BASIC INTRODUCTION INTO MICROWAVE THEORY AND IP APPLICATIONS

1. 1
BASIC INTRODUCTION INTO MICROWAVE THEORY AND IP
APPLICATIONS
FUNDAMENTALS OF MICROWAVE RADIO
COMMUNICATION FOR IP AND TDM
Presented by: Richard Laine / Ivan Zambrano
Silicon Valley, CA.

2. Agenda
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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

3. A. INTRODUCTION

4. • The field of terrestrial microwave communications is constantly experiencing a steady
technological innovation to accommodate the ever-demanding techniques telecom
providers and private microwave users employ when deploying microwave radios in their
cloud networks.
• In the beginning of this wireless evolution, the ubiquitous DS1s/E1s and DS3s/E3s
crisscrossed networks transporting mainly voice communications, data, and video.
• With the advent of Carrier Ethernet and IP, new techniques had to be developed to
ensure the new Layer 2 radios were up to par with the new wave of traffic requirements
including wideband online-streamed media. These new techniques come in the form of
Quality of Service (QoS), Traffic Prioritization, RF Protection and Design, Spectrum
Utilization, and Capacity Enhancement.
• With Carrier Ethernet and IP, network design becomes more demanding and complex in
terms of RF, Traffic Engineering, and QoS. However, the propagation concepts remain
unchanged from TDM link engineering while the link’s throughput of L2 radios doubles,
triples, or quadruples employing enhanced DSP techniques.
Introduction
4 AVIAT NETWORKS July 2013

5. B. WHAT IS TERRESTRIAL MICROWAVE?

6. 6
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

7. 7 AVIAT NETWORKS |
Terrestrial Microwave?………..What is it? (cont'd)
July 2013

8. 8 AVIAT NETWORKS |
Terrestrial Microwave?………..What is it? (cont'd)
July 2013
60% F1
60% F1

9. B.1 SPECTRUM

10. 10 AVIAT NETWORKS |
Frequency Spectrum
July 2013

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Some Standard Frequency Bands for Terrestrial Microwave
Band Radio Frequency Recommendations
(MHz) FCC, NTIA, and ITU-R)
4 GHz 3,600 – 4,200 FCC Part 101 and Rec F.635-6 (2006)
U4 GHz 3,803.5 – 4,203.5 ITU-R Rec F.382-8 (2006)
5 GHz 4,400 – 5,000 ITU-R Rec F.1099-3 Annex-1 (2007)
5 GHz 4,400 – 4,990 U.S. Federal (NTIA)
L6 GHz 5,925 – 6,175 FCC Part 101, Rec F.383-7 (2007)
U6 GHz 6,525 – 6,875 FCC Part 101
U6 GHz 6,430 – 7,110 ITU-R Rec F.384-9 (2007)
7/8 GHz 7,125 – 8,500 U.S. Federal (NTIA)
L7 GHz 7,125 – 7,425 ITU-R Rec F.385-8 Annex-1 (2007)
U7 GHz 7,425 – 7,725 ITU-R Rec F.385-8 (2007)
7W GHz 7,110 – 7,750 ITU-R Rec F.385-8 (2007)
L8 GHz 7,725 – 8,275 ITU-R Rec F.386-7 Annex-6 (2007)
10 GHz 10,550 – 11,680 FCC Part 101, Rec F.747 (1992)
11 GHz 10,700 – 11,700 FCC Part 101, Rec F.387-10 (2010)
13 GHz 12,750 – 13,250 ITU-R Rec F.497-6 (2007)
July 2013

12. 12 AVIAT NETWORKS |
RF Atmospheric Attenuation
July 2013

13. B.2 A TERRESTRIAL MICROWAVE LINK
AND APPLICATIONS

14. 14 AVIAT NETWORKS
Data
Equipment
Outdoor RF/Antenna
Gigabit
Ethernet
NxDS1/E1
PABX
Equipment
Data
Equipment
Outdoor RF/Antenna
Gigabit
Ethernet
NxDS1/E1
PABX
Equipment
6 to 360 Mbit/s
QPSK to 256 QAM
July 2013
One "hop" of Microwave

15. Radio Node Hardware Example - Eclipse
15 AVIAT NETWORKS | July 2013

16. 16 AVIAT NETWORKS |
Cellular Site MSC-BSC-BTS IP/TDM Interconnectivity
MSC (MTSO) - Switching Office (POP)
BTS - Base Station
BSC - Base Station Controller
BSC
18/23 GHz (NxDS1/E1)
23/38 GHz (NxDS1/E1)
18 GHz (NxDS1/E1) 18 GHz (DS3/E3)
Eclipse Eclipse
BTS
BSC
Eclipse
MSC
(MTSO)
Eclipse
BTS
BTS
BTS
Eclipse IRU 600 Self-Healing STM-1/OC-3/Ethernet /IP Ring
Typical TDM Capacity Requirements
OC-3/STM-1 to
OC-12/STM-4
16xDS1/E1 to
OC-3/STM-1
BSC to MSC
2-16xDS1/E11-2xDS1/E1BTS to BSC
3G2GHops
BTS to BTS 1-2xDS1/E1 2-16xDS1/E1
July 2013

17. Mobile RAN and Backhaul Transport
July 201317 AVIAT NETWORKS |
IEEE, Oct. 2010
Carrier Ethernet MPLS-TP

18. Outdoor Networked Radio (4-QAM through 1024-QAM)
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19. B.3 HOW FAR CAN TERRESTRIAL
MICROWAVE GO?

