RF Planning Procedure

RF Planning Procedure for Greenfield Network

Copyright 2009 – Aircom International (India) Pvt. Ltd.

Confidential – not for circulation

Prepared by: Shailendra kumar

Page 1

1. INTRODUCTION Network Planning Play’s a critical role in any cellular design process. Nominal planning is performed to generate basic site count for a new network which forms the foundation stone of that network. By doing a proper Network planning by keeping the future growth plan in mind we can reduce a lot of problem that we may encountered in future and also reduce substantially the cost of optimization once the network will be on full swing. On the other Hand a poorly planned network not only leads to many Network problems, it also increases the Capex and Opex once the network is live. In current low cost/revenue scenario we need to focus on smart and accurate planning to reduce the Capex and Opex during the whole project. Several mechanism and logics are implemented to address such issue which we will discuss in subsequent pages. It is important to remember that local regulation and company policies may change the process or certain step in process. The practices presented in this section serve the purpose of highlighting the important area in RF Design.

1. NETWORK PLANNING AND DESIGN PROCESS. The RF design process presented is a generic process for Greenfield/New Network. In this section RF designed process is described where as CORE&TRANSMISSION is described in other section. The RF design process consists of Two Phases.

 Preliminary Planning  Final Design Fed into the RF design process are the design requirements such as link budget and traffic prediction, and the output of the process is the RF system design(location of the cell sites, cell site parameters, coverage prediction, site sketches, drive test data. Steps need to be followed while planning new network •

CW Testing

•

Model Tuning

•

Nominal Planning

•

RF Survey/Candidate Selection



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Flow Chart Radio Planning



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1. CW Testing The Aim of the CW measurements from field to calibrate Macro cell Propagation Model for Network for different model like a) Dense Urban b) CBD c) Urban,

d) Sub Urban e) Industrial.

 Principally each model should have 5 Sites for accurate measurement, however some time it becomes customer dependent. Few customer demands it with 3 sites per model to save the budget. The objective of CW Drive testing & Model Tuning is: a) To ensure accurate propagation Model b) Aim is to produce Zero Mean Error & Minimize the standard Deviation (Less than equal to 8) Propagaton 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.

–

Wattmeter 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.



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Steps to Follow while doing CW/Simulation Testing

Step s

Activity

Description This is the important part of CW testing as wrong selection will lead to bad results, therefore careful planning is crucial to achieve good results. Site selection should be in synch with customer.

Step1

Site Selection and Route Planning

Step2

Hardware Installation

After site selection , hardware like Antenna, transmitter will be installed at site.AC main is required to energize the transmitter

Step3

Drive Testing and Data Collection

Radio receiver will be used to collect field measurement during drive testing. Drive tester will maintain average speed of 40 Km/Per Hour to get the better results.

Step4

Drive Length

Since the drive will be conducted at higher frequencies therefore the drive route will less<6Kms as signal disappear after that in higher frequency.

2. Model Tuning This is the next step after CW sample collection, collected samples fed into the Asset tool for calibration and Model tuning. Steps followed during the model tuning represented in chart as mentioned below.



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Introduction

RF propagation is based on numerous factors resulting in a very complex process to attempt to model. There is no single “correct” method of calibrating a model but the process described here is widely used. During calibration data from CW surveys is used to calibrate the propagation models to improve their accuracy. Asset allows model parameters to be adjusted to obtain an accurate match between the CW survey data and predictions. The overall objective is to minimize the error between the Propagation Model and the Continuous Wave survey data. The metrics used to quantify the error are the Mean, RMS and Standard Deviation. The generic iterative calibration process can be described as follows:

 Import the CW data into Asset.  Edit CW Properties by entering the Transmitter Antenna details like Type of Antenna being used, Latitude, Longitude, Azimuth, Tilt, Transmitter Height, Power (EiRP) and so on.  Analyze the CW data itself by thoroughly using tools like Histogram Analyses, Clutter Distribution and Regression Analysis.  Average the CW samples on basis of Rayleigh Fading and Map resolution used.  Filter the CW data on basis of Distance from Site and RSSI.  Use AMT (Automatic Model Tuner) to tune the basic Planet General Model.  Save the Model Tuning report.  Note down the Mean and Standard Deviation achieved.  See if the required targets (i.e. Mean=0, SD<8) are achieved.  If targets are met Propagation Model is tuned, if not try and alter the Filtering parameters slightly. And Go to Step 6.  One can also optionally fine tune the Clutter Absorption Loss(CAL) manually on top of AMT. This is achieved by placing a dummy site with the same configuration as that of the CW Transmitter.

