fundamentals of microwave

8/10/2019 FUNDAMENTALS OF MICROWAVE

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BASIC INT RODUCTION INTO M ICROWAVE THEORY AND IP

APPLICAT IONS

FUNDAMENTALS OF MICROWAVE RA

COMMUNICATION FOR IP AND TDM

Presented by: Richard Laine / Ivan ZambranoSilicon Valley, CA.


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Agenda

July 20132 AVIAT NETWORKS |

Introduction....A

What is Microwave....B

Spectrum...B.1 A Terrestrial Microwave Link and Applications.......B.2

How Far can Microwave Go..........B.3

How Microwave Radios Communicate.....B.4

How Repeaters Extend the Range....B.5

Microwave Tower Issues.B.6

Causes of Microwave Disconnect Periods...B.7

L2 Radio Technology........C

Why Propagation..............D

Antennas and Feeder Systems...E

RF Protection..F


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A. INTRODUCTION


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The field of terrestrial microwave communications is constantly experiencing

technological innovation to accommodate the ever-demanding technique

providers and private microwave users employ when deploying microwave rad

cloud networks.

In the beginning of this wireless evolution, the ubiquitous DS1s/E1s and

crisscrossed networks transporting mainly voice communications, data, and vide

With the advent of Carrier Ethernet and IP, new techniques had to be de

ensure the new Layer 2 radios were up to par with the new wave of traffic req

including wideband online-streamed media. These new techniques come in t

Quality of Service (QoS), Traffic Prioritization, RF Protection and Design,

Utilization, and Capacity Enhancement.

With Carrier Ethernet and IP, network design becomes more demanding and c

terms of RF, Traffic Engineering, and QoS. However, the propagation conce

unchanged from TDM link engineering while the links throughput of L2 radio

triples, or quadruples employing enhanced DSP techniques.

Introduction

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B. WHAT IS TERRESTRIAL MICROWAVE?


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Flushing ANSI

values

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Terrestrial Microwave?..What is it?

A line-of-sight point-to-point wireless technology

for the transmission of Internet, voice, data, and

online-streamed media.

July 2013

Refracted Beam

Direct Beam

Reflected Beam
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Terrestrial Microwave?..What is it? (cont'd)

July 2013


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Terrestrial Microwave?..What is it? (cont'd)

July 2013

60% F1

60% F1


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B.1 SPECTRUM


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Frequency Spectrum

July 2013


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Some Standard Frequency Bands for Terrestrial Microw

Band Radio Frequency Recommendations(MHz) FCC, NTIA, and ITU-R)

4 GHz 3,6004,200 FCC Part 101 and Rec F.63

U4 GHz 3,803.54,203.5 ITU-R Rec F.382-8 (2006)

5 GHz 4,4005,000 ITU-R Rec F.1099-3 Annex

5 GHz 4,4004,990 U.S. Federal (NTIA)

L6 GHz 5,9256,175 FCC Part 101, Rec F.383-7

U6 GHz 6,5256,875 FCC Part 101

U6 GHz 6,4307,110 ITU-R Rec F.384-9 (2007)

7/8 GHz 7,1258,500 U.S. Federal (NTIA)L7 GHz 7,1257,425 ITU-R Rec F.385-8 Annex-1

U7 GHz 7,4257,725 ITU-R Rec F.385-8 (2007)

7W GHz 7,1107,750 ITU-R Rec F.385-8 (2007)

L8 GHz 7,7258,275 ITU-R Rec F.386-7 Annex-6

10 GHz 10,55011,680 FCC Part 101, Rec F.747 (1

11 GHz 10,70011,700 FCC Part 101, Rec F.387-10

13 GHz 12,75013,250 ITU-R Rec F.497-6 (2007)

July 2013


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RF Atmospheric Attenuation

July 2013


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B.2 A TERRESTRIAL MICROWAVE LINK

AND APPLICATIONS


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Data

Equipment

Outdoor RF/Antenna

Gigabit

EthernetNxDS1/E1

PABX

Equipment

Data

Equipme

Outdoor RF/Antenna

Gigabit

EthernetNxDS1/E1

PABX

Equipment

6 to 360 Mbit/s

QPSK to 256 QAM

July 2013

One "hop" of Microwave


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Radio Node Hardware Example - Eclipse

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Mobile RAN and Backhaul Transport


IEEE, Oct. 2010

Carrier Ethernet MPLS-TP


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Outdoor Networked Radio (4-QAM through 1024-QAM)



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B.3 HOW FAR CAN TERRESTRIAL

MICROWAVE GO?


