Micowave Survey Knowledge-20080226-A.ppt

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FIELD TELECOMMUNICATION SURVEY

Microwave SURVEY Knowledge

HUAWEI TECHNOLOGIES CO., LTD. Page 2Huawei Confidential

FIELD TELECOMMUNICATION SURVEYFIELD TELECOMMUNICATION SURVEY

ContentsContents1) Introduction

- Survey definition

- Objectives / scope

- On site methodology

- On path methodology

* Los: Urban, long haul…

2) List of tools used during the survey3) Data and survey report

- Site visit / On path data collection- Survey report

4) Proprietary application software- Azimuth- Profile- Pathloss

5) Link budget calculation- ITU-R recommendation- Link budget calculation- North American (nNA) and ITU-R Path Reliability (Outage) Calculation


ContentsContents


1) Introduction

- Survey definition








5) Link budget calculation- ITU-R recommendation- Link budget calculation- Climate / Terrain / Rain charts


INTRODUCTIONINTRODUCTION

Survey definition

– A survey is a mission on site to verify the feasibility of a telecommunication network with the objective of meeting the customer specification, but also optimizing the coverage and minimizing the cost.

– The survey is a key element in the implementation of a project. The success of a network implementation depends on the accuracy of the survey. No survey (or a poor survey) may lead to mistakes in the technical project

– Obstruction, tower to be expanded (extra civil works …)– Delays, subscribers cut

– Penaltiesand other damages …..


ContentsContents


1) Introduction

- Survey definition








5) Link budget calculation- ITU-R recommendation- Link budget calculation- North American (NA) and ITU-R Path Reliability (Outage) Calculations


Objective / scope

– The main objectives of a RF survey are summarized here under:

• Confirm the need expressed by the customer.• Confirm or foresee the precise localization of the stations.• Confirm the network or the system design.• Collect the necessary information’s for system configuration and engineering devices.• When applicable, clarify with the customer Engineering details such as antenna mounting constraints,

equipment consumption, access roads and actions to be taken by the Customer during the implementation.

• Note and anticipate the difficulties to be expected during the implementation: logistics, installation, climatic condition, access, etc. ...



ContentsContents


1) Introduction

- Survey definition








5) Link budget calculation- ITU-R recommendation- Link budget calculation - North American (NA) and ITU-R Path Reliability (Outage) Calculations


On site methodology

• How to proceed ?– Conditions:

• During site survey, a Customer representative should always be present. He will be a facilitator (obtain permission to access the sites, find terrain and landlords, when applicable negotiate the site chosen, coordinate administrative process etc.)

– Map study / analysis of customer's preliminary Network design:This preliminary part will be carried out in order to :• identify the sites to be served • determine the exact co-ordinates and altitude of the sites to be served and if necessity of repeaters if

any• establish the path profiles (not applicable in dense urban, line of sight checked visually)• estimate the antenna height (tower height)• establish a preliminary network structure• estimate the size of antennas



On site methodology

• Site study:– The visit of the sites defined previously will be carried out in order to

confirm , determine or modify:

• the actual possibility to use the site chosen on the map.• the actual co-ordinates and altitude of the site.• the precise location (to be marked ), where station will be implemented• the availability and access to commercial power if needed• any existing antennas• the height and type of the tower according to the specificity of the site and obstacles encountered• any close range obstacles• the network structure / system layout• obtain site « call signs » if available (North America)• Site address (North America)• Obtain tower registrations if needed (North America)



On site methodology

• The information collected will be useful:

– For project engineer• Defined network• Controlled profiles• Defined engineering• PABX data• Frequency data

– For realization team• Access plan• Site lay out• Elevation plans• Indoor layout plans• Lists of installation equipment



On site methodologyOn site methodologyI) 1st STATION: any microwave system

1- Altitude measurement• Choose a reference point• Perform double measurement

(reference altimeter + measuring altimeter)

2- Site coordinate calculation and transcription on the map• Positioning (measurment from know map reference point), triangulation, GPS

3- Scaled and directed block plan (site sketch)• It shall show:• the radio building• tower with possible guy wires• power supply building(s)• fences• access points to the station• notification of possible obstructions in the near field



4- Tower elevation layout• tower height / obtain « tower registration number » (North America only)• structure (hip, wind bracing, batter)• V and H cable routes (structure)• coverage of existing antennas and those to be supplied• report on tower's ground connections

5- Indoor layout• layout of existing equipment• layout of equipment to be supplied• secondary energy routing• LF signal routing• Feeder routing

6- Existing frequency list

On site methodologyOn site methodology



7- Fill in the data sheet• Develop on site engineering chart and fill in the bill of quantity• Take photos

II) 2nd STATION (Repeater station)1- Altitude measurement2- Coordinate calculation3- Distance and azimuth calculation with the help of the calculator or GPS4- Site lay out plan (with station azimuth enclosed)5- Tower elevation plan6- Indoor layout plan7- Data sheet - engineering chart - "Bill of quantity".8- Link budget in case the type of antenna is unknown




III) In the evening, at the hotel1- Computerize the data sheet2- Define the profile on map and computerize it3- Develop the link budget4- Organize the work load of the next day

IV) Methodology to be used for new stations1- Look on site for the best, locate it on the map. The location shall be

accessible and free from radio obstructions.Take into account power supply distribution. Close to medium, low or high voltage power supply.

2- Altitude measurement and coordinate calculation3- Calculation of azimuths and distances4- Localization of possible obstructions5- Development of a profile if no station visibility6- Calculation of tower height to define the area required




7- Control of critical points (altitude and vegetation measurement) to arrange aerial height

8- Site layout9- Elevation drawing10- Indoor layout drawing if required11- Data sheet, engineering chart, … Access map if necessary12- Tower, building and mark stacking13- Photos

This procedure is applicable for any network, microwave system and surveyor.





