Day 1 2. WCDMA Planning

1 © 2005 Nokia V1-Filename.ppt / yyyy-mm-dd / Initials

Company Confidential

WCDMA Network Planning Deepak Yadav9th April 2007



Contents

• WCDMA Planning Process Overview

• WCDMA Link Budget

• WCDMA Nominal Planning

• Site Selection Criteria

• Isolation Requirements



Simplified Network Planning Flowchart

Create nominal plan

Define search areas

Site selection

Detailed site design

Site acquisition

CW Measurement

Identify site options

Site construction

Initial network dimensioning



WCDMA Link Budget



Evaluate cell range using max system load and link budget for

user at the cell edge

Compute cell loading from traffic profile and

cell range

Compare cell loading with the maximum permissible system

load ?

Coverage limited max. cell range for specified max system load

Cell range known

Decrease max system

load

Equal to

Coverage Limited

Capacity Limited

Less than

Greaterthan

Link budget As part of Dimensioning

•Coverage and Capacity is coupling

Loading (capacity) is to be done separately between UL and DL using load equation.

Link budget is to be determined path loss and then cell range for each bearer in different load condition

It requires iteration to find the optimum of maximum load target and cell range

Commercial impact on number sites required in the coverage area

•Load calculation and Iteration process is not covered in this material. (referred to 3GRPESS for details)

Add Carrier/Decrease cell

radius(increase target

load)



Link Budget Overview

Noise figure

Cable losses

Soft handover gain,

antenna gain

Building Penetration loss

Body loss

Margins

PATH LOSS (L)

Max AllowedPath Loss (L)

= Tx Signal + All Gains – Other Losses – Rx Sensitivity



Eb/N0

• In order to meet the defined quality requirements (BLER) a certain average bit-energy divided by total noise+interference spectral density (Eb/N0) is needed. Nokia simulations for Eb/No are based on ITU recommendations.

• Eb is the received energy per bit from the wanted user,

• Io is the total received power density, from both interference and thermal noise, excluding the power of the wanted signal.

• Eb/No depends on:• Service• MS speed• Radio channel

Service Eb/No UL Eb/No DL

Voice 12.2 kbit/s, 3km/h 4 6,5RT 14kbit/s, 3km/h 4 6,5RT 64kbit/s, 3km/h 2 5,5NRT 144kbit/s, 3km/h 1,2 4,8NRT 384kbit/s, 3km/h 1 4,5



Required Eb/N0

dBR

W

I

p

N

E rxb 0

NothownDL PIII )1(

NothownUL PIII

Where:Prx = received powerR = bit rateW = bandwidthIown = total power received from the serving cell (excluding own signal)Ioth = total power received from other cellsPN = noise power = orthogonality factor



Required Ec/I0

• Required Ec/I0 is the required RF C/I needed in order to meet the baseband Eb/N0 criteria

• Ec/I0 independs on a bit rate

dBI

p

W

R

N

E

I

E rxbc 00

Energy per chip

Total power spectral density



Processing Gain

Eb/No= + 4 dB

Processing Gain

Voice 12.2 kbps

Noise level (ex. -105 dBm)

RT 64 kbps

- 21 dB

- 16 dB

NRT 384 kbps

Eb/No= + 2 dB

-9 dB

Eb/No= + 1 dB

+25 dB

+18 dB

+10 dB

Req

uire

d S

ign

al

Pow

er

because of the processing gain the spread signal can be

below the thermal noise level

SFR

W

B

BdBG

Baerer

Up

u



Interference Margin

Interference margin is calculated from the UL/DL loading () values. This parameter shows in DL how much the BTS "sensitivity" is decreased due to the network load (subscribers in the network) & in UL indicates the loss in link budget due to load

dBLog 110 10IMargin =

20

10

6

1.253

25% 50% 75% 99%

IMargin [dB]

Load factor



Soft Handover MDC Gain

• In DL there is some combining gain (about 1dB) due to MS maximal ratio combining

