Abstract: A clock recovery circuit capable of fast and accurate clock phase locking even in the presence of frequency shift and noise. The input signal includes, in order, a preamble with an alternating bit sequence pattern, a unique word and data. A detection unit detects zero crossings and measures the time interval therebetween. A 1-interval judgment unit judges whether an interval signal is within a predetermined range, and a 2-interval judgment unit sums two adjacent interval signals and judges whether the 2-interval signal is within a predetermined range. A control unit controls a zero-crossing signal based on the judgment result and outputs a valid zero-crossing signal if judged in the affirmative. A switching unit switches between outputting the zero-crossing signal and the valid zero-crossing signal as valid phase error information based on a frame reception signal input from a frame detection unit. A clock generation unit uses the valid phase error information in generating a symbol clock.

Abstract: A wireless station capable of increasing the probability that a path diversity effect can be obtained in a case where a plurality of wireless stations transmit packets using a modulation/demodulation scheme with an anti-multipath property. A delay amount determining section (48) randomly selects a delay amount from among a plurality of candidate values. A transmission timing control section (47) determines a transmission start timing, at which to start the packet transmission, to be a timing obtained by delaying a reference timing by the delay amount selected by the delay amount determining section. At the transmission start timing, a modulation section (49) transmits the packet via an RF section (42) and an antenna (41). The difference between the candidate values is greater than or equal to a predetermined delay resolution, and the difference between a maximum candidate value and a minimum candidate value is less than or equal to a predetermined maximum delay.

Abstract: Provided is a wireless communication system capable of transmitting, at a high speed, information requested by a wireless communication terminal to the wireless communication terminal which moves through a spot wireless area at a high speed. In a wireless base station 101, an external information communication control section 102 controls communication with a server. A contents memory section 122 stores therein at least a part of contents received from the server. A wireless LAN communication section 105 communicates with the communication terminal in accordance with a predetermined communication method. A control section 104 establishes connection with the communication terminal by using a first connection which does not require an authentication procedure for connection with the communication terminal, or by using a second connection which requires the authentication procedure for connection with the communication terminal.

Abstract: Provided is a wireless communication system capable of transmitting, at a high speed, information requested by a communication terminal to the communication terminal which moves through a spot wireless area at a high speed. In an integrated base station 101, an external information communication section 102 controls communication with a server. A contents memory section 122 stores therein at least a part of contents received from the server. A wireless LAN communication section 105 communicates with the communication terminal in accordance with a predetermined communication method. A control section 104 establishes connection with the communication terminal by using a first connection which does not require an authentication procedure for connection with the communication terminal, or by using a second connection which requires the authentication procedure for connection with the communication terminal.

Abstract: A base station 2 demodulates a wireless signal after downconverting the signal to a low-frequency signal whose center frequency is fi [Hz] and oversampling the signal. A mobile station 3 demodulates a wireless signal after downconverting the signal to a low-frequency signal whose center frequency is fd [Hz] and undersampling the signal. The same sampling frequency fs [Hz] is used in the base station 2 and in the mobile station 3. The sampling frequency fs [Hz] is set to a value that is an even-number multiple of a wireless symbol transmission rate such that oversampling is done in the base station 2 and undersampling is done in the mobile station 3. The center frequency fi [Hz] is ½ to 1 times a frequency corresponding to the bandwidth and is ½N (N is a natural number) times the sampling frequency fs [Hz].

Abstract: The present invention provides a wireless transmission system capable of exerting a maximum path diversity effect by using combinations formed by a plurality of symbol waveforms even when a maximum number of effective branches is limited to a small number. A transmission timing controlling section (23) determines a timing delayed from a reference timing by a predetermined delay amount as a transmission start timing. A modulating section (21) modulates a signal, by using one symbol waveform among a plurality of symbol waveform candidates, utilizing a modulation scheme in which a phase transition of a symbol waveform, which exerts an anti-multipath property by demodulating the signal on the receiving side, represents a waveform being changed, and then transmits the modulated signal at a transmission start timing.

