JP2006166382A - Wireless receiver, wireless communication system, channel estimation method and computer program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wireless receiver capable of improving the precision of channel estimation without increasing the power of a pilot signal. <P>SOLUTION: In a receiver 10p, a reception conversion unit 11 receives a frame including timewise-spread transmission data, two-dimensionally spread control data and a pilot signal. A channel estimation unit 1 reads out the pilot signal from the received frame, calculates a first channel estimate based on the read pilot signal and a source pilot signal at the time of transmission corresponding to the read pilot signal, and reproduces the control data based on the calculated first channel estimate. A replica generation unit 20 generates a replica of the control data by two-dimensionally spreading the control data again. A channel estimation unit 15 calculates a second channel estimate based on the replica of the control data and reproduces the transmission data based on the calculated second channel estimate. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a radio receiver, a radio communication system, and a channel estimation method for improving channel estimation accuracy of orthogonal frequency division multiplexing / code division multiplexing (OFDM-CDM) in a mobile communication system. And a computer program.

  In recent years, due to the development of mobile communication systems, further broadband, higher frequency and higher reliability have been demanded. When transmitting low-rate data and control data, or when transmitting in an environment where other cell interference is severe In addition, it is known as an effective means to use the OFDM-CDM system. In the OFDM-CDM system, when transmission / reception is performed, the channel response changes depending on the characteristics of the transmission path. Therefore, a known pilot signal is included in the transmission signal and transmitted. Based on this, channel response estimation (hereinafter referred to as channel estimation) for estimating the channel characteristics is performed. By using the characteristics of the transmission path obtained by the channel estimation and receiving the data that should be originally transmitted / received, it is possible to reproduce the original transmission data by applying the inverse characteristics to equalize the data.

  Hereinafter, conventional channel estimation using a pilot signal will be described with reference to FIGS. There are two types of channel estimation methods using pilot signals, depending on the pilot signal transmission method. The first method is a time multiplexing method that multiplexes pilot signals on the time axis, and the second method is a code multiplexing method that spreads pilot signals with spreading codes and multiplexes them on the spreading code axes. (Refer nonpatent literature 1).

  First, a method of time multiplexing pilot signals will be described with reference to FIGS. FIG. 9 is a block configuration diagram of a transmitter 50c that multiplexes and transmits pilot signals to control data and transmission data. In the transmitter 50c, the data channel units 51-1 to 51-n (hereinafter, representatively referred to as the data channel unit 51) perform conversion based on the OFDM-CDM system on transmission data that is information to be transmitted. . Further, the control channel unit 60 controls the control data necessary for reproducing the data on the receiving side, such as the modulation method for modulating the transmission data, the coding rate for encoding, the packet number of the transmission data, etc. Conversion based on the OFDM-CDM system is performed.

  In the data channel unit 51, the error correction encoder 52 gives an error correction code to the input transmission data. The modulation mapping unit 53 maps the transmission data on the transmission signal output from the error correction encoder 52 to the modulation signal by a modulation scheme such as QPSK (Quadrature Phase Shift Keying), and generates a symbol. A serial / parallel converter (S / P) 55 performs serial / parallel conversion on the symbols output from the modulation mapping unit 53 and assigns the symbols to each subcarrier. The time direction spreading unit 56 spreads the symbols assigned to each subcarrier in the time direction using a preset spread signal to generate a spreading chip.

  In the control channel 60, the error correction encoder 61 gives an error correction code to the input control data. The modulation mapping unit 62 maps the control data to the modulation signal with respect to the transmission signal output from the error correction encoder 61 by a modulation method such as QPSK, and generates a symbol. The serial / parallel converter 64 performs serial / parallel conversion on the symbols output from the modulation mapping unit 62 and assigns each symbol to a two-dimensional spreading segment. The two-dimensional spreading unit 65 uses a spreading code set in advance to two-dimensionally spread symbols assigned to spreading segments in the time direction and the frequency direction to generate a spreading chip.

Here, diffusion will be described with reference to FIG. In FIG. 10, a symbol 90 indicates one symbol output from the serial / parallel converter 64. By performing two-dimensional spreading on the symbol 90, the symbol 90 is spread in the time direction and the frequency direction. In FIG. 10, one symbol 90 is spread to 8 symbols in the time direction and spread to 4 symbols in the frequency direction, so that it is spread to 32 symbols as a whole. At this time, if the spreading factor in the time direction is SF _Time and the spreading factor in the frequency direction is SF _Freq , the spreading factor SF is expressed as SF = SF _Time × SF _Freq . Then, it is assigned to one subcarrier in units of spreading chips spread in the time direction.

  Next, the code multiplexer 57 in FIG. 9 code-multiplexes the spreading chip output from the data channel unit 51 and the spreading chip output from the control channel unit 60 on the spreading code axis. The time multiplexer 80 time-multiplexes the pilot signal with respect to the transmission frame output from the code multiplexer 57 on the time axis. The conversion transmission unit 59 performs inverse fast Fourier transform (hereinafter referred to as IFFT) on the transmission frame output from the time multiplexer 80, and guard interval (GI: Guard Interval) to avoid intersymbol interference. ) Is inserted, and a radio wave including a transmission frame is transmitted via the transmission antenna 70.

  FIG. 11 is a diagram showing a transmission frame when pilot signals are time-multiplexed. In FIG. 11, the transmission data and the control data are code-multiplexed, but the pilot signal is time-multiplexed with respect to the control data and the transmission data, and is assigned to a different time slot from the control data and the transmission data. Thus, there is an advantage that there is no intersymbol interference from subcarriers of control data and transmission data.

FIG. 12 is a block diagram showing an internal configuration of a receiver 10c that receives a frame in which a pilot signal transmitted from the transmitter 50c of FIG. 9 is time-multiplexed. The reception conversion unit 11 converts a time-domain signal received by the reception antenna into a reception subcarrier signal by Fast Fourier Transform (FFT: First Fourier Transform). The channel estimation unit 12 reads a received pilot signal that is time-multiplexed with the received subcarrier signal, and calculates a channel estimation value by using the pilot signal that is time-multiplexed in the transmitter 50c (hereinafter referred to as an original pilot signal). . At this time, r is the received subcarrier signal, and the channel response is h, and the pilot signal is s ₁ , as shown in Equation (1).

Next, an estimated value ^ h of the channel response can be calculated by Equation (2) using the input original pilot signal s ₁ and its complex conjugate s ₁ ^* .

In Expression (2), s ₁ is known because it is the original pilot signal used at the time of transmission, and an estimated value of the channel response h can be calculated. Next, when the data signal s ₂ is received, the reception subcarrier signal r can be calculated by Expression (3).

Then, to remove the modulation component by multiplying the complex conjugate h ^* estimate of the channel response h calculated by the formula (2), the estimated value ^ s ₂ of s _2, be calculated by Equation (4) it can.

  When a plurality of pilot signals are used, the channel estimation value is calculated by averaging the channel estimation values calculated for each pilot signal.

  The two-dimensional despreading unit 13 estimates the received subcarrier signal using the channel estimation value calculated from the pilot signal. Further, the two-dimensional despreading unit 13 further performs two-dimensional despreading on the received subcarrier signal estimated by the spreading code used when two-dimensional spreading of the control data in the transmitter 50c, and performs other code multiplexing. The reception control data is read while suppressing the received signal. The error correction decoder 14 decodes the error correction code of the reception control data output from the two-dimensional despreading unit 13 and reproduces the control data.

