scholarly journals Improving Energy Efficiency in Idle Listening of IEEE 802.11 WLANs

2016 ◽  
Vol 2016 ◽  
pp. 1-15 ◽  
Author(s):  
Muhammad Adnan ◽  
Eun-Chan Park
Keyword(s):  
Energy Efficiency ◽  
Ieee 802.11 ◽  
Power Saving ◽  
Local Area ◽  
Contention Window ◽  
Channel Access ◽  
Analysis Model ◽  
Frame Aggregation ◽  
Improve Energy Efficiency ◽  
Idle Listening

This paper aims to improve energy efficiency of IEEE 802.11 wireless local area networks (WLANs) by effectively dealing with idle listening (IL), which is required for channel sensing and is unavoidable in a contention-based channel access mechanism. Firstly, we show that IL is a dominant source of energy drain in WLANs and it cannot be effectively alleviated by the power saving mechanism proposed in the IEEE 802.11 standard. To solve this problem, we propose an energy-efficient mechanism that combines three schemes in a systematic way: downclocking, frame aggregation, and contention window adjustment. The downclocking scheme lets a station remain in a semisleep state when overhearing frames destined to neighbor stations, whereby the station consumes the minimal energy without impairing channel access capability. As well as decreasing the channel access overhead, the frame aggregation scheme prolongs the period of semisleep time. Moreover, by controlling the size of contention window based on the number of stations, the proposed mechanism decreases unnecessary IL time due to collision and retransmission. By deriving an analysis model and performing extensive simulations, we confirm that the proposed mechanism significantly improves the energy efficiency and throughput, by up to 2.8 and 1.8 times, respectively, compared to the conventional power saving mechanisms.

Adaptive Traffic-Aware PSM Mechanism for IEEE 802.11 WLANs

2014 ◽  
Vol 23 (4) ◽  
pp. 437-450 ◽  
Author(s):  
Yi Xie ◽  
Xilong Sun ◽  
Pengfei Yuan ◽  
Xijian Chen
Keyword(s):  
Energy Efficiency ◽  
Ieee 802.11 ◽  
Network Traffic ◽  
Access Point ◽  
Local Area ◽  
Limited Range ◽  
Traffic Load ◽  
Wireless Devices ◽  
Current Channel ◽  
Improve Energy Efficiency

AbstractWireless devices consume large amounts of energy during wireless communication. As the energy storage of battery is limited, improving energy efficiency has become an important approach to prolong the lifetime of devices. The IEEE 802.11 protocol supports the power save mode (PSM) in wireless local area networks (WLANs). However, the standard PSM cannot adapt to the changes of traffic load or channel conditions. Therefore, this article proposes an adaptive traffic-aware PSM mechanism (APSM) that improves energy efficiency of wireless devices in a WLAN with an access point (AP). According to the current channel condition and traffic load, the AP adjusts the interval of beacons that give devices different priorities to fetch buffered packets. The devices can adaptively adjust listening intervals according to network traffic, and adopt different congestion backoff timers when channel collisions happen or the network topology changes. The APSM has been implemented and evaluated in NS-2. The simulation results have shown that devices using the APSM can improve energy efficiency by 115% at most compared with the ones using the standard PSM. The benefit of adaptive beacon interval and listening intervals is significant, while the improvement due to the adaptive backoff timer is minor. The improvement of the APSM over the PSM is more significant when the network traffic level decreases and the ratio of idle power to sleeping power increases. Additionally, the APSM increases the delay of data frames within a limited range, which does not bring any bad effect on network throughput.

scholarly journals Hybrid Control of Contention Window and Frame Aggregation for Performance Enhancement in Multirate WLANs

2015 ◽  
Vol 2015 ◽  
pp. 1-16 ◽  
Author(s):  
Muhammad Adnan ◽  
Eun-Chan Park
Keyword(s):  
Performance Enhancement ◽  
Hybrid Control ◽  
Transmission Rate ◽  
Local Area ◽  
Contention Window ◽  
Channel Access ◽  
Distributed Coordination ◽  
Frame Aggregation ◽  
Transmission Rates ◽  
Coordination Function

The IEEE 802.11 standard has been evolved to support multiple transmission rates in wireless local area networks (WLANs) to cope with diverse channel conditions and to increase throughput. However, when stations with different transmission rates coexist, the basic channel access mechanism of WLAN, distributed coordination function (DCF), not only fails to assure airtime fairness among competing stations but also decreases overall network throughput, because DCF was designed to provide fair opportunity of channel access, regardless of transmission rate. As an effective solution to this problem, we propose a hybrid control mechanism that integrates contention window control and frame aggregation. The former adjusts the size of contention window and differentiates the channel access opportunity depending on the transmission rates of stations. The latter controls the number of packets in the aggregated frame to tightly assure per-station airtime fairness with the reduced channel access overheads. Moreover, we derive an analytical model to evaluate the performance of the proposed mechanism in terms of throughput and fairness. Along with the analysis results, the extensive simulation results confirm that the proposed mechanism significantly increases the overall throughput by about three times compared to the conventional DCF, while assuring airtime fairness strictly.

scholarly journals A Joint Strategy for Fair and Efficient Energy Usage in WLANs in the Presence of Capture Effect

