ETSI TR 101 854 V2.1.1 (2019-04)

TECHNICAL REPORT
Fixed Radio Systems;
Point-to-point equipment;
Derivation of receiver interference parameters useful for
planning fixed service point-to-point systems operating
different equipment classes and/or capacities

2 ETSI TR 101 854 V2.1.1 (2019-04)

Reference
RTR/ATTM-0447
Keywords
point-to-point, radio, transmission, FWA
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3 ETSI TR 101 854 V2.1.1 (2019-04)
Contents
Intellectual Property Rights . 4
Foreword . 4
Modal verbs terminology . 4
Introduction . 4
1 Scope . 5
2 References . 5
2.1 Normative references . 5
2.2 Informative references . 5
3 Definition of terms, symbols and abbreviations . 6
3.1 Terms . 6
3.2 Symbols . 6
3.3 Abbreviations . 6
4 Overview of fundamental approach to noise limited assignments . 7
4.1 The Link Budget . 7
4.1.1 Introduction. 7
4.1.2 Receiver input level . 8
4.1.3 Fade margin (FM) . 11
4.2 Interference assessment . 11
4.2.1 General . 11
4.2.2 Wanted to Unwanted (W/U) ratios . 11
4.2.3 Receiver selectivity evaluation . 12
4.2.4 Net Filter Discrimination (NFD) . 12
4.2.5 The Carrier to Interference (C/I) ratio in mixed payload environment . 14
4.2.6 Evaluation of the Wanted to Unwanted (W/U) ratios . 15
5 Interference limited assignments . 15
6 Summary . 15
Annex A: Interference limited assignments . 16
Annex B: Wanted to Unwanted (W/U) ratios . 17
Annex C: Diagram showing the NFD procedure . 18
-6
Annex D: Table of typical values for noise figure and signal/noise at BER = 10 . 19
Annex E: Receiver selectivity (conservative approach) . 25
Annex F: Receiver selectivity (more realistic approach) . 26
F.0 Introduction . 26
F.1 Gross bit-rate . 26
F.2 Derivation of transmitter spectrum mask . 26
F.3 Derivation of receiver selectivity . 28
F.4 Derivation of cosine roll-off . 29
F.5 Transmitter mask and receiver selectivity of other equipment classes . 30
History . 31

ETSI
4 ETSI TR 101 854 V2.1.1 (2019-04)
Intellectual Property Rights
Essential patents
IPRs essential or potentially essential to normative deliverables may have been declared to ETSI. The information
pertaining to these essential IPRs, if any, is publicly available for ETSI members and non-members, and can be found
in ETSI SR 000 314: "Intellectual Property Rights (IPRs); Essential, or potentially Essential, IPRs notified to ETSI in
respect of ETSI standards", which is available from the ETSI Secretariat. Latest updates are available on the ETSI Web
server (https://ipr.etsi.org/).
Pursuant to the ETSI IPR Policy, no investigation, including IPR searches, has been carried out by ETSI. No guarantee
can be given as to the existence of other IPRs not referenced in ETSI SR 000 314 (or the updates on the ETSI Web
server) which are, or may be, or may become, essential to the present document.
Trademarks
The present document may include trademarks and/or tradenames which are asserted and/or registered by their owners.
ETSI claims no ownership of these except for any which are indicated as being the property of ETSI, and conveys no
right to use or reproduce any trademark and/or tradename. Mention of those trademarks in the present document does
not constitute an endorsement by ETSI of products, services or organizations associated with those trademarks.
Foreword
This Technical Report (TR) has been produced by ETSI Technical Committee Access, Terminals, Transmission and
Multiplexing (ATTM).
Modal verbs terminology
In the present document "should", "should not", "may", "need not", "will", "will not", "can" and "cannot" are to be
interpreted as described in clause 3.2 of the ETSI Drafting Rules (Verbal forms for the expression of provisions).
"must" and "must not" are NOT allowed in ETSI deliverables except when used in direct citation.
Introduction
The present document explains how the assignment criteria between Digital Fixed Service systems, occupying different
bandwidths and using different types of modulation are determined.
The primary aim of spectrum management is to use limited spectrum in the most efficient and effective manner.
Thus the maintenance of interference free operation, alongside the sometime conflicting desire to establish a maximum
link density with guaranteed system availability, are the primary aims of any spectrum management system.
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5 ETSI TR 101 854 V2.1.1 (2019-04)
1 Scope
The present document gives, initially, a basic overview of how a fixed point-to-point system is allocated an EIRP
guaranteeing predetermined link availability. It then reviews the methodology for deriving the parameters necessary for
the sharing of FS systems in an environment with different equipment classes and capacity. The methodology is based
on the limitation of noise and is not exclusive. In addition a method for calculation of RSL based on normalized values
is presented.
