A distributed message in message aware concurrent transmission protocol in IEEE 802.11 WLANs

Kang Young-Myoung, Yoo Joon, Lee Joonsoo, Kim, Kim Chong-Kwon

Description

The IEEE 802.11 distributed coordination function (DCF) employs the carrier sense technology to avoid frame collisions. However, recent measurement studies demonstrate that the physical layer (PHY) capture effect frequently occurs; even when frames collide, one of them can be decoded successfully if its relative signal strength is high enough. Furthermore, a new wireless PHY technology, called Message In Message (MIM), adopts an advanced preamble detection function to enhance the PHY capture effect. To fully exploit MIM in multi-collision environments, frame transmission orders have to be carefully scheduled. It also requires tight time synchronization at multiple access points (APs), thus induces large overheads. In this article, we propose an opportunistic concurrent transmission protocol called D istributed O pportunistic M IM-aware C oncurrent T ransmission (DOMCT) which exploits the MIM functionality in a distributed manner obliterating the centralized control. In DOMCT, APs first prepare interference MAPs to discover the possible simultaneous MIM transmission opportunities. Detecting the inadvertent frame transmission from a neighboring AP, an AP transmits another frame intentionally if both frames can successfully be decoded at destination nodes by the MIM capture effect. Through both analysis and extensive ns-2 simulations, we show that DOMCT outperforms the legacy DCF by up to 61% and observe comparable performance to that of the centralized approach.

Sujets

• Capture effect
• Scheduling

Informations

• Publié par: biomed
• Publié le: 01 janvier 2012
• Nombre de lectures: 2
• Langue: English
• Poids de l'ouvrage: 2 Mo

Extrait

Kanget al. EURASIP Journal on Wireless Communications and Networking2012,2012:325 http://jwcn.eurasipjournals.com/content/2012/1/325

R E S E A R C HOpen Access A distributed message in message aware concurrent transmission protocol in IEEE 802.11 WLANs 1 2*3 1 Youngmyoung Kang , Joon Yoo, Joonsoo Leeand Chongkwon Kim

Abstract The IEEE 802.11 distributed coordination function (DCF) employs the carrier sense technology to avoid frame collisions. However, recent measurement studies demonstrate that the physical layer (PHY)capture effectfrequently occurs; even when frames collide, one of them can be decoded successfully if its relative signal strength is high enough. Furthermore, a new wireless PHY technology, calledMessage In Message(MIM), adopts an advanced preamble detection function to enhance the PHY capture effect. To fully exploit MIM in multicollision environments, frame transmission orders have to be carefully scheduled. It also requires tight time synchronization at multiple access points (APs), thus induces large overheads. In this article, we propose an opportunistic concurrent transmission protocol calledDistributedOpportunistic MIMaware Concurrent Transmission (DOMCT) which exploits the MIM functionality in a distributed manner obliterating the centralized control. In DOMCT, APs first prepare interference MAPs to discover the possible simultaneous MIM transmission opportunities. Detecting the inadvertent frame transmission from a neighboring AP, an AP transmits another frame intentionally if both frames can successfully be decoded at destination nodes by the MIM capture effect. Through both analysis and extensive ns2 simulations, we show that DOMCT outperforms the legacy DCF by up to 61% and observe comparable performance to that of the centralized approach. Keyword:WLANs, Concurrent transmission, Message in message (MIM), Capture effect, Scheduling

Introduction To support the ever growing demands for mobile com munications, IEEE 802.11 wireless LANs (WLAN) have continuously evolved to higher speed variants [1,2]. Des pite the improvements in physical layer (PHY) technolo gies, the goodput of WLANs does not increase in linear proportion to the PHY speed [3]. One limiting factor is large MAC overheads such as backoff time, long proto col header, ACK, and various interframe shifts. Many clever schemes that reduce the MAC overheads have been proposed including frame aggregation [1] and bin ary backoff optimization [4,5]. These schemes are called as the temporal approach because they reduce the time required for MAC layer operations.

* Correspondence: [e-mail] 2 Department of Software Design and Management, Gachon University, Seongnam, Korea Full list of author information is available at the end of the article

This article deals with the interference, another factor that degrades the WLANs performance. Interference is considered as one of the most important factors that decides wireless network throughput per unit area. Interference avoidance or reduction in multihop wire less networks has been the subject of active research during last several years and a plethora of mechanisms [68] that mitigate the effect of interference have been introduced. These mechanisms are referred to as a spatial approach because they essentially try to increase the number of simultaneous transmissions per unit area. Advanced signal processing makes it possible to decode one of simultaneously received frames—i.e., collided frames—successfully if certain conditions are satisfied. The conventional wisdom is that if two or more frames arrive at a receiver at the same time then all of them fail and re sult in a collision. Recent observations confirm the PHY capture effect[911]; if two frames collide within a pre amble period, a receiver can successfully lock on to a

© 2012 Kang et al.; licensee Springer. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.