Fuzzy open-loop Transmission power control for wireless local area networks

Transmission power control is an effective way to save energy in wireless devices on wireless local area networks (WLANs). In WLANs nodes can transmit only when a communication channel is unoccupied. The transmission bursts intervals for nodes vary mainly according to the type of media access control and the number of nodes competing or reserving the channel time. Due to varying burst intervals, there is not a continuous transmission channel between the node and the access point. Therefore, delivery of real-time feedback information from the access point to the transmitting node for, e.g., closed loop power control, is meaningless. In WLANs the nodes around the access point transmit with a high value fixed power in order to guarantee as error-free transmission as possible. However, this approach is quite energy inefficient and causes unnecessary interference to adjacent access points and associated nodes. This paper considers energy-efficient Distributed Coordination Function (DCF) operation of IEEE 802.11 WLANs via an open-loop power control algorithm based on the fuzzy set theory. The main idea is to minimize transmission power of the nodes, while keeping the transmission errors at an acceptable level. The functionality of the proposed solution is evaluated via simulations. (12 refs.)