Rf Planning 4

7/29/2019 Rf Planning 4

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RADIO PLANNING METHODOLOGY

Overall picture

It is important to create an ov erall picture of the ne twork

before going into the d etailed netwo rk planning. This is the

fact the m ain objective of this presentation.

Coverage Cap acity and Quality

Providing coverage is usually considered as the m ost

important ac tivity of a new cellular operator. For a wh ile ,

every netwo rk is indeed coverage d riven. How ever thecoverage is not the only thing. It provides the m eans of

service and should mee t certain quality measures.

The starting point is a set of coverage q ualityrequirements.

To guarantee a g ood qua lity in both uplink and dow nlink

direction, the pow er levels of BTS and M S should bebalance d at the ed ge of the cell. Main output results of

the pow er link budget are:

- Maximum pa th loss that can be tolerated betwee n MSand the BTS.

- Maximu m outp ut pow er level of the BTS transm itter.


These values a re calculated as a result of designconstraints.

- BTS and M S receiver sensit ivity.- MS output powe r level

- Antenna G ain- Diversity rece ption

- Losses in com biners, cab les etc.

The ce l l ranges a re derived w ith propaga tion loss

formu las such a s Okum ara Hata or W alfisch Ikegam i,

which are s imply to use . Given a m aximum path loss,

differences in the op erating e nvironment a nd the qual ity

targets w ill result in d ifferent c ell ranges.

The traffic capacity requirement ha ve to be com bined

with the co verage requirem ents, by al locating

frequen cies. This also ma y have impact on the ce l lrange.


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COVERAGE PLANNING STRATEGIES

The selection of site configurations, antenna and cables inthe core of the coverage p lanning strategy. The right

choice will provide cost saving and guarantees smoothnetwork evolution.

Some typical configurations are :- 3 sector site for (sub)urban areas- 2 sector site for road coverage.- Omni site for rural areas.

These are not the ultimate solutions, decisions should be

based o n careful analysis.Cell Range and Coverage Area :

For any site configurations, the cell ranges ca n bedetermined given the e quipment losses and ga ins. The sitecoverage areas can be calculated then and these w ill lead

to required numb er of sites for a given co verage region. Thismakes it possible to estimate the cost, eg. Per km 2, to be

used for strategic decisionsAfter getting the overall picture, the actual d etailed

radio network planning is done with a RN P tool.


- Marketing specifications- Define design rules and parameters.

- Set performance targets.- Design nominal cell plan.- Implement cell plan.- Produce frequency plan.- Optimize network.- Monitor performances.


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METHODOLOGY EXPLAINED

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 (rollout and

quality)- Forecast traffic dem and and distribution.- Test business plan for different roll out scenarios and quality

levels.Design nominal cell plan.

- Use computer tool to place sites to meet coverage an dcapacity targets.

- Verify feasibility of meeting service requirements- Ensure a frequency plan can be made for the design.- Estimate equipment requirement and cost.

- Develop implementation and resource plans (includingpersonal requirements)- Radio plan will provide input to fixed network planning.


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 envolving

network.

Produce Frequency Plan- Fixed Cluster configration, can be done manually.- Flexible, based on interference matrix using an automatic

tool.


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Optimize the network

- Campaign of measurements- Analyze results

- Adjust network parameters such as : antenna directions,handover parameters, and frequencies.

Expand the network- In accordance with rollout requirements- In accordance with forecast traffic levels

- To improve coverage quality.

- To maintain blocking performances.

RF Planning Process

1 Understand the Customers requirements

Coverage requirements

In building coverage experiments

Initial Roll out plans

Pre determined number of sites ?

2 Survey

Traffic Distribution and Pattern

Growth areas

High density business/ residential areas

Propagation tests for in building coverage estimates

and model calibrations

3. Prepare Planning Tool

Get Digitized maps

Load maps in the planning tool.

Use survey data and run the programme.


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RF Planning Process

4. Draft Plan

Divide the city into number of regions-

Busy business areas

Areas that need excellent inbuilding coverage

areas

Use appropriate model and link budgets to

calculate the number of sites required per region.

5. Fine Tune plan.

Perform more with drive test, confirm plan

predictions.

Review plan with customer and fine tune the plan.

RF Planning Process

Understanding Customer Requirements :

What are the boundaries for the network ?

Are there any special pockets to be covered due to

Govt. requirements ?

What are the areas in which medium to average in

building coverage is acceptable ?

What are the areas where excellent in building

coverage is needed ?

Areas with high growth potential

Need colonies under development

High revenue areas

Shopping malls , offices complex, industrial estates

etc.


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RF Planning Process

In it ia l Imp leme ntat ion Strategy :

High usa ge, h igh reve nue users f ir st ?

High end res iden t ia l and b us iness areas ?

Street coverage f i rst ?Spec ial areas l ike 5 s tar hotel , com m ercial

bui ld ing w ith f ine in bui ld ing co verage ?High wa y cove rage cr it ical ?

Tota l coverage on d ay one ?

Num ber of s ites more than the com pet it ion ?

Any Bu dge t L im itat ions ?

G ive an ideal p lan to s tar t with.Let the custom er cut corners.No t an easy job ! !

RF Planning Process

City Surveys :

Basically a scouting exercise

Looking for :-

Major traffic routes

Markets

Business Centres

Shopping malls

General customer behaviors

Telephone density

Congested areas with narrow lanes

Narrow water canals/lakes/ponds

General city layout

Prestigious residential areas.

VIP areas

Parks/ playground/open areas.

General Building types.. Multistoried, Row houses,

apartments, colonies etc.

