Fujitsu Corporation

Atsushi Yamashita

Hideto Furukawa

Nobutsugu Fujino

Takeshi Inoue

Tadayoshi Katoh

Satoru Chikuma

Tetsuyoshi Takenaka

Tadashi Nakamura

Akiko Tetsuka

Hiroshi Kurihara

Takeshi Ohba

Yoshihiko Asano

Kaneyasu Shimoda

Hiroyuki Sogo

Kosuke Nobuyasu

Yutaka Hamada

Mitsuru Seta

Masahiko Shirota

Tsudoi Kubo

Yasuo Tanishima

Hitoshi Ishikawa

Bun-ichi Miyamoto

Rikihiko Mashima

Masaru Moriwake

A mobile communication system comprises a detecting unit to detect information concerning a moving speed of a mobile terminal, and a selection controlling unit to select a use frequency in a higher frequency band when the speed information detected by the detecting unit is a higher speed, while selecting the use frequency in a lower frequency band when the detected information is a lower speed, and assigning it to the mobile terminal. In a mobile communication system in which a relationship between a terminal moving speed (Doppler frequency) and transmission quality degradation is non-monotonous, the communication quality can be improved and the channel capacity can be increased.

Mobile communication system, and a radio base station, a radio apparatus and a mobile terminal

The invention relates to a radio communication system, a base station control equipment and a mobile station equipment which constitute the radio communication system. An object of the present invention to maintain high channel capacity while adapting to geographical distribution of a mobile station which can perform soft hand-off. The base station control equipment comprises a transmission-quality measuring section for measuring the transmission qualities of reception waves arriving from mobile stations. In the process of channel control, the base station control equipment is given the allowable maximum number N of radio channels through which a BTS transmits in parallel, as a tolerable limit of interference with wireless zones formed by a local station and/or other stations. It allots, in descending order of the transmission qualities, N or less radio channels to the mobile stations which are transmitting ends of reception waves having measured transmission qualities.

Base station control equipment, mobile station equipment, and radio communication system

A method of stabilizing frequency of an output signal of a data-relay apparatus provided in a radio communication system that includes a relay station and a radio terminal device, wherein the data-relay apparatus receives a signal as an input signal from the relay station, and transmits the signal as an output signal to the radio terminal device. The method includes the steps of demodulating the output signal to generate a demodulated signal by use of a first signal, detecting frequency deviation of the output signal from the demodulated signal, generating the first signal according to the detected frequency deviation of the output signal, and generating a second signal to mix with the input signal to generate the output signal according to the generation of the first signal and the second signal being carried out such that the detected frequency deviation of the output signal becomes substantially zero.

Method and apparatus for stabilizing frequency of output signal of relay station in radio communication system

Disclosed is a soft handoff control method in a CDMA mobile telecommunications system in which, when a mobile station is handed of to a wireless link with another base station, handoff to a prescribed wireless link is performed after wireless links are established between the mobile station and a plurality of base stations simultaneously. The method includes deciding, on the basis of the soft handoff rate of a base station, the number of soft handoff branches allocated to a mobile station residing in a cell that corresponds to the base station, and performing soft handoff based upon the number of soft handoff branches.

CDMA soft handoff control method

A bit deinterleave circuit comprises: measurement unit for measuring the reception level of each bit in a received symbol completing a bit interleave process; a command-signal generating unit for outputting a command signal to indicate whether computation in error correction is to be inhibited or permitted for each symbol on the basis of the reception level of the symbol measured by the measurement unit and a threshold value; a first deinterleave unit for deinterleaving the received signal completing a bit interleave process; and second deinterleave unit for rearranging command signals to output the command signals according to a signal output by the first deinterleave unit.

Bit interleave circuit and bit deinterleave circuit

A base transceiver station in a wireless local loop system using a personal handy-phone system constituted by a plurality of cell stations, each accommodating a plurality of subscriber units, a hybrid section integrally handling signals transmitted and received by the plurality of cell stations via a single antenna, and a multiplexing/demultiplexing unit integrally handling the signals transferred between the plurality of cell stations and an existing network, thereby enabling construction of a wireless local loop system which is small in size, can expand the service area without an increase of interference with other base transceiver stations, has a good affinity with existing networks, is provided with ISDN functions, and, at the same time, provides backup against faults and improves the transmission quality and reliability.

Base transceiver station and subscriber unit in wireless local loop system using personal handy-phone system and method for operating same

To achieve soft handoff control between base transceiver stations (BTS) served by mobile telephone switching offices (MTSOs), a communication line logically isolated from the MTSOs is provided between adjacent BTSs. Traffic information is transferred between the BTSs via the communication line, thereby achieving a soft handoff with the control taken by one of the BTSs.

