GSM Radio Planning and Optimization

7/30/2019 GSM Radio Planning and Optimization

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MN 1790MN 1790

TECHCOM Consulting GmbH

www.techcom.de


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Contents: IntroductionContents: Introduction

GSM and SBS fundamental aspects concerning Radio

Network Planning

Planning Objectives & Principle Planning Steps

Specifics influencing Radio Network Planning

Site Survey & Site Investigation

Antenna Types

Antenna Parameters

Antenna Patterns

Antenna Tilt (Mechanical and/or Electrical)

(Effective) Antenna Height

Antenna Diversity

Antenna Cables

Antenna cables and Intermodulation

Antenna Near Products

Exercises


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Contents: Coverage PlanningContents: Coverage Planning

Definition of Terms

Characteristics of Radio Wave Propagation

Radio Wave Propagation Models

Suitable prediction models for Macro-, Micro- and Pico-cells

Location Probability

Link Budgets

Fading

Fast Fading

Rice Fading

Rayleigh Fading

Slow Fading

Jake's Formula

Interference Margin

Noise Figure calculations

Amplifier Noise

Path Loss Balance

Cell Coverage Calculation

Basics about Digital Map Data

Principles of Planning Tools and their usage

Measurement Tools supporting Cell Planning

Cell Types


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Contents: Coverage PlanningContents: Coverage Planning

Omni versus Sector Cells

Exercises


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Contents: Capacity PlanningContents: Capacity Planning

Fundamentals of Traffic Theory

Definitions and Terms

Erlang-B Formula

Erlang-B Look-up Table

Erlang-C Formula

Trunking Gain

Traffic Distribution

Traffic Forecasting

Traffic Measurements

Dimensioning TRXs

Dimensioning Control Channels

Dimensioning Control and Traffic Channels

Capacity and Cell Radius

Dimensioning terrestrial interfaces

Exercises


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Contents: Frequency PlanningContents: Frequency Planning

Interference

Frequency Reuse and Reuse Patterns

Cluster

Cluster: Exercise

Spectrum Efficiency

Optimization of Spectrum Efficiency

Interference Reduction

Frequency Hopping

Power Control

VAD/DTX

Interference Matrix

Frequency Allocation Strategies

Tool supported Frequency Allocation

Interference Analysis


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Contents:

Increase of Network Coverage

Contents:

Increase of Network Coverage

Repeaters and repeater implementation

Repeater Types

Repeater Characteristics

Advantages and disadvantages

Problems: Decoupling

Problems: Time Delay

Influences of repeaters on BTS-capacity

Influence of repeaters on neighbor cell relationships

Influence of repeaters on interference situation

Repeater and Link Budget

Handling of repeaters in planning tools

O&M Systems for repeaters

Further methods and techniques to increase coverage

Exercises


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Contents:

Increase of Network Capacity

Contents:

Increase of Network Capacity

General Remarks

Spectrum Increase

Addition of TRXs

Cell Sectorization

Cell Splitting

Decrease of frequency re-use distance

Implementation of Half Rate

Adaptive Multi Rate

Micro Cell implementation

Hierarchical Cell Structure planning

Multiple Band Operation

Multiple Mode Operation

Handover Boundaries

Cell load dependent handover boundaries


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Contents:

Radio Network Optimization

Contents:

Radio Network Optimization

Reasons for the Need of Optimization

Performance Data Measurements

Drive Tests

Optimization Strategies

Optimization of Physical Parameters

Optimization of Database Parameters

Example Drive Tests

Example Drive Tests: Exercises


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Introduction: ContentsIntroduction: Contents

GSM and SBS fundamental aspects concerning Radio Network Planning

Planning Objectives & Principle Planning Steps

Specifics influencing Radio Network Planning

Site Survey & Site Investigation

Antenna Types

Antenna Parameters

Antenna Patterns

Antenna Tilt (Mechanical and/or Electrical)

(Effective) Antenna Height

Antenna Diversity

Antenna Cables Antenna cables and Intermodulation

Antenna Near Products

Exercises


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GSM and SBS fundamental aspects concerning RadioNetwork Planning

GSM and SBS fundamental aspects concerning RadioNetwork Planning

Implementation of additional hardware to improve QOS

Extension of coverage area

Implementation of new technologies (e.g. HSCSD, GPRS, EDGE)

Network extension

Fine tuning of the existing network without addition of new hardware

Reduction of interference on Air interface

Network optimization

Connecting the links between the different network elementsNetwork integration

Download and activation of network element specific software and databasesCommissioning of the network elements

BTS, BSC, TRAU, MSCInstallation of the network elements

Number and location of BTSs, BSCs, and MSCs

Number and type of links between the network elements

Type of BTSs and antennas (sectorised, omni-directional)

Number of TRXs per cell

Frequencies of serving and neighbor cells

BSICs

LACs

(GSM) Network planning (design)

RemarksSteps


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Cellular network

partial overlap of cells

only a few frequencies per cell

frequency re-use distance

1

1

2

2

4

4

5

5

6

67

7

3

3

GSM and SBS fundamental aspects concerning RadioNetwork Planning: Cellular Concept

GSM and SBS fundamental aspects concerning RadioNetwork Planning: Cellular Concept


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GSM and SBS fundamental aspects concerning RadioNetwork Planning: TDMA Concept

GSM and SBS fundamental aspects concerning RadioNetwork Planning: TDMA Concept

TDMA frame: 4.615 ms

Time

Time Slot

0.577 msTDMA frame No. 0180 TDMA frame No. 0181

1 2 3 4 5 6 7 1 2 3 4 5 6 70 0


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GSM and SBS fundamental aspects concerning Radionetwork Planning: FDMA Concept

GSM and SBS fundamental aspects concerning Radionetwork Planning: FDMA Concept

UPLINK

25 MHz

75 MHz

890 MHz

1710 MHz

915 MHz

1785 MHz

DOWNLINK

935 MHz

1805 MHz

960 MHz

1880 MHz

25 MHz

75 MHz

GSM900

GSM1800

1 2

200 kHz

124374

guard band

1 2124374


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GSM and SBS fundamental aspects concerning RadioNetwork Planning: Cell Types

GSM and SBS fundamental aspects concerning RadioNetwork Planning: Cell Types

360

omni directional cell

180

180 sector cell

120

120 sector cell


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GSM and SBS fundamental aspects concerningRadio Network Planning: Cell Types


8 km

35 km

100 km

GSM 900 Extended Cell

Standard Cell: GSM 900

Standard Cell: GSM 1800


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Concentric cell

Inner area: TRX with low power for

capacity

Complete area: TRX with high

power for coverage

Hierarchical cells

Different layers of cells for

different coverage areas


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GSM and SBS fundamental aspects concerning RadioNetwork Planning: Logical Channels

GSM and SBS fundamental aspects concerning RadioNetwork Planning: Logical Channels

logical channels

control channels traffic channels

BCH CCCH DCCH

FCCH

BCCHSCH

AGCHPCH FACCH

SACCHSDCCH

TCH/F

RACHTCH/H


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GSM and SBS fundamental aspects concerning RadioNetwork Planning: BCCH Multiframe

GSM and SBS fundamental aspects concerning RadioNetwork Planning: BCCH Multiframe

F S F S F S F S F S IB C C C D0 D1 D2 D3 A0 A1

F S F S FS F S F S IB C C C D0 D1 D2 D3 A2 A3

RR RRRRRRRRRRRRRRRRRRRRRRR RRD3 A2 A3 D0 D1 D2

RR RRRRRRRRRRRRRRRRRRRRRRR RRD3 A0 A1 D0 D1 D2

F - FCCH - Frequency Correction Ch.

S - SCH - Synchronization Channel

B - BCCH - Broadcast Control Channel

C - CCCH - Common Control Channel

D - SDCCH - Stand alone Dedicated Control Ch.

A - SACCH - Slow Associated Control Ch.

