ETSI TR 103 712 V1.1.1 (2020-10)

TECHNICAL REPORT
Fixed Radio Systems;
New PtMP technologies and solutions
for microwave backhaul in 5G era

2 ETSI TR 103 712 V1.1.1 (2020-10)

Reference
DTR/ATTM-0448
Keywords
5G, backhaul
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ETSI
3 ETSI TR 103 712 V1.1.1 (2020-10)
Contents
Intellectual Property Rights . 4
Foreword . 4
Modal verbs terminology . 4
Executive summary . 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 New requirement from 5G to microwave backhaul . 7
5 Key technologies to facilitate adaptation to the new requirements . 10
5.1 Active phase array antenna . 10
5.2 Beamforming . 11
5.3 Beam nulling . 13
5.4 Interference cancellation . 14
6 High frequency band with more frequency resource . 14
7 New PtMP structure to increase spectrum re-usability . 15
7.1 Introduction . 15
7.2 General overview . 15
7.2.1 General description of new PtMP structure . 15
7.2.2 Network topology . 16
7.2.3 Multiplexing method. 16
7.2.4 Multiple access method . 16
7.2.5 Duplex method . 16
7.3 Key technologies to enable new PtMP structure . 16
7.4 Technical characteristics . 17
7.5 Simulation . 18
7.5.1 Case 1 - 11 links . 18
7.5.2 Case 2 - 21 links . 20
7.5.3 Simulation conclusion. 24
8 License Scheme . 24
8.1 Introduction . 24
8.2 License scheme recommended for new PtMP structure . 25
8.3 Block assignment of 28GHz in Europe . 25
9 Test methodology . 25
Annex A: General beam nulling algorithms . 26
Annex B: Beam nulling simulation and lab test verification . 28
B.1 Introduction . 28
B.2 Simulation and lab test without applying any beam nulling . 28
B.3 Simulation and lab test with a null applied at 18° beside the main beam . 29
Annex C: Interference cancellation algorithms . 31
Annex D: RPE of active antenna used in simulations . 33
History . 36

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4 ETSI TR 103 712 V1.1.1 (2020-10)
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.
Executive summary
th
The 5 Generation of Access Network (5G) has raised new requirements for backhaul networks. Besides the traditional
solutions using higher frequency bands e.g. W/D bands, which are suitable to transport multi-Gbit/s over several
hundred meters due to large channel bandwidths but limited by almost flat gas attenuation and rain attenuation, a new
PtMP structure is applicable when transmission distance is for example from 1 km to 5 km, when the room for the
antennas is limited in the hub site and when it is not so easy to get higher frequency bands such as W/D band in some
country/area.
The new PtMP structure operates within traditional frequency bands where block license is allowed for traditional PMP
applications, such as 26/28/32/42 GHz, by using sectored multi-beam antennas to connect multiple leaf sites with a
variety of multiplexing method/ multiple access method such as TDM/TDMA, FDM/FDMA, SDM/SDMA or any
combinations of those above.
In the present document, the effectiveness of evolving new technologies enabling the new PtMP structure are discussed
and addressed. These include: phase array antenna, beam-forming/beam nulling, side lobe interference mitigation,
radiated test, etc.
Furthermore simulation results are provided to identify the appropriateness of new PtMP structure for backhaul
networks with longer transmission distance, reduced required antenna number, high transmission capacity and
adaptation to star-based topology in dense network area.

