PERFORMANCE OF MULTIBIT DIFFERENTIAL SQAM IN MOBILE RADIO CHANNEL

A new multi-bit DSQAM (differential superposed quadrature amplitude mo dulation) for use in bandwidth and power limited digital mobile radio is proposed. A DSQAM signal is generated by a differentially encoded S QAM processor, and is detected by a multi-bit differential receiver co mbined with a soft decision Viterbi decoder. The simulated BER result shows that, in an AWGN channel, a 5 bit DSQAM modem achieves a 7.2dB E -b/N-o improvement over a conventional 1 bit differential receiver. In Rician fading channels, DSQAM demonstrates a high degree of robustnes s suffering only a minor loss of signal.