Exact matched filter bound for two-beam Rayleigh fading

The matched filter bound (MFB) is exactly evaluated for a channel modeled by the sum of two delayed and independently Rayleigh-fading beams. It is shown that, if the two beams have comparable average powers, and if the delay spread is moderate or large, then considerable gain is obtained from a diversity-like effect. That is, it is as if the two beams could be detected separately and their results combined. This is true even though significant interference would seem to be present between the beams