A New Soft Handover Mechanism using DCHs in 3GPP HSDPA Networks

In 3GPP (Third Generation Partnership Project) Release 5 (R5), HSDPA (High-Speed Downlink Packet Access) has been standardized to enhance the data rate of downlink packet transmission on top of WCDMA (Wideband Code Division Multiple Access) network. Even HSDPA supports up to 10 Mbps data rate through HSDSCHs (High Speed-Downlink Shared Channels), an UE (User Equipment) suffers from significant handover latency since HSDPA standard lacks supporting soft handover. Therefore, in this paper, we propose a new soft handover mechanism for HSDPA to reduce the handover latency by utilizing DCH (Dedicated Channel) instead of HS-DSCH. Simulation results show that the proposed soft handover mechanism reduces the packet IAT (Inter Arrival Time) less than 15 msec while HSDPA’s hard handover suffers from 190 msec packet IAT. It means that the proposed mechanism guarantees the minimum packet IAT requirement of the typical VoIP service in 20 msec. Furthermore, the proposed mechanism employees no service disruption for the data connection while an UE performs the soft handover procedure.