  The time direction despreading unit 17 despreads in the time direction based on the spreading code used when the transmission data is spread in the time direction in the transmitter 50c and the spreading factor included in the reproduced control data. I do. The equalizer 18 restores the transmission data in a state including the error correction code based on the channel estimation value calculated by the channel estimation unit 12 and the modulation multi-level number included in the reproduced control data. To do. The error correction decoder 19 decodes the error correction code of the restored transmission data based on the coding rate included in the reproduced control data, and reproduces the transmission data.

  Next, a method of code multiplexing pilot signals will be described with reference to FIGS. FIG. 13 is a block diagram showing an internal configuration of the transmitter 50d when the pilot signal is code-multiplexed. About the same block as FIG. 9, the same code | symbol as FIG. 9 is attached | subjected, description is abbreviate | omitted, and only a different location is demonstrated. In the transmitter 50d, in order to code-multiplex the pilot signal, the pilot signal is first spread in the time direction, and the code multiplexer 57 codes the transmission data, the control data, and the pilot signal on the spreading code axis. Multiplex.

  FIG. 14 is a diagram illustrating a transmission frame when the pilot signal is code-multiplexed. In FIG. 14, the pilot signal is spread in the time direction, and is code-multiplexed with respect to the transmission data spread in the time direction and the control data spread in two dimensions. Transmission data and control data are included. Therefore, even if there is a temporal variation in the channel response, the channel estimation value calculated from the pilot signal subjected to the variation is used for the reproduction of control data and transmission data subjected to the same variation. There is an advantage that followability is improved.

FIG. 15 is a block diagram showing an internal configuration of a receiver 10d that receives a signal in which a pilot signal transmitted from the transmitter 50d in FIG. 13 is code-multiplexed. The same blocks as those in FIG. 12 are denoted by the same reference numerals as those in FIG. In FIG. 15, a time-spread pilot signal is code-multiplexed with the reception subcarrier signal output from the reception conversion unit 11. The time-direction despreading unit 30 despreads the received subcarrier signal in the time direction with the spreading code used when the pilot signal is spread in the time direction by the transmitter 50d, and receives other code-multiplexed signals. Suppress and read pilot signal. The procedure for calculating the channel estimation value using the pilot signal code-multiplexed at the time of transmission, that is, the original pilot signal, is performed by the same procedure as in FIG.
Kishiyama, Maeda, Shin, Sawahashi, “Examination of pilot channel configuration in VSF-OFCDM” IEICE Technical Report RCS2002-169, pp19-24, October 2002

  By the way, in the channel estimation method using the pilot signal as described above, in order to improve the accuracy of channel estimation, conventionally, the signal power of the pilot signal is increased. However, the total signal power to be transmitted is limited to a certain value, and if the pilot signal power is increased, the ratio of the pilot signal power to the total transmission power increases, and the power of the data portion decreases, resulting in transmission. There is a problem that quality deteriorates. Also, if the power of the data portion is increased to improve the accuracy of the data portion, and the power of the pilot signal is decreased, the accuracy of the channel estimation deteriorates, and the data portion is equalized by the channel estimation value whose accuracy has deteriorated, When error correction or the like is performed, there is a problem that transmission quality is deteriorated as a whole.

  The present invention has been made to solve the above problems, and an object of the present invention is to provide a radio receiver, a channel estimation method, and a computer program capable of improving the accuracy of channel estimation without increasing the power of a pilot signal. It is to provide.

  In order to solve the above-described problem, the present invention includes transmission data spread in the time direction using a first spreading code, control data spread two-dimensionally using a second spreading code, and a pilot signal. A receiving means for receiving a frame transmitted from a wireless transmitter of a CDM communication system, a received pilot signal is read out from the frame received by the receiving means, and a received pilot signal is read out based on the read received pilot signal and the pilot signal. Control data based on first channel estimation means for calculating one channel estimation value, the first channel estimation value calculated by the first channel estimation means, and the second spreading code. Control data reproducing means for reproducing the control data and the control data reproduced by the control data reproducing means again for the second diffusion Replica generating means for generating a replica of the control data by performing two-dimensional spreading based on the signal, and a second channel estimation value based on the replica of the control data generated by the replica generating means Channel estimation means, transmission data reproduction means for reproducing the transmission data based on the second channel estimation value calculated by the second channel estimation means, and the first spreading code. A wireless receiver characterized by the above.

  The present invention is the above invention, wherein the pilot signal is time-multiplexed with respect to transmission data spread in the time direction and the control data spread two-dimensionally, and the first channel estimation means includes the reception Reading a received pilot signal time-multiplexed from the frame received by the means, calculating a first channel estimation value based on the read received pilot signal and the pilot signal, the transmission data recovery means, A channel estimated value obtained by averaging the first channel estimated value and the second channel estimated value is calculated, and the transmission data is reproduced based on the averaged channel estimated value and the first spreading code. It is characterized by that.

  In the present invention according to the above invention, the pilot signal is spread in the time direction by a third spreading code, and is code-multiplexed on the transmission data spread in the time direction and the control channel spread in two dimensions. And the first channel estimation means reads out the received pilot signal from the frame received by the receiving means by the third spreading code, and based on the read received pilot signal and the pilot signal, 1 channel estimation value is calculated, and the second channel estimation means generates a combined signal obtained by combining the replica of the control data generated by the replica generation unit and the pilot signal, and reproduces the transmission data. The means calculates the second channel estimation value based on the combined signal, and calculates the calculated second channel estimation value. , Characterized in that for reproducing the transmission data based on the first spread signal.

  The present invention relates to transmission data that is time-space-spread and space-time coded with a first spreading code, control data that is two-dimensionally spread and space-time coded with a second spreading code, and a plurality of pilot signals And receiving means for receiving a frame transmitted from a wireless transmitter having a plurality of transmitting antennas by an OFDM-CDM communication system, and reading out a plurality of received pilot signals from the frame received by the receiving means First channel estimation means for calculating a first channel estimation value based on the plurality of received pilot signals and the plurality of pilot signals corresponding to each of the plurality of received pilot signals; The reception control data is read out by the spreading code of the first channel, and the read reception control data is read out from the first channel. First space-time decoding means for space-time decoding based on the estimated value, and decoded data decoded by the space-time decoding means are combined in the frequency direction, and the combined combined decoded data is again the second spread A replica generating means for generating a replica of the control data by performing two-dimensional spreading with a code and space-time encoding; and a second channel estimation value based on the replica of the control data generated by the replica generating means Based on the second channel estimation means to be calculated, the second channel estimation value calculated by the second channel estimation means, and the first spreading code, the transmission data is space-time decoded and the transmission A wireless receiver comprising transmission data reproducing means for reproducing data.

  The present invention provides a radio communication system including a radio transmitter that transmits radio waves according to an OFDM-CDM communication system and a radio receiver that receives the radio waves, wherein the radio transmitter transmits transmission data as a first data. Means for spreading in the time direction with a spreading code; means for spreading the control data two-dimensionally with a second spreading code; the transmission data spread in the time direction; the control data spread in two dimensions; and a pilot signal. Means for multiplexing and generating a frame and transmitting a radio wave including the frame, wherein the radio receiver receives the frame included in the radio wave transmitted from the radio transmitter. And a received pilot signal read from the frame received by the receiving means, and the read received pilot signal, and the pilot First channel estimation means for calculating a first channel estimation value based on the first signal, the first channel estimation value calculated by the first channel estimation means, and the second spreading code. Based on the control data reproduction means for reproducing the control data, and replicating the control data by two-dimensionally spreading the control data reproduced by the control data reproduction means again based on the second spreading code. Calculated by the replica generating means to be generated, the second channel estimating means for calculating the second channel estimation value based on the replica of the control data generated by the replica generating means, and the second channel estimating means Transmission data reproducing means for reproducing the transmission data based on the second channel estimation value and the first spreading code; A wireless communication system characterized by comprising.

