An energy-efficient point coordination function using bidirectional transmissions of fixed duration for infrastructure IEEE 802.11 WLANs

Abstract

Abstract-The Point Coordination Function (PCF) of the IEEE 802.11 standard represents a well-known Medium Access Control (MAC) protocol providing Quality-of Service guarantees in Wireless Local Area Networks (WLANs). However, with the currently employed polling mechanism WLANs consume a significant amount of the energy resources from batterypowered user devices. To provide energy saving, an improved MAC protocol is presented in this paper, where bidirectional transmissions of fixed duration are incorporated into PCF in order to enable dynamic scheduling of real-time traffic. Based on this new strategy, wireless access points (APs) can estimate the proper duration of the Contention Free Period (CFP), in order to allow mobile stations to acknowledge any received data packet with a data packet equal to the received packet in size. Having this information, a mobile station, following the data exchange with the AP, can determine its wake-up timer and activate the sleep mode for the rest of the CFP interval. Comprehensive computerbased simulations demonstrate the feasibility of the proposed MAC improvements to achieve energy efficiency with negligible impact on packet delivery delay.

Optimal Access Point Power Management for Green IEEE 802.11 Networks

“…As already mentioned in the Introduction, despite the abundant literature on energy efficiency in wireless LANs [ 7 , 8 , 9 , 10 , 26 ], very few works exist that deal with a problem similar to the one faced here.…”

“…For example, there is a plethora of works dealing with analysing and reducing the power consumption in cellular networks [ 1 , 2 ], in wireless sensor networks [ 3 , 4 ], in wireless mesh networks [ 5 , 6 ], and in Wireless Local Area Networks (WLANs). With specific focus on IEEE 802.11-based networks, numerous researchers have dealt with improving the energy efficiency acting on the various medium access control and physical layer mechanisms [ 7 , 8 ] or on network-wide algorithms, such as dynamic channel selection [ 9 ] and coordination functions [ 10 ]. Recent works have focused on resource allocation in Terahertz communications [ 11 , 12 ].…”

Analysis of an energy-efficient MAC protocol based on polling for IEEE 802.11 WLANs

“…In its turn, GreenPoll [6] differs from the proposed schemes in [8]- [10] in the fact that STAs enable sleeping processes based only on the virtual carrier sense information attached to the transmitted beacon, control, and data packets. Therefore, GreenPoll can avoid explicit scheduling information attached to the beacons and overcome scalability limitations.…”

“…In contrast, the PCF concatenates multiple bidirectional TXOPs between the AP and the STAs, thus facilitating the execution of the TXOP PSM. Motivated by this, we presented in [6] the Green Polling MAC Protocol (GreenPoll) as a new access mechanism that combines the TXOP PSM for power saving and the PCF with reservation and implicit polling. GreenPoll achieves low overhead and overcomes scalability limitations compared to beacon-based PS mechanisms.…”

“…Results presented in [6] were only based on computer-based simulations. In this paper, we extend that work by theoretically analyzing the maximum achievable energy efficiency of GreenPoll taking into account the influence of the on/off radio transitions.…”