07_RN31548EN10GLA0_Coverage and Capacity Planning

7/27/2019 07_RN31548EN10GLA0_Coverage and Capacity Planning

http://slidepdf.com/reader/full/07rn31548en10gla0coverage-and-capacity-planning 1/89

Coverage and Capacity planning

Customer confidential

1 © NSN Siemens Networks 3G Radio Planning Essentials / NPO Capability Development

3GRPESS – Module 7



Module 7 – Coverage and capacity planning

Objectives

After this module the participant shall be able to:-

• Understand different planning approaches

• Understand specific HSDPA and HSUPA planning issues



• Understand different ways to optimise capacity



Content

• Site selection

• Coverage and interference planning

•



• Coverage and capacity improvement



Content

• Site selection


•






Site Selection – Motivation

• Sites represent expensive long term investments for the operator.

• Good site selection is critical to the performance of a 3G radionetwork.

• Neither RF optimisation nor parameter optimisation can compensate



.

• Site acquisition teams are often under pressure to offer largenumbers of sites while radio network planning teams are often under

pressure to accept large numbers of sites.

• Site selection criteria are used to evaluate whether or not a site issuitable.



Site selection criteria

• Site selection criteria can be divided into two categories

– Inclusion criteria

▪ Whether or not a site should be considered for inclusion within the 3G radio

network plan

▪ Sites with ‘No’ should be included only unless there are no alternatives and thebenefit of introducing the site is believed to justify its cost

– Prioritisation criteria



▪Prioritise those sites being considered for inclusion

▪ Select first sites with highest number of ‘Yes’

• These criteria should be evaluated after a site visit and not only

from the information available within a radio network planning tool



Site Inclusion criteria – Radio

1. Does the site allow the main beam of each proposedantenna to have good visibility of the surroundingterrain without any high obstacles blocking the view?

2. Can the main beam of each antenna be positionedsuch that it does not cross the main beam of another

antenna?3. Can the main beam of each antenna be positioned

such that they are not shadowed by the building orstructure upon which they are secured?

4. Can each antenna be mounted above the roof-to s of



the neighbouring buildings without being excessivelyabove them? – Typically < 10 m above the neighbouring roof-tops

5. Do neighbouring cells have antenna heights which arewithin 15 m of the proposed antenna heights?

6. Are neighbouring cells of similar size?

7. Is the site unlikely to be very dominant and unlikely tocause significant interference to neighbouring cells?

8. Is the best server area of the site unlikely to befragmented?



Site Inclusion criteria – Implementation

9. If the proposed site is a rooft-top site, is theresufficient space for the appropriate antennamountings to ensure that there is adequateclearance from the roof-top?

10. Is the site safe from new neighbouring buildingswhich may be constructed in the future andwhich may block the main beam of an antenna?

11. Are the cabling distances between the Node B



12. Is there access to leased lines or microwavelinks for transmission purposes?

13. Is there availability of the Node B power supplyrequirements?

14. Is there space to accommodate the Node Bequipment?

15. Are rental costs acceptable?

16. Is there reasonable access to the site?

• DC feed up to 200m

• multimode fiber 200m

• single mode fiber 15km



Site Prioritisation criteria

1. Is the site an existing GSM site?

2. Do antenna locations allow for changes in azimuth?

3. Do antenna locations allow for changes in height?

4. Do antenna locations allow sufficient isolation fromother antennas, e.g. GSM antennas?

5. Is the site away from environmentally protected orhistoric areas?

Existing site

Antenna sharing Cost of site

Access



6. Is the site unlikely to require any special permits?7. Is the site unlikely to cause public disapproval?

8. Does the site form a regular pattern with itsneighbours?

9. Is the site close to where the traffic is expected?

10. Is the site capable of accommodating potentialcapacity upgrades?

locationAnd so on…



Site Selection – Site Information

• Collect all necessary information about site details

– Site coordinates, height above sea level, exact address

– House owner

– Type of building

– Building materials (photo)

