basics of microwave communication 1231
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MICROWAVE BASICSTRANSCRIPT
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Guide
Name Basics of Microwave Communication
Contents What Is Microwave Communication?
Technologies and Terms Learned from a Quotation
How Far Can Microwave Reach?
Future of Microwave Communication
3ms Link
Problem
Feedback
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Huawei Confidential
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23/4/8
By Transmission Network Marketing Support Dept.
Basics of Microwave Communication
HUAWEI TECHNOLOGIES CO., LTD. Huawei Confidential Page 3
Contents
What Is Microwave Communication?
Technologies and Terms Learned from a BOQ
How Far Can Microwave Reach?
Evolution Trend of Microwave Communication
11
22
33
44
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Microwave: A Tiny and Invisible Electromagnetic Wave
Page 4
Microwave: a tiny member of electromagnetic wave family• The wavelength of microwave ranges from 1 mm to 1 m. Microwave is tiny when it is compared with other members of
the family.• The frequency of microwave ranges from 300 MHz to 300 GHz. Therefore, the microwave is invisible to human eyes.
Microwave transmission: Microwave, like water waves, will be blocked.• Microwave can be blocked by objects which size are similar or greater than microwave length. • Wavelength = Velocity of light / Frequency
1mm 1m
Microwave
Microwave oven
Microwave communication
Microwave usually refers to microwave communication
radial
X radial
ultraviolet radiation
Visible Light infrared
ray
Radio music
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Microwave Communication Is One of Transmission Modes
Page 5
Fibers Microwave Satellite cables
Definition: a means of signal transmission using microwave as the signal carrierFrequency: a part of microwave frequency are used for microwave communication
• Usually band: 3 GHz to 42 GHz• E-band: 71 GHz to 86 GHz
Transmission mode: sight transmission
Definition: a means of signal transmission using microwave as the signal carrierFrequency: a part of microwave frequency are used for microwave communication
• Usually band: 3 GHz to 42 GHz• E-band: 71 GHz to 86 GHz
Transmission mode: sight transmission
Microwave communication
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Microwave VS. Fibers
Page 6
Regional communications, suitable for mountainous areas, forests, cities, and other regions
Resistance to natural disasters, fast restoration
Low investment, short construction period
secrecy
Microwave
Fibers
Service is affected by climate and terrains
Limited frequency resources, requirements for frequency licenses
Smaller transmission capacities (compared with fibers)
Short construction
period
Large transmission capacities, strong networking capabilities
Stable transmission quality, resistance to the effects of climate and terrains
Long transmission distances
Microwave's advantages Fibers' advantages
Microwave's disadvantages Fibers' disadvantages
Long construction period, high costs on laying fibers, especially on complex terrains
Occupation of a large land area
Large transmission
capacity
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Appearances and Features of Microwave Equipment
RF/IF and baseband unitSignal
processing unit
Multiplexer
High cost, large transmission capacity, stable transmission quality
Applications to long-distance trunk transmission
No requirement for space in telecommunications rooms, unstable transmission quality, transmission of limited types of services
Applications to metropolitan short-distance transmission
Convenient installation and maintenance, fast network construction
Most widely-applied microwave equipment, applications to transmission medium distances,
and short distances
RF unit
Service and power cable
RF unit
Antenna
IF cable
IDUIDU
Page 7
Full indoor microwave Full indoor microwave equipmentequipment
FullFull outdooroutdoor microwavemicrowave equipmentequipment
Split microwave Split microwave equipmentequipment
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Microwave Transmission: Convert Baseband Signal to RF Signal
Page 8
IDU: indoor unit
• Receives signals (FE/GE/STM-1/E1) from the user side.
• Cross-connects the received signals (like what the optical transmission equipment does).
• Converts basebase signals to IF signals by means of modulation and amplification.
ODU: outdoor unit
• Converts IF signals to RF signals by means of frequency translation, power amplification, and filtering.
• ODU is the essential part of microwave equipment.
Antenna
• Converts RF signals to electromagnetic wave.
Waveguide or RF cable
(separate Mounted)
No feeder needed
(directly mounted)
调制 上变
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ilterin
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Mo
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Up
Co
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Fre
qu
en
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Po
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plifica
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Baseband Baseband signalsignal
IF IF signalsignal RF RF
signalsignal ElectromagElectromagnetic wavenetic wave
调制
Cro
ss-con
ne
ction
IDU ODU Antenna
IF a
mp
lificatio
n
IF cable
The signal conversion process in the receive direction is reverse to that in the transmit direction.
