Matsushita Electric Industrial Co., Ltd.

Panasonic Corporation

Panasonic Intellectual Property Corporation of America

Yasuo Harada

Tomohiro Kimura

Naganori Shirakata

Hiroshi Hayashino

Koichiro Tanaka

Shinichiro Ohmi

Hideki Nakahara

Kazuhiro Ando

Yasuhiro Uno

Wei Lih Lim

Pek Yew Tan

Shuya Hosokawa

Yoshio Urabe

Hiroshi Oue

Kazuhiro Ohta

Yukihiro Omoto

Yasuo Nagaishi

Chalermphol Apichaichalermwongse

Tan Pek Yew

A station includes a reservation request transmitter, a bandwidth request transmitter, and a data transmitter. The reservation request transmitter transmits a reservation request to an access point during a contention slot specified by the access point. The contention slot is periodically allocated by the access point. The bandwidth request transmitter transmits a bandwidth request to the access point using a first allocated bandwidth allocated to the station as a response to the reservation request. The bandwidth request has a first data structure different from a second data structure of the reservation request, and includes information indicating a required bandwidth for transmitting a data to be transmitted. The data transmitter transmits the data using a second allocated bandwidth allocated to the station based on the required bandwidth.

Method for ensuring medium access in a wireless network

A spreading code generating apparatus carries out M-sequence multiplication and zero value addition of generated orthogonal codes to obtain channel identification codes, and then carries out inverse Fourier transform of the channel identification codes to generate spreading codes and inverse spreading codes. A transmitting apparatus and a receiving apparatus store the spreading codes and the inverse spreading codes generated by the spreading code generating apparatus, respectively, and use a single code respectively selected from the stored codes to carry out spread spectrum communication.

System and method for spread spectrum communication

Method and apparatus for controlling transmission of a data stream from a station. A QoS registration frame is received, via an access point, from the station. The QoS registration frame includes information indicating a request for transmission of a data stream from the station, and information indicating a minimum required interval and a maximum required interval for an interval which is between start points of two successive durations of a medium dedication. Each duration of the medium dedication represents a time period in which the station is permitted to transmit the data stream. A schedule for the transmission of the data stream is calculated by setting a new interval which is between the minimum required interval and the maximum required interval, when the transmission is admitted. A QoS response frame, which includes information indicating the schedule, is then transmitted from the access point to the station.

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

In a transfer apparatus to which MIMO-OFDM is applied, a data transmission method and a data reception method are provided in which, even when there are frequency errors varying among transfer paths, the precision of estimation of an inverse propagation coefficient function can be improved, thereby making it possible to suppress a degradation in characteristics. Among symbols composed of a plurality of subcarriers orthognal to each other, the transfer apparatus uses, as a synchronization symbol, a symbol in which predetermined amplitudes and phases are assigned to a plurality of subcarriers spaced at predetermined frequency intervals. The synchronization symbol is divided into transmission antennas to generate a plurality of synchronization subsymbols, which are in turn simultaneously transmitted from a plurality of transmission antennas. A reception apparatus estimates a frequency error for each transfer path based on synchronization subsymbols included in signals received by a plurality of reception antennas, and based on the estimated frequency errors, corrects the received signals.

Data transmission method and data reception method

A reception device according to the present invention receives a transmission frame including a synchronization symbol string, having a synchronization symbol repeated multiple times, inserted before a data symbol string. The synchronization symbol is obtained by synthesizing a plurality of sub band symbols which are mutually orthogonal and having different carrier frequencies. The carrier frequencies of the sub band symbols are located at an equal predetermined frequency interval. The synchronization symbol includes a repeated synchronization pattern. The reception device detects a rough carrier frequency error from a phase difference of a synchronization pattern correlation value to correct the frequency, and then detects a residual frequency error from an inter-symbol phase difference of each sub band to correct the frequency. The reception device detects a sampling clock frequency error from an inter-sub band phase difference to correct the frequency. Thus, the demodulation error of the data symbol is reduced.

Reception device

An efficient medium dedication schedule is generated. The schedule gives wireless medium an ability to concurrently serve real-time and non real-time application and still be able to maintain the Quality of Service as requested by the real-time application. Furthermore, QoS registration request is delivered in a time bound manner and a time slot is chosen for transmission during controlled contention phase that give lesser collision and higher throughput.

Methods for ensuring medium access in a wireless network

The presented invention provides methods and apparatus to generate a efficient medium dedication schedule which give wireless medium the ability to serve real-time and non real-time application concurrently and still be able to maintain the QoS as requested by real-time application. Furthermore, it also presents methods for implementing buffer in an efficient matter in order to complement the advantage introduced by burst transmission and burst acknowledgement.

Methods for performing medium dedication in order to ensure the quality of service for delivering real-time data across wireless network

A spreading code generating apparatus carries out M-sequence multiplication and zero value addition of generated orthogonal codes to obtain channel identification codes, and then carries out inverse Fourier transform of the channel identification codes to generate spreading codes and inverse spreading codes. A transmitting apparatus and a receiving apparatus store the spreading codes and the inverse spreading codes generated by the spreading code generating apparatus, respectively, and use a single code respectively selected from the stored codes to carry out spread spectrum communication. With the use of the spreading codes for spreading, the input signal is spread over a wide frequency band with uniform power on the frequency axis. Thus, transmission characteristics are improved, and multiplexing capacity is increased.

During all or part of a time period during which pattern signals are received, a diversity receiving apparatus allows a gain control section to fix the gain of a gain amplifier section, allows an antenna switching section to sequentially switch the selection of antennas during antenna switching periods which are synchronized with averaging periods, and determines an antenna to receive data contained in a packet, based on the levels of average powers measured by an averaging section on an averaging period-by-averaging period basis.

Diversity receiving apparatus and wireless receiving apparatus using the same

In serial transmission of a mixture of isochronous data and anisochronous data, communications through a transmission path with a high ratio of occurrence of transmission errors may disturb images during streaming reproduction and produce noise in sound. To solve this problem, the isochronous data that has not been successfully received is retransmitted by using an anisochronous region. Thus, a transmission error of the isochronous data can be reduced without impairment of isochronous characteristics of the data.

Communications control method

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.

OFDM signal transmission scheme, and OFDM signal transmitter/receiver

An apparatus and method for OFDM demodulation establish symbol synchronization to minimize between-symbol interference even under an environment where multipath occurs. An incoming signal is an OFDM signal including a transmission symbol structured by a valid symbol period and a guard interval, and a predetermined synchronization symbol is included in the OFDM signal for every transmission frame. A correlator calculates how a signal generated by a synchronization symbol generator and the OFDM signal are correlated. A correlation calculator then calculates a correlation therefrom. An integrator integrates the calculated correlation by the guard interval. A timing determination device determines symbol timing from the integrated correlation. An FFT window generator outputs operation timing for Fourier transform from the determined symbol timing. Based on the signal outputted from the FFT window generator, the apparatus for OFDM demodulation extracts a signal in the valid symbol period from the transmission symbol for demodulation.

Apparatus and method of OFDM demodulation

An input of an OFDM signal containing known pilot carriers among given subcarriers is separated into subcarriers through Fourier transform in a fast Fourier transform unit. A data carrier phase error estimating unit obtains an amount of phase correction of each subcarrier on the basis of the pilot carriers in the separated subcarriers. A data carrier phase correcting unit corrects the phase of the separated subcarrier signal on the basis of the amount of phase correction. Thus, the phase errors of the subcarriers can be corrected and the OFDM symbols can be demodulated even if a frequency error and a timing error are occurring between the transmitter and receiver.

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Kobe, Japan

Yasuo Harada