ContentsContents1) Introduction

- Survey definition










INTRODUCTIONINTRODUCTIONOn path methodologyOn path methodology

I) Urban

1- When the network is located in a urban area, 99% of the links are short or very short distances. In this case, if the end far site is visible with naked eye (or binocular) and adequate clearance is obsereved, the surveyor can supposed that the LOS is good. Because the topographic contour information is usually less controlling (clearances are usually controlled by structures in a heavy urban environment) the path profile is sometimes less significant in determining LOS.

II) Long Haul

1- In this case, even with binoculars, it may not be possible to confirm the LOS. Consequently, a preliminary path profile must be done with topographics maps and after field survey, the same path profile must be confirmed with the new field inputs (coordinates, altitude, vegetation height…)



1) Introduction

- Survey definition








5) Link budget calculation- ITU-R recommendation- Link budget calculation - North American (NA) and ITU-R Path Reliability (Outage) Calculations


• List of equipment

– 1 "pilot case" including:

• 2 THOMMEN altimeters• 1 CHAIX compass• 1 GPS + Antenna• 1 Portable PC• 1 printer• 1 camera• 1 pair of binoculars with compass inside• 1 Safety harness• 1 50 m tape• 1 5m tape• Inclinometer• Flashing Mirrors

LIST OF TOOLS USED DURING THE SURVEYLIST OF TOOLS USED DURING THE SURVEY

–1 set of accessories:

• 1 Drawing board• 1 map-meter• 1 programmable calculator• 1 high-power magnifier• Flexible rules, protractors, squars• 1 pair of drawing compasses• 1 set of drawing pencils and erasers• DB scale for coordinate plot

• The following tools will be added if necessary• Grounding tester• Post and spray paint for site marking


• Chaix degree compassCompassCompass



Digital altimeterDigital altimeter



ContentsContents


1) Introduction

- Survey definition






- Site visit / On path data collection

- Survey report4) Proprietary application software

- Azimuth- Profile- Pathloss



• If the visited site is an existing one, the following points will be checked and registered.

• Site lay out on which will appear the different elements such as: tower, tower guy anchors, buildings, fences, close range obstacles.

• Obtain (North America only):– Call Sign– Tower registration number– Street address

DATA AND SURVEY REPORTDATA AND SURVEY REPORT

Site visitSite visit











• For a tower:

– Height, structure , legs and bracing dimensions at necessary heights

– Types and length of vertical and horizontal waveguide runways

– Location , types and directions of existing antennas

– Locations available for the new antennas

– Locations available for the new feeders or coaxial cables

– Tower and waveguide runways earthing

– Tower registration number (North America only)
















• For a building:

– Location of existing equipment’s

– Frequencies of existing equipment’s

– Location available for proposed equipment’s

– Distribution frames and blocks location for customer access and remote alarms connection

– AC and DC power availability and access , capacity installed and used

– Earthing devices, availability, connection possibilities

– Cable ways : availability , extensions required, available WG ports.







Station: JESENIK

Room for transmission equipment
















ContentsContents


1) Introduction

- Survey definition










Survey reportSurvey report


• The results will be presented in a Survey Report which will give the following information:

– Site information sheet indicating: the access, co-ordinates, altitude, etc....– Site access detailed plan (if necessary)– Site lay out– Building lay out– Equipment’s rooms lay out showing the location of: existing transmission

equipment, AC and DC power equipment, distribution frame, earthing, etc....and proposed location for the new one

• Tower sketch indicating the: location of existing antennas, available and proposed locations for the new ones, structure of the tower

• Pictures of the most relevant elements– Path profile of every microwave link (if applicable)– Network diagram indicating azimuths and distances– Path azimuth photo



Survey reportSurvey report• Specific spreadsheet


ContentsContents

FIELD TELECOMMUNICATION SURVEY FIELD TELECOMMUNICATION SURVEY

1) Introduction

- Survey definition







4) Proprietary application software- Azimuth

- Profile- Pathloss



PROPRIETARY APPLICATION SOFTWAREPROPRIETARY APPLICATION SOFTWARE

Software application

• HARRIS has developed software application TOOLS called Pathloss to facilitate network design:

– 1 AZIMUTH : network topology– 2 PROFILE : link profiles– 3 PATH CALCULATION : point-to-point point-multipoint link budget– 4 FREQUENCIES INTERFERENCE ANALYSIS– 5 EQUIPMENT LIST & SUMMARY


Azimuth

• Objective: Draw the network layout and calculate the distances and the azimuts between the various stations.

• Input data:– Station names– Station coordinates and altitudes– Type of architecture– Link between the stations

• Output data:– Distance to the previous station– Azimut to the previous station– Site angle to the previous station– Layout of the network



Azimuth



Azimuth



ContentsContents

FIELD TELECOMMUNICATION SURVEY FIELD TELECOMMUNICATION SURVEY

1) Introduction

- Survey definition





2) List of tools used during the survey

3) Data and survey report


- Survey report

4) Proprietary application software

- Azimuth

- Profile

- Pathloss

5) Link budget calculation

- ITU-R recommendation

- Link budget calculation

- North American (NA) and ITU-R Path Reliability (Outage) Calculations


Profile

• Objective: Draw the path profile between 2 stations, taking into account the clutter and the earth factor.

