Download - 3. WCDMA Radio Planning Fundamentals
2 © Nokia Siemens Networks WCDMA Planning Fundamentals/Jan2008Customer Confidential
WCDMA Radio Planning FundamentalsDeepak YadavJan’2008
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Contents
Scope of 3G Network PlanningWCDMA Planning Process OverviewInput ParametersLink Budget OverviewSite Selection CriteriaCo Sitting and Interference Issues Nominal Planning FundamentalsNetAct Simulations Process Overview
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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
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Scope of 3G network planning
Packet Switched Core
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Network planning process & relation to business planning
marketing
business plan
traffic assumptions
Networkdimensioning
Code & freq. & interference plan
transmission plan
final NW topology/
architecture
parameter planning
coverage plan
Networkoptimization
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New issues in WCDMA planning process wrt GSM
CoveragePlanning andSite Selection
ParameterPlanning
PropagationmeasurementsCoverageprediction
SiteacquisitionCoverageoptimisation
External InterferenceAnalysis
NetworkConfigurationandDimensioning
DEFINITION PLEMENTATION
Traffic distributionService distributionAllowed blocking/queuingSystem features
IdentificationAdaptation
Area / Cellspecific
Handoverstrategies
Maximumnetworkloading
Other RRM
NetworkOptimisation
O & M
Surveymeasurements
Statistical performance analysis
Quality Efficiency Availability
Capacity Requirements
Requirementsand strategyfor coverage,quality andcapacity,
per service
Multiple services
Coverage and capacitycoupling
Multiple services
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Radio networks Dimensioning Overview
COVERAGECOVERAGE CAPACITYCAPACITY
COMPROMISE BETWEEN COVERAGE AND CAPACITYCOMPROMISE BETWEEN COVERAGE AND CAPACITY
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UTRAN Radio Dimensioning
Customer Requirements
LINK BUDGETLINK BUDGET
Rel’99, CPICH, HSDPA, HSUPA
RF Planning Parameters• interf marg
• HO gain• environment
• etc.
RF Planning Parameters• interf marg
• HO gain• environment
• etc.
System Parameters
• Eb/No• TX power
• etc.
System Parameters
• Eb/No• TX power
• etc.
Infrastr. Parameters• # of sectors• antennas
• req cov area• etc.
Infrastr. Parameters• # of sectors• antennas
• req cov area• etc.
DIM TOOLDIM TOOL
Air Interface Dimensioning
(Capacity: Rel’99 + HSPA )
Traffic Demand
• per bearer• # of subs
• GoS• etc.
Traffic Demand
• per bearer• # of subs
• GoS• etc.
System Parameters
• spectral efficiency
• etc.
System Parameters
• spectral efficiency
• etc.
Number of NodeBs
NodeB Type
NodeB configuration:
- Amount
- BB dim
- NDR annex
- etc.
And NodeB Upgrade:
- #CHC / #FSM
- #Carrier
- Sectorisation
- …
Per area and Per area and
per Phaseper Phase
DIM TOOLDIM TOOL
NodeB Dimensioning CHC, DRIC, FSM)
- Ou
tpu
t to
war
d A
cces
s p
lan
nin
g
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Coverage VS Capacity Dimensioning:Cell Breathing
• This diagram shows cells are unloadunload
This diagram shows when some cells are loadedloaded
Cell-A
Cell-C
Cell-B
Results => Results => Coverage Holes!Coverage Holes!
Cell-A
Cell-C
Cell-B
Cell breathing
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Coverage VS Capacity Dimensioning:Fixed Uplink Load - To avoid Coverage holes
"actual" Loading, (ie from the traffic inputs defined in dimensioning)
This diagram shows a Fixed Uplink Load design
Results => No or Results => No or Min Coverage Min Coverage Holes!Holes!
