Title of Invention

"APPARATUS AND METHOD FOR DETERMINING A DATA RATE OF PACKET IN A MOBILE COMMUNICATION SYSTEM"

Abstract

Disclosed is a mobile station for determining a data rate for a packet data service in a mobile communication system including a base station, and the mobile station being provided with a voice service and a packet data service from the base station. In the mobile station, a receiver receives orthogonal code allocation information indicating the number of orthogonal codes allocated for the packet data service, a measurer measures a CIR using a received pilot channel, and a controller determines a data rate corresponding to the measured CIR, controls the determined data rate based on the number of the allocated orthogonal codes, and determines a controlled data rate.

Full Text

PACKET DATA IN A MOBILE "COMMUNICATION SYSTEM BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates generally to a. mobile communication, System supporting a multimedia service including voice and packet data services, and in particular, to an apparatus and method for determining a data rate of packet data. 2. Description of the Related Art A typical mobile communication system, such as an IS-2000 CDMA (Code Division Multiple Access) mobile communication system, has been designed to support a voice service only. However, over time, the mobile communication system has been developed to support a data service as well, in order to meet the growing requirement for high-speed data transmission. Further, a so-called "HDR (High Data Rate)" mobile communication system has been proposed to support a high-speed data service only. As stated above, the existing mobile communication system was designed to support either the voice service only, or the data service only. That is, although the mobile communication system is required to simultaneously support the voice service and the data service, the conventional mobile communication system was designed to separately support the services. Therefore, there is a demand for a mobile communication system capable of supporting the data service as well as the existing voice service. SUMMARY OF THE INVENTION It is, therefore, an object of the present invention to provide an apparatus and method for controlling a data rate of packet data in a mobile communication system supporting voice and packet data services. It is another object of the present invention to provide an apparatus and method for determining a data rate of packet data considering available orthogonal (Walsh) codes and physical channel characteristics of a transmission channel and setting modulation/demodulation parameters according to the determined data rate, in a mobile communication system where a voice user and a packet data user coexist. In accordance with a first object of the present invention, there is provided a mobile station for determining a data rate for a packet data service in a mobile communication system including a base station. The mobile station is provided with a voice service and a packet data service from the base station. The mobile station comprises a receiver for receiving orthogonal code allocation information indicating the number of orthogonal codes allocated for the packet data service; a measurer for measuring a CIR (Carrier to Interference Ratio) using a received pilot channel; and a controller for determining a data rate corresponding to the measured CIR, controlling the determined data rate based on the number of the allocated orthogonal codes, and determining a controlled data rate. In accordance with a second object of the present invention, there is provided a mobile station for selecting a base station for a packet data service from a plurality of base stations in a mobile communication system including a plurality of the base stations. The mobile station is provided with a voice service and a packet data service from the base stations. The mobile station comprises a measurer for measuring CIRs using pilot channels received from the respective base stations; a controller for determining data rates corresponding to the measured CIRs of the respective base stations, and determining a base station having the highest data rate among the data rates of the respective base stations as a base station to which a data rate request is to be transmitted; and a transmitter for transmitting a signal for selecting the determined base station. In accordance with a third object of the present invention, there is provided an apparatus for determining a data rate for a packet data service in a mobile communication system including a base station and a mobile station being provided with a voice service and a packet data service from the base station. The mobile station measures a CIR using a received pilot channel, determines a data rate corresponding to the measured CIR, and transmits information on the determined data rate to the base station. The base station receives the information on the determined data rate, controls the determined data rate based on the number of orthogonal codes allocated for the packet data service, and determines a controlled data rate. BRIEF DESCRIPTION OF THE DRAWINGS The above and other objects, features and advantages of the present invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings in which: FIG. 1A illustrates a structure of a forward link data traffic channel for a packet data service according to an embodiment of the present invention; FIG. IB illustrates a structure of a forward link data traffic MAC (Medium Access Control) channel for a packet data service according to an embodiment of the present invention; FIG. 2 illustrates a structure of a forward link transmitter for a data traffic channel according to an embodiment of the present invention; FIG. 3 illustrates a structure of a forward link transmitter for a data traffic MAC