JP2009278684A - Transmission apparatus, receiving apparatus and wireless communication system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent a fall in downlink throughput in a communication system in which communication resources are allocated to communication terminals on the basis of downlink channel quality. <P>SOLUTION: A communication mode determination section 201 determines the communication mode on the basis of the CIR measured by a CIR measurement section 219; a DRC signal creation section 202 creates a DRC signal with a number corresponding to the communication mode; and a DRC power controller 205 refers to a transmission power table 206 showing the correspondence between DRC numbers and transmission power, and, on the basis of the transmission power of a pilot signal output from a pilot power controller 209, increases transmission power in proportion as the DRC signal indicates that downlink channel quality is good. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a transmission device, a reception device, and a wireless communication system used in a cellular communication system.

  In the cellular communication system, one base station performs wireless communication simultaneously with a plurality of communication terminals, and with the recent increase in demand, it is required to increase transmission efficiency.

  HDR (High Data Rate) has been proposed as a technique for improving the transmission efficiency of a downlink from a base station to a communication terminal. HDR is a method in which a base station performs scheduling for allocating communication resources to each communication terminal and assigns the communication resources to each communication terminal, and further sets a transmission rate for each communication terminal according to downlink channel quality and transmits data.

  Hereinafter, an operation in which the base station and the communication terminal perform wireless communication in HDR will be described. First, the base station transmits a pilot signal to each communication terminal. Each communication terminal estimates a downlink channel quality by CIR (desired wave-to-interference wave ratio) based on a pilot signal and obtains a transmission rate at which communication is possible. Each communication terminal selects a communication mode that is a combination of a packet length, an encoding scheme, and a modulation scheme based on a communicable transmission rate, and data rate control (hereinafter referred to as “DRC”) indicating the communication mode. Send the signal to the base station.

  Note that the types of modulation schemes that can be used in each system are determined in advance, such as BPSK, QPSK, 16QAM, and 64QAM. The types of encoding that can be used in each system are determined in advance, such as 1/2 turbo code, 1/3 turbo code, 3/4 turbo code, and the like. A plurality of transmission rates that can be used in each system are determined by a combination of the packet length, the modulation method, and the coding method. Each communication terminal selects a combination capable of performing communication most efficiently in the current channel quality of the downlink from the combinations, and transmits a DRC signal indicating the selected communication mode to the base station. In general, DRC signals are represented by numbers 1 to N, and the higher the number, the better the quality of the downlink.

  The base station performs scheduling based on the DRC signal transmitted from each communication terminal, sets a transmission rate for each communication terminal, and transmits a signal indicating allocation of communication resources to each communication terminal to each communication terminal through a control channel. Inform. In general, in consideration of improving the transmission efficiency of the system, the base station preferentially allocates communication resources to the communication terminal with the best downlink channel quality, that is, the communication terminal that has transmitted the DRC signal with the largest number. Allocate.

  Then, the base station transmits data only to the corresponding communication terminal at the allocated time. For example, when time t1 is allocated to communication terminal A, the base station transmits data only to communication terminal A at time t1, and does not transmit data to communication terminals other than communication terminal A.

  Thus, conventionally, by setting a transmission rate for each communication terminal according to channel quality by HDR and preferentially allocating communication resources to communication terminals having a high communication rate, data transmission efficiency can be improved as a whole system. It is increasing.

  However, if the communication mode determined by the communication terminal is erroneously received at the base station due to deterioration of the line condition of the uplink from the communication terminal to the base station, the base station transmits data in the erroneous communication mode. End up. In the communication terminal, since the determined communication mode is different from the communication mode of the transmitted data, the data cannot be demodulated and decoded.

  Further, as described above, when time t1 is allocated to communication terminal A, the base station transmits data only to communication terminal A at time t1, and transmits data to communication terminals other than communication terminal A. Do not send.

  From the above, when the communication mode determined by the communication terminal is erroneously received at the base station, there is a problem that a section in which the time-division communication resources are not used is generated and the downlink throughput is reduced.

  The present invention has been made in view of such points, and in a communication system in which communication resources are allocated to each communication terminal based on downlink channel quality, a transmission device capable of preventing a decrease in downlink throughput, An object is to provide a receiving apparatus and a wireless communication system.

  A communication terminal apparatus according to a first aspect of the present invention is a communication terminal apparatus used in a communication system in which communication resources are allocated to each communication terminal apparatus based on downlink line quality, and the downlink line quality is Measuring means, and transmitting means for transmitting a notification signal for notifying the base station apparatus of information indicating the channel quality, wherein the transmitting means includes a base station of the information indicating the channel quality. A configuration is adopted in which a notification signal is transmitted in such a way that information having a high possibility of lowering the downlink throughput when it is erroneously received by the station apparatus is less likely to be erroneous in the propagation path.

  According to this configuration, since a notification signal that is less likely to be erroneous in a propagation path is transmitted for information that is more likely to reduce downlink throughput when received by the base station apparatus in error, the downlink throughput is reduced. Can be prevented.

  The communication terminal apparatus according to the second aspect of the present invention employs a configuration in which the transmission means transmits a notification signal indicating that the channel quality is good with less error in the propagation path.

  According to this configuration, since the notification signal indicating that the channel quality of the downlink is good is transmitted with less error, the error occurrence rate of the notification signal that is frequently selected in the base station can be reduced. Thereby, it is possible to reduce the possibility that communication resource allocation is determined based on an erroneous notification signal.

  The communication terminal apparatus according to the third aspect of the present invention employs a configuration in which the transmission means transmits a notification signal having a higher transmission power for a notification signal indicating that the line quality is better.

  According to this configuration, since a notification signal indicating that the downlink channel quality is good is transmitted with a higher transmission power, a notification signal indicating that the downlink channel quality is good can be made less error-prone.

  A communication terminal apparatus according to a fourth aspect of the present invention comprises control means for controlling transmission power of a pilot signal, and the transmission means sends a notification signal indicating a channel quality better than a predetermined channel quality to the pilot signal. A configuration is adopted in which the transmission power is set higher than the transmission power, and the notification signal indicating the channel quality worse than the predetermined channel quality is transmitted with the transmission power lower than the transmission power of the pilot signal.

  According to this configuration, since the notification signal with the increased transmission power and the notification signal with the decreased transmission power are transmitted compared to the conventional transmission power of the notification signal, the average transmission power of the notification signal is In comparison, a notification signal indicating that the downlink channel quality is good can be made less error-prone while being kept constant. That is, a notification signal indicating that the downlink channel quality is good can be made less prone to error without reducing the downlink capacity compared to the conventional one.

  A communication terminal apparatus according to a fifth aspect of the present invention comprises a table indicating a correspondence relationship between a notification signal and transmission power, and rewriting means for rewriting the contents of the table according to a control signal from a base station apparatus, The transmission means adopts a configuration for controlling the notification signal to a predetermined transmission power based on the table.

  According to this configuration, since the table is adaptively rewritten in response to changes in the communication environment, the error rate of the notification signal can be suppressed even when the communication environment deteriorates.

  The communication terminal apparatus according to the sixth aspect of the present invention employs a configuration in which the transmission means converts the notification signal indicating that the channel quality is better into a codeword having a larger minimum intersymbol distance and transmits it.

  According to this configuration, since a notification signal indicating that the downlink channel quality is good is converted into a code word having a larger minimum code distance and transmitted, the notification signal indicating that the downlink channel quality is good is less likely to be erroneous. can do. Further, according to this configuration, since the code word error corresponding to each notification signal can be changed with a constant code word code length, the base station can change the demodulation system according to each code length. Since there is no need to provide a plurality, the base station apparatus configuration can be simplified.

  A communication terminal apparatus according to a seventh aspect of the present invention comprises a table indicating a correspondence relationship between a notification signal and codewords, and rewriting means for rewriting the contents of the table according to a control signal from a base station apparatus, The transmission means adopts a configuration for converting the notification signal into a predetermined code word based on the table.

  According to this configuration, since the table is adaptively rewritten in response to changes in the communication environment, the error rate of the notification signal can be suppressed even when the communication environment deteriorates.

  A communication terminal apparatus according to an eighth aspect of the present invention includes a determination unit that determines a communication mode indicated by a combination of a modulation scheme and an encoding scheme based on channel quality, and a transmission unit transmits a notification signal to the communication signal. A configuration is adopted in which a signal indicating the communication mode is used.

  According to this configuration, since the notification signal can be expressed by a very small number of bits, it is possible to improve the uplink line use efficiency.

  The communication terminal apparatus according to the ninth aspect of the present invention employs a configuration in which the measurement means measures the reception quality of the pilot signal, and the transmission means uses the notification signal as a signal indicating the reception quality.

  According to this configuration, it is not necessary for the communication terminal to determine the communication mode, so that the power consumption of the communication terminal can be reduced and the device scale can be reduced.

  In the communication terminal apparatus according to the tenth aspect of the present invention, the information having a large amount of change among the information used by the measuring unit to measure the reception quality of the pilot signal and the transmitting unit to indicate the value of the reception quality. A configuration is adopted in which a notification signal that is less susceptible to errors in the propagation path is transmitted.

  According to this configuration, since a notification signal that is less likely to be error in the propagation path is transmitted as the amount of change is larger, the degree of error regarding the value of the reception quality can be reduced. Thereby, possibility that an incorrect communication mode will be determined by a base station apparatus can be made low.