• Input data:– Station names– Station and antenna altitudes– Frequency– Earth factor– Specified clearance– Distance, altitude and vegetation of several points between the 2 stations

• Output data:– Drawing of the profile– Critical point and clearance in this point– Optimal antenna heights



Profile



Profile



Path Calculation:

• Objective: calculate the link budgets for point-to-multipoint equipment, identify the antennas sizes, guarantee the availability compliance with ITU Rec./ Vigants 1975

• Input data:– Frequency– Hop length– Fading parameters– Stations name– Feeder types & lengths– Antenna types– Equipment losses– Transmit power– Depointing and reflection losses



Path Calculation:

• Output data :

– Free space losses– Wave guide losses– RF received level– Gross and net margins– Outage time hop per hop and cumulated– Compliance status with objectives



Path Calculation

PROPRIETARY APPLICATION SOFTWAREPROPRIETARY APPLICATION SOFTWAREMicrowave Worksheet - A-B.pl4

A B

Elevation (m) 2.00 2.00

Latitude 13 56 01.00 N 13 50 25.00 N

Longitude 100 34 08.00 E 101 00 53.00 E

True azimuth (°) 102.04 282.15

Vertical angle (°) -0.17 -0.17

Antenna model HSX10-44 (R) HSX10-44 (R)

Antenna height (m) 70.10 70.10

Antenna gain (dBi) 40.60 40.60

TX line type EWP43(4.7GHz) EWP43(4.7GHz)

TX line length (m) 90.00 90.00

TX line unit loss (dB /100 m) 2.80 2.80

TX line loss (dB) 2.52 2.52

Connector loss (dB) 0.50 0.50

Antenna model HSX10-44 (R) HSX10-44 (R)

Antenna height (m) 55.00 55.00

Antenna gain (dBi) 40.60 40.60

TX line type EWP43(4.7GHz) EWP43(4.7GHz)

TX line length (m) 80.00 80.00

TX line unit loss (dB /100 m) 2.80 2.80

TX line loss (dB) 2.24 2.24

Connector loss (dB) 0.50 0.50

Frequency (MHz) 4700.00

Polarization Horizontal


Path Calculation

PROPRIETARY APPLICATION SOFTWAREPROPRIETARY APPLICATION SOFTWAREMicrowave Worksheet - A-B.pl4

A B

Path length (km) 49.28

Free space loss (dB) 139.76

Atmospheric absorption loss (dB) 0.37

Field margin (dB) 1.00

Main net path loss (dB) 65.97 65.97

Diversity net path loss (dB) 65.69 65.69

Radio model SDH 5 28MHz Plan SDH 5 28MHz Plan

TX power (watts) 0.60 0.60

TX power (dBm) 27.80 27.80

EIRP (dBm) 65.38 65.38

TX Channels 1h 4418.0000H 1l 4730.0000H

RX threshold criteria BER 10-6 BER 10-6

RX threshold level (dBm) -68.50 -68.50

Main RX signal (dBm) -38.17 -38.17

Diversity RX signal (dBm) -37.89 -37.89

Thermal fade margin (dB) 30.61 30.61

Number of exposures 1

Interference fade margin - multipath (dB) -5.04

Flat fade margin - multipath (dB) -5.04 30.61

Dispersive fade margin (dB) 45.00 45.00


Path Calculation


Microwave Worksheet - A-B.pl4

A B

Dispersive fade occurrence factor 3.00

Effective fade margin (dB) 30.16

Climatic factor 1.00

Terrain roughness (m) 6.10

C factor 3.29

Fade occurrence factor (Po) 1.11E+00

Average annual temperature (°C) 27.00

SD improvement factor 99.32

Worst month - multipath (%) 99.99814

(sec) 48.89

Annual - multipath (%) 99.99930

(sec) 219.99

(% - sec) 99.99930 - 219.99

A-B.pl4

Reliability Method - Vigants - Barnett

Space Diversity Method Harris IF Combining


ContentsContents


1) Introduction

- Survey definition








- Survey report


- Azimuth

- Profile

- Pathloss






• ITU-T: International Telecommunications Union - Telecommunications sector– Technical advisory body on telecommunications networks

• ITU-R: International Telecommunications Union - Radiocommunications sector– Technical advisory body on radiocommunications– Workgroups, study groups, meeting: definition of recommendations– Lays the foundations of the world radio conference (every 2 years)

publication of radiocommunications regulations (Mandatory international Treaty)

LINK BUDGET CALCULATIONLINK BUDGET CALCULATION

ITU-R recommendationITU-R recommendation


• Purpose to define the link performance level

– Quality (error performance)

– Availability (or unavailability)

• Parameters:

– Link characteristics

– Equipment characteristics

• Compliance with the objectifs




• Definition:

– A digital link is a digital section as defined in Rec 634, 696 and 697 when it carries a constant-bit rate signal between two terminals with no multiplexer / demultiplexer in between

– It comprises one or several switching sections, themselves comprising one or several hops




• Digital microwave link's performance level is measured with:

– Quality level (or error performance): fraction of the worse month during which BER 10-3 period in which the link is considered as available.

