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