Matsushita Electric Industrial Co., Ltd.

Panasonic Corporation

Matsushita Electric Ind. Co., Ltd.

Hidetoshi Yamasaki

Hitoshi Takai

Yoshio Urabe

Kenji Miyanaga

Hideki Nakahara

Koji Kai

Shouichi Koga

Koichiro Tanaka

Kenichi Mori

Kenji Takahashi

Akihiro Tatsuta

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 PLL frequency synthesizer provides improved phase noise characteristics. In an ADPLL frequency synthesizer, a frequency characteristic adjusting unit compares a predetermined threshold to the difference between the fractional portion of a DCO control signal and the closest integer value, and generates an adjustment signal. A supplementary varactor shifts the oscillating frequency characteristics based on the adjustment signal. By setting the predetermined threshold to a value defining the range in which the possibility of incrementing or decrementing is high, the oscillating frequency characteristics are shifted in cases when the target value of the fractional portion of the DCO control signal is in the range in which the possibility of incrementing or decrementing is high. By shifting the oscillating frequency characteristics, the target value of the fractional portion of the DCO control signal are shifted to a range in which the possibility of incrementing or decrementing is low.

PLL frequency synthesizer

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

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

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. The base station includes antennas disposed such that wireless zones cover mutually different areas, wireless units connected to the antennas in one-to-one correspondence, and for, via the respective antennas, receiving wireless signals from the terminal stations in the wireless zones and transmitting wireless signals to the terminal stations in the wireless zones, a data processing unit for processing the wireless signals received by the plurality of wireless units and generate data to be transmitted to the terminal stations, and a communication control unit for controlling the wireless units so as to, during a slot other than a transmission request slot, form one communication area combining the wireless zones of all of the antennas, and during the transmission request slot, form mutually independent communication areas less than or equal in number to the antennas.

Radio communication system

A inter-station transmission method of extending time allocated for a transmission path delay of an inter-station transmission path within a predetermined turnaround time, and increasing an inter-station transmission distance. A radio base station reproduces a clock synchronized with a BSU transmission clock DCLK used when transmitting downlink transmission data from a communication control station. The radio base station processes the downlink transmission data. The clock synchronization eliminates a necessity of data format conversion between the communication control station and the radio base station, a buffer accumulating transmission data in preparation for the conversion is not necessary. This reduces a turnaround time of a mobile communication system. When the inter-station transmission method is applied to dedicated short-range communications, having a fixed turnaround time, a distance between the communication control station and the radio base station can be increased by a distance according to the eliminated delay time.

Inter-station transmission method, radio base station monitoring method, and device using the method

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 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 diversity receiver carries out error detection, error correction, and data detection on each detected data stringAn output switching unitoutputs a decoded data stringof a branch selected by a branch selectorThe branch selectorselects a branch of highest priority in priority informationfrom branches of which a data detection signalindicates that the data is valid and of which the number of error symbolscoincides with a minimum value. In the priority informationhigher priority is assigned to a branch that includes an antenna of which the coverage is closer to that of an antenna included in a branch selected at the immediately-previous time. Thus, selected from the plurality of branches having the minimum number of error symbolsis the one that includes the antenna of which the coverage is closest to the coverage of the antenna included in the branch selected at the immediately-previous time. Therefore, it is possible to suppress the occurrence of misselection of a poor-quality branch, and improve a reception characteristic.

Diversity receiver

In the transmitter which carries out burst transmission using information data as a packet, if the status is divided into four modes, namely, burst stop mode, burst rising mode, burst continuous mode, and burst falling mode, a waveform shaping equipment designed to read out shaped waveform data for each mode from outputs of either of the two memory tables, the first memory table which holds waveform data for specific data patterns used in common in burst rising mode and burst falling mode and the second memory table which holds waveform data for all data patterns used in the burst continuous mode, or a waveform shaping equipment comprising the third memory table which holds waveform data corresponding to all the data patterns used in the burst rising mode and the fourth memory table which holds waveform data corresponding to all data patterns used in the burst falling mode and generating shaped waveform data by synthesizing the two outputs of the third and the fourth memory tables at the time of burst continuous mode.

Waveform shaping method and equipment

A demodulator,obtains demodulated data in a plurality of channels. Estimating portions,and,estimate and output the numbers of erroneous symbols and error locations thereof in the demodulated data. A data comparator,compares the demodulated data corresponding to the error locations with the demodulated data in the corresponding locations in other channels to determine whether the error location is correct, and it outputs a decision signal in response to the determination. A data selector,selects one of the demodulated data in the plurality of channels on the basis of the numbers of erroneous symbols and the decision signals and outputs the data as selected data. It is then possible to maintain the reliability of error detection even when a less redundant short error detecting code is used, and also to accurately select a channel of good quality even when the demodulated data in all channels contain the same extent of errors.

Diversity reception apparatus

A differential detecting apparatus includes samplers 1 and 2, differential detection calculating unit 3, and two post-detection filters 4 and 5. Differential detection calculating unit 3 performs a differential detection with time-division multiplexing on data output from these samplers and alternately outputs a data sequence of a part of cosine component of the phase difference of the modulated signal and a data sequence of the rest of the cosine component. Differential detection calculating unit 3 also alternately outputs a data sequence of a part of sine component of the phase difference and a data sequence of the rest of the sine component. Each of post-detection filters 4 and 5 includes linear interpolating filter 35 and integral filter 36 which are connected in series. The linear interpolating filter 35 obtains a moving average from successive three pieces of input data weighted by 1:2:1 and the integral filter 36 obtains an integral value from successive k pieces of input data.

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Hyogo, Japan

Hidetoshi Yamasaki