Speakers                                                          Mr. Reiner Hoppe© 2012 by AWE Communications GmbH       ...
Exposure & ElectromagneticCompatibility© 2012 by AWE Communications GmbH                           www.awe-com.com
Contents       • Introduction       • Coverage vs. Exposure        Analysing the trade off between exposure to electromagn...
Introduction   Regulator Requirements for Ensuring Public Safety       •   To protect humans and nature from electromagnet...
Introduction   Regulator Requirements for Ensuring Public Safety       •   Different thresholds for controlled and uncontr...
Introduction   Regulator Requirements for Ensuring Public Safety       •   Thresholds for exposure derived based on therma...
Introduction   Regulator Requirements for Ensuring Public Safety       •   Different public authorities issued recommendat...
Introduction   Example for Determination of Safety Distance       Radio network                                           ...
Introduction   EMC and the Radiation of Electromagnetic Waves       •   To protect humans and nature from electromagnetic ...
Introduction   Methods for the Exposure Level Assessment       •   Field strength prediction based on RF configuration of ...
Introduction   Inputs for Exposure Level Assessment       •   Site location and height       •   Max. radiated power (EIRP...
Coverage vs. Exposure                                           (1/8)   Analysing the trade off between exposure to electr...
Coverage vs. Exposure                                         (2/8) Coverage:   Field Strength > Threshold (Receiver sensi...
Coverage vs. Exposure                                                  (3/8) Exposure:   Field Strength < Threshold (Healt...
Coverage vs. Exposure                                         (4/8) Summary      40…45 dBµV/m                             ...
Coverage vs. Exposure                                                       (5/8)   Outdoor Coverage                      ...
Coverage vs. Exposure                                                       (6/8)   Indoor Coverage                       ...
Coverage vs. Exposure                                                       (7/8)   Indoor Coverage with increased Tx powe...
Coverage vs. Exposure                                    (8/8)   Analysing the trade off between exposure due to   electro...
Options for Network Design                                          (1/8)   Examining potential options for network design...
Options for Network Design                                                                 (2/8)  Thesis 1:      the highe...
Options for Network Design                                        (3/8)  Thesis 2:   the smaller the cell radius, the lowe...
Options for Network Design                                            (4/8)  Results:      High traffic and capacity deman...
Options for Network Design                                         (5/8)                         Comparison of Electrical ...
Options for Network Design                                                  (6/8)                             Comparison o...
Options for Network Design                                                (7/8)             Comparison of Required Tx Powe...
Options for Network Design                                    (8/8)   Examining potential options for network design – det...
EMC Module in ProMan                                                   (1/4)   Features of EMC module in ProMan       •   ...
EMC Module in ProMan                                                      (2/4)   Features of EMC module in ProMan       •...
EMC Module in ProMan                                                     (3/4)   Features of EMC module in ProMan       • ...
EMC Module in ProMan                                                              (4/4)   Features of EMC module in ProMan...
