Fade compensation in QPRS mobile radio modems

Abstract

Spectral efficiency of about 2b/s/Hz compared to 1.6b/s/Hz of the new cellular standard 5 4 -QPSK could be achieved with our proposed pilot symbol assisted class IV Quadrature Partial Response Signalling Scheme (QPRS) in fast fading mobile radio channels. The information bits are multiplexed with a pseudo random pilot sequence which is used for coherent detection. The MLSE type receiver improves the performance in multipath fading channels. This scheme is evaluated in terms of spectral and power efficiency, and ability in eliminating the Doppler shift caused error floor of relatively low bit rate digital mobile radio. Digital and analog channel sounding Techniques for fade compensation in class IV partial response modems are compared. In slow fading mobile channel the digital fade compensated scheme is within 2 dB of Ideal Coherent QPRS.