Welcome to all of you to world of “TELECOM "by
Welcome to all of you to world of “TELECOM "by • • • • • •
Detailed Tropic discussed in this chapter CW Testing Model Tuning Antenna 1. Isotropic Antenna 2. Dipole Antenna
• • • • • • •
RF Planning 1. Coverage planning 2. Capacity planning 3. Highway Planning 4. City planning Planning Tool Asset Planning Tool
Welcome to all of you to world of “TELECOM "by • • • • • •
Detailed Tropic discussed in this chapter CW Testing Model Tuning Antenna 1. Isotropic Antenna 2. Dipole Antenna
• • • • • • •
RF Planning 1. Coverage planning 2. Capacity planning 3. Highway Planning 4. City planning Planning Tool Asset Planning Tool
• • • • • • • • • • •
Please introduce yourself as per guidelines below: Name Qualification Professional Experience in years/months (if applicable) Name of the previous company (if applicable) Tenure in previous previous company company (if applicable) Name of the Institute/University Year of passing What is your AIM in life Expectations from this company Expectations from this course
• Decorum of the course to be maintained by: • Keeping your mobiles in Switched-off or Silent mode. • Doing one discussion at a time. • Following the timings strictly as per schedule for Breaks. • Making the course interactive by asking questions and by giving suggestions.
INTRODUCTION TO RF PLANNING
Designing a cellular system - particularly one that incorporates both Macro cellular and Microcellular networks is a delicate balancing exercise.
The goal is to achieve optimum use of resources and maximum revenue potential whilst maintaining a high level of system quality.
Full consideration must also be given to cost and spectrum allocation limitations.
INTRODUCTION TO RF PLANNING •
A properly planned system should allow capacity to be added economically when traffic demand increases.
•
As every urban environment is different, so is every macro cell and micro cell network. Hence accurate planning is essential in order to ensure that the system will provide both the increased capacity and the improvement in network quality where required, especially when deploying Microcellular systems.
INTRODUCTION TO RF PLANNING
RF planning plays a critical role in the Cellular design process.
By doing a proper RF Planning by keeping the future growth plan in mind we can reduce a lot of problems that we may encounter in the future and also reduce substantially the cost of optimization.
On the other hand a poorly planned network not only leads to many Network problems but it also increases the optimization costs and still may not ensure the desired quality.
INTRODUCTION TO RF PLANNING • The high level life cycle of the RF network planning process can be summarised as follows :• To help the operator to identify their RF design requirement • Optional
Comparative Analysis
• Discuss and agree RF design parameters, assumptions and objectives with the customer
RF Design requirement
• Coverage requirement • Traffic requirement • Various level of design (ROM to detail RF design)
RF Design
Site Realization
RF Design Implementation
• Issuing of search ring • Cand. assessment • Site survey, design, approval • Drive test (optional)
• • • •
Frequency plan Neighbour list RF OMC data Optimisation
INTRODUCTION TO RF PLANNING • This is an optional step • This is intended to : – Help an existing operator in building/expanding their network – Help a new operator in identifying their RF network requirement, e.g. where their network should be built •
For the comparative analysis, we would need to : – Identify all network that are competitors to the customer – Design drive routes that take in the high density traffic areas of interest – Include areas where the customer has no or poor service and the competitors have service
INTRODUCTION TO RF PLANNING • The result of the analysis should include :•
For an existing operator – All problems encountered in the customer‟s network – All areas where the customer has no service and a competitor does – Recommendations for solving any coverage and quality problems
•
For a new operator – Strengths and weaknesses in the competitors network – Problem encountered in the competitors network
INTRODUCTION TO RF PLANNING • The RF design inputs can be divided into : – Coverage requirements • Target coverage areas • Service types for the target coverage areas. These should be marked geographically • Coverage area probability • Penetration Loss of buildings and in-cars – Capacity requirements • Erlang per subscriber during the busy hour • Quality of service for the air interface, in terms GoS • Network capacity – Growth plan - Coverage and Capacity
INTRODUCTION TO RF PLANNING – Available spectrum and frequency usage restriction, if any – List of available, existing and/or friendly sites that should be included in the RF design – Limitation of the quantity of sites and radios, if any – Quality of Network (C/I values) – Related network features (FH, DTX, etc.)
INTRODUCTION TO RF PLANNING
RF Network Design • There are 2 parts to the RF network design to meet the : – Capacity requirement – Coverage requirement •
For the RF Coverage Design CW Drive Testing
Propagation Model
Digitized Databases
RF Coverage Design
Customer Requirements
Link Budget
TOOLS USED FOR RF PLANNING
Network Planning Tool
CW Propagation Tool
DRIVE TEST FOR C.W. TESTING
DRIVE TEST FOR C.W. TESTING INTRODUCTION Drive test types
Predesign drive test
•
Post design drive test
Predesign drive test for measurement integration
• This is at beginning of design when no site has been built or even selected. All test sites are temporary.
DRIVE TEST FOR C.W. TESTING
•
Drive test is performed mostly for characterization of propagation and fading effects in the channel. The object is to collect field data to optimize and adjust the prediction model for preliminary simulations.
•
Post design drive test for site verification / optimization
•
Drive test is performed to verify if they meet the coverage objectives.
•
Overlaps are checked for hand-offs.
