This paper analyses the energy efficiency and QoS performance of 802.11e as a connectivity solution for low-rate applications, such as wireless automation and monitoring. The authors consider non-interference and co-existence scenarios and show through modeling and simulations that the power save operation mode and the EDCA QoS mechanisms in the 802.11e standard can be exploited to achieve the power consumption requirements of low-rate applications. The authors also provide a comparison of the energy efficiency between 802.11e and 802.15.4 under varying interference and traffic conditions. Our results suggest that in some specific scenarios, 802.11e can achieve higher energy efficiency and QoS than 802.15.4.

In this paper, we demonstrate the energy-efficient point coordination function (PCF) operation of IEEE 802.11a wireless LAN (WLAN) via both transmit power control (TPC) and physical layer (PHY) rate adaptation. First, we derive the energy-consumption performance analytically for uplink data transmissions under the PCF. From the evaluation results, we observe that significant energy savings can be achieved by combining TPC with adaptive PHY rate selection. A key requirement for a transmitter to select the most energy-efficient combination of transmit power level and PHY rate is the knowledge of the path loss between the receiver and itself. We present a novel scheme for accurate path loss estimation in 802.11 WLAN. Results and conclusions presented in this paper can serve as a valuable guidance or reference for the design of future 5 GHz 802.11 WLAN systems.