06%2E UMTS RF Planning Process

7/29/2019 06%2E UMTS RF Planning Process

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NORTEL NETWORKS CONFIDENTIAL Version 3.1

UMTS RF Planning Process


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Presentation Name - 1NORTEL NETWORKS CONFIDENTIAL

Content

1. RF Planning Process2. Designing for Performance


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Radio NetworkPlaning

Capacity

Analysis

Optimized Solution

Coverage

Analysis

Quality

Analysis

Site database

Traffic and Carrier count

RF Planning Global Process


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Terrain Database Clutter Database - EIRP

- Antenna- Frequency

- Sectors

- Height etc.

Received power at each bin

Design Threshold

- Based on maximum allowable path loss for the most restrictingservice (Link Budget)

- The required mobile received signal is calculated based on BS EIRP

and on Maximum Path Loss.

Design threshold = BS EIRP-Maximum Path Loss

LINK BUDGET

Propagation Model

Coverage analysis


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RF Planning - Coverage Design

Good CDMA RF PlanningEven site spacing, low

antenna variance to

ensure server dominance

Careful site and antennaselection to cover high

traffic area


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RF Planning - Traffic distribution

Uniform Traffic

Non-Uniform Traffic

Pilot Ec/Io is an important plot.

It shows the best server pilot

signal-to-interference ratio.

Ec/Io is used extensively in call

origination and handoff process.

Non-uniform traffic makes it more

difficult to do RF planning.

Careful site and antennaselection is extremely important.


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sites

Location &configuration

Propagation Model

Terrain Data Base

Monte-Carlo

Simulat ionsStatistics

dropped calls

hand-offs

UL noise rise

Cell loading

MapsPilot Ec/Io

UL Required MS EIRP

Soft HO

RF Planning WCDMA Analysis

PA

Tx/Rx link losses

Noise figure

Eb/NoProcessing Gain

...

Node B

PA

Noise figure

Eb/No

Processing

Gain

...

UE

Service

Cable loss

Antenna pattern

sites configuration

sites constra ints(reuse of exist in g

sites)

Site

Traffic Assumptions Link Budget


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Down l ink best

server

Pi lotEc/Io Required Upl ink Mob i le EIRP

Hand-off

statusLoad

RF Planning WCDMA Analysis : Results


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RF Planning - Pilot Best Server Plot

Pilot best server plot shows

which sector provides the

best Ec/Io to an area.

We want to confine the

coverage of a sector tonearby area as much as

possible.


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RF Planning - Pilot Ec/Io Plot

Pilot Ec/Io is the mostimportant plot. It shows the best server pilot

signal-to-interference ratio.

Ec/Io is used extensivelyin call origination andhandoff process. Based on Nortel experience,

Ec/Io -12 dB provides goodquality networks.

Areas to Improve


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Add Site

Downtilt

RF Planning - Pilot Ec/Io Plot Optimisation (2nd Pass)

Still want to Improve

Pilot Ec/Io has

been improved


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RF Planning - Pilot Ec/Io Plot Optimisation (2nd Pass)

We will add site 169 to servethe Memorial Hall area and

downtilt the surrounding

sectors to reduce interference.


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RF Planning - Pilot Ec/Io Plot Optimisation (3rd Pass)

Pilot Ec/Ioproblem is gone!


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RF Planning - Handoff Plot

Excessive handoff

area due to lack of

dominant server


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RF Planning - Handoff Optimization

Add Site : Excessive

handoff reduced.


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RF Planning - Required Mobile EiRP Plot

Required mobile EiRP plot shows the

mobile transmit power required to

acquire the uplink.

