UbiBayAn auction system for mobile multihop ad-hoc networks*

Hannes Frey, Johannes K. Lehnert, Peter SturmSystem Software and Distributed Systems, University of Trier

* This work is funded in part by DFG, Schwerpunktprogramm SPP1140 “Basissoftware für selbstorganisierende Infrastrukturen für vernetzte mobile Systeme”

Assumptions

Metropolitan sized networking Mobile devices

Wireless communication facilities

Direct communication only within communication range

Unpredictable topology changes due to mobility Network partitions Permanent link failures

The UbiBay application People sell low-value goods “in their neighborhood”

Too much effort to put it on eBay Enough potential buyers locally Need for “cheap” communication

Exchange of goods By appointment Supermarkets etc. as trustworthy third parties Quick auctions at popular places: people have goods with them

Auctions of low-value goods well suited for ad-hoc networks Decentralized and self-organizing Restricted geographical area Not time-critical

The UbiBay application

Start new auctions Describe auction Define minimum bid and duration

See a list of all known auctions View details:

bids, duration, description Participate in auctions

Define maximum bid Notifications

of being outbid of finished auctions

UbiBay

Auctions running:

Bidding on:

Auctioneer for:

10 CD-Rs J. Doe $5.5Details

Bid

Title Auctioneer Bid

Title Auctioneer Bid Max

Dilbert book S. Smith $7 $10 Bid

Dilbert book S. Smith $7Details

Bid

Title #Bids Leader Bid

Calendar 3 B. Stevens $1.5

The UbiBay application

Devices communicate through messages Auction/Description/Notification message Dissemination of messages with PeriodiCast

UbiBay application on all mobile devices Redistributes received messages Distributed maximum computation Handles bidding up to maximum bid Protects maximum bid

The UbiBay application Reputation system

Buyer and seller rate each other Differentiate personal and community ratings Use counters to measure reliability Disseminate ratings using PeriodiCast Follows approach by Schneider et. al., 2000

Security Ensure integrity of messages Cope with replay and

suppression of messages Decentralized and self-organizing CA

PeriodiCast Use device discovery for background

information dissemination Fill unused parts of MTU Distribute information over several

discovery messages Handle fragmentation Timeouts avoid collisions/congestion

Applications reserve buffers/ports Guaranteed priority Notification after dissemination

Allows parallel use of other communication patterns

unusedDevice discovery

MTU

IDPort

IDPort

IDPort

priority based scheduling

Application 1 Application 2bu

ffer

buff

er buff

er

Enhancements/Future work

Handle message suppression Observing mechanism: neighbors detect

malicious devices

Allow mobility of auction agents Marketplace communication pattern

Position-based routing

Protect the maximum bid through secret sharing

Implement UbiBay on real hardware Field test with students