  The communication terminal apparatus according to the eleventh aspect of the present invention employs a configuration in which the transmission means transmits a notification signal converted into a code word having a code length that is longer as the value of the upper digit.

  According to this configuration, since the notification signal converted into a codeword having a longer code length is transmitted as the value of the upper digit, it is possible to reduce the error as the value of the upper digit having a larger change amount.

  The communication terminal apparatus according to the twelfth aspect of the present invention employs a configuration in which the transmission means transmits a notification signal having a higher transmission power as the value of the upper digit.

  According to this configuration, since the notification signal with higher transmission power is transmitted as the value of the upper digit increases, the value of the upper digit having a larger change amount can be transmitted with less error.

  The communication terminal apparatus according to the thirteenth aspect of the present invention employs a configuration in which the transmission means transmits a notification signal spread with a spreading code having a higher spreading factor as the value of the upper digit.

  According to this configuration, since the notification signal spread with the spreading code having a higher spreading factor is transmitted as the value of the upper digit, the value of the upper digit having a larger change amount can be transmitted with less error.

  A base station apparatus according to a fourteenth aspect of the present invention is a reception means for receiving a notification signal transmitted from any one of the communication terminal apparatuses, a measurement means for measuring the reception power of the notification signal, and the reception power. Detecting means for detecting a notification signal having a value smaller than a predetermined threshold, and determining means for deciding allocation of downlink communication resources using a notification signal excluding the detected notification signals from a plurality of received notification signals The structure which comprises these is taken.

  A base station apparatus according to a fifteenth aspect of the present invention is a reception means for receiving a notification signal transmitted from any one of the communication terminal apparatuses, a measurement means for measuring the likelihood of the notification signal, and the likelihood. Detecting means for detecting a notification signal having a value smaller than a predetermined threshold, and determining means for deciding allocation of downlink communication resources using a notification signal excluding the detected notification signals from a plurality of received notification signals The structure which comprises these is taken.

  According to these configurations, since allocation of downlink communication resources is determined by excluding notification signals that are likely to cause errors, it is possible to prevent communication resource allocation from being determined based on erroneous notification signals. Can do.

  A base station apparatus according to a sixteenth aspect of the present invention provides a communication means for rewriting a table based on a comparison result between a calculation means for calculating a detection rate at a detection means and the detection rate and a predetermined threshold value. And a transmission means for transmitting a control signal instructing the apparatus.

  According to this configuration, since the communication terminal can adaptively rewrite the table in response to changes in the communication environment, the error occurrence rate of the notification signal can be suppressed even when the communication environment deteriorates.

  In the radio communication method according to the seventeenth aspect of the present invention, when the communication terminal device transmits a notification signal for notifying the base station device of information indicating the downlink channel quality, the information indicating the channel quality is provided. Information that is more likely to reduce the throughput of the downlink when received by the base station device in error, transmits a notification signal in which the error is less likely to occur in the propagation path, and the base station device transmits the downlink according to the notification signal. The allocation of communication resources was decided.

  According to this method, since a notification signal that is less likely to be erroneous in a propagation path is transmitted for information that is likely to decrease downlink throughput when it is erroneously received by the base station apparatus, the downlink throughput is reduced. Can be prevented.

  In the radio communication method according to the eighteenth aspect of the present invention, the communication terminal apparatus transmits the notification signal indicating that the line quality is good with less error in the propagation path.

  According to this method, since a notification signal indicating that the channel quality of the downlink is good is transmitted with less error, the error occurrence rate of a notification signal that is frequently selected in the base station can be reduced. Thereby, it is possible to reduce the possibility that communication resource allocation is determined based on an erroneous notification signal.

  The wireless communication method according to the nineteenth aspect of the present invention is that a communication terminal apparatus measures a reception quality of a pilot signal, and among information used to indicate the value of the reception quality, a propagation path is indicated as information having a larger change amount. The notification signal which made it difficult to make mistakes was sent.

  According to this method, since a notification signal in which errors are less likely to occur in a propagation path is transmitted as information having a larger amount of change, the degree of error regarding the value of reception quality can be suppressed to a small value. Thereby, possibility that an incorrect communication mode will be determined by a base station apparatus can be made low.

  According to the present invention, in a communication system in which communication resources are allocated to each communication terminal based on downlink channel quality, it is possible to prevent a decrease in downlink throughput.

Graph showing DRC signal selection frequency in base station The block diagram which shows the structure of the base station which concerns on Embodiment 1 of this invention. The block diagram which shows the structure of the communication terminal which concerns on Embodiment 1 of this invention. The figure which shows the content of the transmission power table with which the communication terminal which concerns on Embodiment 1 of this invention is provided. The block diagram which shows another structure of the base station which concerns on Embodiment 1 of this invention. The block diagram which shows the structure of the communication terminal which concerns on Embodiment 2 of this invention. The figure which shows the content of the codeword table with which the communication terminal which concerns on Embodiment 2 of this invention is provided. The block diagram which shows the structure of the base station which concerns on Embodiment 3 of this invention. The block diagram which shows the structure of the communication terminal which concerns on Embodiment 3 of this invention. The block diagram which shows the structure of the base station which concerns on Embodiment 4 of this invention. The block diagram which shows the structure of the communication terminal which concerns on Embodiment 4 of this invention. The block diagram which shows another structure of the base station which concerns on Embodiment 4 of this invention. The block diagram which shows the structure of the communication terminal which concerns on Embodiment 5 of this invention. The block diagram which shows the structure of the communication terminal which concerns on Embodiment 6 of this invention. The block diagram which shows the structure of the CIR signal preparation part of the communication terminal which concerns on Embodiment 6 of this invention. The block diagram which shows the structure of the CIR signal preparation part of the communication terminal which concerns on Embodiment 7 of this invention. The block diagram which shows the structure of the CIR signal preparation part of the communication terminal which concerns on Embodiment 8 of this invention.

  The essence of the present invention is that, among the information indicating the downlink channel quality, the communication terminal is less likely to make an error in the propagation path as the information that is likely to decrease the downlink throughput when it is erroneously received by the base station. Is transmitted to prevent a decrease in downlink throughput.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

(Embodiment 1)
As described above, the base station preferentially allocates communication resources to communication terminals with the best downlink channel quality. In other words, the base station selects the DRC signal having the largest number, and preferentially allocates communication resources to the communication terminal that has transmitted the selected DRC signal. Therefore, the DRC signal selection frequency in the base station is as shown in FIG. FIG. 1 is a graph showing DRC signal selection frequency in a base station. In this figure, DRC numbers 1 to 5 are used, and the larger the number, the better the line quality.

  As shown in FIG. 1, a DRC signal with a larger number has a higher frequency of selection at the base station. That is, the frequency with which communication resources are allocated increases as the communication terminal has better downlink channel quality. Such a relationship is caused by an increase in the probability that there are many communication terminals and there are communication terminals with good downlink channel quality.

  Thus, the selection frequency of each DRC signal is different according to the line quality. In other words, since the DRC signal indicating that the downlink channel quality is good tends to be selected more frequently, if a DRC signal indicating that the downlink channel quality is good is received by mistake, There is a high possibility that the throughput will decrease. In addition, since DRC signals indicating that the downlink channel quality is poor tend to be selected, even if a DRC signal indicating that the downlink channel quality is bad is received erroneously, The impact on throughput reduction is small.

  Therefore, the communication terminal according to Embodiment 1 of the present invention transmits a DRC signal indicating that the downlink channel quality is good with higher transmission power. Also, the base station according to Embodiment 1 of the present invention assigns communication resources by excluding DRC signals whose reception power is lower than a predetermined threshold.

  FIG. 2 is a block diagram showing the configuration of the base station according to Embodiment 1 of the present invention.

  In FIG. 2, the allocating unit 101 communicates communication resources to each communication terminal based on a DRC signal obtained by excluding a DRC signal detected by an unused DRC detection unit 116 (to be described later) from a DRC signal extracted by a demodulation unit 114 (to be described later). Determine the allocation of Then, assignment section 101 instructs buffer 102 to output downlink transmission data based on the determined allocation of communication resources, instructs adaptive coding section 103 the encoding method of downlink transmission data, and adaptive modulation section 104. The downlink transmission data modulation method is instructed to.

  Buffer 102 holds downlink transmission data, and outputs downlink transmission data for a predetermined communication terminal to adaptive encoding section 103 in accordance with an instruction from allocation section 101. Adaptive encoding section 103 encodes the output signal from buffer 102 in accordance with the instruction from allocation section 101 and outputs the encoded signal to adaptive modulation section 104. Adaptive modulation section 104 modulates the output signal from adaptive encoding section 103 in accordance with instructions from allocation section 102 and outputs the result to spreading section 105. Spreading section 105 spreads the output signal from adaptive modulation section 104 and outputs it to multiplexing section 108.

  Modulating section 106 modulates the pilot signal and outputs it to spreading section 107. Spreading section 107 spreads the output signal from modulating section 106 and outputs it to multiplexing section 108.

  Multiplexing section 108 time-multiplexes the spread pilot signal with spread downlink transmission data at a predetermined interval, and outputs the result to transmission RF section 109. The transmission RF unit 109 converts the frequency of the output signal from the multiplexing unit 108 into a radio frequency and outputs it to the duplexer 110.

