Handover mechanisms in next generation heterogeneous wireless ...

3.1 Introduction
Chapter 3
HANDOVER SECURITY
A variety of handover related issues, which lie in two categories: mobility engineering
and handover methodology have been discussed in Chapter 2. These research issues
have been raised in the literature mainly to address the heterogeneities arising from the
interworking of different wireless networks. However, they are incapable of addressing
seamless mobility when multiple network operators need to collaborate to extend
service coverage for their subscribers. For example, a mobile user roaming globally may
be unable to efficiently deal with a growing number of network operators. The demand
for seamless handover in a multi-operator environment creates new research challenges.
In recent years, the consumer market has witnessed the success of some new access
network technologies such as IEEE 802.11 WLAN (better known as Wi-Fi). Other
upcoming technologies, e.g. IEEE 802.16 (also known as WiMax), are being
commercially deployed. The increased affordability and other benefits such as high
bandwidth of these new access methods are encouraging both wireless Internet Service
Providers such as SpeedNet Services and retailers such as Starbucks to deploy their Wi-
Fi services in airports, train stations, hotels and so forth. Traditional cellular network
operators such as T-Mobile are beginning to provide Wi-Fi services. According to a
British consulting firm, Analysys Consulting Ltd. (Cambridge), the current cost of
transferring 1 Mb over an IEEE 802.11 network is between 0.2 and 0.4 eurocent,
compared with between 3 and 38 eurocents for GPRS networks [35]. Till 2007, 66,921
Wi-Fi hot spots have been deployed in the U.S., up 56% from the previous year [36].
Endorsed by the certification programs such as Wi-Fi ZONE from Wi-Fi Alliance [37],
Wi-Fi deployment will continue to grow. This situation is further underpinned by the
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