R - RACH - Random Access Channel

I - idle

uplink

downlink

51 TDMA multiframe


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GSM and SBS fundamental aspects concerning RadioNetwork Planning: SDCCH Multiframe

GSM and SBS fundamental aspects concerning RadioNetwork Planning: SDCCH Multiframe

B0..B7 SDCCH subslots

A0..A7 SACCH subslots

51 TDMA multiframe

downlink

B0 B1 B2 B3 B4 B5 B6 B7

B0 B1 B2 B3 B4 B5 B6 B7

A0 A1 A2 A3

A4 A5 A6 A7

uplink

B0 B1 B2 B3 B4 B5 B6 B7

B0 B1 B2 B3 B4 B5 B6 B7

A0

A1 A2 A3

A5 A6 A7

A4


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GSM and SBS fundamental aspects concerning RadioNetwork Planning: TCH Multiframe

GSM and SBS fundamental aspects concerning RadioNetwork Planning: TCH Multiframe

T T T T T T T T T T T T A T T T T T T T T T T T T -

T t T t T t T t T t T t A t T t T t T t T t T t T a

26 TDMA frame = 120 ms

uplink / downlink: Traffic Channel (TCH/F)

uplink / downlink: Traffic Channel (TCH/H)

T - TCH - Traffic Channel

t - TCH - Traffic Channel

A - SACCH - Slow Associated Control Channel

a - SACCH - Slow Associated Control Channel


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dummy burst

training sequence

26

encrypted bits

57

S

1

TB

3

encrypted bits

57

S

1

TB

3

fixed bit pattern

142

TB

3

TB

3

GP

8.25

GP

8.25

normal burst

frequency correction burst

fixed bits always 0TB

3

TB

3

GP

8.25

synchronization burst

training sequence

64

information

39

TB

3

information

39

TB

3

GP

8.25

access burst

training sequence41

TB8

information36

TB3

GP68.25

GSM and SBS fundamental aspects concerning RadioNetwork Planning: Burst Types

GSM and SBS fundamental aspects concerning RadioNetwork Planning: Burst Types


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GSM and SBS fundamental aspects concerning RadioNetwork Planning: RXQUAL

GSM and SBS fundamental aspects concerning RadioNetwork Planning: RXQUAL

Assumed value 18.1%12.8 % < BERRXQUAL = 7

Assumed value 9.05%6.4 % < BER < 12.8 %RXQUAL = 6

Assumed value 4.53%3.2 % < BER < 6.4%RXQUAL = 5




Assumed value 0.28%0.2 % < BER < 0.4 %RXQUAL = 1

Assumed value 0.14%BER < 0.2 %RXQUAL = 0

RXQUAL (Received signal quality, see GSM 05.08)


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GSM and SBS fundamental aspects concerning RadioNetwork Planning: RXLEV

GSM and SBS fundamental aspects concerning RadioNetwork Planning: RXLEV

RXLEV (Received signal level, see GSM 05.08)

greater than 48 dBmRXLEV = 63

49 dBm to 48 dBmRXLEV = 62

......



Less than 110 dBmRXLEV = 0


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GSM and SBS fundamental aspects concerning RadioNetwork Planning: SQI

GSM and SBS fundamental aspects concerning RadioNetwork Planning: SQI

SQI (Speech quality index, Ericsson defined (and patented) parameter, see Pat. No. WO-9853630)

Value ranges:

-20 dBQ to 30 dBQ for Enhanced Full Rate (EFR) speech coders

-20 dBQ to 21 dBQ for Full Rate (FR) speech coders

badSQI 0

good1 SQI 19

Very good for FR / EFR20 SQI 21 / 30

Perceived speech qualitySQI values


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GSM and SBS fundamental aspects concerning RadioNetwork Planning: BSIC / LAI

GSM and SBS fundamental aspects concerning RadioNetwork Planning: BSIC / LAI

BSIC (Base Station Identity Code, see GSM 03.03 and GSM 05.08)

BSIC = NCC BCC

NCC = Network colour code (range: 0 7)

BCC = Base station colour code (range: 0 7)

LAI (Location are Identification, see GSM 03.03)

LAI = MCC MNC LAC

MCC = Mobile country code

MNC = Mobile network codeLAC = Location area code (range: 0-65535)


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GSM and SBS fundamental aspects concerning RadioNetwork Planning: ARFCN

GSM and SBS fundamental aspects concerning RadioNetwork Planning: ARFCN

RFC (Radio frequency carrier, see GSM 05.01 and GSM 05.05)

The carrier frequency is related to the absolute radio frequency channel number (ARFCN) as given inthe following table:

1805-1880 MHz

F(DL) = F(UL) + 95512 n 885

1710 1785 MHz

F(UL) = 1710.2 + 0.2 x(n-512)

DCS 1800 band

925 - 960 MHz

F(DL) = F(UL) + 450 n 124975 n 1023

880 915 MHz

F(UL) = 890 + 0.2 x nF(UL) = 890 + 0.2 x (n-1024)

Extended GSM

900 band(E-GSM band)

935 960 MHz

F(DL) = F(UL) + 451 n 124

890 915 MHz

F(UL) = 890 + 0.2 x n

Primary GSM

900 band

(P-GSM band)

DL-frequenciesARFCN value

range

UL-frequenciesFrequency band


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438 = n = 511Fl(n) = 747.2 +0.2*(n-438)

30777 - 792747 - 762GSM 750

921 - 925

488.8 496

460.4 467.6

869 894

1930-1990

1 805 - 1 880

925 935

935 - 960

Downlink freq.

(MHz)

45

10

10

45

80

95

45

45

Duplex dis-tance (MHz)

Fl(n) = 890 +0.2*(n-1024)

Fl(n) = 479 +0.2*(n-306)

Fl(n) = 450.6 +0.2*(n-259)

Fl(n) = 824.2 +0.2*(n-128)

FI(n) = 1850.2 +0.2*(n-512)

1710.2 +

0.2*(n-512)

Fl(n) = 890 +0.2*(n-1024)

Fl(n) = 890 +0.2*n

259 = n = 293450.4 457.6GSM 450

955 = n = 973876 - 880Railway GSM

306 = n = 340478.8 486GSM 480

128 = n = 251824 849GSM 850

512 = n = 8101850-1910GSM 1900

512 = n = 8851 710 - 1785GSM 1800

975 = n = 1023880 890GSM 900Extended band

1 = n = 124890 915GSM 900Primary band

Numbering of ARFC (Uplink freq.)Uplink freq.

(MHz)

Frequency band

GSM and SBS fundamental aspects concerning RadioNetwork Planning: Frequency Bands

GSM and SBS fundamental aspects concerning RadioNetwork Planning: Frequency Bands


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GSM and SBS fundamental aspects concerning RadioNetwork Planning: BA

GSM and SBS fundamental aspects concerning RadioNetwork Planning: BA

Neighbour cell list (BA, BCCH Allocation, see GSM 04.08 and GSM 05.08)

The BA is a list of ARFCN which are used in the neighbour cells.

GSM distinguishes the BA (BCCH) and the BA (SACCH).

The carriers to be monitored by the MS in idle mode (for cell reselection) are given by the BA

(BCCH).

The carriers to be monitored by the MS while being in connected mode (TCH or SDCCH) are given

by the BA (SACCH).

The parameter BA-IND discriminates between measurement results related to different BA (BA

(BCCH) and BA (SACCH)).

The parameter BA-USED shows the value of the BA-IND used for BCCH allocation.


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BTSone BS20, BS21, BS22, BS60, BS61

BTSplus BS40, BS41, BS240, BS241

Special types BS82 E-Micro-BTS

BS242 Pico-BTS

Naming convention:

last digit: 0 = indoor1 = outdoor

2 = special purpose

first digit(s) number of TRX supported

GSM and SBS fundamental aspects concerning RadioNetwork Planning:

SIEMENS BASE STATION Types

GSM and SBS fundamental aspects concerning RadioNetwork Planning:

SIEMENS BASE STATION Types


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BS-60 BS-61

BS-20 BS-21 BS-22

GSM and SBS fundamental aspects concerning RadioNetwork Planning: BTSone

GSM and SBS fundamental aspects concerning RadioNetwork Planning: BTSone


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BS241BS240BS40 BS41

GSM and SBS fundamental aspects concerning RadioNetwork Planning: BTSplus



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BS240 XL

More carriers per rack than normal BS240




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BS82

E-Micro-BTS

4 carriers per cabinet in Dual carrier units

Built-in antenna or external antenna

GSM and SBS fundamental aspects concerning RadioNetwork Planning: Special BTS Types



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Server rack

BS242 Pico-BTS

Up to 24 carrier agents at remote locations

Carrier Agent




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BS240 XS

Up to 6 carriers with small rack

and BTSplus Hardware

GSM and SBS fundamental aspects concerning RadioNetwork Planning: BS240 XS

GSM and SBS fundamental aspects concerning RadioNetwork Planning: BS240 XS


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Base

station

controller

BSC

Transcoding

and Rate

Adaptation

Unit

TRAU

GSM and SBS fundamental aspects concerning RadioNetwork Planning: BSC and TRAU

GSM and SBS fundamental aspects concerning RadioNetwork Planning: BSC and TRAU


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3500

3200

1536

> 240

72

32

200

250

500

BR6.0

4000

3200

2880

> 240

120

36

200

400

900

BR7.0

200020001000Switch.