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Propagation emc

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Propagation emc

  1. 1. Speakers Mr. Reiner Hoppe© 2012 by AWE Communications GmbH http://www.awe-communications.comAPAC Distributor: Firespec Engineering (M) Sdn Bhd http://www.firespec.net
  2. 2. Exposure & ElectromagneticCompatibility© 2012 by AWE Communications GmbH www.awe-com.com
  3. 3. Contents • Introduction • Coverage vs. Exposure Analysing the trade off between exposure to electromagnetic waves and deploying optimal (indoor) coverage • Options for Network Design Examining potential options for network design – determining the suitability of meeting coverage and capacity demands • Features of EMC module in ProMan Definition of exposure limits for different frequency bands Comparison of predictions to specified exposure limits • Sample Scenario Definition of exposure limits for different frequency bands Comparison of predictions to specified exposure limits2012 © by AWE Communications GmbH 2
  4. 4. Introduction Regulator Requirements for Ensuring Public Safety • To protect humans and nature from electromagnetic hazards, the health and safety legislation for the deployment of base stations becomes more and more restrictive • Different public authorities issued recommendations  thresholds for exposure • Different thresholds for controlled and uncontrolled (general public) areas • Distinction of different zones for exposure: - Compliance zone: Potential exposure below limits for both controlled and uncontrolled areas - Occupational zone: Potential exposure below limits for controlled areas, but above limits for uncontrolled (general public) areas - Exceedance zone: Potential exposure exceeds limits for both controlled and uncontrolled (general public) areas Compliance Occupational Exceedance zone zone zone2012 © by AWE Communications GmbH 3
  5. 5. Introduction Regulator Requirements for Ensuring Public Safety • Different thresholds for controlled and uncontrolled (general public) areas • Different accessibility categories require assessment of different heights: - Antenna installed on inaccessible tower (with/without neighbouring building) - Antenna installed on publicly accessible structure (e.g. rooftop) - Evaluation of ground level - Evaluation of rooftop level (floor levels)2012 © by AWE Communications GmbH 4
  6. 6. Introduction Regulator Requirements for Ensuring Public Safety • Thresholds for exposure derived based on thermal effects • Analyzed value: Specific Absorption Rate (SAR) Absorbed power in a human body per mass unit of the body (W/kg) • ICNIRP thresholds (basic limits) from 10 MHz to 10 GHz (safety factor for public protection): Occupational General public Whole body (average SAR) 0.4 0.08 Head and trunk (local SAR) 10 2 Limbs (local SAR) 20 4 • Derived reference levels from 400 MHz to 2000 MHz by ICNIRP (average over time): Occupational General public Electric field strength (V/m) 3*sqrt(frequency) 1.375*sqrt(frequency) • Partly lower national margins (e.g. in Switzerland reduction by factor 10) • Simultaneous exposure to multiple sources: superposition with formula 2  87   i 100kHz  Ei    i 1MHz  Ei EThreshold   1.0 1 MHz 300 GHz 2    f 2012 © by AWE Communications GmbH 5
  7. 7. Introduction Regulator Requirements for Ensuring Public Safety • Different public authorities issued recommendations  thresholds • These recommendations must be fulfilled for each transmitting antenna • Site certificate ensures exposure below threshold outside controlled area Antenna Pattern Environment ca. 2-10m Tx Power few dm Site certificate2012 © by AWE Communications GmbH 6
  8. 8. Introduction Example for Determination of Safety Distance Radio network GSM1800 Height of transmitter above ground in m 23.7 Azimuth orientation of antenna (north over east) 90 Center frequency f in MHz 1855 Antenna type K 735147 Max. transmitter output power per channel Pa in W 6.3 Number of frequency channels n 3 Loss between transmitter output and antenna input a in dB 1 Antenna gain factor Gi in main direction (18 dBi) 63.1 a Total max. power on antenna input P in W 15.01 * * P [W ]  n  Pa 10 10 Electrical field strength threshold for general public areas 59.00 Safety distance in main beam direction in m 2.86** ** 30  P  Gi r EThreshold2012 © by AWE Communications GmbH 7
