AN EFFICIENT METHOD OF MOBILE IP BASED HANDOFF MECHANISM FOR WLAN-GPRS INTEGRATED NETWORK

This paper proposes a new technique for Mobile IP (MIP) registration by WLAN host (WH) of the Internet through GPRS network. The home agent (HA) of WH resides in the Internet. The gateway GPRS Support Node (GGSN) provides foreign agent (FA) functionality for WH in GPRS. After successful attachment with GPRS network in roaming scenario, WH needs two mandatory passes for MIP registration with HA. In first pass, it establishes PDP context in GPRS network and in second pass, it sends MIP registration request to FA at GGSN. This two-pass registration causes substantial delay for handoff from WLAN to GPRS. To minimize this delay, we propose a one-pass MIP registration technique through GPRS network by modifying the activate-PDP-context request (APCR) message. In this scheme, the APCR message carries MIP-registration request in its information field to GGSN. Therefore, FA at GGSN can process MIP registration packet before completion of PDP context in GPRS network. Thus, both PDP context creation and MIP registration are accomplished in one pass of signaling. This technique reduces handoff delay from WLAN to GPRS minimizing the control signals. We observed from simulation results that the proposed one-pass technique reduces handoff delay by 18% compared to that of two-pass method proposed in [8]