Mason Communications Training: WCDMA Radio Planning Course
Module 4: UMTS Design Elements
Section 4.3: Interference
WCDMA Radio Planning Course
4
UMTS Design Elements
4.3 Interference
www.masoncom.com
© Mason Communications Ltd 2001
Mason Communications Training: WCDMA Radio Planning Course
Module 4: UMTS Design Elements
Section 4.3: Interference
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Mason Communications Training: WCDMA Radio Planning Course
Module 4: UMTS Design Elements
Section 4.3: Interference
Interference
Where are We Now?
Introduction
to UMTS
Course
Overview
Intro to
Radio Planning
Mobile Radio
Channel
Comms Theory
Course
Overview
Antennas
Part I
Notation
Path Loss
Statistics
Basic Radio
Diversity
Principles
Local Mean
Signal
Intro to Link
Budgets
Narrowband
Channel
Intro to
Planning Tools
Wideband
Channel
Course
Wash Up
Diversity
UMTS
Overview
UMTS
Specifications
Access
Methods
WCDMA
Introduction
UMTS Model
Architecture
Part I
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UMTS
Design Elements
UMTS
Network Design
Matched
Filters and
Rake Receivers
UMTS Link
Budgets
Antennas
Part II
Interference
WCDMA
Physical Layer
UMTS Planning
Process
Site Placement
Radio Resource
Management
Course
Wash Up
Part II
© Mason Communications Ltd 2001
4.3.2
Where are We Now?
The Course Map shows which section we are now on.
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Mason Communications Training: WCDMA Radio Planning Course
Module 4: UMTS Design Elements
Section 4.3: Interference
Interference
What is in This Section?
UMTS
Design Elements
General Classifications of Interference
Matched
Filters and
Rake Receivers
Antenna
Part II
US Multi-Technology Experience
Intermods
Interference
General and UK UTRA Spectrum Allocations
WCDMA
Physical Layer
Basic Transmitter Specifications
Impact of WCDMA Spurious Emissions on GSM
Summary
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© Mason Communications Ltd 2001
4.3.3
What is in This Section?
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Mason Communications Training: WCDMA Radio Planning Course
Module 4: UMTS Design Elements
Section 4.3: Interference
Interference
Why is this Section Important to You?
• Draw the distinction between internal and external
interference
• Understand the impact of spectrum/channel allocation in
relation to ACLR and hence capacity
• Understand impact of W-CDMA spurious emissions on GSM
systems
• Identify how to mitigate the impact on GSM at co-location
sites or those in close proximity to one another
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© Mason Communications Ltd 2001
4.3.4
Why is this Section Important to You?
We will discuss ACLR (Adjacent Channel Leakage Ratio) which is important as it has a
bearing on capacity.
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Mason Communications Training: WCDMA Radio Planning Course
Module 4: UMTS Design Elements
Section 4.3: Interference
Interference
How Will You Learn?
Worked Examples
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Discussion
© Mason Communications Ltd 2001
4.3.5
How Will You Learn?
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Mason Communications Training: WCDMA Radio Planning Course
Module 4: UMTS Design Elements
Section 4.3: Interference
Interference
Interference
• Mobile radio systems are predominantly interference and not
noise limited
• Interference can be categorised in two basic forms:
– Internal to an operator’s own network
– External to an operator’s network
• Interference limits the performance of a network
• Interference can sometimes be inadvertently engineered
into a network
Get it right first time!
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Mason Communications Training: WCDMA Radio Planning Course
Module 4: UMTS Design Elements
Section 4.3: Interference
Interference
Where Are We Now?
UMTS
Design Elements
General Classifications of Interference
Matched
Filters and
Rake Receivers
Antenna
Part II
US Multi-Technology Experience
Intermods
Interference
General and UK UTRA Spectrum Allocations
WCDMA
Physical Layer
Basic Transmitter Specifications
Impact of WCDMA Spurious Emissions on GSM
Summary
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4.3.7
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Mason Communications Training: WCDMA Radio Planning Course
Module 4: UMTS Design Elements
Section 4.3: Interference
Interference
Interference Categories
Internal
External
• Co-channel
• Co-channel (boundary)
•
Antenna selection
•
Antenna orientation
• Adjacent channel (ACLR)
•
As above
• Technology mix
• Adjacent channel (boundary
– ACLR)
• International channel
harmonisation
• Technology mix
•
• Wideband ISI (GSM)
• Intermods
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RF coupling +
insufficient filtering
• Intermods
© Mason Communications Ltd 2001
4.3.8
Note:
ISI – Inter Symbol Interference. See “Wideband Channel” section of the course notes.
