Microwave Radio Planning and Link Design             CISCOM Training Center             Microwave Planning and DesignSlide...
Microwave Radio Planning and Link Design             Microwave Radio Planning and Link Design   Course Contents   • PCM an...
Microwave Radio Planning and Link Design                 Microwave Radio Planning and Link Design    Course Contents (con’...
Microwave Radio Planning and Link Design                        Planning Objectives• MW Radio Planning Objectives       – ...
Microwave Radio Planning and Link Design             PCM and E1 OverviewSlide No 5
Microwave Radio Planning and Link Design             Voice channel digitizing and TDM• Transmission:       – Voice       –...
Microwave Radio Planning and Link Design              PCM Coder Block Diagram 64 kb/sAnalog                               ...
Microwave Radio Planning and Link Design                         E1 History• First use was for telephony (voice) in 1960’s...
Microwave Radio Planning and Link Design                                  E1 Frame•    30 time division multiplexed (TDM) ...
Microwave Radio Planning and Link Design                                          E1 frame diagram              Time Slot ...
Microwave Radio Planning and Link Design              E1 Transmission Media• Symmetrical pair: Balanced, 120 ohm• Co-axial...
Microwave Radio Planning and Link Design        GSM coding and TDM in terrestrial E1• As we know PCM channel is 64Kb/s• Bi...
Microwave Radio Planning and Link Design              Digital Multiplexing: PDH and SDH                           Overview...
Microwave Radio Planning and Link Design      European Digital Multiplexer Hierarchy• Plesiochronous Digital Hierarchy (PD...
Microwave Radio Planning and Link Design                   PDH Multiplexing• Based on a 2.048Mbit/s (E1) bearer• Increasin...
Microwave Radio Planning and Link Design        European PDH Multiplexing Structure                             Higher ord...
Microwave Radio Planning and Link Design European PDH Multiplexing Structure-used                                 1st orde...
Microwave Radio Planning and Link Design                   PDH Problems• Inflexible and expensive because of asynchronous ...
Microwave Radio Planning and Link Design                                 SDH•   Synchronous and based on byte interleaving...
Microwave Radio Planning and Link Design                 SDH Bit Rates                        STM-64      9.995328 Gbit/s ...
Microwave Radio Planning and Link Design              General Transport Module STM-N                           N. 270 colu...
Microwave Radio Planning and Link Design                   SDH Multiplexing Structure                                     ...
Microwave Radio Planning and Link Design                          From 2 Mbps to STM-1              (Justification)       ...
Microwave Radio Planning and Link Design                         Containers C                       Justification bits    ...
Microwave Radio Planning and Link Design                Virtual Containers VC                          Path overhead      ...
Microwave Radio Planning and Link Design                    SDH Advantages• Cost efficient and flexible networking• Built ...
Microwave Radio Planning and Link Design                     SDH Benefits over PDH•   SDH transmission systems have many b...
Microwave Radio Planning and Link Design              SDH Benefits over PDH- con’d       – Standardization                ...
Microwave Radio Planning and Link Design               GSM Block Diagram (E1 links)                          MSC1         ...
Microwave Radio Planning and Link Design                                  Abis- Interface                                 ...
Microwave Radio Planning and Link Design                              Abis- Interface      •       Traffic Information    ...
Microwave Radio Planning and Link Design          Digital Microwave systems OverviewSlide No 32
Microwave Radio Planning and Link Design                       Digital Microwave system•   Equipment       –      E1      ...
Microwave Radio Planning and Link Design                 MODEM- Digital Modulation• PSK       – 2 PSK       – 4 PSK       ...
Microwave Radio Planning and Link Design                      Protecting MW Links• Microwave links are protected against  ...
Microwave Radio Planning and Link Design           Microwave Equipment Specification• Operating Frequency• Modulation• Cap...
Microwave Radio Planning and Link Design              RADIO EQUIPT Example: DART                          Radio           ...
Microwave Radio Planning and Link DesignSlide No 38
Microwave Radio Planning and Link Design              Radio Equipment DatasheetSlide No 39
Microwave Radio Planning and Link Design   Microwave Allocation in Radio spectrum              VLF LF MF             HF VH...
Microwave Radio Planning and Link Design                   Microwave Bands• Some Frequency bands used in microwave are    ...
Microwave Radio Planning and Link Design                    Microwave Capacities• Capacities available for microwave links...
Microwave Radio Planning and Link Design                          23 GHz Band - example                         1232      ...
Microwave Radio Planning and Link Design                                   Channel Spacing              1.75 MHz          ...
Microwave Radio Planning and Link Design              International Regulatory Bodies• ITU-T        Is to fulfil the purpo...
Microwave Radio Planning and Link Design              Performance and availability objectivesSlide No 46
Microwave Radio Planning and Link Design    Performance Objectives and availability objectives• Dimensioning      of netwo...
Microwave Radio Planning and Link Design    ITU-T Recs for Transmission in GSM Net• All BTS, BSC and MSC connections in GS...
Microwave Radio Planning and Link Design                The ITU-T Recs (Standards)• The ITU-T target standard are based on...
Microwave Radio Planning and Link Design                  ITU-T G.821 some definitions•   HRX : hypothetical Reference Con...
Microwave Radio Planning and Link Design              ITU-T G.821 some definitions (con’d)•   SES : Severely Errored Secon...
Microwave Radio Planning and Link Design  ITU-T G.821 HRX Hypothetical Reference Connection                               ...
Microwave Radio Planning and Link Design                  ITU-T G.821 some definitions•   The system is considered unavail...
Microwave Radio Planning and Link Design        ITU-T G.821 performance & Availability                      Examples     B...
Microwave Radio Planning and Link Design                   ITU-T G.821 Availability• Route availability equals the sum of ...
Microwave Radio Planning and Link Design          ITU-T G.821 Performance Objectives•   SES : Severely Errored Seconds    ...
Microwave Radio Planning and Link Design  G.821 Performance Objectives over HRX  ITU-T; G.821, F.697, F.696               ...
Microwave Radio Planning and Link Design              P & A for HRPD – High Grade    1/10 of HRX                          ...
Microwave Radio Planning and Link Design              P & A for HRDS – Medium Grade       IT-T; G.821, F.696, Rep 1052    ...
Microwave Radio Planning and Link Design               P & A for HRX – Local Grade       – The local grade portion of the ...
Microwave Radio Planning and Link Design              Performance Predictions• System performance is determined by the pro...
Microwave Radio Planning and Link Design                          Availability•   The total unavailability of a radio path...
Microwave Radio Planning and Link Design                        HW Unavailability• Unavailability of one equipment module ...
Microwave Radio Planning and Link Design              Calculation of Unavailability• Unavailability of cascaded modules   ...
Microwave Radio Planning and Link Design               Calculation of Unavailability• Unavailability of parallel modules  ...
Microwave Radio Planning and Link DesignImprovement in Availability in n+1 protection • HW protection • Unavailability of ...
Microwave Radio Planning and Link DesignImprovement in Availability in Loop protection • HW and route protection • Unavail...
Microwave Radio Planning and Link Design                        HRDS - Example• HRDS: Medium grade class 3, 50 km. If the ...
Microwave Radio Planning and Link Design              Topology PlanningSlide No 69
Microwave Radio Planning and Link Design                 Capacity and Topology planning•   Capacity demand per link result...
Microwave Radio Planning and Link Design     Transmission Capacity Planning-Traffic             Motorola-standards• Bit ra...
Microwave Radio Planning and Link DesignTransmission Capacity Planning-Example• Example: How Many Motorola micro-cells can...
Microwave Radio Planning and Link Design                       Topology Planning• Network topology is based on       – Tra...
Microwave Radio Planning and Link Design                               Star  •Each station is connected with a separate li...
Microwave Radio Planning and Link Design                                               Star•   Advantages       –      Eas...
Microwave Radio Planning and Link Design                                        Daisy Chain               Application: alo...
Microwave Radio Planning and Link Design                   Daisy Chain• (grooming)Slide No 77
Microwave Radio Planning and Link Design                                         TreeApplication: Used for small or medium...
Microwave Radio Planning and Link Design                                         LoopBTSs are connected onto two way multi...
Microwave Radio Planning and Link Design                Topology Planning• Define clusters• Select reference node• Chose B...