– Unavailability level: fraction of total time in one year in which BER 10-3 (during each second in a period of 10 consecutive seconds)




• Error performance objectives are defined in ITU-T recommandations:

– G.821, reviewed G.821

– G.826, replacing G.821

• The UIT-T does not define unavailability objectives




• Main reason for non quality: multiple path propagation

– Fadings due to atmospheric multiple paths

– Fadings due to ground reflections




• ITU-T G.821 (reviewed G.821) defined 3 quality areas within 64 kbit/s fictive reference communication

• ITU-R applies the ITU-T recommendations to real digital links using microwave systems

– High quality area, Rec. 634 (+ review project)

– Medium quality area, Rec. 696 (+ review project)

– Local quality area, Rec. 697 (+ review project)




• ITU-R's criteria for quality objective (before definition ITU-T Rec. G.821 review)

– Percentage of time with BER 10-3 (SES)

– Percentage of time with BER 10-6 (DM)

– Percentage of time with errored seconds (ES)

– Residual bit error rate (R BER)

• SES: Severly Errored Second

• DM: Degraded Minutes




• ITU-R's criteria for quality objective definition (since ITU-T G.821 Rec. review)

– Percentage of time with BER 10-3

– Percentage of time with errored seconds

• Degraded minutes and residual bit error rate concepts are abandoned

– SESR: Severly Errored Second Ratio

– SER: Errored Second Ratio




ITU-R's objectives for quality (error performance)

(before ITU-T G.821 Rec.Review, en % of the more month

Quality

parameters

High quality

area

(Rec. 634) (4)

Medium quality area (Rec. 696)

BER > 10-3 (ses)

BER > 10-6 (DM)

Errored Sec.(64 kbit/s)

RBER

(L/2500) x 0.054 (1)

(L/2500) x 0.4

(L/2500) x 0.32

(L/2500) x5 x 10-9

Class 1

280 km

0.006 (2)

0.045

0.036

5.6 x 10-10

Class 2

280 km

0.0075 (2)

0.02

0.16

under study

Class 3

50 km

0.002 (3)

0.2

0.16

under study

Class 4

50 km

0.005 (3)

0.5

0.4

under study

Local quality

area

(Rec. 697

0.015

1.5

1.2

under study

(1): including 0.05 % for propagation(2): including 0.0055 % for propagation

(3): add 0.125% by default for propagation(4): for L < 280 km, class 1 objective




ITU-R's objectives for quality (error performance)

(after ITU-T G.821 Rec.Review, in fraction of ordinary month)

Quality

parameters

High quality

area

G.634 Rec. Review

Medium quality area (Rec. 696)

BER > 10-3 (SESR)

Errored Sec.(SES)

(L/2500) x 0.00054

(L/2500) x 0.0032

Class 1

280 km

0.00006

0.00036

Class 2

280 km

0.000075

0.0016

Class 3

50 km

0.00002

0.0016

Class 4

50 km

0.00005

0.004

Local quality

area

G.697 Rec.Review

0.00015

0.012

Degraded minutes and residual bit error rate concepts are abandoned




• Unavailability criteria:

– Hypothetical reference path is unavailable when in at least one transmission direction, digital signal is stopped or when BER is noise than 10-3 during at least 10 consecutive seconds




• Unavailability causes

– Equipment• Modulator, power supply, antenna

– Propagation• Important variation of atmospheric refraction rain

– Other causes• Noise interference, human activity ...




• The following ITU-R, recommendations define availability objectives for real links

– High quality areas: REC. 695

– Medium quality areas: REC. 696

– Local quality areas: REC. 697

• These objectives are global, without allocation to the various possible causes




Availability objectives in relation to the rain: standard / superior

AVAILABILITY UNAVAILABILITY

STANDARD

SUPERIOR

99.99 % 1.10-2 % = 0.01 % = 1.10-4 of the year 50 mn / a year

99.999 % 1.10-3 % = 0.001 % = 1.10-5 of the year 5 mn / a year

The objective has to be chosen by mutual agreement with customer

Standard objective is generally chosen by default




• Digital microwave link planning and implementation must be performed in compliance with these recommendations

• It is therefore necessary to have a forward - looking calculation method for digital link quality and availability




• Link budget parameters

• Link characteristics:

hop length, climate, profile ...

• Equipment characteristicstransmitted power, receiving thresholdconnection losses, antenna gain ...




ContentsContents


1) Introduction

- Survey definition








- Survey report


- Azimuth

- Profile

- Pathloss






Gross marginMB = PE - L1 + G1 - PEL + G2 - L2 - PS

PE : transmitted powerL1 : connection losses, feederG1 : station 1 antenna gainPEL : losses of free spaceG2 : station 2 antenna gainL2 : connection losses, feederPS : receiving threshold (sensitivity, station 2)

E1 R1 R2E2


Link budget calculationLink budget calculation


Probability to exceed a given error rate of 10-n during the

worse month

P = K d3.6 f-0.89 (1+ |p|)-1.4 10-MN/10 (%)

f: frequency (GHz)d: hop length (Km)MN: hop net margin (dB) for BER =

10-n

p = |hr - he| / d path tilt (milliradians)

K = 10-5.4 PL1.5 terrestrial paths, non mountainous regions

K = 10-6 PL1.5 terrestrial paths, mountainous regions

K = 10-4.9 PL1.5 paths above wide surfaces of water

PL: percentage of time in which mean gradient of refractivity in the first 100 m of atmosphere is < -100N units / km (ITU-R Rec.453)




A0.01 path attenuation exceeded during 0.01% of time is

given by the formula (Rec.530)

The values of attenuation exceeded during other

percentages of time (0.001 % < P < 1 %) are defined by:

A0.01 = R.deff = R.d.r (dB)

r = 1 / (1 + d/d0): distance factor

d0 = 35 exp(-0.015 R0.01)

R = K.R: attenuation coefficient

R0.01: rainfall intensity exceeded during 0.01% of time

Ap = A0.01 0.12P-(0.546 + 0.043 log (P))(dB)




The fraction of total time during which the link is unavailable because of the rain in one year is equivalent to the probability for rain attenuation to exceed aperiodic attenuation margin (gross margin MB minus the reduction created by interference) on each hop in the link.

