LINK Planning Factors that determine your PTP Solution · Motorola Solutions PTP LINK Planning Factors that determine your PTP Solution

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LINK PlanningFactors that determine your PTP Solution

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2

Agenda

• Motorola PTP Solutions• Key Questions• Propagation Effects

Freespace LossAtmospheric AbsorptionRain FadeClear Air Fading

• PTP LINKPlanner• Motorola PTP Products


3

WIDE RANGE OF MOTOROLA PTP OPTIONS

2.4 to 5.9 GHz

PTP 100 and 200 PTP 300, 500, 600

License-Exempt and Defined-Use Licensed Solutions

Licensed Solutions

PTP 800

6 to 38 GHz


4

How do I decide?

• What is the range?

• What is the throughput at that range?

• What is the availability?

The answers to all these questions depend on a number of factors, and change depending where the link is deployed.


5

Key Propagation Effects

Line-of-sight (LOS), freespace attenuation + atmospheric gas

(Oxygen, water vapour)

Fading due to Multipath from surface reflection

Diffraction Fading due to obstruction of

path by terrain

Atmospheric multipath fading due to

abnormal refraction

Attenuation due to rain / snow / dust

Distortion due to frequency

selective fading

Modelled according to ITU-R P.530


6

Microwave link planning

• Freespace loss Lfs

• Gaseous absorption Lg

• Rain Lr

• Clear-air fading (multipath) Lm

As in [ITU-R P.530], propagation loss consists of:

Loss (dB) = Lfs + Lg + Lm + Lr


7

Freespace Pathloss

)log(20)log(204.32 fdLfs ++= d = distance (km)f = frequency (MHz)

900 MHz

5 GHz26 GHz

900 MHz

5 GHz

26 GHz

“Perfect” Omni antenna

High-gain antennas at high freqs

0dB

15dB

32dB


8

Atmospheric AbsorptionP = 1013 hPaT = 20 oCρ = 7.5 g/m3

Atmospheric Attenuation Factor ⎯o (dB/km)

6

0.009

0.015

11

0.185

23 38

0.110

80

0.303

0.001

0.010

0.100

1.000

10.000

100.000

1 10 100

Frequency (GHz)

Atte

nuat

ion

fact

or (d

B/km

)

Dry gas Water vapour Total

60GHz Oxygenabsorption peak


9

Key propagation effects above 6 GHz

1. Rain : can be severe

2. Clear-air fading (includes ducting) : can be severe

3. Obstacles and multipath : Unlicensed only for non-LOSFresnel zone should be clearfor Licensed

Licenced Mircrowave (PTP800) is designed forclear LOS operation only !!!


10

Rain FadeFreq (GHz) ¼ wavelength

5.8 12.9 mm

11 6.8 mm

18 4.2 mm

23 3.3 mm

38 2.0 mm

Surface tension forms “pendant” shape

Water drop Water drop

on a leaf

Sphere is the shape with smallest surface area

Raindrop falling through air

Air resistance causes bottom of raindrop to

flatten

When raindropsize gets closeto wavelengthyou get power

absorption

Horizontal dimension isbiggest, soHorizontal

polarisationinteracts more

Largest raindrops

about 9 mm

< 2 mm

> 2 mm

5 mm

Photo: M.Sellars Photo: M.Sellars

H2O is a polarmolecule with aseparation of

charge, so it isaffected by microwaves


11

Rain fade for V & H Polarisation

0.0

10.0

20.0

30.0

40.0

50.0

60.0

70.0

80.0

90.0

100.0

0.0 20.0 40.0 60.0 80.0 100.0 120.0

Distance (km)

99.9

9% R

ain

fade

dep

th (d

B)

Vertical, 5 GHzHorizontal, 5GHzVertical, 18 GHzHorizontal, 18 GHzVertical, 23 GHzHorizontal, 23 GHz

23 GHzLarge gap betweenV and H polarisation

18 GHz

5 GHz

Rain rate 42 mm/hour

Horizontal polarisation is more attenuated by rain


12

Rain Fading

Cambridge U.K.

