Abstract: Of any one of a transmission method X of transmitting modulated signal A and modulated signal B including the same data from a plurality of antennas and a transmission method Y of transmitting modulated signal A and modulated signal B having different data from the plurality of antennas, a base station apparatus does not change the transmission method during data transmission and changes only the modulation scheme. The base station apparatus transmits modulated signal A and modulated signal B to a communication terminal apparatus using the determined transmission method and modulation scheme. In this way, it is possible to improve data transmission efficiency when transmitting data using the plurality of antennas.

Abstract: Modulated signal A is transmitted from a first antenna, and modulated signal B is transmitted from a second antenna. As modulated signal B, modulated symbols S2(i) and S2(i+1) obtained from different data are transmitted at time i and time i+1 respectively. In contrast, as modulated signal A, modulated symbols S1(i) and S1(i)? obtained by changing the signal point arrangement of the same data are transmitted at time i and time i+1 respectively. As a result the reception quality can be changed intentionally at time i and time i+1, and therefore using the demodulation result of modulated signal A of a time when the reception quality is good enables both modulated signals A and B to be demodulated with good error rate performances.

Abstract: A transmission apparatus includes a plurality of orthogonal frequency division multiplexing (OFDM) modulation signal generators, which generate a first OFDM modulation signal and a second OFDM modulation signal. The transmission apparatus also includes a transmitter that transmits the first OFDM modulation signal from a first antenna and the second OFDM modulation signal from a second antenna, in an identical frequency band.

Abstract: A method of generating modulation signals is disclosed including generally three steps. A plurality of modulation signals are generated, each of which is to be transmitted from a different one of a plurality of antennas in an identical frequency band, wherein each modulation signal includes a pilot symbol sequence including a plurality of pilot symbols used for demodulation. Each of the pilot symbol sequences is inserted at the same temporal point in each modulation signal, wherein the pilot symbol sequences are orthogonal to each other with zero mutual correlation among the plurality of modulation signals, each pilot symbol having a non-zero amplitude, the quantity of the plurality of pilot symbols in each sequence being greater than the quantity of the plurality of modulation signals to be transmitted. The plurality of modulation signals each including different transmission data and one of the pilot symbol sequences are output to the antennas.

Abstract: An encoding method and an encoder for creating a low-density parity check convolution code (LDDC-CC), sending a signal sequence after subjecting the code to an error-correction using the low-density parity check convolution code, and creating a low-density parity check code of a time-variant period (3g) by linear operations of first to 3g-th (letter g designates a positive integer) parity check polynomials and input data.

Abstract: MIMO-OFDM communication is provided which allows high accuracy estimation of frequency offset, high accuracy estimation of a transmission path fluctuation and high accuracy synchronization/signal detection. Pilot symbol mapping is provided for forming pilot carriers by assigning orthogonal sequences to corresponding subcarriers among OFDM signals which are transmitted at the same time from respective antennas in the time domain. Even when pilot symbols are multiplexed among a plurality of channels (antennas), this allows frequency offset/phase noise to be estimated with high accuracy.

Abstract: Soft decision sections provisionally decide each modulated signal separated using an inverse matrix calculation of a channel fluctuation matrix at separation section. Signal point reduction sections reduce candidate signal points of a multiplexed modulated signal using the provisional decision results. Soft decision sections make a correct decision using the reduced candidate signal points and obtain received data of each modulated signal. This allows received data RA, RB with a good error rate characteristic to be obtained with a relatively small number of calculations without reducing data transmission efficiency.

Abstract: A communication method of a base station transmits a modulation signal based on an OFDM (orthogonal frequency division multiplexing) modulation scheme to a plurality of communication terminals. The method includes forming a transmission frame on which a first subcarrier group and a second subcarrier group are arranged, and determining on a per frame basis, which subcarrier group of the first subcarrier group and the second subcarrier group is allocated to each of the plurality of communication terminals and what number of subcarriers are selected from the subcarrier group that is allocated to each of the plurality of communication terminals. The method further includes forming the transmission frame based on the determined subcarrier group and the determined number of subcarriers, transmitting the modulation signal including the transmission frame, and receiving feedback information including radio propagation condition estimation information from each of the plurality of communication terminals.

Abstract: A wireless communication method of a base station that transmits a modulation signal based on an orthogonal frequency division multiplexing scheme to a plurality of terminals. The method includes determining, for each terminal of the plurality of terminals, which subcarrier group or how many symbols along a time axis are to be allocated in a transmission frame, the transmission frame including a first period in which first transmission symbols are arranged and a second period in which second transmission symbols which are different from the first transmission symbols are arranged. The method also includes forming the transmission frame according to a determined allocation, wherein a plurality of symbols on a frequency axis for transmitting N bits (N is a natural number) are arranged within a part of the first period, by using a modulation scheme whereby N bits can be transmitted using one symbol. The method further includes transmitting the modulation signal using the transmission frame.

Abstract: A radio transmitting apparatus that has a plurality of antennas and changes the number of modulated signals transmitted simultaneously according to the propagation environment and so forth. A transmission power changing section 12 of a radio transmitting apparatus of the present invention adjusts the pilot symbol signal level so as to match the data symbol composite signal level according to the number of transmit modulated signals set by a modulated signal number setting section 11. By this means, the operating range of received pilot symbols and the operating range of received data symbols become approximately the same on the receiving side, enabling pilot symbol quantization error to be reduced. As a result, the precision of radio wave propagation environment estimation, time synchronization, and frequency offset estimation using pilot symbols improves, and consequently data reception quality improves.

