Nominal RF Design

Link Budget

Maximum

path loss

Propagation

model

Typical site

configuration

Site radius

Nominal RF

Design

(coverage)

Coverage

requirements

Nominal site count

Coverage site

count

• Transmit Power

• Antenna configuration

(type, height, azimuth)

• Site type (sector, omni)

Traffic

requirements

• Standard hexagon site

layout

• Friendly, candidate sites

• Initial site survey inputs

Traffic site

count

Traffic > Cov.

Cov. > Traffic

• Recalculate the site

radius using the

number of sites from

the traffic requirement

• Repeat the nominal

RF design

Traffic requirements

Nominal RF Design

• Calculation of cell radius

• A typical cell radius is calculated for each clutter environment

• This cell radius is used as a guide for the site distance in the respective clutter environment

• The actual site distance could varies due to local terrain

• Inputs for the cell radius calculation :-

• Maximum pathloss (from the link budget)

• Typical site configuration (for each clutter environment)

• Propagation model

Nominal RF Design

• There are different level of nominal RF design :-

• Only using the cell radius/site distance calculated and placing ideal hexagon cell layout

• Using the combination of the calculated cell radius and the existing/friendly sites from the customer

The site distance also depends on the required capacity

•In most mobile network, the traffic density is highest within the CBD area and major routes/intersections

•The cell radius would need to be reduce in this area to meet the traffic requirements

•BASED ON THE SITE DISTANCE & THE COVERAGE REQUIREMENTS CELL COUNT BASED ON COVERAGE IS CALCULATED.

Nominal RF Design

• Cell count based on traffic is derived based on capacity inputs:- • Capacity requirements • GOS • Spectrum availability • Freq. Hopping techniques

• If the total sites for the traffic requirement is more than the sites required for coverage, the nominal RF design is repeated using the number of sites from the traffic requirement

• Recalculating the cell radius for the high traffic density areas

• The calculation steps are :- • Calculate the area to be covered per site • Calculate the maximum cell radius • Calculate the site distance

Site Realisation

• After completion of Nominal design based on cell count ( coverage & capacity requirements) , search rings for each cell site issued.

• Nominal design is done , with the existing network in place(existing BTS). Existing site location remain unchanged , azimuth , tilts as per the new design requirements.

• Based on the search ring form physical site survey is undertaken.

Site Realisation

Search Ring Form

• Site ID

• Site Name

• Latitude/Longitude

• Project name

• Issue Number and date

• Ground height

• Clutter environment

• Preliminary configuration

• Number of sector

• Azimuth

• Antenna type

• Antenna height

• Location Map & SR radius

• Search ring objective

• Approvals

Spheroid:

Coordinates: (GPS)

o ' ''N

o ' ''E

Site AGL (m): 30 Antenna Type: 65 deg Vertical polarised

Antenna Orientation(Deg)

Coverage Objectives:

Revision No. : R1.1

Name & signature of RF Coordinator

Comments

Krishna Nagar, Jotiba Nagar, Shambaji Nagar, Yamuna Nagar

BSNL Circle:Haryana

Krishna Nagar

City / SSA:

Search Radius:50 m

350 120

Sector1 Sector2 Sector3

sec

18 39

240

Search Ring Form

Site Name: Site Id:

Morphology Type: Quasi Open , Industrial

47 36.7

WGS-84

Issue Date:

Longitude: 73

Latitude: 49.3

deg min

Site Realisation

Release of Search Ring

Suitable Candidates?

Candidates

Approved?

Arranged Caravan

All parties agreed at

Caravan

Produce Final RF

Design

Caravan next candidate

Exhausted candidates

Additional sites required

Cell split required

Candidate

approved?