  The duplexer 110 wirelessly transmits the output signal from the transmission RF unit 109 from the antenna 111 to the communication terminal. The duplexer 110 outputs a signal wirelessly transmitted from each communication terminal and wirelessly received by the antenna 111 to the reception RF unit 112.

  The reception RF unit 112 converts the frequency of the radio frequency signal output from the duplexer 110 into baseband and outputs the baseband to the despreading unit 113. Despreading section 113 despreads the baseband signal with a spreading code spreading the DRC signal and outputs the result to demodulation section 114 and reception power calculation section 115.

  Demodulation section 114 demodulates the output signal from despreading section 113 to extract a DRC signal and outputs it to allocating section 101.

  Reception power calculation section 115 measures the reception power of the DRC signal after despreading and outputs it to unused DRC detection section 116. The unused DRC detection unit 116 is set with a predetermined threshold value, which will be described later. A reception power DRC signal lower than this threshold value is detected, and the detection result is output to the allocation unit 101.

  The despreading unit 113, the demodulation unit 114, the reception power calculation unit 115, and the unused DRC detection unit 116 are provided for each communication terminal, and a DRC signal for each communication terminal is output from each demodulation unit 114. A detection result for each communication terminal is output from each unused DRC detection unit 116.

  FIG. 3 is a block diagram showing a configuration of the communication terminal according to Embodiment 1 of the present invention. In FIG. 3, a communication mode determination unit 201 determines a communication mode indicating a combination of a modulation scheme and a coding scheme based on CIR measured by a CIR measurement unit 219 described later, and sends it to the DRC signal creation unit 202. Output. Further, based on the determined communication mode, the communication mode determination unit 201 instructs the adaptive demodulation unit 216 about the downlink reception data demodulation method, and instructs the adaptive decoding unit 217 about the downlink reception data decoding method.

  DRC signal creation section 202 creates a DRC signal having a number corresponding to the communication mode output from communication mode determination section 201 and outputs the DRC signal to modulation section 203 and DRC power control section 205.

  Modulating section 203 modulates the DRC signal and outputs it to spreading section 204. The spreading unit 204 spreads the output signal from the modulation unit 203 and outputs it to the DRC power control unit 205. The DRC power control unit 205 refers to the transmission power table 206 in which the correspondence relationship between the DRC number and the transmission power is shown, and performs DRC based on the transmission power of the pilot signal output from the pilot power control unit 209 described later. The transmission power of the signal is controlled, and the DRC signal after the transmission power control is output to the multiplexing unit 210. A specific method for controlling the DRC signal transmission power will be described later.

  Modulating section 207 modulates the pilot signal and outputs it to spreading section 208. Spreading section 208 spreads the output signal from modulating section 207 and outputs it to pilot power control section 209. Pilot power control section 209 controls the transmission power of the pilot signal, and outputs the pilot signal after the transmission power control to multiplexing section 210. Pilot power control section 209 outputs pilot signal transmission power to DRC power control section 209.

  Multiplexing section 210 time-multiplexes the DRC signal after transmission power control and the pilot signal after transmission power control at a predetermined interval, and outputs the result to transmission RF section 211. The transmission RF unit 211 converts the frequency of the output signal from the multiplexing unit 210 into a radio frequency and outputs it to the duplexer 212.

  The duplexer 212 wirelessly transmits the output signal from the transmission RF unit 211 from the antenna 213 to the base station. The duplexer 212 outputs a signal wirelessly transmitted from the base station and wirelessly received by the antenna 213 to the reception RF unit 214.

  Reception RF section 214 converts the frequency of the radio frequency signal output from duplexer 212 to baseband, and outputs the baseband to despreading section 215 and despreading section 218.

  Despreading section 215 despreads the data component of the baseband signal and outputs it to adaptive demodulation section 216. Adaptive demodulation section 216 demodulates the output signal from despreading section 215 and outputs it to adaptive decoding section 217 in accordance with instructions from communication mode determining section 201. Adaptive decoding section 217 decodes the output signal from adaptive demodulation section 216 in accordance with instructions from communication mode determination section 201 to obtain received data.

  The despreading unit 218 despreads the pilot signal component of the baseband signal and outputs it to the CIR measurement unit 219. The CIR measurement unit 219 measures the CIR of the pilot signal output from the despreading unit 218 and outputs it to the communication mode determination unit 201.

  Next, a signal transmission / reception procedure between the base station shown in FIG. 2 and the communication terminal shown in FIG. 3 will be described.

  First, at the start of communication, a pilot signal is modulated by modulation section 106 of the base station, spread by spreading section 107, and output to multiplexing section 108. Only the spread pilot signal is output from the multiplexing unit 108 to the transmission RF unit 109. The spread pilot signal is frequency-converted to a radio frequency by transmission RF section 109 and is wirelessly transmitted from antenna 111 to each communication terminal via duplexer 110.

  A radio signal including only a pilot signal component wirelessly transmitted from the base station is received by the antenna 213 of the communication terminal, and frequency-converted to baseband by the reception RF unit 214 via the duplexer 212. The pilot signal component of the baseband signal is despread by the despreading unit 218 and output to the CIR measurement unit 219.

  Next, CIR measurement section 219 measures the CIR of the pilot signal output from despreading section 218, and communication mode determination section 201 determines the communication mode based on the CIR. Then, the DRC signal creation unit 202 creates a DRC signal having a number corresponding to the communication mode.

  The DRC signal is modulated by modulation section 203, spread by spreading section 204, and output to DRC power control section 205. The DRC power control unit 205 is based on the ratio between the pilot signal transmission power output from the pilot power control unit 209 and the transmission power of the pilot signal and the transmission power of the DRC signal preset in the transmission power table 206. , DRC signal transmission power is controlled.

  Hereinafter, the setting contents of the transmission power table 206 will be described. FIG. 4 is a diagram showing the contents of the transmission power table provided in the communication terminal according to Embodiment 1 of the present invention.

  The transmission power table 206 shows the correspondence between the DRC number and the transmission power of the DRC signal, and is set so that the transmission power increases as the DRC number increases. Here, DRC numbers 1 to 5 are used, and it is assumed that the higher the number, the better the line quality of the downlink. That is, the transmission power table 206 is set so that the transmission power becomes higher as the DRC signal indicates that the downlink channel quality is better.

  As described above, the DRC signal indicating that the downlink channel quality is good tends to be selected more frequently in the base station. Therefore, in the present embodiment, the DRC signal indicating that the downlink channel quality is good. The transmission power is increased so that errors are less likely to occur. Thereby, the probability that the DRC signal indicating that the downlink channel quality is good is erroneously received can be made lower than the probability that the DRC signal indicating that the downlink channel quality is bad is erroneously received. . In other words, the probability that a DRC signal that is frequently selected by the base station is erroneously received can be lower than the probability that a DRC signal that is frequently selected by the base station is erroneously received.

  Further, the transmission power of the DRC signal set in the transmission power table 206 is represented by a ratio with the transmission power of the pilot signal. Here, as shown in FIG. 4, with reference to DRC number 3 corresponding to the middle of DRC numbers 1 to 5, a DRC signal indicating a number smaller than DRC number 3 is transmitted with transmission power lower than the transmission power of the pilot signal. The DRC signal indicating a number greater than number 3 is set to be transmitted with a transmission power higher than the transmission power of the pilot signal. That is, here, a DRC signal indicating a channel quality worse than a predetermined channel quality (here, a channel quality corresponding to a DRC signal of DRC number 3) is transmitted with a transmission power lower than the transmission power of the pilot signal, A DRC signal indicating a channel quality better than the channel quality is set to be transmitted with a transmission power higher than that of the pilot signal.

  As described above, in the present embodiment, compared with the conventional DRC signal transmission power (that is, the pilot signal transmission power here), the DRC signal for increasing the transmission power and the DRC signal for decreasing the transmission power are set. Then, by setting the total increase / decrease value of the transmission power of the DRC signal to ± 0 dB, a DRC signal indicating that the channel quality of the downlink is good while keeping the average transmission power of the DRC signal constant compared to the conventional case. It can be made less prone to errors. That is, the DRC signal indicating that the downlink channel quality is good can be made less prone to error without reducing the uplink capacity compared to the conventional one.

  Also, as described above, the DRC signal indicating that the downlink channel quality is poor (in FIG. 4, the DRC signals of DRC numbers 1 and 2) are transmitted with lower transmission power than the conventional one, so that they are separated from the base station. In a communication terminal that is located at a certain location and has a high possibility of transmitting a DRC signal indicating that the downlink channel quality is poor, power consumption can be reduced. That is, in a communication terminal that transmits a DRC signal indicating that the downlink channel quality is poor, the DRC signal is conventionally transmitted with a high transmission power. Since the transmission power can be made lower than the high transmission power, the power consumption of the communication terminal can be greatly reduced.

  Note that since the DRC signal indicating that the downlink channel quality is poor is selected at the base station in the first place, the DRC signal indicating that the downlink channel quality is poor is transmitted at a lower transmission power than the conventional one. Even if it is transmitted, there is almost no influence on the decrease in throughput.

