Low-complexity analytical model for cross-layer expired time video packet drop protection in WLANs

We propose exploiting of the M/M/1 Model for solving a cross-layer optimisation problem in video live transmission over IEEE 802.11 wireless local area networks (WLANs). We investigate the packet loss behaviour in the IEEE 802.11 WLANs under various retry limit settings, with emphasis on packet overflow drop rate, expired-time packet discard rate -both in the MAC layer- and packet link loss rate in the physical layer. We will show that there is interaction between packet overflow drop and expired time packet discard in the queue. By introducing the virtual queue length concept, we will show that the expired-time mechanism can be modelled by packet overflow drop process. Subsequently we will prove that packet overflow drop can be avoided by obtaining the optimal queue length. Then we derive the optimum retry-limit in order to minimise the total packet loss rate. Network Simulator-2 (NS-2) is exploited to verify the accuracy of model.