\makeatletter
\@ifundefined{HCode}
{\documentclass[screen, CRPHYS, Unicode, Thematic, published]{cedram}
\newenvironment{noXML}{}{}
\def\tsup#1{$^{{#1}}$}
\def\tsub#1{$_{{#1}}$}
\def\thead{\noalign{\relax}\hline}
\def\endthead{\noalign{\relax}\hline}
\def\tabnote#1{\vskip4pt\parbox{.99\linewidth}{#1}}
\def\tbody{\noalign{\relax}}
\def\ndash{\text{--}}
\RequirePackage{etoolbox}
\def\jobid{crphys20230682}
%\graphicspath{{/tmp/\jobid_figs/web/}}
\graphicspath{{./figures/}}
\newcounter{runlevel}
\let\MakeYrStrItalic\relax
\csdef{Seqnsplit}{\\}
\def\refinput#1{}
\def\back#1{}
\def\0{\phantom{0}}
\def\mn{\phantom{$-$}}
\def\botline{\\\hline}
\DOI{10.5802/crphys.183}
\datereceived{2023-07-31}
\daterevised{2024-03-06}
\dateaccepted{2024-03-15}
\ItHasTeXPublished
\def\sfrac#1#2{{#1}/{#2}}
\makeatletter
\g@addto@macro{\UrlBreaks}{\UrlOrds}
\gappto{\UrlBreaks}{\UrlOrds}
\makeatother
}
{\documentclass[crphys]{article}
\usepackage[T1]{fontenc}
\def\CDRdoi{10.5802/crphys.183}
\let\newline\break
\makeatletter
\def\sfrac#1#2{{#1}/{#2}}
\def\selectlanguage#1{} 
}
\makeatother

\usepackage{upgreek}

\dateposted{2024-07-11}
\begin{document}

\begin{noXML}

%\makeatletter
%\def\TITREspecial{\relax}
%\def\cdr@specialtitle@english{Energy in the heart of EM waves: modelling, measurements and management}
%\def\cdr@specialtitle@french{L'\'energie au c{\oe}ur des ondes \'electromagn\'etiques : mod\'elisation, mesures et gestion}
%\makeatother

\CDRsetmeta{articletype}{research-article}

\title{Extensive 5G measurement campaign to monitor EMF exposure in France}

\alttitle{Vaste campagne de mesures 5G pour surveiller l'exposition aux
ondes \'{e}l\'{e}ctromagn\'{e}tiques en France}

\author{\firstname{Lydia} \lastname{Sefsouf}\IsCorresp}
\address{Agence Nationale des fr\'{e}quences (ANFR), Maisons-Alfort, France}
\email[L. Sefsouf]{lydia.sefsouf@anfr.fr}

\author{\firstname{Emmanuelle} \lastname{Conil}}
\addressSameAs{1}{Agence Nationale des fr\'{e}quences (ANFR), Maisons-Alfort, France}
\email[E. Conil]{emmanuelle.conil@anfr.fr}

\author{\firstname{Jean-Beno\^{i}t} \lastname{Agnani}}
\addressSameAs{1}{Agence Nationale des fr\'{e}quences (ANFR), Maisons-Alfort, France}
\email[J.-B. Agnani]{jean-benoit.agnani@anfr.fr}

\keywords{\kwd{Exposure to EMF}
\kwd{5G}
\kwd{Exposure monitoring}}

\altkeywords{\kwd{Exposition aux ondes \'{e}lectromagn\'{e}tiques}
\kwd{5G}
\kwd{Surveillance de l'exposition}}

