A wireless transceiver and wireless transmitting/receiving method and program thereof

The present invention relates to a wireless transmitter / receiver to which a transmission / reception diversity using a space-time code is applied in a mobile communication system, a wireless transmission / reception method, and a program thereof.

[0002] [Conventional Technology] With the recent development of mobile communication systems, further widening of bandwidth, higher frequency, and higher reliability are required. Therefore, it is known that transmission diversity technology that improves transmission quality without increasing the wireless part of the terminal is effective, and that two-dimensional diffusion that can increase the diffusion gain is effective in an environment where interference with other cells is severe. There is.

[0003] Diffusion in the time direction has been studied as a diffusion method for OFDM-CDM (see Non-Patent Documents 1 and 2). This is because in the frame format where the amplitude fluctuation in the time direction due to the Doppler frequency due to the movement of the terminal is slower than the amplitude fluctuation in the frequency direction due to the frequency selectivity of the propagation path, the diffusion in the frequency direction is more gentle than the diffusion in the time direction. This is because the orthogonality between the cords is easily broken. Also, when a large diffusion rate is required, two-dimensional diffusion is used using both time and frequency. For backdiffusion, the channel response of each subcarrier is used to compensate the amplitude and phase for each subcarrier to perform backdiffusion.

[0004] FIGS. 10 and 11 show the configurations of the radio transmitter and the radio receiver when the space-time transmission diversity is applied to this time-direction diffusion OFDM-CDM method. On the wireless transmitter side, the input of the transmission signal Ω is received, and equation (1) [Equation 1]<img file="JP3669991B2_D0001.tif" />Two coded streams [s₁, -s₂^*], [S₂, s₁^*] Is output to each of the antenna branches # 1 and # 2. On the antenna branch # 1 side, the coded stream [s₁, -s₂^*] Is received, and one local user signal spreading code is used, as shown in FIG.₁, -S₂^*Are diffused in the time direction. At this time, s₁Is time slot 1, -s₂^*Is assigned to time slot 2 which is later than time slot 1 in terms of time. That is, the space-time coded signals of two different time slots are spread by the same one local user signal spreading code. Also, on the antenna branch # 2, the coded stream [s₂, s₁^*] Is received, and the same local user signal diffusion code is used as in the case of the antenna branch # 1 side.₂, s₁^*Are diffused in the time direction. At this time, s₂Is time slot 1, s₁^*Is assigned to the time slot 2 which is later than the time slot 1 in terms of time, as in the case of the antenna branch # 1 side. That is, similarly to the antenna branch # 1 side, the space-time coded signals of two different time slots are spread by the same one local user signal spreading code. Next, on each of the antenna branch # 1 side and the # 2 side, the user signal diffused in the time direction by the own user signal spreading code and another user signal obtained in the same manner are multiplexed. Further, the user signal multiplexed with the other user signal and the pilot signal stored in advance on the wireless transmitter side and the wireless receiver side are multiplexed. In addition, the user signal in which the pilot signal is multiplexed is converted into a time domain signal by IFFT, and a guard interval is added. Then, the antennas of the antenna branches # 1 and # 2 simultaneously radiate the output signal after the addition of the guard interval.

[0005] Therefore, in a conventional wireless transmitter, when the time-space transmission diversity is applied to the frame format, as described above, the space-time coded output shown in FIG. 12 is divided into two continuous diffusion regions (= two) in the time direction. It will be assigned to a different time slot). On the other hand, in the wireless receiver, the antennas of the antenna branches # 1 and # 2 receive the signals radiated from the antennas of the antenna branches # 1 and # 2 on the wireless transmitter side, and the time direction despreader and the channel estimation. Output to the container. The channel estimator estimates the channel response from the received signal received by the antenna using the pilot signal stored in advance. On the other hand, the time direction despreader subtracts the pilot signal from the received signal and despreads two different time slots in order using the own user signal spreading code. And the space-time decoder is on channel h₁, H₂In response to the input of the channel estimation value of, the decrypted signal is obtained by performing space-time decoding in the space-time coded signal of two time slots that are continuous in the time direction of the despreaded signal dediffused in the time direction despreader. obtain.

[0006] [Non-Patent Document 1] Hitoshi Chung, Masao Nakagawa "System characteristics of OFDM-CDMA using transmission diversity in downlink" Institute of Electronics, Information and Communication Engineers, Communication Science and Technology Bulletin Radio Communication System Study Group RCS2000-184 (2000) January) [Non-Patent Document 2] Kenichi Miyoshi, Atsushi Matsumoto, Mitsuru Uesugi "Study on temporal diffusion in FCDM" Institute of Electronics, Information and Communication Engineers, Communication Science and Technology Bulletin Radio Communication System Study Group RCS2001-179 (November 2001) [0007] [Problems to be Solved by the Invention] In the above-mentioned conventional example, in order to perform spreading coding using the same own user signal spreading code between space-time coded signals of different time slots. , The own user signal spreading code is used to despread two different time slots in order. Therefore, the channel response for each symbol cannot be obtained in the reverse diffusion in the time direction. Therefore, the despreading in the wireless receiver is the despreading of equal gain synthesis using only the own user signal diffusing code. Therefore, in order to maintain the orthogonality between the codes, there is a problem that the diffusion rate is limited to the extent that it is not affected by the fluctuation in the time direction. Further, when applying the time-spatial transmission diversity, for example, if a space-time coding matrix of 2 rows and 2 columns is used, the two symbols output in the time direction are diffused into two diffusion regions in the time direction. Further, in the space-time code, the channel response needs to be time-invariant with the time slot lengths of a plurality of symbols output in the time direction. For this reason, it is necessary to design the two diffusion regions so that they are not affected by time fluctuations, and if the requirements for the design become more stringent, or if the two diffusion regions are affected by time fluctuations, transmission is performed. There was a problem that the characteristics deteriorated.