DRIVE TEST FOR C.W. TESTING INTRODUCTION
In field measurement we have to collect variations due to propagation and slow fading.
The received signals are typically sampled and averaged over spatial windows called bins.
There are several sampling issues to be considered like Sampling rate Averaging window Number of bins to be measured
DRIVE TEST FOR C.W. TESTING SAMPLING CRITEREA
When measuring the RF signal strength certain sampling criteria must be met to eliminate the short-term fading components from the long-term component ( I.e. log normal fading )
The RF signal strength measurements must be taken over a radio path or mobile path distance interval of 40, where is the wavelength of the RF signal.
If the distance interval is too short, the short term variation cannot be smoothed out and will affect the local mean.
DRIVE TEST FOR C.W. TESTING
•
If the distance interval is too long, the averaged output cannot represent the local mean since it washes out the detailed signal changes due to the terrain variations.
• The number of RF measurements taken within the 40 distance should be greater than 50. •
Depending on the speed of the vehicle during the drive test, the sampling interval in time is selected.
•
Measurements have to be stopped whenever the vehicle is not moving.
DRIVE TEST FOR C.W. TESTING SAMPLING CRITEREA •
If
f = 1900MHZ, then =
3 * 10 8 / 1900 * 10 6
= 0.158 m 40 =
40 * 0.158
= 6.32 m
50 measurements must be recorded every 6.32m or 1 measurement every 0.1264m
The conversion from sampling distance to mobile velocity can be done as follows minimum sampling rate ( per second ) = v / (0.1264 m/sample)
If velocity of vehicle is 50 kph then Sampling rate( per second ) = (50000/ 3600) / 0.1264 = 110 samples / sec
TEMS kit cannot be used for this purpose as it can report RF signal strength measurements at a maximum rate of 1 sample per second
DRIVE TEST FOR C.W. TESTING WINDOW SIZE •
•
•
In field measurements the interest is on local averages of received signals.
The size of averaging window have to be small enough to capture slow variations due to shadowing and large enough to average out the fast variations due to multipath. A typical range is 20 to 1500 m.
•
The bin size is typically selected in 40 to 1500m, i.e. all measurements in this size square are averaged to one value.
•
Normally the post processing tool takes care of averaging the collected data over different bins.
DRIVE TEST FOR C.W. TESTING NUMBER OF BINS Bin
• The predicted and measured signal strengths for all bins within the drive route is compared and the best set of correction factors to minimize the prediction errors is determined. •
All the bins within the coverage area cannot be drive tested. So a large enough sample set should be considered.
• The more the number of bins, the larger the confidence level of results. •
Generally for acceptable confidence at least 300 to 400 bins have to be considered.
DRIVE TEST FOR C.W. TESTING PROPAGATION KIT The propagation test kit consists of – Test transmitter. – Antenna ( generally Omni ). – Receiver to scan the RSS (Received signal levels). The receiver scanning rate should be settable so that it satisfies Lee‟s law. – A laptop to collect data. – A GPS to get latitude and longitude. – Cables and accessories. – Wattmeter to check VSWR. Receiver Antenna Transmit Antenna
Transmitter
GPS Antenna
RECEIVER LAPTOP
DRIVE TEST FOR C.W. TESTING The propagation test kit consists of
DRIVE TEST FOR C.W. TESTING TRANSMITTER SETUP •
If the propagation test is being done for model tuning to produce a generic model for macro cells, then a high point in the particular area has to be selected.
•
The transmitter and the transmit antenna will be placed at this point (say the roof of the building ).
•
The transmit antenna is connected to the transmitter via a RF cable.
•
Check to see that the cable is connected properly and tight.
•
Loosely connected or faulty cable can increase the VSWR.
•
A test frequency has to selected from the frequency band allocated to the operator. Set the transmitter to this test frequency.
TEST TRANSMITTER
DRIVE TEST FOR C.W. TESTING TEST SITE SELECTION
Site selection is based on a number of criteria. It may not be possible to satisfy all these criteria at the same time, but it is important to select the best sites available.
Drive test sites should be selected to give a good representative sample of the system coverage area. The exact number of sites required will depend on the size of the system coverage area and the variability of the characteristics of the coverage area.
DRIVE TEST FOR C.W. TESTING
•
All terrain and clutter types in the area should be represented in the drive test data for proper prediction tuning.
– Typical terrain types are: Flat, Rolling Hills, Large Hills, Mountains – Typical clutter types are: Water, Open Land, Forest, Commercial / Industrial, Low Density Urban, Medium Density Urban, High Density Urban, City Center, Airport.
•
City maps, topographical maps and aerial photographs can be useful in determining the terrain and clutter types for an area. It may also be necessary to drive the area and observe building types and density.
DRIVE TEST FOR C.W. TESTING TEST SITE SELECTION Site Availability
Test sites must be available for use during the drive test.
The site owner/supervisor should approve access to the site for as long as needed to complete the testing. This may involve multiple visits to the site, possibly on short notice.
Test sites must also be physically accessible to allow setup of the transmitter equipment and mounting of the antenna. For this reason building top sites are preferred to tower sites.
DRIVE TEST FOR C.W. TESTING
Site Visit
•
Each site selected should be visited before testing to verify that is suitable for use.
