ABSTRACT

Internet as a data network has seen explosive growth during recent years. Users expect to be connected to the Internet from anywhere at anytime. So the Low Earth Orbiting (LEO) satellite networks is researching to provide ubiquitous IP connectivity in the world and also in space while guaranteeing short propagation delays. (Carlos Bernardos, Ignacio Soto 2007) Since IP/LEO satellite networks make Internet accesses becoming more and more ubiquitous, demands for mobility are not restricted to single terminals anymore. For example, a person owns more than one mobile device (such as a mobile phone, a laptop, and a personal digital assistant) and each of these devices has multiple network interfaces to connect with each other as well as other networks. When moving together with the owner, the devices constitute a small mobile network. Large scale mobile networks such as aircrafts with mobile devices or airplanes with passengers are more common in IP/LEO satellite networks. [2-4]

Mobile IPv4 (MIPv4) and Mobile IPv6 (MIPv6) have been developed for supporting continuous connections to mobile hosts. While these traditional protocols showed limitations in solving the issue of mobile networks. [5] Each of the mobile devices should be sophisticated enough to run such mobility support protocols, and must be able to attach to the access technology available to connect to the Internet. And the signaling exchanged is limited to a single node sending only one message to avoid signaling

overload every time the network moves. [6] Realizing these deficiencies, the Network Mobility (NEMO) Basic Support Protocol is proposed to support network mobility at the IPv6 layer by the IETF NEMO Working Group. [7-8]

2 STRUCTURE DESIGN OF NEMO BASED IP/LEO SATELLITE NETWORK

The limitations of both MIPv4 and MIPv6 protocols in the supporting mobile network provide opportunities for the proposal of NEMO protocol and also the further researches. The combination of NEMO protocol and IP/LEO satellite network improves the utilization rate of satellite channel resource and it also provides a direct connection to the Internet for the devices and platforms without satellite access capabilities.