Contention-Free Service with the PCF

To support applications that require near real-time service, the 802.11 standard includes a second coordination function to provide a different way of accessing the wireless medium. The point coordination function (PCF) allows an 802.11 network to provide an enforced "fair" access to the medium. In some ways, access to the medium under the PCF resembles token-based medium access control schemes, with the access point holding the token. This chapter describes medium access under the PCF, detailed frame diagrams for the PCF frames, and how power management operations interact with the PCF.

The PCF has not been widely implemented. A media server product for the home implemented the PCF, though it was not commercially successful. Some enterprise-class products have implemented the PCF because it gives the access points more control over access to the wireless medium, and helps the network to to wrest control away from the anarchy of a herd of individual stations. For many readers, this chapter may not be necessary. If you are not using a product that implements the PCF, there is no need to read this chapter unless you have an interest in the standard itself.

Introduction to Wireless Networking

Overview of 802.11 Networks

11 MAC Fundamentals

11 Framing in Detail

Wired Equivalent Privacy (WEP)

User Authentication with 802.1X

11i: Robust Security Networks, TKIP, and CCMP

Management Operations

Contention-Free Service with the PCF

Physical Layer Overview

The Frequency-Hopping (FH) PHY

The Direct Sequence PHYs: DSSS and HR/DSSS (802.11b)

11a and 802.11j: 5-GHz OFDM PHY

11g: The Extended-Rate PHY (ERP)

A Peek Ahead at 802.11n: MIMO-OFDM

11 Hardware

Using 802.11 on Windows

11 on the Macintosh

Using 802.11 on Linux

Using 802.11 Access Points

Logical Wireless Network Architecture

Security Architecture

Site Planning and Project Management

11 Network Analysis

11 Performance Tuning

Conclusions and Predictions



802.11 Wireless Networks The Definitive Guide
802.11 Wireless Networks: The Definitive Guide, Second Edition
ISBN: 0596100523
EAN: 2147483647
Year: 2003
Pages: 179
Authors: Matthew Gast

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