Mitigating tail latency in IEEE 802.11–based networks. (30th August 2017)

• Record Type: Journal Article
• Authors: Kim, Dohyung; Yeom, Ikjun; Lee, Tae‐Jin
• Is Part Of: International journal of communication systems. Volume 31:Number 1(2018)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2017-08-30
• Subjects: delay‐sensitive -- IEEE 802.11 -- medium access -- short‐term fairness -- tail latency; Telecommunication systems -- Periodicals; 621.382
• DOI: 10.1002/dac.3404
• Languages: English
• ISSNs: 1074-5351

Abstract

Summary: Delay sensitive applications are being actively introduced with the advent of 5G and vehicular communications, and such applications are very sensitive to tail latency. However, tail latency has not been seriously considered so far, especially in IEEE 802.11–based networks. Channel access is scheduled by random Contention Window (CW) values in IEEE 802.11–based networks, and the node with the larger CW waits longer, and it may even observe multiple transmissions from a single contending node, which results in a long latency tail. In this paper, we propose a new decentralized MAC called SynchMAC to mitigate this latency tail. In SynchMAC, every competing node transmits exactly one packet within a virtual time slot without a centralized controller. Using the proposed approach, the maximum channel access latency is bounded by T ×2 N, where T is the time required for transmitting a single packet (including Inter‐Frame Space and CW) and N is the number of competing nodes. To maximize the system throughput, the proposed scheme optimizes the value of T by considering the probability of successful transmission. Our simulation study shows that SynchMAC reduces the maximum access latency by up to 94% and 53% compared with the conventional IEEE 802.11 MAC and the comparative scheme, respectively, without degrading throughput performance. We also show that SynchMAC is easily extended to support weighted access. Abstract : Due to random access property inherent in CSMA/CA, the presence of a latency tail is inevitable in IEEE 802.11‐based networks. To resolve the problem, we have proposed a new channel access scheme called SynchMAC, where every competing node transmits only one single packet within a virtual time slot, called a Round. Based on the mathematical analyses, a period of Round is effectively minimized, resulting that the proposed scheme mitigates the latency tail without degrading throughput.