  Further, in the present embodiment, DRC signals (DRC signals with DRC numbers 4 and 5 in FIG. 4) indicating that the uplink channel quality is good are transmitted with higher transmission power than conventional. However, a DRC signal indicating that the uplink channel quality is good is highly likely to be transmitted from a communication terminal that is located relatively close to the base station. Also, transmission power of pilot signals transmitted from communication terminals existing relatively close to the base station by transmission power control for pilot signals normally performed on the uplink (that is, transmission power of conventional DRC signals) is In the first place, it is low. Therefore, in a communication terminal that transmits a DRC signal indicating that the channel quality of the uplink is good, even if the transmission power of the DRC signal that has been low originally increases, the transmission power of the DRC signal is still low and the power consumption is still low. There is almost no impact on power consumption.

  The DRC power control unit 205 obtains the transmission power of the DRC signal by adjusting the transmission power of the pilot signal output from the pilot power control unit 209 according to the ratio set in the transmission power table 206. In DRC power control section 205, the transmission power of the DRC signal output from spreading section 204 is controlled to the obtained transmission power, and the DRC signal after transmission power control is output to multiplexing section 210. Specifically, for example, when the number of the DRC signal output from the DRC signal creation unit 202 to the DRC power control unit 205 is 5, the transmission power of the DRC signal output from the spreading unit 204 is the pilot power. The transmission power is controlled to be 2 dB lower than the transmission power of the pilot signal output from the control unit 209.

  The DRC signal after transmission power control is multiplexed with the pilot signal in multiplexing section 210, converted to a radio frequency by transmission RF section 211, and wirelessly transmitted from antenna 213 to the base station via duplexer 212.

  A signal wirelessly transmitted from the communication terminal is received by the antenna 111 of the base station and input to the reception RF unit 112 via the duplexer 110. The signal input to the reception RF unit 112 is frequency-converted to baseband, despread by the spreading code spreading the DRC signal in the despreading unit 113, and output to the demodulation unit 114 and the reception power calculation unit 115. The

  Demodulation section 114 demodulates the output signal from despreading section 113, extracts a DRC signal, and outputs it to allocating section 101.

  Here, in the communication terminal, since the DRC signal indicating that the downlink channel quality is poor is transmitted with lower transmission power than the conventional one, the base station erroneously outputs the DRC signal indicating that the downlink channel quality is poor. The probability of receiving is increased. In addition, when communication resources are allocated based on the DRC signal received in error, the downlink throughput decreases as described above.

  Therefore, reception power calculation section 115 measures the reception power of the DRC signal after despreading and outputs it to unused DRC detection section 116. In the unused DRC detection unit 116, the lowest reception power that does not cause an error in the DRC signal indicating that the downlink channel quality is the worst (in FIG. 4, the DRC signal of DRC number 1) is preset as a threshold value Has been. Then, the unused DRC detection unit 116 detects a DRC signal having a reception power smaller than the threshold value, and outputs the detection result to the allocation unit 101. The DRC signal detected by the unused DRC detection unit 116 is a DRC signal that is not used when the allocation unit 101 determines communication resource allocation.

  In allocating section 101, allocation of communication resources to each communication terminal is determined based on the remaining DRC signals from which the DRC signals detected by unused DRC detecting section 116 are excluded from the DRC signals extracted by demodulating section 114. The

  As described above, the base station according to the present embodiment excludes a DRC signal having a reception power lower than the lowest reception power at which the DRC signal indicating that the downlink channel quality is the worst is not erroneously received. That is, the base station according to the present embodiment determines the allocation of downlink communication resources by excluding notification signals that are likely to cause errors. For this reason, according to the base station according to the present embodiment, even when a DRC signal indicating that the downlink channel quality is poor is transmitted with lower transmission power than in the prior art, communication resource allocation is performed based on the erroneous DRC signal. Can be prevented from being determined.

  As described above, according to the present embodiment, a DRC signal indicating that the downlink channel quality is good is transmitted with a higher transmission power. Therefore, a DRC signal indicating that the downlink channel quality is good is less likely to be erroneous. It is possible to reduce the error rate of DRC signals that are frequently selected at the base station. As a result, it is possible to reduce the possibility that communication resource allocation is determined based on an erroneous DRC signal, thereby preventing a decrease in downlink throughput.

  The base station according to the present embodiment may be configured as shown in FIG. FIG. 5 is a block diagram showing another configuration of the base station according to Embodiment 1 of the present invention. That is, instead of reception power calculation section 115 and unused DRC detection section 116 shown in FIG. 2, a base station may be configured by including likelihood calculation section 301 and unused DRC detection section 302. In the following description, the same components as those in FIG. 2 are denoted by the same reference numerals as those in FIG.

  In FIG. 5, the likelihood calculating unit 301 calculates a likelihood indicating the degree of probability of the DRC signal and outputs the likelihood to the unused DRC detecting unit 302. In the unused DRC detection unit 302, a minimum likelihood that an error does not occur in a DRC signal indicating that the downlink channel quality is the worst is preset as a threshold value. Then, the unused DRC detection unit 302 detects a DRC signal having a likelihood smaller than the threshold value, and outputs the detection result to the allocation unit 101.

  Thus, even when the base station according to the present embodiment is configured as shown in FIG. 5, the same effects as described above are exhibited.

(Embodiment 2)
The communication terminal according to Embodiment 2 of the present invention converts a DRC signal indicating that the downlink channel quality is better into a codeword having a larger minimum code distance with respect to the codeword of the other DRC signal and transmits it. It is.

  FIG. 6 is a block diagram showing a configuration of a communication terminal according to Embodiment 2 of the present invention. As shown in this figure, the communication terminal according to the present embodiment replaces modulation section 203, spreading section 204, DRC power control section 205 and transmission power table 206 shown in FIG. A table 402, a modulation unit 403, and a spreading unit 404 are provided. In the following description, the same components as those in FIG. 3 are denoted by the same reference numerals as those in FIG.

  The codeword selection unit 401 refers to the codeword table 402, converts the DRC signal created by the DRC signal creation unit 202 into a predetermined codeword, and outputs it to the modulation unit 403. Modulating section 403 modulates the code word and outputs it to spreading section 404. Spreading section 404 spreads the output signal from modulating section 403 and outputs it to multiplexing section 210.

  Next, the operation of the communication terminal according to the present embodiment will be described.

  First, the setting contents of the codeword table 402 will be described. FIG. 7 is a diagram showing the contents of the codeword table provided in the communication terminal according to Embodiment 2 of the present invention.

  The codeword table 402 shows the correspondence between the DRC number and the codeword after the DRC signal conversion, and the codeword table 402 is set so that the larger the DRC number is, the larger the minimum code distance is. Yes. Here, DRC numbers 1 to 5 are used, and it is assumed that the higher the number, the better the line quality of the downlink. That is, the codeword table 402 is set so that the DRC signal indicating that the downlink channel quality is better is converted into a codeword having a larger minimum intersymbol distance.

  Here, the intercode distance is the number of bits that differ between the codewords, and the minimum intercode distance is the minimum number of bits that a codeword differs from all other codewords. Specifically, the code word corresponding to the DRC signal with DRC number 5 is '111111111', and this code word '111111111' is compared with any of the code words corresponding to the DRC signals with DRC numbers 1 to 4 In addition, at least 6 bits are different. Therefore, the minimum inter-code distance of the code word corresponding to the DRC signal with DRC number 5 is 6. Similarly, the minimum inter-code distance of the code word corresponding to the DRC signal with the DRC number 4 is 3.

  Therefore, the code word corresponding to the DRC signal of DRC number 5 is less likely to be mistaken for other code words than the code word corresponding to the DRC signal of DRC number 4. That is, a codeword having a larger minimum code distance is less likely to be mistaken for another codeword.

  In codeword selection section 401, the DRC signal output from DRC signal creation section 202 is converted into a codeword set in codeword table 402 and output to modulation section 403. Specifically, for example, when the DRC signal output from the DRC signal creation unit 202 is a DRC signal of number 5, it is converted into codeword '111111111'.

  The converted codeword is modulated by modulation section 403 and spread by spreading section 404. The spread codeword is multiplexed with the pilot signal in multiplexing section 210, frequency-converted to a radio frequency by transmission RF section 211, and wirelessly transmitted from antenna 213 to the base station via duplexer 212.

  Thus, according to the present embodiment, the DRC signal indicating that the downlink channel quality is good is converted into a codeword having a larger minimum code distance with respect to the codeword of the other DRC signal, and transmitted. A DRC signal indicating that the downlink channel quality is good can be made more unlikely to be an error, and an error occurrence rate of a DRC signal that is frequently selected in the base station can be reduced. As a result, it is possible to reduce the possibility that communication resource allocation is determined based on an erroneous DRC signal, thereby preventing a decrease in downlink throughput.

  Further, according to the present embodiment, it is possible to reduce the error occurrence rate of a DRC signal that is frequently selected in the base station without increasing the transmission power of the DRC signal, thereby increasing the power consumption of the communication terminal. Without making it possible, it is possible to reduce the possibility that communication resource allocation is determined based on an erroneous DRC signal.

  Further, according to the present embodiment, since the code word error corresponding to each DRC signal can be changed with a constant code word code length, the base station demodulates according to each code length. Since it is not necessary to provide a plurality of systems, the base station apparatus configuration can be simplified.

(Embodiment 3)
The base station according to Embodiment 3 of the present invention transmits a control signal for table rewriting to the communication terminal based on the occurrence rate of DRC signals that are excluded when communication resource allocation is determined. The communication terminal according to Embodiment 3 rewrites the contents of the transmission power table or codeword table based on the control signal transmitted from the base station.

