Abstract: The degree of multiplexing of a code division multiplexed signal transmitted by subcarriers is selected on a subcarrier-by-subcarrier basis. As a result, inter-code interference on the propagation path and degradation on the propagation path are lower for a code division multiplexed signal allocated to subcarriers with a low degree of signal multiplexing (G1) than for transmit signals allocated to subcarriers with a high degree of multiplexing. By this technique, it is possible to prevent degradation of the error rate characteristics of important information without lowering spectral efficiency significantly as compared with the case in which the degree of signal multiplexing is decided uniformly for all subcarriers, and to achieve compatibility between spectral efficiency and error rate characteristics.

Abstract: An orthogonal frequency division multiplexing (OFDM) transmission apparatus and method generate a transmission sequence including first data, second data, and known signals such that more known signals are allocated to the first data than to the second data within the transmission sequence. The transmission sequence is OFDM multiplexed into a sequence of OFDM signals and transmitted. A receiver of the OFDM signal sequence uses the known signals for estimating transmission paths of the communicated OFDM signals and improving the reception of the data to which they are allocated.

Abstract: An OFDM communication apparatus includes a determining section determine a number of known signals for transmission path estimation to be inserted in a transmit signal based on channel quality with respect to a communicating party, and a generating section performs inverse Fourier transform processing on an information signal and the number of known signals for transmission path estimation determined by the determining section and generates a transmit signal for the communicating party. The apparatus achieves both an improvement in demodulated signal error rate characteristics and an improvement in information signal transmission efficiency.

Abstract: The number of multiplexing of individual transmit symbols is selected by means of selection sections B1 through B5. The number of spread signals selected by selection sections B1 through B5 are multiplexed adders C1 through C5. By this means, it is possible to select inter-code interference in code division multiplexed signal transmission on a symbol-by-symbol basis, enabling error rate characteristic quality to be selected on a symbol-by-symbol basis. As a result, if a symbol for which the number of multiplexing is reduced and error rate characteristics are made good is selected as appropriate, error rate characteristics can be improved without degrading frequency characteristics so much.

Abstract: Modulation section 201 performs modulation processing on transmission data. Mapping control section 202 controls mapping of the baseband signal onto the subcarriers so that the important information conventionally transmitted by one subcarrier is transmitted by two subcarriers and one of the two subcarriers should be the subcarrier with a carrier frequency signal of frequency 0 which was conventionally not used. IFFT section 203 performs IFFT processing on the modulated transmission data. Transmission section 204 performs transmission processing on the IFFT-processed transmission data and transmits the processed transmission data from antenna 205.

Abstract: Modulation section 201 performs modulation processing on transmission data. Mapping control section 202 controls mapping of the baseband signal onto the subcarriers so that the important information conventionally transmitted by one subcarrier is transmitted by two subcarriers and one of the two subcarriers should be the subcarrier with a carrier frequency signal of frequency 0 which was conventionally not used. IFFT section 203 performs IFFT processing on the modulated transmission data. Transmission section 204 performs transmission processing on the IFFT-processed transmission data and transmits the processed transmission data from antenna 205.

Abstract: A multicarrier transmitting apparatus includes a dividing section that divides transmit data into high-quality transmit data requiring good quality and ordinary transmit data other than the high-quality transmit data. A subcarrier allocation section rearranges the high-quality transmit data and the ordinary transmit data such that the high-quality transmit data is allocated to subcarriers in the vicinity of a center frequency in a predetermined frequency domain and the ordinary transmit data is allocated to subcarriers in the vicinity of both ends in the predetermined frequency domain. The subcarrier allocation section varies, in accordance with channel quality, a range of subcarrier to which the high-quality transmit data and ordinary transmit data are allocated. An orthogonal frequency division multiplexing section performs orthogonal frequency division multiplexing of the high-quality transmit data and the ordinary transmit data rearranged by said subcarrier allocating section.

Abstract: There is provided a transmission device capable of preventing increase of retransmission information or encoding redundant bit and improving a throughput in a MIMO communication method. In this device, an encoding unit (130) subjects data transmitted from a first transmission antenna (110) and a second transmission antenna (120) each formed by a plurality of antennas, to encoding processing all at once. Modulation units (113, 123) modulate the data encoded by the encoding unit (130) for each of the first and the second transmission antennas (110, 120). Transmission units (115, 125) process the modulated data so that it can be transmitted from the corresponding first and the second antennas (110, 120). A transmission control unit (160) performs transmission control of the data transmitted from the respective antennas (110, 120).

Abstract: There is provided a communication device capable of transmitting a transfer rate request signal while reducing it and reducing the interference and power consumption when the transfer rate request signal is transmitted substantially without lowering the transmission efficiency in the MIMO communication method. In this device, a modulation encoding unit (125) encodes and modulates transmission data transmitted to a communication partner of the MIMO communication method and the transfer rate request signal in the plurality of transmission antennas. A transmission unit (132) and a transmission antenna (134) transmit a signal from the modulation encoding unit (125).

