Network Scanner v2

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Network Scanner 1/16 Technical Information R&S® Network Scanner

Transcript of Network Scanner v2

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Technical Information

R&S® Network Scanner

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1. Network Scanner

In mobile radio networks, it must be possible to obtain accurate information about the

receiving conditions of a mobile unit at any place and any time. The radio network analyzer

from Rohde & Schwarz provides outstanding performance independent of standards in a

small unit. It meets the demands of network operators, regulatory authorities, railway carriers

and infrastructure suppliers.

The measurement data is collected and statistically evaluated by the R&S® ROMES software

from Rohde & Schwarz.

1.1 The necessaries

• Measurement speed and accuracy are considerably higher than what mobile phones

can deliver in order to represent the real physical nature

• Mobile phones can only “see” what the base station tells them to see

o Hidden neighborhoods

o Pilot pollution and interference causes are not detectable

• Limited channels/carriers (one carrier per mobile and SIM card)

• Layer 1 and layer 2 decoding for better troubleshooting

• Spectrum analysis provides detection of external interferences

• No SIM card identification is required

o No costs

o No capacity is allocated

• Failure of a mobile phone leads to data loss

• Measurements are independent of mobile chipsets and provide unbiased reference data

• Higher level and time accuracy compared to mobile phone-based measurements

o Calibration is possible

• Use of only one unit for different networks and applications

• Cheaper compared to many dedicated units

1.2 Features

General data

• Frequency range: 80 MHz to 3 GHz

• Bandwidth: 4 MHz

• Resolution bandwidth: 10 kHz

• FireWire IEEE 1394 interface

• GPS PPS high-precision synchronization

• Low-power consumption, typ. 8 W

• Wide-range power supply 9 V to 18 V DC

• Handy, portable and compact solution: 150 mm wide x 80 mm tall x 170 mm deep,

and just 1.5 kg

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WCDMA/CDMA2000® PN scanner

• All WCDMA bands (I to IX)/all CDMA frequencies

• BCH demodulation and decoding of all SIBs (WCDMA)

• 2500 dynamic rake receivers

• Sensitivity up to -122 dBm

• Dynamic range up to 29 dB

GSM network scanner

• All GSM bands

• Sensitivity up to -112 dBm

• Interference analysis (C/I, type, source, location)

• Decoding of layer 3 “system information types 1 to 4” (e.g. ARFCN, NCC, BCC, CI,

LAC, MNC, MCC)

CW power

• Frequency range from 80 MHz to 3 GHz

• Time or distance trigger (sampling rate: 1.6 ms in time triggered mode, 2 ms in

distance triggered mode for single frequency mode)

• Measurement in accordance with Lee criterion

• Multitechnology & multiband

• Channel power (average, peak, RMS)

• Applicable for all GSM, WCDMA, CDMA, TETRA, WiMAX, broadcast and TV

bands

WiMAX / LTE scanner

• User-definable input frequency range from 30 MHz to 6 GHz

• Two independent RF and signal processing paths, each with a bandwidth of 20 MHz

• Integrated preselection for high intermodulation suppression while dynamic range is

high

• Support WiMAX IEEE 802.16e measurements together with the R&S®ROMES drive

test software (R&S®TSMW-K28)

• Support LTE measurement

• I/Q baseband measurement with Gigabit interface (R&S®TSMW-K1)

• Future-ready software-defined architecture

• Integrated GPS

1.3 Benefits

• Easy, time-saving and high-precision coverage measurements and network

optimization

• Outstanding measurement performance (For comparison: WCDMA mobile: approx.

1000 ms/measurement)

o WCDMA: up to 3 ms/measurement (PN scan)

o CDMA: up to 100 ms/measurement (PN scan)

o GSM: up to 12.5 ms/channel (demodulation of sys. types)

o CW: up to 1.6 ms/measurement (20 channels parallel)

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• One hardware platform for different technologies (GSM, CDMA2000®, WCDMA,

CW-Power 80 MHz – 3 GHz, WiMAX, LTE), Frequency range: 80 MHz up to 3/6

GHz

• Easy means of competitive analysis without SIM card identification, e.g. for four or

more network operators (benchmarking) in one drive

o Twelve carriers for PN scanning simultaneously possible

• Indication of interference/pilot pollution problems

• Base station/Cell troubleshooting and maintenance

• Site finder for new base stations (test transmitter required)

