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HUAWEI TECHNOLOGIES CO., LTD.
www.huawei.com
Huawei Confidential
Security Level:INTERNAL 23/4/8
英文标题 :40-47pt
副标题 :26-30pt
字体颜色 : 反白内部使用字体 :
FrutigerNext LT Medium
外部使用字体 : Arial
中文标题 :35-47pt
字体 : 黑体 副标题 :24-28pt
字体颜色 : 反白字体 : 细黑体
Digital Microwave Communication
Principles
Page 2Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved. Page 2Page 2
Foreword
This course is developed to meet the requirement of Huawei
Optical Network RTN microwave products.
This course informs engineers of the basics on digital microwave
communications, which will pave the way for learning the RTN
series microwave products later.
Page 3Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved. Page 3Page 3
ObjectivesObjectives
After this course, you will be able to explain:
Concept and characteristics of digital microwave
communications
Functions and principles of each component of digital
microwave equipment
Common networking modes and application scenarios
of digital microwave equipment
Page 4Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved. Page 4Page 4
Contents
1. Digital Microwave Communication Overview
2. Digital Microwave Communication Equipment
Page 5Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved. Page 5Page 5
Transmission Methods in Current Communications Networks
Optical fiber communication
Microwave communication
Satellite communication
MUX/DEMUX MUX/DEMUX
Micro
wave T
E
Micro
wave T
E
Coaxial cable communication
Page 6Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved. Page 6Page 6
Definition of Microwave Microwave
Microwave is a kind of electromagnetic wave. In a broad
sense, the microwave frequency range is from 300 MHz to
300 GHz. But In microwave communication, the frequency
range is generally from 3 GHz to 30 GHz.
According to the characteristics of microwave propagation,
microwave can be considered as plane wave.
The plane wave has no electric field and magnetic field
longitudinal components along the propagation direction. The
electric field and magnetic field components are vertical to
the propagation direction. Therefore, it is called transverse
electromagnetic wave and TEM wave for short.
Page 7Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved. Page 7Page 7
Concept of Digital Microwave Communication
Digital microwave communication is a way of transmitting digital
information in atmosphere through microwave or radio frequency (RF).
Microwave communication refers to the communication that use microwave as
carrier .
Digital microwave communication refers to the microwave communication that
adopts the digital modulation.
The baseband signal is modulated to intermediate frequency (IF) first . Then
the intermediate frequency is converted into the microwave frequency.
The baseband signal can also be modulated directly to microwave frequency,
but only phase shift keying (PSK) modulation method is applicable.
The electromagnetic field theory is the basis on which the microwave
communication theory is developed.
Page 8Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved. Page 8Page 8
Microwave Frequency Band Selection and RF Channel Configuration (1)
Generally-used frequency bands in digital microwave transmission:
7G/8G/11G/13G/15G/18G/23G/26G/32G/38G (defined by ITU-R Recommendations)
85432 10
20
1 30
40
50
1.5 GHz
2.5 GHz
Long haul trunk
network2/8/34 Mbit/s
11 GHz
GHz
34/140/155 Mbit/s
2/8/34/140/155 Mbit/s
3.3 GHz
Regional network
Regional network, local network, and boundary
network
Page 9Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved. Page 9Page 9
Digital Microwave Communication Modulation (1)
Digital baseband signal is the unmodulated digital signal. The baseband signal cannot be directly transmitted over microwave radio channels and must be converted into carrier signal for microwave transmission.
Digital baseband signal IF signal
Base
band sig
nal
rate
Channel b
andw
idth
Modulation
Service signal
transmitted
Page 10Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved. Page 10Page 10
Questions
What is microwave?
What is digital microwave communication?
What are the frequently used digital microwave frequency bands?
What are the frequently used modulation schemes? Which are the most frequently used modulation schemes?