Abstract: When OFDM signals are transmitted from a plurality of antennas, a pilot carrier is transmitted from one antenna among the plurality of antennas, and a null signal is transmitted from an antenna other than that antenna by a subcarrier of the frequency band that transmits the pilot carrier.

Abstract: A transmission-reception apparatus does not configure ARQ control information from only sequence number, but the transmission-reception apparatus configures the ARQ control information such that the ARQ control information is comprised of one sequence number containing first occurrence of a corresponding packet's error, and bit information representing existence of retransmission requirements about sequence numbers followed on the heels of such the one sequence number.

Abstract: A method and apparatus for setting a guard interval in an OFDM communication. The method includes attaching a part of a first valid symbol to the first valid symbol as a guard interval and attaching a part of a second valid symbol requiring higher channel quality than the first valid symbol, to the second valid symbol as a guard interval, and providing the guard interval of the second valid symbol at a length greater than the guard interval of the first valid symbol.

Abstract: A Multi-Input/Multi-Output (MIMO) receiver may include a plurality of receiving antennas that receive a plurality of radio signals and an estimation section that finds channel estimation values of the plurality of radio signals. A MIMO separation section separates, using a MIMO scheme, the plurality of radio signals in accordance with the channel estimation values, and a compensation section compensates for channel variations of the plurality of radio signals. A selection section selects one of the MIMO separation section and the compensation section.

Abstract: A Multi-Input/Multi-Output (MIMO) receiver may include a plurality of receiving antennas that receive a plurality of radio signals and an estimation section that finds channel estimation values of the plurality of radio signals. A MIMO separation section separates, using a MIMO scheme, the plurality of radio signals in accordance with the channel estimation values, and a compensation section compensates for channel variations of the plurality of radio signals. A selection section selects one of the MIMO separation section and the compensation section.

Abstract: When transmission is performed using the OFDM-CDMA method, subcarriers #1 through #m, #2m+1 through #3m, #3m+1 through #4m, and #4m+1 through #5m in which spread signals are allocated only in the frequency axis direction, and subcarriers #m+1 through #2m in which spread signals are allocated in both the frequency axis direction and the time axis direction, are formed, and these are transmitted simultaneously.

Abstract: A half cut portion is provided with a receiving base for receiving a tube, and a cutter for cutting the tube. The receiving base is provided with a stroke adjusting lever on an upper portion of the receiving base, and the stroke adjusting lever is provided with a cam face in which an amount of projecting is varied by being rotated. The cutter butts to the cam face and a depth of a half cut is set according to a displacement of the amount of projecting of the cam face from the receiving base.

Abstract: A control section (110) recognizes the type of data included in a transmission signal and outputs a control signal (C1) to an S/P conversion section (101) and a spreading control section (107). The S/P conversion section (101) apportions a specific type of data output from the control section (110) to different transmission systems. Spreading sections (102, 103) carry out spreading processing on the specific type of data output from the S/P conversion section (101) with different spreading codes assigned thereto under the control of the spreading control section (107). The data output from the spreading sections (102, 103) is transmitted by radio through addition sections (104-1, 104-2), transmission sections (105-1, 105-2) and antennas (106-1, 106-2). In this way, it is possible to improve the reception performance on the receiving side for specific data while maintaining the transmission efficiency of an MIMO communication system.

Abstract: A transmission apparatus and method turbo-encode data and output systematic bit and parity bit data. The systematic bit data and the parity bit data are modulated independently of each other such that communication quality is better when a modulation scheme for the systematic bit data is changed than when a modulation scheme for the parity bit data is changed. The systematic bit data and the parity bit data are then transmitted.

Abstract: A data retransmission method, providing a practical ARQ (Automatic Repeat request) scheme in multicarrier communication such as OFDM. According to this method, all the carriers (i.e. subcarriers) are divided into a number of groups in advance, and these groups serve as the unit of data retransmission. An error detection code is attached on a per transmission symbol basis and transmission is performed, and, when mobile terminal apparatus 100 at the receiving end detects an error, subcarrier information obtainer 130 counts the number of carriers having received level below predetermined standard on a per group basis, and makes the group having the count value above a threshold level subject to retransmission request.

Abstract: A control section (110) recognizes the type of data included in a transmission signal and outputs a control signal (C1) to an S/P conversion section (101) and a spreading control section (107). The S/P conversion section (101) apportions a specific type of data output from the control section (110) to different transmission systems. Spreading sections (102, 103) carry out spreading processing on the specific type of data output from the S/P conversion section (101) with different spreading codes assigned thereto under the control of the spreading control section (107). The data output from the spreading sections (102, 103) is transmitted by radio through addition sections (104-1, 104-2), transmission sections (105-1, 105-2) and antennas (106-1, 106-2). In this way, it is possible to improve the reception performance on the receiving side for specific data while maintaining the transmission efficiency of an MIMO communication system.