The present document highlights the primary parameters from European standards, which are vital to the development
of an assignment system. These parameters are:
• Transmitter radiation patterns.
• Receiver sensitivity.
• Receiver adjacent channel rejection.
• Receiver co-channel rejection.
In addition to these parameters the antenna radiation profile and, if fitted, the ATPC operating characteristics will have
a major effect on link density.
2 References
2.1 Normative references
Normative references are not applicable in the present document.
2.2 Informative references
References are either specific (identified by date of publication and/or edition number or version number) or
non-specific. For specific references, only the cited version applies. For non-specific references, the latest version of the
referenced document (including any amendments) applies.
NOTE: While any hyperlinks included in this clause were valid at the time of publication ETSI cannot guarantee
their long term validity.
The following referenced documents are not necessary for the application of the present document but they assist the
user with regard to a particular subject area.
[i.1] Recommendation ITU-R P.530: "Propagation data and prediction methods required for the design
of terrestrial line-of-sight systems".
[i.2] Recommendation ITU-R P.676: "Attenuation by atmospheric gases".
[i.3] Recommendation ITU-R F.746: "Radio-frequency arrangements for fixed service systems".
[i.4] Recommendation ITU-R SM.328-11: "Spectra and bandwidth of emissions".
[i.5] ETSI EN 302 217-2: "Fixed Radio Systems; Characteristics and requirements for point-to-point
equipment and antennas; Part 2: Digital systems operating in frequency bands from 1 GHz to
86 GHz;Harmonised Standard for access to radio spectrum of article 3.2 of Directive
2014/53/EU".
[i.6] ETSI TR 103 053 (V1.1.1) (2014-09): "Fixed Radio Systems; Parameters affecting the Signal-to-
Noise Ratio (SNR)and the Receiver Signal Level (RSL) threshold in point-to-point receivers;
Theory and practice".
[i.7] ETSI EN 302 217-1: "Fixed Radio Systems; Characteristics and requirements for point-to-point
equipment and antennas; Part 1: Overview, common characteristics and system-independent
requirements".
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6 ETSI TR 101 854 V2.1.1 (2019-04)
[i.8] ETSI TR 103 103: "Fixed Radio Systems; Point-to-point systems; ATPC, RTPC, Adaptive
Modulation (mixed-mode) and Bandwidth Adaptive functionalities; Technical background and
impact on deployment, link design and coordination".
[i.9] ETSI GR mWT 015: "Frequency Bands and Carrier Aggregation Systems; Band and Carrier
Aggregation".
[i.10] ECC/REC(01)05: "List of parameters of digital point-to-point fixed radio links used for national
planning".
[i.11] Recommendation ITU-R F.758: "System parameters and considerations in the development of
criteria for sharing or compatibility between digital fixed wireless systems in the fixed service and
systems in other services and other sources of interference".
3 Definition of terms, symbols and abbreviations
3.1 Terms
Void.
3.2 Symbols
For the purposes of the present document, the following symbols apply:
dB deciBel
dBW deciBel relative to one Watt
dBW/Hz deciBel relative to one Watt per Hertz
f Nyquist frequency
n
GHz GigaHertz
Hz Hertz
k boltzmann's constant
MHz MegaHertz
Mbit/s Megabit per second
N Modulation scheme
r Cosine roll-off factor
of
T Temperature in degrees Kelvin
3.3 Abbreviations
For the purposes of the present document, the following abbreviations apply:
ACM Adaptive Code and Modulation
ATPC Automatic Transmit Power Control
BB BroadBand
BCA Bands and Carriers Aggregation
BER Bit Error Rate
BW(U) BandWidth Unwanted
BW(W) BandWidth Wanted
C/I Carrier to Interference
CCDP Co-Channel Dual Polarization
CPM Continuous Phase Modulation
CS Channel Spacing
CW Continuous Wave
EIRP Equivalent Isotropically Radiated Power
FEC Forward Error Correction
FET Field-Effect Transistor
FM Fade Margin
FS Fixed Service
FSPL Free Space Path Loss
GBR Gross Bit-Rate
GR Group Report
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7 ETSI TR 101 854 V2.1.1 (2019-04)
IF Intermediate Frequency
IM Industrial Margin
F
ITU-R International Telecommunication Union - Radio sector (formerly CCIR)
N/I Noise to Interference
NF Noise Figure
NFD Net Filter Discrimination
PDH Plesiochronous Digital Hierarchy
QAM Quadrature Amplitude Modulation
RE Radio Equipment
RF Radio Frequency
RIC Radio Interface Capacity
RS Reed–Solomon
RSL Receive Signal Level
Rx Receiver
S/N Signal to Noise
SDH Synchronous Digital Hierarchy
STM Synchronous Transport Module
Tx Transmitter
W/U Wanted to Unwanted
XPD Cross-Polar Discrimination
4 Overview of fundamental approach to noise limited
assignments
4.1 The Link Budget
4.1.1 Introduction
A link budget ensures that the Equivalent Isotropically Radiated Power (EIRP) allocated to the transmitter maintains a
pre-determined level of service defined by error performance and availability. For example, a Bit Error Rate (BER)
-6
better than 10 and desired availability (usually at least 99,99 % of time are commonly used as service levels, see
note 1). Figure 1 illustrates the major elements of propagation loss that are taken into consideration when assigning
transmitter EIRPs to Fixed Service (FS) systems. All elements of propagation loss are frequency and path length
dependent. Fade margin and gaseous absorption characteristics are addressed in Recommendation ITU-R P.530 [i.1]
and Recommendation ITU-R P.676 [i.2] respectively.
