TCP AND SATELLITE NETWORK

TCP Enhancement for Satellite Network

TCP Enhancement for Satellite Network

Introduction

Since the advent of internet, the most important concern for the experts has been to find and invent various techniques or protocols that will ensure data or information transfer that is both speedy and reliable. Therefore, the Internet Protocols introduced played a central role in data or information transfer on the internet. IP, however, consist of a set of protocols known as IP suite that are used to relay datagram over the global network. The most efficient and widely used amongst the protocols introduced by the IP suite is the TCP. A few disadvantages may be attached with the protocol, however its benefits and over all range of applications overshadows them (Reynders, 2003, pp.7).

Discussion

Commonly, known as Transmission Control Protocol, these are widely used because of their reliable data transfer. The benefits they offer also made possible the use of TCP protocols in the terrestrial links. However, many individuals thought that utility of these protocols should be optimized by applying them in other fields. The growth and development in the field of satellite communication particularly interested the experts.

Background

Because of the reliable and efficient data transfer, TCP turned out be a very effective implementation in the fields of satellite communication. However, there are also some limitations and constraints introduced in the satellite links. These constraints were turning out to be major concerns as new satellite systems were introduced with higher efficiency and much higher data transmission rate.

Various Satellite Link Characteristics and Their Effect on TCP Operation

Various characteristics of TCP as a protocol introduced in the satellites were affecting their performance. However, there were several satellite characteristics that were altering the performance of TCP. Some of these characteristics include

Delay in GEO

Majority of the satellites systems used for commercial goals work in Geosynchronous Equatorial Orbit (GEO). Out in space, a GEO satellite is placed approximately 35,800 Kilometres above the equator. The satellite, at this distance, takes a total duration of 24 hours to compete one rotation around the planet. Therefore, the earth and the satellite revolve together as a result of the fact that the Earth also takes 24 hours to execute one complete rotation on its axis. Hence, in a geosynchronous equatorial orbit, a satellite is always and the earth is always positioned on the same spot.

Compared with the queuing delay and transmission delay, propagation delay is the dominant part. That is because the distance between earth station and GEO satellite is very long. The propagation delay will usually reach up to 280md (in a Uni-directional transmission) of fixed delay, if GEO links are utilized for the transmission of messages between two earth stations. Moreover, if an Acknowledgement message (ACK) is also returned on the same satellite channel or link, then Round Trip Time (RTT) will be double the Propagation Delay that is approximately 560ms. Therefore, the delay will be greater than the average transmission delay which will ultimately result in larger bandwidth product and larger round ...