das-distributed antenna system part 2

8/2/2019 DAS-Distributed Antenna System Part 2

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Overview ofDistributed Antenna Systems

(DAS)


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Ways to Improve In-buildingCoverage


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When should each solutionsbe used?

There is not one single solution that is bestfor all purposes. In fact, operators need arange of solutions.

Traffic

PicoRepeater

Micro Repeater +Passive

Pico Repeater +active

Macro BTS +passive

PicoBTS +

active

Building size and complexity

Macro BTS +active

PicoBTS


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Why use DAS Systems ?

To increase coverage

To increase coverage and capacityTo increase coverage, capacity,

and functionality


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DAS deployment motivation

Mobile usage Indoor is the environment where most of the mobile

traffic is created

Studies estimate that 70-80% of traffic will becreated in this environment

Using this value and the actual Optimus traffic reality, we can predict thatonly 2% of the indoor traffic will be performed in the present dedicatedprojects; the remaining 98% will be carried by the macro layer

High revenue data services are more suited to be used in the indoorenvironment


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User perspective

Users demands in terms of QoS are higher and tolerance toproblems is smaller in the indoor environment:

Users will demand good QoS for voice and data servicesmore so when UMTS is implemented later

Users will be specially demanding in what concerns highbit rate data services due to their cost

In the indoor environment the user has an alternativeservice the fixed and the comparison is naturally madeagainst this service

Operator needs to guarantee a much better performance ofthe network in the indoor environment than in the outdoor


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Indoor coverage from the macro layer

In free space, GSM 1800 signal has higher attenuation thanGSM 900, due to the higher frequencies it uses

The dependence of building attenuation is not clear; itdepends on several factors apart from the frequency and thedistance:

Materials and how they are arranged

Orientation relative to the outdoor site

Building environment

Floor geometry

Floor level

Room dimensions

Windows size0

5

10

15

20

25

30

35

40

45

50

Study 1 Study 2 Study 3A Study 3B

Attenuation

(dB)

900MHz

1800MHz

2300MHz


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Indoor coverage from the macro layer

The coverage varies along the height of thebuildings due to:

The shadow effect from other buildings in the lower floors

The direction of the main lobe of the antenna Typically the sites are more down tilted so a lower

coverage is expected in the upper floors

Attenuation with respect to outdoor coverage

0

5

10

15

20

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18Floor

Attenuation

(dB)


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Indoor signal penetration

The propagation loss inside a building depends on severalfactors:

A study performed for the 900, 1800 and 2300 MHz frequencies under aspecific set of conditions reached the following variation of path loss as afunction of distance:


Frequency

Floor dimensions & geometry

Number of floors between emitterand receiver

0

10

20

30

40

50

60

7080

5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100d (m)

Pathloss(dB)

900MHz PathLoss (dB)



Distance

Materials & their arrangement

Leakage to the outside and back


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Marketing and Sales perspectives To know the clients is a marketing competitive advantage

Indoor dedicated projects allow to know the clients - which servicesthey use, when they use them and in what amount - and to beproactive in the delivery of new services with interest to both the clientand the operator

With a dedicated project operators can follow the clients onthe services by carefully looking at the QoS indicators, andbe proactive in the resolution of problems

Adding all this together the operator can provide a service ofexcellence to the clients

creating a partner relationship where the clients feel comfortable andsatisfied

increase in ARPU

Retention and reduction in the churn and captivating new costumers



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Motivations for DedicatedCoverage

CoverageCapacity

Indoor Location Based Services

Reduced cell loading on macro network Increased peak and mean user data rates

Location-specific tariffs

Minimise delay spread

Overcome mobility limitations

Reduce RF exposure

Increase battery life


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Motivations

Users Coverage

Access to network

Ease of Use

Mobility

Cost Health & Safety, data security

Compelling services

Operators Access to users

Low initial and ongoing costs

Differentiated services

Customer retention

Corporate social responsibility (Health& Safety, Security)

