Abstract：An enhanced DCF scheme, called U-DCF, based on logarithm utility function is proposed in this paper, since bandwidth resource can not be utilized efficiently in the chosen backoff parameters of 802.11 DCF. The user’s utility is a function of his data throughput, thus the bandwidth resource utilization problem is modeled as a utility based constrained maximization problem, called a system problem. A user problem formulation of the system problem is derived by using Lagrange relaxation and duality theory, thus the competing stations only need to choose their optimal channel access strategies (CWmin) independently to maximize their net utility. Then the maximum aggregate utilities can be achieved in a distributed way. Simulation results show that, by adjusting the backoff parameter CWmin to the average frame-length and the number of the competing stations on the channel, U-DCF outperforms the original DCF in terms of system throughputs, delay bound and frame-loss-rate.
2008, Vol. 30 
