Method and apparatus for encoding trellis coded direct sequence spread spectrum communication signals

摘要

A method and an apparatus for encoding of trellis coded direct sequence spread spectrum communication signals are provided. An input data bit sequence is received into a transmitter where it is encoded and modulated using trellis code modulation. The encoding comprises encoding the signal using a convolutional coder having a rate equal to 1/log2 (M), where M is a number of biorthogonal Walsh sequences. The encoded and modulated signal is spread by mapping a number of branches of the trellis code to a number of biorthogonal Walsh sequences. The mapping comprises labeling the branches of the trellis code using the biorthogonal Walsh sequences. This mapping uses the output of a convolutional coder as a memory address where the memory address contains one of a number of biorthogonal Walsh sequences. The spread signal may be a binary phase-shift keyed (BPSK) data signal, but is not so limited. A pilot signal is embedded into the spread BPSK data signal to provide phase coherency between the reverse link transmitter and receiver. The BPSK data signal is then multiplexed to form a quadrature phase-shift keyed (QPSK) signal. The QPSK signal is spread using a pseudo-random noise (PN) sequence prior to being transmitted.