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Mason Communications Training: WCDMA Radio Planning Course
Module 4: UMTS Design Elements
Section 4.3: Interference
Interference
Internal Interference
• Co-channel and adjacent channel:
– These fall within your own frequency plans and hence
can be adjusted accordingly
• Wideband ISI
– Likely to occur in hilly and over-water propagation
conditions. These can be mitigated by suitable antenna
downtilting
• Intermods
– In this instance the likelihood is that the interference,
although internally generated, may be affecting other
co-located operators
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Mason Communications Training: WCDMA Radio Planning Course
Module 4: UMTS Design Elements
Section 4.3: Interference
Interference
External Interference
• Co/adj-channel
– Occur when channels are chosen which are at the edge
of spectrum allocation block
– Biggest problem areas occur when there are multiple
operators using contiguous portions of spectrum bands
in geographic boundary conditions, e.g. USA
– mitigated by using frequency plans that migrate from
the centre of the band outwards and utilise band-edge
channels for special applications
• Note: Dissimilar technologies, e.g. GSM/CDMA can exist in
same coverage area with effects exacerbated at boundary
edges
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Mason Communications Training: WCDMA Radio Planning Course
Module 4: UMTS Design Elements
Section 4.3: Interference
Interference
Where Are We Now?
UMTS
Design Elements
General Classifications of Interference
Matched
Filters and
Rake Receivers
Antenna
Part II
US Multi-Technology Experience
Intermods
Interference
General and UK UTRA Spectrum Allocations
WCDMA
Physical Layer
Basic Transmitter Specifications
Impact of WCDMA Spurious Emissions on GSM
Summary
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Mason Communications Training: WCDMA Radio Planning Course
Module 4: UMTS Design Elements
Section 4.3: Interference
Interference
Current Spectrum
1700
1800
GSM 1800
UPLINK
GB
FDD =
90MHz
1900
GSM 1800
DOWNLINK
2000
D
E
C
T
2100
2200
EUROPE
UPLINK
DOWNLINK
A D B EF C
GB
1
1
1
1
A D
1 B E F C
1
USA
GB= Guard Band
FDD =
80MHz
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Mason Communications Training: WCDMA Radio Planning Course
Module 4: UMTS Design Elements
Section 4.3: Interference
Interference
DECT and UMTS Allocations
1850
1860
1870 1880
DCS 1800
DOWNLINK
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D
1900
B
1
E F
1910
1920 1930 1940
1950
1960
1970
1980 1990 2000
EUROPE
DECT
UMTS
A
1890
2
3
A1
C
© Mason Communications Ltd 2001
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D1
4
B1
E1 F1
C1
USA
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Mason Communications Training: WCDMA Radio Planning Course
Module 4: UMTS Design Elements
Section 4.3: Interference
Interference
USA Case
• A, B and C = 15MHz = 15000/200=75 -1 - 2 = 72 channels
• D, E and F = 5MHz = 5000/200 = 25 - 1 - 2 = 22 channels
A
D
B
E F
C
Guard
Band
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B1
E 1 F1
C1
200kHz
Extra guard (200kHz) to meet
FCC out-of-band rejection
GSM guard (100kHz)
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D1
23 24
1 2 3
100kHz
A1
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Mason Communications Training: WCDMA Radio Planning Course
Module 4: UMTS Design Elements
Section 4.3: Interference
Interference
PCS - PCS Interference
Handset
Technology B
Handset
Technology A
Base Station
Technology A
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Base Station
Technology B
© Mason Communications Ltd 2001
4.3.15
The above example happened in the USA where dissimilar technologies occurred, e.g.
GSM1900 and IS-95 at 1900MHz.
It is not uncommon to use very tall towers (50m) compared with the UK.
If Technology A was GSM1900 and Technology B was IS-95 then when one mobile was at
the edge of its service coverage and another technology came close to the base station then
desensitisation of the base station could occur resulting in the mobile at the cell edge being
dropped.
