Transparent Automated Handoff between 802.11b and CDMA-2000

Mayank Keshariya, Postgraduate Student

Dept of CSSE, University of Canterbury

Tue Dec 07 11:35:00 NZDT 2004 in Room 031, MSCS

Abstract

3 G wireless wide area mobile and the IEEE 802.11 family of local area wireless technologies are two of the most significant emerging wireless technologies and both architectures possess complementary characteristics. While 3G networks offer always-on, ubiquitous connectivity with relatively low data rates, 802.11 offers relatively low cost communication at higher data rates, but encompasses only small geographical areas, suitable for hot-spot applications in hotels, campus and airports. By developing a link between these two architectures, it is possible to achieve always best-connected services i.e. essentially continuous communication via the interface that offers the best price/performance characteristics.

However, the mobility requirements of mobile users change with various scenarios. Such users typically want to connect to the public or private networks most convenient to them at the time of connection. We present a versatile mobility solution, which accommodates different interfaces with different levels of security and authentication, which could be deployed as and when required. Our testbed is based on standardised protocols including Mobile IP, IPSec, AAA and 802.1x, and we present performance analysis to validate our architectural approach.

The motivation for heterogeneous networks arises from the fact that no single technology, service or architecture can provide ubiquitous coverage and high throughput across all geographical areas. Handoff is the mechanism by which an ongoing connection between a mobile node and a correspondent node is transferred from one point of access in the network to another. However, every handoff may result in the loss of data packets resulting in unnecessary network congestion. It also involves a sequence of events in the backbone network, including rerouting and reregistering the connection, which put additional loads on the network traffic. Handoff also has an impact on traffic matching and traffic density.

We have also proposed and analysed an automated algorithm for optimised handoff between heterogeneous interfaces to integrate different wireless networks. The interface selection algorithm is based on parameters such as current signal strength, interface priority, bit rate, throughput and noise interference. Additionally, introduction of link quality, hysteresis effect and dwell timers optimise the handoff initiation time as well as selection of the most optimal network.