• soft and softer handovers included • from MS point there is no difference between soft and softer handover

• average is calculated over all the connections taking into account the average difference of the received signal branches (and MS speed)

• 40% of the connections in soft handover or in softer handover and 60% no soft handover

• taking into account the effect multiple transmitters (meaning the receiver MS will get 3dB more power)

• adding 3dB to the values in the graph

• combination of dynamic simulator results and static planning tool

• in case more than 2 connections - no more gain (compared to case of two branches)



Slow and Fast Fading

• Fast Fading Different signal paths interfere and affect the received signal

• Rice Fading – the dominant (usualy LOS) path exist

• Rayleigt Fading – no dominant path exist



Slow and Fast Fading

• Slow Fading (Log-normal Fading)In the real enviroment the propagation condition of the electromagnetic wave are not stable. Some location and time dependant variation in a signal strength appear when the mobile moves around (shadowing effect). The variation of the signal strength are normal distibuted on the logarithmical scale.

received signal level [dBm]

probability density

[dB] has to be measured

m

2

2

2exp

2

1)(

mx

xf



Power Control Headroom(Fast Fading Margin)

Power control headroom is the parameter to describe the margin against fast fading. This parameter is needed because at the cell edge the mobile does not have enough power to follow the fast fading dips. This is especially important for the slow moving mobiles

Power Control Headroom = (average required Ec/I0) without fast PC - (average required Ec/I0) with fast PC

Source: Radio Network Planning & Optimisation for UMTS; J. Laiho, A. Wacker, T. Novosad; Tab. 4.5

without fast PC with fast PC

5Hz 13,1 4,9 8,2

20Hz 11,5 5,7 5,8

40Hz 9,7 6,0 3,7

100Hz 7,9 6,0 1,9

240Hz 6,5 6,3 0,2

average requierd Ec/ I o [dB]max Doppler f r.

Power Control

Headroom

Channel: Pedestrian A;antenna diversity assumed



Soft Handover Gain(Gain Against Slow Fading)

• Soft handover gain is the gain against shadow fading. This is roughly the gain of a handover algorithm, in which the best BTS can always be chosen (based on minimal transmission power of MS) against a hard handover algorithm based on geometrical distance.

• In reality the SHO gain is a function of required coverage probability and the standard deviation of the signal for the environment.

• The gain is also dependent on whether the user is outdoors, where the likelihood of multiple servers is high, or indoors where the radio channel tends to be dominated by a much smaller number of serving cells.

• For indoors users the recommendation is to use smaller SHO gain value.



Bit rate bit/s 64000 aTotal TX power available dBm 21 bTX antenna gain dBi 2 cBody loss dB 0 dTX EIRP per traffic channel dBm 23 e=b+c-dRX antenna gain dBi 18 fRX cable and connector losses dB 3 gReceiver noise figure dB 3 hThermal noise density dBm/Hz -174 jCell loading % 70 kNoise rise due to interference dB 5.23 l=10*log10(1/(1-(k/100)))Total effect of noise dBm/Hz -171 m=h+jInformation rate dBHz 48.06 n=db(a)Effective required Eb/No dB 2.54 oRX sensitivity dBm -115.40 p=l+m+n+o+correction factorSoft Handoff Gain dB 4.5 qFast fading Margin dB 2.5 rLog normal fade margin dB 11.6 sIn-building penetration loss (urban) dB 20 tMaximum path loss urban dB 123.80 pl=e+f+q-g-p-r-s-t

Uplink Budget

Service Bit Rate

Max. UE power

Tx antenna gain, e.g. 2dBi for a dipoleAttenuation due to body obstruction.