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5 ETSI TR 103 712 V1.1.1 (2020-10)
1 Scope
The present document discusses and addresses the effectiveness of evolving new technologies and new PtMP structures,
including phase array antenna, beam-forming/beam nulling, side lobe interference mitigation, and radiated test to
answer the challenges of the coming 5G backhaul network, in frequency bands above 50 GHz and lower frequency
bands where PtMP/block license is allowed, such as 26/28/32/42 GHz.
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] ECC Report 173 (04-2018): "Fixed Service in Europe Current use and future trends".
[i.2] Recommendation ITU-R M.2083-0: "IMT Vision - Framework and overall objectives of the future
development of IMT for 2020 and beyond".
[i.3] ETSI White Paper No. 25 (first edition): "Microwave and Millimetre-wave for 5G Transport".
rd
[i.4] 3GPP TS 38.141-2 (V16.2.0): "3 Generation Partnership Project; Technical Specification Group
Radio Access Network; NR; Base Station (BS) conformance testing Part 2: Radiated conformance
testing".
rd
[i.5] 3GPP TR 38.803 (V14.2.0): "3 Generation Partnership Project; Technical Specification Group
Radio Access Network; Study on new radio access technology: Radio Frequency (RF) and co-
existence aspects".
rd
[i.6] 3GPP TS 37.145-2 (V16.3.0): "3 Generation Partnership Project; Technical Specification Group
Radio Access Network; Active Antenna System (AAS) Base Station (BS) conformance testing;
Part 2: radiated conformance testing".
[i.7] ETSI White Paper No. 15 (second edition): "mmWave Semiconductor Industry Technologies:
Status and Evolution".
[i.8] ECC Report 282: "Point-to-Point Radio Links in the Frequency Ranges 92-114.25 GHz and
130-174.8 GHz".
[i.9] Recommendation ITU-R P.837-7: "Characteristics of precipitation for propagation modelling".
[i.10] Recommendation ITU-R P.530-17: "Propagation data and prediction methods required for the
design of terrestrial line-of-sight systems".
[i.11] ETSI GR mWT 008: "millimetre Wave Transmission (mWT); Analysis of Spectrum, License
Schemes and Network Scenarios in the D-band".
[i.12] ETSI GR mWT 018: "Analysis of Spectrum, License Schemes and Network Scenarios in the
W-band".
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6 ETSI TR 103 712 V1.1.1 (2020-10)
[i.13] ECC Recommendation 18(01): "ECC Recommendation of 27 April 2018 on radio frequency
channel/block arrangements for Fixed Service systems operating in the bands 130-134 GHz,
141-148.5 GHz, 151.5-164 GHz and 167-174.8 GHz".
[i.14] ECC Recommendation 18(02): "ECC Recommendation of 14 September 2018 on radio frequency
channel/block arrangements for Fixed Service systems operating in the bands 92-94 GHz,
94.1-100 GHz, 102-109.5 GHz and 111.8-114.25 GHz".
[i.15] ECC Recommendation (11)01: "ECC Recommendation of 2 February 2011 on guidelines for
assignment of frequency blocks for Fixed Wireless Systems in the bands 24.5-26.5 GHz,
27.5-29.5 GHz and 31.8-33.4 GHz".
[i.16] ECC Recommendation T/R 13-02: "Recommendation T/R of 1993 on preferred channel
arrangements for fixed service systems in the frequency range 22.0-29.5 GHz, revised
15 May 2010 and amended 29 May 2019".
3 Definition of terms, symbols and abbreviations
3.1 Terms
Void.
3.2 Symbols
Void.
3.3 Abbreviations
For the purposes of the present document, the following abbreviations apply:
5G fifth Generation of mobile networks
ADC A/D-Converter
BEM Block Edge Mask
CIR Committed Information Rate
CMOS Complementary Metal Oxide Semiconductor
DAC D/A-Converter
DPD Digital Pre-Distortion
DSP Digital Signal Processing
EIRP Equivalent Isotropically Radiated Power
FDD Frequency Division Duplex
FDM Frequency Division Multiplexing
FDMA Frequency Division Multiple Access
FSL Free Space Loss
IMT International Mobile Telecommunication
LOS Line Of Sight
MP Multi Point
PIR Peak Information Rate
PMP Point to Multi Point
QAM Quadrature Amplitude Modulation
QPSK Quadrature Phase Shift Keying
RF Radio Frequency
RPE Radiation Pattern Envelope
SDM Space Division Multiplexing
SDMA Space Division Multiple Access
SINR Signal to Interference and Noise Ratio
SNR Signal to Noise Ratio
TDD Time Division Duplex
TDM Time Division Multiplexing
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7 ETSI TR 103 712 V1.1.1 (2020-10)
TDMA Time Division Multiple Access
XPIC cross Polarization Interference Cancelling
4 New requirement from 5G to microwave backhaul
Mentioned by many administrations and companies, 5G (IMT-2020) has been initialized at the end of 2019 or in 2020
depending on different countries. As the latest mobile technology, 5G (IMT-2020) has raised new requirements to its
backhaul networks, especially microwave backhaul. Figure 1 is the famous requirements of 5G (IMT-2020) network,
described in Recommendation ITU-R M.2083-0 [i.2]. From the analysis of the figure, the following requirements to
microwave backhaul can be seen.
User experienced
Peak data rate
data rate
(Gbit/s)
(Mbit/s)
20 100
IMT-2020
Area traffic
Spectrum
capacity
efficiency
(Mbit/s/m )
3×
1×
0.1
1×
10× 400
100×
IMT-advanced
Mobility
Network
(km/h)
energy efficiency
Connection density Latency
(ms)
(devices/km )
M.2083-03
Figure 1: Enhancement of key capabilities from IMT-Advanced to IMT-2020
1) Capacity requirement. From Figure 1 above, it can be seen that the user experienced data rate will grow
10 times in 5G (IMT-2020) than in 4G (IMT-advanced). And furthermore, the peak data rate will even grow in
a higher speed, 20 times in 5G (IMT-2020) than in 4G (IMT-advanced). And then researches have been done,
from typical macro sites to small-cells, from dense area to urban area, from tail links to aggregation links, to
determine the transport capacity requirement across the network. The result, showing the backhaul capacity
requirement of 5G site, has been published in table 1, by ETSI mWT in ETSI White Paper No. 25 [i.3].
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8 ETSI TR 103 712 V1.1.1 (2020-10)
Table 1: Backhaul capacity requirement of 5G site