  The present invention relates to a wireless communication system including a plurality of transmission antennas, a wireless transmitter that transmits radio waves from the plurality of transmission antennas according to an OFDM-CDM communication system, and a radio receiver that receives the radio waves. The wireless transmitter includes: means for spreading the transmission data in the time direction using a first spreading code; means for spreading the control data in a two-dimensional manner using the second spreading code; Means for multiplexing the dimension-spread control data and a plurality of pilot signals set for each transmission antenna to generate a frame, and transmitting radio waves including the frame from the plurality of transmission antennas; The wireless receiver includes a receiving unit that receives a frame included in the radio wave transmitted from the wireless transmitter; and the receiving unit Thus, a plurality of received pilot signals are read from the received frame, and the first channel estimation value is based on the read received pilot signals and the pilot signals corresponding to the received pilot signals. First channel estimation means for calculating reception control data from the frame by the second spreading code, and the read reception control data is subjected to space-time decoding based on the first channel estimation value 1 space-time decoding means and the decoded data decoded by the space-time decoding means are synthesized in the frequency direction, and the synthesized synthesized decoded data is again two-dimensionally spread by the second spreading code, The replica generating means for generating a replica of the control data, and the replica generating means Second channel estimation means for calculating a second channel estimation value based on the generated replica of the control data, the second channel estimation value calculated by the second channel estimation means, A wireless communication system comprising: transmission data reproducing means for reproducing the transmission data by space-time decoding the transmission data based on one spreading code.

  The present invention includes transmission data spread in the time direction using a first spreading code, control data two-dimensionally spread using a second spreading code, and a pilot signal, and transmitted from a radio transmitter of the OFDM-CDM communication system. Receiving a received frame, reading a received pilot signal from the received frame, calculating a first channel estimation value based on the read received pilot signal and the pilot signal, and calculating the calculated first The step of reproducing the control data based on the channel estimation value of 1 and the second spreading code, and the two-dimensional spreading of the reproduced control data again based on the second spreading code Generating a replica of the control data; and second channel estimation based on the generated replica of the control data. Calculating a value, and the calculated second channel estimation value, on the basis the first spreading code is a channel estimation method characterized by comprising the steps of: reproducing the transmission data.

  The present invention relates to transmission data that is time-space-spread and space-time coded with a first spreading code, control data that is two-dimensionally spread and space-time coded with a second spreading code, and a plurality of pilot signals Including a step of receiving a frame transmitted from a radio transmitter having a plurality of transmission antennas by an OFDM-CDM communication system, and reading out a plurality of received pilot signals from the received frame and reading the plurality of received pilot signals And calculating a first channel estimation value based on the plurality of pilot signals corresponding to each of the plurality of received pilot signals, and reading out and reading out reception control data from the frame by the second spreading code The reception control data is subjected to space-time decoding based on the first channel estimation value. And generating a replica of the control data by synthesizing the decoded decoded data in the frequency direction, two-dimensionally spreading the synthesized combined decoded data again by the second spreading code, and space-time coding; Calculating a second channel estimation value based on the generated replica of the control data; space-time decoding the transmission data based on the calculated second channel estimation value and the first spreading code; And regenerating the transmission data. A channel estimation method comprising:

The present invention includes an OFDM-CDM communication that includes transmission data spread in the time direction using a first spreading code, control data two-dimensionally spread using a second spreading code, and a pilot signal in a computer of a radio receiver. Of receiving a frame transmitted from a wireless transmitter of a method, reading a received pilot signal from the received frame, and calculating a first channel estimation value based on the read received pilot signal and the pilot signal Procedure and
A procedure for reproducing the control data based on the calculated first channel estimation value and the second spreading code, and a two-dimensional spreading of the reproduced control data again based on the second spreading code. Generating a replica of the control data, calculating a second channel estimation value based on the generated replica of the control data, calculating the second channel estimation value, and the first And a procedure for reproducing the transmission data on the basis of the spread code.

  The present invention relates to a control method in which a transmitter of a wireless receiver is time-space-spreaded by a first spreading code and space-time coded transmission data and two-dimensionally spread by a second spreading code and space-time coded. A procedure for receiving a frame including data and a plurality of pilot signals transmitted from a wireless transmitter having a plurality of transmitting antennas according to an OFDM-CDM communication method, and reading and reading a plurality of received pilot signals from the received frames In addition, a procedure for calculating a first channel estimation value based on the plurality of received pilot signals and the plurality of pilot signals corresponding to the plurality of received pilot signals, and a second spreading code from the frame Read reception control data, and read the reception control data based on the first channel estimation value The procedure of space-time decoding, the decoded decoded data is synthesized in the frequency direction, the synthesized synthesized decoded data is again two-dimensionally spread by the second spreading code, and space-time coding is performed, thereby replicating the control data. A step of generating, a step of calculating a second channel estimation value based on the generated replica of the control data, the transmission based on the calculated second channel estimation value, and the first spreading code. And a procedure for reproducing the transmission data by space-time decoding the data.

  According to this invention, the radio receiver includes transmission data spread in the time direction by the first spreading code, control data spread two-dimensionally by the second spreading code, and a pilot signal, and performs OFDM-CDM communication. A frame transmitted from a wireless transmitter of the scheme is received. A received pilot signal is read from the received frame, and a first channel estimation value is calculated based on the read received pilot signal and the pilot signal. Control data is reproduced based on the calculated first channel estimation value and the second spreading code. The reproduced control data is again two-dimensionally spread based on the second spreading code to generate a control data replica. The second channel estimation value is calculated based on the generated replica of the control data, and the transmission data is reproduced based on the calculated second channel estimation value and the first spreading code. This increases the signal power for channel estimation by regenerating a highly reliable control channel that is normally assigned a large amount of signal power and performing channel estimation using the regenerated control channel and pilot signal. Thus, channel estimation accuracy can be improved.

  In the radio receiver of the present invention, the pilot signal is time-multiplexed with respect to the transmission data spread in the time direction and the control data spread in two dimensions, and the received pilot is time-multiplexed from the received frame. A signal is read, a first channel estimation value is calculated based on the read received pilot signal and the pilot signal, and a channel estimation value obtained by averaging the calculated first channel estimation value and second channel estimation value is calculated. The transmission data is reproduced based on the calculated and averaged channel estimation value and the first spreading code. Thus, the channel estimation value calculated based on the pilot signal and the channel estimation value calculated based on the replica of the control data are weighted according to the pilot signal power and the signal power of the control data and averaged. become. In addition, since the channel estimation is usually performed using control data having a signal power larger than that of the pilot signal, the estimation accuracy can be improved.

