Abstract: A radio communication system having a radio transmitter and a radio receiver and adopting multiple carrier modulation and code spreading modulation methods is disclosed. The radio communication system comprises a selecting unit provided in the radio transmitter or the radio receiver, for selecting an interleaving mode out of plural interleaving modes depending on radio propagation path conditions; a symbol configuration unit provided in the radio transmitter; and a symbol reconfiguration unit provided in the radio receiver. The symbol configuration unit configures information symbols to be transmitted by the radio transmitter in both time and frequency directions in a pattern according to the interleaving mode selected by the selecting unit, and the symbol reconfiguration unit reconfigures information symbols received by the radio receiver in both time and frequency directions in an inverse pattern of the pattern.

Abstract: A signal reception device is disclosed that is capable of detecting symbol synchronization timing with high precision in accordance with a condition of a propagation path even in an environment involving multi-path interference. The signal reception device adopts an OFCDM transmission scheme or a multi-carrier transmission scheme. The signal reception device includes a received signal information calculation unit to calculate received signal information representing a signal reception condition of a received signal; an output combination unit to combine correlation values in a predetermined section obtained by correlation detection based on the received signal information; and a symbol timing detection unit to detect a symbol synchronization timing based on the combined value.

Abstract: A wireless communications system includes a base station and multiple mobile stations performing wireless communication with the base station in a DS-CDMA scheme. Each of the mobile stations has a transmission unit configured to transmit a timing difference detection packet to the base station, prior to transmitting packet data. The base station has a transmission timing control unit configured to detect a difference in signal receive timing from the mobile stations based on the timing difference detection packet, produce transmission timing control information for each of the mobile stations based on the detection result, and supply the transmission timing control information to each of the mobile stations to cause the mobile stations to adjust the transmission timing of the packet data.

Abstract: A mobile station that wirelessly transmits to a base station by DS-CDMA a signal spread by multiplying a spreading code includes a chip-pattern generating unit that generates a predetermined chip pattern by performing chip repetition for a predetermined number of repetitions to a spreading chip sequence, and a multiplying unit that multiplies to a signal including the predetermined chip pattern generated by the generating unit a phase specific to the mobile station.

Abstract: A communication device includes at least one of path search means for detecting respective timings of path components included a signal received via a multipath propagation path using pilot symbols of a known phase included in said received signal and channel estimation means for estimating channel variation using the pilot symbols. The path search means includes a first path search part for detecting respective timings of path components using pilot symbols and a second path search part for detecting respective timings of path components using information symbols derived from a signal demodulated according to the timings detected in the first path search part and pilot symbols. The channel estimation means includes a pilot symbol acquiring part for acquiring pilot symbols included in the received signal and a channel estimation part for implementing channel estimation using the acquired pilot symbols.

Abstract: With the object of efficiently transmitting a variety of different information signals by utilizing the multi-carrier characteristics of Multi-carrier/DS-CDMA, the present invention is characterized in that, when, in an uplink transmission from a plurality of mobile stations to a base station, the mobile stations transmit a preamble to the base station before transmitting an information symbol sequence, the mobile stations individually select a carrier from among a plurality of carriers, and, up until receiving a preamble receipt confirmation signal from the base station with a prescribed maximum number of preamble transmissions serving as an upper limit number; the mobile stations repeatedly transmit a preamble by means of the selected carrier and vary the transmission power used for the transmissions of each carrier.

Abstract: The object of the present invention is to prevent continued reception of unreliable information symbols at the receiver apparatus 200 in the OFCDM radio communication system, so that it is possible to improve transmission quality. The radio communication system according to the present invention comprises a transmitter apparatus 100 configured to estimate conditions of propagation paths used in the radio communication, arrange information symbols along the direction of the frequency axis in accordance with a predetermined pattern based on the estimated conditions of propagation paths, and transmit a radio communication signal including the arranged information symbols and a receiver apparatus 200 configured to receive the radio communication signal, and rearrange the information symbol included in the radio communication signal along the direction of the frequency axis in accordance with a reverse pattern to the predetermined pattern.

Abstract: The object of the present invention is to provide a transmitter for multi-carrier transmission for allocating pilot channels to radio frames, in consideration of interference with other pilot channels.

Abstract: An object is to implement transmission by an appropriate transmission method according to a type of information even in application of directional beam transmission.

Abstract: A mobile communication system 1 according to the present invention comprises base station 30 and mobile station 10. The base station 30 sends a pilot symbol sequence known to the mobile station 10, to the mobile station 10, using a plurality of carriers for downward channels, and performs communication with the mobile station 10 while multiplying the channels by frequencywise same scrambling codes every symbol period. The mobile station 10 is provided with a peak detector 17 for calculating cross correlation allowing for a phase difference of the scrambling codes, between frequencywise pilot symbol sequences received from the base station 30, thereby detecting a radio frame boundary.

