CEPT
ECC
CPG-PTD ad hoc (14)xx
Electronic Communications Committee
4th meeting of CPG-PTD ad hoc “Mobile-DTT”
ANFR, Maisons-Alfort, 19 - 20 July 2013
Date issued:
xx March 2014
Source:
France
Subject:
Proposal for an IMT user equipment OOBE regulatory limit for the
protection of the broadcasting service in the frequency band 470-694
MHz.
Summary:
A Monte Carlo study was carried out for assessing IMT700 uplink interference (i.e. from LTE
user equipment) into Digital Terrestrial Television Broadcasting (DTTB) reception. Measurements
were also carried out for assessing the impact of OOBE as well as short pulse interferences from
IMT user equipment to DTTB reception
Further to the decision of the CEPT administrations, made at the 5th meeting of PTD, to focus on
IMT UE OOBE levels from-40 to -46 dBm/8 MHz (for 10 MHz IMT channel) for further
investigations, supplementary calculations have been done in accordance with the template
defined in Annex 16 of the Chairman’s Report (Annex 16 of doc. CPG-PTD(14)094), for deriving
a single value of IMT UE OOBE limit.
This document proposes a single value of IMT UE OOBE limit for the protection of the
broadcasting service in the frequency band 470-694 MHz as resulting from the studies.
Proposal:
It is proposed that the OOBE of IMT user equipment operating in the frequency band 694-790
MHz should not exceed -42 dBm/8 MHz for a 10 MHz LTE channel bandwidth in the frequency
band 470-694 MHz for the protection of the broadcasting service in this frequency band.
Proposed IMT user equipment OOBE regulatory limit for the protection of the broadcasting
service in the frequency band 470-694 MHz.
A MC study and a measurements campaign were carried out by France, for assessing IMT700 user
equipment (UE) interference into Digital Terrestrial Television Broadcasting reception. The results
obtained show that in case of a single active IMT UE per IMT BS sector (3 IMT UE transmitting
simultaneously in a cell), which represents the worst case scenario in terms of the impact of IMT
UE OOBE:
 It is necessary to choose DDTB receiver ACS and IMT UE ACLR around the same order
of magnitude.
 The average ACS of the recent DTTB receivers is in the range of 62 to 65 dB.
 For an observation time (TW) of 1 hour (3600 seconds), DTTB receiver ACS = 65 dB and
IMT UE ACLR = 65 dB (IMT UE OOBE=-42 dBm), the probability (P) of observing an
-2-
interference from IMT UE to DTTB receivers is 4.4, 0.45 and 0.045% respectively for
decorrelation times (DT) of 1, 10 and 100 s.one second. These probabilities are fairly
higher in case of 10 actives UE per IMT BS sector. However, the increase of P is due to
the in-band (IB) emissions of IMT UEs.
On the basis of the above elements and knowing that P(%) values are calculated for a DTTB
reception in a pixel (100x100 m) at the edge of the DTTB coverage, it is proposed that the OOBE of
IMT user equipment operating in the frequency band 694-790 MHz should not exceed -42 dBm/8
MHz for a 10 MHz LTE channel bandwidth in the frequency band 470-694 MHz for the protection
of the broadcasting service in this frequency band. This value represents already a good protection
under some worst-case conditions (coverage edge, ACS assumptions). It is expected that DTTB
receivers ACS will be improved in the future.
The details of the analysis are presented in Annex 1 to this document.
-3-
ANNEX 1
Determination of an IMT user equipment OOBE regulatory limit for the protection of the
broadcasting service in the frequency band 470-694 MHz.
1
Introduction
The MC study was carried out for a 10 MHz IMT system. The simulation method and assumptions,
the system parameters and the ACLR correction factors used as well as the results obtained are
presented in detail in document CPG-PTD(14)042.
Measurements were carried out on ten different DTTB receivers (DVB-T and DVB-T2 receivers),
currently available on the European market, for assessing the impact of OOBE as well as short
pulse interferences from IMT user equipment to DTTB reception on channel 48. Details of the
measurements are presented in document CPG-PTD(14)044.
