Multichannel FSK and DPSK Reception with Three-Component Multipath

The multichannel bit error probability for noncoherent FSK and differentially coherent PSK systems is obtained for a slow nonselective-fading multipath as a function of the multipath parameters and the order of diversity. The muitipath model involves three components consisting of two specular components and one scatter (diffuse) component. For diversity combining the multichannel noncoherent FSK receiver model employs square-law envelope addition and for DPSK employs linear baseband, postproduct-detection addition. These two diversity combining techniques are shown to be equivalent in terms of a DPSK noncoherent detector model that matches over two adjacent bits of the transmitted signal. As with Single-channel systems, the muitichannel DPSK performance is improved 3 dB over the multichannel FSK performance but otherwise equivalent. Results are given for muiltipath situations corresponding to a variety of differential path delays ranging from small to large delays and for mixed delays. Performance curves are presented for these multipath models and for several special cases representing simplified models.