Performance analysis of coded SSB-QPSK in mobile radio channels

A novel modulation scheme for transmitting QPSK as a single sideband (SSB) signal has been presented by Mujtaba (see, Proc. IEEE Globecom, Sydney, Australia, 1998). In this paper, the performance of SSB-QPSK with convolutional encoding (R=1/2 and K=5) and Viterbi decoding is presented for a mobile radio channel. While the theoretical spectral efficiency of the new scheme, SSB-QPSK, is identical to that of QPSK or SSB (i.e. 2 bps/Hz), it was shown by Mujtaba that for a Rayleigh-fading mobile radio channel, uncoded SSB-QPSK is more robust to equalization imperfections than either uncoded QPSK or uncoded SSB. In this paper, we verify similar results for coded SSB-QPSK. For a flat Rayleigh fading channel with a one-tap equalizer, it is found that SSB-QPSK is more robust to equalizer phase errors than either QPSK or SSB. Performance in a frequency-selective Rayleigh-fading channel is evaluated with a linear equalizer, in which case it is found that if the equalizer fails to remove all the ISI, the residual ISI (and hence the BER as E_b/N_o→∞) is lower for SSB-QPSK compared to QPSK