1. Batch Forwarding in Wireless Sensor Networks (WSNs)
Presented by Drew Wichmann
Paper by Turgay Korkmaz

2. Wireless Sensor Networks
Monitor Environment
Collect and/or aggregate sensory data
Send data to a base station

3. Forwarding Schemes Streaming Batch Forwarding
Receive message, forward to next node
Batch Forwarding
Accumulate data, then forward to next node

4. Batch Forwarding Messages consist of Header (H) and Data (D) bytes
Streaming
Receive: m (H + D)
Send: m (H + D)
Batch
Send: H + m D

5. Batch Size
Static
Based on known load level
Dynamic
Timeout-based

6. Advantages of Batch Forwarding
Easy to concatenate data
Uses contention-based MAC protocol
Batch forwarding allows relay node to send most (if not all) data
Lightly loaded system increases delay due to batch formation
Doesn’t require aggregation

7. Analytical Results

8. Efficiency

9. Maximum Efficiency

10. Delay Performance Propagation Delay Transmission Delay
Processing Delay
Queuing Delay

11. End-to-End Delay
Pattern I
Streaming:
Batch Forwarding:
Pattern II

12. Average End-to-End Delay
di is the end-to-end delay for data from sensor node I
Pattern I:
Pattern II:
Average end-to-end delay
Average delay for Pattern I
Average delay for Pattern II

13. Experiments

14. Setup Sensor Nodes Relay Node Base Station 5 Nodes
D = 12 bytes
5 Nodes
Relay Node
Streaming, Fixed size, and dynamic batch forwarding
Fixed size: m ∈ [1,9]
Dynamic: Timeout (T) = 16ms, 32ms, 64ms
Buffer Size: 15, 30 messages
Base Station
Synchronize base station and sensor nodes
Determine end-to-end delay

15. Fixed Batch Sizes ∆ - total size of received data
Γ – total time to receive ∆ amount of data
R = 250 Kbps

16. Fixed Batch Sizes
Delivery Ratio (DR)

17. Fixed Batch Sizes
End-to-End Delay

18. Dynamic Batch Forwarding
Relay Node sets timer
T = 16ms, 32ms, 64ms

19. Dynamic Batch Forwarding
End-to-End Delay

20. Conclusion Analyzed performance of batch forwarding in WSNs
Verified analysis with experimentation
Best performance for dynamic batch forwarding

21. Questions?