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Applications of Microwave Communication
Backup and supplementary communication resources of fiber links
Backhaul transmission of base station services in mobile communication
Comprehensive service transmission at the tail of fixed networks
Railway and expressway
Water conservancy electricity
Petroleum, harbors Radio and
television, finance
Telecom Operators
Private Networks
HUAWEI TECHNOLOGIES CO., LTD. Huawei Confidential Page 10
Contents
What Is Microwave Communication?
Technologies and Terms Learned from a BOQ
How Far Can Microwave Reach?
Evolution Trend of Microwave Communication
11
22
33
44
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Technologies and Terms Learned from a BOQ
Page 11
ItemPrice(per
hop)Quantity
Total Price
8G STM-1 1+1SD 0.6m With RTN610_620(16E1 (75 ohm) )
3
15G 1+0 0.6m With RTN605(1E_ 2*FE/2*GE/16*E1 ) 1
8G 400M 1+0 XPIC 0.6m With RTN910( 2*FE/2*GE ) 2
13G 200M 3+0 0.6m With RTN950(1*(4FE(RJ45)+2GE(RJ45)) 1*16*E1 )
1
Total Price
1
2
4
3
5
6
7
Service interface : 16E1 (75 ohm)
Equipment Type : RTN610_620
Antenna Size : 0.6m
RF Configuration : 1+1SD
Radio Interface Capacity :STM-1
Frequency Band : 8G
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8G: One of the Operating Frequency Bands (for Long-Distance Transmission)
Page 12
The ITU-R recommendations specify the following common frequency bands for
microwave communication: 4/5/6/7/8/11/13/15/18/23/26/28/32/38/42 GHz.
Frequency band is the necessary information for selecting ODU and antenna.
854 11
Long-distance trunk transmission
3.3 11
GHz6 7
Medium-distance/Short-distance transmission
18 23 3826
City short-distance transmission
13 15
1823
42
8G STM-1 1+1SD 0.6m With RTN610_620(16E1 (75 ohm) )1
1
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Frequency Arrangement Principles
Page 13
8 GHz f0 (MHz)T/R Spacing
(MHz)
Channel Spacing
(MHz)
Number of Working
Channels (n)
7725--8275 8000 311.32 14 8
f0: center frequency
For example: 8 GHz
Channel spacing: difference between the center frequencies of Adjacent channels, for example, 3.5/7/14/28/56 MHz. Channel spacing is specified depending on services.
High/Low station: A high station and a low station must be used in pairs. The station with a higher transmit frequency is a high station and the station with a lower transmit frequency is a low station.
T/R spacing: difference between the transmit frequency and receive frequency of an ODU.
f0
Bandwidth of the frequency band
Channel spacing
f1 f2fn f1
’ f2’ fn
’
T/R spacingT/R spacing
Frequency band of the low station
Frequency band of the high station
Edge protection margin
n: number of channels in the frequency band
Channel spacing
8G STM-1 1+1SD 0.6m With RTN610_620(16E1 (75 ohm) )1
1
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400M: Radio Interface Capacity (Determined by Channel Spacing and Modulation Mode)
Page 14
radio interface Capacity : service transmission capacity in the air
Receive endTransmit end
400 Mbit/s: channel spacing is 56 MHz modulation scheme is 256QAM The radio interface can transmit 400 Mbits
services
数字基带信号 中频信号Channel spacing
56 Mbit/s
基带信号速率
Channel spacing256QAM modulation
Services of a total rate of 400 Mbit/s
A greater channel spacing , a higher modulation scheme then a higher radio interface capacity
Customer services
8G 400M 1+0 XPIC 0.6m With RTN910( 2*FE/2*GE22
Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved. Page 15Page 15
Modulation Principles
A*COS (Wc*t+φ )
Amplitude Frequency Phase
The RF signals converted from digital baseband signals can be indicated by the following formula:
Modulation Scheme Carrier modulated Parameters Carrier unmodulatled
Parameters
QAM A, φ Wc
PSK φ A, Wc
ASK A Wc , φ
PSK φ A, Wc
8G 400M 1+0 XPIC 0.6m With RTN910( 2*FE/2*GE2
2
Digital microwave communication
usually adopts PSK and QAM modulation schemes.
Demodulation is the reverse process of modulation.
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Page 16
Common Microwave Modulation SchemesPSK
PSK: Digital information is represented by the phase changes of
carriers.
The common PSK modulation schemes include 2PSK, 4PSK,
and 8PSK. 4PSK is also QPSK.K
The highest PSK modulation scheme is 8PSK. For more efficient
bandwidth utilization, QAM modulation schemes are adopted.