\def\thanksname{Note}

\thanks{This article follows the URSI-France workshop held on 21 and 22
March 2023 at Paris-Saclay.}

\begin{abstract}
As part of its mission to monitor public exposure, the French National
Frequency Agency (ANFR) has launched an extensive measurement program
at nearly 2000 sites to assess exposure following the deployment of the
new 5G mobile technology starting at the end of 2020. For each site
identified in the program, an initial measurement was conducted prior
to the deployment of 5G, followed by two additional measurements after
the sites had been in operation for approximately 4 months and 8
months, in order to monitor the evolution of exposure as a function of
traffic growth and operational deployment. The measurements were
performed in accordance with the ANFR protocol referenced in the French
Official Journal, which is the reference text for accredited
laboratories carrying out field measurements (E {in situ}). In addition
to the global and detailed frequency exposure measurements, specific
measurements were made by downloading a 1~GB file on the 3500~MHz band.
This approach allows to artificially generate additional traffic
according to the exposure indicator proposed by ANFR for steerable beam
antennas and to estimate the local exposure level that would
statistically be reached by 5G in the long term.
\end{abstract}

\begin{altabstract}
Dans le cadre de ses missions de surveillance de l'exposition du public
aux ondes \'{e}lectromagn\'{e}tiques, l'Agence nationale des
fr\'{e}quences (ANFR) a lanc\'{e} un vaste programme de mesures sur
pr\`{e}s de 2000 sites pour \'{e}valuer l'exposition \`{a} la suite du
d\'{e}ploiement de la nouvelle technologie mobile 5G d\`{e}s fin 2020.
Pour chaque site identifi\'{e} dans le programme, une mesure initiale
est r\'{e}alis\'{e}e avant le rajout de la 5G sur ces sites, une
deuxi\`{e}me et troisi\`{e}me mesure sont r\'{e}alis\'{e}es \`{a}
environ 4 mois et 8 mois de mise en service dans le but de suivre
l'\'{e}volution de l'exposition en fonction du d\'{e}ploiement
op\'{e}rationnel et de l'accroissement du trafic. Les mesures sont
r\'{e}alis\'{e}es selon le protocole de l'ANFR r\'{e}f\'{e}renc\'{e} au
Journal Officiel, constituant le texte de r\'{e}f\'{e}rence des
laboratoires accr\'{e}dit\'{e}s qui r\'{e}alisent des mesures sur le
terrain (E {in situ}). En compl\'{e}ment des mesures d'exposition
globale et d\'{e}taill\'{e}es en fr\'{e}quences, des mesures
sp\'{e}cifiques ont \'{e}t\'{e} effectu\'{e}es en t\'{e}l\'{e}chargeant
un fichier de 1~Go sur la bande 3500~MHz. Ce mode op\'{e}ratoire
permet de g\'{e}n\'{e}rer artificiellement un trafic suppl\'{e}mentaire
correspondant \`{a} l'indicateur d'exposition propos\'{e} par l'ANFR
pour les antennes \`{a} faisceaux orientables et permet d'estimer le
niveau d'exposition local qui serait statistiquement atteint \`{a}
terme en 5G.
\end{altabstract}

\shortrunauthors

\maketitle

\end{noXML}

{\vspace*{-2pt}}

\section{Introduction}\label{sec1}

5G is now being deployed in mainland France on several frequency bands:
the so-called low-frequency bands~700~MHz and 2100~MHz, which have been
used for many years by previous generation mobile phone networks (3G
and 4G), and the new 3500~MHz band, which offers a wider bandwidth for
higher data rates. 

The French Frequency Agency (Agence nationale des fr\'{e}quences ANFR)
ensures compliance with the limits for public exposure to
electromagnetic waves set by decree~\cite{1}. To this end, it develops
and updates the exposure measurement protocol. As part of its mission
to monitor public exposure, the ANFR has launched a major program of 
{in situ} electric field measurements to characterize the impact of 5G on
exposure levels~\cite{2}. This huge operation covered almost 2000 radio
stations throughout mainland France. From the end of 2020 to the end of
2021, three phases were carried out at sites identified to host 5G: an
initial measurement before the arrival of 5G at these sites (phase~1),
a second measurement carried out about 4 months after the start of
service (phase~2) and finally a third measurement at an interval of
about 8 months (phase~3). This campaign continued in 2022 and 2023 with
4 additional phases. 

This paper focuses on the results up to the end of 2021 and includes a
global exposure assessment based on broadband measurements, a detailed
frequency assessment to obtain the contribution of each frequency band,
and specific measurements with forced traffic in the 3500~band.