[0008] The present invention has been made in consideration of such circumstances, and an object of the present invention is to accommodate a coded output for transmission diversity in one diffusion region and improve the yield strength against Doppler frequencies. It is an object of the present invention to provide a wireless transmitter / receiver, a wireless transmission / reception method, and a program thereof.

[Means for Solving the Problems] The present invention has been made to solve the above problems, and the invention according to claim 1 is a code for encoding a transmission signal using a space-time coding matrix. Means of conversion<u style="single">(For example, the space-time encoder 4 described in the embodiment described later)</u>And the spreading means for spreading the space-time coded signals of different time slots of the space-time coded output encoded by the coding means using different spreading codes.<u style="single">(For example, the diffusers 11-1 to 11-2n described in the embodiment described later)</u>And the diffusion signal diffused by the diffusion means<u style="single">, Multiple means for multiplexing in the same time slot constituting the diffusion segment (for example, own user signal multipliers 12-1 to 12-n described in the embodiment described later) and the diffusion signal multiplexed by the multiplexing means.</u>Transmission means to send<u style="single">(For example, the antenna 16 described in the embodiment described later) and</u>It is characterized by having.

[0010] Further, according to the second aspect of the present invention, in the wireless transmitter according to the first aspect, the spreading means uses the space-time coded signals of different time slots of the space-time coded output and different spreading codes. It is characterized by using and diffusing in the time direction.

[0011] Further, according to the third aspect of the present invention, in the wireless transmitter according to the first aspect, the spreading means uses the space-time coded signals of different time slots of the space-time coded output and different spreading codes. It is characterized in that it diffuses in the time direction and the frequency direction.

[0013] In addition,<u style="single">Claim 4</u>In the invention described in the invention, space-time coded signals of different time slots of space-time coded outputs encoded using a space-time coded matrix are spread using different spread codes.<u style="single">And multiplex in the same time slot that constitutes the diffusion segment</u>Receiving means for receiving the spread signal<u style="single">(For example, the antenna 36 described in the embodiment described later)</u>And the despreading means that despreads a predetermined time slot of the spreading signal received by the receiving means by using the spreading code corresponding to the time slot.<u style="single">(For example, the reverse diffusers 31-1 to 31-2n and the reverse diffusers 37-1 to 37-2n described in the embodiments described later).</u>When,<u style="single">Channel response estimation means (for example, channel estimators 38-1 to be described in the embodiment described later) for estimating the channel response for each symbol in the same time slot constituting the diffusion segment from the signal back-spread by the spreading means (for example, channel estimators 38-1 to described in the embodiment described later). 38-2n) and the above</u>The space-time coding matrix of the signal despread by the despreading means<u style="single">And the channel response for each symbol</u>Decoding means to decode using<u style="single">(For example, the space-time decoders 24-1 to 24-n described in the embodiment described later).</u>It is characterized by having.

[0014] In addition,<u style="single">Claim 5</u>In the invention described in the present invention, spatiotemporal coded signals of different time slots of spatiotemporal coded outputs encoded using a spatiotemporal coded matrix are spread in the time direction using different diffusive codes.<u style="single">And multiplex in the same time slot that constitutes the diffusion segment</u>Receiving means for receiving the spread signal<u style="single">(For example, the antenna 36 described in the embodiment described later)</u>And the despreading means that despreads a predetermined time slot of the spreading signal received by the receiving means in the time direction by using the spreading code corresponding to the time slot.<u style="single">(For example, the reverse diffusers 31-1 to 31-2n and the reverse diffusers 37-1 to 37-2n described in the embodiments described later).</u>When,<u style="single">Channel response estimation means (for example, channel estimators 38-1 to be described in the embodiment described later) for estimating the channel response for each symbol in the same time slot constituting the diffusion segment from the signal back-spread by the spreading means (for example, channel estimators 38-1 to described in the embodiment described later). 38-2n) and the above</u>The space-time coding matrix of the signal despread by the despreading means<u style="single">And the channel response for each symbol</u>Decoding means to decode using<u style="single">(For example, the space-time decoders 24-1 to 24-n described in the embodiment described later).</u>It is characterized by having.

