A Practical Fairness Control Model in Wireless Sensor Networks

Fairness is an important problem in congestion control, which is to ensure that all data sources have equal access to end-to-end network bandwidth. In wireless sensor network, nodes are always deployed randomly and redundantly, the effective amount of sensed information of different sensors may be different. In order to fit the characteristic of wireless sensor networks, the Ttraditional fairness definition is extended and a practical fairness control model CFRC is proposed. CFRC does not need knowledge of source distribution at prior, nor make restrictive assumptions on the routing structure, nor maintain any state information, instead, CFRC guarantees the fairness dynamically. In CFRC, a low-cost credit computation algorithm is proposed for each source node to compute its credit locally based on the sensed area of itself and its neighbors; Aggregation node computes the credit of aggregated packets using simple sum operation. Furthermore, an interferer aware fair rate allocation method is proposed in CFRC to allocate bandwidth among not only all upstream neighbors, but also congested node and its interferers based on the average credit. Simulation results show that CFRC can achieve fairness based on the credit of data sources, reduce the number of dropped packets and downgrade the reliability fairly and gracefully when congestion happens.