JP2006121244A - Mobile communication system and method, and mobile station and base station for use therein - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a wireless communication system in which wireless resource can be used efficiently when retransmission is requested. <P>SOLUTION: A transmission state can be estimated with higher precision by correcting the value of CQI(line propagation quality) (A-6) being informed to a base station on the basis of the number of Iteration times (A-5), i.e. the number of repetition times being obtained at the time of turbo decoding information obtained at a mobile station. At the base station, number of retransmission times can be reduced by setting RV (redundant version) parameters suitable for the transmission state on the basis of the number of Iteration times (A-8) and thereby wireless resource can be used efficiently. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a mobile communication system, a communication method, and a mobile station and a base station used therefor, and more particularly, a packet using a hybrid automatic repeat request (HARQ) in HSDPA (High-Speed Downlink Packet Access) in the mobile communication system. It relates to communication methods.

  In 3GPP (3rd Generation Partnership Project), which is a standardization project for W-CDMA (Wideband-Code Division Multiple Access) wireless communication systems, “HSDPA (High speed downlink packet access)”, which is a downlink high-speed packet transmission method, is standardized. ing. As one of important functions for improving the communication performance of HSDPA, Non-Patent Document 1 discloses a transmission method called AMC (Adaptive Modulation and Coding). This AMC technique is a technique for adaptively changing the coding rate and modulation method in error correction according to fluctuations in channel quality.

  In this AMC technique, when the line quality is good, the transmission rate is increased by using an encoding / modulation method that provides a high rate. When the channel quality is not good, the transmission rate is lowered by using an encoding / modulation method which is a low rate so that the packet is reliably transmitted. Specifically, the mobile station measures the downlink propagation quality from time to time using the CPICH (Common Pilot Channel), and the base station determines the optimum mobile station to transmit information based on the measurement result. Information is transmitted by determining the transmission rate.

  Related to the transmission rate are modulation schemes such as QPSK (Quaternary Phase Shift Keying), 16QAM (Quaternary Amplitude Modulation), coding rate (Turbo coding at 1/3, puncture or repeat). There is a method of changing the coding rate by repetition.

  ARQ (Automatic Repeat reQuest) is a packet in which an error detection code is added to an information signal sequence at a base station (transmitting side), and an error is detected in a received packet at a mobile station (receiving side). In this case, a retransmission request for the packet is made to the base station. In the base station, the retransmission request packet is transmitted again and repeated until no error is detected in the mobile station. As a result, error-free transmission can be realized and used together with AMC.

  Further, in the ARQ, in order to improve that the retransmission request is frequently generated and the characteristic is greatly deteriorated when the propagation quality is poor, in addition to the error detection code, an error correction code such as turbo coding is used. HARQ (Hybrid ARQ) that reduces occurrence has been proposed. HARQ and AMC techniques are also controlled by redundant version (RV) parameters. Redundant version (RV) parameters r, s and constellation version parameter b are encoded together to produce the value Xrv. FIG. 11 shows redundant version (RV) coding for 16QAM, and FIG. 12 shows RV coding for QPSK. The base station changes the RV parameter according to the number of packet retransmissions. Details of the redundant version parameter are disclosed in Patent Document 1.

  As described in Non-Patent Document 1 described above, the parameters of the second rate matching stage depend on the values of s and r of the RV parameter. The parameter s can take the value 0 or 1 to distinguish between self-decodable (s = 1) transmissions and non-self-decodable (s = 0) transmissions. The parameter r has a range from 0 to rmax, and changes the initial error variable eini in the case of puncturing. In the case of repetition processing, both parameters r and s change the initial error variable eini.

  In particular, the parameter s determines whether system bits or parity bits are punctured in the second rate matching stage. If s = 1, the parity 1 and parity 2 bits are tried to be punctured, but the system bits are not. Therefore, in the initial transmission, the RV parameter S = 1 should be used.

  This RV parameter is selected according to a predetermined table according to the number of retransmissions. Referring to the table of FIG. 11 as an example, the RV parameter Xrv is 0 (s = 1, r = 0, b = 0) at the first transmission, and Xrv = 1 (s = 0, r = 0, b = 0), and in the second retransmission, Xrv = 2 (s = 1, r = 1, b = 1)... and the RV parameter is selected according to the number of retransmissions.