A0.01 = R.deff = R.d.r

MF =Ap = A0.01 0.12P-(0.546+0.043log(P))

P=4.5.10-9 .10(18.9-23.5log(MF / A0.01))0.5 for (MF/A0.01)<3.8

P<1.10-6 for (MF/A0.01)>3.8




ContentsContents


1) Introduction

- Survey definition








- Survey report


- Azimuth

- Profile

- Pathloss




- North America (NA) and ITU-R Path Reliability (Outage) Calculations


North American (NA) and ITU-RNorth American (NA) and ITU-RPath Reliability (Outage) Calculations* Path Reliability (Outage) Calculations*

*Vigants’ North American and CCIR Rep. 338 Link Calculations for PDH Links. See Ref. 4,

Appendix C for ITU-T Rec. G.826 Link Calculations and the Harris MCD Seminar

Supplements for ITU-R Rec. P.530-6/8and ITU-R Rec. P.530-9/10 Link Calculations.


Performance CalculationsPerformance Calculations

Topics Performance Period (year or any-month)

Probability of Outage, U or SESR

Probability of Multipath Outage Calculations1) Vigants’ North American Model2) Vigants’ CCIR Rep. 338 Model3) ITU-R P.530 Models (see Seminar Supplements)

Space, Frequency, 1:N, and Hybrid DiversityImprovements - ISD, IFD, I1:N, IHD

Path Geometry


Multipath Fading OccurrenceMultipath Fading Occurrence

Radio frequency (~F),

Path length (~D3 ND to ~D4 SD, FD, etc.),

Humidity/temperature gradients,

Terrain flatness,

Calmness of the wind, stratification,

Fog, ducting, layering atmosphere,

and decreases with:

Multipath fading increases with:

Path inclination,

Atmospheric turbulence,

Terrain roughness.


Performance StandardsPerformance Standards

North American performance objectives and computations are annual, which accommodate a “fade season”.

ITU-R performance (outage and quality) objectives and computations are calculated over “any month” or “worst fading month.”

North America vs. ITU-R Performance Period

Conversions to/from North American annual outage performance and ITU-R “any month” performance are provided.


Probability of Multipath OutageProbability of Multipath Outage

Outage Time = UND or USD x Fading Period, sec

= SES/yr or SES/any month.

For a given path, U and SESR are numerically the same in both NA and ITU-R computations.

The Fading Period is a 2.1-4.6 mo (5.5-12x106

sec) fade season in NA (proportional to the average annual temperature), and a 30-day (2.6x106 sec) worst fading month in ITU-R areas.

The first step in the prediction of multipath outage is the probability of outage, UND computation as a Severely-Errored Second Ratio. UND = SESR for a non-diversity link.



UND = SESR = 2.5x10-6 c f D3 10-CFM/10

= 0.0001042

when, for example:

UND = Non-diversity probability of outage (SESR)c = NA climate-terrain factor

= 1 (from c map), or x(w/50)-1.3

x = NA climate factor, 1 (from x map)w = Terrain roughness, 50 ft (from profile)f = 6.7 GHzD = Path length, 25 miCFM = Composite Fade Margin, 34 dB

Vigants’ North American (NA) Model


NA Climate-Terrain Factors, cNA Climate-Terrain Factors, c

As revised by Bellcore 9/86As revised by Bellcore 9/86

c = 0.25

c = 1

c = 2

c = 1

c = 4

c = 6

c = 0.25c = 1

c = 4

Alaska coast, c = 0.25Alaska interior, c = 1

Hawaii, c = 4

Caribbean, c = 4

c = 0.25


NA Climate Factors, x NA Climate Factors, x

*Flat terrain (w = 20', c =6) in this climate area.

Hawaii, x = 2

Alaska, x = 1 (inland)x=0.5 (coastal)

Caribbean, x = 2

southern Yukon, British Columbia,x = 0.5 Other Canadian Provinces, x = 1


Annual Outage Time, TAnnual Outage Time, TNDND

TND = UND (SESR) x Fade Season, SES/yr

= UND x 8x106 sec [3 mo] x t/50where

TND = One-way outage (non-diversity), SES/yr

t = Average temperature, 50oF (from map).Therefore

NA TND = 0.0001042 8x106 50/50

= 834 SES/yr

Bellcore 25 mi Link Outage Objectives (1600 SES/T1 trunk/yr):

Short-haul (10 hops) = 6.4 SES/hop/mi/yr = 160 SES/hop/yr

Long-haul (75-150 hops) = >0.8 SES/hop/mi/yr = >20 SES/hop/yr


Average Annual Temperature, tAverage Annual Temperature, t

Alaska, Canada: Use 35° F (Vigants’ minimum)

Hawaii, South Florida, and the Caribbean are 750F (Vigants’ maximum)

oF



UND (SESR) = KŸQ f D3 10-CFM/10

= 0.0001042 (same as NA calculation)

when, for example (same as NA path):

UND = Non-diversity probability of outage (SESR)KŸQ= ITU-R climate-terrain factor

= x(S)-1.3

x = Climate factor, 2.1x10-5 (from following table)S = Terrain roughness, 15.2 m (from profile)f = 6.7 GHzD = Path length, 40 kmCFM = Composite Fade Margin, 34 dB

Vigants’ ITU-R Report 338 model, same path as NA:


Vigants’ ITU-R Climate FactorsVigants’ ITU-R Climate Factors

Climate Regions x (ITU-R) x (NA)

