Hi,

Wireless communication is the transfer of information over a distance without the use of electrical conductors or "wires". In this paper we discuss how Mobile IP works and the advantages of it in wireless communication.

In IP networks, routing is based on stationary IP addresses, similar to how a postal letter is delivered to the fixed address on the envelope. A device on a network is reachable through normal IP routing by the IP address it is assigned on the network.

The problem occurs when a device roams away from its home network and is no longer reachable using normal IP routing. This results in the active sessions of the device being terminated. Mobile IP was created to enable users to keep the same IP address while traveling to a different network (which may even be on a different wireless operator), thus ensuring that a roaming individual could continue communication without sessions or connections being dropped.

Because the mobility functions of Mobile IP are performed at the network layer rather than the physical layer, the mobile device can span different types of wireless and wireline networks while maintaining connections and ongoing applications. Remote login, remote printing, and file transfers are some examples of applications where it is undesirable to interrupt communications while an individual roams across network boundaries. Also, certain network services, such as software licenses and access privileges, are based on IP addresses. Changing these IP addresses could compromise the network services.

The Mobile Internet Protocol, or better known as Mobile IP, is a protocol that adds to the already existing Internet Protocol by making the movement of a node transparent to applications on its original network. One knows that a host address is made up of a network number and a host part. This network number tells the user what network the host is attached to. Original Internet Protocol algorithms tell certain routers how to get packets to their correct networks. Now with the regular Internet Protocol if the host disconnected itself from its original network and joined another network, the host would never receive any packets because the host has the same IP address from its old network that would not be recognized by the network in which it joined. In essence the host would seem to be missing because its IP address does not match its new network number and therefore would never receive any packets.

Because of this problem, Mobile IP was created so that mobile nodes could freely move from network to network without the fear of losing data or interrupting current computer applications and settings.

Applications:

Mobile IP is most often found in wired and wireless environments where users need to carry their mobile devices across multiple LAN subnets with different IP addresses. It may for example be used in roaming between overlapping wireless systems, for example IP over DVB, WLAN, 3G and BWA. Mobile IP is not used within cellular systems such as 3G, to provide transparency when internet users migrate between cellular towers, since these systems provide their own data link layer handover and roaming mechanisms.

In many applications (VPN and VoIP, to name a few), sudden changes in network and IP-address can cause problems.

Advantages:

Mobile IP uses a strong authentication scheme for security purposes. All registration messages between a Mobile Node and Home Agent are required to contain the Mobile-Home Authentication Extension (MHAE).

To sum up, the number of wireless devices for voice or data is projected to surpass the number of fixed devices. Mobile data communication will likely emerge as the technology supporting most communication including voice and video. Mobile data communication will be pervasive in cellular systems such as 3G and in wireless LAN such as 802.11, and will extend into satellite communication. Network mobility is enabled by Mobile IP, which provides a scalable, transparent, and secure solution. Mobile IP enables advanced applications such as unified messaging. Though mobility may be enabled by link-layer technologies, data crossing networks or different link layers is still a problem. The solution to this problem is a standards-based protocol, Mobile IP.

Regards,

Karthik.