OPSM - Opportunistic Power Save Mode for Infrastructure IEEE 802.11 WLAN

Abstract

We focus on the energy spent in radio communication by the stations (STAs) in an IEEE 802.11 infrastructure WLAN. All the STAs are engaged in web browsing, which is characterized by a short file downloads over TCP, with short duration of inactivity or think time in between two file downloads. Under this traffic, Static PSM (SPSM) performs better than CAM, since the STAs in SPSM can switch to low power state (sleep) during think times while in CAM they have to be in the active state all the time. In spite of this gain, performance of SPSM degrades due to congestion, as the number of STAs associated with the access point (AP) increases. To address this problem, we propose an algorithm, which we call opportunistic PSM (OPSM). We show through simulations that OPSM performs better than SPSM under the aforementioned TCP traffic. The performance gain achieved by OPSM over SPSM increases as the mean file size requested by the STAs or the number of STAs associated with the AP increases. We implemented OPSM in NS-2.33, and to compare the performance of OPSM and SPSM, we evaluate the number of file downloads that can be completed with a given battery capacity and the average time taken to download a file.

Power management in IEEE 802.11 WLAN using proxy-assisted WLAN controller

“…The AP generates beacons for each of the clients accordingly, thus saving power. In Opportunistic PSM (OPSM) [10], by introducing an additional bit in beacon, only one STA is allowed to download at any time. The Station gets maximum throughput and this results in minimising the energy used as the channel contention is eliminated.…”

ZigBee-Assisted Power Saving Management for Mobile Devices

“…For example, authors in [1], [15] proposed to minimize the energy consumption with bounded slowdown. To reduce the congestion at the AP and thus improve the performance of the standard PSM, an opportunistic PSM is proposed in [16] to allow one download at any time. One common shortcoming of these schemes lies in that, their savings largely depend on the accuracy in predicting client network usage patterns, because they are not able to wake up asleep clients at will without the assistance of additional interfaces.…”

Energy Efficient Rate Adaptation Algorithm for FiWi Access Network

“…In case of OPSM the STA wait to be active for optimal time that require least energy consumption. This optimal time is considered as the time when AP is not serving any other STA [9]. In case of mobility aware PSM the mobility of user of traffic pattern is considered to create more sleep opportunity for a STA.…”