channel according to an embodiment of the present invention; FIG. 4 illustrates a structure of a forward transmitter for a common power control channel (CPCCH) according to an embodiment of the present invention; FIG. 5 illustrates a scheme for orthogonally spreading a forward link channel and shifting a radio frequency (RF) band according to an embodiment of the present invention; FIG. 6 illustrates a scheme for frequency-down conversion, quadrature despreading and channel estimation according to an embodiment of the present invention. FIG. 7 illustrates a structure of a forward link receiver for a data traffic channel according to an embodiment of the present invention; FIG. 8 illustrates a structure of a forward link receiver for a data traffic MAC channel according to an embodiment of the present invention; FIG. 9 illustrates a structure of a forward link receiver for a common power control channel (CPCCH) according to an embodiment of the present invention; FIG. 10 illustrates a relationship between a carrier-to-interference ratio (CIR) of a packet channel and distribution of orthogonal codes to a voice user and a packet user in a mobile communication system to which the present invention is applied; FIG. 11 illustrates a structure of a forward link transmitter for a data traffic channel having a data rate control function according to an embodiment of the present invention; FIG. 12 illustrates a slot structure used when a forward link transmitter transmits a packet at a data rate of 614.4kbps according to an embodiment of the present invention; FIG. 13 illustrates a slot structure used when a forward link transmitter transmits a packet at a data rate of 307.2kbps according to an embodiment of the present invention; FIG. 14 illustrates a structure of a forward link for a data traffic channel having a data rate control function according to an embodiment of the present invention; FIG. 15 illustrates a channel structure for transmitting DRC information and sector indicator information by a reverse link transmitter according to an embodiment of the present invention; FIG. 16 illustrates a structure of a scheme for performing a data rate control operation according to an embodiment of the present invention; FIG. 17 illustrates operation timing among a forward Walsh indication channel, a forward pilot channel, a forward packet data channel and a reverse DRC channel during a data rate control operation according to an embodiment of the present invention; FIG. 18 is a flow chart illustrating a data rate determining operation by a mobile station according to an embodiment of the present invention; FIG. 19 is a flow chart illustrating a data rate deteraiining operation by a base station according to an embodiment of the present invention; FIG. 20 is a flow chart illustrating an effective data rate detenriining operation by a mobile station according to an embodiment of the present invention; and FIG. 21 is a flow chart illustrating an effective data rate detenriining operation by a base station according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described herein below with reference to the accompanying drawings. In the following description, well-known functions or constructions are not described in detail since they would obscure the invention in unnecessary detail. The present invention relates to a forward link of a mobile communication system capable of supporting a multimedia service including a voice service and a data service using a Ix bandwidth. A transmitter, channels and a receiver for supporting the voice service are identical in structure to a transmitter, channels and a receiver of the existing Ix system. Here, the "Ix bandwidth" refers to a 1.25MHz frequency bandwidth used in an existing IS-95 synchronous system, and the "Ix system" refers to a system supporting the Ix bandwidth. The data service can be classified into a circuit mode operation and a packet mode operation according to its circuit connection type. The data service includes various video services such as a video conference service, and an Internet service. The data service operating in the circuit mode uses the intact structure of the transmitter, channels, and receiver of the existing Ix system. Thus, reference will be made to the structure of the transmitter, channels and receiver for the packet data service. Table 1 illustrates the channels required for the forward link packet data service in the mobile communication system according to an embodiment of the present invention. (Table Removed) Referring to Table 1, the channels for the forward link packet data service according to an embodiment of the present invention are classified into a data traffic channel and a data traffic MAC (Medium Access Control) channel. The data traffic channel is comprised of a pilot channel, a preamble subchannel and a data traffic subchannel. The data traffic MAC channel is comprised of a QoS (Quality of Service) matching indication channel, a Walsh space indication subchannel and a reverse activity indication subchannel. The pilot channel is multiplexed with the preamble subchannel and the data traffic subchannel before transmission. A pilot symbol provided over the pilot channel is utilized as an amplitude reference value for sync demodulation and can also be utilized as an auxiliary means of increasing accuracy of CIR measurement for data rate control. The preamble channel is multiplexed with the pilot channel and the data traffic subchannel before transmission, and is used to designate a mobile station (MS) corresponding to the data packet transmitted by a base station (BS). The data traffic subchannel is multiplexed with the pilot channel and the preamble subchannel to actually transmit a payload. The QoS matching indication channel uses a QoS matching technique to guarantee different QoS for respective data