Incorporating AP selection and call admission control for seamless handoff procedure

A complete handoff procedure of a mobile node in wireless network includes access point (AP) selection, call admission control (CAC), and IP address allocation. Most current handoff schemes only deal with the Layer-3 address allocation, that is, the IP address re-allocation. Without the integration with AP selection and CAC, the mobile node (MN) may be disconnected before a new IP address is allocated, which makes seamless handoff impracticable. In this paper, an integrated system is proposed. Firstly, AP selection is accomplished by choosing the AP with the smallest number of users associated with. We gather the information of active users on each AP through the modified beacon frames. Then, both call admission and a new IP address pre-fetch are operated through the DHCP relay simultaneously. Particularly, Fairness-enhanced limited fractional guard channel policy (FLFGCP) for CAC scheme and two additional thresholds, dropping probability threshold (DPT) and blocking probability threshold (BPT), are explicitly defined. Both DPT and BPT are applied to balance the dropping probability of handoff calls and blocking probability of new calls respectively. An OMNET++ simulation which demonstrates the applicability of cooperating the AP selection and call admission control for seamless handoff is included.