\section{Measurement protocol and locations}\label{sec2}

\subsection{Measurement protocol}\label{sec21}

Since 2001, the ANFR has been responsible for defining and updating the
{in situ} measurement protocol to verify that the radiofrequency (RF)
exposure levels of the general public are in compliance with the French
exposure limits. The ANFR protocol is referenced in the French Official
Journal~\cite{3} and is used by ISO IEC~17025~\cite{4} accredited
laboratories. It complies with the international standard EN
IEC~62232~\cite{5} section~6.3 ``Evaluation processes for {in situ} RF
exposure assessment''.

The current ANFR measurement protocol version~4 was used~\cite{6}. A
global measurement covering all significant radio sources between
100~kHz and 6~GHz is made at the selected measurement point. It is
based on the use of a broadband probe with a sensitivity of 0.38~V/m.
This assessment shall be made using a spatial averaging over a minimum
of three heights (1.1~m, 1.5~m and 1.7~m) and a time averaging over 6~min
(a shorter duration may be sufficient as long as the root mean
square (RMS) average remains stable).

A detailed measurement (case B) can then be made at the same position
as in case A to determine the exposure for each frequency band and for
each operator (detailed measurement of each exposure contribution in
the same frequency range). Case B involves the use of a spectrum
analyzer with a minimum sensitivity of 0.05~V/m per frequency band. The
results include the integration per service (e.g., mobile phone band or
TV band) and the sources of concern per service that are defined as a
significant emission with a minimum level of 0.3~V/m (more than 40~dB
below the lowest regulatory limit). Spatial averaging over at least
three heights (1.1~m, 1.5~m and 1.7~m) and temporal averaging over 
6~min is also required for Case B (the root mean square (RMS) of the
E-field measured at the three heights over 6~min). 

In the framework of this campaign, case B was not systematically
performed at every measurement point. During the second phase of
measurements in 2021, it was mostly carried out only at points where
the global level was greater than or equal to 2~V/m.

All measurements were performed outdoors and during daytime, in direct
view of the main lobe of the antennas (line-of-sight) and at a distance
of about 100~m. Figure~\ref{fig1} shows a typical configuration of this
campaign. 

\begin{figure}
\includegraphics{fig01}
\caption{\label{fig1}Typical configurations of measurement.}
\end{figure} 

For the current uses of the previous technologies (2G/3G/4G), the level
measured with a broadband probe (case A) is a good indicator of
exposure regardless of the time of day, and is generally close to the
level observed with continuous measurements averaged over a period of
6~min: the amplitude of the variations observed in the studies during
the day is generally small, less than 30\%. However, with the 5G
steerable beam antennas, greater spatial and temporal variability is
expected. As a result, the level measured with a broadband probe at any
one time may no longer be a good indicator of exposure. The level of
exposure will strongly depend on the usage, and in particular on the
data request made by the terminal. For this reason, ANFR proposed
in~\cite{7}, a new indicator, based on a foreseeable use of 5G. This
consists of sending 1~GB of data every 6~min in a given direction.
Assuming an average data rate of 500 Mbps, the antenna will only
transmit in the given direction for about 15~s out of the 6~min
(about 4\% of the time).

At the beginning of the roll-out of a new technology, the load is low,
mainly because only a few users have the appropriate terminals and
subscriptions. Thus, when 5G was launched in the 3.4--3.8~GHz band,
which is used exclusively for 5G, the levels measured were very low, as
expected, because the 5G network would be very lightly loaded. In order
to measure an exposure level that might be more representative of what
5G will eventually generate in the long term, the ANFR opted to
voluntarily solicit the 5G antennas by downloading a 1~GB file in order
to consider a realistic antenna load according to the assumptions made
to define the exposure indicator described above. 