Abstract: A wireless station according to the present invention is a wireless station used as one of a plurality of relay stations forming transmission paths, respectively, different from each other, in a wireless transmission system for transmitting a packet from a transmitting station to a receiving station through the plurality of relay stations, and the wireless station comprises: a reception section for receiving a packet transmitted from the transmitting station, and receiving a packet which is transmitted, based on the packet transmitted from the transmitting station, from a relay station other than the one of the plurality of relay stations, and is transmitted before the one of the plurality of relay stations performs transmission, by using a transmission parameter for obtaining a path diversity effect in the wireless transmission system; a transmission parameter estimation section for estimating the transmission parameter used by the relay station other than the one of the plurality of relay stations, based on

Abstract: A delay section delays a detected signal by less than one bit time in the NRZ data. A subtraction section performs subtraction between a delayed signal and the detected signal, and outputs a resultant signal. A clock extraction section extracts, from crossing points of a subtracted signal, crossing points whose time interval is more than or equal to (Tb??) and less than or equal to (Tb+?) (wherein 0<??Tb/8, 0<??Tb: Tb is one bit time in the NRZ data), and outputs a synchronous signal synchronized with the extracted crossing point. A clock recovery section synchronizes a clock signal with the phase of the synchronous signal, and outputs a data clock signal. A determination section determines the polarity of the subtracted signal outputted from the subtraction section in accordance with the data clock signal, and outputs the determination result as the NRZ data.

Abstract: A transmission device (100) includes a differential encoding section (101) for differentially encoding transmission data, a first waveform generation section (102), a second waveform generation section (103), and two transmission antennas (109 and 110). A reception device (140) includes a reception antenna (141), a delay detection section (144), and a data determination section (145) for low-pass filtering a delay detection signal. The reception device (140) receives modulated signals modulated by using two wave forms having low correlations with each other. Thus, regardless of the presence or absence of delay dispersion in a propagation path and even in a high-speed fading in which the propagation path varies at high speed, a transmission diversity effect can be achieved, thereby making it possible to improve transmission characteristics.

Abstract: A first signal generation section 11 generates a baseband modulation signal for an ASK modulation scheme from transmission data. A second signal generation section 12 generates a pair of baseband modulation signals for a non-ASK modulation scheme from transmission data. When performing non-ASK modulation, a switch 15 connects between an input terminal d and an output terminal and outputs the baseband modulation signals based on the non-ASK modulation. When performing ASK modulation such that the transmission power ratio of the ASK modulation scheme to the non-ASK modulation scheme is a factor of 1, a switch 14 connects between an input terminal b and an output terminal and the switch 15 connects between an input terminal c and the output terminal. When performing ASK modulation such that the transmission power ratio is a factor of 2, the switch 14 connects between an input terminal a and the output terminal and the switch 15 connects between the input terminal c and the output terminal.

Abstract: In a wireless communication system using the contention method, collisions between transmission signals sent from terminals to a base station are avoided, and a communication area is flexibly formed while suppressing unnecessary radiation of the communication area.

Abstract: The present invention provides a wireless station capable of increasing the probability that a path diversity effect can be obtained in a case where a plurality of wireless stations transmit packets using a modulation/demodulation scheme with an anti-multipath property. A delay amount determining section (48) randomly selects a delay amount from among a plurality of candidate values. A transmission timing control section (47) determines a transmission start timing, at which to start the packet transmission, to be a timing obtained by delaying a reference timing by the delay amount selected by the delay amount determining section. At the transmission start timing, a modulation section (49) transmits the packet via an RF section (42) and an antenna (41). The difference between the candidate values is greater than or equal to a predetermined delay resolution, and the difference between a maximum candidate value and a minimum candidate value is less than or equal to a predetermined maximum delay.

Abstract: The present invention provides a wireless transmission system in which it is possible to exert a maximum path diversity effect even if the maximum number of effective branches is limited to a small number. A transmission timing control section (23) determines a transmission start timing to be a timing obtained by delaying a reference timing by a predetermined delay amount. A modulation section (21) modulates a signal by a modulation scheme such that an anti-multipath property is exerted when the signal is demodulated on a receiver side, and transmits the modulated signal at the transmission start timing. In a receiving station (12), a demodulation section (33) demodulates the receive signal to obtain receive data.

Abstract: A detected signal 111 contains a preamble portion which includes symbol alternations, followed by a unique word portion, and a data portion. Each time a symbol alternation is detected, a correction value calculation section 102 averages the phase shift in the detected signal 111 for a predetermined length, thereby calculating a correction value 115. The correction value determination section 103 stores a plurality of correction values 115 in a chronological order. When the unique word portion is detected, the correction value determination section 103 retains, as an effective correction value 118, a correction value which is arrived at by going back a predetermined number of correction values among the stored correction values. A phase rotation section 104 corrects the phase of the detected signal 111 by using an effective correction value 118 calculated by the correction value determination section 103.

