See discussions, stats, and author profiles for this publication at: https://www.researchgate.net/publication/256484371 Device signal strength self-calibration using histograms (Presentation slides) Data · September 2013 CITATIONS READS 0 69 1 author: Christos Laoudias University of Cyprus 89 PUBLICATIONS 1,405 CITATIONS SEE PROFILE Some of the authors of this publication are also working on these related projects: Motive View project All content following this page was uploaded by Christos Laoudias on 20 May 2014. The user has requested enhancement of the downloaded file.
Introduction - Motivation Device Calibration Device Signal Strength Self-Calibration - Device Diversity - Manual Calibration using Histograms Self-Calibration - RSS Histograms - Self-Calibration Method Performance e † and Christos Panayiotou ∗ Christos Laoudias ∗ , Robert Pich´ Evaluation - Measurement Setup - Experimental Results ∗ KIOS Research Center for Intelligent Systems and Networks, University of Cyprus † Tampere University of Technology, Tampere, Finland Conclusions - Concluding Remarks International Conference on Indoor Positioning and Indoor Navigation, Sydney, Australia 15 November 2012
Outline Introduction - Motivation Introduction Device Calibration - Device Diversity - Manual Calibration Device Calibration Self-Calibration - RSS Histograms - Self-Calibration Self-Calibration Method Performance Evaluation Performance Evaluation - Measurement Setup - Experimental Results Conclusions Conclusions - Concluding Remarks International Conference on Indoor Positioning and Indoor Navigation, Sydney, Australia 15 November 2012
Motivation of our work ◮ RSS is intended for determining the signal quality and not for positioning purposes Introduction - Motivation Device Calibration - Device Diversity - Manual Calibration Self-Calibration - RSS Histograms - Self-Calibration Method Performance Evaluation - Measurement Setup - Experimental Results Conclusions - Concluding Remarks International Conference on Indoor Positioning and Indoor Navigation, Sydney, Australia 15 November 2012
Motivation of our work ◮ RSS is intended for determining the signal quality and not for positioning purposes Introduction ◮ Different devices do not report RSS values in the same way - Motivation ◮ The WiFi standard (IEEE 802.11) defines the RSS Device Calibration - Device Diversity Indicator (1 byte integer) for measuring RSS in [0 255] - Manual Calibration ◮ Each vendor’s implementation is limited up to RSSI max Self-Calibration - RSS Histograms ◮ RSSI is mapped to power values in dBm internally by - Self-Calibration Method the device driver (proprietary information) Performance ◮ Even worse: same chipsets may not report the same Evaluation - Measurement Setup RSS values due to different antennas or packaging - Experimental Results Conclusions - Concluding Remarks International Conference on Indoor Positioning and Indoor Navigation, Sydney, Australia 15 November 2012
Motivation of our work ◮ RSS is intended for determining the signal quality and not for positioning purposes Introduction ◮ Different devices do not report RSS values in the same way - Motivation ◮ The WiFi standard (IEEE 802.11) defines the RSS Device Calibration - Device Diversity Indicator (1 byte integer) for measuring RSS in [0 255] - Manual Calibration ◮ Each vendor’s implementation is limited up to RSSI max Self-Calibration - RSS Histograms ◮ RSSI is mapped to power values in dBm internally by - Self-Calibration Method the device driver (proprietary information) Performance ◮ Even worse: same chipsets may not report the same Evaluation - Measurement Setup RSS values due to different antennas or packaging - Experimental Results ◮ Using a new device for positioning is feasible, but the RSS Conclusions values are not compatible with the radiomap - Concluding Remarks International Conference on Indoor Positioning and Indoor Navigation, Sydney, Australia 15 November 2012
