| Title of Invention | METHOD FOR TRANSMITTING/RECEIVING FEEDBACK INFORMATION, AND METHOD FOR TRNSMITTING/RECEIVING DATA USING THE SAME |
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| Abstract | A method for transmitting/receiving feedback information and a method for transmitting/receiving data using the same are disclosed, which acquire accurate channel information and reduces an amount of overhead, and effectively allocate resources during the initial transmission time A method for allowing a first reception end to transmit feedback information includes receiving a transmission request message of the feedback information from a transmission end, generating the feedback information including both band position information indicating a position of a data where data is received and a channel quality indication value indicating a channel quality of the band, and transmitting the feedback information. |
| Full Text | [DESCRIPTION] [invention Title] METHOD FOR TRANSMITTING/RECEIVING FEEDBACK INFORMATION, AND METHOD FOR TRANSMITTING/RECEIVING DATA USING THE SAME [Technical Field] The present invention relates to a method for transmitting/receiving feedback information and a method for transmitting/receiving data using the same, and more particularly to a method for transmitting/receiving feedback information such that it acquires accurate channel information and reduces an amount of overhead, and a method for transmitting/receiving data to effectively allocate resources during the initial transmission time. [Background Art] A transmission end for transmitting data in a mobile communication system must receive two kinds of channel information from a reception end. First channel information from among the two kinds of channel information is indicative of CSI (Channel State Information) . The CSI indicates correct information for a mobile communication channel generated during a specific time from data transmission to the reception end, and is directly received from the reception end. Second channel information is CQI (Channel Quality Information) which is indicative of the simplified CSI information. In more detail, if the transmission end desires to extract transmission (Tx) data and control information from the received signals after receiving transmission (Tx) signals from the reception end, the transmission end requires the CSI, such that distortion caused by propagation signals received via a radio frequency (RF) channel can be removed by using the CSI. Generally, the above-mentioned distortion-removing action has been called a channel equalization function. In the case where the reception end receives a signal from the transmission end, the CQI indicates how strong the channel carrying the received signal is. In other words, the CQI indicates the channel intensity of the signal received in the reception end. Typically, the CQI has been widely used by a resource scheduler. The resource scheduler determines which one of channels can most effectively transmit data from the transmission end to the reception end. In the meantime, the CQI indicates average characteristics of the channel. Generally, the CQI averages the CSI according to a predetermined bandwidth, such that it indicates the average value of the CSI. In other words, if a channel response is denoted by "H", the CQI at a specific band "k" can be represented by the following equation 1: where, G is indicative of the number of subcarriers summed up in the selected band "k". The CQI is based on an average value of a channel power. If the CQI is really applied to the transmission end, this CQI is properly mapped and refined to a set of range definition according to modulation and channel-coding scheme, so that the resultant CQI is transmitted to a destination. This modulated CQI value is called an MCS (Modulation and Coding Scheme) level. The CQI indicates which one of MCS levels for use in a specific band "k" can effectively deliver a data signal from the transmission end to the reception end without generating significant problems. As described above, the modulation-coding scheme is selectively and/or repeatedly changed according to the CQI value, and a variety of parameters (e.g., proper Tx power) can also be regulated by the CQI of the reception end. A detailed description of the above-mentioned parameters capable of being regulated by the CQI value has been described in the 3GPP TS 25.214 V6.7.1 (published on December 2005). According to a conventional method for measuring the CQI value, the CSI is firstly estimated, and the CQI is then measured. Indeed, in the case of estimating the CQI, the above-mentioned Equation 1 based on the CSI is not used, and a plurality of reception powers of a specific carrier is summed up, such that the CQI can be estimated. Therefore, the above-mentioned equation 1 can be represented by the following equation 2: where, R() is indicative of a reception (Rx) signal of the i-th subcarrier, P is indicative of an interval among pilots selected for the CQI estimation, and G' is indicative of the number of Rx signals selected in the frequency band interval of the G value. FIG. 1 exemplarily shows the CQI mapped by the modulation/coding scheme level. In more detail, FIG. 1 exemplarily shows a method for mapping the calculated CQI to a MCS level. In this case, the mapping method is designed to change the MCS level whenever the calculated CQI is higher than a predetermined threshold value. This threshold value changes the modulation and channel encoding actions to others, and a BER (bit error rate), a PER (packet error rate), and a processing performance are crossed at a specific location corresponding to the threshold value, such that the specific location is generally set to the threshold value. Also, the threshold value changes the MCS level according to the CQI value, and changes a variety of parameters such as Tx power of the transmission end. In more detail, a method for performing the modulation and channel encoding actions according to the MCS 0 ~ MCS N-l levels shown in FIG. 1 can be changed according to the system requirements. For example, in the case of a channel (i.e., a good channel) having the CQI value of 30, a coding rate may be set to 1/2, and a modulation scheme may be set to the 16QAM method. In the case of a channel (i.e., a bad channel) having the CQI value of 1, a coding rate may be set to 1/3, and a modulation scheme may be set to the QPSK method. And, in association with the mapping relationship among other parameters, the 3GPP LTE may use a method of the Tables 7A~7E prescribed in the 3GPP TS 25.214 V.6.7.1 (2005.12) or 3GPP TS 36 series (211,212,213,etc), however, it should be noted that the scope of the above-mentioned parameter mapping relationship is not limited to the above- mentioned example, and can also be applied to other examples as necessary. In the meantime, if the CQI reporting period becomes shorter, a channel variation status can be quickly considered, however, an unexpected overhead occurs during the CQI reporting time. Otherwise, if the CQI reporting period becomes longer, the channel variation characteristics cannot be quickly reflected whereas the amount of overhead is reduced, so that a system performance is deteriorated. Therefore, as the importance of the effective usage of radio resources becomes greater, a variety of techniques for reducing an amount of call- origination overhead (i.e., outgoing overhead) created during the CQI transmission have been recently proposed. FIG. 2 is a conceptual diagram illustrating a general CQI feedback scheme. Referring to FIG. 2, the Node-B transmits a common pilot signal to individual users to measure the downlink (DL) channel quality at step (1). Each user measures the channel quality on the basis of the common pilot signal by exploiting orthogonal pilot sequence property, calculates the SINR per measuring bandwidth at step (2), and reports a CQI level index or multiple indices with frequency- positions corresponding to the calculated SINR to the Node- B at step (3). The Node-B properly allocates resources according to channel states of the individual users by referring to the CQI value at step (4) . Therefore, the Node-B determines the modulation scheme or the coding rate, and transmits data to a user equipment (UE) acting as a destination at step (5). There are a variety of methods for transmitting the above-mentioned CQI value to the transmission end, and a detailed description thereof will hereinafter be described with reference to the annexed drawings. FIGS. 3 and 4 show a conventional method for transmitting the conventional CQI value to the transmission end. The periodic CQI reporting scheme of FIG. 3 has been used to report the CQI to the UE, such that it has been widely used by a plurality of communication standards. In more detail, the periodic CQI reporting scheme commands the UE to periodically report the CQI value to the Node-B. Although the method of FIG. 3 uses four sub-frames as a reporting period, it should be noted that the reporting period of the UE is determined by the Node-B and may also be changed according to status information of the UE. The configuration of CQI reporting period can be informed through UL grant or high layer signaling. According to the periodic reporting scheme, as shown in FIG. 3, the CQI reporting of each UE is periodically executed, irrespective of the presence or absence of DL (downlink) traffic data of each UE. If there are no CQI report messages on the condition that a specific UE includes the DL traffic information as denoted by oval- shaped circles in FIG. 3, and if there is no DL traffic information under the same condition, the individual UEs must report the CQI. FIG. 4 shows a triggered CQI reporting scheme. Differently from the periodic CQI reporting scheme executed irrespective of data transmission, the above- mentioned triggered CQI reporting scheme has been designed to receive the CQI only when data transmission is required, such that it prevents uplink channel resources from being unnecessarily wasted. If the Node-B has data to be transmitted to a specific UE, the triggered CQI reporting scheme reports the CQI to the specific UE at intervals of a predetermined period of time. If data transmission is completed, the CQI transmission is no longer performed. Therefore, the CQI reporting is performed only when DL data is allocated to the specific UE as shown in FIG. 4. Also, during the above-mentioned CQI transmission, a variety of CQI formats can be made available and applied to the following three schemes, a detailed description thereof will hereinafter be described in detail. The three schemes are a Full Band CQI reporting scheme, a Best M CQI reporting scheme, and a Hybrid CQI reporting scheme. The Full Band CQI reporting scheme transmits CQI information of all the scheduling bands to the Node-B when the UE transmits the CQI information to the Node-B. Since the Full Band CQI reporting scheme transmits CQI information of all the bands of a channel to the Node-B, the Node-B can recognize detailed information associated with the channel bands of the UE. Therefore, the Node-B can effectively use the UE' s channel bands. However, provided that the Full Band CQI reporting scheme transmits the CQI information to all the channel bands, much more uplink resources are consumed, so that an overall throughput might be deteriorated. Next, the Best M CQI reporting scheme will hereinafter be described with reference to FIG. 5, and the Hybrid CQI reporting scheme will hereinafter be described with reference to FIG. 6. The Best M CQI reporting scheme transmits the CQI of a specific band profitable to each UE, instead of CQI information of all the bands, such that it prevents location information not to be used for the scheduling from being unnecessarily transmitted. The UE calculates the CQI values of all the bands (Bl ~ B12) as shown in FIG. 5, and selects the best M CQI values from among the calculated CQI values. FIG, 5 shows an example in which the M value is set to "4". In FIG. 5, four CQI values (B2, B4, B7 and B9) having the highest CQI levels are selected from among all the CQI values (Bl ~ B12) . In this case, the band including the selected CQI values is transmitted to an uplink channel along with the CQI values. In the meantime, the Best M average CQI reporting scheme is generally similar to the Best M CQI reporting scheme. However, differently from the Best M CQI reporting scheme, the Best M average CQI reporting scheme transmits location information of the selected M bands (B2, B4, B7, and B9), but it averages the selected M bands and transmits the average value of the selected M bands. As a result, the Best M average CQI scheme can slightly reduce the overhead caused by the CQI transmission. However, the Best B average CQI reporting scheme may incorrectly calculate the CQI value of each band, so that the overall scheduling performance may be deteriorated, resulting in the occurrence of a reduced throughput. In the meantime, differently from the above- mentioned CQI reporting scheme, the hybrid CQI reporting scheme shown in FIG. 6 generates/transmits the CQI to recognize the profile of all the bands. All the bands are hierarchically grouped so that the hierarchically-grouped bands generate the level. The CQI values of individual levels are averaged in the grouping units for each level, so that the average CQI is calculated. FIG. 6 shows a specific case in which the n value indicating the hierarchically-grouped level is set to any one of 1~4. The CQI value (B13) at the level of n=2 is equal to the average CQI value at the group band composed of Bl and B2 at the level of n=l. The CQI value (B19) at the level of n=3 is equal to the average CQI value at the group band composed of B13 and B14. Then, the best CQI value of each level and an index value including the best CQI are transmitted to the Node-B. In more detail, as shown in the right side of FIG. 6, if n is set to 1 (i.e., n=l), the CQI value of the band B4 and an index value including the B4 CQI value are transmitted to the Node-B. If n is set to 2 (i.e., n=2), the CQI value of the band B14 and an index value including the B14 CQI value are transmitted to the Node-B. If n is set to 3 (i.e., n=3) , the CQI value of the band B19 and an index value including the B19 CQI value are transmitted to the Node-B. If n is set to 4 (i.e., n=4), the CQI value of the band B22 and an index value including the B22 CQI value are transmitted to the Node-B. In this case, the CQI value transmitted to the Node- B is different in level according to individual transmission times. For example, in the case of the initial CQI transmission, a CQI value of the n=l level and band index information including this CQI value are transmitted to the Node-B. In the case of the next CQI transmission, a CQI value of the n=2 level and band index information including this CQI value are transmitted to the Node-B. As a result, the CQI profile of an overall transmission band can be estimated. Presently, the above-mentioned CQI concept has been applied to a mobile communication system in various ways. Representative examples of the CQI application are a CDMA communication technology for mobile phones and a mobile WiMax technology based on the IEEE 802.16. The CDMA communication technology for mobile phones does not classify a transmission band, and transmits data to a destination using a sequence of the whole band, so that only one value for the whole band is transmitted to the destination. In this case, there are a variety of methods for transmitting the single value for the whole band to the destination, for example, a first transmission method (e.g., old-version method before CDMA2000) capable of acquiring a desired performance by controlling only the power, and a second transmission method (e.g., CDMA2000 or HSDPA) for directly transmitting correct CQI information to the destination. In the case of the CDMA2000 capable of transmitting correct CQI information, the CDMA2000 technology uses a differential CQI to chase (or track) the changing CQI. In other words, the CDMA2000 technology indicates a difference between a previously-transmitted CQI value and a current CQI value by 1-bit indicating the increment