IP-based seamless handover scheme using ANDSF in an untrusted environment

Abstract

In an Inter-WLAN-System, when an UE needs to hand over to an untrusted network, e.g., M, from its serving network, e.g., N, how to choose M and the best base station under M currently is a problem yet to be completely solved, no matter whether M and N belong to the same alliance group or not and no matter whether M and N are homogeneous or heterogeneous networks. In fact, 3GPP recommended ANDSF to solve this problem when N is a 3GPP network and M is a non-3GPP system or vice versa, i.e., when they are heterogeneous networks. Also, when selecting M, current approach neither considers the entire characteristics of mobile users, nor having significant discovery and selection policies to show the states of M, thus often leading UE to select an inappropriate M and/or a base station B in M. It results in the fact that after handover, UE may sometimes find that Radio Signal Strength Indicator (RSSI) of B is not strong, and even UE cannot connect itself to B since B's load is high. That means when M and N do not belong to the same alliance, the problem will be more serious. It also means that if we want to solve the mentioned problem in such an environment, the functions of ANDSF need to be enhanced. Therefore, in this paper, we first design an enhanced ANDSF, named E-ANDSF, which increases ANDSF with a Multiple Parameters Decision Making (MPDM) ranking scheme based on Proxy Mobile IPv6 (PMIPv6) protocol to provide PMAG in N with sufficient information, with which UE can hand over to an appropriate base station. We also propose an improved IP-based handover approach, called IP-based Handover Scheme assisted by E-ANDSF Function (IHEADs for short), which assists UE to hand over to an appropriate target base station by accessing the information provided by E-ANDSF.