Hitachi, Ltd.

Hitachi Denshi Kabushiki Kaisha

Other

Hitachi Communication Technologies, Ltd.

Htachi, Ltd.

Masayuki Ariyoshi

Nobukazu Doi

Yoshito Ohta

Tesshin Shiga

Takashi Yano

Takaki Uta

Hironari Masui

In CDMA communications, a base station detects a difference between a reference phase of a spreading code and a phase of a received signal of each terminal station, and feeds a phase jump signal PJ-i representative of the phase difference back to each terminal station. After timing acquisition, the reception operation is performed using the reference phase, and a shift amount between the phase of a received signal and the reference phase is fed back to each terminal station as phase synchronization control information PC-i. Each terminal station coarsely adjusts the phase of the spreading code in accordance with the phase jump signal PJ-i, and thereafter finely adjusts the phase of its transmitting signal in accordance with the phase synchronization control information PC-i. It is therefore possible to synchronize the phases of the signals transmitted from terminal stations and received at the base station. Accordingly, an orthogonal code is used for spreading on the reverse links.

CDMA communication system and method

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 frequency band for communication between a base station and mobile stations is divided into a reverse-link and a forward-link bands. In each of these bands, carrier frequencies are defined in correspondence with sub frequency bands each having one of several bandwidths. To each of these bands of each mobile station, a sub frequency band with a bandwidth matching a data traffic rate is assigned in advance. Each mobile station spectrum-spreads a reservation packet and transmits the resultant packet by a prescribed carrier frequency corresponding to the reverse-link sub frequency band. The base station spectrum-spreads a response packet and transmits the resultant packet by a prescribed carrier frequency corresponding to the forward-link sub frequency band. Each mobile station spectrum-spreads a data packet by a spreading code for data traffic channel specified in the response packet and transmits the resultant packet by the reverse-link carrier frequency.

CDMA communication method and spread spectrum communication system

CDMA Communication system and method

Growing community of inventors

Mitaka, Japan

Masayuki Ariyoshi