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Liveliness Evaluation of a Cooperation and Accounting Strategy in Hybrid Networks Attila Weyland, Thomas Staub and Torsten Braun ASWN 2004, Boston August 9, 2004 University of Bern Institute of Computer Science and Applied Mathematics

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Attila Weyland, Thomas Staub and Torsten Braun

University of Bern Institute of Computer Science and Applied Mathematics Computer Networks and Distributed Systems Research Group (RVS)

Liveliness Evaluation of a Cooperation and Accounting Strategy in Hybrid Networks

ASWN 2004, Boston August 9, 2004

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8/9/2004 Liveliness Evaluation of a Cooperation and Accounting Strategy in Hybrid Net. - Attila Weyland

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Table of Contents

  • Introduction
  • Motivation
  • Concept
  • Architecture
  • Operation
  • Simulation Scenario & Parameters
  • Results
  • Summary & Outlook
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8/9/2004 Liveliness Evaluation of a Cooperation and Accounting Strategy in Hybrid Net. - Attila Weyland

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Introduction

  • Multi-hop Cellular Networks

– Combine dynamics of mobile ad hoc networks and reliability of infrastructured wireless networks – Compared to single-hop

  • Increased coverage area
  • Dynamic adaptation of network topology

Gateway Provider’s Backbone

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8/9/2004 Liveliness Evaluation of a Cooperation and Accounting Strategy in Hybrid Net. - Attila Weyland

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Motivation

  • New context to deal with weaknesses of

mobile ad hoc networks such as

– Routing – Security – Cooperation

  • Stimulate cooperation without threat of

punishment

  • Make cooperation a rewarding alternative

to selfishness

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CASHnet Concept

  • Every time a node wants to transmit a self-

generated packet, it has to pay with Traffic Credits (TC)

  • Every time a node forwards a packet, it gets

Helper Credits (HC)

  • Traffic Credits can be bought for real money or

traded for Helper Credits at service stations

Gateway Provider’s Backbone Service Station

  • TC

+HC +HC +HC

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8/9/2004 Liveliness Evaluation of a Cooperation and Accounting Strategy in Hybrid Net. - Attila Weyland

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Architecture

  • Assumptions

– Tamper resistant device which allows safe execution

  • f CASHnet functions and maintains two accounts

– Distance (in hop counts) to gateway provided by routing protocol – Sufficient processing power on the node

  • Security mechanisms are based on public key

cryptography

– Nodes authenticate themselves using certificates with short life time issued by the provider – Transmitted messages are digitally singed ensuring non-repudiation (data integrity and data origin authentication)

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8/9/2004 Liveliness Evaluation of a Cooperation and Accounting Strategy in Hybrid Net. - Attila Weyland

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Operation

Gateway Provider’s Backbone Gateway Provider’s Backbone Service Station

  • 4 TC

+1 HC +1 HC +1 HC +1 HC +1 HC

  • 3 TC

Smart Card

CASH net

  • 20 HC
  • 10 RM

+20 TC

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8/9/2004 Liveliness Evaluation of a Cooperation and Accounting Strategy in Hybrid Net. - Attila Weyland

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Simulation Scenarios

A B C

Gateway Mobile Node Service Station

D

10 HC Exchange threshold at Service Stations 50 m Distance threshold to Service Stations 1:1 Traffic Helper Credits exchange rate 500 Initial Real Money account state 100 TC Initial Traffic Credits account state Value Parameter

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Simulation Parameters

900 s Simulation time 1, 0.2, 0.1 pkt/s Packet generation rate 1, 2, 9, 12 Number of Service Stations

  • u. d. between 0 and 20 s

Pause time

  • u. d. between 1 and 10 m/s

Speed random waypoint Mobility model 250 m Transmission range 40 Number of nodes 1500 m x 800 m Area Value Parameter

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Starvation Periods

  • Starvation: a node is unable to transmit self-

generated packets because of missing TCs

5 s packet interval 2 service stations 5 s packet interval 12 service stations

1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39 100 200 300 400 500 600 700 800 900 Simulation time (s) CASHnet, 5 s packet interval, 12 service stations, run 0 Starvation period 1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39 100 200 300 400 500 600 700 800 900 Simulation time (s) CASHnet, 5 s packet interval, 2 service stations, run 0 Starvation period

1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39 100 200 300 400 500 600 700 800 900 Simulation time (s) CASHnet, 5 s packet interval, 2 service stations, run 0 Starvation period

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2 4 6 8 10 12 14 16 18 20 800 760 720 680 640 600 560 520 480 440 400 360 320 280 240 200 160 120 80 40 Starvation length (s) CASHnet, 1 s packet interval, 1 service station Mean starvation occurance

Starvation Events/Duration Category

1 s packet interval 1 service station 1 s packet interval 12 service stations 10 s packet interval 1 service station 10 s packet interval 12 service stations

2 4 6 8 10 12 14 16 18 20 800 760 720 680 640 600 560 520 480 440 400 360 320 280 240 200 160 120 80 40 Starvation length (s) CASHnet, 10 s packet interval, 12 service stations Mean starvation occurance 2 4 6 8 10 12 14 16 18 20 800 760 720 680 640 600 560 520 480 440 400 360 320 280 240 200 160 120 80 40 Starvation length (s) CASHnet, 10 s packet interval, 1 service station Mean starvation occurance 2 4 6 8 10 12 14 16 18 20 800 760 720 680 640 600 560 520 480 440 400 360 320 280 240 200 160 120 80 40 Starvation length (s) CASHnet, 1 s packet interval, 1 service station Mean starvation occurance 2 4 6 8 10 12 14 16 18 20 800 760 720 680 640 600 560 520 480 440 400 360 320 280 240 200 160 120 80 40 Starvation length (s) CASHnet, 1 s packet interval, 12 service stations Mean starvation occurance

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Results

  • Duration and frequency of starvation

events correlates with

– Number of Service Stations – Location of Service Stations

  • Simulation results affected by mobility

model

– Random waypoint movement paths behave centric (2 service stations worse than 1 centered)

  • Per packet charging lets nodes run out of

Traffic Credits/Real Money quickly

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Summary & Outlook

  • Highly decentralized accounting and security

architecture

  • Selfish nodes are allowed, but cooperation is

encouraged via rewards

  • Cost sharing between sender & receiver
  • Evaluation of starvation property through simulations

Compare with other cooperation schemes Use different mobility models, e.g. restricted random waypoint Study effects of possible extensions (e.g. charging for ad hoc only traffic, deposit payment for receiving traffic, increasing granularity) Specify charging/remuneration relation

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Implementation

  • ns-2 [Vint Project], Wireless and Mobility

extensions [Rice] and AODV+ [Hamidian]

  • Class CashnetNode inherits from MobileNode
  • Agent at ns2 src/sink does rewarding
  • Class CMUTrace extended for CASHnet events