Page 11Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved. Page 11Page 11
Contents
1. Digital Microwave Communication Overview
2. Digital Microwave Communication Equipment
3. Digital Microwave Networking and Application
Page 12Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved. Page 12Page 12
Microwave Equipment Category
System Digital microwave
PDH SDH
Split-mount radio
Trunk radio
All outdoor radio
Small and medium capacity (2–16E1,
34M)
Large capacity (STM-0, STM-1, 2xSTM-
1)Capacity
Structure
(Discontinued)
Analog microwave
MUX/DEMUX Mode
Page 13Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved. Page 13Page 13
Trunk Microwave Equipment
• High cost, large transmission capacity, more stable performance, applicable to long haul and trunk transmission
• RF, IF, signal processing, and MUX/DEMUX units are all indoor. Only the antenna system is outdoor.
SDH microwave equipment
BRU: Branch RF Unit
MSTU: Main Signal Transmission Unit (transceiver, modem, SDH electrical interface, hitless switching)
SCSU: Supervision, Control and Switching Unit
BBIU: Baseband Interface Unit (option) (STM-1 optical interface, C4 PDH interface)
P
M1
M2
……
Page 14Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved. Page 14Page 14
All Outdoor Microwave Equipment
• All the units are outdoor.
• Installation is easy.
• The equipment room can be saved.
All outdoor microwave equipment
IF and baseband processing unit
IF cable
RF processing unit
Service and power cable
Page 15Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved. Page 15Page 15
Split-Mount Microwave Equipment (1) The RF unit is an outdoor unit
(ODU). The IF, signal processing,
and MUX/DEMUX units are
integrated in the indoor unit
(IDU). The ODU and IDU are
connected through an IF cable.
The ODU can either be directly
mounted onto the antenna or
connected to the antenna
through a short soft waveguide.
Although the capacity is smaller
than the trunk, due to the easy
installation and maintenance, fast
network construction, it’s the
most widely used microwave
equipment.
Split-mount microwave equipment
Antenna
ODU (Outdoor
Unit)
IF cable
IDU (Indoor Unit)
Page 16Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved. Page 16Page 16
Split-Mount Microwave Equipment (2)
Unit Functions
Antenna: Focuses the RF signals transmitted by ODUs and increases the signal g
ain.
ODU: RF processing, conversion of IF/RF signals.
IF cable: Transmitting of IF signal, management signal and power supply of OD
U.
IDU: Performs access, dispatch, multiplex/demultiplex, and modulation/demod
ulation for services.
Page 17Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved. Page 17Page 17
Split-Mount Microwave Equipment – Installation
antenna (separate mount)
ODU
IF cable
中频口
Separate Mount
Soft waveguide
IDU IF port
antenna (direct mount)
ODU
IDU
Direct Mount
IF cable
IF port
Page 18Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved. Page 18Page 18
Microwave Antenna (1)
Antennas are used to send and receive microwave signals.
Parabolic antennas and cassegrainian antennas are two common types of
microwave antennas.
Microwave antenna diameters includes: 0.3m, 0.6m, 1.2m, 1.8m,2.0m, 2.4m, 3.0m,
3.2metc.
Parabolic antenna Cassegrainian antenna
Page 19Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved. Page 19Page 19
Different frequency channels in same frequency band can share one antenna.
Microwave Antenna (2)
TxRx
TxRx
Channel
Channel
1
1
n
n
1
1
n
n
Page 20Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved. Page 20Page 20
Antenna Adjustment (1)
Side view Side lobe
Main lobeHalf-power angle Tail lobe
Top view
Main lobe
Side lobe
Half-power angle Tail lobe
Page 21Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved. Page 21Page 21
During antenna adjustment, change the direction vertically or horizontally. Meanwhile, use a multimeter to test the RSSI at the receiving end. Usually, the voltage wave will be displayed as shown in the lower right corner. The peak point of the voltage wave indicates the main lobe position in the vertical or horizontal direction. Large-scope adjustment is unnecessary. Perform fine adjustment on the antenna to the peak voltage point.
When antennas are poorly aligned, a small voltage may be detected in one direction. In this case, perform coarse adjustment on the antennas at both ends, so that the antennas are roughly aligned.
The antennas at both ends that are well aligned face a little bit upward. Though 1–2 dB is lost, reflection interference will be avoided.