2) Topology requirement. Also from Figure 1, area traffic capacity and connection density are both increasing in
a large scale, which brings the site densification. Meanwhile, the fibre is penetrating to the edge of the
network. The above two aspects have two main effects:
- Shortening of chains of cascaded radio links as the number of hops from microwave site to fibre is
getting less, approaching the limit of one radio link to the fibre.
- Increase of the number of links originating from a hub site to the leaf sites.
In general, these considerations lead to define different network segments:
- Dense Urban and Urban scenarios: where previously the network was based on a hub-and-spoke kind of
topology, there is a strong increase in fibre Points of Presence (PoP), from which a star topology of high
capacity tail links originate; the fan-out of such hubs tends to be high. The depth of the MW/mmW
network tends to become 1 to 1,5 hops from the fibre PoP.
- Sub-urban scenarios: the trend is the same, but here the MW/mmW network depth is going towards an
average of 1,5 to 2 hops from the fibre PoP.
- Rural scenarios: here the variance will be greater due to the widely different geographical conditions, but
it is expected that the average network depth should tend towards 2,5 hops from the fibre PoP.
- Mixed scenarios: in some places, it may happen that a small cluster of urban or suburban sites are
situated at a certain distance from the fibre PoP, so that the MW/mmW link length for the aggregation
link towards the PoP is not directly related to the cell radius.
As a result, the network topology, especially in dense area, is evolving from linear style to a star-based, high-
capacity, and shorter distance style as shown in Figure 2. This kind of backhaul is expected to be characterized
by variable behaviour, also closer to the access behaviour than for traditional backhaul. Traffic asymmetry,
time variability, weather and style of living- dependent characteristics can be examples of possible sources of
variability. Such new backhaul requirements could be possibly addressed by using links /network
configurations other than point to point.
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9 ETSI TR 103 712 V1.1.1 (2020-10)

Figure 2: Topology evolution in the backhaul network
3) Mitigation of heavy burden of antenna on installation sites. Frequency resource is limited, and site resource for
antennas is also limited. As for traditional PtP microwave service, each link will use one pair of parabolic
antennas. As capacity increases and network topology evolves to star-based style, the number of links will
increase at hub site, and then the number of antennas increases accordingly at hub site. As a result, more
weight and more space are required for antenna installation site to accommodate the increasing antennas, as
shown in Figure 3.
However, the weight and space that the antenna installation site can provide is limited. In most countries, the
number of antennas at the site is strictly constrained, and the application of adding new antennas on the site is
also under stringent control. So the mitigation of heave burden of antenna installation site and easier
installation of antennas should be taken into consideration, especially at the hub site in dense-populated area
and installation over residential building.

