Collocation and co existence guideline

Colocation and Coexistence Guideline
FDD
RECOMMENDATION
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Copyright
© Ericsson AB 2009-14. All rights reserved. No part of this document may be
reproduced in any form without the written permission of the copyright owner.
Disclaimer
The contents of this document are subject to revision without notice due to
continued progress in methodology, design and manufacturing. Ericsson shall
have no liability for any error or damage of any kind resulting from the use
of this document.
Trademark List
All trademarks mentioned herein are the property of their respective owners.
These are shown in the document Trademark Information.
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Contents
Contents
1 Introduction 1
1.1 Interference Scenarios 1
1.2 Inter-Modulation Products 3
1.3 Assumptions 3
1.4 Limitations 5
1.5 Concepts 5
2 Theory 11
2.1 Operating Band Protection 11
2.2 Isolation between Systems 11
2.3 System Degradation 13
2.4 Isolation against Spurious Emissions 14
2.5 Isolation against Blocking 15
3 3GPP Recommendations 17
3.1 Adjacent Channel Blocking 17
3.2 Spurious Emissions 17
3.3 Blocking 18
4 Calculation Examples 21
4.1 Isolation against LTE Spurious Emissions 21
4.2 Isolation against Blocking towards LTE 22
4.3 LTE Spurious Emission Level 22
4.4 LTE Sensitivity Degradation 22
4.5 Interpreting Results and Recommended Actions 23
5 Colocation and Coexistence for E-UTRA 25
5.1 Spectrum Allocation 25
5.2 E-UTRA with E-UTRA 26
5.3 E-UTRA Band 7 with GSM 1800 27
5.4 E-UTRA Band 7 with UTRA Band I 28
5.5 E-UTRA Band 13 with CDMA2000 Band 0 29
6 Solutions 31
6.1 Restrictions in the Operating Band 31
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6.2 Interference Rejection Combining 33
6.3 Guard Bands 34
6.4 Filters 35
6.5 Colocation Solutions 35
7 Spectrum Refarming 37
7.1 Interference Control 37
7.2 Spectrum Recommendations 38
7.3 Channel Spacing Recommendations 39
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Introduction
1 Introduction
System degradation may occur due to interference when LTE systems are
colocated or coexist with different mobile telecommunications systems including
LTE.
Colocation is when two or more base stations share the same site. Coexistence
of deployed base stations means that the base stations have separate sites but
share the same geographical area.
Different radio access technologies or the same radio access technologies
with different operators may be deployed in the same geographic area.
When mobile telecommunications systems are colocated or coexist, certain
precautions must be considered to minimize the interference impact and avoid
system degradation.
This document presents concepts, scenarios and precautions required when an
LTE system and systems of one or more other technologies are colocated or
operate in the same geographical area.
This document gives a theoretical platform to further analyze the colocation
and coexistence scenarios that can occur in the field. It aims to provide a
deeper understanding of the possible impact between systems and how to
minimize system performance degradation. The intention is not to present
fixed solutions, because every scenario is unique, but to offer a toolbox to use
in specific scenarios.
1.1 Interference Scenarios
When two systems are colocated or deployed in the same geographic area,
harmful interference that can degrade system performance may occur between
them:
• Base station to base station
• Base station to User Equipment (UE)
• UE to base station
• UE to UE
The following illustration shows possible interference scenarios between two
systems. The dashed arrows represent the communication between UE and its
own base station in the appropriate network. The continuous arrows represent
the interference.
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L0000154A
RBS 1 RBS 2
UE 2 UE 1
Figure 1 Interference between Two Mobile Systems
Three fundamental interference issues must be considered:
• Spurious emissions; the unwanted emissions from a transmitting system
degrading the performance of a receiving system.
• Blocking, a measure of the receiver ability to receive a wanted signal at its
assigned channel in the presence of an unwanted interferer
• Isolation between systems
The interference between base stations is highly deterministic, while the
interference between the user equipment or between base stations and UE is
statistical due to mobility of the UE.
For the base station to UE scenario, an essential issue is the Near-Far effect.
Assume an LTE system is deployed in the same geographical area using
adjacent frequency blocks.
In Figure 2, system A represents the LTE system and system B represents a
system of another technology. When a UE from system A is located near a
base station from system B, it can cause interference for the receiver of the
system B base station, and the reverse is also true. When the UE of system
A is located far away from the base station of system A, but close to the
base station of system B, significant interference can occur, because the UE
transmits at high power to overcome the high path loss. If different operators
colocate base stations on the same sites, the Near-Far effect is eliminated.
L0000155A
System B System A
A
Figure 2 Near-Far Effect
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Introduction
1.2 Inter-Modulation Products
Inter-Modulation (IM) products are created when two or more frequencies mix
in nonlinear devices in the transmit or receive path. IM products of order n are
the sums and differences in n terms of the original frequencies. The strengths
of the IM products decline with higher orders. To avoid third order IM, the
frequencies should be planned so that no IM in Rx occurs.
1.3 Assumptions
The following assumptions are valid for this guideline:
• Colocation and coexistence between LTE Frequency Division Duplex
(FDD) and Time Division Duplex (TDD) and the following technologies:
0 LTE, FDD with FDD and FDD with TDD
0 GSM
0 WCDMA
0 CDMA2000
• The 3GPP operating bands for E-UTRA are shown in Table 1 and Table 2.
Examples for the operating bands 7, 13 and 38 are given in this guideline.
• All available channel bandwidths are considered.
• Requirements from 3GPP are used for isolation and spurious emission.
Ericsson complies with 3GPP with even better performance.
• The following deployment scenarios are discussed:
0 Colocation
0 Coexistence
0 Coordinated scenario
0 Uncoordinated scenario
• All recommendations are valid for single radio access technologies as well
as Multi Standard mixed mode.
