A new approach to space diversity combining in microwave digital radio

In this paper a new approach to dual-channel space diversity combining in microwave digital radio is described. This approach features: (1) adaptive control of the relative amplitudes and phases of the two branch gains; and (2) a search strategy, based on noncoherent spectrum measurements at the combiner output, that simultaneously accounts for both dispersion and noise. Computer programs have been developed to simulate the search process and to analyze the resulting performance. Eight representative channel response pairs are postulated and performance results are presented for each. It is shown that the scheme provides a high degree of channel equalization over bandwidths up to at least 40 MHz, and that, in receivers not using adaptive equalizers, it offers major improvements in detection performance over selection diversity.