Book contents
- Frontmatter
- Contents
- Authorship by Chapter
- Foreword
- Preface
- Part I Introduction to 802.11
- Part II 802.11 Quality of Service
- Chapter 3 WLAN QoS
- Chapter 4 Performance Understanding of IEEE 802.11 DCF and IEEE 802.11e EDCA
- Chapter 5 Cross-layer Optimized Video Streaming over Wireless Multi-hop Mesh Networks
- Part III 802.11 Security
- Part IV High Throughput 802.11
- Part V 802.11 Mesh Networks
- Part VI 802.11/Cellular Interworking
- Part VII Coexistence
- Part VIII 802.11 Network and Radio Resource Management
- Part IX 802.11 Range
- Part X 802.11 Hardware Design
- Part XI Wi-Fi Hotspots
- Part XII Wi-Fi Applications
- Part XIII Ultra WideBand (UWB)
- Part XIV Public Wireless Broadband
- Epilogue
- Index
Chapter 4 - Performance Understanding of IEEE 802.11 DCF and IEEE 802.11e EDCA
from Part II - 802.11 Quality of Service
Published online by Cambridge University Press: 10 December 2009
- Frontmatter
- Contents
- Authorship by Chapter
- Foreword
- Preface
- Part I Introduction to 802.11
- Part II 802.11 Quality of Service
- Chapter 3 WLAN QoS
- Chapter 4 Performance Understanding of IEEE 802.11 DCF and IEEE 802.11e EDCA
- Chapter 5 Cross-layer Optimized Video Streaming over Wireless Multi-hop Mesh Networks
- Part III 802.11 Security
- Part IV High Throughput 802.11
- Part V 802.11 Mesh Networks
- Part VI 802.11/Cellular Interworking
- Part VII Coexistence
- Part VIII 802.11 Network and Radio Resource Management
- Part IX 802.11 Range
- Part X 802.11 Hardware Design
- Part XI Wi-Fi Hotspots
- Part XII Wi-Fi Applications
- Part XIII Ultra WideBand (UWB)
- Part XIV Public Wireless Broadband
- Epilogue
- Index
Summary
Introduction
One of the key factors for the wide acceptance and deployment of IEEE 802.11 Wireless Local Area Networks (WLANs) is the simplicity and robustness of the Medium Access Control (MAC) protocol. Based on the well-known carrier sense paradigm, with an exponential backoff mechanism devised to minimize the probability of simultaneous transmission attempts by multiple stations, the protocol is able to work in presence of interference, which is very critical for networks operating in unlicensed spectrum. In fact, interfering sources are simply revealed by the carrier sense mechanism in terms of channel occupancy times, or by the acknowledgement mechanism in terms of collisions. However, the simplicity and the robustness have often been traded off with the efficiency of the access protocol, in terms of radio resources which are wasted or underutilized.
In this chapter, we provide a detailed analysis of the 802.11 distributed access protocol, by examining the protocol parameters which most critically affect the protocol efficiency. We quantify the protocol overheads due to control information (i.e., physical headers, frame headers, acknowledgement and other control frames) and to the distributed management of the channel grants (i.e., collisions and idle backoff slots). Then, we consider the distributed channel access extensions, defined in the recently-ratified 802.11e standard in order to support service differentiation among stations with different Quality-of-Service (QoS) requirements. Finally, we attempt to show how these parameters affect the resource repartitioning among the stations and how they can coexist with legacy DCF stations.
- Type
- Chapter
- Information
- Emerging Technologies in Wireless LANsTheory, Design, and Deployment, pp. 63 - 104Publisher: Cambridge University PressPrint publication year: 2007
- 2
- Cited by