Figure 3: More antennas on installation site
According to the analysis above, traditional PtP microwave system can hardly meet the new requirements. Along with
the development of communication industry, there are several new technologies emerging now, which can facilitate the
adaptation to the new requirements.
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5 Key technologies to facilitate adaptation to the new
requirements
5.1 Active phase array antenna
The active phase array antenna is an array of antenna elements designed to change the antenna radiation pattern in order
to adjust the shape and direction of the beam. In an active phase array antenna, the RF signal from the transmitter is fed
to the individual antenna with the correct phase relationship so that the radio waves from separate antennas adding
together increase the radiation in a desired direction, while cancelling to suppress radiation in undesired directions. In a
phased array, the power from the transmitter is fed to the antennas through beamforming technology described in
clause 5.2 in the present document, which can alter the phase electronically, thus steering the beam combination of
radio waves to a different direction.
An active phase array antenna contains antenna array and Digital Signal Processing (DSP) running algorithms, and then
make it possible for the antenna to transmit and receive signals to perform adaptation in a desired way, shown in
Figure 4. A typical block diagram of a T/R module for an antenna element in an active phase array antenna in shown in
Figure 5.
Figure 4: Block diagram of an active phase array antenna

Figure 5: Block diagram of a T/R module for an antenna element in an active phase array antenna
As active antenna contains active components which are much smaller than passive components, active phase array
antenna can integrate multiple array antennas inside as shown in Figure 6, with comparable size to the traditional
parabolic antenna, and then make multi-antenna array implementation possible, thereby reducing the number of
antennas at hub site.
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11 ETSI TR 103 712 V1.1.1 (2020-10)

Figure 6: Parabolic antenna and integrated phase array antenna
5.2 Beamforming
Beamforming is a signal processing technology used to change the direction and the shape of radiation pattern of the
array antenna for either signal transmission or signal reception. It is achieved by combining elements in the array in a
way where signals at particular angles experience constructive interference and while others experience destructive
interference.
Beamforming technology is used in the new PtMP structure introduced in clause 7 to automatically make alignment
with hub site and leaf site. Figure 7 shows the internal diagram of beamforming. Multiple RF channel signals are
transmitted at the same time and are combined in the air. The amplifier and phase shifter of each RF channel could be
adjusted, in order to change the shape and phase of the beam, and then change the pointing direction of the beam
combination.
Figure 7: Internal diagram of beamforming
Figure 8 shows the operation interface and illustration of beamforming. If the four array antennas are kept with the
same phase in the left figure, the combination beam just goes straight. If the phase of four array antennas are changed in
the right figure, the combination beam will change its direction accordingly.

Figure 8: Operation interface and illustration of beamforming
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12 ETSI TR 103 712 V1.1.1 (2020-10)
Along with the technology development, there are several kinds of beamforming implementations:
• Analogue beamforming
Analogue beamforming typically consists of only one RF chain and only one couple of ADC/DAC (converters) and
multiple analogue phase shifters that feed an antenna array, shown in Figure 9. It holds the advantages of low cost,
simple structure and easy implementation, but could only produce one single beam combination at a time, and also is
limited to power and performance as analogue phase shifter is used.

Figure 9: Analogue beamforming
• Digital beamforming.
Digital beamforming consists of multiple RF chains and multiple digital amplitude and phase shifters that feed an
antenna array. In this architecture each RF chain is connected to digital converters (i.e. ADC and DAC), as shown in
Figure 10. It holds more sophisticated structure than analogue beamforming, and then has higher cost and higher power
consumption accordingly. However, digital beamforming can produce multiple beam combinations simultaneously, as
each antenna element fed by a digital amplitude and phase shifter is connected to a RF chain. And also due to this
structure, one signal could be distributed to all antenna elements through digital amplitude and phase shifter, and then
could take advantage of the total gain from all the antenna elements, as a result to achieve high transmitting power. As
digital shifter has higher accuracy than analogue shifter and DPD could be used, the RF performance would be
increased.
Figure 10: Digital beamforming
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13 ETSI TR 103 712 V1.1.1 (2020-10)
• Hybrid beamforming
In order to acquire balance between cost, power assumption and performance, hybrid beamforming is introduced, in
which, several antenna elements fed by an analogue phase shifter are connected to a single RF chain to form a
sub-array, and then several sub-arrays connected to digital amplitude and phase shifters form an antenna array, shown in
Figure 11.
Figure 11: Hybrid beamforming
5.3 Beam nulling
Beam nulling technology is another way to reduce the interference. It is used to suppress interference which is achieved
by inserting nulls in the RPE of phase array antenna in the direction of the interferences. When the main lobe of the
target signal falls on the side lobes of the current signal, the side lobes would interfere with the target signal. The weight
of each sub-antenna of the current signal is obtained by specific algorithms, so that the SINR of current antenna array is
maximized in the desired direction, in the condition that the main lobe power of the current signal is kept unchanged,
and then the side lobes are suppressed and the interference to the target signal is reduced.
An example is shown below. The network topology is depicted in Figure 12. 5 leaf sites are connected to hub site. L1 is
the current signal, and L2 to L5 are the target signals. It is assumed that the main lobes of L2 to L5 just fall on the side
lobes of L1. Then the side lobes of L1 would cause interference to the main lobes of L2 to L5.

