Performance evaluation of multiple access spread spectrum systems in the presence of interference

A simplified version of the Lee-Smith algorithm (W.C. Y. Lee and H.L. Smith, ibid., vol. VT-32, p.177-90, May 1983) is proposed for computing the probability of outage and the bit error rate (BER) due to autointerference in multiple-access spread-spectrum radio systems. The model assumes a pair of transmitting and receiving radios in a region where there are other radios operating in the same band. Each radio is characterized by its own spatial distribution, transmitting power, activity coefficient (denoting the percentage of time the radio is active), antenna height, and a set of carrier frequencies. The probability of outage with respect to the log-normal field-strength attenuation is derived assuming that the probability of having more than one interferer is very low. To allow maximal flexibility, the spatial, carrier frequency, and activity distributions are computer simulated for each radio. As an example of applying the method, the probability of error of an asynchronous frequency-hopping (FH) and a hybrid frequency-hopping/direct sequence (FH/DS) modulation schemes in environments with thousands of radios is reported