The mobile transmit power needed

= max. mobile power - fade margin

- bldg. penetration loss + SHO gain


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Design Target : Cell

Loading


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Operator did not want any

site with Cell Loading >60%

Add carrier

Add sites

RF Planning - Cell LoadingOptimisation


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General statistics (number of total users, dropped users)

Results per site (UL / DL carried throughput)

Results per transmitter (power, load, reuse factor)

Results per mobile (connection status, handoff, power)

Statistical analysis

RF Planning Statistics


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RF Planning - RF Design Optimisation Summary

Analysis of the prediction and simulations results UL/DL coverage quality

Based on design threshold

Ec/I0 for DL coverage

Mobile ERIP for UL coverage

QOS

UL/DL load factor per cell (


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Continuous process

RF Design Optimisation After Site Build

RF design optimisation for coverage When the sites are placed, it is necessary to verify that the both

UL&DL quality of coverage are reached for each service.

The coverage optimisation is performed on

Site position

Antenna tilt and azimuth

Adding new sites if necessary

RF design optimisation for capacity Multi-Carriers solution

Adding new sites


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Content

1. RF Planning Process

2. Designing for Performance


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RR

B B

H H

D = 2R > 2B

It doesnt seem too Difficult ?

WCDMA RF Engineering Experience

A Clean Textbook RF Design for Coverage Define Uplink Budget from QOS Margins

Space Cells for Target Edge Signal Strength.

Adjust heights to contain Interference

Use Buildings as Interference Shields

Unlimited Bldg Penetration & QOS ???


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Mobile TX Pwr vs Log D

-40

-30

-20

-10

0

10

20

-1 -0.5 0 0.5 1

log(d)

dBm

Slope ?

Nortel have been Deploying CDMA in

Real Environments for 8 years

WCDMA RF Engineering Experience

Real World CDMA Cells Fragment at Closer Spacings and

present many conflicting challenges. Path loss Slopes Flatter ,More Patches of Overshoot

Site Grid breaks up

Handoff Problems Increase

Longer Neighbor Lists

Longer Code Search times

Spectral Efficiency Loss


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Cell Border Placement

CDMA-based system isinterference-limited.Avoiding pilot pollution isthe key. Maximizing the signal level inside

the cell

Minimize the signal overshoot tothe neighbor cells

Good CDMA design takesadvantage of the two-slopepropagation model bydesigning cell border beyond

break point. Signal within the cell has a

slower path loss slope, butthe out-of-cell interferencehas a faster path loss slope

H

B=4Hh/l

R-s1

R-s2

Break Point

RR

B B

H H

D = 2R > 2B

RRB

BH H

D = 2R < 2B

Two-slope propagation model

Good design

Poor design


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Antenna Height Variance and Pilot Pollution

Ideally only first tier cell (6 cells) will interfere the cell under

study

Cell separation too close or high antenna height variance

will cause second tier (12 cells) or even third tier cells (36

cells) to interfere No dominant server issue can be addressed by reducing

excessive soft HO area


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Tri-cellular arrangement

Site placement andantenna orientationhas significant impacton server dominance.

Effective technique -antenna main-lobes of

one site are directed atthe antenna nulls of theadjacent sites

OMNI antennas areusually not desirable

OTSR is a good lowcost substitute

a3

b3g3a1

b1g1a2

b2g2

a1

b1g1

a2

b2g2

a3

b3g3b4 g5

a6

Dominant servers everywhere

Many areas with no dominant server


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Inter-System Border Placement

UMTS-to-GSM handover is more critical

GSM-to-UMTS handover is not critical

Mobile performs cell reselection and selects the

CDMA system shortly after entering dual mode

service area

Experience shows performance of inter-system

borders is highest when: Traffic moves normal (perpendicular) to the border

Traffic flow across the border is relatively low


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WCDMA KPIs

Not Considered WCDMA KPIs Common pilot Ec/I0. Note that Ec/I0

is neither linearly related to performancenor directly visible to users.

Handover drop rate. Note that

handover is an eventin FDMA systems,whereas it is a state in CDMA systems.

Cell throughputbecause there is aboundless number of variables thatinfluences cell throughput including enduser application and cost- & marketing-

based decisions by the UMTS networkoperator.

Significant WCDMA KPIs

Call drop rate, call setup

failure rate

Call setup time

Single-userbit rate Objective voice mean

opinion score (MOS)

Documents

06%2E UMTS RF Planning Process