Table 1 3GPP E-UTRA Operating Bands, FDD
Band Identifier UL Frequency [MHz] DL Frequency [MHz] Note
1 IMT core band 1920-1980 2110-2170
(1)
2 PCS 1900 1850-1910 1930-1990
(1)
3 GSM 1800 1710-1785 1805-1880
(1)
4 AWS (US & other) 1710-1755 2110-2155
(1)
5 850 824-849 869-894
(1)
6 850 (Japan) 830-840 875-885
(1)
7 IMT extension 2500-2570 2620-2690
8 GSM 900 876-915 921-960
(1)
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Band Identifier UL Frequency [MHz] DL Frequency [MHz] Note
9 1700 (Japan) 1750-1785 1845-1880
(1)
10 3G Americas 1710-1755 2110-2155
(1)
11 1500 lower (Japan) 1427.9-1452.9 1475.9-1500.9
(1)
12 700 (USA) 698-716 728-746
(1)
13 700 (USA) 777-787 746-756
14 700 (USA) 788-798 758-768
(1)
17 700 (USA) 704-716 734-746
(1)
18 800 Band A (Japan) 815-830 860-875
(1)
19 800 Band B (Japan) 830-845 875-890
(1)
20 800 (European Digital
Dividend)
832-862 791-821
(1)
21 1500 upper (Japan) 1447.9-1462.9 1495.9-1510.9
(1)
22 3500 3410-3490 3510-3590
(1)
23 US S-band 2000-2020 2180-2200
(1)
24 US L-band 1626.5-1660.5 1525-1559
(1)
25 PCS 1900 G 1850-1915 1930-1995
(1)
26 E850 Upper 814-849 859-894
(1)
27 850 Lower 806-824 851-869
(1)
28 APT 700 LTE 703-748 758-803
(1)
29 Media Flow N/A 716-728
(1)
(1) Not covered in this guideline
Some of the bands listed in Table 1, for example Band 12 and Band 17, are
overlapping. In order to support inter-operability between overlapping bands,
the feature Multiple Frequency Band Indicators is introduced, see Multiple
Frequency Band Indicators.
Table 2 3GPP E-UTRA Operating Bands, TDD
Band Identifier Frequency [MHz] Note
33 TDD 2000 1900-1920
(1)
34 TDD 2000 2010-2025
(1)
35 TDD 1900 1850-1910
(1)
36 TDD 1900 1930-1990
(1)
37 PCS center gap 1910-1930
(1)
38 IMT extension center gap 2570-2620
39 China 1880-1920
(1)
40 China 2300-2400
(1)
41 US 2600 2496 – 2690
(1)
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Introduction
Band Identifier Frequency [MHz] Note
42 3500 3400 – 3600
(1)
43 3700 3600 – 3800
(1)
(1) Not covered in this guideline
1.4 Limitations
This document has the following limitations:
• Interference between macro base stations is discussed, but not macro to
UE or UE to UE
• Micro base stations (base stations with low output power) are not discussed
• Remote Radio Unit (RRU) is not discussed
• Half-Duplex is not discussed
• Wireless Access Policy for Electronic Communications Services (WAPECS)
is not covered
1.5 Concepts
This section lists concepts helpful in understanding colocation and coexistence,
including:
• Spectrum definitions
• Transmitter characteristics
• Receiver characteristics
• System properties
• Deployment scenarios
1.5.1 Spectrum Definitions
The following concepts relate to spectrum definitions:
Carrier A carrier is the modulated waveform conveying the
E-UTRA or UTRA physical channels.
Channel bandwidth
Channel bandwidth is the radio frequency bandwidth
supporting a single E-UTRA RF carrier with the
transmission bandwidth configured in the uplink or
downlink of a cell. The channel bandwidth is measured
in MHz and used as a reference for transmitter and
receiver radio frequency requirements. See Figure 3 for
an illustration of the concept.
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Channel edge Channel edge is the lowest and highest frequency of the
E-UTRA carrier, separated by the channel bandwidth.
Channel spacing Channel spacing between two carriers is the distance
between two carrier center frequencies.
Downlink operating band
Downlink operating band is the part of the operating
band designated for downlink.
Guard band A guard band is unused sub-carriers between two
carriers.
Measurement bandwidth
Measurement bandwidth is the bandwidth in which an
emission level is specified, for example 100 kHz.
Operating band Operating band is a frequency range in which E-UTRA
operates (paired or unpaired), and is defined by specific
technical requirements.
Sub-carrier A sub-carrier is a carrier wave of 15 kHz width that is
orthogonal in the frequency domain in the supported
bandwidth.
Transmission bandwidth
Transmission bandwidth is bandwidth of an
instantaneous transmission from user equipment or
base station, measured in Resource Block (RB) units.
See Figure 4 for an illustration of a resource block.
Transmission bandwidth configuration
Transmission bandwidth configuration is the highest
transmission bandwidth allowed for uplink or downlink in
a given channel bandwidth, measured in resource block
units. See Figure 4 for an illustration of a resource block.
Uplink operating band
Uplink operating band is the part of the operating band
designated for uplink.
The following illustration shows the definition of channel and transmission
bandwidth configurations for one E-UTRA carrier:
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Introduction
Transmission
Bandwidth [RB]
Transmission Bandwidth Configuration [RB]
Center subcarrier (corresponds to DC in
baseband) is not transmitted in downlink
Active Resource Blocks
Resource
block
Channel
edge
Channel
edge
Channel Bandwidth [MHz]
L0000158A
Figure 3 Definition of Channel Bandwidth and Transmission Bandwidth
Configuration for One E-UTRA Carrier
The following illustration shows the definition of a resource block of 12
sub-carriers:
One resource blocks
(12 sub-carriers)
∆f =15 kHz
NRB resource blocks
(12NRB + 1 sub-carriers)
L0000157A
DC-sub-carrier
Figure 4 Definition of Resource Block Consisting of 12 Sub-Carriers
1.5.2 Transmitter Characteristics
The following concepts relate to transmitter characteristics:
Adjacent Channel Leakage power Ratio
One measure of Out Of Band Emission is Adjacent
Channel Leakage Power Ratio (ACLR). It is the ratio
of the filtered mean power centered on the assigned
channel frequency to the filtered mean power centered
on an adjacent channel frequency.
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Out Of Band Emission
Out Of Band Emissions (OOBE) are unwanted
emissions immediately outside the channel bandwidth
resulting from the modulation process and non-linearity
in the transmitter but excluding spurious emissions. The
OOBE limits are defined as a mask that stretches from
10 MHz below the lowest frequency of the downlink
operating band to 10 MHz above the highest frequency
of the downlink operating band, as shown in Figure 5.
Spurious emission
Spurious emissions are emissions which are caused
by unwanted transmitter effects such as harmonics
emission, parasitic emission, inter-modulation products,
and frequency conversion products. Spurious emission
excludes OOBE. The spurious emission limits are
defined up to 10 MHz below the lowest frequency of
the downlink operating band and from 10 MHz above
the highest frequency of the downlink operating band,
as shown in Figure 5.
Unwanted emission
Unwanted emissions consist of OOBE and spurious
emissions.