Cell-A
Cell-C
Cell-B
Cell-A
Cell-D
Cell-H
Cell-E
Cell-F
Cell-C
Cell-B
Cell-G
• No (or minimum)
coverage holes problems
• More cells required
• Traffic mobility taken
into account. (Note:
dimensioning assumes
uniform traffic
distribution)
eg. Actual UL load = 8%
eg. Fixed UL load = 30%
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Input parameters – overview
CAPACITY RELATED Spectrum Available User Profile and Traffic Growth
Forecast Traffic Density Map
CAPACITY RELATED Spectrum Available User Profile and Traffic Growth
Forecast Traffic Density Map
COVERAGE RELATED Coverage Regions Area Type Information
COVERAGE RELATED Coverage Regions Area Type Information
QUALITY RELATED MS Class Indoor Coverage Location Probability Blocking Probability
QUALITY RELATED MS Class Indoor Coverage Location Probability Blocking Probability
Gives an Estimation of the Equipment Necessary to Meet the Network Requirements
Network Dimensioning Activities
Radio Link Budget Calculation
Cell Size Calculation Capacity Calculation Transmission Network
Estimate
Gives an Estimation of the Equipment Necessary to Meet the Network Requirements
Network Dimensioning Activities
Radio Link Budget Calculation
Cell Size Calculation Capacity Calculation Transmission Network
Estimate
Input Categories
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Summary of Dimensioning Inputs
Dense Urban Urban Suburban Rural
Voice # of subs & mErl per sub
# of subs & mErl per sub
# of subs & mErl per sub
# of subs & mErl per sub
CS data # of subs & mErl per sub
# of subs & mErl per sub
# of subs & mErl per sub
# of subs & mErl per sub
PS data # of subs & kbps per sub
# of subs & kbps per sub
# of subs & kbps per sub
# of subs & kbps per sub
Coverage area km2 km2 km2 km2
Location probability % % % %
Standard deviation dB dB dB dB
Fade margin dB dB dB dB
Penetration loss dB dB dB dB
Area correction factor dB dB dB dB
MS / Node B antenna height m m m m
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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
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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)
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Site Selection Criteria
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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
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How do I asses a site option?
Each site needs to be assessed on several grounds.RadioTransmissionAccessPowerPlanning
Ideally every site option reported by the surveyor would pass in each of the areas listed above.
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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
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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.
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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
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1)_1( kk
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1
Uplink Load EquationUplink Load EquationUplink Load EquationUplink Load Equation Downlink Load EquationDownlink Load EquationDownlink Load EquationDownlink Load Equation
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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
Max
imum
pro
paga
tion
loss
(dB
)
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 dBiRESULT: Doubling of the "little i" will cause throughput to decrease to 70% of the original value
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i = Coverage Overlap
Some overlap is required to allow soft handover to occurNeed 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
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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)
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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
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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
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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 Downlink Load EquationEquation
Downlink Load Downlink Load EquationEquation
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kkk
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1
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1
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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.
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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 !!!
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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Interference Issues
Wideband Noise - unwanted emissions from modulation process and non-linearity of transmitterSpurious Emissions - Harmonic, Parasitic, Inter-modulation productsBlocking - Transmitter carriers from another systemInter-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
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Interference IssuesNonlinear 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
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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 DLDL
1920-1980 MHz
2110-2170 MHz
40 MHz
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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 MHz1805 - 1880 MHz 1920 - 1980 MHz2110 - 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
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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
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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
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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
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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 antennasThe 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
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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 systemsBetter to avoid sites used for safety critical applications.
UMTS antennas
Other systems
Minimum separation
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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
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Antenna installation
d has to be >3.2 m
Safety margin of 15 between the reflecting surface and the 3 dB lobe
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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 !
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Nominal Planning for UMTS
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What is a nominal plan?
A nominal plan is initially a hypothetical wireless network.The nominal plan is the starting point for the cell rollout process and will evolve into the final network design.As physical sites are identified and acquired, the nominal plan is amended.
Nominal Plan
Final Network Design
Rollout process
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Initial Network Dimensioning
Spreadsheet based analysis.Used in the license application.Identifies the approximate number of sites required.Identifies the approximate site radii required for:
Urban/Suburban/Rural areasVoice/Data services
Used as a major input to the nominal plan.
Urban Suburban RuralVoice 1.8 km 3.1 km 4.4 km64 kb/s 1.6 km 2.7 km 3.5 km384 kb/s 1.1 km 2.4 km 3.2 km
Typical cell radii estimates
Maximum range to support all services
Service not supported in this environment
Service supported
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Create Nominal Plan
Position a hexagonal grid of sites over the desired coverage area.The radius of each hexagon can be determined from the previous slide.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
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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.
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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
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Identify Site Options
Surveyor visits each search area and identifies potential site options.The first sites to be considered should be
– Existing radio sites.
– Sites offered from major site owners (MSO) E.g. Utilities & Railways.
All options should meet certain criteria to ensure that they are– Technically acceptable.
– Build able
A good idea to consult with the planning/zoning authority during the survey.Good training of surveyors will save time later in the build process.
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Identify Site Options
The surveyor will prepare a report listing the options.Report will include:
– Accurate grid reference.
– Accurate height of structures or available antenna windows.
– Photographs of the site.
– 360º panoramic photos from site or if obstructed from nearby location/structure.
A
D
C B
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Site Selection
Normally a desk study.Evaluate radio coverage and transmission.
Quickly eliminate unsuitable options.
Rank the remaining sites in order of preference.
Nominate a preferred option and possibly a backup option.
A3rd
D1st
C2ndB - Unsuitable
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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
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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.
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Thank You