20. Typical Relative Path Lengths with Clear Line of Sight (LOS)
20 AVIAT NETWORKS |
Path Length, mi (km)
6/7/8 GHz
11 GHz
18 GHz
23/38 GHz
100(160)5(8) 10(16)
• Path lengths in the different RF
bands are estimates only
• A path analysis is required to
calculate the reliability and
availability criteria.
Maximum EIRP (Effective
Isotropic Radiated Power) =
+55 dBW = +85 dBm
3(5)
July 2013
80 GHz

21. 21
Examples of Very Long IP Microwave Links for Air Traffic Control
July 2013

22. B.4 HOW MICROWAVE RADIOS
COMMUNICATE

23. July 201323 AVIAT NETWORKS |
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 Traffic
Less Critical
Traffic Critical Traffic
(256QAM) 40

24. July 201324 AVIAT NETWORKS |
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 which
reliable communication can not be maintained! This
ratio can be considered a metric that characterizes the
performance of one system vs. another. The smaller
the ratio, the more efficient is the modulation and
detection process for 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 and BW
Eb/N
0
mNoEbNC log10// 
With concatenated coding, the coded curve is steeper
than with Reed-Solomon alone.
Example: The C/N of a p-t-p radio featuring
4DS1/16QAM and Eb/N0 = 11.9 dB @ 10-6
equals: 11.9 dB + 10 log4 = 17.9 dB

25. July 201325 AVIAT NETWORKS |
MLCM Signal Constellation
d
√2 d
1 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

26. B.5 HOW REPEATERS EXTEND THE
RANGE

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Passive Reflector
"Billboard"
Site A
Single
Reflector
Site B
Terrain
Obstruction
Passive Repeater Arrangements
Site B
Site A
Terrain
Obstruction
Terrain
Obstruction
Double
Reflector
Double Reflector
July 2013

28. 28 AVIAT NETWORKS |
Site A Beam Bender
(Back-To-Back
Parabolics)
Terrain
Obstruction
Site B
Beam Bender
Back-To-Back Parabolic Antennas
"Beam Bender"
Other Passive Repeater Arrangements
July 2013

29. B.6 MICROWAVE TOWER ISSUES

30. Twist and Sway
30 AVIAT NETWORKS | July 2013
A B C
Antennas: HSX12-77 Antennas: HSX12-77
Beamwidth: ±0.35o Beamwidth: ±0.35o
425ft/130m
200ft/60m
425ft/130m
Daytime Tower Twist: ±10
±0.50 deflection angle
at 10 dB point

31. B.7 CAUSES OF MICROWAVE
DISCONNECT PERIODS

32. Causes of Traffic Disconnect - Outage
32 AVIAT NETWORKS |
• Rain outage (predictable and therefore acceptable) in access links above
about 10 GHz
• Equipment failure within the MTBF (Mean Time Between Failure) period
• Maintenance error or manual intervention (e.g., failure of a locked-on
module or path)
• Infrastructure failure (e.g., antenna, batteries, towers, power system)
• Low fade margin in non-diversity links
• Power fade (long-term loss of fade margin) in paths above about 6 GHz
July 2013

33. C. SOME EXAMPLES OF L2 RADIO
TECHNOLOGY

34. Eclipse Intelligent Node Unit
• The most compact nodal
solution on the market
• Single indoor unit
supporting multiple radio
paths
• Hot-swappable radio and
data access modules
• Support for all traffic types
• Cable-less traffic
connections
• Complete solution in one
box
34 AVIAT NETWORKS | July 2013

35. • 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, Hybrid
TDM/Ethernet/IP, or all-IP throughput
• QPSK to 256-QAM
Networked Radios
35 July 2013AVIAT NETWORKS |

36. D. WHY PROPAGATION?

37. Radio Wave Propagation
37 AVIAT NETWORKS |
GEO, MEO,
and LEO
Satellites
Sky Wave
(MF, HF only)
REFRACTED WAVE
NON-REFRACTED (k=1) WAVETransmitting
Antenna
Receiving
Antenna
Troposphere
Ionosphere
Microwave link propagation is
influenced by REFRACTION,
REFLECTION, and DIFFRACTION
(not shown) wave propagation.
Ground Wave
(LF/MF only)
True Earth’s Curvature
MULTIPATH RAYS
July 2013

