Abstract: A base station includes a transmit diversity unit. The transmit diversity unit is provided with two transmission units for respective systems. Each of the transmission units produces transmission codes by coding transmission data. Each of the transmission units produces two CDMA signals by subjecting first transmission codes to spreading and 16QAM and transmits the two CDMA signals. Each of the transmission units produces two CDMA signals by subjecting second transmission codes to spreading and 16QAM and transmits the two CDMA signals. With this, time-difference diversity is implemented. Each of the transmission units codes the transmission data such that constellation points of a combined signal derived from the two CDMA signals are substantially evenly distributed. Accordingly, it is ensured that noise margin is large so that a bit error rate is improved.

Abstract: Upon completion of decoding by a first decoding part 14, a first identification signal indicative of permission or inhibition of transmission of the next data is sent to a packet transmitting device.

Abstract: A bit stream of data is mapped in such a manner that a specified bit of at least one symbol becomes a dummy bit.

Abstract: In a transmitter constituting a communication system, a buffer/transmission data disassembly unit disassembles a transmission packet into a plurality of blocks, an error detection coding unit attaches an error detection code to each of the blocks, and a transmitting unit transmits the blocks having the error detection code attached and retransmits a designated block designated by retransmission information from a receiver. In a receiver, a receiving unit receives blocks from the transmitter, an error detection unit detects an error in the received block, an ARQ control information generating unit generates information relating to retransmission of the received block, and a buffer/received data assembly unit recovers a data packet by combining a plurality of blocks. Improvement in transmission efficiency is attained.

Abstract: A multiplex communication system includes a scaling circuit for controlling, in response to a scaling control signal, the signal level of a digital multiplex signal digital generated by a modulation circuit; a variable attenuation circuit for attenuating the signal level of the RF signal output from a quadrature modulation circuit in response to an attenuation control signal; and a control signal generating circuit for generating a scaling control signal in response to the effective value of the digital multiplex signal generated by the digital modulation circuit and in accordance with a digital conversion value corresponding to a desired input level of the quadrature modulation circuit, for supplying its output to the scaling circuit, for generating an attenuation control signal in response to the scaling control signal, and for supplying it to the variable attenuation circuit.