A Systematic Study of IEEE 802.11 DCF Network Optimization From Theory to Testbed

Abstract

In IEEE 802.11 wireless local area networks (WLANs), an important technique for medium access control (MAC) is the distributed coordination function (DCF). Two access mechanisms are provided by DCF, the default basic access mechanism and the optional request-to-send/clear-to-send (RTS/CTS) mechanism. The performance of IEEE 802.11 DCF networks has been predicted recently by NS-2 simulator based on a unified analytical model presenting the delay, throughput and stability [1]. NS-3 and OMNeT++ provide an essential platform to model IEEE 802.11 physical (PHY) and MAC layers, nevertheless the accuracy of which is yet not investigated. In this paper we present two studies, first is a comparative simulation study of the unified IEEE 802.11 DCF analytical model [1], by considering distinct network conditions, various topologies, different access modes and discrete system parameters in NS-3 and OMNeT++. A Linux based testbed is setup to validate the mathematical model and the simulation results. The second is the optimization study to adaptively tune the RTS threshold, so that the network operates in an access mode which steers to the maximum network throughput performance. An explicit expression of RTS threshold, verified by the simulations in NS-3 and OMNeT++, is obtained in contrast to previous studies based on channel estimation and numerical calculations. Performance evaluation is done by comparing the simulation, testbed and theoretical results. This study not only proves the credibility of the theoretical model of IEEE 802.11 DCF, but also assures that the results obtained from NS-3 and OMNeT++ are persuasive and provides a foundation for RTS threshold analysis in IEEE 802.11 WLANs for practical network design considerations.

Effects of Mac Parameters on the Performance of IEEE 802.11 DCF in NS-3

“…A.Bozkurt [11] investigated the impact of retry limit, contention window, and velocity on throughput for IEEE 802.11 based VANET using Markov chain based analytical model with M/G/1/k queue. S.Manzoor et al [1] analyzed the performance of IEEE802.11 DCF through analytical model, Linux based test bed and verified by two simulation tools (OMNeT++, NS-3). They represent the effect of access mechanisms, backoff parameters (cutoff phase, window size), and number of nodes on optimal throughput.…”

Distributed Medium Access Control Method through Inductive Reasoning

“…Various studies have been conducted on IEEE 802.11 MAC protocols. The performance of the distributed coordination function in the IEEE 802.11 specification was analyzed mathematically and through computer simulations [14,15]. The authors in [16] proposed a collision-rate-based backoff algorithm.…”

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“…A.Bozkurt [11] investigated the impact of retry limit, contention window, and velocity on throughput for IEEE 802.11 based VANET using Markov chain based analytical model with M/G/1/k queue. S.Manzoor et al [1] analyzed the performance of IEEE802.11 DCF through analytical model, Linux based test bed and verified by two simulation tools (OMNeT++, NS-3). They represent the effect of access mechanisms, backoff parameters (cutoff phase, window size), and number of nodes on optimal throughput.…”

“…WLANs have become increasingly popular in the past two decades as a primary and fast-growing wireless connectivity among wireless devices because of their facile and distributed nature connectivity, low network construction and maintenance cost, and simple implementation [1,2,3]. The IEEE 802.11 standard [4] defines the MAC and PHY layer specifications for connectivity with fixed, portable, and moving stations within a wireless local area network(WLAN).The IEEE 802.11 supports two contention-based medium access protocols, named as DCF and EDCA, use carrier sense multiple access with collision avoidance (CSMA/CA) as random access mechanism.…”