Abstract: A base station device according to the present invention includes: a first reception weight calculator 122 configured to calculate weight of each antenna element of an array antenna 114 to be used in communications with a first mobile station device by using a reference signal transmitted from the first mobile station device; and a second reception weight calculator 124 configured to calculate weight of each antenna element of the array antenna 114 to be used in communications with a second mobile station device, which is different from, the first mobile station device of the multiple mobile station devices, the second reception weight calculator 124 calculating the weight so that null can be directed to an arriving direction of the reference signal transmitted from the first mobile station device, the arriving direction being determined on the basis of weight calculated by the first reception weight calculator 122.

Abstract: There is provided a wireless communication method, a wireless communication system, a base station and a mobile station which conduct wireless communication using an OFDM modulation scheme. The base station transmits a timing correction burst to the mobile station only when a correlation peak detected from a received OFDM symbol is within a predetermined timing detection range. If the timing correction burst is not introduced from the base station even after expiration of predetermined time duration, by copying a signal by a length different from a guard interval from the end of an effective symbol and adding the copied signal to the front of the effective symbol, the mobile station generates a new timing correction channel (second time), in which transmission timing of a previously generated timing correction channel is shifted.

Abstract: A communication system using an OFDM includes a data creation section for coding data to be transmitted and mapping the data, a null symbol insertion section for filling a null symbol into a no-data subchannel if the number of subchannels containing the mapped data is small for the band assignment, and a symbol interleave section for performing symbol interleave in the whole user assignment band and inserting a known training symbol and pilot symbol into the determined symbol position of the user assignment band are included and symbols are placed such that signal phase change is continuous in the same subcarrier between symbols and carrier sense is executed at the positions of the symbols where the signal phase change is continuous.

Abstract: Provided are a new frame synchronization method, which is capable of shortening the time necessary for frame synchronization between a receiver and a base station of PHS based on an OFDM communication system, and the receiver therefor. A frame synchronization method of OFDM communication system includes: a symbol synchronization step of obtaining a synchronization timing for each OFDM symbol by executing calculation of correlation in the symbols on the basis of an autocorrelation factor included in each OFDM symbol transmitted from wireless base stations; a unique symbol correlation search stop of obtaining timing of a notification channel by executing calculation of correlation for a unique symbol included in the notification channel; and a notification channel decoding step of executing decoding of the notification channel or a channel synchronized with the notification channel on the basis of timing when a degree of correlation obtained by the unique symbol correlation search is highest.

Abstract: An OFDM communication device (10) includes: an REF/IF/BR unit (11) for receiving a series of symbols; a frequency fluctuation amount information acquisition unit (21) for acquiring frequency fluctuation amount information that indicates a frequency fluctuation amount of the received series of symbols; and a GI length determination/instruction unit (23) for determining a GI length in accordance with the frequency fluctuation amount information acquired by the frequency fluctuation amount information acquisition unit (21), and instructing a transmission device to transmit symbols with the determined GI length.

Abstract: A base station includes: a MIMO preceding section (32) for converting transmission data addressed to a mobile station to two data streams that respectively correspond to two reception antennas included in the mobile station, by performing MIMO precoding on the transmission data; a weight calculating section for calculating a transmission weight to be used for forming a directivity pattern directed toward each of the two reception antennas; and a weighting/combining section (34) for generating two combined data streams that are to be supplied to the respective antennas (20-1 and 20-2), by weighting each of the two data streams with the transmission weight calculated with respect to the reception antenna of the mobile station that corresponds to the data stream, and combining the two weighted data streams for each of the antennas (20). The two combined data streams are respectively transmitted from the antennas (20-1 and 20-2).

Abstract: A base station includes: a MIMO precoding section (32) for converting transmission data addressed to a mobile station to two data streams that respectively correspond to two reception antennas included in the mobile station, by performing MIMO precoding on the transmission data; a weight calculating section for calculating a transmission weight to be used for forming a directivity pattern directed toward each of the two reception antennas; and a weighting/combining section (34) for generating two combined data streams that are to be supplied to the respective antennas (20-1 and 20-2), by weighting each of the two data streams with the transmission weight calculated with respect to the reception antenna of the mobile station that corresponds to the data stream, and combining the two weighted data streams for each of the antennas (20). The two combined data streams are respectively transmitted from the antennas (20-1 and 20-2).

Abstract: In a communication system and a communication method using a TDD-OFDMA communication method, inter-carrier interference due to delay dispersion is prevented by suppressing the delay time within a guard interval.

Abstract: A base station apparatus which conducts a packet communication with a wireless communication terminal includes: a retransmission request detection unit which detects a retransmission request from the wireless communication terminal; a bandwidth assignment unit which assigns a communication bandwidth applied to the packet communication; a modulation class calculation portion, based on both bandwidth information regarding the bandwidth assigned by the bandwidth assignment unit and a data amount of packets corresponding to the retransmission request, calculates a modulation class applied to a retransmission in order to adjust a number of retransmitted packets to be the same as a number of previously transmitted packets; a modulation class determination unit which determines whether or not the modulation class is lower than a modulation class applied to a previous packet transmission; and a retransmission unit which retransmits packets corresponding to the retransmission request based on the determination result

Abstract: A communication system includes: an RF/IF/BB unit (21) for receiving, in a mobile station device (20), a transmission signal from a base station device; a received power calculation unit (221) for obtaining received power thereof; a communication rate modification unit (23) for changing a communication rate by changing a modulation scheme used by the base station device to modulate the transmission signal in a predetermined case; and a communication rate increase limit unit (27) for limiting the communication rate to be increased by the communication rate modification unit (23), according to received power required for the mobile station device (20) to demodulate the transmission signal and according to the received power obtained when receiving the transmission signal after the communication rate is changed by the communication rate modification unit (23) and predicted based on the received power obtained by the received power calculation unit (221) and based on a decrease amount of a transmission power of a

