Title of Invention	AN APPARATUS AND METHOD FOR TRANSMITTING INFORMATION BIT SEQUENCES FROM A BS (BASE STATION) TRANSMITTER TO A PLURALITY OF USERS
Abstract	This invention relates to an apparatus for transmitting information bit sequences from a BS (Base Station) transmitter to a plurality of users, comprising; a first set of S/P (Serial parallel) converters for dividing each of the information bits received in sub-channel units into a plurality of information bit sequences in response to the respective users; a plurality of channelizers for spreading the divided information bit sequences using different codes, combining this spread information bit sequences into a single sequence associated with the individual users, and outputting the single sequence; a second set of S/P converters for dividing the single sequence, distributing the divided sequences over a plurality of bandwidths capable of mapping-processing the divided sequences with sub-carrier frequencies; a frequency hopper for frequency hopping for preventing each of the bandwidths from overlapping with time-frequency cells given by the given interval; and an IFT (Inverse Fourier Transform) unit for IFT-processing the divided sequences outputting from the frequency hopper, and generating the IFT-processed result.

Title of Invention

AN APPARATUS AND METHOD FOR TRANSMITTING INFORMATION BIT SEQUENCES FROM A BS (BASE STATION) TRANSMITTER TO A PLURALITY OF USERS

Abstract

This invention relates to an apparatus for transmitting information bit sequences from a BS (Base Station) transmitter to a plurality of users, comprising; a first set of S/P (Serial parallel) converters for dividing each of the information bits received in sub-channel units into a plurality of information bit sequences in response to the respective users; a plurality of channelizers for spreading the divided information bit sequences using different codes, combining this spread information bit sequences into a single sequence associated with the individual users, and outputting the single sequence; a second set of S/P converters for dividing the single sequence, distributing the divided sequences over a plurality of bandwidths capable of mapping-processing the divided sequences with sub-carrier frequencies; a frequency hopper for frequency hopping for preventing each of the bandwidths from overlapping with time-frequency cells given by the given interval; and an IFT (Inverse Fourier Transform) unit for IFT-processing the divided sequences outputting from the frequency hopper, and generating the IFT-processed result.

