Abstract: A repeating station, a communication apparatus, and an antenna directivity control method are disclosed. The repeating station includes a first antenna group including at least one antenna element, a second antenna group that is different from the first antenna group, the second antenna group including two or more antenna elements adjusted so that radiation in the direction of the first antenna group is reduced, wherein the second antenna group is adjusted such that radiated power in the direction of the first antenna group is reduced.

Abstract: A wireless positioning apparatus (10, 30, 50) includes a multipath delay estimator (11) configured to estimate multipath delay components from one or more received signals; a selector (13, 53) configured to select appropriate delay estimates from the estimated multipath delay components according to a predetermined criterion; a storage (15, 55) configured to store an NLOS delay function defining prior (statistics of) information about non-line-of-sight delays; and a position estimator (17, 57) configured to estimate a position of a mobile station based on the selected delay estimates and the NLOS delay function read out from the storage.

Abstract: A radio communication system including a transmitter and a receiver (100) for transmitting MIMO channel signals is provided. The transmitter comprises a pilot signal insertion controller (93) for inserting a pilot signal for channel estimation into at least a leading frame; and an information symbol controller for controlling the number of information symbols to be contained in a frame, based on the existence of the pilot signal. The receiver comprises a received signal replica generator (112) for generating received signal replicas based on previously obtained provisional channel estimation values and transmission signal estimation values; a canceller (111) for removing, from a received signal, received signal replicas of at least a part of streams that are not channel estimation target streams; and a channel estimation value generator (113) for generating channel estimation values by a filter using outputs from the removing unit and the transmission signal estimation values.

Abstract: An OFDM transmitter (100) is disclosed. The OFDM transmitter comprises: a sorter (103-1) for sorting plural input complex signals and partitioning them into plural groups; plural IFFTs (103-2) for performing inverse Fourier transform on the input complex signals in groups; a peak reducer (103-4) for performing peak reduction, based on outputs from at least one of the IFFTs; and a multiple discrete signal generator (103-5) for generating a designated number of discrete signals from outputs of the peak reducer.

Abstract: A transmitter has a peak reducing part carrying out peak reduction processing; an OFDM signal generating part generating an OFDM signal from an input information signal; a cyclic shifting part generating a signal obtained from cyclically shifting the OFDM signal; and an adding part adding the OFDM signal and the cyclically shifted signal together.

Abstract: A transmission apparatus used in a radio communication system adopting the OFDM scheme is disclosed. The transmission apparatus includes: a dividing inverse Fourier transform part including plural transform parts, wherein the dividing inverse Fourier transform part divides a signal to be transmitted into plural signals, and each of the plural transform parts performs inverse Fourier transform on one of the plural signals; a peak control part for outputting a peak control signal based on peaks that are detected from output signals of the dividing inverse Fourier transform part; and a peak reducing process part for adjusting a weight or an arranging order of an output signal of the dividing inverse Fourier transform part according to the peak control signal to output an adjusted signal, and synthesizing the adjusted signal with other signal so as to output a synthesized signal.

Abstract: An ID tag for RF transmitting its own tag ID information is disclosed. The ID tag comprises an ID storage for outputting the tag ID information stored therein; an ID concealing unit that conceals the tag ID information based on a certain value relating to time and outputs a concealed ID; a time information concealing unit that conceals the certain value based on a stored tag unique value and outputs concealed information; and a data outputting unit that receives and combines the concealed ID and the concealed information, and outputs combined data.

Abstract: A communication apparatus in a radio transmission system in which plural first communication apparatuses sends the same transmission signals and a second communication apparatus receives the transmission signals is disclosed. The communication apparatus functions as one of the plural first communication apparatuses, and the communication apparatus includes: a detection part for detecting a start or a stop of data transmission performed by a first communication apparatus that is different from the communication apparatus; and a guard interval length control part for controlling a guard interval length on the basis of a detection result of the detection part.

Abstract: In a transmission power control method of the present invention, a value of a received signal quality parameter of a received multicast signal is measured. A parameter signal, indicating the received signal quality parameter value, is transmitted from a plurality of mobile stations to a base station through a radio link. The parameter signals from the mobile stations are received at the base station through the radio link. A power control value of each of the mobile stations is determined based on the received signal quality parameter values of the received parameter signals. The transmission power of the multicast signal, sent to each of the mobile stations, is controlled based on the determined power control value.

Abstract: A locating system for determining a position of an object comprises a transmitting station that transmits a first ID signal containing a first identifier of this transmitting station; a receiving station that receives the first ID signal, measures the intensity of the first ID signal, and extracts the first identifier; a data management unit that stores and manages the intensity in association with the first identifier, the intensity and the identifier being supplied from the receiving station; and a positioning computer that estimates the position of the transmitting station using a first correcting formula defining a relation between the intensity and the distance, based on the data stored in the data management unit.

Abstract: A radio relay system is disclosed that is capable of preventing communication degradation in a case where radio signals are relayed using the same frequency band in a mobile communication environment. The radio relay system includes a first radio station, a second radio station, and a radio relay apparatus for relaying a radio signal that is exchanged between the first radio station and the second radio station. The radio relay apparatus includes a phase correction determining unit that determines a phase correction amount of the relayed signal based on channel information pertaining to channels established between the first radio station, the second radio station, and the radio relay apparatus, and a phase correction unit that corrects the relayed signal based on the phase correction amount determined by the phase correction determining unit.

