MINIMIZING THE TIME DELAY IN GEO SATELLITE SYSTEM TCP MECHANISM FOR ENHANCED THROUGHPUT USING H- INFINITY TECHNIQUE

*Isioto, Nte N.¹, Nwabueze, Christopher. A², Akaneme S. A ³, Dickson Rachael⁴

ABSTRACT

This research work focuses on minimizing the cumulative time delay in the mechanism of geostationary earth orbit (GEO) satellite system Transport Control Protocol (TCP) in a bid to enhancing the system throughput using h-infinity synthesis technique. The satellite system has become the solution-bridge to the problem of long range communication medium and achieving global ubiquitous network coverage cheaply. TCP over satellite is a critical structure in the communication network; but due to the long propagation satellite channel path and the increasing reliance on the wireless network especially the internet, the protocol has witnessed increased traffic congestion and severe delays which can snowball into data queue and more delays if not checked.  Also, TCP over satellite is a slow protocol due to its mechanisms of flow control and congestion avoidance, geared toward reliable service delivery.  Hence, the high latency or time delays in satellite channels. The delay from the long propagation path alone, accounts for more than 70% of the system delay. If the system time delay is not minimized, the system performance is affected adversely. To minimize these delays and improve the performance of the TCP over satellite communication system a robust control method is needed which can consider the high level of disturbances in the design by improving the settling time, the tracking error and the stability margins of the system. H-infinity synthesis technique is an advanced and robust feedback control technique which uses weights to achieve robust controller characteristics through loop-shaping. In this work, the H-infinity synthesis technique was applied to improve the throughput of TCP over satellite system by minimizing the time delays. The computation and simulation were carried out in MATLAB application software. From the results, the existing TCP over satellite system recorded a very high settling time of 356 seconds which indicates that the system has slow speed. However, H-infinity controlled TCP over satellite model recorded a very low settling time of 0.0394 seconds which indicates 99.99% improvement of the system. These results indicate high speed response to disturbance. Therefore, H-infinity controlled TCP over satellite system achieved low latency, enhanced TCP throughput and overall system performance.

Keywords: Satellite communication, time delay, TCP performance, robust control, enhanced throughput, round trip time, low latency, system performance