In these circumstances there are good reasons to co-locate the technologies together on the
same mast.
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Mason Communications Training: WCDMA Radio Planning Course
Module 4: UMTS Design Elements
Section 4.3: Interference
Interference
PCS - PCS Interference
Effect
= Receiver De-sensitisation
= Smaller Cells than designed for
= Dropped Calls etc.
Biggest impact on new operators in rural areas or areas of
patchy coverage
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Mason Communications Training: WCDMA Radio Planning Course
Module 4: UMTS Design Elements
Section 4.3: Interference
Interference
Inter-Operation Interference at
Spectrum Boundary
Operator B’s BTS
Operator A’s BTS
receiving minimum signal
Operator A’s MS
Operator B’s MS
@full power
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Reduced cell coverage
© Mason Communications Ltd 2001
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Original cell extent
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Mason Communications Training: WCDMA Radio Planning Course
Module 4: UMTS Design Elements
Section 4.3: Interference
Interference
Boundary Interference
• The previous mentioned effects can be mitigated by:
– Co-locate technologies on the same site, i.e. reduces
tendency for mobile close to BTS to use maximum pwr
– Migrate frequency plans from centre of allocation
– Co-ordinate frequency plans of operators. This is
particularly true for national boundaries, see ETSI
– Co-ordinate site engineering, e.g. antenna location,
filtering and power levels
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Mason Communications Training: WCDMA Radio Planning Course
Module 4: UMTS Design Elements
Section 4.3: Interference
Interference
Frequency Co-ordination (GSM)
• This is dealt with in an ETSI Technical Report (ETR) number
103 (ref: RTR/SMG-020330Q-1) “European digital cellular
telecommunications (Phase 2); Radio network planning
aspects (GSM 03.30) “ section 4.8 where it states:
“ Frequency co-ordination between countries is a matter of
negotiations between countries as described in CEPT Rec.
T/R 25-04. Co-channel and 200kHz adjacent channels need
to be considered between PLMNs and other services as
stated in GSM 05.05.
Frequency sharing between GSM countries is regulated in
Cept Rec. T/R 20-08 concerning frequency planning and
frequency co-ordination for the GSM service.”
We’ve yet to see what happens for WCDMA!
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© Mason Communications Ltd 2001
4.3.19
The above was for GSM. To date we have not seen a similar document for UMTS.
Note that unlike GSM, there is not true harmonisation across Europe for the UMTS
carriers.
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Mason Communications Training: WCDMA Radio Planning Course
Module 4: UMTS Design Elements
Section 4.3: Interference
Interference
Out of Band Interference
• Interference caused by broad-band or spectrally close
sources overlapping your band
Operating
Band
Unwanted
Source
• Note: LNAs and active devices at the antenna are
susceptible to this form of interference band
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Mason Communications Training: WCDMA Radio Planning Course
Module 4: UMTS Design Elements
Section 4.3: Interference
Interference
Out-of-Band Reduction
• New, or additional, filtering can be implemented to reduce
the effects of the interfering source
– This can be difficult to implement whilst at the same
time maintaining RX performance
• If the new source is in close proximity, i.e. tens of
wavelengths, then increased antenna separation and/or reorientation can be used
– Near field losses should be calculated, i.e. not standard
Friis equation, to determine degree of coupling between
the two systems
Un-written rule: Last on site, tidies up interference
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Mason Communications Training: WCDMA Radio Planning Course
Module 4: UMTS Design Elements
Section 4.3: Interference
Interference
Where Are We Now?
UMTS
Design Elements
General Classifications of Interference
Matched
Filters and
Rake Receivers
Antenna
Part II
US Multi-Technology Experience
Intermods
Interference
General and UK UTRA Spectrum Allocations
WCDMA
Physical Layer
Basic Transmitter Specifications
Impact of WCDMA Spurious Emissions on GSM
Summary
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Mason Communications Training: WCDMA Radio Planning Course
Module 4: UMTS Design Elements
Section 4.3: Interference
Interference
Intermods
Own band
Pwr
Other Users
Antenna
Coupling
LNA
Own
Antenna
Coupling
Coupling
Unwanted
Intermod Products
Freq
Coupling
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Mason Communications Training: WCDMA Radio Planning Course
Module 4: UMTS Design Elements
Section 4.3: Interference
Interference
Intermods
Third order
intercept
Output
Power
(dBm)
Third order
intermod products
(x3 input signal)
Input power (dBm)
• Intermods can be traced using the fact that the intermod
products increase three times faster than the input signal.
