Sybot: An Adaptive and Mobile Spectrum Survey System for WiFi Networks Kyu-Han Kim, Alexander W. Min,Kang G. Shin Mobicom Twohsien

OUTLINES  Motivations  Architecture  System Prototype  Evaluation  Conclusion

OUTLINES  Motivations  Architecture  System Prototype  Evaluation  Conclusion

Motivations  Limitations of Existing Approaches Accuracy and repeatability Efficiency and flexibility Adaptation and awareness

OUTLINES  Motivations  Architecture  System Prototype  Evaluation  Conclusion

Architecture  Overview of Sybot Periodic and aperiodic monitoring Decomposition Use of spatio-temporal variance Adaptive and controllable monitoring  Adaptive Spectrum Monitoring

Architecture

 Overview of Sybot  Adaptive Spectrum Monitoring Complete Monitoring Selective Monitoring Diagnostic Monitoring

Architecture – Complete monitoring  Building a comprehensive map  Grid size  Temporal variance

Architecture – Selective monitoring  Reference grids  Smallest set  Accuracy

Architecture – Diagnostic monitoring  Detecting abnormal changes  Speculating measurement areas  Exploiting external network monitoring information

OUTLINES  Motivations  Architecture  System Prototype  Evaluation  Conclusion

System Prototype of Sybot – Software Implementation  Mobility control module  Spectrum monitoring module

System Prototype of Sybot – Hardware Implementation  iRobot  RB230 wireless router  Sonar sensor

OUTLINES  Motivations  Architecture  System Prototype  Evaluation  Conclusion

Evaluation  Testbed Setup 12 Aps Long-term: three times a day Short-term: 5-10 times a day Unit grid size: 20in * 30in

Evaluation  Repeatability  Impact of grid size  Reducing the space to measure  Gains form adaptive selection of reference grids  Diagnosis of abnormal spectrum condition

Evaluation - Repeatability

Evaluation - Impact of grid size

Evaluation – Reducing the space to measure

Evaluation – Gains from adaptive selection of reference grids

Evaluation – Diagnosis of abnormal spectrum condition

OUTLINES  Motivations  Architecture  System Prototype  Evaluation  Conclusion

Conclusion  Discussion Multiple Aps Multiple Sybots  Concluding Remarks Three monitoring techniques that significantly reduce the measurement overhead Provide accurate spectrum-monitoring result under dynamic spectrum conditions Determine trade-off between accuracy and efficiency