Abstract: Provided is a transmitting device which improves a data rate while maintaining channel estimation accuracy, or improves channel estimation accuracy while maintaining a data rate, in a MIMO-OFDM system. In the transmitting device, a transmitting antenna information adding section (104) adds transmitting antenna information to a pilot signal by performing different phase rotation to the separate pilot signal by transmitting antenna by having a common pilot signal as a reference phase. A pilot arranging section (107) is previously provided with, as a conversion table, a corresponding relationship between combination information of the transmitting antenna and a subcarrier to be used for transmission of the pilot signal and control information. The pilot arranging section (107) allocates the pilot signal outputted from the transmitting antenna information adding section (104) to the subcarrier to have the combination information in accordance with the control information.

Abstract: A wireless communication system enabling multihop communication while maintaining the system throughput and preventing degradation of the user throughput. In the system, a BS (base station) determines the relaying method (whether an RS performs reproduction relay or nonreproduction relay) of the RS (relaying station) and the MCS of multihop communication according to the reception quality (the line quality among an MS2, the RS, and the BS) of the pilot for nonreproduction relay, the reception quality (the line quality between the RS and the BS) of the pilot 2 for reproduction relay, and the line quality (the line quality between the MS2 and the RS) measured at the RS. The determination result is transmitted as relay information to the RS and to the MS2 (a mobile station (2)) through the RS. The MS2 encodes and modulates the uplink data with the MCS based on the relay information and transmits the data to the RS.

Abstract: A transmitting apparatus, a receiving apparatus and a transmission power control method wherein even in a case of performing a transmission power control of multi-valued modulated symbols, the degradation of reception characteristic and that of network usage efficiency can be avoided. A power control instructing part (204) adjusts, based on an encoding rate and a modulation scheme in a case of applying a power control value, which maximizes the MIMO channel capacity, to each stream, the power control value of a stream, which is the most likely to be affected by a power estimation error, into a reference value, and then applies the adjustment value used for that adjustment to the other streams, that is, the streams that are not likely to be affected by the power estimation error. A power control part (205) performs a transmission power control in accordance with the power control value as adjusted by the power control instructing part (204).

Abstract: Provided is a mobile communication system capable of obtaining a diversity effect even when a signal received by a relay station has an error in a corporate relay to which time space encoding is applied. In this mobile communication system, when S1 has no error and S2 has an error, a relay station (1) does not perform relay transmission at time t (Null) and relay-transmits S1* to a base station at time t+T. That is, in this case, the relay station (1) relay-transmits at time t+T only S1 to be transmitted at time t when no error is contained in either S1 or S2. Moreover, when S1 has an error and S2 has no error, the relay station (1) relay-transmits S2 at time t and does not perform relay transmission at time t+T (Null). That is, in this case, the relay station (1) relay-transmits only S2 to be transmitted at time t+T at time t if no error is contained in either S1 or S2.

Abstract: A radio transmitting apparatus, a radio receiving apparatus, a wireless communication method and a wireless communication system wherein even when a channel correlation is large, the channel capacity and the feedback amount can be improved. In ST401, a receiving apparatus (200) determines that the channel correlation value exceeds a predetermined threshold value. In ST402, a transmitting apparatus (100) is instructed to perform 42 MIMO transmission. In ST403, the transmitting apparatus (100) determines a pair of antennas exhibiting the highest channel correlation. In ST406, the receiving apparatus (200) uses, based on the pair information, a channel matrix, which comprises channel estimation values, to calculate a delay shift amount. In ST407, the delay shift amount is fed back to the transmitting apparatus (100). In ST408, the transmitting apparatus (100) uses the pair information and delay shift amount to combine SDM and a cyclic sample delay diversity, thereby transmitting data.

Abstract: A transmitter, a receiver and a communication method enabling improvement of the data rate of an MIMO system. One signal x2 out of the three signals is combined with the other two signals x1, x3 respectively to generate two combined signals x1+x2, x2+x3. The combined signals are transmitted through transmission antennas (102, 103). A signal separating section (106) of the receiver separates the received signals r1, r2 into two signals y1, y2 by a signal separation processing such as the ZF. An MLD processing section (107) generates MLD evaluation formulae using y1, y2 and performs an MLD processing in which x2 is cancelled from y1, y2 and evaluation formulae about x1, x3 are generated, and a maximum likelihood estimation is performed. As a result of the MLD processing, x1, x3 are detected. In a canceling section (108) the detected x1, x3 are canceled from y1, y2, and x2 is detected.