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Mason Communications Training: WCDMA Radio Planning Course
Module 4: UMTS Design Elements
Section 4.3: Interference
Interference
Identification of Intermods
Non-Linear
Device
Wanted
f1
Intermods
f2
Non-Linear
Device
f1
f2
Wanted @ -X dB
X dB
Pad
Intermods @ -3X dB
Non-Linear
Device
f1
f2
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Wanted @ -X dB
X dB
Pad
© Mason Communications Ltd 2001
Intermods @ -X dB
4.3.25
The pad is an attenuator.
Devices such as amplifiers driven too hard, dissimilar metal junctions etc. can act in a nonlinear manner and hence introduce Inter-modulation Products.
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Mason Communications Training: WCDMA Radio Planning Course
Module 4: UMTS Design Elements
Section 4.3: Interference
Interference
Interference
• The following items can also be sources of intermodulation
products:
• LNAs
– If the LNA has a broad frequency input, e.g. >>
operating band, then under strong signal conditions the
LNA can produce IMs which are delivered to the Rx
• Repeaters
– If broad band, high gain, repeaters are used then IMs
can be produced which are difficult to identify
– These will certainly be a challenge for 3G
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Mason Communications Training: WCDMA Radio Planning Course
Module 4: UMTS Design Elements
Section 4.3: Interference
Interference
Where Are We Now?
UMTS
Design Elements
General Classifications of Interference
Matched
Filters and
Rake Receivers
Antenna
Part II
US Multi-Technology Experience
Intermods
Interference
General and UK UTRA Spectrum Allocations
WCDMA
Physical Layer
Basic Transmitter Specifications
Impact of WCDMA Spurious Emissions on GSM
Summary
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Mason Communications Training: WCDMA Radio Planning Course
Module 4: UMTS Design Elements
Section 4.3: Interference
Interference
FDD Uplink
4.9MHz
4.9MHz
4.9MHz
4.9MHz
TDD
MHz
1979.7
1980.0
1919.9
1920.3
1900.0
1900.3
3G UK TDD and FDD Spectrum
14.6MHz
10MHz
14.8MHz
10MHz 10MHz
14.6MHz
10MHz
14.8MHz
10MHz 10MHz
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MHz
2110.0
2110.3
2169.7
2170.0
FDD Downlink
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Mason Communications Training: WCDMA Radio Planning Course
Module 4: UMTS Design Elements
Section 4.3: Interference
Interference
3G General FDD Spectrum
1920
2110
1980
DL
UL
Europe
2170
190MHz
Min 134.8
Max 245.2
1850
1910
1930
1990
ITU-Region 2
80MHz
Note: Not to scale
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Nominal 5MHz channel
Channel raster of 200kHz
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Mason Communications Training: WCDMA Radio Planning Course
Module 4: UMTS Design Elements
Section 4.3: Interference
Interference
UTRA Spectrum in relation to GSM1800
GSM1800
1710
1785 1805
Tx
3G-UTRA
1880
1920
1980
2110
2170
DECT
Rx
Note: Not to scale
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© Mason Communications Ltd 2001
4.3.30
The thickness of the arrows above represents the signal strength. Clearly, a transmitted
signal will have a higher value than that detected at the receiver.
For example the UE will transmit at 21dBm whilst the base station is expecting to receiver
at less than –100dBm.
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Mason Communications Training: WCDMA Radio Planning Course
Module 4: UMTS Design Elements
Section 4.3: Interference
Interference
Where Are We Now?
UMTS
Design Elements
General Classifications of Interference
Matched
Filters and
Rake Receivers
Antenna
Part II
US Multi-Technology Experience
Intermods
Interference
General and UK UTRA Spectrum Allocations
WCDMA
Physical Layer
Basic Transmitter Specifications
Impact of WCDMA Spurious Emissions on GSM
Summary
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Mason Communications Training: WCDMA Radio Planning Course
Module 4: UMTS Design Elements
Section 4.3: Interference
Interference
Base Station Transmitter power
• 3GPP does not state the base station output power – left to
the manufacturer
• Power measured either:
•
At output of cabinet if no external LNAs and filters
used or
•
At output of final device (filter) prior to antenna
• Maximum power must stay within ±2dB of manufacturers
rated output level for normal conditions or ±2.5dB for
extreme conditions
• Power control steps (inner loop for a code channel); 1dB is
mandatory and 0.5dB is optional
• The maximum power is set by the licence
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4.3.32
Note that the tolerances above represent large values and care should be taken in planning
the network that this variability is accounted for.