  Hereinafter, the related art will be described in detail with reference to FIGS. 11, 13, and 14. FIG. 13 is a diagram showing an example of a radio channel between a mobile station and a base station. As shown in FIG. 13, between the mobile station 100 and the base station 101, both uplink and downlink lines (Uplik & Downlink) is set to DPCH (Dedicated Physical Channel). CPICH is a pilot signal transmitted from base station 101 with a predetermined power, and is used by mobile station 100 for measurement of downlink (DL) reception quality and the like.

  HS-PDSCH is a shared channel for packet transmission of user data, and is used in a time multiplexed manner between a plurality of mobile stations. HS-SCCH is a shared channel for transmitting control data necessary for receiving packets transmitted on HS-PDSCH, and each mobile station uses HS-SCCH control information to transmit HS-PDSCH packets. Receive.

  The HS-DPCCH is an individual channel that transmits CQI (Channel Quality Indication: downlink quality information) determined from the quality measurement result of CPICH and ACK / NACK (Acknowledgement / Negative Acknowledgement) as notification confirmation information of the received packet.

  FIG. 14 simply shows the flow of data transmission and reception in FIG. 13 as an operation sequence diagram. In the base station, a transmission procedure 200 is performed. The transmission procedure 200 includes three procedures: turbo coding 201, RV selection 202, and rate matching 203. First, turbo coding 201 is performed on data (packets) to be transmitted. This is because even if an error is added on the transmission path, data is transmitted without error by performing error correction at the mobile station.

  In the turbo coding / decoding method, information bits (system bits) which are transmission data strings are encoded to generate two parity bits (first parity bit and second parity bit) used in error correction processing, and information bits (system Bit) and these two parity bits are transmitted. The mobile station reproduces transmission data from information bits (system bits) while performing error correction processing using the received two parity bits.

  These first parity bit and second parity bit are reliability information of information bits (system bits) generated by the turbo coding process on the transmission side, and when performing decoding processing at the mobile station, these parity bits are By using it, it has a function of improving the reproduction accuracy of information bits (system bits).

  Next, RV selection (202) is performed. At the time of initial transmission, transmission capable of self-decoding (s = 1) is selected as RV selection. Next, the transmission bits are repeated or punctured to match the frame size of the HS-PDSCH by rate matching (203). Since s = 1 at the first transmission, rate matching is performed so that parity bits are punctured rather than system bits. The frame size of the HS-PDSCH is calculated using the CQI notified to the base station by the mobile station measuring the CPICH reception quality, but is omitted in FIG.

  The mobile station receives the HS-PDSCH based on control data (including RV parameters) mapped to the HS-SCCH. The reception procedure 210 includes four procedures of rate dematching (211), symbol re-synchronization (212), turbo decoding (213), and error detection (214) at the time of retransmission.

  First, rate dematching (211) is performed to decompose the system bits and the parity bits. At this time, an intermediate value is given to the punctured bit. If the transmitted data is at the time of retransmission, symbol combination with the previously received data symbol is performed. Thereafter, turbo decoding (213) is performed to correct the error, and CRC determination (214) is performed to determine whether or not there is an error in the transmitted data.

  If it is determined that there is no error in the CRC determination, it can be said that the data to be transmitted has been correctly received, and the reception procedure is terminated. If it is determined that there is an error in the CRC determination, NACK that is a retransmission request is mapped to HS-DPCCH. At this time, the received data that is erroneous in the CRC determination is not discarded, but is stored in a buffer for synthesis with the next retransmission data. However, data may be discarded when the reliability of the decryption result is low.

  Next, the base station that has received the retransmission request performs a retransmission procedure 204. The retransmission procedure 204 performs the same procedure as the transmission procedure 200. However, for RV selection, RV parameters corresponding to the number of retransmissions are selected. This RV parameter is selected according to a predetermined table according to the number of retransmissions.

  Referring to FIG. 11 as an example, the RV parameter Xrv is 0 (s = 1, r = 0, b = 0) at the first transmission, and Xrv = 1 (s = 0, r = 0, b) at the first retransmission. = 0), and in the second retransmission, Xrv = 2 (s = 1, r = 1, b = 1)... And the RV parameter is selected according to the number of retransmissions. Then, by rate matching, transmission bits are repeated or punctured so as to match the frame size of HS-PDSCH, and retransmission is performed.

