““Effects of power conservation, wireless Effects of power conservation, wireless coverage and cooperation on data coverage and cooperation on data

dissemination among mobile devices”dissemination among mobile devices”

20012001

Authors: Maria Papadopouli and Henning Schulzrinne

Presented by:Taylor Perkins

About MeAbout Me

Taylor Perkins– 5th Year Co-op Computer Science Major– Specializations: UI & Databases– From Roswell, GA– Interests:

Anything new and interesting More high-level, less low-level

ProblemProblem

Increase in non-voice data– News, traffic, weather, sports, etc.

Sparse coverage or high costRequires connectivity to the InternetLots of Power UsageHow to increase data access, but not

increase power usage?

SolutionSolutionShare data between roaming usersMotivation:

– High spatial locality of info– Different information providers

Not necessarily cooperating with each otherImagine: A Train or Airport

– High spatial locality: News, sports, schedules– Popular info: Music & Video games

7DS – P2P sharing system7DS – P2P sharing system“7DS is an architecture, a set of protocols,

and an implementation enabling the exchange of data among peers that are not necessarily connected to the Internet.”

ApplicationMobile & Stationary DevicesAnticipate information needs, searches

among peers for this information.

How it WorksHow it Works Two modes

– Prefetch Anticipate information needs

– On-demand Search among peers after fetch from Internet fails

Two interaction types– Peer-to-peer (P-P) – 7DS’s main focus

Data sharing Message forwarding Caching popular information

– Server-Client (S-C) – Servers also connected to other servers Data sharing Message forwarding Caching popular information

More DetailsMore Details Device forms queries based on URL of request Also predicts future URLs Multicasts these queries to other devices Host can select subset of requests to listen to

(Saves power) 7DS-enabled servers can broadcast that they have

data (advertisement) 7DS organizes and manages device cache

– User can view, browse and manage cache through GUI

How it Saves PowerHow it Saves Power Trades power for data only when battery is above

threshold. Reduce energy consumption

– Idle periods– Low expectation of data– Battery life below threshold– Periodically turn off network interface

Reduce collaboration (Thresholds):– Above 75% Battery: Active querying– 50%-75%: Passive querying (only responds)– Below 50%: Stops participation in 7DS

Some ResultsSome Results

Experiment Setup:

1km x 1km test space.

One node has data, which all other nodes are interested in getting.

Some More ResultsSome More Results

And More ResultsAnd More Results

CriticismCriticism

7 Years old– More power, more bandwidth

Requires other 7DS users– Software install– Cooperation

Hard to Perform Experiments– Requires simulation