or decrement. The OFDM transmission system such as the WiMax system capable of splitting a wireless transmission band transmits the CQI as to a channel scheduling subband discriminated by the scheduler to the transmission end. In this case, the method for transmitting the CQI to the transmission end is the periodic CQI reporting scheme, and is relevant to the Best M average CQI reporting scheme. This transmission method of the CQI is the band-based CQI reporting scheme, so that a large amount of overhead unavoidably occurs. The differential CQI is used to reduce the large amount of overhead. In this case, a few bits(including lbit) information having a predetermined option of +delta dB increment or -delta dB decrement (or MCS level differential) for each sub-band is transmitted to the transmission end. In the case of the conventional CQI reporting cases, the differential CQI is used to reduce the amount of CQI's overhead. According to the conventional art, it is assumed that there is no change in the once-selected band during the reporting time of the differential CQI. In other words, the once-determined CQI might be continuously fixed in next times, and only the CQI variation within the predetermined band might be reported. In addition, the CQI variation within the reported band has been designed to indicate only the increment/decrement on the basis of a specific value. So, if the increment or decrement does not occur, i.e., if a current status is maintained, either the increment information or the decrement information is transmitted to a destination, so that the transmission end may unexpectedly have the loss rather than the gain. In the case of transmitting the differential CQI, a differential value between a current signal and a previous signal indicates only the fixed-range value. Therefore, if a variation range of the CQI value is very large, the conventional system has difficulty in effectively coping with the CQI value. The conventional system periodically transmits the CQI of the whole band to a destination, so that it indicates whether the differential CQI value is correctly represented. Unless the variation of the CQI value is represented by a current encoding scheme, the conventional system has no method for quickly informing the transmission end of this situation. The conventional periodic CQI reporting scheme may periodically report the CQI value when a corresponding user is not allocated, or may not report the CQI value even when the data of the corresponding user is allocated, resulting in the occurrence of serious problems. The triggered CQI reporting scheme transmits the CQI value only when data of the corresponding user is allocated. However, if several users simultaneously report the CQI value, several CQI channels are used, so that CQI channel capacity can be problematic. In addition, the current CQI reporting schemes have no CQI information received from the UE during the transmission of initial data of the system. Also, the current CQI reporting schemes have no CQI information received from the UE, even when the user does not transmit data for a long period of time and then begins to transmit the data. For the convenience of description and better understanding of the present invention, the above-mentioned first case is called an "initial data transmission case", and the above-mentioned second case is called "no available feedback information case" (i.e., no CQI information case). In other words, according to the above-mentioned initial data transmission case, the system must transmit data of a base station (e.g., Node-B of 3GPP) to a destination without using the CQI information received from the UE. In this case, since the system has no CQI information of a specific band, it is unable to select an effective transmission band from among several bands so that data of the effective transmission band cannot be transmitted to the destination. [Disclosure] [Technical Problem] Accordingly, the present invention is directed to a method for transmitting/receiving feedback information, and a method for transmitting/receiving data using the same, that substantially obviate one or more problems due to limitations and disadvantages of the related art. An object of the present invention is to provide a method for transmitting a CQI value and information of a band location at which data can be effectively transmitted, so that it reduces the number of errors generated during the tracking time of a variation of the CQI value. Another object of the present invention is to provide a method for diversifying values indicated by differential information, so that it can more precisely indicate the variation of differential information. Yet another object of the present invention is to provide a method for prescribing a specific function required for transmitting feedback information such as CQI. Yet another object of the present invention is to provide a method for reducing an amount of CQI overhead, and effectively using allocated resources, thereby reporting feedback information such as CQI values of several users. Yet another object of the present invention is to provide a method for reducing the number of bits of feedback information such as CQI, such that it can quickly consider an abruptly-changing channel status within limited resources. Yet another object of the present invention is to provide a method and apparatus for effectively using resources during the transmission of initial data, so that it reduces the loss of data during the transmission time. Yet another object of the present invention is to provide a method and apparatus for prescribing default feedback information during the transmission of initial data, recognizing channel information via differential feedback information transmitted or received, so that it can effectively exchange information. Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention. The objectives and other advantages of the invention may be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings. [Technical Solution] To achieve these objects and other advantages and in accordance with the purpose of the invention, as embodied and broadly described herein, a method for allowing a first reception end to transmit feedback information, the method comprising: receiving a transmission request message of the feedback information from a transmission end; generating the feedback information including both band position information indicating a position of a data where data is received and a channel quality indication value indicating a channel quality of the band; and transmitting the feedback information. Preferably, when a number of total reception ends, including the first reception end, which are going to transmit the feedback information at a specific time, is a plural number, the feedback information transmission request message is transmitted to the first reception end determined in consideration of individual priority information of the total reception ends. In another aspect of the present invention, there is provided a method for requesting transmission of feedback information comprising: if there are a plurality of reception ends which are going to transmit the feedback information at a specific timeslot, determining priority information of the individual reception ends; selecting a specific reception end which is going to transmit the feedback information in consideration of the determined priority information of the individual reception ends; and requesting transmission of the feedback information from the selected reception end. In yet another aspect of the present invention, there is provided a method for transmitting data of a Node- B comprising: transmitting a request message of feedback information to a User Equipment (UE}; receiving the feedback information from the UE according to the feedback information request message; and after receiving the feedback information, starting transmission of downlink data. In yet another aspect of the present invention, there is provided a method for transmitting data of a Node- B comprising: if available feedback information is not received from a User Equipment (UE), allocating downlink resources according to a distributed resource allocation scheme; and starting transmission of initial downlink data to the UE via the allocated downlink resources. In yet another aspect of the present invention, there is provided a method for transmitting data of a Node- B comprising: receiving default feedback information established by a User Equipment (UE); and transmitting initial downlink data via downlink resources allocated on the basis of the default feedback information. In yet another aspect of the present invention, there is provided a method for transmitting data of a Node- B comprising: establishing default feedback information to be equally used by both a User Equipment (UE) and the Node- B; transmitting initial downlink data via downlink resources allocated on the basis of the default feedback information; and receiving differential feedback information from the UE after transmitting the initial downlink data. In yet another aspect of the present invention, there is provided a method for receiving data of a User Equipment (UE) comprising: receiving a feedback information request message from a Node-B; transmitting a differential value between feedback information generated by the feedback information request message and default feedback information commonly contained in the Node-B and the UE; and receiving data via resources allocated from the Node-B on the basis of the differential value. In yet another aspect of the present invention, there is provided a method for receiving data of a User Equipment (UE) comprising: receiving initial downlink data via downlink resources allocated by a distributed resource allocation scheme; transmitting a differential value between feedback information replying to the reception of the initial downlink data and default feedback information commonly contained in both the UE and a Node-B to the Node-B; and receiving downlink data generated after the initial downlink data from the Node-B via downlink resources allocated on the basis of the differential value. In yet another aspect of the present invention, there is provided a method for receiving data of a User Equipment (UE) comprising: establishing default feedback information, and transmitting the established default feedback information to a Node-B; and receiving initial downlink data transmitted via downlink resources allocated on the basis of the default feedback information. It is to be understood that both the foregoing general description and the following detailed description of the present invention are exemplary and explanatory and are intended to provide further explanation of the invention as claimed. [Advantageous Effects] The present invention transmits the CQI value and the position information of a received band (i.e., Rx band) as feedback information, and reduces the number of errors caused when the Node-B tracks a CQI variation in an OFDM system capable of transmitting data via divided Tx bands, thereby correctly performing the scheduling of data. The present invention allows the differential information to indicate the increment, decrement, and the same status between the current signal and the previous signal, so that it can more accurately track the CQI information. The present invention can easily change the range of a differential value according to the variation speed of the differential information, and the mobility is gradually emphasized. As a result, the present invention can be effectively applied to the rapidly-changing channel. The present invention can reduce an amount of overhead when the differential value is transmitted according to the joint encoding scheme, and properly selects a sequence indicating a necessary function according to the encoding scheme during the transmission of feedback information such as CQI, so that it quickly informs the transmission end of the specific situation as compared to the conventional art. If several UEs which desire to transmit feedback information at a specific timeslot, the Node-B decomposes the resources allocated for transmission of the feedback information according to priority information of individual UEs, so that the allocated resources can be effectively used. Specifically, if the feedback information to be transmitted is CQI information, the present invention calculates the user priority in consideration of CQI characteristics, so that information necessary for the DL scheduling can be effectively transmitted via the limited resources. In this case, the present invention transmits a differential value of feedback information via each channel, so that the number of bits of the feedback information to be transmitted can be reduced, and the number of channels allocated for transmission of the feedback information can also be reduced. In this way, the present invention uses the feedback information with the reduced bits, so that the Node-B can quickly consider the abruptly-changing channel status. The present invention transmits the CQI reporting request message to a corresponding UE during the initial data transmission, starts transmission/reception of the DL data after receiving the CQI value corresponding to the CQI reporting request message, so that it can stably transmit/receive data. The present invention uses the distributed resource allocation scheme capable of minimizing the influence of a specific frequency band during the initial data transmission, so that it can stably transmit/receive data without generating an additional time delay. The present invention exchanges information via the differential CQI value using the default CQI value commonly contained in the Node-B and the corresponding UE, so that UL resources can be effectively allocated. The present invention performs the initial DL data transmission of the Node-B using the default CQI value created by signals received via the synchronization estimation process, before the corresponding UE receives the initial DL data, so that the initial data transmission can be effectively performed. Therefore, the present invention can use the default CQI value as a reference for calculating the differential CQI value. [Description of Drawings! The accompanying drawings, which are included to provide a further understanding of the invention, illustrate embodiments of the invention and together with the description serve to explain the principle of the invention. In the drawings: FIG. *. exemplarily shows CQI mapped by the modulation/coding scheme level; FIG. 2 is a conceptual diagram illustrating a general CQI feedback scheme; FIGS. 3~4 show a conventional method for transmitting a conventional CQI value to a transmission end; FIG. 5 shows the Best M CQI reporting scheme; FIG. 6 shows the Hybrid CQI reporting scheme; FIGS. 7 — 8 show position information of data Rx bands of individual UEs; FIG. 9 is an exemplary data structure for transmitting position information of a CQI reporting band according to the present invention; FIG. 10 is an exemplary data structure for transmitting information indicating a CQI value according to the present invention; FIG. 11 is a conceptual diagram illustrating a method for indicating a position variation of a band via which the UE receives data according to the present invention; FIG. 12 is a graph illustrating a slow variation of the CQI value according to the present invention; FIG. 13 is a graph illustrating a rapid variation of the CQI value according to the present invention; FIGS. 14~19 show exemplary channel structures for transmitting band position information and CQI values according to the present invention; FIG. 20 is a block diagram illustrating an apparatus for transmitting feedback information according to the present invention; FIG. 21 is a block diagram illustrating a method for selecting UEs going to report CQI values according to a preferred embodiment of the present invention; FIG. 22 shows a method for sequentially selecting UEs reporting the CQI using the method of FIG. 21 according to the present invention; FIGS. 23~26 shov; detailed concepts of the sequential selection method shown