38. Ray Tracing Along a Profile
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• Not unlike outbound ripples from a pebble
tossed into a quiet pond, the outgoing microwave
wave front is circular. However, the only part of
the wave of interest is equal to the diameter
(aperture) of the antenna. Beyond the antenna’s
near field, and into the far field, the wave front is
flat, as shown. The ray(s), one direct (shown)
plus multipath rays (if any), are always
perpendicular (90o) to the wave front - thus only
one ray is assigned to each direct or multipath
route. All path profiles and engineering are based
upon ray analysis.
• Antennas serve only to provide maximum
coupling of the direct ray energy into the
waveguide feeder, to the exclusion of multipath
rays. Thus, optimum dish alignment is crucial
for minimum fading.
k = 1 (True Earth’s Radius)
Superrefraction (k>3)
Wavefront Ray 90o
Substandard
Refraction (k<1)
Possible
Obstruction
Possible
Decoupling,
Defocusing, or
Entrapment
Dry and High Valleys
Humid Wetlands

39. 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 Supp
Shelter
Elliptical
Waveguide, Coax
Atmospheric
Multipath
Millimeter Wave
Rain Attenuation
Refraction, k-Factor
Variations
Antenna Sizes,
Types, Alignment
Diversity
Type, Ant.
Spacing, XPIC
Path
Clearance
July 2013
Dust Cloud

40. Multipath Propagation
40 AVIAT NETWORKS |
Excessive Path
Clearance
Elevated Super-refractive
Layer
Specular Reflection
July 2013

41. E. ANTENNAS AND FEEDER SYSTEMS

42. 42 AVIAT NETWORKS |
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

43. 43 July 2013

44. 44 AVIAT NETWORKS |
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

45. 45 AVIAT NETWORKS |
Antenna Alignment Issues
Antenna aligned on a side-lobe
Correct antenna alignment
July 2013

46. 46 AVIAT NETWORKS |
Antenna Decoupling
• Angle of arrival may vary by as much as 1° on long paths
in humid areas at night; therefore larger antennas are
typically 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

47. 47 AVIAT NETWORKS |
PRESSURIZED (AIR)
COAXIAL CABLE
UNPRESSURIZED (FOAM)
COAXIAL CABLE
ELIPTICAL
WAVEGUIDE
RECTANGULAR (RIGID)
WAVEGUIDE
CIRCULAR (RIGID)
WAVEGUIDE
Transmission Lines
July 2013

48. 48 AVIAT NETWORKS |
Transmission Lines (Feeder Systems)
• Coaxial cable
• Air dielectric (lower loss)
• Foam dielectric (higher loss)
• Works from DC, but losses increase very rapidly above 2GHz
• Waveguide
• Elliptical (very common)
• Circular (very low loss)
• Rectangular (now rarely used)
• Flexible/twistable waveguide
• Frequencies below cut-off do not propagate through waveguide
July 2013

49. F. RF PROTECTION

50. Definitions
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• Protection Schemes provide a level of security from long-
term (>10 CSES/event – Consecutive Severely Errored
Seconds) outages and loss of data throughput, and
therefore improve Availability and reduce traffic
disconnects.
• Diversity Arrangements reduce the number and duration
of short-term (<10 CSES/event) outages (no traffic
disconnects) and therefore improve Performance.
July 2013

51. F.1 MONITORED HOT STANDBY

52. 1+1 Monitored Hot Standby Outdoor Node (cont’d)
July 201352 AVIAT NETWORKS |
Tribs 1-20
Protection
Cable
ODU 600sp/hp/ep
Y-Cables

53. 1+1 Monitored Hot Standby Outdoor Node
July 201353 AVIAT NETWORKS |
Equal split (3dB)
RF Splitter is also
possible with the
consequence of a
2dB link gain
penalty which
translates into a
58% degradation in
the hop’s error
performance and
perhaps larger
antennas!
ANTENNA
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 or Tx B is on line

54. H.2 MONITORED HOT STANDBY WITH
SPACE DIVERSITY

55. July 201355 AVIAT NETWORKS |
Space Diversity with Horizontal Offset

56. 1+1 Monitored Hot Standby Space Diversity - Outdoor Node
July 201356 AVIAT NETWORKS |
Multipath forms essentially
in the vertical plane;
consequently, the antennas
should always be placed
vertically to achieve de-
correlated paths !
Main ANTENNA
DATA
OUT
DATA IN
Tx A
Rx A
Tx B
Rx B
INU errorless data
selection is frame-by-frame
Diversity ANTENNA
300 ms
Vertical antenna spacing from 3 – 23m
ITU-R P.530-13
RSLM
RSLD
-40 dB fade
-20 dB fade

57. THANKS YOU AND SUGGESTIONS

58. Suggestions
58 AVIAT NETWORKS | July 2013
• Professional Affiliations News Websites
• IEEE
• LinkedIn www.bbc.com
www.foxnews.com
• Movies www.elpais.es
• The Pirates of Silicon Valley
• Social Network
• The Internship
• The Greatest Game Ever Played
• Flash of Genius
• Countries
• Spanish English
• Chile Australia
• Argentina New Zealand
Dubai
Canada
USA