Electronics ◽  
2019 ◽  
Vol 8 (4) ◽  
pp. 386
Author(s):  
Bilal Khan ◽  
Rana Rehman ◽  
Byung-Seo Kim
Keyword(s):  
Energy Efficiency ◽  
Power Control ◽  
Access Point ◽  
Local Area ◽  
Contention Window ◽  
Transmission Power ◽  
Capture Effect ◽  
Analysis Model ◽  
Transmission Power Control ◽  
Joint Strategy

Capture effect has been shown as a physical layer (PHY) phenomenon of modern wireless devices that improves the performance of wireless local area networks (WLANs) in terms of throughput. In this paper, however, we explore the effect of PHY capture in the domain of energy efficiency. Analysis model that takes into account the effect of PHY capture is backed up by ns-2 simulations show that capture effect improves energy efficiency of WLAN by 20%. This improvement, however, results in unfairness, i.e, a group of nodes located far away from the Access Point (AP) is three times less energy efficient than the group of nodes located closer to the AP. To resolve the unfairness caused by the capture effect, furthermore, this paper proposes a joint strategy of adaptive transmission power control (ATXPR) and contention window adjustment (CWADJ). Namely, a node that suffers transmission failure due to another node capturing the channel steps up its transmission power according to the transmission power control algorithm and refrains from increasing its contention window according to contention window adjustment mechanism, respectively. Our proposed joint strategy is 99% fair while maintaining overall energy efficiency of the network.

scholarly journals Power Saving Proxies for Web Servers

2019 ◽  
Vol 63 (2) ◽  
pp. 179-192
Author(s):  
Karl J O’Dwyer ◽  
Eoin Creedon ◽  
Mark Purcell ◽  
David Malone
Keyword(s):  
Energy Efficiency ◽  
Power Consumption ◽  
Embedded System ◽  
Power Saving ◽  
Web Servers ◽  
Small Energy ◽  
Significant Percentage ◽  
Improve Energy Efficiency ◽  
Data Centre ◽  
Energy Footprint

Abstract Electricity is a major cost in running a data centre, and servers are responsible for a significant percentage of the power consumption. Given the widespread use of HTTP, both as a service and a component of other services, it is worthwhile reducing the power consumption of web servers. In this paper we consider how reverse proxies, commonly used to improve the performance of web servers, might be used to improve energy efficiency. We suggest that when demand on a server is low, it may be possible to switch off servers. In their absence, an embedded system with a small energy footprint could act as a reverse proxy serving commonly-requested content. When new content is required, the reverse proxy can power on the servers to meet this new load. Our results indicate that even with a modest server, we can get a 25% power saving while maintaining acceptable performance.

Notification of Data Congestion Intimation [NDCI] for IEEE 802.11 Adhoc Network with Power Save Mode

2017 ◽  
Vol 5 (2) ◽  
pp. 317
Author(s):  
Azeem Mohammed Abdul ◽  
Syed Umar
Keyword(s):  
Ieee 802.11 ◽  
Collision Energy ◽  
Simulation Analysis ◽  
Power Saving ◽  
Analysis Model ◽  
802.11 Dcf ◽  
Adhoc Network ◽  
Transmission Window ◽  
Power Save Mode ◽  
Voice Data

<p>IEEE 802.11-power save mode (PSM) independent basic service set (IBSS) Save, the time is divided into intervals of the signals. At the beginning of each interval signal and power saving alarm periodically all open windows (vocals). The station will be in competition with the rest of the frame window frame sent voice data leakage range. Element depends frame transmission IEEE CSMA / CA as defined in 802.11 DCF. A chance of transmit voice frames type of collision energy IBSS success. This article gives an analysis model with a chance of success output transmission window fixed size element. The results of the simulation analysis of the accuracy of the analysis.</p>

scholarly journals An Energy-Efficient Strategy for Microcontrollers

2021 ◽  
Vol 11 (6) ◽  
pp. 2581
Author(s):  
Huanjie Wu ◽  
Chun Chen ◽  
Kai Weng
Keyword(s):  
Energy Efficiency ◽  
Power Consumption ◽  
Low Power ◽  
Power Saving ◽  
Research Direction ◽  
Sleep Time ◽  
Analytical Models ◽  
Clock Frequency ◽  
Improve Energy Efficiency ◽  
Time Required

Power saving has always been an important research direction in the field of microcontrollers. Dozens of low power technologies have been proposed to achieve the goal of reducing their power consumption. However, most of them focus mostly on lowering the consumption rate. It is well known that energy is the integral of power over time. Thus, our view is that both power and time should be carefully considered to achieve better energy efficiency. We reviewed some commonly used low power technologies and proposed our assumptions and strategy for improving energy efficiency. A series of test sets are designed to validate our hypotheses for improving energy efficiency. The experimental results suggest that time has no less impact on energy consumption than power. To support the operation of the processor, some peripheral components consume a constant amount of power regardless of the clock frequency, but the power consumption will be reduced when the processor enters low-power modes. This results in some interesting phenomena that are different from the usual thinking that energy can be saved by increasing processor clock frequency. For STM32F407 and Xtensa LX6 processors, this article also analyzes and calculates the minimum sleep time required for achieving energy saving based on our analytical models. Our energy efficiency strategy has been verified, and in some cases, it can indeed improve energy efficiency. We also proposed some suggestions on hardware design and software development for better energy efficiency.

Sign in / Sign up

Export Citation Format

Share Document