Oki Electric Industry Co., Ltd.

Eiichiro Kawakami

Satoru Shimizu

Kiyohito Tokuda

Atsuhiko Sugitani

The present invention is provided with one main station and a plurality of substations. After transmitting data addressed to all substations, the main station transmits a message addressed to all substations to query whether reception was normal. When unable to receive data normally, the substations transmit a response message to the query message, but do not transmit a response message when data reception was normal. The time for confirming that transmission was normal or abnormal can be shortened by the main station transmitting data addressed to all substations only one time, and by the substations transmitting response messages only in the case of abnormal reception.

Data communication system

A code division multiple access receiver estimates symbol values transmitted by different stations by despreading a combined received signal, weights the estimated symbol values by use of weighting factors calculated for the different stations, respreads the weighted symbol values to estimate the interference due to each station, and subtracts the estimated interference from the received signal to produce a residual signal. The weighting factors can be calculated from the residual signal; the weighting factors are calculated so as to minimize the power of the residual signal. The weighting factors are adjusted at certain intervals, preferably at intervals determined from the rate of fading of the received signal.

CDMA receiver with weighted interference cancellation

The signal transmission equipment is comprised such that a signal point does not cross the origin of the constellation by selecting signals to be input to the QPSK modulator, and the positions of the signal points in the constellation.

Signal transmission equipment

A code division multiple access receiver, which receives a signal combining both information signals and training signals, has an interference canceler that successively estimates and cancels interference caused by the training signals. The interference canceler also successively estimates and cancels interference caused by the information signals. The estimating and canceling process is preferably repeated, for each training signal and each information signal, in two or more stages.

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Tokyo, Japan

Eiichiro Kawakami