  In the mobile station, the reception procedure 215 is performed. The reception procedure 215 performs the same procedure as the reception procedure 210. At this time, the original data is restored from the method of improving the received signal power to noise power ratio (SNR) by performing symbol synthesis with the previously received symbol data stored in the buffer in advance in step 212 or the puncture rule. However, the probability of decoding by turbo decoding is increased by a method for improving the coding rate.

  As retransmission data, the same packet is retransmitted and a received packet containing an error is combined for each symbol to improve SIR and improve reception characteristics. This method is called Chase Combining. A method of improving the reception characteristic by improving the coding gain by retransmitting the packet is called Incremental Redundancy.

  If it is determined that there is no error in the CRC determination by using this retransmission data, it can be said that the data to be transmitted has been correctly received, and the reception procedure is terminated. Even if this retransmission data is used, if it is determined that there is an error in the CRC determination, a retransmission request is reported to the base station again. Thereafter, retransmission is repeated until no error is detected in the mobile station. Thereby, error-free transmission can be realized.

  FIG. 15 shows a conventional apparatus configuration on the receiving side (mobile station). As shown in the figure, the mobile station (receiving side) receives the HS-PDSCH, and the rate dematching unit 500 restores the repeated or punctured bits to the original data by the rate matching function at the base station. The symbol data storage buffer unit 503 storing the symbol data received last time, the symbol data newly received from the symbol data storage buffer unit 503 and the symbol data newly received and restored by the rate dematching unit 500 A symbol data synthesis unit 501 having a function of synthesizing.

  Further, the mobile station decodes the data combined by the symbol data combining unit 501 by turbo decoding, which has a function of correcting an error inserted on the transmission path by turbo decoding, and the turbo decoding unit. CRC determination unit 504 that performs CRC determination based on the received data and determines whether or not the data has been correctly received without error. As a result of CRC determination unit 504, if there is no error, ACK is generated. If there is an error, ACK / NACK is generated. A generation unit 506.

  Furthermore, the mobile station receives CPICH and calculates a CPICH channel quality calculation unit 508 that calculates channel quality, and a CQI calculation unit 507 that generates CQI based on the channel quality calculated by the CPICH channel quality calculation unit 410. And an HS-DPCCH generation unit 505 having a function of mapping the ACK / NACK obtained from the ACK / NACK generation unit 506 and the CQI obtained from the CQI calculation unit 507 to the HS-DPCCH that is an uplink channel.

JP 2003-333668 A 3GPP TR25.848 & TR25.858

  In the measurement and estimation of the channel quality, if the error is large or the temporal variation of the channel quality is fast, the mobile station may not obtain the desired quality and it may be necessary to retransmit the data. In this case, the RV parameter at the time of retransmission is selected according to a predetermined table according to the number of retransmissions, and this selection method is not selected according to the current transmission path condition, so it is not optimal. If optimal RV selection is not performed, the number of retransmissions increases or transmission is performed using excessive resources, and radio resources are wasted. Further, since the line quality is measured by measuring the CPICH, there is a problem that the quality of the HS-PDSCH that is originally transmitted is different and an error occurs.

  The present invention has been made in view of the problems of the related art, and an object of the present invention is to provide a radio communication system and a communication method capable of efficiently using radio resources when there is a retransmission request, and to use the same. To provide a base station and a mobile station.

  A mobile communication system according to the present invention is a mobile communication system that determines a transmission method of transmission information of a channel according to the propagation quality of a downlink from a base station to the mobile station, wherein the mobile station Means for measuring propagation quality, means for turbo-decoding the transmission information, and means for correcting the propagation quality in accordance with the number of repetitions of turbo decoding and notifying the base station.

  A communication method according to the present invention is a communication method in a mobile communication system in which a transmission method of transmission information of a channel is determined according to the propagation quality of the downlink from the base station to the mobile station, And means for measuring the propagation quality, turbo decoding the transmission information, and correcting the propagation quality according to the number of repetitions of the turbo decoding and notifying the base station. To do.

  A mobile station according to the present invention is a mobile station in a mobile communication system that determines a transmission method of transmission information of a channel according to the propagation quality of the downlink from the base station, and means for measuring the propagation quality And means for turbo-decoding the transmission information and means for correcting the propagation quality according to the number of repetitions of turbo decoding and notifying the base station.

  The base station according to the present invention is a base station that determines a transmission method of transmission information of the channel according to the propagation quality of the downlink measured at the mobile station, and the propagation quality is determined at the mobile station. The transmission information is turbo decoded and corrected according to the number of repetitions of the turbo decoding, and includes transmission method determining means for determining the transmission method according to the propagation quality notified from the mobile station. It is characterized by.