Reference phase
11
1000
QPSK signal vectors (binary code)
01
16QAM signal vectors (quaternary code)
0010
0011
0110
0111
1110
1111
1010
1011
0001
0000
0101
0100
1101
1100
1001
1000
QAM
The QAM modulation schemes fully utilize the signal plane by
combining amplitude and phase modulation. In QAM modulation
schemes, the signal vectors are well distributed on the signal plane.
The common QAM modulation schemes include 4QAM, 16QAM,
32QAM, 64QAM, 128QAM, and 256QAM.
The QAM modulation schemes achieve high bandwidth utilization
efficiency. The 256QAM functions in octonary code.
Tips: In quaternary code, one point represents four bits. That is, 1 MHz can carry 4 Mbit/s traffic. (Service is less than 4 Mbit/s due to redundant bits.) The 16QAM modulation schemes is so called because the fourth power of two is 16. Do you understand why 256QAM is so called?
8G 400M 1+0 XPIC 0.6m With RTN910( 2*FE/2*GE2
2
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Adaptive Modulation (AM)
Page 17
Adaptive modulation (AM): By using the AM function, the microwave transmission system automatically changes the modulation scheme according to weather conditions.
This function ensures the most effective service transmission in any weather conditions.
256QAM ... 64QAM...QPSK...64QAM ... 256QAM
Voice
data
Tx Path
AM Engine
ChangeCommand
Rx Path
QualityIndicator
Rx Path
AM Engine
ChangeCommand
Tx Path
QualityIndicator
Data Sink
Data SinkData
Source
DataSource
IF Module IF ModuleWorking principles
8G 400M 1+0 XPIC 0.6m With RTN910( 2*FE/2*GE2
2
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0.6 m: Antenna Diameter
Page 18
Microwave antennas include parabolic antenna and Cassegrain antenna. The parabolic antenna is commonly used.
The common diameters of microwave antennas are 0.3 m, 0.6 m, 0.9 m, 1.2 m, 1.8 m, 2.4 m, 3.0 m, and 3.7 m.
Within one frequency band, N channels can be supported by one antenna.
Parabolic antenna Cassegrain antenna
Antenna
diameter.
Antenna
diameter
0.6m
Commonly used in microwave communication
15G 1+0 0.6m With RTN605(1E_ 2*FE/2*GE/16*E1 )33
Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved. Page 19Page 19
Antennas Main parameters Antenna gain:
Antenna gain indicates the concentricity of the energy radiated by an antenna.
Antenna gain is the ratio of the power of the antenna at a point in space to the power of an ideal
antenna (directionless) at the same point. The measurement unit is dBi.
GdB = 20lgf(GHz) + 20lgD(m) + 10lg η + 20.4dB
In this formula, η (antenna efficiency) = Antenna radiation power / Antenna input power If the frequency is specified, the antenna gain increases by 6 dB when the antenna diameter
doubles. If the antenna diameter is specified, the antenna gain also increases by 6 dB when the frequency
doubles.
15G 1+0 0.6m With RTN605(1E_ 2*FE/2*GE/16*E1 )33
3dB beam bandwidth angle:
Deviated from the center of the main lobe to one of the two sides, the half-
power (–3 dB) point appears when the detected power is reduced by half.
The angle between the two half-power points is called 3dB beam bandwidth
angle.
3dB beam bandwidth angle indicates the directivity of antennas. Larger
antenna diameter ,smaller 3dB beam bandwidth angle, better directivity, and
higher antenna gain.
3dB
-3dB
Main Lobe
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Page 20
Space diversity is more cost-effective and efficient that frequency diversity. Therefore, SD is used more often
than FD. FD applies when more channels are available.
FD: Frequency Diversity SD: Space Diversity
Hf1f1
f2f2
Application scenarios: Areas prone to fading, such as rivers and lakes.Working principle: One antenna transmits signals and two antennas receive signals. There is a low probability that both receive antennas are interfered simultaneously.Note: The distance between two receive antennas is determined by frequency bands.
Application scenarios: Areas where the weather changes frequentlyWorking principle: Two frequencies are used to transmit the same service. There is a low probability that both frequencies are interfered simultaneously.Note: Frequency spacing needs to be increased to reduce the correlation of different frequencies.
1+1 SD: Anti-Fading Diversity Technology The diversity technology is used to offset the effects of fading. To be specific, the system transmits the
same information over two or more paths and selects or combines the signals from the receiver.
