Working Group SE
ECC
CEPT
of the Electronic
Communications Committee
SE 40
Electronic Communications Committee
WGSE Project Team SE40 Meeting
SE40(13)020
Copenhagen, 29 – 30 October 2013
Source: France
Subject: technical and operational RLAN parameters to be used for sharing studies in
the 5 GHz frequency range
Date issued: 25 October 2013
Password protection required? (Y/N)
N
Summary:
The present document provides consideration related to technical and operational RLAN
parameters to be used for sharing studies in the 5 GHz frequency range. The document was an
input made by France on 5GHz RLANs for the recent JTG.
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Radiocommunication Study Groups
Received: 9 October 2013
Document 4-5-6-7/315-E
11 October 2013
English only
France
TECHNICAL AND OPERATIONAL RLAN PARAMETERS TO BE USED FOR
SHARING STUDIES IN THE 5 GHz FREQUENCY RANGE
1
Introduction
The present document provides consideration related to technical and operational RLAN parameters
to be used for sharing studies in the 5 GHz frequency range.
2
General comment
On a general basis, France will insist on the fact that the whole set of assumptions used in the
sharing studies between RLAN and other services in the 5 GHz range needs to depict RLAN
parameters and deployments consistent with the requirement for additional spectrum and consistent
each other.
As an example, RLAN data rates are linked to RLAN e.i.r.p. and bandwidth that also control the
access points coverage area and hence the number of RLAN covered by an access point. Also, one
should consider that the maximum RLAN e.i.r.p. will have an impact on the number of access
points to cover a certain area.
To this respect, a number of documents presented by the industry to justify such additional
spectrum provide a number of information relevant to this discussion. In addition,
Document 4-5-6-7/137 from WP 5A that estimates the spectrum requirement for broadband RLAN
in the 5 GHz range, is also a relevant source of information.
Finally, the mass-market and unlicensed nature of RLAN applications will mean that any potential
introduction in the additional portions of the 5 GHz range will represent a point of no-return. The
sharing conditions will therefore have to take into account long-term RLAN expectations and all
possibilities. This means that sharing parameters and simulations will have to be based on the safe
side.
3
RLAN technical characteristics
3.1
e.i.r.p. levels
Within discussions in the JTG Correspondence group, different elements have been proposed and in
particular the following e.i.r.p. distributions (from the USA):
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RLAN EIRP Level
200 mW
(OmniDirectional)
80 mW
(OmniDirectional)
50 mW
(OmniDirectional)
25 mW
(OmniDirectional)
RLAN Device
Percentage
(Indoor operation)
18%
26%
14%
37%
RLAN Device
Percentage
(Outdoor operation)
0.9%
1.3%
0.8%
2%
Compared to the maximum e.i.r.p. (200 mW, i.e. 23 dBm), these distribution corresponds to
average of 18.9 dBm (indoor) and 18.7 dBm (outdoor).
Considering indoor RLAN, France could agree to consider e.i.r.p. distribution in the sharing
analysis at the condition that the methodology and assumptions are duly depicted and agreed.
On the contrary, it is expected that by nature, any RLAN outdoor usage will be driven by coverage
and will hence more than likely be transmitting close to the maximum e.i.r.p..
It is also noted that JTG already considered that “Alternatively administrations may choose to use a
single e.i.r.p. level.”
Finally, it is understood from the table above that the maximum RLAN e.i.r.p in the extended band
would be 200 mW.
French position on e.i.r.p. levels
-
e.i.r.p. distribution could be used for indoor RLAN as far as duly justified and agreed
in JTG;
e.i.r.p. distribution for outdoor RLAN should be further studied;
administrations may assume a single e.i.r.p. level in a simulation;
it is assumed that the maximum e.i.r.p. is 200 mW (23 dBm). E.i.r.p. above 200 mW are
therefore not considered.
3.2
Channel bandwidths distribution
Considering RLAN channel bandwidth, France agrees to consider the distribution proposed by JTG
and confirmed by USA but at the condition that the methodology and assumptions are duly depicted
and agreed.