Full Text	BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transmission apparatus and method for use in a mobile communication system based on an OFDM (Orthogonal Frequency Division Multiplexing) scheme, and more particularly to a transmission apparatus and method for supporting a multiple access scheme on the basis of the OFDM scheme. 2. Description of the Related Art Recently, mobile communication systems have developed from mobile systems for providing a user with voice signals to a wireless packet communication system for providing the user with high-speed and high-quality wireless data packets, such that anyone can use a variety of data services and multimedia services. The third-generation mobile communication system is classified into an asynchronous 3GPP (3rd Generation Partnership Project), and a synchronous 3GPP2, each of which are being standardized for implementing high-speed and high-quality wireless packet communication services. For example, an HSDPA (High Speed Downlink Packet Access) standardization is in progress in the 3GPP, and a IxEV-DV (lxEvolution Data and Voice) standardization is in progress in the 3GPP2. The IxEV-DV standardization for the downlink is "IS-2000 Release C". Presently, the standardization of the uplink is in progress, and the uplink is being standardized under the title "IS-2000 Release D". The aforementioned standardizations are needed for users or subscribers to receive high-speed (more than 2Mbps) and high-quality wireless data packet transmission service in the third-generation mobile communication systems. A fourth-generation mobile communication system is needed for users or subscribers to receive higher-speed and higher-quality multimedia communication services. Technical solutions for providing high-speed and high-quality wireless data packet services require improved software capable of developing more diverse and abundant contents and improved hardware capable of developing wireless access technology, which can provide users with excellent services and has high spectrum efficiency. The aforementioned improved hardware, from among the technical solutions, will firstly be described. The high-speed and high-quality data service available in wireless communication is generally deteriorated by channel environments. Channel environments for wireless communication are frequently changed by a variety of factors, for example, white noise, variation in reception signal power, shadowing, movement of a Subscriber Station (SS), a Doppler effect caused by a frequent change in speed, and interference caused by other users or a multi-path signal. Therefore, in order to provide the aforementioned high-speed wireless data packet service, technology improvements over the second-generation or third-generation mobile communication systems, and which improves adaptive capacity for channel variation, is required. Although a high-speed power control scheme for use in the conventional system enhances adaptive capacity for such channel variation, the 3GPP and the 3GPP2 which are currently processing a high-speed data packet transmission system standard commonly utilize an Adaptive Modulation and Coding (AMC) scheme and a Hybrid Automatic Repeat Request (HARQ) scheme. The AMC scheme changes a modulation scheme and a code rate of a channel encoder according to a variation in the downlink channel. In this case, downlink channel quality information can generally be obtained by measuring a Signal-to-Noise Ratio (SNR) of a signal using the SS functioning as a terminal receiver. The SS transmits the channel quality information to a BS (Base Station) through an uplink. The BS predicts the downlink channel conditions on the basis of the downlink channel quality information, and prescribes an appropriate modulation scheme and a code rate for a channel encoder on the basis of the predicted downlink channel condition. Therefore, an Adaptive Modulation and Coding (AMC) system adapts a high-order modulation scheme and a high code rate to an SS (Subscriber Station) having an excellent channel. However, the AMC system adapts a low-order modulation scheme and a low code rate to an SS having a relatively inferior channel. Typically, the SS having the excellent channel may be positioned in the vicinity of the BS, and an SS having the relatively inferior channel may be positioned at a cell boundary. The aforementioned AMC scheme can largely reduce an interference signal as compared to a conventional scheme dependent on a high-speed power control, resulting in the improvement of system performance. If an unexpected error occurs in an initial transmission data packet, the HARQ scheme requires retransmission of the data packet to compensate for the erroneous packet. In this case, a predetermined link control scheme is adapted to the compensation process of the erroneous packet, and is considered to be equal to the HARQ scheme. The HARQ scheme is called a Chase Combining (CC) scheme, and is classified into a Full Incremental Redundancy (FIR) scheme and a Partial Incremental Redundancy (PIR) scheme. The CC scheme transmits all of the packets during a retransmission operation in the same manner as in an initial transmission process. In this case, a reception end combines the retransmission packet with the initial transmission packet to increase reliability of a coded bit received in a decoder, such that the reception end can obtain an overall system performance gain. In this case, if two equal packets are combined with each other, an effect similar to that of an iterative coding occurs, and a performance gain of about 3dB can be attained on average. The FIR scheme retransmits a packet composed of only redundant bits generated from a channel encoder, instead of retransmitting the same packet, such that the FIR scheme can improve a coding gain of a decoder included in the reception end. That is, the decoder uses both initial transmission information and new redundant bits during a decoding process, resulting in an increased coding rate. As a result, the decoder's performance can also be improved. It is well known in coding theory that a performance gain obtained by a low coding rate is greater than a performance gain obtained by an iterative coding rate. Therefore, when considering only the performance gain, the FIR scheme provides better performance than that of the CC scheme. The PIR scheme transmits a data packet which is composed of a combination of information bits and new information bits during a retransmission time. The PIR scheme combines the information bits with the initial transmission information bits during a decoding process, such that it can obtain an effect similar to that of the C scheme. Also, the PIR scheme performs the decoding process using the redundant bits, such that it can obtain effects similar to those of the FIR scheme. The PIR scheme has a coding rate greater than that of the FIR scheme, such that it's the PIR scheme performance is considered to be intermediate between individual performances of the FIR and C schemes. However, the HARQ scheme must consider a variety of factors related to performance and system complexity (e.g., a buffer size and a signaling etc.), such that it is difficult to determine either one of the factors. Provided that the AMC scheme and the HARQ scheme use independent techniques capable of improving the adaptive capacity for a channel variation or are combined with each other, system performance can be greatly improved. In other words, if a modulation scheme suitable for the downlink channel conditions and a coding rate of the channel encoder are determined by the AMC scheme, a data packet corresponding to the determined information is transmitted. However, although the aforementioned two schemes are used, the principal problem encountered in radio communication, i.e., the lack of radio resources, is incapable of being solved. In more detail, multiple access - based technology having a superior spectrum efficiency must be developed to maximize subscriber capacity and to enable high-speed data transmission request for a multimedia service. The publication ("Multicarrier CDMA with Adaptive Frequency Hopping for Mobile radio Systems". By Chen discloses an apparatus for transmitting information bit sequences from a BS (Base Station) transmitter to a plurality of users, comprising: a plurality of channelizers for dividing a single frame of information bit sequences to be transmitted to individual users into a plurality of division times according to a given time interval, dividing the information bit sequences within the plurality of division times, spreading the divided information bit sequences using different Walsh codes, combining the spread information bit sequences into a single sequence associated with the individual users, and outputting the single sequence (page 1853, column 1, last full paragraph); and a frequency hopper for dividing the single sequence, distributing the spread information bit sequences over a plurality of bandwidths capable of mapping - processing the spread information bit sequences with sub-carrier frequencies, and preventing each of the bandwidths from overlapping with time-frequency cells given by the given time interval (page 1583, column 2, first full paragraph). KR-2001-16948 (Song) relates to an orthogonal code jump multiplexing communication device and a method which are provided to effectively utilize limited resources using the orthogonal code jump multiplexing technique when activity of synchronized channels, which hold orthogonal characteristics, is low. In addition, by diffusing or not diffusing according to the jump pattern which a transceiver gives to a user removing an unnecessary channel assigned and return processes, waste by unnecessary controlling signal transmission and a buffer capacitance and data transfer delay, which are small compared to buffer capacitance as in a first communication station, are reduced. Song relates to a statistic multiplexing scheme and apparatus utilizing an orthogonal code jump method in a wire/wireless communication system which is synchronized through a single medium and a plurality of communication channels which exist together. D does not disclose the characteristic of the present invention having a strong characteristic of selecting fading, rather than a multiplexing scheme on the basis of an OFDM (Orthogonal Frequency Division Multiplexing) scheme, through a characteristic if a CDMA scheme and a frequency jump. EP 1039683 an orthogonal frequency division multiplexing (OFDM) based spread spectrum multiple access system in which the entire bandwidth is divided into orthogonal tones, and all of the orthogonal tones are reused in each cell. To reduce peak-to-average ratio at the mobile transmitter, each voice user is allocated preferably a single one, but no more than a very small number, of the orthogonal tones for use in communicating with the base station. Data users are similarly allocated tones for data communication, however, the number of tones assigned for each particular data user is a function of the data rate for that user. The tone assignment for a given user is not always the same within the available band, but instead the tones assigned to each user are hopped over time. More specifically, in the downlink, the tones assigned to each user are change relatively rapidly, e.g., from symbol to symbol, i.e., the user fast "hops" from one tone to another. However, in the uplink, preferably slow hopping is employed to allow efficient modulation of the uplink signal which necessitates the employing of additional techniques, such as interleaving, to compensate for the reduction in the intercell interference averaging effect. For data communication power control is employed in the uplink and/or downlink so that the transmission rate is increased, e.g., by increasing the number of symbols transmitted per tone per unit time or the coding rate, as a function of allocated power per tone and the corresponding channel attenuation. US 20040219920 discloses a method for rate selection by a communication device for enhanced uplink during soft handoff in a wireless communication system includes a first step of receiving information from a scheduler. This information can included one or more of scheduling, a rate limit, a power margin limit, and a persistence. A next step includes determining a data rate for an enhanced uplink during soft handoff using the information. A next step includes transmitting to a serving base station on an enhanced uplink channel at the data rate determined from the determining step. US 20030152023 discloses a wireless transmitter (TXi) which comprises circuitry for providing a plurality of control (CONTROL) bits and circuitry for providing a plurality of user (USER) bits. The transmitter also comprises circuitry for modulating (16) the plurality of control bits and the plurality of user bits into a stream of complex symbols and circuitry (18) for converting the stream of complex symbols into a parallel plurality of complex symbol streams. The transmitter also comprises circuitry (20) for performing an inverse fast Fourier transform on the parallel plurality of complex symbol streams to form a parallel plurality of OFDM symbols and circuitry (22) for converting the parallel plurality of OFDM symbols into a serial stream of OFDM symbols. Each OFDM symbol in the serial stream of OFDM symbols comprises a plurality of data points, and selected (SF.sub.2.x) OFDM symbols in the serial stream of OFDM symbols carry modulation information (AMOD). The modulation information in one or more of the selected OFDM symbols comprises a plurality of modulation groups, and the plurality of modulation groups comprises a number of modulation parameters that describe modulation of a corresponding set of data points in a subsequent OFDM symbol in the serial stream of OFDM symbols. US2002159422 describes a method and apparatus for wireless communication are described. In one embodiment, a method for communicating with a subscriber comprises transmitting orthogonal frequency domain multiplexing (OFDM) signals to the subscriber, and receiving direct-sequence spread spectrum (DSSS) signals from the subscriber. In conclusion, a new multiple access scheme having superior spectrum efficiency must be developed to provide the high-speed and high-speed and high-quality packet data service. SUMMARY OF THE INVENTION Therefore, the present invention has been made in view of the above and other problems, and it is an object of the present invention to provide an apparatus and method for providing wide-band spectrum resources needed for a high- speed wireless multimedia service indicative of the objective of the next- generation mobile communication system. It is another object of the present invention to provide a multiple access scheme and associated transmitter for effectively using time-frequency resources. It is yet another object of the present invention to provide an effective multiple access scheme and a time-frequency resource utilization method which can effectively provide a high-speed wireless multimedia service indicative of the objective of the next-generation mobile communication system. It is yet further another object of the present invention to provide a multiple access scheme which includes both characteristics of a CDMA scheme and characteristics of a frequency hopping scheme on the basis of an OFDM (Orthogonal Frequency Division Multiplexing) scheme, and a transmitter for use in the multiple access scheme. It is yet further another object of the present invention to provide a forward channel configuration in a multiple access scheme which includes both characteristics of a CDMA scheme and characteristics of a frequency hopping scheme on the basis of an OFDM scheme. It is yet further another object of the present invention to provide a multiple access scheme which combines portions of an OFDM scheme, a CDMA scheme, and a frequency hopping scheme, and a transmitter for use in the multiple access scheme. It is yet further another object of the present invention to provide a multiple access scheme for differentially assigning time-frequency resources to individual users, and a transmitter for use in the multiple access scheme. It is yet further another object of the present invention to provide a multiple access scheme for differentially assigning time-frequency resources to individual services corresponding to individual users, and a transmitter for use in the multiple access scheme. In accordance with one aspect of the present invention, the above and other objects can be accomplished by the provision of an apparatus for transmitting information bit sequences from a BS (Base Station) transmitter to a plurality of users, comprising a plurality of channelizers for dividing a single frame time of information bit sequences to be transmitted to individual users into a plurality of times according to a given time interval, dividing the information bit sequences within the plurality of division times, spreading the divided information bit sequences using different Walsh codes, combining the spread information bit sequences into a single sequence associated with the individual users, and outputting the single sequence; and a frequency hopper for dividing the single sequence, distributing the spread information bit sequences over a plurality of bandwidths capable of mapping-processing the spread information bit sequences with sub-carrier frequencies, and preventing each of the bandwidths from overlapping with time-frequency cells given by the given time interval. In accordance with another aspect of the present invention, there is provided a method for transmitting information bit sequences from a BS (Base Station) transmitter to a plurality of users, comprising the steps of a) dividing a single frame time of information bit sequences to be transmitted to individual users into a plurality of times according to a given time interval, dividing the information bit sequences within the plurality of division times, spreading the divided information bit sequences using different Walsh codes, combining the spread information bit sequences into a single sequence associated with individual users, and outputting the single sequence; and b) dividing the information bit sequences, which have been combined into the single sequence in step (a), distributing the spread information bit sequences over a plurality of bandwidths capable of mapping-processing the spread information bit sequences with sub-carrier frequencies, and perfanning a frequency hopping function such that each of the bandwidths does not overlap with the time-frequency cells given by the given time interval. In accordance with yet another aspect of the present invention, there is provided a transmission apparatus for use in a mobile communication system capable of transmitting information bit sequences from a BS (Base Station) transmitter to a plurality users, comprising a plurality of traffic channel transmitters for dividing a modulation data symbol sequence corresponding to a predetermined user into division modulation data symbol sequences, the number of which is equal to the number of sub-channels assigned to the predetermined user, spreading the respective division modulation data symbol sequences using different channelization codes, and performing a mapping-process with sub-carriers comprising a corresponding sub-channel; a TDM (Time Division Multiplexer) for receiving a first input signal from the traffic channel transmitters, the first input signal including traffic channel signals from the traffic channel transmitters, a pilot channel signal, and sync (synchronous) and shared channel signals, which have been spread by a predetermined channelization code and have been modulated by a predetermined modulation scheme, and receiving a preamble channel signal as a second input signal, such that the first input signal and the second input signal are selected in time-domain units of the sub-channel; and an IFT (Inverse Fourier Transform) unit for IFT-processing a signal selected by the TDM, and generating the IFT-processed result. In accordance with yet further another aspect of the present invention, there is provided a transmission method for use in a mobile communication system capable of transmitting information bit sequences from a BS (Base Station) transmitter to a plurality of users, comprising the steps of a) dividing a modulation data symbol sequence corresponding to a predetermined user into division modulation data symbol sequences, the number of which is equal to the number of sub-channels assigned to the predetermined user, spreading the respective division modulation data symbol sequences using different channelization codes, and performing a mapping-process in association with sub-carriers comprising a corresponding sub-channel; b) multiplexing a first input signal and a second input signal such that the first input signal and the second input signal are selected in time-domain units of the sub-channel; wherein the first input signal includes traffic channel signals, a pilot channel signal, and sync (synchronous) and shared channel signals, which have been spread by a predetermined channelization code and have been modulated by a predetermined modulation scheme, and a preamble channel signal is the second input signal, and c) IFT (Inverse Fourier Transform) - processing a signal selected at step (b), and generating the IFT-processed result. In accordance with yet further another aspect of the present invention, there is provided a transmission method for use in a mobile communication system based on a multiple access scheme, comprising the steps of a) assigning at least one sub-channel to a predetermined user, spreading data of the predetermined user using prescribed encoded codes associated with individual sub-carriers comprising the sub-channel; b) in association with individual output data of the sub-channels, assigning different sub-carriers for every time interval, a unit of which is determined to be each of the sub-channels in a time domain; and c) IFT (Inverse Fourier Transform) - processing the data in the assigned sub-carrier areas such that it is converted into time-domain data. BRIEF DESCRIPTION OF THE ACCOMPAYING DRAWINGS The above and other objects, features and other advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which: Fig. 1 is a diagram illustrating an exemplary utilization of a time-frequency resource in accordance with the present invention; Fig. 2 is a block diagram of a transmitter for use in a mobile communication system of a multiple access scheme in accordance with the present invention; Fig. 3 is a detailed block diagram of a channelizer of Fig. 2 in accordance with the present invention; Fig. 4 is a diagram illustrating an example of effectively using time-frequency resources in accordance with the present invention; Fig. 5 is a block diagram of forward channels capable of providing a high-speed wireless multimedia service in accordance with the present invention; Fig. 6 is a detailed block diagram of a transmitter capable of supporting a multiple access scheme in accordance with the present invention; and Fig. 7 is a block diagram of a transmitter processing an output signal of the transmitter shown in Fig. 6 in accordance with the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Now, preferred embodiments of the present invention will be described in detail with reference to the annexed drawings. In the drawings, the same or similar elements are denoted by the same reference numerals even though they are depicted in different drawings. In the following description, a detailed description of known functions and configurations incorporated herein will be omitted when it may obscure the subject matter of the present invention. The present invention provides a multiple access method accompanied by an effective use of time-frequency resources so as to implement a high-speed wireless multimedia service indicative of the objectives of the next-generation mobile communication system, and a transmitter for use in the multiple access method. A wide-band spectrum resource is needed for a high-speed wireless multimedia service indicative of the objectives of the next-generation mobile communication system. However, when using the wide-band spectrum resources, a wireless transmission path makes the fading phenomenon prominent due to a multipath propagation, and a frequency-selective fading phenomenon can also be easily observed even in a transmission band. Therefore, in order to implement the high-speed wireless multimedia service, an OFDM scheme having very strong resistance to the frequency-selective fading phenomenon is better than the conventional CDMA scheme, such that many developers are recently conducting intensive research into the OFDM scheme. Typically, the OFDM scheme enables sub-channel spectrums to maintain mutual orthogonality therebetween, and also enables the sub-channel spectrums to be overlapped with each other, resulting in excellent spectrum efficiency. Also, the OFDM scheme implements a modulation process using an IFFT (Inverse Fast Fourier Transform), and implements a demodulation process using an FFT (Fast Fourier Transform). For example, the multiple access scheme based on the OFDM scheme may be determined to be an OFDM scheme for assigning some part of an overall sub-carrier to a specific user. The OFDM scheme does not require a spreading sequence for bandwidth spreading. The OFDM scheme can dynamically change the set of sub-carriers assigned to a specific user according to fading characteristics of a wireless transmission path, and this operation of the OFDM scheme is typically referred to as "dynamic resource allocation" or "frequency hopping". The multiple access scheme requiring the spreading sequence is classified into a spreading scheme in a time domain and a spreading scheme in a frequency domain. The spreading scheme in the time domain performs spreading of a user signal in the time domain, and controls the spreading signal to be mapping-processed with a sub-carrier. The spreading scheme in the frequency domain performs demultiplexing of a user signal in the frequency domain, controls the demultiplexing signal to be mapping-processed with a sub-carrier, and distinguishes user signals using orthogonal sequences. The following multiple access scheme according to the present invention can implement a characteristic of the multiple access scheme based on an OFDM scheme, a characteristic of the CDMA scheme, and a characteristic of the frequency hopping scheme which has very strong resistance to the frequency selective fading. It should be noted that the aforementioned new multiple access scheme is called a Frequency Hopping-Orthogonal Frequency Code Division Multiple Access (FH-OFCDMA) scheme. Fig. 1 is a diagram illustrating an exemplary utilization of time-frequency resources in accordance with the present invention. In Fig. 1, the abscissa is the time domain, and the ordinate is the frequency domain. As to the multiplex access scheme capable of supporting K users by properly utilizing time-frequency resources, reference numeral 101 is a time-frequency resource assigned to a first user, reference numeral 102 is a time-frequency resource assigned to a second user, reference numeral 103 is a time-frequency resource assigned to a third user, and reference numeral 104 is a time-frequency resource assigned to a K-th user. The time-frequency resource assigned to every user is determined by a predetermined bandwidth and a predetermined time. The bandwidth may be assigned according to category information of services required by each user. For example, a wide bandwidth is assigned to a user who has requested a service (e.g., a high-speed packet data service, etc.) requiring a large amount of time-frequency resources. However, a narrow bandwidth is assigned to a user who has requested a service (e.g., a voice service, etc.) requiring a small amount of time-frequency resources. The aforementioned bandwidth assignment means that time-frequency resources can be differentially assigned to individual users. In Fig. 1, in comparison with the second user, the remaining users are each assigned a relatively wide bandwidth. Particularly, the widest bandwidth is assigned to the K-th user from among all of the users. In the case of comparing the time-frequency resources 101 assigned to the first user with the time-frequency resources 103 assigned to the third user, a relatively large amount of time resources are assigned to the first user rather than the third user. If the widest bandwidth is assigned to the K-th user, this means that the K-th user currently uses a service requiring much more time-frequency resources as compared to the remaining users. The bandwidths BW1, BW2, BW3, and BWk can be represented by the following Equations 1 to 4. BW1 n1 = M1 x m (1) where M1 is the number of sub-channels assigned to the first user, m is the number of sub-carriers comprised of a single sub-channel, and n1 is a total number of sub-carriers assigned to the first user. BW2 n2 = M2xm (2) where M2 is the number of sub-channels assigned to the second user, and m is the number of sub-carriers comprised of a single sub-channel, and n2 is a total number of sub-carriers assigned to the second user. BW3 n3 = M3 x m (3) where M3 is the number of sub-channels assigned to the third user, and m is the number of sub-carriers comprised of a single sub-channel, and n3 is a total number of sub-carriers assigned to the third user. BWk nk = Mk x m (4) where Mk is the number of sub-channels assigned to the k-th user, and m is the number of sub-carriers comprised of a single sub-channel, and nk is a total number of sub-carriers assigned to the k-th user. As can be seen from the aforementioned Equations 1 to 4, the bandwidth is determined by multiplying the number (nk) of overall sub-carriers assigned to the k-th user by the bandwidth fsc of respective sub-carriers. The number nk of all sub-carriers assigned to the k-th user is determined by multiplying the number (Mk) of sub-channels assigned to the k-th user by the spreading factor, which is equal to the product of the sub-carriers which comprise the k-th sub-channel. Therefore, if the number of sub-channels assigned to a user is adjusted, a bandwidth usable by the user can also be adjusted. In this case, the above operation in which the bandwidth is assigned considering both service requirements and available time-frequency resources of a corresponding user is called a scheduling algorithm. Although the present invention does not disclose an embodiment of the scheduling algorithm, it is not limited to any a specific embodiment of the scheduling algorithm, and as such may employ any kind of scheduling algorithms. The bandwidth assignment for every user must be performed within a total bandwidth BWT predetermined in a frequency domain. The number (M) of all sub-carriers available in the total bandwidth BWT and the number (nk) of sub-carriers assigned to respective users can both be represented by the following Equation 5: Fig. 2 is a block diagram of a transmitter for use in a mobile communication system of a multiple access scheme in accordance with the present invention. A detailed configuration of a transmitter for supporting the aforementioned time-frequency resource utilization shown in Fig. 1 is shown in Fig. 2. It is assumed that the transmission of signals (d1, d2,..., dk) associated with the K users is shown in Fig. 2 in the same manner as in Fig. 1. Also, it is assumed that the signals (d1, d2,..., dk) associated with the K users have already been channel-encoded and data-modulated. For reference, in the case of classifying users in the following description, k is indicative of an arbitrary user from among all the users, and K is indicative of a total number of users. For example, if 10 users exist, K is 10, and k is adapted to determine an arbitrary user from among 10 users. Referring to Fig. 2, the signals (d1, d2,..., dk) associated with respective users are transmitted to corresponding time delay controllers 201, 211, and 221. In more detail, a sequence d1 of the first user signal is transmitted to the first time delay controller 201, a sequence d2 of the second user signal is transmitted to the second time delay controller 211, and a sequence dK of the Kth user signal is transmitted to the K-th time delay controller 221. The time delay controllers 201, 221, and 221 can adjust a relative start point in the time domain of the time-frequency resource for every user. For example, assuming that the assignment of the tirrie-frequency domain for every user is established as in Fig. 1, the first time delay controller 201 will adjust a relative start point in the time domain of the first time-frequency resource 101 assigned to the first user. After the time delay controllers 201, 211, 221 output signals for every user, which adjust a relative start point, the signals for every user are transmitted to Serial/Parallel (S/P) converters 202, 212, and 222 