Revisiting 802.11 for User Fairness and Efficient Channel Utilization in Presence of LTE-U

TL;DR

This paper investigates fairness issues in LTE-U and Wi-Fi coexistence, revealing unfair throughput distribution among Wi-Fi users and proposing a PCF-based scheme to improve fairness and channel utilization.

Contribution

It introduces a practical analysis of Wi-Fi fairness under LTE-U duty cycling and proposes a novel PCF-based scheme to enhance fairness and efficiency.

Findings

LTE-U causes unfair Wi-Fi throughput distribution.

Non-victim Wi-Fi users dominate channel access.

Proposed PCF scheme improves fairness and channel utilization.

Abstract

A promising solution satisfying the industry's demand to have minimum alterations in LTE for its operation in unlicensed spectrum is duty cycled LTE-U scheme, which adopts discontinuous transmission to ensure fair coexistence with 802.11 (Wi-Fi) WLANs. Even though the scheme guarantees to maintain Wi-Fi network performance, the fairness among Wi-Fi users still remains arcane. In this work, we present a practical scenario where LTE-U, despite being discontinuous (by following an ON-OFF cycle), results in not only unfair throughput distribution among Wi-Fi users but also causes degradation in Wi-Fi APs downlink performance. This is due to the domination of few Wi-Fi users who harness channel in both ON and OFF durations of LTE-U, namely non-victim users over those who get access only in OFF duration, called victim users. In this paper, we studied the performance of victim and non-victim Wi-Fi users, and Wi-Fi AP while varying LTE-U ON duration (i.e., duty cycle). A propitious scheme is proposed for WLANs, with regard to ease of implementation, employing Point Coordination Function (PCF) mode of 802.11, promising fairness among Wi-Fi users with improvement in the channel utilization of Wi-Fi network. An analytical model is developed to demonstrate guaranteed improvement and validate the simulation results.