• The inspection should be done by the same people who will be doing the site setup for the actual drive test. Familiarity with the site should speed up the site setup during the drive test.
DRIVE TEST FOR C.W. TESTING BUILDING SITE SELECTION
•
When inspecting a building site the rooftop should be checked for any obstructions that would interfere with signal propagation. This could include objects on the rooftop itself or other nearby buildings or structures.
• The antenna location should be selected and a sketch of the rooftop made to identify this location relative to other objects nearby. •
Photographs should be taken of the location where the antenna will be mounted and in all directions looking away from the site.
DRIVE TEST FOR C.W. TESTING BUILDING SITE SELECTION
DRIVE TEST FOR C.W. TESTING TOWER SITE SELECTION
When inspecting a tower site the best location to mount the antenna to the tower must be deter-mined.
This should be selected such that the tower doesn‟t interfere with the propagation pattern of the transmit antenna. This will usually require that the antenna be above the tower or on an arm extending from the side of the tower.
The area around the tower should be checked for any obstructions that would interfere with signal propagation.
DRIVE TEST FOR C.W. TESTING TEMPORARY STRUCTURE
•
Generally cranes are used for temporary structure.
•
When cranes are used power generators have to be arranged in advance.
• The location should be selected such that the antenna will be above any nearby obstacles.
DRIVE TEST FOR C.W. TESTING TEMPORARY STRUCTURE
DRIVE TEST FOR C.W. TESTING DRIVE TEST PLAN
Each drive route should be marked on a detailed road map showing the exact route to be driven.
These maps should be used during the actual drive for navigation of the test vehicle.
They can also be used during the drive test
DRIVE TEST FOR C.W. TESTING
•
verification to check that the positioning information in the drive test file is correct.
•
A separate map should be prepared for each route.
•
Both line of site (LOS) and non-LOS points have to be included in the drive test.
DRIVE TEST FOR C.W. TESTING
• The data collected should represent typical coverage scenarios.
•
In urban area the effect of street orientations have to be considered.
• The selection of drive test route should be based on the terrain variations, Major highways and throughfares, potential shadowing areas and handoff region.
DRIVE TEST FOR C.W. TESTING DRIVE TEST PROCEDURE • The actual dive test must be performed carefully to insure that the data collected is accurate.
•
It is important that all equipment used be tested and all setup information be recorded.
•
If any of the procedures are not followed or any of the data is not properly recorded then the drive test data will not be usable and the drive will have to be repeated.
DRIVE TEST FOR C.W. TESTING
•
Engineer should study the drive test plan ahead of time and highlight the intended drive test routes.
•
For each drive test a team of two people should get involved.
• The measurement process should be stopped the car stops ( eg near traffic lights) or whenever the sampling and measurements look suspect.
DRIVE TEST FOR C.W. TESTING DRIVE TEST OUTPUT Lat
Long
RSSI
Freq
X1
Y1
M1
F
X2
Y2
M2
F
X3
Y3
M3
F
The result of drive test is a collection of data files which has lat, long, Received Signal Strength Indicator (RSSI) at that point and the frequency.
The location information ( lat, long ) is used by the post processing tools as a reference of correlation between the measured vs. predicted signal levels for measurement integration.
This file has to be transferred onto the planning tool either by a floppy or by data transfer using LAN.
DRIVE TEST FOR C.W. TESTING DRIVE TESTOUTPUT
Model Tunning
Model Tunning •Model Tuning On Asset version 6.1
Model Tunning Model Tunning
Models are used to predict path loss.
Different models are used for different purpose. Eg:- Rural Macro-cell -Okumura hata model, Micro cells - Ray tracing
Models have to be tuned using data collected by drive testing.
Good propagation tool + Sound engineering ingenuity = Sound RF design.
Some of the popular prediction models are Okumura hata, Walfisch Ikegemi, COST231, Ray tracing etc.
Model Tunning Okumura Hata Model
This is used for Macro cell modeling.
It has become environments.
It is best applicable for cell ranges of 5 to 20 kms.
the
most
popular
propagation
model
for
mobile
Model Tunning •
Below a range of 1 km it becomes very unreliable since obstacles in the close vicinity of receiver and transmitter become the dominant scattering influences which are not taken into account in the formula.
•
Path loss = K1 + K2log(d) + K3log(Heff) + K4 * Diff + K5log(Heff)log(d) + K6log(Hmeff) +K7log(f) + Kmorphology
Model Tunning •
K1 - 1Km intercept value. Upto this point model assumes free space loss
•
K2 - Slope value
•
K3 - Effective height coefficient
•
K4 - Coefficient for diffraction calculation
•
K5 - Hata model multiplier
•
K6 - Multiplier for mobile height
•
K7 - factor for frequency
Model Tunning •
model has four main parameters: – Building separation (in meters) (b) : It is the distance between the centre of two buildings.
– Average building height (h) : This is the average height of all buildings in the cell’s coverage area.
– Road width (w) – Road orientation angle ( )
Model Tunning
d
h w b
Walfish Ikegami Model
Model Tunning MODEL TUNING
Propagation models use clutter and terrain data to predict cell coverage at a site. However usually the terrain and clutter data available from the maps are not perfect.
This means that the actual cell coverage could be different from the predicted cell coverage. This could in turn result in wrong cell designing.
