Supporting mobile E-learning application reliability through multi-homing

Multi-homing technologies enable a communication session between a number of hosts to be transparently implemented over multiple underlying physical networks simultaneously. Increasingly mobile devices are supporting a hybrid of underlying physical networks; an example of such a device is the Nokia 9500 Communicator which supports mobile network access through GPRS and Wireless LAN access through 802.11b. As the physical capabilities of devices tend towards hybrid network support, mobile application developers are adopting multi-homing technologies in order to overcome the limitations of mobile environments in which frequent disconnections and fluctuating bandwidths are likely. In such an environment the path redundancy offered by multi-homed protocols has a clear attraction. This paper investigates the use of the multi-homed transport layer Stream Control Transmission Protocol (SCTP) in the development of E-learning applications. It describes and evaluates a test implementation which simulates the use of a media streaming E-Learning application in a large classroom in which wireless coverage is achieved through multiple overlapping WLAN access points. Finally results are presented which illustrate the ability of SCTP to maintain a quality end user experience in the case of catastrophic network failure.