IEEE INFOCOM 2005, Miami, FL

RID: Radio Interference Detection in Wireless Sensor

Networks

Gang Zhou, Tian He, John A. Stankovic, Tarek F. Abdelzaher

Computer Science Department, University of VirginiaMarch 2005

Outline

Motivation, State of the Art, and Contributions

Radio Interference Detection Protocols RID protocol RID-B protocol

Using Radio Interference Detection in TDMA Designs

Conclusions and Future Work

Motivation

Use Communication Topology as the Basis of TDMA Designs One popular example:

Assume collision free by allowing one node, within two communication hops, to transmit packets at a time.

Using Communication Topology is Misleading

Case B: Not Bandwidth Efficient

B DC

Case A: Not Collision Free

D BA

A’s Comm. Range

AC

How about K hops communication topology?

K needs to be > 2 ! K needs to be < 2 !

We Need to Detect Radio Interference!

State of the Art

Communication Topology is Widely used as the Design Basis of TDMA Protocols

In MANET: NAMA protocol [Bao and Garcia-Luna-aceves 2001]

In WSN: TRAMA protocol [Rajendran et al. 2003]

Pervasive Existence and Complexity of Radio Interference are Reflected in Recent WSN Experiments:

Shadowing Phenomena [Woo et al. 2004] Radio irregularity [Zhou et al. 2004] Packet delivery performance [Zhao and Govindan 2003] Reliable multihop routing [Woo et al. 2003] Connectivity assessment tool [Cerpa et al. 2003]

Contributions

To the best of our knowledge, our protocols, RID and RID-B, are the first to detect radio interference topology in runtime systems

Apply radio interference detection in TDMA design (take NAMA as a case study)

NAMA-RID-B keeps 100% packet delivery ratio In heavy load, NAMA can have packet loss up to 60%

Analyze the application of radio interference detection in backoff algorithms.

(See paper for detail) Study the relationship between communication range

and interference range in MICA2 devices, in both strong link case and weak link case.

(See paper for detail)

RID Protocol

RID Phases: HD-ND Detection Information Sharing Interference Calculation

Range 1: A’s High Sending Power Communication Range

Range 2: A’s Normal Sending Power Interference Range

B

AC

Range 1Range

2

HDHDND

ND

RID Protocol

Transmitter

Receiver:

HD ND

T1 T2

HD

PropagationDelay

MHWT

HD ND

System wide solution: Random back off

RID Protocol

Signal from T1: HD ND

T1 T2

Signal from T2:

AccumulativeSignal:

MHWT

HD ND

MHWT

HD

System wide solution: Random back off Add-on rule

Condition A: Stable power level during T1

Condition B: Stable low power level (background noise power) during T2

Transmitter

Receiver:

HD ND

T1 T2

HD

PropagationDelay

MHWT

HD ND

RID Protocol

System wide solution: Random back off Add-on rule

Condition A: Stable power level during T1

Condition B: Stable low power level (background noise power) during T2

Signal from T1: HD ND

T1 T2

Signal from T2:

AccumulativeSignal:

MHWT

HD ND

MHWT

HD

RID Protocol

System wide solution: Random back off Add-on rule

Condition A: Stable power level during T1

Condition B: Stable low power level (background noise power) during T2

Signal from T1: HD ND

T1 T2

Signal from T2:

AccumulativeSignal:

MHWT

HD ND

MHWT

HD

RID Protocol

System wide solution: Random back off Add-on rule Multi-round

Detections

Signal from T1: HD ND

T1 T2

Signal from T2:

AccumulativeSignal:

MHWT

HD ND

MHWT

HD

RID Phases: HD-ND Detection Information Sharing Interference Calculation

ID1 Power1

ID2 Power2

ID3 Power3

…… ……

Interference_In Table

Record:Who can

interfere with me and how

much it is

ID10 Power10

ID11 Power11

ID12 Power12

…… ……

Interference_Out Table ID21 Power21

ID22 Power22

ID23 Power23

…… ……

Interference_HTP Table

Record:Who I can

interfere with and how much

it is

Record:Who can

interfere with one of my

neighbors and how much it is

This Phase generates two more

tables

Goal: Figure out All Collision Cases by Local Calculation Basic Step:

Calculate possible interference cases at receiver D, when there are only two simultaneous transmitters

RID Phases: HD-ND Detection Information Sharing Interference Calculation

(1) Node i1’s signal can be disturbed by node i2’s signal (2) Without interference, node i1’s signal is able to be

received by node D

)}_(

)*)((|),{()(

1

21212

ysensitivitreceiverP

SNRPPPiiDN

Di

TidleDiDi

(1)

(2)

Interference Calculation --- Extension Step

Extension: How about k simultaneous transmitters?