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Typical Relative Path Lengths with Clear Line of Sight (

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Path Length, mi (km)

6/7/8 GHz

11 GHz

18 GHz

23/38 GHz

5(8) 10(16)

Path lengths in the d

bands are estimates only

A path analysis is r

calculate the reliabavailability criteria.

Maximum EIRP (Effective

Isotropic Radiated Power) =

+55 dBW = +85 dBm

3(5)

July 2013

80 GHz


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Examples of Very Long IP Microwave Links for Air Traffic

July 2013


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B.4 HOW MICROWAVE RADIOS

COMMUNICATE


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Adaptive Coding and Modulation for IP Backhaul

Throughput

[Mbit/s @ 7 MHz Ch BW]

(QPSK) 10

(16QAM) 20

(64QAM) 30

Example: 99.990% 99.995% 99.999% Rain Availability or Path Reliability

Fade Margin: 24 dB (20%) 31 dB (55%) 40 dB (25%)

Time

Fast Multipath or Slow Rain Fade

Best Effort TrafficLess Critical

Traffic Critical Traffic

(256QAM) 40


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Coding Gain in AWGN Channels

Coding gain in AWGN (Additive White Gaussian Noise) channels is defined as

the amount that the bit energy or S/N power ratio can be reduced under the coding

technique for a given Pb (bit error probability) or Pbl(block error probability)

Shannon Limit: Threshold, Eb/N0, below wreliable communication can not be maintained! T

ratio can be considered a metric that characterizes

performance of one system vs. another. The sm

the ratio, the more efficient is the modulation

detection processfor a given Pb.

Pb

10-2

10-4

10-6

Uncoded

Coded

-1.6 dB-8 dB 16 dB

X dB of Coding Gain depending on modulation

Eb/N

0

mNoEbNC log10//

With concatenated coding, the codedcurve is s

than with Reed-Solomon alone.

Example: The C/N of a p-t-p radio feat

4DS1/16QAM and Eb/N0 = 11.9 dB @

equals: 11.9 dB + 10 log4 = 17.9 dB


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MLCM Signal Constellationd

2 d1 0

Level 1

1 0

2d

1 0

Level 2

A set of 64 symbols is divided into subsets B0 & B1 with

increased minimum square distance. Error performance

of level 1 is determined by the minimum square distance

of the original partition. Then in order to increase free

Euclidean distance, coding (combination of block or

convolutional) is performed to the lower level. Hence the

total error performance is improved. Example (16QAM):

Code rate, R = (1/2+3/4+23/24+1)/4=3.2/4

B1 B0

C2 C0 C1 C3

Level 3


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B.5 HOW REPEATERS EXTEND THE

RANGE

P i R A


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Passive Reflector

"Billboard"

Site A

Single

Reflector

Site B

Terrain

Obstruction

Passive Repeater Arrangements

Site A

Terrain

Obstruction

Double

Reflector

Double R

July 2013


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Site A Beam Bender

(Back-To-Back

Parabolics)

TerrainObstruction

Site B

Beam Bender

Back-To-Back Parabolic Antennas

"Beam Bender"

Other Passive Repeater Arrangements

July 2013


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B.6 MICROWAVE TOWER ISSUES

T i t d S


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Twist and Sway

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Antennas: HSX12-77 Antennas: HSX12-77

Beamwidth: 0.35o Beamwidth: 0.35o

425ft/130m

200ft/60m

425ft/130m

Daytime Tower Twist: 10

0.50deflection angle

at 10 dB point


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Causes of Traffic Disconnect - Outage

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Rain outage (predictable and therefore acceptable) in access link

about 10 GHz

Equipment failure within the MTBF (Mean Time Between Failure)

Maintenance error or manual intervention (e.g., failure of a lo

module or path)

Infrastructure failure (e.g., antenna, batteries, towers, power syst

Low fade margin in non-diversity links

Power fade (long-term loss of fade margin) in paths above about

July 2013


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C. SOME EXAMPLES OF L2 RADIO

TECHNOLOGY


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Networked Radios


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Lower Losses than Couplers More ODUs per Antenna feed

Fewer Antennas Increased system gain

Reduces antenna sizes

Less Tower Loading

Radios features 5 to 38 GHz licensed operation

Fully transparent to payload

Up to 500 Mbit/s of TDM, HybridTDM/Ethernet/IP, or all-IP throughput

QPSK to 256-QAM

Networked Radios

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D. WHY PROPAGATION?