services, and is used to transmit QoS matching-related information. The QoS matching indication channel becomes an I-channel component of the data traffic MAC channel. The Walsh space indication subchannel is used to transmit Walsh space information of the base station, which can be allocated to the data traffic subchannel through dynamic Walsh allocation. The Walsh space indication subchannel is multiplexed with the reverse activity indication subchannel to become a Q-channel component of the data traffic MAC channel. The reverse activity indication subchannel is a broadcast channel for controlling a traffic load of a reverse link, and is multiplexed with the Walsh space indication subchannel to become the Q-channel component of the data traffic MAC channel. In addition to the channels Listed in Table 1, a channel for the forward link packet data service according to the embodiment of the present invention includes a common power control channel (CPCCH) for controlling transmission power of a physical channel for the data service operating in the circuit mode in the reverse link. FIG. 1A illustrates a structure of a forward link data traffic channel for a packet data service according to an embodiment of the present invention, and FIG. IB illustrates a structure of a forward link data traffic MAC channel for a packet data service according to an embodiment of the present invention. Referring to FIGs. 1A and IB, a minimum transmission unit of a physical channel for the packet data service is a 1,536-chip slot having a 1.25msec duration. Referring to FIG. 1A, one slot of the data traffic channel (DTCH) is divided into two half slots, each comprised of 768 chips. A leading 128-chip period of each half slot is allocated to the pilot channel (PICH) for inserting a pilot symbol. In each half slot, the remaining 640 chips, except for the part allocated to the PICH, are allocated to the data traffic subchannel (DTSCH) for a payload. hi the case of an idle slot where no payload exists, the DTSCH is gated-off thereby to reduce interference to a service connected in the circuit mode and a signal from an adjacent base station. Referring to FIG. IB, the data traffic MAC channel (DTMACCH) is comprised of a first channel (in-phase (I) channel) and a second channel (quadrature-phase (Q) channel). The first channel is used as the QoS (Quality of Service) matching indication channel (QMICH), while the second channel is used as the Walsh space indication subchannel (WSISCH) and the reverse activity indication subchannel (RAISCH). In each slot, the WSISCH and the RAISCH have a 1,280-chip period and a 256-chip period, respectively. The WSISCH and the RAISCH are multiplexed to each other, thus becoming the second channel of the DTMACCH. Meanwhile, the preamble subchannel (PSCH) not shown in FIGs. 1A and IB is multiplexed with the PICH and the DTSCH, and then transmitted over the DTCH. Since the PSCH is used to designate a mobile station corresponding to a data packet transmitted by a base station, it should exist in a leading part of a first slot of the DTCH for transmitting a physical layer packet. A preamble symbol may have a value of '0'. FIG. 2 illustrates a structure of a forward link transmitter for a data traffic channel according to an embodiment of the present invention. The forward link data traffic channel transmitter transmits a preamble subchannel (PSCH) signal, a data traffic subchannel (DTSCH) signal and a pilot channel (PICH) signal by time division multiplexing (TDM). Referring to FIG. 2, an input preamble symbol having a value '0' is mapped to a value '+1' by a signal point mapper 201. The output symbol of the signal point mapper 201 is spread with a specific 64-ary biorthogonal Walsh code (or sequence) corresponding to a unique user MAC ID (Identification, or index) by a Walsh spreader 202. The Walsh spreader 202 outputs a first-channel (I-channel) sequence and a second-channel (Q-channel) sequence. The output sequences of the Walsh spreader 202 are subject to sequence repetition according to a data rate (or transmission rate) in a sequence repeater 203. The sequence repeater 203 can repeat the output sequences of the Walsh spreader 202 as many as a maximum of 16 times according to the data rate. Therefore, the PSCH included in one slot of the DTCH can last (continue) for anywhere in the range from 64 chips up to a maximum of 1,024 chips according to the data rate. The I and Q sequences output from the sequence repeater 203 are provided to a time division multiplexer (TDM) 230 where they are multiplexed with PICH and DTSCH. A scrambler 211 scrambles a channel-coded bit sequence, and the output sequence of the scrambler 211 is interleaved by a channel interleaver 212. The size of the channel interleaver 212 depends on the size of the physical layer packet. The output sequence of the channel interleaver 212 is mapped to M-ary symbols by an M-ary symbol modulator 213. The M-ary symbol modulator 213 serves as a QPSK (Quadrature Phase Shift Modulation) modulator, a 8-PSK (8-ary Phase Shift Keying) or a 16-QAM (16-ary Quadrature Amplitude Modulation) modulator according to the data rate, and the modulation mode may be changed in a unit of a physical layer packet having a variable data rate. The I and Q sequences of the M-ary symbols output from the M-ary symbol modulator 213 are subject to sequence repetition/symbol puncturing according to the data WE CLAIM:- 1. A method for determining a data rate for a packet data service in a mobile station for a mobile communication system comprising a base station, the mobile station being provided with a voice service and a packet data service from the base station, comprising the steps of: measuring a carrier-to-interference ratio (CIR) using a received pilot channel; wherein receiving orthogonal code allocation information indicating a number of orthogonal codes allocated for the packet data service; determining a data rate corresponding to the measured CIR; and controlling the determined data rate based on the number of the allocated orthogonal codes. 