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4G LTE – Drivetest and Cove

Different Between TD-LTE & FD-LTE

Item LTE-TDD LTE-FDD

Duplex mode TDD FDD

Frame structure Type 2 Type 1

UL and DL Ratio 7 types of UL and DL ratio, flexible All subframes can be allocated only fo

downlink.

RRU Noise Figure

A T/R converter is required. The T/R

converter will bring about the insertion

loss of 2~2.5 dB .

A duplexer is required and the duple

about the insertion loss of 1

BeamformingSupported (exchangeability based on

uplink and downlink channel)

Not supported (no exchangeability ba

and downlink channels)

MIMO Mode Modes 1 –8 are supported. Mode 1 –6 are supported

Network InterferenceStrict synchronization is required in the

whole network.Synchronization requirement is n

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Drive Test Peripheral

Notebook

GPS

LTE

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4G LTE – Drivetest and Coverage Analysis| Page 4

ReferenceSignal Received

Power (RSRP)

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LTE RS Power Allocation• RS Power for 20 MHz @ 10W/port

RS = 40dBm – 10*log(12*100) + 10*log(1+1)

= 12.2 dBm

• RS Power for 10 MHz @ 5W/portRS = 37dBm – 10*log(12*50) + 10*log(1+1)

= 12.2 dBm

RS Power for 10 MHz @ 10W/port

RS = 40dBm – 10*log(12*50) + 10*log(1+1)= 15.2 dBm

With the same total power, coverage LTE

10 Mhz is larger than with LTE 20 MHz

RS Power for 10 MHz @ 10W/

RS = 40dBm – 10*log(12*50) = 15.2 dBm

With the same total power, co

10 Mhz is larger than with LTE

Impact on Radio Netw

Performance: A larger

results in a larger incr

ReferenceSignalPwr, b

estimation performan

PDSCH demodulation

but it also leads to low

power of the PDSCH (

increases

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LTE RS Power Allocation

• Power Boosting for RS

PB =1 by default

• RS Power for 20MHz

= 43 – 10*log(100*12) + 10*log10(PB+1) = 15.2dBm

Bandwidth 10M

15M

20M

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RS Power Overhead Comparison with CPICH

Type A Symbol: without RS REsType B Symbol: with RS REs

• RS power per RE is 15.2dBm (0.033W) for 20MHz

• Total RS power in 20MHz for Type B Symbol is 0.033*2 (RS REs/ RB) * 100 RBs = 6.6W

• Total RS power in 20MHz for Type A Symbol is 0

• Only two symbols carry RS within 0.5ms and hence the RS power overhead is about over 1 timeslot

LTE RS power overhead is about 9.4% which is similar to 10% CPICH

of UMTS

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RxLev, RSRP and RSCP ComparisonItems GSM UMTS LTE

(e)NodeB power per Tx (dBm) 43 43 43

Bandwidth (MHz) 0.2 5 20

Number of RB N/A N/A 100

BCCH Power/ CPICH power

/RS power per RE (dBm) 43 33 15.2

CL (dB) 120 120 120

Rx Lev/RSCP/RSRP (dBm) -77 -87 -104.8

Received RS signal strength

over whole bandwidth

-81.8

RSRP is the recei

over 15KHz band

bandwidth of RS

RSRP of LTE is much smaller than RSCP of UMTS under same radi

Only 1/6 REs is used

within one RB and h

power is 10*log10(

than RSRP

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4G LTE – Drivetest and Covera

Factors Influencing LTE Coverage

Some other factors such as site height, BPL, TMA, coverage probability,…

TX Power

MIMO Radio Condition

Frequency

BandData RateICIC

RB NuFactors Affecting LTELink Budget

MCSCell Load

InterferenceMargin LTE Standard

LTE

Specific

ICIC：Inter Cel

k d l

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Weak Coverage and Coverage Holes

The signal quality in cells is poorer than the optimization baseline

As a result, UEs cannot be registered with the network or accessed s

cannot meet QoS requirements.

If there is no network coverage or coverage levels are excessively low in an area, the area is

coverage area. The receive level of a UE is less than its minimum access level (RXLEV_Adownlink receive levels in a weak coverage area are unstable. In this situation, the UE is d

network. After entering a weak coverage area, UEs in connected mode cannot be handed

cell, and even service drops occur because of low levels and signal quality.