Rx antenna gain in the boresight directionCable and connector losses between the Rx antenna and the cabinet

Source thermal noise

Loading converted to noise riseLoading in the cell

due to other users

Added system noise

Bit rate converted to dB

+

Attenuation through building walls

Effective Isotropic Power from the Tx antenna



Bit rate bit/s 64000 aTotal TX power available dBm 21 bTX antenna gain dBi 2 cBody loss dB 0 dTX EIRP per traffic channel dBm 23 e=b+c-dRX antenna gain dBi 18 fRX cable and connector losses dB 3 gReceiver noise figure dB 3 hThermal noise density dBm/Hz -174 jCell loading % 70 kNoise rise due to interference dB 5.23 l=10*log10(1/(1-(k/100)))Total effect of noise dBm/Hz -171 m=h+jInformation rate dBHz 48.06 n=db(a)Effective required Eb/No dB 2.54 oRX sensitivity dBm -115.40 p=l+m+n+o+correction factorSoft Handoff Gain dB 4.5 qFast fading Margin dB 2.5 rLog normal fade margin dB 11.6 sIn-building penetration loss (urban) dB 20 tMaximum path loss urban dB 123.80 pl=e+f+q-g-p-r-s-t

Path loss = Tx signal + all gains - losses - ( SNR + Noise)



UL & DL Link Budget CalculationsLink budget

Chip rate 3840,00 DL data rate 64,00UL Data rate 64,00 DL load 85%

UL Load 50%2

Uplink DownlinkRECEIVING END Node B UEThermal Noise Density dBm/Hz -173,98 -173,98Receiver Noise Figure dB 3,00 8,00Receiver Noise Density dBm/Hz -170,98 -165,98Noise Power [NoW] dBm -105,14 -100,14Reguired Eb/No dB 2,00 5,50Soft handover MDC gain dB 0,00 1,00Processing gain dB 17,78 17,78Interference margin (NR) dB 3,01 8,24Required Ec/Io [q] dB -15,78 -12,28Required Signal Power [S] dBm -117,91 -105,18Cable loss dB 2,00 0,00Body loss dB 0,00 0,00Antenna gain RX dBi 18,00 0,00Soft handover gain dB 2,00 2,00Power control headroom dB 3,00 0,00Istropic power dBm -132,91 -107,18

TRANSMITTING END UE Node BPower per connection dBm 21,00 24,73Cable loss dB 0,00 2,00Body loss dB 0,00 0Antenna gain TX dBi 0,00 18Peak EIRP dBm 21,00 40,73Isotropic path loss dB 153,91 147,91DL peak to average ratio dB 6,00Isotropic path loss to the cell border 153,91

NRT 64kbit/s, 3km/hNRT 64kbit/s, 3km/hNRT 64kbit/s, 3km/hNRT 64kbit/s, 3km/h

• The calculation is done for each service (bit rate) separately

• The link budget must be balanced



WCDMA Nominal Planning



Create Nominal Plan

• Position a hexagonal grid of sites over the desired coverage area.

• The radius of each hexagon can be determined from the link budget.

• The capacity of the network can then be analyzed to detect:

• Hot spots that require cell splits.

• Under used cells that could be removed from the plan.

Example nominal plan for Jersey



Define Search Areas

• The sites in a nominal plan are only imaginary.

• To become a real network, physical sites are required.

• A suitable physical site must be found for each nominal site.

• A suitable physical site must amongst other things:• Give adequate radio coverage.

• Have connectivity into the transmission network.

• Be aesthetically and politically acceptable to the local community.

• Have power nearby, good access and a co-operative owner.

• A survey of each nominal site is normally carried out to identify possible site options which meet the above criteria.



Define Search Areas

• Guidelines have to be given to the surveyor so the options give appropriate radio coverage.

• The guideline is given in the form of a search area. Could be:• Radius from the nominal site.

• One or more polygons following height contours.

Or



Detailed Site Design

• Prior to commencement of construction work, a detailed site design is required.

• Includes• Antenna and feeder requirements.

• Antenna azimuths and tilts.

• Equipment capacity requirements

• Can’t be completed in isolation. Must take into account other sites.