Cap. (Erl)

320032001000Process.

Cap. (Erl)

128n. a.n. a.GPRS TS

48-112112112LAPD

464636PCMx

202012TRAU

10010060BTSE

150150120Cells

250250120TRX

BR5.5BR5.0BR4.0Capacity

GSM and SBS fundamental aspects concerning RadioNetwork Planning: Capacity Numbers

GSM and SBS fundamental aspects concerning RadioNetwork Planning: Capacity Numbers


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Planning Objectives & Principle Planning StepsPlanning Objectives & Principle Planning Steps

General planning objectives:

To realize service(s) with

maximum coverage

maximum capacity

maximum Quality of Service (QoS)

minimal interference

at minimum costs


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Principle planning steps

1) Basic planning data acquisition (data about: expected traffic load and planned service area)

nominal cell plan

2) Terrain data acquisition & installation of a digital terrain database (including topographical and

morphological data) into a planning tool

3) Coarse coverage prediction and initial site determination for a first site selection process using

the digital terrain data and standard propagation models

4) Site survey and site selection

5) Survey measurements (to fine tune the propagation models)

6) Detailed network design (to determine final network structure: Number and configuration of

BTS, BSC, TRAU; needed antennas and transmission lines; frequency plan; future evolution

strategy)

7) Transmission planning


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Nominal Plan

Detailed Plan

Modification &

Optimization


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External factors influencing radio network planning:

Physics (propagation of electromagnetic waves, interaction of electromagnetic waves with

matter, ...)

Government restrictions (concerning coverage, blocking, maximum output power

levels, ...)

Topography

Statistics (population distributions, population development, )

...

Specifics influencing Radio Network PlanningSpecifics influencing Radio Network Planning


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Site Survey & Site InvestigationSite Survey & Site Investigation

Site survey and site investigation:

Selection of the sites to be used from alternative locations (if available)

Contract for site leasing exists?

Adaption of the cell plan to the real locations that are used (nominal positions must be replaced

by the real ones)

Antenna installation possible?

Antenna separation possible?

Predicted antenna height realistic?

First Fresnel Zone free of obstacles (for the nearest 50 to 100 meters)?

Enough place for the radio (BTS and microwave) equipment, the battery backups, ...?

Find out from where the primary power can be taken Find antenna cable path and measure required cable length

Find out how the transport network can be brought into the site

Sketch the earthing and lightning protection system

...


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Antenna PatternsAntenna Patterns

Antenna pattern:

The (real) distribution of the radiated power as function of the direction is usually displayed inhorizontal and/or vertical antenna radiation patterns. For these diagrams, usually polar

coordinates graduated in decibels (dB) are used. Since an antenna is a passive component, due

to the conservation of energy an increase of the radiated power in one direction will reduce the

radiated power in an other direction. For sector antennas, the main lobe in the front direction

should be maximised whereas the back lobe should be minimised.

The sector width (e.g. 120 sector) should not be confused with the half power beam width. For

example, often 60 65 half power beam width antennas are used to realise 120 sectors.


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Antenna PatternsAntenna Patterns

Antenna patterns display the distribution of radiated energy in the horizontal and vertical direction:

horizontal pattern vertical patternelectrical

down-tilted

antenna


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Antenna ParametersAntenna Parameters

Frequency range

Polarization Gain

Half-power beam width

Electrical tilt

Front to back ratio

Impedance

VSWR and return loss

Maximum power per input

Input connectors

Connector position

Dimensions (height, width, depth)

Weight

Wind load (frontal, lateral, rearward)

Maximum wind velocity


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Example values for a sector antenna:

200 km/hMaximum wind velocity

460 N, 300 N, 1020 N at 150 km/hWind load (frontal, lateral, rearward)

12 kgWeight

2574 / 258 / 103 mmDimensions (height, width, depth)RearsideConnector position

7/16 femaleInput connectors

500 W (at 50oC ambient temperature)Maximum power per input

< 1.3VSWR and return loss

50 OhmImpedance

> 23 dBFront to back ratio

6o electrical downtiltElectrical tilt

H-plane: 90o / E-plane: 6.5oHalf-power beam width

17dBiGain

VerticalPolarization

870 - 960 MHzFrequency range


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Half power beam width:

The opening angle between the points where the radiated power is 50 % (3 dB) lower than the

power transmitted in the main direction is called the half power beam width.

Antenna gain:

The gain of an antenna is given either in dBi (with respect to an ideal, isotropic antenna) or in dBd

(with respect to a dipole antenna):

Gain (dBi) = Gain (dBd) + 2.15 dB

Antenna tilt:

Two different tilt types can be distinguished: electrical tilt and mechanical tilt.

Mechanical tilt is achieved by corresponding mounting of the antennas using special mounting

devices.

Electrical tilt is a built-in function of an antenna. Either an antenna has or does not has this

function. Usually an electrical down-tilted antenna has just one (fixed) electrical (down)-tilt but

there also exist antennas where the electrical (down)-tilt is settable.

In addition to an electrical tilt also a mechanical tilt can be applied. The effective tilt is the sum of

both tilts.


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Voltage Standing Wave Ratio (VSWR):

The VSWR-ratio is a measure for the reflected output power. If the impedance of the antenna

does not match to the impedance of the feeder, the output power is reflected to the transmitter. Asa consequence the transmitter performance and the radiated power will be reduced. The closer

the VSWR-ratio is to 1, the lower the reflected output power.

Polarisation:

The polarisation plane is given by the electrical field vector. Usually antennas are vertically or

cross polarised.


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Antenna Tilt (Mechanical and/or Electrical)Antenna Tilt (Mechanical and/or Electrical)

Mechanical downtilt:

JAdvantages:

Downtilt adjustable, simple method (requires only some mounting hardware: downtilt kit)

L Disadvantages:

Downtilt angle varies for different azimuth directions

Horizontal half-power beam width increases with downtilt angle

Gain reduction depending on azimuth direction

Electrical downtilt:

JAdvantages:

Downtilt angle is constant for all azimuth directions

Horizontal half-power beam width does not increase with downtilt angle

L Disadvantages:

Downtilt angle is fixed


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Antenna Tilt (Mechanical and/or Electrical)Antenna Tilt (Mechanical and/or Electrical)

Adjustable electrical downtilt:

JAdvantages:

Downtilt adjustable

Downtilt angle is constant for all azimuth directions

Horizontal half-power beam width does not increase with downtilt angle

Optimum downtilt angle:

Must be calculated

Depends on the surrounding

Field strength reduction in the horizontal direction is maximum if minimum between main

and first upper side lobe is pointing towards horizon


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(Effective) Antenna Height(Effective) Antenna Height

Several methods to calculate effective antenna height:

Absolute calculation method:

Effective height = Base station antenna height above ground

Heff= HBS

Relative calculation method:

Heff= HBS + HTHatBS HTHatMS if HTHatBS > HTHatMS

Heff= HBS if HTHatBS HTHatMS

HBS = Base station antenna height above ground at base station site

HTHatBS = Terrain height above sea level at base station site

HTHatMS = Terrain height above sea level at mobile station site

Averaged calculation method:

Effective height = Base station antenna height above the averaged terrain height of the

prediction area


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Antenna DiversityAntenna Diversity

Diversity techniques:

Space diversity:horizontal separation (effective separation depends on azimuth)

vertical separation

Polarization diversity:

+/- 45 polarization

horizontal plus vertical polarization

Combining techniques:

Switched combining

Maximum ratio combining

Diversity gain:

Depends on the combining technique

Increases with the number of receive antennas

Increases with decreasing correlation of the individual received signals


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Antenna CablesAntenna Cables

The radio planner has to know the exact loss of the system:

Jumper cable / Feeder cable / Connectorswhich must be specified in the link budget.