Inter-antenna distance H: 100 times of wavelength to 200 times of wavelength
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Microwave Protection Schemes
Network management center
Ch5
Site6
Site 1Site 4
Site 7
Site 5
Ch32 km
Ch47km
6km
Ch86km
Site 2
Site
3
Ch16 km Ch2
5 km
Ch75km
Link-level protectionRF protection: 1+1 FD, SDService protection: LAG, N+1
Equipment-level equipment1+1HSB,System control unit 1+1Cross-connect and clock unit Input power 1+1
Network-level protectionTDM: SNCP, MSPETH: ERPS, MSTP
• Microwave equipment supports multiple protection schemes: link-level protection, equipment-level protection, and network-level protection.
• A combination of multiple protection schemes ensures 99.999% reliability of microwave equipment.
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XPIC: Cross-Polarization Interference Cancellation
Page 22
CCDP: Co-Channel Dual-Polarization
The transmit end transmits two electromagnetic waves whose polarization directions are orthogonal to each other. The receive end cancels interference between the two electromagnetic waves by means of the XPIC function, thus retrieving the two original signals.
The XPIC technology improves the utilization of frequency spectrum resources and thus doubles the transmission capacity.
6 GHz channel configuration without the XPIC 6 GHz channel configuration with the XPIC
Vertical polarization
Horizontal polarization
55 8G 400M 1+0 XPIC 0.6m With RTN910( 2*FE/2*GE )
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3+0: RF Configuration Mode
The commonly used configuration modes are N+0/1+1/N+1.
Page 23
RF Configuration Meaning Required Channels
Number of ODUs
Ax(N+M)
A: number of configuration groups > 0N: number of main links > 0M: number of standby links ≥ 0
N+M Ax(N+M)
1+11+1N+1 protection refers to the protection configuration that N microwave working channels in a microwave direction share one microwave protection channel.
2+12+1
1+1 protection schemes include 1+1 HSB/FD/SD. The above figure shows 1+1 HSB/FD.
3+0
66
13G 200M 3+0 0.6m With RTN950(1*(4FE(RJ45)+2GE(RJ45)) 1*16*E1 )
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Hop: Units of Radio Links
Page 24
One hop of radio link
• Hop: One hop of radio link includes the equipment at the two ends, and the equipment may be comprised of multiple IDUs, ODUs, and antennas.
• Microwave equipment is quoted and sold by hop.• The tree, chain, and ring topologies of microwave networks are all comprised of hops.• Networked microwave requires two hops of communal IDUs, which are called
combined stations. Combined stations help reduce the redundant IDUs.
7
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Contents
What Is Microwave Communication?
Technologies and Terms Learned from a BOQ
How Far Can Microwave Reach?
Evolution Trend of Microwave Communication
11
22
33
44
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Page 26
Factors That Affect Microwave Transmission Distances
• The microwave transmission distances ranges from 1 km to 100 km and the microwave transmission capacity reaches the GE level.
• Major factors: space loss, antenna gain, line loss, transmit power, and receive sensitivity Space loss is determined by the nature. Antenna gain, feeder loss, transmit power, and receive sensitivity are determined by the microwave equipment.
• (Transmit power – Receive sensitivity + Antenna gain – Feeder loss) - Space loss > 0 Network design reserves 30 dB as fade margin.
• Frequency bands, weather, terrains, equipment gain, and feeder loss affect microwave transmission distances.
Space loss
Transmission distance
Antenna gain
Transmit power Receive endTransmit end
Receive
sensitivity
Feeder loss
Antenna gain
Feeder loss
2
1
2
3 3
54
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Major Factors That Affect Space Loss
Space lossSpace loss
Free space loss
Obstacle and terrain
Weather (rain, snow, fog)
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Free Space Loss
• The attenuation of electromagnetic waves due to spreading in free space is called free space loss.
• Free space is the ideal vacuum space where electromagnetic waves do not generate reflection, refraction, scattering, and other physical phenomena.
Higher frequency band, lager Free space loss
Natural factors
Equipment factors
Free space Loss Ls (dB) = 92.4 + 20logF + 20logD
F: transmit frequency (unit: GHz)
D: transmission distance (unit: km)
For example: loss of transmission of 13 GHz signals over 20 km:
Ls = 92.4 + 22.3 + 26 = 140.7 (dB)
Page 29
Example: Loss of Signals at Different Frequencies in Air
Temperature = 30oCHumidity = 50%
Frequency (GHz)
0 25 50
0.4
Temperature = 40oC Humidity = 80%
1.0
23GHz
Loss in air(dB/Km)
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The terrains whose reflection coefficient is lower are more suitable for microwave transmission.
