Receiver optimization and error rates for pseudo-noise spread spectrum systems with narrowband interference suppression

This report describes the results of a study of maximum likelihood receiver structures for direct sequence spread spectrum communications over channels with multipath distortion and narrowband interference, and several methods of assessing the bit error probability performance of bit-by-bit receivers and maximum likelihood receivers. This work is a continuation of work which focused on the performance of various methods of suppressing narrowband interference using spectral estimation. The previous work gave performance results in terms of SNR improvement provided by interference suppression. The previous results are extended in this report by deriving a receiver structure based on the maximum likelihood (minimum probability of error) principle. Error probability results given include simulation of a bit-by-bit receiver operated in conjunction with dispersive and nondispersive channels with narrowband interference. Also, a technique for assessing the error rate by averaging conditional probabilities is stated which applies to both fixed nondispersive and fixed dispersive channels, and bit-by-bit and maximum likelihood receivers. Probability of error results obtained using this approach are given.