NOTE 1: In modern digital systems implementing Adaptive Code and Modulation (ACM, "mixed-mode" systems
defined in ETSI EN 302 217-1 [i.7] and better described in ETSI TR 103 103 [i.8]) such availability is
usually applied for the "reference mode" used for planning purpose. In some cases, a lower availability
might also be acceptable, e.g. in Bands and Carriers Aggregation (BCA systems described in ETSI
GR mWT 015 [i.9]) systems where high availability is guaranteed by the carrier(s) in the lower band,
while the carrier(s) in the higher band might not physically exhibit sufficient fade margin for that;
therefore, lower availability (best effort) is still acceptable for their "supplementary" payload.

Free Space Path Loss (FSPL)
+ Gaseous Absorption
+ Fade Margin
Receiver
Losses
Equivalent Receiver
Isotropically
Antenna
Receiver
Transmitter
Radiated
Gain
Power
(EIRP)
Figure 1: Fixed Link Budget
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8 ETSI TR 101 854 V2.1.1 (2019-04)
Rx Reference Sensitivity Level =
= Tx EIRP - FSPL - Fade Margin - Gaseous Absorption + Rx Antenna Gain - Rx Losses.
Tx EIRP =
= Rx Reference Sensitivity Level - Rx Antenna Gain + Rx Losses + Gaseous Absorption + FSPL + Fade Margin.
NOTE 2: Rx Losses are typically due to feeder losses connecting antenna port to indoor Rx equipment; when
outdoor equipment front ends are concerned, no Rx losses are usually present.
4.1.2 Receiver input level
The reference sensitivity calculated using the methodologies shown in tables 1 and 2 may be used as a theoretical guide
figure. The level of reference sensitivity in most practical cases will be within a few dB of this theoretical level. When
best practice noise figure and fixed losses are used in the calculation most, if not all, practical receiver reference
sensitivities will be at or above the theoretical level but below that quoted in the relevant European standard.
See annex D for guidance on S/N ratios and Noise Figure (NF) values.
Table 1 sets out an example calculation for RSL. This method of calculation may be used in conjunction with a noise
limited assignment system.
Table 1: Example showing calculation of RSL
Factor Notes Example values
Channel Bandwidth (MHz) 14
Payload rate (Mbit/s) 34,368
Gross bit rate (Mbit/s) ~ 1,1 x Payload rate (without FEC)
(including FEC and service channel) ~1,15 x payload rate (with FEC) = 1,15 × 34,368 Mbit/s 39,523
n
Modulation scheme
16 QAM (2 states, n = 4)
Thermal Noise kT (dBW/Hz) 10 log [k (Boltzmann's constant) × T (288 K)] -204
10 log [1,4 (Gross bit rate/n)]
Rx noise Bandwidth Factor B (dBHz) 71,4
= 10 log [1,4 (39,523 × 10 /4)]
Receiver Noise kTB (dBW) Thermal Noise (kT) + Bandwidth Factor (B) -132,6
Noise Figure (dB) See annex D 7
-6
S/N for BER = 10 (dB) See annex D 17,6
Fixed System Losses (dB) Assume 4 dB 4
Interference Margin (dB)
Assume 1 dB 1
(see clause 4.2.2)
kTB + Noise Figure + Fixed System Losses + Interference
-6
RSL for BER = 10 (dBW) -102
Margin + S/N
Median Rx Input Level (dBW) ≈ RSL plus calculated fade margin -102 + FM
NOTE 1: Where figures are quoted they are shown as an example and do not relate to any specific frequency band,
equipment type or European standard.
