Measurement of RF Electromagnetic Fields for Base Station Compliance

1. Presentation of the Recommendation ITU-T K 100:"Measurement of radio frequency of electromagnetic fields to determine compliance with human exposure limits when a base station is put into service" ITU Regional Standardization Forum for Africa Dakar, Senegal 24-25 March 2015 Patrick ZEBOUA ARTCI

2. INTRODUCTION Development of networks and wireless technologies since the years 90 • Strong integrationof mobile services • Deployment of radio-electric infrastructure • Problematic of the exposure to electromagnetic waves Involvement of several structures at various levels to address the problematic 2

3. Actors and their areas of intervention • Research on the possible biological and health effects of EMF and safety standards relating to the exposure of populations • Development of standards for evaluation and measurement of exposure levels: • Assessment of the conformity of the exposure to electromagnetic waves WHO, CIPR-NI, National Authorities, etc. IEC, CENELEC, COST 281, national bodies, ITU-T (CE5] etc. Regulators, operators, national organizations 3

4. ITU-T Study Group 5 (CE5) Structure 7 Questions WP3/5 ICT and climate change WP1/5 Damage Prevention and Safety 5 Questions Question 12 Terminologies WP2/5 Electromagnetic fields: emission, immunity and human exposure 6 Questions Q7/5- Human exposure to electromagnetic fields (EMFs) due to radio systems and mobile equipment 4

5. A few ITU-T Recommendations approved by the EC5 ITU-T Recommendation K. 52 aims to define the techniques and procedures designed to determine the conformity of the telecommunications facilities and handset to limit values of national or international electromagnetic fields warranting security. ITU-T Recommendation K. 61 aims to help telecommunications operators to check the conformity of their facilities to the standards in the field of exposure limit values defined by local or national authorities. It contains guidelines on the measurement methods that could be used to assess this compliance. It also gives indications relevant for the choice of pertinent numerical methods for the prediction of the exposure level in various situations. ITU-T Recommendation K. 70 defines techniques which can be used by telecommunications operators to evaluate the report of total exposure in the vicinity of the transmitting antennas and to identify the main source of radiation. It provides advice on the mitigation methods which allow the reduction of the level of radiation so as to comply with the exposure limits. ** Software in appendix allowing its implementation : EMF - estimator 5

6. A few ITU-T Recommendations approved by the EC5 Recommendations ITU-T K. 83: The objective of the Recommendation K. 83 is to provide the public with clear information on the levels of electromagnetic fields in areas accessible to the public in the form of result continuedmeasurement Recommendations ITU-T K. 91 : The Recommendation ITU-T K. 91 gives guidance on how to assess and monitor the exposure of persons to electromagnetic fields (EMF) of radio frequency (RF), in areas surrounded by facilities of radiocommunication, based on existing standards relating to the exposure and to the conformity in the range of frequencies between 9 kHz and 300 GHZ. ** A computer software uncertainties is attached to this Recommendation.

7. Recommendations ITU-T K100 Entitled: "Measurement of radio frequency of electromagnetic fields to determine compliance with human exposure limits when a base station is put into service" Publisher: Davide Colombi & Byung Chan Kim Approval Date: 07/12/2014 Approval Procedure: AAP Original Version: English Summary:This Recommendation provides information on measurement techniques and method to assess the conformity of the electromagnetic fields to the limits of exposure of the general public when a new base station (BS) is put into service, taking into account the effects of the environment and other relevant sources of RF emissions in the vicinity of this new base station 7

8. ITU-T K 100: general procedure 8

9. Data to collect • For each service implemented: • Frequencies, bandwidth of channels; • Powers of transmitters and gains of the antennas; • Specific case of mobile communication systems • GSM: central frequency of the BCCH and number of transmitters • WCDMA: Frequency CPICH and average power • LTE: central frequency and bandwidth • Technical information, if possible, on the base stations in the vicinity 9

10. Simplified Assessment • It pertains to the enabling procedures to verify the conformity of a base station without the necessity to unfold to any length the procedure for detailed assessment 10

11. Simplified Assessment Hm and Dm = Fct (freq,PIRE) (see equation 7.1 ; 7.2 ; 7.3 Rec ITU-T K. 100) For example: a 400MHz transmitter with a pire of 2000 W, is compliant if • The lower part of the antenna is located at a height of 12 m from the track accessible to the public; • In the direction of the main lobe the areas accessible to the general public are located at least 18 m • Any other source of radio-electric emission with a PIRE above 100 W, is located at a distance less than 90 meters from the evaluated facility in the direction of the main lobe and less than 36 m in the other directions Typical values of Dm Typical values of Hm 11

12. Area of investigation Top View of the Assessment domain boundary Profile View of the Assessment domain boundary 12 12

13. Domain of investigation For example: • In GSM 1800, for a PIRE= 2000W, the value of D is significantly less than 20 meters. In other words to more than 20 m of the installation the ratio of exposure is less than -0.05 ; the compliance is therefore ensured • In GSM 900, for a PIRE = 4000W, the value of D is significantly less than 40 meters. In other words to more than 40 m of the installation the ratio of exposure is less than -0.05 ; the compliance is therefore ensured Typical value of the parameter D of the Assessment domain boundary 13

14. General Evaluation • The general assessment of the exposure • consists in the measure of the intensity of total field on the whole frequency range covered by the recommendation, or at least in the range of frequencies used by the technologies on the site, including surrunding sources. • Measurement Devices • The broadband device is therefore adapted to this type of measurement. Selective device for frequency can also be used by integrating the intensity of a field on the full bandwidth. • Magnitude measured • At a sufficient distance from the source, only the electrical (E) or magnetic (H) mean-square (RMS) of the field intensity should be measured and the exposure ratio (ER) can be calculated as follows: • Measurement Area • The measurement should be carried out in the field of investigation to a height of 1.5 m • Criterion of conformity • The site is deemed to be cormpliant , if the measured level of maximum density of total power in DI is less than one twentieth of the lowest power density limit in the frequency bands covered by the measurement. 14

15. DetailedAssessment 15

16. Detailed Assessment • Evaluation of neighbouring base stations • If the operating bands of ambient sources are known, the contribution of ER of each source is measured with the selective device for frequency by integrating the intensity of the field on the corresponding band. When this information is not directly available, it can be recovered by inspection of important peaks in the spectrum. • Determination of the TER • When the extrapolated intensity of the field Ei in each band (Bi) used by the evaluated base station and by the relevant ambient sources is known in the points of the DI where the evaluation of the overall exposure have stated the maximum field, the total level of exposure is calculated by adding the ratios of exposure. • Criterion of conformity • The site is deemed to be compliant, if the ER of the evaluated base station obtained with the detailed measurement is less than 0.05 or when the TER < 1. 16

17. Additional information • ITU-T/SG5 "Environment & Climate Change"itu.int/go/tsg5 • ITU-T and Climate Changeitu.int/go/itu-t/climate THANK YOU!