Further to the decision of the CEPT administrations, made at the 5th meeting of PTD, to focus on
IMT UE OOBE levels from-40 to -46 dBm/8 MHz (for 10 MHz IMT channel) for further
investigations, supplementary calculations has been done in accordance with the template defined in
Annex 16 of the Chairman’s Report (Annex 16 of doc. CPG-PTD(14)094), for deriving a single
value of IMT UE OOBE limit.
This document proposes a single value of IMT UE OOBE limit for the protection of the
broadcasting service in the frequency band 470-694 MHz.
2
Reminder of the results of the MC study presented in document CPG-PTD(14)044
First MC calculations were carried out for a wide range of ACS and ACLR values, respectively
from 40 to 80 dB and from 48 to 78 dB (IMT UE OOBE ranging from -25 to -55 dBm).
After having examined the obtained results, that is the instantaneous probability of interference (IP)
of DTT fixed roof top antenna reception by IMT UE emissions, for the sake of efficiency, it was
decided to limit the ACS values to 60 and70 dB and the ACLR range to from -35 to -50 dBm.
Moreover, the probability P(%) of TV viewer observing IMT UE causing at least one harmful
interference to DTTB reception during a time window (TW) of 1 hour was calculated. The value of
TW was fixed to 1 hour as proposed by some contributions to the mobile-DTT correspondence
group in October 2013 on the basis of the average viewing time. The results obtained are presented
in Table 1.
The objective of this TW concept is to reconcile the use of Monte Carlo approach with the need to
take into account time element by converting the instantaneous probability of interference (IP) of
interference from IMT UE to DTTB reception into a probability P(%) which would better reflect
the impact of interference on TV viewers.
-4-
TABLE 1
Simulation results for 200000 events (runs)
IP values for ACS = 60 and 70 dB; and ACLR = 58, 63, 68 and 73 dB
ACS (dB)
60
TW (s)
DT (s)
DT (s)
DT (s)
DT (s)
# active UEs
1
3600
1
10
100
200
ACLR correction
factor (dB)
0
IP(OOB+IB)
P1 %
P2 %
P3 %
P4 %
OOBE (dBm/8 MHz)
UE
ACLR
(dB)
IP(OOB)
IP(IB)
-35
58
4.21E-05
2.63E-05
6.85E-05
21.8
2.43
0.24
0.12
-40
63
2.10E-05
3.68E-05
6.31E-05
20.3
2.24
0.22
0.11
ACS (dB)
70
# active UEs
1
ACLR correction
factor (dB)
0
OOBE (dBm/8 MHz)
UE
ACLR
(dB)
-40
IP(OOB)
IP(IB)
IP(OOB+IB)
P1 %
P2 %
P3 %
P4 %
63
1.05E-05
< 5E-06
1.05E-05
3.71
0.37
0.037
0.018
-45
68
5.26E-06
< 5E-06
5.26E-06
1.87
0.18
0.018
0.009
-50
73
5.26E-06
< 5E-06
5.26E-06
1.87
0.18
0.018
0.009
Note : the simulations in the table above were carried out with 200000 events (runs), resulting in an
accuracy which cannot be better than 5E-06.
The results show the need to balance expected ACS and required ACLR. In addition, it provides an
illustration that lower DT will correspond to higher probability of occurrence in a one hour time
window. On the other hand, it has to be pointed out that lower decorrelation time would also
correspond to shorter and less disruptive interference. Therefore, there is a balance between the
level of the probability P (%) and the impact of a single interference situation.
3
Assumptions and results of supplementary calculations
Supplementary simulations have been carried out according to the parameters decided by PTD at its
5th meeting:
 Number of active UE per sector = 1 and 10;
 ACS = 65 dB;
 ACLR = 63, 65, 67 and 69 dB;
 ACLR correction factor (for 10 UE) = 9 and 19 dB;
-5-
 TW = 1800 s (30 min) and 3600 s (60 min);
 DT = 1, 10 and 100 s.