Microwave Radio Planning and Link Design                     DiversitySlide No 81
Microwave Radio Planning and Link Design                                Diversity• Diversity is a method used if project p...
Microwave Radio Planning and Link Design                         DiversityDiversity Improvement• The degree of improvement...
Microwave Radio Planning and Link Design                   Diversity Improvement              10 –3                       ...
Microwave Radio Planning and Link Design                          Single Diversity• Space diversity       – Employs transm...
Microwave Radio Planning and Link Design                       Space Diversity                        Separate paths      ...
Microwave Radio Planning and Link Design                  Frequency diversity• The same signal is transmitted simultaneous...
Microwave Radio Planning and Link Design                  Frequency diversity It is not recommended for 1+1 systems, becau...
Microwave Radio Planning and Link Design              Hot standby configuration•   Tx and Rx operate at the same frequency...
Microwave Radio Planning and Link Design                    Hybrid diversity• Is an arrangement where 1+1 system has two a...
Microwave Radio Planning and Link Design                         Angle diversity•   Angle diversity techniques are based u...
Microwave Radio Planning and Link Design                 Combined diversity• In practical configuration a combination of s...
Microwave Radio Planning and Link Design                  Combined diversityCombined space and frequency diversity        ...
Microwave Radio Planning and Link Design                         Path Diversity•   Outage due to precipitation will not be...
Microwave Radio Planning and Link Design                                    Path Diversity•       The diversity gain (I.e....
Microwave Radio Planning and Link Design              Microwave AntennasSlide No 96
Microwave Radio Planning and Link Design                    Microwave Antennas• The most commonly used type is parabolic a...
Microwave Radio Planning and Link Design                               Antenna Gain•The gain of parabolic antenna referred...
Microwave Radio Planning and Link Design                     Antenna Gain-cont.• This figure shows the relationbetween the...
Microwave Radio Planning and Link Design                           VSWR• VSWR resembles Voltage Standing Wave Ratio• It is...
Microwave Radio Planning and Link Design               Side and Back lobe Levels• The important parameters in frequency pl...
Microwave Radio Planning and Link Design                             Beam Width• The half power beam width of antenna is d...
Microwave Radio Planning and Link Design     Antenna Characteristics – EIRP and ERP•   Effective Isotropic Radiated Power ...
Microwave Radio Planning and Link Design                         Passive Repeater• Two types of passive repeaters :       ...
Microwave Radio Planning and Link Design                    Passive Repeater- cont.• By using passive repeaters; the free ...
Microwave Radio Planning and Link Design                               Plane Reflectors•   More popular than back to back ...
Microwave Radio Planning and Link Design                Plane ReflectorsSlide No 107
Microwave Radio Planning and Link Design                     Back to back Repeater• Use of them is practical when reflecti...
Microwave Radio Planning and Link Design               Back to back antennasSlide No 109
Microwave Radio Planning and Link Design         Antenna Characteristics - Polarization• Co-Polarization       – The trans...
Microwave Radio Planning and Link Design                             Cross Polarization•   Transmission of two separate tr...
Microwave Radio Planning and Link Design                                Cross Polarization• To ensure interference-free op...
Microwave Radio Planning and Link Design                 Mechanical Stability• Limitations in sway / twist   for the struc...
Microwave Radio Planning and Link Design   Antenna  DatasheetSlide No 114
Microwave Radio Planning and Link DesignDigital AntennapatternSlide No 115
Microwave Radio Planning and Link Design                Antenna PatternSlide No 116
Microwave Radio Planning and Link Design               Radio PropagationSlide No 117
Microwave Radio Planning and Link Design                  Electromagnetic (EM) Waves•   EM wave is a wave produced by the ...
Microwave Radio Planning and Link Design               Electromagnetic Waves Properties• E and H vectors are orthogonal• I...
Microwave Radio Planning and Link Design                    Radio Wave Propagation• The propagation of radio wave is affec...
Microwave Radio Planning and Link Design                         Frequency Effect• Attenuation: Loss• Propagation of radio...
Microwave Radio Planning and Link Design                           Terrain effect• Reflection and scattering• The radio wa...
Microwave Radio Planning and Link Design                       Atmospheric effect• Loss and refraction• The gaseous consti...
Microwave Radio Planning and Link Design                    Multipath effect• Multipath effect occurs when many signals wi...
Microwave Radio Planning and Link Design               EM wave Reflection and scattering• When electromagnetic waves incid...
Microwave Radio Planning and Link Design                 EM wave Reflections• Reflection of the radio beam from lakes and ...
Microwave Radio Planning and Link Design               EM wave Reflection coefficient (ρ)• Reflection can be characterized...
Microwave Radio Planning and Link Design         EM wave Reflection coefficient-cont. • The resulting electromagnetic fiel...
Microwave Radio Planning and Link Design                   EM wave Refraction• Refraction occurs because radio waves trave...
Microwave Radio Planning and Link Design                      EM wave Refraction• Radio wave is refracted toward the regio...
Microwave Radio Planning and Link Design                       EM wave Refraction• Refractivity depends on       – Pressur...
Microwave Radio Planning and Link Design               EM wave Refraction and Ray bending• Refraction cause ray bending in...
Microwave Radio Planning and Link Design               EM wave Refraction: K-Factor• K is a value to indicate wave bending...
Microwave Radio Planning and Link Design         K-Factor and Path Profile Correction• Path profile must be corrected by K...
Microwave Radio Planning and Link Design   Formation Of Ducts- Refraction and reflectionGround Based Duct: Refraction and ...
Microwave Radio Planning and Link Design   Formation Of Ducts- Refraction and reflection               Elevated DUCT      ...
Microwave Radio Planning and Link Design               Formation Of Ducts- Explanation                     Refraction and ...
Microwave Radio Planning and Link Design    Ducting Probability- Refraction and reflection• Duct probability percentage of...
Microwave Radio Planning and Link DesignITU-R DUCT Probability CONTOUR MAPSSlide No 139
Microwave Radio Planning and Link DesignMultipath Propagation - Refraction and reflection• Multipath propagation occurs wh...
Microwave Radio Planning and Link Design                        Diffraction• Diffraction occurs and causes increase in tra...
Microwave Radio Planning and Link Design                             Diffraction lossPractical methods are used to estimat...
Microwave Radio Planning and Link Design                        Knife edge models• Knife edge approximation is used when t...
Microwave Radio Planning and Link Design                                   Absorption•     At frequency above 10      GHz ...
Microwave Radio Planning and Link Design                   Rain Attenuation• When radio waves interact with raindrops the ...
Microwave Radio Planning and Link Design                    Rain Attenuation• Rain rate is measured to estimate attenuatio...
Microwave Radio Planning and Link Design                    Raindrop shape• As the raindrops increase in size, they depart...
Microwave Radio Planning and Link Design                           Fading• The radio waves undergo variations while travel...
Microwave Radio Planning and Link Design                            Fade Margins• Fade Margin is extra power• Fade Margins...
Microwave Radio Planning and Link Design                     Mutipath Fading• As the fading margin increased the probabili...
Microwave Radio Planning and Link Design                          Mutipath Fading• The impacts of multipath fading can be ...
Microwave Radio Planning and Link Design                      Mutipath Fading               P                   Flat fadin...
Microwave Radio Planning and Link Design        Microwave Link Planning and DesignSlide No 153
Microwave Radio Planning and Link Design                        Hop Calculations (Design)                  Predictable    ...
Microwave Radio Planning and Link Design                              Path Profile• Path profile is essentially a plot of ...
Microwave Radio Planning and Link Design                 Path Profile Example• Path profiles are necessary to determine si...
Microwave Radio Planning and Link Design               Path Profile: Clearance of Path• Design objective: Full clearance o...
Microwave Radio Planning and Link Design           Path Profile: Fresnel Zone ExampleSlide No 158
Microwave Radio Planning and Link Design                           Fresnel Zone• Fresnal Zone is defined as the zone shape...
Microwave Radio Planning and Link Design                            Fresnel Zone Equation•   First Fresnel zone radius    ...
Microwave Radio Planning and Link Design               Fresnel Zone Radii calculations                                  “T...
Microwave Radio Planning and Link DesignObstacle Loss: Fresnel Zone is not Cleared                                    Obst...
Microwave Radio Planning and Link Design               Knife Edge Losses               0        0      6      12    20 dBS...