In particular, the percentage of expected 160 MHz bandwidth usage (15%) seems a bit low since
one of the main justifications for the additional spectrum was to allow the creation of more
160 MHz-channels that would open up the possibility for the key spectrum-driving application of
very high data throughput.
French position on channel bandwidth
-
bandwidth distribution could be used for RLAN as far as duly justified and agreed in JTG;
provisionally : 20 MHz: 10%, 40 MHz: 25%, 80 MHz: 50%, 160 MHz: 15%.
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3.3
Antenna pattern
Within discussions in the JTG Correspondence group, omnidirectional nature of the RLAN antenna
has been agreed but only in the horizontal plane, whereas the following antenna pattern has been
proposed for the vertical plane (from the USA):
TABLE 6
RLAN elevation antenna pattern
Elevation Angle θ
(Degrees)
Gain
(dBi)
45  θ  90
-4
35  θ  45
0
0  θ  35
3
–15  θ  0
-1
–30  θ  –15
-4
–60  θ  –30
-9
–90  θ  –60
-8
At first, it is not clear where this pattern comes from and if it is based on measurement of existing
5 GHz RLAN but it should be noted that its spherical gain is -1.6 dBi. Given that this pattern is
applied to e.i.r.p. level, it seems that the gain is to be increased by at least 1.6 dB.
Considering its shape, it is expected that such antenna pattern with quite high directivity can only be
related to certain type of fixed access points (AP). However, most AP currently in use can be
indiscriminately be installed horizontally and vertically, leaving no room for such high antenna
discrimination.
In addition, antenna pattern for “mobile” RLAN such as laptops, smartphones, tablets, M2M, …
can be used in all positions and can more than likely only relate to omnidirectional antenna. On the
contrary, it should be considered that the antennas of these applications could also be used vertically
which, on average, will probably lead to a 0 dBi gain in all directions.
One could also argue that with such directive antennas, waves reflections would have to be
considered.
Finally, if the sharing between RLAN and other services was shown as feasible only thanks to such
specific antenna pattern, it would then be necessary to specify RLAN regulatory conditions
consistent with this antenna pattern (e.g. by setting a RLAN maximum power 3 dB below the
maximum e.i.r.p.).
Overall, France does not see any justification for using the antenna pattern above compared to a
purely omnidirectional antennas (0 dBi) in azimuth and elevation, as already agreed in JTG.
French position on RLAN antenna
-
Omnidirectional (0 dBi) in azimuth and elevation are to be used in sharing studies.
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3.4
Outdoor/Indoor ratio
The percentage of outdoor RLAN obviously depend on the type of applications expected to be used
outdoor and may probably not be the same for each portion of the 5 GHz range (referring to the
current situation in the 5 150-5 350 MHz band (indoor only) and 5 470-5 725 MHz band (outdoor
possible).
It seems widely agreed that an “indoor only” usage cannot be controlled and that, in such band, it is
more than likely that a portion of RLAN are operated outdoor. France is of the view that a 5%
outdoor ratio is relevant in such case.
On the other hand, some applications such as Wireless Metropolitan Area Networks (WMAN) are
part of the justification for additional spectrum and are mainly dedicated to provide outdoor WIFI
connections (e.g. the FON network already publicises about 12 Millions spots). In such case, it can
easily be assumed that the number of outdoor usage will be very high. One can also note that,
although such networks can be served by indoor AP, this means that the outdoor RLAN will have to
operate at much higher e.i.r.p..
Overall, it can be assumed that in those portions of the 5 GHz range, the outdoor ratio could reach
20 to 30%.
French position on outdoor/indoor ratio
-
Consider a parametric approach.
Minimum outdoor ratio = 5%.
Maximum outdoor ratio = 30%.
3.5
Propagation conditions
Within discussions in the JTG Correspondence group, propagations models have been proposed by
the USA as follows :
Aeronautical radar case:
Recommendation ITU-R P.528 + angular clutter loss model from Recommendation
ITU-R P.452 + building attention with a Gaussian distribution utilizing a mean of
17 dB and a standard deviation of 7 dB.
