The ALOHA systems in shadowed mobile radio channels with slow or fast fading

The influence of receiver capture on the performance of the ALOHA protocol in the presence of shadowing is investigated. The combined effect of Rayleigh fading, log-normal shadowing, and spatial distribution of mobile users is also studied. It is shown that shadowing is similar to fading and near/far phenomena, in that it makes the capture effect possible and provides ALOHA systems with substantial improvements in throughput. It is also confirmed that the superimposed Rayleigh fading, log-normal shadowing, and spatial distribution can further enhance the capture effect, resulting in a ALOHA system with higher throughput. The fast fading effect in ALOHA systems is explored. A very fast fading case is examined which may be considered to be equivalent to interleaving in slow fading. It is found that an ALOHA system under fast fading conditions also benefits from the capture results in higher throughput.>