– Possible antenna heights



– 360deg photo (clearance view) – Neighbourhood, surrounding environment

– Drawing sketch of rooftop

– Antenna mounting conditions

– Access possibilities (truck?, road, roof) – BS location, approx. feeder lengths



Site Selection & Site Survey Tools

• A paper map of the area

• A paper diagram of the building

• Coverage plot from the planning tool• Best server plot from the planning tool

• A GPS receiver



• nocu ars an compass• A digital camera

• An altimeter

• A tape measure or other measuring device• Safety equipment if necessary



Site Selection / Site Survey documentation

• SARF

Site Acquisition Request Form

• SIR/SARSite Information (Acquisition) Report

• TSS report

Technical Site Surve Re ort



• TDRSTechnical Data for Radiating System

• ...



Content

• Site selection

• Coverage and interference planning – Pathloss based approach

– 3G Simulation based Approach



– p ann ng – HSUPA planning

• Capacity planning




Path Loss based Approach

• Relatively simple and most commonly adopted approach

• Uses software tools which are relatively mature

• Generates results which are easy to interpret• Makes use of maximum allowed path loss figures from link budgets

• Generates plots and statistics for 3G coverage, best server areas



Link Budget result for maximum allowed path loss 140 dB

Downlink transmit power in the planning tool 33 dBm

Node B antenna gain assumed in the link budgets 18 dBi

Feeder Loss assumed in the Link Budgets 2 dB

Planning tool signal strength threshold -91 dBm

Should also account for differences between the uplink anddownlink path loss (this approach uses the downlink path loss togauge coverage)

and C/I



Pilot power planning threshold

• Link budget, planning margin and planningthreshold definitions are important phasesof pathloss based 3G planning

Antenna gain

Antenna line losses



Received pilot power = Pilot transmit power – Antenna line losses + Antenna gain - (Max. pathloss – Planning margins )

CPICH EIRP



Pilot power planning threshold

• Pilot power planning threshold is the minimum outdoor pilot levelwhich is required in order to achieve the required CoverageProbability

• Pilot power planning threshold is based on power budgetcalculations and planning margin definitions –



– Eb/N0 – Location probability Slow fading margin

– Indoor/outdoor coverage

• Pilot power planning threshold have to be defined separately foreach service and area type – Select the threshold for limiting service



Pilot power planning threshold – Examples

Different services can have different coverage quality requirementsand thus also different planning margins

• Indoor (BPL = 12 dB, St. Dev. = 10 dB)

• 90 % location probability

Indoor



Speech -90.0 dBm Uplink limited

Video call -90.2 dBm Uplink limited

PS Data 384/384 -82.4 dBm Uplink limited

PS Data 384/HSDPA 384 -84.6 dBm Uplink limited

HSUPA 384/HSDPA 384 -85.4 dBm Uplink limited

HSUPA/HSDPA 1 Mbps -80.8 dBm Downlink limited



Effect of planning margin on coverage area

• Planning margin parameter settings have a major effect on the cellarea calculations

NRT 64/384 planning margin effect on Coverage Area

(stepped +/- 1dB)

80%

100%

120%

a



-80%

-60%

-40%

-20%

0%

20%

40%60%

-6 -4 -2 0 2 4 6

Change of parameter

E f f e c t i n

C o v e r a g e

A r e

Building penetration loss change (ref = 16dB)

Indoor standard deviation change (ref = 12dB)



Import SiteCandidates

DefinePropagation Model

Example Process for Path Loss based Approach

• Process should be customised for specific project requirements

• Coverage and Cell Isolation analysis should include best server areaanalysis



Compute Path Loss

Default Config.ComputeService LinkBudgets

Pilotthreshold

Coverage and Cell Isolation Analysis

Propagation Model



• Task divided into two activities

• Service coverage to be maximised while managing cell isolation

• Cell isolation translates to system capacity

Coverage and Cell Isolation AnalysisPath Loss Based Approach



Coverage and Cell Isolation Analysis

Coverage Analysisand Optimisation

Cell Isolation Analysisand Optimisation

Existing process New process



• Same array as currently used – termed ‘Best Server’ array

• Requirement to identify dominant clutter type and use appropriate pilot planningthreshold

