Maximal-Ratio Diversity Combiners

A diversity combiner with a structure which is common to many communication systems is described. When the combiner inputs are independent and identically distributed narrowband Gaussian random processes and the reference signals are timeinvariant, it is found that the combiner output can be conveniently represented as a function of a Gaussian random process, a chisquare variate, Gaussian variate, and known time functions. This representation clearly indicates the performance gain from diversity. In addition, it simplifies the evaluation of expectations of functions of the combiner output; recursion relations, with respect to the order of diversity, are found for these expectations. The results of this paper thus serve to unify and generalize many other results dealing with maximal-ratio diversity combiners; extensions of many well-known results can also be found by using the recursion relations.