Tenants Continuity of business

Quiet Enjoyment

High, appropriate, footfall

Corporate Social Responsibility

Landlords Continuity of business (own and tenants)

High, appropriate footfall

Preserve and enhance property value

Corporate Social Responsibility


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In-building System Example


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General Architecture


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Why Deploy Wireless DAS

Macro cellular coverage does not generally provide good and reliable

in-building coverage without a coverage enhancement Provide employees mobility so they can work anywhere within the

facility Improves a Companys Customer Satisfaction

Calls not Missed Better Call Quality

Calls Not Dropped Data is available on demand

Increases Revenue Faster Response Times Reduced Lost Sales Improved Employee Productivity/Efficiency

Reduced Facilities Cost Wiring to difficult places is reduced since the endpoints/devices are

wireless.

Provide Reliable communications for security & public safety


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Benefits of In-Building Systems

Subscribers can originate/receive voice or data whilein moving within commercial and public buildings Extension of cellular network coverage to corporate,

campus, high-rise, and public sites is required forseamless coverage and subscriber satisfaction

Provide seamless coverage and roaming to buildingand campuses Reliable communications for public safety (e.g. police,

fire, EMS, etc.) are required. Can support multiple access technologies

Can deliver many applications to mobile users Constant access to corporate applications, servers,

and the Internet Can improve operational efficiency of employees and

the business

Unobtrusive


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DAS Types

Passive distribution systems

Active distribution systems


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Passive DAS RF Coverage

Solutions


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Passive DAS Solutions

What is it?RF Source-Base station/repeater/mini repeater

used to drive system Components:Coaxial cable

RF splitters

Antennas

Leaky Cables


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Passive DAS

Discrete Antennas

Each Cable Run Ends in One Antenna

Creates Hot Spots Troublesome Near Windows

Phones Operate in Far Field

Advantage: Directivity and Deployment


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Passive DAS- RF Sources

Repeater:

10 W / 20 W output

Max 50-100 db gain Isolation issues

Donor and coverageantenna placement

Low costNo backhaul

Easy to install

Base station:

Macro BTS 10 W

Micro BTS 1WPico BTS mws

High cost

Requires backhaul

Dedicated room


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Passive DAS- Power Dividers

Power divider

Resistive components

Balanced orunbalanced types

available

Factors to consider:

Splitting loss

Insertion loss

0 dBm In

-3.5 dBmOut

-3.5 dBmOut


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Passive DAS- Antennas

Observe building layout

Locations for RF source first

Antenna placementsIdeal vs. reality

Aesthetic issues

Suspended ceiling a plusColumns and pillars


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Open areas

Equal distance between

boundaries

Omni-directional Antenna

FLOOR PLAN


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Areas with leakage constraints

Long and narrow halls

Directional Antenna

Floor Plan


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Passive DAS- Leaky Coax

Cable Run Is the Antenna

No Hot Spots

Phones Operate in Near Field Building Structure Spoils Far Field

Pattern

Simpler but Costly Installation Installs Out of Sight


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Passive DAS

Types:

Parallel

Series


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Passive DAS- Parallel

0 m 80m 160m 240m

20 dBm

input

320m

(-5 dB)(-5 dB)

(-5 dB)

(-5 dB)

2-way Splitter

ERP = 11.5 dBm3 dBm -5.5 dBm

-11.5 dBm


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Passive DAS- Series

0m 80m 160m

15 dB

Coupler

10 dB

320m240m

6 dB

ERP =0 dBm0 dBm -1 dBm

20 dBm

in ut

-0.4 dB -0.5 dB -1.4 dB

-2 dBm

-5 dB (-5 dB) (-5 dB)

(-5 dB)


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Antenna Arrangement forMultiple Floors


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Distributed Systems: Multiple Antenna