Cables are characterized by:

Cross-section and length

Loss in [dB/m]

Impedance

Frequency range

Reflection factor

3rd order inter-modulation product

Minimum bending radius (for repeated bending)

Hints concerning the selection of antenna cables:

The power dissipation increases exponentially with the cable length. Thick cables have lower

losses, but larger bending radii and they are more expensive.

Avoid unnecessary long cables!


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MN 1790 1 - 47

TECHCOM

Consulting

Antenna cables and IntermodulationAntenna cables and Intermodulation

What is intermodulation (IM)?

Occurrence of frequencies different from the transmitted frequencies in the spectrum

Example: Two frequencies are used: f1 = 942.6 MHz, f2 = 945.6 MHz

Additionally frequency fIM = 936.6 MHz is measured

Responsible for Intermodulation are non-linearities in the transmission path

Example: non-linear amplifier

dirty surfaces

oxidized contacts

treated surfaces, e.g. antennas on printed circuit boards


57/394

MN 1790 1 - 48

TECHCOM

Consulting


Order of an Intermodulation Product (IMP)

IM-Frequencies are related to the transmitted frequencies by sums and differences:

fIM = | n * f1 m * f2 |

Order O of IM-Product is

O = n + m

Examples:

far away from f1 or f242 * f1 2 * f2

close to f1 and f253 * f1 - 2 * f 2

close to f1 and f232 * f1 - 1 * f 2

far away from f1 or f221 * f1 - 1 * f 2

remarkordern,m

Odd orders of IMP are close to the original frequencies!


58/394

MN 1790 1 - 49

TECHCOM

Consulting


Why can Intermodulation Products be dangerous?

IMP can be located in a frequency band where they interfere!

Example 1 (Extended GSM, f1 = 942.6 MHz, f2 = 945.6 MHz):

948.61 * f1 - 2 * f 2

951.62 * f1 - 3 * f 2

954.63 * f1 - 4 * f 2

957.64 * f1 - 5 * f 2

930.65 * f1 - 4 * f 2

4 * f1 - 3 * f 2

3 * f1 - 2 * f 2

2 * f1 - 1 * f 2

n,m

933.6

936.6

939.6

fIM [MHz]

Frequency

960 MHz925 MHz


59/394

MN 1790 1 - 50

TECHCOM

Consulting


Why can Intermodulation Products be dangerous?

IMP can be located in a frequency band where they interfere!

Example 2 (Extended GSM, f1 = 933 MHz, f2 = 955.6 MHz):

978.21 * f1 - 2 * f 2

4 * f1 - 3 * f 2

3 * f1 - 2 * f 2

2 * f1 - 1 * f 2

n,m

865.2

887.8

910.4

fIM [MHz]

915 MHz880 MHz Freq.960 MHz925 MHz


60/394

MN 1790 1 - 51

TECHCOM

Consulting

Antenna Near Products: OverviewAntenna Near Products: Overview

Antenna near products:

Antenna combiners

Receiver modules

Additional equipment

Equipment depends on base station type:

BTSone BS20, BS21, BS22, BS60, BS61

BTSplus BS40, BS41, BS240, BS241, BS240XL

Specific solutions:

BS82

BS242

BS240XS


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MN 1790 1 - 52

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Consulting

BTSone:

BTSplus:

BS82:

BS242:

Antenna Near Products: Output PowerAntenna Near Products: Output Power

40 W60 WHigh Power

25 W25 WLow Power

GSM1800/1900GSM900PA version

50 W63 WEDGE CU GMSK

32 W40 WEDGE CU 8PSK

40 W60 WGSM CU

GSM1800/1900GSM900CU version

14 W14 WCU without DUAMCO

8 W8 WCU with DUAMCO

GSM1800/1900GSM900DCU version

200 mW100 mWCA without Duplexer

GSM1800/1900GSM900CA version


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MN 1790 1 - 53

TECHCOM

Consulting

Antenna Near Products: CombinersAntenna Near Products: Combiners

Tasks of combiners:

reducing amount of antenna for transmitting

combining concepts: combining on air

hybrid couplers

filter combiners

duplex function for using the antenna in RX path


63/394

MN 1790 1 - 54

TECHCOM

Consulting

Antenna Near Products: HYCOMAntenna Near Products: HYCOM

TX 0

TESTLOOP

ANT VSWRIsolator

TX 0

TESTLOOP

ANTTX 1

3 dBHybridVSWR

Isolator

Isolator

TX 0

TESTLOOP

ANT

TX 1

TX 2

TX 3

3 dB

Hybrid

3 dBHybrid

3 dBHybridVSWR

Isolator

Isolator

Isolator

Isolator

HYCOM 1:1

HYCOM 2:1

HYCOM 4:1


64/394

MN 1790 1 - 55

TECHCOM

Consulting

Antenna Near Products: DUCOMAntenna Near Products: DUCOM

DUCOM (DUKIT) 2:1

DUKIT 2*1:1

DUCOM 4:1

RX-FIL

TX-FILIsolator

VSWR

RX-FIL

TX-FILIsolator

VSWR

TESTOUT 0

RX 0

TX 0

RX 1

TX 1

TESTOUT 1

ANT 0

ANT1

RX-FIL

TX-FIL

VSWR

RX-FIL

TX-FIL

VSWR

TESTOUT 0

RX 0

TX 0

RX 1

TESTOUT 1

ANT 0

ANT1

TX 1

TX 2

TX 3

3 dBHybrid

3 dBHybrid

Iso la to r

Iso la to r

Iso la to r

Iso la to r

RX-FIL

TX-FIL

Isolator

VSWR

Isolator

VSWR

TESTOUT 0

RX 0

TX 0

RX 1

TX 1

TESTOUT 1

ANT 0

ANT 1

RX-FIL

RX-FILRXdiv 0ANTdiv 0

RXdiv1ANTdiv 1

RX-FIL

TX-FIL


65/394

MN 1790 1 - 56

TECHCOM

Consulting

Antenna Near Products: FICOMAntenna Near Products: FICOM

ANT OUT

FICOM Base 2:1

TX 2 TX 3TX 0 TX 1

VSWR

TX 4

FICOM Expansion 2:1 FICOM Expansion 1:1


66/394

MN 1790 1 - 57

TECHCOM

Consulting

Antenna Near Products: Combiner Losses BTS1Antenna Near Products: Combiner Losses BTS1

1.82.0HYCOM 1:1

3.93.7HYCOM 2:1

7.66.5HYCOM 4:1

2.82.8DUKIT

2.52.5DUCOM 2:1

4.93.3FICOM 6:1

4.23.0FICOM 4:1

3.52.4FICOM 2:1

5.75.7DUCOM 4:1

Loss for DCS/PCS (dB)Loss for GSM (dB)Combiner type

Combiner losses for BTS one:


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TECHCOM

Consulting

Antenna Near Products: DUAMCO 2:2Antenna Near Products: DUAMCO 2:2


68/394

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TECHCOM

Consulting



69/394

MN 1790 1 - 60

TECHCOM

Consulting



70/394

MN 1790 1 - 61

TECHCOM

Consulting

Antenna Near Products: DUAMCO 2:1, 4:1Antenna Near Products: DUAMCO 2:1, 4:1


71/394

MN 1790 1 - 62

TECHCOM

Consulting

Antenna Near Products: FICOMAntenna Near Products: FICOM


72/394

MN 1790 1 - 63

TECHCOM

Consulting

Antenna Near Products: Combiner Losses BTSplusAntenna Near Products: Combiner Losses BTSplus

5.35.3DUAMCO 2:1

8.58.5DUAMCO 4:1

2.52.5DUAMCO 2:2

5.84.2FICOM 8:1

4.63.7FICOM 6:1

4.23.2FICOM 4:1

3.72.7FICOM 2:1

8.98.9DUAMCO 8:2

5.75.7DUAMCO 4:2

Loss for DCS/PCS (dB)Loss for GSM (dB)Combiner type

Combiner losses for BTS plus and BS82:


