04 2e indoor coverage for shanghai mcc v6 2e1

7/29/2019 04 2E Indoor Coverage for Shanghai MCC v6 2E1

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NORTEL NETWORKS CONFIDENTIAL

Practical Indoor Coverage

Solutions for UMTS

Prepared for Shanghai MCC

October 2003


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The Need for Indoor Coverage

Chinese cities are increasingly populated withhigh-rise buildings and underground structures

Chinese GSM subscribers are maturing They expect coverage any time, anywhere

CMCC has used indoor solutions extensively Most new structures

Many older structures ones (hotels, the subway)

There are already high standards and

expectations of indoor coverage in China


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The Challenges of UMTS

UMTS is a new technology Indoor coverage reliability for other cellular technologies has been

continuously improved over many years

UMTS supports many services not just voice

Challenge is to satisfy subscriber expectationsfor coverage and service availability on Day One


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Indoor Basics


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The Technical Difficulties of Indoor

Unique features of the indoor environment Much shorter distances

Much lower speeds

Non-uniform offered traffic

Each deployment is unique (buildings, parking garages, tunnels)

Design challenges Indoor coverage prediction via software tools nearly impossible

Field measurements are essential


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Indoor RF Design

Indoor propagation characterized by high pathloss

Due to the density of walls, corridors, small apertures, irregularities

Indoor propagation loss difficult to predict

Due to environmental variations from site to site

Virtually impossible to find a universal

propagation model

Propagation measurements in each building type are essential


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Approaching UMTS Indoor Coverage


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GSM Approach to Indoor

GSM uses multi-layer hierarchical cell structures(HCS) to address indoor coverage and capacity Enabled by FDMA/non-co-channel nature of GSM

Each cell/layer has its own radio spectrum

HCS is risky for UMTS All cells co-channel (common spectrum)

UMTS HCS would be too dependent on Compressed Mode

Risk of very low performance and capacity


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IS-95/cdma2000 Approach to Indoor

Many solutions to indoor coverage not just one Macrocell signal penetration of buildings

Macrocell design includes in-building penetration margin

RF repeaters

Small base stations with a variety of signal distribution systems

Key challenges are Managing outdoor coverage penetration to indoors, indoor

coverage spillage to outdoors

Recall: all cells are co-channel

Managing handovers between outdoor and indoor

The IS-95/cdma2000 approach is more suitable

for UMTS


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UMTS Approach to Indoor

Leverage IS-95/cdma2000 indoor engineeringexperience Get UMTS signal indoors using penetration from outdoor

macrocells, RF repeaters, and in-building signal distribution

Avoid dependence on Compressed Mode Indoor coverage co-channel with outdoor

Spectrum conserved for capacity expansion

Minimize dependence on GSM GSM used as last resort indoor coverage, not primary indoor

coverage Transition to GSM indoors could result in noticeably degraded

performance (PS) or service unavailability (CS64 videophone)


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UMTS Indoor Deployment

As with outdoor design, the goal is to create indoorserver dominance Indoor signal (CPICH Ec/I0) should dominate outdoor signal

Re-optimization of outdoor cells might be required

But the indoor signal must be contained Otherwise, the result is excessive downlink interference and handover

to the outdoor cell

These requirements arise due to 100% co-channel

nature of UMTS cells

Cannotforce UEs onto indoor or outdoor cell using configurationparameters

The only solution is to control the RF signal!


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UMTS Indoor/Outdoor Mobility Management

Soft handover when UE moves from indoors tooutdoors or vice versa No hard handover

No need for Compressed Mode


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UMTS Indoor Coverage Implementation


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Macrocell Signal Penetration to Indoors


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Macrocell Signal Penetration to Indoors Outdoor macrocells are designed with an in-

building penetration margin Results in increased cell density

This approach is widely used in most cellular

deployments to provide basic indoor coverage

No need to make specific investments in individual buildings Moderate engineering and deployment difficulty


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Macrocell Signal Penetration to Indoors

Some indoor cold spots will certainly exist Some buildings will have penetration losses greater than the

designed penetration margin

Outdoor cells not optimized for indoor coverage

Some buildings may offer significant traffic Severe impact on cell capacity if many users are near the MPL (e.g.,

deep indoors)

