Local Area Networks

ISBN-13: 9780738156736 / Angielski / Miękka / 2008 / 200 str.

Osama S. Aboul-Magd

Opis

This book is part of the IEEE Standards Wireless Networks Series. This book describes Wireless Local Area Networks Quality of Service enhancements. Those enhancements enable the support of real-time applications such as voice and video. The scope of the book includes: - Overview of QoS mechanisms and architectures. - WLAN QoS mechanisms and relationship to QoS general architectures. - Performance analysis and case studies. WLAN QoS planning and engineering are challenging tasks to both network operators and end users. This book is an attempt to satisfy the need for better understanding of WLAN QoS features as well as the related engineering challenges. The reader will be able to understand WLAN QoS mechanisms and features in a simple and clear way beyond that obtained by just reading standard documents. The reader of the book should be able to understand: - WLAN QoS basic operation. How WLAN QoS is related to other QoS architectures especially IP QoS, and the related interworking issues. - How to tackle WLAN QoS main issues including admission control, scheduling, and buffer management. How to engineer a WLAN-based network to support QoS-based applications.

Spis treści

Preface xi

Acronyms xv

Chapter 1 Quality of Service Mechanisms and Metrics 1

Traffic Management Mechanisms 1

Traffic Conditioning 4

The Metering Function 5

Marker 9

Dropper 9

Shaper 10

Admission Control 11

Nodal Mechanisms 15

Transmission Scheduler 15

Buffer Management 22

Feedback Congestion Management 26

Performance Metrics 31

Throughput 32

Delay 33

Packet Loss 36

Simple Queueing Models 36

MMl Queueing System 38

MG 1 Queueing System 41

Chapter 2 QoS Architectures 43

Reservation Model 43

Reservation Model Example 45

Service Types 49

Differentiation Model 54

Differentiating Model Examples 56

IEEE Standard 802. IQ Ethernet Frame Priority 62

Chapter 3 IEEE Standard 802.11 Overview 65

IEEE 802.11 Architecture and Frame format 65

IEEE 802.11 PHY Overview 69

IEEE 802.1 la PHY 69

IEEE 802.1 lb PHY 71

The IEEE 802.1 lg PHY Overview 73

The IEEE 802.11 MAC Overview 75

Distributed Coordination Function (DCF) 75

Point Coordination Function (PCF) 81

Power Management 85

IEEE 802.11 Throughput 86

IEEE 802.11 Frame Types 90

A Queueing Model for PCF Performance 92

Chapter 4 IEEE 802.11 QoS Features 97

IEEE 802.1 le MAC Overview 97

Data Frame Format 99

Association to QoS BSS 102

EDCA Operation 105

HCCA Operation 108

Admission Control 110

EDCA Admission Control 119

HCCA Admission Control 123

Direct Link Setup 125

Block Acknowledgment (BA) 129

Throughput Improvement Due to Block Acknowledgment 132

Power Management Using APSD 134

WiFi Multimedia (WMM) Specification 136

IEEE 802.1 In (High Throughput) MAC Features 139

Frame Aggregation 139

IEEE 802.1 In Block Acknowledgment 141

A Simple Engineering Example 143

Chapter 5 Interworking with WLAN QoS 145

Common WLAN Deployment Scenario 147

WLAN QoS Interworking with Ethernet 148

WLAN QoS Interworking with IP Networks 151

Chapter 6 Concluding Remarks 157

Bibliography 159

Index 163

O autorze

Osama Aboul–Magd holds a Bachelor of Science degree in Electrical Engineering from Cairo University, as well as an M.A.Sc. and Ph.D. from the University of Toronto. As a Senior Advisor for Nortel Networks, he is involved in the planning and design of QoS and traffic management features for many products covering multiple technologies including Frame Relay, ATM, IP, and Ethernet. In addition to his interest in WLAN QoS and MAC related issues, Mr. Aboul–Magd has made numerous contributions to the standards development community. He was a key leader in the ATM Traffic Management specification at the ATM Forum and editor of the Ethernet Traffic Management Specification at the Metro Ethernet Forum. Mr. Aboul–Magd also co–authored the IETF (MPLS WG) proposed standard, Constraint–Based LSP Setup Using LDP and was a primary author of the OIF optical user–network interface (O–UNI) implementation agreement, OIF2000.125.6, Sept. 2001. In 2003, he began participating in the IEEE 802.11 Working Group, increasing his involvement in the standards development process. Throughout his career, Mr. Aboul–Magd has developed over twelve patents in various technology arenas.