Aiming at the problem that the contention window of enhanced distributed channel access（ EDCA）mechanism changes too steeply in high-load network

leading to a significant performance degradation of network

an adaptive backoff algorithm is proposed. On the basis of GDCF algorithm

the current network congestion status is measured by the mean value of the maximum backoff phase of the data packet

thus dynamically adjust the reset method of contention window. Such approach can reduce network collisions and improve network performance. The algorithm has less extra cost and is easy to be implemented

the simulation in NS—2 shows that the improved algorithm can significantly improve the performance of the EDCA mechanism in high-load network

reduce the delay of high-priority service

and improve the throughput of each priority service.