Abstract: A detected signal 111 contains a preamble portion which includes symbol alternations, followed by a unique word portion, and a data portion. Each time a symbol alternation is detected, a correction value calculation section 102 averages the phase shift in the detected signal 111 for a predetermined length, thereby calculating a correction value 115. The correction value determination section 103 stores a plurality of correction values 115 in a chronological order. When the unique word portion is detected, the correction value determination section 103 retains, as an effective correction value 118, a correction value which is arrived at by going back a predetermined number of correction values among the stored correction values. A phase rotation section 104 corrects the phase of the detected signal 111 by using an effective correction value 118 calculated by the correction value determination section 103.

Abstract: A clock recovery circuit capable of fast and accurate clock phase locking even in the presence of frequency shift and noise. The input signal includes, in order, a preamble with an alternating bit sequence pattern, a unique word and data. A detection unit detects zero crossings and measures the time interval therebetween. A 1-interval judgment unit judges whether an interval signal is within a predetermined range, and a 2-interval judgment unit sums two adjacent interval signals and judges whether the 2-interval signal is within a predetermined range. A control unit controls a zero-crossing signal based on the judgment result and outputs a valid zero-crossing signal if judged in the affirmative. A switching unit switches between outputting the zero-crossing signal and the valid zero-crossing signal as valid phase error information based on a frame reception signal input from a frame detection unit. A clock generation unit uses the valid phase error information in generating a symbol clock.

Abstract: A wireless transmission system capable of performing a multi-station simultaneous transmission of data, that is, simultaneously transmitting data by wireless to a plurality of stations. The wireless transmission system includes a plurality of wireless stations for transmitting/receiving data and it constitutes a system for path diversity by use of a wireless station at the transmitting end, a multipath transmission path, and a wireless station at the receiving end. At least one of the plurality of wireless stations decides, in accordance with a response packet responsive to a multi-station simultaneous transmission request packet transmitted by the wireless station or other stations, a plurality of delay amounts relative to a reference timing during the multi-station simultaneous transmission in the wireless transmission system.

Abstract: A data receiving device is provided enabling a reduction in the time required for extracting a partial band signal, and capable of being easily made in a simple structure as an LSI device without requiring a plurality of analog circuits having the same characteristics. The data receiving device includes: a first sampler for sampling an in-phase signal I(t) at every predetermined sampling period and outputting the sampled in-phase signal; a second sampler for sampling a quadrature signal at every predetermined sampling period and outputting the sampled quadrature signal; a partial band extracting section structured by a complex filter for extracting partial band signals IBr, QBr from frequency components included in the sampled in-phase signal and the sampled quadrature signal; and first and second delay detection operating sections for performing a delay detecting process based on the partial band signals and outputting detection signals.

Abstract: A base station 2 demodulates a wireless signal after downconverting the signal to a low-frequency signal whose center frequency is fi [Hz] and oversampling the signal. A mobile station 3 demodulates a wireless signal after downconverting the signal to a low-frequency signal whose center frequency is fd [Hz] and undersampling the signal. The same sampling frequency fs [Hz] is used in the base station 2 and in the mobile station 3. The sampling frequency fs [Hz] is set to a value that is an even-number multiple of a wireless symbol transmission rate such that oversampling is done in the base station 2 and undersampling is done in the mobile station 3. The center frequency fi [Hz] is ½ to 1 times a frequency corresponding to the bandwidth and is ½N (N is a natural number) times the sampling frequency fs [Hz].

Abstract: There is provided a new inter-station transmission method capable of extending, as compared with a conventional method, a time to be allocated for a transmission path delay of an inter-station transmission path within a predetermined turnaround time, and increasing an inter-station transmission distance as much as possible. A radio base station (20) reproduces a clock synchronized with a BSU transmission clock DCLK, the BSU transmission clock DCLK being used when transmitting downlink transmission data from a communication control station (10). Based on the reproduced clock, the radio base station (20) processes the downlink transmission data. Since this clock synchronization eliminates a necessity of data format conversion between the communication control station (10) and the radio base station (20), a buffer such as a FIFO for accumulating transmission data in preparation for the conversion is no longer necessary. Consequently, a delay time caused by the buffer in a conventional process is eliminated.