Motivation of our work ◮ RSS is intended for determining the signal quality and not for positioning purposes Introduction ◮ Different devices do not report RSS values in the same way - Motivation ◮ The WiFi standard (IEEE 802.11) defines the RSS Device Calibration - Device Diversity Indicator (1 byte integer) for measuring RSS in [0 255] - Manual Calibration ◮ Each vendor’s implementation is limited up to RSSI max Self-Calibration - RSS Histograms ◮ RSSI is mapped to power values in dBm internally by - Self-Calibration Method the device driver (proprietary information) Performance ◮ Even worse: same chipsets may not report the same Evaluation - Measurement Setup RSS values due to different antennas or packaging - Experimental Results ◮ Using a new device for positioning is feasible, but the RSS Conclusions values are not compatible with the radiomap - Concluding Remarks ◮ Best accuracy is guaranteed only if the user carries the same device during positioning, otherwise calibration is required International Conference on Indoor Positioning and Indoor Navigation, Sydney, Australia 15 November 2012
Motivation of our work ◮ RSS is intended for determining the signal quality and not for positioning purposes Introduction ◮ Different devices do not report RSS values in the same way - Motivation ◮ The WiFi standard (IEEE 802.11) defines the RSS Device Calibration - Device Diversity Indicator (1 byte integer) for measuring RSS in [0 255] - Manual Calibration ◮ Each vendor’s implementation is limited up to RSSI max Self-Calibration - RSS Histograms ◮ RSSI is mapped to power values in dBm internally by - Self-Calibration Method the device driver (proprietary information) Performance ◮ Even worse: same chipsets may not report the same Evaluation - Measurement Setup RSS values due to different antennas or packaging - Experimental Results ◮ Using a new device for positioning is feasible, but the RSS Conclusions values are not compatible with the radiomap - Concluding Remarks ◮ Best accuracy is guaranteed only if the user carries the same device during positioning, otherwise calibration is required ◮ Existing calibration methods do not fit well in real-time positioning scenarios International Conference on Indoor Positioning and Indoor Navigation, Sydney, Australia 15 November 2012
Device Diversity Introduction - Motivation Device Calibration - Device Diversity - Manual Calibration Self-Calibration - RSS Histograms - Self-Calibration Method Performance Evaluation - Measurement Setup - Experimental Results Conclusions - Concluding Remarks Source: K. Kaemarungsi (2006) International Conference on Indoor Positioning and Indoor Navigation, Sydney, Australia 15 November 2012
Good News: Linearity between RSS values −20 −20 −30 −30 Mean RSS from Asus eeePC [dBm] Mean RSS from HP iPAQ [dBm] −40 −40 Introduction −50 −50 - Motivation Device Calibration −60 −60 - Device Diversity −70 −70 - Manual Calibration −80 −80 Self-Calibration - RSS Histograms RSS pairs RSS pairs −90 −90 Cloud center Cloud center - Self-Calibration Least−squares Fit Least−squares Fit Method −100 −100 −100 −90 −80 −70 −60 −50 −40 −30 −20 −100 −90 −80 −70 −60 −50 −40 −30 −20 Mean RSS from HTC Flyer [dBm] Mean RSS from Samsung Nexus S [dBm] Performance Evaluation - Measurement Setup - Experimental Results ◮ Manual Calibration : Collect several colocated RSS pairs at Conclusions known locations and estimate the linear coefficients through - Concluding Remarks least squares r (2) r (1) ¯ = α 12 ¯ + β 12 ij ij International Conference on Indoor Positioning and Indoor Navigation, Sydney, Australia 15 November 2012
Good News: Linearity between RSS values −20 −20 −30 −30 Mean RSS from Asus eeePC [dBm] Mean RSS from HP iPAQ [dBm] −40 −40 Introduction −50 −50 - Motivation Device Calibration −60 −60 - Device Diversity −70 −70 - Manual Calibration −80 −80 Self-Calibration - RSS Histograms RSS pairs RSS pairs −90 −90 Cloud center Cloud center - Self-Calibration Least−squares Fit Least−squares Fit Method −100 −100 −100 −90 −80 −70 −60 −50 −40 −30 −20 −100 −90 −80 −70 −60 −50 −40 −30 −20 Mean RSS from HTC Flyer [dBm] Mean RSS from Samsung Nexus S [dBm] Performance Evaluation - Measurement Setup - Experimental Results ◮ Manual Calibration : Collect several colocated RSS pairs at Conclusions known locations and estimate the linear coefficients through - Concluding Remarks least squares r (2) r (1) ¯ = α 12 ¯ + β 12 ij ij ◮ Limited Applicability: (i) User needs to be familiar with the indoor area and (ii) a considerable data collection effort is required International Conference on Indoor Positioning and Indoor Navigation, Sydney, Australia 15 November 2012
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