  9. 9. Introduction EMC and the Radiation of Electromagnetic Waves • To protect humans and nature from electromagnetic hazards, the health and safety legislation for the deployment of base stations becomes more and more restrictive • Different public authorities issued recommendations based on guidelines formulated by the International Committee on Non Ionising Radio Protection (ICNIRP) • These recommendations must be fulfilled for each new transmitting antenna • Thresholds for the radiated electrical field strength for different frequency ranges  analysis must be carried out before installing a base station or transmitter • ProMan accurately predicts the radiated electrical field of antennas  alternative to costly field strength measurements around each antenna • ProMan takes into account the detailed geometrical representation of the environment • Results allow the simple comparison of the superposed radiated field strength levels to the specified exposure limits • Installation of new antennas on locations where already multiple antennas are mounted is more critical concerning the fulfilment of exposure limits due to superposition2012 © by AWE Communications GmbH 8
  10. 10. Introduction Methods for the Exposure Level Assessment • Field strength prediction based on RF configuration of antenna and environment description  lowest effort  possible before deployment  worst case assumption (far field) • Measurement of the electrical field strength on specific locations and extrapolation for full power transmission (max. cell load)  high effort for measurements  depending on individual situation (cell load)  limited reproducibility • Measurement row for grid of locations over larger scenario  highest effort  covering different scenarios  depending on individual situation (cell load)  limited reproducibility  Field strength prediction provides most efficient method2012 © by AWE Communications GmbH 9
  11. 11. Introduction Inputs for Exposure Level Assessment • Site location and height • Max. radiated power (EIRP or Tx power at antenna input) • Carrier frequency / frequency band • Antenna pattern with gain for each direction (3D or vertical and horizontal) • Azimuth orientation of antenna • Antenna downtilt • Description of the environment (buildings, terrain, …)2012 © by AWE Communications GmbH 10
  12. 12. Coverage vs. Exposure (1/8) Analysing the trade off between exposure to electromagnetic waves and deploying optimal (indoor) coverage Coverage: Field Strength > Threshold (Receiver sensitivity) Receiver Sensitivity depending on - thermal noise (bandwidth!) - interference (co-channel, adjacent channel leakage) Exposure: Field Strength < Threshold (Health risks) Threshold depending on - thermal effects - national margins Summary: Field Threshold Strength < Field Strength < Threshold (Receiver sensitivity) (Health risks)2012 © by AWE Communications GmbH 11
  13. 13. Coverage vs. Exposure (2/8) Coverage: Field Strength > Threshold (Receiver sensitivity) Receiver Sensitivity depending on - thermal noise (bandwidth!)  wider bandwidths require higher field strengths for reception P=k*T*B k = Boltzman constant = 1,380 ·10-23 J·K-1 T = absolute temperature (Kelvin) B = bandwidth (Hz) Examples (T = 300K): GSM 900 (200 kHz): P = -120 dBm  E = 16 dBµV/m UMTS FDD (5 MHz): P = -107 dBm  E = 37 dBµV/m - interference (co-channel, adjacent channel leakage)  depending on network layout  optimised layout should keep the interference small  in worst cases approx. a few dB above thermal noise2012 © by AWE Communications GmbH 12
  14. 14. Coverage vs. Exposure (3/8) Exposure: Field Strength < Threshold (Health risks) Threshold depending on - thermal effects Biology responsible for definition of thresholds Analysed value: Specific Absorption Rate (SAR): Absorbed power in a human body per mass unit of the body (W/kg) ICNIRP thresholds: SAR of 4 W/kg in 30 minutes leads to 1 K increase of temperature in body which is the max. Safety factor of 50 for public protection  0.08 W/kg - Thresholds for exposure incl. national margins Germany / EU / ICNIRP Switzerland Linear Logarithmic Linear Logarithmic GSM 900 f = 900 MHz 41 V/m 152,3 dBµV/m 4 V/m 132,0 dBµV/m GSM 1800 f = 1800 MHz 58 V/m 155,3 dBµV/m 6 V/m 135,6 dBµV/m UMTS f = 2140 MHz 61 V/m 155,7 dBµV/m 6 V/m 135,6 dBµV/m2012 © by AWE Communications GmbH 13
