  In this paper, we consider the problem of modelling the average delay
experienced by a packet in a single cell IEEE 802.11 DCF wireless local area
network. The packet arrival process at each node i is assumed to be Poisson
with rate parameter \lambda_i. Since the nodes are sharing a single channel,
they have to contend with one another for a successful transmission. The mean
delay for a packet has been approximated by modelling the system as a 1-limited
Random Polling system with zero switchover time. We show that even for
non-homogeneous packet arrival processes, the mean delay of packets across the
queues are same and depends on the system utilization factor and the aggregate
throughput of the MAC. Extensive simulations are conducted to verify the
analytical results.
