Experimental Compliance Testing of Telephony Base Stations, Broadcast Stations, and General Mobile Transmitters

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1 Experimental Compliance Testing of Telephony Base Stations, Broadcast Stations, and General Mobile Transmitters Sven Kühn Foundation for Research on Information Technologies in Society ETH Zurich, Switzerland

2 Compliance Test Procedures Free-Space Measurements of incident E or H-Field: applicable only for quasi-plane wave field conditions Free-Space Measurements of incident E and H Field applicable for any kind of field distribution Free-Space measurements in general are not a sufficient proxy for fields actually induced in exposed bodies Dosimetric Measurements due to limited sensitivity applicable in the near field of the source

3 Compliance Test of General Mobile Transmitters several new wireless connectivity standards and technologies, e.g., DECT, Bluetooth, IEEE growing usage of these technologies in homes and offices device application is uncontrolled and devices are accessible to the public request from public health agencies for information on the expected exposure from general mobile transmitters no systematic study on the expected exposure procedures for compliance testing not available

transmitters with respect to safety guidelines and other sources of exposure

4 Objectives characterization of the exposure from different communication systems applied in home and office environments evaluation of the exposure from these transmitters with respect to safety guidelines and other sources of exposure development and evaluation of procedures for compliance testing of general mobile transmitters

Review of RF Exposure Relevant Parameters

DECT 1880 1900 250 Bluetooth 2402 2480 100 802.

11a 5470 5725 1000 Wireless PC peripherals 27 2400

5 Review of RF Exposure Relevant Parameters Technology RF range (MHz) Peak output power (mw) DECT Bluetooth b g a a Wireless PC peripherals up to 10 Baby surveillance up to 500

6 Methods for Experimental Evaluation in Free Space Experimental determination of the DUT s radiation main beam: - circular scans at constant distance around the DUT - determination of the E-field maximum E-field mapping up to a distance of 2.5m E-Field mapping over distance 2 1 DUT

7 Methods and Equipment for Dosimetric Evaluation dosimetric assessment system, e.g., DASY4 miniature dosimetric probes (ES3DV6, EX3DV6) flat and SAM phantom tissue simulating liquids (f: 27MHz - 6 GHz)

8 Test Condition of Device well-defined time-averaged P out (with respect to max time-averaged P out ) to-consider: 1) static or adaptive power control 2) time domain channel access dependence on: - medium access control method - time domain duplex - transmitted data rate covering frequency dependencies worst-case exposure position for dosimetric evaluation to-consider: 1) typical operational positions can be defined - applicable test standard exists, e.g., telephone handsets - no applicable test standard exists, e.g., Bluetooth headset 2) no typical operational positions can be defined

9 Test Conditions - IEEE802.11b one RF channel occupies 22 MHz of the 80 MHz band fixed peak output power channel access mechanism and data rate determine P avg - channel access mechanism determines minimum crest factor - CSMA/CA (Carrier Sense Multiple Access with Collision Avoidance) - CSMA/CA + RTS/CTS (Ready to Send / Clear to Send) - MSDU size determines actual crest factor:

10 Test Conditions - IEEE802.11b - Test Parameters three test channels (1, 6, 11) cover nearly the entire band channel access mechanism with lowest crest factor - CSMA/CA: cf_min = CSMA/CA + RTS/CTS: cf_min = 1.38 maximum output data rate: - unidirectional transmission (e.g. use of UDP) - UDP payload = 1472 byte dosimetric test positions: - phantom flat section - phantom head for WLAN handsets UDP b MAC DUT remote device

11 Results - Incident E-Field from IEEE802.11b 100 SMC WLAN AP Airport Extreme 10 [V/m] [cm]

12 Results - Incident E-Field from DECT Fixed Part 100 Siemens Gigaset 3015 Binatone LB617 HiTel Moai [V/m] [cm]

13 Results - Incident E-Field from Bluetooth 100 Mitsumi Bluetooth Dongle (asynchronous operation) Acer Bluetooth Dongle (asynchronous operation) [cm]

14 Results - Baby Surveillance Devices 1000 Vivanco BM800 Vivanco BM900 Philips SC [V/m] [cm]

15 Results - Incident E-Field from Wireless Peripherals E-field (V/m) at distance Device 1 cm 5cm 10 cm Logitech keyboard Gyration mouse Results - Finger Exposure Position E-field (V/m) Thumb Little finger 5 Trigger finger Mouse tip 2

16 Results - Spatial Peak SAR DECT maximum SAR Device 1g [mw/g] 10g [mw/g] Ascom Avena Siemens 2000C Siemens Swisscom R IEEE802.11b maximum SAR Device 1g [mw/g] 10g [mw/g] SMC Access Point Airport Extreme Airport Express

005 <0.005 Nokia HDW-2 (Class 3) 0.009 <0.

