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A Topology Control Approach to Using

Directional Antennas in Wireless Mesh

Networks

Umesh Kumar, Himanshu Gupta and Samir R. DasDepartment of Computer Science

State University of New York at Stony Brook

ICC 2006

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Outline Introduction Background and Problem formulation Algorithm Performance evaluation Conclusion

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Introduction Direction vs. Omni-direction

Spatial reuse The transmission range of direction antennas

are longer than one of omni-direction antennas Improving capacity

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Background and Problem formulation--Assumption The transmission range of direction

antenna : Rd The transmission range of omni-direction

antenna : Ro Rd/Ro = 2/tan(θ/2)

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Interference model The number of nodes are hear this

transmission

u ve

A

G

B

E

C

D

F

|Interfer(e)| =2

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Problem formulation k-direction antennas on each node

kθ < 360 max node degree is k Maximizing throughput

Minimizing interference Smaller interference caused path lengths

increasing

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Spanning Tree Algorithm Furer and Raghavachari’s algorithm

G=(V,E) Input : random spanning tree T=(V,E) Let S be the set of vertices having degree d or d-1

(d is the degree of T) Let T1,…,Tr be the subtrees comprising T-S If there is an edge between Ti and Tj, the edge is

inserted in T Output: minimum degree spanning tree T=(V,E)

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10

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Using direction antenna A centralized algorithm Using k arcs of angle θ and radius Rd on

each node to cover all edges in E’

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Performance evaluation :Simulation environment

Simulator Qualnet

The number of node 100

Transmission range 70m

Network size 300 m2 or 500 m2

Average node degrees 5 or 13

Antenna beamwidth 30,45 and 60

The number of antennas 3 or 4

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Performance evaluation:Topological properties Average interference per network link

Average stretch factor The ratio of the shortest path lengths with

directional antennas and omni-directional antennas in the mesh network

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Average interference per link with different beamwidths

3 antennas per node

4 antennas per node

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Average Stretch factors with different beamwidths

3 antennas per node

4 antennas per node

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Packet delivery fraction for qualnet simulations (4 antennas per node)

Dense network

Sparse network

100 nodes and50 flows

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Packet delivery fraction for qualnet simulations (3 antennas per node)

Dense network

Sparse network

100 nodes and50 flows

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Conclusion This paper presented a topology control

approach to using directional antennas in wireless multihop networks. Low interference Reasonable stretch factor Increasing the end to end throughput

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