The measurement consists of two assessments in the 3500~MHz band: when
the network is not voluntarily solicited and when it is solicited by a
mobile phone by downloading a 1~GB file from a server, ensuring that
the server's performance allows the expected 5G speeds (500 Mbps on
average) at the measurement point. It is also necessary to ensure that
the download occurs in the 3500~MHz band. This approach for in situ
measurements using emulated base station load profiles is described in
Annex B of the IEC~62232 standard~\cite{5}.

It is worth noting that the RMS electric field level averaged over
6~min without network solicitation can be evaluated over a period of
less than 6~min, as long as the averaged RMS value is stable. The RMS
electric field level averaged over 6~min can then be evaluated from the
measurement averaged over the duration of the download according to the
following equation:
{\begin{equation}\label{eq1}
E_{\text{estim\_6~min}}=\sqrt{\left(\frac{T_{t}}{360}\right)
\times {E}_{\mathrm{at}}^{2}+\left(1-\frac{T_{t}}{360}\right)
\times {E}_{\mathrm{st}}^{2}}
\end{equation}}\unskip
where: 

${E}_{\text{estim\_6~min}}$: field strength in V/m averaged
over 6~min 

${T}_{{t}}$: duration of the 1~GB file download in seconds

${E}_{\mathrm{at}}$: average field strength in V/m measured during the
download time

${E}_{\mathrm{st}}$: average field strength in V/m measured without
artificial network load.

\subsection{Measurement locations}

The distribution of 5G sites in mainland France is shown in
Figure~\ref{fig2}(a)\footnote{From 2022, the ANFR has extended its
program to include the DROM-COM.}, with 85\% of sites located in urban
areas and 15\% in rural areas (Figure~\ref{fig2}(b)). This
distribution is close to the share of urban population in the total
population of France (80\% in urban areas)~\cite{8}. 

\begin{figure}
\includegraphics{fig02}
\caption{\label{fig2}(a) Geographical distribution. (b) Environment
type distribution. (c) Frequency bands distribution.}
\end{figure} 

In the remainder of this paper, a measurement taken before 5G was
activated will be noted as a ``before'' measurement, representing
Phase~1, the one performed after approximately 4 months of 5G
activation will be noted as an ``after 1'' measurement, representing
Phase~2, and the one performed after approximately 8 months of
operational deployment will be referred to as an ``after 2''
measurement, representing Phase~3. Depending on the phase of the
campaign considered, a pair of measurements taken before and after 5G
is activated will be recorded as ``before--after1'' or ``before--after2''. 
A trio of measurements representing the three phases of the
campaign will be noted ``before--after1--after2''.

\section{Results \label{sec3}}

\subsection{Analysis of the overall exposure levels on sites hosting 5G
in the 3500~MHz band}\label{sec31}

In this section, the analysis of the overall exposure levels (case A)
is studied at about 1360 sites hosting 5G in the 3500~MHz band.
Figure~\ref{fig3}(a) shows the distribution of measurements by 1~V/m
increments on the overall exposure levels observed before and after the
activation of 5G during phases~2 and 3 of the campaign.

\begin{figure}
\includegraphics{fig03}
\caption{\label{fig3}(a) Distribution of overall exposure levels before
and after 5G roll out on 3500~MHz band; (b) distribution of differences
between overall exposure levels before and after 5G roll out on
3500~MHz band.}
\end{figure} 

These histograms show that exposure remains steady between phases~1 and
2. This trend has changed in phase~3, where an increase is observed. In
fact, 11\% of the points that were in the ``from 0 to 1~V/m'' range in
phase~1 leave this range and move to the higher ranges because they
become more exposed, as can be seen from the histograms plotted in
Figure~\ref{fig3}(a). However, this increase is moderate, as can be
seen, 83\% of the ``after2'' measurements remain below 2~V/m, compared
to 88\% of the ``before'' and ``after1'' measurements.

