A bit more about the technologies involved...

Jean Tourrilhes
Hewlett Packard Laboratories, Palo Alto

3 August 00

La culture c'est comme la confiture, moins on en a, plus on l'étale...

1 Introduction

I'm not pretenting to teach a course on Wireless LAN. I guess that many books explain the subject in more details and accuracy than me (anyway, I hope). I just feel that many users of Wireless LANs don't really know what is inside their magic piece of kit and are curious about it. I hope that this document will help you to understand a bit more of the different technological aspects and compare the different Wireless LANs functionalities.

While working on the Wavelan driver and the Wireless Extensions, I've gathered much information trying to understand how it works. The vendors documentation and web sites have been also very helpful, many of them really try to explain the technologies behind their products and provide white papers. The Net contains also a lot of papers and reports on the subject of wireless LANs and radio communications.

I have still a limited knowledge and understanding of the wide numer of technologies used by Wireless LANs, so I hope that it is mostly accurate, complete and that it will help you. If some knowledgeable person could help me to improve this document, or if anybody could give me some suggestions or corrections, I would be glad...

This document is the third part of the Linux Wireless LAN Howto, located at http://www.hpl.hp.com/personal/Jean_Tourrilhes/Linux/, and available in HTML, PostScritp or PDF form. Please refer to its first part for details (copyright, disclaimers...) and a list of some other web pages on the subject.

2 MAC, LAN, Layer and other strange words...

MAC, LAN, Layer and other strange words...

3 Anatomy of a radio LAN

A radio network is a collection of nodes communicating together through radio devices, using radio waves to carry the information exchanged (obvious, isn't it ?). It is sometime called a radio Ethernet, by analogy of the wired technology. Most radio devices are a card (ISA, Pcmcia) to plug in a PC (or workstation), and interact directly with the standard networking stack on it (no need of PPP or any specific protocol stack).

Anatomy of a radio LAN

4 The radio modem (physical layer)

This section of the document deals with all the issues related to the physical layer (bottom of the pile, OSI wise :-), or in our case the radio modem.

The radio modem (physical layer)

5 The MAC level (link layer)

This section of the document focus on the next layer up, the link layer. This mostly comprise the MAC (Medium Access Control) protocol. Different MAC protocols and techniques are presented.