The following illustration shows unwanted emissions for operating bands, and
spurious emission bands:
Operating band (BS transmit)
10 MHz 10 MHz
Operating band unwanted emissions Spurious
emissions
Spurious
emissions
L0000159A
Figure 5 Operating Band Unwanted Emissions and Spurious Emissions
Bands
1.5.3 Receiver Characteristics
The following concepts relate to receiver characteristics:
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Introduction
Adjacent Channel Selectivity
Adjacent Channel Selectivity (ACS) is a measure of the
receiver ability to receive a wanted signal at its assigned
channel frequency in the presence of an adjacent
channel signal.
Blocking characteristics
The blocking characteristics are a measure of the
receiver ability to receive a wanted signal at the
assigned channel in the presence of an unwanted
interferer.
The following illustration shows definitions of ACLR and ACS, using example
characteristics of an aggressor interfering and a victim wanted signal:
L0000160A
Interfering
signal
Ratio defines
ACLR
for transmitted
signal
Ratio defines
ACS
for transmitted
signal
Wanted
signal
Transmitter
unwanted
emissions
Receiver filter
characteristics
Interfering
signal
Wanted
signal
Figure 6 Definitions of ACLR and ACS
1.5.4 System Properties
The following concepts relate to system properties:
Adjacent Channel Interference Ratio
Adjacent Channel Interference Ratio (ACIR) is the
total leakage between two transmissions on adjacent
channels, defined from ACLR and ACS.
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Antenna reference point
The antenna reference point at both the receiver and
the transmitter side is at the antenna connector when a
Tower Mounted Amplifier (TMA) is not used and at the
TMA antenna port when TMA is used, see Deployment
Guideline.
1.5.5 Deployment Scenarios
The following concepts relate to deployment scenarios:
Colocation Colocation is two or more base stations sharing the
same site. Normally the antennas belonging to the two
base stations (or systems) are separated horizontally on
a rooftop or separated vertically on a mast.
Coexistence Coexistence means deploying a base station on its own
individual site, sharing the geographical area with base
stations belonging to at least one other system.
Coordinated scenario
The base stations of two different technologies are
colocated and the carriers are from the same operator.
In this case high control of the interference between the
two carriers and UEs in the network can be achieved.
Uncoordinated scenario
The base stations of two technologies are colocated
and the carriers are from different operators. The base
stations can also be coexisting with carriers from same
or different operators. In this case it is harder to control
the interference between the two carriers and UEs in
the network.
Table 3 Coordinated and Uncoordinated Scenarios
Same operator Different operators
Colocation Coordinated Uncoordinated
Coexistence Uncoordinated Uncoordinated
Many networks have a mixture of colocated and coexisting base stations as
well as a mixture of coordinated and uncoordinated scenarios.
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Theory
2 Theory
This chapter describes the theory related to colocation and coexistence,
including:
• Operating band protection
• Isolation between systems
• System degradation
• Isolation against spurious emissions
• Isolation against blocking
2.1 Operating Band Protection
The ACIR is a measure of the leakage between two operating bands. It consists
of the following parts:
• Transmitter performance ACLR
• Receiver performance ACS
ACLR and ACS are expressed in linear terms.
The ACIR is defined as:
ACIR = 1
1
ACLR + 1
ACS
Equation 1 ACIR Definition
2.2 Isolation between Systems
Methods for achieving isolation between systems differ for colocation and
coexistence.
2.2.1 Colocation
The isolation between two systems is defined as the linear sum of all path
attenuations between the victim antenna reference point and each interfering
antenna reference point. This means that all contributions from aggressor
system antennas towards the victim antenna reference point should be
considered.
The lowest recommended antenna isolation for colocated equipment according
to 3GPP is 30 dB. This is valid for equipment on the same site belonging to the
same operator, as well as for all operators sharing the same site. The value
has been used to derive requirements in various standards.
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2.2.2 Coexistence
When systems coexist in the same geographical area and the antennas point
to each other, the requirement for isolation between these systems varies
depending on the sites. For each specific site, a unique relation exists between
distance to the aggressor base station and isolation Lisol under free space
propagation conditions:
Lisol= 32:4+20log d +20log F 0(Ga +Gb)+D
Equation 2 Relation between Distance and Isolation
where
Ga and Gb are the antenna gains [dB]
F is the frequency [MHz]
d is distance [km]
D is the decoupling factor achieved by changing direction or tilt of the main
antenna lobe [dB].
For the worst case when antennas point at each other, D = 0, but increases
when the main antenna lobe direction or the tilt is changed. Lisol is defined
between the antenna reference point (the transmitter connector) in the
aggressor base station and the receiver reference point at the victim base
station.
The interference level at the victim site depends on various factors:
• Rated output power of the aggressor
• Antenna types and specifications
• Antenna heights
• Antenna tilts and azimuths
• Distance between sites
• Type of environment, for example urban, suburban or rural
The following illustration shows antenna decoupling and how changing tilt
angles α1, α2, and azimuth angles affect the D value:
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Theory
L0000161A
α1
α2
d
Figure 7 Antenna Decoupling
2.3 System Degradation
System degradation is measured by the degradation of sensitivity, 1S. It is
defined as the sensitivity degradation caused by external interference, and
calculated as the noise rise due to the received interference:
1S = 10log 10N
10 +10Irx
10
10N
10
!
= 10log

1+10Irx0N
10

Equation 3 System Degradation Calculation
where
N is the noise floor [dB]
Irx is the external interference defined as the total sum of all power (narrow
and wide-band) emitted by the aggressor system and received in the band
of the victim system
Irx = Pem 0Lisol
Equation 4 External Interference Calculation
where
Pem is the sum of narrow-band and external interferers in the linear dimension:
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PemLin =
XPnarrow +
Z p(f) df
Equation 5 Sum of Narrow-Band and External Interferers
where
Pnarrow is the discrete narrow-band spurious or the inter-modulation
products generated due to non-linearities in the transmit chain
p(f) is the noise spectral density excluding the narrow-band interferers
Lisol is the sum of the individual isolation values for each of the aggressor
base stations according to Equation 2
Pem = 10 log PemLin [dBm]
2.4 Isolation against Spurious Emissions
According to 3GPP, a tolerable value degradation of sensitivity, 1S, is 0.8 dB.
Inserting this value in Equation 3 and solving Irx yields:
Irx = N 06:9
Equation 6 Calculating External Interference
The noise floor N can be expressed as:
N = Nt +Nf +10log B
Equation 7 Calculating Noise Floor
where
Nt is the system thermal noise power density = 0114 [dBm/MHz]
Nf is the system noise figure [dB]
B is the channel bandwidth [MHz]
If the emitted power of the interferer, Pem, is known, and the tolerable
interference level is calculated according to Equation 7, the required isolation
can be found from Equation 4:
Lisol = Pem 0Irx
Equation 8 Calculating Tolerable Interference Level
For a given value of the isolation Lisol, the maximum allowed spurious emission
level Pem can be determined. The equation can then be written as:
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Theory
Pem = Lisol +Irx
Equation 9 Maximum Allowed Spurious Emission Level
Using Equation 6 and Equation 7 for a measurement bandwidth 100 kHz and a
given Nf , gives the external interference Irx. Considering this, and for a given
Lisol, the emission level Pem in dBm/100 kHz can be calculated from Equation 9.
