Towards a Media Independent Handover Based Approach to Heterogeneous Network Mobility

In recent years the number and diversity of networks available to mobile computing devices has increased dramatically. It is now feasible for a device to support multiple networks such as 3G, 802.3, 802.11 and even 802.16. Given the diversity of these networks in terms of range and bandwidth, there is a need to define a seamless approach to network handover. While current 802 standards provide the facility to detect and select access points, these mechanisms are specific to individual network types. Moreover, current 802 standards do not provide the facility, or even the availability, of information triggers for handover. In order to address issues relating to heterogeneous network handover, the IEEE have proposed a new standard: 802.21, also referred to as Media Independent Handover. It is proposed that the emerging 802.21 standard will enable a mobile device to detect and initiate handover from one network to another. Currently the 802.21 standard is at draft stage and no implementations are available. This paper investigates how elements of the proposed standard can be utilised in conjunction with the transport layer Stream Control transmission Protocol (SCTP) in order to facilitate seamless network handover. We compare a pre-emptive 802.21 oriented switch strategy against standard fault reactive SCTP strategies. Results indicate that the 802.21 oriented strategy behaves more effectively than conservative SCTP switchover strategies, and has equivalent performance to aggressive SCTP switchover strategies.