  15. 15. Coverage vs. Exposure (4/8) Summary 40…45 dBµV/m 130 dBµV/m Field Threshold Strength < Field Strength < Threshold (Receiver sensitivity) (Health risks) Indoor Max. allowed dynamic range of signal : Problem 85 dB (130 dBµV/m – 45 dBµV/m) Actual dynamic inside buildings due to transmission of walls: Penetration of walls: Concrete wall: L = 20 dB  max. 4 walls can be penetrated to fulfil coverage and EMC aspects  Due to the wall penetration losses the signal inside the building has a high dynamic range and so it is very difficult to fulfil coverage and EMC aspects simultaneously!2012 © by AWE Communications GmbH 14
  16. 16. Coverage vs. Exposure (5/8) Outdoor Coverage (Visualisation of Thresholds) Computation with propagation models of radio network planning tools Threshold ICNIRP Field Strength: 152,3 dBµV/m Threshold Switzerland Field Strength: 132 dBµv/m Threshold Receiver Field Strength: 40..45 dBµV/m GSM 900 cell, frequency: 948 MHz, Tx power: 43 dBm, Antenna gain: 15 dBi, Antenna height: 15 m  EMC thresholds are no problem…but coverage not sufficient everywhere2012 © by AWE Communications GmbH 15
  17. 17. Coverage vs. Exposure (6/8) Indoor Coverage (Visualisation of Thresholds) Computation with propagation models of radio network planning tools Threshold ICNIRP Field Strength: 152,3 dBµV/m Threshold Switzerland Field Strength: 132 dBµv/m Threshold Receiver Field Strength: 40..45 dBµV/m GSM 900 cell, frequency: 948 MHz, Tx power: 43 dBm, Antenna gain: 15 dBi, Antenna height: 15 m Penetration loss: 20 dB  EMC thresholds are no problem…but insufficient indoor coverage2012 © by AWE Communications GmbH 16
  18. 18. Coverage vs. Exposure (7/8) Indoor Coverage with increased Tx power (30 dB !) Computation with propagation models of radio network planning tools Threshold ICNIRP Field Strength: 152,3 dBµV/m Threshold Switzerland Field Strength: 132 dBµv/m Threshold Receiver Field Strength: 40..45 dBµV/m GSM 900 cell, frequency: 948 MHz, Tx power: 73 dBm, Antenna gain: 15 dBi, Antenna height: 15 m Penetration loss: 20 dB  Indoor coverage only sufficient if Tx power is so high that EMC problems occur!2012 © by AWE Communications GmbH 17
  19. 19. Coverage vs. Exposure (8/8) Analysing the trade off between exposure due to electromagnetic waves and deploying optimal (indoor) coverage  Coverage (especially indoor) becomes very often a problem if critical exposure is avoided in outdoor environment (i.e. small Tx power) and if base station density is not very high  Increasing the Tx power is no alternative to guarantee coverage because of exposure thresholds  A detailed planning of the network is mandatory to find a trade off between exposure and (indoor) coverage2012 © by AWE Communications GmbH 18
  20. 20. Options for Network Design (1/8) Examining potential options for network design – determining the suitability of meeting coverage and capacity demands  Indoor coverage is important in cities (potential users/customers)  Generally, in cities antenna heights are not very high because of traffic (and capacity) requirements  the higher the max. traffic density, the smaller the cell radius (max. number of users per cell reduces cell size with increasing traffic)  the smaller the cell radius, the lower the antenna height (shadowing of buildings increases with decreasing antenna heights) Results of previous chapter:  Indoor coverage and EMC exposure can only be combined if the distance between base station and buildings is short  Exposure related: 43..50 dBm Tx output power are maximum if combined with sector antennas with 10..20 dBi gain  Indoor coverage related: Distance between site and building below 800 m2012 © by AWE Communications GmbH 19
  21. 21. Options for Network Design (2/8) Thesis 1: the higher the max. traffic density, the smaller the cell radius (max. number of users per cell reduces cell size with increasing traffic) Example: Assumption: Cell Capacity: 50 user simultaneously, circuit switched traffic (e.g. voice) Case Study: Cell size [km2] Case 1: 6 10 simultaneous users per km2 5  Cell Area: 5 km2 4 Size of cell [km2] 3 Case 2: 2 50 simultaneous users per km2 1  Cell Area: 1 km2 0 10 20 30 40 50 60 70 80 90 100 User per km 22012 © by AWE Communications GmbH 20
  22. 22. Options for Network Design (3/8) Thesis 2: the smaller the cell radius, the lower the antenna height (shadowing of buildings increases with decreasing antenna heights) Tx antenna height: 35 m Tx antenna height: 15 m2012 © by AWE Communications GmbH 21
