Abstract: Operating a communication device in a half-duplex mode using only overhead channels; and substantially free running a timing reference obtained during reception to allow a timing reference value to drift during transmission.

Abstract: A method and apparatus for encoding and decoding QAM trellis modulated data. In the transmitter, a subset of bits of an input bit set are convolutionally encoded based upon a punctured convolutional code of a lower data rate to provide a set of coded symbols. The coded symbols and the uncoded bits of the input bit set are provided to a QAM modulator to provide a QAM modulation signal indicative of the values of coded symbols and the uncoded bits. In the receiver a QAM demodulator converts the received QAM signal to QAM signal space coordinates. A decoder employing the Viterbi algorithm is used to reconstruct a corrected estimate of the values of the coded data bits from the received signal coordinates. The corrected estimate of the values of the coded data bits are then used in conjunction with the received signal coordinates to provide corrected estimates of the values of the uncoded input bits.

Abstract: A method and apparatus for encoding and decoding QAM trellis modulated data. In the transmitter, a subset of bits of an input bit set are convolutionally encoded based upon a punctured convolutional code of a lower data rate to provide a set of coded symbols. The coded symbols and the uncoded bits of the input bit set are provided to a QAM modulator to provide a QAM modulation signal indicative of the values of coded symbols and the uncoded bits. In the receiver a QAM demodulator converts the received QAM signal to QAM signal space coordinates. A decoder employing the Viterbi algorithm is used to reconstruct a corrected estimate of the values of the coded data bits from the received signal coordinates. The corrected estimate of the values of the coded data bits are then used in conjunction with the received signal coordinates to provide corrected estimates of the values of the uncoded input bits.

Abstract: A method and apparatus for constructing high rate trellis codes for PSK modulation that can be encoded and decoded using the encoder and decoder for a rate 1/2 punctured convolutional code. In particular, the design of trellis encoders and decoders for 2.sup.k -PSK modulation for rates (km-1)/km for k.gtoreq.3 and m.gtoreq.1 is provided.

Abstract: A Viterbi decoder for recovering the original bit data stream that was convolutionally encoded as a code symbol stream in a Code Division Multiple Access (CDMA) mobile communication system. The decoder simultaneously decodes at the several data rates associated with certain multirate vocoders. The decoder can decode at an unknown data rate in either continuous or framed packet modes. It accomplishes this by simultaneously decoding at multiple rates and by creating one or more data quality metrics for each decoded data packet. Special input and output buffering is provided to isolate the decoder from system timing constraints. The input buffer includes selection and accumulation logic to organize code symbol data into the packet order for repeat mode or random burst mode at lower frame data rates.