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FIELD TELECOMMUNICATION SURVEY
Microwave SURVEY Knowledge
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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
HUAWEI TECHNOLOGIES CO., LTD. Page 3Huawei Confidential
ContentsContents
FIELD TELECOMMUNICATION SURVEYFIELD TELECOMMUNICATION SURVEY
1) 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- Climate / Terrain / Rain charts
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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 …..
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ContentsContents
FIELD TELECOMMUNICATION SURVEYFIELD TELECOMMUNICATION SURVEY
1) 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 (NA) and ITU-R Path Reliability (Outage) Calculations
HUAWEI TECHNOLOGIES CO., LTD. Page 6Huawei Confidential
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. ...
INTRODUCTIONINTRODUCTION
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ContentsContents
FIELD TELECOMMUNICATION SURVEYFIELD TELECOMMUNICATION SURVEY
1) 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 (NA) and ITU-R Path Reliability (Outage) Calculations
HUAWEI TECHNOLOGIES CO., LTD. Page 8Huawei Confidential
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
INTRODUCTIONINTRODUCTION
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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)
INTRODUCTIONINTRODUCTION
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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
INTRODUCTIONINTRODUCTION
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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
INTRODUCTIONINTRODUCTION
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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
INTRODUCTIONINTRODUCTION
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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
On site methodologyOn site methodology
INTRODUCTIONINTRODUCTION
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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
On site methodologyOn site methodology
INTRODUCTIONINTRODUCTION
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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.
On site methodologyOn site methodology
INTRODUCTIONINTRODUCTION
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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 (NA) and ITU-R Path Reliability (Outage) Calculations
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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…)
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FIELD TELECOMMUNICATION SURVEYFIELD TELECOMMUNICATION SURVEY
1) 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 (NA) and ITU-R Path Reliability (Outage) Calculations
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• 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
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• Chaix degree compassCompassCompass
LIST OF TOOLS USED DURING THE SURVEYLIST OF TOOLS USED DURING THE SURVEY
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Digital altimeterDigital altimeter
LIST OF TOOLS USED DURING THE SURVEYLIST OF TOOLS USED DURING THE SURVEY
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ContentsContents
FIELD TELECOMMUNICATION SURVEYFIELD TELECOMMUNICATION SURVEY
1) 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 report4) 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
HUAWEI TECHNOLOGIES CO., LTD. Page 23Huawei Confidential
• 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
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DATA AND SURVEY REPORTDATA AND SURVEY REPORT
Site visitSite visit
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DATA AND SURVEY REPORTDATA AND SURVEY REPORT
Site visitSite visit
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DATA AND SURVEY REPORTDATA AND SURVEY REPORT
Site visitSite visit
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• 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)
DATA AND SURVEY REPORTDATA AND SURVEY REPORT
Site visitSite visit
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DATA AND SURVEY REPORTDATA AND SURVEY REPORT
Site visitSite visit
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DATA AND SURVEY REPORTDATA AND SURVEY REPORT
Site visitSite visit
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DATA AND SURVEY REPORTDATA AND SURVEY REPORT
Site visitSite visit
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DATA AND SURVEY REPORTDATA AND SURVEY REPORT
Site visitSite visit
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• 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.