corresponding to the time delay controllers 201, 211, and 221, respectively. The S/P converters 202, 212, and 222 output the signals for every user in parallel in the form of sequences equal to the predetermined number of branches (n1; n2,..., nk). The number of different branches (n1≠ n2 ≠,..., ≠nK) may be assigned to the S/P converters 202, 212, and 222, or the number of same branches (n1= n2 =... =nK) may also be assigned to the S/P converters 202, 212, and 222. In this case, signals for every branch generated from the S/P converters 202, 212 and 222 have durations which increase by the predetermined number of branches (n1, n2,..., nk) as compared to a corresponding entry signal. The output signals of the S/P converters 202, 212, and 222 are transmitted to channelizers 203, 213, and 223. The channelizers 203, 213, and 223 are spread in a time domain while being classified according to entry signals equal to the predetermined number of branches. Thereafter, the spread signals are summed, such that a single spread signal is created. Detailed descriptions of the channelizers 203, 213, 223 will be given with reference to Fig. 3. The output signals of the channelizers 203, 213, and 223 are transmitted to the S/P converters 204, 214, and 224. The S/P converters 204, 214, and 224 convert the signal to a parallel signal, and output the output signals of the channelizers 203, 213, and 223 in the form of sequences equal to the predetermined number of branches (n1, n2,..., nk). In this case, signals for every branch generated form the S/P converters 204, 214, and 224 are set to a duration which is greater than that of a corresponding entry signal by the predetermined numbers of branches (n1, n2,..., nk). Therefore, user signals generated from the S/P converters 204, 214, and 224 through the S/P converters 202, 212, and 222 and the channelizers 203, 213, and 223 may be considered to be signals processed by a CDMA scheme. The number of branches (n1, n2,..., nk) predetermined for respective S/P converters 202, 212, and 222 at a first end is equal to the number of branches (n1, n2,..., nk) predetermined for respective S/P converters 204, 214, and 224 at a second end, as shown in Fig. 2, but it should be noted that the present invention is not limited to the above embodiment shown in Fig. 2. For example, the number of branches (n1, n2,..., nk) predetermined for respective S/P converters 202, 212, and 222 at the first end may be different from the number of branches (n1, n2,..., nk) predetermined for respective S/P converters 204, 214, and 224 at the second end. Output signals of the S/P converters 204, 214, and 224 are transmitted to a frequency hopper 231. The frequency hopper 231 can dynamically change the set of sub-carriers assigned for every user according to fading characteristics of a wireless transmission path. In more detail, the frequency hopper 231 may be considered to be a configuration capable of hopping a frequency of a signal to be transmitted. The time-frequency resource utilization example shown in Fig. l may be accompanied by fading characteristics encountered at a specific time. The time delay controllers 201, 211, and 221 are separated from the frequency hopper 231 in Fig. 2. However, the frequency hopper 231 may include the time delay controllers 201, 211, and 221 if needed, such that it can adjust the time delays for every user signal. In this case, the time delay controllers 201, 211, and 221 may be omitted. Although the present invention does not describe a detailed frequency hopping pattern needed for the frequency hopper 231, a variety of frequency hopping patterns available for the frequency hopper 231 can be proposed within a predetermined range in which there is no overlapping of the set of sub-carriers assigned for every user. The output signal of the frequency hopper 231 is transmitted to an Inverse Fourier Transform (IFT) unit 232. The IFT unit 232 converts the output signal of the frequency domain into another signal of the time domain, and outputs the signal of the time domain. The IFT unit 232 may adapt the OFDM scheme to a signal to be transmitted. The transmission signal converted into the time-domain signal by the IFT unit 232 is transitioned to a Radio Frequency (RF) band, and is then transmitted to a target. Fig. 3 is a detailed block diagram of each channelizer 203, 213, or 223 of Fig. 2 in accordance with the present invention. It is assumed that the following description relates to the K-th channelizer 223 for the K-th user signal. Referring to Figs. 2 and 3, the K-th user signal is converted into nk sequences using the S/P converter 222. The first sequence n(k,1) from among nk sequences (n(k,2), n(K,2).... n(K,K) is transmitted to a first spreading unit 302, and is multiplied by an orthogonal sequence W0, such that it is spread. The second sequence n(K,2) from among the nk sequences (n(k,1), n(k,2),...., n(K,K)) is transmitted to a second spreading unit 303, and is multiplied by an orthogonal sequence W1, such that it is spread. The n-th sequence n(K,n) from among the nk sequences (n(K,1), n(K,2)..., n(K,K)) is transmitted to an n-th spreading unit 304, and is multiplied by an orthogonal sequence Wn-1, such that it is spread. If the aforementioned spreading using different orthogonal sequences for every entry sequence is performed, interference does not occur in the entry sequences. The n spreading signals generated from the first to n-th spreading units 302, 303, and 304 are transmitted to an adder 305. The adder 305 sums the spreading signals, and outputs a sequence of a single spreading signal. The spreading signal generated from the adder 305 is transmitted to a scrambler 306. The scrambler 306 receives a scrambling sequence as another entry signal, and multiplies the spreading signal by the scrambling sequence, and outputs a scrambled signal. The scrambler 306 prevents interference from being generated due to the frequency hit phenomenon wherein a corresponding signal is overlapped with an output signal of a nearby BS (Base Station) in a frequency domain under cellular environments. The scrambler 306 is introduced as a method for improving reception performance of the corresponding signal. If the influence of an interference signal transmitted from the nearby BS is negligible, the scrambler 306 may be omitted if needed. Fig. 3 depicts a detailed configuration of the channelizer 223 associated with m sequences (i.e. first sequences) to be transmitted over the same sub-channel from among the nk sequences (n(K,1), n(K,2), ..., n(K,K)) equal to the output signals of the S/P converter 222 of Fig. 2. In more detail, Fig. 3 depicts some parts of the channelizer 223 of Fig. 2. The remaining sequences from among the nk sequences (n(K,1), n(K,1),..., n(K,K)) equal to the output signals of the S/P converter 222 of Fig. 2 are grouped in n units. The n grouped sequences are channelized as in Fig. 3, and are transmitted over different sub-channels. As can be seen from the description of the transmitter shown in Figs. 2 and 3, the multiple access method according to the present invention can implement a characteristic of the multiple access scheme based on an OFDM scheme, a characteristic of the CDMA scheme, and a characteristic of the frequency hopping scheme which has very-strong resistance to the frequency selective fading. Fig. 4 is a diagram illustrating an example of effectively using the time-frequency resource in accordance with the present invention. In Fig. 4, a unit square is comprised of a predetermined number of sub-carriers, and is referred to as a Time-Frequency Cell (TRC) having the same duration as the OFDM symbol interval. A plurality of sub-carriers are assigned to the TFC. Data corresponding to respective sub-carriers assigned to the TFC is processed by the CDMA scheme, and is then processed by the OFDM scheme using the respective sub-carriers. In the case of using the CDMA scheme, data is spread by a predetermined channelization code prescribed for every sub-carrier, and the spread data is scrambled by a prescribed scrambling code. In Fig. 4, a Frame Cell (FC) is defined as a time-frequency domain having both a bandwidth fFC equal to a predetermined multiple (e.g., 32 times) of the TFC, and a frame duration equal to a predetermined multiple (e.g., 16 times) of the TFC. If the FC is adapted to the present invention, the measurement result of wireless transmission is not frequently reported during the application time of the AMC technology. Fig. 4 depicts two different sub-channels contained in a single FC, i.e. a sub-channel A and a sub-channel B. The two different sub-channels may be assigned to different users, respectively, or may also be assigned to one user. The respective sub-channels are frequency-hopping-processed by a predetermined frequency interval according to a change in time. This means that sub-channels assigned to respective users are dynamically changed according to fading characteristics varying with time. Fig. 4 depicts an example of a certain pattern of the frequency hopping pattern. However, the present invention is not always limited to the exemplary pattern of Fig. 4, as the frequency hopping pattern of the present invention can be defined in various ways as needed. In the case of using the AMC technology, an SS (Subscriber Station) measures a current state of a wireless transmission path at predetermined time intervals, and reports the measurement result to a BS (Base Station). Upon receipt of the wireless transmission path state information from the SS, the BS changes the AMC scheme. The changed AMC scheme is reported to the SS. Then, the SS transmits a signal to a desired target using the modulation and coding schemes as changed by the BS. The present invention reports the wireless transmission path state information in FC units, such that it can reduce load encountered by the AMC technology. The FC can be properly adjusted. according to the amount of overhead information encountered by the AMC technology. For example, if a large amount of overhead information exists, the FC is widened. If a small amount of overhead information exists, the FC is narrowed. A transmitter for providing a specific user with a service can generally use a plurality of sub-channels. QoS (Quality of Service) and the number of simultaneous users must be considered in order to use the plurality of sub-channels. Fig. 5 is a block diagram of forward channels capable of providing a high-speed wireless multimedia service in accordance with the present invention. In more detail, a forward channel for an FH-OFCDMA(Frequency Hopping-Orthogonal Frequency Code Division Multiple Access) scheme indicative of a multiple access scheme proposed by the present invention is defined as a "FORWARD FH-OFCDMA CHANNEL" in Fig. 5. The "FORWARD FH-OFCDMA CHANNEL" may be comprised of a pilot channel, a synchronous (sync) channel, a preamble channel, a traffic channel, and a shared control channel, or may also be comprised of only the preamble channel. An example of the "FORWARD FH-OFCDMA CHANNEL" will be described with reference to Figs. 6 and 7. The pilot channel may allow an SS to acquire a BS, or may be adapted to perform channel estimation. The sync channel may allow the SS to acquire BS information and timing information. The preamble channel is basically adapted to perform frame synchronization, or may also be adapted to perform channel estimation. The traffic channel is adapted as a physical channel for transmitting information data. Although the preamble channel is separately denoted in Fig. 5 to establish frame synchronization, the preamble information transmitted over the preamble channel may be transmitted as a preamble of a frame transmitted over the traffic channel if needed. The shared control channel is used as a physical channel for transmitting control information needed for receiving the information data transmitted over the traffic channel. Fig. 6 is a detailed block diagram of an exemplary transmitter which implements the channel configuration of Fig. 5. Transmitters of individual channels shown in Fig. 5 are shown in Fig. 6. The transmitters of individual channels will hereinafter be described with reference to Fig. 6. Regarding a transmitter for transmitting user data over the traffic channel, a sequence of coded bits of the k-th user is generated from a channel encoding process (not shown), and is then transmitted to a modulator 601. The modulator 601 modulates the coded bits using a QPSK, 16QAM, or 64QAM modulation scheme, and outputs modulation symbols. In the case of using the AMC scheme, the modulation scheme used by the modulator 601 is determined by the BS according to current wireless transmission path state information. A plurality of modulation symbols generated from the modulator 601 each have a complex value. The modulation symbols generated from the modulator 601 are transmitted to the rate matcher 602. A sequence repeat process or a symbol punching process is applied to the modulation symbols received in the rate matcher 602. In more detail, the rate matcher 602 fabricates the modulation symbols to match a transmission format of a packet transmitted over a radio channel, and outputs the fabrication result. In this case, the transmission format includes the number of modulation symbols capable of being transmitted via a single frame. The modulation symbol sequence generated from the rate matcher 602 is transmitted to a first demultiplexer 603, The first demultiplexer 603 demultiplexes the modulation symbol sequence, and outputs modulation symbol sequences for every sub-channel by the predetermined number of branches. The number of branches corresponds to the number (Mk) of sub-channels used for a k-th user service, and Mk may be determined to be a number from 1 to 16. The reference character 'k' a number between 1 and K, and the reference character 'K' is defined as the number of maximum service available users. In this case, the modulation symbol sequences for every sub-channel, which are generated for every branch using the first demultiplexer 603, have predetermined durations. However, this is not related to the duration of the modulation symbol sequence received in the first demultiplexer 603. Upon receipt of modulation symbol sequences for every sub-channel from the first demultiplexer 603, a maximum of Mk sub-channel transmitters is needed to transmit the received modulation symbol sequences over different sub-channels. Therefore, Fig. 6 depicts Mk sub-channel transmitters. Although the sub-channel transmitters are different from each other with respect to the reception modulation symbol sequences, they perform the same operation, such that the following description will relate to only one sub-channel transmitter for the convenience of description. One or more sub-channels may be assigned to traffic channels of respective users, such that one or more sub-channel transmitters may also be adapted to transmit data over the traffic channels of the respective users. The modulation symbol sequences for every sub-channel, which have been received from the first demultiplexer 603, are transmitted to a corresponding second demultiplexer from among Mk second demultiplexers 604 and 614. For example, a modulation symbol sequence corresponding to the first sub-channel from among the modulation symbol sequences for every sub-channel, which have been received from the first demultiplexer 603, is transmitted to a second demultiplexer 604. The second demultiplexer 604 demultiplexes the modulation symbol sequence corresponding to the first sub-channel, and outputs a plurality of modulation symbol sequences for every sub-carrier. The number of modulation symbol sequences for every sub-carrier is equal to the number 'm' of sub-carriers contained in only one sub-channel. In this case, the modulation symbol sequences for every sub-carrier each have a predetermined duration which is greater than of the number of modulation symbols for every sub-channel by 'm' times. The modulation symbol sequences for every sub-carrier, which have been received from the second demultiplexer 604, are transmitted to a channel divider 605. The channel divider 605 spreads the modulation symbol sequences for every sub-carrier using an orthogonal sequence having a predetermined length 'm', and outputs the spread modulation symbol sequences. In this case, the modulation symbol sequences for every sub-carrier will be spread by different orthogonal sequences. Output sequences, in chip units, which have been spread according to individual sub-carriers by the channel divider 605, are transmitted to an adder 606. The adder 606 sums the output sequences for every sub-carrier in chip units, and outputs the added result in the form of a single sequence. The output sequence of the adder 606 is transmitted to a scrambler 607. The scrambler 607 multiplies a scrambling code generated from a scrambling sequence generator 613 by the output sequence of the adder 606, and outputs a scrambled sequence. The aforementioned components from the second multiplexer 604 receiving the modulation symbol sequence to the scrambler 607 generating the scrambled sequence may be equal to components needed for signal processing corresponding to the CDMA scheme. The scrambled sequence is transmitted to a mapping unit 608. The scrambled sequence received in the mapping unit 608 is mapping-processed with sub-carriers comprising a first sub-channel assigned to the scrambled sequence. The mapping unit 608 may perform a frequency hopping function capable of dynamically changing sub-carriers comprising the sub-channel according to fading characteristics of the wireless transmission path. Although the aforementioned description does not disclose a detailed example, it is obvious that sub-channel transmitters corresponding to the remaining sub-channels other than the first sub-channel can output data to individual sub-channels in the same manner as in the aforementioned sub-channel transmitter. Secondly, as to the pilot channel transmitter for transmitting a pilot signal (i.e. unmodulated signal) over a pilot channel, the unmodulated signal is transmitted to a pilot tone position determination unit 621. The pilot tone position determination unit 621 determines a sub-carrier position at which a pilot tone is to be inserted. Therefore, the pilot tone will be inserted into the determined sub-carrier position. Thirdly, as to the synch channel transmitter for transmitting information data over a sync channel, the information data is transmitted to a channel encoder 631. The channel encoder 631 encodes the information data of the sync channel, and outputs the encoded information data. The encoded information data is transmitted to a modulator 632. The modulator 632 modulates the encoded information data according to a predetermined modulation scheme, and outputs the modulation result in the form of sync channel data. Fourthly, as to the shared channel transmitter for transmitting control information over a shared control channel, the control information is transmitted to the channel encoder 641. The channel encoder 641 encodes the control information of the shared control channel, and outputs the encoded control information. The encoded control information is transmitted to a modulator 642. The modulator 642 modulates the encoded control information according to a predetermined modulation scheme, and outputs the modulation result in the form of shared control channel data. Fig. 7 depicts a configuration for the FORWARD FH-OFCDMA CHANNEL in accordance with the present invention. An input end "A" shown in Fig. 7 is connected to an output end "A" shown in Fig. 6, such that a transmitter of the present invention can be implemented. Therefore, output signals of the transmitter of Fig. 6 are transmitted to the input end "A" of Fig. 7. The output signals are comprised of traffic channel data, pilot channel data, sync channel data, and shared control channel data, which are generated from each sub-channel. Referring to Fig. 7, the output signals of Fig. 6 are transmitted to input terminals of a Time Division Multiplexer (TDM) through the input terminal "A". A preamble channel signal is also transmitted to other input terminals of the TDM 701. The TDM 701 TDM-processes the output signals of Fig. 6 and the preamble channel signal, and outputs the TDM-processing result. Referring back to Fig. 4, a single FC is comprised of 16 TFCs in a time domain. The TDM 701 selects/outputs the preamble channel in a first TFC from among the 16 TFCs, and selects/outputs the output signals in the remaining 15 TFCs other than the first TFC. Output signals corresponding to either the preamble channel signal or the remaining channel signals, having been generated from the TDM 701, are transmitted to an IFT (Inverse Fourier Transform) unit 702. The IFT unit 702 IFT-processes its own input signal from among the output signals which correspond to either the preamble channel signal or the remaining channel signals, such that it converts a frequency-domain signal into a time-domain signal. The output signal of the IFT unit 702 is transmitted as "FORWARD FH-OFCDMA CHANNEL" of the present invention. As apparent from me above description, in the case of using a multiple access scheme and time-frequency resource utilization according to the present invention, time-frequency resources can be effectively used, and spectrum efficiency can be maximized. Therefore, it is expected that the present invention will effectively provide a high-speed wireless multimedia service satisfying the objectives of the next-generation mobile communication system. Also, the present invention can implement a characteristic of the multiple access scheme based on an OFDM scheme, a characteristic of a CDMA scheme, and a characteristic of a frequency hopping scheme which has very strong resistance to the frequency selective fading. Although the preferred embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims. WE CLAIM 1. An apparatus for transmitting information bit sequences from a BS (Base Station) transmitter to a plurality of users, comprising: a first set of S/P (Serial parallel) converters for dividing each of the information bits received in sub-channel units into a plurality of information bit sequences in response to the respective users: a plurality of channelizers for spreading the divided information bit sequences using different codes, combining this spread information bit sequences into a single sequence associated with the individual users, and outputting the single sequence; a second set of S/P converters for dividing the single sequence, distributing the divided sequences over a plurality of bandwidths capable of mapping-processing the divided sequences with sub-carrier frequencies; a frequency hopper for frequency hopping for preventing each of the bandwidths from overlapping with time-frequency cells given by the given interval; and an IFT (Inverse Fourier Transform) unit for IFT-processing the divided sequences outputting from the frequency hopper, and generating the IFT - processed result. 2. The apparatus as claimed in claim 1, wherein the number of information bit sequences is equal to the number of sub-carriers comprising a sub- channel. 3. The apparatus as claimed in claim 1, wherein the frequency hoppcr converts sub-carriers assigned to individual sub-channels in a previous time domain into secondary sub-carriers based on a characteristic of a wireless transmission path, such that the frequency hopper performs a frequency hopping function. 4. The apparatus as claimed in claim 1, comprising: a plurality of time delay controllers corresponding to the number of information bit sequences of the users, for adjusting relative start points of the users in a time domain. 5. The apparatus as claimed in claim 1, wherein the plurality of channelizers comprises means for dividing a single frame of information bit sequences to be transmitted to individual users into a plurality of division times according to a given time interval, dividing the information bit sequences within the plurality of division times. 6. The apparatus as claimed in claim 1, wherein the each users is assigned at least one sub-channel according to a QoS (Quality of Services) of the user. 7. The apparatus as claimed in claim 3, wherein the characteristic of the wireless transmission path is reported according to its current condition in Frame Cell (FC) units. 8. A method for transmitting information bit sequences from a BS (Base Station) transmitter to a plurality of users, comprising the steps of: a) dividing each of the information bits received in sub-channel units into a plurality of information bit sequences in response to the respective users; b) dividing a single frame of information bit sequences to be transmitted to individual users into a plurality of times according to a given time interval, dividing the information bit sequences within the plurality of division times, spreading the divided information bit sequences using different orthogonal codes, combining the spread information bit sequences into a single sequence associated with the individual users, and outputting the single sequence; c) dividing the single sequence, distributing the divided sequences over a plurality of bandwidths capable of mapping - processing the divided sequences with sub-carrier frequencies; d) frequency hopping for performing a frequency cells given by the given time interval; and e) IFT (inverse Fourier Transform) - processing the divided sequences, and generating the IDT-processed result. 9. The method as claimed in claim 8, wherein the number of information bit sequences is equal to the number of sub-carriers comprising a sub- channel. 10. The method as claimed in claim 8, wherein the frequency hopping function shifts sub-carriers comprising individual sub-carriers in a previous time domain to secondary sub-carriers. 11. The method as claimed in claim 8, comprising the steps of: f) in response to the information bit sequences of the users, adjusting relative start points of the users in a time domain. 12. The method as claimed in claim 8, wherein step of combining the spread information bit sequences into a single sequence comprises the steps of: summing the spread information bit sequences and generating a single spread information bit sequence; and multiplying the spread information bit sequence by a predetermined scrambling code, and generating a scrambled information bit sequence as the single sequence. 13. The method as claimed in claim 8, wherein the each users is each assigned at least one sub-channel according to a QoS (Quality of Services) of the user. 14.The method as claimed in claim 9, wherein the characteristic of the wireless transmission path is reported according to its current condition in Frame Cell (FC) units. 15. A transmission apparatus for use in a mobile communication system capable of transmitting information bit sequences from a BS (base Station) transmitter to a plurality of users, comprising: a plurality of traffic channel transmitting for dividing a modulation data symbol sequence corresponding to a predetermining user into division modulation data symbol sequences, the number of which is equal to the number of sub-channel assigned to the predetermined user, spreading the respective division modulation data symbol sequences using different channelization codes, and performing a mapping-process with sub-carriers comprising a corresponding sub-channel; a TDM (Time Division Multiplexer) for receiving a first input signal from the traffic channel transmitting, the first input signal including channel signals from the traffic channel transmitters, a pilot signal, and sync (synchronous) and shared channel signals, which have been spread by a predetermined channelization code and have been modulated by a predetermined modulation scheme, and receiving a preamble channel signal as a second input signal, such that the first input signal and the second input signal are selected in time-domain units of the sub-channel; and an IFT (Inverse Fourier Transform) unit for IFT-processing a signal selected by the TDM, and generating the IFT-processed result. 16. The apparatus as claimed in claim 15, wherein the TDM selects the second input signal in a time domain of an initial sub-channel assigned to the predetermined user in a Frame Cell (FC), and selects the first input signal in time-domains of the remaining sub-channels other than the initial sub-channel. 17.The apparatus as claimed in claim 15, wherein each of the traffic channel transmitters comprises: a demultiplexer for dividing each of the division modulation data symbol sequences into a plurality of parts equal to the number of sub-carriers comprising a corresponding sub-channel; a channelizer for spreading the respective divided modulation data symbol sequences, having been divided according to the sub-carriers, using different channelization codes; an added for summing the divided modulation data symbol sequences, having been spread according to the sub-carriers, and generating a singie division modulation data symbol sequence; a scrambler for multiplying the single division modulation data symbol sequence by a predetermined scrambling code, and generating the multiplied result; and a mapping unit for mapping an output signal of the scrambler with individual sub-carriers comprising the corresponding sub-channel. 18. A transmission method for use in a mobile communication system capable of transmitting information bit sequences from a BS (Base Station) transmitter to a plurality of users, comprising the steps of : a) dividing a modulation data symbol sequence corresponding to a predetermined user into division modulation data symbol sequences, the number of which is equal to the number of sub- channels assigned to eth predetermined user, spreading the respective division modulation data symbol sequences using channelization codes, and performing a mapping-process in association with sub-carriers comprising a corresponding sub- channel; b) multiplexing a first input signal and a second input signal such that the first input signal and the second input signal are selected in time-domain units of the sub-channel, wherein the first input signal includes traffic channel signals, a pilot channel signal, and sync (synchronous) and shared channel signals, which have been spread by a predetermined channelization code and have been modulated by a predetermined modulation scheme, and a preamble channel signal is the second input signal; and c) IFT (Inverse Fourier Transform) - processing a signal selected at step (b), and generating the IFT-Processed result. 19. The method as claimed in claim 18, wherein step (b) comprises the step of: bl) selecting the second input signal in a time domain of an initial sub- channel assigned to the predetermined user in a Frame Cell (FC) and selecting the first input signal in time-domains of the remaining sub- channels other than initial sub-channel. 20. The method as claimed in claim 18, wherein step (a) comprises: a1) dividing each of the division modulation data symbol sequences into a plurality of parts equal to the number of sub-carriers comprising a corresponding sub-channel; a2) spreading the respective divided modulation data symbol sequences, having been divided according to the sub-carriers, using different channelization codes; a3) summing the divided modulation data symbol sequences, having been spread according to the sub-carriers, and generating a single division modulation data symbol sequence; a4) multiplying the single division modulation data symbol sequence by a predetermined scrambling code, and generating the multiplied result; and a5) mapping an output signal of step (a4) with individual sub-carriers comprising the corresponding sub-channel. 21. The apparatus as claimed in claim 1, wherein the orthogonal codes are Walsh codes. 22. The method as claimed in claim 8, wherein the orthogonal codes are Walsh codes. This invention relates to an apparatus for transmitting information bit sequences from a BS (Base Station) transmitter to a plurality of users, comprising; a first set of S/P (Serial parallel) converters for dividing each of the information bits received in sub-channel units into a plurality of information bit sequences in response to the respective users; a plurality of channelizers for spreading the divided information bit sequences using different codes, combining this spread information bit sequences into a single sequence associated with the individual users, and outputting the single sequence; a second set of S/P converters for dividing the single sequence, distributing the divided sequences over a plurality of bandwidths capable of mapping-processing the divided sequences with sub- carrier frequencies; a frequency hopper for frequency hopping for preventing each of the bandwidths from overlapping with time-frequency cells given by the given interval; and an IFT (Inverse Fourier Transform) unit for IFT-processing the divided sequences outputting from the frequency hopper, and generating the IFT - processed result.