[0015] Also,<u style="single">Claim 6</u>In the invention described in the present invention, spatiotemporal coded signals of different time slots of spatiotemporal coded outputs encoded using a spatiotemporal coded matrix are spread in the time direction and the frequency direction using different diffusive codes.<u style="single">And multiplex in the same time slot that constitutes the diffusion segment</u>Receiving means for receiving the spread signal<u style="single">(For example, the antenna 36 described in the embodiment described later)</u>And the despreading means that despreads a predetermined time slot of the spreading signal received by the receiving means in the time direction by using the spreading code corresponding to the time slot.<u style="single">(For example, the reverse diffusers 31-1 to 31-2n and the reverse diffusers 37-1 to 37-2n described in the embodiments described later).</u>When,<u style="single">Channel response estimation means (for example, channel estimators 38-1 to be described in the embodiment described later) for estimating the channel response for each symbol in the same time slot constituting the diffusion segment from the signal back-spread by the spreading means (for example, channel estimators 38-1 to described in the embodiment described later). 38-2n) and the above</u>The space-time coding matrix of the signal despread by the despreading means<u style="single">And the channel response for each symbol</u>Decoding means to decode using<u style="single">(For example, the space-time decoders 24-1 to 24-n described in the embodiment described later).</u>And a synthesis means that synthesizes the signal decoded by the decoding means in the frequency direction.<u style="single">(For example, the frequency direction synthesizer 28-1 to 28-2n described in the embodiment described later).</u>It is characterized by having.

[0016] In addition,<u style="single">Claim 7</u>In the invention described in the present invention, a transmission signal is encoded using a space-time coding matrix, and space-time coded signals of different time slots of the coded space-time coded output are spread using different spreading codes, and the spread is performed. Spread signal<u style="single">, Multiplexing to the same time slot constituting the spreading segment, and multiplying the multiplexed spreading signal</u>It is characterized by transmitting.

[0017] In addition,<u style="single">Claim 8</u>In the invention described in the invention, space-time coded signals of different time slots of space-time coded outputs encoded using a space-time coded matrix are spread using different spread codes.<u style="single">And multiplex in the same time slot that constitutes the diffusion segment</u>The spread signal is received, and a predetermined time slot of the received spread signal is despread using the spread code corresponding to the time slot.<u style="single">From the despreaded signal, the channel response for each symbol in the same time slot constituting the spread segment is estimated, and the above-mentioned</u>The despreaded signal is converted into the space-time coding matrix.<u style="single">And the channel response for each symbol</u>It is characterized by decoding using.

[0018] In addition,<u style="single">Claim 9</u>In the invention described in the present invention, a coding process for encoding a transmission signal using a space-time coding matrix and a space-time coded signal having different time slots of the coded space-time coded output are spread by using different spreading codes. Diffusion processing and the diffused diffusion signal<u style="single">, Multiple processing to multiplex in the same time slot constituting the diffusion segment, and the multiplexed diffusion signal</u>It is a transmission program for causing a computer to execute a transmission process to be transmitted.

[0019] In addition,<u style="single">Claim 10</u>In the invention described in the invention, space-time coded signals of different time slots of space-time coded outputs encoded using a space-time coded matrix are spread using different spread codes.<u style="single">And multiplex in the same time slot that constitutes the diffusion segment</u>A reception process for receiving the spread signal, and a backspread process for despreading a predetermined time slot of the received spread signal using the spread code corresponding to the time slot.<u style="single">The channel response estimation process for estimating the channel response for each symbol in the same time slot constituting the diffusion segment from the despreaded signal, and the above-mentioned</u>The despreaded signal is converted into the space-time coding matrix.<u style="single">And the channel response for each symbol</u>Is a receiving program for causing a computer to execute a decoding process for decoding using the above.

[Embodiments of the Invention] First, the basic concept of the present invention will be described. 1 to 6 are explanatory diagrams of the principle of the present invention. FIG. 1 shows a configuration of an embodiment of a wireless transmitter to which the principle of the present invention is applied. As shown in FIG. 1, first, on the wireless transmitter side, the transmission symbol (= transmission signal Ω) is space-time coded using a space-time coding matrix of 2 rows and 2 columns. Here, the transmission signal Ω = [s₁, s₂] Is represented by the above equation (1). Two coded streams of this space-time coded output [s₁, -s₂^*], [S₂, s₁^*] Is output to each of the antenna branches # 1 and # 2. In each antenna branch, as shown in Fig. 2, each coded stream is first S / P converted. FIG. 2 shows the state of S / P conversion and two-dimensional diffusion in antenna branch # 2.