Multiple antennas provide more homogeneouscoverage than single antenna

Less interference from in-building to or from the

outer world Easier to make in-building cells the best service

everywhere in the building

Effective use of allocated spectrum

P i Di ib i K D i


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Passive Distribution Key DesignIssues

When using a repeater isolation betweendonor & coverage antennas has to be checked

Need minimum repeater gain + 15 dB

Noise back to the BTS needs to be checked

Noise Calculation back at BTS

Link budget analysis

Power per channel available from repeaterSplitter/coupler losses

Cable insertion losses

Antenna gain


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Noise floor increases due to loss

Signal loss through distribution network

Additional loss due to splitters or taps

Using radiating cable vs. run- and- drop

Designing multi-antenna star topology

Single- or multi-band distribution

Overall cost vs. performance

Passive Distribution KeyDesign Issues

Li it f A ti DAS i M lti


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Limits of Active DAS in Multi-band Applications

In excess of 150-200 meters the cable loss is too high, therefore

it becomes less convenient for passive distribution

Due to cable slope, Multiband Multiservice distribution

requires higher power at higher frequencies

Attenuation

[dB]

0

5

10

15

20

25

30

35

40

45

50

50 100 200 400

900MHz

1800MHz

2400MHz

Length[m]


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Active DAS:The Concept

An RF to optical hub

Single-mode fiber transport

An optical to RF remote

Coaxial distribution to multiple radiating points

Why fiber and coax? Minimize Cost

Maximize installation ease

Maximize flexibility


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When can passive systemsexpect to be problematic?

High and wide buildings can generate highlosses in a passive system

Historical buildings can be sensitive toextensive drilling and pulling of thick cables

Campus applications like universities,amusement parks, sports arenas havebuildings that are separated

For buildings with restricted access likehospitals, hotels, tunnels, airports

When upgrading low frequency systems (likeGSM900) to UMTS UMTS is uplink limited and very sensitive to high

losses in a large passive network

For very tall, wideor complexbuildings

Historical buildingswhere drilling is not

allowed

Campusapplications


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Active DAS: Fiber and Coax

Utilize fiber optic distribution from the basestation to the remote unit

Low loss for long distances

Frequency independent

Utilize coaxial cable to transport the signalsfrom the remote unit to several (2-4) radiatingpoints

No power required

Low loss for short distances


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Active DAS:


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Active DAS:A Multi-technology Environment

1) Network interface: High Power RF, Low power RF, Air interface,.

2) Low power passive RF:Cross-band and hybrid couplers, signal conditioning

and monitoring.3) Signal Conversion (electrical to optical)

4) Cabling, interconnection, remote supply distribution

5) Signal conversion (optical to electrical), RF processing, RF Amplification

6) Passive wideband RF

7) RF Radiating

8) Monitoring, control, SW & digital communication

POINT OF

INTERFACE

NETWORKBTS

TX

RX

E/OCONVERSION

O/ECONVERSION

O/ECONVERSION

O/ECONVERSION

O/ECONVERSION

O/ECONVERSION

O/ECONVERSION

O/ECONVERSION

O/ECONVERSION

Centralised Equipment

ACTIVEDistribution

CoverageArea

PASSIVEDistribution

BTS

TX

RX

BTS

TX

RX

E/OCONVERSION

E/OCONVERSION

E/OCONVERSION

E/OCONVERSION

E/OCONVERSION

E/OCONVERSION

E/OCONVERSION

1 2 3 4 5 6 7 8


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Active Systems: Advantages

Efficient use of fiber and cable by multiplexingvarious frequencies onto the backbones.

Built to allow several operators in the same or

different frequency band to share the system. The RF part provides independent control and

level mechanism to optimize and maintainsystems for each single operator.

Expandable to allow more operators to join the

system at a later stage.


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Active Systems: Upgradeability

Capacity is not limited by initial hardwaredeployment.

No physical limitation for the remote

antenna location. BTS capacity can be added in central

equipment rooms.