  FIG. 8 is a block diagram showing the configuration of the base station according to Embodiment 3 of the present invention. As shown in this figure, the base station according to the present embodiment is configured to further include a detection rate calculation unit 501, a control signal creation unit 502, a modulation unit 503, and a spreading unit 504 in the configuration shown in FIG. In the following description, the same components as those in FIG. 2 are denoted by the same reference numerals as those in FIG.

  In FIG. 8, the detection rate calculation unit 501 calculates the detection rate in the unused DRC detection unit 116 and outputs the detection rate to the control signal creation unit 502. That is, the detection rate calculation unit 501 calculates the occurrence rate of DRC signals that are excluded when communication resource allocation is determined. Control signal creation section 502 creates a control signal for table rewriting (hereinafter referred to as “table rewriting signal”) based on the detection rate, and outputs the control signal to modulation section 503. Modulation section 503 modulates the table rewrite signal and outputs the result to spreading section 504. Spreading section 504 spreads the output signal from modulation section 503 and outputs the result to multiplexing section 108.

  FIG. 9 is a block diagram showing a configuration of a communication terminal according to Embodiment 3 of the present invention. As shown in this figure, the communication terminal according to the present embodiment is configured to further include a despreading unit 601, a demodulating unit 602, and a table rewriting unit 603 in addition to the configuration shown in FIG. In the following description, the same components as those in FIG. 3 are denoted by the same reference numerals as those in FIG.

  In FIG. 9, the despreading unit 601 despreads the baseband signal with the spreading code in which the table rewrite signal is spread and outputs it to the demodulating unit 602. Demodulation section 602 demodulates the output signal from despreading section 601, extracts a table rewrite signal, and outputs it to table rewrite section 603. The table rewriting unit 603 rewrites the contents of the transmission power table according to the table rewriting signal.

  Next, a signal transmission / reception procedure between the base station shown in FIG. 8 and the communication terminal shown in FIG. 9 will be described.

  First, in the base station detection rate calculation unit 501, the detection rate in the unused DRC detection unit 116 is calculated and output to the control signal creation unit 502. The detection rate can be calculated from the number of detections in a predetermined time, for example.

  The control signal creation unit 502 is set with a predetermined threshold value of the detection rate, and the threshold value is compared with the detection rate calculated by the detection rate calculation unit 501. When the detection rate calculated by the detection rate calculation unit 501 is equal to or greater than the threshold value, a table rewrite signal is generated to instruct to increase all transmission powers set in the transmission power table 206, It is output to the modulation unit 503. That is, in the control signal creation unit 502, when the occurrence rate of DRC signals that are excluded when communication resource allocation is determined exceeds a predetermined threshold value, the transmission power of each DRC signal is set higher than the current transmission power. A table rewrite signal instructing to increase uniformly is created.

  The table rewrite signal is modulated by modulation section 503, spread by spreading section 504, and output to multiplexing section 108. The spread table rewrite signal is multiplexed with the transmission data and pilot signal by multiplexing section 108, converted to a radio frequency by transmission RF section 109, and wirelessly transmitted from antenna 111 to each communication terminal via duplexer 110. Is done.

  A radio signal wirelessly transmitted from the base station is received by the antenna 213 of the communication terminal, and frequency-converted to baseband by the reception RF unit 214 via the duplexer 212. The baseband signal is despread by the despreader 601 and demodulated by the demodulator 602 to extract a table rewrite signal. The extracted table rewriting signal is output to the table rewriting unit 603.

  The table rewriting unit 603 rewrites the contents of the transmission power table 206 in accordance with the table rewriting signal. That is, the table rewriting unit 603 increases all transmission powers set in the transmission power table 206.

  In the above description, the table rewriting unit 603 rewrites the contents of the transmission power table 206. However, the present embodiment is applied to the communication terminal according to the second embodiment, and the table rewriting unit 603 is shown in FIG. The content of the codeword table 402 may be rewritten.

  In this case, control signal creation section 502 of the base station according to the present embodiment is set in codeword table 402 when the detection rate calculated by detection rate calculation section 501 is equal to or greater than a threshold value. A table rewrite signal for instructing to increase all the minimum inter-code distances of codewords is created. That is, if the occurrence rate of DRC signals that are excluded when communication resource allocation is determined exceeds a predetermined threshold, control signal creation section 502 determines the minimum codeword corresponding to each DRC signal. A table rewrite signal is generated to instruct the inter-code distance to be uniformly larger than the current distance. Then, the table rewriting unit 603 of the communication terminal rewrites the contents of the codeword table 402 according to the table rewriting signal. That is, the table rewriting unit 603 rewrites the codeword set in the codeword table 402 to a codeword in which all the minimum inter-code distances are larger than the current one.

  Thus, in the present embodiment, the contents of the transmission power table or codeword table are rewritten based on the DRC signal generation rate that is excluded when communication resource allocation is determined. In other words, in the present embodiment, the contents of the transmission power table or codeword table are rewritten adaptively in response to changes in the communication environment. That is, according to the present embodiment, when the occurrence rate of DRC signals excluded when the communication environment deteriorates and communication resource allocation is determined exceeds a predetermined threshold, each DRC signal Therefore, even when the communication environment is deteriorated, the error rate of DRC signals can be suppressed.

  In the present embodiment, the predetermined threshold value of the detection rate is appropriately determined in consideration of the environment where the communication system is applied.

  Further, in the present embodiment, a second predetermined threshold value is further set in the control signal creation unit 502, and the detection rate calculated by the detection rate calculation unit 501 is higher than the second threshold value. If the transmission power table 206 becomes smaller, a table rewrite signal may be generated that instructs to reduce all transmission power set in the transmission power table 206. Thereby, when the reception quality of the DRC signal becomes excessive, the transmission power of the DRC signal can be lowered, so that the power consumption of the communication terminal can be reduced.

  Further, in this embodiment, the table is rewritten based on the detection rate in the unused DRC detection unit 116, but the DRC used to determine communication resource allocation among the DRC signals transmitted from the mobile station. Based on the signal distribution, the table may be rewritten so that the distribution becomes an optimal distribution. In this case, the base station shown in FIG. 8 is configured to include a use DRC distribution determination unit instead of the detection rate calculation unit, and the use DRC distribution determination unit is not used with the DRC signal output from the demodulation unit 114. Based on the detection result output from the DRC detection unit 116, the distribution of the DRC signal used for determining the allocation of communication resources is determined, and a signal indicating the distribution is output to the control signal creation unit 502. Further, the control signal creation unit 502 creates a table rewrite signal based on the signal indicating the distribution output from the used DRC distribution determination unit.

(Embodiment 4)
The communication terminal according to Embodiment 4 of the present invention transmits the CIR information indicating that the downlink channel quality is good with higher transmission power. Also, the base station according to Embodiment 4 of the present invention assigns communication resources by excluding CIR information whose reception power is lower than a predetermined threshold.

  In Embodiment 1 above, the communication terminal determines a communication mode based on the CIR, transmits a DRC signal corresponding to the determined communication mode to the base station with a predetermined transmission power, and the base station transmits the DRC signal. Based on the above, the allocation of communication resources to each communication terminal was determined. Since the DRC signal can be represented by a very small number of bits compared to other information indicating the channel quality of the downlink (for example, CIR of the downlink), the DRC signal can be used to improve the uplink channel usage efficiency. There is an advantage that it can be increased. On the other hand, the communication terminal needs to determine a communication mode and create a DRC signal, and also needs to have a communication mode determination table, a DRC signal creation table, and the like. There is a disadvantage that the size of the apparatus increases and the size of the apparatus increases.

  Therefore, in this embodiment, the communication terminal transmits CIR information to the base station with a predetermined transmission power, and after the base station determines the communication mode based on the CIR information, the communication resource of each communication terminal is determined. Determine allocation. By doing so, there is a disadvantage that the line use efficiency of the uplink is somewhat lowered, but the communication terminal does not need to determine the communication mode and create the DRC signal, and for communication mode determination Therefore, there is no need to provide a table for creating a DRC signal, a table for creating a DRC signal, and the like. Also, in this embodiment, since the base station can compare CIR information of a plurality of terminals and determine an accurate communication mode with certainty, this embodiment changes the communication mode from the CIR in each communication terminal. This is particularly effective when it cannot be determined simply.

  Hereinafter, the base station according to the present embodiment and the communication terminal according to the present embodiment will be described. FIG. 10 is a block diagram showing a configuration of a base station according to Embodiment 4 of the present invention. In the following description, the same components as those in FIG. 2 are denoted by the same reference numerals as those in FIG.

  In FIG. 10, the demodulation unit 701 demodulates the output signal from the despreading unit 113, extracts a signal including CIR information (hereinafter referred to as “CIR signal”), and outputs the signal to the allocation unit 704.

  The reception power calculation unit 702 measures the reception power of the despread CIR signal and outputs it to the unused CIR detection unit 703. The unused CIR detection unit 703 is set with a predetermined threshold as in the first embodiment, detects a CIR signal having a reception power lower than the threshold, and sends the detection result to the allocation unit 704. Output.

  The despreading unit 113, the demodulation unit 701, the reception power calculation unit 702, and the unused CIR detection unit 703 are provided for each communication terminal, and the CIR signal for each communication terminal is output from each demodulation unit 701. Each unused CIR detection unit 703 outputs a detection result for each communication terminal.

