Performance of direct sequence spread spectrum in a fading dispersive channel with jamming

The performance of a binary phase-shift-keyed direct-sequence spread-spectrum communication system in a fading dispersive channel with jamming is examined. The channel is modeled as a wide-sense-stationary uncorrelated scattering channel, dispersive only in time. The channel output consists of a strong stable component of the signal plus a continuum of dispersive components and is referred to as a frequency-selective Rician fading channel. To obtain specific results, the multipath intensity profile is modeled by triangular function. Both the uncoded and coded performances are analyzed. The multipath spread is chosen to limit intersymbol interference to K adjacent coded symbols in the coded case and to only adjacent data bits in the uncoded case. No specific interleaver design is considered. A closed-form expression for the probability of error is obtained, assuming random spreading sequences. Numerical results are presented for values of the system and channel parameters. It is shown that a jammer can optimize its strategy if the probability of error is not too high.