Obstacle and Terrain
Page 30
Straight line
Reflection
Impacts of Impacts of terrainsterrains
Inc
rea
sin
g re
flec
tion
co
effic
ien
tIn
cre
as
ing
refle
ctio
n c
oe
fficie
nt
Natural factors
Equipment factors
Category AMountains or cities with dense buildings
Category BHills
Category C Plains
Category DLarge-area water surface
Straight line
Reflection
Poor transmission Poor transmission quality!quality!
Impacts of Impacts of obstaclesobstacles
Good transmission Good transmission quality!quality!
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Weather (Snow, Rain, Fog)
Page 31
• Rain, snow, and fog are the major weather factors that affect microwave transmission.
Raindrops or ice causes scattering loss of microwave signals.
• Rain has the greatest impact on microwave transmission.
Microwave signals at frequencies lower than 10 GHz can hardly be affected by rain.
Microwave signals at frequencies higher than 10 GHz can be affected by rain;
the higher the frequency, the greater the rain fading.
• Snow and fog cause loss of about 0.5 dB/km for microwave signals.
Natural factors
Equipment factors
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Antenna gainThe lower the frequency band, the larger the antenna
diameter, and the higher the antenna gain.
Transmit power
The higher the transmit power, the longer the transmission distance.
Feeder loss The lower the frequency band, the shorter the feeder, and
the lower the feeder loss.Transmit power
The lower the frequency band and modulation scheme, the higher the transmit power.
Antenna gainThe greater the antenna gain, the longer the transmission distance.
Feeder lossThe lower the feed line loss, the longer the transmission distance
Receive sensitivity
The lower the receiver sensitivity, the longer the transmission distance.
Receive sensitivity The lower the frequency band and modulation scheme, the smaller the channel spacing, and the lower (better) the
receive sensitivity. With the given channel spacing, the smaller the service capacity, the better the receive sensitivity.
Equipment Factors That Affect Microwave Transmission
Natural factors
Equipment factors
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Page 33
Contents
What Is Microwave Communication?
Technologies and Terms Learned from a BOQ
How Far Can Microwave Reach?
Evolution Trend of Microwave Communication
11
22
33
44
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History of Microwave Transmission
Page 34
In 1947, Bell Telephone Laboratories (BTL) built the first analog microwave circuit (TD-X) between New York and Boston. This circuit adopted the frequency modulation (FM) mode.
In 1950, the 4 GHz TD-2 microwave system was used for the first time to provide commercial telephone services.
In the late 1960s, the first digital microwave system was built to improve the voice quality. In 1988, the International Telecommunications Union (ITU) internationalized Synchronous
Optical Network (SONET) of U.S.A as Synchronous Digital Hierarchy (SDH) transport network standards. The SDH microwave system developed rapidly in the 1990s.
In 2007, equipment vendors launched the IP radio (Hybrid/Packet radio) equipment that provided higher transmission efficiency.
Analog microwave
Digital microwave
TDM
Digital microwave IP
Capacity
30-1920K
IP400M
155M
34/140M
2/4/6/8M
1970s
1980s
1990s
2000s
1950s
SDH
Analog microwave
PDH
Small capacity
TDM
Digital microwaveAnalog microwaveE_BAND>1G
In accordance with the LTE deployment, equipment vendors started the R&D efforts on E-BAND products in 2010. These products will be put into wide commercial use in 2012.
Digital microwave
E_BAND
2010s
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TDM Radio and IP Radio
PDH/SDH
Application scenario: 2G, majority of TDM services, small capacity
Frame structure: Radio interfaces transmit TDM services. Ethernet services are mapped to TDM services
eliminated gradually
Hybrid
Application scenario: 2G/3G hybrid transmission, majority of E1 services
Frame structure: Radio interfaces transmit Ethernet and TDM services in Native mode.
Now mainstream
Packet
Application scenario: 3G/4G applications, majority of ETH services
Frame structure: Radio interfaces transmit Ethernet services. TDM services are encapsulated into Ethernet packets.
IP radioTDM radio
mainstream in future
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Page 36
Frequency band: 71-76 GHz, 81-86 GHz Native data transmission: a maximum transmission capacity of 1500 Mbit/s Typical transmission distance: 1-1.5 km Full outdoor solution
What Is E-Band Radio?What Is E-Band Radio?
Native Ethernet traffic in air
Ethernet
Full Outdoor
DC
10 20 30 40 50 60 70 80 90
6L/6U 1113 15 18 23 26 38
e-band
71GHz - 86GHz
Traditional Radio Link
7/8 42 55 58 (TDD)
ITU-R Radio-Frequency Channel Arrangements
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Thanks!