  In the radio receiver of the present invention, the pilot signal is spread in the time direction by a third spreading code, and is code-multiplexed with respect to the transmission data spread in the time direction and the control channel spread in two dimensions. The received pilot signal is read from the received frame by the third spreading code, and the first channel estimation value is calculated based on the read received pilot signal and the pilot signal. A synthesized signal obtained by synthesizing the generated replica of the control data and the pilot signal is generated, and a second channel estimation value is calculated based on the generated synthesized signal. The transmission data is reproduced based on the calculated second channel estimation value and the first spread signal. As a result, the channel estimation value is calculated from the combined signal generated from the pilot signal and the replica of the control data. Further, the signal power of the control data is added to the signal power of the pilot signal, so that channel estimation using a larger signal power can be performed, and the estimation accuracy can be improved.

  The radio receiver of the present invention also includes transmission data that is time-space-spreaded by the first spreading code and space-time coded, and control data that is two-dimensionally spread by the second spreading code and space-time coded. And a frame transmitted from a wireless transmitter having a plurality of transmission antennas by the OFDM-CDM communication method. A plurality of received pilot signals are read from the received frame, and a first channel estimation value is calculated based on the read plurality of received pilot signals and a plurality of pilot signals corresponding to the plurality of received pilot signals. Reception control data is read from the frame by the second spreading code, and the read reception control data is spatiotemporally decoded based on the first channel estimation value. The decoded decoded data is synthesized in the frequency direction, and the synthesized synthesized decoded data is again two-dimensionally spread by the second spreading code, and space-time coded, thereby generating a replica of the control data. Based on the generated replica of the control data, a second channel estimation value is calculated, and based on the calculated second channel estimation value and the first spreading code, the transmission data is space-time decoded to reproduce the transmission data. It was set as the structure to do. Accordingly, it is possible to apply a transmission diversity scheme in which frames are transmitted from a plurality of transmission antennas, and it is possible to perform channel estimation based on a pilot signal in a state where transmission quality is improved by the transmission diversity scheme.

(First embodiment)
Hereinafter, a receiver according to a first embodiment of a wireless receiver of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic block diagram showing a receiver 10p that reproduces transmission data when pilot signals are time-multiplexed in the first embodiment.
The receiver 10p shown in FIG. 1 receives the transmission frame in which the pilot signal transmitted from the transmitter 50c of FIG. 9 described above is time-multiplexed, and reproduces the transmission data. In the receiver 10p of FIG. 1, the same blocks as those of the receiver 10c illustrated in FIG. 12 are denoted by the same reference numerals, description thereof is omitted, and differences from the receiver 10c will be described below.

  In the receiver 10p, the replica generation unit 20 is reproduced by using the channel estimation value calculated by the channel estimation unit 12 based on the received pilot signal and the original pilot signal added to the transmission frame by the transmitter 50c. A copy of the control data before being code-multiplexed at the time of transmission, that is, a replica is generated from the control data. In the replica generation unit 20, the re-error correction encoder 21 performs the same error encoding as that at the time of transmission on the reproduced control data. The re-modulation mapping unit 22 maps the control data output from the re-error correction encoder 21 to the modulation signal using the same modulation method as that used for transmission, and generates symbols. The re-two-dimensional spreading unit 23 performs serial-parallel conversion on the symbols output from the re-modulation mapping unit 22 and assigns each symbol to a two-dimensional spreading segment. Further, the re-two-dimensional spreading unit 23 uses a spreading code used when two-dimensionally spreading the control data when transmitting the symbols assigned to the spreading segment when transmitting the two-dimensionally in the time direction and the frequency direction. A replica of the control data before spreading and code multiplexing is generated.

  The channel estimation unit 15 reads out the control data code-multiplexed on the reception subcarrier signal output from the reception conversion unit 11 with the spreading code used when the control data is two-dimensionally spread at the time of transmission, and the replica generation unit The channel estimation value is calculated based on the replica of the control data output from 20 and the reception control data. The averager 16 uses the channel estimation value calculated by the channel estimation unit 12 based on the pilot signal and the channel estimation value calculated by the channel estimation unit 15 based on the replica of the control data on the pilot signal power and the control data signal. Perform weighting according to power and average. The equalizer 18 is despread by the time-direction despreading unit 17 so that information corresponding to transmission data read from the received subcarrier signal, a channel estimation value output from the averager 16, and Transmission data including an error correction code is restored based on the modulation multi-level number included in the reproduced control data. The error correction decoder 19 performs error correction decoding on the restored transmission data to reproduce the transmission data.

  With the configuration of FIG. 1, the channel estimation value calculated based on the pilot signal and the channel estimation value calculated based on the replica of the control data are weighted according to the pilot signal power and the power value of the signal power of the control data. Go and average. Therefore, the estimation accuracy can be improved because channel estimation is normally performed using control data having a signal power larger than that of the pilot signal.

  FIG. 2 is a schematic block diagram showing a receiver 10q that reproduces transmission data when pilot signals are code-multiplexed in the first embodiment.

  The receiver 10q shown in FIG. 2 receives the transmission frame in which the pilot signal transmitted from the transmitter 50d of FIG. 13 described above is code-multiplexed, and reproduces the transmission data. In the receiver 10q of FIG. 2, the same blocks as those of the receiver 10d shown in FIG. 15 are denoted by the same reference numerals, description thereof is omitted, and differences from the receiver 10d will be described below.

  In the receiver 10q, the replica generation unit 20 uses the channel estimation value calculated by the channel estimation unit 12 based on the received pilot signal and the original pilot signal, and generates a replica of the control data from the reproduced control data. . In the replica generation unit 20, the re-error correction encoder 21 performs the same error encoding as that at the time of transmission on the reproduced control data. The re-modulation mapping unit 22 maps the control data to the modulation signal by the same modulation method as that at the time of transmission with respect to the transmission signal output from the re-error correction encoder 21, and generates a symbol. The re-two-dimensional spreading unit 23 performs serial-parallel conversion on the symbols output from the re-modulation mapping unit 22 and assigns each symbol to a two-dimensional spreading segment. In addition, the re-two-dimensional spreading unit 23 performs two-dimensional spreading in the time direction and the frequency direction by using a spreading code used when two-dimensional spreading of control data during transmission of symbols assigned to the spreading segment. A replica of the control data before code multiplexing is generated.

  The composite signal generation unit 31 spreads the original pilot signal in the time direction by the spreading code used when the pilot signal is spread in the time direction at the time of transmission, and outputs the spread original pilot signal and the replica generation unit 20 A synthesized signal is generated by synthesizing the control data replica.

  The channel estimation unit 32 reads out the control data and pilot signal code-multiplexed on the subcarrier signal output from the reception conversion unit 11 using respective spreading codes, and reads out the control data and pilot signal and the combined signal generation unit 31. Channel estimation is performed based on the combined signal generated by the above, and a channel estimation value is calculated. The equalizer 18 is despread by the time direction despreading unit 17, thereby transmitting data read from the subcarrier signal, a channel estimation value output from the channel estimation unit 32, and reproduced control data. The transmission data in a state including the error correction code is restored based on the modulation multi-level number included in. The error correction decoder 19 performs error correction decoding on the restored transmission data and reproduces the transmission data.

  With the configuration of FIG. 2, the channel estimation value is calculated from the combined signal generated from the pilot signal and the control data replica. Therefore, the signal power of the control data is added to the signal power of the pilot signal, and a larger signal power is used. Therefore, the estimation accuracy can be improved.

(Second Embodiment)
Next, as a second embodiment of the wireless receiver of the present invention, a receiver that applies transmission diversity schemes that transmit transmission data from two transmission antennas and reproduces transmission data using a pilot signal will be described.

