Enhanced Fast Handover for Network Mobility in Intelligent Transportation Systems

To maintain the Internet connectivity of a group of nodes in intelligent transportation systems (ITSs), the network mobility basic support (NEMO BS) protocol was standardized. The NEMO BS provides mobility for mobile network nodes (MNNs) in a moving network through a mobile router (MR). Since packet loss in NEMO dramatically increases during a handover as the number of MNNs increases, Mobile IPv6 fast handovers (FMIPv6) was adopted to reduce packet loss and handover latency. However, since FMIPv6 was originally designed for a single mobile node (MN), FMIPv6 based on NEMO (fNEMO) incurs a high tunneling burden on the link between the previous and new access routers (PAR and NAR, respectively). In this paper, we propose an enhanced fNEMO (EfNEMO) as an efficient fast handover scheme that significantly mitigates the tunneling burden and handover latency. In particular, EfNEMO performs a tentative binding update (BU) procedure to register a new care-of address (NCoA) for the MR with the MR´s home agent (HA) before the layer-2 handover. Consequently, EfNEMO delivers packets destined for MNNs via various paths between the HA and the NAR without any tunneling. Furthermore, EfNEMO reduces handover latency because it performs the registration to the HA in advance. By establishing an analytical model for the proposed EfNEMO, we investigate the handover performance of NEMO, fNEMO, and EfNEMO. In addition, we compare EfNEMO with NEMO and fNEMO in terms of the overall cost and the handover latency. Simulation is also performed to compare in a more realistic environment. The results of analysis and simulation show that EfNEMO significantly outperforms fNEMO and NEMO.