Joint delay and energy model for IEEE 802.11 networks

Popularity of IEEE 802.11 networks has increased dramatically over the past number of years. Nowadays audio/video conferencing, gaming and other quality of service (QoS) sensitive services are being delivered to the end users over wireless. Commonly probability for a packet to overstay a specific timeout serves as a QoS metric, and obtaining media access control layer packet delay distribution is highly important for this QoS prediction. Usually wireless devices are equipped with energy supplies of limited capacity, and accurate estimation of their energy expenditure is essential from the network design point of view. Meanwhile, as packets of longer delay normally have higher energy transmission cost, there is a certain dependency between the two metrics. This paper considers internal structure of the metrics and proposes a mathematical model that allows obtaining their individual distributions together with the joint distribution. The model presents a random sum, where the summand formation is determined by a Terminating Markov Process. The model has been validated through comparison with results of NS3 simulation.