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Mason Communications Training: WCDMA Radio Planning Course
Module 4: UMTS Design Elements
Section 4.3: Interference
Interference
Spectrum Emission Mask (Illustrative)
2.5 2.7
3.5
7.5
-15
P=43dBm
o
-20
P=39dBm
-25
F_offsetmax
0
-5
-10
-30
-15
-35
-20
P=31dBm
-25
rewoP
P
-40
dBm )
d
B) w m
Frequency Separation from Carrier (MHz)
Note:10log(1MHz/30KHz)
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Source:3GPP TS 25.104 V3.5.0 (2000-12)
© Mason Communications Ltd 2001
4.3.33
The spectrum emission mask used by 3GPP uses three different base station power outputs,
43, 39 and 31dBm. Use the appropriate, and/or interpolate, for values used in your system.
Note that the two ordinates are related to each other by their respective bandwidths of
measurement.
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Mason Communications Training: WCDMA Radio Planning Course
Module 4: UMTS Design Elements
Section 4.3: Interference
Interference
Where Are We Now?
UMTS
Design Elements
General Classifications of Interference
Matched
Filters and
Rake Receivers
Antenna
Part II
US Multi-Technology Experience
Intermods
Interference
General and UK UTRA Spectrum Allocations
WCDMA
Physical Layer
Basic Transmitter Specifications
Impact of WCDMA Spurious Emissions on GSM
Summary
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Mason Communications Training: WCDMA Radio Planning Course
Module 4: UMTS Design Elements
Section 4.3: Interference
Interference
Adjacent Channel Leakage Power Ratio (ACLR)
• ACLR is defined as:
•
(transmitted power)/(power measured in an adjacent
channel)
•
Measured using a matched filter - root raised cosine
filter (roll-off of 0.22, see later) whose noise power
bandwidth = chip rate (3.84 Mchips /s)
• Applicable to single and multiple carrier base stations
BS Adjacent Channel
offset
ACLR Limit
5MHz
45dB
10MHz
50dB
Source:3GPP TS 25.104 V3.5.0 (2000-12)
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Mason Communications Training: WCDMA Radio Planning Course
Module 4: UMTS Design Elements
Section 4.3: Interference
Interference
Adjacent Channel Leakage Power Ratio (ACLR)
• Impact of ACLR
• Non standard (5MHz) channel separations causes leakage over and
above specified limits which results in capacity reduction resulting
from effective increase in ‘self’ interference
14.6MHz
10MHz
4.87MHz channel separation
5MHz channel separation
• Deployment strategy required to mitigate the effects of capacity
reduction through additional ACLR
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Mason Communications Training: WCDMA Radio Planning Course
Module 4: UMTS Design Elements
Section 4.3: Interference
Interference
Co-existence with GSM
• Required for protection of GSM900 and GSM 1800, base
stations and mobiles, in geographic areas where both are
deployed with WCDMA!!
GSM
WCDMA
LNA
?
?
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© Mason Communications Ltd 2001
Filter
Re-position
Re-orient
Remove or
Co-locate
?
4.3.37
Note: Terminology is often confusing!
Co-location means either locating antennas on the same mast of within the same compound
on different masts (H3g)
Other terms often referred to are Site sharing which could mean on the same mast or
sharing the same compound but with different masts.
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Mason Communications Training: WCDMA Radio Planning Course
Module 4: UMTS Design Elements
Section 4.3: Interference
Interference
Co-existence with GSM
• The power of any UTRA spurious emissions shall not exceed the
following levels, measured in 100kHz bandwidth
Protection
GSM-MS
GSM-BTS
GSM900
GSM1800
Band(MHz) Same Area Co-located Band(MHz) Same Area Co-located
921-960
-57dBm
1805-1880
-47dBm
876-915
-98dBm
1710-1785
-98dBm
Source:3GPP TS 25.104 V3.5.0 (2000-12)
• Factors to be considered
•
•
•
•
GSM and W-CDMA antenna gains, G GSM(ϕ,θ), Gcdma (ϕ,θ)
Use LNA factors
Friis path loss modified by near field equation
Use measured spurious values
W-CDMA
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© Mason Communications Ltd 2001
GSM
4.3.38
The important factor here is that measure values are used.