2.5 Isolation against Blocking
In the case of blocking, it is the tolerable received interference for a certain
degradation 1S that is specified in the respective standard. The interfering
signal is total carrier output power from the aggressor base station and the
resulting isolation requirement is:
Lisol = PBS 0Iblock
Equation 10 Calculating Isolation Requirement
where
Iblock is the received interference [dBm]
PBS is the output power from the aggressor base station [dBm]
The maximum total carrier output power from the aggressor base station,
PBS, can also be identified from the minimum isolation requirement using the
following equation:
PBS = Lisol +Iblock
Equation 11 Maximum Total Carrier Output Power
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3GPP Recommendations
3 3GPP Recommendations
This chapter provides an overview of 3GPP recommendations and gives
references to specific 3GPP documents for the following:
• Adjacent channel blocking
• Spurious emissions
• Blocking
For further information about 3GPP standards and specifications for base
station transmission, see 3GPP TS 36.104: Base Station (BS) radio
transmission and reception.
3.1 Adjacent Channel Blocking
The ACLR must be higher than 45 dB for all available bandwidths. The ACS
specifies a maximum interference level for a certain degradation of the wanted
signal equal to -52 dBm for all available bandwidths and for interfering E-UTRA
signals of various bandwidths.
3.2 Spurious Emissions
Colocation and coexistence have different requirements for setting spurious
emission limits.
For colocation with other base stations, the minimum requirement states that
the power of any spurious emission cannot exceed the 3GPP limits.
Table 4 Spurious Emission Limits for Colocated Base Stations
Base Station Type Frequency Range [MHz] Maximum Level
[dBm]
Measurement Bandwidth
[kHz]
Note
GSM 900 876 - 915 -98 100
(1)
GSM 1800 1710 - 1785 -98 100
(1)
UTRA Band I 1920 - 1980 -96 100
(1)
CDMA2000 Band 0 824 - 849 -98 100
(1)
TD-SCDMA Band f) 1880 - 1920 -96 100
(1)
E-UTRA Band 7 2500 - 2570 -96 100
(1)
E-UTRA Band 13 777 - 787 -96 100
(1)
E-UTRA Band 38 2570 - 2620 -96 100
(1)
E-UTRA Band 40 2300 - 2400 -96 100
(1)
(1) This requirement does not apply to E-UTRA operating in the same band
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For coexistence with other base stations, the minimum requirement states that
the power of any spurious emission for coexistence with systems operating in
other frequency bands cannot exceed the limits given in the following table,
according to 3GPP standards:
Table 5 Spurious Emission Limits for Coexisting Base Stations
E-UTRA System Type Frequency Range [MHz] Max. Level [dBm] Measurement
Bandwidth [kHz]
Note
921 - 960 -57 100
(1)
GSM 900
876 - 915 -61 100
(2)
1805 - 1880 -47 100
(1)
GSM 1800
1710 - 1785 -61 100
(2)
2110 - 2170 -52 1000
(1)
UTRA Band I or
E-UTRA Band 1 1920 - 1980 -49 1000
(2)
869 - 894 -57 100
(1)
CDMA2000 Band 0
824 - 849 -61 100
(2)
TD-SCDMA Band f) 1880 - 1920 -52 1000
2620 - 2690 -52 1000
(1)
E-UTRA Band 7
2500 - 2570 -49 1000
(2)
746 - 756 -52 1000
(1)
E-UTRA Band 13
777 - 787 -49 1000
(2)
E-UTRA Band 38 2570 - 2620 -52 1000
(1)
E-UTRA Band 40 2300 - 2400 -52 1000
(1)
(1) This requirement does not apply to E-UTRA base station operating in the same band
(2) This requirement does not apply to E-UTRA base station operating in the same band; in that case, the requirement
is -96 dBm for 100 kHz measurement bandwidth
3.3 Blocking
For colocation with other base stations, the following blocking requirements
exist: For all technologies and operating bands discussed in this document, the
interfering signal mean power is +16 dBm for a desired signal mean power of
PREFSENS + 6 dB [dBm] and a Continuous Wave (CW) carrier as interfering
signal. Here PREFSENS is the reference sensitivity power level that is given
according to the following table:
Table 6 Base Station Reference Sensitivity Levels
E-UTRA Channel Bandwidth [MHz] PREFSENS [dBm]
1.4 -106.8
3 -103.0
5 -101.5
10 -101.5
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3GPP Recommendations
E-UTRA Channel Bandwidth [MHz] PREFSENS [dBm]
15 -101.5
20 -101.5
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Calculation Examples
4 Calculation Examples
This chapter provides calculation examples for the following:
• Isolation against LTE spurious emissions
• Isolation against blocking towards LTE
• LTE spurious emission level
• LTE sensitivity degradation
This document provides interpretation of the results and recommended actions.
4.1 Isolation against LTE Spurious Emissions
This section gives an example calculating the required isolation between the
eNodeB and base stations of different radio access technologies including LTE,
using the methods described in Section 2.3 on page 13.
Assume that LTE and GSM base stations are colocated, or that they will be
deployed in the same geographic area. Assume also that the GSM 1800 base
stations formally comply with a maximum emission level of –98 dBm/100 kHz
(for colocation, see Table 4) or –61 dBm/100 kHz (for coexistence, see Table 5).
The stated emission level (per 100 kHz) is converted to an emission level in the
LTE channel. Assume that the actual LTE channel bandwidth B = 10 MHz.
Pem = 098 + 10 log (10/0.1) = 078 dBm
A typical noise figure for LTE equipment is 5 dB specified by 3GPP. Inserting
these figures into Equation 7 yields:
N = 0114 + 5 + 10 log (10) = 099 dBm
Inserting into Equation 6 yields:
Irx = 06.9 0 99 = 0105.9 dB
Finally, inserting into Equation 8 yields:
Lisol = 078 + 105.9 = 27.9 dB
When base stations are colocated, the isolation can be achieved either by
adapting the site solution or by adding extra filters on the GSM equipment.