Figure 12: Network topology of an example of beam nulling
In order to minimize the interference from L1 impacting L2 to L5, specific algorithms are implemented in L1, to
maximize the SINR. The other links apply the same mechanism in the other directions. The antenna radiation pattern of
L1 after nulling algorithms is shown in Figure 13.
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14 ETSI TR 103 712 V1.1.1 (2020-10)

Figure 13: Antenna radiation pattern of L1 after nulling algorithms
See Annex A for more details of general algorithms.
See Annex B for simulation and lab test verification.
5.4 Interference cancellation
As multi-beam is used, each beam can cause mutual interference to the other beams, and then SINR and capacity may
decrease in victim beams. To solve this problem, interference cancellation technology is introduced.
According to different transmission directions, there are two types of interference cancellation technologies.
The first type is from leaf sites to hub site. As all the signals from each link connected to leaf sites are received by hub
site, interference cancellation is implemented in the receiving direction at hub site, by exchanging signals received from
each leaf site to eliminate the accompanying interference, with utilization of channel matrix obtained through channel
estimation algorithm.
The second type is from hub site to leaf sites. As the leaf sites are far away from each other, it is impossible to send
signal from one leaf site to another leaf site. Then interference cancellation is implemented in the transmitting direction
at each leaf site, by pre-coding the interference cancellation signal into the transmitting signal, with utilization of
channel matrix obtained through channel estimation algorithm.
See Annex C for more details of general algorithms.
Note, for all the technologies introduced above, they are frequency independent and thus can be used in any frequency
bands.
6 High frequency band with more frequency resource
To meet the new requirements from 5G to microwave backhaul, one way is to continue the exploration in higher
frequency bands such as W band (92 to 94 GHz, 94,1 to 95 GHz, 95 to 100 GHz, 102 to 109,5 GHz and 111,8 to
114,5 GHz), and D band (130 to 134 GHz, 141 to 148,5 GHz, 151,5 to 164 GHz and 167 to 174,8 GHz). Naturally,
more frequency resource are available in these higher frequency bands, which brings more transmission capacity.
The characteristics of W band and D band have been studied by CEPT and ETSI in recent years. Refer to ECC
Report 282 [i.8] and ETSI GR mWT 008 [i.11] for D band and ETSI GR mWT 018 [i.12] for W band for details. And
also the channel arrangements have been studied and published by CEPT, in ECC Recommendation 18(01) [i.13] for D
band and ECC Recommendation 18(02) [i.14] for W band.
Solutions implemented by some of the key technologies introduced above in clause 5 in the present document,
including active phase array antenna, beamforming, etc., could be used in W band and D band systems to make better
antenna alignment as the beam in such high frequency band would be significantly narrow.
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15 ETSI TR 103 712 V1.1.1 (2020-10)
From the study above, it can be seen that, the transmission distances in W band and D band with the condition
1 Gbps/250 MHz & 1 000 MHz/99,9 % & 99,99 %/QPSK are less than 1 km. And in higher condition
10 Gbps/64 QAM, the transmission distances are around 200 m to 400 m. There are more than 16 GHz of spectrum
available in the W-band, and more than 30 GHz of spectrum available in the D-band. According to large channel
bandwidths and almost flat gas attenuation and rain attenuation, W band and D band are suitable for transmitting multi-
Gbps in dense urban scenarios. Possible use of the W band in dense urban scenarios to allow capacities up to few Gbps
is observed as less capable than the D band, due to the minor amount of available spectrum, and the higher
fragmentation compared to D band.
7 New PtMP structure to increase spectrum re-usability
7.1 Introduction
To meet the new requirements from 5G to microwave backhaul, another way, when transmission distance is for
example from 1 km to 5 km, the number of antennas is limited in the hub site, and it is not so easy to get higher
frequency bands such as W/D band in some country/area, is to make full use of the traditional bands from 6 GHz to
42 GHz in hands.
7.2 General overview
7.2.1 General description of new PtMP structure
A new PtMP solution is a concept to meet the new requirement from 5G to microwave backhaul, through high capacity
transmission, adaptation to new star-based network topology with reduced number of antennas, and easy installation
with automatic antenna alignment.
The new PtMP structure is shown in Figure 14. Hub site uses sectored multi-beam antennas to connect leaf sites. Each
°
sectored multi-beam antenna covers and holds n flows connected to k leaf sites. The multiplexing method could be
TDM, FDM, SDM, or any combinations of those above. The multiple access method could be TDMA, FDMA, SDMA,
or any combinations of those above.