2. The method as claimed in claim 1, wherein the determined data rate is decreased when the number of the allocated orthogonal codes is less than the number of all orthogonal codes. 3. The method as claimed in claim 2, comprising the step of calculating a sequence repetition number determined by a ratio of the number of data modulation symbols per packet to the number of available data modulation symbols based on the number of the allocated orthogonal codes, wherein the determined data rate is controlled according to the calculated sequence repetition number. 4. The method as claimed in claim 3, wherein the determined data rate is decreased by determining to increase the number of slots for transmitting one packet according to the calculated sequence repetition number. 5. The method as claimed in claim 3, wherein the determined data rate is decreased by determining to decrease the number of symbols in a transmission packet according to the calculated sequence repetition number. 6. The method as claimed in claim 4 and 5, wherein the determined data rate is decreased when the calculated sequence repetition number is less than a predetermined value. 7. The method as claimed in claim 1, wherein the orthogonal code allocation information is received from the base station in a predetermined time unit. 8. The method as claimed in claim 8, wherein the predetermined time unit is a frame unit. 9. The method as claimed in claim 1, comprising the step of transmitting information on the controlled data rate to the base station. 10. The method as claimed in claim 1, comprising the step of setting demodulation parameters according to the controlled data rate. 11. The method as claimed in claim 10, wherein the demodulation parameters comprising (i) a sequence repetition number determined by a ratio of the number of data modulation symbols per packet to the number of available data modulation symbol, (ii) the number of slots for transmitting one packet, and (iii) the number of symbols in a transmission packet. 12. An apparatus for use in a mobile communication system having a mobile station for determining a data rate for a packet data service in a mobile communication system comprising a base station, the mobile station being provided with a voice service and a packet data service from the base station using a method as claimed in claim 1 to 11, comprising: a measurer capable of measuring a CIR using a received pilot channel; wherein a receiver capable of receiving orthogonal code allocation information indicating the number of orthogonal codes allocated for the packet data service; and a controller capable of determining a data rate corresponding to the measured CIR, control the determined data rate based on the number of the allocated orthogonal codes, and determine a controlled data rate. 13. An apparatus for use in a mobile communication system having a mobile station as claimed in claim 12, wherein the controller is capable of decreasing the determined data rate when the number of the allocated orthogonal codes is less than the number of orthogonal codes corresponding to the determined data rate. 14. An apparatus for use in a mobile communication system having a mobile station as claimed in claim 13, wherein the controller is capable of calculating a sequence repetition number determined by a ratio of the number of data modulation symbols per packet to the number of available data modulation symbols based on the number of the allocated orthogonal codes, and controls the determined data rate according to the calculated sequence repetition number. 15. An apparatus for use in a mobile communication system having a mobile station as claimed in claim 14, wherein the controller is capable of decreasing the determined data rate by determining to increase the number of slots for transmitting one packet according to the calculated sequence repetition number. 1S. An apparatus for use in a mobile communication system having a mobile station as claimed in claim 14, wherein the controller is capable of decreasing the determined data rate by determining to decrease the number of symbols in a transmission packet according to the calculated sequence repetition number. 17. An apparatus for use in a mobile communication system having a mobile station as claimed in claim 15 and 16, wherein the controller is capable of decreasing the determined data rate when the calculated sequence repetition number is less than a predetermined value. 18. An apparatus for use in a mobile communication system having a mobile station as claimed in claim 12, wherein the orthogonal code allocation information is received from the base station in a predetermined time unit. 19. An apparatus for use in a mobile communication system having a mobile station as claimed in claim 19, wherein the predetermined time unit is a frame unit. 20. An apparatus for use in a mobile communication system having a mobile station as claimed in claim 12, comprising a transmitter is capable of transmitting information on the controlled data rate to the base station.

Documents:

in-pct-2002-565-del-abstract.pdf

in-pct-2002-565-del-assignment.pdf

in-pct-2002-565-del-claims.pdf

in-pct-2002-565-del-correspondence-others.pdf

in-pct-2002-565-del-correspondence-po.pdf

in-pct-2002-565-del-description (complete).pdf

in-pct-2002-565-del-drawings.pdf

in-pct-2002-565-del-form-1.pdf

in-pct-2002-565-del-form-19.pdf

in-pct-2002-565-del-form-2.pdf

in-pct-2002-565-del-form-3.pdf

in-pct-2002-565-del-form-5.pdf

in-pct-2002-565-del-gpa.pdf

in-pct-2002-565-del-pct-101.pdf

in-pct-2002-565-del-pct-210.pdf

in-pct-2002-565-del-pct-308.pdf

in-pct-2002-565-del-petition-138.pdf