DATA AND SURVEY REPORTDATA AND SURVEY REPORT
Site visitSite visit
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DATA AND SURVEY REPORTDATA AND SURVEY REPORT
Site visitSite visit
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Station: JESENIK
Room for transmission equipment
DATA AND SURVEY REPORTDATA AND SURVEY REPORT
Site visitSite visit
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DATA AND SURVEY REPORTDATA AND SURVEY REPORT
Site visitSite visit
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DATA AND SURVEY REPORTDATA AND SURVEY REPORT
Site visitSite visit
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DATA AND SURVEY REPORTDATA AND SURVEY REPORT
Site visitSite visit
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DATA AND SURVEY REPORTDATA AND SURVEY REPORT
Site visitSite visit
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ContentsContents
FIELD TELECOMMUNICATION SURVEYFIELD TELECOMMUNICATION SURVEY
1) 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 (NA) and ITU-R Path Reliability (Outage) Calculations
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Survey reportSurvey report
DATA AND SURVEY REPORTDATA AND SURVEY 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
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DATA AND SURVEY REPORTDATA AND SURVEY REPORT
Survey reportSurvey report• Specific spreadsheet
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ContentsContents
FIELD TELECOMMUNICATION SURVEY FIELD TELECOMMUNICATION SURVEY
1) 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 (NA) and ITU-R Path Reliability (Outage) Calculations
HUAWEI TECHNOLOGIES CO., LTD. Page 43Huawei Confidential
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
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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
PROPRIETARY APPLICATION SOFTWAREPROPRIETARY APPLICATION SOFTWARE
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Azimuth
PROPRIETARY APPLICATION SOFTWAREPROPRIETARY APPLICATION SOFTWARE
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Azimuth
PROPRIETARY APPLICATION SOFTWAREPROPRIETARY APPLICATION SOFTWARE
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ContentsContents
FIELD TELECOMMUNICATION SURVEY FIELD TELECOMMUNICATION SURVEY
1) Introduction
- Survey definition
- Objectives / scope
- On site methodology
- On path methodology
* Los: Urban, long haul…
2) List of tools used during the survey
3) 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 (NA) and ITU-R Path Reliability (Outage) Calculations
HUAWEI TECHNOLOGIES CO., LTD. Page 48Huawei Confidential
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
PROPRIETARY APPLICATION SOFTWAREPROPRIETARY APPLICATION SOFTWARE
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Profile
PROPRIETARY APPLICATION SOFTWAREPROPRIETARY APPLICATION SOFTWARE
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Profile
PROPRIETARY APPLICATION SOFTWAREPROPRIETARY APPLICATION SOFTWARE
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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
PROPRIETARY APPLICATION SOFTWAREPROPRIETARY APPLICATION SOFTWARE
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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
PROPRIETARY APPLICATION SOFTWAREPROPRIETARY APPLICATION SOFTWARE
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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
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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
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Path Calculation
PROPRIETARY APPLICATION SOFTWAREPROPRIETARY APPLICATION SOFTWARE
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
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ContentsContents
FIELD TELECOMMUNICATION SURVEYFIELD TELECOMMUNICATION SURVEY
1) Introduction
- Survey definition
- Objectives / scope
- On site methodology
- On path methodology
* Los: Urban, long haul…
2) List of tools used during the survey
3) 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 (NA) and ITU-R Path Reliability (Outage) Calculations
HUAWEI TECHNOLOGIES CO., LTD. Page 57Huawei Confidential
• 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
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• Purpose to define the link performance level
– Quality (error performance)
– Availability (or unavailability)
• Parameters:
– Link characteristics
– Equipment characteristics
• Compliance with the objectifs
LINK BUDGET CALCULATIONLINK BUDGET CALCULATION
ITU-R recommendationITU-R recommendation
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• 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
LINK BUDGET CALCULATIONLINK BUDGET CALCULATION
ITU-R recommendationITU-R recommendation
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• 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)
LINK BUDGET CALCULATIONLINK BUDGET CALCULATION
ITU-R recommendationITU-R recommendation
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• 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
LINK BUDGET CALCULATIONLINK BUDGET CALCULATION
ITU-R recommendationITU-R recommendation
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• Main reason for non quality: multiple path propagation
– Fadings due to atmospheric multiple paths
– Fadings due to ground reflections
LINK BUDGET CALCULATIONLINK BUDGET CALCULATION
ITU-R recommendationITU-R recommendation
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• 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)
LINK BUDGET CALCULATIONLINK BUDGET CALCULATION
ITU-R recommendationITU-R recommendation
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• 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
LINK BUDGET CALCULATIONLINK BUDGET CALCULATION
ITU-R recommendationITU-R recommendation
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• 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
LINK BUDGET CALCULATIONLINK BUDGET CALCULATION
ITU-R recommendationITU-R recommendation
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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
LINK BUDGET CALCULATIONLINK BUDGET CALCULATION
ITU-R recommendationITU-R recommendation
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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
LINK BUDGET CALCULATIONLINK BUDGET CALCULATION
ITU-R recommendationITU-R recommendation
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• 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
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ITU-R recommendationITU-R recommendation
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• Unavailability causes
– Equipment• Modulator, power supply, antenna
– Propagation• Important variation of atmospheric refraction rain
– Other causes• Noise interference, human activity ...