17 Results - Peak Spatial SAR Bluetooth Baby Surveillance maximum SAR Device 1g [mw/g] 10g [mw/g] Mitsumi Dongle (Class 1) Acer Dongle (Class 2) SE HDH-300 (Class 3) <0.005 <0.005 Nokia HDW-2 (Class 3) <0.005 maximum SAR Device 1g [mw/g] 10g [mw/g] Vivanco BM Vivanco BM Wireless PC Peripherals below measurement uncertainty: < mw/g

18 Results - Summary test max. max. max. ICNIRP ONIR* frequency 10g SAR E-field E-field limit limit range [W/kg] [V/m] [V/m] [V/m] [V/m] Device class [MHz] (20 cm) (100 cm) Baby surveillance DECT** WLAN Bluetooth PC peripherals <1.5 < *ONIR limits for fixed transmitters with ERP of >6W ** Extrapolated maximum for asymmetric transmission mode

19 Conclusions - General Mobile Transmitters Worst-case spatial peak SAR values close to the limits for the public or uncontrolled environments, e.g., IEEE802.11b and Bluetooth class I devices Worst-case spatial peak SAR in the range of mobile phones Maximum incident field exposures at 1m can significantly exceed those of base stations (typically V/m); at very close distances the derived exposure limits are violated The most reliable procedure for evaluation of exposure and demonstration of compliance is the dosimetric evaluation under worst-case conditions

20 Compliance Test of Controlled Transmitters Controlled transmitters are directly accessible to professional personell only Compliance w.r.t. expsoure of the general public is tested at certain distances Exposure is assessed in free-space by assessment of the incident E-field Compliance is tested with reference levels (e.g. ICNIRP)

21 Technologies Technology Frequency Band Technology Frequency Band ETACS 900 AMPS NMT USDC NMT NAMPS GSM JTACS GSM PDC GSM NTACS C UMTS CDMA IS DECT (EU) CDMA IS DECT (US) CDMA IS DECT (US) CDMA IS Radio Broadcast CDPD TV Broadcast /

22 Reference Levels Compliance with the reference level will ensure compliance with the relevant basic restriction. (ICNIRP) Most countries have adopted the reference levels from the ICNIRP Guidelines for limiting exposure to time-varying electric, magnetic, and electromagnetic fields Some countries, e.g., Italy and Switzerland have adopted the precautionary principle, i.e., those countries limit the exposure to a fraction of the ICNIRP for places of sensitive use Reference levels were derived for plane wave exposure conditions for for a simplified (spheroidal) whole-body model

23 Assessment methods General considerations: - field perturbation by the measurement personnel, e.g., reflection and absorption of the EMF due to the body of the measurement engineer - application of the measurement antenna, e.g., non-observance of antenna directivity and polarization - application of not effectively decoupled cables, e.g., act a secondary antennas - application of the measurement receiver, e.g., wrong measurement settings - selection of the measurement point, e.g., measurement points that are not feasible to give the maximum EMF exposure, measurement points close to bodies that - influence the measurement antenna s calibration.

Assessment methods Sweeping method (Swiss ONIR) Locations with sensitive use Scan of the measurement volume in maximum hold mode of the measurement receiver (broad band or frequency selective)

24 Assessment methods Sweeping method (Swiss ONIR) Locations with sensitive use Scan of the measurement volume in maximum hold mode of the measurement receiver (broad band or frequency selective) Extrapolation to maximum + determination of the maximum field exposure + fast - influence of engineers body - not representative w.r.t. to reference limits which must be averaged over the volume of the human body

25 Assessment methods Examination of well-defined point within volume (e.g., Protocole de mesure in situ, ANFR France) Averaging over the measurement points Application of isotropic measurement antennas + representative w.r.t. to reference levels - time consuming - limited number of positions Combination of both methods was used in the Salzburg study

26 Broadband Field Probes Fields summed up in a broad frequency range. To consider: Calibration; Linearity; Frequency response; Isotropy; Time-domain response; Temperature response.

Frequency and Code selective equipment Requires trained personell Known

channel overlay in frequency domain To-Consider: calibration of the

measurement antenna; frequency response of the analyzer, cable, and

27 Frequency and Code selective equipment Requires trained personell Known frequency spectrum distribution Measurement receiver overcome the issue of channel overlay in frequency domain To-Consider: calibration of the analyzer, cable, and measurement antenna; linearity analyzer, cable, and measurement antenna; frequency response of the analyzer, cable, and measurement antenna; detector type; temperature response mismatch between measurement equipment.

28 Conclusions - Controlled Transmitters Compliance is tested with reference levels Translation of incident fields into actually induced fields is still under scientific investigation Determination of measurement methods that reflect induced fields is still under scientific investigation

WLAN. Date: 20 October 2016

WLAN. Date: 20 October 2016 WLAN Date: 20 October 2016 A wireless local area network (WLAN) allows computers and laptops to be connected to each other, to peripheral devices (printers, scanners etc.) and to an Internet access point.