Oki Electric Industry Co., Ltd.

Kiyoki Sekine

Manabu Kawabe

Toshio Kato

Takuro Sato

Kenji Horiguchi

Shinichi Sato

Atsushi Fukasawa

Chiharu Yamano

Yuichi Shiraki

Ikuo Kawasumi

Junji Uehara

A method of switching a communication channel when a mobile station moves from one service area to another service area is disclosed. The mobile station determines a difference between the transmission phase of a frame synchronizing signal received from a first base station currently holding a communication channel with the mobile station and the transmission phase of a frame synchronizing signal received from a second base station expected to newly set up a communication channel with the mobile station. The mobile station sends phase difference information representative of the above difference to the first base station via the communication channel. The first base station having received the phase difference information transfers the information to the second base station, causing it to correct the phase of data thereof to be sent to the mobile station. This successfully implements soft handover while guaranteeing the phase synchronization of frames sent from the two base stations.

Mobile communication system for accomplishing handover with phase difference of frame sync signals corrected

A communication system includes a first communication station for transmitting first data and second data at a first transmission power level and a second transmission power level, respectively, and a second communication station for receiving the first data and the second data transmitted from the first communication station as a reception signal. The second communication station generates transmission power control information based on the received first and second data, and transmits the generated transmission power control information to the first communication station. The first communication station receives the transmission power control information from the second communication station, and controls the first transmission power level and the second transmission power level independently of each other based on the transmission power control information.

Multiplexing communication system

There has been such a drawback that it is difficult to accurately estimate the location of mobile station MS in a mobile communication system. To solve the problem, according to the mobile communication system of the present invention, a mobile station and several base station cooperate for estimation. First the base stations BS in which the mobile station is laid and other base stations adjacent thereto each measure the receipt levels of the radio wave radiated by the mobile station to notify the position manage center of the receipt levels. Second the position manage center instructs the mobile station to control the radio wave pursuant to the receipt levels in such a fashion the receipt levels are stabilized; finally. Third each base station measure the distance between the base station and the mobile station based upon the propagation time of the radio wave to inform the position manage center of the distance. Finally, the position manage center estimates the location of the mobile station based upon a point or several points given by the circles defined using the distances.

System and method for estimating location of mobile station

Differences between two adjacent bits of connection control data are derived in sequence. The derived differences are logically combined with a pilot signal and simultaneously with user data. The logically combined signals are spread to spreading bands and added to each other. The added signal is used as a modulating signal and transmitted through phase shift keying (PSK). Thereafter, the PSK modulated carrier is demodulated to derive the modulating signal. The modulating signal is despread to derive a user signal. The user signal includes the user data and the foregoing differences. The modulating signal is further despread to derive the pilot signal with the foregoing differences included. The pilot signal with the foregoing differences is subjected to a conjugate conversion and then multiplied by the user signal so that the foregoing differences are removed from the user signal to obtain the user data. The connection control data is reconstructed from the foregoing differences included in the pilot signal.

Communication system, transmitter and receiver

The object of the present invention is to provide a radio communication system capable of following change in fading. To attain the object, the transmitter in the radio communication system according to the present invention predicts the state of fading after the specified period of time based on the fading state signal indicative of state of fading at current time notified by the receiver, thereby amplifies the transmission signal in accordance with the predicted state of fading.

Means for predicting fading state in radio communication system

A spreading code generator generates a spreading code by modulo-two addition of two internal spreading codes. The first internal spreading code is part of a pseudorandom noise sequence, created by resetting a pseudorandom noise generator to an assigned initial state at intervals determined by counting a framing signal. The second spreading code is selected from a set of preferably orthogonal sequences, the selected sequence being repeated at intervals shorter than the period of the framing signal. A code-division multiple-access communication system employs this spreading code generator to generate all spreading codes used at all communicating stations. One of the spreading codes generated at each station is transmitted as a synchronization signal.

Spreading code generator and CDMA communication system

A transmission device is disclosed in which user data are cross converted, at their base band, by the orthogonal transformers 31.about.34. Signaling data are collected at every integer which does not exceed the ratio of the user data to the signaling data and time division-like multiplexed by the multiplexer 20. The multiplexed data are crossly converted, at its base band, by the orthogonal transformer 35. The base band data cross converted by the orthogonal transformers 31.about.35 are added by the adder 40 and carrier modulated so as to be radio transmitted from the antenna 60.

CDMA communications system using multiplexed signaling data lines

In a mobile radio communication system, at a transmitter side, when a sound-absent section is detected in sound data, transmission of the sound data is stopped, and instead, tail bits are transmitted. A transmission power is lowered to 0 (zero) or a given value other than 0 when the transmission of the tail bits is finished. The lowering of the transmission power is held until a sound-present section is detected. Convolutional encoding is effected to the sound data and the tail bits prior to transmission. At a receiver side, the variation in transmission power is monitored to control an operation of an associated component in response to the monitored power variation. Viterbi decoding is effected for decoding the convolutional code.

Mobile radio communication system

There is disclosed a spread code generation device for spread spectrum communication wherein an input data is modulated so as to be spread by a spread code having a first period. The device includes a long period PN code generator for generating a spread code having a second period longer than the first period, an initial state register for storing an initial phase of the spread code having the first period output from the long period PN code generator and for outputting the initial phase to the long period PN code generator, and a counter for receiving and computing the spread code output from the long period PN code generator and for outputting a trigger signal to the initial state register when the computed spread code reaches the first period. The initial state register outputs the initial phase to the long period PN code generation in response to the trigger signal from the counter. The long period PN code generator is reset to the initial phase when the initial phase is input to the long period PN code generator, whereby the spread code having the first period is output from the counter.

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Tokyo, Japan

Kiyoki Sekine