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Cognitive Radio System Testbed Demonstration

Cognitive Radio System Testbed Demonstration. Dr. Kyutae Lim (ktlim@ece.gatech.edu) Associate Director of Technology Georgia Electronic Design Center, www.gedcenter.org Georgia Institute of Technology. Cognitive Radio Testbed Overview. Cognitive Radio Testbed.

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Cognitive Radio System Testbed Demonstration

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  1. Cognitive Radio System Testbed Demonstration Dr. Kyutae Lim (ktlim@ece.gatech.edu) Associate Director of Technology Georgia Electronic Design Center, www.gedcenter.org Georgia Institute of Technology

  2. Cognitive Radio Testbed Overview

  3. Cognitive Radio Testbed • Cognitive Radio Testbed was built in Georgia Electronic Design Center, Georgia Tech, Atlanta, GA. • Perform the real time demonstration of various operations in CR system. • Perform the industrial level of evaluation for PHY/MAG and Sensing Technologies. • CR Testbed has flexibility in H/W and S/W. • Testbed configuration and test procedure can be set by WG and Tiger team. • We hope CR testbed to contribute for forging IEEE 802.22 Standard.

  4. Equipment Control Component Control Display Control Signal Generation Spectrum Sensing Received sig. Analysis Testbed Control : MATLAB CR Testbed System Configuration Signal Generation Signal Reception TV Antenna DTV Test Receiver AMP Vector Signal Analyzer DTV Sig Gen Spectrum Analyzer Vector Sig Gen Receiver Module ADC : Data Acquisition 4 CH DAC

  5. Broadcast sig. generator Rec. signal spectrum Constellation (OFDMA) Main Control DTV monitor RF receiver module Vector signal analyzer Spectrum Analyzer Vector signal generator DAC/ADC/ Computer Photo of Cognitive Radio Testbed

  6. System Specification

  7. Demo.1 : Cognitive Radio System Concept Purpose : Basic CR operation principle Spectrum Sensing Co-existance of Incumbent and WRAN Interference mitigation Frequency agile operation

  8. Equipment Control Component Control Display Control Signal Generation Spectrum Sensing Received sig. Analysis Testbed Control : MATLAB Testbed Configuration: Demo.1 Signal Generation Signal Reception TV Antenna DTV Test Receiver AMP Vector Signal Analyzer DTV Sig Gen Spectrum Analyzer Vector Sig Gen Receiver Module ADC : Data Acquisition 4 CH DAC

  9. Spectrum Sensing (TV signals only)

  10. WRAN Interferer (overlapped) WiMax signal used as WRAN

  11. OFDMA Constellation / EVM OFDMA communication failed. No constellation. EVM does not meet the criteria

  12. TVs-WRAN Co-Existence (WRAN in vacant channel)

  13. OFDMA Constellation / EVM OFDMA communication working well. Good constellation. EVM meet the criteria

  14. Dynamic Frequency Switching - I- New primary user signal into the WRAN channel -

  15. OFDMA Constellation / EVM Communication failed.

  16. Dynamic Frequency Switching - II- WRAN signal move to another vacant channel -

  17. OFDMA Constellation / EVM Communication in work.

  18. Demo.2 : Evaluation of Spectrum Sensing Technology Purpose : Verifying Various Spectrum Sensing Technologies Generating Spectrum Environment Energy Detection: MRSS Feature Detection: AAC

  19. Equipment Control Component Control Display Control Signal Generation Spectrum Sensing Received sig. Analysis Testbed Control : MATLAB Testbed Configuration: Demo.2 Signal Generation Signal Reception TV Antenna DTV Test Receiver AMP Vector Signal Analyzer DTV Sig Gen Spectrum Analyzer Vector Sig Gen Receiver Module ADC : Data Acquisition 4 CH DAC

  20. Dual Sensing Strategy (presented Mar 06) Begin Sensing Energy Detection for wide band (Analog, RSSI, MRSS, FFT…) Fine/Feature Detection for single channel MAC (Select single channel) Spectrum Usage Database (BS) FFT CSFD Field Sync Optimum Radiometer Spectral Correlation AAC Multi-cycle Detector ATSC Segment Sync occupied? Y End Sensing N

  21. Input Signal Spectrum / Time-domain Waveform

  22. Coarse MRSS

  23. Fine MRSS with Threshold Detection

  24. AAC for OFDM (WLAN 802.11a) Get two clues (due to short and long preamble) !!

  25. An Example of Scheduling Algorithm for DFH WRAN A Channel 1 • A WRAN system maintains two channels (operating channel and candidate channel) • If WRAN BSes can communicate each other to schedule the time switching to the candidate channel, collision can be completely avoided. • Even if collision occurs on the candidate channel, it is only in very short time (about quite time). WRAN B Channel 2 Channel 3

  26. Demo.3 : Evaluation of protecting Incumbent user from WRAN signal Generation of various fading environment DTV Signal quality measurement in Fading Coexistence of DTV and WRAN Signal quality measure for DTV and WRAN

  27. Equipment Control Component Control Display Control Signal Generation Spectrum Sensing Received sig. Analysis Testbed Control : MATLAB Testbed Configuration: Demo.3 Signal Generation Signal Reception TV Antenna DTV Test Receiver AMP Vector Signal Analyzer DTV Sig Gen Spectrum Analyzer Vector Sig Gen Receiver Module ADC : Data Acquisition 4 CH DAC

  28. ATSC Test 1 – Fading (1) • ATSC with Fading channel environment • ATSC • Ch. 39 (center freq: 623 MHz) • Level: -10 dBm • Fading • Rayleigh (Pass loss: 3 dB, freq ratio = 1.00) • EASY3 for DTV test • Number of DTV signals and Fading parameters can be easily adjusted

  29. ATSC Test 1 – Fading (2)

  30. ATSC Test 1 – Fading (3) Signal quality can be measured

  31. ATSC Test 1 – Fading (4)``````````````````````````````````````````````````````````````````````````````````````````````````````````````` ` ` Various graphs enables signal quality analysis for DTV signal

  32. ATSC Test 2 – w/ WiMax (1) • ATSC with Fading plus OFDMA signal to the adjacent channel • ATSC • Ch. 39 (center freq: 623 MHz) • Level: -10 dBm • No fading • WRAN (WiMax signal is used) • Freq: 616.5 MHz, BW: 7 MHz • Level: 0 dBm

  33. ATSC Test 2 – w/ WRAN (2) ATSC • Spectrum WiMax Mask WiMax

  34. ATSC Test 2 – w/ WRAN (3)

  35. ATSC Test 2 – w/ WRAN (4) Signal quality is little bit degraded due to OFDM signal at adjacent channel

  36. ATSC Test 2 – w/ WRAN (5) OFDM signal

  37. ATSC Test 2 – w/ WRAN (6) Still OK! • OFDM (WiMax) performance

  38. Summary • CR Testbed has built in GEDC, Georgia Tech • Maximum H/W flexibility • Full S/W control: MATLAB • Easy to expand for evaluating Sensing, Interference, MAC, PHY … • CR Testbed has been demonstrated • CR Concept and frequency agile operation • Spectrum sensing technology evaluation • Emulation of various fading channel environment • Evaluation of WRAN signal to interfere DTV reception

  39. Suggestion • Realistic spectrum environment can generated repeatedly. • The testbed can be customized to perform various test/evaluation. • The parameters and figure-of-merit can be defined by WG. • Standard procedure for evaluation can be defined by WG. • Let’s use this testbed for standard evaluation platform for PHY and Sensing technology !!!

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