Johannesburg South Africa

Kuala Lumpur Malaysia

Bombay India

Dar es Salaam

Tanzania

Sydney Australia

Lattitude 52.2 N 26.1 S 3.2 N 18.6 N 6.5 S 33.9 S

Longitude 0.1 E 28.0 E 101.7 E 74.4 E 39.2 E 151.2 E

Rainfall rateR0.01 = 0.01%

22 mm/hr 51 mm/hr 116 mm/hr 74 mm/hr

95.5 mm/hr 45.9 mm/hr

For a 99.99% link need to know max rain rate not exceeded for 99.99% of the time then calculate path loss due to this amount of rain


13

99.99% Rain fade (Morocco 29mm/hour)

0.0

20.0

40.0

60.0

80.0

100.0

120.0

140.0

160.0

0.0 20.0 40.0 60.0 80.0 100.0 120.0

Link length (km)

Rai

n fa

de (d

B)

5.8 8.0 11.0 18.0 23.0 26.0 38.0


14

99.99% Rain fade (Malaysia 98mm/hour)

0.0

20.0

40.0

60.0

80.0

100.0

120.0

140.0

160.0

0.0 20.0 40.0 60.0 80.0 100.0 120.0

Link length (km)

Rai

n fa

de (d

B)

5.8 8.0 11.0 18.0 23.0 26.0 38.0


15

• Beam spreading (commonly referred to as defocusing) • Antenna decoupling • Surface multipath • Atmospheric multipath

These mechanisms can occur by themselves or in combination

Clear-air fading

Fading NOT due to rain, particles, obstacles (trees, buildings)=> “CLEAR AIR fading”

Caused by extremely refractive layers of air in the atmosphere

According to ITU-R P.530-12, clear-air fading mechanisms include :


16

“Duct” = Extremely refractive layer of air

Top of duct

Earth surface

• Ducts in atmosphere due to changing refractive index• Cause radio waves to bend back towards the earth surface• Primarily due to water vapour, worst above coastal areas

0

-39

-157

True Earth

0

-39

-157

Equivalent earth (standard atmosphere) 0

-39

-157

Flat Earth

Rays return to earth

Gradient of refractive index dN/dh = -39 units/km (linear)Change in temperature -> ducts change -> refractive index changes

linear


17

Not correlated with rain, so fading effects considered independent

Based on data of refractive index - Can vary depending on the season – eg worst in summer months in UK

Use refractivity gradient to estimate probability of ducting as in ITU-R P.453

Cambridge U.K. Johannesburg South Africa

Abu-Dhabi UAE

Bombay India

Dar es Salaam Tanzania

Sydney Australia

Refractivity index dN1

-214 -261 -1321 -333 -248 -468

Geoclimatic factor K 2.6e-4 3.6e-4 0.189 5.8e-4 3.3e-4 1.4e-3

Clear air fading

ITU combines all types of clear-air fading


18

Clear-air fading depends on:• Latitude – worse at equator• Altitude – worse at sea-level• Surface roughness – worse over flat ground• Inclination angle – worse on flat path• Frequency – worse at high frequency

Mountains - Low fading

Flat coastal - High fading

Ducts form easilyand persist

Ducts broken-up

Transmission pathlies inside a duct

Transmission pathcuts across ducts, => little refraction


19

99.99% Clear-air fade (Ashburton, U.K. vs Abu-Dhabi)

0.0

10.0

20.0

30.0

40.0

50.0

60.0

70.0

80.0

90.0

100.0

0.0 20.0 40.0 60.0 80.0 100.0 120.0

Link length (km)

Fade

(dB

)5.8 8.0 11.0 18.0 23.0

26.0 38.0 Abu-Dhabi 5.8 Abu-Dhabi 8.0 Abu-Dhabi 11

Abu-Dhabi 18 Abu-Dhabi 23 Abu-Dhabi 26 Abu-Dhabi 38

Abu-Dhabi

Ashburton, U.K.


