Multimedia SIP sessions in a Mobile Heterogeneous Access Environment

Maintaining multimedia sessions by means of SIP [3] signaling has often been termed as application layer mobility management scheme [5]. There have been numerous proposals [1], [4], [2] to support different types of mobility using SIP signaling which is generally used to set up and tear down the multimedia stream. Mobility management in heterogeneous networks plays a very important role since the user could be moving between multiple types of access networks involving many service providers during a multimedia session. These access networks could be 802.11b, CDPD, or GPRS based network supporting DHCP or PPP servers in the networks. The movement of the mobile host can be between the access networks where each access network may belong to the same subnet, same domain or different one. In this case the end-client would have access to both the networks at the same time, but connectivity to the network would be determined by any local policy defined in the client itself such as signal strength or any other measurement based on QoS parameter of the traffic. This paper discusses various issues associated with SIP signaling for maintaining continuity of signaling and media flow in a Local Area Network and Wide Area Network environment.