後卓越計畫進度報告 (2008/1/7)

1. 後卓越計畫進度報告 (2008/1/7) 清華大學 許健平教授 淡江大學 張志勇教授

2. Hybrid Congestion Control Protocol in Wireless Sensor Networks Accepted by the VTC2008-spring

3. Introduction • Congestion occurs in sensor networks • Nodes are densely distributed • Application produces high flow rate • The node which is more close to sink is more easy to congest

4. Hybrid Congestion Control Protocol in Wireless Sensor Networks (HCCP) • Congestion Detection Phase • Data Rate Adjustment Phase

5. Congestion Detection Phase • Prediction congestion for next time period T • Each sensor will count • The current upstream and downstream data rates of neighbors (Net Flow Size, NS) • Remaining buffer size (RB) to predict whether congestion will happen or not at next time period T

6. Congestion Advertisement • Congestion Degree (CD) • Congestion advertisement is triggered • In the beginning of each time period T • The buffer state from light to heavy state Light State RBi>= NSi Heavy State RBi< NSi

7. j i k Data Rate Adjustment Phase • Potential Traffic Capacity • How many packets that the sensor i can hold from upstream neighbors at next period

8. y x z i a b Data Rate Adjustment PhaseTendency Congestion Degree • The degree of congestion probability of x • if the total traffic from x to i is prohibited in a time period T • If αi(x) < 0 • If sensor i suppress the data rate Rx,i , sensor x may congestion at next time period • If αi(x) >= 0 • congestion will not happen at next time period even sensor i suppress the data rate Rx,i CDy CDx CDz Ry,i Rx,i Rz,i

9. NSz = 3 NSy = 1 NSx = 1 RBz = 3 RBy = 2 RBx = 2 CDz = 0 CDy = 1 CDx = 1 NSi = 1 RBi = 0 CDi = -1 CDi<0 represent the node is heavy state Example [Total In Flow Size / Total Out Flow Size] [4/3] [5/2] [3/2] y x z 1 3 1 [5/4] i i PCi = 0 + 4 = 4 2 2 b a