EESS radar case:
Recommendation ITU-R P.619 + angular clutter loss model from Recommendation
ITU-R P.452 + building attention with a Gaussian distribution utilizing a mean of
17 dB and a standard deviation of 7 dB.
As for the building attenuation, France supports the principle of a normal Gaussian distribution but
would recommend that due justification be given to the figures proposed (17 dB mean and 7 dB
standard deviation).
Also, France is not opposed to a possible use of the angular clutter loss model from
Recommendation ITU-R P.452, although it is expected as being more relevant to aeronautical radar
case than EESS (that operate at very high elevation angles). It is also noted that this model depicts
2 sub-cases for the suburban environment and 3 for the urban environment, which obviously would
complicate its application. France would encourage JTG to only make use of the lower case
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(i.e. suburban with 9 m height and 25m distance and urban with 20m height and 20m distance) that
would be more representatives of most cities in the world.
It is also noted that such model is associated with a RLAN antenna height distribution. Although
France supports the principle, it would be expected a certain level of consistency between the
maximum RLAN height and the maximum clutter height.
Finally, for the EESS (case) one can assume that the impact of angular clutter loss model would
have a low impact. For dynamic analysis under the EESS case, instead of the clutter loss model,
France therefore proposes an alternative method by which all RLANs seen with an elevation angle
lower than 10° would be disregarded, irrespective of their situation and environment.
French position on Outdoor/Indoor ratio
-
building attenuation with a Gaussian distribution (17 dB + 7 dB if duly justified);
not opposed to possible use of angular clutter loss model from Recommendation ITU-R
P.452 (with consistent antenna height distribution);
for EESS, alternatively, proposes to disregard RLANs seen with an elevation angle lower
than 10°.
3.6
RLAN reference deployment area
Within discussions in the JTG Correspondence group, the USA proposed to consider an
hypothetical area with a certain number of inhabitants and in which relevant active RLAN devices
are deployed.
France has no objection that such hypothetical area be considered but would like to keep the door
open to different reference deployment area, such as cities or countries and deployment based on
existing population densities.
It is more than likely that if RLAN deployment considerations are consistent over the various
methods, simulations results would be similar. To this respect, France is of the view that specifying
the “active RLAN density per inhabitant” in the frequency band to be considered would represent
the relevant parameter to be used in the technical studies.
To do so, over a representative population, consideration will have to be given in particular of the
total number of 5 GHz RLAN equipments (users, AP, M2M, …), the possible repartition in various
5 GHz range portions, the number of RLAN user per AP, the relevant activity factor…
French position on RLAN reference deployment area
-
hypothetical area (US model) or deployment based on population densities associated with
“active RLAN density per inhabitant” parameter;
France will consider the 90 biggest cities over the French territory.
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3.7
Total number of RLAN
Before considering the number of active RLAN, it is important to have a relevant information about
the total number of RLAN over a certain area.
The so-called “PLUM Report” (Future proofing Wi-Fi – the case for more spectrum – A report for
CISCO (January 2013)) is one of the reference to justify for the 5 GHz RLAN spectrum extension.
In particular, its Figures 4-2 and 4-3 provide the evolution of WIFI Access points and terminals
from 2009 up to 2025 in western Europe.
FIGURE 4-2
Devices by technology in Europe (source “Plum Report”)
FIGURE 4-3
APs by technology in Europe (source “Plum Report”)
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From these figures, one can note that in 2009, there were already 100 million Wi-Fi access points in
western Europe and 350 million active devices WIFI equipment, mainly accommodated in the
2.4 GHz band. This represented 450 Millions equipment, hence already more than 1 per inhabitant
(assuming 400 Million inhabitants in western Europe).
By 2025, the expectation is 400 million Wi-Fi access points in western Europe and 1300 million
active devices. This represents 1.7 Billion equipment in Europe, hence roughly 4 per inhabitant (3
devices and 1 Access Point).
For France, with 66 million inhabitants, this will result in a total of 198 million RLAN devices and
66 million Access Points (AP), i.e. a total of 264 million RLAN.
