This paper studies a Bad Apple phenomenon caused by Head-of-Line blocking in IEEE 802.11 networks. This problem can adversely affect the performance of wireless multimedia streaming. We summarize the characteristics of the Bad Apple problem, and then propose a Station-Based Adaptation (SBA) algorithm to solve it. SBA maintains perstation information, operating at the MAC layer as an extension to 802.11 DCF. SBA deactivates flows destined to temporarily unreachable stations, and later reactivates flow transmission when the stations are available. Simulation results show that SBA can effectively improve the performance and robustness of the 802.11 system when stations experience unpredictable temporary failures that are several seconds in duration.
Jean Cao, Yujing Wu, Carey L. Williamson