  The program according to the present invention is a program for causing a computer to execute an operation of a mobile station in a mobile communication system in which a transmission method of transmission information of the channel is determined according to the propagation quality of the downlink from the base station. A process of measuring the propagation quality, a process of turbo decoding the transmission information, and a process of correcting the propagation quality according to the number of repetitions of the turbo decoding and notifying the base station. And

  Another program according to the present invention is a program for causing a computer to execute an operation of a base station that determines a transmission method of transmission information of a relevant line according to the downlink propagation quality measured in the mobile station. The propagation quality is obtained by turbo decoding the transmission information in the mobile station and correcting the transmission information according to the number of repetitions of the turbo decoding. The transmission quality is determined according to the propagation quality notified from the mobile station. It includes processing for determining a method.

  The operation of the present invention will be described. RV parameters for data retransmission are not selected according to a predetermined table according to the number of retransmissions, but the number of repetitions (also referred to as the number of iterations) when performing turbo decoding in the mobile station is fed back. Information is mapped to the HS-PDCCH and transmitted to the base station, and the base station selects the RV parameter together with the iteration count and ACK / NACK information, which are the return counts. Further, by adding an offset value calculated from the number of iterations at the time of HS-PDSCH decoding to the CQI to the channel quality measured by CPICH, it is possible to estimate the channel quality with higher accuracy.

  According to the present invention, it is possible to estimate the transmission state with higher accuracy by correcting the value of CQI notified to the base station based on the iteration count that is the iteration count obtained at the time of turbo decoding obtained by the mobile station. There is an effect that can be performed. Also, in the base station, by setting the RV parameter suitable for the transmission state based on the number of iterations, there is an effect that it is possible to reduce the number of retransmissions. There is also an effect that it can be used.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The configuration of the radio base station apparatus in the embodiment of the present invention will be described. Note that the system configuration of FIG. 13 described above is equivalent to that of the mobile communication system in the present invention. Here, referring to FIG. 13 again, DPCH (Downlink) / (Uplink) is set between the mobile station 100 and the base station 101. CPICH is a pilot signal transmitted with a predetermined power from the base station 101, and is used by the mobile station 100 to measure DL (Downlink) reception quality.

  HS-PDSCH is a shared channel for packet transmission of user data, and is used in a time multiplexed manner between a plurality of mobile stations. HS-SCCH is a shared channel for transmitting control data necessary for receiving packets transmitted on HS-PDSCH, and each mobile station uses HS-SCCH control information to transmit HS-PDSCH packets. Receive.

  The HS-DPCCH is an individual channel that transmits CQI (Channel Quality Indication: downlink quality information) determined from the quality measurement result of CPICH and ACK / NACK (Acknowledgement / Negative Acknowledgements) as notification information of received packets.

  FIG. 1 is a block diagram of a base station in the mobile communication system as shown in FIG. 13, and FIG. 2 is a block diagram of the mobile station. The base station (transmission side) in FIG. 1 repeats the Turbo encoding unit 300 that turbo-encodes transmission data, and the data encoded by this Turbo encoding unit so as to match the frame size of the HS-DPSCH. A rate matching unit 302 having a function of puncturing, an RV selection unit 301 for calculating an RV parameter for selecting a bit to be repeated and punctured by the rate matching unit 302, HS-DPCCH, and receiving CQI, ACK / NACK, An HS-DPCCH reception unit 303 that decodes and separates the number of iterations and inputs the number of iterations to the RV selection unit 301.

  The mobile station (reception side) in FIG. 2 receives the HS-PDSCH, and the rate dematching unit 400 that restores the original data to the bits repeated or punctured by the rate matching function at the base station, and the previous received A symbol data storage buffer unit 404 that stores symbol data, and a function that newly receives the symbol data received from the symbol data storage buffer unit 404 and the symbol data newly received and restored by the rate dematching unit 400 And a symbol data synthesis unit 401.

  In addition, the mobile station performs turbo decoding on the data combined by the symbol data combining unit 401, thereby correcting an error inserted on the transmission path, a turbo decoding unit 402, and a turbo decoding unit ( The iteration number determination unit 403 having a function of counting the number of iterations, which is the number of iterations performed in step 402), and CRC determination based on the data decoded by the turbo decoding unit, and whether or not the reception was correctly performed is determined. As a result of the CRC determination unit 405, there is an ACK if there is no error, and an ACK / NACK generation unit 407 that generates NACK if there is an error.

