110499697 Microwave Principle and Equipment

Microwave Principle and Equipment ZTE University

Contents 

Microwave Equipments Application    



Application/Solution Mobile Network Application Cellular Network Application Ethernet Application

Microwave Communication Principles  ZTE Microwave Product  Microwave Future Evolution

Application/Solution Point to Point Digital Microwave transmission system

Coaxial cable Microwave link

MUX

MUX

Satellite

Fiber optic cable

Mobile Network Application SDH

SDH

PDH

.....

BTS

PDH

MSC

BTS

PDH PDH

BTS

BTS

BTS

BTS

PDH

BTS BTS PSTN

MSC

BSC

SDH

SDH

BSC

SDH

PDH

SDH Microwave PDH Microwave

BTS

BTS BTS

SDH PSTN: Public Switched Telephone Network MSC: Mobile Switching Center BSC: Base Station Controller BTS: Base Transceiver Station

BTS

BTS

BTS

BSC

SDH

BTS BTS

BTS

PDH

BSC BTS

PDH PDH BTS

BTS

BTS

BTS

PDH

BTS

Cellular Network Application （1）

UMTS: Universal Mobile Telecommunication System

Cellular Network Application（2）

RNC: Regional Network Centre ADM: Add/Drop Multiplexer MUX: Multiplexer STM: Synchronous Transport Module

Ethernet Application(1) LAN to LAN Bridge

Ethernet Application(2)

Ethernet Application(3)

Review 

What are the main transmission methods nowadays?  What are the main applications for microwave equipments?

Contents 

Microwave Equipments Application  Microwave Communication Principles 





Introduction to Microwave Principles System Structure

ZTE Microwave Product  Microwave Future Evolution

Introduction to Microwave Principles   

  

  

Different Transmission Systems Microwave Frequency Features of Radio Transmission Radio Frequency Spectrum Utilization Radio Wave Propagation Fading Interference Microwave Radio Link Relay station (Passive)

Different Transmission Systems Coaxial cable

Microwave link

MUX

MUX

Satellite

Fiber optic cable

Microwave Frequency Frequency: 300MHZ～ 300GHZ

Frequency band: UHF: 0.3-1.12G KU: 12.4-18G S: 2.6-3.95 G U: 40-60G

LF

MF

HF

VHF

Wavelength: 1m~1mm

X: 8.2-12.4G LS: 1.7-2.6 G Ka: 26.5-40G XC: 5.85-8.2G

UHF

SHF

L: 1.12-1.7G K: 18-26G C: 3.95-5.85G

EHF

microwave



10Km

1Km

100m

10m

f

30KHz

300KHz

3MHz

30MHz

1m 300MHz

10cm 3GHz

1cm 30GHz

1mm 300GHz

Features of Radio transmission 1

Wavelength is short while frequency is high.

2

Wide frequency band

3

Line of sight propagation, reflection, diffraction and scattering

4

Free space loss

5

Fading caused by other types of path loss.

6

Interference

Radio Frequency Spectrum Utilization （1）

Regional network 1.5 2.5

2 8 34 Mbit/s

3.3 11 GHz National backbone network Regional and local network

34 140 155 Mbit/s

1

2

3

4

5

2 8 34 140 155 Mbit/s 8

10

20

GHz 30

40

50

Radio Frequency Spectrum Utilization （2） Low frequency band

High frequency band

Channel number 1

2

n

1'

2'

n'

F3

Fo Frequency F1 F2 Band width Fo: Center frequency

Radio Wave Propagation （1） The radio link propagation follows the line of sight: it requires a perfect clearing between transmitting and receiving antennas. The propagation medium is made of the lower layers of the atmosphere (a few meters to a few hundred of meters above ground)

The non homogeneity of the atmosphere influences the waves propagation: 1°) Path curvature 2°) Reflecting, diverging, focusing intermittent events Free space loss (Lfs)=92.4+20×log(f×d) (dB) f:GHz, d:km

Radio Wave Propagation （2） Atmosphere influence

Refraction

Partial reflection

Absorption Gaz and water vapor

Diffusion Diffusion volume

n2

n2

Frequ. < 15 GHz : insignificant 20 GHz : 0.1 dB / km

i.2

Rain i.1

n1

n1

Frequ. > ?10 GHzo

500Km

n1×sin i.1 = n2×sin i.2

Almost horizontal

Radio Wave Propagation （3） Ground influence

Diffraction Reflection

Diffraction on a ridge

Spherical diffraction

Radio Wave Propagation （4） Air refraction index at sea level: n = 1.000 315 N

N = 315 N units

h

Standard atmosphere

h

Ro Real Earth

N = - 39 N.units Km

K = R/Ro = 4/3

R Imaginary Earth

N : Gradient of air refraction index

N may reach more extreme values than + 250 or - 350, during short percentage of time

An imaginary earth with the radius of 8500km, allows to simplify analysis on Refraction propagation of radio wave.

Fading Causes Types Selective Fading Rain and Snow Fading Anti-Fading Measures

Causes Causes of fading ：

1

Changes of transmitting media

2

Reflection

3

Atmosphere

4

Rain

Types 1

Fast fading and slow fading

2

Up fading and down fading

3

Frequency selective fading and flat fading

Selective Fading Multi-path propagation

Cause：

Refraction

Reflection

A1 A

A 2 ,T A 1 ,T

1

Receiver

Transmitter F=

1

= A

T =

A max

A min

Frequency A1 -A2 A1+ A

For A1 = A2

2

2

2

-T A2 A1

F F0

Radio channel

2

8

A max dB = + 6 A min dB = -

< 1 minimal-phase fading > 1 non-minimal phase fading

The direct signal is larger than the reflected signal

1

Rain and Snow Fading Main cause ：

frequencies > 10 GHz -80 < Pr < -20 dBm Receiver

Demodulator

A

B FI

CAG

Digital signal Transmitter dBm

dBm

IF Level 0 dBr ?2dB?

A IF

W0 Noise

B Signal

W Time

Noise

C N

Time

Anti-Fading Measures Techniques without diversity

1

Reduce ground reflection

2

Increase path consistency

3

Various equalizers

H

Diversity techniques 1

Frequency Diversity

2

Space Diversity

10.2/F0/2