Maritime temperate, coastal 4.1x10-5 2.0or high humidity/temperature

Maritime sub-tropical 3.1x10-5 1.4

Continental temperate or 2.1x10-5 1.0mid-latitude inland

High-dry mountainous 1.0x10-5 0.5

Climate-Terrain Factors: KŸQ = xS-1.3 c = x(w/15)-1.3

S,w = Terrain roughness, 6-42m range

and equivalent North American values of “x”


Multipath Outage Models (1)Multipath Outage Models (1)

Non-Diversity Probability of Outage UND (SESR) Models

Vigants’ North American Outage ModelUND = 6x10-7 c f D3 10-CFM/10

Vigants’ ITU-R Rep. 338 Outage ModelUND = KŸQ f D3 10-CFM/10

1995 ITU-R P.530-5/6 Method 2 Outage Model*UND = K/100 f 0.93 D3.3 (1+ p)-1.1 -1.2 10-CFM/10

1999 ITU-R P.530-7/8 Outage Model* UND = K/100 f 0.89 D3.6 (1+p)-1.4 10-CFM/10

2001 ITU-R P.530-9/10 “Detailed Link Design” Outage Model* UND = KD/100 D3.2 (1+p)-0.9710-0.032f –0.00085h -CFM/10

Notes: D is in km, K and KD are given as a % in the ITU-R tables. K/100 derives SESR.


Multipath Outage Models (2)Multipath Outage Models (2)

UND = SESR = Non-diversity probability of multipath outage

c, KŸQ = Vigants’ NA and ITU-R climate/terrain factors

K = Geoclimatic factor, with PL, highest % ducting

KD = 10-3.9 – 0.003 dN1 sa-0.42 (P.530-9 “Detailed Link Design”)

dN1 = Point refractivity gradient in the first 65m

sa = 110x110m area terrain roughness from GTopo30 data

f = Frequency, GHz h = Elevation amsl of the lowest antenna, m

D = Path length, km CFM = Composite Fade Marginp = Path inclination angle, 0-24 mrad range = k=4/3rds grazing angle over a flat average terrain plane,

1-12 mrad range (P.530-5/6 Method 2 only) *mrad = milliradian 1o = 17.5 mrad 1 mrad = 0.0573o

Notation


ITU-R Annual Outage Time, TITU-R Annual Outage Time, TNDND

TND (month) = 0.0001042 x 2.6x106 sec/mo = 270 SES/any month outage

TND (year) = SES/any mo x 3.1 mo x t, oF/50

where

t, oF = Annual average temperature, oF (see following chart for oF - oC)

TND Year = 270 x 3.1 x 50/50 (50oF/10oC)= 834 SES/yr (same as NA calc.)

Outage time (SES/yr or SES/any month), not an ITU-R parameter, may be computed for field measurements and comparison to North American calculations:


0F 0C-50 -46-40 -40-30 -34-20 -29-10 -23 0 -18 10 -12 20 -7 30 -1 40 4 50 10 60 16 70 21 80 27

By Vigants’ model, minimum temperature is 350F (20C) and maximum is 750F (240C)

50

6070

80

70

70

6050

403020100

-10

-20 -40 -50

-30

80 70

Average Annual Temperature, t

0F


1+1 Space Diversity - I1+1 Space Diversity - ISD SD (1)(1)

Performance objectives

Frequency band

Path length, inclination

Path geometry (clearance, reflection zone location, diversity dish size and spacing; path: flatland? mountainous?)

Climatic conditions (k-factor range; ducting?)

Support structure (building, space, tower loading)

Aesthetic, architectural, zoning constraints

Depends upon:


1+1 Space Diversity - I1+1 Space Diversity - ISD SD (2)(2)

TSD = TND/ISD

NA ISD = 7x10-5 f s2 10CFM/10/D= 42 (SD dish separation s = 30 ft)

TSD = 834/42 = 20 SES/yr (meets objective)

ITU ISD = 1.2x10-3 f s2 10CFM/10/D= 42 (s = 9.1 m), same as NA above

TSD = 270/42 = 7 SES/any month (meets objective)

Since the computed 834 SES/yr and 270 SES/any month non-diversity outages are excessive, diversity is added. The following Space Diversity Improvement (ISD) assumes equal main and diversity path fade margins (CFMs):


Space Diversity - IF Combining

Errorless Data Switching between diversity receivers anticipates a degraded condition (e.g. IFslope alarm, FEC syndrome counts) and rapidly switches the data before data errors occur.

Dispersion-Sensing IF Combiners monitor signal distortion, muting that signal with excessive dispersion. Lacking this feature, the output signal could be more distorted than either input, thus increasing outage.

The Space Diversity ISD model is equally applicable to links with receivers using either Errorless Data Switching or Dispersion-Sensing IF Combiners:


1+1 Frequency Diversity - I1+1 Frequency Diversity - IFDFD

NA IFD = 50 f 10CFM/10/f2 DMI

= 18 TFD = 834/18 = 47 SES/yr

ITU IFD = 80 f 10CFM/10/f2 DKM

= 18 TFD = 270/18 = 15 SES/any month

where

f = Diversity spacing, 0.16 GHz (2.4%)

In most ITU-R and some North American regions - Canadian electrical utilities or in the U.S. with FCC waiver - frequency and hybrid diversity may be used. Except with >5% f diversity spacings, IFD is less than ISD, but NA and ITU-R outage objectives are often met with IFD.