To avoid this model tuning is done.
Model Tunning •
In model tuning data collected from the propagation test is loaded on the planning tool.
• This data represents the real life condition cell coverage.
• The prediction for that cell is then done using the same conditions as were for the propagation tests (i.e. using the same antenna type, same height of the antenna at the site, same downtilts, same transmit power etc.
Model Tunning MODEL TUNING •
Ideally both the propagation test cell coverage and the predicted cell coverage should match.
•
If they match then the model does not require to be tuned.
•
If the models do not match then the certain parameters in the propagation model equation are altered so that they both match.
Model Tunning •
Once both the cell coverage match the model is then said to be tuned.
•
Now the actual antenna type, height of antenna, transmit power are used and prediction done.
• This prediction can then be assumed to be correct.
•
Cell designing is then done using this prediction.
Model Tunning MODEL TUNING
Ideally model tuning needs to be done for all the sites.
However in many cases , the Network is divided into different clutter types (around 7 to 8) (e.g. urban, dense urban, semi urban, rural etc.) and models are tuned for each clutter types.
The sites are then categorized in these clutter types and then fitted in the model tuned for that clutter type.
This method though not perfect is widely accepted and saves lot of time and money for the operator.
You must have an existing project with map data and with CW sites. In the below mentioned slide there are total three sites for tuning.
of Omni antenna.
Make the Feeder cable from Equipment > Click on Feeder
g
c c on
e spec c pro ec > c c New Feeder
ve ee er ame ay n art and click on close
Update the site database for antenna , model and feeder type
Making a reference Model From Configuration > Propagation Model
Propagation Model Window will pop up > click Add > select any reference model(Say standard Macrocell 3) > Click Add
ve e propaga on mo e name ay 1900)> click View/Edit Model Parameter
e re a ve n orma on say Frequency) in general tab
Fill K-values information from user guide
oose
ec ve an enna e g (say Relative)
a gor
m
oose
rac on ca cu a on (say Epstein Peterson)
e o
Initial through clutter losses and clutter offsets will be 0. No need to fill the value in this tab
Importing the CW Drive test file From Tools > Click Measurements
Measurement toolbox will open > Click “Add” in cell associate measurement > Browse Header(.hd) file > click open
mpor ng o
r ve e w minutes
a e ew
If header file and site database information are same then loading will ask for the association of drive data with cell > Click OK
Click on Load Associated
Similarly Import the other drive (Signia) files
Model Analysis Select the particular measurements>click Individual > Model Analysis Tool Box will pop up > In Model tab, Fill the required information > Select the Model
In filter tab > Give distance filtering > Rx Level Filtering > Clutter filtering > Polygon Filtering
For Polygon Filtering you must have measurement analysis > Check Measurement Signal > View the drive data in 2D view with sites > Click on Create new vector from 2D menu > Give vector name (Say 1900)> Select polygon shape > make polygon for the bad drive samples > Save all vectors
Now if you want to use polygon filtering > Check Use Exclusion Polygons box > Click Select polygons > check the specific polygon > click on Apply
o ygon e ec e w s ow you e no o Exclusion polygons > click OK
Model Analysis box will pop up > Select all the measurement > click Composite. This will give combine values. You can also do the analysis for individual drive data
After the completion of composite analysis this will give you the values as slide is showing
You can also view the analysis report from here > Click View Report > Analysis will run
After the completion of analysis an option box will pop up > choose the desired options > Click OK
Analysis report will generate (See the below mentioned specimen) In this case You can see that mean error & Std. Dev is not matching with exact criteria.Actually mean value should be 0 and Std. Dev should be less or equal to 8
Analysis report will generate (See the below mentioned specimen) In this case You can see that mean error & Std. Dev is not matching with exact criteria. Actually mean value should be 0 and Std. Dev should be less or equal to 8. After tuning the value of K1, K2 and K7 we will get the exact report as given
Auto Tuning After Analysis you need to do the tuning for improved results. Select the measurements > Click Auto Tune
Initialization of Auto tuning will take few minutes
Model Calibration Utility box will pop up. This will show you the reference model K-value. Also at the moment Through clutter losses are 0. You can see the same from; Clutter > View/set Through clutter parameters
. you can fix or open the clutter losses values. In the below mentioned slide all clutter loss values are open.
Before going to Auto tuning you can also fix or open the Kvalues. For eg. In the below mentioned slide K2 is open while others are fix. For Auto Tuning Go to Tools> Auto Tune
Auto Tuning will take Few Minutes time
Auto Tuning will give you new k and clutter values. If you want to apply the new values go to Tools > Apply New parameters
You also can see the new clutter losses values
This will complete the Auto Tuning Process. Now From File > Click Exit
See the tuned values from Configuration >Propagation Model> Select Specific Model > View/Edit model Parameters > Path loss tab and then > Clutter tab
Antenna
BASIC INTRODUCTION TO ANTENNA What is antenna?
•
An antenna is the converter between cable bounded electromagnetic waves and free space waves. •
ANTENNA INSTALLATION
Antenna installation configurations depend on the operators preferences.
It is important to keep sufficient decoupling distances between antennas.
If TX and RX direction use separated antennas, it is advisable to keep a horizontal separation between the antennas in order to reduce the TX signal power at the RX input stages.
