Mobile Inter-networking with IPv6 : Concepts, Principles and Practices

20

Fast Handover in aWireless LAN

It’s hard to imagine being mobile without assuming wireless.    –(somewhat obvious) self revelation

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20.1 INTRODUCTION

WLAN has quickly become a technology choice for homes, enterprises, metro mesh networks, rural mesh networks and so on. Due to low cost, higher bandwidth and ease of use, it has found large scale acceptance. Enterprises have found it appealing especially for the "mobile VoIP" potential. It is not only feasible to replace a fixed telephone with a device equipped with WLAN, but also enhance the user experience available with VoIP. Increasingly, such "devices" are becoming mobile phones which offer roaming to cellular networks when a user is out of coverage of WLAN. So, enterprises can trade the cost of their fixed telephony for mobile telephony while improving the productivity. Given the recent advances in mobile computing, mobile rich-media communication is not too far behind.

We saw in Chapter 14 the actions performed by a mobile node on a typical day:

while (true) do

{

1. Establish link connectivity

2. Establish IP connectivity

3. Request network resources

4. Run application(s)

5. Undergo handover

6. Go back to step 1

}

We return to fast handover in this chapter, focusing on implementation of the protocol over a wireless medium. We use WLAN as the wireless access medium and investigate the radio-specific problems as well as the ...