Providing Time Based Fairness in Multi Rate Ad Hoc Network

Generally, there appears to be a direct relationship between the data rate and the throughput in single rate network. However, under multi rate networks, the long term throughput of each station becomes largely independent of its own data rate, rather, it gets bounded by the lowest data rate peer. The presence of a low data rate link in particular brings down the aggregate throughput, thereby restricting the benefits of higher data rates used by the peers. In this paper we propose a simple and efficient mechanism by which the stations employing higher data rates receive greater transmission opportunities, thereby increasing the aggregate throughput. The calculations are based on the baseline property, which guarantees airtime fairness in the network if all competing stations meet their target throughput. Every station attempts to meet its respective target throughput by dynamically adjusting its minimum contention window CWmin and, hence, controlling its transmission opportunities.