CURRENT RESEARCH FOR MOBILITY MANAGEMENT IN 4G

There is considerable research being done on mobility management. Mobility solutions can be found by either developing improvements within the current architecture, or by revising the architecture to reflect the changing environment. The solutions propose different addressing and packet forwarding schemes. Almost all of them are IP based solutions, which allow interoperability and easy integration with the existing architectures. Within each of the solutions the relevance to mobility and their strengths and limitations, are discussed in brief:

1. The Internet Indirection Infrastructure is a scalable, self-organizing scheme which easily integrates with legacy systems. It proposes an architecture that offers a communication abstraction based on rendezvous points in an overlay network. When a host wants to send a packet, it forwards the packet to one of the servers it knows. A packet keeps traversing the network till the target server is reached; this leads to delay in route discovery and packet forwarding.
2. FARA (Forwarding directive, Association, and Rendezvous Architecture) is an ongoing project whose main purpose is to provide mobility by separating location from identity. One advantage is that neither an entirely new namespace nor a globally unique one is required for the entities. It allows several different forwarding mechanisms to co-exist in the network, resulting in variability in characteristics like mobility, identity, and anonymity. However, FARA model fails to take into consideration many packet forwarding issues like performance of network nodes, or the balance of anonymity vs. identity for communicating endnodes. It does not accommodate for security either.
3. Host Identity Payload (HIP) provides another way of breaking the binding between identities and topological locations of network nodes. HIP introduces new cryptographic identities that can be dynamically mapped to IP addresses. However, HIP Host Identity (HI). being a public key, is not practical in all actions; it is somewhat long, it needs to be hashed before being used in IPv6 applications. While providing support for mobility and multi-homing with a major architectural change in the addressing concept, the solution requires only small changes in current host implementations.
4. IST MIND develops the concepts and protocols generated in BRAIN by enabling hosts to cooperate with self-organizing wireless ad-hoc networks. It provides independent, interoperable solutions for local/micro-mobility from global mobility.
5. DRIVE specifies a multi-access architecture allowing for seamless intersystem- handover. The concept of a host-controlled flow control was developed to enable parallel usage of different access systems. The architecture is based on Hierarchical Mobile IP, extended by an AAA (Authentication, Authorization and Accounting) component. Over DRiVE extends the scenario with moving networks (e.g. vehicles, trains, etc.) in a multiradio/multi-access environment, defines a Mobile IP-based solution, and focuses on multicast support. The project has strong influence on the ongoing work within the IETF NEMO (Network Mobility) group.
6. The Architectural Principles of Ambient Networks require the integration of a multitude of different communication environments, rather than suffering from heterogeneity. The approach is to use network composition as the principle instead of terminals; networks as such can form the basic building block of the communication architecture. Network composition is a more powerful concept than the simple internetworking as enabled by the Internet Protocol. The current Internet assumes homogeneity in the environment in which to provide control. Ambient Networks have the potential to solve this issue of fragmented control.
7. Developing Standards for Seamless & Secure Mobility: Several industry consortia and standard development organizations such as the IEEE 802 LAN/MAN Standards Committee and the Internet Engineering Task Force (IETF) are expending considerable efforts to develop a common framework and extend existing mobility protocols in order to facilitate and optimize handover performance. Various activities are currently under way, including extensions to Mobile IP at the IETF, and the formation of the Media Independent Handover (MIH) working group in IEEE 802, in addition to several task groups within IEEE 802.11 in order to deal with roaming (IEEE 802. 11r) and interfacing to external networks (IEEE 802.11u) .
8. Interference Alignment Techniques for Wireless Interference Channels: The project is going at Samsung Advanced Institute of Technology, Korea from Nov. 2008 onwards.
9. Transmission Techniques for Multiple MIMO Relay Channels: This project is being developed at LG Electronics, Korea from Aug. 2008.
10. Physical Layer Design for High-speed wireless Systems (9^th): The project is going at Interstate Technology & Regulatory Council.

The best solution among the current and ongoing projects will be the one that successfully addresses all the related challenges as well as allows scalability for future possibilities. A few open issues, however, need to be addressed in most of the existing projects; i.e. synchronization of the entire network and sound QoS.