Antenna Adjustment (2)Antenna Adjustment (2)
Side lobe position
AGCVoltage
detection point
VAGC
Main lobe position
Angle
Page 22Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved. Page 22Page 22
Antenna Adjustment (3)Antenna Adjustment (3)
During antenna adjustment, the
two wrong adjustment cases are
show here. One antenna is aligned
to another antenna through the side
lobe. As a result, the RSSI cannot
meet the requirements.
CorrectWrongWrong
Page 23Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved. Page 23Page 23
Specifications of Transmitter
Working frequency band
Generally, trunk radios use 6, 7, and 8 GHz frequency bands. 11, 13 GHz and
higher frequency bands are used in the access layer (e.g. BTS access).
Output power
The power at the output port of a transmitter. Generally, the output power is
15 to
30 dBm.
Split-Mount Microwave Equipment – ODU (2)
Page 24Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved. Page 24Page 24
Questions
What types are microwave equipment classified into?
What units do the split-mount microwave equipment have? And what are their functions??
How to adjust antennas?
Page 25Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved. Page 25Page 25
Summary
Classification of digital microwave equipment
Components of split-mount microwave equipment and
their functions
Antenna installation and key specifications of antennas
Functional modules and key performance indexes of
ODU
Functional modules of IDU
Page 26Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved. Page 26Page 26
Contents
1. Digital Microwave Communication Overview
2. Digital Microwave Communication Equipment
3. Digital Microwave Networking and Application
Page 27Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved. Page 27Page 27
Common Networking Modes of Digital Microwave
Ring network Chain network
Add/Drop network
Hub network
Page 28Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved. Page 28Page 28
Application of Digital Microwave
Complementary networks to optical networks (access the services from
the last 1 km)
BTS backhaul transmission
Redundancy backup of
important links
VIP customer access
Emergency communications
(conventions, activities, danger
elimination, disaster relief, etc.)
Special transmission conditions (rivers,
lakes, islands, etc.)
Microwave Microwave applicationapplication
Page 29Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved. Page 29Page 29
Questions
What are the networking modes frequently used for digital
microwave?
What are the types of digital microwave stations?
What is the major application of digital microwave?
Page 30Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved. Page 30Page 30
Protection Modes of Digital Microwave Equipment (1)
With one hybrid coupler added between two ODUs and the antenna, the 1+1 HSB can be realized in the configuration of one antenna. Moreover, the FD technology can also be adopted.
The 1+1 HSB can also be realized in the configuration of two antennas. In this case, the FD and SD technologies can both be adopted, which improves the system availability.
Hybrid coupler
Page 31Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved. Page 31Page 31
N+1 (N≤3, 7, 11) Protection
In the following figure, Mn stands for the active channel and P stands for the standby channel. The active channel and the standby channel have their independent modulation/demodulation unit and signal transmitting /receiving unit.
When the fault or fading occurs in the active channel, the signal is switched to the standby channel. The channel backup is an inter-frequency backup. This protection mode (FD) is mainly used in the all indoor microwave equipment.
Products of different vendors support different specifications.
Protection Modes of Digital Microwave Equipment (2)
Switching control unit
Switching control unitRFSOH
PP
MM11
MM22
MM33
PP
MM11
MM22
MM33
chch11
chch22
chchPP
chch33
chch11
chch22
chchPP
chch33
Page 32Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved. Page 32Page 32
Protection Modes of Digital Microwave Equipment (3)
Configuration
Protection ModeRemark
sApplication
1+0 NP Non-protection Terminal of the network
1+1 FD Channel protection Inter-frequency Select the proper
mode depending on the geographical
condition and requirements of the
customer
1+1 SD Equipment protection and channel protection
Intra-frequency
1+1 FD+SD Equipment protection and channel protection
Inter-frequency
N+1 FD Equipment protection and channel protection
Inter-frequency
Large-capacity backbone network
Page 33Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved. Page 33Page 33
Questions
What protection modes are available for the microwave?
Thank youwww.huawei.com