1. BeamStar: A New Low-cost Data Routing Protocol for Wireless Sensor Networks Shiwen Mao and Y. Thomas Hou The Bradley Department of Electrical and Computer Engineering Virginia Tech, Blacksburg, VA 24061 Email: smao@vt.edu, thou@vt.edu Speaker : Ching - Chung Lin Globecom 2004

2. Outline  Introduction  Assumption  BeamStar routing protocol  Practical implementation  Conclusion

3. Introducion  Characteristics are desirable for a routing protocol  Scalability  Low complexity  Energy-efficiency  Error-resilience

4. Introducion  Goals of the routing protocol  minimum control overhead  shift the control and management to base station  Components of the routing protocol  Base station-assisted location discovery  Location-aware data forwarding

5. Assumption Base Station(s) ： Sensor node(s) ：

6. Assumption  BeamStar requires the entire sensor network be within the maximum transmission range of the base station

7. BeamStar (Base station-assisted location discovery)  A node’s location is determined by 1. the directionality of the last base station transmission (Sector Number SN) 2. lowest power level information that it can receive from the base station (Ring Number RN)  We define the Location by {SN,RN}

8. BeamStar (Base station-assisted location discovery) 1 2 3 45 1 2 3

9. ( 1, 1 ) ( 1, 2 ) ( 1, 3 ) ( 2, 1 ) ( 2, 2 ) ( 2, 3 ) ( 3, 1 ) ( 3, 2 ) ( 3, 3 ) ( 4, 1 ) ( 4, 2 ) ( 4, 3 )

10. BeamStar (Base station-assisted location discovery) The packet format of a control message from the base station.

11. BeamStar (Location-Aware Data Forwarding)  The header fields are:  BaseID ： the identifier of the destination base station  SourceLocID: the location identifier, i.e., {RN, SN}, of the source sensor node.  LastRelayLocID: the location identifier of the last sensor node that forwarded this data packet  PacketSeqNumber: the sequence number of the packet  each node also maintains a sequence number table

12. { 1, 3} { 2, 4} { 2, 3} { 3, 3} { 2, 2} BeamStar (Location-Aware Data Forwarding) { 3, 2} { 1, 2} { 3, 1} { 1, 1} { 2, 1}

13. BeamStar (Location-Aware Data Forwarding)  There are many advantages of using this routing scheme.  the intermediate sensor nodes do not need to store a routing table or maintain flow-state related information.  the storage requirement is also minimal.  the routes to the base station are loop-free  data packet is forwarded by multiple nodes through different routes

14. Practical implementation  A. Wake Up On-Demand  B. Query for Events  C. Creating Finer Regions  D. Deploying Multiple Base Stations  E. Reallocation and Reorganization

15. Practical implementation  A. Wake Up On-Demand  To further conserve energy, we can put the sensor nodes to a “sleep” state after the initialization phase  the dual radio design can be used to awake a sleeping sensor.  This wake up on-demand scheme is especially useful for sensor networks that monitor rare events

16. Practical implementation  B. Query for Events : sleep mode

17. Practical implementation  C. Creating Finer Regions

18. Practical implementation  D. Deploying Multiple Base Stations A B (3,2) { 2, 3 }

19. Practical implementation  D. Deploying Multiple Base Stations AB (3,2) { 3, 2 }

20. Practical implementation  E. Reallocation and Reorganization

21. Conclusions  BeamStar protocol  Scalable  energy efficient  error-resilient routing

22. Thank you

23.  Ad hoc sensors

24. BeamStar (Location-Aware Data Forwarding)

26. Practical implementation  D. Deploying Multiple Base Stations A AB B (2,3) (3,2)