Example:


1:N Frequency Diversity - I1:N Frequency Diversity - I1:N1:N

Multiline 1:N links are assigned space diversity with 1+1 IF combining or 1:N frequency diversity to meet outage objectives. In the above IFD calculation, the diversity spacing f is replaced with fEQ in 1:N links. 1:3 link example:

fEQ = ___________N________________ , GHz

N + N-1 + N-2 + … + _1_ f 2f 3f Nf

where:fEQ = Equivalent FD spacing in the IFD calculation

N = Number of bearer channels (3, in a 1:3 link) f = Actual RF channel spacing (0.160 GHz), (starting with the

smallest spacing, if non-symmetrical)

fEQ = 0.111 GHz (111 MHz, compared to f = 160 MHz) I1:N = 12.4 (compared to IFD = 18)


Hybrid Diversity - IHybrid Diversity - IHDHD

If the highest T and R frequencies are assigned to the upper antenna at the vertically-spaced antenna end of this link, the any-month (and annual) outage times is further reduced by 2-10% (2x100 f/f) compared to space diversity alone.

Although only ISD is used in many hybrid diversity outage calculations (ISD = 42 in these examples) a more accurate IHD model adds these improvements to reflect Hybrid Diversity’s even better performance:

IHD = ISD + IFD = 42 + 18 = 60 in these examples

Hybrid (space+frequency) Diversity can be used in most ITU-R (and some NA) paths.


Vigants’ Annual Outage Time, TVigants’ Annual Outage Time, T

TND = 0.4 c f t D3 10-CFM/10

= 0.4 1 6.7 50 253 10-34/10

= 834 SES/yr (same as previous calculation)

TSD = 5.7x103 c t D4 10-CFM/5/s2

= 5.7x103 1 50 254 10-34/5/302

= 20 SES/yr (same as previous calculation)

Note that frequency is irrelevant and that outage varies as D4 in all diversity links (SD, FD, HD)

Simplified ND and SD Annual Outage Calculations


Required Fade Margin (CFM)Required Fade Margin (CFM)

Req’d CFM (NA) = -5 log (3.5x10-6 s2 T)/(c t/50 D4)

= -5 log (3.5x10-6 302 20)/(1 50/50 254)

= 34 dB (same as previous computation)

The outage equations are combined to derive the required fade margin for a space diversity link (TNA = 20 SES/yr):

Req’d CFM (ITU) = -5 log (4.6x10-10 s2 T)/(K•Q D4)= -5 log (4.6x10-10 92 22)/(6.2x10-7 404)= 31.4 dB

The ITU-R outage equations may also be combined:

The above ITU-R required CFM calculation reflects a higher outage objective (22 SES/any-month) compared to the 7 SES previously computed with the larger 34 dB fade margin (CFM).


Outage Calculation ConstraintsOutage Calculation Constraints

“Normal” multipath fading only:

Excludes specular reflection fade outages in ND links and non-optimum dish separations in SD links

No fade margin reductions due to power fading(antenna decoupling or misalignment, ducting, etc.)

Excludes (or accommodate) interference

Excludes dispersive fade outages (link DFM<50 dB)

Excludes SES outage due to module switching, failures, and maintenance activity.

Rain outage is annualized over a ~10 year period

The “Fine Print” - Multipath Outage Predictions assume the following:


Path Calculation SheetsPath Calculation Sheets

Antenna sizes, Feeder (coax or waveguide) type, Radio system gain and adaptive equalization, and Diversity arrangements meeting performance objectives,

Frequency band, Antenna heights (path clearances from profiles),Antenna min/max size constraints (decoupling, DFM), Antenna types (standard, or HP for interference), and Diversity spacings (for uncorrelated fading)

Final path calculations, which select the

are prepared only after the

have been already been assigned.


Path Geometry ComputationsPath Geometry Computations

Location of the reflection zone (dish heights?)

Dish discriminations to the reflection (dish sizes?)

Fresnel clearance at the reflection (diversity? spacing?)

Path inclination angle

Reflection grazing angle (V- or H-pol assignment?)

Ray height at the reflection or obstruction area

Reflected ray time delay, nsec (link’s DFM?)

Optimum diversity dish separations to specular reflections

RSL up or down fade depth to a specular reflection

Arrival angle with k-factor variations (dish sizes?)

Obstruction loss vs. terrain type (“knife-edge”, etc.)

Provide the:


Difficult Digital Microwave PathsDifficult Digital Microwave PathsDefinition: Those paths which support Analog Radio links but may degrade less robust (older) Digital Radios:

Path is short (perhaps <25mi/40km), but has excessive clearance over exposed (little path blockage and dish discrimination to) terrain supporting long-delayed (>10 nsec/10ft/3m) multipath reflections. Burst ES and SES outages may occur if the link's DFM (radio DFM + antenna discriminations) is less than about 50 dB.

Path is very long (perhaps >50mi/80km) and affected by elevated atmospheric ducting layers which generate extremely rapid multipath fade activity. SES outages may occur if the receiver quadrature recovery (relock) time is >100 msec.


Geometry - Short, High PathGeometry - Short, High Path20 Mile Path

REFLECTION OR OBSTRUCTION, K=1.33 <FT

AMSL, Mi>X ELEV=1,200.R ELEV=0.

DISTANCE=20.00Y ELEV=1,200.

DIST XR=10.00DIST RY=10.00

H<R>=1,150.ANT. DISC. :

X,DEG=1.248Y,DEG=1.248

FREQ=2.000 GHzF<N>=101.76

SD DISH SEP:SD<X>=18.3SD<Y>=18.3

DELAY, NS=25.44RSL<R=1>, dB=-11.45

R,DEG=1.248

32 km Path

REFLECTION OR OBSTRUCTION, K=1.33 <M

AMSL, KM>X ELEV=365.R ELEV=0

DISTANCE=32.19Y ELEV=365.