))))}(),...,,(

),...,(,...,(

12((

)_(

)*)...((

|),...,,{()(

111

11211

21

1

21

DNjji

ijjijj

ktt

ysensitivitreceiverP

SNRPPPP

iiiDN

tt

ktt

Di

TidleDiDiDi

kk

k

(1)

(2)

(3)

(1) Node i1’ signal can be disturbed by the sum of node set {i2, ……, ik}

(2) Without interference, node i1’s signal is able to be received by node D

(3) Any proper subset of node set {i2, ……, ik} can not generate enough interference

Interference Calculation --- Properties

Two interesting properties of : )(DNk

N

iik

N

k

ji

DNSysteminScenariosCollisionAll

DNDNjiji

12

)()2(

)))()(((,)1(

Is complete

Has no Redundan

cy

RID-B Protocol

Motivation of RID-B Future traffic information is needed to take full use of

Nk(D) in RID. Very expensive, especially in WSN

RID-B’s concern: Detect nodes that can interrupt the receiver’s reception of the weakest packet from nodes within its communication neighborhood.

JR

ED

C

G

F

RID-B Calculation

How to achieve that? The same way to build Interference_In table Reorganize the Interference_In table

Replace entry (transmitter ID, power level) with entry (transmitter ID) if the following condition is met

Entry is removed, if the condition is not met

}_|min{

*)(

min

min

ysensitivitreceiverPJiPPwhere

SNRPPP

iRiRR

TidleJRR

Weakest signal power level from R’s

communication neighbors (C here)

JR

ED

C

G

F

Using RID-B in NAMA Protocol

NAMA Protocol Scheduling is based on 2 hops communication topology. Each node makes local decision whether it can have the

current time slot, based on IDs in two communication hops.

Without communication, there comes a consensus. Only one node wins the time slot.

NAMA-RID-B Protocol Scheduling is based on 2 hops of interference topology. Each node makes local decision whether it can have the

current time slot, based on IDs in two interference hops. Without communication, there comes a consensus. Only

one node wins the time slot.

Simulation ConfigurationComponents Setting

Simulator GloMoSim

Terrain (144m X 144m) Square

Node Number 144

Node Placement Uniform

Payload Size 32 Bytes

Application Many-to-one CBR streams

Routing Protocol GF

MAC Protocol NAMA/NAMA-RID-B (ACK added, Max #Retransmission is 8)

Radio Model RADIO-ACCNOISE

Radio Bandwidth 250Kb/s

Radio Range 25m (Adjust parameter values to set different interference range)

Confidence Intervals The 90% confidence intervals are shown in each figure

Performance Evaluation

Performance with Different System Load

Overhead

Performance with Different System Load

Performance with Different ICR and SNR

(a) Performance with Different ICR (ICR=RI/Rc)

(b) Performance with Different SNR Threshold

Conclusions

To the best of our knowledge, our protocols, RID and RID-B, are the first to detect radio interference topology in runtime systems

Apply radio interference detection in TDMA design. It improves NAMA’s packet delivery ratio from 40% to 100%, in heavy load.

Analyze the application of radio interference detection in backoff algorithms.

Study the relationship between communication range and interference range in MICA2 devices, in both strong link case and weak link case.

Future Work

Predict future traffic information, and combine it with RID to design more bandwidth efficient TDMA

Explore the use of RID-B in backoff algorithms in detail

Analyze the combination of RID with topology control protocols

Implement and evaluate radio interference detection in a large-scale sensor network system

Explore the interaction between radio interference and radio irregularity

The End!

Thanks to anonymous reviewers for their valuable

comments!

Thanks to anonymous reviewers for their valuable

comments!