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C urrent research work and plans

COST 286 Electromagnetic Compatibility (EMC) in Diffused Communications Systems Wrocław, 17-18 September, 2003. C urrent research work and plans. Zbigniew M. Jóskiewicz . Wroclaw University of Technology Institute of Telecommunication and Acoustics

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C urrent research work and plans

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  1. COST 286 Electromagnetic Compatibility (EMC) in Diffused Communications Systems Wrocław, 17-18 September, 2003 Current research work and plans Zbigniew M. Jóskiewicz Wroclaw University of Technology Institute of Telecommunication and Acoustics Wybrzeże Wyspiańskiego 27, 50-370 Wrocław, Poland tel. +4871 3203641, fax. +4871 3223473 e-mail: zbigniew.joskiewicz@.pwr.wroc.pl

  2. Our experience For many years Institute of Telecommunication and Acoustics does research in following fields: • Electromagnetic compatibility of devices and systems • Measurements in accredited EMC laboratory (EN 17025) • Development of new test and measurement methods • Telecommunication (esp. radiocommunication) systems • Planning of radiocommunication systems • Modelling of radiowave propagation • Coexistence and compatibility analysis of radiocommunication systems • Testing of telecommunication systems (incl. field tests) • Measurements of EM fields radiated by communication systems and EM disturbances affecting radiocommunication systems

  3. Laboratorytestsandmeasurements • EMI (conducted and radiated) measurements, • tests of electromagnetic immunity, • measurements of the effectiveness of electromagnetic shielding, • measurements of coaxial cables parameters, • measurements of cable television equipment, • other typical telecommunication measurements.

  4. CERTIFICATE Laboratory has a Certificate issued by“Polish Centre For Accreditation” and a Certificate of Assessment issued by “Technology International (Europe) Ltd”. This approval is granted for specifications implementing the EU Directives on EMC.

  5. Examples of completed project(communication systems) Analysis of intersystem compatibility of: • Radio Local Loop systems (2.4 GHz i 3.5 GHz ) and cordless telephony with DECT air interface • Radio Local Loop systems (2.4 GHz i 3.5 GHz ) and mobile telecommunication systems (GSM, UMTS) • LMDS (Local Multipoint Distribution Systems) and UMTS with requirements for systems installations in case of base stations collocation • VSATs and other communication systems (coordination procedures with civil aviation systems)

  6. Current research • Optimisation of measurement method for monitoring of the electromagnetic environment • Monitoring of the communication systems electromagnetic environment • Analysis of intersystem compatibility of RLL systems with CDMA2000 air interface and other communication systems • Electromagnetic compatibility in wireless networks

  7. Monitoring of the electromagnetic environment EM fields must be known in order to: • find sources of disturbances • estimate the possible disturbance level on other system and services • improve spectrum management and planning of communication systems • avoid problems during new communication systems activation (controlling of EM environment before system installation)

  8. Monitoring of the electromagnetic environment (2) • The electromagnetic environment in which the diffused communications system operates is complex and dynamic. • Measurement method has to take into account complexity and dynamic character of EM field (in frequency and time domain)

  9. Monitoring of the electromagnetic environment (3) • In our Institute the measurement method and set-up with special computer programs (to control EMI receiver, to review and statistical analysis of measurement results) have been developed • Since 1999 many measurements (also for operators of radiocommunication system) have been done • The method is being improved • New computer program will be written

  10. Measurement set-up Measurement set-up should be as simple as possible and should enable measurement of EM fields in frequency and time domain Mobile Fixed Antenna Antenna IF + DC IF RF EMI receiver RF EMI receiver

  11. Measurement requirements • Long-term measurements are required (without maxhold function) • EMI receiver must be used because of possible non-linear effects (intermodulation) in spectrum analyzers • Frequent measurements (every few seconds) with recording each measurement results for duplex bands • Measurement in location of base station and user’s terminals • Proper selection of EMI receiver settings (input attenuator, frequency bands, duplex frequency, resolution bandwidth ect. ) to obtain required sensitivity and measurement time • For measurements should be used antenna of radiocommunication system or antenna with similar technical parameters • Statistical analysis of measurement results must be done

  12. Example of statistical analysis of measurement results Signal level (RBw=30 kHz) in frequency domain (upstream) - azimuht 180 (2001.07.24-25) Max level Min level Avg level Signal level [dBm] Frequency [MHz]

  13. Example of statistical analysis of measurement results Signal level (RBw=30 kHz) in frequency domain (downstream) - azimuht 180 (2001.07.24-25) Max level Min level Avg level Signal level [dBm] Frequency [MHz]

  14. Example of statistical analysis of measurement results - radio channel utilization Signal above – 100 dBm level in radio channel [% of time] Channel number Signal above – 100 dBm level in radio channel [% of time] Channel number

  15. Example of statistical analysis of measurement results- freqency utilization Signal above – 100 dBm level [% of time] Frequency [MHz]

  16. The reason of disturbances – operator changes radio channel Signal level (RBw=30 kHz) in frequency domain (upstream) - azimuht 135 (2002.08.05) Max level Min level Avg level Signal level [dBm] Frequency [MHz] Example

  17. The reason of disturbances – spurious emission Signal level (RBw=30 kHz) in frequency domain (downstream) - azimuht 135 (2002.08.05) Max level Min level Avg level Signal level [dBm] Frequency [MHz]

  18. The reason of disturbances – unknown interference with changing frequency Maximum measured values of signal level Signal level [dBm] Frequency [MHz] Example

  19. Our plans This year we plan to build reverberation chamber – the first reverberation chamber in Poland • Room is ready to install the chamber • tender is under consideration

  20. Future research work • Development of measurement methods (emission and susceptibility) of devices and communication systems above 1 GHz in reverberation chamber • Electromagnetic compatibility aspects in wireless networks (esp. WLAN) and existing communication systems (for new services) and new systems

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