Radio Network Planning Part1

I.Objective of this lesson :

1.Main topics :

a).Able to understand GSM Network Planning from the point of view of a BSS engineer.
b).Able to understand the flow of GSM Network Planning from the point of view of a BSS engineer.

2.Sub-topics :
-Characteristic of radio mobile communication network
-Radio wave broadcast path
-Mutil-path and loss
-Electromagnetic propagation loss
-Model of Coverage prediction
-Propagation model
-Receive level design
-Antenna concept and classification
-Distributed system
-Antenna guideline
-Types pf Diversity
-Steps of GSM Network planning
-Subtopics ( continue )
-Work involved in GSM Network planning
-Key points in planning
-Coverage planning
-Link budget
-Coverage of special area
-Antenna selection
-Cell layer design
-Capability planning
-Site survey
-Frequency planning

II.Network planning introduction

Brief introduction of this chapter content

- Characteristic of radio communication
- Radio wave broadcast path、mutil-path and loss
- Design of serving cell’s level
- Antenna
- Diversity

RADIO NETWORK DESIGN 1

RND ACTIVITIES

INDOOR NETWORK DESIGN 1

III.Characteristic of radio mobile communication network

- Subscriber’s Mobile character
- Complexity of radio propagation
- Frequency efficiency

It is required that the MS be in the 90% of the service area. It is also required that 99% of the time be able to access the network.

GSM use Electromagnectic Waves to propagate the information. When tight frequency-reuse is used in high capacity network, interference has become an important factor that influence the network performance.

1. Radio wave broadcast path

The multiple path reflection of the signal strength may cause the fast fading symtoms. This multiple path’s phase difference may sometime cancel the signal thus causing this fast fading symtoms.
The green part of the diagram are the part that cause fast fading. If the MS were in the green part of the diagram,then the SS will be very weak.

We use frequency hopping to counter fight the above fading problem.

2.Mutil-path and loss

Signal Strength differ according to the position of the MS. We call this as fading. There are 2 types of fading – fast fading and slow fading.

When signal strength drop gradually as the distance from the Base Station increase, this type of fading, we call slow fading.

Slow fading characteristics
1)SS drops as the distance from Base Station increase.
2)Slow fading is not relation with time.
3)Slow fading is forseeable

Fast fading characteristics
1)On a certain spot, there may be a sharp decrease in SS, we call this fast fading or short term fading.
2)SS drops sharply causing sharp fading dips

3.Electromagnetic propagation loss

- Freedom space propagating fading L(dB)=32.4+20lg(fMHz)+20lg(Dkm)
- Dispersion decade of no plainly ground
- Obstacle cause rounding loss
- Propagation medium loss
- Penetration fading
- Indoor propagating fading

4.Model of Coverage prediction

+ Propagation Models Used in GSM

- Okumura/Hata model
.Apply to Macrocell,900M
- COST231-Hata model
.Apply to Macrocell,1800M
- COST231 Walfish-Ikegami model
.Apply to Microcell,900Mand 1800M
- The model is used in planning tool-ASSET
.Apply to Microcell, 900Mand 1800M

+Propagation model

Formula for Propagation Loss :

In the above formula :

Coefficiency constant that are related with frequency :

Urban:k1=69.55+26.16log(Fc) {Fc=900,1800}( urban )
Suburban:K1=69.55+26.16log(Fc)－2[log(Fc/28)]2-5.4 ) {Fc=900,1800} ( suburban )
Open Area:k1=69.55+26.16log(Fc)-4.78[log(Fc)]2+18.33log(Fc)-40.94 ) {Fc=900,1800} ( Open area )

When doing analysis for different terrains, the values of K may differ. The following slide shows a typical K values that are used in a medium-sized city.

Coefficiency used in the above formula

K constants that are used in the nominal cell planning.

5.Receive level design

Receive Level :

IV.Antenna concept and classification

- Base on wave bandwidth
-->30、60、90、120、omni。
- Base on 900，1800，double- frequency band
- Base on polarization
-->Single polarization、double polarization

1.Distributed system

There are 2 types of Distruibuted system :

Radiating cable :
The fading loss in radiating cable is great. This radiating cable is typical used in tunnels and interior of the buildings. The price of radiating cable is high.

2.Antenna Guideline

- Gain and directional drawing
- Frequency band
- Downtilt
- Return loss
- Impedance
- Max transmitting power
- Polarization mode
- Downtilt precision

3.Types of Diversity

- Space Diversity
- Time Diversity
- Frequency Diversity
- Multipath Diversity
- Polarization Diversity

The gain in diversity can improve coverage.
Proper plan in link budget can withstand more path losses.

IV.Location of Network Planning

Indicate where is our scope of work as a Cell Planner and Cell Optimizer.

The macro view of GSM network planning is divided into 2 parts – Planning and Optimization. It is a cyclic action throughout the network expansion.
The micro view of GSM network planning involved the planning work. It involves at the pre-installation phase.

1.Steps of GSM Network planning

The left oval shape depict the work done in the initial planning and site survey. Data collected in the left oval shape is input into the middle oval shape. Using the 3-D digital map as the basis, the middle oval provide 5 outputs.

The outputs of the middle oval shape confirm the configurations for our right oval shape’s design.

To be continue

Please continue read at Radio Network Planning Part2