For coexistence in the same geographic area, the minimum required physical
separation between LTE (with 0.8 dB degradation) and GSM can be estimated
to roughly 300 m, according to Equation 2 and assuming a maximum emission
level of –61 dBm/100 kHz. This assumes that the frequency is 2600 MHz, the
antenna gains Ga = Gb = 18 dBi, and the decoupling factor D = 10 dB.
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4.2 Isolation against Blocking towards LTE
The blocking requirement Iblock for LTE eNodeB is 16 dBm, and is specified for
a degradation 1S of 6 dB, see Section 3.3 on page 18.
If the output power from the aggressor base station PBS = 43 dBm, the required
isolation is found when using Equation 10:
Lisol = 43 – 16 = 27 dB
4.3 LTE Spurious Emission Level
Assume that in this case, the isolation, Lisol, is 30 dB. The maximum allowed
spurious emission level Pem for 100 kHz measurement bandwidth must be
determined. It is assumed that the allowed degradation 1S is 0.8 dB and that
the noise figure for LTE equipment is 5 dB.
Using Equation 6 yields:
Irx = 06.9 + N
Using Equation 7 yields:
N = 0114 + 5 + 10 log (0.1) = 0119 dBm/100 kHz
Thus Irx = 06.9 – 119 = 0125.9 dB
Finally using Equation 9 yields:
Pem = 30 – 125.9 = 095.9 dBm
4.4 LTE Sensitivity Degradation
Assume that an LTE eNodeB is colocated with a GSM 1800 base station.
According to Table 4, the maximum spurious emission requirement for
colocation is 098 dBm/100 kHz. For a 10 MHz carrier, the corresponding level
is for this bandwidth:
098 + 10 log (10/0.1) = 078 dBm/10 MHz
With 30 dB of system isolation, the external interference Irx is:
Irx = 078 – 30 = 0108 dB
For a noise figure of 5 dB, the LTE noise floor is –99 dBm/10 MHz and the
LTE sensitivity degradation can be calculated according to Equation 3 as:
1S = 10log

1+1001080(099)
10

= 0.5 dB
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Calculation Examples
4.5 Interpreting Results and Recommended Actions
The true impact of interference always depends on the actual isolation achieved
in the field and the actual performance of the installed equipment. Each
practical colocation or coexistence scenario must be analyzed thoroughly,
using the methods presented in this document as a starting point.
Colocation requirements are usually based on 30 dB isolation, while a typical
installation may often have 25 to 40 dB isolation. If the required isolation
is more than is currently achieved, minor modifications of the installation or
colocation methods, for example using diplexers, may increase the isolation
significantly in many cases.
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Colocation and Coexistence for E-UTRA
5 Colocation and Coexistence for E-UTRA
This chapter provides information about colocation and coexistence for
E-UTRA, specifically:
• Spectrum allocation
• E-UTRA with E-UTRA
• E-UTRA Band 7 with GSM 1800
• E-UTRA Band 7 with UTRA Band I
• E-UTRA Band 13 with CDMA2000 Band 0
5.1 Spectrum Allocation
Different E-UTRA operating bands will be deployed in different regions, see
Table 1 and Table 2. E-UTRA will be deployed together with E-UTRA or with
other technologies, as shown in the following illustration of the spectrum
allocation:
UL
Combined DL/UL
DL
China,
(Australia)
ITU
Europe
825 845 870 890 915 935
876 921
806
IMT-2000
960 2025
1710
IMT-2000
Japan
DL UL is
Switched!
810 915
860 885
830 960
Americas
824 849 869 894
TDMA/GSM/ MXM
1990
1850 1910 1930
PCS
R-GSM 900
CDMA GSM 900 GSM 1800/IMT -2000
PDC 800 others **
1880
1710 1785 1805 1880
1710 1785 1805
GSM 1800
1880
1710 1785 1805 1880
1710 1785 1805
870 925
cdmaOne **
1920
PHS
915 1900
DECT
1980
1920
IMT-2000
2110
2110 2170
UMTS FDD
2010
MSS
MSS
TDD
TDD
MSS
MSS
KDDI
KDDI
cdma2000
W-CDMA
1940 2110 2130
A
D
B
E
F
C
A
D
B
E
F C
* * * *
843
832
898
887
833
845
888
900
1487-1491
1439-1443
—
1.5G–
2110 2155/70
1710 1755/70
3G/AWS/IMT -2000
IMT IMT
1900
DECT
1980
1920 2110 2170
UMTS FDD
2010
TDD
TDD
1755 1850
1915 ***
1995 ***
G G
2200
UL
Combined DL/UL
DL
ITU
Europe/Latin America
2690
USA
IMT-2000
2690
2500
2570 2620
external
BS (ITFS/BRS)
2495 2568 2572 2614 2618 2690
Japan
MSS
BSS
MSS BSS
FDD
outband
TDD MSS
BSS
MSS BSS
FDD
outband
TDD
L0000163A
Figure 8 IMT2000 Technology Spectrum Allocation
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In this chapter, some examples of combinations of E-UTRA operating bands
with bands of different technologies are presented, together with calculations
on isolation for colocation and coexistence.
5.2 E-UTRA with E-UTRA
Considerations for colocation and coexistence of E-UTRA with E-UTRA include
the following:
• Operating bands
• Isolation
• Near-Far effect
5.2.1 Operating Bands
Two operating band examples are shown:
• E-UTRA band 7 (FDD) with E-UTRA band 7 (FDD)
• E-UTRA band 7 (FDD) with E-UTRA band 38 (TDD)
In Table 1 and Table 2, operating bands are shown for the E-UTRA bands.
5.2.2 Isolation
The spurious emission limits for colocated and coexisting base stations are
found in Table 4 and Table 5.
Table 7 Colocation and Coexistence Isolation for E-UTRA with E-UTRA
1S [dB] Pem [dBm] Irx 0N [dBm] Lisol [dB]
Spurious emissions,
colocation
0.8 -96/100 kHz -6.9 29.9
Spurious emissions,
coexistence, different
operating bands, FDD to
FDD and TDD to FDD
0.8 -49/1000 kHz -6.9 66.9
Spurious emissions,
coexistence, same operating
band
0.8 -96/100 kHz -6.9 29.9
1S [dB] PBS [dBm] Iblock [dBm] Lisol [dB]
Blocking 6 43 16 27
For FDD to TDD, guard bands are required, see Figure 9. Wider guard bands
are required for uncoordinated systems compared to coordinated systems.
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L0000164A
Guard band
FDD UL FDD DL
TDD
Figure 9 Guard Bands
5.2.3 Near-Far Effect
Requirements differ depending on the operating bands used. If the same
operating bands coexist, the Near-Far effect may occur, see Section 1.1 on
page 1. The effect may be overcome with site colocation. If different operating
bands coexist, the requirements for isolation are higher, and additional filters
are needed.