This first conclusion is confirmed by a comparison of the statistical
parameters shown in Table~\ref{tab1}. The average exposure levels are 1.16~V/m
for the ``before'' measurement, 1.17~V/m for the ``after1'' measurement
and 1.34~V/m for the ``after2'' measurement, i.e., an average variation
that increases from 0.01~V/m (close to zero) for phase~2 to 0.18~V/m
for phase~3.

\begin{figure}
\includegraphics{fig04}
\caption{\label{fig4}Probability density function (a) and cumulative
distribution function (b) of differences between overall exposure
levels before and after 5G roll out on 3500 band. 
See \mbox{Figure~\ref{fig3}(b)} for real data.}
\end{figure} 

\begin{table}
\caption{\label{tab1} Comparison of overall exposure filed level
statistics before and after 5G roll out}
\tabcolsep=4pt
\begin{tabular}{cccccc}
\thead
&\parbox[t]{2cm}{\centering Nb \mbox{measurements}} & 
\parbox[t]{1cm}{\centering Mean \newline  (V/m)} & 
\parbox[t]{1.2cm}{\centering Median\newline  (V/m)}&
\parbox[t]{2cm}{\centering  Std Deviation  (V/m)} & 
\parbox[t]{1cm}{\centering Max  (V/m)}\vspace*{2pt} \\
\endthead
Overall exposure ``before'' & 1358 & 1.16 & 0.99 & 0.75 & 6.19 \\ 
Overall exposure ``after1'' & 1358 & 1.17 & 1.01 & 0.74 & 5.41 \\ 
Overall exposure ``after2'' & 1358 & 1.34 & 1.19 & 0.79 & 5.83\vspace*{5pt}  \\ 
 & \parbox[t]{2cm}{\centering Nb \mbox{measurements}} & \parbox[t]{1.5cm}{\centering Mean\newline variation} & 
 \parbox[t]{1.5cm}{\centering Median\newline variation} & 
 \parbox[t]{2cm}{\centering Std deviation variation} & \parbox[t]{1.5cm}{\centering Max variation}\vspace*{5pt} \\ 
``after1--before'' Variation  & 1358 & 0.01 & 0.02 & ${-}$0.01 & ${-}$0.78 \\ 
``after2--before'' Variation  & 1358 & 0.18 & 0.2\0 & \mn0.04 & ${-}$0.36
\botline
\end{tabular}
\end{table}

In order to better characterize the variation between the ``before''
and ``after1--after2'' measurements, the local variation is studied to
observe how the electric field levels are distributed locally (i.e.
site by site). For this purpose, the statistical distribution of the
differences between the trio  of ``before--after1--after2''
measurements is characterized by histograms of 0.3~V/m steps in
Figure~\ref{fig3}(b) and modeled by the normal distribution probability
density and its cumulative distribution function (CDF) in
Figure~\ref{fig4}.

The histograms show a greater variation in phase~3 than in phase~2,
where in more than 90\% of the cases, the variation was between
${-}$0.3~V/m and 0.3~V/m (non-significant), compared to 69\% in phase~3.
From the probability density and CDF, it can be clearly seen that the
distribution of the ``before--after2'' variation is no longer centered
on zero as it was for the ``before--after1'' variation. It also
shows that the 90\% and 99\% values are larger for the ``before--after2'' 
variation.

The results conclude that 4 months after 5G became operational, there
was no significant change in overall exposure compared to before 5G
started. However, after 8 months, an increase in overall levels was
observed: the average overall exposure level increased from 1.16~V/m
to 1.34~V/m. 

It should be further noted that as only the global exposure was
investigated, it is not possible at this stage of the study to identify
which frequency bands are contributing to this increase. The detailed
frequency measurements (case B), discussed in the next section, provide
a comprehensive exposure assessment with a frequency-selective analyzer
that can identify the sources contributing to the exposure, as
described above in the measurement protocol. 

\subsection{Analysis of the contribution of the 3500~MHz band}\label{sec32}

For a more detailed analysis of the increase highlighted in the case A
study, the detailed frequency measurements (case B) will be discussed
by isolating the contribution of the telephony service in the 3500~MHz
band, but also in the other frequency bands. Among the 1358 sites
previously analyzed, 141 of the most exposed sites (where at least one
measurement has an overall value of 2~V/m) were covered by detailed
measurements during phases~2 and 3 of the campaign. 