[0021] By S / P conversion, in antenna branch # 1, space-time coded signal s in time slot 1.₁Is input and the space-time coded signal in time slot 2 -s₂^*Is input and the space-time coded signal s₁For the diffusion code C₁, Space-time coded signal-s₂^*About C₂With (C₁ C₂)Spread. And the space-time coded signal s₁Diffuse output and space-time coded signal -s₂^*The spreading output of is code-multiplexed in the same spreading segment. Similarly, in antenna branch # 2, the space-time coded signal s in time slot 1₂Is input and the space-time coded signal s in time slot 2₁^*Is input and the space-time coded signal s₂For the diffusion code C₁, Space-time coded signal s₁^*About C₂Diffuse using. And the space-time coded signal s₂Diffusion output and space-time coded signal s₁^*The spread output of is code-multiplexed in the same spread segment. At this time, the diffusion is time-direction diffusion or time-two-dimensional diffusion in the time direction and the frequency direction shown in FIG. That is, for example, the space-time coded signal s₁When spreading in the time direction, the space-time coded signal s to multiple symbols in one subcarrier₁When spreading in the time direction and the frequency direction, the space-time coded signal s to multiple symbols in multiple subcarriers.₁To spread.

As a result, two different diffused coded signals (= s) belonging to different time slots 1 and 2 of the space-time coded output₁And s₂, -S₂^*And s₁^*) Are different diffusion codes (= C)₁, C₂), And the code-multiplexed own user signal is obtained. Next, in the same manner, the other user signal and the own user signal, which are space-time coded and spread code multiplexed, are multiplexed by another user. Next, in each subcarrier in the temporal diffusion or two-dimensional diffusion region, the diffusion code C_1、C₂Pilot signals are diffused by using a plurality of diffusion codes # 1 and # 2 for pilot signals orthogonal to the above, and the diffused pilot signal and a user signal multiplexed by another user are multiplexed. Then, the frame signal (shown in FIG. 4) generated by this is converted into a time domain signal by using a fast inverse Fourier transform (IFFT). In addition, a guard interval (GI) is added, up-converted to the carrier frequency, and transmission is performed simultaneously from both antennas of antenna branches # 1 and # 2. That is, the wireless transmitter has a diffused coded signal s.₁About diffusion code C₁The spread coded signal-s₂^*About C₂Diffused and code-multiplexed signal using, and diffused coded signal s₂About diffusion code C₁, The diffusion coded signal s₁^*About C₂It spreads using and simultaneously transmits a code-multiplexed signal.

[0023] FIGS. 5 and 6 show a configuration of an embodiment of a wireless receiver to which the principle of the present invention is applied. As shown in FIG. 5, in the wireless receiver, the diffused coded signal s via the antenna.₁About diffusion code C₁The spread coded signal-s₂^*About C₂Diffused and code-multiplexed signal using, and diffused coded signal s₂About diffusion code C₁, The diffusion coded signal s₁^*About C₂When signals that are diffused and code-multiplexed using are received at the same time, the guard interval is removed from these received signals. Then, these received signals are converted into received subcarrier signals by fast Fourier transform (FFT). Next, with respect to this received subcarrier signal, each of the plurality of pilot signal spreading codes # 1 and # 2 used for the antennas of the antenna branches # 1 and # 2 on the wireless transmitter side is used. Backdiffusion is performed by the subcarrier. Next, for the back-diffused signal, the modulation component of the pilot signal is removed, and the channel response from the antennas of the antenna branches # 1 and # 2 on the radio transmitter side is estimated. Then, a reception replica of the pilot signal from each transmitting antenna is generated using the pilot signal, the diffusion code for the pilot signal, and the obtained channel estimation value. On the other hand, the received pilot signal replica is subtracted from the Fourier transformed received subcarrier signal, and the spreading code C is applied to the received subcarrier signal obtained by subtracting this pilot signal._1、C₂Is used to reverse-diffuse in the time direction. As a result, the diffusion code C₁The signal back-spread in is channel h₁And diffuse coded signal s₁Product with and channel h₂And diffuse coded signal s₂It is represented by the sum of products with. Also, the diffusion code C₂The signal back-spread in is channel h₁And diffuse coded signal-s₂^*Product with and channel h₂And diffuse coded signal s₁It is represented by the sum of products with. Then, for two despread outputs belonging to this same time slot, the channel estimate h₁, H₂Space-time decoding is performed using. When the transmitted signal is spread in the time direction, the received signal is decoded in the wireless receiver (see FIG. 5). On the other hand, when the transmission signal is two-dimensionally diffused in the time direction and the frequency direction, the spatiotemporally decoded signal in each subcarrier is synthesized in the frequency direction, and the received signal is decoded in the wireless receiver as described above ( See Figure 6).

[0024] Therefore, in the time-space transmission diversity, the time-direction output of the space-time coding matrix is spread over a plurality of diffusion regions in the time direction, whereas in the present invention, the time-direction output of the space-time coding matrix is one. Since it is diffused by using a plurality of diffusion codes in the diffusion region, the resistance of the channel to time fluctuation is improved. Further, when two-dimensional diffusion is used, each subcarrier can partially reverse-diffuse in the time direction to perform decoding and synthesize in the frequency direction.

