Reducing Interference in Ad hoc Networks through Topology Control

Tomas Johansson and Lenka CarrMotyckov´a

EISLAB Lulea University of Technology

SE971 87 Lulea, SwedenACM Discrete Algorithms and Methods for Mobile Computing an

d Communications-Principles of Mobile Computing

(DIALM-POMC’05)

Speaker : Chang Chau-Chieh

Outline

• Introduction• Interference metrics• Average Path Interference algorithm

(API) • Related works• Simulation• Conclusion

Introduction

• Topology Control• Increase the network lifetime• Minimize the interference

• Using interference model• Evaluate the topology

Introduction

• G=(V,E) : Euclidian graph • V : network nodes• E : communication links

Introduction

• GTC = (V,ETC) : t-spanner graph

• the shortest path in GTC between any two nodes is at most t times longer than the shortest path between these nodes in G

Interference metrics – (1)

• Interference model• the maximum coverage for any node

Interference metrics – (2)

• The metrics do not consider • the paths in the graph• the interference in general

Interference metrics – (2) (3)

• Interference-optimal path (IoptPuv)

• Interference-optimal path with the shortest path (SPuv)

Interference metrics – (4)

• Maximum interference difference metric

Average Path Interference algorithm (API)

• Computing a Gabriel graph• Reducing the graph

API- Step 1

API- Step 2

API

Related works

• Low Interference Spanner Establisher (LISE)

• XTC algorithm

LISE

• GTC = (V,ETC) : t-spanner graph

• the shortest path in GTC between any two nodes is at most t times longer than the shortest path between these nodes in G

e2

e1

LISE

• Interference model

S

Cov(e1) = 5Cov(e2) = 1

LISE

XTC

• Nodes needs local knowledge. • Degree : 6• GXTC does not contain any cycles of lengt

h 3

XTC

Simulation

Network size 20 * 20 units

Communication range 2.5 units

Topology control algorithm LISE, XTC, API

Simulation Results

Simulation Results

Simulation Results

Simulation Results

Conclusion

• We also propose a new topology control algorithm• Produce an energy-spanning graph • Established a new interference metrics• Low interference graph