• Pilot planning thresholds computed from dominant of uplink and downlink linkbudgets

Example Coverage ArrayPath Loss Based Approach





Example Coverage Report

• Service coverage report for dominant clutter type

• Used as a tool for quantifying gains and losses in coverage performance

• Coverage specified on a per clutter type basis

Path Loss Based Approach





Example Cell Isolation ArrayPath Loss Based Approach

• Downlink C/I array used – termed ‘Total Interference’ array

• Used as a tool for quantifying gains and losses in coverageperformance

• Requirement to include an edge zone of sites• Poor cell isolation can appear as poor C/I





Example Cell Isolation Array

• C/I report for -6 dB threshold, also generate for -3dB, +3dB and +6dB

• Used as a tool for quantifying gains and losses in C/I performance






Scenario modelled by C/Ianalysis: no SHO

Scenario with C/I greater than -6dB: manageable SHO

Scenario with C/I less than -6dB: excessive SHO

Accounting for Soft Handover (I)Path Loss Based Approach

• C/I analysis does not explicitly account for soft handover connections – some of the interfering connections will actually be soft handover connections

• C/I less than -6dB would lead to excessive soft handover connections

– an area with a C/I of -6dB is likely to have more than 3 soft handoverconnections

• C/I greater than -6dB still leads to sufficient soft handover regions that must bemanaged by the soft handover parameter set





Accounting for Soft Handover (II)

• 3G simulations can be used to illustrate the correspondencebetween C/I and the number of candidate soft handover connections

• 3G soft handover parameter set may be used to manage the

resultant soft handover overhead




C/I < -6 dBcorresponds toexcessive soft

handovercandidates

C/I > -6 dBcorresponds tosufficient soft

handovercandidates



Poor dominanceand strong best

Poor dominanceand weak bestserver signal

Hexagonal Site

Example of a Poor Cell Layout

• Areas of poor dominancecorrespond to inefficient use of theair interface

• Weak best server signals lead toareas susceptible to interference

• Solution is to change the cell layout




C/I < -6 dB C/I Coverage

Areas of poordominance – some

with low C/I

performance



Each antennadirected between two

others

Cloverleaf Site

Example of a Good Cell Layout

• Cloverleaf design

• C/I patterns mesh

• Dominance areasrelatively well defined




Both coverage andC/I performancerelatively good

C/I < -6 dB C/I Coverage

B



C/I > 12 dB

C/I < 12 dB

Example Network Performance (I)

• An example urban area

• Maximising coverage performance does not encourage antenna downtilts

• Downtilt should be used with caution to prevent excessive increases in site

density




No downtilts

poor C/I

C/I < 9 dB

C/I < 6 dB

C/I < 3 dB

C/I < -6 dB

C/I < -3 dB

C/I < 0 dB

Downtilts of up to 6°

improved C/I

P th L B d A h



Dense Urban

Urban

Suburban

Coverage

Example Network Performance (II)

• Corresponding plots of service coverage performance




Rural

No downtilts

non-contiguous local coverage

Downtilts of up to 6°

contiguous local coverage

• Local dense urban service coverage performance improved

• Downtilts have improved both the C/I and the local coverage performance

P th L B d A h



AppropriateAntennaHeights

Impact of Antenna Height

• High antennaplacement increaseslevels of remoteinterference




Excessively highantennas

Significant overlapof coverage areas

Degraded C/Iat remotelocations

Reduceddominance of

neighbors

Extensivedominance forthe highantenna

Excessive Antenna Heights



Content

• Site selection





– p ann ng

– HSUPA planning





3G Simulation based Approach

• is more complex and time consuming

• is often used for focused 3G system investigations rather than wide area radio networkplanning

