A Fairness-Aware topology independent TDMA MAC policy in time constrained wireless ad hoc networks

摘要

As current network technologies evolve towards 5G supporting increased throughput and low time delays, a need emerges for supporting time constraint applications at the wireless end user level. The network formed due to the dynamicity of the Internet of Things (IoT), can be seen as a wireless ad hoc environment where certain time constraints need to be satisfied motivating the revisit of topology independent TDMA policies in this work. It has been shown that such policies, even though suitable to satisfy certain time constraints, suffer either from low throughput or from fairness issues. In this paper a new fairness-aware policy for medium access control in wireless ad hoc networks is proposed that exploits the topology independent properties of the existing policies in the literature and in addition, it takes into account fairness by accessing the medium according to the individual envy metric that is easily calculated by each node. In particular, under the proposed policy, nodes that are treated "unfairly" increase their medium access opportunities in subsequent frames and vice versa. The proposed policy is evaluated against the existing topology independent policies demonstrating its effectiveness of throughput increment while at the same time nodes are treated "fairly"(given certain fairness metrics). It is shown here that the best case regarding throughput corresponds to the policy of the worst case regarding fairness while those policies that treat nodes "fairly", result in small throughput. Under the proposed policy, fairness remains close to the best fairness case but at the same time throughput is improved compared to the same case. Furthermore, it is also shown here that individual nodes that are treated "unfairly" tend to experience a larger number of consecutive re-transmissions and consequently time delays, thus emphasizing the need to consider fairness in these emerging environments.