  Furthermore, the mobile station receives CPICH, and calculates a CPICH channel quality calculation unit 410 that calculates channel quality, and a CQI calculation unit 409 that generates CQI based on the channel quality calculated by the CPICH channel quality calculation unit 410. , CQI offset unit 408 having a function of adding an offset obtained from the number of iterations performed during turbo decoding of HS-PDSCH to a CQI value obtained from CQI calculation unit 409, and ACK obtained from ACK / NACK generation unit 407 A HS-DPCCH generation unit 406 having a function of mapping the number of iterations obtained from the CQI and iteration number determination unit 403 obtained from the / NACK and CQI offset unit 408 to the HS-DPCCH that is an uplink channel.

  The operation of the present embodiment will be described using the flowcharts of FIGS. FIG. 3 is a flowchart when the CRC determination result is OK and the number of iterations is small. FIG. 4 is a flowchart when the CRC determination result is OK and the number of iterations is large. FIG. 5 is a flowchart when the CRC determination result is NG and the number of iterations is small. FIG. 6 is a flowchart when the CRC determination result is NG and the number of iterations is large.

  First, the operation when the CRC determination result is OK and the number of iterations is small will be described with reference to FIG. The base station transmits new data (packet) (A-3). The mobile station receives the packet (A-4) and performs turbo decoding. Further, the number of iterations performed by turbo decoding is counted. In turbo decoding, to determine the number of iterations, the iterations may be stopped when the SIR is sufficiently obtained, or stopped when there is no change in the hard decision result compared to the previous iteration. Also good. In any case, the iteration may be stopped in a state where no effect can be obtained even if further iterations are performed.

  Then, it is determined whether an error is inserted using CRC. In this case, if it is OK, there is no error in the CRC, and the data can be correctly received (A-5). Since the CRC result is OK (no error), the ACK signal is mapped to the HS-DPCCH. Further, an offset that increases the CQI value is added to the CQI value calculated from CPICH (A-6).

  Furthermore, the number of iterations obtained in A-5 is also mapped to the HS-DPCCH. The mapping method of the iteration count information to the HS-DPCCH will be omitted here in order to add a detailed description later. Next, the base station receives the HS-DPCCH (A-7). That is, information such as the ACK signal mapped to the HS-DPCCH, the CQI value offset-added in the direction of increasing the CQI value, and the number of iterations (the number of iterations) is received. Since the ACK signal is received, the data transmitted from the transmission buffer is deleted and new data is transmitted (A-8). At this time, since the S bit, which is one of the RV parameters, is an initial transmission, transmission capable of self-decoding (s = 1) is selected.

  Next, an operation when the CRC determination result is OK and the number of iterations is large will be described with reference to FIG. Information such as the ACK signal mapped to the HS-DPCCH, the CQI value offset-added in the direction of increasing the CQI value, and the number of iterations (the number of times is small) is received. Since the ACK signal is received, the transmitted data is deleted from the transmission buffer, and new data is transmitted (A-8).

  The base station transmits new data (packet) (B-3). The mobile station receives the packet (B-4) and performs turbo decoding. Further, the number of iterations performed by turbo decoding is counted. Then, it is determined whether an error is inserted using CRC. In this case, if it is OK, there is no error in the CRC, indicating that data can be received correctly (B-5). Since the CRC result is OK (no error), the ACK signal is mapped to the HS-DPCCH. In addition, although the CRC result was OK, a large number of iterations were required, so an offset that lowers the CQI value is added to the CQI value calculated from CPICH (B-6)

  Although the CRC result is OK, the fact that a large number of iterations are required means that the delay time for turbo decoding in the mobile station increases. Also, depending on the CQI value obtained from CPICH, if data selected from a CQI higher than the data received this time at the base station is transmitted, there is a high possibility that the data cannot be completely decoded by turbo decoding. Therefore, the throughput is improved by adding an offset for lowering the CQI value. The number of iterations obtained in B-5 is also mapped to the HS-DPCCH. The method for mapping this iteration count information to the HS-DPCCH will be omitted here in order to be described in detail later.

