Upstream/downstream unfairness issue of TCP over wireless LANs with per-flow queueing

Fairness is an important issue in wireless LAN due to their shared media nature. Essentially, IEEE 802.11 MAC protocols have been designed to provide fair access for all the competing mobile hosts. However, the fairness at MAC layer can not be maintained at TCP layer in the presence of both mobile senders and receivers accessing to the wired networks. In this paper we investigate the TCP upstream/downstream unfairness issue over the 802.11 wireless LAN with per-flow queueing employed at the access point. The interactions between 802.11 MAC protocol and TCP are evaluated through analysis and simulation. Based on the derived analytical model, an efficient solution is proposed to be implemented at the access point for fairness achievement.