[0025] Hereinafter, an embodiment of the wireless transmitter and wireless receiver of the present invention will be described with reference to the drawings. FIG. 7 is a configuration diagram showing the configuration of the radio transmitter of the present embodiment in the multicarrier code division multiplexing (MC-CDM) method or the orthogonal frequency division multiple access code division multiplexing (OFDM-CDM) method. The wireless transmitter of this embodiment includes a encoder 1, a mapping device 2, an interleaver 3, a space-time encoder 4, S / P converters 5-1 and 2, and antenna branches 6-1 and 2. Consists of. The encoder 1 receives the input of the transmission data, performs error correction coding, and outputs the data to the mapping unit 2. The mapping device 2 receives the input of the transmission data after the error correction coding, maps it to the modulation constellation, and outputs it to the interleaver 3. In order to spread the burst error, the interleaver 3 receives the input of the mapped data, changes the order of the data, and outputs the data to the space-time encoder 4. The space-time encoder 4 encodes the output signal of the interleaver 3 by using the 2-by-2 orthogonal space-time coding matrix shown in the above equation (1). S / P converter 5-1,2 the output signal of the space-time encoder 4 series-parallel variations and conversion, and outputs to the antenna branches 6-1,2.

[0026] Antenna branches 6-1 (= antenna branches # 1, # 2) are S / P converters 10-1, 2 and diffusers 11-1, 2, ..., 2n (n are natural numbers, respectively). ), Own user signal multipliers 12-1, 2, ..., n, other user signal multipliers 13, pilot signal multipliers 14, and fast inverse Fourier transformers (= IFFT + GI) 15. It is composed of an antenna 16. The antenna branch 6-2 is also configured in the same manner as the antenna branch 6-1. The S / P converters 10-1 and 2 receive the output signal of the S / P converter 5-1 and assign two diffusers to each user signal, and the diffusers 11-1 and 2, 3 and 4, ..., 2n-1 or 2n, output to a set of diffusers to which a user signal is assigned.

[0027] The diffusers 11-1 and 2, 3 and 4, ..., 2n-1 and 2n diffuse and multiplex two signals in a row of a space-time coding matrix using two diffusion codes. .. That is, the spreaders 11-1 and 2, 3 and 4, ..., 2n-1 and 2n have the same spreading code for user signal spreading (for example, the spreaders 11-1 and 2 have the same user signal spreading, respectively). Diffusion code C₁, C₂Is used. In the antenna branch 6-2, the set of diffusers corresponding to the user signals input as antenna branch 6-1 have the same spreading code C for user signal spreading.₁, C₂Is used. ) To perform time-direction diffusion or time-two-dimensional diffusion in the time direction and frequency direction shown in Fig. 3, and output to the corresponding local user signal multipliers 12-1, 2, ..., N, respectively. At this time, the spreaders 11-1 and 2 and 3 and 4 use different spreading codes for user signal spreading, and similarly, all the sets of diffusers use different user signal spreading codes from the other sets of spreaders. Use the diffusion code.

[0028] The local user signal multipliers 12-1, 2, ..., N are the local user signals input from the diffusers 11-1 and 2, 3 and 4, ..., 2n-1 and 2n, respectively. (For example, in the own user signal multiplier 12-1, the output signals of the diffusers 11-1 and 2 are the own user signals, and other than that, they can be regarded as other users. Also, other own user signals. (The same applies to the multipliers 12-2, 3, ..., N) are added, multiplexed in the same diffusion segment, and output to the other user signal multiplier 13. The other user signal multiplexing device 13 receives inputs of a plurality of own user signals in which the own user signal multiplexing devices 12-1, 2, ..., And n are multiplexed using different diffusion codes, and multiplexes them. , Output to the pilot signal multiplier 14.

[0029] The pilot signal multiplier 14 is a diffusion code C for user signal diffusion in each subcarrier in the time-direction diffusion or two-dimensional diffusion region._1、C₂Pilot signals are diffused by using a plurality of diffusion codes # 1 and # 2 for pilot signals orthogonal to the above, and the diffused pilot signal and a user signal multiplexed by another user are multiplexed. Here, when two-dimensional diffusion is used, the one in which the partial correlation between the diffusion codes in each subcarrier in the diffusion segment becomes 0 is selected (even if the partial correlation does not become 0, the frequency direction synthesis described later is performed. Can be suppressed). The Fast Inverse Fourier Transform 15 converts the generated frame signal (shown in FIG. 4), that is, the subcarrier signal multiplexed in the diffusion segment, into a time domain signal using the Fast Inverse Fourier Transform (IFFT), and guard intervals. Add (GI). The antenna 16 receives the output signal of the fast inverse Fourier transformer 15, up-converts it to the carrier frequency, and transmits it at the same time as the antenna of the antenna branch 6-2.

[0030] FIG. 8 shows the present embodiment in the multicarrier code division multiplexing (MC-CDM) method or the orthogonal frequency division multiple access code division multiplexing (OFDM-CDM) method when the radio transmitter is diffused in the time direction. It is a block diagram which shows the structure of the wireless receiver of. In FIG. 8, the radio receivers of the present embodiment include antenna branches 26-1, 2, adders 25-1, 2, ..., n, a block S / P converter 27, and a deinterleaver 23. And the decoder 21. Further, FIG. 9 shows a multicarrier code division multiple access (MC-CDM) method or an orthogonal frequency division multiplex code division multiple access (OFDM-CDM) method in the case of two-dimensional diffusion in the time direction and the frequency direction on the wireless transmitter side. It is a block diagram which shows the structure of the wireless receiver of this embodiment.