  Next, the base station receives the HS-DPCCH (B-7). Information such as the ACK signal mapped to the HS-DPCCH, the CQI value offset-added in the direction of decreasing the CQI value, and the number of iterations (the number of iterations) is received. Since the ACK signal is received, the transmitted data is deleted from the transmission buffer, and new data is transmitted (B-8). At this time, since the S bit, which is one of the RV parameters, is an initial transmission, transmission capable of self-decoding (s = 1) is selected. In addition, since an offset is added in the direction in which the CQI value is lowered, it is desirable to select transmission data having a data size smaller than that of the previous transmission data or a larger transmission power.

  Next, the operation when the CRC determination result is NG and the number of iterations is small will be described with reference to FIG. The base station transmits new data (packet) (C-3). The mobile station receives the packet (C-4) and performs turbo decoding. Further, the number of iterations performed by turbo decoding is counted. Then, it is determined whether an error is inserted using CRC. In this case, if it is NG, an error has occurred in the CRC, indicating that data has not been correctly received (C-5).

  Since the CRC result is NG (with an error), a NACK signal is mapped to the HS-DPCCH. Also, since the CRC result is NG, an offset that lowers the CQI value is added to the CQI value calculated from CPICH (C-6). Then, the number of iterations obtained in C-5 is also mapped to the HS-DPCCH. A method for mapping the iteration count information to the HS-DPCCH will be described in detail later, and is omitted here.

  Next, the base station receives the HS-DPCCH (C-7). Information such as the NACK signal mapped to the HS-DPCCH, the CQI value offset-added in the direction of decreasing the CQI value, and the number of iterations (the number of iterations) is received. Since the NACK signal is received, retransmission data is transmitted from the transmission buffer (C-8).

  At this time, it is desirable to select transmission capable of self-decoding (s = 1) for the S bit which is one of the RV parameters. This is because, although the CRC is NG (with an error), the Turbo decoding is stopped without performing many iterations, and in such a case, the system bit is reliable for the wrong value. Since the degree is high, it cannot be corrected with the parity bit. At this time, it is preferable to adopt a puncturing method (s = 1) that places importance on system bits as retransmission data, and to perform packet combining for improving the received signal power to noise power ratio (SNR).

  Further, in the case of such a pattern in the mobile station (CRC is OK but the number of iterations is small), the reception buffer may be discarded and turbo decoding may be performed based only on retransmission data with s = 1. Then, the mobile station receives retransmission data (C-9). After packet synthesis, CRC is OK (no error) by performing turbo decoding (C-10). Since the CRC is OK (no error), the HS-DPCCH to which the ACK information is mapped is transmitted (mapped to the HS-DPCCH together with the CQI and the number of iterations).

  Next, the base station receives the HS-DPCCH (C-11). An ACK signal mapped to this HS-DPCCH is received. Since the ACK signal is received, the transmitted data is deleted from the transmission buffer, and new data is transmitted (C-12). At this time, since the S bit, which is one of the RV parameters, is an initial transmission, transmission capable of self-decoding (s = 1) is selected. In this example, the case where the number of retransmissions is one and the CRC is OK (no error) has been described, but error-free can be realized by repeating retransmission until the CRC becomes OK.

  Next, the operation when the CRC determination result is NG and the number of iterations is large will be described with reference to FIG. The base station transmits new data (packet) (D-3). The mobile station receives the packet (D-4) and performs turbo decoding. Further, the number of iterations performed by turbo decoding is counted. Then, it is determined whether an error is inserted using CRC. In this case, an error has occurred in the CRC, indicating that data cannot be received correctly (D-5).

  Since the CRC result is NG (with an error), a NACK signal is mapped to the HS-DPCCH. Also, since the CRC result is NG, an offset that lowers the CQI value is added to the CQI value calculated from CPICH (D-6). The number of iterations obtained in D-5 is also mapped to the HS-DPCCH. A method for mapping the iteration count information to the HS-DPCCH will be omitted here in order to be described in detail later.

  Next, the base station receives the HS-DPCCH (D-7). Information such as the NACK signal mapped to the HS-DPCCH, the CQI value offset-added in the direction of decreasing the CQI value, and the number of iterations (the number of iterations) is received. Since the NACK signal is received, retransmission data is transmitted from the transmission buffer (D-8). At this time, it is desirable to select transmission in which the S bit, which is one of the RV parameters, is not self-decoding (s = 0).