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Carrier Ethernet Link Design Parameters


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Carrier Ethernet Link Design Parameters

39

Flushing ANSI

values

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NETWORK LAYOUT

FIELD VERIFICATION

MICROWAVE EQUIPMENT (Backhaul

Capacity, Link Aggregation, RF Band,

Diversity)

LINK ANALYSIS (Google Map Study, Field

Survey, Geometry, Weather Patterns)

LINK PERFORMANCE CALCS (ITU, Vigants)

LINK AVAILABILITY CALCS (RF Protection,

Rain Outage)

ACTIVE NODES and PASSIVE REPEATERS

FREQUENCY STUDY (Interference,

Licensing, Antenna Selection)

INFRASTRUCTURE (Shelter, AC/DC Power,

Site Security, Towers, Ice Shield, Air Con, etc.)

ANTENNA FEEDER SYSTEM, (Structures,

Aesthetics, Transmission Lines)

GROUNDING AND SAFETY

Towers >200ft (60-m)

Require Lighting,

Painting

Sections:

20-ft guyed,

25-ft Self SuppShelter

Wav

Atmospheric

Multipath

Millimeter Wave

Rain Attenuation

Refraction, k-Factor

Variations

Antenna Sizes,

Types, Alignment

Diversity

Type, Ant.

Spacing, XPIC

Path

Clearance

July 2013

Multipath Propagation


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Multipath Propagation

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Excessive Path

Clearance

Elevated Super-refractive

Layer

Specular Reflection

July 2013


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E. ANTENNAS AND FEEDER SYSTEMS

Reflector Antennas


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Reflector Antennas

Photos courtesy of Andrew Corporation

July 2013

Standard parabolic

Standard parabolic

(with radome)Shielded with radome

(high performance)

Higher F/B ratio

Spillover Effect Scattering Effect Diffraction Effect


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43 July 2013

Antennas


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Antennas

Used to efficiently radiate/receive the energy towards/from

the far-end of the link

Important characteristics Gain / directivity / beamwidth

Side lobe level

Front-to-back ratio (F/B)

Polarization (linear V/H, circular, dual V/H)

Cross-polar discrimination

VSWR

Frequency operating range

Mounting, weight, and wind loading

Aesthetics

July 2013

Antenna Alignment Issues


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Antenna Alignment Issues

Antenna aligned on a side-lobe

Correct antenna alignment

July 2013

Antenna Decoupling


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Antenna Decoupling

Angle of arrival may vary by as much as 1on long paths

in humid areas at night; therefore larger antennas aretypically slightly uptilted during daytime periods

Such variations may cause power fades and degraded

performance (loss of fade margin, increased outage) if

antennas are very directive

Variation in arrival angle

K=

K=4/3

K=-2

July 2013

Transmission Lines


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PRESSURIZED (AIR)

COAXIAL CABLE

UNPRESSURIZED (FOAM)

COAXIAL CABLE

ELIPTICAL

WAVEGUIDE

RECTANGULAR (RIGID)

WAVEGUIDE

CIRCULAR (RIGID)

WAVEGUIDE

Transmission Lines

July 2013

Transmission Lines (Feeder Systems)


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( y )

Coaxial cable

Air dielectric (lower loss)

Foam dielectric (higher loss)

Works from DC, but losses increase very rapidly above 2G

Waveguide

Elliptical (very common)

Circular (very low loss)

Rectangular (now rarely used)

Flexible/twistable waveguide

Frequencies below cut-off do not propagate through wave

July 2013


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F. RF PROTECTION

Definitions


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Protection Schemes provide a level of security from l

term (>10 CSES/eventConsecutive Severely Errored

Seconds) outages and loss of data throughput, andtherefore improve Availabilityand reduce traffic

disconnects.

Diversity Arrangements reduce the number and duratof short-term (


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F.1 MONITORED HOT STANDBY

1+1 Monitored Hot Standby Outdoor Node (contd)


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Tribs 1-20

Protection

Cable

ODU 600sp/hp/ep

Y-Cables

1+1 Monitored Hot Standby Outdoor Node


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y


Equal split (3dB)

RF Splitter is also

possible with theconsequence of a

2dB link gain

penalty which

translates into a

58% degradation inthe hops error

performance and

perhaps larger

antennas!

ANTENN

DATA

OUT

DATA IN

-1.6dB

-6.6dB

Tx A

Rx A

Tx B

Rx B

Asymmetric

RF

Coupler

INU/IDU errorless data

selection is frame-by-frame

-1.6dB

-1.6dB

Tx A orTx B is on line


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H.2 MONITORED HOT STANDBY WITH

SPACE DIVERSITY

Space Diversity with Horizontal Offset


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THANKS YOU AND SUGGESTIONS

Suggestions


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58 AVIAT NETWORKS | July 2013

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