60º

60º

180º180º

300º

300º

Ant 1

Ant 2

Ant 5

Ant 4

Ant 6

Ant 3



Setting up NetAct for Nominal Planning

Import suitable antenna patterns

Create UMTS cell layer

Create a UMTS propagation model

Create UMTS site templates



Create a UMTS Propagation Model

• In a real network rollout one of the first tasks of the radio engineers would be to calibrate a UMTS propagation model.

• For the purposes of the following sections we will assume that this has been completed.

• Set up a propagation model with the parameters described here.

Parameter Setting Clutter Type OffsetModel Type Standard Macrocell Unclassified 0Frequency 2200 Urban 10

Mobile Rx Height 1.5 Suburban Residential 5Effective Earth Radius 8491 Village 3

K1 143 Isolated Dwellings 2K2 42 Open Rural 1K3 -2.55 Woodland Forest 7K4 0 Park Recreational 2K5 -13.82 Industry 5K6 -6.55 Water 0K7 0.8 Airport 1

Eff. Ant. Height Relative Open in urban 5Diffraction Bullington Agricultural land 1

Merge knife edges 0 Pylons 1Sea 0Rivers 0



Import Antenna Pattern

• Import the antenna patterns supplied by the manufacturers.



Create Coverage Schema & Cell Layer

• The only parameters that are necessary to set on the cell layer are the signal thresholds and the coverage schema.

• These are derived from the link budgets used in the network dimensioning.



Create Site Templates

• Create default nominal sites• either an omni site.

• and/or a sector site.

• 3 sector parameters listed here.

Level Tab Field SettingSite General Hex Radius #1Cell General Model UMTSCell Cell Config Antenna 85 XPCell Cell Config Downtilt 4Cell Cell Config Height 20Cell Cell Config Azimuth #2

UMTS cell layer Antenna/TRX PA output 33

#1 Will depend on area type egUrban/Suburban/Rural

#2 Typically either 0º, 120º, 240ºor 60º, 180º, 300º.



Creating a Nominal Plan

• From the link budgets, identify the cell radius for each environment to be planned.

• Create a UMTS site template

• For each environment, position a hexagonal grid of sites with the appropriate cell radii over the target coverage area.



Locating Urban Nominal Sites

• Define mid hexagon radius as 1100m and select in the site template.

• Position a grid of sufficient sites to cover the urban areas.



Locating Rural Nominal Sites

• Select Hexagon Radius in the site template to be 4400m.

• Position a grid of sufficient sites to cover the rural areas.



Evaluate Nominal Network Coverage

• Run a coverage array for the nominal network.

• Check that the coverage is in line with your expectations.

• Adjust site locations and add additional sites if improvements to coverage is necessary.

• Check for excessively high sites.



Evaluate Nominal Network Capacity

• Create a traffic raster for each service.

• Create a terminal type for each service.

• Spread traffic for each terminal type to simulate users.

• Analyze how much traffic each cell will pick up (capture).

• Evaluate if each cell has sufficient capacity.

Create Traffic Raster

Capture Traffic

Evaluate Each Cells Required Capacity

Re-Engineer Network (if required)



Create Terminal Types

• Create a circuit switched terminal type for each service.

• Allocate traffic to simulate users.• Voice = 200 Erlangs

• 384 kb/s = 100 Erlangs (simulating 100 terminals)

Clutter Type Weight

Urban 500Open in urban 30

Suburban Residential 20Industry 10Village 10Airport 5

Park Recreational 5Woodland Forest 2Agricultural land 1

Isolated Dwellings 1Open Rural 1

Pylons 1Rivers 0Sea 0

Unclassified 0Water 0



Spread Voice Traffic

• Spread the traffic on the voice terminal type over the island.



Create Coverage Array (Voice)

• Set the minimum service level in the Array Settings window to match the minimum threshold for speech services.

• i.e. -114dBm

• Create coverage array as usual.



Analyze Voice Traffic

• Use the traffic analysis tool to estimate the voice traffic per cell.

