Research On Control Of Capacity And Energy Of VoIP Over Wlan

The continuous integration of wireless communication technology and computer network technology is the main feature of information technology development nowadays. This paper makes a description of wireless LAN technology and VoIP technology. Then we studies the combination of them,VoIP over WLAN (VoWLAN) technology. This paper studies two aspects of capacity and energy of VoWLAN technology in-depth, from the study, the number of VoIP calls WLAN can support is far fewer than the theoretical number WLAN bandwidth can support. When mobile terminals are used, the usage of WLAN interface costs large energy consumption, continuous talk time will be greatly reduced. Capacity and power consumption are two main bottlenecks in the wide deployment of Voice-over-IP(VoIP) over IEEE 802.11 wireless LAN. In this paper, we analyze the capacity of VoIP traffic in 802.11 WLAN and do the relevant simulations without sleep strategy. We implement MAC sleep control mechanism in NS2 platform independently, do the simulation with sleep strategy and analyze its capacity and energy saving performance. We find that capacity decreases when the network adopts sleep strategy. After a thorough analysis on VoIP over 802.11 WLANs by p-persistent model of the IEEE 802.11 protocol, we confirm our simulation results. Then we consider the important network parameter, average collision probability, which reflects the condition of network congestion, and use it controlling sleep strategy. We provide a dynamic sleep strategy, namely Collision Detective Dynamic Sleep Strategy(CDDSS) to improve both the capacity and energy saving rate of the VoWLAN. In our CDDSS, Mobile Station(MS) adjusts sleep interval and packetization interval adaptively according to the average collision probability pc of the network. Our simulation results show that CDDSS can not only improve the capacity of VoIP in 802.11 WLANs, but also save more energy, solve the capacity and energy bottlenecks of WLAN-based VoIP applications to a certain extent.