Outdoor cells might not provide sufficient capacity

Extremely small site spacing can lead to poor

performance (pilot pollution)


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RF Repeaters


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RF Repeaters

Benefits

An RF repeater is a low cost solution for indoorcoverage Small buildings, tunnels, underground parking

To the UE, the repeaters signal appears to be

multipath Repeater doesnt generate capacity but does

redistribute donor cells capacity efficiently Useful when traffic is low but excess system capacity is high


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isolation

RF RepeatersUnderstand Problems and Limitations

Single antenna: no receive (or transmit) diversity Macrocells noise figure increased

Both the desired signal and unwanted signals are

amplified

Spurious emissions, adjacent channels

Added delay is significant: 5-6 ms

Proper antenna isolation required

f0

5 MHz5 MHz 5 MHz 5 MHz 5 MHz

90 dB53.5 dB

45 dB35 dB

53.5 dB45 dB

35 dB


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RF RepeatersLink Budget Comparison

Outdoor User, No Repeater unit CS12.2 CS64 PS64 PS128

Channel bandwidth MHz 3.84 3.84 3.84 3.84

N0 = kT dBm/Hz -174 -174 -174 -174

Noise bandwidth (B) dBHz 65.8 65.8 65.8 65.8

BTS noise figure (NF) dB 3.3 3.3 3.3 3.3

Noise in channel bandwidth (N0 * NF * B) dBm -104.9 -104.9 -104.9 -104.9

Radio bearer data rate (not including DCCH) kbps 12.2 64 64 64

Processing gain dB 25.0 17.8 17.8 17.8

Target uplink Eb/N0 (1%/5% BLER target for CS/PS) dB 7.1 4.2 3.2 3

BTS receive sensitivity dBm -122.7 -118.4 -119.4 -119.6

Uplink load factor % 0 0 0 0

Uplink load margin dB 0.0 0.0 0.0 0.0

Maximum UE PA power at antenna connector dBm 21 21 21 21

Base station antenna gain dBi 16.5 16.5 16.5 16.5

Base station receive cable loss dB 3 3 3 3

Maximum allowable OUTDOOR path loss (no repeater) dB 157.2 152.9 153.9 154.1

Indoor User, With Repeater unit CS12.2 CS64 PS64 PS128


N0 = kT dBm/Hz -174 -174 -174 -174






Target uplink Eb/N0 (1%/5% BLER target for CS/PS) dB 7.1 4.2 3.2 3BTS receive sensitivity dBm -121.7 -117.4 -118.4 -118.6






Maximum allowable total path loss dB 156.2 151.9 152.9 153.1

Repeater gain dB 90.0 90.0 90.0 90.0

Path loss to cell site dB 110.0 110.0 110.0 110.0

Maximum allowable INDOOR path loss dB 136.2 131.9 132.9 133.1

Outdoor User, With Repeater unit CS12.2 CS64 PS64 PS128


N0 = kT dBm/Hz -174 -174 -174 -174






Target uplink Eb/N0 (1%/5% BLER target for CS/PS) dB 7.1 4.2 3.2 3

BTS receive sensitivity dBm -121.7 -117.4 -118.4 -118.6






Maximum a llowable OUTDOOR path loss (wi th repeater) dB 156.2 151.9 152.9 153.1

Outdoor User, No Repeater

Outdoor User, With RepeaterIndoor User, Subtending Repeater


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RF RepeatersCareful Engineering Required

Repeaters should not be usedas a general coverage solution

RF design, engineering, andoptimization can be tricky

Leveraging IS-95/cdma2000experience a must

UNDERGROUND PARKING

MAINDISTRIBUTION

COAX

IAL

CABLE

VERTIC

A

L

RACEW

A

Y

First

floor

utility

room

ANT

ANT

ANT

ANT

ANT

Repeater


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Indoor Base Station


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Indoor Base StationBenefits

If indoor traffic volume is high, a dedicated indoorbase station can be used Unlike other solutions, a dedicated base station provides capacity