 One needs to continuously alter the model parameter in question, re-analyze against the measured data, quantify the effect of the change in terms of whether the change was beneficial (i.e. it has reduced the standard deviation between the propagation model and the CW data) until and unless Mean and Standard Deviation cannot be reduced any further

After completing the procedure we get K1 to K7 values which will be used to calculate path loss as shown below.



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Path Loss: K1+K2log(d)+K3logHms+K4log(Hms)+K5log(Heff)+k6log(Heff)*logd+K7difn+C_Loss.

d = TX-Rx distance (m) Heff=Height Effective Hms=Test mobile effective height (m) Diffn=Diffraction Loss (dB) K1 and K2 =Intercept and Slope K3= Mobile antenna height Factor K4=Okumara Hata multiplying factor K5=Effective antenna height gain K7=A Multiplying factor for diffraction

3. Nominal Planning Nominal Planning is backbone of any network launch and acts as a foundation stone on which the entire Network is planned. Nominal Planning consists of determining the position and characteristics of each site to achieve compliance with coverage and traffic requirement. Coverage Plots of this nominal Cell Planning are issued to represent the result of this design step. For the purpose of bid, a Nominal plan will be prepared based on the equipment details, subscriber projection, coverage objectives, and coverage threshold and propagation model applicable in the desired circles. The objective is to provide a nominal cell plan, which will demonstrate the proposed design. This will include nominal plans for Coverage Preliminary Work a) Propagation Tool Setup



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1. Set up the planning tool hardware. This includes the server and or clients which may be UNIX based. 2. Setup the plotter and printer to be used. b) Terrain, Clutter, Vector data acquisition and setup

1. Procure the terrain, clutter and vector data in the required resolution. 2. Setup these data on the planning tool. 3. Test to see if they are displayed properly and printed correctly on the plotter. c) Setup site tracking database 1.

This is done using Project management or site management databases.

2. This is the central database which is used by all relevant department, viz. RF, Site acquisition, Power, Civil engineering etc, and avoids data mismatch.

d) Load master lease site locations in database 1.

If predetermined friendly sites that can be used are available, then load this data into the site database.

e) Marketing Analysis and GOS determination for Capacity Management 1.

Marketing analysis is mostly done by the customer.

2. Growth plan is provided which lists the projected subscriber growth in phases. 3. GOS is determined in agreement with the customer (generally the GOS is taken as 2%) 4. Based on the marketing analysis, GOS and number of carriers as inputs, the network design is carried out.

f)

Zoning Analysis 1.

g)

This involves studying the height restrictions for antenna heights in the design area.

Initial Link Budget

1. Link Budget Analysis is the process of aanalyzing all major gains and losses in the forward and reverse link radio paths.

2. Inputs Confidential – not for circulation


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a.

Base station & mobile receiver sensitivity parameters

b. Antenna gain at the base station & mobile station.

c. Hardware losses (Cable, connector, combiners etc). d. Target coverage reliability. e.

Fade margins.

3. Output a.

Maximum allowable path loss.

h) Initial cell radius calculation

1. Using link budget calculation, the maximum allowable path loss is calculated. 2. Using Okumura Hata empirical formula, the initial cell radius can be calculated. i)

Initial cell count estimates

1. Once the cell radius is known, the area covered by one site can be easily calculated. 2. By dividing the total area to be covered by the area of each cell, a initial estimate of the number of cells can be made. j)

Morphology Definition

1. Morphology describes the density and height of manmade or natural obstructions. 2. Morphology is used to more accurately predict the path loss. 3. Some morphology area definitions are Urban, Suburban, rural, open etc. 4. Density also applies to morphology definitions like dense urban, light suburban, commercial etc. 5.

