Towards energy-awareness in managing wireless LAN applications

01/2012; DOI: 10.1109/NOMS.2012.6211930


We have investigated the scope for enabling WLAN applications to manage the trade-off between performance and energy usage. We have conducted measurements of energy usage and performance in our 802.11n WLAN testbed, which operates in the 5 GHz ISM band. We have defined an effective energy usage envelope with respect to application-level packet transmission, and we demonstrate how performance as well as the effective energy usage envelope is effected by various configurations of IEEE 802.11n, including transmission power levels and channel width. Our findings show that the packet size and packet rate of the application flow have the greatest impact on application-level energy usage, compared to transmission power and channel width. As well as testing across a range of packet sizes and packet rates, we emulate a Skype flow, a YouTube flow and file transfers (HTTP over Internet and local server) to place our results in context. Based on our measurements we discuss approaches and potential improvements of management in effective energy usage for the tested applications.

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Available from: Saleem N. Bhatti
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    • "We then compare these to a performance envelope, based on the operation of a single client, generated on an IEEE 802.11n/g testbed. While we have constrained ourselves to 802.11g and 802.11n for practical purposes (e.g. the network configuration of the University of Twente deployment), our methodology for generating the performance envelopes has been applied to other IEEE 802.11 variants in our previous work [2], [3]. The considered GoAs are: real-time audio, realtime video, streamed (non-real-time) audio, streamed video and bulk data transfers. "
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    ABSTRACT: We demonstrate that in a future converged network scenario, it may be beneficial to allow selection of 802.11 variant based on application requirements. We analyse traces from the campus network from the University of Twente, comprising ∼5000 users. We have evaluated a performance envelope derived from testbed experiments for individual IEEE 802.11 variants and compare these with the traffic patterns from the campus network. From our comparison, we find that specific IEEE 802.11 variants (e.g. 802.11g or 802.11n) may be better suited to specific applications, such as video streaming, rather than using a single WLAN standard for all traffic.
    Full-text · Conference Paper · Jan 2013
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    ABSTRACT: 802.11 WLAN is a popular choice for wireless access on a range of ICT devices. A growing concern is the increased energy usage of ICT, for reasons of cost and environmental protection. The Power Save Mode (PSM) in 802.11 deactivates the wireless network interface during periods of inactivity. However, applications increasingly use push models, and so devices may be active much of the time. We have investigated the effectiveness of PSM, and considered its impact on performance when a device is active. Rather than concentrate on the NIC, we have taken a system-wide approach, to gauge the impact of the PSM from an application perspective. We experimentally evaluated performance at the packet level and system-wide power usage under various offered loads, controlled by packet size and data rate, on our 802.11n testbed. We have measured the system- wide power consumption corresponding to the individual traffic profiles and have derived application-specific effective energy-usage. We have found that in our scenarios, no significant benefit can be gained from using PSM.
    No preview · Conference Paper · Nov 2012
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    ABSTRACT: Widespread use of wireless LAN (WLAN) may soon cause an over-crowding problem in use of the ISM spectrum. One way in which this manifests itself is the low Received Signal Strength Indication (RSSI) at the WLAN stations, impacting performance. Meanwhile, the IEEE 802.11 standard is being evolved and extended, for example with new coding schemes and the 802.11n standard, which makes use of 5GHz and 2.4GHz. We report on measurements of the upper and lower bounds of performance with good and poor RSSI in 802.11g and 802.11n. We find that in operation under poor (low) RSSI, performance is indeed impacted. In some cases the impact is such that there may be little benefit in using the newer 802.11n over the mature 802.11g.
    No preview · Conference Paper · Jan 2013
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