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Le Wang, Jukka MannerAalto Univeristy
Dept. Communications and Networking
e-Energy 31.5.2011
Proxies for Energy-Efficient Web Access Revisited
This work is to present a proxy-based solution for energy-efficient web access
Introduction and Background
Experimental setup and results
Architecture and Design
Battery constraint leads to the reconsideration of energy-efficient mobile data services
Goals
Various miscellaneous works exist on EE mobile communication (e.g. [2] and [7] in the paper)Data communication is a key function on modern mobile phonesWe want to see how much, when, why we can save energy
• No simulations: design, implement and measure• Focus on web content for now
Think also about deployment• Don't seek to change the whole Internet
Goals
Our previous work has showed what really matters• Anything you do, make it quick• Radio consumes an almost fixed amount of energy
regardless of amount of bits transferredFeatures of a good solution
• Generic and transparent solution• Independent of individual browsers• Bundling and compression to decrease delivery time• Minimizing the side-affect of TCP throughput
We re-visit “classical” PEPs for ordinary mobile users and energy saving
Solution outline
Two components• Client-side “web proxy” (similar to an SSH proxy setup)• Network-side enhanced web proxy
Our own protocol bw. the components• Standard HTTP from proxy to web content servers
Use a derivative of DTNs: putting data in a “bundle”Compare different alternatives
• Straight connectivity• Simple compressing HTTP proxy• Bundle web content bw. mobile and proxy• Bundle & compress web content
Simplified messaging is used to fetch bundled and compressed web content from proxy after receiving all the embedded objects
Transparent proxy access, bundling and selective compression are main implementation components
Transparent proxy accessLibcurl and libmicrohttpdLocal browser points to 127.0.0.1
•BundlingBundling all web objects before sending
•Selective compression
Experiments
3 different wireless links• 2G (Edge)• 3G (HSPA, 2 mbit, good coverage)• WLAN (54G, close to AP)
3 different content• Wiki: mostly text, easily compressed, small• BBC web site: relatively light, mediu size• Iltalehti: very unfriendly for mobile users, huge
Web content at different distances from the user4 alternatives: none, compress. proxy, bundle & compressionMeasure:
• Latency• Consumed energy on the mobile device
Experimental setup
Results in 2G
Results in 3G
Results in WLAN
Summary
Transparent deployment without changing web browser and web servers
Simplified and efficient message exchange processReduce energy consumptionReduce traffic load on the wireless interface
Substantial power saving potential by using bundling and selective compression
Future Work
Improve the design and identify bundling conditions• When to bundle, when not, when to compress, etc.
Take web caching into consideration• Caching obviously helps, but how much?
Investigate other hardware platforms and web content
Look at better transport protocols for wireless links
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