interference-aware qos routing ( iqrouting ) for ad-hoc networks

Interference-aware QoS Routing (IQRouting) for Ad-

Hoc Networks

Rajarshi Gupta, Zhanfeng Jia, Teresa Tung, and Jean Walrand

Dept of EECS, UC Berkeley

Globecom 2005St. Louis, Missouri

EECS, UC Berkeley November 2005

2

Battalion of Tanks

Support flows with QoS Video streaming Voice calls Urgent messages

DARPA sponsored SmartNets Project


3

Interference Wired networks

Independent links Ad-hoc networks

Neighbor links interfere

Interference range > Transmission range

For simulations Tx range = 500 m Ix range = 1 km

InterferenceRange

TransmissionRange

Node A

Node D

Node C

Node B

Link 2

Link 1


4

Interference Model

Node

Link

Link

Conflict


5

Cliques Cliques

Clique= Complete Subgraph

Maximal Clique is not a subset of any other clique

Cliques in Conflict Graph Set of links that all

interfere with each other Closely related to capacity

Clique Constraints Only one link in a clique

may be active at once Flows on all links in a

clique must sum 1

A

B C

E F

D

Maximal Cliques:

ABC, BCEF, CDF


6

Available Bandwidth Available bandwidth on a link (avlbw)

Each link part of many maximal cliques Consider slack on each clique constraint Take the minimum

Available bandwidth in network/path Minimum of avlbw of all links in network/path

Key difference between wired and ad-hoc In wired, width of path determined by bottleneck

link In ad-hoc, width determined by bottleneck clique


7 Bellman’s Principle of Optimality Principle states: If optimal path from S to D

goes through A, then it follows optimal path from A to D (Bellman)

Distributed routing algorithms hinge on this principle

S AD


8

Principle of Optimality in Ad-Hoc ? Widest path from node 1

to 3 is link A (FA 1) Consider widest path

from node 1 to 5 Path A-D-E:

FA+FD+FE 1 so capacity 1/3

Path B-C-D-E: FB+FC 1, FC+FD 1,

FD+FE 1, so capacity 1/2

2

31

45

A

CB

E

Dinterference

E

CD

B

A

Connectivity Graph Conflict Graph

Does not conform with Bellman’s Principle of Optimality Hence, work with distributed heuristic algorithms


11

IQRouting at Source Link state protocol distributes available bandwidth

information Choose five candidate paths by source routing

Widest Shortest Path (WSP) WSP compliment Shortest Feasible Path (SFP) OSPF-like weighted path cost ( + used capacity) Shortest Widest Path (SWP)

Use ad-hoc versions of well-known QoS routing algorithms Account for interference among neighboring

links Clique constraints determine avlbw


12

Distributed IQRouting

Candidate paths are compared using probe packets Distributed comparison across network Nodes in path use local and current clique

information Probe rejected if lack of resources QoS metric accumulated along path

Best candidate chosen at destination


13

Comparison of Path Metric

Probe packets Evaluate clique

capacities along path Check if clique

constraints are met Accumulate path metric

(e.g. minimum of avlbw on path)

Look for bottleneck clique

FB+FC+FD+Fothers 1FD+FE+FG+Fothers 1

1

2

3

4

5

6

7

8A

C

B

D

E

H

G


15

Simulations Topology

Random 100 nodes 3 km X 3 km field Transmission 500 m Interference 1 km Flows between 5 src & 5 dest nodes

Note Random flow arrivals, durations By changing mean of flow arrival and

duration, we alter the “load” on the network


16 Comparing Admission Ratios

Competing algorithms Shortest Path OSPF ILP-based SFP Ad-Hoc SFP

2 flavors IQR-Width IQR-Cost

Results IQR performs

better


17

Grid 10X10 Grid Choose node

pairs 7 hops apart

Compare adm ratios and path length

At higher load, IQR finds longer paths with greater capacity


18

0 0.5 1 1.5 2 2.5

0

0.5

1

1.5

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2.5

50%

100%

0%

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2122

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X position in km

Y p

ositi

on in

km

0 kbps 1000 kbps500 kbps

Choose SourceChoose DestinationClick on bar to choose flow rateRouting…


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0 0.5 1 1.5 2 2.5

0

0.5

1

1.5

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50%

100%

0%

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X position in km

Y p

ositi

on in

km

Choose Source, click on clear area to quit

Flow 1 from 32 to 3 at 298.9889 kbps


Choose Next SourceChoose DestinationClick on bar to choose flow rateRouting…


20

0 0.5 1 1.5 2 2.5

0

0.5

1

1.5

2

2.5

50%

100%

0%

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X position in km

Y p

ositi

on in

km


Flow 1 from 32 to 3 at 298.9889 kbpsFlow 2 from 2 to 33 at 298.9889 kbps


21

0 0.5 1 1.5 2 2.5

0

0.5

1

1.5

2

2.5

50%

100%

0%

1

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2122

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3435

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3738

3940

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X position in km

Y p

ositi

on in

km


Flow 1 from 32 to 3 at 298.9889 kbpsFlow 2 from 2 to 33 at 298.9889 kbps


Choose Next SourceChoose DestinationClick on bar to choose flow rate

Flow Rejected. Insufficient Resources


22

Conclusions Multi-hop services have a long way to go

Actual capacity far lower than advertised Shortest path methods are inadequate Heuristic schemes most promising

IQRouting proposes one simple, distributed algorithm for ad-hoc networks

Performance results show significant improvement

Questions

http://www.eecs.berkeley.edu/~guptar

[email protected]

interference-aware qos routing ( iqrouting ) for ad-hoc networks

Documents

width of path

optimal path

metaccumulate path metric

path bc

weighted path cost

widest pathpick shorter

clique constrainttake

bottleneck linkin ad