These elements are further sustained by documents presented by the RLAN industry (Intel, Digital
Europe and Cisco) within the European preparation in CPG/PTD (see documents
CPG-PTD(13)048, 062 and 065 respectively), with expectation of 3.5 billion yearly shipments to be
considered by years 2014-2016.
Assuming a typical 3 to 4 years equipment lifetime therefore gives a total of around 10 Billion
equipments in service worldwide, so about 1 and ½ equipment per inhabitant.
Assuming higher penetration in some parts of the world (such as North America, Europe, Japan,
Korea,…) will then result in 3 RLAN equipment per inhabitant in developed countries, hence
confirming elements from the “PLUM Report” for Cisco.
French position on number of 5 GHz RLAN
-
A number of 3 RLAN devices and 1 Access Point per inhabitant is to be considered.
3.8
Band repartition
In deriving the number of RLAN per channel, the following elements will have to be considered:
The RLAN based on 802.11n and 802.11ac include 2 radio chains (2.4 and 5 GHz) and
can hence use simultaneously both frequencies. It is therefore not adequate to assume a
band repartition including the 2.4 GHz spectrum.
Only channels within the 5 150-5 850 MHz range should be considered (i.e. 35 channels
of 20 MHz).
In addition, the 5 150-5 350 MHz band is limited to indoor use. Therefore, outdoor
RLANs cannot be spread over this portion of the 5 GHz spectrum.
3.9
Activity factor
France agrees with the principle to consider only Access Points (AP) in the sharing studies, on the
understanding that the AP activity factor encompasses the one from user devices.
There is probably a number of methods to assess such activity factor, but France is of the view that
elements provided by WP 5A (Document 4-5-6-7/137) to support the additional spectrum
requirement for broadband RLAN in the 5 GHz range is one of the source to consider.
In particular, in the revised calculation based on Recommendation ITU-R M.1651, rows B6 of
Table 7a and 7b provide, for busy hours, the traffic per user (session-seconds) for the 5 different
reference RLAN categories:
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B6 (table 7a)
Traffic/User (session-seconds)
Corporate
Home
Public
category 1
67.5
8.1
20.25
category 2
9.6
21.6
6
category 3
0
0
6
category 4
90
540
18
category 5
72
432
21.6
One can also note that as mentioned in row D2, some applications (highlighted in yellow above)
combines the 2 directions and are hence to be doubled, leading to the following traffic/user.
B6 (table 7a)
Traffic/User (session-seconds)
Corporate
Home
Public
category 1
135
16.2
40.5
category 2
9.6
21.6
6
category 3
0
0
12
category 4
90
540
18
category 5
144
432
43.2
Since these elements are provided for each busy hours, this table can then be translated in Activity
factors (over 3600 seconds).
category 1
3.75%
0.45%
1.13%
category 2
0.27%
0.60%
0.17%
category 3
0.33%
category 4
2.50%
15.00%
0.50%
category 5
4.00%
12.00%
1.20%
10.52%
28.05%
3.33%
TOTAL per user
It can be seen from this table that the activity factor per user (hence per AP) varies from 3.33 % to
28 % (ratio of around 10) depending on the environment.
This seems to be quite high activity factor. However, this is the strict application of the figures
proposed by the RLAN community.
On this basis, France proposes to assess the impact of RLAN 5 GHz based on a range of activity
factor and proposes to consider a 3% to 30 % and to invite RLAN community to justify the activity
factor in way consistent with the calculation of the spectrum requirement.
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Overall, it can be noted that these activity factor would lead to a range of “active RLAN density per
inhabitant” from 0.03 to 0.3 over the whole 5 GHz range and (assuming an idle spread 35 channels)
of 0.0008 up to 0.008 within each 20 MHz channel (one can note that the US proposal represent a
density of 0.001 active RLAN per inhabitant).
French position on activity factor and active RLAN density
-
consider at this stage a 3% to 30 % activity factor for each AP;
this represents an “active RLAN density per inhabitant” of 0.0008 up to 0.008 within each
20 MHz channel;
invite RLAN community to justify the activity factor in a way consistent with the
calculation of the spectrum requirement.
______________
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