Full Text

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a transmission apparatus and method for
use in a mobile communication system based on an OFDM (Orthogonal
Frequency Division Multiplexing) scheme, and more particularly to a transmission
apparatus and method for supporting a multiple access scheme on the basis of the
OFDM scheme.
2. Description of the Related Art
Recently, mobile communication systems have developed from mobile
systems for providing a user with voice signals to a wireless packet
communication system for providing the user with high-speed and high-quality
wireless data packets, such that anyone can use a variety of data services and
multimedia services. The third-generation mobile communication system is
classified into an asynchronous 3GPP (3rd Generation Partnership Project), and a
synchronous 3GPP2, each of which are being standardized for implementing
high-speed and high-quality wireless packet communication services. For
example, an HSDPA (High Speed Downlink Packet Access) standardization is in
progress in the 3GPP, and a IxEV-DV (lxEvolution Data and Voice)
standardization is in progress in the 3GPP2. The IxEV-DV standardization for
the downlink is "IS-2000 Release C". Presently, the standardization of the
uplink is in progress, and the uplink is being standardized under the title "IS-2000
Release D". The aforementioned standardizations are needed for users or
subscribers to receive high-speed (more than 2Mbps) and high-quality wireless
data packet transmission service in the third-generation mobile communication
systems. A fourth-generation mobile communication system is needed for users
or subscribers to receive higher-speed and higher-quality multimedia
communication services.

