A New Soft Handover Mechanism using DCHs in High-Speed Downlink Packet Access Networks

In 3GPP (Third Generation Partnership Project) Release 5 (R5), HSDPA (High-Speed Downlink Packet Access) has been standardized to enhance the data rate downlink packet transmission on top of WCDMA (Wideband Code Division Multiple Access) network. Even HSDPA supports up to 10 Mbps data rate through HS-DSCHs (High Speed-Downlink Shared Channels), an UE (User Equipment) suffers from significant handover latency, since HSDPA standard does not 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 set-vice in 20 msec. Further more, the proposed mechanism employees no service disruption for the data connection while an UE performs the soft handover procedure.