Topological Persistence for Medium Access Control

The primary function of the medium access control (MAC) protocol is managing access to the shared communication channel. From the viewpoint of the transmitters, the MAC protocol determines each transmitter´s channel occupancy, the fraction of time that it spends transmitting over the channel. In this paper, we define a set of topological persistences that conform to both network topology and traffic load. We employ these persistences as target occupancies for the MAC layer protocol. A centralized algorithm is developed for calculating topological persistences and its correctness is established. A distributed algorithm and implementation are developed that can operate within scheduled and contention-based MAC protocols. In the distributed algorithm, network resources are allocated through auctions at each receiver in which transmitters participate as bidders to converge on the topological allocation. Very low overhead is achieved by piggybacking auction and bidder communication on existing data packets. The practicality of the distributed algorithm is demonstrated in a wireless network via simulation using the ns-2 network simulator. Simulation results show fast convergence to the topological solution and, once operating with topological persistences, improved performance compared to IEEE 802.11 in delay, throughput, and drop rate.