[0031] In FIG. 9, the wireless receivers of the present embodiment include antenna branches 26-1, 2, adders 25-1, 2, ..., n, a block S / P converter 27, and a device. It is composed of an interleaver 23, a decoder 21, and a frequency direction synthesizer 28-1, 2, ..., 2n-1, 2n. Antenna branch 26-1 includes antenna 36, fast Fourier transform (= -GI + FFT) 35, reverse diffuser 31-1, 2, ..., 2n-1, 2n, and reverse diffuser 37-. 1, 2, ..., 2n-1, 2n, channel estimator 38-1, 2, ..., 2n-1, 2n, space-time decoder 24-1, 2, ..., n Consists of. The antenna branch 26-2 is also configured in the same manner as the antenna branch 26-1.

[0032] The antenna 36 receives the signals transmitted from the antenna branches 6 and 2 of the wireless transmitter, down-converts the signals, and then outputs the signals to the fast Fourier transformer 35. The Fast Fourier Transformer 35 receives the input of the received signal from the antenna 36, removes the guard interval from the received signal, converts it to a subcarrier signal using the FFT, and then reverse diffusers 31-1, 2, ... , 2n-1, 2n, reverse diffuser 37-1, 2, ..., 2n-1, 2n. The despreaders 37-1, 2, ..., 2n-1, 2n receive the input of the subcarrier signal and are used in the antenna branches 6-1, 2 on the radio transmitter side in each subcarrier. The received subcarrier signal is despread using the spreading code for the pilot signal, and is output to the channel estimators 38-1, 2, ..., 2n-1, and 2n, respectively.

[0033] The channel estimators 38-1, 2, ..., 2n-1, 2n remove the modulation phase component of the pilot signal from the despread signal, and the antenna branch 6 on the radio transmitter side. The channel response from -1 and 2 is estimated, and the estimation result is output to the space-time encoder 24-1, 2, ..., n. The despreaders 31-1, 2, ..., 2n-1, 2n receive the input of the subcarrier signal, and as shown in FIG. 5, the pilot signal, the diffusion code for the pilot signal, and the obtained channel estimation. The value is used to generate a reception replica of the pilot signal from each transmitting antenna, the reception pilot signal replica is subtracted from the Fourier-converted reception subcarrier signal, and the reception subcarrier signal obtained by subtracting this pilot signal is self-reliant. Reverse diffusion is performed in the time direction using the diffusion code assigned to the user. The space-time decoders 24-1, 2, ..., N use the two sets of diffusion codes used by their own users for the signal after time-direction despreading output by the despreader 31-1. The received subcarrier signal is despread and space-time decoding is performed using the channel estimation value.

Adders 25-1, 2, ..., n receive output signals from the space-time encoders 24-1 of the antenna branches 26-1, 2 respectively, when the receiving antenna diversity is used. , The space-time decoding output of the diversity branch is synthesized and output to the block S / P converter 27 or the frequency direction synthesizer 28-1, 2, ..., 2n-1, 2n. The frequency direction synthesizers 28-1, 2, ..., 2n-1, 2n are the spatiotemporal decoding outputs added by the adders 25-1, 2, ..., n when two-dimensional diffusion is used. Then, it is further synthesized in the frequency direction and output to the block S / P converter 27. The block S / P converter 27 blocks the composite signal synthesized by the adders 25-1, 2, ..., n and the frequency direction synthesizer 28-1, 2, ..., 2n-1, 2n. Converts in parallel / series and outputs to the deinterleaver 23. The deinterleaver 23 receives the output signal of the block S / P converter 27, changes the order of the data in the reverse order of the interleaver 3, and outputs the data to the decoder 21. The decoder 21 receives the output signal of the deinterleaver 23, corrects the error, and obtains the reproduced data.

Next, the operation of the wireless transmitter and the wireless receiver of the present embodiment will be described with reference to the drawings. In the wireless transmitter of the present embodiment, when transmitting the transmission data Ω, error correction coding, mapping to the modulation constellation, and interleaving are performed in the encoder 1, the mapping device 2, and the interleaver 3, and the space-time encoder is performed. Output to 4. The encoder 4 has [s] as shown in FIG.₁, -s₂^*] To S / P converter 5-1 and [s₂, s₁^*] Is output to the S / P converter 5-2. The S / P converter 5-1 is a diffusion coded signal s₁To the S / P converter 10-1 of the antenna branch 6-1 to the diffused coded signal-s₂^*Is output to the S / P converter 10-2. Further, the S / P converter 5-2 is a diffusion coded signal s.₂To the S / P converter 10-1 of the antenna branch 6-2, the diffusion coded signal s₁^*Is output to the S / P converter 10-2.

