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Vehicular ad hoc network (VANET) standards, including IEEE 1609 WAVE and ETSI C-ITS, use IPv6 to interconnect VANET with the Internet. Considering the high vehicle speeds and short communication ranges of Road Side Units (RSUs), such vehicles may suffer from frequent service interruptions. A vehicle must have an IP address, and the IP mobility service should be supported during the movement of the vehicle. VANET standards such as WA VE or C-ITS use the IPv6 address auto configuration to allocate an IP address to a vehicle. In C-ITS, NEMO-BS is used to support the IP mobility. The vehicle moves rapidly, so the reallocation of the IP address as well as the binding update occurs frequently. The vehicle communication, however, may be disrupted for a considerable amount of time, and the packet loss occurs during this period. Finding the home address of the peer vehicle is also not trivial.

Several VANET IP mobility schemes have been proposed in order to mitigate this problem. However, these only support L3 handover, as the RSUs act as IPv6 access routers (ARs) for vehicles. Some VANET IP mobility schemes reduce the handover latency of the L3 handover but do not fundamentally mitigate the frequency of the L3 handover. As L3 handover indicates that the default router of the vehicle is changing, the vehicle must perform IPv6 configuration, including router discovery and neighbor unreachability detection. Since most L3 handover latency is caused by this IPv6 configuration, the L3 handover involves a higher signaling cost and longer handover latency than the L2handover. 

To solve these problems, we propose two schemes in this thesis. The first scheme is a network based L2 extension handover scheme for VANET. It decouples the AR functions from the RSU. An AR connects several RSUs via L2 links within its coverage. In this configuration, most inter-AR handovers are replaced with intra-AR handovers, so that the frequency of the L3 handover is decreased substantially. Therefore, the service disruption time caused by default router switching is also reduced, and the deployment of VANET can be made more flexible by decoupling the RSU and the AR. Proxy Mobile IPv6 is adopted in order to support inter-AR handover in the proposed scheme. Furthermore, the scheme supports seamlessness in both the intra-AR and inter AR handovers with buffering at the AR. The performance analysis and the simulation result reveal that the proposed scheme reduces the signaling cost and handover latency and also shows seamless packet delivery for vehicles.

In the second scheme, we propose a network-based identifier locator separation scheme for VANETs. The scheme uses a vehicle identity-based address generation scheme. It eliminates the frequent address reallocation and simplifies finding of the peer vehicle IP address. In the scheme, a network entity tracks the vehicles in its coverage and the vehicles share the IP address of the network entity for their locators. The network entity manages the mapping between the vehicle's identifier and its IP address. The scheme excludes the vehicles from the mobility procedure, so a vehicle needs only the standard IPv6 protocol stack, and mobility signaling does not occur on the wireless link. The scheme also supports seamlessness, so the packet loss is mitigated. The results of the simulation show the seamless packet delivery regarding the vehicles. 

Chapter 1 Introduction	1
1.1 Background	1
1.2 Problem Statement and Objectives	2
1.2.1 VANET environments	2
1.2.2 Identifier and Locator Separation Scheme	4
1.3 Approaches	5
1.3.1 Reduce the Layer 3 Handover	5
1.3.2 Network-based ID-LOC Separating Protocol for VANETs	6
2.1.1 IEEE Wireless Access in Vehicular Environments (WAVE)	10
2.1.2 ETSI C-ITS	12
2.1.2.1 ETSI Geo-Routing	13
2.1.2.2 ETSI GeoNetworking Header	14
2.1.2.3 Transmission of IPv6 Packets over GeoNetworking Protocols	15
2.1.3 Vehicle Safety Beacon messages	16
2.1.3 Authentication and Association Procedure in DSRC	17
2.2 Proposed Solutions	19
2.2.1 Host-based IP mobility Protocols	19
2.2.2 Network-based IP mobility Protocols	20
2.2.3 IP Address Allocation Protocols	21
2.2.3.1 Central IP Address Allocation	21
2.2.3.2 Distributed IP Address Allocation	21
Chapter 3 A L2 Extension Scheme for Providing Seamless Handover in VANET	22
3.1 Introduction	22
3.2 Architectural Design	25
3.2.1 System Architecture	25
3.2.1.1 Vehicle	26
3.2.1.2 L2 Switch	26
3.2.1.3 Road Side Unit (RSU)	27
3.2.1.4 Access Router (AR)	30
3.3 Handover Procedure	31
3.3.1 Intra AR Layer 2 Handover	31
3.3.2 Inter AR Layer 3 Handover	36
3.3.3 Applying PMIPv6 to C-ITS	37
3.4 Performance Evaluation	38
3.4.1 Mobility Model	39
3.4.2 Cost Modeling	39
3.4.2.1 Proxy Mobile IPv6	40
3.4.2.2 Layer 2 Handover Scheme	40
3.4.3 Handover Latency	41
3.4.3.1 Proxy Mobile IPv6	41
3.4.3.1 Layer 2 Handover Scheme	42
3.4.4 Signaling Cost Analysis Results	43
3.4.5 Handover Latency Analysis Results	45
3.5 Simulation	46
Chapter 4 An Identifier Locator Separation scheme for seamless VANET handover	57
4.1 Introduction	57
4.2 Architectural Design	59
4.2.1 System Architecture	59
4.2.1.1 Vehicle	60
4.2.1.2 Road Side Unit (RSU)	60
4.2.1.3 Identifier Locator Mapping Server (ILMS)	62
4.2.3 Registration Procedure	64
4.2.4 Communication Procedure	66
4.2.5 Handover Procedure	69
4.3 Comparison	71
4.3.1 Identifier Allocation manner	71
4.3.2 ID-Locator mapping manner	72
4.3.3 Destination Address Resolution mechanism	73
4.3.4 Packet Forwarding	74
4.3.5 Mobility Support	76
4.4 Simulation	77
Chapter 5 Conclusions	89
Chapter 6 Discussions	91