Trellis‐coded dpsk with multiple‐symbol viterbi decoding over mobile satellite channel at K and L bands

Mobile satellite communication systems at K a /K band (30/20 GHz) are attractive because of their large bandwidth availability and potentiality to support smaller earth-stations and satellite antennas compared with L-band (1.6/1.5 GHz) systems. In this paper, multiple-symbol Viterbi decoding and dual-space equal-gain diversity reception for trellis-coded differential M-ary phase-shift-keying (DPSK) modulation are investigated as two mitigation techniques for severe channel impairments expected from a land mobile satellite communication channel at K band and, for comparison purposes, at L band. The multiple-symbol Viterbi decoder (MSVD) is a modified Viterbi decoder with inputs from multiple differential detectors. The channel is modelled as Rayleigh distributed multipath fading with a lognormally distributed line-of-sight (LOS) component due to shadowing. Four trellis-coded modulation (TCM) schemes are studied. The dependency of the system performance improvement on the decoder structure, the TCM scheme, and the system RF frequency band is presented.