Technical solutions for providing high-speed and high-quality wireless data
packet services require improved software capable of developing more diverse
and abundant contents and improved hardware capable of developing wireless
access technology, which can provide users with excellent services and has high
spectrum efficiency.
The aforementioned improved hardware, from among the technical
solutions, will firstly be described.
The high-speed and high-quality data service available in wireless
communication is generally deteriorated by channel environments. Channel
environments for wireless communication are frequently changed by a variety of
factors, for example, white noise, variation in reception signal power, shadowing,
movement of a Subscriber Station (SS), a Doppler effect caused by a frequent
change in speed, and interference caused by other users or a multi-path signal.
Therefore, in order to provide the aforementioned high-speed wireless data packet
service, technology improvements over the second-generation or third-generation
mobile communication systems, and which improves adaptive capacity for
channel variation, is required. Although a high-speed power control scheme for
use in the conventional system enhances adaptive capacity for such channel
variation, the 3GPP and the 3GPP2 which are currently processing a high-speed
data packet transmission system standard commonly utilize an Adaptive
Modulation and Coding (AMC) scheme and a Hybrid Automatic Repeat Request
(HARQ) scheme.
The AMC scheme changes a modulation scheme and a code rate of a
channel encoder according to a variation in the downlink channel. In this case,
downlink channel quality information can generally be obtained by measuring a
Signal-to-Noise Ratio (SNR) of a signal using the SS functioning as a terminal
receiver. The SS transmits the channel quality information to a BS (Base
Station) through an uplink. The BS predicts the downlink channel conditions on
the basis of the downlink channel quality information, and prescribes an
appropriate modulation scheme and a code rate for a channel encoder on the basis
of the predicted downlink channel condition. Therefore, an Adaptive
Modulation and Coding (AMC) system adapts a high-order modulation scheme
and a high code rate to an SS (Subscriber Station) having an excellent channel.

However, the AMC system adapts a low-order modulation scheme and a low code
rate to an SS having a relatively inferior channel. Typically, the SS having the
excellent channel may be positioned in the vicinity of the BS, and an SS having
the relatively inferior channel may be positioned at a cell boundary. The
aforementioned AMC scheme can largely reduce an interference signal as
compared to a conventional scheme dependent on a high-speed power control,
resulting in the improvement of system performance.
If an unexpected error occurs in an initial transmission data packet, the
HARQ scheme requires retransmission of the data packet to compensate for the
erroneous packet. In this case, a predetermined link control scheme is adapted to
the compensation process of the erroneous packet, and is considered to be equal to
the HARQ scheme. The HARQ scheme is called a Chase Combining (CC)
scheme, and is classified into a Full Incremental Redundancy (FIR) scheme and a
Partial Incremental Redundancy (PIR) scheme. The CC scheme transmits all of
the packets during a retransmission operation in the same manner as in an initial
transmission process. In this case, a reception end combines the retransmission
packet with the initial transmission packet to increase reliability of a coded bit
received in a decoder, such that the reception end can obtain an overall system
performance gain. In this case, if two equal packets are combined with each
other, an effect similar to that of an iterative coding occurs, and a performance
gain of about 3dB can be attained on average.
The FIR scheme retransmits a packet composed of only redundant bits
generated from a channel encoder, instead of retransmitting the same packet, such
that the FIR scheme can improve a coding gain of a decoder included in the
reception end. That is, the decoder uses both initial transmission information
and new redundant bits during a decoding process, resulting in an increased
coding rate. As a result, the decoder's performance can also be improved. It is
well known in coding theory that a performance gain obtained by a low coding
rate is greater than a performance gain obtained by an iterative coding rate.
Therefore, when considering only the performance gain, the FIR scheme provides
better performance than that of the CC scheme.
The PIR scheme transmits a data packet which is composed of a
combination of information bits and new information bits during a retransmission

time. The PIR scheme combines the information bits with the initial transmission
information bits during a decoding process, such that it can obtain an effect
similar to that of the C scheme. Also, the PIR scheme performs the decoding
process using the redundant bits, such that it can obtain effects similar to those
of the FIR scheme. The PIR scheme has a coding rate greater than that of the
FIR scheme, such that it's the PIR scheme performance is considered to be
intermediate between individual performances of the FIR and C schemes.
However, the HARQ scheme must consider a variety of factors related to
performance and system complexity (e.g., a buffer size and a signaling etc.),
such that it is difficult to determine either one of the factors.
Provided that the AMC scheme and the HARQ scheme use independent
techniques capable of improving the adaptive capacity for a channel variation or
are combined with each other, system performance can be greatly improved. In
other words, if a modulation scheme suitable for the downlink channel conditions
and a coding rate of the channel encoder are determined by the AMC scheme, a
data packet corresponding to the determined information is transmitted.
However, although the aforementioned two schemes are used, the principal
problem encountered in radio communication, i.e., the lack of radio resources, is
incapable of being solved. In more detail, multiple access - based technology
having a superior spectrum efficiency must be developed to maximize subscriber
capacity and to enable high-speed data transmission request for a multimedia
service.

The publication ("Multicarrier CDMA with Adaptive Frequency Hopping for Mobile
radio Systems". By Chen discloses an apparatus for transmitting information bit
sequences from a BS (Base Station) transmitter to a plurality of users,
comprising:
a plurality of channelizers for dividing a single frame of information bit sequences
to be transmitted to individual users into a plurality of division times according to
a given time interval, dividing the information bit sequences within the plurality
of division times, spreading the divided information bit sequences using different
Walsh codes, combining the spread information bit sequences into a single
sequence associated with the individual users, and outputting the single
sequence (page 1853, column 1, last full paragraph); and
a frequency hopper for dividing the single sequence, distributing the spread
information bit sequences over a plurality of bandwidths capable of mapping -
processing the spread information bit sequences with sub-carrier frequencies,
and preventing each of the bandwidths from overlapping with time-frequency
cells given by the given time interval (page 1583, column 2, first full paragraph).
KR-2001-16948 (Song) relates to an orthogonal code jump multiplexing
communication device and a method which are provided to effectively utilize
limited resources using the orthogonal code jump multiplexing technique when
activity of synchronized channels, which hold orthogonal characteristics, is low.
In addition, by diffusing or not diffusing according to the jump pattern which a
transceiver gives to a user removing an unnecessary channel assigned and
return processes, waste by unnecessary controlling signal transmission and a

buffer capacitance and data transfer delay, which are small compared to buffer
capacitance as in a first communication station, are reduced.
Song relates to a statistic multiplexing scheme and apparatus utilizing an
orthogonal code jump method in a wire/wireless communication system which is
synchronized through a single medium and a plurality of communication
channels which exist together. D does not disclose the characteristic of the
present invention having a strong characteristic of selecting fading, rather than a
multiplexing scheme on the basis of an OFDM (Orthogonal Frequency Division
Multiplexing) scheme, through a characteristic if a CDMA scheme and a
frequency jump.
EP 1039683 an orthogonal frequency division multiplexing (OFDM) based spread
spectrum multiple access system in which the entire bandwidth is divided into
orthogonal tones, and all of the orthogonal tones are reused in each cell. To
reduce peak-to-average ratio at the mobile transmitter, each voice user is
allocated preferably a single one, but no more than a very small number, of the
orthogonal tones for use in communicating with the base station. Data users are
similarly allocated tones for data communication, however, the number of tones
assigned for each particular data user is a function of the data rate for that user.
The tone assignment for a given user is not always the same within the available
band, but instead the tones assigned to each user are hopped over time. More
specifically, in the downlink, the tones assigned to each user are change
relatively rapidly, e.g., from symbol to symbol, i.e., the user fast "hops" from one
tone to another. However, in the uplink, preferably slow hopping is employed to
allow efficient modulation of the uplink signal which necessitates the employing

of additional techniques, such as interleaving, to compensate for the reduction in
the intercell interference averaging effect. For data communication power control
is employed in the uplink and/or downlink so that the transmission rate is
increased, e.g., by increasing the number of symbols transmitted per tone per
unit time or the coding rate, as a function of allocated power per tone and the
corresponding channel attenuation.
US 20040219920 discloses a method for rate selection by a communication
device for enhanced uplink during soft handoff in a wireless communication
system includes a first step of receiving information from a scheduler. This
information can included one or more of scheduling, a rate limit, a power margin
limit, and a persistence. A next step includes determining a data rate for an
enhanced uplink during soft handoff using the information. A next step includes
transmitting to a serving base station on an enhanced uplink channel at the data
rate determined from the determining step.
US 20030152023 discloses a wireless transmitter (TXi) which comprises circuitry
for providing a plurality of control (CONTROL) bits and circuitry for providing a
plurality of user (USER) bits. The transmitter also comprises circuitry for
modulating (16) the plurality of control bits and the plurality of user bits into a
stream of complex symbols and circuitry (18) for converting the stream of
complex symbols into a parallel plurality of complex symbol streams. The
transmitter also comprises circuitry (20) for performing an inverse fast Fourier
transform on the parallel plurality of complex symbol streams to form a parallel
plurality of OFDM symbols and circuitry (22) for converting the parallel plurality
of OFDM symbols into a serial stream of OFDM symbols. Each OFDM symbol in
the serial stream of OFDM symbols comprises a plurality of data points, and

selected (SF.sub.2.x) OFDM symbols in the serial stream of OFDM symbols carry
modulation information (AMOD). The modulation information in one or more of
the selected OFDM symbols comprises a plurality of modulation groups, and the
plurality of modulation groups comprises a number of modulation parameters
that describe modulation of a corresponding set of data points in a subsequent
OFDM symbol in the serial stream of OFDM symbols.
US2002159422 describes a method and apparatus for wireless communication
are described. In one embodiment, a method for communicating with a
subscriber comprises transmitting orthogonal frequency domain multiplexing
(OFDM) signals to the subscriber, and receiving direct-sequence spread spectrum
(DSSS) signals from the subscriber.
In conclusion, a new multiple access scheme having superior spectrum efficiency
must be developed to provide the high-speed and high-speed and high-quality
packet data service.
SUMMARY OF THE INVENTION
Therefore, the present invention has been made in view of the above and other
problems, and it is an object of the present invention to provide an apparatus
and method for providing wide-band spectrum resources needed for a high-
speed wireless multimedia service indicative of the objective of the next-
generation mobile communication system.
It is another object of the present invention to provide a multiple access

scheme and associated transmitter for effectively using time-frequency resources.
It is yet another object of the present invention to provide an effective
multiple access scheme and a time-frequency resource utilization method which
can effectively provide a high-speed wireless multimedia service indicative of the
objective of the next-generation mobile communication system.
It is yet further another object of the present invention to provide a multiple
access scheme which includes both characteristics of a CDMA scheme and
characteristics of a frequency hopping scheme on the basis of an OFDM
(Orthogonal Frequency Division Multiplexing) scheme, and a transmitter for use
in the multiple access scheme.
It is yet further another object of the present invention to provide a forward
channel configuration in a multiple access scheme which includes both
characteristics of a CDMA scheme and characteristics of a frequency hopping
scheme on the basis of an OFDM scheme.
It is yet further another object of the present invention to provide a multiple
access scheme which combines portions of an OFDM scheme, a CDMA scheme,
and a frequency hopping scheme, and a transmitter for use in the multiple access
scheme.
It is yet further another object of the present invention to provide a multiple
access scheme for differentially assigning time-frequency resources to individual
users, and a transmitter for use in the multiple access scheme.
It is yet further another object of the present invention to provide a multiple
access scheme for differentially assigning time-frequency resources to individual
services corresponding to individual users, and a transmitter for use in the
multiple access scheme.
In accordance with one aspect of the present invention, the above and other
objects can be accomplished by the provision of an apparatus for transmitting
information bit sequences from a BS (Base Station) transmitter to a plurality of
users, comprising a plurality of channelizers for dividing a single frame time of

information bit sequences to be transmitted to individual users into a plurality of
times according to a given time interval, dividing the information bit sequences
within the plurality of division times, spreading the divided information bit
sequences using different Walsh codes, combining the spread information bit
sequences into a single sequence associated with the individual users, and
outputting the single sequence; and a frequency hopper for dividing the single
sequence, distributing the spread information bit sequences over a plurality of
bandwidths capable of mapping-processing the spread information bit sequences
with sub-carrier frequencies, and preventing each of the bandwidths from
overlapping with time-frequency cells given by the given time interval.
In accordance with another aspect of the present invention, there is
provided a method for transmitting information bit sequences from a BS (Base
Station) transmitter to a plurality of users, comprising the steps of a) dividing a
single frame time of information bit sequences to be transmitted to individual
users into a plurality of times according to a given time interval, dividing the
information bit sequences within the plurality of division times, spreading the
divided information bit sequences using different Walsh codes, combining the
spread information bit sequences into a single sequence associated with individual
users, and outputting the single sequence; and b) dividing the information bit
sequences, which have been combined into the single sequence in step (a),
distributing the spread information bit sequences over a plurality of bandwidths
capable of mapping-processing the spread information bit sequences with
sub-carrier frequencies, and perfanning a frequency hopping function such that
each of the bandwidths does not overlap with the time-frequency cells given by
the given time interval.
In accordance with yet another aspect of the present invention, there is
provided a transmission apparatus for use in a mobile communication system
capable of transmitting information bit sequences from a BS (Base Station)
transmitter to a plurality users, comprising a plurality of traffic channel
transmitters for dividing a modulation data symbol sequence corresponding to a
predetermined user into division modulation data symbol sequences, the number
of which is equal to the number of sub-channels assigned to the predetermined
user, spreading the respective division modulation data symbol sequences using
different channelization codes, and performing a mapping-process with