Note the operators in the UK have held co-ordination meetings and a joint document has
been produced with agreed separation distances.
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Mason Communications Training: WCDMA Radio Planning Course
Module 4: UMTS Design Elements
Section 4.3: Interference
Interference
Transmit Pulse Shape Filter
• Pulse shaping (spectral containment) filter used is a Root
Raised Cosine (RRC) with a roll-off of α=0.22 (frequency
domain)
• Impulse response of the chip impulse filter RC0(t) and chip
duration are given by:
1.50E+00
RC0 (t) =
1.00E+00
 t


t  t
sin π (1− α) +4α cos π (1+ α)
 Tc

Tc  Tc

π
RC0(t)
Tc =
5.00E-01
2
t   t 
1 − 4α  
Tc   Tc  
1
≈ 026042
.
µs
chiprate
t(sec)
0.00E+00
0.00E+00
5.00E-07
1.00E-06
1.50E-06
-5.00E-01
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© Mason Communications Ltd 2001
4.3.39
Note a Fourier transform of the impulse response will shows the spectral shape of the
emissions.
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Mason Communications Training: WCDMA Radio Planning Course
Module 4: UMTS Design Elements
Section 4.3: Interference
Interference
Where Are We Now?
UMTS
Design Elements
General Classifications of Interference
Matched
Filters and
Rake Receivers
Antenna
Part II
US Multi-Technology Experience
Intermods
Interference
General and UK UTRA Spectrum Allocations
WCDMA
Physical Layer
Basic Transmitter Specifications
Impact of WCDMA Spurious Emissions on GSM
Summary
NJHY430O.PPT
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© Mason Communications Ltd 2001
Page 40
4.3.40
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Mason Communications Training: WCDMA Radio Planning Course
Module 4: UMTS Design Elements
Section 4.3: Interference
Interference
Summary
• In this section on Interference you have learnt
•
Interference can arise from Internal and External
sources
•
Intermods
•
3G Spectrum allocations
•
Impact of ACLR on capacity
• This section is important to you because
NJHY430O.PPT
•
WCDMA is interference/noise limited
•
Basic planning with regard to limiting impact of WCDMA
on GSM
© Mason Communications Ltd 2001
4.3.41
Summary
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Mason Communications Training: WCDMA Radio Planning Course
Module 4: UMTS Design Elements
Section 4.3: Interference
Interference
The End of Interference
Introduction
to UMTS
Course
Overview
UMTS
Overview
UMTS
Specifications
Access
Methods
WCDMA
Introduction
UMTS Model
Architecture
NJHY430O.PPT
NJHY430O
Intro to
Radio Planning
Mobile Radio
Channel
Comms Theory
Course
Overview
Notation
Any More
Questions?
Path
Loss
Statistics
Antenna
Part I
Basic Radio
Diversity
Principles
Local Mean
Signal
Intro to Link
Budgets
Narrowband
Channel
Intro to
Planning Tools
Wideband
Channel
Course
Wash Up
Diversity
© Mason Communications Ltd 2001
Page 42
UMTS
Design Elements
UMTS
Network Design
Matched
Filters and
Rake Receivers
UMTS Link
Budgets
Antennas
Part II
Interference
WCDMA
Physical Layer
UMTS Planning
Process
Site Placement
Radio Resource
Management
Course
Wash Up
4.3.42
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Mason Communications Training: WCDMA Radio Planning Course
Module 4: UMTS Design Elements
Section 4.3: Interference
Client
Presentation
Title
Date
Mason Communications Ltd
5 Exchange Quay
Manchester M5 3EF
England
Tel: +44 (0)161 877 7808
Fax: +44 (0)161 877 7810
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Mason Communications Training: WCDMA Radio Planning Course
Module 4: UMTS Design Elements
Section 4.3: Interference
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The information contained herein is the property of Mason Communications Ltd and
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