Effect of Vertical Handovers on Performance of TCP-Friendly Rate Control

this paper, we evaluate performance of TFRC during handovers between GPRS, WLAN, and UMTS.We measure behavior of TFRC and TCP flows in a testbed implementing vertical handovers using Mobile IP. To verify our testbed measurements and to study the effect of changes in path characteristics, we use an ideal handover model in the ns-2 simulator [40]. Essentially, an ideal handover is represented by a step change in the bottleneck link bandwidth, latency, and buffer size, as if a smooth handover with packet forwarding were implemented [7]. Throughput, aggressiveness, responsiveness, and fairness of TFRC are evaluated. We show that there are significant problems with using TFRC in the presence of vertical handovers. In particular, over a fast link TFRC receives only a fraction of TCP throughput, while over a slow link TFRC can starve concurrent TCP flows after a handover. Two proposals based on overbuffering and an explicit handover notification are demonstrated to be effective solutions to these problem

Multicasting Services and Information in Sweden – Final Report

The MUSIS project identified, developed, and tested a number of innovative mobile multimedia and information services to be distributed over wireless networks. The project ran from September 2004 through December 2005. Live market trials were conducted in Stockholm and Växjö. The project was initiated through SIBED, a joint Swedish-Israeli program that supports development and verification of technologies and applications. MUSIS had three main objectives: • To identify and implement innovative mobile media services, particularly those suited to multicast delivery. • To create an innovative model for content creation and distribution for this type of service. • To integrate a multicast platform in the network. The two first objectives of the project were fulfilled and field tested. Due to the extensive testing needed to install a new component in a live network, actual multicast delivery was not implemented across the live network: instead the look-and-feel o