Research Of VoIP In IEEE 802.11 Wlan

IEEE 802.11 is the protocol standards of wireless local area network(WLAN). Applications of WLAN based on 802.11 has gone into people's life,they are widely used from personal communication, food service, indoor or outdoor meeting to military fields. Voice over WLAN is a typical application of IEEE 802.11,it can be deployed rapidly in any flexible easy wiring area, so it's widly used in the place such as Marketing MVP, offices and conncil house.IEEE 802.11e provide the mechanism to distinguish the priority for different service flow, compared to other services it improves the priority of real-time services such as VoIP in WLAN, so that its QoS requirement will be satisfied to some extent, because of not providing the different priority between move host (MH) and access point (AP) in WLAN, the unbalance between uplink and downlink service flow on AP was induced, and then lead to bottleneck, further more restrict the VoIP capacity. To solve this problem, a new strategy based on the analysis of the capacity of VoIP in WLAN was proposed in this paper to improve the switch in capacity of AP's channel. We use the length of AP's queue to estimate whether the network is congested or not. And then modify the arbitration inter-frame space (AIFS) of the service flows dynamically, we modulate the priority of AP dynamically according to web congestion condition, to weaken the restriction of VoIP capacity caused by bottleneck of AP. The result of simulation shows that, the proposed scheme can increase VoIP capacity efficiently.WiFi is another typical application of standards IEEE 802.11. The WiFi mobile phone of underground mine rescue system is composed of Samsung's processor S3C2440 as the core, and Marvell's 88w8686 as WiFi module.The design is to realize its voice call function mainly.