• uses software tools which are less mature• generates results which are more difficult to interpret

• makes use of 3G parameter assumptions and a 3G traffic profile

• Generates lots and statistics for covera e ca acit soft handover intercell interference



uplink load and downlink transmit power, HSDPA Performance

Monte Carlo Simulation

• static simulation which considers snap shots in time

• for each snap shot a population of mobile terminals is distributed and the radio network

behaviour evaluated• simulation results are recorded as an average over many independent snap shots

• probability distributions can be generated

• in contrast to a dynamic simulation which runs over time

3G Simulation Based Approach



Snap shot

Calculate UE transmitpowers

Evaluate Uplink Cell

Start

Distribute terminals

Iteration


3G Simulation Algorithm

• On first iteration theuplink load is 0 % andthe total cell transmit

powers are only theCPICH and CommonControl Channels

•



Calculate cell transmitpowers per user

Evaluate total Celltransmit powers

oa

Record results

specific iteration if theuplink load or celltransmit power is toohigh

• UEs are blocked for aspecific snap shot ifthey are blocked forconsecutive iterations




Upgrade

CPICHPower

Add site

Example Process3G Simulation Based Approach

Coverage

Loaded network

• Increased scope for optimisation• Allows capacity to be quantified and so capacity upgrade solutions

can be studied

• Figure below represents one example



Tune

Validate

Validated Network

Soft HandoverOverhead

Realistic trafficprofiles

Include HSDPA

Increase sectorisation

Incr. BTS tx power

Add carrier

Capacity




• The Common Pilot Channel (CPICH) is used by UE for: – synchronisation and channel estimation

– handover and cell re-selection decisions

• CPICH Measurements are based upon RSCP and Ec/Io

– RSCP is an absolute power measurenet

– Ec/Io = RSCP/RSSI, and does not account for orthogonality

• CPICH Ec/Io and RSCP coverage must be sufficient

– CPICH Ec/Io affected by cell load


CPICH Optimisation



• typ ca y ass gne o t e tota own n transm t power capa ty

– ignoring intercell interference, this results in an Ec/Io of -10 dB when cell is fullyloaded

– Intercell interference will further decrease this value

• Potential for limited CPICH tuning, e.g. if neighbouring cells have MHA and verylarge differences in their cable losses

• If CPICH are tuned then important to ensure soft handover balance ismaintained

• RF optimisation should be completed prior to parameter optimisation




Ec/Io ArrayC/I Array


Example CPICH Ec/Io Array

•Similar to the C/I array generated by the path loss approach

• Areas of poor CPICH Ec/Io correspond to areas of poor C/I

• Live network minimum requirement for cell selection is typically -18 dB

• RRC Connection establishment success rate is poor at -18 dB

• Example planning minimum requirement is -15 dB when network is loaded






RSCP Array

pp

Example CPICH RSCP Array

• Provides a measure of link loss, i.e. linkloss = CPICH transmit power – CPICHRSCP

• Live network minimum requirement forcell selection is typically -115 dBm

• UE receiver thermal noise is typically -

38 © NSN Siemens Networks 3G Radio Planning Essentials / NPO Capability DevelopmentCustomer confidential

100 m an so an o -115

corresponds to an Ec/Io of -15 dB whenin thermal noise limited scenarios

• In RRC connected mode, inter-system

handover can be triggered at higherCPICH RSCP and Ec/Io


S f H d O i i i



pp

Soft Handover Optimisation

• Soft handover - UE is connected to multiple Node B

• Softer handover - UE is connected to multiple cells belonging to same Node B

• Soft and Softer handover generates overheads

– Soft handover overhead - transmit power, Node B baseband processing, Iub, RNC

– Softer handover overhead - transmit power

• Overhead must be sufficient to ensure reliable handover and maintain cell


• Total Overhead should not exceed 40 %

RF optimisation should be completed prior to parameter optimisation


E l A ti S t Si A (I)



