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Comparative Performance Evaluation of Image Descriptors Over IEEE 802.11b NoisyWireless Networks

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We evaluate the image retrieval
procedure over an IEEE 802.11b Ad Hoc network, operating
in 2.4GHz, using IEEE Distributed Coordination Function
CSMA/CA as the multiple access scheme. IEEE 802.11 is a
widely used network standard, implemented and supported
by a variety of devices, such as desktops, laptops, notebooks,
mobile phones etc., capable of providing a variety of different
services, such as file transfer, internet access et.al. Therefore,
we consider IEEE 802.11b being a suitable technology to
investigate the case of conducting image retrieval over a
wireless noisy channel. The model we use to simulate the noisy
environment is based on the scenario in which the wireless
network is located in an outdoor noisy environment, or in
an indoor environment of partial LOS - Line-of-sight power.
We used a large number of descriptors reported in literature
in order to evaluate which one has the best performance in
terms of Mean Average Precision - MAP values under those
circumstances. Experimental results on known benchmarking
database show that the majority of the descriptors appear to
have decreased performance when transferred and used in such
noisy environments.

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Comparative Performance Evaluation of Image Descriptors Over IEEE 802.11b NoisyWireless Networks

  1. 1. Comparative Performance Evaluation of Image Descriptors Over IEEE 802.11b Noisy Wireless Networks<br />Presented by EvaggelosChatzistavros<br />EvaggelosChatzistavros, Savvas A. Chatzichristofis<br />Georgios Stamatellos, KostantinosZagoris<br />
  2. 2. Retrieval over noisy channel. Why?<br />
  3. 3. Content Based Image Retrieval<br /><ul><li>Any technology that in principle help you to organize digital image archives based on their visual content.
  4. 4. Anything ranging from a simple similarity matching metric to a robust image annotation engine can fall under the purview of CBIR.</li></li></ul><li>IEEE 802.11 Wireless Networks<br />Infrastructure Mode<br />Ad- Hoc Mode<br />
  5. 5. Problems with wireless link<br /><ul><li>Interference: Presence of many different wireless transmitters at the same frequency
  6. 6. Fading: Multiple copies of the same signal reach the receiver
  7. 7. BER: Bit Error Rate, affected by the above factors, has an effect on transmitted data</li></li></ul><li>Configuration of experiments<br />Different channel conditions caused <br />by different BER values, based on <br />Rician fading model<br />
  8. 8. Rician fading<br />
  9. 9. Retrieval scenario 1<br /><ul><li>Two wireless nodes
  10. 10. IEEE 802.11 b, 11Mbps
  11. 11. 200 – 250 m distance between nodes
  12. 12. Transport protocol: UDP– User Datagram Protocol
  13. 13. BER values: 0, 0.001, 0.01, 0.1, 0.17
  14. 14. Descriptor is transferred between nodes
  15. 15. Increased BER values lead to increased number</li></ul> of errors (bits) at the descriptor<br /><ul><li>Retrieval is conducted based on corrupted descriptor</li></li></ul><li>Retrieval scenario 1 (2)<br />
  16. 16. Retrieval scenario 1 – Simulation results<br />MAP over different BER<br />
  17. 17. Retrieval scenario 2<br /><ul><li>Two wireless nodes
  18. 18. IEEE 802.11 b, 11Mbps
  19. 19. 200 – 250 m distance between nodes
  20. 20. Transport protocol: UDP– User Datagram Protocol
  21. 21. BER values: 0, 0.001, 0.01, 0.1, 0.17
  22. 22. Image is transferred between nodes
  23. 23. Increased BER values lead to increased number</li></ul> of errors (bits) at the image<br /><ul><li>Retrieval is conducted based on corrupted image</li></li></ul><li>Retrieval scenario 2 (2)<br />
  24. 24. Retrieval scenario 2 – Simulation results<br />MAP over different BER<br />
  25. 25. N – MAP descriptor values<br />Tradeoff between a descriptor’s size and the degradation<br /> of its performance<br />
  26. 26. Conclusions – Future work<br />
  27. 27. 감사합니다Thank youありがとうΕυχαριστώ πολύ!<br />

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