1. AN EFFICIENT TDMA SCHEME WITH DYNAMIC SLOT ASSIGNMENT IN CLUSTERED WIRELESS SENSOR NETWORKS Shafiq U. Hashmi, Jahangir H. Sarker, Hussein T. Mouftah and Nicolas D. Georganas IEEE Globecom 2010 1

2. OUTLINE Introduction Related work Goals Network environment Network model Dynamic slot assignment scheme Traffic Model with correlated connection arrival Energy model for DSA Simulation Conclusion 2

3. INTRODUCTION Energy conservation is one of the primary goal for wireless sensor networks(WSNs). The major cause of energy wasting is idle listening. 3

4. INTRODUCTION Contention – based TDMA – based High energy efficient Need Synchronization Not easy dynamically change the frame length 4

5. RELATED WORK Bit-Map-Assisted(BMA) MAC Protocol Sensor nodes transmit data to the cluster head, only if significant events are observed. It reduces the energy wastes due to idle listening in low activity network. 5

6. RELATED WORK Disadvantage BMA keeps the same frame size, keeping an idle period in the frame for inactive sensors, which wastes the bandwidth 6

7. GOALS Design a MAC protocol Reduce the energy loss in the data transmission phase Minimize the wastage in channel bandwidth 7

8. NETWORK ENVIRONMENT Assumption A large number of sensor nodes in a single cluster area There are two channels One channel is used for control signaling The other channel for data traffic The arrival of connection requests is assumed to be correlated Poisson distribution 8

9. NETWORK MODEL Basic framework 9

10. NETWORK MODEL Control packet exchange(based on slotted ALOHA) S header Request ACK Signal channel Data channel 10

11. NETWORK MODEL Control packet exchange S header ACK Signal channel Data channel 11

12. DYNAMIC SLOT ASSIGNMENT SCHEME (DSA) λ: the first connection–request arrival rate v: the number of slots in signaling channel R: probabilities of reject B: probabilities of block 12

13. TRAFFIC MODEL WITH CORRELATED CONNECTION ARRIVAL M: the maximum number of connection that can be accepted by a CH in a cluster λ: the first connection request from the sensor nodes arrives at CH with a Poisson arrival process xλ: the second and following request arrive rate x: is a correlation-factor, x≥1 μ: the connection duration of each sensor node ρ: traffic intensity(=sensor data traffic λ/ μ) P(m): the probability that m sensors are connected in a cluster Poisson distribution: 13

14. ENERGY MODEL FOR DSA m ave : the average number of sensor nodes connected out of M possible connection in every frame E tx, E rx : energy consumed by sensor for transmitting and receiving 1byte r: sending a request packet s: receiving the control packet b/ μ: sensor send b bytes data packets on the data channel in 1/ μ consecutive frames E agg : energy for aggregating the same number of packets 14

15. SIMULATION 15

16. SIMULATION Network topology 16

17. SIMULATION EA-TDMA 17

18. SIMULATION 18

19. SIMULATION 19

20. SIMULATION 20

21. SIMULATION 21

22. CONCLUSION In this paper, we have presented the system model and the analytical model of the DSA Energy efficient Channel efficient MAC scheme 22

23. THANKS FOR YOUR ATTENTION ! 23