in FIG. 22 according to the present invention; FIG. 27 is a conceptual diagram illustrating a method for reporting the CQI using a differential value when the number of selected UEs is a plural number according to the present invention; FIGS. 28~30 are conceptual diagrams illustrating methods for reporting the CQI using a differential value when the number of selected UEs is a plural number according to the present invention; FIG. 31 is a conceptual diagram illustrating a method for sequentially selecting UEs reporting the CQI using a differential value when the number of selected UEs is a plural number according to the present invention; FIGS. 32~33 show detailed concepts of the sequential selection method shown in FIG. 31 according to the present invention; FIG. 34 is a block diagram illustrating characteristics of a Node-B according to another preferred embodiment of the present invention; FIG. 35 is a conceptual diagram illustrating a method for delaying data transmission until the CQI is received from the UE, and transmitting the delayed result according to a preferred embodiment of the present invention; FIG. 36 shows the preferred embodiment of FIG. 35 from the viewpoint of a data stream to be transmitted according to individual steps according to the present invention; FIG. 37 is a conceptual diagram illustrating a distributed resource allocation scheme and a localized resource allocation scheme according to the present invention; FIG. 38 is a conceptual diagram illustrating a method for transmitting initial data according to the distributed resource allocation scheme according to a preferred embodiment of the present invention; FIG. 39 is a conceptual diagram illustrating a method for establishing a default CQI value during the transmission of initial data, and transmitting the established default CQI value according to a preferred embodiment of the present invention; FIG. 40 is a conceptual diagram illustrating a method for transmitting the CQI of each user using the default-CQI establishing method of FIG. 39 according to the present invention; FIG. 41 is a block diagram illustrating an apparatus for delaying data transmission until the CQI is received during the initial data transmission, and transmitting the delayed result, and the Node-B including the apparatus according to a preferred embodiment of the present invention; FIG. 42 is a block diagram illustrating an apparatus for transmitting data according to the distributed resource allocation scheme, and the Node-B including the apparatus according to another preferred embodiment of the present invention; and FIG. 43 is a block diagram illustrating an apparatus for transmitting data using the default-CQI value during the transmission of initial data, and the Node-B including the apparatus according to still another preferred embodiment of the present invention. [Best Model Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference indexes will be used throughout the drawings to refer to the same or like parts. It should be noted that most terminology disclosed in the present invention is defined in consideration of functions of the present invention, and can be differently determined according to intention of those skilled in the art or usual practices. Therefore, it is preferable that the above-mentioned terminology be understood on the basis of all contents disclosed in the present invention. For example, although feedback information transmitted from the UE is exemplarily set to the CQI in the present invention, it should be noted that the scope of the feedback information is not always limited to the CQI on the condition that the feedback information can report location and status information of a data Rx band, so that other feedback information may also be included in the scope of the present invention FIGS. 7~8 show position information of data Rx bands of individual UEs. FIGS. 7~8, differently from the CDMA communication scheme capable of transmitting data via all bands without dividing the transmission (Tx) band into sub-bands, the communication scheme is shown, which divides a radio frequency (RF) band into sub-bands so that it transmits data via the the sub-bands, and may change a Tx channel of data applied to each UE according to the lapse of time. Particularly, provided that a specific system (e.g., a cognitive radio communication system) for providing a new communication service by recognizing a currently-unused frequency band is used, the above-mentioned characteristics become more serious. According to the concept and system of FIG. 7, downlink (DL) data transmitted to each UE is transmitted over a channel having different bands for each sub-frame, and the number of allocation channels for transmitting the DL data is changeable. According to the concept and system of FIG. 8, although the number of allocation channels for DL data applied to each UE is fixed to a predetermined number, data applied to each UE is changeable according to sub-frames. Therefore, if the system transmits a feedback signal on the assumption that the once-selected band is unchangeable during the reporting time of either the CQI value or the differential CQI value, the system may transmit incorrect information according to a communication scheme (e.g., WiMax), dividing the RF band into several sub-bands. In more detail, the system may transmit incorrect information according to a specific communication scheme (See FIG. 7 or 8) capable of changing a transmission band of DL data with time. Therefore, the frame structure for transmitting feedback information (e.g., CQI) according to the present invention can transmit only the CQI value, and can include band position information indicating the position of a data reception band in the CQI value, such that it transmits the resultant CQI value indicating a channel quality of the above-mentioned band to a destination. Needless to say, all or either of the above-mentioned band position information and the channel quality information may be configured in the form of a differential signal, so that an amount of a corresponding signal may be decreased. A method for reporting feedback information of the data reception channel according to the present invention may basically include two steps for indicating the differential CQI values, i.e., a first step for reporting the. band position, and a second step for reporting a variation of the band CQI value. The band position information and the CQI value may be simultaneously transmitted, or may be transmitted independent of each other. Also, the above-mentioned method for reporting the feedback information of the data reception channel may further include not only different analysis results of the values indicated by bits of the differential CQI value, but also an adaptation step thereof. In order to indicate the differential value using bits, the system must consider the number of cases and the available ranges of individual values. The resultant number of cases may indicate the number of necessary bits. There are a variety of methods for indicating the above- mentioned values, i.e., a separate encoding scheme, and a joint encoding scheme. The separate encoding scheme allocates individual differential values to independent bit sequences. In other words, differential values are encoded by differential positions and/or bits to which the differential CQI values are assigned, and the encoded values are concatenated in the form of a single signal. If reporting channel capacity cannot afford the concatenated bit sequences, the combination of differential position and CQI can be transmitted separately in a time division-wise. One of aspect for above mentioned separate transmission is to divide the selected band information into separate transmission unit. Another aspect of above mentioned separate transmission is to divide the concatenated sequence to fit into the reporting channel capacity and the segmented sequences is transmitted in time division-wise. In this case, in order to extract information of each band, the separate encoding scheme must recognize only positions of corresponding bits, so that the separate encoding scheme can be easily implemented. Provided that the number of cases to be indicated by K-th information is N* , the number of necessary bits is . In this case, M is indicative of a minimum integer number higher than "x". Therefore, provided that M independent information must be transmitted, the total number of necessary bits is denoted by The joint encoding scheme binds values of several bands associated with the combination of individual differential values into a single group, such that it considers the number of cases under the above-mentioned situation. In this case, the combination of all differential values is assigned to a single bit sequence. In order to recognize either the position information corresponding to individual bands or the CQI variation of the individual bands, the system must check all the bit sequences according to the joint encoding scheme. In this way, if several values are grouped into a single structure, the system may indicate the values with the least number of bits, so that the total amount of overhead can be reduced. If the number of cases to be indicated by the K-th value is is Nh, and the number of Nk, values is M, the total number of cases to be indicated can be represented by the following equation 3: [Equation 3] Therefore, the total number of necessary bits can be represented by Generally, in the case of comparing the separate encoding scheme with the joint encoding scheme, the total number of used bits can be represented by the following equation 4: [Equation 4] Next, a method for transmitting the reporting band position information and/or the CQI value using the above- mentioned encoding scheme will hereinafter be described with reference to FIG. 9. FIG. 9 is an exemplary data structure for transmitting the CQI reporting band position information according to the present invention. Referring to FIG. 9, the left side of FIG. 9 shows a specific case in which differential position information is indicated by independent bits, and the right side of FIG. 9 shows another case in which the differential position information is grouped into a single structure, so that the grouped structure is shown in the right side of FIG. 9. According to the present invention, if the differential position information values DP1—DP5 are combined and transmitted as shown in the right side of FIG. 9, the position information values DP1~DP5 are not considered to be equal to each other and then combined, but different weights are assigned to the position information values DP1~DP5 so that the position information values DP1~DP5 having different weights are combined with each other. For example, if col is assigned to DPI, is assigned to DP2, is assigned to DP3, 4 is assigned to DP4, and 5 is assigned to DP5, the order of the weights col ~ 5 can be represented by col this case, the highest weight is assigned to specific information indicating position information of a band at which the most recent data is received, so that the resultant data may be transmitted to a desired destination. A detailed description of the above-mentioned method for assigning weights to individual information during the joint encoding, and combining the assigned resultant values with each other will hereinafter be described. If several bit information values are combined and transmitted, the bit information values may be combined by either a soft combine scheme or a hard combine scheme. If the system desires to separately transmit only differential information using the above-mentioned method for transmitting feedback information, the left side or the right side of FIG. 9 may be selectively used to transmit feedback information. FIG. 10 is an exemplary data structure for transmitting information indicating a CQI value according to the present invention. Referring to FIG. 10, the left side of FIG. 10 shows a specific case in which differential CQI values are indicated by independent bits, and the right side of FIG. 10 shows another case in which the differential CQI values are grouped into a single structure so that the grouped structure is shown in the right side of FIG. 10. Needless to say, in the same manner as in FIG. 9, if the individual CQI values are grouped into one and the grouped result is transmitted as shown in the right side of FIG. 10, the system of FIG. 10 assigns weights to individual bit information and combines the resultant bit information with each other. In this way, if the system desires to transmit only specific information indicating only the differential CQI values, the right side or the left side of FIG. 10 may be selectively used to transmit the specific information. FIG. 11 is a conceptual diagram illustrating a method for indicating a position variation of a band via which the UE receives data according to the present invention. A band position of a transmission (Tx) channel of current data and a current CQI value of data transmitted via the band may be higher than a previous band position and CQI, may be lower than the same, or may be equal to the same as necessary. In the case of transmitting the CQI value via the differential CQI value, the conventional system is designed to indicate the increment or decrement of a current signal in association with a previous signal, so that it is unable to indicate a specific case in which the current signal is equal to the previous signal. Although the error of +1 or -1 in the CQI variation does not greatly affect the scheduling caused by an overall CQI level variation, position information of a reception (Rx) band (hereinafter referred to as Rx band position information) may encounter a serious problem because the error of +1 and the error of -1 in index information of a corresponding band may indicate different bands. Differently from the CQI variation, the position of the data Rx band is maintained during a predetermined frame as shown in FIG. 11. Therefore, if the data Rx band position is indicated by an index indicating a previous Rx band position, the value of +1, and the value of -1, the accuracy of the scheduling task may be greatly deteriorated. Therefore, the present invention provides a method for indicating the CQI value and the data Rx band position signal using the increment value of +1 indicating that the current signal is higher than the previous signal, the decrement value of -1 indicating the current signal is lower than the previous signal, and the same status value of 0 indicating that the current signal is equal to the previous signal, so that it can transmit more accurate feedback information. As shown in FIG. 11, the band position may be maintained during a predetermined frame, and the method for reporting feedback information according to the present invention transmits the Rx band position information much more infrequently than the CQI reporting method, so that the overhead of uplink resources is reduced. In this case, it is preferable that the transmission of the band position information may be limited to only a specific case in which the position of the Rx band is changed to another position. In the meantime, the increment is indicated by the value of +1, the decrement is indicated by the value of and the same status is indicated by the value of 0. And, the variation of the difference value between the current signal and the previous signal can be adjusted by the signal-variation width, and a detailed description thereof will hereinafter be described with reference to FIGS. 12 and 13. FIG. 12 is a graph illustrating a slow variation of the CQI value according to the present invention. FIG. 13 is a graph illustrating a rapid variation of the CQI value according to the present invention. In the case of updating the CQI information via the differential value, the present invention may change the range of a value indicated by each bit so as to track the rapid variation of the CQI value. A horizontal axis of FIG. 12 or 13 indicates a time (i.e., a sub-frame), and a vertical axis of FIG. 12 or 13 indicates a CQI level at a sub-frame of a corresponding time. In other words, as shown in FIG. 12, the present invention is able