Cell: CS Traffic(E)Site0A: 1.27874Site0B: 18.989Site0C: 2.64128Site1A: 18.1042Site1B: 0.099755Site1C: 1.71587Site2A: 2.13376Site2B: 1.58312Site2C: 105.062Site3A: 11.8475Site3B: 2.43671Site3C: 12.1231Site4A: 2.06883Site4B: 1.76368Site4C: 1.87409Site5A: 1.58884Site5B: 3.31571Site5C: 3.13637Site6A: 1.81907Site6B: 3.5485



Spread Data Traffic

• Spread the traffic on the data terminal type over the island.



Create Coverage Array (Data)

• Set the minimum service level in the Array Settings window to match the minimum threshold for data services.

• i.e. -96dBm

• Create coverage array as usual.



Site Selection Criteria



Site Selection Criteria

• Proper site location determines usefulness of its cells

• Sites are expensive

• Sites are long-term investments

• Site acquisition is a slow process

• Hundreds/thousands of sites needed per network

Base station sites are valuableBase station sites are valuablelong-term assets for the operatorlong-term assets for the operator



How do I asses a site option?

• Each site needs to be assessed on several grounds.• Radio

• Transmission

• Access

• Power

• Planning

• Ideally every site option reported by the surveyor would pass in each of the areas listed above.



Bad GSM Sites

• In GSM, there were two types of bad sites.• Donkeys - Low sites which provide very little coverage.

• Donkeys carry so little traffic that they often never pay for themselves.

• Boomers - High sites which propagate much further than is needed.• A boomer will cause localised interference and prevent capacity being added to some

other sites in the area.

Small “Donkey” site Large “Boomer” site



Bad UMTS Sites

• Good radio engineering practice doesn’t change much for UMTS.• It just becomes more important.

• In UMTS • A “Donkey” will never pay for itself.

• A “Boomer” will reduce the range and capacity of surrounding sites.

• Two major factors determine whether a site is considered good, a “Donkey” or a “Boomer”, They are:

• Site location.

• Antenna height.

• Other parameters can be used in an attempt to control booming sites but it is far better to avoid building them in the first place.



Importance of Controlling 'Little i'

• WCDMA is an interference-limited network. I.e. capacity of the network is directly linked to how interference is maintained/controlled.

• From the Radio Network Planning point of view, the "little i" - other-to-own cell interference- is the only thing that can really be influenced by the Planner during the site selection and planning stage. WCDMA RF planning is all about having good dominance in the desired coverage area.

• Unlike in GSM, that there is no frequency plan to "play" with in order to minimise the effects of bad sites.

K

k

kkko

b

UL

vRNE

Wirisepw

11

1)_1(

K

k

kkko

b

UL

vRNE

Wirisepw

11

1)_1( kk

k

kbK

kDL vi

RWNoE

1)/()/(

1

kkk

kbK

kDL vi

RWNoE

1)/()/(

1

Uplink Load EquationUplink Load EquationUplink Load EquationUplink Load Equation Downlink Load EquationDownlink Load EquationDownlink Load EquationDownlink Load Equation



Importance of Controlling 'Little i'

• Planners have to select the sites diligently so that the other-to-own cell interference ratio is MINIMIZED by planning clear dominance areas during site selection / planning phase.

0 500 1000 1500140

145

150

155

160

165

170

DL throughput in kbps

Ma

xim

um

pro

pa

ga

tion

loss

(d

B)

128 kbps

i = 0.2i = 0.2i = 0.4i = 0.4i = 0.6i = 0.6i = 0.8i = 0.8

BTS TX power 43 dBm

MS TX power 21 dBm

Ec/Io -16.5 dB

BTS Eb/No 1.5

MS Eb/No 5.5

Other to own cellinterference ratio i

0.2, 0.4, 0.6,

0.8

Orthogonality 0.6

Channel profile ITU VehicularA, 3 km/h

MS speed 3 km/h

MS/BTS NF 8 dB / 4 dB

Antenna gain 16 dBi• RESULT: Doubling of the "little i" will cause throughput to

decrease to 70% of the original value



i = Coverage Overlap

• Some overlap is required to allow soft handover to occur

• Need to control amount of interference since the network capacity is directly related to it.

