Dynamic Transmit-Power Control for WiFi Access Points Based on Wireless Link Occupancy

Dynamic transmit-power control (DTPC) is critical to improve spectral efficiency and reduce interference in wireless local area networks (WLANs). DTPC schemes typically use signal-to-noise-ratio (SNR) information and require exchange of information between transmitters and receivers. However, that is not always easy to implement in actual WLAN deployments. In this paper, we present a simple but novel DTPC scheme for 802.11n Access Points (AP). The method, which is run by each AP without exchanging signaling information with other APs and associated Stations (STA), seeks for transmitting with the minimum power provided that the link is not overloaded. In lieu of using the SNR at the receiver side, the power is adapted based on the wireless link occupancy (rate load). As a result, no signaling exchange between stations and the AP is required. Reducing the transmit-power reduces both co-channel and adjacent channel interference and, hence, entails benefits for all nearby WLANs. The DTPC scheme was tested in a simulator and implemented in an actual 802.11n deployment, which confirmed the theoretical benefits.