to track a CQI value of a slowly-changing channel by the combination of three values -1, 0, and 1. However, in order to rapidly update the differential value due to the faster channel-variation speed, the present invention may perform scaling of the range of the CQI value, or may exponentially change the range of the CQI value. There are a variety of mapping methods for use in the above-mentioned scheme, i.e.,a first mapping method, a second mapping method, and a third mapping method. The first mapping method is indicative of a mapping model based on a single parameter (M), so that it exemplarily indicates a differential value in the form of .., -3*M, -2*M, -M, 0, M, 2*M, and 3*M, .... In this case, the M value is changed in the order of 1, 2, ..., according to the variation speeds, so that the variation speed of the differential value can be smoothly adjusted. The second mapping method is designed to use two parameters M and P. The second mapping method indicates the differential value in the form of ..., -M-2P, -M, -P, 0, M, M+P, and M+2P, .... For example, if the M or P value is set to "1", the differential value between the M and P values may be denoted by ..., -3, -2, -1, 0, 1, 2, and 3, .... If the M value is set to "1" and the P value is set to "2", the differential value between the M and P values may be denoted by ..., -5, -3, -1, 0, 1, 3, and 5, ... The above- mentioned second mapping method has an advantage in that it indicates a differential value (e.g., values between M and 2M values) within the range of the magnitude M. The third mapping method may exponentially use four parameters X, M, P, and N. In other words, the third mapping method may indicate the differential value in the form of ..., X+M*P(N*2), X+M*P*"*1', X+M*P(0), 0, -X-M*P(0), -X- M*P(Nn), and -X-M*P(N*2),.... For example, if the X value is set to 0, the M value is set to 1, the P value is set to 2, and the N value is set to 1, the differential value may be denoted by ..., 4, 2, 1, 0, -1, -2, and -4, ... For example, if the X value is set to 0, the M value is set to 2, the P value is set to 3, and the N value is set to 1, the differential value may be denoted by ..., 18, 6, 2, 0, -2, -6, and -18, .... For example, if the X value is set to 2, the M value is set to 1, the P value is set to 2, and the N value is set to 1, the differential value may be denoted by ..., 6, 4, 3, 0, -3, ~4, and -6, ... As a result, the third mapping method can adjust the interval between a first differential value at a part close to a central value and a second differential value at a part distant from the central value, such that the differential values can be combined in various ways. In the case of adjusting the parameters M, P, X, and N using the above-mentioned mapping models, the range of a value capable of being tracked by the differential value can also be adjusted. In order to change the above- mentioned models, the part for requesting the CQI may transmit the variation of the above-mentioned model to the other party using a specific bit sequence or command, and may report the differential CQI from the other party. A method for encoding the CQI value and the band position information using the differential value denoted by the aforementioned mapping models, and transmitting the encoded result will hereinafter be described in detail. FIGS. 14~19 show exemplary channel structures for transmitting band position information and CQI values according to the present invention. The recording data of the CQI variation value is converted into' a bit sequence by the separate encoding scheme and the joint encoding scheme. In order to estimate the CQI variation, an index value of a selected band and the CQI variation value within the selected band must be tracked. In order to report the above-mentioned situation, the present invention may request a differential CQI value for the selected band as shown in FIG. 10. Also, the present invention may report whether the position of bands selected at the same transmission time or different transmission times is unchanged. The reporting scheme may be executed as shown in FIG. 9. In the case of transmitting differential values of the position and CQI value, the differential values can be transmitted as shown in FIGS. 9 and In. However, in the case of simultaneously transmitting the differential values, the differential values may be combined in various ways as shown in FIGS. 14 to 19. FIG. 14 shows a specific case in which separately- encoded differential CQI values are attached to the differential index values of the selected band, and the attached result is transmitted to a desired destination. FIG. 15 shows a modified example of FIG. 14. In more detail, FIG. 15 shows a specific case in which only differential position information is merged- encoded. FIG. 17 shows a specific case in which the differential position information and the differential CQI value are merged-encoded, respectively, so that the merged- encoded result is transmitted to a destination. FIG. 18 shows a specific case in which the differential position information and the differential CQI value are considered to be only one information, so that the merged-encoding process is applied to the resultant information. FIG. 19 shows a specific case in which the differential band position information and the differential CQI value are merged-encoded in units of sequential bits, and the merged- encoded result is transmitted to a destination. In this case, the reception end has an advantage in that it can track the sequential band position information and CQI values. According to the present invention, in the case of combining the above-mentioned differential CQI information with the differential position information, and transmitting the combined result, the differential CQI information and the differential position information are not equally combined with each other, but predetermined weights are assigned to individual bits of the above- mentioned information, so that the resultant data having different weights is transmitted. In this case, in the case of transmitting individual bit information separately from each other, in association with the differential CQI value and differential position information transmitted by the joint encoding scheme, the Node-B divides the received information into individual bit information, so that the Node-B can analyze the differential CQI value and differential position information on the basis of the divided bit information. And, the differential CQI value and the differential position information received by the joint encoding scheme may also be used to perform the next scheduling. For example, the band position is unchanged during a specific sub-frame and only the CQI value of each sub-frame is changed during the specific sub-frame, the highest weight is assigned to the CQI value of the most recently received signal, so that the resultant CQI value including the highest weight is transmitted to a desired destination. Therefore, the CQI value of the data Rx band can reflect the most recent CQI value. In the case of assigning a weight to Tx data and transmitting the resultant Tx data, the reception end can extract a differential CQI value and differential band position information for each bit. In the case of assigning the highest weight to the most recent information, and transmitting the resultant data, the possibility of inaccurately damaging the most recent differential CQI value and the differential position information due to signal distortion is lowered during the transmission time. As described above, the present invention can properly track the variation of CQI values and the variation of a selected band. It is obvious to those skilled in the art that various modifications of the present invention can be implemented in various ways as shown in FIGS. 14 to 19. In the meantime, a special function may be added to either the above-mentioned joint encoding scheme or the separate encoding scheme. The conventional system has been designed to periodically transmit an overall-band CQI to indicate whether a differential CQI value is correctly expressed. As a result, if the abrupt CQI variation cannot be represented by the current encoding scheme, the conventional system is unable to quickly inform the transmission end of this situation. In order to solve the problems of the conventional art, in the case where the CQI value and the band position information cannot be correctly denoted by only the currently-used differential CQI information due to the abrupt CQI variation, the present invention provides a method for defining a special function capable of informing the transmission end of the above-mentioned case. And, the special function may be relevant to the method for indicating the CQI information using the separate encoding scheme or the joint encoding scheme. A method for defining the special function using each encoding scheme, and analyzing associated values will hereinafter be described in detail. Firstly, the unary data mapping method for the separate encoding will be described in detail. The unary- data mapping method (also called a unidirectional data mapping method) is designed to define only unidirectional variation of data in the number of several cases associated with bit sequences. In more detail, only the positive( + )- directional variation of data or the negative(-)- directional variation of data can be defined by the unary data mapping method. For example, if 1-bit has two numbers (i.e., 1 and 0) of cases, the numbers of cases are mapped by the increasing/decreasing permutations as denoted by {2,1} or {-1,-2}. The two bits (i.e., 2-bit) has the number of cases denoted by {00, 01, 10, 11}, and the resultant number denoted by {00, 01, 10, 11} is mapped by the increasing/decreasing permutations as denoted by {1,2,3,4} and {-1,-2,-3, -4}. In this case, a special function may be mapped to a specific bit sequence as necessary. For example, in the case of using three bits (i.e., 3-bit), a specific sequence {111} from among several sequences denoted by 3 bits may be designed to describe a specific situation incapable of being explained by a currently-defined mapping scheme. If the Node-B receiving the differential value composed of 3 bits meets the sequence {111}, the Node-B recognizes that the current CQI cannot be estimated by a corresponding mapping scheme, so that it requests an overall CQI from the UE. If the CQI value is changed in the direction from the increment to the decrement or in the direction from the decrement or increment during the above-mentioned unary data mapping scheme, the UE transmits a sequence for a special function to the Node-B, so that the Node-B can recognize that the CQI variation cannot be represented by the unary data mapping scheme indicating only the unidirectional increment/decrement. The Node-B receives the sequence from the UE, generates a command for switching the increasing/decreasing direction, and transmits the command to the UE as necessary. Needless to say, the UE may recognize that the CQI variation cannot be represented in the increasing/decreasing directions, and may switch the increasing/decreasing directions to other directions. Next, the binary data mapping method for the separate encoding will be described in detail. The binary mapping method is similar to the unary mapping method, however, it should be noted that the increment/decrement actions of data are executed in all of positive/negative directions, differently from the unary mapping method. For example, if the binary differential information is established by 1-bit, the binary differential information may be indicated by the combination of positive and negative values, as shown in the combination {1,-1}. If the binary differential information is established by 2-bit, the binary differential information may be indicated by the combination {-1,0,1,2} or {-2,-1,0,1} of positive and negative values. If the CQI variation cannot be explained under the current mapping references, the binary data mapping method may define the special function in the same manner as in the unary mapping method. For example, in the case of using the 2-bit, the sequence {11} is established by a special function, and the Node-B receives the sequence {11}, the binary mapping method determines that the CQI value cannot be tracked by the current mapping references, such that the UE requests the overall CQI. Next, the joint encoding scheme will hereinafter be described in detail. The joint encoding scheme may have the combination more easily than the separate encoding scheme. In other words, in the case of indicating the combination of individual values, the joint encoding scheme can represent the bit sequence more effectively than the separate encoding scheme. For example, in order to indicate the status {-1, 0, 1}, the separate encoding scheme requires 2 bits. In order to transmit the status {-1,0,1} three times, the separate encoding scheme requires 6 bits. However, according to the joint encoding scheme, the number of total available cases is 27, and is denoted by 5 bits. Since only 27 sequences from among 32 sequences denoted by the 5-bit are defined, the joint encoding scheme can define the special function using the.remaining values. For example, it is assumed that each differential value may have three values {-1,0,1} and the value denoted by {-1,0,1} should be transmitted five times. Under this assumption, the total number of combinations is denoted by 35=243, and the 243 combinations can be represented by 8 bits. Accordingly, the above-mentioned 24 3 sequences from among 256 sequences, each of which is represented by 8 bits, are expressed and the remaining 13 sequences are left. One of the aforementioned sequences may indicate an overall failure of the differential mapping. In the case of other combinations, first CQI information from among the CQI information may indicate the error, and second CQI information may also indicate the error as necessary. In the meantime, in the case of creating a bit sequence using the real joint encoding scheme, the following regulations are needed. Provided that the number of cases of all the differential values (hereinafter referred to as the case-number of all the differential values) is set to X, and M differential values must be transmitted, the total number of cases is denoted by XM, so that XM cases occur. If the above-mentioned number of cases is re-defined, the bit sequence value to be transmitted can be represented by the following equation 5: [Equation 5] where dk is indicative of k-th transmission (Tx) data. In the meantime, provided that weights are assigned to individual differential values according to the joint encoding scheme and are then combined with the differential values, Equation 5 can also be represented by the following equation 6: where a>k is indicative of a weight of the dk value. If a transmission (Tx) bit sequence is given as shown in the Equations 5 and 6, the reception end may decide CQI information on the basis of the L value, may search for each differential value dk, and may decide the CQI information on the basis of the retrieved differential value dk. If the CQI information is decided by the joint- encoding value (L) , it is preferable that the highest weight is assigned to differential value information relevant to the most recently-received data, so that the channel status can be properly decided. The above- mentioned case may be effectively applied to a specific case in which a CQI value indicating the final channel status of a corresponding band is the most important matter, because the band position is unchanged in the above- mentioned case, however, it should be noted that the scope and spirit of the present invention is not limited to only this example, and can also be applied to other examples as necessary. A method for searching for the dk value corresponding to each differential value from among the joint-encoding value (L) can be performed as follows. Firstly, in the case where no weight is assigned to each differential value information and the differential values having no weights are combined with each other, this situation can be represented by the following equation 7: where, mod(x,y) is indicative of an operator for calculating a remainder created when "x" is divided by "y". also, if the joint-encoding value (L) is received on the condition that weights are assigned to individual bit information as shown in Equation 5, the d* value can be calculated by the following equation 8: [Equation 8] In this way, if the joint encoding scheme is used as described above, the number of Rx data bits can be reduced, and an amount of overhead of uplink resources can also be reduced. The highest weight is assigned to the final differential value during the joint encoding operation, so that the possibility of damaging the final differential value during the transmission time is minimized. Needless to say, the method for analyzing the feedback information according to the present invention acquires information indicating a data Rx band position from feedback information entered by the UE, and acquires CQI information at the data Rx band. And, if the band position information and the CQI value are represented by the differential values as described above, the differential values are compared with previous values, so that the perfect band position information and the perfect CQI information can be acquired. In the meantime, the above-mentioned channel structure and an apparatus for implementing the method for transmitting feedback information using the channel structure will hereinafter be described in detail. FIG. 20 is a block diagram illustrating an apparatus for transmitting feedback information according to the present invention. Referring to FIG. 20, Tx data of the Node-B is received via an antenna, and is received in the controller 1001 via a duplexer. The controller 1001 according to the present invention may extract information (pk) indicating a Rx band position and a CQI value (rk) of the corresponding band from the Rx data (R). The controller 1001 transmits a control signal (c) to the calculator 1003 and the encoder 1004, so that it controls operations of the calculator 1003 and the encoder 1004. The information (rk and pk) extracted by the controller 1001 may be applied to the buffer 1002 and the calculator 1003. The buffer 1002 stores received information (rk and pk) , so that it may output information (rk_i and pk-i) stored after 'the lapse of a single frame (i.e., 1-frame) to the calculator 1003. Needless to say, if the CQI value used as feedback information is not continuously transmitted in the same manner as in the CQI transmission case activated only when the presence of Rx data is decided, corresponding information can be stored in the buffer 1002 until the next feedback information is transmitted. For the convenience of description and better understanding of the present invention, the buffer 1002 may store a plurality of information pieces during the interval of the 1 frame, and a detailed description thereof will hereinafter be described in detail. Next, the calculator 1003 receives the information values (rk-1 and Pk-1) stored during a frame period corresponding to the 1-frame interval, and receives new information values (rk and p>) from the controller 1001, such that it can calculate differential values (dvk and dpk) of the received information values. In this case, as can be seen from FIG. 20, the calculator 1001 calculates a differential value of the band position information and a differential value of the CQI value. However, the band position information having a relatively-low variation determines whether the data Rx band position is changed less times than in the CQI value information. Preferably, if the controller 1001 determines whether the data Rx band position is changed or not, and informs the calculator 1003 of the variation of data Rx band position via the control signal (c) , the differential calculation process reduces the amount of Tx signal only when the data Rx band position variation is notified to the calculator 1003 via the control signal (c), so that the amount of overhead can also be reduced. Thereafter, the differential values (dvn and dpk) generated by the calculator 1003 may enter the encoder 1004. The encoder 1004 receives the differential band position information (dpk) and the differential CQI value (dvk) according to the control signal (c) of the controller 1001, encodes the received data (dpk and dvk) in various ways as shown in FIGS. 14 to 19. If required, a specific sequence performs data mapping for a special function, and may generate Tx data (L) . The Tx data (L) is transmitted to the Node-B via the antenna after passing through the duplexer. In the meantime, the selected CQI reporting scheme for determining the CQI reporting on the basis of the UE priority information will hereinafter be described in detail. In this case, the UE priority is determined on the basis of a channel variation status of UEs, a CQI transmission time interval, and a throughput in a wireless communication environment. In order to effectively use the limited radio resources, the selected CQI reporting scheme considers a channels status, a CQI transmission time, and a data rate when determining the UE priority reporting the CQI, so that it transmits the CQI in descending numerical orders of the UE priority. As a result, the selected CQI reportint scheme reduces the CQI overhead, can effectively use the resources, and sufficiently considers a changing channel status via the limited CQI reporting channel using a differential CQI value, so that the system performance is improved. FIG. 21 is a block diagram illustrating a method for selecting UEs going to report CQI values according to a preferred embodiment of the present invention. Referring to FIG. 21, in order to measure a channel quality of downlink (DL) data, the Node-B transmits a common pilot signal to individual UEs of users, and each UE measures a SINR of the received signal and determines a CQI index indicating a channel quality level of downlink (DL) data. Each UE transmits this CQI value in an uplink direction to effectively report the CQI value, so that the resources can be maximally used. According to the present invention, the system of FIG. 21 transmits the CQI value only when user data to be transmitted to a DL traffic path exists, so that it can reduce the number of unnecessary reporting times. If there are several users who desire to transmit data at the same time, the Node-B selects a specific UE acting as the CQI transmission target according to the priority information determined by a variety of factors, so that it reduces the number of channels used for CQI transmission. And, the system firstly transmits the CQI of the high-priority user according to the channel status and condition of the users, so that it solves the CQI overhead problems and improves the performance. In the meantime, the priority of UEs (i.e., the UE priority) can be determined by the following characteristics, as represented by the following equation 9: [Equation 9] where, "i" is indicative of index information of UEs, VVQI is indicative of the degree of a difference between a CQI value of a previous sub-frame of the i-th UE and a CQI value of a current sub-frame of the i-th UE, ∆tcot indicates how long the transmission time interval between a previous CQI value of the i-th UE and a current CQI value is, and SINR, is indicative of the degree of the SINR value of the i-th UE. And, deterro^ is indicative of the degree of errors of Rx data of the i-th UE, {T, system, and Rt is how tall the data rate of the i-th UE is. If the above-mentioned characteristics increase, the priority of each UE also increases. Therefore, the priority function P (xl, x2,..., xn) shown in Equation 9 is configured in the form of an increasing function for each characteristic parameter (xi). In order to construct the characteristic function, a specific weight is multiplied by each characteristic parameter according to system requirements, as represented by the following equation 10: [Equation 10] where — b indicate the weights assigned to individual parameters. As described above, the UE having the priority determined by Equation 9 or 10 is selected as a CQI reporting object by the Node-B. In this case, the UEs are selected as the CQI reporting objects in descending priority orders. For this purpose, the Node-B transmits a CQI transmission request message to high-priority UEs selected as the CQI reporting objects, and the CQI transmission request message is transmitted to the UEs along with Tx data of each UE. In the meantime, there is no need to consider all the characteristic parameters shown in Equation 9 or 10. Only some characteristic parameters may be considered according to weights multiplied by characteristic parameters for the system requirements. Generally, if feedback information to be transmitted is a CQI of a DL channel, the most important matters of the above-mentioned characteristic parameters are the values of VVQI and ∆tCQT . In this case, VVQI is indicative of a difference between a CQI value of a previous frame and a CQI value of a current frame, and ∆tCQT is indicative of a time interval between the CQI value of the previous frame and the CQI value of the current frame. The present invention can determine the priority of UEs by considering only the above-mentioned two values VQI and AtCQI . In the meantime, in order to more correctly indicate the DL-channel quality, there is proposed a method for sequentially assigning weights in the order of increasing- subscripts of the weights coi~a>&. FIG. 22 shows a method for sequentially selecting UEs reporting the CQI using the method of FIG. 21 according to the present invention. FIGS. 23 — 26 show detailed concepts of the sequential selection method shown in FIG. 22 according to the present invention. Referring to FIGS. 22 and 23~26, the present invention basically assumes that the CQI transmission request occurs only when data to be transmitted by the UE exists. And, it is assumed that each UE receives two uplink channels (e.g., HD-SICH) for CQI transmission from the Node-B. In order to easily recognize the relationship between data and CQI of individual UEs, the DL traffic data (See upper part of FIGS. 22 and 23 — 26) and the CQI traffic data (See lower part of FIGS. 22 and 23~26) of the same UE are denoted by the same oblique lines, as shown in FIGS. 22 and 23~26. Referring to FIG. 23, the Node-B transmits the CQI transmission request to UE3 and UE4, each of which has the DL traffic data in the two allocated UL channels at step ®. Provided that the VyQK value is not high due to the rapidly- changing channels of other UEs at step ©, UE1 and UE2 are selected as the transmission targets by the ktCQI value. Next, if the UE1 has a low SINR at step ©, the UE1 is selected by the SINRi value. If unexpected errors occur in Rx data of the UE4, the UE4 can also be selected by the det_errori value. In the meantime, since the UE having data in the DL traffic information is only the UE1, only the UE1 is selected as the CQI reporting object at step ©. The UE which is going to transmit the CQI at the above steps is selected by the Equations 9 and 11. Generally, the number of selected UEs is equal to the number of channels allocated for CQI transmission. If the number of UEs, each of which has Rx data in the DL traffic, is less than the number of allocated channels, the Node-B transmits only the CQI of the UE having data to be received. During the initial selection step, the Node-B may select the UE, which is going to transmit the CQI, from among several UEs in consideration of channel capacity for CQI transmission of each UE. During the initial selection step, the Node-B selects all of UEs, each of which has priority higher than a predetermined priority value. Thereafter, if the Node-B has difficulty in reporting the CQI values of all the selected UEs in consideration of the CQI reporting scheme and channel capacity, the Node-B may transmit the CQI transmission request to only some UEs instead of all the selected UEs. Referring to FIG. 24, if unexpected errors occur in Rx data of the UE3 at step ©, the UE3 is selected by the det_errori value, and at the same time the UE4 is selected by the AtCQti value. Next, the UE2 is selected by the AtCQI value at step©. Provided that the DL channel of the UE3 is abruptly changed and errors occur in Rx data of the UE1, the weight multiplied by the VyQI weight multiplied by the det_errorj. value, so that the UE3 is selected. Needless to say, the above-mentioned cases has been disclosed as examples of the present invention, and the weight multiplied by each parameter may also be changed. Referring to FIG. 25, provided that all the UE channels are abruptly changed at step ©, individual UEs have the same VVQl) value, so that the UE3 and the UE4 are selected by the Atc value. Thereafter, the individual UEs have the same VVQIi value at step ®, so that the UE1 is selected if the throughput of the UE1 is less than a requested throughput. And, if the channel of the UE3 is abruptly changed, the UE3 is selected by the VVQU value. Thereafter, the Node-B selects the UE1 having the abruptly-changing channel and the UE2 having a long Tx-time interval at step ®. In this way, if the UE is selected as a CQI transmission target, the Node-B transmits the CQI transmission request rressage to the UEs, so that the CQI may be reported to individual UEs according to the allocated band and capacity. Finally, referring to FIG. 26, if the channels of all the UEs are abruptly changed, the UE3 and the UE4 are selected as the CQI reporting objects by the AtCQl value at step ©. The Node-B selects the UE1 and UE4 receiving data at step ©. If all the channels are not abruptly changed, the Node-B selects the UE2 and the UE4 as the CQI reporting objectts by the &tCQI value at step ©. According to the concepts of FIGS. 22 and 23 to 26, the Node-B transmits the CQI request message to only the UE having Rx data in the DL traffic information. In the case of determining the individual priority, weights are sequentially assigned to the priority function of Equation 10 in the order of subscripts attached to the weights. However, differently from the concepts of FIGS. FIGS. 22 and 23 to 26, it should be noted that other examples of the present invention can be readily implemented by those skilled in the art. If there are several UEs capable of transmitting the CQI using the method for transmitting the feedback information, a differential CQI value may be transmitted to the UEs, and a detailed description thereof will hereinafter be described in detail. FIG. 27 is a conceptual diagram illustrating a method for reporting the CQI using a differential value when the number of selected UEs is a plural number according to the present invention. The system of FIG. 27 is based on the CQI reporting scheme for reporting the priority information of individual UEs, and employs a differential CQI value to effectively use radio resources, so that it reduces the number of bits of the CQI information. According to the concept of FIG. 27, in the case of using the differential value under the abruptly-changing channel situation, CQI information of UEs which desire to transmit data can be effectively transmitted via a limited channel, resulting in an increased system performance. The above-mentioned scheme is called a SDV (Selection Differential Value) CQI reporting scheme, and a detailed description thereof will hereinafter be described in detail. The SDV CQI reporting scheme measures the SINR of a received signal (Rx signal) in the same manner as in the above-mentioned selection CQI reporting scheme, and measures the DL-channel status on the basis of the measured SINR of the Rx signal. The priority is determined according to the measured CQI value and the UE condition. If there are several UEs which are going to transmit the CQI according to the priority, the Node-B transmits the CQI using the differential value indicating a difference between the previous CQI value and the current CQI value. The SDV CQI reporting scheme can reduce the CQI overhead because the UE for selectively transmitting the CQI is determined according to the priority information, and at the same time it reports the differential CQI value so that it reduces the number of information bits. As