500000 events (runs) have been simulated resulting in an accuracy which cannot be better than 2E06. These results obtained are presented in Table 2 and in Figures 1 to 4 (see Annex 3 for the
interpretation of the calculated IP). Rough results are presented in the Excel file below:
TABLE 2
Simulation results for 500000 events (runs)
IP values for ACS = 65 and 70 dB; and ACLR = 63, 65, 67 and 69 dB
Evaluation of the probability of interference (IP) from IMT UE to DTTB rooftop fixed
reception (MC simulations)
Scenario
Urban rooftop fixed DTTB reception
IMT Channel BW (MHz)
10
IMT UE e.i.r.p. (dBm)
23
Reference OOBE (dBm) level
is defined for full resource
allocation (50 RB) to a single
UE
ACS (dB)
65
# active UEs/Sector
1
ACLR correction factor (dB)
0
19
9
UE ACLR
(dB)
IP-Case 1
IP- Case 2
IP- Case 3
-40
63
1.47E-05
6.10E-05
6.31E-05
-42
65
1.26E-05
5.04E-05
5.56E-05
-44
67
6.31E-06
4.73E-05
5.08E-05
-46
69
6.30E-06
4.42E-05
4.63E-05
OOBE (dBm/8 MHz)
10
Note : the simulations in the table above have been made with 500 000 samples,
resulting in an accuracy which cannot be better than 2E-06
It should be noted here that the IP obtained in the case of 10 UEs transmitting simultaneously in an
IMT BS sector is higher than the IP obtained in the case of a single UE. However, this is due to the
in-band emission of the UEs and not due to their OOBE.
-6-
Figure 4
Figure 5
Figure 6
Figure 7
The probability of occurrence P (%) of at least one interference from IMT UEs to DTTB receiver
during a given time window (TW = 30 min or 60 min) are represented in figures 4 to 7, for different
number of active UE (1 or 10), different values of decorrelation time (DT = 1s, 10s or 100s) and
different ACLR correction factors (0dB, 9dB or 19dB). The ACS is 65 dB.
It is to be noted that, for the case of DT = 1s, the difference between the curves considering ACLR
reduction factors of 9 and 19 dB should be read with caution, as the corresponding probabilities of
interference (IP) and DT considered are very low.
Figure 8
-7-
Figure 8 givesa better insight into the meaning of P. The P curves presented in this figure, based on
the PI presented in Table 2, show that even a probability P=18 % of observing a interference from
IMT UE to DTTB reception during ban observation time (TW) of 1 hour, probability that can be
considered high, doesn’t mean that an interference will occur in this TW since the instantaneous
probability of interference (IP) from IMT UE to DTTB reception is quite low (see Tables 1 and 2).
Actually, to be sure that interference will occur it is needed to wait more than 20 hours!
Conclusions
For an observation time (TW) of 1 hour (3600 seconds), DTTB receiver ACS = 65 dB and IMT UE
ACLR = 65 dB (IMT UE OOBE=-42 dBm), the probability P(%) of observing an interference from
IMT UE to DTTB receivers is 4.4, 0.45 and 0.045% respectively for decorrelation times (DT) of 1,
10 and 100 s.one second. These probabilities are fairly higher in case of 10 actives UE per IMT BS
sector. However, the increase of P is due to the in-band (IB) emissions of IMT UEs.
Bearing in mind that these P(%) are calculated for a DTTB reception in a pixel (100x100 m) at the
edge of the DTTB coverage and the average ACS of recent DTTB receivers is in the range of 62 to
65 dB (see Annex 4), it is proposed that the OOBE of IMT user equipment operating in the
frequency band 694-790 MHz should not exceed -42 dBm/8 MHz for a 10 MHz LTE channel
bandwidth in the frequency band 470-694 MHz for the protection of the broadcasting service in this
frequency band. This value represents already the protection under some worst-case conditions
(coverage edge, ACS assumptions). It is expected that DTTB receivers ACS will be improved in the
future.