Abstract: A receiver, comprising a plurality of antennas configured to receive signals that are obtained by multiplying a plurality of data symbols transmitted over a plurality of data channels using spreading codes for each of the data channels, the data symbol being transmitted over a plurality of sub-carriers having different frequencies; a spreading code multiplier configured to multiply reception signals received by the plurality of antennas using spreading codes for the data channels corresponding to the reception signals; a weight controller configured to adjust antenna weights by which a reception signal received by each antenna is to be multiplied, and sub-carrier weights by which a reception signal received over each sub-carrier is to be multiplied; a weight multiplier configured to multiply the reception signals by the antenna weights and the sub-carrier weights adjusted by the weight controller; and a combining unit configured to combine the reception signals multiplied by the antenna weights and the sub-ca

Abstract: The transmission system of the present invention is designed to transmit a plurality of signals between the transmitter and the receiver using a plurality of carriers and comprises a radio link characteristics estimator 4 configured to estimate the characteristics of a radio link between the transmitter and the receiver and a carrier quantity determination unit 3 configured to determine the number of carriers according to the result of the estimate by the radio link characteristics estimator 4. The radio link characteristics estimator 4 estimates the characteristics according to an interval in delay time of multipath signals and the number of the multipath signals. The carrier quantity determination unit 3 determines fewer carriers when multipath interference is small, and determines more carriers when the multipath interference is great.

Abstract: A radio transmission system is configured to, on the occasion of radio transmission of information between a transmitter and a receiver, perform the radio transmission of information using an orthogonal frequency and code division multiplexing transmission scheme of parallelly transmitting identical information by a plurality of sub-carriers. The radio transmission system has a spreading factor variable control transmitting device for parallelly converting information channel-coded at the transmitter, according to symbols transmitted simultaneously, and for spreading a sequence of parallelized symbols in at least one of a frequency direction and a time direction by a spreading code sequence of a designated spreading factor.

Abstract: Received signals of the respective sub-carriers are multiplied by a weighting controlled for each sub-carrier, using a weighting control part 2-8 and multipliers 2-9, so that the mean square error between the signals following despreading and the signals that are actually transmitted is minimized. Afterward, MMSE combining is performed.

Abstract: The present invention is directed to a channel structuring method that includes a step of providing time frames segmented at a predetermined interval in communication channels of n subcarriers, a step of selecting a predetermined number of subcarriers from n subcarriers and a step of inserting a common control channel signal and a common pilot signal periodically into each of the time frames of the selected subcarriers.

Abstract: The present invention provides a single carrier/DS-CDMA packet transmission method wherein a predetermined time slot is assigned to reservation demand packet transmission in regard to a spreading code, and the reservation demand packet and data packets are time-multiplexed for transmission. An uplink packet transmission method in a multi-carrier/DS-CDMA mobile communication system is also provided, wherein frames are set up in each communication channel of a subcarrier, time slots which are time-segments of the frames are set up further, and a mobile station spreads a packet to be transmitted by a spreading code and the information signal is transmitted to a base station in a predetermined time slot.

Abstract: A multi-carrier CDMA transmission system signal format that reproduces data symbols, aligns the reproduced data symbols along a frequency axis, multiplies the reproduced data symbols by a spreading code, and conducts multiplex transmission of data using a plurality of sub-carriers of different frequencies, in which a common pilot symbol inserted in a transmission signal for estimating a variation in channel and estimating a channel common to each of a plurality of users, and a user-specific individual pilot symbol transmitted along a channel different from the above-described channel.

Abstract: A communication method includes the steps of: a) transmitting an ACK signal indicating a received packet includes no error or a NACK signal indicating the received packet includes error from a reception end to a transmission end, and performing automatic repeat request; b) obtaining reliability of the received packet when demodulating it at the reception end; and c) reporting from the reception end to the transmission end the reliability of the received packet utilizing the ACK/NACK signal by using not less than three levels.

Abstract: A multi-carrier CDMA radio transmitting method replicates each information symbol and disposes thus-obtained information symbols along a frequency axis, multiplies the thus-obtained information symbols with a spreading code along the frequency axis, spreads the information symbols into components of a plurality of sub-carriers having different frequencies. The transmission rate of the information is changed by controlling the amount of information transmitted simultaneously by controlling the number of the information symbols to be used for spreading for the plurality of sub-carrier components for each user to which the information is to be transmitted.