This basically leads to a number of sub-area formation where the link budget will differ and hence the cell radius and cell count will differ.

k) Complete Initial Cell Placement 1. l)

Planning of cell sites sub-area depending on clutter type and traffic required.

Run Propagation Analysis 1.

Using generic models prepared by drive testing & prop test, run predictions for each cell depending on morphology type to predict the coverage in the given subareas.

2. Planning tool calculates the path loss and received signal strength using Coordinates of the site location, Ground elevation above mean sea level, Antenna



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height above ground, Antenna radiation pattern (vertical & horizontal) & antenna orientation, Power radiated from the antenna.

m) Reset Cell Placement( Ideal Sites)

1. According to the predictions change the cell placements to design the network for contagious coverage and appropriate traffic. n) System Coverage Maps 1.

Prepare presentations as follows

2. Background on paper showing area MAP which include highways, main roads etc. 3. Phase 1 sites layout on transparency. 4. Phase 1 sites composite coverage prediction. 5.

Phase 2 sites layout transparency.

6. Phase 2 composite coverage predictions on transparency. 7.

If more phases follow the same procedure.

o) Design Review With The Client 1.

Initial design review has to be carried out with the client so that he agrees to the basic design of the network.

2. During design review, first put only the background map which is on paper. Then step by step put the site layout and coverage prediction.

3. Display may show some coverage holes in phase 1 which should get solved in phase 2 .

Input Required for Nominal Planning

a. All relevant data such as coverage objectives Antenna specifications (radiation pattern and specifications), regulatory constraints (max EIRP, site height, etc.) b. RF propagation model for each clutter type.

c. The existing sites/towers from Infrastructure partner if any; shall be the basis for the start of nominal cell planning. Other sites required for the purpose will be added in the plan to meet the planning objectives.



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Responsibility Matrix S No Activity

Vendor Customer

1

EiRP details

-

P

2

Link Budget with K values

P

S

3

Nominal RF Design – Site details with Lat-Long, antenna height, tilt, azimuth, Coverage Plots, Statistics, XML export from planning

P

-

4

Digital Map Data

P

-

7

Hot Spot Location

-

P

8

List of highways & Rail routes to be covered

-

P

9

List of Sharing site details & Antenna height details

-

P

10

Proposed polygons of cities

-

P

11

Coverage Plots – A0 plots

P

-

12

Coverage & Site export in MapInfo format

P

-

13

Coverage information in PPT

P

-

14

Submission of Final Report

P

-

4. RF Survey & Candidate selection This is the next step of nominal planning wherein we send the engineer in the field for physical verification Initial design review has to be carried out with the client so that he agrees to the basic design of the network. During design review, first put only the background map which is on paper. Then step by step put the site layout and coverage prediction. Display may show some coverage holes in phase 1 which should get solved in phase 2 . The site survey is the activity of describing a potential site, and evaluating its feasibility and preparedness for possible installation. Also examined are constraints and location specific information that would lead to the qualification or disqualification of the chosen location. A specific questionnaire is used as a guideline for this activity. This Candidate Information Report (CIR) questionnaire captures all information about the site including equipment room, antennas, power supply details, etc . Equipment room survey consists in drafting a plan of the room where the equipment will be installed.



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Examination of existing towers, antennas and environment on each site allows for determination of antennas best location. Information so gathered is input into a site survey report, which will be used for site selection and site engineering (when the site is selected).

a) Selection of Sites Prepare Initial Search Ring

•

Note the latitude and longitude from planning tool.

•

Get the address of the area from mapping software.

•

Release the search ring with details like radius of search ring, height of antenna etc.

Release search rings to project management

Visit friendly site locations

•

If there are friendly/sharing sites available that can be used (infrastructure sharing), then these sites are to be given preference.

•

If these sites suite the design requirements, then visit these sites first.