Next, in the antenna branch 6-1 the S / P converter 10-1 sets the diffusion coded signal s.₁Is output to the diffuser 11-1, and the S / P converter 10-2 is the diffusion coded signal -s.₂^*Is output to the diffuser 11-2. The diffuser 11-1 is the diffused coded signal s at the antenna 16.₁The diffusion code C₁Spread with. In addition, the diffuser 11-2 is a diffusion coded signal -s.₂^*The diffusion code C₂Spread with. Then, the local user signal multiplier 12-1 uses the diffusion coded signal s.₁Diffuse output and spread coded signal-s₂^*The spreading output of is code-multiplexed in the same spreading segment as shown in FIG. Similarly, in the antenna branch 6-2, the S / P converter 10-1 uses the diffusion coded signal s.₂Is output to the diffuser 11-1, and the S / P converter 10-2 is the diffusion coded signal s.₁^*Is output to the diffuser 11-2. The diffuser 11-1 is the diffused coded signal s at the antenna 16.₂The diffusion code C₁Spread with. In addition, the diffuser 11-2 has a diffusion coded signal s.₁^*The diffusion code C₂Spread with. Then, the local user signal multiplier 12-1 uses the diffusion coded signal s.₂Spread output and spread coded signal s₁^*The spreading output of is code-multiplexed in the same spreading segment as shown in FIG.

At this time, the diffusers 11-1 and 11-1 and 2 perform time-direction diffusion or time-two-dimensional diffusion in the time direction and the frequency direction shown in FIG. That is, for example, the diffusion coded signal s₁When spreading in the time direction, the spreading coded signal s to multiple symbols in one subcarrier₁When spreading in the time and frequency directions, the spread coded signal s to multiple symbols in multiple subcarriers.₁To spread.

[0038] As a result, the local user signal code-multiplexed is obtained from the local user signal multiplexing device 12-1, and then the other user signal multiplexing device 13 similarly performs space-time coding and diffusion code multiplexing. The other user signal from the own user signal multiplexing device 12-2 or the like and the own user signal are multiplexed by the other user. Next, the pilot signal multiplexing unit 14 has a diffusion code C at each subcarrier in the time-direction diffusion or two-dimensional diffusion region._1、C₂Pilot signal s using multiple pilot signal diffusion codes that are orthogonal to_pIs diffused, and the diffused pilot signal and the user signal multiplexed by another user are multiplexed. Then, the fast inverse Fourier transform unit 15 converts the frame signal (shown in FIG. 4) generated thereby into a time domain signal by using the fast inverse Fourier transform (IFFT), and adds a guard interval (GI). Then, the antenna 16 simultaneously radiates the transmission signal up-converted to the carrier frequency at the antenna branches 6-1, 6-2.

[0039] On the other hand, on the radio receiver side, the antenna 36 of the antenna branch 26-1 receives the signals radiated at the same time in the antenna branches 6-1, 6-2. The fast Fourier transformer 35 receives the input of the received signal from the antenna 36, removes the guard interval from the received signal, converts it into a subcarrier signal using the FFT, and then reverse diffusers 31-1 and 2 and the reverse spreader. Output to 37-1 and 2. The despreader 37-1 receives the input of the received subcarrier signal in the time slots 1 and 2 converted into the received subcarrier signal by the fast Fourier transform (FFT) after the guard interval is removed by the fast Fourier transformer 35, and the pilot Back-spreading is performed on each subcarrier using the signal spreading code # 1, and channel h₁And pilot signal s_pOutput the product of. Further, the despreader 37-2 similarly performs despreading at each subcarrier using the spread code # 2 for the pilot signal, and channel h.₂And pilot signal s_pOutput the product of.

Next, the channel estimators 38-1 and 2 are set to the channel h.₁And pilot signal s_pProduct, channel h₂And pilot signal s_pFor the signal consisting of the product of, the modulation component of the pilot signal is removed, and the channel response h_1、h₂To estimate. And channel estimators 38-1, 2 are pilot signals s_p, Pilot signal diffusion codes # 1 and # 2 and the obtained channel estimates h_1、h₂Is used to generate a receiving replica of the pilot signal from each transmitting antenna. On the other hand, the reverse spreaders 31-1 and 2 subtract the received pilot signal replica generated by the channel estimators 38-1 and 2 from the Fourier-transformed received subcarrier signal, and subtract this pilot signal into the received subcarrier signal. On the other hand, the diffusion code C assigned to the own user₁And C₂Is used to reverse diffuse in the time direction. As a result, the diffusion code C₁The signal back-spread in is channel h₁And diffuse coded signal s₁Product with and channel h₂And diffuse coded signal s₂It is represented by the sum of products with. Also, the diffusion code C₂The signal back-spread in is channel h₁And diffuse coded signal-s₂^*Product with and channel h₂And diffuse coded signal s₁It is represented by the sum of products with. Then, the space-time decoder 24-1 has a channel estimate h for two despread outputs belonging to these different time slots.₁, H₂Using the spread coded signal s₁And diffuse coded signal s₂Is calculated, and space-time decoding is performed. When the transmitted signal is spread in the time direction, the received signal is decoded in the wireless receiver (see FIG. 5). On the other hand, when the transmission signal is two-dimensionally diffused in the time direction and the frequency direction, the spatiotemporally decoded signal in each subcarrier is synthesized in the frequency direction, and the received signal is decoded in the wireless receiver as described above ( See Figure 6).

