1. A Survey on Energy Efficient MAC Protocol for Wireless Sensor Networks Huma Naushad

2. Sensor Networks Sensor nodes are low cost, low power, multifunctional electronic devices. Small in size Wireless communication over short distances. Sensors have Sense, data processing and communicating components. A sensor network is composed of densely deployed sensor nodes.

3. Applications Military military command, control, communications, computing intelligence, targeting systems. Health monitor patients, assist disabled patients. Others managing inventory, monitoring product quality, monitoring disaster areas.

4. Protocol Stack Physical layer addresses simple but robust modulation, transmission and receiving techniques. Data Link Layer -Is responsible for multiplexing of data streams, data frame detection, medium access and error control. -Medium access control MAC a sub-layer. Network Layer routes data supplied by transport layer.

5. Protocol Stack Transport Layer maintains flow of data Application Layer depends on sensing tasks Power Management Plane manages how sensor node uses its power

6. Protocol Stack Mobile Management Plane detects and registers node movement Task Management Plane balances and schedules sensing tasks given to a specific region

7. Power Consumption Wireless sensor node is an microelectronic device can be equipped with limited power source. Replenishment of power resource might be impossible, sensor lifetime shows a strong dependence on battery lifetime. Power consumption is divided into 3 domains -Sensing -Communicating -Data processing.

8. Energy efficiency in MAC protocols Major sources of energy waste Collision Idle listening Overhearing Control packet overhead

9. Schedule based protocols Time slots are pre-allocated on the bases of time, code or frequency to individual nodes Examples -LEACH - Sohrabi & Pottie - Bluetooth. Energy conservation -Collision free - low duty cycle operation -overhearing avoidance. Disadvantages -time slots are wasted -not flexible to changes - lack peer to peer communication.

10. Contention based protocols Common channel is shared between nodes Examples -MACA - MACAW Energy conservation -Piconet -PAMAS - IEEE 802.11 Disadvantages -Idle listening - collision.

11. Energy efficient MAC protocols SMAC TMAC TRAMA Power efficient System Cluster Based energy efficient scheme

12. Proposal Study some of the classic and state of the art energy efficient protocols for wireless sensor networks. The survey article would capture their comparative study and any room for further improvements.