Performance of DS/SSMA (Direct-Sequence Spread-Spectrum Multiple-Access) communications in impulsive channels

Performance of digital linear and nonlinear correlation receivers is studied in a multi-user environment. There are assumed to be two types of sources interfering with data transmission: multiple-access interference, and additive channel noise, which is attributed to impulsive noise sources in the environment. The contribution of multiple-access interference is examined by considering K users transmitting simultaneously over a linear channel using the binary PSK direct-sequence SSMA technique. Alternatively, the effects of the non-Gaussian impulse channel in such a system are studied by modeling the sample of noise after front-end filtering. The performance of hard-limiting correlation receivers is compared with that of conventional linear correlation receivers in such channels by exact computation of the average bit error probabilities of these two systems. It is seen that hard-limiting correlation receivers can offer substantial improvement over the conventional linear correlator when the additive non-Gaussian channel noise exhibits impulsive behavior.