Select Initial Anchor Sites •

Initial anchor sites are the sites which are very important for the network buildup, Eg - Sites that will also work as a BSC.

Enter Data In Propagation Tool

•

Enter the sites exact location in the planning tool.

Perform Propagation Analysis •

Now since the site has been selected and the lat/lon of the actual site ( which will be different from the designed site) is known, put this site in the planning tool and predict coverage.

•

Check to see that the coverage objectives are met as per prediction.

Reset / Review Search Rings •

If the prediction shows a coverage hole ( as the actual site may be shifted from the designed site), the surrounding search rings can be resetted and reviewed.

Candidate site Visit( Average 3 per ring) •

For each proposed location, surveys should carried out and at least 3 suitable site candidates identified.



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•

Details of each candidate should be recorded on a copy of the Site Proposal Form for that site. Details must include: »

Site name and option letter Site location (Lat./Long)

»

Building Height

»

Site address and contact number

»

Height of surrounding clutter

»

Details of potential coverage effecting obstructions or other comments (A, B, C,...)

Visit Site With All Disciplines( SA, Power, Civil etc ) •

A meeting at the selected site takes place in which all concerned departments like RF Engineering, Site acquisition, Power, Civil Engineer, Civil contractor and the site owner is present.

•

Any objections are taken care off at this point itself.Otherwise this will create problem in future

•

Proper site location determines usefulness of its cells.

•

Site are expensive and have to be chosen carefully.

•

The planner needs to visit each and every site if required

Site Location

Simple logic for Good site •

We need to understand various factors we must take into account to ensure that the selected site is good.

•

Simple way is to ask yourself three questions 1) Why am I putting this site ? 2) Will this selected site serve that purpose ? 3) Are there any possible problems that might arise if i select this site. If yes can I solve or avoid those problems?

BAD SITE SELECTION •

Uncontrolled interference

•

Interleaved coverage

•

Awkward HO behaviours

•

But are good for microwave links



Page 14

GOOD SITE SELECTION •

Sites off hilltop locations are preferable for a BTS site as  hills can be used to separate cells  interference can be easily controlled  minimum overlapping will result  can face problems for microwave links

Desired cell boundary

b) SITE SELECTION CRITERIA Radio criteria for site selection •

Good view in the main beam direction



Page 15

•

No surrounding nearby high obstacle

•

Good visibilty of terrain

•

Room for antenna mounting

•

LOS to the two microwave site and if possible to the BSC

•

Short cabling distance

Non-radio criteria •

Space for equipment

•

Availaibilty of lease lines or microwave links

•

Power supply

•

Access restrictions

•

Rental costs

•

Ease of acquisition

c) Guideline while doing RF Physical Survey 1. Make yourself clear what to do before starting survey. 2. Survey Engineers should have a) 5/6 Mega Pixel Camera b) Measurement Tape c) GPS d) Binocular e) Compass f) Altimeter 3. Each option should have 12 different photograph even after same clutter and within search ring. 4. Check Properly, if nominal falls in DIG or lower AMSL area 5. Govt area should be intimated well in advance. 6. Check Properly, option should be at least 50m away from HT line 7. For sharing option photograph for clutter should be taken from tower only. 8. Each obstruction should be captured in camera. 9. Proper justification required for single option and same should be communicated from site only. 10. Take clear photograph of existing tower justifying antenna height in case of sharing option 11. Daily Report Submission 12. Make proper civil layout for new option 13. Building feasibility should be checked properly for candidate selection. 14. Clear visibility of footprint of site & structural stability of building. For example a) G+1 building can not take a load of 40m tower b) If we required 24 height on 24m building then we should not proposed 24 m tower height.4 m of pole can cater the purpose c) For GBT option we should have at least footprint of 15mx20m for 50m tower. d) For GBT option we must take the photograph near by building if possible otherwise prepare a plan. 15. For sharing option make proper layout indicating dimension and position of tower,D.G,Shelter, Guard room



Page 16

16. For sharing option make proper layout of shelter(Inside) indicating dimension and position of BTS, Battery Bank, Power Supply,Tx Rack etc. 17. Consider all obstruction which can obstruct RF signal, take photograph fro each obstruction 18. Check the building feasibility properly a) Check the column, space for site b) Match the criteria justifying tower * building height relation 19. Always carry complete KIT along with extra battery. 20. Mobile phone should be switched on at any point of time.