Driveby, RF

suggest possible alternative

Next

candidate Problem

identifying

candidate

Discuss

alternative with customer

Issue design change

Exhausted candidates

Y

N

Y Y

Y

Y

Y Y

N N

N

N

N N

Y N

Site Realisation

• Candidate Assessment Report-Site Survey Forms

• Site survey Forms for all suitable candidates for the search ring

• For each candidates :- • Location (latitude/longitude) • Location map showing the relative location of the candidates and

also the search ring • Candidate information (height, owner etc) • Photographs (360º set, rooftop, access, building) • Possible antenna orientations • Possible base station equipment location • Information for any existing antennas • Planning reports/comments (restrictions, possibilities of approval

etc.)

Site Realisation-Site Survey Form

• Final RF Configuration Form

• Base Station configuration • Azimuth • Antenna height • Antenna type • Down tilt • Antenna location • Feeder type and length • BTS type • Transmit power • Transceiver

configuration

Date

BSNL Circle

CITY / SSA

Site ID

Site Name

Owner Name

Address & Contact No.

Construction

Tower Type Bldg. Hgt

Tower Hgt Antenna Ht

Coordinate LAT N LONG E

GSM ANTENNA :

AZ M-TILT

SECTOR 1 85° +1.9 Spheroid:

SECTOR 2 185° +0.7

SECTOR 3 307° +1.3

Candidate No.

Assess: Priority

Morphology/Clutter

Site Blockage if Any

Remark

Name: Name:

Signature: Signature:

BSNL/ NBSNL

20 m.

GBT / Rooftop 10 m.

6 m.

AP909014-2

BSNL Survey Team Representative Nokia Representative

Accept/ Reject

TECHNICAL SITE SURVEY FORM

June 12, 2004

BHPAT-09

Bihar

AP909014-2

AP909014-2

Patna 09

Container/Room

85° 48 ' 31.2"26° 21' 25.9"

TYPE

Traffic Engineering

Spectrum

Available Reuse factor

Maximum number

of TRX per cell

No of TCH

available Traffic offered

Traffic

Requirement

Subscriber supported

Channel loading

Traffic Engineering

• Traffic Requirement

• The Erlang per subscriber

• Grade of Service (GoS)

• GoS is expressed as the percentage of call attempts that are blocked during peak traffic

• Most cellular systems are designed to a blocking rate of 1% to 5% during busy hour

Traffic Engineering • Frequency Reuse

• In designing a frequency reuse plan, it is necessary to develop a regular pattern on which to assign frequencies

• The hexagon is chosen because it most closely approximated the coverage produced by an omni or sector site

• Common reuse factor : 4/12, 7/21

Traffic Engineering

• Channel Loading

• As the number of TRX increases, the control channels required increases accordingly

• The following channel loading is used for conventional GSM network

• For services such as cell broadcast, additional control channels might be required

Number of TRX Control Channels Number of TCH

1 Combined BCCH/SDCCH 7 2 1 BCCH, 1 SDCCH 14 3 1 BCCH, 2 SDCCH 21 4 1 BCCH, 2 SDCCH 29 5 1 BCCH, 3 SDCCH 36 6 1 BCCH, 3 SDCCH 44 7 1 BCCH, 3 SDCCH 52 8 1 BCCH, 3 SDCCH 60

Traffic Engineering

• After determining the number of TCH available and the traffic requirements, the traffic offered is calculated using the Erlang B table

• For example, for a 2% GoS and 3 TRX configuration, the traffic offered is 14

Erlang

• If the traffic per subscriber is 50mE/subscriber, then the total subscribers

supported per sector = 280

• For a uniform traffic distribution network, the number of sites required for the traffic requirement is :-

