Mobile (Cellular) Network Dimensioning and Planning

Jaspreet Singh Walia

467355, jaspreet.walia@aalto.fi

28-10-2014

Abstract

The purpose of network dimensioning and planning of a telecommunications network is to ensure that the

expected need will be met in an economical way, both for the operators and the subscribers.

In the field of network building and expansion the main advances have been in planning the radio and

transmission part of the network and in optimizing the processes and activities in the existing networks.

Second generation (2G) mobile communications have enabled voice traffic to go wireless. The third

Generation (3G) mobile communications known as Universal Mobile Telecommunications System (UMTS)

uses variable data rates and also independence of service platforms. The variable bit rate enhances the

usability and performance efficiency for both customers and operators but also poses greater challenges in

network planning and optimization.

This report gives description of the main phases of network planning and important aspects like link budget

modeling and network capacity, by providing solutions for the given problems.

1) Introduction:

Network planning is a rather iterative process from topology design, network synthesis to

realization. Its purpose is to ensure that new networks and services meets the demand of subscribers

and operators.

Need of Network Planning:

Meet current standards and demands and also comply with future requirements.

Uncertainty of future traffic growth and service needs.

High bit rate services require knowledge of coverage and capacity enhancements methods.

Real constraints o Coexistence and co-operation of 2G and 3G for old operators. o Environmental constraints for new operators.

Network planning depends not only on the coverage but also on load.

Dimensioning

Radio network dimensioning is an iterative process in which possible configurations and amount of

network equipment are estimated, based on the operators and subscribers requirements related to the following:

Coverage:

coverage regions

area type information

propagation conditions Capacity:

spectrum available

subscriber growth forecast

traffic density information Quality of Service:

area location probability (coverage probability)

blocking probability

end user throughput

Dimensioning activities include radio link budget and coverage analysis, capacity estimation, and

finally, estimations on the amount of sites and base station hardware, radio network controllers

(RNC), equipment at different interfaces, and core network elements (i.e. Circuit Switched Domain

and Packet Switched Domain Core Networks).

Detailed Planning

In detailed planning the target is to find the optimum configuration of BTS in each site in planning

area or nominal configuration for different parts of the planning area.

Several factors to be considered:

Propagation environment (macro, micro, indoor cell) Site characteristics (indoor, outdoor, wall, mast) Required capacity and coverage BTS antenna configuration has strong impact on interference level and on capacity Optimum combination among several options is to be selected to fulfill quality requirements. Main

tool is link budget and cell size calculations. Detailed planning incorporates system level

simulations for a certain cluster of cells to estimate maximum traffic or load of the network in

different cells.[4].

In Monte-Carlo type of simulations a certain number of mobiles are located over a coverage area

and distributed homogenously or non-homogenously

Results include coverage, capacity, and interference-related information (BTS TX powers, max. number of mobiles in each cell, one-cell-to-other-cell interference)

Figure 1, System level simulations [4]

Network Optimization

Radio network optimization is performed to improve the performance of the network with existing

resources. The goal is to better utilize existing network resources, to solve existing and potential

problems and to identify possible solutions for future planning. Through Radio Network

Optimization, the service quality and resources usage of the network are greatly improved to

achieve a balance between coverage, capacity and quality. In general, the following steps are

followed during the Radio Network Optimization process:

Data Collection and Verification

Data Analysis

Parameter and Hardware Adjustment

Optimization result confirmation and reporting.

Due to the mobility of subscribers and the complexity of radio propagation, most of network

problems are caused by increasing subscribers and the changing radio environment. Radio Network

Optimization is a continuous process that is required as the network evolves.

Common parameters in link budget calculations

Table 1, Uplink [1],[2]

Table 2, Downlink [1],[2]

2) Dimensioning Part

Municipality Area(km2) Urban/Sub-Urban/Rural

Espoo 312.75 Sub-Urban

Helsinki 213.26 Urban

Vantaa 238.37 Sub-Urban

Kauniainen 5.88 Sub-Urban

Hyvinkaa 322.62 Rural

Jarvenpaa 37.55 Rural

Kerava 30.62 Rural

Kirkkonummi 366.10 Rural

Nurmijarvi 361.84 Rural

Sipoo 339.62 Rural

Tuusula 219.51 Rural

Vihti 522.06 Rural

Total Sub-Urban area= 556.95 km2

Total Urban area= 213.26 km2

Total Rural area= 2199.92 Km2

Losses Respective Values

Tx Power 46 dBm

Antenna Gain 18 dBi

Cable Loss 2 dB

EIRP 62 dB

UE Noise Figure 7 dB

Thermal Noise -104.5 dB

Rx Noise -97.5 dB

SINR -9 dB

Rx Sensitivity -106.5 dB

Control Channel Overhead 1 dB

Rx Antenna Gain 0 dB

Body Loss 0 dB

Interference margin; rural 3 dB; sub-urban 5 dB; city 8 dB

Indoor penetration loss; rural 15 dB; sub-urban 15 dB; urban 20 dB

Maximum path loss = EIRP Interference margin Penetration loss Control channel overhead- receiver sensitivity

