A study of fairness issues in the assignment of bandwidth to elephant TCP connections sharing a rain-faded GEO satellite channel

The goodput of long-lived TCP connections can be maximized in error-prone channels by trading bandwidth for Bit Error Rate (BER). This fact can be exploited in the bandwidth and transmission parameters' assignment, by means of Adaptive Coding and Modulation (ACM), in satellite systems; in such a case, multiple source-destination (SD) pairs actually 'see' channels with diverse characteristics, owing to unequal weather conditions. However, when dealing with multiple SD assignments, both aspects of goodput-maximization and fairness must be dealt with. Improving the effectiveness of TCP may be relatively easy, but maintaining the effectiveness while maintaining the fairness is a challenge. The paper compares alternative solutions, by taking into account different approaches.