1. On the Energy Efficient Design of Wireless Sensor Networks Tariq M. Jadoon, PhD Department of Computer Science Lahore University of Management Sciences

2. Agenda Overview MAC and Network Layer Simulation Model Results Conclusions & Future Work

3. Overview What are WSNs? Wireless Sensor Networks (WSNs):  Small sensor nodes (or motes)  Monitoring the environment and processing and communicating the gathered information. Base stations (also called sinks)  centralize the data gathered by sensor nodes. Sensor nodes consist of: Sensors Embedded processor Radio transceiver Battery http://www.evaluationengineering.com/archive/articles/0704/Images/dataFIG1-copy.jpg

4. Energy Conservation Low Traffic Rate / Predefined traffic patterns Low Mobility Sensor Vs. Adhoc Networks

5. Main Issues in the Design of WSNs Energy Conservation Low-cost Optimal placement of the sensor nodes Energy efficient design across all layers Radio communication is a major source of power consumption MAC layer design => rules of transmitting and receiving over the wireless medium using the radio. What is the effect of changing the MAC layer protocol on the average energy consumed for a given network layer protocol? Is it possible to tune the MAC/ Network layer for optimal energy consumption?

6. Energy Consumption Transmission Reception Overhead Collision Idle Listening Overhearing Control Packets  Advantages: Collision Avoidance, Idle Listening Overhearing Avoidance  Disadvantages: Frequent Synchronization Scalability  Advantages: No Synchronization Scalable  Disadvantages: Collision Idle Listening, etc. MAC Layer (who transmits when) MAC Protocols Scheduled (TDMA Based) Random Access (Contention-Based)

7. Random Access MAC Protocol S-MAC Periodic Listen and Sleep Collision Avoidance Overhearing Avoidance Implementation Details Perfect Synchronization Message Passing Overhearing Avoidance Cycle Length – 1 sec 3%, 5% S-MAC Frame Sizes RTS: 20 Bytes CTS/ACK: 14 Bytes Data Frame: 34 Bytes + Network Layer Packet Size RTS CTS Data ACK Data Sleep ModeListen Mode ABC PowerPower Time Wakeup Time Cycle Time Sleep Time Duty Cycle = (Wakeup Time) / (Cycle Time)

8. = n Scheduled MAC Protocol TDMA-Wakeup (TDMA-W) S-Slot W-Slot Channel Access Protocol  Incoming Counter  Outgoing Counter Implementation Details No use of Self Organization Perfect Synchronization Cycle Length – 1 sec Slot Time – 13.6 msec 72 Slots per TDMA Cycle Counter – 2, 4, 6 Frame Sizes: Wakeup Frame: 20 Bytes Data Frame: 34 Bytes + Network Layer Packet Size S1S2W1W2 S1S2W1W2W1W2 W1W2 Sleep State Wakeup State Wakeup Frame Data Frame S1S2 S1S2 Node 1 Node 2 Outgoing Counter[2] Incoming Counter[1]

9. Network Layer – Energy Aware Routing Protocol Destination-initiated Reactive Protocol Multiple Paths between Source and Destination Path Probabilistically chosen at each hop Probability function of Cost Metric Cost Metric function of Residual and Transmission Energy C ij = e ij α R i -β Setup Phase Data Communication Phase Route Maintenance Phase Implementation Details α = 0; β = 1, 10, 100 Packet Sizes  Route Request: 32 Bytes  Data: 32 Bytes + Application Layer Message Size Source Destination B D C A E

10. Simulation Model 120m Destination Node Source Node 20 m

11. Extended LSU SensorSimulator3.1 in OMNeT ++ Basic Structure  Simple Modules – Protocol Layers – Hardware Components  Compound Modules – Sensor Nodes  System Module – Network Simulation Design  Coordinator Module  Protocol Stack – Application, Network, MAC and Physical Layer  Hardware Components – Battery, Radio and CPU  Wireless Channel Module

12. Sensor Node Hardware Components Protocol Stack Application Layer – Light Sensor sending after fixed interval Network Layer – Energy Aware Routing β = 1, 10, 100 MAC Layer – S-MAC TDMA-W 3%, 5% Counter = 2, 4, 6 Physical Layer – No attenuation Battery Voltage Radio Data Rate SLEEP Current IDLE Current TRANSMIT Current RECEIVE Current 3V40 kbps5 μA4.5 mA8.25 mA4.5 mA

13. Experiments and Results

15. Conclusions