The capture effect in frequency-hop spread-spectrum multiple-access communications over fading channels with near/far problem

Fading and the near/far problem in multiuser frequency-hop spread spectrum systems are investigated. The received signals from different users have different power levels due to these problem. This phenomenon makes it possible for the system to use the receiver with capture ability, i.e. the receiver can detect accurately the strongest signal, with greater possibility, when more than one signal is present at the receiver. Noncoherent multilevel frequency-shift keying modulation, Reed-Solomon coding, and asynchronous slow frequency-hop transmission are assumed. The emphasis is on deriving the conditional probability of a symbol error when it is hit by undesired signals.<>