• Ideal for high-speed measurements on railways, for example

o All 19 GSM-R channels simultaneously at 180 km/h with 10 cm measurement

distance

• Internal distance trigger (CW power) for uniform coverage measurements

• RF tracking as slave during CW power measurements

• Indoor measurements possible: backpack solution

• EMF measurement with the R&S® TSMU-H

1.4 Test Mobile vs. Scanner

Test Mobile Scanner Frequency limitation - ++

Band limitation O ++

Operator limitation - ++

Operating charges - ++

QoS ++ O

End-to-end ++ O

Coverage + ++

Accuracy - ++

Speed - ++

1.5 The Solutions

1.5.1 Basic configuration

• Rohde & Schwarz receiver (e.g. R&S® TSMU)

• GPS

• Notebook

• R&S® ROMES software

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1.5.2 Indoor configuration

• R&S® TSMx / R&S® TSM-DVB receiver

• Battery pack and charger

• 2 mobile phones

• GPS

• Notebook

• R&S® ROMES software

• Backpack

1.5.3 Portable configuration

• R&S® TSMx receiver

• Up to 4 mobile phones

• GPS

• Notebook

• R&S® ROMES software

• Robust suitcase

1.5.4 Vehicle-mounted configuration

• Rohde & Schwarz receiver

• Uninterruptible power supply system with separate battery

• Up to 16 mobile phones

• GPS

• R&S® ROMES software

• 19" rackmount

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2. Applications

2.1 Transmitter Scan

The GSM Network Scanner allows measurement and demodulation on multiple GSM

bands in parallel. Selected channels or bands will be defined in the measurement

configuration, together with the scanning speed

The NWS Transmitter Scan View shows the currently detected signals with:

· ARFCN

· Code Power of BCCH

· BSIC

· CI

· LAC

· MNC

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· MCC

· T(MEAS) = Total Time since first reception of signal

· T (TDMA) = TDMA Frame Offset

· Frame Number FN

This view is continuously updated with the measurement data and can be configured in

many ways for optimum display of the signals.

2.2 Benchmarking

The GSM NWS Top N View displays the properties of the signals from the base

transceiver stations that are elements of the Top N Pools defined in the driver configuration

menu. A Top N Pool contains up to N BSICs with specific characteristics providing the

strongest synchronization channel P(SCH) level at a given position and time

2.3 2G/3G BCH Demodulation & BTS Position Estimation

Communication with seamless coverage and without interference, reliable data

transmission at an acceptable speed – these and many other quality criteria are decisive for the

success of a mobile radio network on the market. To enable network operators to provide the

required quality -- and thus be commercially successful. Rohde & Schwarz offers with it’s

coverage systems professional solutions for all state of the art technologies. The Software

ROMES controls the devices for the data acquisition and is used for data evaluation.

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2.3.1 Features of 2G/3G BCH Demodulation and BTS Position Estimation

• Detailed analysis of System Information S1 – S19 without a test mobile

• No SIM card is necessary for authorization to network

• Parallel measurement in appropriate and competitive networks

• Fast scan with up to 50 meas. / sec for a complete scan

• Usable for all GSM and UMTS bands

• Automatic BTS localization

• Creation and export of BTS list

• On-line control of measurement activities by ROMES

• Evaluation by Replay function of ROMES

2.3.2 Benefits

2.3.2.1 Benefits of 2G/3G Demodulator

2G/3G network analysis without using a test mobile

• Independent of test mobile with different net performance

• Reference system with high performance

• No SIM card needed

• Easy benchmark tests of net performance e.g. all bands WCDMA, CDMA,

CDMA2000, GSM

• Only one Drive Test Scanner TSMQ for parallel measurements in all bands needed

e.g. for 5 operators 5 test mobiles would be needed

• Small, compact test system for mobile applications

• Easy to operate – time saving

2.3.2.1 Benefits of BTS Position Estimation

Computes the geographical coordinates of GSM Transmitter stations by a special algorithm

using BCH Demodulation data and timing information.

• Fast and easy creation of BTS list in unknown area

• Detection and localization of interfering Base Stations

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• Just driving

• Automatic BTS list generation

• Marginal equipment costs (just Scanner and GPS is required)

Map display of all decoded and localized GSM transmitters

Map display of localized GSM transmitters from network operator A

Map display of localized GSM transmitters from network operator B

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Map display of localized GSM transmitters from network operator C

2.4 Interference Analysis

Interference in Mobile Networks is most common and can only hardly be analyzed

with regular network engineering measures. The continuous installation and reconfiguration

of base stations – always under time pressure – is a major challenge for Frequency Planning.