• Soft handover helps to reduce interference. (Soft HO Gain)

• Too much overlap:• Increases interference to other cells --> reduce capacity

• Increases Soft Handover overhead --> reduce capacity



Bad Site Location

wanted cellboundary

uncontrolled, stronginterferences

interleaved coverage areas:weak own signal, strong foreign signal

• Avoid hill-top locations for BS sites (same for GSM)• uncontrolled interference

• interleaved coverage

• no sharp dominance areas

• awkward Soft/Hard HO behaviours

• BUT: good location for microwave links ! (TNP jurisdiction)



wanted cellboundary

Good Site Location

• Prefer sites off the hill-tops• use hills/high rise buildings to separate cells• contiguous coverage area• well defined dominance areas• needs only low antenna heights if sites are slightly elevated above valley

bottom



Characteristics of a good site

It has good clearance, no obstacles around, and it overlooks the surrounding rooftops. This site will give good macro coverage.

Bad site; blocked by neighbour building



Characteristics of a good site

BAD: In a urban/dense urban area, too high a site is a bad site since it will introduce too much interference to other sites in the network(remember the little i)

while for a rural area it's a good site.

Uplink Load EquationUplink Load EquationUplink Load EquationUplink Load Equation

Downlink Load EquationDownlink Load EquationDownlink Load EquationDownlink Load Equation

K

k

kkko

b

UL

vRNE

Wirisepw

11

1)_1(

K

k

kkko

b

UL

vRNE

Wirisepw

11

1)_1(

kkk

kbK

kDL vi

RWNoE

1)/()/(

1

kkk

kbK

kDL vi

RWNoE

1)/()/(

1



Examples of Bad Sites

Typical mess! =>GSM1800 antennas with space div. between CDMA (IS-95) antennas and pointing directly at the high building

GSM1800 and GSM900 antennas are too close=> Not enough isolation => Intermodulation and spurious emission.These situations can easily be

avoided!!

Time consuming and costly to fix.



Arghhh… note how far you can see -roughly 10km = TOO FAR. There is a riveras well, so interference is enormous. Sitedistance is about 700meters in thisphase!! Site was good in phase 1when distance between sites was 4km!

Well shit happens … who could have knownthat they were going to build this high building one year after installation ?! Planners shouldhave anticipated this during initial site surveys!

Examples of Bad SitesLittle i, Little i, Little i !!!



Examples of Bad Sites

The TX/RX and Rx div antennas are not pointingin the same direction! Installation problem.

Is this installation OK? The satellite dish is in near field of the GSM900 antennas -> some effects for sure. Definite interference to satellitesystem. But could not be tested because the satellite system was not in use! Avoid installing antennas in close proximity to other objects since its radiation pattern will be altered.



Examples of GOOD Sites

Enough space between the two Tx/Rx and Rx Div., AND pointing in the same direction! Site survey point of view: Provides clear dominance to the desired coverage area.



Summary of Site Selection Guidelines

• The objective is to select a site location which covers the desired area but keeps emissions to a minimum.

• The site should be located as close to the traffic source as possible.• The closer the site is to the traffic, the less output power will be required by the

user equipment and node B. This will minimise the noise affecting other users on both the serving cell as well as other nearby cells.

• The antenna height selected will depend largely on the type of environment in which the site is to be located. Eg Dense Urban, Urban, Suburban, Rural.

• The key factor to be considered is how well can the emissions be controlled.



Summary of Site Selection Guidelines• You can "feel" the site only if you are there!

