1. TreeCast: A Stateless Addressing and Routing Architecture for Sensor Networks Santashil PalChaudhuri, Shu Du, Ami K. Saha, and David B. Johnson Department of Computer Science, Rice University IEEE IPDPS 2004 Speaker: Hao-Chun Sun

2. Outline  Introduction  TreeCast Architecture  Stateless Scoped Addressing  Evaluation  Conclusion

3. Introduction -background-  Sensor Networks Sinks, sensor nodes  Small, inexpensive  Low power  Sensing and report sensory data to sink Dense deployment  Tolerating the low quality of sensor nodes

4. Introduction -motivation-  State in the sensors Robustness of the network  Node failure  Temporary wireless failures  Communication pattern Sink floods a query to sensor network and sensor node reply with relative data. A sensor node sends data to sink after sensing without an explicit query.

5. Introduction -related work-  Data centric routing Directed Diffusion Mechanism  Using the interests  gradients  routing info. interests sink

6. Introduction -related work-  Data centric routing SPIN Mechanism  Sensors flood short description and wait for request from sinks. Short description sink

7. TreeCast Architecture  Overview Address Allocation  Address assignment  Tree Construction Tree Maintenance  Parent failure  Node Addition Routing Messages

8. TreeCast Architecture  Address Allocation basic idea Node address has some correlation with  the distance of the node from the sink and  the subtree it belongs to. Node address form  ((0 | 1) b ) k k: level  b: neighbor number 2 b >> N (N: maximum neighbor number) s abc de 00 0111 01100101 k: 0 k: 1 k: 2 b=2

9. TreeCast Mechanism  Address assignment algorithm

10. TreeCast Mechanism  Address assignment algorithm Choose Parent— a Level M Level (M+1) Level (M+2) CONFIRM 1.Source address 2.b value 1.Source address 2.b value 1.k x T wait 1.Strongest signal 2.Random selection 1.k x T wait 1.Strongest signal 2.Random selection

11. TreeCast Mechanism  Address assignment algorithm Do Allocation— a Level M Level (M+1) Level (M+2) CONFIRM 1.Source address 2.b = 2 1.Source address 2.b = 2 1.random b-bit number 2.concatenate with parent address 1.random b-bit number 2.concatenate with parent address (10) (01) (11) (1110) PROBE 1.Source address 2.Random tag 1.Source address 2.Random tag COMPLAINT APPROVE

12. TreeCast Mechanism  Address assignment algorithm Hear Allocation— a Level M Level (M+1) Level (M+2) CONFIRM 1.Source address 2.b = 2 1.Source address 2.b = 2 Check address (10) (01) (11) (1110) PROBE 1.Source address 2.Random tag 1.Source address 2.Random tag COMPLAINT APPROVE

13. TreeCast Mechanism  Tree Construction Property: 1.A node know own level 2.A node know its parent’s address Property: 1.A node know own level 2.A node know its parent’s address

14. TreeCast Mechanism  Tree Maintenance Parent failure New nodes b a s e f g h d k j i l m n c Do Allocation CONFIRM PROBE COMPLAINT APPROVE Orphan node

15. TreeCast Mechanism  Routing Messages Sink floods a query to sensor network.  Broadcast Tree Orphan: forward all unique query packets. Sensor node sends sensory data to sink.  Every node sends to its parent and parent forwards the packets. K level Orphan:  (K-1) level any parent (ANY PARENT flag)  K level any other node (LATERAL flag)

16. Stateless Scoped Addressing  A subset sensors query A particular geographical area A particular attribute  Reinforcement Learning First time—  Sink sends a query with flooding.  Sensor node response relative data and its own address. Once the sink knows the relevant sensors, it can direct the query to only the nodes.

17. Stateless Scoped Addressing  Address Aggregation Set Approximation 111001111010111000111011 1110

18. Stateless Scoped Addressing  Address Aggregation Set Approximation—Threshold based  (n / N)  n: Number of nodes in subtree rooted in children nodes which did not respond to this query  N: Number of nodes in the subtree rooted at this node 45/60

19. Stateless Scoped Addressing  Address Aggregation Address Coalescence  Basic delta compression technique (1.2.3.4.5.6.7.8) (1.2.3.4.6.7.8) (1.2.3.5.6.7) (1.2.3.4.5.6.7.8), (5,6.7.8), (4,5.6.7)

20. Stateless Scoped Addressing  Address Aggregation Address Coalescence  Basic delta compression technique (1.2.3.4.5.6.7.8) (1.2.3.4.6.7.8)(1.2.3.5.6.7) [(1.2.3.4.5.6.7.8), (5,6.7.8), (4,5.6.7)] [(1.5.4.3.2.3.4), (6,4)] E (1.5.4.3.2.3.4) (1.5.4.3.2.4)

21. Stateless Scoped Addressing  Query Optimization (1.2.3.4) (1.2.3.5) [(2.4.1.4.5),(3,2.4.5)],[…………],….., [(1.2.3.4.5.6.7.8), (5,6.7.8), (4,5.6.7)] (1.2.3)[(1.2.3.4.5.6.7.8), (5,6.7.8), (4,5.6.7)] (1.2.3.3)(1.2.3.1) [(1.2.3.4.5.6.7.8), (5,6.7.8)][(1.2.3.5.6.7.8)]

22. Evaluation  Ns-2 simulator  Network size:1000m x 1000m  Nodes number: 200  Nodes deployment: uniform random distribution  Radio transmission range: 125m (avg. density: 10 nodes per transmission area)

23. Evaluation  Simulation Parameters Parameter NameParameter Value Number of runs10 Timeout to wait for probable parents 12s Bits per level8 (2 8 address per level)

24. Evaluation  Scenario 200 nodes, 1000m x 1000m

25. Evaluation  Generated Tree

26. Evaluation  Levels assigned to nodes with increasing distance from sink

27. Evaluation  Reachability of sensor nodes under node failures

28. Conclusion  It has been presented a novel way to auto-configure a deployment of sensor network.  Unique address allocation lets routing messages becomes stateless and trivial.  It has been presented a stateless addressing scheme for addressing a specific group of sensors using reinforcement learning, thus decreasing message overhead.