Panasonic Corporation

Matsushita Electric Industrial Co., Ltd.

Hideki Nakahara

Hitoshi Takai

Koichiro Tanaka

Kenji Miyanaga

Hidetoshi Yamasaki

Naganori Shirakata

Yasuo Harada

Tomohiro Kimura

Kenichi Mori

Yoshio Urabe

Mikihiro Ouchi

Hiroshi Hayashino

Yoshinobu Matsumura

Tomohiko Taniguchi

Shinichiro Ohmi

Shuya Hosokawa

Hiroshi Oue

A wireless transmission system performs multi-station simultaneous transmission of data. The wireless transmission system includes wireless stations for transmitting and receiving data. Transmitter-side wireless stations, a multipath channel, and receiver-side wireless stations constitute a system for path diversity. At least one wireless station among the wireless stations determines, depending on a response packet with respective to a multi-station simultaneous transmission request packet transmitted by itself or other stations, delay amounts from a reference timing during multi-station simultaneous transmission in the wireless transmission system, and symbol waveforms that are a basis for a modulated waveform. A difference between each delay amount is set to be larger than or equal to a predetermined delay resolution for each symbol waveform, and a difference between maximum and minimum values of the delay amounts is set to be smaller than or equal to a predetermined maximum delay.

Wireless transmission system, and wireless station and method used for same

A wireless transmission system capable of exerting a maximum path diversity effect by using combinations formed by symbol waveforms. A transmission timing controlling section () determines a transmission start timing. A modulating section () modulates a signal by using one of a plurality of symbol waveform candidates and by utilizing a modulation scheme in which a phase transition of a symbol waveform represents a waveform being changed, and then transmits the modulated signal at a transmission start timing. A predetermined delay amount is set such that (i) the number of reception timings, each indicating a timing at which a receiving station () receives a signal, is a plural number and is less than or equal to a maximum number of effective branches for each symbol waveform, and (ii) each time difference between the reception timings is greater than or equal to a delay resolution and less than or equal to a maximum delay.

Wireless transmission system, wireless transmitting method, and wireless station and transmitting station used therein

An inter-carrier interface removal device can improve estimation accuracy of inter-carrier interference caused by Doppler shift in a received multi-carrier signal moving at a high speed, and a reception characteristic of the multi-carrier signal after removing the inter-carrier interference. The inter-carrier interference removal device includes a channel estimation unit estimating a channel frequency characteristic according to a carrier signal, an equalization unit equalizing the carrier signal with the channel frequency characteristic and outputs tentative carrier data, a reliability value calculation unit calculating a reliability value according to the channel frequency characteristic, a weighting unit weighting the tentative carrier data with the reliability value, an ICI component estimation unit estimating an ICI component according to the weighted tentative carrier data and the estimated channel frequency characteristic, and an ICI removal calculation unit removing the ICI component from the carrier signal.

Inter-carrier interference removal device and reception device using the same

A transmission device includes a differential encoding section for differentially encoding transmission data, a first waveform generation section, a second waveform generation section, and two transmission antennas. A reception device includes a reception antenna, a delay detection section, and a data determination section for low-pass filtering a delay detection signal. The reception device receives modulated signals modulated by using two waveforms 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.

Transmission method and transmission system

A wireless station is 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. The wireless station includes 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 another relay station, 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.

Wireless station, wireless transmission method for the wireless station, and wireless transmission system using the wireless station

A detected signalcontains 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 sectionaverages the phase shift in the detected signalfor a predetermined length, thereby calculating a correction value. The correction value determination sectionstores a plurality of correction valuesin a chronological order. When the unique word portion is detected, the correction value determination sectionretains, as an effective correction value, a correction value which is arrived at by going back a predetermined number of correction values among the stored correction values. A phase rotation sectioncorrects the phase of the detected signalby using an effective correction valuecalculated by the correction value determination section

Phase error correction circuit and receiver incorporating the same

In an OFDM transmission method, in order to compensate any frequency response variation time wise resulted from any distortion in a transmission path, out-of-synchronization with passage of time, frequency drift, and phase shift, and to improve a demodulation characteristic, a PS detector in a receiver receiving an OFDM signal detects a pilot symbol. A PS1 TPFR calculator calculates a frequency response of the transmission path for a first pilot symbol, while a PS2 TPFR calculator calculates a frequency response of the transmission path for a second pilot symbol. Thereafter, a compensation vector calculator calculates compensation vectors from the frequency responses of the transmission path for both the first and second pilot symbols by linear approximation. A frequency response compensator compensates the frequency response variation of subcarriers in a data symbol based on the calculated compensation vectors.

OFDM signal transmission method, and OFDM signal transmitter/receiver

A wireless transmission system exerts a maximum path diversity effect even if the maximum number of effective branches is limited to a small number. A transmission timing control section determines a transmission start timing to be a timing obtained by delaying a reference timing by a predetermined delay amount. A modulation section 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, a demodulation section demodulates the receive signal to obtain receive data. The predetermined delay amount is such that signals are received at the receiving station at a plurality of signal-receiving timings, and the number of signal-receiving timings is less than or equal to a predetermined maximum number of effective branches, a difference between the signal-receiving timings is greater than or equal to a predetermined delay resolution and is less than or equal to a predetermined maximum delay.

Wireless transmission system and wireless transmission method and wireless station and transmitting station for use therein

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. It is arranged that each difference between the plurality of delay amounts be greater than a predetermined delay resolution and that the difference between the maximum and minimum values in the plurality of delay amounts be smaller than a predetermined maximum delay.

Wireless transmission system, wireless station used therein and method used therefor

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.

Clock recovery circuit and receiver using the circuit

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 () randomly selects a delay amount from among a plurality of candidate values. A transmission timing control section () 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 () transmits the packet via an RF section () and an antenna (). 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.

Wireless transmission system and wireless transmission method and wireless station for use therein

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 IB, QBfrom 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.

Data receiving device

In an OFDM transmission scheme, in order to compensate any frequency response variations time wise resulted from any distortion in a transmission path, out-of-synchronization with passage of time, frequency drift, and phase shift, and to improve a demodulation characteristic, a PS detector in a receiver receiving an OFDM signal detects a pilot symbol. A PS1 TPFR calculator calculates a frequency response of the transmission path for a first pilot symbol, while a PS2 TPFR calculators calculates a frequency response of the transmission path for a second pilot symbol for a second pilot symbol. Thereafter, a compensation vector calculator calculates compensation vectors from the frequency responses of the transmission path for both of the first and second pilot symbols by linear approximation. A frequency response compensatory compensates the frequency response variation of subcarriers in a data symbol based on the calculated compensation vectors.

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Hyogo, Japan

Hideki Nakahara