a result, CQI of several UEs can be effectively transmitted to a destination without increasing an additional CQI transmission channel. There are a variety of schemes for implementing the above-mentioned scheme, and detailed description thereof will hereinafter be described in detail. FIGS. 28~30 are conceptual diagrams illustrating methods for reporting the CQI using a differential value when the number of selected UEs is a plural number according to the present invention. Referring to FIG. 28, the Node-B equally allocates the same resources to individual CQI reporting channels. Needless to say, the UEs receiving the CQI transmission channel are selected as the CQI transmission targets in consideration of their priority information. According to the concept of FIG. 28, resources are equally allocated to the selected UEs, so that the CQI values having the same accuracy are transmitted to the selected UEs. Referring to FIG. 29, some UEs having low priority have no opportunity for transmitting data according to the CQI variation, however, the remaining UEs having high priority divide resources into sub-units and transmit the data via the divided resources. UEs having priority higher than a predetermined reference value are selected as the CQI transmission targets according to the priority function shown in Equations 9 to 11. However, if the CQI cannot be transmitted to all the selected UEs according to the differential values used for CQI transmission, the concept of FIG. 29 excludes some UEs from the CQI transmission targets in consideration of channel transmission capacity according to a predetermined condition. In this case, the predetermined condition indicates a difference between a CQI value of a previous transmission frame and a CQI value of a current frame on the basis of the priority information indicating whether the reception end has correctly recognized the previous CQI value. In other words, according to a first selection step for selecting the UEs as the CQI reporting objects, the Node-B determines whether the priority of each UE is higher than a predetermined value, and selects all the UEs, each of which has the priority higher than the predetermined value, as the CQI reporting objects. Thereafter, at a second selection step, the Node-B re-selects the UE used as the CQI reporting objectt in consideration of channel capacity. The priority considered at the first selection step may be equal to the priority considered at the second selection step, however, the objects considered at first and second steps are different from each other, so that different weight may be assigned to individual parameters. Finally, according to the concept of FIG. 30, UEs, which are selected according to the priority information and share the CQI transmission channel, are allocated a different amount of resources. In this case, the Node-B can more precisely transmit the CQI information of the high-priority UE. Exemplary methods of the above-mentioned SDV CQI reporting scheme will hereinafter be described in detail. FIG. 31 is a conceptual diagram illustrating a method for sequentially selecting UEs reporting the CQI using a differential value when the number of selected UEs is a plural number according to the present invention. FIGS. 32~33 show detailed concepts of the sequential selection method shown in FIG. 31 according to the present invention. Referring to FIGS. 31 to 33, the Node-B reports the CQi only when DL data to be transmitted exists. If the CQI information of at least two UEs is transmitted at the same time, the concept of FIGS. 31 to 33 assumes that a differential value between the CQI value of a previous sub- frame and the CQI value of a current sub-frame should be reported. In order to easily recognize the relationship between data and CQI of individual UEs, the DL traffic data (See upper part of each drawing) and the CQI traffic data (See lower part of each drawing) of the same UE are denoted by the same oblique lines, as shown in FIGS. 22 and 23~26. Referring to FIG. 32, if the channels of all users are not abruptly changed at step ®, transmission of the CQI values of the UE2 and UE4 is selected by the VVQh value. In this case, since several users are selected as CQI transmission targets, the CQI values of the individual users should be transmitted as differential values. Next, if the channel of the UE2 is abruptly changed at step ©, the UE2 is selected by the VVQI value. In this case, the number of UEs used as the CQI transmission targets is not a plural number, so that the Node-B does not transmit the differential value, and requests transmission of all CQI values of the current sub-frame. Thereafter, if a Rx SINR of the UE3 is low at step requests the UE3 to transmit the CQI by the SINR± value. Next, as shown in FIG. 33, if channels of all UEs are abruptly changed at step ®, the CQI information of all users is transmitted as a differential value. In this case, an amount of information for CQI transmission is reduced, so that the CQI differential value transmitted from each UE has bits of less than 1/4 as compared to bits required for the other case in which all the CQI information of the current sub-frame. As a result, although the CQI transmission channel is not additionally transmitted, all the CQI values of the UE1, UE2, UE3, and UE4 can be transmitted. Thereafter, if unexpected errors occur in the Rx data of the UE3 at step ©, the Node-B can transmit only the CQI value of the UE3 according to the det_errorx value. If the throughput of the UE1 is lower than a required throughput, the CQI value of the UE1 can be transmitted by the Ti high, the CQI values of the UE2 and UE4 are transmitted as a differential value by the VVQI value. If the SINR value of the UE4 is low, the CQI values of the UE2 and UE4 are transmitted as a differential value by the SINRx value. The above-mentioned steps have exemplarily disclosed the method for selecting UEs used as the CQI transmission targets, and calculating a differential value when several selected UEs exist, so that the capacity of the allocated CQI transmission channel and the amount of differential value information can be changed in various ways. However, according to the method for calculating the CQI transmission channel capacity and the differential value, the degree of decreasing information amount may be unique for each system, and the decreasing information may maintain a specific level for a predetermined period. Based on the above-mentioned explanation, the general trigged CQI reporting scheme can be defined as follows. The factors to be considered for the CQI reporting can control the CQI reporting scheme of each UE by determining whether the transmission end has correct CQI information. If the channel variation is not high at a previous reporting time and a current reporting time, a corresponding UE may be excluded from the CQI reporting objects at the current CQI reporting time. Also, if the channels of several UEs are abruptly changed at the previous and current reporting times, the present invention must correctly transmit a large amount of UE information to the transmission end. For this purpose, the present invention excludes a specific UE which has not established as the CQI reporting objectt from all the UEs, and must distribute the CQI reporting channel resources to the remaining UEs. This distribution method may equally distribute the channel resources to individual UEs, or may allocate different-amount resources to the UEs in consideration of the characteristics (e.g., priority or QoS) of the UEs. If the CQI channel resources are insufficient, the accuracy of the CQI reported by each UE may be decreased, and an overall CQI reporting and a differential CQI reporting can be made available. FIG. 34 is a block diagram illustrating characteristics of a Node-B according to another preferred embodiment of the present invention. Referring to FIG. 34, in order to perform the feedback-information requesting method and the feedback- information receiving method according to the present invention, the Node-B includes the priority decision unit 1201, the UE selection unit, and the feedback-information transmission request unit 1203. If there are several UEs which are going to transmit feedback information at a specific timeslot, the priority decision unit 1201 determines the priority of the UEs. The above-mentioned priority decision may be performed by a variety of parameters shown in FIG. 34. The parameters do not have the same importance, so that the system of FIG. 34 may further include the weight assignment unit 1201a for assigning different weights according to importance information of the parameters. The weights a>y ~ ab may be set to "0" if some parameters are excluded from parameters to be considered. Individual parameters to which differential weights are allocated are summed up by the adder 1201b, the priority information is completed as denoted by Priorityhigh. The UE selection unit 1201 receiving the above- mentioned priority information selects UEs used as the CQI reporting objects in consideration of the received priority information. In this case, the UE selection unit 1201 considers the allocation degree of the UL channel to be used for the CQI reporting of individual UEs, and selects UEs which are going to report the CQI. In more detail, the Node-B of FIG. 34 determines constituent modules of the UE selection unit 1201. If the priority is higher than a predetermined value, the Node-B selects a corresponding UE as the priority CQI reporting object, and may exclude some UEs from selected UEs according to channel condition information. The UE selection unit 1210 considers not only the priority information but also the UL channel allocation information at a single step, and may select the CQI reporting object according to the considered result. If the UE which is going ro transmit feedback information such as CQI is selected, information of the selected UE is transmitted to the feedback-information transmission request unit 1203. The feedback-information transmission request unit 1203 transmits a CQI transmission request to the selected UE selected as the CQI transmission object.- The feedback-information transmission request unit 1203 may include a resource-allocation adjusting unit 1203a and a CQI request signal generator 1203b. The resource- allocation adjusting unit 1203a determines whether the UL channel, via which each UE generating the CQI transmission request can report the CQI, will be equally allocated to individual UEs, and determines whether resources proportional to the priority information of the UEs will be allocated. The CQI-request signal generator 1203b generates the CQI request signal according to the resource allocation information. The generated CQI request signal is transmitted to the selected UEs by the transmitter (not shown), and the receiver (not shown) receives the CQI transmitted from the UEs having received the CQI request signal. In the meantime, a method for effectively reporting initial CQI information to solve the problems of the conventional art will hereinafter be described in detail. In this case, the conventional problem occurs when the UE used as a transmission object has no available CQI information during the transmission of initial DL data. FIG. 35 is a conceptual diagram illustrating a method for delaying data transmission until the CQI is received from the UE, and transmitting the delayed result according to a preferred embodiment of the present invention. The embodiment of FIG. 35 shows an exemplary case in which the Node-B has data to be transmitted via the downlink channel and transmits data after the lapse of a long idle time, so that no CQI is received from the UE. In brief, the embodiment of FIG. 35 has no information available for recognizing the DL-channel status. In this case, as can be seen from FIG. 35, the Node-B transmits the CQI reporting request to the UE at the time (t) , receives the CQI message from the UE, and transmits data to the UE at the (t+1) time. As a result, Tx data may be delayed. However, the 3GPP LTE scheme consumes the time of about 0.5ms from the CQI reporting request time of the Node-B to the CQI reception time of the Node-B. The time of about 0.5ms is much shorter than a latency time of most traffic data. If the Node-B waits for a feedback message of the initial CQI, receives the CQI reporting message from the UE, and allocates DL resources on the basis of the received CQI message, the embodiment of FIG. 35 can more effectively manage resources according to a DL-channel situation recognized by the CQI. The time delay of "+1" shown in FIG. 35 indicates the above-mentioned delay. In the case of the above-mentioned 3GPP LTE, it is preferable that the time delay may be set to 1 sub-frame. The above-mentioned scheme is called a delayed initial data transmission scheme. The delayed initial data transmission scheme will be described in detail from the viewpoint of data sequences to be transmitted at individual steps. FIG. 36 shows the preferred embodiment of FIG. 35 from the viewpoint of a data stream to be transmitted according to individual steps according to the present invention. Referring to FIG. 36, if data to be transmitted via the DL exists, a storage unit for storing the data is required. FIG. 36 shows a method for storing the DL transmission data in the buffer. In this way, the embodiment of FIG. 36 determines whether the buffer stores CQI information available for a corresponding DL channel to transmit DL data. If the above-mentioned CQI information is pre-guaranteed, the embodiment of FIG. 2 6 allocates the DL resources according to the general scheduling, and transmits data via the allocated DL resources. However, in the case of the initial data transmission (e.g., if data is initially transmitted via a corresponding DL channel, or- if data is transmitted after the lapse of a long idle time), the embodiment of FIG. 36 has no CQI information available for a corresponding DL- channel situation. In this case, the Node-B transmits the CQI reporting request message to the UE via the DL traffic channel at step (D. Upon receiving the CQI reporting request message, the UE reports the CQI of a corresponding DL via the UL. In this case, the initial CQI information generated by the UE is typically generated on the basis of a common pilot signal simultaneously transmitted along with the CQI request message. However, it should be noted that the above-mentioned initial CQI information may be generated on the basis of a predetermined signal capable of indicating a DL-charmel situation. If the Node-B receives the CQI, it transmits DL data delayed for a predetermined time consumed for receiving the CQI reporting message. The delay degree of DL data may be indicated by a predetermined timeslot, a sub-frame, or an OFDM symbol according to the time consumed for receiving the initial CQI reporting message. As described above, the 3GPP LTE scheme requires the time of about 0.5ms to receive the initial CQI message. The time of about 0.5ms corresponds to the length of a sub-frame selected by most schemes. Therefore, as shown in FIG. 36, the embodiment of FIG. 36 considers the time consumed for receiving the initial CQI, and delays Tx data by a predetermined time corresponding to a single sub-frame, so that it transmits the delayed data. According to the above-mentioned delayed initial data transmission scheme, the CQI information transmitted from the UE may be configured in the form of a differential CQI value, so that it reduces the number of bits indicating corresponding information and effectively sues the UL resources. In other words, the delayed initial data transmission scheme transmits only a difference between a previous CQI value and a current CQI value, so that it may transmit a small amount of information as compared to the scheme for transmitting all the CQI values. However, if the above-mentioned initial data transmission (e.g., if data is initially transmitted via a corresponding DL channel, or if data is transmitted after the lapse of a long idle time) is performed under the condition that there is no CQI information indicating the DL-channel situation, the CQI does not have previous CQI