mSIP: Extension of SIP for Soft Handover with Bicasting

This Letter proposes an extension of session initiation protocol (SIP) to support soft handover with bicasting, named mobile SIP (mSIP). In the mSIP scheme, the soft handover is achieved by bicasting to the mobile node in the handover region. For this purpose, a new handover' header is defined in the SIP re-INVITE message. The mSIP handover can reduce handover latency and loss, compared to the SIP handover.