• If one or more of these characteristics are not fulfilled by the examined site, the Field Planner should REJECT the site and choose another site

• Be flexible, even creative! Try to think of all the possible implementation solutions that the site could support: different pole heights, split poles for different sectors, etc.

• Always check neighbouring sites, to be sure your chosen candidate is "fitting" well into the surrounding, e.g. for coverage, SHO zones,etc.



Using Existing Cellular Sites

• Most UMTS networks will be built around an existing GSM network.

• Many GSM networks were built around existing analogue sites.

• In the early days of analogue cellular sites were often located to give maximum coverage. No thought was given to capacity issues.

• Despite causing problems in high capacity networks, many of these high sites are still in operation today.

• Most cellular networks contain these nightmare sites.

• When rolling out UMTS around an existing network it is vital to avoid these sites.



UMTS Configurations

• Most vendors support the same basic configurations.• Omni

• 3 sector

• 6 sector

• Each vendor supports their own variations on these configurations.• Some solutions eliminate the need for RF plumbing.

• Some require similar amounts of equipment to a GSM BTS.

• Some increase the number of antennas on a site.

• The configuration can be affected by the wide variety of UMTS antennas.



Co-locating a Node B at a GSM site

• Isolation requirements between UMTS and GSM systems can be derived from UMTS and GSM specifications.

• In many cases equipment performance will exceed the requirements in the specifications.

• Each vendor should be able to provide information which can be used to improve the isolation requirements.

• The isolation requirements will affect• Choice of antenna configuration

• Filtering at both the GSM and UMTS sites.

• Isolation is the attenuation from the output port of a transmitter to the input port of the receiver.



Interference Issues

• Wideband Noise - unwanted emissions from modulation process and non-linearity of transmitter

• Spurious Emissions - Harmonic, Parasitic, Inter-modulation products

• Blocking - Transmitter carriers from another system

• Inter-modulation Products - Spurious emission, specifications consider this in particular

• Active: non-linearities of active components - can be filtered out by BTS

• Passive: non-linearities of passive components - cannot be filtered out by BTS

• Other EMC problems - feeders, antennas, transceivers and receivers



Interference Issues• Nonlinear system transfer function can be expressed as a series

expansion

• In the case of one input frequency, vin = cos 1t, output will consist of harmonics, m1

• Fundamental (m = 1) frequency is the desired one.• If m > 1, there are higher order harmonics in output => harmonic

distortion.• Can be generated both inside an offender or a victim system.

• In the case of two input frequencies, vin = cos 1t + cos 2t , output will consist of harmonics m1 + n2, where n and m are positive or negative integers.

• Intermodulation is the process of generating an output signal containing frequency components not present in the input signal. Called intermodulation distortion (IMD).

• Most harmful are 3rd order (|m| + |n| = 3) products.• Can be generated both inside an offender or a victim system.

x y = a0 + a1x + a2x2 + a3x3 + ...System



Interference from Other System

• GSM spurious emissions and intermodulation results of GSM 1800 interfere WCDMA receiver sensitivity

• WCDMA spurious emissions interfere GSM receiver sensitivity

• GSM transmitter blocks WCDMA receiver

• WCDMA transmitter blocks GSM receiver

GSM GSM 1800 1800

ULUL

GSM GSM 1800 1800

DLDL

1710-1785 MHz

1805-1880 MHz

UMTS UMTS UL UL

UMTS UMTS DL DL

1920-1980 MHz

2110-2170 MHz

40 MHz



M Distortion from GSM1800 DL to WCDMA UL

• GSM1800 IM3 (3rd order intermodulation) products hits into the WCDMA FDD UL RX band if:

• 1862.6 f2 1879.8 MHz

• 1805.2 f1 1839.6 MHz

WCDMADL

WCDMAUL

GSM1800DL

GSM1800UL

1710 - 1785 MHz 1805 - 1880 MHz 1920 - 1980 MHz 2110 - 2170 MHz40 MHz

f1 f2

fIM3

fIM3 = 2f2 - f1

X dBc

• For active elements IMproducts levels are higherthan IM products producedby passive components• Typical IM3 suppressionvalues for power amplifiers are -30 … -50 dBc depending on frequencyspacing and offset• Typical values for passiveelements are -100 … -160 dBc



Harmonic distortion

• Harmonic distortion can be a problem in the case of co-siting of GSM900 and WCDMA.