5.3 E-UTRA Band 7 with GSM 1800
This section describes operating band and isolation requirements for E-UTRA
Band 7 with GSM 1800.
In this case, E-UTRA Band 7, see Table 1, is colocated or coexists with GSM
1800.
Table 8 GSM 1800 Operating Band
GSM Operating Band UL Operating Band Base Station
Receive UE Transmit [MHz]
DL Operating Band Base Station
Transmit UE Receive [MHz]
Bandwidth [MHz]
GSM 1800 1710 - 1785 1805 - 1880 0.2
5.3.2 Isolation
Table 9 Colocation and Coexistence Isolation for E-UTRA Band 7 with GSM 1800
1S [dB] Pem [dBm] Irx 0 N [dBm] Lisol [dB]
Spurious emissions,
colocation
0.8 -98/100 kHz -6.9 27.9
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Table 9 Colocation and Coexistence Isolation for E-UTRA Band 7 with GSM 1800
Spurious emissions,
coexistence
0.8 -61/100 KHz -6.9 64.9
Blocking 6 43 16 27
Collisions do not occur between the operating bands for E-UTRA Band 7 and
GSM 1800, so guard bands are unnecessary. In this case, no additional actions
are required beyond using appropriate filters.
5.4 E-UTRA Band 7 with UTRA Band I
Band 7 with UTRA Band I.
In this case, E-UTRA Band 7, see Table 1, is colocated or coexists with UTRA
Band I.
Table 10 UTRA Band I Operating Band
UTRA Operating Band UL Operating Band Base Station
Bandwidth [MHz]
I 1920 - 1980 2110 - 2170 3.84
5.4.2 Isolation
Table 11 Colocation and Coexistence Isolation for E-UTRA Band 7 with UTRA Band I
1S [dB] P em [dBm] Irx 0 N [dBm] Lisol [dB]
Spurious emissions,
colocation
0.8 -96/100 kHz -6.9 29.9
Spurious emissions,
coexistence
0.8 -49/1000 kHz -6.9 66.9
Blocking 6 43 16 27
Collisions do not occur between the operating bands for E-UTRA Band 7 and
UTRA Band I, so guard bands are unnecessary. In this case, no additional
actions are required beyond using appropriate filters.
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5.5 E-UTRA Band 13 with CDMA2000 Band 0
Band 13 with CDMA2000 Band 0.
In this case, E-UTRA Band 13, see Table 1, is colocated or coexists with
CDMA2000 Band 0.
Table 12 CDMA2000 Band 0 Operating Band
CDMA2000 Operating Band UL Operating Band Base Station
Bandwidth [MHz]
CDMA2000 Band 0 824 - 849 869 - 894 1.23
5.5.2 Isolation
Table 13 Colocation and Coexistence Isolation for E-UTRA Band 13 with CDMA2000 Band 0
Spurious emissions,
colocation
0.8 -98/100 kHz -6.9 27.9
Spurious emissions,
coexistence
0.8 -61/100 kHz -6.9 64.9
Blocking 6 43 16 27
Collisions do not occur between the operating bands for E-UTRA Band 13
and CDMA2000 Band 0, so guard bands are unnecessary. In this case, no
additional actions are required beyond using appropriate filters.
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Solutions
6 Solutions
This chapter provides suggested solutions for colocation and coexistence,
including:
• Restrictions in the operating band
• Interference Rejection Combining
• Guard bands
• Filters
• Colocation solutions
6.1 Restrictions in the Operating Band
This section provides uplink scheduling solutions for the cases when
transmission power restrictions apply to parts of the operating band.
6.1.1 PUCCH Overdimensioning
The PUCCH carries uplink control information, see Control Channel
Dimensioning. The resource blocks reserved for the PUCCH are allocated in
the edge of the supported bandwidth according to the standard. There is a risk
that this situation may cause harmful degradation of the PUCCH performance
in specific scenarios as described below.
• Where Additional Maximum Power Reduction (A-MPR) restrictions
apply, the UE is allowed to reduce the output power at the band
edges to reduce interference in neighboring frequency bands. The
networkSignallingValue parameter defines how much power
reduction the UE is allowed to use. The PUCCH Overdimensioning feature
allows the PUCCH region to be moved to another part of the supported
bandwidth where A-MPR restrictions are less severe.
• Where the transmission in neighboring frequency bands degrades LTE
system performance at the band edges, the PUCCH Overdimensioning
feature can be used to move the PUCCH region to frequency regions with
less interference from the neighboring bands. The region closer to the
band center that will carry PUCCH signaling is referred to as the Active
PUCCH region.
Overdimensioning of the PUCCH, which means moving the PUCCH
symmetrically towards the band center, is a solution to this problem.
The PUCCH Overdimensioning feature also allows specifying the maximum
number of resource blocks that the network allows any UE to use for PUSCH
in a cell. This limitation is needed to fulfil some of the additional spectrum
emission requirements according to 3GPP TS 36.101, User Equipment (UE)
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radio transmission and reception in conjunction with PUCCH Overdimensioning.
This is controlled by using the puschMaxNrOfPrbsPerUe parameter.
L0000863A
Without PUCCH Over-Dimensioning
Active
PUCCH
Region
Active
PUCCH
Region
With PUCCH Over-Dimensioning
PUCCH
Over-Dimensioned (RBs)
Active
PUCCH
Region
Active
PUCCH
Region
PUCCH
Over-Dimensioned (RBs)
Figure 10 Overdimensioning of PUCCH
The following parameters are related to the PUCCH Overdimensioning feature:
Table 14 Parameters for Overdimensioning of PUCCH
Parameter Description
networkSignallingValue Specifies the signalling value related to A-MPR according
to 3GPP to be broadcast in the cell
pucchOverdimensioning Specifies the number of resource blocks at each band
edge outside of the active PUCCH region that are
available for scheduling of Physical Uplink Shared
Channel (PUSCH)
puschMaxNrOfPrbsPerUe Specifies the maximum number of physical resource
blocks allowed on PUSCH for any UE
Setting the values of pucchOverdimensioning and puschMaxNrOfPrbsP
erUe to other than their default values takes effect only if the corresponding
license for the PUCCH Overdimensioning feature is active.
For further information, see 3GPP TS 36.101, User Equipment (UE) radio
transmission and reception, Radio Network and PUCCH Overdimensioning.
