Online Backoff Control of Unslotted ALOHA with Collision Resolution

Abstract

In this paper, we propose to adopt a collision resolution procedure (CRP) for unslotted ALOHA networks. When a collision occurs, the devices involved in the collision can join the CRP to retransmit their packets. By considering the properties of the proposed CRP, we introduce a mathematical model to analyze the throughput performance based on which we can optimize the backoff behavior of the devices to maximize the system throughput. We show that the maximum throughput could reach 0.260 (packets/sec) which is 41.3% improvement compared to the 0.184 (packets/sec) throughput which is the maximum for the conventional unslotted ALOHA. In addition, we also propose an online backoff control algorithm that estimates the number of devices that have packets to transmit in real-time and controls the backoff rate accordingly to achieve maximum throughput. Through simulation results, we show that the proposed algorithm could adapt to the varying population size in the network and can achieve the maximum throughput of 0.260 (packets/sec). © 2022 IEEE.