Very often does the missing synchronization between Network Planning and Network

Operation lead to inconsistent data and parameter settings for the base stations. Other

factors for interference are undue frequency or power settings, including one’s own or

those of neighboring countries. Close to borders, interference gains an even higher mportance.

Interference in Mobile Networks is either Co-Channel, Adjacent Channel or Traffic

Channel Interference, or external sources like spurious emissions or intermodulation.

Function of the GSM Interference Analyzer: The defined ARFCN channels to

participate in the analysis are scanned with up to 80 channels per second, including Cell

Identity (CI) demodulation. All measured date is referenced with time stamp and

geographic position. No SIM card needs to be used for this measurement, as the scanner

works only passively. In case there are more than one BCCH on one ARFCN, those will be

identified and displayed as different co-channel signals by their CI.

Interference Analysis is done in 5 steps:

1. The Test Mobile makes an endless call. RxLev, RxQual and, if available, C/I from the

mobile are continuously monitored.

2. If one or more thresholds of those are exceeded, the analyzer suspects an interference

situation and triggers the analysis process.

3. Determination of potential interferers by comparison of the current SC with all entries in

the Base Station Database comprising the same or an adjacent ARFCN, that lie in a certain

radius around the measurement location (e.g. 35 km).

4. Synchronization of the network scanner measurement data and the Base Station

Database information, by comparison of measured CI and the listed CIs from the database.

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5. List display of the results. The Frequency Reuse Event List View list all events during

interference analysis. Timestamp, details of the interference event, description of the

serving cell, Channel / Frequency Hopping, C/I Value from the Test Mobile (if

available), and the very Test Mobile triggering the interference analysis.

2.5 2G/3G Handover & Neighborhood Analyzer

This system compares the configured neighbours as seen by a mobile and the GSM

BTS database (the planned situation) with the TopN calculations of the GSM NWS results

(the measured situation). Normally it will be expected that the serving cell and the configured

neighbours shall be in the TopN list of strongest stations.

Any differences (missing neighbours) can be used for optimization of the neighbour

configuration.

The GSM Neighbourhood Analyser is the internal components which uses information from

three sources:

• Measurement results from the GSM Network Scanner

• Measurement results from GSM test mobiles in dedicated mode

• Configuration information from the GSM BTS database

The results of the analysis are shown in three areas:

1. Upper events list showing missing neighbours as pairs (MN – SC)

This list shows two types of events:

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a) symbolized by two towers is where a neighbour cell is in the top N, which is not a

neighbour of another top N member (normally all TopN members should be mutually

neighbours)

b) symbolized by a tower and a mobile is where there is a top N member which is not a

neighbour of the serving cell as defined by the mobile. Each event condition can happen

several times, each time the length and duration is recorded and shown in sub items of the

main entry. The main entry shows the sum of the sub items.

2. Lower left Serving Cell list

This list shows a statistic how many of the configured neighbours of a serving cell where

actually measured by the GSM NWS and what was the shortest distance to the serving cell.

The list is sorted from the worst case (red) to the best case (green).

3. Lower right neighbours list

This list is valid for the selected serving cell on the left. It shows in detail the measurement

results for the neighbours. For P min und P max also the [power] of the serving cell at the

location of the min or max measurement is displayed.

2.5 3G Network Tuning with Network Scanner

System Configuration sample

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The basic measurements of scanner are:

• CPICH_RSCP (received signal code power)

• CPICH_Ec/No (received energy per chip divided by the power density in the band)

• RSSI (received signal strength indicator)

The scanner will be used to achieve:

• Crossed feeder issues (DL)

• Coverage verification

• Interference problems (overshooting cell, pilot pollution)

• Missing neighbours

Coverage Verification. Network scanner with high sensitive receiver is used to detect the

coverage area. It will measure the P-CPICH RSCP and P-CPICH Ec/No to figure out the

coverage.

Coverage level RSCP [dBm] Ec/N0 [dB]

Sufficient RSCP ≥ −100 Ec/N0 ≥ −14

Poor −115 ≤ RSCP <−100 −16 ≤ Ec/N0 < −14

No coverage RSCP < −115 Ec/N0 <−16

Best server signal strength (RSCP)

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Pilot Ec/No Measurements

Interference. By correlating low Ec/No with high RSCP (RSCP > -90 dBm AND Ec/No < -9

dB), areas with high interference can be detected

Potential

Inteference

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Primary Common Pilot Channel (P-CPICH) – OVERSHOOTING

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Primary Common Pilot Channel (P-CPICH) – PILOT POLLUTION: High CPICH

reception levels from many Cells, (more than MAX_ACTIVE_SET)

size

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