Abstract: A communication apparatus includes a receiving unit that receives a data frame including a plurality of pieces of unit data and transmitted from a communication partner; a determining unit that determines whether there is data loss, for each piece of unit data included in the data frame received by the receiving unit; a transmission right acquiring unit that acquires a transmission right; and a generating unit that generates grant data for granting the transmission right acquired by the transmission right acquiring unit to the communication partner, when the determining unit determines that at least any one of the pieces of unit data has been lost.

Abstract: Disclosed is a wireless communication apparatus which receives, by multiple antennas, signals created by spatially multiplexing multiple transmit streams subjected to power allocation. The wireless communication apparatus has a channel matrix estimator which estimates a channel matrix of spatially multiplexed channels, a spatial demultiplexer which obtains an antenna receive weight matrix from the estimated channel matrix and demultiplexes into multiple receive streams by multiplying receive signals of antennas by the antenna receive weight matrix, and a power estimator which estimates power allocation information as to each stream. In the wireless communication apparatus, the channel matrix estimator estimates a channel matrix in view of power allocation to each stream estimated by the power estimator.

Abstract: A radio communication network that requires no connection between base stations during handoff or when the cell is overloaded, is realized by using a receiver that has a multi-user detection function and a transmitter for synthesizing control information and user data to output the synthesized data. Upon reception of a signal that is transmitted from a mobile station located on the boundary with a neighboring cell, the base station synthesizes user data for a mobile station in its local cell and control information for controlling the handoff operation to transmit the synthesized data. In response to this transmission, a mobile station in the neighboring cell separates the control information by multi-user detection to detect the signal and transmits a handoff request to the base station.

Abstract: A transmission device transmits data to a certain communication device among multiple communication devices connected over a wireless network in wireless communication capable of using multiple transmission rates. The transmission device includes first transmitting means for transmitting a first packet to the certain communication device during a transmission inhibited period; receiving means for receiving a second packet including information indicating a communication environment at reception of the first packet at the certain communication device from the certain communication device; and second transmitting means for transmitting a third packet to the certain communication device at a transmission rate appropriate for the information that is included in the received second packet and that indicates the communication environment. The data length of the certain data included in the first packet is shorter than that of the data included in the third packet.

Abstract: A wireless communication apparatus having a wireless communication function capable of using a plurality of transmission rates. The wireless communication apparatus includes utilization-factor calculation means for calculating a utilization factor of a wireless transmission path through which wireless communication is performed using the wireless communication function; and determination means for determining a transmission rate at least on the basis of the utilization factor calculated by the utilization-factor calculation means.

Abstract: A scrambling initial value is shared without deteriorating transmission efficiency. On the transmission side, a scrambling initial value is created based on a part of a physical layer header not scrambled, a transmission signal sequence scrambled is created by calculating an exclusive-OR operation between a scrambled sequence generated from the scrambling initial value and a transmission data sequence, and is transmitted. On the reception side, the same descrambling initial value as the scrambling initial value is created based on a part of a physical header of a reception frame, and a reception data sequence is descrambled by calculating an exclusive-OR operation between a descrambled sequence generated from this descrambling initial value and a reception signal sequence scrambled.

Abstract: Disclosed is a wireless communication apparatus which receives, by multiple antennas, signals created by spatially multiplexing multiple transmit streams subjected to power allocation. The wireless communication apparatus has a channel matrix estimator which estimates a channel matrix of spatially multiplexed channels, a spatial demultiplexer which obtains an antenna receive weight matrix from the estimated channel matrix and demultiplexes into multiple receive streams by multiplying receive signals of antennas by the antenna receive weight matrix, and a power estimator which estimates power allocation information as to each stream. In the wireless communication apparatus, the channel matrix estimator estimates a channel matrix in view of power allocation to each stream estimated by the power estimator.

Abstract: A radio communication network that requires no connection between base stations, for example, during handoff or when the cell is overloaded, is realized by using a receiver that has a multi-user detection function and a transmitter for synthesizing control information and user data to output the synthesized data. Upon reception of a signal that is transmitted from a mobile station located on the boundary with a neighboring cell, a base station synthesizes user data for a mobile station in its local cell and control information for controlling handoff operation to transmit the synthesized data. In response to this transmission, a mobile station in the neighboring cell separates the control information by multi-user detection to detect the signal and transmits a handoff request to the base station.