Maximum path loss for rural= 149.5 dB

Maximum path loss for sub urban= 147.5 dB

Maximum path loss for city= 139.5 dB

For calculation purpose, frequency of LTE is taken as 1800 MHz

h(ms)= 1.2 m

h(bs)= 25 m

Medium/small size (i=2)

a2 = 0.8 + (1.1 log (f) 0.7)hms 1.56 log (f)

a2 = -0.8213

Sub urban (i=3)

a3 = a2 + 2(log (f/28))2 + 5.4

a3 = 11.1173

Rural (i=4)

a4 = a2 + 4.78 (log (f))2 18.3 log (f) + 40.9

a4 = 31.1599

By using COST 231 extension of Okumura-Hata model, the radius covered by each cell site is

calculated as

r(rural) = 18.47 km

r(sub urban) = 2.07 km

r(city) = 1.24 km

Area type Radius of cell

(r)

Area of cell

(33 r2)/ 2 Coverage

area of cell

(km2)

Cell sites Cost of cell

sites

Rural 18.47 886.3101 2199.92 2.4821= 3 300 x 103

Sub urban 2.07 11.1325 556.95 50.0292= 51 3000 x 103

Urban 1.24 3.9948 213.26 53.3844= 54 21350 x 103

Conclusion: More cell sites are needed in dense areas as compared to rural areas.

3) Network Capacity Provision Part:

Population in Kauniainen municipality = 9039

Market share of the mobile operator (Nu) = 55% of the population = 4971

Arrival rates for voice calls = v = k1 Nu = 1.7 104 4971 = 3.4797 per second Arrival rates for data services = D = k2 Nu = 8.9 103 4971 = 0.627 per second

Service type Minimum rate (r) Arrival rate () Duration () Total throughput = r

Data service 500 kbps 0.627 per sec 365 sec 114427.5 kbps

Voice service 16 kbps 3.479 per sec 75 sec 4175.64 kbps

Sum Total Throughput 118.6 Mbps

Area of Kauniainen municipality = 5.88 km2

Throughput density = 118.6 / 5.88 = 20.17 Mbps per km2

Calculation of SIR at cell edge:

For Transmitted power, P; Transmitter gain, G; Radius of cell, r km and propagation loss exponent

() = 2.5

= 0.0277 (linear) = -15.57 db

Since EIRP is same for all base stations, SIR at cell edge does not depend on cell radius.

Spectral efficiency:

= A log2 (1 + B SIR) [bps/Hz]

A = 0.88 , B = 0.8, SIRi = -7.57 db

= 0.1662

W = 10 MHz

Throughput (TP) = W = 1.6622 Mbps

TPdensity= TP/(Cell area)

Cell area = TP / TPdensity = 1.6622 / 20.17 = 0.0824 sq. km

Cell radius = 0.1781 km

Cell number Distance of MS

from base station

(d)

Average path loss

Lo + 10log10(d-

)

1 r L1= Lo + 10log10((r)-

)

2 r L2 = L2= Lo + 10log10((r)-

)

3 2r L3= Lo + 10log10((2r)-

)

4 (7)r L4= Lo + 10log10(((7)r)-

)

5 (7)r L5= L4= Lo + 10log10(((7)r)-

)

6 2r L6=L3= Lo + 10log10((2r)-

)

7 r L7= L2= Lo + 10log10((r)-

)

Impact of propagation loss exponent ():

Spectral efficiency Throughput (Mbps) Cell radius (km)

2 0.2559 2.423 0.2150 2.5 0.1662 1.6622 0.1781

3 0.1113 1.113 0.1457

3.5 0.0733 0.7334 0.1183

4 0.0476 0.4764 0.0953

Conclusion:If the value for path loss exponent is more, spectral efficiency is less. Hence,

throughput comes out to be less and same is the case for the cell radius.

Since single cell reuse and omni directional antennas are considered in all cell sites, interference at

cell edge is more and hence, SIR would be less.

References

[1] H.Holma & A.Toskala, WCDMA for UMTS: HSPA Evolution and LTE, John Wiley & Sons, 2010

[2] H.Holma & A.Toskala, LTE for UMTS: OFDMA and SC-FDMA based radio access, John Wiley & Sons, 2009

[3] https://sites.google.com/site/lteencyclopedia/lte-radio-link-budgeting-and-rf-planning/lte-link-

budget-comparison

[4] http://www.comlab.hut.fi/opetus/4210/presentations/16_wcdma_rnp.pdf