Hitachi, Ltd.

Kddi Corporation

Htachi, Ltd.

Takaki Uta

Takashi Yano

Nobukazu Doi

Katsuhiko Tsunehara

Atsushi Ogino

Ryota Yamasaki

Toshiro Suzuki

Tsuyoshi Tamaki

Keiji Hasegawa

Kumiko Takikawa

Mikio Kuwahara

Tomoaki Ishifuji

Toshinori Suzuki

Seishi Hanaoka

Masayuki Ariyoshi

Hisato Iwai

In a position detection system utilizing a WLAN supporting multiple data transfer rates, it is possible to reduce the number of required installed base stations, so system construction costs can be lowered. In a wireless station, a transmitted signal is judged at the time of transmission, and in case it is normal user data, the signal is transmitted by setting optimal transmission parameters for which a high communication throughput with wireless communication is obtained, and in case it is a position detection signal, the aforementioned signal is transmitted by setting transmission parameters for which the service range is increased. As a transmission parameter for which the service range is increased, a low data transfer rate or a long preamble length is used.

Method, system and apparatus for detecting a position of a terminal in a network

In any indoor location, whenever operating a wireless terminal position detecting system comprising a transferable wireless terminal, a plurality of base stations individually allowing a connection from said wireless terminal, and a plurality of wireless receiving stations individually receiving wireless signal from said terminal and base stations, there is a problem in terms of the provision of a method for minimizing positional detection error on the part of said wireless terminal and a method for practically realizing said method. Hence, to solve the above problem, the present invention provides a wireless terminal position detecting method featuring the function to evaluate the result of measurement against wireless signals from an objective wireless terminal received by individual wireless receiving stations based on a definition of a plurality of position detectable areas designating a geographic range required for detecting actual position of said objective wireless terminal and also based on another definition for specifying plural wireless receiving stations each being located at a predetermined known position allocated for individual areas for detecting actual position of the objective wireless terminal in respective position detectable areas before eventually determining the actual position of the objective wireless terminal.

Wireless terminal position detecting method and system therefor

When one base station to which a terminal is to connect is determined from a plurality of base stations in a wireless communication system, the best base station is selected according to the communication quality or the content of communication services. In the wireless communication system, the plurality of base stations are classified into a plurality of groups. Indexes of communication quality between the base stations and the terminal are obtained and, for each group, the characterizing quantities of the indexes of communication quality are calculated. The base station group with which the terminal is to communicate is specified based on the characterizing quantities. One of the base stations in the specified group is determined as a communication destination base station.

Method for selecting base station

In a position detection system for detecting a position of a terminal apparatus of a radio communications system, a position detection time is shortened using a position detection method for determining signal times-of-arrival between the terminal apparatus and base stations neighboring the terminal apparatus. According to the present invention, means for generating a database in which received power information about signals transferred between the terminal apparatus and the base stations neighboring the terminal apparatus corresponds to position information about the terminal apparatus, and for determining the position information by searching received power information obtained in the position detection from the database, and means for determining the position by use of signal times-of-arrival are executed in parallel. Then, the use of a result of the means which has detected the position earlier than another means shortens the position detection time.

System and method for position detection of a terminal in a network

A system and method are provided for wireless communication. In one example, a wireless communication system that enhances total system throughput is provided. The system performs parallel data transmission from a plurality of access points to a plurality of user terminals. On terminals with power control function, their transmit power can be set to minimize interference. The wireless communication system comprises a management server which performs centralized management of time of access-point-to-terminal packet transmission, access points, and user terminals that perform data transmission, according to transmission time control information from the management server. Transmit queues for measuring downlink traffic and receive queues for measuring uplink traffic are provided on the access points or the management server. The system determines uplink and downlink periods from the transmit and receive queue lengths. The system also controls the access points and user terminals to transmit for the determined periods. Consequently, packet collision due to transmission from a terminal that interferes with neighboring terminals is eliminated. Thus, system throughput is enhanced.

System and method for wireless communication using a management server and access points

In a mobile communication system, the tracking of synchronization is conducted in a stable state even in a multipath environment. A delay profile detector calculates a delay profile a(n) using a despread signal for each processing unit n. A delay profile averaging unit averages a(n) to produce Ave(|a(n)|). A data symbol detector conducts rake combining of the despread signal using a(n) and Ave(|a(n)|). According to a(n) and Ave(|a(n)|, a weighting function unit calculates a representative value representing delay waves. A loop filter generates a control signal in response to the representative value. A clock controller controls a spread code generator according to the control signal.

Mobile terminal, a base station, and a synchronization control method

An uplink channel transmission power control method is provided for a CDMA mobile communication system performing one way communication. A base station measures the received level of data transmitted from each mobile terminal at each channel, and generates a transmission power control signal of each uplink traffic channel. The generated transmission power control signals are multiplexed, and the multiplexed common transmission power control signal is transmitted to all mobile terminals by using the common channel shared by the mobile terminals. Each mobile terminal derives the transmission power control signal of the uplink traffic channel used by the terminal, from the received common transmission power control signal, and controls the transmission power of a data packet.

CDMA communication system and its transmission power control method

On the side of a mobile station, interference of a perch channel with call control information or a traffic channel is reduced, realizing stable communication. In a method of CDMA communication in which communication is made through the traffic channel for transmitting user data and the perch channel for transmitting a spreading code used for demodulation of the user data, the traffic channel has a call control channel subjected to the time division multiplex, and that call control channel and a part of the perch channel, which is non-orthogonal to the call control channel, are arranged not to overlap with each other in a time base.

Mobile communication method using CDMA multiplexing technique and mobile communication system

The present invention provides a transmit power controlling method for reducing an influence of incorrect control in a mobile communication system in the CDMA mode. A likelihood of transmit power controlling signal is generated on the basis of the transmit power controlling signal transmitted by a radio base station and the receiving quality, a variation amount of the transmit power is generated on the basis of the likelihood, and the transmit power of a mobile station is controlled on the basis of the variation amount.

Method for controlling transmit power for communication system

In a mobile communication system, the tracking of synchronization is conducted in a stable state even in a multipath environment. A delay profile detector calculates a delay profile a(n) using a despread signal for each processing unit n. A delay profile averaging unit averages a(n) to produce Ave(&verbar;a(n)&verbar; ). A data symbol detector conducts rake combining of the despread signal using a(n) and Ave(&verbar;a(n)&verbar; ). According to a(n) and Ave(&verbar;a(n)&verbar; , a weighting function unit calculates a representative value representing delay waves. A loop filter generates a control signal in response to the representative value. A clock controller controls a spread code generator according to the control signal.

A spread spectrum receiver having a smaller circuit scale is accomplished by a circuit construction wherein the number of taps is set to a number smaller than a spread factor, and a cyclic accumulation process for determining a correlation value of one symbol is executed by a circuit construction using an input sequence register block in common with an addition block of a spread spectrum receiver by MF according to the prior art.

Spread spectrum receiver using digital matched filter

A transmitting apparatus for code division multiplexed signals used in the spread spectrum communication has its analog amplifier rid of spurious generation and relieved of the need of having a large transmission back-off, thereby accomplishing the low-power, low-cost and simple design of the amplifier. Multi-channel transmission signals are rendered the spread spectrum with a spread code, and the resulting code division multiplexed signal undergoes the peak amplitude limitation so that the last-stage analog amplifier can have a small back-off.

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Kokubunji, Japan

Takaki Uta