The indoor base station uses the same carrier as

the macrocell Indoor/outdoor, outdoor/indoor mobility utilizes soft handover

No need for Compressed Mode or hard handover

Can be managed by OMC-R


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Indoor Base StationChallenges

Existing signal distribution systems might ormight not be re-usable

We do not recommend using the indoor GSM

base station as the primary source of indoor

coverage Many indoor base stations within one macrocell

can result in excessively long macrocell neighbor

lists


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Indoor Signal Distribution Systems


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Fiber Distributed Antenna System

Fiber-optic DAS is a widely used solution forlarge building indoor coverage Transmission losses are small so coverage footprint can be large

Engineering relatively

straightforward Antenna locations and fiber

routes

Downlink power & uplink

path loss required at each

antenna

Smaller equipment count:antennas, hubs, and EOMs

RFFE

MH

EHRAU Indoor

Antennas

Nortel

BTS

LGC DAS


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Coaxial Distributed Antenna System

RF coaxial DAS can be used in smaller buildings Transmission losses larger, potential coverage footprint smaller

Engineering can be tricky Antenna locations and

cable routes

Complex downlink power& uplink path loss

calculations

Larger equipment count:

combiners, splitters,

cables, attenuators,antennas, amplifiers,

connectors


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Hybrid Optical/Coaxial Distribution

In-building distributionsystems are chosen

according to

Cost

Building size & shape

Pre-existing facilities (e.g.,

fiber)

Multiple simultaneous

(hybrid) solutions are

possible HOTEL COVERAGEHOTEL COVERAGE

PARKING COVERAGEPARKING COVERAGE

POWER AVAILABLE FORPOWER AVAILABLE FOR

ENHANCED COVERAGEENHANCED COVERAGE

S1S1 S2S2

S3S3

HOTEL COVERAGEHOTEL COVERAGE

PARKING COVERAGEPARKING COVERAGE

POWER AVAILABLE FORPOWER AVAILABLE FOR

ENHANCED COVERAGEENHANCED COVERAGE

S1S1S1S1 S2S2S2S2

S3S3S3S3


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DAS Antenna Placement StrategiesFrom IS-95/cdma2000 Experience

Each floor should utilize multiple antennas Antennas located at corners, radiating inward

Ensures indoor signal dominates outdoor at building edges

Transmit and receive diversity improves indoor

performance UMTS UE sees each antennas signal as another multipath

Time [chips]

Ec/Io


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floor 1

Corridor

CorridorSource

Tunnel

Amplifier

radiating cable feeder

Building

Yagi antennas

Leaky Coaxial Antenna Feeder

Leaky cable is suitable for certain situations Tunnels, indoor corridors

Engineering can be tricky Complex gain/loss calculations

Moderate equipment count: amplifiers, antennas, leaky cable,

regular cable, connectors


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How to Choose an Indoor Coverage Solution


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Coverage Solution Selection Process

Each indoor deployment scenario will have aunique solution Solutions are selected after detailed assessment of each

deployment environment

Considerations when choosing a solution include Cost

Flexibility and ease of engineering

Capacity requirements


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Summary of Indoor Coverage Solutions

Macrocell Building

PenetrationRF Repeater

Dedicated Base Station

with DAS

Cost

depends on penetration

margin utilized

hardware: low

engineering: high

hardware: high

engineering: high

Coverageno deep indoor coverage good excellent

Capacity no benefit no benefit excellent

Impact on Macrocell

potential capacity

reduction if indoor traffic

is high, or if penetration

margin is large

coverage reduction

larger neighbor list,

potential capacity

reduction if engineering

is improper

Engineering Effort moderate moderate high

Typical Deployment Scenarios

ground floors of all

building types

tunnels, parking

garages, small buildings

highrises, shopping

malls, campuses,airports


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Summary


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A Cost Effective Practical Indoor Solution

Summary

Significant UMTS indoor coverage is requiredfrom service launch

Indoor coverage strategies should be based onCDMA experience rather than GSM experience

Indoor coverage will be provided by a mix of

solutions, not just indoor base stations


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04 2e indoor coverage for shanghai mcc v6 2e1

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