Figure 14: General structure of new PtMP systems
A logical scheme of the new PtMP solution includes increased frequency re-usability, beamforming technology and use
of active phase array antenna.
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16 ETSI TR 103 712 V1.1.1 (2020-10)
Increasing transmission capacity by increasing frequency re-usability is reasonable as the frequency resource is limited
in traditional bands. Using active phase array antenna can greatly reduce the number of antennas in the antenna
installation sites. Active phase array antenna, together with beamforming technology, enable multi-beam adjustable in
hub site, to facilitate automatic antenna alignment.
7.2.2 Network topology
The new PtMP structure is a typical Point-to-Multipoint network topology, which provides a communication route
(on a single radio channel in each sector) from hub site to a number of leaf sites. Each hub site is either served directly
from the hub site or via one or more radio repeaters. In general, each leaf site communicates with hub site by a single
pathway.
7.2.3 Multiplexing method
Multiplexing method is used to multiplex together the signals from a central station to a number of Terminal Stations to
allow the radio medium to be shared effectively between the various traffic paths typically under the control of the
central station. The hub site of new PtMP structure could transmit signals simultaneously in all links to leaf sites with
the same frequency band, so the multiplexing method would contain SDM (Space Division Multiplexing), in which
physical separation of transmitting (antennas) is used to deliver simultaneously different data streams from central
station to multiple terminal stations.
7.2.4 Multiple access method
Multiple access method is used to provide multiple access from a number of terminal stations to one central station, thus
sharing the available radio capacity into the central station between the traffic requirements of the terminal stations. The
leaf sites of new PtMP structure could send signals simultaneously to hub site with the same frequency band, so the
multiple access method would contain SDMA (Space Division Multiple Access), in which physical separation of
transmitting (antennas) is used to deliver simultaneously different data streams from multiple terminal stations to central
station.
7.2.5 Duplex method
Duplex method is used to separate the two directions of signal in a bi-directional link. In the new PtMP structure, both
TDD - Time Division Duplex and FDD - Frequency Division Duplex could be used as duplex method.
7.3 Key technologies to enable new PtMP structure
The new PtMP structure integrates key technologies introduced above in clause 5 in the present document, to better
meet the new requirements from 5G backhaul.
Multiple beams pointing to different desired directions are produced, in order to connect to multiple leaf sites and make
antenna automatic alignment, through active phase array antenna and beamforming technologies.
To enhance the frequency re-usability, beam nulling and interference cancellation technologies are used to minimize the
mutual interference between each two links, and then achieve reducing the minimum angle between two links with the
same frequency band.
Finally, the new PtMP structure becomes possible with multiple links from hub site to leaf sites in the same frequency
band inside one antenna as well as antenna automatic alignment between hub site and leaf sites.
A simple example is shown below. A star topology network with hub site connecting to 17 leaf sites is showing in
Figure 15.
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17 ETSI TR 103 712 V1.1.1 (2020-10)

Figure 15: Example network
If new PtMP structure is implemented in this network, only one frequency band and 3 active phase array antennas are
used to connect all the leaf sites to hub site, as shown in Figure 16. And also antenna installation becomes much easier
as automatic beam alignment is implemented.

