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Sink Deployment in Wireless Surveillance Networks. Michael Chien -Chun Hung , Kate Ching-Ju Lin March 31, 2011. Network and Mobile System Lab(NMS Lab) Research Center for Information Technology Innovation (CITI) Academia Sinica , Taipei, Taiwan. Wireless Surveillance System (WSS).
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Sink Deployment in Wireless Surveillance Networks Michael Chien-Chun Hung, Kate Ching-Ju Lin March 31, 2011 Network and Mobile System Lab(NMS Lab) Research Center for Information Technology Innovation (CITI) Academia Sinica, Taipei, Taiwan
Wireless Surveillance System (WSS) • Meerkat • Panoptes
Camera Deployment • Camera placement • Environment-dependent • Location: where to put? • Angle: how to place ? • Camera management • Application-dependent • Resolution: how to set? • Tracking: how to group?
Wireless Surveillance System Camera Deployment Sink Deployment Camera Placement Camera Management
Sink Deployment: Scenario 1 A 2 Mbps Link reliability: 65% C 54 Mbps Link reliability: 85% B 1 Mbps Link reliability: 50%
Sink Deployment: Scenario 2 • Camera’s demand rate • The sink should be closer to the camera with higher demand • Each camera should utilize the same bit-rate • The sink should have similar distance to all cameras C A 5.5 Mbps Link reliability: 60% 5.5 Mbps Link reliability: 50% B 5.5 Mbps Link reliability: 60%
Sink Deployment • Goal: maximize overall satisfaction of all cameras • di: demand streaming rate of camera i • ui: effective throughput of camera i • Similar to circumcenter in a polygon • Circumcenter may not exist in general case • Exhausted searchis achievable • Enormous deployment-cost
Spring-Cam Approach C dA = 1000 kbps dC = 750 kbps A A C B dB = 1500 kbps Vector Diagram SUM B
Spring-Cam Framework • Step 1: Initialization • Origin (corner) • Central point • Average point • Average point weighted by the camera’s demand • Random • Step 2: Adjustment • Move the sink according to the net force of the mass-spring system
Spring-Cam Framework (Cont.) • Step 3: Termination • When the potential energy cannot be further reduced • Step 4: Advanced search • (x,y): the result of step 3 • Spring-Cam+5 returns the best result within (x ± 5, y ± 5)
Performance Evaluation • Parameters: • 350*350 square meter field • Demand rate between [500, 1000] kbps • Performance metric: • Total Satisfaction : • Hit Ratio: • , Hk =
Total Satisfaction 23% Number of cameras ↑, performance metric ↓ Spring-Cam outperforms average location by 23% Advanced search ↑, performance metric ↑
Hit Ratio Advanced search ↑, hit ratio ↑ Number of cameras ↑, hit ratio ↓
Conclusion • Introducing sink deployment problem • Maximizing the overall satisfaction of all cameras • Proposing Spring-Cam • Locating the sink that satisfies each camera’s demand • Reducing the overhead of exhausted search
Thank You for Your Attendance! Michael Chien-Chun Hung shinglee@citi.sinica.edu.tw http://nms.citi.sinia.edu.tw/shinglee Network and Mobile System Group(NMSGroup) Research Center for Innovation Technology Information (CITI) Academia Sinica, Taipei, Taiwan
Sink deployment • Topology-dependent • Supplementary to camera deployment • Multiple bit-rates supported by IEEE 802.11 • Auto rate-selection based on transmission quality • Distance to the sink significantly affect SNR • 802.11 performance anomaly1 • Huge throughput decrement • Rate selection in WSSs is mutually dependent • 1 M. Heusse, F. Rousseau, G. Berger-Sabbatel and A. Duda, “Performance anomaly of 802.11 b” in INFOCOM’03
System overview • Independent rate selectionfor each camera • The quality of the link between itself and the sink • Multi-path fading、interference、channel fading • Focus on channel fading determined by the distance • The impact of 802.11 performance anomaly • All cameras obtain similar throughput2 • : approximated achievable uploading throughput • pi: link reliability between camera i and the sink • 2 K.-J. Lin and C. fu Chou, “Exploiting multiple rates to maximize the throughput of wireless mesh networks,” IEEE Transactions on Wireless Communications, 2009
System overview (cont.) ≒ • Maximizing equals to minimizing • By AM-GM Inequality Property: • Maximum: when all cameras use the same bit-rate • Bit-rate selection mainly bases on the distance • The sink must have similar distance to all cameras
Spring-Cam in a nutshell • The sink must have similar distance to all cameras • zi: the distance between camera i and the sink • : the average distance of all zi • Similar to mass-spring system in Physics • A virtual spring connecting a camera and the sink • If zi > : the sink should be placed closer to camera i • If zi < : the sink should be placed further to camera i
Spring-Cam Overview • Utilizing mass-spring operations • Virtual spring between the sink and each camera • Demand rate as elasticity coefficient. • Efficient in locating possible position • Promptly converge to a potential point • Supplementary to exhausted search • Reduce search cost