NOTE 2: Column 3 uses as an example a 34 Mbit/s, 16 QAM system with FEC and occupying a bandwidth of
14 MHz.
An alternative method for calculation of RSL is set out below. This approach calculates a normalized value of RSL
where the bit rate is normalized to a value of 1 Mbit/s and NF = 0 dB. The normalized RSL value may be calculated
using the well established equation (1), in conjunction with the example calculations set out in table 3:

( / ) = −114 +  +10∗  + (1)

where Noise Figure NF = 0 dB
The actual RSL (rated, typical value) may be calculated using equation (2):
( )= +10∗ + + +  (2)
where:
IM =
Noise Figure Industrial Margin in dB
F
IM =
S/N Industrial Margin in dB
s
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9 ETSI TR 101 854 V2.1.1 (2019-04)
Table 2 shows typical Noise Figures (inclusive of simple duplexers) and associated Industrial Margin values
(e.g. temperature extremes, production spread of FET devices and of RF circuits/filter attenuation) in the frequency
range: 6 GHz to 42 GHz. These values may be used in conjunction with equation (2).
-3
A value of 1 dB may be considered appropriate for the S/N Industrial Margin where the BER is in the range 10 to
-6
10 .
Typical S/N ratios (normalized to a noise bandwidth equal to the symbol-rate) are presented in table 3. Coded values are
valid for the referenced coding algorithm only; use of other coding algorithms would result in different S/N values and
different symbol-rates.
Table 3 gives two normalized RSL values with respect to each of the system coding examples shown, one based on a
-3 -6
BER = 10 and one based on a BER = 10 (derived from ETSI TR 103 053 [i.6], from table contained in archive
tr_103053v010101p0).
Table 2: Typical Noise Figures (NF) and associated Industrial Margins (IM )
F
Frequency band Typical Noise Figure (NF) Industrial margin (IM )
F
(GHz) (dB)
(dB)
1,3 to 3 ~4 +3
3 to 5 ~5 +3
6 to 15 ~5 +3
18 to 23 ~6 +3
26 to 28 ~7 +3
32 ~7 +3
38 to 42 ~8 +3
48 to 50 ~9 +3
52 to 55 ~10 +3
71 to 76 / 81 to 86 ~13 +4
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10 ETSI TR 101 854 V2.1.1 (2019-04)
Table 3: Examples of S/N normalized to the symbol rate and RSL normalized to NF = 0 dB and B = 1 Mbit/s
4CPM-2RC
Modulation format 4PSK 16 QAM 32 QAM 64 QAM 128 QAM
h = 0,25 (see note 1)
Coded Coded Coded Coded
Coded
Coded Coded Un- (16TCM- Un- (32TCM- Un- (64TCM- Un- (128TCM-
Coding (see note 3) Un-coded Un-coded (RS
(RS 255,243) (RS 255,243) coded 4D+RS coded 2D+RS coded 4D+RS coded 4D+RS
255,241)
255,243) 255,243) 255,243) 249,243)
B × (4/3,5) B × (5/4,5) × B × (6/5,5) × B × (7/6,5) × B ×
Gross Bit rate B B × (255/243) B B × (255/243) B B B B
× (255/243) (255/243) (255/243) (249/243) (255/241)
Symbol rate factor
2 2 2 2 4 4 5 5 6 6 7 7 7
"n"
(B/2) × (B/2) × (B/3,5) × (B/4) × (B/5,5) × (B/6,5) × (B/7) ×
Symbol rate B/2 B/2 B/4 B/5 B/6 B/7
(255/243) (255/243) (255/243) (255/243) (255/243) (249/243) (255/241)
-3
S/N (BER = 10 ) 13,5 12 11 9,6 18,2 13,2 21,5 15,2 24,5 19,9 27,6 24 27,2
-6
S/N (BER = 10 ) 17,5 14 14,2 10,5 21,3 13,7 25 16,4 28 20,5 31,4 25 28,5
-3
RSL at BER = 10
-103,5 -104,8 -106,0 -107,2 -101,8 -106,0 -99,5 -104,6 -97,3 -101,3 -94,9 -98,0 -95,0
(see note 2)
-6
RSL at BER = 10
-99,5 -102,8 -102,8 -106,3 -98,7 -105,5 -96,0 -103,4 -93,8 -100,7 -91,1 -97,0 -93,7
(see note 2)
B = Payload Bit-rate
NOTE 1: Technical background for Continuous Phase Modulation (CPM) formats may be found in ITU-R Recommendation SM.328-11 [i.4].
NOTE 2: Normalized to NF = 0 dB and B = 1 Mbit/s.
NOTE 3: Uncoded values = theoretically achievable values.
Coded values = typically measured in a mass production environment by one manufacturer (these are not the limits for testing, nor the guaranteed values provided to customers).

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11 ETSI TR 101 854 V2.1.1 (2019-04)
4.1.3 Fade margin (FM)
The two main factors considered that cause the wanted signal to fade are multipath clear air fading and rain fade.