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MN 1790 1 - 64

TECHCOM

Consulting

Antenna Near Products: RX SensitivityAntenna Near Products: RX Sensitivity

BTSone: -109 dBm at rack input

BTSplus: - 116 dBm with TMA

BS82: = -110 dBm

BS242:-88 dBm (GSM900), -95 dBm (GSM1800/GSM1900)


74/394

MN 1790 1 - 65

TECHCOM

Consulting

Antenna Near Products: Receiver ModulesAntenna Near Products: Receiver Modules

Tasks of receiver modules:

amplifying received signals

different concepts: receiver module in BTS rack

Tower mounted amplifiers

splitting of received signal for TRX equipment

comparison of different signals (RX diversity)


75/394

MN 1790 1 - 66

TECHCOM

Consulting

Antenna Near Products: RXAMOD/RXMUCO,RXAMCO

Antenna Near Products: RXAMOD/RXMUCO,RXAMCO

RXMUCO within BTSE rack

Rx Antenna

R

x

C

A

B

L

E

LNA

TPU

RXAMOD at Rx antenna

LNA

Cascading Output

TPU

Cascading

Output

RXAMCO

DUCOM

TXFIL

RXFIL

LNA


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MN 1790 1 - 67

TECHCOM

Consulting

Antenna Near Products: ValuesAntenna Near Products: Values

2.52.5DUKIT

1.71.7RXFIL

2.22.2DUCOM

RX Loss for DCS/PCS (dB)RX Loss for GSM (dB)Equipment type

3030RXAMOD

22RXMUCO

22.520RXAMCO

RX Gain for DCS/PCS (dB)RX Gain for GSM (dB)Equipment type

Gain and loss of various BTS1 equipment:


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MN 1790 1 - 68

TECHCOM

Consulting

Antenna Near Products: DIAMCOAntenna Near Products: DIAMCO


78/394

MN 1790 1 - 69

TECHCOM

Consulting

Antenna

Rx Tx

LNA

TMA

Rx Tx

TriplexerEncoder

DUAMCO/DIAMCO

Antenna Near Products: TMAAntenna Near Products: TMA


79/394

MN 1790 1 - 70

TECHCOM

Consulting

19.5 (without TMA)19.5 (without TMA)DIAMCO

19.5 (without TMA)19.5 (without TMA)DUAMCO

25.525.0TMA

RX Gain for DCS/PCS (dB)RX Gain for GSM (dB)Equipment type

Gain and loss of various BTS plus equipment:

0.60.4TMA

TX Loss for DCS/PCS (dB)TX Loss for GSM (dB)Equipment type

Antenna Near Products: ValuesAntenna Near Products: Values


80/394

MN 1790 1 - 71

TECHCOM

Consulting

Antenna Near Products: Additional EquipmentAntenna Near Products: Additional Equipment

Additional equipment: DULAMO

D4EMHPDU

DUBIAS

DIPLEXER


81/394

MN 1790 1 - 72

TECHCOM

Consulting

Antenna Near Products: DULAMOAntenna Near Products: DULAMO

DULAMO for BTSone:

Allows to use TMA with BTSone

Works with HYCOM, DUCOM and FICOM


82/394

MN 1790 1 - 73

TECHCOM

Consulting

Antenna Near Products: D4EMAntenna Near Products: D4EM

D4EM for BTSone:

Allows to use 2 DUCOM 2:1 for one cell

with 4 TRX

Reduced combiner loss


83/394

MN 1790 1 - 74

TECHCOM

Consulting

Antenna Near Products: HPDUAntenna Near Products: HPDU

High Power Duplexer: HPDU

Duplex filter for combining RX and TX path

HPDU technical data


84/394

MN 1790 1 - 75

TECHCOM

Consulting

Antenna Near Products: DUBIASAntenna Near Products: DUBIAS

FICOM

HPDU

DUBIAS

TMA

TX/RX antenna

DIAMCO

TMA

CU1 CU8 RX1 RX8

BIAS-TEE for HPDU: DUBIAS

Allows use of HPDU with TMA

DUBIAS technical data


85/394

MN 1790 1 - 76

TECHCOM

Consulting

Antenna Near Products: DIPLEXERAntenna Near Products: DIPLEXER

DIPLEXER

Allows use of one feeder cable or even

one antenna for GSM900

and GSM 1800/1900

Antenna

Combiner

900

DIPLEXER

Antenna

Combiner

1800

DIPLEXER

TX/RX ant. TX/RX ant.

1700 - 2000 MHz800 - 1000 MHz

800 - 1000 MHz 1700 - 2000 MHz

Dimensions:

274mm * 126mm * 51mm

Insertion loss:

0,15 dB (800 - 1000 MHz)

0,25 dB (1700 - 2000 MHz)

Base Station

Feeder cable


86/394

MN 1790 1 - 77

TECHCOM

Consulting

Antenna Near Products: Specific SolutionsAntenna Near Products: Specific Solutions

BS82 Enhanced Micro-BTS: Solution without DUAMCO

Output Power: 14 W


87/394

MN 1790 1 - 78

TECHCOM

Consulting


BS82 Enhanced Micro-BTS: Solution with DUAMCO

Output Power: 8 W


88/394

MN 1790 1 - 79

TECHCOM

Consulting


BS242 Pico-BTS: Losses of antenna near equipment

3.8 dB3.8 dBEXTSPLIT

1.7 dB1.7 dBDUPL

GSM1800/

GSM1900

GSM900Equipment

type


89/394

MN 1790 1 - 80

TECHCOM

Consulting


BS240XS antenna near equipment


90/394

MN 1790 1 - 81

TECHCOM

Consulting

ExercisesExercises

1) What are the units for:

- the power?

- the level?

- the loss?

- the gain?

2) Write down the formula which expresses the level as function of the power.

3) Write down the formula which expresses the power as function of the level.

4) Consider a device with 10 mW output power and 1 W input power.

What is the amplification/attenuation in dB?

5) Consider a device with 100 W output power and 1 W input power.

What is the amplification/attenuation in dB?


91/394

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Consulting

ExercisesExercises

6) Fill in the following table:

Factor of: +/- 10 dB

60 dBm

50 dBm

40 dBm

30 dBm

20 dBm

10 dBm

0 dBm

-10 dBm

...

-90 dBm

-100 dBm

-110 dBm

P [W]L


92/394

MN 1790 2 - 1

TECHCOM

Consulting

Coverage Planning: ContentsCoverage Planning: Contents

Definition of Terms

Characteristics of Radio Wave Propagation


Suitable prediction models for Macro-, Micro- and Pico-cells

Location Probability

Link Budgets

Fading

Fast Fading

Rice Fading

Rayleigh Fading

Slow Fading Jake's Formula

Interference Margin

Noise Figure calculations

Amplifier Noise


93/394

MN 1790 2 - 2

TECHCOM

Consulting

Coverage Planning: ContentsCoverage Planning: Contents

Path Loss Balance

Cell Coverage Calculation

Basics about Digital Map Data

Principles of Planning Tools and their usage

Measurement Tools supporting Cell Planning

Cell Types

Omni versus Sector Cells

Exercises


94/394

MN 1790 2 - 3

TECHCOM

Consulting

Definition of TermsDefinition of Terms

To achieve coverage in an area, the received signal strength in UL and DL must be above the so

called receiver sensitivity level:

Coverage: RX_LEV > (actual) receiver sensitivity level

No Coverage: RX_LEV < (actual) receiver sensitivity level

The minimum receiver sensitivity levels in UL and DL are defined in GSM 05.05:

- for normal BTS : -104 dBm

- for GSM 900 micro BTS M1 : -97 dBm- for GSM 900 micro BTS M2 : -92 dBm

- for GSM 900 micro BTS M3 : -87 dBm- for DCS 1800 micro BTS M1 : -102 dBm

- for DCS 1800 micro BTS M2 : -97 dBm

- for DCS 1800 micro BTS M3 : -92 dBm

- for GSM 900 small MS (class 4, 5): -102 dBm

- for other GSM 900 MS: -104 dBm

- for DCS 1800 class 1 or class 2 MS : -100 dBm- for DCS 1800 class 3 MS : -102 dBm


