Interleaved trellis coded modulation and decoding

摘要

Digital communications systems employ trellis coded modulation schemes. A K-dimensional trellis coded modulated symbol is transmitted over M channels in K/M cycles (where M divides K). K/M consecutive data units are transmitted serially in a time multiplexed manner in K/M consecutive cycles over one channel. If M=1, then each symbol is transmitted over one channel in K cycles in a time-multiplexed manner. At the receiver, a symbol is formed by grouping the data received from M channels in K/M cycles and this symbol is then decoded by a joint equalizer and decoder. If the number of parallel channels is N, then N/M trellis coded modulators and N/M decoders can be used in parallel. The advantage of this approach is an increase in speed by factor N/M. The N/M trellis coded modulation and joint equalization and decoding operations can also be implemented by using fewer hardware trellis coded modulators and decoders using folding technique where multiple operations are time-multiplexed to the same hardware modulator or decoder which are operated by higher clock speed.