Detecting Phantom Nodes in Wireless Sensor Networks

Joengmin Hwang, Tian He, Yongdae Kim(ACM Infocom2007)

Presenter : Justin

Main ideas

Two factors: Prevent the phantom nodes from generating

consistent ranging (distance) claims to multiple honest nodes.

Detect phantom nodes by the proposed speculative method

Generating ranging claims If the locations of neighboring nodes are

known, it is easy to generate a fake location. Without the location information of the

neighboring nodes, it is hard for an attacker to generate a set of consistent ranging values (distances)

Generating ranging claims C

B

D

A

D’

Generating ranging claims C

B

D

A

D’

D’C and D’B decreaseD’A increase

Generating ranging claims

C

B

D

AD’

Generating ranging claims

C

B

D

A D’

D’C and D’B increaseD’A decrease

The detailed approach

Definition: A set of nodes is consistent, if they can be

projected on the unique Euclidean plane (in 3-D case, Euclidean space), keeping the measured distances among themselves.

The detailed approach

Problem: Given a node set Nbr(v) that consists of a

node v and its neighbors, and a distance set D that consists of the measured distance, denoted by

Find the largest consistent subset of Nbr(v).

}),(,,ˆˆ|ˆ{ jivNbrjiddd jiijij

The detailed approach

Two phases: Distance Measurement Phase Filtering Phase

Distance Measurement

1) Node v measures distance to each neighbor i

2) Node v announces the measured distance3) Node i announces its measured distance to

its neighbor j, and v collects4) For each collected distance, if , it is

included in the filtering phase

vid̂

ijd̂

jiij dd ˆˆ

Filtering

Using a graph G(V,E) to construct a consistent subset.

The set V is used to contain the node v and its neighbors

The set E is used to keep the edges between two nodes when the distance information between them maintains consistency.

Filtering

1) The local coordinate system L is determined by three nodes v, i, j with measured distance

2) Each node , calculating its location on L

3) Picking a pair of nodes , whose location on L are

4) Comparing the distance and ( which obtained in distance measurement phase )

5) If , create edge e(i, j) in E6) Choose the largest sizeof G(V,E)

ijvjvj ddd ˆ,ˆ,ˆ

)(vNbrk kp

)(, vNbrji ji pp ,

||~jiij ppd ijd̂

|~ˆ| ijij dd

Filtering

Filtering

ip

jp

||~jiij ppd

If , create edge e(i, j) in E Choose the largest sizeof G(V,E)

|~ˆ| ijij dd

Filtering

Node 6 is a phantom node

Filtering

Experiment results

Experiment results

Experiment results

Conclusions

Pros Presenting a way to exclude the phantom

nodes by projecting each nodes into a local coordinate

The filtering operation is efficient

Cons By using TDOA or TOA to measure distance,

nodes need to be deployed at wide-space It’s not suitable for small area application