H<R>=350.ANT.DISC.:

X,DEG=1.246Y,DEG=1.246

FREQ=2.000 GHZF<N>=101.76SD DISH SEP:

SD<X>=5.6SD<Y>=5.6

DELAY,NS=25.44RSL<R=-1>, dB=-11.15

R,DEG=1.246

1150 ft (351m)

K = 4/31.25O Discriminationto the Reflection

1200(365m)

750

500

250

0

1000

0 4 8 12 16 20(32 km)

1.248O

Grazing Angle

25 n

s

Multi

path D

elay

K =0.109O Decoupling

Angle

Distance,Mi

Ele

va

tio

n A

MS

L, F

t

with HP41CX REFL geometry printouts

Long delay (25 nsec) = poor radio DFM, but high (20+ dB) antenna discriminations at1.250 = good link DFM (>50 dB)


Geometry - Long, High PathGeometry - Long, High Path

100 Mile Path

REFLECTION OR OBSTRUCTION,K=1.33

<FT AMSL, Mi>X ELEV=2,400.R ELEV=0.

DISTANCE=100.00Y ELEV=2,400.


H<R>=1,150.ANT. DISC. :

X,DEG=0.250Y,DEG=0.250

FREQ=2.000 GHzF<N>=20.35


DELAY, NS=5.09RSL<R=1>, dB=-5.20

R,DEG=0.250

161 km Path

REFLECTION OR OBSTRUCTION,K=1.33 <M

AMSL, KM>X ELEV=731.R ELEV=0.

DISTANCE=161.00Y ELEV=731.


H<R>=350.ANT. DISC. :

X,DEG=0.249Y,DEG=0.249

FREQ=2.000 GHzF<N>=20.36


DELAY, NS=5.09RSL<R=1>, dB=4.77

R,DEG=0.249

K = 4/3

0.25° Discriminationto the Reflection

1500

500

0

1000

0 20 40 60 80 100(161 km)

0.249°Grazing Angle

5 ns

Multi

path D

elay

K = 0.543°

DecouplingAngle

Distance,Mi

2000

2400(731m)

1150 ft(350 m)

Ele

va

tio

n A

MS

L, F

t

with HP41CX REFL geometry printouts

Short delay (5 nsec) = good (>50 dB) radio DFM, needed since there is very little antenna discrimination on long paths.


Not Computing Path Geometry?Not Computing Path Geometry?

Too small Poor discrimination to reflections/interference (degraded link DFM/IFM, more reflection fading)

Too large and/or Subject to heavy multipath fade activity and more not uptilted outage due to antenna decoupling

Too high Exposed to the reflection, more feeder loss

Too low Obstructed path, power fading with ducting

Improperly spaced Correlated fade activity between dishes

Horizontally Deeper fade depth compared to V-polpolarized with grazing angle >0.2O

Antennas Possible Effect


Polarization SelectionPolarization Selection

Reduction of the reflection coefficient (fade depth) with V-pol (grazing angle >0.20). Rain outage on V-pol paths above 10 GHz is also reduced 40-60% compared to H-pol.

Reflection coefficient and fade depth vs. grazing angle (V- and H-pol)

Fade charts, V- and H-pol, showing much smaller specular reflection fade depths with V-polarization (Italian path, = about 0.40).

Maximum FadeDepth, dB (Reflection)

50+

20

14

10.5

8

6

4.5

3

2

1

0

–1.0

–0.9

–0.8

–0.7

–0.6

–0.5

–0.4

–0.3

–0.2

–0.1

0.0 0* 0.1* 0.3* 0.5* 1* 3* 5* 10* 30* 50* 90*

Maximum Fade Depth = 20 log _1_ 1+R

GRAZING ANGLE, , degrees

MA

GN

ITU

DE

, R


Path Calculations - ConclusionsPath Calculations - Conclusions

Vigants’ North American/ITU-R Rep.338 multipath outage model provides an accurate estimate of performance worldwide in optimally configured and aligned digital microwave links.

However, the new ITU-R Rec. P.530 model is replacing Vigants’ Rep. 338 model in many international regions.

The Transmission Engineer’s main function is to configure the path clearances, antenna heights, types, and sizes, and diversity schemes to accommodate

ducting (power fading), specular reflections, and interference over wide diurnal and seasonal variations in climate and terrain.

The Manufacturer’s Responsibility is to provide robust digital microwave radios with effective network management, and

Installation Crews must align antennas for optimum long-term performance.

Models and Responsibilities:


Useful FormulasUseful Formulas

For English (ft, mi, GHz, dB) Metric (m, km, GHz, dB)

Path Loss 96.6 + 20 log f + 20 log D 92.4 + 20 log f + 20 log D

Earth’s curvature 0.67 d1d2/k d1d2/12.7k

F1 radius 72.1 (d1d2/f D)0.5 17.3 (d1d2/f D)0.5

Fn radius F1 (n)0.5 F1 (n)0.5

Dish gain (55% eff) 7.5 + 20 log f + 20 log d 17.8 + 20 log f + 20 log d

Dish BW, degrees 66/fd 20/fd

Div. dish separation 1200 D/f h(t) 127D/f h(t)

Multipath delay, nsec Fn /2f Fn/2f

NOTATION: f = frequency, GHz D = path length

k = k-factor (4/3, etc.) d1, d2= distances (d1 + d2 = D)

h(t) = Tx dish height above n = Fresnel zone number

the reflection plane F1 = 1st Fresnel zone radius

d = dish diameter

Supplementing the Outage Model

Thank youwww.huawei.com

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