Throughput analyses of packet radio communications systems

Abstract Collision of packets is inevitable and is a problem in contention‐type random access systems. In radio systems, however, the throughput of the systems is improved as a result of the capture effect on power differences between colliding packets caused by propagation characteristics of channels such as fading, shadowing, and distance problems. In this paper, analyses are made of the capture effect by considering channel characteristics of radio channels and modulating and demodulating schemes. First, a theoretical equation for the packet reception success probability of the ALOHA system under frequency nonselective slow Ray‐leigh fading has been derived, and the validity of this equation has been proven by computer simulation. Thus, throughput characteristics of slotted ALOHA and pure ALOHA system have been analyzed by means of this theoretical formula. In addition, it has been proven theoretically that the channel capacity of the ALOHA system is improved two times by the capture effect for the case of a large number of mobile stations and high mean power versus noise power ratios.