  The allocation unit 704 determines allocation of communication resources to each communication terminal based on the CIR information indicated by the CIR signal obtained by excluding the CIR signal detected by the unused CIR detection unit 703 from the CIR signal extracted by the demodulation unit 701. To do. Allocation unit 704 then instructs buffer 102 to output downlink transmission data based on the determined allocation of communication resources, and outputs CIR information to communication mode determination unit 705.

  Communication mode determination section 705 determines a communication mode indicating a combination of a modulation scheme and an encoding scheme based on CIR information output from allocation section 704 and outputs a signal indicating the communication mode to modulation section 706. . Further, based on the determined communication mode, communication mode determination section 705 instructs adaptive encoding section 103 to specify a downlink transmission data encoding scheme and instructs adaptive modulation section 104 to specify a downlink transmission data modulation scheme. Modulating section 706 modulates a signal indicating the communication mode, and outputs the modulated signal to spreading section 707. Spreading section 707 spreads the output signal from modulating section 706 and outputs the result to multiplexing section 108.

  FIG. 11 is a block diagram showing a configuration of a communication terminal according to Embodiment 4 of the present invention. In the following description, the same components as those in FIG. 3 are denoted by the same reference numerals as those in FIG.

  In FIG. 11, the CIR information creation unit 801 creates a CIR signal indicating the CIR measured by the CIR measurement unit 219 and outputs the CIR signal to the modulation unit 802 and the CIR information power control unit 804. Modulation section 802 modulates the CIR signal and outputs the result to spreading section 803. The spreading unit 803 spreads the output signal from the modulation unit 802 and outputs it to the CIR information power control unit 804. The CIR information power control unit 804 refers to the transmission power table 805 showing the correspondence between the size of the CIR and the transmission power, and determines the CIR information based on the transmission power of the pilot signal output from the pilot power control unit 209. The transmission power of the signal is controlled, and the CIR signal after the transmission power control is output to the multiplexing unit 210.

  Despreading section 807 despreads the baseband signal with a spreading code spreading the signal indicating the communication mode, and outputs the despread signal to communication mode detecting section 808. The communication mode detection unit 808 demodulates the output signal from the despreading unit 807 and detects the communication mode. Based on the detected communication mode, the communication mode detection unit 808 instructs the adaptive demodulation unit 216 about the downlink reception data demodulation method, and instructs the adaptive decoding unit 217 about the downlink reception data decoding method.

  Next, a signal transmission / reception procedure between the base station shown in FIG. 10 and the communication terminal shown in FIG. 11 will be described.

  First, in the communication terminal shown in FIG. 11, CIR measurement section 219 measures the CIR of the pilot signal output from despreading section 218, and CIR information creation section 801 creates a CIR signal.

  The CIR signal is modulated by modulation section 802, spread by spreading section 803, and output to CIR information power control section 804. Similar to the first embodiment, the transmission power table 805 shows the correspondence between the CIR size and the CIR signal transmission power, and the CIR signal transmission power increases as the CIR increases. ing. That is, in the transmission power table 805, as in the first embodiment, the CIR signal indicating that the downlink channel quality is good is set so that the transmission power becomes higher. Also, the transmission power of the CIR signal set in the transmission power table 805 is represented by the ratio with the transmission power of the pilot signal, as in the first embodiment.

  The CIR information power control unit 804 obtains the transmission power of the CIR signal by adjusting the transmission power of the pilot signal output from the pilot power control unit 209 according to the ratio set in the transmission power table 805. In CIR information power control section 804, the transmission power of the CIR signal output from spreading section 803 is controlled to the obtained transmission power, and the CIR signal after the transmission power control is output to multiplexing section 210.

  The CIR signal after transmission power control is multiplexed with the pilot signal in multiplexing section 210, converted to a radio frequency by transmission RF section 211, and wirelessly transmitted from antenna 213 to the base station via duplexer 212.

  In the base station shown in FIG. 10, the demodulation unit 701 demodulates the output signal from the despreading unit 113, extracts the CIR signal, and outputs the CIR signal to the allocation unit 704. The reception power calculation unit 702 measures the reception power of the despread CIR signal and outputs it to the unused CIR detection unit 703. In the unused CIR detection unit 703, as in the first embodiment, the lowest reception power at which no error occurs in the CIR signal indicating that the downlink channel quality is the worst is preset as a threshold value. The unused CIR detection unit 703 detects a CIR signal having a reception power smaller than the threshold value, and outputs the detection result to the allocation unit 704. The CIR signal detected by the unused CIR detection unit 703 is a CIR signal that is not used when the allocation unit 704 determines the allocation of communication resources.

  The allocation unit 704 allocates communication resources to each communication terminal based on the CIR indicated by the remaining CIR signal obtained by removing the CIR signal detected by the unused CIR detection unit 703 from the CIR signal extracted by the demodulation unit 701. Is determined, and the CIR information is output to the communication mode determination unit 705.

  Communication mode determination section 705 determines a communication mode based on the CIR information output from allocation section 704 and outputs a signal indicating the communication mode to modulation section 706. A signal indicating a communication mode is modulated by a modulation unit 706, spread by a spreading unit 707, multiplexed by transmission data and a pilot signal by a multiplexing unit 108, and frequency-converted to a radio frequency by a transmission RF unit 109, It is wirelessly transmitted from the antenna 111 to the communication terminal via the duplexer 110.

  In the communication terminal shown in FIG. 11, the despreading section 807 despreads the baseband signal and outputs the despread signal to the communication mode detection section 808. In communication mode detection section 808, the output signal from despreading section 807 is demodulated to detect the communication mode, and based on the detected communication mode, adaptive demodulation section 216 is instructed to demodulate the downlink received data, and adaptive The decoding unit 217 is instructed to decode the downlink received data.

  Thus, according to the present embodiment, as in the first embodiment, the CIR signal indicating that the channel quality of the downlink is good is transmitted with a higher transmission power, and therefore the frequency used in the base station. It is possible to reduce the error occurrence rate of high CIR information. As a result, it is possible to reduce the possibility that communication resource allocation is determined based on erroneous CIR information, and it is possible to prevent a decrease in downlink throughput.

  In addition, according to the present embodiment, as in the first embodiment, the CIR signal of the reception power lower than the lowest reception power at which the CIR signal indicating that the downlink channel quality is the worst is not erroneously received is excluded. Therefore, even when a CIR signal indicating that the downlink channel quality is poor is transmitted with lower transmission power than in the past, it is possible to prevent communication resource allocation from being determined based on erroneous CIR information. .

  Note that the base station according to the present embodiment may be configured as shown in FIG. FIG. 12 is a block diagram showing another configuration of the base station according to Embodiment 4 of the present invention. That is, instead of the reception power calculation unit 702 and the unused CIR detection unit 703 illustrated in FIG. 10, a base station may be configured by including a likelihood calculation unit 901 and an unused CIR detection unit 902. In the following description, the same components as those in FIG. 10 are denoted by the same reference numerals as those in FIG.

  In FIG. 12, the likelihood calculating unit 901 calculates a likelihood indicating the degree of likelihood of the CIR signal and outputs the likelihood to the unused CIR detecting unit 902. In the unused CIR detection unit 902, a minimum likelihood that no error occurs in a CIR signal indicating that the downlink channel quality is the worst is preset as a threshold value. Unused CIR detection section 902 detects a CIR signal having a likelihood smaller than the threshold value, and outputs the detection result to allocation section 704.

  Thus, even when the base station according to the present embodiment is configured as shown in FIG. 12, the same effects as described above are exhibited.

(Embodiment 5)
The communication terminal according to Embodiment 5 of the present invention converts a CIR signal indicating that the downlink channel quality is better into a codeword having a larger minimum code distance with respect to the codeword of the other CIR signal, and transmits the codeword. It is.

  FIG. 13 is a block diagram showing a configuration of a communication terminal according to Embodiment 5 of the present invention. As shown in this figure, the communication terminal according to the present embodiment replaces modulation section 802, spreading section 803, CIR information power control section 804 and transmission power table 805 shown in FIG. A word table 1002, a modulation unit 1003, and a spreading unit 1004 are provided. In the following description, the same components as those in FIG. 11 are denoted by the same reference numerals as those in FIG.

  The codeword selection unit 1001 refers to the codeword table 1002, converts the CIR signal created by the CIR information creation unit 801 into a predetermined codeword, and outputs the codeword to the modulation unit 1003. Modulation section 1003 modulates the code word and outputs it to spreading section 1004. Spreading section 1004 spreads the output signal from modulation section 1003 and outputs the result to multiplexing section 210.

  Next, the operation of the communication terminal according to the present embodiment will be described.

  The codeword table 1002 shows the correspondence between the CIR size and the codeword after CIR signal conversion, as in the second embodiment, and the larger the CIR size, the smaller the minimum inter-code distance. The CIR signal is set to be converted into a large code word. That is, the codeword table 1002 is set so that the CIR signal indicating that the downlink channel quality is better is converted into a codeword having a larger minimum intersymbol distance.

  In the code word selection unit 1001, the CIR signal output from the CIR information creation unit 801 is converted into a code word set in the code word table 1002 and output to the modulation unit 1003. The converted codeword is modulated by modulation section 1003 and spread by spreading section 1004. The spread codeword is multiplexed with the pilot signal in multiplexing section 210, frequency-converted to a radio frequency by transmission RF section 211, and wirelessly transmitted from antenna 213 to the base station via duplexer 212.