Microwave Radio Planning and Link Design               Smooth Spherical Earth Losses                                      ...
Microwave Radio Planning and Link Design                      Line-Of-Sight Survey                                  LOS• L...
Microwave Radio Planning and Link Design               Line-Of-Sight Survey- Flowchart                               Netwo...
Microwave Radio Planning and Link Design               LOS Survey EquipmentNecessary:                          Optional:• ...
Microwave Radio Planning and Link Design         LOS Survey Procedure - Preparation• Preparation       – Maps of 1:50k sca...
Microwave Radio Planning and Link Design               LOS Survey Procedure - Field• Verification of sites positions and a...
Microwave Radio Planning and Link Design               Other Methods of LOS Survey• Mirrors• Flash• Balloon• Portable MW E...
Microwave Radio Planning and Link Design                       LOS Survey Report• Site Data       – Name       – Coordinat...
Microwave Radio Planning and Link Design                           Link Budget•   Includes all gains and losses as the sig...
Microwave Radio Planning and Link Design                             Link Budget• Link budget is the sum of all losses and...
Microwave Radio Planning and Link Design                          Link Budget (con’d)               Pin = Pout − ∑ L + ∑ G...
Microwave Radio Planning and Link Design                                  Link Budget                      Gt             ...
Microwave Radio Planning and Link Design Link Budget Parameters-Free Space Loss•   It is defined as the loss incurred by a...
Microwave Radio Planning and Link Design               Link Budget Parameters                         Free Space Loss     ...
Microwave Radio Planning and Link Design                    Link Budget Parameters• Total Antenna Gain:                   ...
Microwave Radio Planning and Link Design                        Link Budget Parameters• Rx Level: Signal strength at the r...
Microwave Radio Planning and Link Design                                        Fading• Fading types       – Multipath Fad...
Microwave Radio Planning and Link Design               Fade Margin and Availability•   Is the difference between the nomin...
Microwave Radio Planning and Link Design                 Flat Fading ITU-R P.530-7                                    Pfla...
Microwave Radio Planning and Link Design               Flat Fading- cont. ITU-R P.530-7•   The geoclimatic (K) depends on ...
Microwave Radio Planning and Link DesignFrequency Selective Fading ITU-R F.1093• Result from surface reflections or introd...
Microwave Radio Planning and Link Design  Frequency Selective Fading ITU-R F.1093                                       3...
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  • PCM and E1
  • PCM and E1
  • PCM and E1
  • PCM and E1
  • PCM and E1
  • PCM and E1
  • PCM and E1
  • Digital Multiplexing: PDH and SDH
  • Digital Multiplexing: PDH and SDH
  • Digital Multiplexing: PDH and SDH
  • Digital Multiplexing: PDH and SDH
  • Digital Multiplexing: PDH and SDH
  • Digital Multiplexing: PDH and SDH
  • Digital Multiplexing: PDH and SDH
  • Digital Multiplexing: PDH and SDH
  • Digital Multiplexing: PDH and SDH
  • Digital Multiplexing: PDH and SDH
  • Digital Multiplexing: PDH and SDH
  • Digital Multiplexing: PDH and SDH
  • Digital Multiplexing: PDH and SDH
  • Digital Multiplexing: PDH and SDH
  • Digital Multiplexing: PDH and SDH
  • Digital Multiplexing: PDH and SDH
  • Digital Multiplexing: PDH and SDH
  • Digital Multiplexing: PDH and SDH
  • Digital Microwave systems Overview
  • Digital Microwave systems Overview
  • Digital Microwave systems Overview
  • Digital Microwave systems Overview
  • Digital Microwave systems Overview
  • Digital Microwave systems Overview
  • Digital Microwave systems Overview
  • Digital Microwave systems Overview
  • Digital Microwave systems Overview
  • Digital Microwave systems Overview
  • Digital Microwave systems Overview
  • Digital Microwave systems Overview
  • Digital Microwave systems Overview
  • Performance and availability objectives
  • Performance and availability objectives
  • Performance and availability objectives
  • Performance and availability objectives
  • Performance and availability objectives
  • Performance and availability objectives
  • Performance and availability objectives
  • Performance and availability objectives
  • Performance and availability objectives
  • Performance and availability objectives
  • Performance and availability objectives
  • Performance and availability objectives
  • Performance and availability objectives
  • Performance and availability objectives
  • Performance and availability objectives
  • Performance and availability objectives
  • Performance and availability objectives
  • Performance and availability objectives
  • Performance and availability objectives
  • Performance and availability objectives
  • Performance and availability objectives
  • Performance and availability objectives
  • Topology Planning
  • Topology Planning
  • Topology Planning
  • Topology Planning
  • Topology Planning
  • Topology Planning
  • Topology Planning
  • Topology Planning
  • Topology Planning
  • Topology Planning
  • Topology Planning
  • Diversity
  • Diversity
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  • Diversity
  • Diversity
  • Diversity
  • Diversity
  • Diversity
  • Diversity
  • Diversity
  • Diversity
  • Diversity
  • Diversity
  • Microwave Antennas
  • Microwave Antennas
  • Microwave Antennas
  • Microwave Antennas
  • Microwave Antennas
  • Microwave Antennas
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  • Microwave Antennas
  • Microwave Antennas
  • Microwave Antennas
  • Microwave Antennas
  • Microwave Antennas
  • Radio Propagation
  • Radio Propagation
  • Radio Propagation
  • Radio Propagation
  • Radio Propagation
  • Radio Propagation
  • Radio Propagation
  • Radio Propagation
  • Radio Propagation
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  • Radio Propagation
  • Radio Propagation
  • Radio Propagation
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  • Radio Propagation
  • Radio Propagation
  • Radio Propagation
  • Microwave Link Planning and Design
  • Microwave Link Planning and Design
  • Microwave Link Planning and Design
  • Microwave Link Planning and Design
  • Microwave Link Planning and Design
  • Microwave Link Planning and Design
  • Microwave Link Planning and Design
  • Microwave Link Planning and Design
  • Microwave Link Planning and Design
  • Microwave Link Planning and Design
  • Microwave Link Planning and Design
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  • Microwave Link Planning and Design
  • Microwave Link Planning and Design
  • Microwave Link Planning and Design
  • Microwave Link Planning and Design
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  • Microwave Link Planning and Design
  • Microwave Link Planning and Design
  • Microwave Link Planning and Design
  • Microwave Link Planning and Design
  • Microwave Link Planning and Design
  • Microwave Link Planning and Design
  • Microwave Link Planning and Design
  • Microwave Link Planning and Design
  • Microwave Link Planning and Design
  • Microwave Link Planning and Design
  • Microwave Link Planning and Design
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  • Microwave Link Planning and Design
  • Microwave Link Planning and Design
  • Microwave Link Planning and Design
  • Microwave Link Planning and Design
  • Microwave Link Planning and Design
  • Microwave Link Planning and Design
  • Microwave Link Planning and Design
  • Frequency Planning
  • Frequency Planning
  • Frequency Planning
  • Frequency Planning
  • Frequency Planning
  • Frequency Planning
  • Frequency Planning
  • Frequency Planning
  • Frequency Planning
  • Frequency Planning
  • Frequency Planning
  • Frequency Planning
  • Frequency Planning
  • Frequency Planning
  • Frequency Planning
  • Frequency Planning
  • Frequency Planning
  • Frequency Planning
  • Frequency Planning
  • Frequency Planning
  • 52528672 microwave-planning-and-design

    1. 1. Microwave Radio Planning and Link Design CISCOM Training Center Microwave Planning and DesignSlide No 1