Abstract: A radio transmitting apparatus, a radio receiving apparatus and a radio transmitting method wherein the accuracy of detecting streams in D-TxAA is improved. There is included a transmission mode switching part (102) that switches output destinations of first and second input streams (1865,1866) in accordance with the propagation environments of first and second MIMO channel beams (1831,1832). The transmission mode switching part (102) switches from a D-TxAA mode transmission to a first or second unique mode transmission in accordance with the propagation environments.

Abstract: An interleave apparatus and an interleave method for preventing an increase in the number of retransmissions to improve the throughput. In a wireless communication apparatus having the interleave apparatus, a data holding part (1021) two-dimensionally arranges and holds bit sequences. A first index calculating part (1022) sequentially calculates first indexes to be used for reading, in a column direction, the bit sequences arranged in a row direction. A second index calculating part (1023) sequentially calculates second indexes to be used for reversing the order of the upper-order and lower-order bits to be read from the even-numbered columns when the bit sequences are read in accordance with the first indexes. A third index calculating part (1024) sequentially calculates third indexes to be used for reading the bit sequences from a different start position in accordance with the number of retransmissions. A reading part (1025) reads the bit sequences in the order that is in accordance with the third indexes.

Abstract: A wireless communication apparatus that allows channel information to be reproduced with high precision at a transmitting end without increasing feedback information amount. In this apparatus, a channel estimating part (103) uses received pilot signals to perform channel estimation for each channel. A correlation detecting part (104) uses the result of the channel estimation to obtain correlation values between the channels, thereby detecting correlation values of all channels. An amplitude/phase ratio determining part (105) determines, based on the correlation values, the quantization bit ratio of the amplitude and phase of channel information to be used when those amplitude and phase are quantized. A feedback information generating part (106) quantizes the channel information in accordance with the determined ratio of the amplitude and phase.

Abstract: A MIMO transmitting apparatus that achieves a flexible control in accordance with variation of a propagation environment to reduce the number of retransmissions. A buffer (104) temporarily stores transport bits, which have been interleaved, in preparation for retransmission. An intra-code-word interleaver (105) performs an interleave process by all of the bits included in the symbols to be simultaneously transmitted from a plurality of transmitting antennas. When performing an intra-code-word interleave process, the intra-code-word interleaver (105) performs the interleave process in accordance with an interleave pattern notified from an interleave pattern table (107). A counter (106) counts retransmission requests, and outputs the number of retransmissions to the interleave pattern table (107).

Abstract: A link adaptation method and others wherein feedback information amount can be reduced. According to this method, a receiving apparatus (100) calculates, based on a channel matrix, a capacity (C) and a stream ratio (r) that is a ratio of the reception qualities of streams, and then transmits, as feedback information, the calculated capacity (C) and stream ratio (r) to a transmitting apparatus. In the transmitting apparatus (200), the number of transmittable streams, the modulation scheme and the fed-back capacity (C) are used to calculate the encoding ratio (R) and sequence length (S) of spatial multiplexed symbols. Then, the modulation scheme (M1-Mn) of each stream is decided based on the fed-back stream ratio (r) and the sequence length (S) of spatial multiplexed symbols.

Abstract: A retransmission control scheme and a wireless communication apparatus wherein the efficiency of retransmission control is enhanced to further improve the system throughput. In this wireless communication apparatus (100), an error occurrence factor addressing part (140) receives information related to the error occurrence factor of a transmitted packet or information related to the schemes of forming or transmitting a retransmittal packet corresponding to that error occurrence factor, and switches, based on the received information, the schemes of forming or transmitting the retransmittal packet. In this way, the schemes of forming or transmitting the retransmittal packet can be switched in accordance with the error occurrence factor of the transmitted packet. At the end of receiving the retransmittal packet, therefore, the performing of a decoding processor the like in accordance with that scheme of forming or transmitting can enhance the efficiency of the retransmission control.

Abstract: There are disclosed a radio communication device and others capable of generating in a short time a secret key common to a base station and a mobile station in a radio communication system using the MIMO technique and starting the encrypted communication at an early stage. In this device, in ST545, when a channel coincidence judgment unit (105) and a channel coincidence judgment processing unit (205) respectively judge that the channel matrix generated by the base station completely coincides with the channel matrix generated by the mobile station or they do not coincide completely but they can coincide finally by error correction of the secret key or the like, according to the judgment result indicated in the channel coincidence judgment signal generated in ST540-2, ST545 is followed by ST550.