Antennas for GSM System
Antennas for GSM System
Antennas for GSM System
• Base station antenna specification
and meanings • Antenna types and trends
(Technical Data)
Blah blah blah
bl ah
Electrical properties
Mechanical properties
•
Operation Frequency Band
•
Size
•
Input impedance
•
Weight
•
VSWR
•
Radome material
•
Polarization
•
Appearance and color
•
Gain
•
Working temperature
•
Radiation Pattern
•
Storage termperature
•
Horizontal/Vertical beamwidth
•
Windload
•
Downtilt
•
Connector types
•
Front/back ratio
•
Package Size
•
Sidelobe suppression and null filling
•
Lightening
•
Power capability
•
3rd order Intermodulation
•
Insulation
Electrical properties
Dipoles Wavelength 1/4 Wavelength 1/2 Wavelength 1/4 Wavelength 1/2 Wavelength Dipole
1800MHz
166mm
900MHz
333mm
1
Multiple dipole matrix
dipole
接收功率(received power)：1mW
G A I N =
Received power ：4 mW
10log(4mW/1mW) = 6dBd
Antenna (Overlook
Omnidirectional array” Received power ：1mW
Sector antenna” Received power ：8mW
Gain=10log(8mW/1mW) = 9dBi
Frequency Range • • • •
Optimum 1/2 wavelength for dipole at 925MHz
at 890 MHz
at 960 MHz Antenna Dipole
B A N D W I D T H =
960 - 890 = 70MHz
Impedance •
50
Antenna Cable 50 ohms 50 ohms
VSWR
Forward: 10W 50 ohms Backward: 0.5W
Return Loss
80 ohms
10log(10/0.5) = 13dB
VSWR (Voltage Standing Wave Ratio)
9.5 W
•
1.5
•
=(VSWR-1)/(VSWR+1)
•
RL=-20lg
Polarization
Vertical
+ 45degree slant
Horizontal
- 45degree slant
V/H (Vertical/Horizontal)
Slant (+/- 45
)
•
Linear, vertical
•
45
dual linear 45 slant
dBd and dBi
Ideal radiating dot source (lossless radiator) 2.15dB
eg: Dipole
0dBd = 2.15dBi
Pattern :-
Beamwidth
3dB Beamwidth
10dB Beamwidth Peak - 3dB
60
(eg)
Peak
Peak - 3dB
Peak - 10dB 120 (eg)
Peak
Peak - 10dB
3dB 3dB Beam width Horizontal •
Directional Antenna：65°/90°/105°/120 °Omni：360°
3dB 3dB Beam width Horizontal
Directional：
Omni-directional ：
Down Tilt
•
Mechanical down tilt
•
Fixed electronic down tilt
•
Adjustable electronic down tilt
Demonstration of Electronic Down-tilt
Non down tilt
Electronic downtilt
Mechanical downtilt
(Electronic and mechanical down tilt)
Front to Back Ratio •
Ratio of maximum main lobe to maximum side lobe
Back power
Front power F/B = 10 log(FP/BP)
typically
25dB
Upper Side lobes Suppression & Null Fill
Side lobe
In (dB)
In (dB)
Mechanical properties
Mast
•
Mast diameter 45-90mm
(Antenna Types and Development )
(Antenna Types) By frequency band: GSM900, GSM1800, GSM900/1800 By polarization: Vertical, Horizontal, ±45º linear polarization, circle polarization By pattern:
Omni-directional, directional
By down-tilt:
Non, mechanical, electronic adjustment, remote control
By function:
Transmission, receiving, transceiving
ONE ANTENNA FOR MULTIPLE BANDS
– 870-960MHz and 1710-1880MHz – Extended band option with 806-960MHz – Dual slant
45º polarisation
– 65º horizontal beamwidth – Band independent Teletilt™ control – 17dBi gain in both bands – Diplexed or Non-Diplexed versions
7/8”
MAIN FEEDER
1/2”
JUMPER CABLE
Planning
Coverage Planning Strategies
Coverage Planning Strategies
• The selection of site configurations, antennas and cables is the core of the coverage planning strategy. The right choice will provide cost savings and guarantees smooth network evolution.
3
2 3
4
– 3-sector sites for (sub) urban areas – 2-sector sites for road coverage
7
1 2
3 1 2
4 7
4 7
6
5 4
6
5
7
1
3
4
6
2
7
1
3
4
6
2
5
1
3 5
1
6
2
7
7
Some typical configurations are:
4
6
5
3 5
1
2
•
6
5
• These are not the ultimate solutions, decisions should be based on a careful analysis •
Cell Range and Coverage Area
•
For any site configuration, the cell ranges can be determined given the equipment losses and gains. The site coverage areas can be calculated then and these will lead to the required number of sites for a given coverage region. This makes it possible to estimate the cost, e.g. per km2 , to be used for strategic decisions.
Network Planning Tool:Network Planning Tool:
Planning tool is used to assist engineers in designing and optimizing wireless networks by providing an accurate and reliable prediction of coverage, doing frequency planning automatically, creating neighbor lists etc.