6.1.2 Limiting PUSCH Scheduling
In case interference into adjacent bands needs to be avoided, scheduling
strategies can be used to avoid that resource blocks of the PUSCH are
scheduled in these parts, so called PUSCH blocking. The following parameters
are related to the scheduling and interference management:
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Solutions
Table 15 Parameters for Scheduling and Interference Management
Parameter Description
ulInterferenceManagementActive Specifies if uplink interference management is enabled or
disabled
ulConfigurableFrequencyStart Specifies the start frequency offset for the allocation of
resources when the uplink interference management is
disabled expressed as a percentage of the supported
bandwidth
ulFrequencyAllocationProportion Specifies the amount of frequency resources that is
allocated in UL expressed as a percentage of the
supported bandwidth
To enable PUSCH blocking the parameter ulInterferenceManagementAc
tive has to be set to FALSE. Then the parameters ulConfigurableFreq
uencyStart and ulFrequencyAllocationProportion can be used to
apply PUSCH blocking. Table 16 describes the required parameter settings for
applicable PUSCH blocking scenarios for different bandwidths.
Table 16 Parameter Settings for PUSCH Blocking
Bandwidth
[MHz]
RB Number ulConfigurableFrequencyStart [%] ulFrequencyAllocationProportion
[%]
5 0-2 15 90
5 0-6 30 75
10 0-3 10 92
15 0-7 + 67-74 11 79
20 0-23 + 76-99 25 52
20 0-24 + 75-99 26 50
20 50-74 76 75
20 50-77 79 72
20 25-49 51 75
20 22-49 51 72
PUSCH blocking can be used in combination with PUCCH Overdimensioning
functionality and A-MPR in order to fulfil some of the additional spectrum
emission requirements according to 3GPP TS 36.101, User Equipment (UE)
radio transmission and reception, see Section 6.1.1 on page 31.
6.2 Interference Rejection Combining
Interference Rejection Combining (IRC) is a method to enhance the capacity
by suppressing the undesirable inter-cell interference in uplink. IRC uses
correlations in the spatial domain (between antennas) and in the frequency
domain to suppress interfering signals from other cells or in-band external
interferers, see Interference Rejection Combining.
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6.3 Guard Bands
In a given area of coverage, if there are two operating networks working in the
same spectrum bandwidth or band, the width of the guard band defines how
much is the operator A is interfering into the operator B. The wider the guard
band, the less interference.
L0000475A
Operator A
Guard Band
2305.0 MHz 2325.0 MHz
Operator B
2327.5 MHz 2347.5 MHz
Figure 11 Guard Band between Two Operators. The Frequencies Given Are
Examples for Illustrative Purpose Only
If the two systems are uncoordinated, a UE operating at the end of spectrum
band of operator A will be causing more interference into a UE operating at the
start (left end in Figure 11) of the spectrum band belonging to operator B.
The most serious interference case is assumed to be OOBE from an RBS
operating at the edge of one band to the nearest edge of the other band. Two
interference scenarios are considered, moderate OOBE and strong OOBE.
Moderate OOBE means that there is high geographical isolation between the
two systems, while strong OOBE means low geographical isolation; the sites
are placed in the same neighborhood with antennas pointing against each
other. See Section 2.2.2 on page 11.
According to 3GPP TS 36.104: Base Station (BS) radio transmission and
reception, the tolerable throughput degradation is up to 5% from the reference
case. If the guard band is below a certain width, the degradation may exceed
the 5%. To compensate the excessive degradation at narrow guard band,
extra filters have to be applied.
Table 17 Filter Precautions for Different Guard Band Sizes
Guard Band
[MHz]
2.5 5 7.5 10
Moderate OOBE Yes No No No
Strong OOBE Yes Yes No No
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Solutions
6.4 Filters
In case of coexistence, a proper filter has to be applied to achieve the required
isolation. Table 18 gives recommendations for the filters to be chosen for the
appropriate guard band between operators bandwidth.
Table 18 Recommended Filter Attenuation for 2.5 MHz and 5 MHz Guard
Band
Guard Band [MHz] Filter Attenuation [dB]
2.5 10
5 5
7.5 No filter needed
10 No filter needed
6.5 Colocation Solutions
This section provides suggested colocation solutions including:
• Separate antenna systems
• Dual diplexer and shared mast feeder
• Shared antenna
6.5.1 Separate Antenna Systems
The simplest way to colocate LTE with a system already deployed is to add
another antenna system for LTE. The antennas would probably be mounted at
different heights or separated physically.
The following general recommendations are used within Ericsson:
• If the LTE antennas and antennas for the other technology are separated
vertically or horizontally , pointing in parallel directions or away from each
other, the isolation is fulfilled. Furthermore,
• when horizontal separation is used, the azimuth directions should not
intersect
• when vertical separation is used, the tilt directions should not intersect
The separation distance depends on the horizontal beam width and the
frequency band, according to the document Antenna Configuration Guideline in
the Site Solution library:
Table 19 Horizontal Separation for Directional Antennas in [m]
Horizontal
Beam Width
GSM900 Only GSM1800/GSM1900/
UMTS/LTE Only
GSM900 with GSM1800/GSM
1900/ UMTS/LTE
65±10 0.4 0.2 0.3
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Horizontal
Beam Width
UMTS/LTE Only
GSM900 with GSM1800/GSM
1900/ UMTS/LTE
90±10 1.0 0.5 0.5
105±10 1.5 0.7 0.7
120±10 2.0 1.0 1.0
180±10 5.0 2.5 2.5
For vertical separation, the minimum distance is 0.2 m.
For Omni antennas, the horizontal separation requirements may be higher,
depending on the antenna gains and the frequency, as shown in the following
table:
Table 20 Horizontal Separation for Omni Antennas in [m]
Omni Antenna Gain
[dBi]
UMTS/LTE Only
GSM900 with
GSM1800/GSM1900/
UMTS/LTE
10 3.0 1.5 1.0
10 5.0 2.5 1.0
For vertical separation, the minimum distance is 0.2 m.
6.5.2 Dual Diplexer and Shared Mast Feeder
In this solution there are two diplexers. The first diplexer combines the LTE
Tx/Rx and the Tx/Rx for the other technology from each base station to a
single feeder, which ascends the mast. A second diplexer splits the two into
separate TMAs or antennas. These antennas should have at least 30 dB
antenna isolation. The first diplexer should have at least 50 dB isolation. The
main concern is inter-modulation products of the third order generated after the
first diplexer. See Section 1.2 on page 2 for more information.
6.5.3 Shared Antenna
The existing Tx/Rx antenna is replaced with an antenna covering both LTE
and the other technology (this is actually two antennas in the same radome).
This antenna must have at least 30 dB isolation between LTE and the other
technology.