Abstract: A wireless relay system for relaying a radio signal transmitted from a first wireless station to a second wireless station via a wireless relay apparatus is disclosed. The wireless relay system includes a relay control part for receiving transmission symbols transmitted from the first wireless station and refraining from relaying a portion of the symbols, a pilot signal transmission part for transmitting a pilot signal that is inserted into a section of the portion of the transmission symbols, a coupling loop interference wave estimation part for receiving the pilot signal and estimating a coupling loop interference wave based on the pilot signal, and a coupling loop interference wave cancellation part for subtracting the estimated coupling loop interference wave from a reception signal.

Abstract: Each radio station can manage a plurality of channels, and functions both as a master station which controls transmission in each channel and a slave station which operates under control of a master station. In case of a master station, it transmits a signal under control of the own station, and in case of a slave station, it transmits a signal under control of the master station. Each radio station can communicate with any other radio station either directly or through another radio station. In each channel, communication is carried out in time division of centralized control access phase and distributed control access phase. A master station in case of centralized control access phase is determined in each channel and in each link.

Abstract: A received-signal combining method of transmitting a signal, based on a signal having undergone error-correction coding and transmitted from a radio-transmitting station, to a receiving station from a plurality of radio-receiving stations, and generating a reception-information sequence based on the thus-transmitted signal by the receiving station, comprises the steps of: each radio-receiving station rendering error-correction decoding and error detection processing on the signal transmitted from the radio-transmitting station, and transmitting the error-correction-decoding result to the receiving station when no error is detected by the error detection processing; and the receiving station combining the received error-correction-decoding result according to a first algorithm when receiving the error-correction-decoding result from any radio-receiving station, and, thus, generating the reception-information sequence.

Abstract: This invention provides an MIMO communication system and MIMO communication method. An MIMO receiver estimates state of each communication channel from the received signals received by #1 to #L antennas, generates feedback information according to the information of channel state, sends the feedback information to a transmitter through a feedback path, processes the feedback information in order to compensate feedback-delay of the feedback path, generate K*L proper reception weights by using the information of channel state and processed feedback information, multiplies the received #1 to #L substreams of respective #1 to #K signal streams by the proper #1 to #L reception weights, respectively, composes the #1 to #L weighted substreams to obtain respective composed #1 to #K signal streams and demodulate the composed #1 to #K signal streams, respectively, and combines the demodulated K signal streams to reproduce an original transmission signal.

Abstract: An OFDM receiver receives an OFDM signal transmitted from an OFDM transmitter by using a sub-carrier. The OFDM receiver includes a channel estimator configured to obtain a channel estimated value of each multi-path based on OFDM signals received through a plurality of multi-paths; a transmission signal estimated value calculator configured to calculate a transmission signal estimated value as an estimated value of the OFDM signal; and an inter-carrier interference compensator configured to extract a multi-path not becoming a form to contain a signal component only of a target symbol in an FFT window based on the transmission signal estimated value and the channel estimated value of each multi-path, and to compensate for inter-carrier interference in the OFDM signal based on signal components corresponding to all sub-carriers of the multi-paths.

Abstract: A channel capacity is increased by using MIMO (multiple input multiple output) radio relaying system. A transmission is made from a transmitter 10 using a first antenna 111 and a second antenna 112 having polarization characteristics which are orthogonalized to each other. A reception is made in a repeater 201 using reception antennas 211 and 212 each having the same polarization characteristic as the first and the second antenna 111 and 112, respectively. Each signal received by the first and the second reception antenna 211 and 212, respectively, is passed through loop interference suppressors 271 and 272, respectively, and through amplifiers 241 and 242, respectively, to be transmitted from the first and the second transmission antenna 211 and 212 having the same polarization characteristics as the second and the first antenna 112 and 111, respectively.

Abstract: An OFDM transmitter transmits an OFDM signal by a frame having a plurality of transmission symbol periods constituted of an effective symbol period for transmitting an information bit and a guard interval. The OFDM transmitter includes a guard interval length decider configured to decide a guard interval length in accordance with a feedback signal from an OFDM receiver; and a guard interval length changer configured to change a guard interval length in each transmission symbol period, in accordance with a decided guard interval length without changing a frame length.

Abstract: An object of the present invention is, in a communication path of which received signal quality is extremely poor, to prevent such a state of the communication failure. To a frame generator 13 in a transmitter 10, which transmits OFDM signal, a pilot & data arrangement format determiner 20, which determines pilot & data arrangement format of an OFDM signal based on the value of received signal quality at a receiver 30, a pilot symbol number determiner 19, which determines the number of pilot symbols based on the value of received signal quality, and a power amplification rate determiner 18, which determines power amplification rate based on the value of received signal quality, are newly provided. Thereby, it is possible to change the pilot & data arrangement format, the number of pilot symbols and the power amplification rate depending on the value of received signal quality to generate transmission signal frame of the OFDM signal.

Abstract: A radio receiver includes a plurality of antenna elements for receiving a radio signal from a radio transmitter; a setting part changing an impedance of at least one of the plurality of antenna elements according to an instruction signal; a measuring part measuring a change in throughput in a received signal caused due to the change in the impedance; and an instruction part providing the instruction signal which is changed in response to the measurement result.