With a database that takes into account data such as terrain, clutter, and antenna radiation patterns, as well as an intuitive graphical interface, the Planning tool gives RF engineers a state-of-the-art tool to:
Design wireless networks
Plan network expansions
Optimize network performance
Diagnose system problems
• The major tools available in the market are Planet, Asset, Net-Act, Cell Cad.
•
Also many vendors have developed Planning tools of their own like Net plan by Motorola, TCPU by Ericsson and so on.
Propagation Test Kit Propagation Test Kit
The propagation test kit consists of
Test transmitter.
Antenna ( generally Omni ).
Receiver to scan the RSS (Received signal levels). The receiver scanning rate should be settable so that it satisfies Lee‟s law.
A laptop to collect data.
A GPS to get latitude and longitude.
Cables and accessories.
Site Master to check VSWR.
•
A single frequency is transmitted a predetermined power level from the candidate site.
• These transmitted power levels are then measured and collected by the Drive test kit. This data is then loaded on the Planning tool and used for tuning models.
•
Commonly Graysons or BVS test kits are used.
RF Network Design COVERAGE PLANNING
Frequency Bands •
GSM-900
•
The term GSM-900 is used for any GSM system which operates in any 900 MHz band.
•
P-GSM-900
P-GSM-900 band is the primary band for GSM-900 Frequency band for primary GSM-900 (P-GSM-900) : 2 x 25 MHz
• •
•
E-GSM-900
In some countries, GSM-900 is allowed to operate in part or in all of the following extension band. E-GSM-900 (Extended GSM-900) band includes the primary band (P-GSM-900) and the extension band :
• •
890 – 915 MHz for MS to BTS (uplink) 935 – 960 MHz for BTS to MS (downlink)
880 – 890 MHz for MS to BTS (uplink) 925 – 935 MHz for BTS to MS (downlink)
Frequency Bands •
R-GSM-900
R-GSM-900 (Railway GSM-900) band includes the primary band (P-GSM900) and the following extension band:
• •
•
GSM-1800
Frequency band: 2 x 75 MHz
• •
876 – 890 MHz for MS to BTS (uplink) 921 – 935 MHz for BTS to MS (downlink)
1710 – 1785 MHz for MS to BTs (uplink) 1805 – 1880 MHz for BTS to MS (downlink)
Carrier Spacing and Channel Structure •
Channel number – the carrier frequency is designated by the absolute radio frequency channel number (ARFCN ). The frequency value of the carrier n in the lower band is called F L (n) while F U (n ) is the corresponding frequency value in the upper band. Frequencies are in MHz
•
P-GSM-900:
F L (n) = 890 + 0.2 n
with 1 < n < 124
F U (n) = F L (n) + 45 •
E-GSM-900:
F L (n) = 890 + 0.2 x n with 1 < n < 124 F L (n) = 890 + 0.2 x (n-1024) with 975 < n < 1024 F U (n) = F L (n) + 45
Coverage, Capacity, and Quality •
Providing coverage is usually considered as the first and most important activity of a new cellular operator. For a while, every network is indeed coverage driven. However, the coverage is not the only thing. It provides the means of service and should meet certain quality measures.
•
The starting point is a set of coverage quality requirements.
To guarantee a good quality in both uplink and downlink direction, the power levels of BTS and MS should be in balance at the edge of a cell. Main output results of the power link budgets are: • Maximum path loss that can be tolerated between the MS and the BTS • Maximum output power level of the BTS transmitter.
Coverage, Capacity, and Quality
These values are calculated as a function of design constraints: • BTS and MS receiver sensitivity levels • MS output power level • Antenna gain • Diversity reception • Losses in combiners, cables, etc.
Coverage, Capacity, and Quality •
The cell ranges are derived with propagation loss formulas such as Okumura-Hata, using inputs of maximum path loss, differences in the operating environments and the quality targets in different cell ranges.
•
The traffic capacity requirements have to be combined with the coverage requirements, by allocating frequencies. This also may have impact on the cell range.
Coverage Planning Strategies •
The selection of site configurations, antennas and cables is the core of the coverage planning strategy. The right choice will provide cost savings and guarantees smooth network evolution.
•
Some typical configurations are:
3-sector sites for (sub)urban areas
2-sector sites for road coverage omni sites for rural areas
Coverage Planning Strategies •
These are not the ultimate solutions, decisions should be based on a careful analysis
•
Cell Range and Coverage Area
•
For any site configuration, the cell ranges can be determined given the equipment losses and gains. The site coverage areas can be calculated then and these will lead to the required number of sites for a given coverage region. This makes it possible to estimate the cost, e.g. per km 2 , to be used for strategic decisions.
Methodology •
Define design rules and parameters
Identify design rules to meet coverage and capacity targets efficiently
Acquire software tools and databases Calibrate propagation models from measurements
Set performance targets
Clear statement of coverage requirements (roll out and quality)
Forecast traffic demand and distribution Test business plan for different roll out scenarios and quality levels
Methodology •
Design nominal plan
Use computer tool to place sites to meet coverage and capacity targets
Verify feasibility of meeting service requirements
Ensure a frequency plan can be made for the design
Estimate equipment requirements and costs
Develop implementation and resource plans (including personnel requirements)
Radio plan will provide input to fixed network planning
Nominal RF Design Link Budget
Propagation model
Coverage requirements
Site radius
Nominal RF Design (coverage)
Traffic requirements
Maximum path loss
Typical site configuration •
•
•
Transmit Power Antenna configuration (type, height, azimuth) Site type (sector, omni)
Traffic requirements
•
•
•
Standard hexagon site layout Friendly, candidate sites Initial site survey inputs
•
•
Recalculate the site radius using the number of sites from the traffic requirement Repeat the nominal RF design
Coverage site count
Traffic site count
Traffic > Cov. Cov. > Traffic
Nominal site count
Methodology
•
Implement cell plan
Identify physical site locations near to nominal or theoretical locations, using search areas .