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Spectrum Refarming
7 Spectrum Refarming
Spectrum refarming is done in order to free spectrum from an existing
technology such as GSM or WCDMA to a new technology like LTE.
In Table 21 some examples of common operating bands for sharing possibilities
are given.
Table 21 Examples of Common Operating bands for Frequency Sharing between GSM, LTE
and WCDMA
UL Frequency
[MHz]
DL Frequency
[MHz]
Technology for
frequency band
sharing
GSM/EDGE Band
designation
WCDMA Band
number
LTE Band number
1920 - 1980 2110 - 2170 WCDMA, LTE Not available I 1
1850 - 1910 1930 - 1990 GSM, WCDMA,
LTE
PCS 1900 II 2
1710 - 1785 1805 - 1880 GSM, WCDMA,
LTE
DCS 1800 III 3
1710 - 1755 2110 - 2155 WCDMA, LTE Not available IV 4
824 - 849 869 - 894 GSM, WCDMA,
LTE
GSM 850 V 5
2500 - 2570 2620 - 2690 WCDMA, LTE Not available VII 7
880 - 915 925 - 960 GSM, WCDMA,
LTE
E-GSM VIII 8
Different technologies can share the spectrum, which means that they can be
deployed in the same operating band. Appropriate actions have to be taken to
avoid degrading interference between the technologies:
• Interference control
• Frequency placement within the shared band
• Deploying guard bands
7.1 Interference Control
For Interference management in LTE, there are the following features
available for uplink: Interference Rejection Combining, see Section 6.2 on
page 33, Random Start Point Frequency Schedulingand Frequency Selective
Scheduling.
With Random Start Point Frequency Scheduling it is possible to select the
starting point in frequency randomly to be either the lowest or highest possible
frequency. Hence LTE users can be avoided to be scheduled in adjacent bands
as GSM or WCDMA users, which will reduce the interference between the
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systems. Frequency Selective Scheduling is a function that allocates the LTE
UEs to the frequencies with the most favorable signal quality. Interference from
GSM or WCDMA users can thereby be mitigated.
7.2 Spectrum Recommendations
The first step in the preparation for refarming is to set the target frequency
configuration. The target configuration is chosen depending on how the
operator uses his own spectrum as well as how competitor operators use theirs.
The rule is to position own GSM frequencies close to a competitor’s GSM
frequencies, and LTE close to competitors LTE spectrum. When GSM spectrum
is to be released for LTE usage the target configuration in Figure 12 is the
recommendation if other operator use GSM next to the own GSM spectrum, or
LTE just below own target LTE spectrum.
L0000610A
LTE LTE
GSM GSM
Other operator Other operator
Own spectrum
Figure 12 Target Configuration, LTE below GSM
This arrangement is suggested in order to control the interference between
GSM and LTE, and reduce guard band requirements for uncoordinated
scenarios. Target configuration in Figure 13 is recommended in the case when
other operators deploy GSM just above and below operator’s own operating
band.
L0000611A
LTE
GSM
GSM GSM
GSM
Other operator Other operator
Own spectrum
Figure 13 Target Configuration, LTE within Split GSM
The same rules should be followed when refarming WCDMA for LTE.
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Spectrum Refarming
7.3 Channel Spacing Recommendations
When carriers of different technologies are present within the same operating
band a specific channel spacing must be obtained in order to have minimum
disturbance between the two technologies. In this section recommendations
are given for channel spacing and guard band sizes. The channel spacing is
the distance between two carrier center frequencies including guard band size.
Channel Spacing = Channel BW1 +Channel BW2
2 +Guard Band
Equation 12 Channel Spacing as a Function of Channel Bandwidth (BW) and
Guard Band Size
7.3.1 LTE and GSM
The recommendations given in this section are according to 3GPP, see 3GPP
TS 37.104: Multi-Standard Radio (MSR) Base Station (BS) radio transmission
and reception.
Figure 14 shows the channel spacing between an LTE carrier and a GSM
carrier.
L0000609A
LTE Carrier
GSM Carriers
Channel Spacing
Guard Band
Channel Bandwidth
Figure 14 Channel Spacing between an LTE Carrier and a GSM Carrier
The guard band depends on the geographical coordination between the
deployed technologies of the operator and competitors in the same area.
For the coordinated scenario, the guard band size can be as low as 0 kHz,
which means that the channel spacing is 10.1 MHz for an LTE carrier of 20
MHz. If the GSM Broadcast Control Channel (BCCH) is placed next to LTE
carrier, a guard band of 100 kHz is recommended, which means a channel
spacing of 10.2 MHz for an LTE carrier of 20 MHz.
For the uncoordinated scenario, the following carrier spacing is recommended:
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• For LTE carriers of ≥ 5 MHz: Guard band size of 300 kHz, which means a
channel spacing of 10.4 MHz for an LTE carrier of 20 MHz
• For LTE carriers of 1.4 and 3 MHz: Guard band size of 200 kHz, which
means a channel spacing of 1.8 MHz for an LTE carrier of 3 MHz
7.3.2 LTE and WCDMA
Guard band recommendations for LTE and WCDMA are not yet fully studied
in 3GPP.
In a first stage of refarming from WCDMA to LTE, one WCDMA carrier can be
replaced by a LTE carrier of 5 MHz bandwidth. This means a channel spacing
of 5 MHz between the LTE carrier and the adjacent WCDMA carrier.
L0000612A
5 MHz
5 MHz
5 MHz
WCDMA
WCDMA
WCDMA
WCDMA
LTE
WCDMA
WCDMA
WCDMA
Figure 15 Example with Replacing a WCDMA Carrier with an LTE Carrier
when Using Four WCDMA Carriers
In later stages, additional WCDMA carriers can be replaced in order to deploy
LTE carriers of 10 or 15 MHz bandwidth. Most likely, at least at an initial stage,
areas with WCDMA only will coexist with areas with WCDMA and LTE.
For the coordinated scenario, WCDMA and LTE can be deployed in the same
band, colocated with adjacent carriers without any major degradation for any of
the systems. WCDMA and LTE cannot be deployed using the same frequency
for the coordinated scenario.
For the uncoordinated scenario, WCDMA and LTE can be deployed in the same
band and coexisting without any major degradation for any of the systems. No
specific precautions need to be taken in order to protect WCDMA from LTE; for
example guard zones are not required.
When planning the network for the above described cell coordination, it is also
important to take precautions for the Near-Far effect, see Figure 2. In order
to combat this problem, the sites of the two networks should be colocated if
possible. If not possible to colocate everywhere, the new network should if
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Spectrum Refarming
possible be planned so that the cell borders for one system do not coincide with
the antenna placements for the other system.
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