In this paper, the average packet delay on IEEE 802.11 DCF under finite load traffic in multi-hop ad hoc networks is analyzed. We employ a Markov chain model to analyze the probability of transmission at each node in an arbitrary slot and derive the channel access delay. We model each node using an M/G/1 queue and derive the queueing delay. The model is extended from analyzing the single-hop average packet delay to evaluating the end-to-end packet delay in multi-hop ad hoc networks without assuming the traffic to be in a saturation state. To validate our analytic results, we have done extensive simulation. The analytic and the simulation results match very well.
Providing quality of service （QoS） guarantees for multimedia applications over Hybrid networks by wired and wireless LANs is rapidly becoming an important issue. In order to protect the high priority traffic flows and improve network performance in a heavy-loaded network, a new dynamic admission control algorithm is proposed in this paper. We firstly propose a method to fit the fractional autoregressive integrated moving average （FARIMA） models to four actual wireless traffic traces and a traffic prediction based on the upper probability limit. Our experiments show that the one-step forecasts based on the FARIMA models are better than those based on autoregressive integrated moving average （ARIMA） models. We also propose a prediction-based admission control algorithm in hybrid QoS networks with WiFi access using the FARIMA models. The comprehensive simulation experiments are performed to verify the effectiveness of the proposed admission control algorithm.