Modify nominal design as theoretical sites are replaced with physical sites
Modify search areas in accordance with evolving network.
Produce frequency plan
Fixed cluster configuration, can be done manually.
Flexible, based on interference matrix using an automatic tool.
Methodology •
Optimizing the network
•
Expand the network
In line with the roll out requirement
In line with the forecasted traffic level
Improve the coverage quality
Maintain the blocking performance
Fade Margin •
The concept of a fade margin is to reserve extra signal power to overcome potential fading.
•
Assume :
•
The mobile radio system needs an signal level of Pr dBm at the receiver
The maximum likely fade (loss) is calculated to be L(fade) dB
The a received signal level of Pr dBm can be ensured by transmitting enough power for a normal received signal level of (Pr + L(fade)) dBm
Fade Margin •
The fade margin is normally equal to the maximum expected fade or to a smaller value. The value is chosen in such a way that the threshold value is undershot in only a low percentage of time.
•
For this purpose, it is necessary to know the probability density function of the fading.
•
In RF planning, the impact of Rayleigh fading is taken into account by implementing an extra fade margin of 8 dB.
Multipath Propagation •
The radio wave may be reflected, from a hill, a building, a truck, an aeroplane or a discontinuity in the atmosphere. In some cases, the reflected signal is significantly attenuated, while in others almost all the radio energy is reflected and very little absorbed. The result is that not one but many different paths are followed between the transmitter and receiver. This is known as Multipath Propagation
Multipath Propagation
Building
Building Building
Multipath Propagation •
Reflection and multipath propagation can cause positive and negative effects :
Coverage extension Multipath propagation allows radio signal to reach behind hills and buildings and into tunnels The latter effect is known as ducting
Multipath Propagation
Constructive and destructive interference The interference due to multipath propagation manifest itself in the following 3 most important ways:• Random phase shift creates rapid fluctuations in the signal strength known as Rayleigh fading • A delay spread in the received signal causes each symbol to overlap with adjacent symbols : intersymbol interference • Random frequency modulation due to different doppler shifts on different paths
Propagation Modeling
Statistical propagation models
These calculate a median signal for each pixel. The level within this pixel varies about the median in a way that can only be analysed statistically.
Local mean signal levels are distributed around the pixel median with a log-normal probability distribution.
Formulas derived from measurements (e.g. Okumura-Hata).
No obstacles assumed to be close to the BTS antenna.
Deterministic propagation models
Take into account individual buildings and use ray tracing techniques.
Make use of high resolution map data (at least 10m).
Cellular Architecture •
The essential principles of the cellular architectures are :-
Low power transmitters with antenna heights between 20 – 50 50 m Small coverage zones (cells), typical macro cell radius 3 – 30 30 km
Frequency reuse (factor n = 3, 4, 7 ... )
Cell splitting to increase local capacity Micro and Pico cells act as patches for hot spots, tunnels and buildings
•
Balance is to be found between conflicting requirements of :
Coverage
Traffic capacity
Cell Clustering •
Frequency reuse is the core concept of the cellular mobile radio system, given the fact that the number of allowed frequencies is fixed. A frequency can be reused simultaneously in different cells, provided that the cells using the same frequency set are far enough separated so that co-channel interference is kept at an acceptable level most of the time.
•
The total frequency spectrum allocation can be divided into K frequency reuse patterns.
Cell Types •
The 2 main cell types are :
Omni cells : – Coverage is in principle a circle, but in reality a rough pattern
Sector cells : – 2 sectors (e.g. for highways) – 3 sectors
•
Cell Coverage Area
Omni cell (Hexagon) = 2.6 R 2
Sector cell (Hexagon) = 1.96 R 2
Capacity Planning
• Capacity Planning
Capacity Planning •
Capacity can be understood in simplest terms as the number of mobile subscribers a BTS can cater for at a given time.
•
Capacity planning is a very important process in the network rollout as it defines the number of base stations required and their respective capacities.
•
When the sector utilization more then 100% then we will go for a new capacity site in the nearby area.
•
Capacity plans are made in the preplanning phase for initial estimations, as well as later in a detailed manner.
• The number of base stations required in an area comes from the coverage planning, and the number of transceivers required is derived from capacity planning as it is directly associated with the frequency re-use factor.
Capacity Planning • There are three essential parameters required for capacity planning: estimated traffic, average antenna height, and frequency Re-use. – Estimated Traffic:- Traffic in the network is dependent on the user communication rate and user movement in the network. Traffic estimation in the network is given in terms of „erlangs‟. One erlang (1 Erl) is defined as the amount of traffic generated by the user when he or she uses one traffic channel for one hour (this one hour is usually the busy hour of the network) – Average Antenna Height:-The concept of the average antenna height is the basis of the frequency re-use pattern determining capacity calculations in a cellular network. If Antenna Height is low then the covered area is small in an Urban Area, Exactly the opposite is the case in micro cellular environment. – Frequency Re-use:-Frequency re-use basically means how often a frequency can be re-used in the network. If the average number of the transreceivers and the total number of frequencies are known, the frequency re-use factor can be calculated.
