Demwap

A Bitcricket White Paper

www.bitcricket.com

Inside 802.11n Wireless LANs

Practical Insights and Analysis

December 2007 By J. Scott Haugdahl Founder and CTO, Bitcricket

Abstract The IEEE 802.11n Draft Standard specifies a next generation wireless LAN (WLAN) technology promising nearly twice the reach and far better throughput than 802.11abg legacy devices. The technology is very complex (the draft is over 470 pages long) and has evolved during the standards process with a history of battle lines between contributors. The dust has settled and we are finally seeing real deliverable technology and interoperability. This 16-page white paper takes a brief look at the history behind the process, the convergence to a draft standard, the promise of 802.11n, details on improvements in both transmission speed and protocol efficiency, and several major milestones pushing 802.11n into the enterprise. Unique to this white paper is a look at 802.11n in action by capturing frames from an operational system using 40 MHz bandwidth, multiple antennas, and multiple streams. Such capture and analysis takes us inside 802.11n operation, helping us to better understand how it works, especially new features such as block ACKs and aggregated frames.

Inside 802.11n Wireless LANs: Practical Insights and Analysis

Contents

A Brief Historical Perspective .............................................................................................. 2 March Madness ................................................................................................................... 4 The Promise......................................................................................................................... 5 Cutting the Overhead .......................................................................................................... 7 802.11n Captured Frame Analysis ...................................................................................... 9 Major Milestones: 802.11n Goes...