    2. 2. Microwave Radio Planning and Link Design Microwave Radio Planning and Link Design Course Contents • PCM and E1 TDM Overview • Digital Multiplexing: PDH and SDH Overview • Digital Microwave Systems Overview • Microwave links Performance and Quality Objectives • Topology and Capacity Planning • Diversity • Microwave AntennasSlide No 2
    3. 3. Microwave Radio Planning and Link Design Microwave Radio Planning and Link Design Course Contents (con’d) • Radio Propagation • Microwave Link Planning and Design – Path Profile – LOS Survey – Link Budget – Performance Prediction • Frequency Planning • Interference • Digital map and tools overviewSlide No 3
    4. 4. Microwave Radio Planning and Link Design Planning Objectives• MW Radio Planning Objectives – Selection of suitable radio component – Communication quality and availability – Link Design – Preliminary site location and path profile, LOS survey – Channel capacity – Topology – Radio frequency allocation (planning)Slide No 4
    5. 5. Microwave Radio Planning and Link Design PCM and E1 OverviewSlide No 5
    6. 6. Microwave Radio Planning and Link Design Voice channel digitizing and TDM• Transmission: – Voice – Data• Voice is an analog signal and needs to be digitized before transmitted digitally• PCM, Pulse Code Modulation is the most used technique• The European implementation of PCM includes time division multiplexing of 30 64 kb/s voice channels and 2 64kb/s for synchronization and signaling in basic digital channel called E1• E1 rate is 2.048 Mb/s = 32 x 64 kb/sSlide No 6
    7. 7. Microwave Radio Planning and Link Design PCM Coder Block Diagram 64 kb/sAnalog 64 kb/ssignal LPF LPF S/H S/H Quantizer Quantizer Encoder Encoder PCM signal Slide No 7
    8. 8. Microwave Radio Planning and Link Design E1 History• First use was for telephony (voice) in 1960’s with PCM and TDM of 30 digital PCM voice channels which called E1• E1 is known as PCM-30 also• E1 was developed slightly after T1 (1.55 Mbps) was developed in America (hence T1 is slower)• T1 is the North America implementation of PCM and TDM• T1 is PCM-24 systemSlide No 8
    9. 9. Microwave Radio Planning and Link Design E1 Frame• 30 time division multiplexed (TDM) voice channels, each running at 64Kbps (known as E1)• E1 rate is 2.048 Mbps containing thirty two 64 kbps time slots, – 30 for voice, – One for Signaling (TS16) – One for Frame Synchronization (TS0)• E1 (2M) Frame rate is the same PCM sampling rate = 8kHz, Frame duration is 1/8 kHz = 125 μs (Every 125 us a new frame is sent)• Time slot Duration is 125 μs/32 = 3.9 μs• One time slot contains 8 bits• A timeslot can be thought of as a link running at 8000 X 8 = 64 kbps• E1 Rate: 64 X 32 = 2048000 bits/secondSlide No 9
    10. 10. Microwave Radio Planning and Link Design E1 frame diagram Time Slot Time Slot Time Slot ………… Time Slot …………. Time Slot Time Slot Time Slot 0 1 2 ………… 16 ………… 29 30 31 125µs Bits 1 2 3 4 5 6 7 8 Frame containing frame alignment Si 0 0 1 1 0 1 1 signal (FAS) Frame not containing frame alignment Si 1 A Sn Sn Sn Sn Sn signal Frame Alignment Signal (FAS) pattern - 0011011 Si = Reserved for international use (Bit 1) Sn = Reserved for national use A = Remote (FAS Distant) Alarm- set to 1 to indicate alarm conditionSlide No 10
    11. 11. Microwave Radio Planning and Link Design E1 Transmission Media• Symmetrical pair: Balanced, 120 ohm• Co-axial: Unbalanced, 75ohm• Fiber optic• Microwave• Satellite• Other wireless radio• Wireless OpticalSlide No 11
    12. 12. Microwave Radio Planning and Link Design GSM coding and TDM in terrestrial E1• As we know PCM channel is 64Kb/s• Bit rate for one voice GSM channel is 16Kb/s between BTS and BSC (terrestrial)• One GSM E1 is 120 GSM voice channels• The PCM-to-GSM TRAU (transcoder) reduces no of E1’s by 4• Each GSM radio carries 8 TCHs in the air, this equivalent to 8x16Kb/s=2x64Kb/s between BTS and BSC.• Each GSM radio has 2 time slots in the GSM E1.• Example: 3/3/3 site require 9x2=18 E1 time slots for traffic and time slot(s) for radio signaling linksSlide No 12
    13. 13. Microwave Radio Planning and Link Design Digital Multiplexing: PDH and SDH OverviewSlide No 13
    14. 14. Microwave Radio Planning and Link Design European Digital Multiplexer Hierarchy• Plesiochronous Digital Hierarchy (PDH)• Synchronous Digital Hierarchy (SDH )Slide No 14
    15. 15. Microwave Radio Planning and Link Design PDH Multiplexing• Based on a 2.048Mbit/s (E1) bearer• Increasing traffic demands that more and more of these basic E1 bearers be multiplexed together to provide increased capacity• Once multiplexed, there is no simple way an individual E1 bearer can be identified in a PDH hierarchySlide No 15
    16. 16. Microwave Radio Planning and Link Design European PDH Multiplexing Structure Higher order multiplexing 4 x 34 16 x E1 4 x E1 139,264 kbps 1 1 E1 34,368 kbps 8448 kbps 30 2048 kbpsSlide No 16
    17. 17. Microwave Radio Planning and Link Design European PDH Multiplexing Structure-used 1st order 2nd order 2.048 Mbps 8.228 Mbps E1 E2 MUX 3rd order DEMUX 34.368 Mbps Primary PCM E3 VF Multiplexing MUX DEMUX Data MUX Data Multiplexing DEMUX MUX DEMUX BTS mobile Multiplexing MUX DEMUXSlide No 17
    18. 18. Microwave Radio Planning and Link Design PDH Problems• Inflexible and expensive because of asynchronous multiplexing• Limited network management and maintenance support capabilities• High capacity growth• Sensitive to network failure• Difficulty in verifying network status• Increased cost for O&MSlide No 18
    19. 19. Microwave Radio Planning and Link Design SDH• Synchronous and based on byte interleaving• provides the capability to send data at multi-gigabit rates over fiber-optics links.• SDH is based on an STM-1 (155.52Mbit/s) rate• SDH supports the transmission of all PDH payloads, other than 8Mbit/sSlide No 19
    20. 20. Microwave Radio Planning and Link Design SDH Bit Rates STM-64 9.995328 Gbit/s 4 STM-16 2.48832 Gbit/s 4 STM-4 622.08 Mbit/s 4 STM-1 155.52 Mbit/s 3 STM-0 51.84 Mbit/sSlide No 20
    21. 21. Microwave Radio Planning and Link Design General Transport Module STM-N N. 270 columns N. 9 N. 261 1 SOH: Section Overhead 3 RSOH AU: Administration Unit AU pointer MSOH: Multiplexer Section 5 Payload Overhead RSOH: Repeater Section MSOH Overhead 9Slide No 21
    22. 22. Microwave Radio Planning and Link Design SDH Multiplexing Structure 140 Mbps VC-4 C-4 TU-3 34 Mbps x 3 TUG-3 x1 VC-3 C-3 2 Mbps x7 TUG-2 TU-12 VC-12 C-12 x3 C: Container AU-4 AUG STM-N VC: Virtual Container x1 xN TU: Tributary Unit Mapping TUG: Tributary Container Group Aligning AU: Administrative Unit Multiplexing AUG: Administrative Unit GroupSlide No 22
    23. 23. Microwave Radio Planning and Link Design From 2 Mbps to STM-1 (Justification) 2 Mbits VC-12 VC-4 STM-1 + POH SDH + POH + SOH MUX SOH: Section Overhead POH: Path OverheadSlide No 23
    24. 24. Microwave Radio Planning and Link Design Containers C Justification bits = Container PDH StreamSlide No 24
    25. 25. Microwave Radio Planning and Link Design Virtual Containers VC Path overhead = Virtual Container ContainerSlide No 25
    26. 26. Microwave Radio Planning and Link Design SDH Advantages• Cost efficient and flexible networking• Built in capacity for advanced network management and maintenance capabilities• Simplified multiplexing and demultiplexing• Low rate tributes visible within the high speed signal. Enables direct access to these signals• Cost efficient allocation of bandwidth• Fault isolation and Management• Byte interleaved and multiplexedSlide No 26
    27. 27. Microwave Radio Planning and Link Design SDH Benefits over PDH• SDH transmission systems have many benefits over PDH: – Software Control allows extensive use of intelligent network management software for high flexibility, fast and easy re-configurability, and efficient network management. – Survivability With SDH, ring networks become practicable and their use enables automatic reconfiguration and traffic rerouting when a link is damaged. End-to-end monitoring will allow full management and maintenance of the whole network. – Efficient drop and insert SDH allows simple and efficient cross-connect without full hierarchical multiplexing or de-multiplexing. A single E1 2.048Mbit/s tail can be dropped or inserted with relative ease even on Gbit/s links.Slide No 27
    28. 28. Microwave Radio Planning and Link Design SDH Benefits over PDH- con’d – Standardization enables the interconnection of equipment from different suppliers through support of common digital and optical standards and interfaces. – Robustness and resilience of installed networks is increased. – Equipment size and operating costs reduced by removing the need for banks of multiplexers and de- multiplexers. Follow-on maintenance costs are also reduced. – Backwards compatibly will enable SDH links to support PDH traffic.Slide No 28