  23. 23. Options for Network Design (4/8) Results: High traffic and capacity demands can only be achieved with small cells, i.e. low antenna heights Low antenna heights have problems with indoor coverage  Increase the number of cells with a homogenous distribution of the sites in the area to be covered with the mobile network Case Study: Comparison of two different cell layouts: • single (central) omni transmitter location (with 20 W Tx power, 0 dBi antenna gain) • seven (distributed) omni transmitter locations (with 2 W Tx power, 0 dBi antenna gain) Hints: Omni instead of sector antennas used to exclude effects of antenna patterns ! GSM network used as example. But key message of results can be transformed to UMTS without significant modifications!2012 © by AWE Communications GmbH 22
  24. 24. Options for Network Design (5/8) Comparison of Electrical Field Strength Single Antenna Configuration Multiple Antenna Configuration Max. Value = 130 dBµV/m Max. Value = 125 dBµV/m Mean Value = 69 dBµV/m Mean Value = 64 dBµV/m2012 © by AWE Communications GmbH 23
  25. 25. Options for Network Design (6/8) Comparison of Coverage Probability Single Antenna Configuration Multiple Antenna Configuration Bad coverage probability in many Coverage Probability > 90% buildings (especially at the border) nearly everywhere2012 © by AWE Communications GmbH 24
  26. 26. Options for Network Design (7/8) Comparison of Required Tx Power in Downlink Single Antenna Configuration Multiple Antenna Configuration Very high Tx power is required to reach mobile stations Very low Tx power is sufficient  Exposure problems!  No exposure problems!2012 © by AWE Communications GmbH 25
  27. 27. Options for Network Design (8/8) Examining potential options for network design – determining the suitability of meeting coverage and capacity demands Suggestion: More medium or small power sites should be used instead of a few high power sites to  improve indoor coverage  reduce the exposure to electromagnetic waves  increase the capacity of the network Problem: Distributed medium or small power sites need more effort in the radio network planning process  highly accurate propagation models required  propagation models should offer the option to analyse indoor coverage in more detail2012 © by AWE Communications GmbH 26
  28. 28. EMC Module in ProMan (1/4) Features of EMC module in ProMan • Based on highly accurate wave propagation models (either deterministic or empirical) • Unlimited number of antennas can be considered in the project For each antenna the following parameters are used for the EMC analysis: - Max. radiated power (EIRP or Tx power at antenna input) - Number of carriers - Carrier frequency / frequency band - Antenna pattern incl. azimuth and mechanical downtilt  Path loss prediction (includes influence of antenna pattern)2012 © by AWE Communications GmbH 27
  29. 29. EMC Module in ProMan (2/4) Features of EMC module in ProMan • EMC-Specifications (national or international) - User-defined thresholds (equations) for different frequency ranges / bands - Predefined specifications for several countries (e.g. Germany, Switzerland,...) - Open interface to define new specifications or to modify pre-defined specifications - Threshold within each band defined by following formula (in V/m): Exp. Limit = Level Factor • (Frequency/MHz)Level Exponent + Level Offset - Definition of constant threshold X possible via  Level Factor a = 0.0  Level Exponent b = 0.0  Level Offset c = X2012 © by AWE Communications GmbH 28
  30. 30. EMC Module in ProMan (3/4) Features of EMC module in ProMan • Wireless standards (analyzed systems) - Definition by name and range of the carrier frequencies (min. and max.) - Predefined standards (GSM900, GSM1800,...) - Open interface to define new standards or to modify pre-defined standards - Superposition of all carriers operating on the same standard2012 © by AWE Communications GmbH 29
  31. 31. EMC Module in ProMan (4/4) Features of EMC module in ProMan • Computed and predicted results: - Field strength (V/m) for each wireless standard (superposition of all carriers of the same standard) - Superposition of all wireless standards present in the given scenario by using the following formula with Ei in V/m and individual thresholds per frequency band: 2  87   i 100kHz  Ei   i 1MHz  Ei EThreshold   1.0 1 MHz 300 GHz 2    f   - Resulting exposure plot including all carriers and standards with comparison to overall threshold of 1.0 for superposed exposure limit2012 © by AWE Communications GmbH 30

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