• GSM900 DL frequencies are 935 - 960 MHz and second harmonics may fall into the WCDMA TDD band and into the lower end of the FDD band.

GSM900935 - 960 MHz

WCDMATDD

WCDMA FDD1920 - 1980

...

2nd harmonics

fGSM = 950 - 960 MHz

1900 -1920 MHz

2nd harmonics can be filtered out at the output of GSM900

BTS.

f



Isolation Requirements

GSM 900 GSM 1800 UMTSReceiving band

(UL)890 – 915 MHz 1710 – 1785 MHz 1920 – 1980 MHz

Transmitting band(DL)

935 – 960 MHz 1805 – 1880 MHz 2110 – 2170 MHz

GSM 1800 TxGSM 1800 Tx

1805 MHz1805 MHz 1880 MHz1880 MHz

UMTS RxUMTS Rx

1920 MHz1920 MHz 1980 MHz1980 MHz

GSM 1800 RxGSM 1800 Rx

1710 MHz1710 MHz 1785 MHz1785 MHz

UMTS RxUMTS Rx

2110 MHz2110 MHz 2170 MHz2170 MHz

For example - To prevent UMTS BTS blocking: with transmit power = 43 dBm For example - To prevent UMTS BTS blocking: with transmit power = 43 dBm

Max level of interfering signal for blocking = -15 dBm in UMTSMax level of interfering signal for blocking = -15 dBm in UMTS

Isolation required = 58 dBmIsolation required = 58 dBm



Achieving Isolation Requirements

• Isolation can be provided in a variety of different ways.

• By antenna selection and positioning.

• By filtering out the interfering signal.

• By using diplexers and triplexers with shared feeder and multiband antennas.

UMTSUMTS

GSMGSM

FilterFilter

UMTSUMTS

GSMGSM

DiplexerDiplexer

UMTSUMTS

GSMGSM



Co-siting - Antenna Installations• Difficult to calculate isolation between two antennas and

measurements are required.

• Best configurations - antennas pointing in different directions or where there is vertical separation between antennas

• The following configurations will should all give 30dB isolation.

dddd

dd

90º90º 120º120º

dd

dd180º180º

dd

d = 0.3 - 0.5 md = 0.3 - 0.5 m d = 1 - 3 md = 1 - 3 m d = 0.5 - 2 md = 0.5 - 2 m



Site sharing with third party systems

• Some UMTS sites might be co-located with other non GSM operators.

• PMR

• Broadcast

• Navigation

• Some of these systems use older equipment which might be more vulnerable to EMC issues.

• Need to define minimum antenna separations between systems

• Better to avoid sites used for safety critical applications.

UMTS antennas

Other systems

Minimum separation



Antenna installation issues: Clearance angle

h (meters)

d (meters)Clearance angle

• Rules of thumb: • h d/2, d < 10 m

• h d/3, 10 < d < 20 m

• h d/4, d > 30 m

Antenna

d (meters)

Top view

Side view



Antenna installation

d has to be >3.2 m

• Safety margin of 15 between the reflecting surface and the 3 dB lobe



Antenna installation: Other RF-systems

Not Acceptable

D O C U M E N T T Y P E 1 ( 1 )

T y p e U n itO r D e p a r tm e n tH e r eT y p e Y o u r N a m e H e r e T y p e D a te H e r e

A c c e p ta b le

B e c a re fu l w i thb a c k - lo b e !

Date post:	21-Nov-2014
Category:	Documents
Upload:	raghvendra-singh
View:	128 times
Download:	12 times

Day 1 2. WCDMA Planning

Documents