5. CASE STUDY ON NOMINAL PLANNING-1 City-Calicut Contents 

Short Summary of CALICUT



Assumption & Guideline



Link Budget



Propagation Model



Polygons



Sharing Site Options



Planned Vs Sharing Sites



Statistics of Planned City Sites



Clutter partition as per standard Polygon used by other OPCO



Summary



Recommendations



Page 17

a) Short Summary of CALICUT City The city of Kozhikode, Calicut as it was known to the British and Europeans was the seat of active trade, political unrest and historical happenings. It is a tourist hotspot and a favored destination.

b) Assumption and Guidelines 

Map Used-25m(Resolution)



Antenna Used for Nominal Planning-65 deg for City & 33 Deg for Highway

Clutter Dense Urban Urban Sub Urban Rural / Highway

Bldg Loss 25 dB 20 dB 15 dB 8 dB

Threshold -65 dB -70 dB -75 dB -85 dB

Antenna Horizontal Beam width 65 Degree 65 Degree 65 Degree 65/33 Degree

Antenna Gain

RF Antenna Ht

17 dBi 17 dBi 17dBi 17 / 21dBi

25 M 25 M 30 M 35-40 M

Standard Macro cell 3 Model:Its usage in the environments where the distance from the site is greater than 500 metres, BS antenna heights in the range of 15-200 metres and receiver heights in the range of 1-10 metres. Pathloss (dB)=k1 + k2log(d)+k3(Hms)+k4log(Hms)+K5log(Heff)+k6log(Heff)log(d)+k7(diffn) +C_Loss Where: d is the distance from the base station to the mobile station 9km Hms is the height of the MS above ground (m0)



Page 18

Heff is the effective BS antenna height (m) Diffn is the diffraction loss calculated using either the Epstein-Peterson, Bullington, Deygout or Japanese Atlas Knife edge techniques. K1 & k2 are the Intercept and Slope. These factors correspond to a constant offset (in dB) and a multiplying factor for the log of the distance between the BS and MS K3 is the MS antenna height factor. Correction factor used to take into account the effective MS antenna height. K4 is the multiplying factor for Hms K5 is the effective antenna height gain. This is multiplying factor for the log of the effective antenna height K6 is the multiplying factor for log(Heff)log(d) K7 is the multiplying factor for diffraction loss calculation C-Loss is the clutter specifications such as heights and separation are also taken into account in the calculation process. c) Link Budget ownlink(Dense Urban) Mean o/p power over burst 40 Power(Before 46.0 Combiner) 21

Urban W dBm

40 46.0 21

Suburban W

dBm

40 46.0 21

W dBm

Rural 40 46.0 21

Highway W

dBm

40 46.0 21

W dBm

User input Rx (MS) RxSens

-102

-102

-102

-102

-102

Interference degr.

3

3

3

3

3

Div.gain

0

Rx.ant gain

0

0

0

0

0

Rx ant.cable loss

0

0

0

0

0

UL duplexer loss

0

0

0

0

0

-99

-99

-99

-99

-99

Min Rx Level

n.a.

0

n.a.

0

n.a.

0

n.a.

0

n.a.

User input Tx (BS) Tot.comb.&dupl.los s

3

3

3

3

3

PA backoff???