Abstract: A communication system includes: an RF/IF/BB unit (21) for receiving, in a mobile station device (20), a transmission signal from a base station device; a received power calculation unit (221) for obtaining received power thereof; a communication rate modification unit (23) for changing a communication rate by changing a modulation scheme used by the base station device to modulate the transmission signal in a predetermined case; and a communication rate increase limit unit (27) for limiting the communication rate to be increased by the communication rate modification unit (23), according to received power required for the mobile station device (20) to demodulate the transmission signal and according to the received power obtained when receiving the transmission signal after the communication rate is changed by the communication rate modification unit (23) and predicted based on the received power obtained by the received power calculation unit (221) and based on a decrease amount of a transmission power of a

Abstract: Provided are a radio communication system, a transmission device, and a communication signal transmission method, which enable a reception device to correctly demodulate a communication signal without performing a feedback of a propagation path characteristic from the reception device to the transmission device.

Abstract: To realize prompt and efficient data communication by dynamically changing the optimum MCS and PC. A base station (120) serving as a wireless communication device according to the present invention includes an obtaining unit (220) for obtaining an RSSI and an SINR of a receive signal upon generation of transmission data to be sent to a PHS terminal (110) serving as a wireless communication device to communicate with; a modulation and coding scheme determining unit (224) for determining an MCS, based on the volume of the transmission data; a transmission power determining unit (226) for determining a transmission power, based on the volume of the transmission data, the RSSI, the SINR, and the MCS determined; and a wireless communication unit (214) for sending the transmission data, using the MCS determined and the transmission power determined.

Abstract: One of the objects of the present invention is to more completely avoid impossibility of access between a mobile station and a base station, in wireless communication using an OFDM (Orthogonal Frequency Division Multiplexing) modulation scheme. In one embodiment, a base station removes a guard interval from an OFDM symbol received from a PHS terminal through a timing correction channel at two different timings to obtain two effective symbols, calculates a timing correction amount by including one timing, at which an guard interval is removed for the effective symbol that has caused detection of one correlation peak within a predetermined timing detection range of two correlation peaks detected from the respective effective symbols, into a differential from reference timing of the base station at the time of detection of the one correlation peak, and transmits the timing correction amount to the PHS terminal by means of a timing correction burst.

Abstract: A mobile station (12) includes an AGC unit (24) for controlling the received power of a communication signal sent from a base station via at least one of the subchannels, based on the maximum received power of a signal received together with the communication signal by any of the subchannels; a received power difference detecting unit (30) for detecting the received power difference between the maximum received power of a signal sent from the base station and the maximum received power of a signal arriving from a device different from the base station; and a modulation and coding scheme determining unit (38) for determining a modulation and coding scheme for a new communication signal to be sent from the base station, based on the signal quality of the communication signal subjected to received power control by the AGC unit (24) and the received power difference detected.

Abstract: A wireless communication system which performs packet communication in a time division multiplexing communication format between wireless communication devices using either one or a plurality of communication channels includes: a resend request unit which detects that a received packet contains an error and requests a resend; a resend request detection unit which detects the request for a resend; a packet resend unit which resends the packet in accordance with the request for a resend detected by the resend request detection unit; and a channel allocation unit which allocates a different communication channel for the packet resend unit to resend the packet from the communication channel which was used for sending the packet in which the error detected by the resend request unit was contained.

Abstract: One object of the present invention is to more completely avoid impossibility of access between a mobile station and a base station, in wireless communication using an OFDM (Orthogonal Frequency Division Multiplexing) modulation scheme. In one embodiment, a PHS terminal generates a timing correction channel (first time) to be frame synchronized with a notification channel. A base station transmits a timing correction burst to the PHS terminal only when a correlation peak detected from a received OFDM symbol is within a predetermined timing detection range. If the timing correction burst is not introduced from the base station even after expiration of predetermined time duration, the PHS terminal generates a new timing correction channel (second time), in which transmission timing of a previously generated timing correction channel is shifted.

Abstract: A mobile station which performs a handover from a base station to a base station calculates the transmission loss of a broadcast control channel sent from the target base station, and corrects the transmission power of an uplink ANCH to the target base station, based on a known base station desired receive power and the calculated transmission loss. Alternatively, the mobile station may correct the transmission power of the uplink ANCH to the target base station, based on the transmission power of an uplink signal to the serving base station, the transmission loss of a downlink signal sent from the serving base station, and the transmission loss of a broadcast control channel sent from the target base station.

Abstract: A mobile station which performs a soft handover from a serving base station to a base station in which frame synchronization is established in the uplink direction with the base station calculates the time difference between the receive timing of a downlink signal sent from the base station and the receive timing of a broadcast control channel sent from the base station at S100 to use as a timing correct amount, and corrects the transmission timing of an uplink ANCH to the base station, based on the transmission timing of an uplink signal to the base station and the time difference calculated at S126, to thereby establish frame synchronization in the uplink direction with the base station.

Abstract: A mobile station (12) includes a transmission loss calculator (32) for calculating the transmission loss of a broadcast signal sent from a base station and a transmission power controller (34) for controlling the transmission power of an uplink signal to the base station, based on a known base station desired receive power and the transmission loss calculated by the transmission loss calculator (32).