First, a method using a time-multiplexed pilot signal to which the transmission diversity method is applied will be described with reference to FIGS.
FIG. 3 is a block diagram of a transmitter 50c that time-multiplexes and transmits pilot signals in the second embodiment. In the transmitter 50a of FIG. 3, the same blocks as those of the transmitter 50c of FIG. 9 are denoted by the same reference numerals, description thereof is omitted, and differences from the transmitter 50c will be described below.

First, in the configuration of the pilot channel in the transmission diversity method, the transmission signal is encoded so that the signals transmitted from the two transmission antennas 70a and 70b can be distinguished on the reception side. Then, with two symbols as one pair, [s ₁ , s ₂ ] is transmitted at a certain time t = 1, and [s ₁ , −s ₂ ] is transmitted at the next time t = 2. To do. That is, the transmission antenna 70a multiplies the code [1, 1] by s ₁ that is a pilot symbol for the transmission antenna 70a, and the transmission antenna 70b is orthogonal to the code [1, 1] of the transmission antenna 70a. The code [1, −1] is multiplied by s ₂ which is a pilot symbol for the transmission antenna 70b, and transmitted. At this time, the reception subcarrier received at the reception side at time t = 1 and the reception subcarrier at time t = 2 are expressed by Expression (5).

Here, h ₁ and h ₂ are the channel response of the transmission antenna 70a and the channel response of the transmission antenna 70b, respectively. S ₁ and s ₂ for inputting the original pilot signal on the receiving side in the case of the pilot signal is known, the channel estimation value ^ h ₁ of h _1, a channel estimation value ^ h ₂ of h ₂ formula ( 6).

The channel responses h ₁ and h ₂ for the two transmission antennas 70a and 70b calculated in this way are used for decoding the space-time code, and the estimated values ^ s ₁ and ^ s ₂ of the transmission data are calculated. To do.

Next, in the data channel unit 51 of FIG. 3, the space-time encoder 54 space-time codes the modulated symbol output from the modulation mapping unit 53. Here, the space-time encoding performed by the space-time encoder 54 is to encode time-domain transmission data, that is, transmission symbols, using a 2-by-2 space-time encoding matrix. The space-time coding matrix for the transmission signal [s ₁ , s ₂ ] with 2 symbols as a pair is expressed by the following equation (7).

Space-time code symbol s ₁ is assigned to a claw of the subcarriers transmitted from the transmitting antenna 70a (the sub-carrier # 1), the following sub-space-time coded symbols -s ₂ ^* is transmitted from the transmitting antenna 70a Assigned to a carrier (subcarrier # 2). On the other hand, the space-time code symbol s ₂ is assigned to the first subcarrier (subcarrier # 1) transmitted from the transmission antenna 70b, and the space-time code symbol s ₁ ^* is transmitted from the transmission antenna 70b. Allocated to subcarrier (subcarrier # 2). After the space-time code symbol is assigned to the subcarrier, the frequency domain signal is converted into a time domain signal by inverse fast Fourier transform and transmitted from the transmission antennas 70a and 70b.

On the other hand, on the receiving side, fast Fourier transform is performed on the received signal to convert it into a subcarrier signal. Received subcarrier signals r ₁ and r _{2 in} subcarriers # 1 and # 2 after conversion are expressed by the following equations (8), respectively.

Here, h _{i, m} is a channel response from the transmission antenna i to the receiver in the subcarrier m. Which transmission antenna is the received signal is determined based on the pilot signal included in the signal, and the transmission signal is estimated by the following equation (9) based on the channel estimation value obtained from the pilot signal.

When the development of Expression (9) is advanced, the following Expression (10) is obtained.

Here, the estimated value ^ s ₁ of the obtained transmission signal and the second term in ^ s ₂ are generated when the orthogonality of space-time decoding collapses when the channel responses are different between subcarriers # 1 and # 2. It is an interference component. This interference component is suppressed as the accuracy of the channel estimation value based on the pilot signal is higher, and becomes a component that can be ignored.

  Next, in FIG. 3, the serial-parallel converters 55a and 55b perform serial-parallel conversion on symbols corresponding to transmission data transmitted from the two transmission antennas 70a and 70b output from the space-time encoder 54. Do. The time direction spreading unit 56 performs time direction spreading on the symbols output from the serial / parallel converters 55a and 55b to generate a spreading chip.

  In the control channel 60, the space-time encoder 63 performs the space-time encoding described above on the control data. The serial / parallel converters 64a and 64b perform serial / parallel conversion on symbols corresponding to control data transmitted from the two transmission antennas 70a and 70b output from the space-time encoder 54. The secondary spreading unit 65 performs two-dimensional spreading on the symbols output from the serial / parallel converters 64a and 65b to generate a spreading chip.

  The code multiplexers 57a and 57b perform code multiplexing on the spreading chips corresponding to the two transmission antennas 70a and 70b output from the data channel unit 51 and the control channel 60 so as to correspond to the transmission antennas 70a and 70b. The time multiplexers 58a and 58b time-multiplex pilot signals corresponding to the transmission antennas 70a and 70b with respect to the frames output from the two code multiplexers 57a and 57b. The conversion transmitters 59a and 59b perform IFFT on the frames output from the two time multiplexers 58a and 58b, insert GIs, and transmit the radio waves from the transmission antennas 70a and 70b.

  FIG. 4 is a diagram showing a transmission frame when the transmission diversity method is applied and the pilot signal is time-multiplexed. The two pilot signals are time-multiplexed with respect to transmission data and control data, and the two pilot signals are code-multiplexed. With this configuration, the two pilot signals are assigned to different time slots from the control data and the transmission data, and there is an advantage that there is no intersymbol interference from the subcarriers of the control data and the transmission data.

  FIG. 5 is a block diagram showing an internal configuration of the receiver 10a that receives transmission data transmitted from the transmitter 50a of FIG. 3 and reproduces the transmission data. In FIG. 5, the same blocks as those of the receiver 10 c illustrated in FIG. 12 are denoted by the same reference numerals, description thereof is omitted, and differences from the receiver 10 c will be described below.

  In FIG. 5, the channel estimation unit 12a and the channel estimation unit 12b are configured to read a reception pilot signal from reception subcarriers received by the reception conversion unit 11 from the transmission antennas 70a and 70b. A channel estimation value is calculated based on the original pilot signal time-multiplexed corresponding to 70a and the original pilot signal time-multiplexed corresponding to transmitting antenna 70b.

  The time direction despreading unit 43 performs despreading only in the time direction using the spreading code used when two-dimensionally spreading the control data. The space-time code decoder 40 performs space-time decoding of the symbols output from the time-direction despreading unit 43 based on the channel estimation values calculated by the channel estimation units 12 a and 12 b. The frequency direction synthesis unit 41 synthesizes the data space-time decoded by the space-time code decoder 40 in the frequency direction based on the channel estimation values calculated by the channel estimation units 12a and 12b, and performs error correction. The control data including the code is restored. The error correction decoder 14 performs error correction decoding on the restored control data and reproduces the control data.