information at a sub-frame given behind the initial data transmission time, so that the delayed initial data transmission scheme cannot reduce the amount of corresponding information via the differential CQI. Therefore, the present invention provides a method for establishing a common default CQI at both the Node-B and the UE during the initial data transmission, and reporting/receiving only the differential CQI during the next CQI transmission/reception time. In more detail, as shown in FIG. 36, if the UE receives the CQI reporting request message from the Node-B at step (2), the UE replies to the CQI reporting request message and transmits a differential value between a stored default CQI value and the generated CQI value, instead of transmitting all the CQI values. The Node-B uses the same default CQI value as the UE's default CQI value, acquires all the CQI values (i.e., an overall CQI value) on the basis of the received differential value, allocates downlink resources to the UE, and transmits data to the UE via the allocated DL resources. As a result, the above-mentioned scheme of FIG. 36 can more effectively use the UL traffic resources than the method for reporting the entire CQI value. The scheme of FIG. 36 can be applied to all steps from the CQI reporting step replying to the CQI reporting request message for initial data transmission. Next, a method for allocating DL resources without intentionally delaying data transmission in the case of the initial data transmission will hereinafter be described in detail. FIG. 37 is a conceptual diagram illustrating a distributed resource allocation scheme and a localized resource allocation scheme according to the present invention. The distributed resource allocation scheme shown in the left side of FIG. 37 distributes resources for data transmission to several frequency bands, instead of allocating the resources to only a specific frequency band, so that data is transmitted via the distributed resources. The localized resource allocation scheme shown in the right side of FIG. 37 allocates resources for data transmission to only a specific frequency band. Generally, provided that relatively correct information of individual frequency bands is recognized, the localized resource allocation scheme selects frequency band indicating good channel characteristics, and allocates resources to the selected frequency band, such that an overall throughput of the system can be increased. However, provided that information of individual frequency bands is insufficient and resources for data transmission are concentrated at a specific frequency band, the overall throughput of the system can be decreased. Therefore, the present invention provides a method for transmitting data according to the distributed resource allocation scheme shown in the left side of FIG. 37. FIG. 38 is a conceptual diagram illustrating a method for transmitting initial data according to the distributed resource allocation scheme according to a preferred embodiment of the present invention. Referring to FIG. 38, in the case of initial data transmission (e.g., if data is initially transmitted via the DL channel, or if data is transmitted after the lapse of a long idle time) under the condition that there is no available CQI information for the DL-channels status, the distributed resource, allocation scheme is designed to transmit data via the band composed of only a specific-area channel, so that an overall throughput of the system can be decreased. In order to solve this problem, the present invention provides a method for allocating/transmitting DL resources according to the distributed resource allocation scheme during the initial data transmission. As a result, although a channel situation of a specific band is poor, the present invention can reduce the number of data transmission errors because data is transmitted via the distributed channels. As shown in FIG. 38, after the initial data transmission is completed, the DL resources can be allocated according to the distributed resource allocation scheme because CQI indicating each channel condition of a corresponding DL is pre-guaranteed, and the DL resources can be allocated according to the localized resource allocation scheme. After the initial data transmission is completed, CQI information transmitted from the UE may be configured in the form of a differential CQI value according to the above-mentioned delayed initial data transmission scheme. If the CQI value is an initially-reported CQI value, a predetermined reference for calculating the differential value is required. The default CQI value commonly used for the Node-B and the UE is established and used to calculate the differential value. Differently from either the method for transmitting initial data via the resources allocated by the distributed resource allocation scheme or the method for delaying the data transmission until receiving the CQI message for the initial data transmission, a method for performing the initial data transmission using the default CQI value will hereinafter be described in detail. FIG. 39 is a conceptual diagram illustrating a method for establishing a default CQI value during the transmission of initial data, and transmitting the established default CQI value according to a preferred embodiment of the present invention. Referring to FIG. 39, if data is firstly transmitted to a specific UE or there is no available CQI value for recognizing the DL-channel situation because a long period of time elapses from the final data transmission, the UE according to the delayed initial data transmission scheme may initially generate the CQI value using a common pilot signal received along with the CQI reporting request message. However, prior to receiving the CQI reporting request message, the UE may receive the common pilot channel via a cell searching process or a synchronization acquisition process between the UE and the Node-B, such that it may recognize the DL-channel situation via the received common pilot channel. In other words, prior to initiation of the initial data transmission, the UE may easily generate the CQI indicating the most recent DL-channel.situation as compared to the Node-B. Therefore, the embodiment of FIG. 39 transmits a previous CQI value contained in the UE as a default CQI value to the Node-B before starting the initial data transmission, and the Node-B allocates DL resources via the default CQI value, and transmits data via the allocated DL resources. As shown in FIG. 39, if data is firstly transmitted, or data is transmitted after the lapse of a long idle time, the embodiment of FIG. 39 transmits data using the default CQI value received from the UE, and may continuously use the default CQI value during the next data transmission. However, it is preferable that the embodiment of FIG. 39 uses the new CQI value created by the common pilot signal transmitted along with the DL data. More preferably, if a differential CQI value is used as the CQI value, the UL resources can be more effectively used. As a result, the embodiment of FIG. 39 transmits data to the UE using resources allocated by the CQI value. FIG. 40 is a conceptual diagram illustrating a method for transmitting the CQI of each user using the default-CQI establishing method of FIG. 39 according to the present invention. If data is firstly transmitted to individual UEs (e.g., UE1 and UE2), or data is transmitted to the UEs after the lapse of a long idle time, the Node-B receives the default CQI value from the UEs. In this case, the default CQI value may be generated by a common pilot signal, which has been received during either the synchronization acquisition step or the cell searching step before the UE1 and UE2 receive the initial data from the Node-B, so that the default CQI value indicates a predetermined-level DL channel situation. In this waym if the Node-B receives the default CQI value from each UE, it is preferable that the CQI value to be received from each UE at the next step is set to the differential CQI value. In this case, as shown in FIG. 40, if there are several UEs, each of which reports the CQI within a single sub-frame, the individual UEs can effectively report the CQI. Differently from the embodiment of FIG. 40, the present invention does not report the default CQI value generated by the UE to the Node-B, and allows the Node-B and the UE to have the common default CQI value, so that it may report the next CQI value on the basis of the differential CQI value. In this case, the default CQI value commonly used by the Node-B and the UE is used as a reference value for reporting the next differential CQI, so that the default CQI value may be pre-defined by a communication system or may be generated by the module for generating the same default CQI value contained in each of the Node-B and the UE. If the initial data transmission is performed using the predetermined default CQI value, it is preferable that data may be transmitted according to the delayed initial data transmission scheme or the distributed resource allocation scheme. Characteristics of the Node-B capable of implementing the initial data transmission method according to the present invention will hereinafter be described. FIG. 41 is a block diagram illustrating an apparatus for delaying data transmission until the CQI is received during the initial data transmission, and transmitting the delayed result, and the Node-B including the apparatus according to a preferred embodiment of the present invention. Referring to FIG. 41, the Node-B according to the present invention includes a buffer 1101, a controller 1102, and a transceiver 1103 used as a transmitter/receiver. If data (DL_DATAk) to be transmitted via the DL exists, this data (DL_DATAk) is applied to the buffer 1101. In this case, the controller 1102 determines whether the available CQI value is stored in the buffer 1101. In the case of the initial data transmission (e.g., if data is firstly transmitted to a specific UE, or if data is transmitted after the lapse of a long idle time), the controller 1102 commands the transceiver 1103 to transmit the CQI reporting request message because there is no CQI value available for the buffer 1101. If the Node-B receives the CQI value from a corresponding UE by replying to the CQI reporting request message, the CQI value is transmitted to the buffer 1101 and the controller 1102 as shown in FIG. 11. Upon receiving the CQI value, the controller 1102 allocates the DL resources. In this way, after the CQI value is received in the controller 1102, the controller 1102 transmits DL data (DL_DATAk+1) . Generally, Tx DL data is delayed by a predetermined time corresponding to the 1 sub- frame as compared to the initial DL data, so that the DL data can be stably transmitted. FIG. 42 is a block diagram illustrating an apparatus for transmitting data according to the distributed resource allocation scheme, and the Node-B including the apparatus according to another preferred embodiment of the present invention. Referring to FIG. 42, the Node-B includes a buffer 1201, a controller 1202, and a transceiver 1203. The Node- B of FIG. 42 determines whether the buffer 1201 includes available CQI values during the initial DL data. If there is no available CQI value, the controller 1201 generates a command for performing initial data transmission according to the distributed resource allocation scheme, so that DL data stored in the buffer 1201 is transmitted. In this case, it should be noted that the above-mentioned Tx DL data has no delay until the CQI is received from the UE, differently from the initial DL data transmitted from the Node-B of FIG. 41. If the initial DL data is transmitted from the transceiver 1203, the embodiment of FIG. 42 receives a CQI value corresponding to the initial DL data from the corresponding UE. In this case, it is preferable that the received CQI value may be a differential CQI value created on the basis of the default CQI value commonly contained in the Node-B and the UE, so that UL resources can be effectively used. FIG. 43 is a block diagram illustrating an apparatus for transmitting data using the default-CQI value during the transmission of initial data, and the Node-B including the apparatus according to a still another preferred embodiment of the present invention. The embodiment of FIG. 43 includes a buffer 1301, a controller 1302, and a transceiver 1303. In this case, if it is determined that the buffer 1301 has no CQI value available for the initial DL data transmission at steps CD and ©, the embodiment of FIG. 43 may generate a transmission command of the initial DL data on the basis of the default CQI value. In this case, the default CQI value may be a default CQI value commonly contained in the Node-B and the UE according to the communication standard prescribed for the communication system. Otherwise, the default CQI value may be a default CQI value reported to the Node-B. In this case, the default CQI value reported to the Node-B may be generated by signals, which are received in the synchronization estimation step and the cell searching step before the corresponding UE receives the initial DL data. In this way, if the transceiver 1303 transmits the initial DL data using the default CQI value, it may receive the CQI value from a corresponding UE. In this case, provided that a differential value between the received CQI value and the ~ above-mentioned default CQI value is calculated and used, the UL resources can more effectively used. Althougn tne aoove-mentionea prererrea emooaxments have disclosed an exemplary case in which the reception end of data transmits the CQI value and the corresponding band position information to the transmission end, it should be noted that all kinds of predetermined feedback signals, each of which transmits both feedback information corresponding to the data reception and the position information of the data Rx band, may also be covered with the scope and spirit of the present invention. It should be noted that most terminology disclosed in the present invention is defined in consideration of functions of the present invention, and can be differently determined according to intention of those skilled in the art or usual practices. Therefore, it is preferable that the above-mentioned terminology be understood on the basis of all contents disclosed in the present invention. It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the invention. Thus, it is intended that the present invention cover the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents. [industrial Applicability] As apparent from the above description, the present invention transmits not only the CQI value but also the Rx band position information as feedback information, so that it can reduce the number of errors created when the Node-B tracks the CQI variation in the OFDM system capable of transmitting data via divided Tx bands. Therefore, the present invention can be effectively used for the cognitive radio communication system. The present invention allows the differential information to indicate the increment, decrement, and the same status between the current signal and the previous signal, so that it can more accurately track the CQI information. The present invention can easily change the range of a differential value according to the variation speed of the differential information, and the mobility is gradually emphasized. As a result, the present invention can be effectively applied to the rapidly-changing channel. If several UEs which desire to transmit feedback information at a specific timeslot, the Node-B decomposes the resources allocated for transmission of the feedback information according to priority information of individual UEs, so that the allocated resources can be effectively used. As a result, the present invention can be effectively applied to a communication system equipped with several UEs. The present invention provides a method for effectively transmitting data at the initial data transmission. If data is not transmitted to a destination during a long period of time, or if data is firstly transmitted to the destination, the present invention can be effectively used. 