Multipath clear air fading is considered dominant below about 10 GHz and rain fade is dominant above about 15 GHz.
Consequently, depending on the frequency band under consideration, the multipath, rain, or a combination of the two
fade margins, are calculated to ensure that system performance requirements are met. Fade margin is dependent on
frequency, path length and level of service availability required (see clause 4.1).
4.2 Interference assessment
4.2.1 General
The radio link to be assigned needs to be co-ordinated with all existing links within a defined co-ordination zone.
Interference levels into/from the new link need to be assessed and compared against defined limits,
ERC/REC(01)05 [i.10] gives common guidelines on limits for use in typical link planning. The co-ordination distance
is dependent on propagation conditions and therefore, in general, decreases as FS bands increase in frequency.
Interference levels to and from the proposed link are assessed taking into account such factors as receiver sensitivity,
path profile, antenna gain, antenna radiation pattern and antenna cross-polar response. When fitted, the operating profile
of ATPC also needs to be taken into consideration. The correct implementation of the ATPC profile into the assignment
process will significantly improve link density.
Interference levels to and from the proposed link are assessed taking into account such factors as receiver sensitivity,
path profile, antenna gain, antenna radiation pattern and antenna cross-polar response. When fitted, the operating profile
of ATPC also needs to be taken into consideration. The correct implementation of the ATPC profile into the assignment
process will significantly improve link density.
4.2.2 Wanted to Unwanted (W/U) ratios
Wanted to Unwanted (W/U) ratios are determined for each single interferer combination of wanted and unwanted signal
types. In a noise limited assignment system the correct inclusion of these figures, into the assignment link budget
calculation, will limit the increase in noise floor, caused by interference between FS systems sharing the same
frequency band, below a predetermined level.
The principle behind noise limited assignments is illustrated in figure 2. It shows the elements involved in determining
W/U for a single co-channel interferer. For interference scenarios where the wanted and unwanted channels are not
co-channel and have a degree of NFD (see clause 4.2.4) the W/U ratio is modified to take into account the additional
protection given by the NFD. The derivation of single interferer W/U ratios is covered in clause 4.2.5.
When link is first planned in absence of any significant interference (W/U  ∞), the inclusion of a multiple interferer
allowance may be appropriate. This additional protection takes into account the fact that the victim receiver is very
likely, in future, to experience new interference signals from a number of sources, in particular from multiple FS links
in the same co-ordination zone (e.g. interference margin up to 3 dB as provided by ECC/REC(01)05 [i.10]), but also
from emissions from other services sharing the same band; the latter contribution, if any, is defined by specific sharing
studies, based on Recommendation ITU-R F.758 [i.11], which, in most cases, are based on a globally permitted
I/N ≤ −10 dB, that would imply an additional protection of 0,5 dB.
ETSI
12 ETSI TR 101 854 V2.1.1 (2019-04)
-
Receive Signal Level (BER 10 )
Carrier Noise Ratio
Interference Margin
Receiver Noise Floor kTB
plus noise figure and other losses.
Wanted to
Unwanted Ratio Noise/Interference Ratio

Multiple Interference Allowance
Maximum Permissible Interference
Level for a single interferer
Figure 2: Derivation of single interferer co-channel interference limit
4.2.3 Receiver selectivity evaluation
An overall receiver selectivity mask for a given system type, obtained by a combination of RF, IF and base band
filtering, can, in theory, be derived from the corresponding transmitter spectrum mask. It is common practice for
digitally modulated systems to have Tx and Rx channel shaping such that, as far as possible, the ideal transfer function
for pulses with even attenuation characteristics is equally split between the Tx and Rx.
In the absence of specific equipment data the following two methods may be used to support link assignment:
- a conservative approach of the above method is shown in annex E;
- a more realistic approach of the above method is shown in annex F.
NOTE: These approaches should not imply supplementary requirements on the equipment.
4.2.4 Net Filter Discrimination (NFD)
It is common practice in co-existence studies between transmitters and receivers of different symbol rate and
modulation formats to use the concept of Net Filter Discrimination (NFD).
NFD is defined in Recommendation ITU-R F.746 [i.3] as (see notes 1 and 2):

NFD = (3a)
, ,
NOTE 1: The term "adjacent channel received power" is intended as the interfering power at antenna port (i.e.
without any filter contribution).
For the purpose of that Recommendation, it is formally defined for the adjacent channel separation, but it is common
practice to consider NFD concept extended to any frequency spacing between wanted Rx frequency and unwanted
interference frequency.
