Low spectral efficiency trellis coded modulation systems

Abstract

Trellis-coded modulation (TCM) is a known technique to increase the data rate without increasing the channel bandwidth when implementing error correction coding. TCM is a combination of M-ary modulation and error correction coding. This thesis investigates the performance of a low spectral efficiency TCM system, which is compared with three alternative systems having comparable bandwidth. The three alternative systems are all non-TCM systems and consist of QPSK with independent r=1/2 error correction coding on the in-phase and quadrature components, 8-ary biorthogonal keying (8-BOK) with r=2/3 error correction coding, and 16-BOK with r=3/4 error correction coding. The effects of both additive white Gaussian noise (AWGN) and pulse-noise interference (PNI) are considered. The TCM system shows much better than expected performance and significant resistance to PNI, and performance improves as the number of memory element increases. The alternative QPSK system with soft decision decoding (SDD) experiences significant degradation with PNI. The 8-BOK with r=2/3 error correction and 16-BOK with r=3/4 error correction systems occupy approximately the same bandwidth as the TCM system and show better performance in PNI than the alternative QPSK system.