Abstract: A transmission apparatus includes a plurality of orthogonal frequency division multiplexing (OFDM) modulation signal generators, which generate a first OFDM modulation signal and a second OFDM modulation signal. The transmission apparatus also includes a transmitter that transmits the first OFDM modulation signal from a first antenna and the second OFDM modulation signal from a second antenna, in an identical frequency band.

Abstract: In a multivalue modulation type with one pilot symbol inserted for every 3 or more symbols, signal points of each one symbol immediately before and after a pilot symbol are modulated using a modulation type different from that for pilot symbols. In this way, it is possible to suppress deterioration of the accuracy in estimating the reference phase and amount of frequency offset by pilot symbols and improve the bit error rate characteristic in the signal to noise ratio in quasi-coherent detection with symbols whose symbol synchronization is not completely established.

Abstract: A transmitting apparatus and method transmits different modulated signals from a plurality of antennas, and employs a configuration that includes a modulation section that obtains a modulated signal by performing signal point mapping of transmit bits using a signal point arrangement that is divided into a plurality of signal point sets on the IQ plane, whereby the minimum distance between signal points within a signal point set is smaller than the minimum signal point distance between signal point sets; and an antenna that transmits a modulated signal obtained by the modulation section. A signal point generating apparatus generates a first and second symbols to be transmitted by first and second antennas, respectively.

Abstract: An encoder and decoder using LDPC-CC (Low Density Parity Check-Convolutional Codes) is disclosed. In the encoder (200), an encoding rate setting unit (250) sets an encoding rate (s?1)/s (s=z), and an information creating unit (210) sets information including from information Xs,i to information Xz?1,i to zero. A first information computing unit (220-1) receives information X1,i at time point i to compute the X1(D) term of formula (1). A second information computing unit (220-2) receives information X2,i at time point i to compute the X2(D) term of formula (1). A third information computing unit (220-3) receives information X3,i at time point i to compute the X3(D) term of formula (1). A parity computing unit (230) receives parity Pi?1 at time point i?1 to compute the P(D) of formula (1). The exclusive OR of the results of the computation is obtained as parity Pi at time i. Ax.

Abstract: A method of generating modulation signals is disclosed including generally three steps. A plurality of modulation signals are generated, each of which is to be transmitted from a different one of a plurality of antennas in an identical frequency band, wherein each modulation signal includes a pilot symbol sequence including a plurality of pilot symbols used for demodulation. Each of the pilot symbol sequences is inserted at the same temporal point in each modulation signal, wherein the pilot symbol sequences are orthogonal to each other with zero mutual correlation among the plurality of modulation signals, each pilot symbol having a non-zero amplitude, the quantity of the plurality of pilot symbols in each sequence being greater than the quantity of the plurality of modulation signals to be transmitted. The plurality of modulation signals each including different transmission data and one of the pilot symbol sequences are output to the antennas.

Abstract: A transmitting apparatus and method transmits different modulated signals from a plurality of antennas, and employs a configuration that includes a modulation section that obtains a modulated signal by performing signal point mapping of transmit bits using a signal point arrangement that is divided into a plurality of signal point sets on the IQ plane, whereby the minimum distance between signal points within a signal point set is smaller than the minimum signal point distance between signal point sets; and an antenna that transmits a modulated signal obtained by the modulation section. A signal point generating apparatus generates a first and second symbols to be transmitted by first and second antennas, respectively.

Abstract: A multiple-input multiple-output (MIMO) orthogonal frequency division multiplexing (OFDM) transmission and reception apparatus is provided which allows high accuracy estimation of frequency offset, high accuracy estimation of a transmission path fluctuation and high accuracy synchronization/signal detection. A mapping section generates a plurality of OFDM signals. In these OFDM signals, some pilot carriers are assigned to the same carrier position, and orthogonal sequences are assigned to the same time slot in the same carrier position.

Abstract: An encoder and decoder using LDPC-CC (Low Density Parity Check-Convolutional Codes). An encoding rate setting unit sets an encoding rate (s?1)/s (s=z), and an information creating unit sets information including from information Xs,i to information Xz?1,i to zero. A first information computing unit receives information X1,i at time point i to compute the X1(D) term of a formula. A second information computing unit receives information X2,i at time point i to compute the X2(D) term of the formula. A third information computing unit receives information X3,i at time point i to compute the X3(D) term of the formula. A parity computing unit receives parity Pi?1 at time point i?1 to compute the P(D) of the formula. The exclusive OR of the results of the computation is obtained as parity Pi at time i.

Abstract: Modulated signal A is transmitted from a first antenna, and modulated signal B is transmitted from a second antenna. As modulated signal B, modulated symbols S2(i) and S2(i+1) obtained from different data are transmitted at time i and time i+1 respectively. In contrast, as modulated signal A, modulated symbols S1(i) and S1(i)? obtained by changing the signal point arrangement of the same data are transmitted at time i and time i+1 respectively. As a result the reception quality can be changed intentionally at time i and time i+1, and therefore using the demodulation result of modulated signal A of a time when the reception quality is good enables both modulated signals A and B to be demodulated with good error rate performances.

Abstract: An input digital signal is periodically and alternately subjected to first modulation and second modulation, being thereby converted into a pair of a baseband I signal and a baseband Q signal. The first modulation and the second modulation are different from each other. The pair of the baseband I signal and the baseband Q signal are outputted. The first modulation may be at least 8-signal-point modulation while the second modulation may be phase shift keying.