Abstract

SCTP (Stream Control Transmission Protocol) provides interesting features, as multihoming and multistreaming, to enhance information transport performances over air interfaces. Additional extensions have been proposed to adapt SCTP to wireless context (mSCTP: mobile SCTP). However, published approaches do not take into account channel state information during handover processes. The present work proposes a new extension for SCTP which aims at improving transport protocol performance in wireless environments: QoS_Measurement_chunk. It relies a) on a cross-layer mechanism taking place between SCTP and the link layer and b) on a new SCTP control chunk. It allows the emission of radio information from the mobile to its SCTP peer. These information can be used by SCTP layer to adapt transmission rate to the current radio transmission conditions. So, SCTP congestion control parameters are modified to take into account new radio conditions. The combined using of QoS_Measurement_Chunk and multihoming feature provide a data handover with a performance improvement. This new mechanism is useful to perform intra or inter RAT (Radio Access Technology) data handover. The obtained simulation results are compared with the standard SCTP when downlink transmission is considered in handover situation and present better performance in terms of data throughput over the access network.

Key words: Inter-RAT handover, SCTP, Qos_measurement_chunk, cwnd adaptation, flow control.