    29. 29. Microwave Radio Planning and Link Design GSM Block Diagram (E1 links) MSC1 BTS SDH MSC2 BTS MSC3 BSC1 PDH Abis BTS BTS BTS BSC2 BTS BTS BTSSlide No 29
    30. 30. Microwave Radio Planning and Link Design Abis- Interface BSC Abis-Interface BTS • Connects between the BSC and the BTS • Has not been standardized • Primary functions carried over this interface are: Traffic channel transmission, terrestrial channel management, and radio channel management • On Abis-Interface, two types of information Traffic information Signalling informationSlide No 30
    31. 31. Microwave Radio Planning and Link Design Abis- Interface • Traffic Information – The traffic on the physical layer needs ¼ TS (Time Slot) on the E1 with bit rate = 16 Kb/s – 4 channels exist within one TS • Signalling Information – Different rates on the physical layer: 16 Kb/s, 32 Kb/s, and 64 Kb/s – The protocol used over the Abis-Interface is LAPD protocol (Link Access Protocol for the ISDN D-channel) – The signalling link between the BSC and the BTS is called RSL (Radio Signalling Link)Slide No 31
    32. 32. Microwave Radio Planning and Link Design Digital Microwave systems OverviewSlide No 32
    33. 33. Microwave Radio Planning and Link Design Digital Microwave system• Equipment – E1 – MUX – IF MODEM – Transceiver In door Out door TRU – Feeder For In door Co-axial transmission line Waveguide transmission line For Outdoor IF between modem ODU Transceiver (TRU)Slide No 33
    34. 34. Microwave Radio Planning and Link Design MODEM- Digital Modulation• PSK – 2 PSK – 4 PSK – 8 PSK• QAM – 8 QAM – 16 QAM – 32 QAM – 64 QAM – 128 QAMSlide No 34
    35. 35. Microwave Radio Planning and Link Design Protecting MW Links• Microwave links are protected against – Hardware failure – Multipath Fading – Rain Fading• Protection Schemes – 1 + 1 configuration – Diversity – RingSlide No 35
    36. 36. Microwave Radio Planning and Link Design Microwave Equipment Specification• Operating Frequency• Modulation• Capacity• Bandwidth• Output power• Receiver Thresholds @ BER’s 10-6 and 10-3• MTBF• FKTBSlide No 36
    37. 37. Microwave Radio Planning and Link Design RADIO EQUIPT Example: DART Radio Equipment Antenna dish Dish diameter: 30 cmSlide No 37
    38. 38. Microwave Radio Planning and Link DesignSlide No 38
    39. 39. Microwave Radio Planning and Link Design Radio Equipment DatasheetSlide No 39
    40. 40. Microwave Radio Planning and Link Design Microwave Allocation in Radio spectrum VLF LF MF HF VHF UHF SHF EHF 3k 30 k 300 k 3M 30 M 300 M 3G 30 G 300 G VHF Very low frequency • Microwave primarily is LF Low frequency utilized in SHF band, and MF Medium frequency some small parts of UHF & HF High Frequency EHF bands VHF Very High Frequency UHF Ultra High Frequency SHF Super High Frequency EHF Extremely High FrequencySlide No 40
    41. 41. Microwave Radio Planning and Link Design Microwave Bands• Some Frequency bands used in microwave are – 2 GHz – 7 GHz – 13 GHz – 18 GHz – 23 GHz – 26 GHz – 38 GHz• The usage of frequency bands will depend mainly on the budget calculation results and the path lengthSlide No 41
    42. 42. Microwave Radio Planning and Link Design Microwave Capacities• Capacities available for microwave links are – 1 x 2 Mbps with a bandwidth of 1.75 MHz – 2 x 2 Mbps with a bandwidth of 3.5 MHz – 4 x 2 Mbps with a bandwidth of 7 MHz – 8 x 2 Mbps with a bandwidth of 14 MHz – 16 x 2 Mbps with a bandwidth of 28 MHzSlide No 42
    43. 43. Microwave Radio Planning and Link Design 23 GHz Band - example 1232 1120 1120 21224 22456 22456 23576 Low High Possible Number of Channels 2 x 2 (3.5 MHz) 4 x 2 (7 MHz) 8 x 2 (14 MHz) 16 x 2 (28 MHz) 320 160 80 40Slide No 43
    44. 44. Microwave Radio Planning and Link Design Channel Spacing 1.75 MHz 3.5 MHz 2 E1 3.5 MHz 7 MHz 4 E1 7 MHz 14 MHz 8 E1 14 MHz 28 MHz 16 E1Slide No 44
    45. 45. Microwave Radio Planning and Link Design International Regulatory Bodies• ITU-T Is to fulfil the purposes of the Union relating to telecommunication standardization by studying technical, operating and tariff questions and adopting Recommendations on them with a view to standardizing telecommunications on a world-wide basis.• ITU-R plays a vital role in the management of the radio-frequency spectrum and satellite orbits, finite natural resources which are increasingly in demand from a large number of services such as fixed, mobile, broadcasting, amateur, space research, meteorology, global positioning systems, environmental monitoring and, last but not least, those communication services that ensure safety of life at sea and in the skies.Slide No 45
    46. 46. Microwave Radio Planning and Link Design Performance and availability objectivesSlide No 46
    47. 47. Microwave Radio Planning and Link Design Performance Objectives and availability objectives• Dimensioning of network connection is based on the required availability objective and performance• Dimension a network must meet the standard requirements recommendations by ITU• The performance objectives are separated from availability objectives• Factors to be considered – radio wave propagation – hardware failure – Resetting time after repair – Frequency dependant interference problemsSlide No 47
    48. 48. Microwave Radio Planning and Link Design ITU-T Recs for Transmission in GSM Net• All BTS, BSC and MSC connections in GSM network are defined as multiples of the primary rate if 2 Mbps,• ITU-T Rec G.821 applies as the overall standard for GSM network.• ITU-T Rec G.826 applies for SDH.Slide No 48
    49. 49. Microwave Radio Planning and Link Design The ITU-T Recs (Standards)• The ITU-T target standard are based on two recommendations: – ITU-T Recommendation G.821,intended for digital connection with a bit rate of 64 kBit/s. Even used for digital connection with bit rates higher than 64kBit/s. G.821 will successively be replaced by G.826. – ITU- T Recommendation G.826, used for digital connection with bit rates of or higher than 2,048 kBit/s (European standard) or 1,544 kBit/s (USA standard).• The main difference between G.826 and G.821 is that G.826 uses Blocks instead of bits in G.821Slide No 49
    50. 50. Microwave Radio Planning and Link Design ITU-T G.821 some definitions• HRX : hypothetical Reference Connection – This a model for long international connection, 27,500 km – Includes transmission systems, multiplexing equipment and switching• HRDP: Hypothetical Reference Digital Path – The HRDP for high grade digital relay systems is 2500 km – Doesn’t include switching• HRDS: Hypothetical Reference Digital Section – It represents section lengths likely to be encountered in real networks – Doesnt include digital equipments, such as multiplexers/demultiplexers.Slide No 50
    51. 51. Microwave Radio Planning and Link Design ITU-T G.821 some definitions (con’d)• SES : Severely Errored Seconds – A bit error rate (BER) of 10-3 is measured with an integration time of 1 second.• DM : Degraded Minutes – A bit error rate (BER) of 10-6 is measured with an integration time of 1 minute.• ES : Errored Seconds – Is the second that contains at least one error• RBER: Residual Bit Error Rate – The RBER on a system is found by taking BER measurements for one month using a 15 min integration time, discarding the 50 % of 15 min intervals which contain the worst BER measurements, and taking the worst of the remaining measurementsSlide No 51
    52. 52. Microwave Radio Planning and Link Design ITU-T G.821 HRX Hypothetical Reference Connection 27,500 km 1250 km 25,000 km 1250 kmT-reference T-reference point point LE INT INT LE 15 % 15 % 40 % 15 % 15 % Local Medium Local High Medium Grade Grade Grade Grade GradeSlide No 52
    53. 53. Microwave Radio Planning and Link Design ITU-T G.821 some definitions• The system is considered unavailable when one or both of the following conditions occur for more than 10 consecutive seconds – The digital signal is interrupted – The BER in each second is worse than 10 –3• Unavailable Time (UAT) – Begins when one or both of the above mentioned conditions occur for 10 consecutive seconds• Available Time (AT) – A period of available time begins with the first second of a period of 10 consecutive seconds of which each second has a bit error ratio (BER) better than 10-3Slide No 53