95/394

MN 1790 2 - 4

TECHCOM

Consulting


Maximum output power forMS of different power classes:

+/- 2 dB29 dBm5

+/- 2 dB33 dBm4

+/- 2 dB36 dBm37 dBm3

+/- 2 dB24 dBm39 dBm2

+/- 2 dB30 dBm-1

ToleranceGSM 1800 MSGSM 900 MSPower Class


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TECHCOM

Consulting


Maximum output power (before combiner input) fornormal BTS / TRX of different power classes:

2.5 (


97/394

MN 1790 2 - 6

TECHCOM

Consulting


Maximum output power (per carrier, at antenna connector, after all stages of combining) formicroBTS / TRX of different power classes:

>0.05 0.16 W>0.01 0.03 WM3

>0.16 0.5 W>0.03 0.08 WM2

>0.5 1.6 W>0.08 0.25 WM1

GSM 1800

micro-BTS

GSM 900

micro-BTS

TRX power class


98/394

MN 1790 2 - 7

TECHCOM

Consulting


The reference sensitivity performance as defined in GSM 05.05 for the GSM 900 system fordifferent channel types and different propagation conditions:


99/394

MN 1790 2 - 8

TECHCOM

Consulting

Characteristics of Radio Wave PropagationCharacteristics of Radio Wave Propagation

Physical Reasons

Diffraction

Reflection

Scattering

Absorption

Doppler shift

Technical Problems

Distance attenuation

(Path Loss)

Fading

Inter-symbol Interference

Ducting

Frequency shift /

broadening


100/394

MN 1790 2 - 9

TECHCOM

Consulting

Characteristics of Radio Wave PropagationCharacteristics of Radio Wave Propagation

Exercise:

Which physical phenomena is sketched in the following pictures?


101/394

MN 1790 2 - 10

TECHCOM

Consulting

Radio wave propagation:

The radio wave propagation is described by solutions of the Maxwell equations.

Exact solutions of the Maxwell equations are not accessible for real space environment with

obstacles which give rise to reflections and diffractions.

However, the full information provided by an exact solution (e.g. exact polarization and phase ofthe field strength) is mostly not needed.

What is needed is the the received power level.

What a propagation model should provide is the attenuation of the power level due to the fact thatthe signal propagates from the transmitter to the receiver.



102/394

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TECHCOM

Consulting

Empirical models and deterministic models:

Empirical models are based on measurements. Some empirical models (like the ITU model) arecurves derived from measurements. Others summarize the measurements in formulas (like theOkumura Hata model) which fit the measured data.

Such models are very simple to handle but also usually rather imprecise. They are limited to

environments similar to the one where the measurements were performed.

Deterministic models are based on simplifying assumption for the general problem. This can be a

mathematical approximation of the original problem (like the finite difference model). Or it can be asimple model for a special situation of the general problem (like the knife edge model).

Deterministic model can reach a very high precision, but they suffer from a very high complexity.

Semi empirical models are a combination of empirical models with deterministic models forspecial situations (like knife edge models).



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TECHCOM

Consulting


Empirical models

Log distance path loss

ITUOkumura HataCOST Hata

Diffraction models

Epstein PetersonDeygoutGiovanelli

Semi empirical models

Okumura Hata & knife edge

COST Hata & knife edgeCOST Walfisch Ikegami

Deterministic models

Ray launching, ray tracing

Finite difference


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MN 1790 2 - 13

TECHCOM

Consulting

Received power:

PT: Transmitted powerPR: Reveived power

nTR dcPP =

)lg()lg()lg(lg dAdncLP

P

T

R =+==

101010Path loss:

d: distance


n

T

R dc

P

P =

0

0.2

0.4

0.6

0.8

1.0

2.5 5.0 7.5 10.0


105/394

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TECHCOM

Consulting

0 . 0 0 0 1

0 . 0 0 1

0 . 0 1

0 .1

1

1 2 5 1 0

n = 4n = 3n = 2

0

0 . 2

0 . 4

0 . 6

0 . 8

1 . 0

2 . 5 5 . 0 7 . 5 1 0 . 0

n = 4n = 3n = 2

Received power level

as function of distance don linear scale.

nR dP 1

Received power level

as function of distance d

on log scale.

nR

dP 1



106/394

MN 1790 2 - 15

TECHCOM

Consulting


2

4

dP

R

Example: Free space propagation

?: wavelength in vacuum; , speed of light in vacuum

f: frequency in MHzd: distance in km

The influence of the surface is neglected completely

f

c=s

mc 81099792 = .

( ) ( )dfL lglg. 20204432 ++=


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TECHCOM

Consulting


Example: 2 ray model

d1

d2a

d2b

d

hBS

hMS

( )( )

( )( )

d

hhdd

d

hhdhhdd

ddd

d

hhdhhdd

MSBS

MSBS

MSBS

ba

MSBS

MSBS

2

2

2

12

2

22

2

222

2

22

1

=

++++=

+=

++=


108/394

MN 1790 2 - 17

TECHCOM

Consulting



d

hhk

dd

e

d

eP MSBS

ikdikd

R

2

22

21

2

444

21

sin

( ) ( )

++=

d

hhkdfL MSBSsinlg.lglg. 2002620204432

( )dhhLMSBS

lg)lg()lg( 402020120 +=

dc

hhf

d

hhk

d

hhkhhkd

c

fk

MSBSMSBSMSBS

MSBS

2

2

=

>>

=

sinfor large

f: frequency in MHz

d: distance in km

hBS: height base station in m

hMS : height mobile station in m

The ground is assumed to be flat and perfectly reflecting.

The model is valid forhBS> 50mand din the range of km or for LOS microcell channelsin urban areas.


109/394

MN 1790 2 - 18

TECHCOM

Consulting

80

100

120

140

1601 10 100

900MHz1800 MHz

path loss in dB

distance in km


hBS = 50m

hMS = 1.5m



110/394

MN 1790 2 - 19

TECHCOM

Consulting


Log-distance path loss model:

n

R

d

dP

0

+=

0

100 d

dnLL

dlg

d0: reference distance ca. 1km for macro cells or in the range of1m -100m for micro cells;

should be always in the far field of the antennaLd0: reference path loss; to be measured at the reference distance.

2-3Obstructed in factories

4-6Obstructed in building

1.6-1.8In building LOS

3-5Shadowed urban area

2.7-3.5Urban area

2Free space

Exponent nEnvironment


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TECHCOM

Consulting


Okumura Hata model:

Based on empirical data measured by Okumura in 60s Hata developed a formula withcorrection terms for different environments.

The Okumura Hata model assumes a quasi flat surface, i.e. obstacles like buildings are not

explicitly taken into account. Thus the Okumura Hata model is isotropic. The different types ofsurfaces (big cities, small cities, suburban and rural) are distinguished by different correction

factors in this model.

Parameter range for this model:

Frequency f= 150 1500MHz

Height base station hBS

= 30 200m

Height Mobile station hMS= 1 10m

Distance d= 1 20km


112/394

MN 1790 2 - 21

TECHCOM

Consulting

[ ]

[ ] [ ]

[ ]

=

++=

974751123

805617011

556944821316265569

2

.).lg(.

.)lg(..)lg(.

)(

)lg()lg(..)()lg(.)lg(..

MS

MS

MS

BSMSBSurban

h

fhf

hd

dhchdhfL

small cities

big cities (f>400MHz)


Okumura Hata model:

f: frequency in MHz

d: distance in km

hBS: height base station in m

hMS : height mobile station in m

( )[ ] 94403318784

4528

2

2

2

.)lg(.lg.

.lg

+=

+

=

ffc

fc suburban areas

rural areas


113/394

MN 1790 2 - 22

TECHCOM

Consulting

+=

+=

00010

0020

223542126

.

.

)(

)lg(.)(.

MS

MSurban

hd

dchdL

small cities

big cities


Okumura Hata model:

Forf= 900MHz, hBS= 30m, hMS= 1,5m the formula reads:

d: distance in km

5128

949

.

.

=

=

c

c suburban areas

rural areas


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MN 1790 2 - 23

TECHCOM

Consulting


COST Hata model:

The Okumura Hata model cannot be applied directly to systems like GSM 1800/1900 o r DECT.Therefore it was extended to higher frequencies in the framework of the European research

cooperation COST (European Cooperation in the field ofscientific and technical research).