  The replica generation unit 20 generates a replica of control data before being code-multiplexed at the time of transmission from the reproduced control data. In the replica generation unit 20, the re-error correction encoder 21 performs the same error encoding as that at the time of transmission on the reproduced control data. The re-modulation mapping unit 22 maps the control data output from the re-error correction encoder 21 to the modulation signal using the same modulation method as that used for transmission, and generates symbols. The re-space-time encoder 24 performs space-time coding on the symbols output from the remodulation mapping unit 22 and outputs the space-time encoded symbols. The re-two-dimensional spreading units 23a and 23b perform serial-parallel conversion on the symbols output from the re-space-time encoder 24, and assign the two symbols subjected to the serial-parallel conversion to the two-dimensional spreading segment. In addition, the re-two-dimensional spreading units 23a and 23b are two-dimensionally arranged in the time direction and the frequency direction by using a spreading code used for two-dimensional spreading of control data when transmitting the symbols assigned to the spreading segments. A replica of the control data before spreading and code multiplexing is generated.

  The channel estimation unit 15a reads out the control data code-multiplexed on the received subcarrier signal received by the reception conversion unit 11 from the transmission antenna 70a by despreading, and outputs it from the re-two-dimensional spreading unit 23a of the replica generation unit 20 Channel estimation is performed using a replica of the control data thus obtained, and a channel estimation value is calculated. Similarly, the channel estimation unit 15b reads out the control data that is code-multiplexed on the reception subcarrier signal received from the transmission antenna 70b by the reception conversion unit 11 by despreading, and re-two-dimensional spreading unit 23b of the replica generation unit 20 The channel response is estimated using the replica of the control data output from, and the channel estimation value is calculated.

  The averager 16 uses the channel estimation value calculated by the channel estimation units 12a and 12b based on the pilot signal and the channel estimation value calculated by the channel estimation units 15a and 15b based on the replica of the control data as the pilot signal. Weighting is performed according to the power value of the power and the signal power of the control data, and averaged.

  The time-direction despreading units 17a and 17b are time-dependently determined by the spreading codes used when the reception conversion unit 11 has spread from the transmission antennas 70a and 70b in the time direction with respect to the respective reception subcarrier signals. The information corresponding to the transmission data is read by despreading in the direction. The space-time code decoder 42 includes two pieces of information corresponding to the transmission data read from the received subcarrier signals by the time direction despreading units 17a and 17b, the channel estimation value output from the averager 16, and the reproduction The transmission data including the error correction code is reproduced based on the modulation multi-level number included in the control data. The error correction decoder 19 performs error correction and reproduces transmission data.

  With the configuration of FIG. 5, transmission quality is improved by the transmission diversity method. Further, the channel estimation value calculated based on the pilot signal and the channel estimation value calculated based on the control data replica are averaged by weighting according to the pilot signal power and the signal power of the control data. Therefore, the estimation accuracy can be improved because channel estimation is usually performed using control data having a signal power larger than that of the pilot signal.

  In addition, since the pilot signal is time-multiplexed with respect to the transmission data and the control data is code-multiplexed, when the terminal moving speed is fast and the channel fluctuation is fast, the control calculated by the control data replica is used. By using only the channel estimation value of the data for decoding the transmission data, it is possible to improve the followability to the channel time variation.

  Next, with reference to FIGS. 6 to 8, a description will be given of a scheme that uses a code-multiplexed pilot signal in the transmission diversity scheme.

  FIG. 6 is a block diagram of a transmitter 50b that transmits time-multiplexed pilot signals in the second embodiment. In the transmitter 50b of FIG. 6, the same blocks as those of the transmitter 50d of FIG. 13 are denoted by the same reference numerals, description thereof is omitted, and differences from the transmitter 50d will be described below. In the data channel unit 51 of FIG. 6, the space-time encoder 54 space-time codes the modulated symbol output from the modulation mapping unit 53.

  The serial-parallel converters 55a and 55b perform serial-parallel conversion on symbols corresponding to transmission data transmitted from the two transmission antennas 70a and 70b output from the space-time encoder 54. The time direction spreading unit 56 performs time direction spreading on the symbols output from the serial / parallel converters 55a and 55b to generate a spreading chip.

  In the control channel 60, the space-time encoder 63 performs the space-time encoding described above on the control data. The serial / parallel converters 64a and 64b perform serial / parallel conversion on symbols corresponding to control data transmitted from the two transmission antennas 70a and 70b output from the space-time encoder 54. The secondary spreading unit 65 performs two-dimensional spreading on the symbols output from the serial / parallel converters 64a and 64b to generate a spreading chip.

  The code multiplexers 57a and 57b perform code multiplexing so that the spreading chips corresponding to the two transmission antennas 70a and 70b output from the data channel unit 51 and the control channel 60 correspond to the transmission antennas 70a and 70b, Generate a frame. Further, the code multiplexers 57a and 57b generate a frame obtained by code-multiplexing a pilot signal spread in the time direction on a frame in which control data and transmission data are code-multiplexed. The conversion transmitters 59a and 59b perform IFFT on the frames output from the two code multiplexers 57a and 57b, respectively, insert GIs, and transmit the radio waves from the transmission antennas 70a and 70b.

  FIG. 7 is a diagram showing a transmission frame when the transmission diversity method is applied and two pilot signals are code-multiplexed. In FIG. 7, two pilot signals, transmission data, and control data are included in one subcarrier, and even if there is a temporal variation in the channel response, it is calculated from the pilot signal that has undergone the variation. The channel estimation value thus used is used for reproduction of control data and transmission data subjected to the same fluctuation, and thus there is an advantage that time followability is improved.

  FIG. 8 is a block diagram showing an internal configuration of the receiver 10b that receives transmission data transmitted from the transmitter 50b of FIG. 6 and reproduces the transmission data. In FIG. 8, the same blocks as those of the receiver 10d shown in FIG. 15 are denoted by the same reference numerals, description thereof is omitted, and differences from the receiver 10d will be described below.

  In FIG. 8, time-direction despreading units 30a and 30b read out pilot signals from the respective reception subcarrier signals received by the reception conversion unit 11 from the transmission antennas 70a and 70b using spread codes obtained by spreading the pilot signals during transmission. . Channel estimation units 12a and 12b calculate channel estimation values based on the two received pilot signals output from time direction despreading units 30a and 30b and the two original pilot signals used at the time of transmission.

  The time-direction despreading unit 43 performs despreading only in the time direction by using a spreading code used when two-dimensionally spreading control data during transmission. The space-time code decoder 40 decodes the symbols output from the time-direction despreading unit 43 based on the channel estimation values calculated by the channel estimation units 12a and 12b. The frequency direction synthesis unit 41 synthesizes the data space-time decoded by the space-time code decoder 40 in the frequency direction based on the channel estimation values calculated by the channel estimation units 12a and 12b, and performs error correction. The control data including the code is reproduced. The error correction decoder 14 decodes the data output from the frequency direction synthesizer 41 and reproduces the control data.

  The replica generation unit 20 generates a replica of the control data before being code-multiplexed at the time of transmission, that is, a replica, from the reproduced control data. In the replica generation unit 20, the re-error correction encoder 21 performs the same error encoding as that at the time of transmission on the reproduced control data. The re-modulation mapping unit 22 maps the control data output from the re-error correction encoder 21 to the modulation signal using the same modulation method as that used for transmission, and generates symbols. The re-space-time encoder 24 performs space-time coding on the modulated symbols, and outputs space-time encoded symbols that form one pair of two symbols. The re-two-dimensional spreading units 23a and 23b perform serial-parallel conversion on the symbols output from the re-space-time encoder 24, and assign the symbols subjected to the serial-parallel conversion to the two-dimensional spreading segments. In addition, the re-two-dimensional spreading units 23a and 23b are two-dimensionally arranged in the time direction and the frequency direction by using a spreading code used for two-dimensional spreading of control data when transmitting the symbols assigned to the spreading segments. Two replicas of control data before spreading and code multiplexing are generated.