It is also common practice, when using C/I performance available in ETSI EN 302 217-2 [i.5], dealing with like wanted
and unwanted signals (i.e. with same CS and class of modulation), to consider NFD according to formula (3b) below,
(see notes 2 and 3):
NFD ≅ 10 log (Pc/Pa) (3b)
Where:
• Pc is the total interfering power received (in W and U operating at same frequency) after co-channel RF, IF
and base band filtering.
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13 ETSI TR 101 854 V2.1.1 (2019-04)
• Pa is the total interfering power received (in W and U operating at offset frequency) after offset RF, IF and
base band filtering.
NOTE 2: In the definition of NFD according 3a) and 3b) the following assumptions are made:
 adjacent channels XPD, if any, is not been taken into account;
 a single sideband interfering channel only is considered; for double side like-modulated
interferences a NFD 3 dB lower should be taken into account.
As pointed out in Recommendation ITU-R F.746 [i.3], this value is produced purely by the Tx spectrum and by the
overall Rx filtering. It does not include any other decoupling (e.g. antenna discrimination, XPD or the actual interfering
power level).
NOTE 3: Comparing equations (3a) and (3b) it is evident that the there is a slight difference represented by the
ratio:
! " # $%& ’()$ ( * +%#!$)
0 = ( );
,
however, in modern digital systems, where tight roll-off shaping is usually implemented, and when W
and U signals are alike, the factor is quite less than 1 dB.
When W and U signals are different, NFD(0) is not negligible and, when using formula (3b), should be
taken into account for NFD calculation as shown in clause 4.2.5.
When comparing to assessment parameters available in ETSI EN 302 217-2 [i.5], equations (3a or 3b) might be written
(see note 3) as:
..
≅ ℎ− (  ℎ ) (3c)
-" #
//
In formula (3c), de facto equivalent to formula (3b), the C/I (dB) are the prescribed values for 1 dB degradation of
-6
guaranteed threshold for BER=10 ; NFD value calculated with equation (3c) also represents a guaranteed value for all
equipment assessed according ETSI EN 302 217-2 [i.5] for RE Directive compliance.
For frequency planning purpose, an estimation of real NFD can be made using the following integral calculations.
(Reference to the diagrams in annex C will help the reader to understand the procedure).
With Tx and Rx masks aligned in the co-channel configuration (see topmost diagram in annex C):
1) Draw the transmitter spectrum mask and receiver filter mask. Integration step size to be dependent on the
bandwidth of the narrowest system.
2) Add corresponding Rx and Tx values. Obviously in practice the transmitted signal will experience a degree of
attenuation throughout its bandwidth, however minor, when processed through the filter (i.e. producing the
NFD(0) described in note 2 above). This step is purely a scaling exercise.
3) Convert decibel sum calculated in 2) to absolute.
4) Integrate the absolute values calculated in 3).
5) Offset the Tx mask as necessary and repeat action 1) to 4).
6) Divide the co-channel integral result by the offset integral result.
7) Convert the value found in 6) to a decibel value.
The actions above can be summarized in the following formula:

+2∆+2∆
=10∗  10 ∗ /10 ∗  (4)
01+-∆+-∆
Where:
• Tc = Interferent transmission power density mask shape - co-channel (dB)
• Rc = Wanted receiver attenuation mask - co-channel (dB)
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14 ETSI TR 101 854 V2.1.1 (2019-04)
• To = Interferent transmission power density mask shape - offset (dB)
• fo = Wanted RX centre frequency
• Δ = Suitable lower frequency with significant values of Rc, Tc or To
-
• Δ = Suitable upper frequency with significant values of Rc, Tc or To
+
It can be seen that, since:
+2∆+2∆
=10 ∗     and     =10 ∗ (5)
+-∆+-∆
Equation (4) is equivalent to equation (3b).
4.2.5 The Carrier to Interference (C/I) ratio in mixed payload environment
Figure 3 shows NFD values plotted against frequency separation. Values for mixed systems can be calculated and are
shown on the same graph. Where the transmission bandwidth exceeds receiver bandwidth i.e. not all the transmitted
power falls within the receiver bandwidth, a factor equal to 10 x log (bandwidth of interferer/bandwidth of victim)
needs to be applied when calculating the necessary wanted to unwanted ratio. Scenarios illustrating the change in NFD
for three systems using the same modulation order but transferring different traffic rates are shown:
1) When the traffic rate for an interferer is four times that of the victim the transmitted bandwidth will be four
times the receiver bandwidth. A bandwidth factor of 6 dB (10 x log 4) is added to the NFD.
2) When the interferer and the victim's rates are equal there is no bandwidth factor.
3) When the victim's bandwidth exceeds that of the interferer, the NFD out to approximately three times the mean
sum of both bandwidths will be below the value for "like with like" systems. This is because within this range
of frequencies the transmitted power lies within the receiver bandwidth over a greater number of channel
offsets.
