An erasure-control decoding algorithm is discussed for frequency-hopped spread-spectrum systems operating in the presence of pulsed or partial-time interference, and some properties of the resulting error probability which are useful in designing effective decoding algorithms are derived. Based on numerical results, specific decoding algorithms which correct both erasures and errors are then presented for use with block codes employing hard decisions.

The coded error probability for direct sequence (DS) BPSK or QPSK spread-spectrum systems, used with or without interleaving, and operating in the presence of pulsed multiple-tone interference, is investigated. We consider the worst-case channel error probability under conditions of pulsed multiple-tone jamming for the various systems, and present coded error probability as a function of interleaving delay for(n, k)block codes with hard-decision decoding. It is shown that when the maximum level of continuous multiple-tone interference does not exceed the level of the desired signal, the duty cycle of the corresponding pulsed interference which yields the worst-case error probability is usually small, and that the smaller the duty factor of the jamming, the more considerable is the performance improvement due to the use of interleaving in conjunction with the coding.

Upper and lower bounds on the average probability of error of direct sequence (DS) spread-spectrum communication systems operating in the presence of either multiple tone or multiple access interference are presented. The bounds are quite tight and can be used without the restriction that the peak level of the interference be less than the desired signal level. A simple method for evaluating approximations to the bounds for multiple access systems, in which the peak interference does indeed exceed the desired signal level, is presented as well. The tightness of both the bounds and the approximations are illustrated with numerical results.