sub-carriers comprising a corresponding sub-channel; a TDM (Time Division
Multiplexer) for receiving a first input signal from the traffic channel transmitters,
the first input signal including traffic channel signals from the traffic channel
transmitters, a pilot channel signal, and sync (synchronous) and shared channel
signals, which have been spread by a predetermined channelization code and have
been modulated by a predetermined modulation scheme, and receiving a preamble
channel signal as a second input signal, such that the first input signal and the
second input signal are selected in time-domain units of the sub-channel; and an
IFT (Inverse Fourier Transform) unit for IFT-processing a signal selected by the
TDM, and generating the IFT-processed result.
In accordance with yet further another aspect of the present invention, there
is provided a transmission method for use in a mobile communication system
capable of transmitting information bit sequences from a BS (Base Station)
transmitter to a plurality of users, comprising the steps of a) dividing a modulation
data symbol sequence corresponding to a predetermined user into division
modulation data symbol sequences, the number of which is equal to the number of
sub-channels assigned to the predetermined user, spreading the respective division
modulation data symbol sequences using different channelization codes, and
performing a mapping-process in association with sub-carriers comprising a
corresponding sub-channel; b) multiplexing a first input signal and a second input
signal such that the first input signal and the second input signal are selected in
time-domain units of the sub-channel; wherein the first input signal includes
traffic channel signals, a pilot channel signal, and sync (synchronous) and shared
channel signals, which have been spread by a predetermined channelization code
and have been modulated by a predetermined modulation scheme, and a preamble
channel signal is the second input signal, and c) IFT (Inverse Fourier Transform) -
processing a signal selected at step (b), and generating the IFT-processed result.
In accordance with yet further another aspect of the present invention, there
is provided a transmission method for use in a mobile communication system
based on a multiple access scheme, comprising the steps of a) assigning at least
one sub-channel to a predetermined user, spreading data of the predetermined user
using prescribed encoded codes associated with individual sub-carriers
comprising the sub-channel; b) in association with individual output data of the
sub-channels, assigning different sub-carriers for every time interval, a unit of

which is determined to be each of the sub-channels in a time domain; and c) IFT
(Inverse Fourier Transform) - processing the data in the assigned sub-carrier areas
such that it is converted into time-domain data.
BRIEF DESCRIPTION OF THE ACCOMPAYING DRAWINGS
The above and other objects, features and other advantages of the present
invention will be more clearly understood from the following detailed description
taken in conjunction with the accompanying drawings, in which:
Fig. 1 is a diagram illustrating an exemplary utilization of a time-frequency
resource in accordance with the present invention;
Fig. 2 is a block diagram of a transmitter for use in a mobile
communication system of a multiple access scheme in accordance with the present
invention;
Fig. 3 is a detailed block diagram of a channelizer of Fig. 2 in accordance
with the present invention;
Fig. 4 is a diagram illustrating an example of effectively using
time-frequency resources in accordance with the present invention;
Fig. 5 is a block diagram of forward channels capable of providing a
high-speed wireless multimedia service in accordance with the present invention;
Fig. 6 is a detailed block diagram of a transmitter capable of supporting a
multiple access scheme in accordance with the present invention; and
Fig. 7 is a block diagram of a transmitter processing an output signal of the
transmitter shown in Fig. 6 in accordance with the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Now, preferred embodiments of the present invention will be described in
detail with reference to the annexed drawings. In the drawings, the same or
similar elements are denoted by the same reference numerals even though they are
depicted in different drawings. In the following description, a detailed
description of known functions and configurations incorporated herein will be
omitted when it may obscure the subject matter of the present invention.
The present invention provides a multiple access method accompanied by

an effective use of time-frequency resources so as to implement a high-speed
wireless multimedia service indicative of the objectives of the next-generation
mobile communication system, and a transmitter for use in the multiple access
method.
A wide-band spectrum resource is needed for a high-speed wireless
multimedia service indicative of the objectives of the next-generation mobile
communication system. However, when using the wide-band spectrum
resources, a wireless transmission path makes the fading phenomenon prominent
due to a multipath propagation, and a frequency-selective fading phenomenon can
also be easily observed even in a transmission band. Therefore, in order to
implement the high-speed wireless multimedia service, an OFDM scheme having
very strong resistance to the frequency-selective fading phenomenon is better than
the conventional CDMA scheme, such that many developers are recently
conducting intensive research into the OFDM scheme.
Typically, the OFDM scheme enables sub-channel spectrums to maintain
mutual orthogonality therebetween, and also enables the sub-channel spectrums to
be overlapped with each other, resulting in excellent spectrum efficiency. Also,
the OFDM scheme implements a modulation process using an IFFT (Inverse Fast
Fourier Transform), and implements a demodulation process using an FFT (Fast
Fourier Transform). For example, the multiple access scheme based on the
OFDM scheme may be determined to be an OFDM scheme for assigning some
part of an overall sub-carrier to a specific user. The OFDM scheme does not
require a spreading sequence for bandwidth spreading. The OFDM scheme can
dynamically change the set of sub-carriers assigned to a specific user according to
fading characteristics of a wireless transmission path, and this operation of the
OFDM scheme is typically referred to as "dynamic resource allocation" or
"frequency hopping".
The multiple access scheme requiring the spreading sequence is classified
into a spreading scheme in a time domain and a spreading scheme in a frequency
domain. The spreading scheme in the time domain performs spreading of a user
signal in the time domain, and controls the spreading signal to be
mapping-processed with a sub-carrier. The spreading scheme in the frequency
domain performs demultiplexing of a user signal in the frequency domain,

controls the demultiplexing signal to be mapping-processed with a sub-carrier,
and distinguishes user signals using orthogonal sequences.
The following multiple access scheme according to the present invention
can implement a characteristic of the multiple access scheme based on an OFDM
scheme, a characteristic of the CDMA scheme, and a characteristic of the
frequency hopping scheme which has very strong resistance to the frequency
selective fading. It should be noted that the aforementioned new multiple access
scheme is called a Frequency Hopping-Orthogonal Frequency Code Division
Multiple Access (FH-OFCDMA) scheme.
Fig. 1 is a diagram illustrating an exemplary utilization of time-frequency
resources in accordance with the present invention. In Fig. 1, the abscissa is the
time domain, and the ordinate is the frequency domain.
As to the multiplex access scheme capable of supporting K users by
properly utilizing time-frequency resources, reference numeral 101 is a
time-frequency resource assigned to a first user, reference numeral 102 is a
time-frequency resource assigned to a second user, reference numeral 103 is a
time-frequency resource assigned to a third user, and reference numeral 104 is a
time-frequency resource assigned to a K-th user. The time-frequency resource
assigned to every user is determined by a predetermined bandwidth and a
predetermined time. The bandwidth may be assigned according to category
information of services required by each user. For example, a wide bandwidth is
assigned to a user who has requested a service (e.g., a high-speed packet data
service, etc.) requiring a large amount of time-frequency resources. However, a
narrow bandwidth is assigned to a user who has requested a service (e.g., a voice
service, etc.) requiring a small amount of time-frequency resources. The
aforementioned bandwidth assignment means that time-frequency resources can
be differentially assigned to individual users. In Fig. 1, in comparison with the
second user, the remaining users are each assigned a relatively wide bandwidth.
Particularly, the widest bandwidth is assigned to the K-th user from among all of
the users. In the case of comparing the time-frequency resources 101 assigned to
the first user with the time-frequency resources 103 assigned to the third user, a
relatively large amount of time resources are assigned to the first user rather than
the third user. If the widest bandwidth is assigned to the K-th user, this means

that the K-th user currently uses a service requiring much more time-frequency
resources as compared to the remaining users.
The bandwidths BW1, BW2, BW3, and BWk can be represented by the
following Equations 1 to 4.
BW1
n1 = M1 x m (1)
where M1 is the number of sub-channels assigned to the first user, m is the
number of sub-carriers comprised of a single sub-channel, and n1 is a total number
of sub-carriers assigned to the first user.
BW2
n2 = M2xm (2)
where M2 is the number of sub-channels assigned to the second user, and m
is the number of sub-carriers comprised of a single sub-channel, and n2 is a total
number of sub-carriers assigned to the second user.
BW3
n3 = M3 x m (3)
where M3 is the number of sub-channels assigned to the third user, and m is
the number of sub-carriers comprised of a single sub-channel, and n3 is a total
number of sub-carriers assigned to the third user.
BWk
nk = Mk x m (4)
where Mk is the number of sub-channels assigned to the k-th user, and m is
the number of sub-carriers comprised of a single sub-channel, and nk is a total

number of sub-carriers assigned to the k-th user.
As can be seen from the aforementioned Equations 1 to 4, the bandwidth is
determined by multiplying the number (nk) of overall sub-carriers assigned to the
k-th user by the bandwidth fsc of respective sub-carriers. The number nk of all
sub-carriers assigned to the k-th user is determined by multiplying the number
(Mk) of sub-channels assigned to the k-th user by the spreading factor, which is
equal to the product of the sub-carriers which comprise the k-th sub-channel.
Therefore, if the number of sub-channels assigned to a user is adjusted, a
bandwidth usable by the user can also be adjusted. In this case, the above
operation in which the bandwidth is assigned considering both service
requirements and available time-frequency resources of a corresponding user is
called a scheduling algorithm. Although the present invention does not disclose
an embodiment of the scheduling algorithm, it is not limited to any a specific
embodiment of the scheduling algorithm, and as such may employ any kind of
scheduling algorithms.
The bandwidth assignment for every user must be performed within a total
bandwidth BWT predetermined in a frequency domain. The number (M) of all
sub-carriers available in the total bandwidth BWT and the number (nk) of
sub-carriers assigned to respective users can both be represented by the following
Equation 5:

Fig. 2 is a block diagram of a transmitter for use in a mobile
communication system of a multiple access scheme in accordance with the present
invention. A detailed configuration of a transmitter for supporting the
aforementioned time-frequency resource utilization shown in Fig. 1 is shown in
Fig. 2. It is assumed that the transmission of signals (d1, d2,..., dk) associated
with the K users is shown in Fig. 2 in the same manner as in Fig. 1. Also, it is

assumed that the signals (d1, d2,..., dk) associated with the K users have already
been channel-encoded and data-modulated. For reference, in the case of
classifying users in the following description, k is indicative of an arbitrary user
from among all the users, and K is indicative of a total number of users. For
example, if 10 users exist, K is 10, and k is adapted to determine an arbitrary user
from among 10 users.
Referring to Fig. 2, the signals (d1, d2,..., dk) associated with respective
users are transmitted to corresponding time delay controllers 201, 211, and 221.
In more detail, a sequence d1 of the first user signal is transmitted to the first time
delay controller 201, a sequence d2 of the second user signal is transmitted to the
second time delay controller 211, and a sequence dK of the Kth user signal is
transmitted to the K-th time delay controller 221. The time delay controllers
201, 221, and 221 can adjust a relative start point in the time domain of the
time-frequency resource for every user. For example, assuming that the
assignment of the tirrie-frequency domain for every user is established as in Fig. 1,
the first time delay controller 201 will adjust a relative start point in the time
domain of the first time-frequency resource 101 assigned to the first user. After
the time delay controllers 201, 211, 221 output signals for every user, which adjust
a relative start point, the signals for every user are transmitted to Serial/Parallel
(S/P) converters 202, 212, and 222 corresponding to the time delay controllers
201, 211, and 221, respectively. The S/P converters 202, 212, and 222 output the
signals for every user in parallel in the form of sequences equal to the
predetermined number of branches (n1; n2,..., nk). The number of different
branches (n1≠ n2 ≠,..., ≠nK) may be assigned to the S/P converters 202, 212,
and 222, or the number of same branches (n1= n2 =... =nK) may also be assigned
to the S/P converters 202, 212, and 222. In this case, signals for every branch
generated from the S/P converters 202, 212 and 222 have durations which
increase by the predetermined number of branches (n1, n2,..., nk) as compared to
a corresponding entry signal. The output signals of the S/P converters 202, 212,
and 222 are transmitted to channelizers 203, 213, and 223. The channelizers
203, 213, and 223 are spread in a time domain while being classified according to
entry signals equal to the predetermined number of branches. Thereafter, the
spread signals are summed, such that a single spread signal is created. Detailed
descriptions of the channelizers 203, 213, 223 will be given with reference to Fig.
3. The output signals of the channelizers 203, 213, and 223 are transmitted to

the S/P converters 204, 214, and 224. The S/P converters 204, 214, and 224
convert the signal to a parallel signal, and output the output signals of the
channelizers 203, 213, and 223 in the form of sequences equal to the
predetermined number of branches (n1, n2,..., nk). In this case, signals for every
branch generated form the S/P converters 204, 214, and 224 are set to a duration
which is greater than that of a corresponding entry signal by the predetermined
numbers of branches (n1, n2,..., nk). Therefore, user signals generated from the
S/P converters 204, 214, and 224 through the S/P converters 202, 212, and 222
and the channelizers 203, 213, and 223 may be considered to be signals processed
by a CDMA scheme. The number of branches (n1, n2,..., nk) predetermined for
respective S/P converters 202, 212, and 222 at a first end is equal to the number of
branches (n1, n2,..., nk) predetermined for respective S/P converters 204, 214, and
224 at a second end, as shown in Fig. 2, but it should be noted that the present
invention is not limited to the above embodiment shown in Fig. 2. For example,
the number of branches (n1, n2,..., nk) predetermined for respective S/P
converters 202, 212, and 222 at the first end may be different from the number of
branches (n1, n2,..., nk) predetermined for respective S/P converters 204, 214, and
224 at the second end.
Output signals of the S/P converters 204, 214, and 224 are transmitted to a
frequency hopper 231. The frequency hopper 231 can dynamically change the
set of sub-carriers assigned for every user according to fading characteristics of a
wireless transmission path. In more detail, the frequency hopper 231 may be
considered to be a configuration capable of hopping a frequency of a signal to be
transmitted. The time-frequency resource utilization example shown in Fig. l
may be accompanied by fading characteristics encountered at a specific time.
The time delay controllers 201, 211, and 221 are separated from the frequency
hopper 231 in Fig. 2. However, the frequency hopper 231 may include the time
delay controllers 201, 211, and 221 if needed, such that it can adjust the time
delays for every user signal. In this case, the time delay controllers 201, 211, and
221 may be omitted. Although the present invention does not describe a detailed
frequency hopping pattern needed for the frequency hopper 231, a variety of
frequency hopping patterns available for the frequency hopper 231 can be
proposed within a predetermined range in which there is no overlapping of the set
of sub-carriers assigned for every user.

