Link characteristics estimation for IEEE 802.11 DCF based WLAN

Knowledge of network path characteristics enables upper layers to improve performance through adaptation protocols which adjust behaviors according to current network path characteristics. For a mobile node of a wireless network, this knowledge is especially valuable because the characteristics of the wireless link, which often dominate network path characteristics, change frequently and abruptly due to mobility, fading, and contention among nodes. Due to the dynamics and precious bandwidth of the wireless link, the commonly used probing packet methods are not appropriate for estimating the characteristics of a network path with a wireless link. We propose a new mechanism to estimate link characteristics of IEEE 802.11 DCF (distributed coordination function) based wireless LAN (WLAN), one of the most popular wireless access networks. Instead of sending probing-packets, a mobile node estimates its link characteristics based on wireless link quality and the contention status of the whole WLAN. We implement this mechanism and test its accuracy in NS2.