Therefore, in the spatiotemporal transmission diversity, the time direction output of the spatiotemporal coding matrix is spread in a plurality of diffusion regions in the time direction, whereas in the radio transmitter and the radio receiver of the present embodiment, the spatiotemporal code is used. Since the temporal output of the chemical matrix is diffused within one diffusion region using multiple diffusion codes, the channel's resistance to time fluctuations is improved. Further, when two-dimensional diffusion is used, each subcarrier can partially reverse-diffuse in the time direction to perform decoding and synthesize in the frequency direction.

[0042] In the above-described embodiment, the frame configuration in which the pilot signal is code-multiplexed has been described, but the present invention is not limited to this, for example, a frame in which the pilot signal is time-multiplexed. It is also applicable to the configuration. Further, when the spreading code is surplus, the spreading code may be used for a fast-moving user to multiplex the space-time coded output in one spreading segment. In addition, when there are two users of high-speed movement, the two time slots used in the time-space transmission diversity are divided and used by each of the two users, and both the diffusion codes assigned to each user are used. You may.

[0043] The above-mentioned wireless transmitter and wireless receiver have a computer system inside. The series of processes related to the signal processing described above are stored in a computer-readable recording medium in the form of a program, and the processing is performed by the computer reading and executing this program. Here, the computer-readable recording medium refers to a magnetic disk, a magneto-optical disk, a CD-ROM, a DVD-ROM, a semiconductor memory, or the like. Further, this computer program may be distributed to a computer via a communication line, and the computer receiving the distribution may execute the program.

[Effect of the Invention] As described above, the present invention encodes a transmission signal using a space-time coding matrix on the radio transmitter side, and the space-time of different time slots of the coded space-time coding output. The coded signal is spread using different spreading codes, the spread spreading signal is transmitted, the radio receiver receives the spread signal, and a predetermined time slot of the received spread signal is referred to as this time slot. A signal that has been de-spread and de-spread using the corresponding spreading code is decoded using a space-time coding matrix, so that the coded output for transmission diversity is contained within one spreading region and is resistant to Doppler frequencies. It is possible to obtain an effect that can improve.

BRIEF DESCRIPTION OF THE DRAWINGS [FIG. 1] FIG. 1 is an explanatory diagram illustrating the principle of the wireless transmitter of the present embodiment.

FIG. 2 is an explanatory diagram illustrating the principle of allocating a space-time coded output to a diffusion region in the wireless transmitter of the present embodiment.

FIG. 3 is an explanatory diagram illustrating the principle of time-direction diffusion in the wireless transmitter of the present embodiment.

FIG. 4 is an explanatory diagram illustrating the principle of two-dimensional diffusion in the wireless transmitter of the present embodiment.

FIG. 5 is an explanatory diagram illustrating a frame signal at antenna branch # 1 in the wireless transmitter of the present embodiment.

FIG. 6 is an explanatory diagram illustrating the principle of the wireless receiver of the present embodiment.

FIG. 7 is a configuration diagram showing a configuration of a wireless transmitter according to the present embodiment.

FIG. 8 is a configuration diagram showing a configuration of a wireless receiver according to the present embodiment.

FIG. 9 is a configuration diagram showing a configuration of a wireless receiver according to the present embodiment.

FIG. 10 is a configuration diagram showing a configuration of a conventional wireless transmitter.

FIG. 11 is a configuration diagram showing a configuration of a conventional wireless receiver.

FIG. 12 is an explanatory diagram illustrating the allocation of a conventional space-time coded output to a diffusion region.

[Explanation of codes] 1 ... Coder 2 ... Mapping device 3 ... Interleaver 4 ... Space-time coder 5-1,2 ... S / P converter 6-1, 2.. .Antenna branch 10-1, 2 ... S / P converter 11-1, 2, ..., 2n ... diffuser 12-1, 2, ..., n ... own user signal multiplexing Instrument 13 ... Other User Signal Multiplier 14 ... Pilot Signal Multiplier 15 ... High Speed Inverse Fourier Converter 16 ... Antenna 21 ... Decoder 23 ... Deinterleaver 24-1, 2 , ..., n ... Space-time decoder 25-1, 2, ..., n ... Adder 26-1, 2 ... Antenna branch 27 ... Block S / P converter 28- 1, 2, ..., 2n-1, 2n ... Frequency direction synthesizer 31-1, 2, ..., 2n-1, 2n ... Reverse diffuser 35 ... Fast Fourier transducer 36 ... Antenna 37-1, 2, ..., 2n-1, 2n ... Reverse Diffuser 38-1, 2, ..., 2n-1, 2n ... Channel Estimator