Problems with Providing QoS in EDCA Ad-Hoc Networks with Hidden and Exposed Nodes

In this paper we investigate the problem of providing QoS within IEEE 802.11 EDCA ad-hoc networks. Our study shows that a strong unfairness in medium access between certain nodes may appear. It also shows that the possible unfairness is dependent on the actual placement of nodes. Furthermore, the inability of the four-way handshake mechanism to improve the performance of the analyzed networks is also mentioned. Finally, in the paper we indicate the need of proposing both a new MAC layer protocol and a valid EDCA analytical model including hidden nodes.