siteper supportedSubscriber

rs subscribeTotal sitesTotal

Traffic Engineering

• Erlang B Table

N 1% 1.20% 1.50% 2% 3% 5% 7% 10% 15% 20% 30% 40% 50%

1 0.01 0.01 0.02 0.02 0.03 0.05 0.1 0.11 0.18 0.25 0.43 0.67 1

2 0.15 0.17 0.19 0.22 0.28 0.38 0.5 0.6 0.8 1 1.45 2 2.73

3 0.46 0.49 0.54 0.6 0.72 0.9 1.1 1.27 1.6 1.93 2.63 3.48 4.59

4 0.87 0.92 0.99 1.09 1.26 1.52 1.8 2.05 2.5 2.95 3.89 5.02 6.5

5 1.36 1.43 1.52 1.66 1.88 2.22 2.5 2.88 3.45 4.01 5.19 6.6 8.44

6 1.91 2 2.11 2.28 2.54 2.96 3.3 3.76 4.44 5.11 6.51 8.19 10.4

7 2.5 2.6 2.74 2.94 3.25 3.74 4.1 4.67 5.46 6.23 7.86 9.8 12.4

8 3.13 3.25 3.4 3.63 3.99 4.54 5 5.6 6.5 7.37 9.21 11.4 14.3

9 3.78 3.92 4.09 4.34 4.75 5.37 5.9 6.55 7.55 8.52 10.6 13 16.3

10 4.46 4.61 4.81 5.08 5.53 6.22 6.8 7.51 8.62 9.68 12 14.7 18.3

11 5.16 5.32 5.54 5.84 6.33 7.08 7.7 8.49 9.69 10.9 13.3 16.3 20.3

12 5.88 6.05 6.29 6.61 7.14 7.95 8.6 9.47 10.8 12 14.7 18 22.2

13 6.61 6.8 7.05 7.4 7.97 8.83 9.5 10.5 11.9 13.2 16.1 19.6 24.2

14 7.35 7.56 7.82 8.2 8.8 9.73 10.5 11.5 13 14.4 17.5 21.2 26.2

15 8.11 8.33 8.61 9.01 9.65 10.6 11.4 12.5 14.1 15.6 18.9 22.9 28.2

16 8.88 9.11 9.41 9.83 10.5 11.5 12.4 13.5 15.2 16.8 20.3 24.5 30.2

17 9.65 9.89 10.2 10.7 11.4 12.5 13.4 14.5 16.3 18 21.7 26.2 32.2

18 10.4 10.7 11 11.5 12.2 13.4 14.3 15.5 17.4 19.2 23.1 27.8 34.2

19 11.2 11.5 11.8 12.3 13.1 14.3 15.3 16.6 18.5 20.4 24.5 29.5 36.2

20 12 12.3 12.7 13.2 14.0 15.2 16.3 17.6 19.6 21.6 25.9 31.2 38.2

21 12.8 13.1 13.5 14 14.9 16.2 17.3 18.7 20.8 22.8 27.3 32.8 40.2

22 13.7 14 14.3 14.9 15.8 17.1 18.2 19.7 21.9 24.1 28.7 34.5 42.1

23 14.5 14.8 15.2 15.8 16.7 18.1 19.2 20.7 23 25.3 30.1 36.1 44.1

Traffic Engineering

• If a traffic map is provided, the traffic engineering is done together with the coverage design

• After the individual sites are located, the estimated number of subscribers in each sector is calculated by :-

• Calculating the physical area covered by each sector

• Multiply it by the average subscriber density per unit area in that region

• The overlap areas between the sectors should be included in each sector

because either sector is theoretically capable of serving the area

• The number of channels required is then determined by :-

• Calculating the total Erlangs by multiplying the area covered by the average

load generated per subscriber during busy hour

• Determine the required number of TCH and then the required number of TRXs

• If the number of TRXs required exceeded the number of TRXs supported by the available spectrum, additional sites will be required

SWAP PLAN

• Why do we need a swap plan?

To reduce mix of different vendor BTS within a large city/ area • Reduce Inter MSC HO. • Better maintenance efficiency

Swap Strategy • No. of existing BTS sites with configuration known • No. of new sites with configuration known.

Network Planning Steps

Parameter Planning

• Parameter planning means creating a default set of BSS parameters.

• The most important parameters to plan for: • frequencies • BSIC • LAC • handover control parameters • adjacent cell definitions.

BSS Parameter

• Relevant BSS parameter for NW planning

• frequency allocation plan

• transmit power

• definition of neighbouring cells

• definition of location areas

• handover parameters

• power control parameters

• cell selection parameters