Height base station hBS= 30 200m


Distance d= 1 20km

[ ]

[ ] [ ]805617011

5569448213933346

.)lg(..)lg(.)(

)lg()lg(..)()lg(.)lg(..

=

++=

fhfhd

dhchdhfL

MSMS

BSMSBSurban


115/394

MN 1790 2 - 24

TECHCOM

Consulting


COST Hata model:

suburban areas

rural areas

city center

The major difference between the Okumura Hata model is a modified dependence onfrequency and additional correction factor for inner city areas

Forf= 1800MHz, hBS= 30m, hMS= 1,5mthe correction term for the dependence on hMScan again be neglected. For the other terms of COST Hata model the insertion of the valuesserves:

)lg(.. dcLurban

+= 223524136

( )[ ] 94403318784

4528

2

3

2

2

.)lg(.lg.

.lg

+=

+

=

=

ffc

fc

c


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MN 1790 2 - 25

TECHCOM

ConsultingBoth models, the Okumura Hata model and the COST Hata model can lead locally

to substantial deviation from the measured attenuation since these models are

isotropic. Local properties of the surface (big buildings, hills etc.) are not taken intoaccount.

9231

141

3

.

.

=

=

=

c

c

c

COST Hata model:

suburban areas

rural areas

city center



117/394

MN 1790 2 - 26

TECHCOM

Consulting

ITU model:

The ITU (or CCIR) model was originally developed for radio broadcasting. It is based onmeasurements in the UHF and VHF range which are summarized in graphs

(ITU-R 370-7, ) for the field strength.The different topographic situations are described by the parameters hBSeff and h.

The ITU model describes the radio wave propagation for the rangesf= 30... 250 MHz and 450... 1000MHz

d=10... 1000km

Definition:hBSeff is the antenna height above the mean elevation of the terrain measured in a range from 3kmto 15 km along the propagation path.

h is the mean irregularity of the terrain in the range from 10km to 50 km along the propagationpath, i.e. 90% of the terrain exceed the lower limit and 10% of the terrain exceed the upper limit of

the band defined by h.

The curves for the field strength are given for different hBSeff and h = 50m. The correction forother values ofh is given in an additional graph.Since local effects of the terrain are not taken into account the deviation between predicted and

actual median field strength may reach 20dB for rural areas. In urban areas this value may be wellexceeded.



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ITU model:


hBSeff

h

3km 10km 15km 50km

90%

10%

0km


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Correction to the ITU model: clearance angle method

An improvement of the ITU model is obtained by considering the maximum of the angle (clearance

angle) between the horizontal line and the elevations in the range of 0 to 16km along thepropagation path. The correction to the field strength ITU model (with h=50m ) is give as graphsfor the clearance angle. The clearance angle correction applies to both the receiving and thetransmitting side.


16km

MS, BS Position


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COST Walfisch Ikegami model:

For a better accuracy in urban areas building height and street width have to be taken intoaccount, at least as statistical parameters. Based on the Walfisch Bertoni propagation model for

BS antennas place above the roof tops, the empirical COST Walfisch Ikegami model is ageneralisation including BS antennas placed below the roof tops.



Height base station hBS= 4 50m


Distance d= 0.02 5km

Further parameter:

Mean building height: hin m

Mean street width: win m

Mean building spacing: bin m

Mean angle between propagation path and street: in


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b w

dBS

MS

hhBS

hMS



BS

MS


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With LOS between BS and MS (base station antenna below roof top level):


)lg()lg(. dfLLOS

2620642 ++=

With non LOS:

++

=,

,

0

0

L

LLL

L

msdrts

NLOS

0

0

+

>+

msdrts

msdrts

LL

LL

free space propagation:

rtsL roof top to street diffraction and scatter loss:

+

+

+++=

,..

,..

,.

)lg()lg()lg(.

114004

075052

354010

201010916MSrts

hhfwL

00

00

0

9055

5535

350


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msdL multiscreen diffraction loss:

)lg()lg()lg( bfkdkkLLfdamsdmsd

91

+++=

hhBS

>

( )

+

+

=

=

=

+

=

,.

,.

,

,

,.

)(.

),(.

,

,

),lg(

1925

704

1925

704

1518

18

508054

8054

54

0

1181

f

f

k

h

hhk

dhh

hhk

hhL

f

BSd

BS

BSa

BS

msd

hhBS

hhBS

>

hhBS

>

hhBS

hhBS

hhBS

50.>d

and

and

50.d

Medium sized cities and suburban centres

with moderate tree density

Metropolitan centres


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Although designed for BS antennas placed below the mean building height the COST WalfischIkegami model show often considerable inaccuracies.

This is especially true in cities with an irregular building pattern like in historical grown cities. Alsothe model was designed for cities on a flat ground. Thus for a hilly surface the model is not

applicable.


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Lee micro cell model:


This model is based on the assumption that the path loss is correlated with the total depth B ofthe building blocks along the propagation path. This results in an extra contribution to the LOS

attenuation

)()( BdLLLOS

+=

)(dLLOS

)(BFor both and can be read off graphs based on extensive measurements.

This model is not very precise and large errors occur in the following situation:

When the prediction point is on the main street but there is no LOS path

When the prediction point is in a side street on the same side of the main street as the BS.


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Diffraction knife edge model:

Diffraction models apply for configurations were a large obstacle is in the propagation path and theobstacle is far away from the transmitter and the receiver, i.e.: and 21 ddh ,

The obstacle is represented as an ideal conducting half plane (knife edge)

hMShBS

d1

h

d2

Huygens secondary source


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Huygens principle: all points of a wavefront can be considered as a source for a secondary waveletsum up the contributions of all wavelets starting in the half plane above the obstacle

Phase differences have to be taken into account (constructive and destructive interferences)

Difference between the direct path and the diffracted path,

the excess path length

Phase difference: with Fresnel Kirchoff diffraction parameter.

Note: this derivation is also valid for

( )

21

21

2

2 dd

ddh +

2

2

2

== ( )

21

212

dd

ddh

+=

0


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Diffraction loss:

+=

=

du

uii

E

EL D

D

22

12020

2

0

explglg)(

0E

DE

field strength obtained by free field propagation without diffraction (and ground effects).

diffracted field strength

Shadow border region:

+

)lg(.)(

20513

0D

L,

,

0

0

>>


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Fresnel Zone:Condition for the nth Fresnel Zone:

d1 d2

r Fnl1 l2

22121=+ nddll

Fnrdd >>

21,

Fn

Fn

r

hn

ndd

ddrddll

2

22

1

21

212

2121

=

=

++

The diffraction parameter can be rewritten with quantities describing the Fresnel zonegeometry.

For obstacles outside the 1st Fresnel zone:

For obstacles outside the 5th Fresnel zone:

dBLD

112 .)( =


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Diffraction multiple knife edge Epstein Petersen model:

The attenuation of several obstacles is computed obstacle by obstacle with the single knife edgemethod, i.e. first diffraction path: l1l2, second diffraction path: l2l3.

The model is valid for . ji dh


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Diffraction multiple knife edge Epstein Petersen model:

.

( )

21

21

11

2

dd

ddh

+=

)()(21

DDDtotal

LLL +=

The Fresnel integral is replaced by an empirical approximation:

( )[ ]

+++

110102096

0

2

..lg.)(

DL

..

,.

780

780

>N

R

PV

( )

=

N

RR

N

R

P

VV

PVf

22

12

1exp)(


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Rice Fading

0

0.1

0.2

0.3

0.4

0 2 4 6 8 10

Absolute value of signal amplitude in V

Probability

Eample: Gauean distributed signal for: VVR

51

=


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Rayleigh Fading

Rayleigh fading is the other important special case of the Ricean fading. Rayleigh fadingdescribes the situation were there is no dominant path, i.e. a non LOS situation.

All contribution to the received signal are comparable in strength and arrive statistically distributed.

with : averaged field strength, and :

=

2

2

22

R

R

R

R

R

V

V

V

VVf exp)(

RV

=

0

0

0

0

1

P

P

PPf exp)(

2

0

2

1R

VP = averaged receive power:


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0.001

0.01

0.1

1

-30 -20 -10 0 10 20

Power / averaged power in dB

Integrated probability for the power to be below a fading marging fora Rayleighdistribution

Probability

Rayleigh Fading


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Fast Fading

All described types of fast fading have as characteristic length scale the wavelength of the signals.

