Probability of capture and rejection of primary multiple-access interference in spread-spectrum networks

The probability of capture is evaluated for the situation in which several transmitters use the same spread-spectrum code for the attention of a single receiver. The first stage in the capture mechanism is that of the acquisition of capture. The authors are concerned with the second stage, that of retaining capture, in the presence of interference from contending users. The probability of retaining capture is computed via accurate approximations and upper bounds for direct-sequence, frequency-hopped, and hybrid spread-spectrum signaling formats and for different data modulation and demodulation schemes. The calculation of the overall probability of capture is carried out for spread-spectrum systems with and without forward-error control. The ability to reject primary multiple-access interference in spread-spectrum radio networks is examined by computing the maximum number of users that may contend for the same receiver, without causing the probability of capture to fall below some desirable level