Wideband or band selective RF frontends have virtually no limitation on multichannel operation.

A ti Di t ib ti D i


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Active Distribution DesignIssues

Accurate provisioning: power per RF user

Existing vs. installed distribution wiring

Single- mode fiber vs. multi- mode fiber Upgradeable architecture

Overall cost vs. performance


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Distributed Systems: Different Media

Fiber optic: Interference Immunity

Loss-independence oftransmission frequencies

Small diameter of fiber

bundle Small bending radius of

fiber bundle

Well suited for longdistances

High Bandwidth

Coaxial cable: Susceptible to Interference Higher loss at higher

transmission frequency

Large diameter if low loss

is required Large bending radius if low

loss is required

Thin coaxial cable is easyto install

Well suited for shortdistances (< 50 m)

C i


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ComparisonCoax and FDAS: Cost

Fiber Active Solution cost includes: installed fiber, optical

transducers and typical output power of 50mW per band

Cable cost doesnt include any active cable booster

0

2

4

6

8

10

12

14

16

50 100 200 400 800

Thousan

ds

Coax1/2"

Single Band twin fibre

Dual band twin fibre

TriBand twin fibre

Length (m)

Cost

coax

fiber

Can we compare the cost of

an installed segment of coaxwith an installed segment offibre ?

The additional cost ofElectro/Optic transducers iscompensated as long as fiberrun is >100mt.


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Distributed Systems: Optical vs. BTS

Optical distribution: Infrastructure is shared

among operators Remote units and

radiating points are

shared among operators Less impact on building No need to enter each

remote unit forrestructuring and

capacity enhancement Lower cost in case of

high rise buildings Easy upgradeability

Micro base station:

Infrastructure cannot beshared among operators

Micro base station cannot

be shared amongoperators

Higher impact on building

Units have to be added or

moved if capacityenhancement is needed

Cost increase issubstantial for High rise

buildings

A ti DAS


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Active DAS:An Answer for any Requirements

POINT OF

INTERFACE

NETWORKBTS

TX

RX

E/OCONVERSION

O/ECONVERSION

O/ECONVERSION

O/ECONVERSION

O/ECONVERSION

O/ECONVERSION

O/E

CONVERSIONO/E

CONVERSION

O/ECONVERSION

Centralised Equipment

ACTIVE

Distribution

Coverage

AreaPASSIVE

Distribution

BTS

TX

RX

BTS

TX

RX

E/OCONVERSION

E/OCONVERSION

E/OCONVERSION

E/O

CONVERSION

E/OCONVERSION

E/OCONVERSION

E/OCONVERSION

+SCALABILITY +BANDWIDTH +SPECTRAL EFFICIENCY+FLEXIBILITY

A ti DAS


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+flexibilityModular architectureDifferent Output power and config. optionsSuitable for different technologiesIndependent on optical loss

+ScalabilityEasily expandableUpgrades will not affect main investments

+Bandwidth

Suitable for present and future services

Ready for band extension

+Spectral efficiencyHigh dynamicsSuitable for complex modulation schemesNegligible EVM degradation

Active DAS:An Answer for any Requirements


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Active DAS-Technology of Choice

ONE SYSTEM for ALL SERVICES OPEN INFRASTRUCTURE

CENTRALIZED EQUIPMENT EASE OF MAINTENANCE

LOW POWER CONSUMPTION INCREASED MTBF

MODULAR CONFIGURATION SCALABLE INVESTMENT

REDUNDANT POWER SUPPLY MAXIMUM RELIABILITY

WIDE RANGE OF OPTIONS APPLICATION-ORIENTED DESIGN

INTEGRATED MONITORING FUNCTIONS HIGHEST LEVEL OF SYSTEM MANAG.

STRONG AND UNIFORM COVERAGE OPTIMUM NETWORK PERFORMANCE


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Any Questions


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das-distributed antenna system part 2

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