-8-
ANNEX 2
Method of calculation of P
If IP is the interference probability derived from the Monte Carlo simulations and C is the number
of network state changes during a certain time window (TW), assuming that two consecutive
network states are independent (not correlated), then the probability P of TV viewer observing LTE
UE causing at least one harmful interference to DTTB reception is given by:
𝑃 = 1 − (1 − 𝐼𝑃)𝐶
(1)
Such probability P could be understood as the probability of having a disruption of duration DT
(decorrelation time) when watching TV during a given TW (time window). This time window
should reflect what is considered acceptable for the TV viewer.
C could be calculated as follows
C = TW/DT
where :
TW: time window;
DT : average “decorrelation” time between two consecutive network states
for one active uplink data user.
The average “decorrelation” time reflects the fact that when a terminal is interfering with the
broadcasting receiver, it will keep the resource of the network for a certain time before this resource
is allocated to another terminal which may, or may not, cause interference to the broadcasting
receiver.
Some contributions to the third mobile-DTT correspondence group meeting in October 2013
indicate a TW equal to one hour. The basis for this value could be an average viewing time for a
given TV program.
The range of DT could be:
–
from 1 ms which is the the subframe time : it is not realistic to assume that each
terminal will transmit;
–
to the full time window. If this time window is as large as one hour, this is neither
realistic since it would assume that each terminal is permanently transmitting traffic
data (other than signaling). In addition, for such large time, the movement of the
terminal would also create another dimension of decorrelation, since the interference
potential could significantly vary between the positions of the terminal during one hour.
“Decorrelation” time depends on the services used by the IMT user, but it is felt possible to derive
an average “decorrelation” time considering the various IMT services.
-9-
ANNEX 3
Numerical examples of the probability of interference (pI) calculated
across a pixel of 100 m x 100 m in urban scenarios
500 000
K (# generated events)
M (# of events where dRSS>sens)
NI (# events without
# events with
interference)
Interference
pNI: probability of noninterference
475 000
pI: 1- pNI: probability of
interference
475 000
0
100
0
474999
1
0.99999789
2.10526E-06
474998
2
0.99999579
4.21053E-06
474997
3
0.99999368
6.31579E-06
474996
4
0.99999158
8.42105E-06
474995
5
0.99998947
1.05263E-05
474994
6
0.99998737
1.26316E-05
474993
7
0.99998526
1.47368E-05
474992
8
0.99998316
1.68421E-05
474991
9
0.99998105
1.89474E-05
474990
10
0.99997895
2.10526E-05
474989
11
0.99997684
2.31579E-05
474988
12
0.99997474
2.52632E-05
474987
13
0.99997263
2.73684E-05
474986
14
0.99997053
2.94737E-05
474985
15
0.99996842
3.15789E-05
474984
16
0.99996632
3.36842E-05
474983
17
0.99996421
3.57895E-05
474982
18
0.99996211
3.78947E-05
474981
19
0.99996
4E-05
474980
20
0.99995789
4.21053E-05
474979
21
0.99995579
4.42105E-05
474978
22
0.99995368
4.63158E-05
474977
23
0.99995158
4.84211E-05
474976
24
0.99994947
5.05263E-05
474975
25
0.99994737
5.26316E-05
474974
26
0.99994526
5.47368E-05
474973
27
0.99994316
5.68421E-05
474972
28
0.99994105
5.89474E-05
474971
29
0.99993895
6.10526E-05
474970
30
0.99993684
6.31579E-05
474969
31
0.99993474
6.52632E-05
474968
32
0.99993263
6.73684E-05
474967
33
0.99993053
6.94737E-05
- 10 -
ANNEX 4
ACS values of recent DTTB receivers (see CPG-PTD(14)044)
Calculated DVB-T/T2 receivers’ adjacent channel selectivity
Continuous IMT UE transmission, UE ACLR=60 dB
ACS without
DTTB Receiver
CH48 filter (dB)
Rx1 (DVB-T2)
62
Rx2 (DVB-T2)
72
Rx3 (DVB-T)
62
Rx4 (DVB-T2)
60
Rx5 (DVB-T2)
65
Rx6 (DVB-T)
62
Rx7 (DVB-T2)
72
Rx8 (DVB-T)
72
Rx9 (DVB-T)
62
Rx10 (DVB-T)
54
DVB-T2 average value
65
DVB-T average value
62
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