Method for carrying out soft handoff in mobile communication system, and

A network control system for eliminating a relative error among control signals transmitted from nodes provided in radio zones respectively, a mobil station moving among the radio zones, each of the nodes comprising: a relative error detecting unit for detecting a relative error between an after-controlled transmitting control signal to be transmitted to adjacent nodes and a received control signal from an adjacent node; and a control unit for controlling a before-controlled transmitting control signal in such a way that the relative error becomes zero so as to output the after-controlled transmitting control signal.

Network control system for controlling relative errors between network

A network control system for controlling a plurality of nodes respectively corresponding to, and provided in, a plurality of radio zones. Each node has a corresponding base station, where a mobil station travels among the plurality of radio zones and communicates with the base station of a respective node when travelling in a radio zone corresponding to the respective node. Each base station transmits a transmission signal for the corresponding node to adjacent nodes, receives transmission signals transmitted from the base stations of adjacent nodes and spatially filters the received transmission signals. Each base station includes (a) a notification unit notifying the base stations of adjacent nodes of transmission timing information of the transmission signal of its own node, and (b) a correction unit receiving transmission timing information from the base stations of adjacent nodes indicating the timing of the transmission signals of the adjacent nodes, and correcting the timing of the transmission signal of its own node to minimize a difference between the timing of the transmission signal of its own node and the timing of the spatially filtered transmission signals received from the base stations of the adjacent nodes.

A network control system for controlling a plurality of nodes respectively corresponding to, and provided in, a plurality of radio zones. Each node has a corresponding base station. A mobil station travels among the plurality of radio zones and communicates with the base station of a respective node when travelling in a radio zone corresponding to the respective node. Each base station transmits a transmission signal to adjacent nodes and receives transmission signals transmitted from the base stations of adjacent nodes. Each base station includes (a) a reception automatic frequency control unit receiving the transmission signals transmitted by base stations of adjacent nodes, and performing an automatic frequency control operation for each received transmission signal, (b) a frequency error detection unit detecting a frequency error between the automatic frequency controlled transmission signals and a frequency obtained by adding a nominal frequency gap between base stations to the transmission frequency of the transmission signal of the node corresponding to the frequency error detection unit, (c) an averaging unit spatially filtering the frequency errors to produce a spatial mean value, and (d) a transmission frequency control unit controlling the transmission frequency of the node corresponding to the transmission frequency control unit in accordance with the spatial mean value, to substantially eliminate the frequency errors.

An analog Viterbi decoder realizes a part of the signal processing operations necessary to produce a decoded signal by, for example, calculation of branch metrics in branch metric calculation circuit, and addition, comparison, and selection an ACS circuit, using analog signal processes, to remarkably decrease the number of elements, and to realize a high speed Viterbi decoder with a relatively small size.

Apparatus and method using analog viterbi decoding techniques

A path trace Viterbi decoder comprising an ACS circuit for generating a path selecting signal, a path memory for storing the path selecting signal, a node calculator for calculating the node number of a most likely path on the basis of the data read out from the path memory, and a trace memory for storing the most likely path data, etc. The node number data of the most likely path calculated by the node calculator is stored in the trace memory and the decoding operation is carried out by using the data read from the trace memory.

Path trace viterbi decoder

An integrated viterbi decoder structure and method, the viterbi decoder receives test input signals at a distributor, an ACS circuit and a path memory and compares the output signals generated by the test input signals with predetermined test signals so as to test the internal operations of the viterbi decoder without the need for complex logic housed with the viterbi decoder.

Viterbi decoder and method for testing the viterbi decoder

A Viterbi decoder with a pipeline processing function for decoding a received code sequence transferred from an encoder, including correlation determining circuit for calculating correlation between a received code sequence and each of a plurality of predetermined code sequences of known allowable transitions; and selecting circuits operatively receiving the correlations for selecting one of the predetermined code sequences as the maximum likelihood transition. The selected one of the predetermined code sequences has the maximum correlation among the correlations. A decoded code sequence is obtained from the selected one of the predetermined code sequences. The correlation determining circuit includes a plurality of new correlation determining circuits each for determining a new correlation based on newly received code sequence and an aready calculated correlation between the already received code sequence and one of the predetermined code sequences; and a comparing circuit for comparing, simultaneously with the determination of the new correlations, already calculated correlations between the already received code sequence and the predetermined code sequences, so as to output a path selecting data. The selecting circuits selects, in response to the selecting data, one of the predetermined code sequences as the maximum likekihood sequence with respect to the code sequence generated by the encoder.

Growing community of inventors

Kawasaki, Japan

Atsushi Yamashita