The output signal of the frequency hopper 231 is transmitted to an Inverse
Fourier Transform (IFT) unit 232. The IFT unit 232 converts the output signal
of the frequency domain into another signal of the time domain, and outputs the
signal of the time domain. The IFT unit 232 may adapt the OFDM scheme to a
signal to be transmitted. The transmission signal converted into the time-domain
signal by the IFT unit 232 is transitioned to a Radio Frequency (RF) band, and is
then transmitted to a target.
Fig. 3 is a detailed block diagram of each channelizer 203, 213, or 223 of
Fig. 2 in accordance with the present invention. It is assumed that the following
description relates to the K-th channelizer 223 for the K-th user signal.
Referring to Figs. 2 and 3, the K-th user signal is converted into nk
sequences using the S/P converter 222. The first sequence n(k,1) from among nk
sequences (n(k,2), n(K,2).... n(K,K) is transmitted to a first spreading unit 302, and is
multiplied by an orthogonal sequence W0, such that it is spread. The second
sequence n(K,2) from among the nk sequences (n(k,1), n(k,2),...., n(K,K)) is transmitted
to a second spreading unit 303, and is multiplied by an orthogonal sequence W1,
such that it is spread. The n-th sequence n(K,n) from among the nk sequences
(n(K,1), n(K,2)..., n(K,K)) is transmitted to an n-th spreading unit 304, and is
multiplied by an orthogonal sequence Wn-1, such that it is spread. If the
aforementioned spreading using different orthogonal sequences for every entry
sequence is performed, interference does not occur in the entry sequences. The n
spreading signals generated from the first to n-th spreading units 302, 303, and
304 are transmitted to an adder 305. The adder 305 sums the spreading signals,
and outputs a sequence of a single spreading signal. The spreading signal
generated from the adder 305 is transmitted to a scrambler 306. The scrambler
306 receives a scrambling sequence as another entry signal, and multiplies the
spreading signal by the scrambling sequence, and outputs a scrambled signal.
The scrambler 306 prevents interference from being generated due to the
frequency hit phenomenon wherein a corresponding signal is overlapped with an
output signal of a nearby BS (Base Station) in a frequency domain under cellular
environments. The scrambler 306 is introduced as a method for improving
reception performance of the corresponding signal. If the influence of an
interference signal transmitted from the nearby BS is negligible, the scrambler
306 may be omitted if needed. Fig. 3 depicts a detailed configuration of the

channelizer 223 associated with m sequences (i.e. first sequences) to be
transmitted over the same sub-channel from among the nk sequences (n(K,1), n(K,2),
..., n(K,K)) equal to the output signals of the S/P converter 222 of Fig. 2. In more
detail, Fig. 3 depicts some parts of the channelizer 223 of Fig. 2. The remaining
sequences from among the nk sequences (n(K,1), n(K,1),..., n(K,K)) equal to the output
signals of the S/P converter 222 of Fig. 2 are grouped in n units. The n grouped
sequences are channelized as in Fig. 3, and are transmitted over different
sub-channels.
As can be seen from the description of the transmitter shown in Figs. 2 and
3, the multiple access method according to the present invention can implement a
characteristic of the multiple access scheme based on an OFDM scheme, a
characteristic of the CDMA scheme, and a characteristic of the frequency hopping
scheme which has very-strong resistance to the frequency selective fading.
Fig. 4 is a diagram illustrating an example of effectively using the
time-frequency resource in accordance with the present invention. In Fig. 4, a
unit square is comprised of a predetermined number of sub-carriers, and is
referred to as a Time-Frequency Cell (TRC) having the same duration as the
OFDM symbol interval. A plurality of sub-carriers are assigned to the TFC.
Data corresponding to respective sub-carriers assigned to the TFC is processed by
the CDMA scheme, and is then processed by the OFDM scheme using the
respective sub-carriers. In the case of using the CDMA scheme, data is spread
by a predetermined channelization code prescribed for every sub-carrier, and the
spread data is scrambled by a prescribed scrambling code. In Fig. 4, a Frame
Cell (FC) is defined as a time-frequency domain having both a bandwidth fFC
equal to a predetermined multiple (e.g., 32 times) of the TFC, and a frame
duration equal to a predetermined multiple (e.g., 16 times) of the TFC. If the FC
is adapted to the present invention, the measurement result of wireless
transmission is not frequently reported during the application time of the AMC
technology.
Fig. 4 depicts two different sub-channels contained in a single FC, i.e. a
sub-channel A and a sub-channel B. The two different sub-channels may be
assigned to different users, respectively, or may also be assigned to one user.
The respective sub-channels are frequency-hopping-processed by a predetermined

frequency interval according to a change in time. This means that sub-channels
assigned to respective users are dynamically changed according to fading
characteristics varying with time. Fig. 4 depicts an example of a certain pattern
of the frequency hopping pattern. However, the present invention is not always
limited to the exemplary pattern of Fig. 4, as the frequency hopping pattern of the
present invention can be defined in various ways as needed.
In the case of using the AMC technology, an SS (Subscriber Station)
measures a current state of a wireless transmission path at predetermined time
intervals, and reports the measurement result to a BS (Base Station). Upon
receipt of the wireless transmission path state information from the SS, the BS
changes the AMC scheme. The changed AMC scheme is reported to the SS.
Then, the SS transmits a signal to a desired target using the modulation and
coding schemes as changed by the BS. The present invention reports the
wireless transmission path state information in FC units, such that it can reduce
load encountered by the AMC technology. The FC can be properly adjusted.
according to the amount of overhead information encountered by the AMC
technology. For example, if a large amount of overhead information exists, the
FC is widened. If a small amount of overhead information exists, the FC is
narrowed.
A transmitter for providing a specific user with a service can generally use
a plurality of sub-channels. QoS (Quality of Service) and the number of
simultaneous users must be considered in order to use the plurality of
sub-channels.
Fig. 5 is a block diagram of forward channels capable of providing a
high-speed wireless multimedia service in accordance with the present invention.
In more detail, a forward channel for an FH-OFCDMA(Frequency
Hopping-Orthogonal Frequency Code Division Multiple Access) scheme
indicative of a multiple access scheme proposed by the present invention is
defined as a "FORWARD FH-OFCDMA CHANNEL" in Fig. 5. The
"FORWARD FH-OFCDMA CHANNEL" may be comprised of a pilot channel, a
synchronous (sync) channel, a preamble channel, a traffic channel, and a shared
control channel, or may also be comprised of only the preamble channel. An
example of the "FORWARD FH-OFCDMA CHANNEL" will be described with

reference to Figs. 6 and 7. The pilot channel may allow an SS to acquire a BS,
or may be adapted to perform channel estimation. The sync channel may allow
the SS to acquire BS information and timing information. The preamble channel
is basically adapted to perform frame synchronization, or may also be adapted to
perform channel estimation. The traffic channel is adapted as a physical channel
for transmitting information data. Although the preamble channel is separately
denoted in Fig. 5 to establish frame synchronization, the preamble information
transmitted over the preamble channel may be transmitted as a preamble of a
frame transmitted over the traffic channel if needed. The shared control channel
is used as a physical channel for transmitting control information needed for
receiving the information data transmitted over the traffic channel.
Fig. 6 is a detailed block diagram of an exemplary transmitter which
implements the channel configuration of Fig. 5. Transmitters of individual
channels shown in Fig. 5 are shown in Fig. 6.
The transmitters of individual channels will hereinafter be described with
reference to Fig. 6.
Regarding a transmitter for transmitting user data over the traffic channel,
a sequence of coded bits of the k-th user is generated from a channel encoding
process (not shown), and is then transmitted to a modulator 601. The modulator
601 modulates the coded bits using a QPSK, 16QAM, or 64QAM modulation
scheme, and outputs modulation symbols. In the case of using the AMC scheme,
the modulation scheme used by the modulator 601 is determined by the BS
according to current wireless transmission path state information. A plurality of
modulation symbols generated from the modulator 601 each have a complex
value.
The modulation symbols generated from the modulator 601 are transmitted
to the rate matcher 602. A sequence repeat process or a symbol punching
process is applied to the modulation symbols received in the rate matcher 602.
In more detail, the rate matcher 602 fabricates the modulation symbols to match a
transmission format of a packet transmitted over a radio channel, and outputs the
fabrication result. In this case, the transmission format includes the number of
modulation symbols capable of being transmitted via a single frame. The

modulation symbol sequence generated from the rate matcher 602 is transmitted
to a first demultiplexer 603, The first demultiplexer 603 demultiplexes the
modulation symbol sequence, and outputs modulation symbol sequences for every
sub-channel by the predetermined number of branches. The number of branches
corresponds to the number (Mk) of sub-channels used for a k-th user service, and
Mk may be determined to be a number from 1 to 16. The reference character 'k'
a number between 1 and K, and the reference character 'K' is defined as the
number of maximum service available users. In this case, the modulation
symbol sequences for every sub-channel, which are generated for every branch
using the first demultiplexer 603, have predetermined durations. However, this
is not related to the duration of the modulation symbol sequence received in the
first demultiplexer 603.
Upon receipt of modulation symbol sequences for every sub-channel from
the first demultiplexer 603, a maximum of Mk sub-channel transmitters is needed
to transmit the received modulation symbol sequences over different
sub-channels. Therefore, Fig. 6 depicts Mk sub-channel transmitters. Although
the sub-channel transmitters are different from each other with respect to the
reception modulation symbol sequences, they perform the same operation, such
that the following description will relate to only one sub-channel transmitter for
the convenience of description. One or more sub-channels may be assigned to
traffic channels of respective users, such that one or more sub-channel
transmitters may also be adapted to transmit data over the traffic channels of the
respective users.
The modulation symbol sequences for every sub-channel, which have been
received from the first demultiplexer 603, are transmitted to a corresponding
second demultiplexer from among Mk second demultiplexers 604 and 614. For
example, a modulation symbol sequence corresponding to the first sub-channel
from among the modulation symbol sequences for every sub-channel, which have
been received from the first demultiplexer 603, is transmitted to a second
demultiplexer 604. The second demultiplexer 604 demultiplexes the modulation
symbol sequence corresponding to the first sub-channel, and outputs a plurality of
modulation symbol sequences for every sub-carrier. The number of modulation
symbol sequences for every sub-carrier is equal to the number 'm' of sub-carriers
contained in only one sub-channel. In this case, the modulation symbol

sequences for every sub-carrier each have a predetermined duration which is
greater than of the number of modulation symbols for every sub-channel by 'm'
times. The modulation symbol sequences for every sub-carrier, which have been
received from the second demultiplexer 604, are transmitted to a channel divider
605. The channel divider 605 spreads the modulation symbol sequences for
every sub-carrier using an orthogonal sequence having a predetermined length
'm', and outputs the spread modulation symbol sequences. In this case, the
modulation symbol sequences for every sub-carrier will be spread by different
orthogonal sequences. Output sequences, in chip units, which have been spread
according to individual sub-carriers by the channel divider 605, are transmitted to
an adder 606. The adder 606 sums the output sequences for every sub-carrier in
chip units, and outputs the added result in the form of a single sequence. The
output sequence of the adder 606 is transmitted to a scrambler 607. The
scrambler 607 multiplies a scrambling code generated from a scrambling
sequence generator 613 by the output sequence of the adder 606, and outputs a
scrambled sequence. The aforementioned components from the second
multiplexer 604 receiving the modulation symbol sequence to the scrambler 607
generating the scrambled sequence may be equal to components needed for signal
processing corresponding to the CDMA scheme.
The scrambled sequence is transmitted to a mapping unit 608. The
scrambled sequence received in the mapping unit 608 is mapping-processed with
sub-carriers comprising a first sub-channel assigned to the scrambled sequence.
The mapping unit 608 may perform a frequency hopping function capable of
dynamically changing sub-carriers comprising the sub-channel according to
fading characteristics of the wireless transmission path.
Although the aforementioned description does not disclose a detailed
example, it is obvious that sub-channel transmitters corresponding to the
remaining sub-channels other than the first sub-channel can output data to
individual sub-channels in the same manner as in the aforementioned sub-channel
transmitter.
Secondly, as to the pilot channel transmitter for transmitting a pilot signal
(i.e. unmodulated signal) over a pilot channel, the unmodulated signal is
transmitted to a pilot tone position determination unit 621. The pilot tone

position determination unit 621 determines a sub-carrier position at which a pilot
tone is to be inserted. Therefore, the pilot tone will be inserted into the
determined sub-carrier position.
Thirdly, as to the synch channel transmitter for transmitting information
data over a sync channel, the information data is transmitted to a channel encoder
631. The channel encoder 631 encodes the information data of the sync channel,
and outputs the encoded information data. The encoded information data is
transmitted to a modulator 632. The modulator 632 modulates the encoded
information data according to a predetermined modulation scheme, and outputs
the modulation result in the form of sync channel data.
Fourthly, as to the shared channel transmitter for transmitting control
information over a shared control channel, the control information is transmitted
to the channel encoder 641. The channel encoder 641 encodes the control
information of the shared control channel, and outputs the encoded control
information. The encoded control information is transmitted to a modulator 642.
The modulator 642 modulates the encoded control information according to a
predetermined modulation scheme, and outputs the modulation result in the form
of shared control channel data.
Fig. 7 depicts a configuration for the FORWARD FH-OFCDMA
CHANNEL in accordance with the present invention. An input end "A" shown
in Fig. 7 is connected to an output end "A" shown in Fig. 6, such that a transmitter
of the present invention can be implemented. Therefore, output signals of the
transmitter of Fig. 6 are transmitted to the input end "A" of Fig. 7. The output
signals are comprised of traffic channel data, pilot channel data, sync channel
data, and shared control channel data, which are generated from each sub-channel.
Referring to Fig. 7, the output signals of Fig. 6 are transmitted to input
terminals of a Time Division Multiplexer (TDM) through the input terminal "A".
A preamble channel signal is also transmitted to other input terminals of the TDM
701. The TDM 701 TDM-processes the output signals of Fig. 6 and the
preamble channel signal, and outputs the TDM-processing result. Referring
back to Fig. 4, a single FC is comprised of 16 TFCs in a time domain. The TDM
701 selects/outputs the preamble channel in a first TFC from among the 16 TFCs,

and selects/outputs the output signals in the remaining 15 TFCs other than the first
TFC. Output signals corresponding to either the preamble channel signal or the
remaining channel signals, having been generated from the TDM 701, are
transmitted to an IFT (Inverse Fourier Transform) unit 702. The IFT unit 702
IFT-processes its own input signal from among the output signals which
correspond to either the preamble channel signal or the remaining channel signals,
such that it converts a frequency-domain signal into a time-domain signal. The
output signal of the IFT unit 702 is transmitted as "FORWARD FH-OFCDMA
CHANNEL" of the present invention.
As apparent from me above description, in the case of using a multiple
access scheme and time-frequency resource utilization according to the present
invention, time-frequency resources can be effectively used, and spectrum
efficiency can be maximized. Therefore, it is expected that the present invention
will effectively provide a high-speed wireless multimedia service satisfying the
objectives of the next-generation mobile communication system.
Also, the present invention can implement a characteristic of the multiple
access scheme based on an OFDM scheme, a characteristic of a CDMA scheme,
and a characteristic of a frequency hopping scheme which has very strong
resistance to the frequency selective fading.
Although the preferred embodiments of the present invention have been
disclosed for illustrative purposes, those skilled in the art will appreciate that
various modifications, additions and substitutions are possible, without departing
from the scope and spirit of the invention as disclosed in the accompanying
claims.