LINK BUDGET CALCULATIONLINK BUDGET CALCULATION
ITU-R recommendationITU-R recommendation
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• 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
LINK BUDGET CALCULATIONLINK BUDGET CALCULATION
ITU-R recommendationITU-R recommendation
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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
LINK BUDGET CALCULATIONLINK BUDGET CALCULATION
ITU-R recommendationITU-R recommendation
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• 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
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ITU-R recommendationITU-R recommendation
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• Link budget parameters
• Link characteristics:
hop length, climate, profile ...
• Equipment characteristicstransmitted power, receiving thresholdconnection losses, antenna gain ...
LINK BUDGET CALCULATIONLINK BUDGET CALCULATION
ITU-R recommendationITU-R recommendation
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ContentsContents
FIELD TELECOMMUNICATION SURVEYFIELD TELECOMMUNICATION SURVEY
1) Introduction
- Survey definition
- Objectives / scope
- On site methodology
- On path methodology
* Los: Urban, long haul…
4) List of tools used during the survey
5) Data and survey report
- Site visit / On path data collection
- Survey report
6) Proprietary application software
- Azimuth
- Profile
- Pathloss
7) Link budget calculation
- ITU-R recommendation
- Link budget calculation
- North American (NA) and ITU-R Path Reliability (Outage) Calculations
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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
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Link budget calculationLink budget calculation
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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)
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Link budget calculationLink budget calculation
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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)
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Link budget calculationLink budget calculation
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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
LINK BUDGET CALCULATIONLINK BUDGET CALCULATION
Link budget calculationLink budget calculation
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ContentsContents
FIELD TELECOMMUNICATION SURVEYFIELD TELECOMMUNICATION SURVEY
1) Introduction
- Survey definition
- Objectives / scope
- On site methodology
- On path methodology
* Los: Urban, long haul…
2) List of tools used during the survey
3) 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 America (NA) and ITU-R Path Reliability (Outage) Calculations
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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.
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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
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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.
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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.
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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.
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Probability of Multipath OutageProbability of Multipath Outage
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
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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
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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
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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
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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
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Probability of Multipath OutageProbability of Multipath Outage
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:
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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”
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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.
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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
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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:
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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
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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:
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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):
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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:
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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:
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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)
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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.
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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
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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).
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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:
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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.
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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:
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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.
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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.
DIST XR=16.10DIST RY=16.10
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)
HUAWEI TECHNOLOGIES CO., LTD. Huawei Confidential
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.
DIST XR=50.00DIST RY=50.00
H<R>=1,150.ANT. DISC. :
X,DEG=0.250Y,DEG=0.250
FREQ=2.000 GHzF<N>=20.35
SD DISH SEP:SD<X>=45.8SD<Y>=45.8
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.
DIST XR=80.50DIST RY=80.50
H<R>=350.ANT. DISC. :
X,DEG=0.249Y,DEG=0.249
FREQ=2.000 GHzF<N>=20.36
SD DISH SEP:SD<X>=14.0SD<Y>=14.0
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.
HUAWEI TECHNOLOGIES CO., LTD. Huawei Confidential
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
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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
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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:
HUAWEI TECHNOLOGIES CO., LTD. Huawei Confidential
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
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