Capacity Enhancement Solutions •
Conventional solutions • Cell splitting • Site distance reduction • Interference Reduction Features • New Site Plan • Optimize site properly
•
Extra Spectrum • Extended GSM (10 MHz) • Dual Band/ Dual Mode
•
Microcells (Hotspot, Continuous Layer)
•
Indoor Planning Solutions
City Planning
City Planning Enhancement Solutions •
Conventional solutions – New Site planned – Building Height – Tower Heights
•
Microcells (Hotspot, Continuous Layer)
City Planning • • •
•
The whole land area is divided into three major classes – urban, suburban and rural – based on human-made structures and natural terrains City Is coming under Dense Urban, Urban & Suburban. City Planning requires from the planners is generally a network design that covers 100% of the area. Fulfilling this requirement is usually impossible, so efforts are made design a network that covers all the regions that may generate traffic and to have „holes‟ only in no-traffic zones. The cells (sites) that are constructed in these areas can be classified as outdoor and indoor cells. Outdoor cells can be further classified as macro-cellular, microcellular or pico-cellular. – Macro Cells:- When the base station antennas are placed above the average roof-top level, the cell is a known as a macro-cell. A macro-cell range may vary from a couple of kilometers to 35 km So this concept is used for rural Environment. – Micro Cells:- When the base station antennas are below the average roof-top level, then the cell is known as a micro-cell. The area that can be covered is small, so this concept is applied in Dense urban and urban areas. The range of micro-cells is from a few hundred meters to a couple of kilometers. – Pico Cells:-Pico-cells are defined as the same layer as micro-cells and are usually used for indoor coverage.
Highway Planning •
In Highway planning needs High gain antenna as well as more height.
• This site is coming under clutter type Rural area. • This site is dedicated to highways & act as an backbone network for those Rural area nearby the highway.
RF Planning on Asset Tool
Creating a Project • • •
•
Add a new project from the “Add Project” Give a Project Name & Change the Following parameters as the Requirement: Coordinate System:-The information is vital to locate the mapping information on the earth’s surface. This information is obtained from the data provided. • Map Projection • Ellipsoid • UTM Zone Then Click “Save” button and then press “OK”.
Creating a Project Mapping data directory – Information relating to the location in the directory structure of where the particular type of mapping data is held
– Line (vector) data – Heights – Clutter – Text
Training On Asset Tool
Creating a Project • •
User data directory Directory for storage of the user data types – – – – – –
User Preference Prediction Directory Max Disk Space (Default space 5 GB) Colour Palette (C:\Program Files\AIRCOM International\Enterprise 6.0\Common) Coverage Array Directory User Line Vector (Data)
Creating a Project
• •
Map data extents Defined the overall area that the user will be able to move around in the 2-D view Click on “Calculate” Button.
Asset Planning Tool •
Now Project created & Select the project by click on the “Start” Button.
2D Views Window
3. Add Sites 2. Add BSC 1. Add MSC 4. Moving
•
5. Deleting 6. Moving antenna 7. Re-orientating antenna
For a new project, the user will need to firstly lay down MSCs and BSCs in hierarchical order.
Site Database Window
Site Database
Site Database
•
To get all information regarding a site, Like GSM Antenna Height, type, power, Lat/Long.
Site Database
Site Database
Site Database
Analysis •
Predictions for all sites to be analysed are required before any analysis is done
Analysis - Array Creation
Create Array
Add site to coverage array Display coverag Add cell to e for a coverage cell array
Create/display Array Coverag e Statistic
Display coverage for a site
Cell signal difference
Analysis - Array Creation
Use to analysis network with frequency hopping turn-on
Use to analysis network without frequency hopping turn-on
Analysis - Array Creation
Minimum signal level at which a cell is considered to be a serving cell
Analysis - Array Creation
Analysis - Array Creation
Use when there are predictions of different resolution, to interpolate and smooth all the different resolutions to the selected one to give a continuous resolution coverage array
Settings •
Options - Carriers
Settings •
Option - Group
Settings •
Option - Carrier Layers
Settings •
Option - Cell Layer
Settings •
Option - Cell Layer
Settings •
Coverage Thresholds and Types
Create Array •
Select the filter in Create Array windows & Press “OK”.
•
Then Processing for the Create Array.
Asset Planning Tool •
After Processing Prediction Plot of the Site.
•
For multiple Site we can select required Site the go for Prediction.
Single Site Prediction
Multiple Site Prediction
Report
Export • The project can be exported to the following format : – Coverage (MapInfo bitmap) – Enterprise – Coverage (Coversoft/GSM Association V6) – Coverage (InterGraph) – Coverage (MapInfo Mif) – Coverage (MapInfo Tiff) – Neptune – NPS/10 – NPS/X – PlaNet/EET
Import •
Asset can import data from :-
– Enterprise – Neptune – NPS/X – PlaNet/EET