  This is because CRC is NG (with error) and CRC is NG even though turbo decoding has performed many iterations. In such a case, the decoded system bits Can be corrected by increasing the number of parity bits in the retransmission data and increasing the coding rate. At this time, the reception characteristic is improved by adopting a puncturing method (s = 0) that places importance on the parity bit as retransmission data and improving the coding gain by retransmitting different redundant bits as retransmission data. Then, the mobile station receives retransmission data (D-9).

  By performing turbo decoding after packet synthesis, the CRC becomes OK (no error) (D-10). Since the CRC is OK (no error), the HS-DPCCH to which the ACK information is mapped is transmitted (mapped to the HS-DPCCH together with the CQI and the number of iterations).

  Next, the base station receives the HS-DPCCH (D-11). An ACK signal mapped to this HS-DPCCH is received. Since the ACK signal is received, the transmitted data is deleted from the transmission buffer, and new data is transmitted (D-12). At this time, since the S bit, which is one of the RV parameters, is an initial transmission, transmission capable of self-decoding (s = 1) is selected. In this example, the case where the CRC is OK (no error) after one retransmission is described, but error-free can be realized by repeating the retransmission until the CRC becomes OK.

  As described above, the four patterns have been described. The respective trends are shown in FIGS. In addition, since the four patterns described above are examples, they also vary depending on turbo reception characteristics and CPICH quality estimation characteristics at the mobile station. 7 and 8 also change depending on when the Iteration is stopped, so the drawings and descriptions shown here are merely examples.

  Next, a method for mapping the iteration count information to the HS-DPCCH will be described with reference to FIG. 9A is a format diagram of HS-DPCCH before mapping, and FIG. 9B is a format diagram of HS-DPCCH after mapping. Generally, since the maximum number of iterations is 8, the example of the case where the range of iterations is 1 to 8 is shown in FIG. In this case, as the number of iterations, it is only necessary to take 8 values, so 3 bits are required.

  On the other hand, as shown in FIG. 10, HS-DPCCH has a 20-bit configuration in which ACK / NACK information is repeated 10 times and 10-bit and 5-bit CQI information is (20, 5) encoded. It should be noted that 5 bits of (20.5) encoded CQI information always have the same value (0, 1). The (20, 5) encoding is calculated as shown in the following Equation 1 by the linearity of the five base vectors of length 20 shown in FIG.

ここに、ａn はＣＱＩ情報ビットであり、ｂi が（２０，５）符号化の出力ビットとなる。図１０でのｉが１６〜１９まで基底ベクトルはそれぞれ同じ値となっている。そのため、ここで（２０，５）符号化されたＣＱＩ情報のうち、５ヒット分については、必ず同じ値（０，１）となる。よって、ＨＳ−ＤＰＣＣＨにマッピングされている（２０，５）符号化されたＣＱＩのうち、４ビット分まで省略することが可能である。

Here, an is a CQI information bit, and bi is an output bit of (20, 5) encoding. In FIG. 10, the basis vectors have the same values from i to 16-19. Therefore, of the CQI information encoded here (20, 5), the same value (0, 1) is always obtained for 5 hits. Therefore, it is possible to omit up to 4 bits in the (20, 5) coded CQI mapped to the HS-DPCCH.

  Then, it is possible to map information on the number of iterations to the omitted part. In this example, since 3 bits are required as the number of iterations, mapping can be performed as shown in FIG.

  Of course, the operation of the base station and mobile station in the above-described embodiment can be configured such that the operation procedure is recorded in advance on a recording medium such as a ROM and is read by a computer and executed.

It is a figure which shows the example of the base station in embodiment of this invention. It is a figure which shows the example of the mobile station in embodiment of this invention. It is a figure which shows the operation example 1 (example in case a CRC determination result is OK and the number of iterations is few) of embodiment of this invention. It is a figure which shows the operation example 2 (example in case a CRC determination result is OK and there are many iterations) of embodiment of this invention. It is a figure which shows the operation example 3 (example in case a CRC determination result is NG and there are few iterations) of embodiment of this invention. It is a figure which shows the operation example 4 (example in case a CRC determination result is NG and there are many iterations) of embodiment of this invention. It is a figure explaining an example of the operation | movement tendency in embodiment of this invention. It is a figure explaining the other example of the operation | movement tendency in embodiment of this invention. It is a figure which shows the example of mapping of HS-DPCCH in embodiment of this invention. It is a figure explaining the base vector used for (20,5) encoding. It is a figure which shows the example of the RV encoding with respect to 16QAM. It is a figure which shows the example of the RV encoding with respect to QPSK. 1 is a schematic diagram of a wireless communication system. It is a figure which shows the example of a conventional operation | movement. It is a figure which shows the example of the conventional mobile station.

