Radio network planning

RADIO NETWORK DESIGN 1
 

RND   ACTIVITIES

For the radio Network design are : Firstly Normal Cell planning Tool asset,In this part device into 3 parts : (1) RF Measurements(RFM), (2) Propagation Model Optimission(PMO),(3) Capacity Dimensioning(CD). In Capacity Dimensioning part should have RF Site surveys(SS) before we do something,then Final cell Planning(FCP),after Final Cell Planning preparing the Frequency Planning and Cell Parameter Planning(CPP),then Initial Tuning(IT) ,the last is Acceptance Tests(AT).

INDOOR NETWORK DESIGN 1

 The Indoor Network design are:
Firstly we need to design the coverage and capacity demands then Capacity dimensioning(CD) after this it should have Nominal Antenna & BTS System(NABS),after Site Surveys finished the RF Measurements of indoor is comming,then Final Antenna Configuration next step is Frequency Planning(FP) ,then Cell Parameter Planning(CPP),after this is Tuning & Optimisation(TO) the last step Acceptance Tests(AT).

 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 Electromagnetic 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.

Radio wave broadcast path

1.Forward wave  and Earth reflection wave（normal propagation model）,Please see figure as below:

2.Troposphere lay reflection radio wave（propagation with the random）,Please see figure as below:

3.Mountain diffracted wave（signal origin of shadow area）,Please see the figure as below:

4.Ionosphere reflection radio wave（over sight communication approach）,Please see the figure as below:

Radio wave broadcast path

The multiple path reflection of the signal strength may cause the fast fading symptom.  This multiple path’s phase difference may sometime cancel the signal thus causing this fast fading symptoms.

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.

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

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

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.

Propagation model 

Coefficiency used in the above formula :

 

K constants that are used in the nominal cell planning.

Receive level design

Receive Level :

Application Environment:

-Handset Receiving in buildings : The minimum receiving power is -70 dBm : 

Handset sensitivity: -102 dBm,fast attenuation protection:3dB, slow attenuation protection(indoors): 7dB
(the standard devitation of slow attenuation is 7 dB indoors and 8 dB outdoors, and the call successful rate in the
coverage area is 90%), penetration loss:18 dB, interference noise :2dB, environment noise protection : 2 dB.

-Handset receiving in car or a first floor room in a building: The minimum receiving power is -80 dBm :Handset sensitivity: -102 dBm,fast attenuation protection:3dB, slow attenuation protection: 5 dB (Call successful rate in the coverage area is 90%)
 penetration loss:10 dB, interference noise :2dB, environment noise protection  : 2 dB.

-Handset receiving outdoor : The minimum receiving power is -90 dBm 

Handset sensitivity: -102 dBm,fast attenuation protection:3dB, slow attenuation protection: 5 dB (Call successful rate in the coverage area is 90%)
, interference noise :2dB, environment noise protection  : 2 dB.

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

Distributed  system

 

-leakage cable 

 

 

 

 

-Distributed antenna

 

 

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.  

 Antenna guideline

•Gain and directional drawing

•frequency band

•downtilt

•return loss

•impedance

max transmitting power

•Polarization mode

•downtilt precision

 Types pf Diversity
-Signal 1

-Signal 2

-Signal 3

•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.