Towards Sustainable Portable Computing through Cloud Computing and Cognitive Radios

Vinod NamboodiriWichita State University

Sustainability

• The World Wide Fund for Nature, United Nations Environment Programme, and World Conservation Union define sustainability as follows:

• Sustainability is improving the quality of human life while living within the carrying capacity of supporting eco-systems.

Computing Plays a Role

• Anywhere from 3-7% of global energy attributed to Information and Communication Technologies (ICT)

• That is why we have this workshop!

Sustainability – Portable Devices

Energy consumed off the grid

Laptops

Desktops

Data Cen

ters

Mobile Phones

Mobile In

frastr

ucture

Internet

0

50

100

150

200

250

300

350

400

450

Sectorwise electricity consumption (million MWh)

Electronic Waste

Somavat et. al, e-Energy 2010, with updated results

Does not include data center cooling costs

Existing Approaches

• Energy-aware schemes to maximize battery lifetime– Energy efficient protocols at various layers of the

stack – Cross-layer approaches

• Do not necessarily address energy consumed from the grid

• Do not address electronic waste problem

Hardware or Software Approach?

• New hardware could be more energy-efficient• New hardware = more electronic waste!

• Software upgrades through improved protocols, drivers, OS can also lead to energy-efficiency

• Minimizes device replacement

• Favor software approaches where possible

A Proposed Solution

• Rely on Cloud Computing paradigm– portable device executes all applications remotely– more like a thin-client

• Example– Game of Chess on Smartphone– Play locally or online

Application executed locally

on device hardware

Server(s)

Application executed on remote server over a communication network

Non-Cloud Architecture Cloud Architecture

• Periodic hardware upgrades needed on device due to limited local resources

• Periodic hardware upgrades lead to more waste

• Application execution with limited resources could be energy-inefficient for portable devices

• Non-Sustainable

• Fewer or no hardware upgrades needed on device; needed only on server(s)

• Rare hardware updates results in less waste• Application execution on remote, powerful

servers could be energy-efficient• More Sustainable

• Communication will be bottleneck• For portable devices, wireless medium

will have heavy contention• Cognitive Radio could be the answer,

if found energy-efficient

WLAN Access

Cognitive Radios

Courtesy Broadband Wireless Networking Lab, Georgia Tech

Courtesy Anonymous Source

Why Cognitive Radios?

• State-of-the-art solution to wireless spectrum congestion– Can continuously hunt for spectrum that is less

congested– Implemented mainly in software; software

upgrades can keep optimizing communication energy consumption

Are Cognitive Radios Energy Efficient?

• Save Energy– By finding spectrum with • Less contention• Better channel conditions

• Waste Energy– Scanning is a • power-intensive process• Delay inducing process

Merits of CognitionTo Energy Consumption- better channel- less contention

Demerits to obtaining Cognition- power intensive- time consuming

Physical Layer

Channel Conditions

Higher Layer

Node distribution, Channel scanning time, Number of nodes, etc.

Factors under Study

Cognitive Radio Result

Notes:Two radios used; one for scanning one for communicationNode conttention only factor differentiating channelsNumber of Channels Considered = 20. All scanned.

Cloud vs Non-Cloud

C1; Google DocsC2: Office Live

NC: Microsoft Office with WiFi off

Future Work

• Consider many cloud based applications• Understand cloud based network traffic and

optimize energy for communication• Consider cloud based application scenarios

and impact on energy consumption under the cognitive radio model