NFD [dB] TX mask attenuation [dB]
TXrate/RXrate = ~6 dB
NFD [dB ]
= ~TX spectrum m ask
TX m ask
NFD with R X rate
(f loor attenuation)
= 1/4 TX rate
(ref.)
NFD with R X
rate = T X rate
NFD with R X rate
= 2 × TX rate
TXrate/RXrate
= ~6 dB
{TX-RX spacing}[MHz]
Figure 3: Qualitative examples of mixed NFD among different rate systems of the same class
ETSI
15 ETSI TR 101 854 V2.1.1 (2019-04)
Where a managing authority allocates channels and EIRPs that authority will ensure that the established network and
the new system will co-exist without degradation in system performance. This is achieved by keeping interference
levels below defined limits whilst ensuring that transmission EIRPs (see clause 4.1) are sufficient to maintain the
required level of system performance. The necessary protection is achieved by ensuring that the level of interference
from individual transmissions is kept below defined limits. These protection levels, the ratio between required signal
and interferer, are referred to as wanted to unwanted ratios. The evaluation of W/U is covered in clause 4.2.6.
4.2.6 Evaluation of the Wanted to Unwanted (W/U) ratios
NFD is evaluated at all possible frequency offsets and for all possible Tx and Rx system combinations. Once calculated,
the values are subtracted from the co-channel or in mixed systems, a co-channel-equivalent (i.e. when BW(U) >
BW(W), taking into account the bandwith ratio as shown in clause 4.2.5), W/U (see clause 4.2.2).
Tables of typical W/U ratios for two sets of systems combinations are given in annex B.
W/U = Co-channel/co-channel-equivalent W/U - NFD
5 Interference limited assignments
The noise limited approach described earlier makes two assumptions regarding the number of multiple interferers and in
addition it also sets a pre-determined level of noise floor degradation. Both of these elements can impose limitations and
can, in some cases, be overcome by the adoption of an interference limited approach. An explanation of this is given in
annex A.
6 Summary
The present document has concentrated on equipment performance and not considered the major contribution to
spectrum engineering made by the antenna. Obviously parameters such as off axis and cross-polar performance of
antennas in a mixed FS environment significantly affect the level of interference experienced by a victim receiver.
A generic approach has been taken although a modern computer based assignment system will provide facilities which
enhance link density by utilizing guaranteed performance when the guaranteed level exceeds the generic limit.
ETSI
16 ETSI TR 101 854 V2.1.1 (2019-04)
Annex A:
Interference limited assignments
The assumption that a specified number of multiple interferers are present when planning the interference margin in a
noise limited assignment system makes it necessary to add an additional protection margin to the N/I ratio.
For example, assume that the noise limited assignment system for co-channel operation is based on degradation in noise
floor of 1 dB (equivalent to a N/I of 6 dB) and that the multiple co-channel allowance assumes that the number of
multiple interferers is between 2 and 3. Thus the total N/I for a single co-channel interferer consists of 6 dB plus a
multiple element of 4 dB (10 log 2,5). In practice such a system will ensure that all co-channel interferers are limited
to 10 dB below noise floor. However, as the examples below demonstrate there will be occasions when single
interferers can breach the 10 dB threshold without a detrimental effect on link availability:
EXAMPLE 1: Assume two co-channel interferers: N/I of Int = 7 dB;
N/I of Int = 13 dB.
-0,7 -1,3
Cumulative increase in interference = 10 + 10 in relative terms = 0,249.
Degradation in noise = 10 log (1 + 0,249) = 0,967 dB.
EXAMPLE 2: When the number of multiple interferers exceeds the number assumed the level of interference
experienced is likely to exceed the theoretical level used for assignment purposes.
The interference limited approach can overcome the problems illustrated above. Interference limited assignment
systems calculate and record the cumulative interference level into each receiver. There are two possibilities which will
ensure the rejection of a new assignment. The first occurs when the establishment of an additional transmitter causes the
cumulative interference level into an established link receiver to exceed the assignment limit. Secondly the new
assignment may fail because one, or both, end/s of the link may be subjected to cumulative interference from the
established network, which exceeds the assignment limit.
Obviously a decrease in assignment N/I, resulting in an increase in interference margin, will resolve certain problems.
The resulting increase in Tx EIRPs and receiver C/I may improve link density. Two scenarios exist. The first covers the
situation where an increase in a single or very limited number of links EIRPs overcomes a specific problem. The
second, the global approach, requires a general increase in system EIRP throughout the network. Obviously the first
scenario will address local problems and have a limited effect on link density. The global approach can give significant
increases in the level of link density but is extremely difficult in practice to implement. A study within the UK Radio
communications Agency suggests that a one off EIRP increase to the order of 10 dB is necessary to obtain useful
benefits within a well-established network designed to operate with a 6 dB N/I ratio. Increases in EIRP of this order are
rarely feasible in practice.