  The combined signal generators 31a and 31b spread the original pilot signal in the time direction by the spreading code used when the pilot signal is spread in the time direction at the time of transmission, the two original pilot signals spread, and the replica generator A synthesized signal is generated by synthesizing two replicas of the two control data output from 20.

  The channel estimators 32a and 32b read out the control data and the pilot signal code-multiplexed on the received subcarrier signal output from the reception converter 11 based on the respective spreading codes, and the combined signal generators 31a and 31b A channel estimation value is calculated based on the generated combined signal. The time-direction despreading units 17a and 17b are time-dependently determined by the spreading codes used when the reception conversion unit 11 has spread from the transmission antennas 70a and 70b in the time direction with respect to the respective reception subcarrier signals. Information of two transmission data corresponding to the transmission antennas 70a and 70b is read out by despreading in the direction.

  The space-time code decoder 42 includes information corresponding to the two transmission data read from the received subcarrier signals by the time direction despreading units 17a and 17b, and channel estimation values output from the channel estimation units 32a and 32b. And space-time decoding based on the modulation multi-level number included in the reproduced control data to restore transmission data including an error correction code. The error correction decoder 19 performs error correction decoding on the restored transmission data and reproduces the transmission data.

  With the configuration of FIG. 8, transmission quality is improved by the transmission diversity method. Furthermore, since the channel estimation value is calculated from the composite signal generated from the pilot signal and the replica of the control data, the signal power of the control data is added to the signal power of the pilot signal, and channel estimation using a larger signal power is performed. Since this can be done, the estimation accuracy can be improved.

  With the above-described configuration, the power per spreading code for the control data channel is set larger than that for the transmission data channel, and further spread in the frequency direction, thereby improving reliability by increasing the power for the control channel. In addition, reliability is improved by frequency diversity gain due to frequency direction spreading. By reproducing the control data of this highly reliable control channel and performing channel estimation using the regenerated control channel and pilot signal, the signal power for channel estimation can be increased and the channel estimation accuracy is improved. It becomes possible.

  In the configuration described above, when a plurality of pilot signals are used, the channel estimation values calculated based on each pilot signal are added and averaged.

  In the second embodiment described above, the case where two transmission antennas are used as the transmission diversity method has been described. However, the present invention is not limited to this configuration, and can be realized even when there are two or more transmission antennas. It is possible to do.

  The wireless communication system described above is a wireless communication system configured by the receiver 10p of FIG. 1 and the transmitter 50c of FIG. 9, and a wireless communication system configured by the receiver 10q of FIG. 2 and the transmitter 50d of FIG. This corresponds to a communication system, a wireless communication system constituted by the transmitter 50a in FIG. 3 and the receiver 10a in FIG. 5, and a wireless communication system constituted by the transmitter 50b in FIG. 6 and the receiver 10b in FIG.

  The receivers 10a, 10b, 10p, and 10q described above have a computer system inside. The transmission data reproduction process described above is stored in a computer-readable recording medium in the form of a program, and the above process is performed by the computer reading and executing this program. Here, the computer-readable recording medium means a magnetic disk, a magneto-optical disk, a CD-ROM, a DVD-ROM, a semiconductor memory, or the like. Alternatively, the computer program may be distributed to the computer via a communication line, and the computer that has received the distribution may execute the program.

It is the block diagram which showed the internal structure of the receiver in case the pilot signal by 1st Embodiment is time-multiplexed. It is the block diagram which showed the internal structure of the receiver in case the pilot signal by 1st Embodiment is code-multiplexed. It is the block diagram which showed the internal structure of the transmitter which time-multiplexes the pilot signal by 2nd Embodiment. It is a figure which shows the structure of the transmission frame in case the pilot signal by 2nd Embodiment is time-multiplexed. It is the block diagram which showed the internal structure of the receiver in case the pilot signal by 2nd Embodiment is time-multiplexed. It is the block diagram which showed the internal structure of the transmitter which code-multiplexes the pilot signal by 2nd Embodiment. It is a figure which shows the structure of the transmission frame in case the pilot signal by 2nd Embodiment is code-multiplexed. It is the block diagram which showed the internal structure of the receiver in case the pilot signal by 2nd Embodiment is code-multiplexed. It is the block diagram which showed the internal structure of the transmitter which time-multiplexes a pilot signal in the prior art. It is a figure for demonstrating the system of the two-dimensional diffusion in a prior art. It is the figure which showed the structure of the transmission frame at the time of the time division multiplexing of the pilot signal in a prior art. It is the block diagram which showed the internal structure of the receiver in case the pilot signal in the prior art is time-multiplexed. It is the block diagram which showed the internal structure of the transmitter which code-multiplexes a pilot signal in the prior art. It is a figure which shows the structure of the transmission frame in case the pilot signal by 2nd Embodiment is code-multiplexed. It is the block diagram which showed the internal structure of the receiver in case the pilot signal by 2nd Embodiment is code-multiplexed.

Explanation of symbols

10p receiver 11 reception conversion unit 12 channel estimation unit 13 two-dimensional despreading unit 20 replica generation unit 15 channel estimation unit 18 equalizer

Claims (10)