Active set size (3 dB Window Add) Active set size (4 dB Window Add)

Example Active Set Size Arrays (I)

• Impact of addition window



E l A ti S t Si A (II)



Active set size (with fading) Active set size (no fading)

Example Active Set Size Arrays (II)

• Slow fading standard deviation and correlation factor has impact uponactive set size


C t t



Content

• Site selection




– p ann ng

– HSUPA planning



HSDPA Radio Network Planning Process



• Existing radio network planning process can be applied to HSDPA

• Focus continues to be:

– Coverage

– Dominance (inter-cell interference) – Size of best server areas

• Link budgets should be completed for HSDPA

• Macrocell deployment strategy likely to continue to be based upon R99 link

HSDPA Radio Network Planning Process


budget analysis

• Indoor solutions and specific traffic hotspots may be planned based uponHSDPA link budgets

• Planning tool can be used to generate an expectation of HSDPA throughput

• HSDPA supported by NetAct Planner – HSDPA throughput results can be

generated

HSDPA in NetAct Planner



Eb/No speed offsets

Bearer Coding rate Eb/No 0-3 km/h 50 km/h 120 km/h

QPSK_1_38 QPSK_38 0.82 5.19 0.33 -0.03

QPSK_2_36 QPSK_36 0.57 5.18 0.32 -0.02

QPSK_3_36 QPSK_36 0.57 5.18 0.32 -0.02

Modulation

Number of Codes

• NetAct Planner uses a look-up table to define the relationship between Eb/No andThroughput

• Bit rate determined by modulation, number of codes and coding rate, e.g. QPSK_5_64corresponds to a bit rate of: (3.84/SF16) * 0.64 coding rate * 2 bits per symbol * 5 codes= 1.536 Mbps

HSDPA in NetAct Planner


QPSK_4_36 QPSK_36 0.57 5.18 0.32 -0.02

QPSK_5_36 QPSK_36 0.57 5.18 0.32 -0.02QPSK_5_43 QPSK_43 1.39 5.21 0.36 -0.04

QPSK_5_50 QPSK_50 2.34 5.15 0.43 0.06

QPSK_5_57 QPSK_57 3.31 4.98 0.52 0.37

QPSK_5_64 QPSK_64 4.61 4.58 0.67 1.08

QPSK_5_78 QPSK_78 7.88 3.08 1.08 3.84

16QAM_5_46 16QAM_46 9.52 0.00 100.00 100.00

16QAM_5_50 16QAM_50 9.96 0.00 100.00 100.00

16QAM_5_57 16QAM_57 10.92 0.00 100.00 100.00

16QAM_5_64 16QAM_64 11.72 0.00 100.00 100.00

16QAM_5_71 16QAM_71 12.59 0.00 100.00 100.00

16QAM_5_74 16QAM_74 13.05 0.00 100.00 100.00

Coding Rate

• 16QAM Eb/No difficultto achieve with loworthogonality

• Requirement to havehigher orthogonalityclose to serving cell

HSUPA Radio Network Planning Process



• Existing radio network planning process can be applied to HSUPA

• Focus continues to be:

– Coverage

– Dominance (inter-cell interference)

– Size of best server areas

• Link b d e s sho ld be com le ed for HSUPA

HSUPA Radio Network Planning Process


• Macrocell deployment strategy likely to continue to be based uponR99 link budget analysis

• Indoor solutions and specific traffic hotspots may be plannedbased upon HSDPA and HSUPA link budgets

• Dimensioning tools can be used to generate an expectation ofHSUPA throughput

Content



Content

• Site selection


•


– Downlink capacity – Uplink capacity


Capacity planning



Capacity planning

• Capacity planning is based on – Number of coverage sites – Needed features – Possible micro, indoor and hotspot site implementation

• Capacity planning is commonly trade off: – Increased capacity with macro layer means lower cell ranges – Increased coverage within macro layer means lower capacity