Firstly, the Figure~\ref{fig5}(a) shows the service contributing most
to the overall exposure, where it can be seen that the 800~MHz and
900~MHz bands are the main contributors in about 55\% of the cases in
both phase~2 and phase~3. The 2100~MHz band appears to be the main
contributor in 9\% of cases in phase~3, compared to 1\% in phase~2. The
3500~MHz band could not a priori be the cause of the increase in total
exposure in phase~3 as it is not the main contributor. 

\begin{figure}
\includegraphics{fig05}
\caption{\label{fig5}Distribution of main contributions to overall
exposure (a) by service/frequency band and evolution of their mean
value (b). (FM-RNT: Radio broadcasting, PMR-Balise: Private Mobile
Radio, TM: Mobile Telephony (cellular network).)}
\end{figure} 

Secondly, to better illustrate the exposure by service, the histograms
in Figure~\ref{fig5}(b) show the increase in average exposure,
particularly for mobile services, between phases~2 and 3. The increase
in average exposure per frequency band is relatively significant for
frequencies where LTE (4G) is present (TM\_1800 and TM\_2100). For the
3500~MHz band, it is not possible to conclude that there is an increase
as the levels are not significant. It is important to point out that
the levels measured remain very low compared to the regulatory limit
values (36~V/m for the lowest mobile telephony band and 61~V/m for the
highest band). 

At least, these selective E-field measurements show that the observed
increase in total exposure is not due to an increase in field strength
in the 3500~MHz band, but to an increase in exposure in the other
mobile phone bands, especially those allocated to 4G.

\subsection{5G specific measurements with data download}\label{sec33}

At the launch of the campaign, few users are soliciting 5G antennas, so
it seemed interesting to artificially generate traffic to study the
impact of 5G on overall exposure by simulating higher usage in this
band. As described in the protocol section, the traffic is generated by
downloading 1~GB of data, which is equivalent to the exposure indicator
proposed by the ANFR. Measurements from 464 sites are studies in this
section.

Figure~\ref{fig6}  shows in grey the average field strength during the
download of the 1~GB file in the 3500~MHz band, and in pink and blue
the levels over 6~min with and without artificial download. The levels
with download averaged over 6~min are calculated from Equation~(\ref{eq1})
using the download time and the mean level measured during the
download.

\begin{figure}
\includegraphics{fig06}
\caption{\label{fig6}Average field strength while downloading a 1~GB
file compared with the average level without downloading on the
3500~MHz band.}
\end{figure} 

For each site, the levels shown here are the maximum levels observed
between phases ``after1'' and ``after2''.

The mean increase calculated between the measurement on the 3500~MHz
band with artificial download averaged over 6~min (shown in blue) and
the average level without download (shown in pink) on the same band is
0.54~V/m. The average level calculated from the single download of the
1~GB data file is 0.68~V/m, close to 0.70~V/m, almost the same as the
average level from the download measurements including existing
traffic, suggesting no significant traffic yet in this band.

The Table~\ref{tab2} shows the statistics calculated for the 3500~MHz
band with and without artificial downloading.

\begin{table}
\caption{\label{tab2}Statistics on the 3500~MHz band with and without
downloading}
\tabcolsep=2.7pt
\begin{tabular}{lccccc}
\thead
 & \parbox[t]{2.2cm}{\centering Nb \mbox{measurements}} & 
 \parbox[t]{1cm}{\centering Mean  (V/m)} & 
  \parbox[t]{1.3cm}{\centering Median  (V/m)}
  &  \parbox[t]{1.4cm}{\centering  Standard deviation} & 
   \parbox[t]{1cm}{\centering Max  (V/m)}\vspace*{2pt} \\ 
\endthead
\parbox[t]{4.8cm}{\raggedright\hangindent1pc Exposure on the band  5G 3500~MHz without download} & 464 & 0.16 & 0.10 & 0.16 & 1.22 \vspace*{5pt}\\ 
\parbox[t]{4.8cm}{\raggedright\hangindent1pc  Exposure on the band  5G~3500~MHz with download} & 464 & 0.70 & 0.38 & 0.79 & 5.75\vspace*{5pt}  \\ 
 & \parbox[t]{2.2cm}{\centering Nb \mbox{measurements}} & 
 \parbox[t]{1.4cm}{\centering Mean \mbox{variation}} & 
 \parbox[t]{1.4cm}{\centering Median variation} & 
 \parbox[t]{1.4cm}{\centering Std deviation variation} & 
 \parbox[t]{1.4cm}{\centering Max variation} \vspace*{5pt} \\ 
\parbox[t]{4.8cm}{\raggedright\hangindent1pc  Variation with and without download (V/m)} &  & 0.54 & 0.28 & 0.63 & 4.53\vspace*{2pt}
\botline
\end{tabular}
\end{table}