A frame transmitted from a wireless transmitter of the OFDM-CDM communication system, including transmission data spread in the time direction by the first spreading code, control data two-dimensionally spread by the second spreading code, and a pilot signal. Receiving means for receiving;
First channel estimation means for reading a received pilot signal from the frame received by the receiving means, and calculating a first channel estimation value based on the read received pilot signal and the pilot signal;
Control data reproduction means for reproducing the control data based on the first channel estimation value calculated by the first channel estimation means and the second spreading code;
Replica generating means for generating a replica of the control data by two-dimensionally spreading the control data reproduced by the control data reproducing means again based on the second spreading code;
Second channel estimation means for calculating a second channel estimation value based on the replica of the control data generated by the replica generation means;
Transmission data reproduction means for reproducing the transmission data based on the second channel estimation value calculated by the second channel estimation means and the first spreading code;
A wireless receiver comprising: The pilot signal is time-multiplexed with respect to transmission data spread in the time direction and the control data spread in two dimensions.
The first channel estimation means includes:
Reading a received pilot signal time-multiplexed from the frame received by the receiving means, calculating a first channel estimation value based on the read received pilot signal and the pilot signal,
The transmission data reproducing means includes
A channel estimated value obtained by averaging the first channel estimated value and the second channel estimated value is calculated, and the transmission data is reproduced based on the averaged channel estimated value and the first spreading code. The wireless receiver according to claim 1. The pilot signal is spread in the time direction by a third spreading code, and is code-multiplexed with respect to the transmission data that has been spread in the time direction and the control channel that has been two-dimensionally spread.
The first channel estimation means includes:
From the frame received by the receiving means, a received pilot signal is read by the third spreading code, a first channel estimation value is calculated based on the read received pilot signal and the pilot signal,
The second channel estimation means includes:
Generating a composite signal obtained by combining the replica of the control data generated by the replica generation unit and the pilot signal;
The transmission data reproducing means includes
The second channel estimation value is calculated based on the combined signal, and the transmission data is reproduced based on the calculated second channel estimation value and the first spread signal. The wireless receiver according to 1. OFDM including transmission data that is time-space-spread and space-time coded by the first spreading code, control data that is two-dimensionally spread and space-time coded by the second spreading code, and a plurality of pilot signals A receiving means for receiving a frame transmitted from a wireless transmitter having a plurality of transmitting antennas by a CDM communication method;
A plurality of received pilot signals are read out from the frame received by the receiving means, and a plurality of received pilot signals are read out based on the read out plurality of received pilot signals and the plurality of pilot signals corresponding to the plurality of received pilot signals. First channel estimation means for calculating a channel estimation value;
First space-time decoding means for reading reception control data from the frame by the second spreading code, and for space-time decoding the read reception control data based on the first channel estimation value;
The decoded data decoded by the space-time decoding means is synthesized in the frequency direction, and the synthesized synthesized decoded data is again two-dimensionally spread by the second spreading code and is subjected to space-time coding, thereby replicating the control data. Replica generating means for generating
Second channel estimation means for calculating a second channel estimation value based on the replica of the control data generated by the replica generation means;
Transmission data reproduction means for space-time decoding the transmission data and reproducing the transmission data based on the second channel estimation value calculated by the second channel estimation means and the first spreading code;
A wireless receiver comprising: In a wireless communication system including a wireless transmitter that transmits a radio wave according to an OFDM-CDM communication system, and a radio receiver that receives the radio wave,
The wireless transmitter is
Means for spreading the transmission data in the time direction by the first spreading code;
Means for two-dimensionally spreading control data with a second spreading code;
Means for multiplexing the transmission data that has been spread in the time direction, the control data that has been two-dimensionally spread, and a pilot signal, generating a frame, and transmitting a radio wave including the frame;
The wireless receiver
Receiving means for receiving the frame included in the radio wave transmitted from the radio transmitter;
First channel estimation means for reading a received pilot signal from the frame received by the receiving means, and calculating a first channel estimation value based on the read received pilot signal and the pilot signal;
Control data reproduction means for reproducing the control data based on the first channel estimation value calculated by the first channel estimation means and the second spreading code;
Replica generating means for generating a replica of the control data by two-dimensionally spreading the control data reproduced by the control data reproducing means again based on the second spreading code;
Second channel estimation means for calculating a second channel estimation value based on the replica of the control data generated by the replica generation means;
Transmission data reproduction means for reproducing the transmission data based on the second channel estimation value calculated by the second channel estimation means and the first spreading code;
A wireless communication system comprising: In a wireless communication system including a plurality of transmission antennas, a wireless transmitter that transmits radio waves from the plurality of transmission antennas according to an OFDM-CDM communication system, and a radio receiver that receives the radio waves,
The wireless transmitter is
Means for spreading the transmission data in the time direction by the first spreading code;
Means for two-dimensionally spreading control data with a second spreading code;
The transmission data spread in the time direction, the control data spread in two dimensions, and a plurality of pilot signals set for each of the transmission antennas are multiplexed to generate a frame, and the radio wave including the frame is Means for transmitting from a plurality of transmitting antennas;
With
The wireless receiver
Receiving means for receiving a frame included in the radio wave transmitted from the radio transmitter;
A plurality of received pilot signals are read out from the frame received by the receiving means, and a plurality of received pilot signals are read out based on the read out plurality of received pilot signals and the plurality of pilot signals corresponding to the plurality of received pilot signals. First channel estimation means for calculating a channel estimation value;
First space-time decoding means for reading reception control data from the frame by the second spreading code, and for space-time decoding the read reception control data based on the first channel estimation value;
The decoded data decoded by the space-time decoding means is synthesized in the frequency direction, and the synthesized synthesized decoded data is again two-dimensionally spread by the second spreading code and is subjected to space-time coding, thereby replicating the control data. Replica generating means for generating
Second channel estimation means for calculating a second channel estimation value based on the replica of the control data generated by the replica generation means;
Transmission data reproduction means for space-time decoding the transmission data and reproducing the transmission data based on the second channel estimation value calculated by the second channel estimation means and the first spreading code;
A wireless communication system comprising: A frame transmitted from a wireless transmitter of the OFDM-CDM communication system, including transmission data spread in the time direction by the first spreading code, control data two-dimensionally spread by the second spreading code, and a pilot signal. Receiving step;
Reading a received pilot signal from the received frame, calculating a first channel estimate based on the read received pilot signal and the pilot signal;
Regenerating the control data based on the calculated first channel estimation value and the second spreading code;
Generating a replica of the control data by two-dimensionally spreading the reproduced control data again based on the second spreading code;
Calculating a second channel estimate based on the generated replica of the control data;
Regenerating the transmission data based on the calculated second channel estimation value and the first spreading code;
A channel estimation method characterized by comprising: OFDM including transmission data that is time-space-spread and space-time coded by the first spreading code, control data that is two-dimensionally spread and space-time coded by the second spreading code, and a plurality of pilot signals Receiving a frame transmitted from a wireless transmitter having a plurality of transmission antennas by a CDM communication method;
A plurality of received pilot signals are read from the received frame, and a first channel estimation value is calculated based on the read plurality of received pilot signals and the plurality of pilot signals corresponding to the plurality of received pilot signals. And steps to
Reading reception control data from the frame by the second spreading code, and space-time decoding the read reception control data based on the first channel estimation value;
Synthesizing the decoded decoded data in the frequency direction, two-dimensionally spreading the synthesized combined decoded data again by the second spreading code, and generating a control data replica by space-time coding;
Calculating a second channel estimate based on the generated replica of the control data;
Based on the calculated second channel estimation value and the first spreading code, space-time decoding the transmission data to reproduce the transmission data;
A channel estimation method comprising: To the wireless receiver computer,
A frame transmitted from a wireless transmitter of the OFDM-CDM communication system, including transmission data spread in the time direction by the first spreading code, control data two-dimensionally spread by the second spreading code, and a pilot signal. The procedure to receive,
A procedure for reading a received pilot signal from the received frame and calculating a first channel estimation value based on the read received pilot signal and the pilot signal;
Replaying the control data based on the calculated first channel estimation value and the second spreading code;
Generating a replica of the control data by two-dimensionally spreading the reproduced control data again based on the second spreading code;
Calculating a second channel estimate based on the generated replica of the control data;
Replaying the transmission data based on the calculated second channel estimation value and the first spreading code;
A computer program for running. To the wireless receiver computer,
OFDM including transmission data that is time-space-spread and space-time coded by the first spreading code, control data that is two-dimensionally spread and space-time coded by the second spreading code, and a plurality of pilot signals A procedure for receiving a frame transmitted from a wireless transmitter having a plurality of transmission antennas by a CDM communication method;
A plurality of received pilot signals are read from the received frame, and a first channel estimation value is calculated based on the read plurality of received pilot signals and the plurality of pilot signals corresponding to the plurality of received pilot signals. And the steps to
A step of reading reception control data from the frame by the second spreading code and space-time decoding the read reception control data based on the first channel estimation value;
A procedure of generating a replica of the control data by synthesizing the decoded decoded data in the frequency direction, two-dimensionally spreading the synthesized combined decoded data again by the second spreading code, and space-time coding;
Calculating a second channel estimate based on the generated replica of the control data;
A step of space-time decoding the transmission data based on the calculated second channel estimation value and the first spreading code to reproduce the transmission data;
A computer program for running.

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