Figure 16: Antennas used in the hub site
7.4 Technical characteristics
As analysed above, new PtMP structure can exploit the technique achievements of 5G backhaul requirement, and
possesses its own unique characteristics, which would gain interests from users who can benefit from these
characteristics.
New multiplexing method and new multiple access method are introduced in new PtMP structure - SDM (Space
Division Multiplexing) and SDMA (Space Division Multiple Access). SDM enables delivering different data streams
simultaneously from central station to multiple terminal stations by physical separation of transmitting (antennas), and
SDMA enables delivering different data streams simultaneously from multiple terminal stations to central station by
physical separation of transmitting (antennas). In this way, frequency re-usability and transmission capacity could be
increased in a certain area, comparing to the traditional TDM/TDMA, FDM/FDMA, etc.
As one trend of antenna technology, active antenna is frequently discussed in many applications in microwave industry,
and is also introduced in new PtMP structure, to enable flexibly connection from hub site to leaf sites, reduce the
number of antennas at hub site and make auto alignment possible.
Since the new PtMP system uses different multiplexing method/access method and adopt new technologies such as
active antenna, the characteristics of new PtMP may show some difference from traditional PmP structure. The new
PtMP system consists of thousands of T/R modules, in which high integration process (BiCMOS, CMOS) is usually
required to reduce the size and power consumption. As discussed in ETSI White Paper No. 15 [i.7], SiGe BiCMOS
technology is well suited for highly integrated mmWave systems, especially, mmWave phased array transceivers.
BiCMOS exploits its integration capabilities, not only reducing the number of chips to be assembled in the phased array
but also greatly simplifying the control routing in large arrays. As a result, the introduction of high integration process
brings different system performance in terms of noise figure, channel linearity and gain, etc., to traditional progress
such as GaAs.
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18 ETSI TR 103 712 V1.1.1 (2020-10)
7.5 Simulation
7.5.1 Case 1 - 11 links
To verify the performance of new PtMP structure with 5G requirement, simulation has been done. The target network is
shown in Figure 17. It has one hub site, and total 11 leaf sites. The capacity requirement for each link is 200 Mbps in
average at availability of 99,995 %, and 1Gbps at peak at availability of 99,98 %. The channel model used for the
simulations is pure Line Of Sight (LOS). Thus, usual Free Space Loss (FSL) attenuation is computed. The environment
assumptions are listed in Table 2 below, according to Recommendation ITU-R P.837-7 [i.9] and Recommendation
ITU-R P.530-17 [i.10].
Table 2: Environment assumptions
PARAMETER VALUE NOTE
Water Vapor Density 7,5 g/m
Temperature 15 °C
Pressure 1 013,25 hPa
Refractivity Gradient -790,549 N units/km
Rain Rate 47,2 mm/h 0,01 % probability

The distance, angle and height information are listed in Table 3.

Figure 17: Target network for simulation
Table 3: Distance, angle and height information of target network
Leaf Leaf sites Hub site height (m)
Distance (km) Angle (°)
No. height (m)
1 1,04 37,7 256 273
2 2,60 41,4 291,5 273
3 2,67 41,9 271 273
4 3,07 26,3 241,2 273
5 3,84 32,7 235,4 273
6 2,16 12,8 225,5 273
7 1,32 18,6 231 273
8 1,75 20 201 273
9 1,68 32,1 179 273
10 1,26 34,1 214 273
11 1,22 62,3 266 273
NOTE: The distances which are greater than 3 km are shown in light blue cells.

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19 ETSI TR 103 712 V1.1.1 (2020-10)
Simulation based on new PtMP structure has been done, by using traditional band of 28 GHz. The target network has
been divided into 3 sectors as shown in Figure 18, as inter-sector interference has been taken into consideration. Beam
nulling has also been done to reduce the inter-sector and intra-sector interference. In each sector one phase array
antenna with 8 data streams (possible beams) is used to cover all the leaf sites inside. A phase array antenna contains 8
sub-array antennas, and in each sub-array antenna there are 16×20 antenna elements inside, with 8 dBi antenna gain for
each antenna element. Hybrid beamforming is used in the simulation to steer beams from hub site to leaf sites, and
implement antenna automatic alignment. The system parameters are shown in Table 4 below.
NOTE: In the system shown in this case there are 8 streams with 16×20 antenna elements in each active antenna,
which means that the whole hub site will use 3×2 560 antenna elements with phase and/or amplitude
control. The distance between the centres of two single antenna elements is from 0,5 λ to 0,8 λ depending
on implementation.
Table 4: System parameters of new PtMP simulation
PARAMETER VALUE NOTE
EIRP 56 dBm QPSK
50 dBm 16 to 256-QAM
SNR 5 dB QPSK
29 dB 256-QAM
Noise Figure 8,5 dB
Figure 18: Division of target network
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20 ETSI TR 103 712 V1.1.1 (2020-10)
The simulation
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