Abstract: A symbol arranging method by which a processing load due to channel estimation for MIMO channels can be reduced. In the methods a symbol is arranged for a transmission frame format having a pilot area and a data area. The pilot symbol is arranged in the pilot area. An ICE data symbol used for iterative channel estimation (ICE) is arranged in an ICE data area in the data area. The MIMO data symbol not used for ICE is arranged in the MIMO data area in the data area.

Abstract: Provided is a radio communication method or the like for making compatible an improvement in error rate characteristics and a reduction in delay. The radio communication method is used in a mobile communication system (1) including a mobile station (10), a relay station (20) and a base station (30). A transmitted signal containing a signal addressed to the base station (30) is transmitted at first from the mobile station (10) to the relay station (20). A non-reproduced relay signal obtained in the relay station (20) from the transmitted signal is transmitted from the relay station (20) to the base station (30). On the basis of the reception result of the non-reproduced relay signal at the base station (30), a re-transmission request of the transmitted signal is transmitted from the base station (30).

Abstract: A wireless communication method and the like for improving the system throughput. The wireless communication method is used in a mobile communication system having a base station apparatus (BS), a relay station apparatus (RS) (100) and a mobile station apparatus (MS) #1. In a first transmission step, a first transport signal, which includes data addressed to MS #1, is transmitted from BS to RS (100). In a second transmission step, a second transport signal, which includes a pilot generated by BS, is transmitted from BS. Simultaneously, in the second transmission step, a relay signal, which includes the data addressed to MS #1 and also includes a pilot that is generated by RS (100) and that has a particular orthogonal relationship with the pilot generated by BS, is transmitted from RS (100) to MS #1.

Abstract: An inventive wireless communication apparatus that, in a wireless communication system to which a secret key scheme is applied, can generate a secret key, which is different from a secret key generated by a third party, even if a wireless signal is intercepted by the third part having an approximate propagation path environment to a receiving wireless communication apparatus. In the inventive apparatus, an eigenvalue selecting part (317) of a secret key generating part (207) selects a maximum one of MIMO channel eigenvalues received from an eigenvalue detecting part (206) and inputs the selected maximum eigenvalue to a quantizing part (327). The quantizing part (327) quantizes the magnitude of the maximum eigenvalue received from the eigenvalue selecting part (317) to produce and input a quantized data to a key generating part (337).

Abstract: There is disclosed a radio communication device capable of preventing wire-tap of an encrypted communication even if a radio signal is wire-tapped by a third person in a radio communication system using the MIMO technique. In this device, an inter-channel correlation calculation unit (104) calculates an inter-channel correlation value between two channels in the MIMO channel according to four channel estimation values inputted from a channel estimation unit (103). The six channel correlation values calculated are all inputted to a channel selection unit (105). The channel selection unit (105) selects a minimum channel correlation value from the six channel correlation values inputted from the inter-channel correlation calculation unit (104) and reports two channels corresponding to the selected channel correlation value to an inter-channel correlation monitoring unit (110) and inputs the channel estimation value of the two channels to a secret key generation unit (106).

Abstract: A wireless communication method of repetition system and the like for ensuring that when the same data symbols are combined, a diversity gain is achieved. In a step (ST 420), a data symbol placing part (105) decides destination places of respective replicated data symbols (S1-S4) such that the same data symbols are not placed at destination place numbers (7,8) of data symbols that exhibit poor channel estimation precisions. In a step (ST 430), the data symbol placing part (105) places, in accordance with the decision in the foregoing step (ST 420), the four data symbols (S1-S4), which are received from a repetition part (102), in one frame received from a channel estimation error predicting part (104).

Abstract: A radio transmitting apparatus and the like for improving the reception error rate characteristic. In this apparatus, a data modulating part (121) modulates a data signal to provide a modulated symbol. A Q-inverting part (125) generates a symbol that corresponds to the modulated symbol provided by the data modulating part (121) and that, when combined with the modulated symbol, becomes a signal having a particular value. A multiplexing part (110) multiplexes the modulated symbol provided by the data modulating part (121) with the corresponding symbol generated by the Q-inverting part (125) to provide a multiplexed signal.