• HSDPA implementation brings some new challenges – When using shared carrier with HSPA, capacity is shared between R99 and HSPAservices

– In order to guarantee high HSPA service availability then dedicated HSPA carriershould be used. Thus Capacity in the downlink is allocated for HSDPA

– In uplink the capacity needs to be shared between R99 UL DCH and HSUPA also

with dedicated carrier

• Capacity planning follows dimensioning results, but in detailed capacity planningthe sites can and might be needed to estimate per site method – This means that one site at the time is evaluated from the point of capacity

Coverage versus Capacity




Coverage and capacity are noticed together

• Higher capacity tolerance means lower cell range

• Higher cell range means lower capacity

?


Load

?

Capacity limitationCoverage limitation

Capacity and coverage planning



Capacity and coverage planning1. Coverage and interference estimation, which

notices possible limiting services

• R99 UL service(s)• HSDPA with selected cell edge throughput• HSUPA with selected cell edge throughput• Initially with max. load

Planning threshold can be utilised to illustratedifferent service availability and coverage Number of sites for coverage

2. Cell loading and throughput estimation withinca acit evaluation

Coverage and interference estimation

Cell loading and capacityestimation

Add

Output numberof Node Bs

Decrease max Decrease cell



CoverageLimited

• Cell load Initial load• DL power Max. power• HSPA throughput Minimum throughput Feature selection for HSPA

3. Coverage and capacity comparison

• Service availability• Coverage availability• Capacity availability Not sufficient coverage (coverage limited),

decrease loading or add new sites Not enough capacity (capacity limited), add carrier

or lower cell range/new sites

arr er

Comparison of number ofcoverage sites vs. capacity

requirement

Coverage and capacity matchingTotal number of sites

system load/new sites

Acceptable

CapacityLimited

ra us new s tes

Configuration planning





Coverage limited scenario• Scenario is based on wrong estimation of either capacity or too less number of sites

– Decreasing system loading can be utilised to accommodate less users in one cell

– Adding more sites to overcome coverage limitation

• Lower increase in generated interference floor greater cell range more users in eachcell greater actual system loading.

Capacity limited scenario

• Capacity demand is higher than what can be provided by an initial number of Node Bs,


– Maximum power or loading is exceeded, no services available – HSPA throughput (UL or DL) is lower than minimum throughput

• Cell capacity must be increased or the cell size decreased, or by adding additional carriers

• Reduced cell range fewer users loading the cell – Cell range decreasing commonly impacts on number of sites

• Note: Capacity can also be increased with features

Coverage and Capacity planning are iteratively madetogether with Site selection and Configuration planning

UMTS Network Configuration for HSDPA Support



Capacity planning setup and simulation

UMTS Network Configuration for HSDPA Support

• Capacity planning can be done also with NetAct Planner – Much more complex and time consuming

• Next the setup for capacity planning in NetAct Planner

Coverage planning and optimisation


• HSDPA/HSUPA bearers

• HSDPA coding rates

• Bit rates

• Eb/No target

• HSUPA Power control and

Soft handover parameters

Define HSPA services

• Packet services

• HSDPA support

• HSUPA SHO

• QoS parameters

Create HSPA terminals

• Set terminal parameters• UMTS support

• HSDPA support

• HSUPA support

• Associate bearers with services and them with terminal types

• Spread the terminals

Create UMTS cells and

set HSPA parameters• Assign carrier

• Set cell parameters

• Set power parameters forHSDPA

• Set Noise rise for HSUPA

Run static analysis or Monte Carlo simulator

View array outputs and reports

Validate capacity planning

HSUPA simulation output



HSUPA simulation output


• Results can show an estimation of

available cell throughput or forexample Service availability

Downlink Capacity



• Downlink is shared among R99 services and HSDPA traffic and control as well aswith common control and associated channels

• Similarly other main issues which impacts downlink capacity are:

