Abstract— Next-generation wireless systems are envisioned to have an all-IP-based infrastructure with the support for heterogeneous access technologies. The design of intelligent mobility management techniques is one of the key research challenges these systems. In this paper we will outline the current challenges in FMIPv6 as a mobility management technique for next- generation wireless systems. We will analyse the solutions that have been proposed to solve these mobility management challenges. In addition, we will look at the issues that the current solutions did not address. We will then propose a cross-layer design approach utilising the IEEE 802.21 MIH services such as predictive layer 2 triggers to optimize FMIPv6. Index Terms—Mobility Management, Handover delay, FMIPv6 I. BACKGROUND mong many proposed mobility management solutions, Mobile IPv6 (MIPv6) [1] has been proposed as the standard to solve the problem of mobility. It does this by redirecting packets for the mobile node (MN) to its current location. In MIPv6 the period during which the MN looses connectivity with its current link until the time it receives the first packet after connecting to the new link is known as handover latency. The overall handover latency in MIPv6 consists of Layer 2 (L2) handover latency and Layer 3 (L3) handover latency. L2 handover latency is the period when the MN is disconnected from the air-link to the current Access Router (AR) until the time it connects to the air-link of the new AR [1]. In L3 handover, there are latencies incurred due to the processes of movement detection, Care-of-Address (CoA) configuration and Binding Updates (BU). The handover latency incurred by MIPv6 is intolerable for time sensitive and real-time traffic [2], since the MN Sabelo Dlamini is with Communications Research Group at the Department of Electrical Engineering, University of Cape Town, Private Bag, Rondebosch, 7701, South Africa. (phone: 021-650-2813; fax: 021-650-3465; e- mail: dlaminis@crg.ee.uct.ac.za) is not able to send or receive traffic during this interval. Various protocols have been proposed to optimize handover latency in MIPv6 e.g. Fast Handovers in MIPv6 (FMIPv6) [2] being one of them. FMIPv6 protocol has been designed to reduce handover delays incurred due to movement detection, Care-of-Address (CoA) acquisition and binding update (BU) events. This is done with the aid of anticipation based Layer 2 (L2) trigger information as well as by obtaining the subnet prefix information from the New Access Router (nAR) while the MN is still connected to its current/old Access Router (oAR). In order to form a new CoA, FMIPv6 relies on the oAR to resolve the network prefix of the nAR based on the L2 identifier reported from the MN. The anticipation mechanism specified by FMIPv6 suffers from the problem of timing hence it may cause the handover process to start earlier or later than the actual handover. This reduces the certainty about the MN’s movement. Also sudden degradation of the wireless link during the handover initiation phase may cause the MN to lose connectivity with the oAR. In this case, if the handover anticipation time is large, then the MN may not have sufficient time for new CoA (NCoA) configuration while being attached to the oAR’s link. Consequently, there would be long handover latencies. II. RELATED WORK Various schemes have been proposed to provide more definitive L2 triggers to reduce handover delays in FMIPv6. The work in [3] and [4] use the IEEE 802.21 MIH services [9] to provide timely L2 triggers. However link quality monitoring and decision-making algorithms that execute L2 triggers are not considered. In [5] the link quality and the received signal strength indication (RSSI) considered. However the effect and the choice of the prediction algorithm used is not considered. In [5] the Least Mean Square linear prediction algorithm is used, whilst in [6] and [7] Linear Regression and Exponential Smoothing are used respectively. There has been no work performed that Optimization of handover latency in FMIPv6 using predictive Layer 2 triggers Sabelo Dlamini, Student Member, IEEE and Mqhele E. Dlodlo, Member, IEEE A