Harmonious Coexistence between Aloha and CSMA: Novel Dual-channel Modeling and Throughput Optimization

TL;DR

This paper introduces a dual-channel analytical model to optimize coexistence between Aloha and CSMA networks, improving throughput and fairness in unlicensed spectrum sharing, especially for IoT and LTE WiFi coexistence.

Contribution

It proposes a novel dual-channel framework for analyzing Aloha and CSMA coexistence and provides an optimization method for system parameters to ensure harmonious operation.

Findings

Optimal CSMA packet transmission time is slightly less than Aloha's.

Throughput and fairness are significantly improved with parameter tuning.

Framework effectively enhances LTE Unlicensed and WiFi coexistence.

Abstract

The scarcity of the licensed spectrum is forcing emerging Internet of Things (IoT) networks to operate within the unlicensed spectrum. Yet there has been extensive observation indicating that performance deterioration and significant unfairness would arise, when newly deployed Aloha-based networks coexist with incumbent Carrier Sense Multiple Access (CSMA)-based WiFi networks, especially without proper adjustment of packet transmission times. Therefore, ensuring harmonious cohabitation between Aloha and CSMA networks is of paramount importance. How to properly tune system parameters to guarantee harmonious coexistence between these two networks, nevertheless, remains largely unexplored. To address the above open issue, this paper proposed a novel dual-channel analytical framework to characterize the throughput performance of the cohabitation between slotted Aloha and CSMA networks. To achieve harmonious coexistence, the total throughput of the coexisting network under a given desired throughput proportion is optimized by tuning the packet transmission time of CSMA nodes and transmission probabilities. The optimization results indicate that the packet transmission time of CSMA nodes should be set slightly less than that of Aloha nodes. The proposed framework is further applied to enhance the network throughput and fairness of the cohabitation of LTE Unlicensed and WiFi networks.