To evaluate the impact on the global exposure level, the average level
over 6~min related to the download of the isolated 1~GB file, resulting
from the specific measurement with 5G artificial solicitation, is
integrated by calculation to the global exposure case A and the
cumulative overall exposure case B without specific solicitation of the
network (only with existing traffic). The Figure~\ref{fig7}(a) shows
the distribution of the overall exposure levels ``case A'' with and
without artificial downloading. The Figure~\ref{fig7}(b) shows the
distribution of the overall cumulative exposure ``case B'' with and
without artificial downloading. 

\begin{figure}
\includegraphics{fig07}
\caption{\label{fig7}Distribution of the overall exposure (case a) (a)
and overall cumulative exposure (case B) (b) with 5G solicitation
computationally integrated and compared to the measurement without
specific solicitation (with existing traffic only).}
\end{figure} 

The comparison between the statistical parameters of case A and case B
with and without downloading in the 3500 MHz band is shown in
Table~\ref{tab3}.

\begin{table}
\caption{\label{tab3}Comparison of field strength statistics of overall
exposure with and without downloading at 464 sites operating on
3500~MHz band}
\begin{tabular}{lcccc}
\thead
 & \parbox[t]{1.8cm}{\centering Number of measures} & 
 \parbox[t]{1.2cm}{\centering Average  (V/m)} & 
 \parbox[t]{1.2cm}{\centering Median  (V/m)} & 
 \parbox[t]{1.8cm}{\centering Standard deviation}\vspace*{2pt}\\ 
\endthead
Overall exposure case A without download  & 464 & 1.51 & 1.24 & 1.00 \\ 
Overall exposure case A with download & 464 & 1.74 & 1.53 & 1.12 \\ 
Variation (V/m) &  & 0.23 & 0.29\vspace*{5pt} & 0.12 \\ 
\parbox[t]{6.2cm}{\raggedright\hangindent1pc
Overall cumulative exposure case~B without download} & 464 & 1.33 & 1.13\vspace*{2pt} & 0.89 \\ 
Overall cumulative case B with download & 464 & 1.58 & 1.38 & 1.03 \\ 
Variation (V/m) &  & 0.25 & 0.25 & 0.15
\botline
\end{tabular}
\end{table}

The average increase observed between the global exposure without
downloading a file (only with existing traffic) and the global exposure
relative to the single download of the 1~GB file is 21\% (0.23~V/m) for
case A and 31\% (0.25~V/m) for the cumulative level for case B, in line
with the exposure indicator introduced by the ANFR~\cite{9}.

In fact, in order to assess the use of the 3500~MHz band with respect
to the indicator proposed by ANFR, based on the expected use of 5G
(1~GB of data sent in a given direction every 6~min), the relative
usage rate is calculated from the level measured in the 3500~MHz band
without download (corresponding to the existing traffic) and the level
measured in the 3500~MHz band with download (corresponding to the
estimated future traffic). This rate reached an average of 12\% (median
6\%), which means that the exposure indicator proposed by ANFR remains
relevant and has not yet been reached (it would be reached when the
rate reaches 100\%). This means that 5G usage in the 3500~MHz band was
still low at the end of 2021. 