    54. 54. Microwave Radio Planning and Link Design ITU-T G.821 performance & Availability Examples BER 10-6 BER 10-3 <10s >10s DM SES DM DM SES DM ES ES ES ES ES Available time (AT) Unavailable time (UAT)Slide No 54
    55. 55. Microwave Radio Planning and Link Design ITU-T G.821 Availability• Route availability equals the sum of single link availabilities forming the route.• Unavailability might be due to – Propagation effect – Equipment effectNote: Commonly used division is to allocate 2/3 of the allowed total unavailability to equipment failure and 1/3 to propagation related unavailabilitySlide No 55
    56. 56. Microwave Radio Planning and Link Design ITU-T G.821 Performance Objectives• SES : Severely Errored Seconds – BER should not exceed 10–3 for more than 0.2% of one second intervals in any month – The total allocation of 0.2% is divided as: 0.1% for the three classifications – The remaining 0.1% is a block allowance to the high grade and the medium grade portions• DM : Degraded Minutes – BER should not exceed 10–6 for more than 10% of one minute intervals in any month – The allocations of the 10% to the three classes• ES : Errored Seconds – Less than 8% of one second intervals should have errors – The allocations of the 8% to the three classesSlide No 56
    57. 57. Microwave Radio Planning and Link Design G.821 Performance Objectives over HRX ITU-T; G.821, F.697, F.696 1250 km 25000 km 1250 km Local Medium High Medium Local SES 0.2% (0.1% +0.1% for High and 0.015 0.015 0.04 0.015 0.015 Medium grade for 0.05 0.05 adverse conditions 1.5 1.5 4 1.5 1.5 DM 10 % 1.2 1.2 3.2 1.2 1.2 ES 8 % INT LESlide No 57
    58. 58. Microwave Radio Planning and Link Design P & A for HRPD – High Grade 1/10 of HRX ITU-T; G.821, Rep 1052 2500 High Grade 0054 % SES (0.004+0.05) (Additional 0.05% for adverse propagation conditions) 0.4 % DM ES 0.32 % 0.3 % UAT Note: between 280 to 2500 all parameters are multiplied by (L/2500)Slide No 58
    59. 59. Microwave Radio Planning and Link Design P & A for HRDS – Medium Grade IT-T; G.821, F.696, Rep 1052 – Used for national networks, between local exchange and international switching center Performance and availability Objectives for HRDS Performance parameter Percentage of any month Class 1 Class 2 Class 3 Class 4 280 km 280 km 50 km 50 km SES 0.006 0.0075 0.002 0.005 DM 10 % 0.045 0.2 0.2 0.5 Errored Seconds ES 8 % 0.036 0.16 0.16 0.4 RBER 5.6x10-10 Under Under Under study study study UAT 0.033 0.05 0.05 0.1Slide No 59
    60. 60. Microwave Radio Planning and Link Design P & A for HRX – Local Grade – The local grade portion of the HRX represents the part between the subscriber and the local exchange – Error performance objectives are: BER shouldn’t exceed 10–3 for more than 0.015% of any month with an integration time of 1 s BER shouldn’t exceed 10-6 for more than 1.5% of any month with an integration time of 1 min The total errored seconds shouldn’t exceed 1.2% of any month – Unavailability objectives for local grade circuits have not yet been established by ITU-T or ITU-R.Slide No 60
    61. 61. Microwave Radio Planning and Link Design Performance Predictions• System performance is determined by the probability for the signal level to drop below the radio threshold level or the received spectrum to be severely distorted• The larger fade margin, the smaller probability for the signal to drop below the receiver threshold levelSlide No 61
    62. 62. Microwave Radio Planning and Link Design Availability• The total unavailability of a radio path is the sum of the probability of hardware failure and unavailability due to rain• The unavailability due to hardware failure is considered for both the go and return direction so the calculated value is doubled• The probability that electronic equipment fails in service is not constant with time• the high probability of hardware failure occurred during burn-in and wear-out periods• During life time the random failures have constant probabilitySlide No 62
    63. 63. Microwave Radio Planning and Link Design HW Unavailability• Unavailability of one equipment module – HW MTTR N1 = MTBF + MTTR where MTTR is mean time to repair MTBF is mean time between failures.Slide No 63
    64. 64. Microwave Radio Planning and Link Design Calculation of Unavailability• Unavailability of cascaded modules N1 N1 N2 N2 N3 N3 Nn Nn n  n  n N s = 1 − As = 1 − Π (1 − N i ) ≈ 1 − 1 − Σ Ni  = Σ N i i =1  i =1  i =1Slide No 64
    65. 65. Microwave Radio Planning and Link Design Calculation of Unavailability• Unavailability of parallel modules N1 N1 N2 N2 n N s = Π Ni i =1 N3 N3 Nn NnSlide No 65
    66. 66. Microwave Radio Planning and Link DesignImprovement in Availability in n+1 protection • HW protection • Unavailability of a n+1 redundant system N n +1 = 1  ( n + 1)  N 2 (1 − N ) ( n +1) −2  2! ( ( n + 1) − 2 )!  n   n +1 2 Can be approximated N n +1 = N 2Slide No 66
    67. 67. Microwave Radio Planning and Link DesignImprovement in Availability in Loop protection • HW and route protection • Unavailability in a loop N=(N1+N2)(N3+N4+N5+N6+N7) N3 N2  k  J  N =  ∑ N i  ∑ N i  N1  i =1  i = k +1  N4 N7 N5 N6 Where, – J: Amount of hops in loop – K: Consecutive number of hop from the hub – N: Unavailability of the hop Slide No 67
    68. 68. Microwave Radio Planning and Link Design HRDS - Example• HRDS: Medium grade class 3, 50 km. If the link is 5km find UAT in % & s/d N• Solution: – From table of HRDS, Medium grade class 3, 50 km >>UAT = 0.05% – For 5 km >> UAT = (0.05%) * 5/50 = 0.005% – UAT = (0.005/100) * 365.25*24= 0.438h/y = 26min/y = 4s/dSlide No 68
    69. 69. Microwave Radio Planning and Link Design Topology PlanningSlide No 69
    70. 70. Microwave Radio Planning and Link Design Capacity and Topology planning• Capacity demand per link results from transceiver capacity at those BTS which are to be connected to the microwave link• One transceiver reserves 2.5 time slots for traffic and signalling• It is common to design for the higher capacity demand.• For rapid traffic increase, the transmission network is dimensioned to reserve the capacity of 6 transceivers• The advantage to reserve capacity – Flexibility in topology planning – New BTS s can be added to existing transmission links – New transceivers can be added without implementing new transmission links – No need for changeover to new transmission links in fully operating networkSlide No 70
    71. 71. Microwave Radio Planning and Link Design Transmission Capacity Planning-Traffic Motorola-standards• Bit rate for one voice PCM channel is 64Kb/s• Bit rate for one voice GSM channel is 16Kb/s between BTS and BSC• Each GSM radio carries 8 TCHs in the air, this equivalent to 8x16Kb/s=2x64Kb/s between BTS and BSC.• Each GSM radio has 2 time slots in the GSM E1.• Example: 3/3/3 site require 9x2=18 E1 time slots for traffic and one time slot for RSL, total is 19 time slotsSlide No 71
    72. 72. Microwave Radio Planning and Link DesignTransmission Capacity Planning-Example• Example: How Many Motorola micro-cells can be daisy chained using one E1 at maximum?• Solution: – Motorola micro cell has 2 radios (omni-2) – Each micrcell requires 2x2 time slots for traffic and 1 time slot for rsl – So each micro cell requires 5 time slots (64 kb/s time slots) – Each E1 contains 31 time slots – [31time slots] divided by [5 time slots/microcell] gives us the the maximum no of daisy chained microcells – So 6 microcells can be daisy chained at maximumSlide No 72
    73. 73. Microwave Radio Planning and Link Design Topology Planning• Network topology is based on – Traffic – Outage requirements• Most frequently used topologies – Star – Daisy Chain – LoopSlide No 73
    74. 74. Microwave Radio Planning and Link Design Star •Each station is connected with a separate link to the MW hub. •Commonly used for leased line connections (needs low availability)Slide No 74
    75. 75. Microwave Radio Planning and Link Design Star• Advantages – Easy to design – Independent paths which mean link failure affects only one node – Easy to configure and install – Can be expanded easily• Disadvantages – Limited distance from BTS or hub to the BSC – Inefficient use of frequency band – Inefficient link capacity use as each BTS uses the 2 Mbps – High concentration of equipment at nodal point – Interference problemSlide No 75
