Title :
A comparison study of low bit rate DE-QPSK, TCM 8-ary PSK and 16-ary DE-QAM fully digital demodulators operating over a land mobile satellite link
Author :
Fines, P. ; Aghvami, A.H.
Author_Institution :
Dept. of Electron. & Electr. Eng., King´´s Coll., London Univ., UK
fDate :
6/1/1992 12:00:00 AM
Abstract :
A complete structure of a fully digital low bit rate m-ary PSK and m-ary QAM demodulator, is given. Its architecture is optimised for applications in a land mobile satellite environment, where flat Rician fading, large Doppler shifts and low E b/N o are the main channel impairments. A power efficient 9.6 Kb/s differentially encoded (DE) QPSK and trellis coded modulated (TCM) 8-ary PSK as well as a bandwidth efficient 64 Kb/s DE 16-ary QAM fully digital demodulators are considered as application examples. All of them have similar architecture with the only difference being their decision units and the absence of fine automatic gain control for the PSK schemes. The authors consider the digital implementation using digital signal processors (DSP) of virtually all demodulator operations. Their acquisition, steady state and tracking performances are evaluated by computer simulation over an AWGN and a Rician fading channel.<>
Keywords :
amplitude modulation; demodulators; encoding; fading; mobile radio systems; phase shift keying; satellite relay systems; white noise; 64 Kbit/s; 9.6 Kbit/s; AWGN channel; Doppler shifts; Rician fading channel; TCM 8-ary PSK; decision units; differentially encoded QPSK; digital demodulators; digital signal processors; flat Rician fading; land mobile satellite link; low bit rate m-ary PSK; m-ary QAM; tracking performances; trellis coded modulation;
Journal_Title :
Communications, Speech and Vision, IEE Proceedings I
