Fairness is an essential problem in congestion control, which is to ensure all data sources have equal or weighted access to end-to-end network bandwidth. In this paper, we propose a practical fairness model CFRC to allocate congested bandwidth based on the credit of each sensor source instead of uniformly. Credit represents the effective amount of sensed information of packet generated in sensor source. In CFRC, a low-cost credit computation method ACCA is proposed for each source node to compute its credit locally based on the sensed area of it and its neighbors; Aggregation node computes the credit of aggregated packets using simple sum operation. Furthermore, an interferer aware fair rate allocation algorithm IFRA is proposed in CFRC to allocated bandwidth not only among all upstream neighbors, but also among congested nodes and its interferers. Simulation results verify the performance of CFRC.