A new approach for the analysis of the slotted Aloha local packet radio networks

Abstract

A novel method for the exact calculation of the throughput of a centralized slotted Aloha packet radio network over slow Rayleigh-fading channels is presented, and the results are compared with computer simulations. Upper and lower bounds on the performance are provided. The effects of capture on the throughput of the system are related to the modulation and coding technique, the signal-to-noise ratio of the received signal, the general terminal distribution in the area, and the length of the transmitted packets. BPSK (binary phase shift keying), coherent and noncoherent binary FSK (frequency shift keying) modulations, and BCH coding are considered for the exact calculations. The results of the analysis show that the maximum average throughput of the slotted Aloha packet radio network is around 60%, rather than the 36% predicted from the simplified analysis. In contrast with previous reports, it is shown that the throughput of the system is not affected significantly by the use of coding or the change of packet lengths.<>