Airport coverage


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RF Planning SurveysIn building Coverage Surveys :

Classify Buildings-

Hotel/restaurants

Commercial

Industrial

Residential

Shopping malls/markets

Propagation tests in a number of buildings in each variety.

Rf signal on road Vs. inside building gives building penetration loss.

Repeat tests in as many buildings as possible to get an estimate of

building loss for the area.

In building coverage affected mostly in ground floor/basement

Typical values (examples only) :

> Hotel restaurants 15 dB

> Commercial buildings 20 dB

> Shopping malls 15 dB

> Industrial Estates 12-15 dB

> Residential buildings 15-20 dB

> Old/Historical buildings 25-30 dB

RF Propagation Test KitsBattery powered Transmitter. 10 or 20 Watts output : frequency in

GSM 900/1800 Mhz.

Portable mast Adjustable upto 5 m. With 1 m

antenna on top, effective height

above ground is 6 m.

Transmit antenna High gain omni or directional antenna

as required

Receiver TEMS mobile Hand held mobile phone with RS232connection to a laptop. Or an

accurate portable RF sensitivity meter

/ CW receiver if model calibration is

required.

Positioning system GPS system, with PCMCIA card

Computer Laptop PC with TEMS software and

GPS software

Cables accessories Calibrated cable lengths (10 m) of low

loss feeder with known attenuation

values; 12 Volts battery with

appropriate cable to connect to

transmitter.

Power meter, VSWR meter.


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RF Planning ToolPlanning Tool preparation and Model Calibration :

There are many planning tool available toaday :

PLANET (MSI)

Cell Cad (LCC)

Odessy (Aethos)Asset (Aircom)

NetPlan (Motorola)

A planning tool Should be :

Easy to use

Compatible with tools like TEMS

Minimum hardware requirements.

Economical.

Maps collected from authorized sources.

1:50000 or 1:25000 scale

50 m resolution for macro

Less than 30 m resolution for Micro cell planning using Ray tracing Tool

Maps are digitized under 3 categories :

LandUse

Digital Terrain MapVectors (Roads, Railways, etc.)


Most Planning tools use corrections for the land use or clutter.Propagation Model tuned by assigning the values to

Clutter factor (Gain or Loss due to clutter )

Clutter Heights (for diffraction modeling)

Different types of clutter are defined in these models/ tools

1. Dense Urban2. Urban

3. Suburban

4. Suburban with Dense Vegetation

5. Rural

6. Industrial area

7. Utilities (marshalling yards, docks, container depots etc. )

8. Open area

9. Quasi Open Area

10. Forest

11. Water

Too many clutter type definitation complicate planning process 10 to 15 is

typical.


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DTM

Provided by the map vendor

Provides contour information as a digital map.

Vectors

Highways

Main Roads

Railways

Canals / water ways.

Coast line

Rivers.

Each categories is digitized as different layer

Displayed separately if required

Map information is set up in the planning tool.

Model calibration carried out.

Model CalibrationAll tools have provision for manipulating clutter values.

Different tools have different directory structures and means of handling

geographical data.

The procedure mainly talks about ensuring correct data header files toinclude.

BTS location

EIRP of BTS

Antenna Type BTS antenna height

Description of surrounding area.

Procedure uses a general core model equation :

The equation has constant k1 to k6 and a constant of clutter, kclutter

Initial values for the constants are set as per the model chosen (sayOkumara Hata )

PLANET programme is run repeatedly to make RMS error values forall data files ZERO or a minimum.

For each run of the programme, the values ofk1 to k6 are manipulated.

This completes model calibration.


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Link Budget and other Steps

Key Points To be Considered :

Coverage Probability

Expected inbuilding coverage

Edge probability

Fade margin required

Maximum permissible path loss ( from the link Budget )

What is the radius of the cell ?

Number of sites required (from coverage point of view )

Is the number of sites calculated as above adequate for

capacity ?

Decide on more sites for capacity.

Capacity Calculations

Capacity calculations :

Check if number of sites is enough to give capacity.

Depends on

Spectrum available This decides the site configuration.

Availability of features like frequency hopping etc.

If Capacity is not met, add more sites.

If number of site is not OK with the customer, then :-

Recalculate site density, for 50 % in building coverage in place

of 75 %


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Fine Tune The Plan

Use Planning tool to return Coverage predictionsIterate the process in consultation with the customer.Finalize Plan and document it.

Search Areas

Planner issues search areas for each site location with information

on : Location Lat/Long Antenna heights Specific target areas if any Size of search areas

Size acquisition team scouts for buildings.3-5 alternatives preferred.

Site SelectionCentral Business area

Small Search areas (100 m)

Avoid near field obstruction.

Antenna at or slightly above the average clutter height.

Orientation is critical.

Try solid structure (lift room ) for antenna mounting.

This helps reduce backlobe radiation problemsAvoid towers on building tops. This reduces interference to neighbouring cells.

Residential suburban areas :

Larger search areas (200 m)

Location not very critical.Antenna 3-5 metres above average clutter height.Antenna orientation less critical.


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Site SelectionIndustrial area :

A suitable central location.

Avoid proximity to electrical installations like towers, transformersetc.

Towers are common

Quasi / open Highways

Larger search areas (500 m)

Limited by terrain and not the clutter. Hilly areas need care.

Highways need closer search areas along road.

Tall sites give better coverage.

Extending Cell RangeExtended cell range reduces number of sites.

Cell range improvement achieved through :

BTS transmit power enhancement

BTS sensitivity enhancement

Combination of both


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Extending Cell RangeImproving BTS receiver sensitivity :

Better devices in the BTS receiver.

Using Mast Head amplifiers with very low noise figures.Better RF cables.

Rf Planning 4

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