    76. 76. Microwave Radio Planning and Link Design Daisy Chain Application: along roads • Advantages – Efficient use of link capacity (if BTSs are chained to the same 2Mbps) – Low concentration of equipment at nodal point • Disadvantages – Installation planning is essential as the BTSs close – If the first link is lost, the traffic of the whole BTS chain is lost – extended bandwidth (grooming)Slide No 76
    77. 77. Microwave Radio Planning and Link Design Daisy Chain• (grooming)Slide No 77
    78. 78. Microwave Radio Planning and Link Design TreeApplication: Used for small or medium size network• Advantages – Efficient equipment utilization by grooming – Short paths which require smaller antenna – Frequency reuse• Disadvantages – Availability , one link failure affect many sitesSlide No 78 – Expansions might require upgrading or rearrangement
    79. 79. Microwave Radio Planning and Link Design LoopBTSs are connected onto two way multidrop chain• Advantages – Provide the most reliable means of transmission protection against microwave link fading and equipment failure – Flexibility y providing longer hops with the same antenna size, or alternatively, smaller antenna dishes with the same hop length• Disadvantages – Installation planning; since all BTSs of a loop must be in place for loop protection – More difficult to design and add capacity – Skilled maintenance personnel is required to make cofiguration changes in theSlide No 79 loop
    80. 80. Microwave Radio Planning and Link Design Topology Planning• Define clusters• Select reference node• Chose Backbone• Decide the topologySlide No 80
    81. 81. Microwave Radio Planning and Link Design DiversitySlide No 81
    82. 82. Microwave Radio Planning and Link Design Diversity• Diversity is a method used if project path is severely influenced by fading due to multi path propagation• The common protection of diversity techniques are: – Space Diversity – Frequency Diversity – Combination of frequency and space Diversity – Angle Diversity Note: frequency diversity technique takes advantage because of the frequency selectivity nature of the multi path depressive fading.Slide No 82
    83. 83. Microwave Radio Planning and Link Design DiversityDiversity Improvement• The degree of improvement afforded by all of diversity techniques on the extents to witch the signals in the diversity branches of the system are uncorrelated.• The improvement of diversity relative to a single channel given by: PSinglechannel Improvement factor I = where P refers to BER PDiversitySlide No 83
    84. 84. Microwave Radio Planning and Link Design Diversity Improvement 10 –3 No diversity 10 -4 10 -5 diversity Diversity 10 -6 improvement factor 10 -7 20 30 40 Fade DepthSlide No 84
    85. 85. Microwave Radio Planning and Link Design Single Diversity• Space diversity – Employs transmit antenna and two receiver antenna – The two receivers enables the reception of signals via different propagation paths – It requires double antenna on each side of the hop, a unit for the selection of the best signal and partially or fully duplicated receivers Note: whenever space diversity is used, angle diversity should also be employed by tilting the antenna at different upwards anglesSlide No 85
    86. 86. Microwave Radio Planning and Link Design Space Diversity Separate paths Tx 1 Rx 1 S Rx 1Slide No 86
    87. 87. Microwave Radio Planning and Link Design Frequency diversity• The same signal is transmitted simultaneously on two different frequencies• One antenna is required on either side of the hops, a unit selecting the best signal and duplicate transmitters and receivers• A cost-effective technique• Provides equipment protection , also gives protection from multipath fadingSlide No 87
    88. 88. Microwave Radio Planning and Link Design Frequency diversity It is not recommended for 1+1 systems, because 50% of thespectrum is utilized For redundant N+1 systems this technique is efficient, because thespectrum efficiency is better, but the improvement factor will bereduced since there are more channel sharing the same diversitychannel 1+1 systemsSlide No 88
    89. 89. Microwave Radio Planning and Link Design Hot standby configuration• Tx and Rx operate at the same frequency, so there is no frequency diversity could be expected• This configuration gives no improvement of system performance, but reduces the system outage due to equipment failures• Used to give equipment diversity (protection) on paths where propagation conditions are non-critical to system performanceSlide No 89
    90. 90. Microwave Radio Planning and Link Design Hybrid diversity• Is an arrangement where 1+1 system has two antennas at one of the radio sites• This system effect act as space diversity system, and diversity improvement factor can be calculated as for space diversitySlide No 90
    91. 91. Microwave Radio Planning and Link Design Angle diversity• Angle diversity techniques are based upon differing angles of arrival of radio signal at a receiving antenna, when the signals are a result of Multipath propagation• The angle diversity technique involves a receiving antenna with its vertical pattern tilted purposely off the bore sight lines• Angle diversity can be used is situations in witch adequate space diversity is not possible or to reduce tower heightSlide No 91
    92. 92. Microwave Radio Planning and Link Design Combined diversity• In practical configuration a combination of space and frequency diversity is used• Different combination algorithms exist• The simple method (conservative) to calculate the improvement factor for combined diversity configuration I = Isd + IsdSlide No 92
    93. 93. Microwave Radio Planning and Link Design Combined diversityCombined space and frequency diversity TX RX f1 f2 TX RX f1 S f2 RX RXSlide No 93
    94. 94. Microwave Radio Planning and Link Design Path Diversity• Outage due to precipitation will not be reduced by use of frequency,angle or space diversity.• Rain attenuation is mainly a limiting factor at frequencies above ~10 GHz• Systems operating at these high frequencies are used in urban areas where the radio relay network may from a mix of star and mesh configurations• The area covered by an intense shower is normally much smaller than the coverage of the entire network• Re-Routing the signal via other pathsSlide No 94
    95. 95. Microwave Radio Planning and Link Design Path Diversity• The diversity gain (I.e. the difference between the attenuation (dB) exceeded for a specific percentage of time on single link and that simultaneously on two parallel links – Tends to decrease as the path length increases from 12 km or a given percentage of time, and for a given lateral path separation – Is generally greater for a spacing of 8 km than for 4 km, though an increase to 12 km dose not provide further improvement – Is not significantly dependent on frequency in the range 20 – 40 GHz, for a given geometry, and - Ranges from about 2.8 dB at 0.1% of the time to 0.4 dB at 0.001% of the time, for a spacing of 8 km, and path lengths of about the same value for a 4 km spacing are about 1.8 to 2.0 dB.Slide No 95
    96. 96. Microwave Radio Planning and Link Design Microwave AntennasSlide No 96
    97. 97. Microwave Radio Planning and Link Design Microwave Antennas• The most commonly used type is parabolic antenna• The performance of microwave system depends on the antenna parameters• Antenna parameters are: – Gain – Voltage Standing Wave Ratio (VSWR) – Side and back lobe levels – Beam width – Discrimination of cross polarization – Mechanical stabilitySlide No 97
    98. 98. Microwave Radio Planning and Link Design Antenna Gain•The gain of parabolic antenna referred to an isotropic radiator is given by: 4π Gain ≈ 10 log(η × A × 2 ) λ where: η= aperture efficiency (typical values : 0.5-0.6) λ = wavelength in meters – A = aperture area in m2Note : the previous formula valid only in the far field of the antenna, the gain will be decreased in the near field, near field antenna gain is obtained from manufacturerSlide No 98
    99. 99. Microwave Radio Planning and Link Design Antenna Gain-cont.• This figure shows the relationbetween the gain of microwave dishand frequency with different dishdiameters• Can be approximated Gain = 17.8 + 20log (d.f) dBi where, d : Dish diameter (m) f : Frequency in GHzSlide No 99
    100. 100. Microwave Radio Planning and Link Design VSWR• VSWR resembles Voltage Standing Wave Ratio• It is important in the case of high capacity systems with stringent linearity objectives• VSWR should be minimum in order to avoid intermodulation interference• Typical values of VSWR are from 1.06 to 1.15• High performance antennas have VSWR from 1.04 to 1.06Slide No 100
