S-ALOHA Systems With Successive Transmission: Emulating CSMA System

Abstract

In slotted-ALOHA (S-ALOHA) system, users should contend for the channel to transmit a packet in their queue every single time, irrespective of how many packets they have in their queue. The maximum throughput of S-ALOHA system is known as e(-1) approximate to 0.3679 (packets/slot) for a large number of users. This work proposes a novel S-ALOHA system, where the user with a successful (re)transmission of the packet at the head of queue is allowed to keep on transmitting his packet with some reservation probability if his queue is not empty. We call this system S-ALOHA system with successive transmission (ST) and show that the throughput of the proposed system becomes one packet per slot as the reservation probability is raised. We analyze the stability region of S-ALOHA systems with ST for two heterogeneous users and also investigate the stability condition of the system with N symmetric users. Finally, we develop a Bayesian-learning backoff algorithm, with which users can control their (re)transmission with real-time estimation on the backlogged users. It is shown that the system with the proposed backoff algorithm can achieve the theoretical limit of the throughput.