Research Of Energy-saving Power Control Mechanism For Wireless LAN

The energy-saving problem of the ICT(Information and Communication Technologies) sector has become an important subject for both industry and academics. As one of the main source of energy consumption of ICT sector, the energy-saving issue of WLAN(Wireless Local Area Networks) draws more attention. With the popularization of mobile phone and tablet devices, the amount of data traffic has increased sharply. As a result, large numbers of APs(Access point) has been deployed, bringing observable electrical energy consumption. Since IEEE 802.11 n has become the mainstream protocol of WLAN, the research of energy-saving technology of WLAN, especially for the IEEE 802.11 n protocol based devices, can bring practical cost reduction for network operators, and positive effect of energy-saving footprint of ICT sector. To this end, we focus on the energy-saving mechanism of WLAN from the network operators’ point of view, aiming at the wide deployed APs to decrease the energy consumption and promote the energy efficiency for WLAN and the wireless access network.In this paper, we first set up the energy consumption evaluation criteria of WLAN devices, and then theoretically analyze the calculation of the criteria. On account of this, we introduce the A-TPCM mechanism to reduce the power consumption and improve the energy efficiency of 802.11 n WLAN devices. The key idea of A-TPCM is to adjust transmission power adaptively based on channel estimation. Thus it allows WLAN devices to use a much lower power level in transmit mode and tunes the transmission power adaptively under different channel conditions. The main procedure of the mechanism includes the channel estimation, the generation of adjusting decision and the execution of the decision. Particularly, the A-TPCM introduces the subframe error rate for the statistic of Block ACK frames to estimate the channel. Thus the algorithm needs no modification to the existing protocol, and is easy to deploy. Besides, the A-TPCM also has the advantages in deploying at both AP and UE sides, and being backward compatible with the IEEE 802.11a/b/g standards with little modifications. We evaluate the performance of the A-TPCM by OPNET and the results show that the A-TPCM can decrease energy consumption of 802.11 n WLAN devices in different conditions.