Explanation of symbols

DESCRIPTION OF SYMBOLS 300 Turbo encoding part 301 RV selection part 302 Rate matching part 303 HS-DPCCH receiving part 400 Rate dematching part 401 Symbol data synthetic | combination part 402 Turbo (turbo) decoding part 403 Iteration frequency | count determination part 404 Symbol data preservation | save buffer part 405 CRC determination Unit 406 HS-DPCCH generation unit 407 ACK / NACK generation unit 408 CQI offset unit 409 CQI calculation unit 410 CPICH channel quality calculation unit

Claims (15)

A mobile communication system configured to determine a transmission method of transmission information of a corresponding line according to propagation quality of a downlink from a base station to a mobile station,
The mobile station includes means for measuring the propagation quality, means for turbo decoding the transmission information, and means for correcting the propagation quality according to the number of repetitions of the turbo decoding and notifying the base station A mobile communication system.   The mobile communication system according to claim 1, wherein the base station includes a transmission scheme determining unit that determines the transmission scheme according to the notified propagation quality.   The mobile communication system according to claim 2, wherein the transmission method determining means sets a parameter value for determining the transmission method in accordance with the propagation quality. The mobile station further includes means for making a retransmission request to the base station when there is an error in the received transmission information,
4. The mobile communication system according to claim 3, wherein the transmission method determining means of the base station sets the value of the parameter at the time of retransmission of the transmission information based on the retransmission request. A communication method in a mobile communication system configured to determine a transmission method of transmission information of a line according to a propagation quality of a downlink from a base station to a mobile station,
The mobile station includes means for measuring the propagation quality, turbo decoding the transmission information, and correcting the propagation quality according to the number of repetitions of the turbo decoding and notifying the base station. A communication method characterized by the above.   The communication method according to claim 5, further comprising: a transmission method determination step for determining the transmission method in accordance with the notified propagation quality in the base station.   The communication method according to claim 6, wherein the transmission method determining step sets a parameter value for determining the transmission method according to the propagation quality. The mobile station further includes a step of making a retransmission request to the base station when there is an error in the received transmission information,
8. The communication method according to claim 7, wherein the base station transmission method determination step sets the parameter value at the time of retransmission of the transmission information based on the retransmission request.   A mobile station in a mobile communication system configured to determine a transmission method of transmission information of a channel according to a propagation quality of a downlink from a base station, the means for measuring the propagation quality, and the transmission information as a turbo A mobile station, comprising: means for decoding; and means for correcting the propagation quality according to the number of repetitions of the turbo decoding and notifying the base station.   10. The mobile station according to claim 9, further comprising means for making a retransmission request to the base station when there is an error in the received transmission information. A base station configured to determine a transmission method of transmission information of the corresponding line according to the propagation quality of the downlink measured in the mobile station,
The propagation quality is obtained by turbo decoding the transmission information in the mobile station and correcting the transmission information according to the number of repetitions of the turbo decoding.
A base station comprising transmission method determining means for determining the transmission method according to the propagation quality notified from the mobile station.   12. The base station according to claim 11, wherein the transmission method determining means sets a parameter value for determining the transmission method according to the propagation quality.   13. The base station according to claim 12, wherein the transmission scheme determining means sets the parameter value at the time of retransmission in response to a retransmission request for the transmission information from the mobile station.   A program for causing a computer to execute an operation of a mobile station in a mobile communication system that determines a transmission method of transmission information of a channel according to the propagation quality of a downlink from a base station, the propagation quality being A program comprising: a process of measuring; a process of turbo decoding the transmission information; and a process of correcting the propagation quality according to the number of repetitions of the turbo decoding and notifying the base station. A program for causing a computer to execute an operation of a base station that determines a transmission method of transmission information of a corresponding link according to a propagation quality of a downlink measured in a mobile station,
The propagation quality is obtained by turbo decoding the transmission information in the mobile station and correcting the transmission information according to the number of repetitions of the turbo decoding.
The program characterized by including the process which determines the said transmission system according to the said propagation quality notified from the said mobile station.

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