Survivability and Scalability of Space Networks

Network survivability, which reflects the ability of a network to continue to function during and after natural or man-made disturbances, is a crucial aspect for any kind communication. It goes beyond security and fault tolerance to focus on delivery of essential services and rapid recovery of full services when situation improves. Wireless and space networks have the challenge of survivability, since users and network entities are mobile and the communication channels are accessible to anyone. Network scalability reflects the ability of a network to support increased amount of load. Future Low Earth Orbiting spacecrafts will contain several IP-enabled devices, such as Earth observing equipment, that will be accessible by terrestrial users through the Internet. Satellites are being used to capture real-time images, video for various purposes, such as, observing the Earth, weather data, live images for tornado, cyclones, tsunami, etc. In future, these data will be accessed by terrestrial users through the Internet. As number of Internet users are growing very rapidly, such satellite services will have a significantly large number of client requests which will overload the bandwidth-limited satellite links. Therefore, the survivability and scalability of space networks may become a major issue and this should be addressed in order to provide seamless services to ongoing communication to all users irrespective of mobile or stationary. However, most of network survivability and scalability analysis are based on terrestrial networks. We have listed various approaches used in those analysis. This paper clearly indicates the issues regarding survivability and scalability of space networks that need to be addressed.