NCS-2006 March 29-31, 2006 Chiang Mai, ThailandThe IASTED International Conference on Networks and Communication Systems

Assurance-aware Self-organization of Sensor Networks

Chutima Boonthum, Irwin Levinstein, Stephan Olariu, Lan Wang, Qingwen Xu{cboont, ibl, olariu, walng_l, xu_q}@cs.odu.eduDepartment of Computer Science, Old Dominion UniversityNorfolk, VA 23529 USA

2NCS-2006 March 29-31, 2006 Chiang Mai, ThailandThe IASTED International Conference on Networks and Communication Systems

Background & Motivation

Wireless Sensor Networks (WSNs) have been widely used in various applications

Securing WSNs has become a major issue and has number of proposed solutions

Yet, none of these addresses the issue on information assurance

Therefore, we explored various aspects related to “information assurance in WSNs”

3NCS-2006 March 29-31, 2006 Chiang Mai, ThailandThe IASTED International Conference on Networks and Communication Systems

Agenda

WSNs overviewSensors and sensor networksInformation assuranceSystem longevitySecuring individual sensors

Self-organizationAssurance-awareness

4NCS-2006 March 29-31, 2006 Chiang Mai, ThailandThe IASTED International Conference on Networks and Communication Systems

Sensors & Sensor Networks

Sensor fundamental constraints1. Sensors are anonymous

2. Modest non-renewable power

3. Sleep most of the time

4. Work unattended

5. Modest transmission range

WSNs are multi-hop, limited no of sensors, and unknown topology

5NCS-2006 March 29-31, 2006 Chiang Mai, ThailandThe IASTED International Conference on Networks and Communication Systems

Information Assurance

Network survivabilityAbility to function for a long period of time

Information survivabilityAbility to have uninterrupted and secure access to

information on network

Network securityBasic security services at network level

Information securitySecure information flow

6NCS-2006 March 29-31, 2006 Chiang Mai, ThailandThe IASTED International Conference on Networks and Communication Systems

System Longevity

Appropriate sleep-wake schedulesTo save the energy

Optimal workforceTo provide results satisfying a number of quality of

service requirements

Topology and coverage controlTo enhance the effective functional lifetime of the

network

7NCS-2006 March 29-31, 2006 Chiang Mai, ThailandThe IASTED International Conference on Networks and Communication Systems

Securing individual sensors

Tampering/ Tamper resistanceTrying to force open an individual sensor

Blanking out memory, orConfiguring the security service using frequency hopping

and cryptographic keys.Physically removing sensors from the deployment

areaEstablishing Signature Array (SA) of sensor’s

neighborhood using signal strengths, immediately after deployment.

If the sensor do not anymore receive the signals correspond with those in SA, then blank out memory

8NCS-2006 March 29-31, 2006 Chiang Mai, ThailandThe IASTED International Conference on Networks and Communication Systems

Assurance-aware Self-Organization

A powerful multi-hop communication network capable of utilizing the limited resources of sensors in adaptive and efficient wayEnergy efficiency

sensors need to sleep most of the time

AdaptivityVirtual infrastructure adapts to network size, topology,

density, and application requirement

Multi-hop systemVirtual infrastructure supports efficient multi-hop

communication

9NCS-2006 March 29-31, 2006 Chiang Mai, ThailandThe IASTED International Conference on Networks and Communication Systems

Leader Election

When sensor wakes up, it starts to listen for a beacon frame time period.

If it has not received, that itself becomes a leader and start sending the “Beacon Packet”

If it does, it then becomes a member of that cluster.

T: sleeping periodF: beacon frame length

10NCS-2006 March 29-31, 2006 Chiang Mai, ThailandThe IASTED International Conference on Networks and Communication Systems

Beacon Frame

Beacon slot (B) – sending time of each beacon frame Collision slot (C) – reserved for member to report potential

collision Wakeup slot (W) – reserved for member to wake up leaders Member slots (M) – for member to send messages to the cluster

leader

11NCS-2006 March 29-31, 2006 Chiang Mai, ThailandThe IASTED International Conference on Networks and Communication Systems

Collision Resolution

When a sensor receives some short beacon packets that are close to cause the collision problem, it sends a collision packet at its leader’s Collision slot and reset its listening timer.

If a leader hears anything in its Collision slot, it selects another time to send its beacon packet.

12NCS-2006 March 29-31, 2006 Chiang Mai, ThailandThe IASTED International Conference on Networks and Communication Systems

Competing for slots

A member randomly chooses a slot from “free” Member slots in the beacon frame and send a report packet twice (at Wakeup slot and at the chosen slot).

The leader will confirm if the package arrive; otherwise, a member will choose another “free” a lot and resend the packet.

If two members sent data on the same M-slot, the leader will receive no packet at that slot due to noises.

13NCS-2006 March 29-31, 2006 Chiang Mai, ThailandThe IASTED International Conference on Networks and Communication Systems

Maintaining the virtual infrastructure

Every sensor needs to listen for a beacon frame once in a while

Old leaders may fail and new leaders may show up

When a leader dies, a part of network needs to be reorganized. Hence, leader reelection is triggered.

14NCS-2006 March 29-31, 2006 Chiang Mai, ThailandThe IASTED International Conference on Networks and Communication Systems

Conclusion

We surveyed number of issues related to setting up the infrastructure that leveraged by information assuranceLeader election, Beacon frame, Collision resolution,

Competing for slots, Maintain the virtual infrastructure

Research toward a solution is ongoing.