  As described above, according to the present embodiment, as in the second embodiment, the CIR signal indicating that the downlink channel quality is better, the codeword having the larger minimum inter-code distance with respect to the codewords of other CIR signals. Therefore, the error occurrence rate of CIR information frequently used in the base station can be reduced. As a result, it is possible to reduce the possibility that communication resource allocation is determined based on erroneous CIR information, and it is possible to prevent a decrease in downlink throughput.

  Further, according to the present embodiment, as in the second embodiment, it is possible to reduce the error occurrence rate of CIR information frequently used in the base station without increasing the transmission power of the CIR signal. Without increasing the power consumption of the communication terminal, it is possible to reduce the possibility that communication resource allocation is determined based on erroneous CIR information.

  Also, according to the present embodiment, as in the second embodiment, the base station can change the difficulty of the codeword corresponding to each CIR signal while keeping the codeword code length constant. Since there is no need to provide a plurality of demodulation systems according to each code length, the base station apparatus configuration can be simplified.

(Embodiment 6)
The communication terminals according to Embodiments 6 to 8 of the present invention transmit the information having a larger change amount in the CIR information with less error in the propagation path. In other words, the communication terminals according to Embodiments 6 to 8 of the present invention transmit information indicating a rough value in the CIR information with less error in the propagation path.

  Here, “information with a large amount of change” and “information indicating a rough value” specifically include, for example, when the CIR value is represented by a decimal value (for example, 8.7 dB), an integer part ( In other words, this is “8”). In this case, the amount of change per unit of the integer portion is 1 dB, and the amount of change per unit of the decimal portion is 0.1 dB. Therefore, the integer portion becomes “information with a large amount of change”. Therefore, in the base station, when the integer part is received in error, the degree of error becomes larger than in the case where the decimal part is received in error, and there is a high possibility that an incorrect communication mode is determined. That is, there is a high possibility that the downlink throughput will decrease.

  Also, the CIR information is usually converted into a code word with a limited number of bits and transmitted to the base station. Also, there is a limit to the transmission power that can be used to transmit CIR information and the spreading rate of the spreading code. Therefore, it is difficult and difficult to make the entire CIR information difficult to error.

  Therefore, in Embodiments 6 to 8 of the present invention, only “information with a large amount of change” (that is, “information indicating a rough value”) of CIR information is accurate within the above-described restrictions on transmission of CIR information. In the above-mentioned limit, “information with a large change amount” is transmitted with less error in the propagation path.

  Hereinafter, a communication terminal according to Embodiment 6 of the present invention will be described. The communication terminal according to Embodiment 6 of the present invention converts a CIR value into a codeword having a code length that is longer as the value of the higher digit is transmitted.

  FIG. 14 is a block diagram showing a configuration of a communication terminal according to Embodiment 6 of the present invention. In the following description, the same components as those in FIG. 11 are denoted by the same reference numerals as those in FIG.

  In FIG. 14, CIR signal creation section 1101 creates a CIR signal by converting the CIR value measured by CIR measurement section 219 into a codeword, and outputs the created CIR signal to multiplexing section 210. At this time, the CIR signal creation unit 1101 creates a CIR signal by converting the code length of the CIR value to a codeword having a code length that is longer as the higher digit value.

  Next, the configuration of the CIR signal creation unit 1101 will be described. FIG. 15 is a block diagram showing a configuration of a CIR signal creation unit of a communication terminal according to Embodiment 6 of the present invention.

  In FIG. 15, upper digit information generation section 1201 outputs the value of the upper digit among the CIR values output from CIR measurement section 219 to 6-bit encoding section 1203. The lower digit information generation unit 1202 outputs the lower digit value of the CIR value output from the CIR measurement unit 219 to the 4-bit encoding unit 1204. Specifically, for example, when the CIR value output from the CIR measurement unit 219 is 8.7 dB, the upper digit information generation unit 1201 converts the value of the integer part “8” into the 6-bit encoding unit 1203. The lower-order digit information generation unit 1202 outputs the value of the decimal part “7” to the 4-bit encoding unit 1204.

  The 6-bit encoding unit 1203 converts the value (here, “8”) output from the high-order digit information generation unit 1201 into a 6-bit code word, and outputs the 6-bit code word to the time multiplexing unit 1205 To do. The 4-bit encoding unit 1204 converts the value (here, “7”) output from the low-order digit information generation unit 1202 into a 4-bit code word, and outputs the 4-bit code word to the time multiplexing unit 1205 To do. Here, it is assumed that the number of bits that can be used to indicate the CIR value is 10 bits.

  The time multiplexing unit 1205 stores a 6-bit code word in the first half of one slot, and stores a 4-bit code word in the subsequent second half, so that the code word of the integer part of the CIR value (that is, the upper bit) The code word corresponding to the digit value) and the code word of the decimal part of the CIR value (that is, the code word corresponding to the lower digit value) are time-multiplexed. Then, the time multiplexing unit 1205 outputs the time-multiplexed 10-bit codeword to the modulation unit 1206 as a CIR signal. In this example, one slot is composed of 10 bits, the integer part of the CIR value is represented by the first 6 bits, and the decimal part of the CIR value is represented by the last 4 bits.

  Modulating section 1206 modulates the CIR signal and outputs it to spreading section 1207. Spreading section 1207 spreads the output signal from modulation section 1206 and outputs the result to multiplexing section 210.

  Next, the operation of the communication terminal having the above configuration will be described.

  In the 6-bit encoding unit 1203, the value of the upper digit (here, “8”) in the CIR value is converted into a 6-bit code word. On the other hand, in the 4-bit encoding unit 1204, the lower-order digit value (here, “7”) in the CIR value is converted into a 4-bit codeword.

6 codeword type represented by the bit is 2 ^6, since the type of a code word represented by 4 bits is 2 ^4, between who codewords represented by 6 bits each codeword The minimum inter-code distance in can be made large. Therefore, a code word represented by 6 bits is less likely to be mistaken for other code words than a code word represented by 4 bits. That is, in the present embodiment, the value of the upper digit among the CIR values is less likely to be erroneous.

  As described above, the communication terminal according to the present embodiment converts the code word into a codeword having a longer code length as the upper digit value of the CIR value within the limitation of 10 bits that can be used to indicate the CIR value. The value of the upper digit having the larger change amount can be transmitted with less error. As a result, even if an error occurs in the CIR signal in the propagation path, the base station has a higher probability of being able to receive the higher-order digit value of the CIR value more accurately, and suppresses the degree of error in the CIR value. Can do. Therefore, in the base station, the possibility that an incorrect communication mode is determined can be reduced.

  In the present embodiment, it has been described that the upper digit value is converted into a 6-bit code word and the lower digit value is converted into a 4-bit code word. However, the number of bits of the code word corresponding to the value of the upper digit is not particularly limited as long as the number of bits of the code word corresponding to the value of the lower digit is larger.

(Embodiment 7)
The communication terminal according to the seventh embodiment of the present invention transmits the CIR value with a higher transmission power for the higher digit value.

  Since the communication terminal according to the present embodiment is different from the communication terminal according to Embodiment 6 only in the internal configuration of CIR signal creation section 1101, only the CIR signal creation section 1101 will be described below.

  FIG. 16 is a block diagram showing a configuration of a CIR signal creation unit of a communication terminal according to Embodiment 7 of the present invention. In the following description, the same components as those in FIG. 15 are denoted by the same reference numerals as those in FIG. 15, and detailed descriptions thereof are omitted.

  16 converts the CIR value measured by the CIR measurement unit 219 into a code word, and then creates a CIR signal by increasing the transmission power as the value of the higher digit.

  In FIG. 16, the 5-bit encoding unit 1301 converts the value output from the higher-order digit information generation unit 1201 into a 5-bit code word, and outputs the 5-bit code word to the modulation unit 1303. Also, the 5-bit encoding unit 1302 converts the value output from the lower-order digit information generation unit 1202 into a 5-bit code word, and outputs the 5-bit code word to the modulation unit 1304. As described above, in this embodiment, both the upper digit value and the lower digit value are converted into 5-bit codewords, so there is a difference in error resistance between the two in terms of codewords. Absent.

  Modulating section 1303 modulates the code word output from 5-bit encoding section 1301 and outputs the result to upper digit spreading section 1305. Modulating section 1304 modulates the code word output from 5-bit encoding section 1302 and outputs the modulated code word to lower digit spreading section 1306.

  Upper digit spreading section 1305 spreads the output signal from modulating section 1303 and outputs the result to upper digit power control section 1307. Further, the lower digit spreading section 1306 spreads the output signal from the modulation section 1304 and outputs it to the lower digit power control section 1308. At this time, the upper digit spreading section 1305 and the lower digit spreading section 1306 perform spreading processing using spreading codes of the same spreading factor but different types. That is, the upper digit value and the lower digit value of the CIR value are spread by different types of spreading codes having the same spreading factor.

  The upper digit power control unit 1307 controls transmission power of a signal indicating the value of the upper digit of the CIR value based on the transmission power of the pilot signal output from the pilot power control unit 209, and the signal after transmission power control Is output to the code multiplexer 1309. Also, the lower digit power control unit 1308 controls the transmission power of the signal indicating the lower digit value of the CIR value based on the transmission power of the pilot signal output from the pilot power control unit 209, and after the transmission power control Are output to the code multiplexer 1309. A specific method for controlling the transmission power will be described later.