Weakcoverage

Coverage holes

R l i W k C P bl

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Resolving Weak Coverage Problems

Analyze geographical environments and

check the receive levels of adjacent

eNodeBs.

Analyze the EIRP of each sector based on

parameter configurations and ensure

EIRPs can reach maximum values if

possible.

Increase pilot power.

Adjust antenna azimuths and tilts,

increase antenna height, and use high-gain

antennas.

Deploy new eNodeBs if coverage hole

problems cannot be resolved by

adjusting antennas.

Increase coverage by adjacent eNodeBs

to achieve large coverage overlapping

between two eNodeBs and ensure a

moderate handover area.

Note: Increasing coverage may lead to

co-channel and adjacent-channel

interference.

Use RRUs, ind

leaky feeders, a

resolve the pro

elevator shafts

garages or bas

buildings.

Analyze the im

terrains on cov

Case: Searching for a Weak Coverage Area by Using a Scanner or Performing Drive Tests

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Case: Searching for a Weak Coverage Area by Using a Scanner or Performing Drive Tests

UEs

Perform drive tests in zero-load environments to obtain

the distribution of signals on

test routes. Then, find a

weak coverage area based

on the distribution, as

shown in the figure.

Adjust RF parameters of the

eNodeB covering the area.

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R l i P bl ith L k f D i

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Resolving Problems with Lack of a Dominan

…

Adjust engineering

parameters of a cell that can

optimally cover the area as

required.

Determine cells covering an

area without a dominant cell

during network planning, and

adjust antenna tilts and

azimuths to increase coverage

by a cell with strong signals

and decrease coverage of

other cells with weak signals.

C S hi f A With t C ll

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Case: Searching for an Area Without a Dominant Cell

Symptom

UEs frequently perform cell reselections or

handovers between identical cells.

Analysis

Analysis can be based on signaling procedures andPCI distribution.

According to PCI distribution shown in the figure,

PCIs alternate in two or more colors if there is no

dominant cell.

Solution

According to the coverage plan, cell 337 is a

dominant cell covering the area and cell 49 also hasstrong signals. To ensure handovers between cells 337

and 49 at crossroads, increase tilts in cell 49.

1.P

La

do

ce

Cross Co erage

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Cross Coverage

Cross coverage means that the coverage scope of an eNodeB exceeds the planned on

discontinuous dominant areas in the coverage scope of other eNodeBs. For example

much higher than the average height of surrounding buildings, its transmit signals p

roads and form dominant coverage in the coverage scope of other eNodeBs. This is

If a call is connected to an island that is far away from an eNodeB but is still served b

around the island are not configured as neighboring cells of the current cell when ce

are configured, call drops may occur immediately once UEs leave the island. If neigh

configured but the island is excessively small, call drops may also occur because UE

handed over. In addition, cross coverage occurs on two sides of a bay because a shotwo sides. Therefore, eNodeBs on two sides of a bay must be specifically designed.

Cross

coverage

Resolving Cross Coverage Problems

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Resolving Cross Coverage Problems

…

Adjust antenna tilts or replace

antennas with large-tilt antennaswhile ensuring proper antenna

azimuths. Tilt adjustment is the

most effective approach to control

coverage. Tilts are classified into

electrical tilts and mechanical tilts.

Electrical tilts are preferentially

adjusted if possible.

Adjust antenna azimuths properly

so that the direction of the mainlobe slightly obliques from the

direction of a street. This reduces

excessively far coverage by electric

waves because of reflection from

buildings on two sides of the street.

Decrease th

a high site.Decrease tr

carriers whe

not affected.

Case: Cross Coverage Caused by Improper Tilt Settings

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Case: Cross Coverage Caused by Improper Tilt Settings

Symptom

As shown in the upper right figure, cross coverage

occurs in a cell whose PCI is 288. Therefore, the cell

interferes with other cells, which increases the

probability of service drops.

Analysis

The most possible cause for cross coverage is

excessively antenna height or improper tilt settings.

According to a check on the current engineering

parameter settings, the tilt is set to an excessively

small value. Therefore, it is recommended that the tilt

be increased.

Solution

Adjust the tilt of cell 288 from 3 to 6. As shown in the

lower right figure, cross coverage of cell 288 is

significantly reduced after the tilt is adjusted.