▪ Cell max power, can be set and controlled with parameters

▪ Power for CCCH, can be tuned also▪ Orthogonality

▪ HS-SCCH power,this is art of the HSDPA total ower

p y

High orthogonality , lowinterferencee.g. micro, clear dominance

Macro cell closer celledge, lower quality


– HSDPA feature selection:

▪ Scheduler type: shared or cell specific

▪ Round robin or proportional fair

▪ Number of codes HS-DPSCH

Uplink Capacity



p p y

• Uplink is shared between R99 and HSUPA, thus capacity is impacted by eachother

• Main issues impacting to uplink capacity are

– Little I

– Power rise

– Eb/Nos

– Available noise rise, can be set in parameters

– Configuration and number of carriers


Issues Affecting Capacity



g p y

• Mixture of services makes capacity planning more complex

– Real Time Voice and Data services in Erlang

– Non-Real Time Data services in kbps

• Load calculation is required especially in UL to determine the ULinterference (Noise Rise)

• Different Services have different Eb/No re uirements


• Traffic is asymmetric between DL and UL• Different kinds of interferences have to be taken into account

(orthogonality factor α, little i, etc.)

• Different Node B maximum Tx power should be considered

• Speed of the Users differs

Values used in the following examples



g p64/128/384 kbps Data

BTS TX power 43 dBm

MS TX power 21 dBm

E c /I o -16.5 dB

BTS E b /N o 2/1.5/1

MS E b /N o 6/5.5/5


Other to own cell

interference ratio i

0.6

Orthogonality 0.6

Channel profile ITU Vehicular

A, 3 km/h

MS speed 3 km/h

MS/BTS NF 8 dB / 4 dB

Antenna gain 16 dBi

Throughput for Different Services



160

165

170

i o n l o s s ( d B )

Macro cell, P(DL) = 43 dBm, P(UL) = 21 dBm

3 km/h 64.0 kbps3 km/h 128.0 kbps

3 km/h 384.0 kbps

64/128/384 kbps Data


0 100 200 300 400 500 600 700 800 900 1000140

145

150

155

DL throughput in kbps

M a x i m u m p

r o p a g a

Max capacity

Effect of little i



160

165

170

l o s s ( d B )

128 kbps

i = 0.2i = 0.4

i = 0.6

i = 0.8

• Doubling of the "little i" will cause 70 % throughput decrease of theoriginal value

• In the real environment we willnever have separated cell.Therefore in the load factorcalculation the other cellinterferences should be taken


0 500 1000 1500140

145

150

155

DL throughput in kbps

M a x

i m u m p

r o p a g a

t i o

.

• This can be introduced bymeans of the little i value,which describes how much twocells overlap (biggeroverlapping more inter-cell

interferences)• LSERV: Pathloss to serving

cell, Ln : pathloss to neigbourn, M overlapping cells



Module Contents



• Site selection

•Coverage and interference planning



• Coverage and capacity improvement – Coverage vs. capacity

– Coverage Improvements Alternatives

– Capacity Improvements Alternatives

– Antenna tilting, design and improvement




How to improve the

How to improve the coverage? Uplink

?



Load

?

Module Contents



• Coverage vs. capacity

• Coverage Improvements Alternatives

• Capacity Improvements Alternatives



• Antenna tilting, design and improvement

Module Contents



• Site selection





• Coverage and capacity improvement – Coverage vs. capacity

– Coverage Improvements Alternatives

– Capacity Improvements Alternatives

– Antenna tilting, design and improvement



Impact of sensitivity (MHA)



The use of MHAs brings• UL coverage gain (important for early phase of a network)

• capacity gain for low-loaded networks (keeping the cell size constant)

DL Path loss155

160

s



NRT Data 384k UL Path loss

NRT Data 384k UL Path loss, 1dB improvementNRT Data 384k UL Path loss, 2dB improvement