  The code multiplexing unit 1309 multiplexes the signal indicating the upper digit value of the CIR value and the signal indicating the lower digit value in the same time zone. That is, the code multiplexing unit 1309 code-multiplexes the signal indicating the value of the upper digit and the signal indicating the value of the lower digit.

  Next, the operation of the communication terminal having the above configuration will be described.

  In the upper digit power control section 1307, the signal indicating the value of the upper digit of the CIR value is controlled to a transmission power that is higher by a predetermined value than the transmission power of the pilot signal. Also, in the lower digit power control unit 1308, the signal indicating the lower digit value of the CIR value is controlled to a transmission power that is lower by a predetermined value than the transmission power of the pilot signal. That is, the higher the value of the CIR value, the higher the transmission power.

  As described above, the communication terminal according to the present embodiment transmits the CIR value by increasing the transmission power as the value of the upper digit increases, so that the value of the upper digit having the larger change amount is less likely to be erroneous. can do. As a result, even if an error occurs in the CIR signal in the propagation path, the base station has a higher probability of being able to receive the higher-order digit value of the CIR value more accurately, and suppresses the degree of error in the CIR value. Can do. Therefore, in the base station, the possibility that an incorrect communication mode is determined can be reduced.

  Also, in the present embodiment, compared to the conventional CIR signal transmission power (that is, the pilot signal transmission power here), the transmission power is increased for the upper digit value, and the lower digit value is set. The transmission power of the entire CIR signal is kept the same as the transmission power of the conventional CIR signal by lowering the transmission power by the amount higher for the upper digit value and setting the total increase / decrease value of the transmission power to ± 0 dB. I did it. Therefore, according to the present embodiment, it is possible to transmit the CIR signal with less error as the higher digit value while keeping the transmission power of the CIR signal the same as the conventional one. In other words, it is possible to transmit with less significant error as the value of the upper digit without reducing the uplink capacity compared to the conventional one.

(Embodiment 8)
The communication terminal according to the eighth embodiment of the present invention spreads and transmits a CIR value with a spreading code having a higher spreading factor as the upper digit value.

  Since the communication terminal according to the present embodiment is different from the communication terminal according to Embodiments 6 and 7 only in the internal configuration of CIR signal creation section 1101, only the CIR signal creation section 1101 will be described in the following description. .

  FIG. 17 is a block diagram showing a configuration of a CIR signal creation unit of a communication terminal according to Embodiment 8 of the present invention. In the following description, the same components as those in FIG. 15 or FIG. 16 are denoted by the same reference numerals as those in FIG. 15 or FIG.

  The CIR signal generator 1101 shown in FIG. 17 converts the CIR value measured by the CIR measurement unit 219 into a code word, and then generates a CIR signal by spreading the higher digit value with a spreading code having a higher spreading factor. .

  In FIG. 17, upper digit spreading section 1401 spreads the output signal from modulating section 1303 and outputs it to time multiplexing section 1205. Also, the lower digit spreading section 1402 spreads the output signal from the modulation section 1304 and outputs it to the time multiplexing section 1205. At this time, the upper digit spreading section 1401 performs spreading processing with a spreading code of the same type as that used by the lower digit spreading section 1402 and a spreading factor higher than the spreading factor in the lower digit spreading section 1402. That is, the upper digit value of the CIR value is spread with a higher spreading factor than the lower digit value. As a result, the higher digit value is less likely to be erroneous in the propagation path.

  As described above, the communication terminal according to the present embodiment transmits the CIR value by increasing the spreading factor as the value of the higher digit, and thereby transmitting the value of the higher digit having the larger change amount so that the error is less likely to occur. can do. As a result, even if an error occurs in the CIR signal in the propagation path, the base station has a higher probability of being able to receive the higher-order digit value of the CIR value more accurately, and suppresses the degree of error in the CIR value. Can do. Therefore, in the base station, the possibility that an incorrect communication mode is determined can be reduced.

  Also, in this embodiment, the spreading factor is increased by the amount that is higher for the upper digit value and the lower digit value is higher for the higher digit value than the conventional CIR signal spreading factor. Lower. In this way, the amount of data that can be sent in one slot is kept equal to the conventional CIR signal. Therefore, according to the present embodiment, it is possible to transmit with less significant errors as the value of the upper digit without reducing the amount of data that can be transmitted in one slot.

  Note that the communication terminal according to Embodiment 1 and the communication terminal according to Embodiment 2 may be combined. In addition, the communication terminal according to the fourth embodiment and the communication terminal according to the fifth embodiment can be combined. It is also possible to implement a combination of the communication terminals according to Embodiments 6 to 8 described above. In addition, the transmission power table included in the communication terminal according to the fourth embodiment and the codeword table included in the communication terminal according to the fifth embodiment are used as control signals from the base station in the same manner as in the third embodiment. It is also possible to rewrite as appropriate based on this.

  In the first to eighth embodiments, the case where the pilot signal is time-multiplexed has been described. However, the first to eighth embodiments are not limited to this, and the case where the pilot signal is code-multiplexed is also described. Applicable.

  In the first to eighth embodiments, the CIR is used as a value indicating the reception quality of the pilot signal. However, the present invention is not limited to this, and any value can be used as long as it indicates the reception quality. .

  In the first to fifth embodiments, the predetermined threshold values set in the unused DRC detection unit and the unused CIR detection unit are fixed values. However, the error rate of the DRC signal and the error rate of the CIR signal The threshold value may be adaptively changed accordingly.

  In Embodiments 6 to 8, when codewords are multiplexed, they may be multiplexed using either time multiplexing or code multiplexing.

  Moreover, in the said Embodiments 6-8, the CIR value represented by the integer part 1 digit and the decimal part 1 digit was mentioned as an example, and was demonstrated. However, the present invention is not limited to this, and the sixth to eighth embodiments can be implemented for all CIR values represented by a plurality of digits.

  In the sixth to eighth embodiments, the value of the upper digit of the CIR value is described as “information with a large amount of change”. However, “information with a large amount of change” does not necessarily correspond to the digit size. For example, first, a value that changes by 2 dB is shown as a rough value such as 0 dB, 2 dB, 4 dB, 6 dB, and the like. In the case of taking it, a value that changes by 2 dB becomes “information with a large change amount”. In this method, for example, when a CIR value of 7 dB is represented, a CIR signal including two pieces of information, that is, information indicating 6 dB and information indicating that there is an increase of 1 dB is transmitted to the base station. At this time, the communication terminal apparatus transmits information indicating 6 dB with less error than information indicating that there is an increase of 1 dB in the same manner as in the sixth to eighth embodiments.

101, 704 Allocation unit 102 Buffer 103 Adaptive encoding unit 104 Adaptive modulation unit 105, 107, 204, 208, 704, 504, 707, 803, 1004 Spreading unit 106, 203, 207, 403, 503, 706, 802, 1003 Modulation unit 108, 210 Multiplexing unit 113, 215, 218, 601 Despreading unit 114, 602, 701 Demodulation unit 115, 702 Reception power calculation unit 116, 302 Unused DRC detection unit 201, 705 Communication mode determination unit 202 DRC signal generation Unit 205 DRC power control unit 206, 805 transmission power table 209 pilot power control unit 216 adaptive demodulation unit 217 adaptive decoding unit 219 CIR measurement unit 301, 901 likelihood calculation unit 401, 1001 code word selection unit 402, 1002 code word table 501 Detection rate calculation unit 5 2 Control signal creation unit 603 Table rewrite unit 703, 902 Unused CIR detection unit 801 CIR information creation unit 804 CIR information power control unit 1101 CIR signal creation unit 1201 Upper digit information generation unit 1202 Lower digit information generation unit 1203 6-bit encoding Unit 1204 4-bit encoding unit 1305, 1401 upper digit spreading unit 1306, 1402 lower digit spreading unit 1307 upper digit power control unit 1308 lower digit power control unit

Claims (6)

Measuring means for measuring the reception quality of the received pilot signal;
Encoding means for encoding the information indicating the reception quality;
Transmitting means for transmitting the encoded information,
The information is composed of a plurality of bits,
The encoding means encodes the information such that the most significant bit among the plurality of bits is less likely to be erroneous.
Transmitter device. The information indicates a modulation scheme and a transmission rate set based on the reception quality.
The transmission device according to claim 1. Transmitting means for transmitting a pilot signal;
Receiving means for receiving information indicating the reception quality of the pilot signal,
The information is composed of a plurality of bits, and is encoded such that the most significant bit among the plurality of bits is less likely to be erroneous.
Receiver device. Scheduling means for performing scheduling based on the received information;
The receiving device according to claim 3. The information indicates a modulation scheme and a transmission rate set based on the reception quality,
Control means for controlling a modulation scheme and a transmission rate based on the received information;
The receiving device according to claim 4. A transmitter that measures reception quality of a received pilot signal, encodes information indicating the reception quality, and transmits the encoded information;
A receiving device that transmits the pilot signal and receives information indicating reception quality of the pilot signal;
The information is composed of a plurality of bits,
The transmitting device encodes the information such that the most significant bit among the plurality of bits is less likely to be erroneous.
Wireless communication system.

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