Viterbi algorithm detection of shaped BPSK in adjacent-channel interference with bandlimiting

The effect of adjacent channel interference (ACI) in UHF satellite communications (SATCOM) narrowband channels utilizing shaped biphase-shift keyed (SBPSK) modulation with Viterbi algorithm (VA) detection is examined. The SBPSK modulator, satellite channel, and demodulator with VA detection are modeled by a Monte Carlo simulation. The degradation in energy-per-bit-to-noise-spectral-density ratio (E_b/N₀) relative to BPSK performance in Gaussian noise is determined with channel separation as a parameter. This is compared with earlier results using integrate-and-dump (I&D) detection. For VA metrics matched to the ideal non-bandlimited channel, it is found that VA detection performs considerably better than I&D detection at low ACI ratios. For ACI ratios above 3 dB, the opposite is true. It is hypothesized that VA metrics more closely matched to the channel-induced distorted signal will give improved performance