To combat Fast Fading:

Use frequency hopping

Use antenna diversity


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Slow Fading

XdLdL += )()(

Slow fading denote the variation of the local mean signal strength on a longer time scale.The most important reason for this effect is the shadowing when a mobile moves around (e.g. in a

city).

Measurements have shown that the variation of the the mean receive level is a normal distributionon a log scale log normal fading.

The fading can be parameterized by adding a zero mean Gaussian distributed random variable .X

Let Pm be a minimal receive level, what is the probability that the receive level is higher

than the minimal receive level, i.e. ?))(Pr( =>mR

PdP

Pr

The has to be determined by measurements.

( )

=

2

2

22

1

PPPX exp)(


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Slow Fading

To compute the probability that the receive level exceeds a certain margin the Gaussian

distribution has to be integrated. This leads to the Q function:

)(1)(

21

2

1

2exp

2

1)(

2

zQzQ

zerfdx

xzQ

z

=

=

=


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Slow Fading

0.001353.00.022752.00.158661.00.500000.0

0.000053.90.001872.90.028721.90.184060.9

0.000073.80.002562.80.035931.80.211860.8

0.000113.70.003472.70.044571.70.241960.7

0.000163.60.004662.60.054801.60.274250.6

0.000233.50.006212.50.066811.50.308540.5

0.000343.40.008202.40.080761.40.344580.4

0.000483.30.010722.30.096801.30.382090.3

0.000693.20.013902.20.115071.20.420740.2

0.000973.10.017862.10.135671.10.460170.1

Q(z)zQ(z)zQ(z)zQ(z)z

Tabulation of the Q function


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Jakes Formula

Jakes formula gives a relation for the probability that a certain value Pm at the cell boundary atradius R is exceeded and the corresponding probability for the whole cell. It is based on

the log distance path loss model:

+=

0

0 lg10)()(d

dndLPdP TR

+=

22

11

21exp)(1

2

1)(Pr

b

aberf

b

abaerfPmcell

)(Prmcell

P

( )2

)(RPP

aRm

= 2

)lg(10 en

b =


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Log-normal FadingLog-normal Fading

In a shadowing environment, the probability of a certain level as function of the level value followsa Gaussian distribution on a logarithmic scale.

In general, a Gaussian distribution is described by a mean value and the standard deviation.

Level [dBm]

Probability

Level [dBm]

Probability


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From measurements the standard deviation 1 sigma ( LNF ) in a certain environment.

Typical measurement values (outdoor, indoor) are given in the following table:

9 dB

9 dB

8 dB

LNF(i)

10 dB

8 dB

6 dB

Dense urban

Urban

Rural

LNF(o)Environment


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To achieve a certain cell edge probability LNF must be multiplied with a factor given in thefollowing table:

(Cell edge probability means the probability to have coverage at the border of the cell)

0.000

0.126

0.253

0.385

0.524

0.674

0.842

1.036

1.2821.645

1.751

1.881

2.054

2.326

50

55

60

65

70

75

80

85

9095

96

97

98

99

Factor for calculation of

lognormal fading margin

Cell edge probability in %


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Integrating the Gaussian distribution function over the whole cell area delivers cell areaprobabilities. Some example results are given in the following table:

77

91

97

99

50

75

90

95

Cell area probability in %Cell edge probability in %


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Interference MarginInterference Margin

An interference margin can be introduced in the link budget in order to achieve accurate coverage

prediction in case that the system is busy.

This margin in principle depends on the traffic load, the cell area probability and the frequency

reuse. The required margin will be small if interference level d ecreasing concepts like frequencyhopping, power control and DTX are used.

Typically, a margin of 2 dB is recommended.


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Noise Figure calculationsNoise Figure calculations

Thermal Noise:

Every object which is at a temperature T > 0K emits electromagnetic waves(thermal noise). Therefore, electromagnetic noise can be related to a temperature.

P = s * e* A * T4

Noise Factor:

The Noise Factor can be calculated from the Noise Temperature as follows:

Noise Factor = Noise Temperature / 290K + 1

Noise Figure:

The noise figure is the value of the Noise Factor given in dB:

Noise Figure = 10 * log (Noise Factor)


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Conversion table:

4384.02893.01702.0751.0

4223.92752.91591.9670.9

4063.82632.81491.8590.8

3903.72502.71391.7510.7

3743.62382.61291.6430.6

3593.52262.51201.5350.5

3443.42142.41101.4280.4

3303.32022.31011.3210.3

3163.21912.2921.2140.2

3023.11802.1841.170.1

Noise

Temp.

Noise

Figure

Noise

Temp.

Noise

Figure

Noise

Temp.

Noise

Figure

Noise

Temp.

Noise

Figure

Noise figure in dBNoise Temperature in K

Noise Figure calculationsNoise Figure calculations


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Amplifier NoiseAmplifier Noise

Amplifier:

An amplifier amplifies an input signal, as well as the noise of the input signal. It adds its own noise, which is also amplified.

GTin

Tnoise

G * Tin + G * Tnoise


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Cascade of amplifiers:

G1Tin

Tn1

G1* Tin + G1 * Tn1

G2

Tn2

G2 * (G1 * Tin + G1 * Tn1) + G2 * Tn2

= G1*G2* (Tin + Tn1 + Tn2/G1)

= G * (Tin + Tnoise)

With Tnoise = Tn1 + Tn2/G1 andG = G1 * G2

GTin

Tnoise


Equivalent to cascade of amplifiers


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Friis formula:

Tnoise = Tn1 + Tn2 / G1 + Tn3 / (G1*G2) + ...

GTin

Tnoise


Equivalent to cascade of amplifiers

Tnoise = Tn1 + Tn2/G1

G = G1 * G2


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Example:

G1Tin

Tn1

G1* Tin + G1 * Tn1

G2

Tn2

G1*G2* (T in + Tnoise)

With

Tnoise = Tn1 + Tn2/G1

Assumptions:

G1 = 16 Tn1 = 28KG2 = 20 Tn2 = 200K

Result:Gain = 320Tnoise = 40.5K

Assumptions:

G1 = 20 Tn1 = 200KG2 = 16 Tn2 = 28K

Result:Gain = 320Tnoise = 201.4K

Consequence:

Position of amplifier in chainis very important


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Exercise 1:

Calculate the noise temperature of the following system:

G Tnoise ?

Antenna cableLoss 10 dB

Amplifier in BTSGain 25 dB

Noise temperature 240K


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Exercise 2:

Calculate the noise temperature of the following system:

Tnoise ?

Cable to antenna mastLoss 10 dB

G

Amplifier in BTSGain 2 dB

Noise temperature 290K

G

Mast Head Amplifier

Gain 28 dBNoise temperature 260K


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Path Loss BalancePath Loss Balance

Since the coverage range in UL should be the same as the coverage range in DL, the radio linkmust be balanced:

Maximum allowable path loss in UL = Maximum allowable path loss in DL

Considering the link budget, usually the UL is the bottleneck, i.e. the maximum allowable path lossis determined by the UL and not by the DL, although:

The BS receiver sensitivity is usually better than the MS receiver sensitivity.

Diversity is usually only used in the receive path.

In case of an unbalanced link with weak UL, the UL sensitivity and therefore also the UL coverage

range can be increased by using tower mounted amplifiers.


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Cell Coverage CalculationCell Coverage Calculation

From consideration of link budget Maximum allowable path loss

Using radio wave propagation formulas (e.g.Hata) Maximum cell size

Exercise:

Consider a class 4 MS of height = 1.5 m. The BTS height = 30 m. Assume Hata

propagation conditions and a cell area probability of 97%. What is the maximum outdoor,

indoor cell radius and in-car cell radius:

a) In a dense urban environment ( LNF,o= 10 dB; LNF,i= 9 dB )?

b) In a suburban environment ( LNF,o= 8 dB; LNF,i= 9 dB)?

c) In an open area ( LNF,o= 6 dB; LNF,i= 8 dB)?

Assume an in-car penetration loss of 6dB.


170

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