0

0

0

0

0

17

17

17

17

21

3 57.0 21

3 57.0 21

3 57.0 21

3 57.0 21

3 61.0 21

Tx ant gain Tx ant. Cable loss EiRP

Miscellaneous Standard dev. Area Probability

7

7

7

4

4

79%

79%

79%

79%

79%



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Fading magin Body Loss Indoor penetration loss (Inc LNF) Max.allow.PL Cell range Site area The Threshold Level Assume:

Dense Urban Correction Factor

5.64 49

5.64 49

5.64 49

3.22 57

3.22 57

3

3

3

3

3

25 122. 38 0.33 63 0.22 06

20 127. 38 0.56 31 0.61 83

15 132. 38 1.31 41 3.36 74

8 141. 79 3.89 03 29.5 11

8 145. 79 5.41 64 57.2 08

Km Sq.K m

-65 Hb(m )= Hm( m) = a(Hm )=

dBm

Lc =

Frequency

Km Sq.K m

dBm

1.5 0.04 3

-70 Hb(m )= Hm( m) = a(Hm )=

-2

Lc =

25

1800

Km Sq.K m

dBm

1.5 0.04 3

-75 Hb(m )= Hm( m) = a(Hm )=

1

Lc =

25

1800

Km Sq.K m

dBm

1.5 0.04 3

-85 Hb(m )= Hm( m) = a(Hm )=

8

Lc =

30

1800

Km Sq.K m

dBm

1.5 0.04 3

-85 Hb(m )= Hm( m) = a(Hm )=

14

Lc =

15

35

1800

35 1.5 0.04 3

1800

d) Propagation Model 

Agreed Coverage Threshold



Considering 100% Sharing



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e) Polygon

1. Polygon Created On Asset

2.Polygon Created On Map of India

f) Sharing Site Options



Page 21

g) Planned Vs Sharing Sites



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h) Statistics of Planned Sites as per Polygon

Statistics for GSM - GSM Best Server [Non-Simulator] Category summary Multiple categories - all display categories in Cumulative mode: Category

Covered area(km²)

Covered area(%)

-65.00 <= x dBm

24.149

57.37%

-70.00 <= x < -65.00 dBm

34.781

82.63%

-75.00 <= x < -70.00 dBm

39.956

94.92%

-85.00 <= x < -75.00 dBm

42.015

99.81%

Clutter

Total area(km²)

Covered area(km²)

Covered area(%)

urban_high_density

0.55

0.55

100.00%

urban_medium

4.351

4.351

100.00%

urban_low_density

12.578

12.573

99.96%

villages

0.94

0.937

99.67%

industrial

0.015

0.015

100.00%

low_dense_vegetation

9.127

9.103

99.73%

Clutter summary



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agriculture/fallow

0.31

0.31

100.00%

water

0.153

0.153

100.00%

open

13.024

13.008

99.88%

quasi_open

0.248

0.248

100.00%

river

0.724

0.724

100.00%

Sea

0.074

0.044

59.66%

Attribute

Total area(km²)

Covered area(km²)

Covered area(%)

CALICUT

42.093

42.015

99.81%

Attribute summary

i)

Clutter partition as Per Polygon CALICUT -Statistics Report (With Available Sharing Options) UNITECH COVERAGE STATISTICS DATE : 6/10/2008

TOWN NAME :

CALICUT

STATE : KERALA

CLUTTER TYPE

DENSE URBAN

URBAN

SUB URBAN

RURAL

TOTAL AREA

0.550

4.366

12.578

0.940

CLUTTER

Area Covered Coverage >-65

With 0.528

% Area Covered With Coverage >-65

96.00%


0.550

4.128


100.000

94.55%


0.550

4.241

With

With


12.048


Page 24


100.000

97.137

95.79%


0.550

4.366

12.573

0.937

100.000

100.000

99.96%

99.68%

With


j)

Prediction Plot (CALICUT City)



Page 25

k) Summary  39 Sites Planned Outside the CALICUT City Polygon for Small Town & Highway out of which 03 Sites are not showing on the 2D view of Asset Tool.



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 Total Sites Used to cover CALICUT City(polygon)– 48 out of which 43 are sharing site, 05 other small town sites.

l)

Recommendations



Page 27



Nominal Planning done with electrical tilt of 2 deg since the city is along with coastal boundary therefore mechanical tilt of 2 deg is recommended for border cells



For Highways and railways we had used 2 sector with high gain antenna and one sector with 65deg city antenna



2 New site required with this link budget and the Clutter requirement.



Change in Orientation based on coverage requirement



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RF Planning Procedure

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