Wireless Multimedia Sensor Networks

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Wireless Multimedia Sensor Networks

  1. 1. Real-time Multimedia Monitoring inLarge-Scale Wireless Multimedia Sensor Networks: Research Challenges Joint work by: M.Cesana, A.Redondi – Politecnico di Milano N. Tiglao, A. Grilo – INESC-ID/INOV/IST J. M. Barcelo-Ordinas, M. Alaei – Universitat Politecnica de Catalunya P. Todorova – Fraunhofer FOKUS
  2. 2. MWMSN Project  Multi-tier Wireless Multimedia Sensor Networks  Goal: To enable support for enhanced monitoring and tracking applications through multimedia visual/audio wireless sensor nodes NGI 2012, Karlskrona, Sweden 2
  3. 3. Outline  Introduction  Real-time multimedia monitoring applications  Efficient delivery of visual data in WMSNs  MAC Layer  Network Layer  Transport Layer  Research challenges and final discussion NGI 2012, Karlskrona, Sweden 3
  4. 4. Introduction  WSN equipped with multimedia sensors give birth to WMSN.  They enable a new class of monitoring applications, but demanding in terms of:  computational resources  energy resources  Need for innovative solutions:  combination/optimization techniques at the different layers of the protocol stack NGI 2012, Karlskrona, Sweden 4
  5. 5. Real-Time Multimedia Monitoring  Supervised monitoring (Image/Video-based)  Delivery of compressed image/video flows, analyzed by a human operator  Low bitrate achievable with complex encoders (e.g. H.264/AVC), not supported by WMSN  Suitable solutions: Object-based approaches, Distributed Video Coding  Challenge: Successful implementation of these techniques NGI 2012, Karlskrona, Sweden 5
  6. 6. Real-Time Multimedia Monitoring  Unsupervised monitoring (Feature-based)  Use visual features to describe the underlying pixel content  Suitable for a broad range of monitoring tasks (e.g., object recognition, face detection…)  Main challenges:  Coding of visual features  Low-complexity feature extraction algorithms  Rate-accuracy models for resources allocation NGI 2012, Karlskrona, Sweden 6
  7. 7. MAC Layer  Main requirements for video streaming over WMSN:  Steady-flow of information  Delay-bounded delivery of packets  As a consequence, the MAC layer has to:  support reliable communication  be QoS-aware  save as much energy as possible NGI 2012, Karlskrona, Sweden 7
  8. 8. MAC Layer – available solutions  Available solutions to tune QoS metrics:  Power control  Traffic class differentiation (Q-MAC)  Contention-free vs. contention-based approaches  Duty-cycling control  Queuing and scheduling mechanisms  Error control mechanisms  For WMSN, most important features are:  Intra/Inter-node traffic class differentiation  Node synchronization (duty-cycling control) NGI 2012, Karlskrona, Sweden 8
  9. 9. MAC Layer – available solutions NGI 2012, Karlskrona, Sweden 9
  10. 10. Network Layer: Routing Traditional solutions for WSN focused on energyconsumption In the WMSN case, need also for real-timedelivery Desirable features  Traffic differentiation and joint-optimization of multiple QoS goals  Resource balancing  Fast adaptation to change in monitoring conditions  Support to in-network processing / cross-layer opt.  Scalability  Energy-harvesting awareness NGI 2012, Karlskrona, Sweden 10
  11. 11. Network Layer – available solutions NGI 2012, Karlskrona, Sweden 11
  12. 12. Transport Layer Similarly to the network layer case, availablesolutions are not suitable for WMSN. Design guidelines  Differentiated reliability  Trade-off between reliability/timeliness  Media-centric collaborative reliability  Congestion control  Cross-layer optimization NGI 2012, Karlskrona, Sweden 12
  13. 13. Transport Layer – available solutions NGI 2012, Karlskrona, Sweden 13
  14. 14. Collaborative Sensing in WMSN Multimedia nodes are characterized by adirectional sensing model (FoV) They can be grouped basing on their commonsensing coverage Several challenges  Directional coverage  Clustering / Scheduling  Collaboration protocols NGI 2012, Karlskrona, Sweden 14
  15. 15. Conclusions and Research Challenges Application Layer (feature-based):  Novel coding techniques  Practical implementations MAC Layer  Service differentiation  Dynamic duty-cycling control Network Layer:  In-network processing  Energy harvesting Transport Layer  Media-centric reliability  Cross-layer optimization with routing NGI 2012, Karlskrona, Sweden 15
  16. 16. Thank your for your attention! NGI 2012, Karlskrona, Sweden 16
  17. 17. Project Members  M. Cesana, A. Redondi – {cesana, redondi}@elet.polimi.it  Multimedia coding, Application  N. Tiglao, A. Grilo – {nestor.tiglao, antonio.grilo}@inesc-id.pt  Routing and Transport  J. M. Barcelo-Ordinas, M. Alaei – {joseb,malaei}@ac.upc.edu  MAC Layer  P. Todorova – petia.todorova@fokus.fraunhofer.de  Collaborative Sensing NGI 2012, Karlskrona, Sweden 17

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