Case: Inverse Connections Involved in the Antenna System

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Case: Inverse Connections Involved in the Antenna System

SymptomThe RSRPs of cells 0 and 2 at the Expo Village site are low and

high respectively in the red area shown in the figure. The signalquality of cells 0 and 2 is satisfactory in the areas covered bycells 2 and 0 respectively.

Analysis After installation and commissioning are complete, the RSRP in

the direction of the main lobe in cell 0 is low. After cell 0 is

disabled and cell 2 is enabled, the RSRP in cell 2 is normal andthe SINR is higher than that tested in cell 0. Therefore, thisproblem may occur because the antenna systems in the twocells are connected inversely. Test results are as expected afteroptical fibers on the baseband board are swapped.

SolutionSwap optical fibers on the baseband board or adjust feeders and

antennas properly. It is recommended that optical fibers on thebaseband board be swapped because this operation can beperformed in the equipment room.

SuggestionsNetwork planning personnel must participate in installation.

Alternatively, customer service personnel have detailed network

planning materials and strictly supervise project constructors forinstallation. After installation is complete, labels must beattached and installation materials must be filed.

Imbalance Between Uplink and Downlink

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Imbalance Between Uplink and Downlink

When UE transmit power is less than eNodeB transmit power, UEs in idle mode may

successfully register in cells. However, the eNodeB cannot receive uplink signals

when UEs perform random access or upload data. In this situation, the uplink cov

the downlink coverage distance. Imbalance between uplink and downlink involves

coverage. In limited uplink coverage, UE transmit power reaches its maximum but

requirement for uplink BLERs. In limited downlink coverage, the downlink DCH tra

its maximum but still cannot meet the requirement for the downlink BLER. Imbala

downlink leads to service drops. The most common cause is limited uplink covera

Imbalance

between

uplink and

downlink

Uplink coverage areaDownlink coverage area

coverage area

Resolving Problems with Imbalance Between Uplink and Downlink

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Resolving Problems with Imbalance Between Uplink and Downlink

…

If no performance data is available for RF

optimization, trace a single user in the OMC

equipment room to obtain uplink measurement

reports on the Uu interface, and then analyze the

measurement reports and drive test files.

If performance data is available, check each

carrier in each cell for imbalance between uplink

and downlink based on uplink and downlink

balance measurements.

If uplink interference leads to imbalance

uplink and downlink, monitor eNodeB ala

check for interference.

Check whether equipment works proper

whether alarms are generated if imbalanc

uplink and downlink is caused by other fa

example, uplink and downlink gains of rep

trunk amplifiers are set incorrectly, the an

system for receive diversity is faulty when

and transmission are separated, or power

are faulty. If equipment works properly or

generated, take measures such as replace

isolation, and adjustment.

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4G LTE –

Drivetest and Coverage Analysis| Page 23

Signal to Noise& Interference

Ratio (SINR)

Traditional Frequency Planning

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Traditional Frequency Planning

1

1

Advantage

Higher spectrum efficiency

Disadvantage Lower cell edge throughput due to serious interference

Suitable Scenario Lacking frequency resource Capacity requirement scenarios, such as dense urban and urban areas during network

initial stage

1*3*1 Frequency Planning

Advantage Lower interference and larger coverage radius

Disadvantage Lower spectrum efficiency

Suitable Scenario Abundant frequency resource or inconsecutive spectrum scenarios large coverage

scenarios.

1*3*3 Frequency Planning

Interference and Capacity Comparison 1*3*3

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Interference and Capacity Comparison 1 3 3

The downlink service channel SINR of ×3×

and ×3×3

0

0.2

0.4

0.6

0.8

1

-10 0 10 20 30 40

SINR

C D F

1×3×1 1×3×3

SINR distribution comparison Average sector capacity compariso

1*3*3 with low interference because of more frequency resource.

1*3*3 with high sector capacity because of low interference.

More frequency resource required for 1*3*3

1*3*3 10MHz channel (30MHz) compare with 1*3*1 10MHz channel (

SINR

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SINRThe SINR is not specifically defined in 3GPP specifications. A common formula is as follow

SINR = S/(I + N)

S: indicates the power of measured usable signals. Reference signals (RS) and physica

channels (PDSCHs) are mainly involved.

I: indicates the power of measured signals or channel interference signals from other cesystem and from inter-RAT cells.

N: indicates background noise, which is related to measurement bandwidths and receive

coefficients.

Empirical SINR at the edge of a cell:

The SINR is greater than -3 dB in 99% areas in Norway.