20

LINKPlanner calculates this automatically

Abu-Dhabi Clear-air fading

time

RSL

0.01% fade

mean

61dB

U.K. Clear-air fading

time

RSL

mean

0.01% fade24dB

Abu-Dhabi, at 40km, 8GHz signal will fade by 61dB for 0.01% of time

U.K., at 40km, 8GHz signal will fade by 24dB for 0.01% of time

99.99% Clear-air fade (Ashburton, U.K. vs. Abu-Dhabi)

0.0

10.0

20.0

30.0

40.0

50.0

60.0

70.0

80.0

0.0 20.0 40.0 60.0 80.0 100.0 120.0

Link length (km)

Fade

(dB

)

U.K. 8 GHz Abu-Dhabi 8 GHz


21

Winnipeg, Canada: 99.99% Fading (Rain and Clear-air)

0.0

20.0

40.0

60.0

80.0

100.0

120.0

140.0

0.0 20.0 40.0 60.0 80.0 100.0 120.0

Link length (km)

Fade

(dB

)

Rain 5.8 Rain 8 Rain 11 Rain 18 Rain 23 Rain 26 Rain 38CA 5.8 CA 8 CA 11 CA 18 CA 23 CA 26 CA 38

Rain 18GHz

Rain 23GHz

Clear-air fading


22

Geographical variations

Sometimes rain dominates (usually at higher frequencies),whereas clear-air fading may dominate near the coast

Lake Mary

Charlottesville

Boston

Schaumburg

Dallas

Dodge CitySalt Lake City

Phoenix

Seattle

San Diego

GeorgeTownGrand Cayman

CityRain

(mm/hr)

Geoclimatic Factor K ( x 0.001 )

Salt Lake City 21 0.055

San Diego 25 0.190

Phoenix 33 0.130

Dodge City 36 0.170

Boston 41 0.329

Schaumburg 41 0.230

Seattle 41 0.091

Charlottesville 51 0.090

Dallas 55 0.245

Lake Mary 81 0.330

GeorgeTown, Gr. Cayman 84 0.250

Depends on intensity of heaviest

rainstormNOT

frequent drizzle

High values above 0.2mean high ducting


23

USA Rain Fade

0.0

10.0

20.0

30.0

40.0

50.0

60.0

70.0

0.0 20.0 40.0 60.0 80.0 100.0 120.0Link distance (km)

99.9

9% R

ain

fade

dep

th

Boston 6GHzBoston 11GHzBoston 18GHzDallas 6GHzDallas 11GHzDallas 18GHzDodge City 6GHzDodge City 11GHzDodge City 18GHzLake Mary 6GHzLake Mary 11GHzLake Mary 18GHzPhoenix 6GHzPhoenix 11GHzPhoenix 18GHzSalt Lake City 6GHzSalt Lake City 11GHzSalt Lake City 18GHz

18GHz

11GHz

6GHz

Fading calculations for USA - RAINRain fade worstin areas of heavystorms (Florida)

Lower frequencies not affected much by rain


24

USA Clear-air fade

0.0

10.0

20.0

30.0

40.0

50.0

60.0

0.0 20.0 40.0 60.0 80.0 100.0 120.0

Link distance (km)

99.9

9% F

ade

dept

h

Boston 6GHzBoston 11GHzBoston 18GHzGT Cayman Is. 6GHzGT Cayman Is. 11GHzGT Cayman Is. 18GHzSeattle 6GHzSeattle 11GHzSeattle 18GHzPhoenix 6GHzPhoenix 11GHzPhoenix 18GHzSalt Lake City 6GHzSalt Lake City 11GHzSalt Lake City 18GHz

Fading calculations for USA – Clear-air

Clear-air fadingworst on coast(Boston, Cayman Isl)

Best in Salt Lake City(high altitude, mountains, inland)


25

Link Distances for 99.99% Availability, 256-QAM, 6-foot dish

0 10 20 30 40 50 60 70 80

Frequency (GHz)

Distance (km)

Salt Lake City Phoenix GeorgeTown, G.Cayman Boston Lake Mary

6 GHz

11GHz

18GHz

Dominated by clear-air fading,worst on coast (Lake Mary)

Dominated by rain fading,worst in stormy areas(GeorgeTown)

Fading calculations for USA – Rain and Ducting combined

Salt Lake City has lowest rainfallso high frequencies travel quite far

Salt Lake City is in the mountainsso clear-air fading is low

18 GHz in Salt Lake City

travels further than 6 or 11 GHz in most

other places !

