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 Speaker : Ching - Chung Lin Globecom 2004

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

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

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

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

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

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}

BeamStar (Base station-assisted location discovery)

( 1, 1 ) ( 1, 2 ) ( 1, 3 ) ( 2, 1 ) ( 2, 2 ) ( 2, 3 ) ( 3, 1 ) ( 3, 2 ) ( 3, 3 ) ( 4, 1 ) ( 4, 2 ) ( 4, 3 )

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

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

{ 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}

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

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

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

Practical implementation  B. Query for Events : sleep mode

Practical implementation  C. Creating Finer Regions

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

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

Practical implementation  E. Reallocation and Reorganization

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

Thank you

 Ad hoc sensors

BeamStar (Location-Aware Data Forwarding)

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