1. SELF-ORGANIZING MEDIA ACCESS MECHANISM OF A WIRELESS SENSOR NETWORK AHM QUAMRUZZAMAN

2. Sensor Networks Composed of large number of sensor nodes. Nodes are able to communicate in short distance Limited energy Limited storage, processing power Multi-hop topology

3. Application Useful to extract and monitor data Randomly deployed for military surveillance Widespread environmental sampling Health monitoring

4. Important Issue Power conservation and management are most important factors Quality of service and bandwidth efficiency are secondary issue An improved low-power scalable self- organization protocol will be desirable

5. Sensor Network Challenges Major drawback- limited energy Topology changes very frequently Hardware design challenge Scalability Prone to failure Broadcast communication Cost

6. Sensor Network vs. other Wireless Network A cellular network – composed of stationary and mobile nodes. – The network has infrastructure – The base station has unlimited power – The base station covers a wide range – Main objective- quality of service with high bandwidth

7. Sensor Network vs. other Wireless Network Mobile ad hoc Network (MANET) – Peer-to-peer network – Consists of 10 to 100 nodes – Main objective- quality of service – Energy resource is secondary important

8. Sensor Network vs. other Wireless Network Bluetooth technology – Enables wireless link among electronic devices – One master and can support up to seven devices within its network to form a piconet – All nodes are synchronized to master – Low power and low data rate – TDMA protocol

9. Sensor Network vs. other Wireless Network Sensor network is different from all of these networks – Main objective- power management – It may have a much larger of nodes – Transmission power and radio range are much less than Bluetooth and MANET – Mobility rates are much slower than MANET

10. Media Access Control (MAC) Self-organization capability – Ability of the system to function properly without human assistance – It enable nodes to coordinate among themselves to achieve a large sensing task with little energy usage

11. Media Access Control (MAC) Transmission Media: – Optical Media – Infrared – Radio Channel access is done by two different methods: – Contention based protocol – TDMA based protocol

12. Media Access Control (MAC) Nodes power saving technique – Letting the nodes sleep whenever possible – Nodes go into the idle mode when it has nothing to do – Idle node consumes the same energy as the active node – Proper choice of protocols will be able to turn off and on the radio when necessary

13. Media Access Control (MAC) Scalability of nodes Error control – Forward Error Correction (FEC) – Automatic Repeat Request (ARQ)

14. Traditional MAC Protocols CSMA Scheme MACA and MACAW CSMA with collision detection and Slotted ALOHA IEEE 802.11 Bluetooth based protocol

15. Current Survey of MAC Protocol for Wireless Sensor Network Sohrabi and Pottie proposed S (Stationary)- MAC – TDMA based protocol – Power conservation achieved by using random wakeup schedule and by turning off the radio during idle times. – Limitation: low bandwidth utilization

16. Current Survey of MAC Protocol for Wireless Sensor Network Adaptive transmission control (ARC) proposed by Woo and Culler – In ARC mechanism, node periodically attempts to inject the packet. – If the packet is not injected successfully, it signals that the road is jammed. – So the node can reduce the transmission rate.

17. Current Survey of MAC Protocol for Wireless Sensor Network DE-MAC, distributed energy-aware protocol – treats the critical nodes differently – Criticality depends on the relative energy levels within the neighboring nodes. – Protocol performs a local election process to select the weaker nodes and make them sleep. – Low energy nodes sleep more than high energy nodes and increases energy saving.

18. Current Survey of MAC Protocol for Wireless Sensor Network Sensor MAC protocol proposed by Heidemann and Estrin – Nodes go into periodic sleep. – During the sleep, nodes turn off the radio – Also sets the nodes sleep during the transmission of other nodes – To prevent collision and overhearing, it uses 802.11 contention based mechanism (RTS/CTS)

19. Comparative Performance MAC Protocol Media Access Mode Power Saving technique Limitations Stationary MAC TDMARandom wake up schedule during connection phase and by turning off the radio during idle time Low bandwidth utilization ARC (Adaptive Transmissi on Control Scheme) Contention Based By constant listening and random delay Emphasize on fair bandwidth allocation to all nodes rather than saving on energy nodes

20. MAC Protocol Media Access Mode Power Saving Technique Limitations DE-MACTDMABy selecting critical nodes and let the critical nodes to sleep more than neighbor nodes Protocol does not treat all nodes equally Sensor MAC Contention based. Nodes go into periodic sleep by turning off the radio Latency increases

21. Conclusion Many important research questions remain regarding prolong lifetime of nodes Current error detection control scheme are not enough Future research must satisfy fault tolerance, scalability, cost, hardware, topology change and power consumption.

22. THANK YOU