FCC Rules for 6 GHz:Smallest antenna = 6ftShortest path = 17 km

FCC Rules for 11 GHz:Smallest antenna = 2.6ft

Shortest path = 5 km


26

Simple Questions?

What is the range?

What is the throughput at that range?

What is the availability?

There is no “quick answer” to these questions, a lot depends on your location and a number of factors for your link

Calculating these factors manually would be very time consuming!


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MOTOROLA LINKPlanner software MOTOROLA LINKPlanner software

Link planning should be carried out BEFORE equipment purchase / install

Download the FREE tool from http://www.motorola.com/ptp/software

Start the PTP LINKPlanner tool

Create sitesCreate linksRequest path data from MotorolaFree 3 metre Terrain Data (US Only, 10 metre world wide)Aerial Photography (free from Google Earth)

Load obstruction data into link toolsObstructions estimated from aerial photography and local knowledge

Estimate antenna heights

Estimate appropriate antenna sizes

Estimate environmental noise

Configure link for customer needs


29

Long link, 112km


30


31

Fresnel zone – clear if possible

Width of First Fresnel zone (n=1)28GHz, d=10km, Fn ≈ 5m

Curvature of EarthRadius of Earth 6371km‘Effective Earth Radius’ factor – typically 4/3‘bulge’ ≈ 1.5m for d=10km

ITU-R P.526 model for irregular terrain

d2d1

Fn

21

21

ddddnFn

+=

λ

PTP 800 is designed for clear LOS operation only !!!


320 5 10 15 20 25 30 35 40 45 50 55Distance (km)

6

11

15

18

23

26

38

Frequency (GHz)

Short, high-capacity links



Medium links

Medium links

Long trunks

Long trunks

4.9 - 5.8 Unlicensed

0.5

Regulator may not license < 5km or 17km (FCC)

Minimum link dist ~ 0.5km

Distances calculated for various frequencies assuming:128QAM, 99.99%, 4-foot dishes, “medium” fading (rain = 58 mm/hr, refractive index dN1 = -219)

Guidance for PTP 800 link distances


33

PTPFeature PTP 100 PTP 200 PTP 300 PTP 500 PTP 600 PTP 800RF bands

(GHz)2.4, 5.2, 5.4, 5.8 4.9, 5.4 5.4, 5.8 5.4, 5.8

2.5, 4.5, 4.8, 4.9, 5.4, 5.8,

5.96 – 38

Max. Throughput 14 Mbps 21 Mbps

25 Mbps –50 Mbps LOS

option105 Mbps 300 Mbps 368 Mbps

(full duplex)

Max. LOS Range

35 mi (56 km) with

reflector

5 mi (8 km) Integrated antenna

155 mi (250 km)

155 mi(250 km)

124 mi(200 km) NA

Max. NLOS Range NA NA 6 mi (10 km) 6 mi (10 km) 5 mi (8 km) NA

Security 56-bit DES128-bit AES

56-bit DES128-bit AES

128/256-bit AES

128/256-bit AES

128/256-bit AES;

FIPS 140-2

128/256-bit AES

Wind Speed Survival

118 mph (190 kph)

118 mph (190 kph)

202 mph (325 kph)

202 mph (325 kph)

202 mph (325 kph)

150 mph (242 kph)

Operating Temperature

-40º~131º F (-40º~55º C)

-40º ~131º F (-40º~55º C)

-40º~140º F (-40º~60º C)

-40º~140º F (-40º~60º C)

-40º~140º F (-40º~60º C)

-27º~131º F (-33º~55º C)

PRODUCTS AND KEY FEATURES


34

SummeryWhy use Lower frequencies ??

Unlicensed – No Licence Fees

Unlicensed – Quick and Easy to deploy – No Frequency Co-ordination

Long Distance

Non Line of Site possible


35

SummeryWhy use higher frequencies ??

Bandwidth – much more available > 10GHz

Easier to make Narrow-beam antennas (e.g. point-to-point links)

Better frequency re-use (e.g. 38GHz, 60GHz)

Always use LINKPlanner!!

Q&A

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LINK Planning Factors that determine your PTP Solution · Motorola Solutions PTP LINK Planning Factors that determine your PTP Solution