\subsection{Results on sites hosting 5G on low bands (700~MHz and
2100~MHz)}\label{sec34}

It should be noted that these frequency bands are not reserved
exclusively for 5G, the resources are shared with 4G technology and the
measurement equipment does not allow to distinguish the 5G contribution
from the 4G contribution in the level measured in the band.

To study the exposure created by the 5G roll out in these bands, 101
sites deploying 5G in the 2100 band and 142 sites in the 700 band were
measured three times: an initial measurement before 5G deployment
corresponding to phase 1 (``before''), and two measurements after 4 and
8 months of operation, corresponding to phase~2 (``after 1'') and
phase~3 (``after 2'') respectively. 

Regarding the 700~MHz sites, the overall level results show an average
increase in overall exposure of 0.1~V/m between September and
December~2021 (during phase~3) compared to an increase of 0.06~V/m at
the same sites between May and September~2021 (during phase~2).

The statistics for the overall exposure levels measured at the 2100~MHz
5G sites exposure remained stable between phases~1 and 2 (average
variation of ${-}$0.02~V/m). An upward trend was observed in phase~3
(average variation of 0.11~V/m). 

In sum, as for measurements on 3500~MHz sites, the results of the low
band measurements show an increasing trend in the overall exposure
level during the period of the end of 2021.

The analysis of the detailed frequency measurements reveals that the
800~MHz, 900~MHz and 1800~MHz bands are the main bands contributing to
the overall exposure. 

\section{Conclusion}\label{sec4}

This paper focused on analyzing the exposure evolution related to the
deployment of 5G on the French national territory. More than 5000
measurements were part of a large exposure monitoring program on sites
deploying 5G in the 700~MHz and 2100~MHz low frequency bands already
used for 3G and 4G networks, as well as in the new 3500~MHz band
exclusively dedicated to 5G. This paper was dedicated to the results of
measurements performed on sites deploying 5G during the year~2021.

First, the analysis of the overall measurements allowed to observe a
slight increase on 1358 sites, measured at 4 months and then 8 months
intervals after their 5G deployment. Then, a sample was taken of the
most exposed sites, where the analysis of detailed measurements showed
an increase in the average exposure on all the mobile telephony bands.
It also showed that the 800~MHz and 900~MHz bands are the main
contributors to exposure, followed by the 700~MHz, 1800~MHz, 2600~MHz,
2100~MHz and 3500~MHz bands respectively for phase~2 and the 1800~MHz,
700~MHz and 2100~MHz bands respectively for phase~3 (the 3500~MHz band
was not identified as the main contributor in phase~3). 

As 5G traffic is still low at this stage of deployment, additional 5G
specific measurements were performed in the 3500~MHz band in the
presence of artificially generated traffic to solicit the 5G antenna by
downloading a 1~GB file using a 5G phone. The first results suggest an
increase of about 30\% of the overall exposure.

It can be conclude that the increase in the overall levels at
5G~3500~MHz sites is not a priori related to an increase in the field
strength in this band, but to an increase in levels in all other
frequency bands of mobile telephony, reflecting an increase in traffic.
It is important to remember that phase~3 of the campaign took place at
the end of 2021 where an increase in traffic could be observed.

The results of the low band measurements also show an increasing trend
in overall exposure levels by the end of 2021. The average increase is
0.11~V/m for 5G sites operating in the 2100~MHz band, and 0.09~V/m for
sites deploying 5G in the 700~MHz band. The frequency analysis showed
that this increase is not correlated with the deployment of 5G in these
bands.

The measurement campaign has continued in 2022 and 2023 and will assess
exposure after 1 to 2 years of 5G deployment.

\section*{Declaration of interests}
The authors do not work for, advise, own shares in, or receive funds
from any organization that could benefit from this article, and have
declared no affiliations other than their research organizations.

\section*{Acknowledgements}
The authors would like to greatly acknowledge EXEM company (ANFR'S
subcontractor) for the successful running of this measurement campaign
and for all the help given to launch this vast program. 

\back{}

\bibliographystyle{crunsrt}
\bibliography{crphys20230682}
\refinput{crphys20230682-reference.tex}

\end{document}
