Smart transport layer based mobility for horizontal and vertical handoffs

Mobility management remains an important task to be investigated while integrating homogeneous and heterogeneous wireless networks. Traditionally, IP layer is widely used to implement roaming solutions including Mobile IP , HMIP , FMIP , FHMIP , etc. With the standardization of the Stream Control Transmission Protocol, which offers new interesting features such as multihoming and multistreaming, experiencing mobility at the transport level becomes more attractive. Indeed, this layer is endowed with various connectivity facilities and flow control features that render the transport layer more appropriate to support seamless roaming. To take benefit from these new facilities, several SCTPbased mobility schemes have been proposed. Nevertheless, none can claim to be the ultimate solution since they suffer from drawbacks such as unnecessary handoff delays and signaling loads. Moreover, the throughput measured immediately after a handoff is affected quite considerably by spurious retransmissions due to packet loss and failed Selective Acknowledgment messages (SACKs). In this paper, we propose a smart Hierarchical Transport layer Mobility scheme ( sHTM ) which deals with homogeneous and heterogeneous handovers, reduces packet loss, handoff latencies and improves throughputs. sHTM exploits the dynamic address reconfiguration feature of SCTP and introduces a new mobility unit to effect more efficient handoff procedures. Simulation results reveal that sHTM guarantees lower handoff latency and good throughput during the handoff period compared to existing mSCTP-based solutions.)