WE CLAIM
1. An apparatus for transmitting information bit sequences from a BS (Base
Station) transmitter to a plurality of users, comprising:
a first set of S/P (Serial parallel) converters for dividing each of the
information bits received in sub-channel units into a plurality of
information bit sequences in response to the respective users:
a plurality of channelizers for spreading the divided information bit
sequences using different codes, combining this spread information bit
sequences into a single sequence associated with the individual users, and
outputting the single sequence;
a second set of S/P converters for dividing the single sequence,
distributing the divided sequences over a plurality of bandwidths capable
of mapping-processing the divided sequences with sub-carrier
frequencies;
a frequency hopper for frequency hopping for preventing each of the
bandwidths from overlapping with time-frequency cells given by the given
interval; and
an IFT (Inverse Fourier Transform) unit for IFT-processing the divided
sequences outputting from the frequency hopper, and generating the IFT
- processed result.

2. The apparatus as claimed in claim 1, wherein the number of information
bit sequences is equal to the number of sub-carriers comprising a sub-
channel.
3. The apparatus as claimed in claim 1, wherein the frequency hoppcr
converts sub-carriers assigned to individual sub-channels in a previous
time domain into secondary sub-carriers based on a characteristic of a
wireless transmission path, such that the frequency hopper performs a
frequency hopping function.
4. The apparatus as claimed in claim 1, comprising:
a plurality of time delay controllers corresponding to the number of
information bit sequences of the users, for adjusting relative start points
of the users in a time domain.
5. The apparatus as claimed in claim 1, wherein the plurality of channelizers
comprises means for dividing a single frame of information bit sequences
to be transmitted to individual users into a plurality of division times
according to a given time interval, dividing the information bit sequences
within the plurality of division times.
6. The apparatus as claimed in claim 1, wherein the each users is assigned
at least one sub-channel according to a QoS (Quality of Services) of the
user.

7. The apparatus as claimed in claim 3, wherein the characteristic of the
wireless transmission path is reported according to its current condition in
Frame Cell (FC) units.
8. A method for transmitting information bit sequences from a BS (Base
Station) transmitter to a plurality of users, comprising the steps of:

a) dividing each of the information bits received in sub-channel units
into a plurality of information bit sequences in response to the
respective users;
b) dividing a single frame of information bit sequences to be
transmitted to individual users into a plurality of times according to
a given time interval, dividing the information bit sequences within
the plurality of division times, spreading the divided information bit
sequences using different orthogonal codes, combining the spread
information bit sequences into a single sequence associated with
the individual users, and outputting the single sequence;
c) dividing the single sequence, distributing the divided sequences
over a plurality of bandwidths capable of mapping - processing the
divided sequences with sub-carrier frequencies;
d) frequency hopping for performing a frequency cells given by the
given time interval; and

e) IFT (inverse Fourier Transform) - processing the divided
sequences, and generating the IDT-processed result.
9. The method as claimed in claim 8, wherein the number of information bit
sequences is equal to the number of sub-carriers comprising a sub-
channel.
10. The method as claimed in claim 8, wherein the frequency hopping
function shifts sub-carriers comprising individual sub-carriers in a previous
time domain to secondary sub-carriers.
11. The method as claimed in claim 8, comprising the steps of:
f) in response to the information bit sequences of the users, adjusting
relative start points of the users in a time domain.
12. The method as claimed in claim 8, wherein step of combining the spread
information bit sequences into a single sequence comprises the steps of:
summing the spread information bit sequences and generating a single
spread information bit sequence; and
multiplying the spread information bit sequence by a predetermined
scrambling code, and generating a scrambled information bit sequence as
the single sequence.

13. The method as claimed in claim 8, wherein the each users is each
assigned at least one sub-channel according to a QoS (Quality of Services)
of the user.
14.The method as claimed in claim 9, wherein the characteristic of the
wireless transmission path is reported according to its current condition in
Frame Cell (FC) units.
15. A transmission apparatus for use in a mobile communication system
capable of transmitting information bit sequences from a BS (base
Station) transmitter to a plurality of users, comprising:
a plurality of traffic channel transmitting for dividing a modulation data
symbol sequence corresponding to a predetermining user into division
modulation data symbol sequences, the number of which is equal to the
number of sub-channel assigned to the predetermined user, spreading the
respective division modulation data symbol sequences using different
channelization codes, and performing a mapping-process with sub-carriers
comprising a corresponding sub-channel;
a TDM (Time Division Multiplexer) for receiving a first input signal from
the traffic channel transmitting, the first input signal including channel
signals from the traffic channel transmitters, a pilot signal, and sync
(synchronous) and shared channel signals, which have been spread by a
predetermined channelization code and have been modulated by a
predetermined modulation scheme, and receiving a preamble channel

signal as a second input signal, such that the first input signal and the
second input signal are selected in time-domain units of the sub-channel;
and
an IFT (Inverse Fourier Transform) unit for IFT-processing a signal
selected by the TDM, and generating the IFT-processed result.
16. The apparatus as claimed in claim 15, wherein the TDM selects the
second input signal in a time domain of an initial sub-channel assigned to
the predetermined user in a Frame Cell (FC), and selects the first input
signal in time-domains of the remaining sub-channels other than the initial
sub-channel.
17.The apparatus as claimed in claim 15, wherein each of the traffic channel
transmitters comprises:
a demultiplexer for dividing each of the division modulation data symbol
sequences into a plurality of parts equal to the number of sub-carriers
comprising a corresponding sub-channel;
a channelizer for spreading the respective divided modulation data symbol
sequences, having been divided according to the sub-carriers, using
different channelization codes;

an added for summing the divided modulation data symbol sequences,
having been spread according to the sub-carriers, and generating a singie
division modulation data symbol sequence;
a scrambler for multiplying the single division modulation data symbol
sequence by a predetermined scrambling code, and generating the
multiplied result; and
a mapping unit for mapping an output signal of the scrambler with
individual sub-carriers comprising the corresponding sub-channel.
18. A transmission method for use in a mobile communication system capable
of transmitting information bit sequences from a BS (Base Station)
transmitter to a plurality of users, comprising the steps of :
a) dividing a modulation data symbol sequence corresponding to a
predetermined user into division modulation data symbol
sequences, the number of which is equal to the number of sub-
channels assigned to eth predetermined user, spreading the
respective division modulation data symbol sequences using
channelization codes, and performing a mapping-process in
association with sub-carriers comprising a corresponding sub-
channel;
b) multiplexing a first input signal and a second input signal such that
the first input signal and the second input signal are selected in

time-domain units of the sub-channel, wherein the first input signal
includes traffic channel signals, a pilot channel signal, and sync
(synchronous) and shared channel signals, which have been spread
by a predetermined channelization code and have been modulated
by a predetermined modulation scheme, and a preamble channel
signal is the second input signal; and
c) IFT (Inverse Fourier Transform) - processing a signal selected at
step (b), and generating the IFT-Processed result.
19. The method as claimed in claim 18, wherein step (b) comprises the step
of:
bl) selecting the second input signal in a time domain of an initial sub-
channel assigned to the predetermined user in a Frame Cell (FC) and
selecting the first input signal in time-domains of the remaining sub-
channels other than initial sub-channel.
20. The method as claimed in claim 18, wherein step (a) comprises:
a1) dividing each of the division modulation data symbol sequences into a
plurality of parts equal to the number of sub-carriers comprising a
corresponding sub-channel;

a2) spreading the respective divided modulation data symbol sequences,
having been divided according to the sub-carriers, using different
channelization codes;
a3) summing the divided modulation data symbol sequences, having been
spread according to the sub-carriers, and generating a single division
modulation data symbol sequence;
a4) multiplying the single division modulation data symbol sequence by a
predetermined scrambling code, and generating the multiplied result; and
a5) mapping an output signal of step (a4) with individual sub-carriers
comprising the corresponding sub-channel.
21. The apparatus as claimed in claim 1, wherein the orthogonal codes are
Walsh codes.
22. The method as claimed in claim 8, wherein the orthogonal codes are
Walsh codes.

This invention relates to an apparatus for transmitting information bit sequences
from a BS (Base Station) transmitter to a plurality of users, comprising; a first set
of S/P (Serial parallel) converters for dividing each of the information bits
received in sub-channel units into a plurality of information bit sequences in
response to the respective users; a plurality of channelizers for spreading the
divided information bit sequences using different codes, combining this spread
information bit sequences into a single sequence associated with the individual
users, and outputting the single sequence; a second set of S/P converters for
dividing the single sequence, distributing the divided sequences over a plurality
of bandwidths capable of mapping-processing the divided sequences with sub-
carrier frequencies; a frequency hopper for frequency hopping for preventing
each of the bandwidths from overlapping with time-frequency cells given by the
given interval; and an IFT (Inverse Fourier Transform) unit for IFT-processing
the divided sequences outputting from the frequency hopper, and generating the
IFT - processed result.

Documents:

467-KOLNP-2005-FORM-27.pdf

467-kolnp-2005-granted-abstract.pdf

467-kolnp-2005-granted-claims.pdf

467-kolnp-2005-granted-correspondence.pdf

467-kolnp-2005-granted-description (complete).pdf

467-kolnp-2005-granted-drawings.pdf

467-kolnp-2005-granted-examination report.pdf

467-kolnp-2005-granted-form 1.pdf

467-kolnp-2005-granted-form 18.pdf

467-kolnp-2005-granted-form 2.pdf

467-kolnp-2005-granted-form 3.pdf

467-kolnp-2005-granted-form 5.pdf

467-kolnp-2005-granted-gpa.pdf

467-kolnp-2005-granted-reply to examination report.pdf

467-kolnp-2005-granted-specification.pdf

467-kolnp-2005-granted-translated copy of priority document.pdf

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Patent Number

226177

Indian Patent Application Number

467/KOLNP/2005

PG Journal Number

50/2008

Publication Date

12-Dec-2008

Grant Date

08-Dec-2008

Date of Filing

21-Mar-2005

Name of Patentee

SUMSUNG ELECTRONICS CO. LTD.

Applicant Address

416 MAETAN-DONG, YEONGTONG-GU, SUWON-SI, GYEONGGI-DO

Inventors:

#	Inventor's Name	Inventor's Address
1	YOUNG-KWON CHO	# 202-601, DONGSUWON LG VILLAGE, MANGPO-DONG, PALDAL-GU, SUWON-SI, GYEONGGI-DO
2	KATZ MARCOS DANIEL	#621-906, DONGBO APT., YEONGTONG-DONG, PALDAL-GU, SUWON-SI, GYEONGG-DO
3	SEOK-HYUN YOON	# 104-602, HYUDAI APT., IMUN 3-DONG, DONGDAEMUN-GU, SEOUL,
4	DONG-SEEK PARK	#107-1802, SK, SEOCHEON-RI, GIHEUNG-EUP, YONGIN-SI, GYEONGGI-DO
5	SEONG-III PARK	#325-801, HANYANG APT., SEOHYEON-DONG, BUNDANG-GU, SEONGNAM-DO
6	HO-KYU CHOI	#1204-303, MUJIGAEMAEL, GUMI-DONG, BUNDANG-GU, SEONGNAM-SI, GYEONGGI-DO
7	YOUNG-KYUN KIM	#309-1405, WOOSEONG APT., SANGNOKMAEUL, JEONGJA-DONG, BUNDANG-GU, SEONGNAM-SI, GYEONGGI-DO
8	HYEON-WOO LEE	#806-901, BYUCKSAN APT., GWONSEON, GWONSEON-GU, SUWON-SI GYEONGGI-DO
9	PAN-YUH JOO	#104-1002, HYUNDAI HOME TOWN, YEHYEONMAEUL, SEOCHEN-RI, GIHEUNG-EUP, YONGIN-SI, GYEONGGI-DO

PCT International Classification Number

H04B 1/707

PCT International Application Number

PCT/KR2004/001477

PCT International Filing date

2004-06-19

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1	40352/2003	2003-06-20	Republic of Korea