The SINR is greater than -3 dB in 99.25% areas in the Huayang field in Chengdu.

Signal Quality (SINR is mainly involved)

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Signal Quality (SINR is mainly involved)

Frequency

plan

③ Site

selection

④ Antenna

height

⑤ A

az⑥ A

Cell layout

Resolving Signal Quality Problems Caused by Improper Parameter Sett

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g g Q y y p p

Change and optimize frequencies based on drive test and

performance measurement data.

Optimizing

frequencies

Adjust antenna azimuths and tilts to change the distribution of signinterfered area by increasing the level of a dominant sector and dec

other sectors.

Adjusting the

antenna

system

Increase power of a cell and decrease power of other cells to form

cell.

Decrease RS power to reduce coverage if the antenna pattern is

of a large antenna tilt.

Power adjustment and antenna system adjustment can be used t

Adding dominant

coverage

Adjusting power

Case: Adjusting Antenna Azimuths and Tilts to Reduce Inte

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Case: Adjusting Antenna A imuths and Tilts to Reduce Inte

SymptomCross coverage occurs at sites 1, 2, 3, 7, 8, 9, 10, 11, and 12, and co-channel i

in many areas. Analysis

According to the analysis of engineering parameters and drive test data, cell decoverage areas. Coverage by each cell can be reduced by adjusting antenna

SolutionChange the tilt in cell 28 from 2 degrees to 4 degrees so that the direction poindemonstration route. Change the tilt in cell 33 from 3 degrees to 6 degrees so points to the Wanke Pavilion. Change the tilt in cells 50 and 51 from 3 degreesthat the direction points to the Communication Pavilion. Decrease the transmit3 dB to reduce its interference to overhead footpaths near China Pavilion.

SINR before optimization in Puxi SINR after

Poor signal

quality before

optimization

Case: Changing PCIs of Intra-frequency Cells to Reduce Int

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g g q y

Symptom

Near Japan Pavilion, UEs access a cell whose PCI is 3 and SINRs are low. UEs are about 200

eNodeB. This problem may be caused by co-channel interference.

Analysis

This problem is not caused by co-channel interference because no neighboring cell has the sam

current cell. Cell 6 interferes with cell 3. SINRs increase after cell 6 is disabled. In theory, stagg

reduce interference.

Solution

Change PCI 6 to PCI 8. Test results show that SINRs increase by about 10 dB.

SINR when cell 6 is enabled SINR when cell 6 is disabled SINR w

Case: Handover Failure Caused by Severe Interference

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y

Symptom

During a test, handovers from PCI 281 to PCI 279 fail.

Analysis

Cell 281 is a source cell and is interfered by cells 279 and 178. Delivered handover co

fail and cannot be received correctly by UEs. Cell 279 is a target cell for handover, and

not adjusted preferentially because the signal strength in the handover area can ensur

after handovers. Therefore, cell 178 must be adjusted to reduce its interference to cell

Solution

Adjust antenna tilts to decrease coverage by cell 178.

SINR Improvement

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SINR Improvement AFTER ACPINITIAL PLAN

In the inner city of Jakarta where ZTE antenna configuration taken

into the initial planning show there are so much SINR around 0~5

(dB). After do the ACP Optimization the SINR much improve with

much blue color (SINR >=15 dB)

Initial Plan

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Initial Plan

After ACP

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Radio Parameter @ GENEX Probe

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@

PCI (Physical Cell Identifier)

Value range : 0 – 839, cross-chec

feeder problem when conductin

RSRP (Reference Signal Receive P

-70 dBm to -90 dBm

-91 dBm to -110 dBm →

-110 dBm to -130 dBm →

SINR (Signal to Interference+No 16 dB to 30 dB → Goo

1 dB to 15 dB → Norm

-10 dB to 0 dB → Bad

Radio Parameter @ GENEX Probe…cont

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Modulation Coding Scheme

64 QAM → Good

16 QAM → Normal

QPSK → Bad

Neighboring cell Downlink EARFCN

@

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Signal quality overview plot (Serving PCI)

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RNO-1

Signal quality overview plot (RSRP)

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4G LTE –

Drivetest and Covera

Signal quality overview plot (SINR)

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4G LTE –


Signal quality overview plot (DL Throughput)

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4G LTE –


Signal quality overview plot (UL Throughput)

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4G LTE –


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03-150323115803-conversion-gate01 (1)

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