As the demand of, requesting the Internet without any disturbance by the mobile users of any network is increasing the IETF started working on Network Mobility (NEMO). Maintaining the session of all the nodes in mobile network with its home network and external nodes can be provided by the basic Network Mobility support protocol. It provides mobility at IP level to complete networks, allowing a Mobile Network to change its point of attachment to the Internet, while maintaining the ongoing sessions of the nodes of the network. The Mobile Router (MR) manages the mobility even though the nodes don't know the status of mobility. This article discusses few basic concepts and limitations of NEMO protocol and proposes two ways to optimize the NEMO routing technique for registered and unregistered Correspondent Nodes (CN) of the Mobile Network Node (MNN).
INTERNET access requirement in heterogeneous environments is increasing. The success of cellular communication shows the interest of users in mobility access. These networks are expected to provide not only voice services, and also the data services. IP is the base technology for future networks, which can provide all kind of services with different access modes like fixed and mobile. But IP was not designed for supporting mobility of users and terminals. The IETF has defined some IP-layer protocols that enable terminal mobility in IPv4 and IPv6 [1] networks. But, these protocols do not support the movement of a complete network that moves as a whole and changing its point of attachment to the fixed infrastructure, that is, network mobility. The IETF created a working group: NEMO (Network Mobility), with the aim of extending existing host mobility solutions to enable the movement of networks in IPv6.
Basically IP networks were not designed in terms of supporting for mobility or mobile environments. IP addresses are locators that specify, based on a routing system, how to reach the terminal that is using that address, it can also part of the endpoint identifiers of a communication, and upper layers use the identifiers of the peers of a communication to identify it.
The IETF has been working for the problems in terminal mobility; the NEMO group in IETF comes up with IP layer solutions for both IPv4 and IPv6 that enable the movement of terminals without stopping their ongoing sessions. These solutions are even being completed with proposals that improve the efficiency of the base solution, particularly in micromobility environments. The issue of terminal mobility has been analyzed recently in [2].
The first step in adaptation of mobile networks is terminal mobility support in IP networks, but there exists also the need of supporting the movement of a complete network that changes its point of attachment to the fixed infrastructure, maintaining the sessions of every device of the network: what is known as network mobility in IP networks. In this case, the mobile network will have at least a router called as Mobile Router (MR) that connects to the fixed infrastructure, and the devices of the mobile network will obtain connectivity to the exterior through this MR. The IP terminal mobility solution does not support the movement of networks, because of that, the IETF NEMO WG [3] was created to specify a solution, at the IP layer, to enable network mobility in IPv6. Some of the applications, which use the Internet access, are, (i) Public transportation systems: These systems would let passengers in trains, planes, ships, etc to access the network.
(ii) Personal networks: Electronic devices carried by people, such as PDA’s, photo cameras, etc. would connect through a cellular phone acting as the MR of the personal network.
(iii) Vehicular scenarios: Future cars will benefit from having Internet connectivity, not only to enhance safety, but also to provide personal communication, entertainment, and Internetbased services to passengers The NEMO working group was developed the basic solution to the network mobility problem in IPv6 networks by modifying the IPv6 host mobility solution (MIPv6). But the solution has to be flexible to deal with different mobile networks configurations, in particular, networks containing different subnets and nested mobile networks. Vehicle-to-Internet can be reached through NEMO BSP. Enabling broader communication facilities is an important contribution to the global trend towards ubiquitous communications [7] so; along with technologies of wireless communication, it is possible to install wireless network equipment in vehicles for people to make network connections. So, technologies like NEMO along with VANET can be used for vehicular network since they pose their own purposes [8]. Average frequency of route changes with times the NEMO communicates through VANET.
ROMSGP (receive on more stable group path) [9] will group nodes according to their velocity vectors. If two vehicles were in different groups, the connection between them is considered unstable. In such situation, a penalty will be added to the routing path. Meanwhile, if a node tries to send a packet, it will search it routing table to find next one with less penalty. Additionally, LET (Link Expiration Time) is consider to choose the most stable path i.e. to do a new route discovery before the link being expired. Mobile host in a wireless network may move with certain mobility patterns, such as regular and random movement patterns. Normally, VANET belongs to the regular movement patterns Su et al [10] propose the use of mobility prediction to improve the performance of ad hoc routing [10] with non-random behaviors. In case, if cars are close enough to communicate directly using an ad hoc network a better bandwidth through the infrastructure can be achieved. The reason is that, although the number of hops can be similar, the
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