A balance between power, path length and link availability is necessary. Simulations which estimate link density and
include elements for N/I ratio, transmitter output, receiver performance, antenna gain and profile, target path lengths,
link availability, system distribution, system losses, propagation losses and fade margins will help those involved with
spectrum engineering to define a practical level of N/I and thus noise degradation. Once the assignment criteria and the
network are established the scope for changes to criteria are very limited for the reasons mentioned previously.
In practice there is only a subtle difference between noise limited and interference limited assignments. An assignment
system which is truly interference limited will give some degree of flexibility to address local spectrum congestion but
will require a greater degree of sophistication. On a medium to large scale the additional sophistication will be
incorporated into the assignment system software. On a smaller scale, when manual assignments are undertaken, the
penalty will be time related. Different problems require different solutions. Spectrum engineers should assess the
problems in their area of responsibility and base their solution on the unique set of problems that they face.
ETSI
17 ETSI TR 101 854 V2.1.1 (2019-04)
Annex B:
Wanted to Unwanted (W/U) ratios
Tables B.1 and B.2, shown as examples, give the wanted to unwanted ratios for two system types. All possible
interference sources are shown and protection ratios out to at least three times the wanted channel spacing are shown.
When the wanted and unwanted channels of digital systems are not equal, Step 1 in the Wanted to Unwanted tables is
equal to 1/2 the narrowest bandwidth. Thereafter the step sizes are equivalent to the narrowest bandwidth. When the
wanted and unwanted channels are the same, all step sizes are equal to the bandwidth of these systems.
Table B.1: Wanted System 49 Mb/s in 14 MHz (38 GHz, 4H)
Unwanted
Spectral System
efficiency Wanted/Unwanted Ratio (dB) versus Step Size (see annex B)
Channel
class
Mbps Spacing
[MHz]
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14
2 4 3.5 30 30 23.6 -7.5 -9.6 -9.6 -9.6 -9.6 -9.6 -9.6 -9.6 -9.6 -9.6 -9.6 -9.6
2 8 7 30 29.6 -8.6 -12 -12.4 -12 -12 -12 -12 -12 -12 -12.4 -12 -12 -12.4
216 14 30 26.6 -14 -15 -14.7 -15 -15 -15 -15 -15 -15 -14.7 -15 -15 -14.7
2 32 28 33 32.4 0.1 -9.8 -12.2 -12 -12 -12 -12 -12 -12 -12.2 -12 -12 -12.2
4L 8 3.5 30 30 23.6 -8.7 -9.6 -9.6 -9.6 -9.6 -9.6 -9.6 -9.6 -9.6 -9.6 -9.6 -9.6
4L 16 7 30 29.7 -11 -12 -12.4 -12 -12 -12 -12 -12 -12 -12.4 -12 -12 -12.4
4L 32 14 30 26.6 -20 -21 -21 -21 -21 -21 -21 -21 -21 -21 -21 -21 -21
4H 49 14 30 26.6 -15 -15 -15 -15 -15 -15 -15 -15 -15 -15 -15 -15 -15
4L 64 28 33 32.6 -3.7 -11 -12.2 -12 -12 -12 -12 -12 -12 -12.2 -12 -12 -12.2
98 28 33 32.7 -7.1 -12 -12.2 -12 -12 -12 -12 -12 -12 -12.2 -12 -12 -12.2
4H
Table B.2: Wanted system 215 Mb/s in 28 MHz (11 GHz, class 8A)
Unwanted
Spectral System
efficiency Wanted/Unwanted Ratio (dB) versus Step Size (see annex B)
Channel
class
Mbps Spacing
[MHz]
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14
2 4 3.5 50 50 48.7 46.3 38.9 14 12 12.2 12.2 12.2 12.2 12.2 12.2 12.2 12.2
2 8 7 50 49.8 40.3 10.7 9.2 9.2 9.2 9.2 9.2 9.2 9.2 9.2 9.2 9.2 9.2
2 16 14 50 48.6 9.4 6.3 6.3 6.3 6.3 6.3 6.3 6.3 6.3 6.3 6.3 6.3 6.3
232 28 50 46.3 3.3 3.3 3.3 3.3 3.3 3.3 3.3 3.3 3.3 3.3 3.3 3.3 3.3
4L 8 3.5 50 50 48.7 46.3 38.8 8.4 3 2.4 2.3 2.3 2.3 2.3 2.3 2.3 2.3
4L 16 7 50 49.8 40.1 3.9 -0.7 -0.7 -0.7 -0.7 -0.7 -0.
...