Evaluation models of capture probability for coherent BPSK and non-coherent FSK demodulation

Abstract

The capture effect can improve the channel throughput of random multiple access protocols. So far, no attempt to investigate the capture effect in LEO satellite channels has been made. Two sophisticated evaluation models are proposed respectively for coherent BPSK and non-coherent FSK demodulation. The C-BPSK model introduces the threshold of carrier lock into the calculation of the capture probability, and consequently removes the overestimated part of the probability. Moreover, the affect of bit-sync offsets of the interfering packets on the capture probability is also taken into account. The novel NC-FSK model properly considers the bit decision process of the receiver under interfering packets, and is able to present a more practical estimate of the capture effect in the UoSAT satellite channel. Although originally proposed for the LEO satellite channel, the two models are completely applied to the other mobile channels where the channel noise is Gauss-distributed.