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. [CLAIMS] [Claim 1] A method for allowing a first reception end to transmit feedback information, the method comprising: receiving a transmission request message of the feedback information from a transmission end; generating the feedback information including both band position information indicating a position of a band where data to be received and a channel quality indication value indicating a channel quality of the band; and transmitting the feedback information. [claim 2\ The method according to claim 1, wherein: when a number of total reception end, including the first reception end, which are going to transmit the feedback information at a specific time is plural number, the feedback information transmission request message is transmitted to the first reception end determined in consideration of individual priority information of the total reception ends. [Claim 3] The method according to claim 2, wherein: the feedback information includes a channel quality indicator, and the priority information is determined in consideration of at least one of an element including a difference between the channel quality indicator of a previous frame and the channel quality indicator of a current frame, and a reporting time interval between the channel quality indicator of the previous frame and the channel quality indicator of the current frame. [Claim 4] The method according to claim 3, wherein the elements considered for the priority information further include first information indicating whether a signal-to- noise ratio (SNR) of a corresponding transmission end is low, second information indicating whether the data received has a low error rate, third information indicating whether a data rate of the corresponding transmission end is high, and fourth information indicating whether a throughput of the corresponding reception end is lower than a system-required throughput. [Claim 5] The method according to claim 1, wherein the band position information and the channel quality indication value are indicated by differential signals, which indicate a differential value between a previous band position and a current band position, and a differential value between a previous channel quality indication value and a current channel quality indication value, respectively. [Claim 6] The method according to claim 5, wherein the differential signals indicate any one of a first status in which a current signal is higher than a previous signal, a second status in which a current signal is lower than a previous signal, a third status in which a current signal is equal to a previous signal. [Claim 7] The method according to claim 5 or 6, wherein the differential signals are adjustable signals, which have an adjustable range of a difference value between the previous signal and the current signal. [Claim 8] The method according to claim 1, wherein at least one of the band position information and the channel quality indication value is merged-encoded. [Claim 9] The method according to claim 8, wherein: at least one of sequences of a specific number corresponding to a difference between a first number of cases and a second number of cases is used to define a special function, in which the first number of cases indicates a number of cases the differential signals for the band position information and the channel quality indication value can represent, and the second number of cases indicates a number of cases which can be represented by a number of bits which can represent the first number of cases. [Claim 10] The method according to claim 9, wherein the special function reports a transmission error of the band position information and the channel quality indication value. [Claim 11] The method according to claim 1, wherein the feedback information transmission request message is generated from the transmission end which desires to start transmission of initial data to the first reception end. [Claim 12] A method for reporting feedback information of a data reception channel, the method comprising: transmitting band position information indicating a position of a data reception band of the data reception channel; and transmitting a channel quality indication value indicating a channel quality of the data reception band. [Claim 13] The method according to claim 12, wherein the transmitting the band position information and/or the transmitting the channel quality indication value report differential values indicating a variation of the band position information and a variation of the channel quality indication value, respectively. [Claim 14] The method according to claim 12 or 13, wherein the transmitting the band position information is performed less frequently than the transmitting the channel quality indication value. [Claim 15] The method according to claim 12 or 13, wherein the transmitting the band position information and the transmitting the channel quality indication value are performed simultaneously. [Claim 16] The method according to claim 12 or 13, wherein one or more bit sequences for representing a plurality of the band positions information and the channel quality indication values are segmented and transmitted at different transmission timing. [Claim 17] A method for requesting transmission of feedback information, the method comprising: if there are a plurality of reception ends which are going to transmit the feedback information at a specific timeslot, determining individual priority information of the plurality of reception ends; selecting a specific reception end for transmiting the feedback information, in consideration of the determined individual priority information of the plurality of reception ends; and requesting transmission of the feedback information from the selected reception end. [Claim 18] The method according to claim 17, wherein the plurality of reception end which are going to transmit the feedback information at the specific timeslot are reception end having data received. [Claim 19] The method according to claim 18, wherein: the feedback information includes a channel quality indicator, and the priority information is determined in consideration of at least one of an element including a difference between the channel quality indicator of a previous frame and the channel quality indicator of a current frame, and a reporting time interval between the channel quality indicator of the previous frame and the channel quality indicator of the current frame. [Claim 20] The method according to claim 19, wherein the elements considered for the priority information further include first information indicating whether a signal-to- noise ratio (SNR) of a corresponding transmission end is low, second information indicating whether the data received has a low error rate, third information indicating whether a data rate of the corresponding transmission end is high, and fourth information indicating whether a throughput of the corresponding reception end is lower than a system-required throughput. [Claim 21] The method according to claim 19 or 20, wherein the priority information is determined by- assigning weights to the individual elements. [Claim 22] A method for receiving feedback information, the method comprising: if there are a plurality of reception ends which are going to transmit the feedback information at a specific timeslot, requesting transmission of the feedback information from a first reception end selected in consideration of individual priority information of the plurality of reception ends; and receiving the feedback information including both band position information indicating a position of a data reception band of the first reception end and a channel quality indication value indicating a channel quality of the data reception band from the first reception end. [Claim 23] The method according to claim 22, wherein the feedback information includes differential value information of each of the band position information and the channel quality indication value. [Claim 24] A method for requesting transmission of feedback information, the method comprising: if there are a plurality of users who are going to transmit the feedback information at a specific timeslot, determining individual priority information of the the plurality of users; selecting a specific user for transmiting the feedback information, in consideration of the determined individual priority information of the plurality of users; and if a number of the selected users is plural number, requesting transmission of a differential value of the feedback information of the selected users. [Claim 25] The method according to claim 24, wherein the differential value for use in the requesting transmission of the differential value is a reduced value reduced to a extent that an amount of the transmitted feedback information is less than channel capacity allocated for the transmission of the feedback information of the selected users. [Claim 26] The method according to claim 24, further comprising: if there are a plurality of the selected users in the selecting the specific users, and the differential value of the feedback information to be transmitted by the selected users is greater than channel capacity allocated for the transmission of the feedback information, selecting high-priority users within the allocated channel capacity, in which the requesting the transmission of the differential value requests transmission of the feedback information from the users selected at the selecting the high-priority users. [Claim 27] A method for transmitting data of a Node-B, the method comprising: transmitting a request message of feedback information to a User Equipment (UE); receiving the feedback information from the UE according to the feedback information request message; and after receiving the feedback information, starting transmission of downlink data. [Claim 28] The method according to claim 27, wherein the feedback information at the receiving the feedback information is generated from the UE by a common pilot signal having been transmitted along with the feedback information request message. [Claim 29] The method according to claim 27 or 28, wherein: the Node-B and the UE include the same default feedback information, and the receiving the feedback information includes: receiving a differential value between the default feedback information of the UE and feedback information generated by the feedback information request message; and acquiring the generated feedback information using the received differential value and the default feedback information stored in the Node-B. [Claim 30] A method for receiving data of a User Equipment (UE), the method comprising: receiving a feedback information request message from a Node-B; transmitting a differential value between feedback information generated by the feedback information request message and default feedback information commonly contained in the Node-B and the UE; and receiving data via resources allocated from the Node-B on the basis of the differential value. [Claim 31] The method according to claim 30, wherein: the receiving the feedback information request message includes receiving a common pilot signal, and the generated feedback information is generated by the common pilot signal. [Claim 32] A method for transmitting data of a Node-B, the method comprising: if available feedback information is not received from a User Equipment (UE), allocating downlink resources according to a distributed resource allocation scheme; and starting transmission of initial downlink data to the UE via the allocated downlink resources. [Claim 33] The method according to claim 32, further comprising: after performing the starting transmission of the initial downlink data, receiving feedback information generated by the UE according to the initial downlink data transmission; and changing the distributed resource allocation scheme used as a downlink resource allocation scheme to a localized resource allocation scheme on the basis of the received feedback information. [Claim 34] The method according to claim 32 or 33, wherein the Node-B and the UE include the same default feedback information, and the method further comprises: after performing the starting transmission of the initial downlink data, receiving a differential value between the default feedback information of the UE and the feedback information generated by the UE by the initial downlink data transmission, and acquiring the generated feedback information using the received differential value and the default feedback information stored in the Node-B. [Claim 35] A method for receiving data of a User Equipment (UE), the method comprising: receiving initial downlink data via downlink resources allocated by a distributed resource allocation scheme; transmitting a differential value between feedback information replying to the reception of the initial downlink data and default feedback information commonly contained in both the UE and a Node-B to the Node-B; and receiving downlink data generated after the initial downlink data from the Node-B via downlink resources allocated on the basis of the differential value. [Claim 36] The method according to claim 35, wherein the downlink data generated after the initial downlink data is received via downlink resources allocated by a localized resource allocation scheme. [Claim 37] A method for transmitting data of a Node-B, the method comprising: receiving default feedback information established by a User Equipment (UE); and transmitting initial downlink data via downlink resources allocated on the basis of the default feedback information. [Claim 38] The method according to claim 37, wherein the default feedback information is generated by a downlink signal created before the transmitting the initial downlink data. [Claim 39] A method for transmitting data of a Node-B, the method comprising: establishing default feedback information to be equally used by both a User Equipment (UE) and the Node-B; transmitting initial downlink data via downlink resources allocated on the basis of the default feedback information; and receiving differential feedback information from the UE after the transmitting the initial downlink data. [Claim 40] A method for receiving data of a User Equipment (UE), the method comprising: establishing default feedback information, and transmitting the established default feedback information to a Node-B; and receiving initial downlink data transmitted via downlink resources allocated on the basis of the default feedback information. A method for transmitting/receiving feedback information and a method for transmitting/receiving data using the same are disclosed, which acquire accurate channel information and reduces an amount of overhead, and effectively allocate resources during the initial transmission time A method for allowing a first reception end to transmit feedback information includes receiving a transmission request message of the feedback information from a transmission end, generating the feedback information including both band position information indicating a position of a data where data is received and a channel quality indication value indicating a channel quality of the band, and transmitting the feedback information. |
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| Patent Number | 271391 | |||||||||||||||||||||
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| Indian Patent Application Number | 540/KOLNP/2009 | |||||||||||||||||||||
| PG Journal Number | 09/2016 | |||||||||||||||||||||
| Publication Date | 26-Feb-2016 | |||||||||||||||||||||
| Grant Date | 18-Feb-2016 | |||||||||||||||||||||
| Date of Filing | 10-Feb-2009 | |||||||||||||||||||||
| Name of Patentee | LG ELECTRONICS INC. | |||||||||||||||||||||
| Applicant Address | 20, YEOUIDO-DONG, YEONGDEUNGPO-GU, SEOUL | |||||||||||||||||||||
Inventors:
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| PCT International Classification Number | H04Q 7/38,H04L 27/26 | |||||||||||||||||||||
| PCT International Application Number | PCT/KR2007/004014 | |||||||||||||||||||||
| PCT International Filing date | 2007-08-22 | |||||||||||||||||||||
PCT Conventions:
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