145

150

0 5 10 15 20 25 30 35 40 45

UL Load

P a t h

l o

Extended cell feature



• Extended cell feature reserves higher amount of BTS base bandprocessing resources for RACH processing

• Default 20 km cell range can be extended in 20 km steps to 60 km



– Coastal regions – Mountain regions



Capacity Improvement Alternatives



• 6 sectored site

– ~ 60-80% capacity gain compared to 3sectors (not 100% due to inter-sectorinterference)

• More carriers (frequencies) persector



– power splitting gives roughly 60% morecapacity

– downlink can be dedicated for HSDPA

• Advanced scheduling and receiver

structures – better resource usage

– improved orthogonality

6 sectored site



• More sectors increase the capacity of the WCDMA network

• Sectorisation gain in capacity is more efficient than in GSM whereit is limited by the number of frequencies available and frequency

planning (WCDMA freq reuse=1)• Going from 3 to 6 sectors, the capacity gain is not 100% due to the

increased interference.



• To achieve a higher capacity gain, it is crucial to control the amountof interference and the soft handover overhead. If the overlappingis to big, to much interference and a higher soft handover overhead

occurs.

Capacity Upgrade with carrier addition



• No changes to antennas or antenna cables

• No HW changes in Flexi BTS

300

350

r s i t e

take 2nd frequency

Cost/Erlang isdecreasing withca acit u rade



0

50

100

150

200

250

S

p e e c h E r l a n g p

20W 2x10W + 2x10W

DL power per sector

into use



Advanced scheduling and receiver structures



• Proportional fair scheduling in HSDPA improves cell throughput byallocating more resources to users when in good RF conditions

• Equaliser in receiver cancels own cell interference

• Dual antenna diversity improves fading conditions

+100 %



+20 %

+60 %



Effect of tilting on coverage and capacity



• Tilting can be used to improve both coverage and capacity – Coverage improvement due to higher signal level on the cell dominance area

– Capacity improvement due to decreased level of interference outside celldominance area Lower little i

• Antenna tilting means adjustment of antenna radiation pattern invertical direction on the plane of main beam



• Antenna radiation pattern can be tilted by mechanical installation

change or by adjustment of electrical phasing of the antennaelements

Effect of tilting on the signal level



RECEIVED SIGNAL LEVEL

-70.00

-60.00

-50.00

-40.00

l e v e l

RX level

RX level ant

RX level ant tilt

Coverage threshold out

Coverage thres hold in



-100.00

-90.00

-80.00

0 . 1 0

0 . 1 2

0 . 1 5

0 . 1 8

0 . 2 2

0 . 2 7

0 . 3 2

0 . 3 9

0 . 4 8

0 . 5 8

0 . 7 0

0 . 8 6

1 . 0 4

1 . 2 6

1 . 5 4

1 . 8 7

2 . 2 7

2 . 7 6

3 . 3 5

4 . 0 8

4 . 9 6

6 . 0 2

Distance

R X



Pilot level without and with tilt



8 electricalWithout tilt





Tilting angle from geometry



Example tilt angle

• 6 degree vertical beamwidth

• Cell range 200 m 600 m

14

16

.


Customer confidential15 20 25 30 35 40

4

6

8

10

12

ν geo h 200, 6,( )

ν geo h 300, 6,( )

ν geo h 400, 6,( )

ν geo h 600, 6,( )

h

Antenna tilting Optimisation – Example



• WCDMA 1900 Network

• Identified places for optimisation

– Urban area: high other-cell interference

– Rural area: a few sites collecting a lot of interference

• Optimisation approaches

– Antenna down tiltin



– Antenna lowering



Antenna tilting Optimisation – ExampleUrban Area



• 16 sites, 48 cells

• All 3-sector sites

• similar height

• Area 10 km x 12 km

• On average 7 km2 per site



• erra n: at w t out waters

07_RN31548EN10GLA0_Coverage and Capacity Planning

Documents

Transcript of 07_RN31548EN10GLA0_Coverage and Capacity Planning