    101. 101. Microwave Radio Planning and Link Design Side and Back lobe Levels• The important parameters in frequency planning and interference calculations are sidelobe and backlobes• Low levels of side and backlobes make the use of frequency spectrum more efficient• The levels of side and backlobes are specified in the radiation envelope patterns• The front to back ratio gives an indication of backlobe levels• The front to back ratio increases with increasing of frequency and antenna diameterSlide No 101
    102. 102. Microwave Radio Planning and Link Design Beam Width• The half power beam width of antenna is defined as the angular width of the main beam at –3dB point – An approximate formula used to find the beam width is: α3dB = ± 35. λ/D in degrees – The 10dB deflection angle is found approximately by: α10dB = 60. λ/D in degreesSlide No 102
    103. 103. Microwave Radio Planning and Link Design Antenna Characteristics – EIRP and ERP• Effective Isotropic Radiated Power (EIRP) – It is equal to the product of the power supplied to a transmitting antenna and the antenna gain in a given direction relative to an isotropic radiator (expressed in watts) – EIRP = Power - Feeder Loss + Antenna Gain Both EIRP and Power expressed in dBW Antenna gain expressed in dBi• Effective Radiated Power (ERP) – The same as EIRP but is relative to a half-wave dipole instead of an isotropic radiator• EIRP = ERP + 2.14 dB• Example Transmitter Output Power = 4 Watts = 36 dBm, Transmission Line Loss = 2 dB, and Antenna Gain = 10 dBd. Calculate the ERP – Answer: ERP = 36 - 2 + 10 = 44 dBmdSlide No 103
    104. 104. Microwave Radio Planning and Link Design Passive Repeater• Two types of passive repeaters : – Plane reflectors – Back to Back antennas• The plane reflector reflects MW signals as the mirror reflects light – The laws of reflection are valid here• The back to back antennas work just like an ordinary repeater station, but without frequency transportation or amplification of the signalSlide No 104
    105. 105. Microwave Radio Planning and Link Design Passive Repeater- cont.• By using passive repeaters; the free space loss becomes: AL= AFSA – GR + AFSBwhere – AFSA is the free space loss for the path site A to passive repeater – AFSB is the free space loss for the path site B to passive repeater – GR is the gain of the passive repeaterSlide No 105
    106. 106. Microwave Radio Planning and Link Design Plane Reflectors• More popular than back to back antennas due to : – Efficiency is around 100% – Can be produced with much larger dimensions than parabolic antennas• The gain of plane reflectors is given by: GR= 20 log( 139.5 . f2 .AR . cos( Ψ/2 )) in dBwhere : – AR is the physical reflector area in m2 – F is the radio frequency in GHz Ψ is the angle in space at the passive repeater in degreesSlide No 106
    107. 107. Microwave Radio Planning and Link Design Plane ReflectorsSlide No 107
    108. 108. Microwave Radio Planning and Link Design Back to back Repeater• Use of them is practical when reflection angle is large• The Gain of back to back antennas is given by GR= GA1 – AC + GA2 in dBwhere : – GA1: is the gain of one of the two antennas at the repeater in dB – GA2: is the gain of the other antenna at the repeater in dB – AC : is the coupling loss between antennas in dBSlide No 108
    109. 109. Microwave Radio Planning and Link Design Back to back antennasSlide No 109
    110. 110. Microwave Radio Planning and Link Design Antenna Characteristics - Polarization• Co-Polarization – The transmit and receive antennas have the same polarization – Either horizontal or vertical (HH or VV)• Cross-Polarization – The transmit and receive antennas have different polarization – Either HV or VHSlide No 110
    111. 111. Microwave Radio Planning and Link Design Cross Polarization• Transmission of two separate traffic channels is performed on the same radio frequency but on orthogonal polarization• The polarization planes are horizontal and vertical• The discrimination between the two polarization is called Cross Polar Discrimination (XPD)• Cross-Polarization Discrimination (XPD) – the ratio between the power received in the orthogonal (cross polar) port to the power received at the co-polar port when the antenna is excited with a wave polarized as in the co-polar antenna element• Good cross polarization allows full utilization of the frequency bandSlide No 111
    112. 112. Microwave Radio Planning and Link Design Cross Polarization• To ensure interference-free operation, the nominal value of XPD the value is usually in the rang 30 – 40 dB• Discrimination of cross polar signals is an important parameter in frequency planning Vertical Horizontal 1 2 3 4 5 6 7 8 1’ 2’ 3’ 4’ 5’ 6’ 7’ 8’ 28 MHzSlide No 112
    113. 113. Microwave Radio Planning and Link Design Mechanical Stability• Limitations in sway / twist for the structure of the structure (tower or mast) correspond to a maximum 10 dB signal attenuation due to antenna misalignment• The maximum deflection angle may be estimated for a given antenna diameter and frequency by using α 10dB = 60. λ/D in degreesSlide No 113
    114. 114. Microwave Radio Planning and Link Design Antenna DatasheetSlide No 114
    115. 115. Microwave Radio Planning and Link DesignDigital AntennapatternSlide No 115
    116. 116. Microwave Radio Planning and Link Design Antenna PatternSlide No 116
    117. 117. Microwave Radio Planning and Link Design Radio PropagationSlide No 117
    118. 118. Microwave Radio Planning and Link Design Electromagnetic (EM) Waves• EM wave is a wave produced by the interaction of time varying electric and magnetic field• Electromagnetic fields are typically generated by alternating current (AC) in electrical conductors• The EM field composes of two fields (vectors) – Electric vector E – Magnetic vector H• Electromagnetic waves can be – Reflected and scattered – Refracted – Diffracted – Absorbed (its energy)Slide No 118
    119. 119. Microwave Radio Planning and Link Design Electromagnetic Waves Properties• E and H vectors are orthogonal• In free space environment, the EM-wave propagates at the speed of light (c)• The distance between the wave crests is called the wavelength (λ)• The frequency ( f )is the number of times the wave oscillates• The relation that combines the EM-wave frequency and wavelength with the speed of light is: λ=c/fSlide No 119
    120. 120. Microwave Radio Planning and Link Design Radio Wave Propagation• The propagation of radio wave is affected by : – Frequency Effect – Terrain Effect – Atmospheric Effect – Multipath EffectAll the above mentioned effects cause a degradation in qualitySlide No 120
    121. 121. Microwave Radio Planning and Link Design Frequency Effect• Attenuation: Loss• Propagation of radio depends on frequency band• At frequencies above 6 GHz radio wave is more affected by gas absorption and precipitation – At frequencies close to 10 GHz the effects of precipitation begins to dominate – Gas absorption starts influencing at 22 GHz where the water vapour shows characteristic peakSlide No 121
    122. 122. Microwave Radio Planning and Link Design Terrain effect• Reflection and scattering• The radio wave propagating near the surface of earth is influenced by: – Electrical characteristics of earth – Topography of terrain including man-made structuresSlide No 122
    123. 123. Microwave Radio Planning and Link Design Atmospheric effect• Loss and refraction• The gaseous constituents and temperature of the atmosphere influence radio waves by: – Absorbing its energy – Variations in refractive index which cause the radio wave reflect, refract and scatterSlide No 123
    124. 124. Microwave Radio Planning and Link Design Multipath effect• Multipath effect occurs when many signals with different amplitude and/or phase reach the receiver• Multipath effect is caused by reflection and refraction• Multipath propagation cause fadingSlide No 124
    125. 125. Microwave Radio Planning and Link Design EM wave Reflection and scattering• When electromagnetic waves incide on a surface it might be reflected or scattered• Rayleigh criterion used to determine whether the wave will be scattered or reflected• The reflected waves depend on the frequency, incidence angle and electrical property of the surfaceSlide No 125
    126. 126. Microwave Radio Planning and Link Design EM wave Reflections• Reflection of the radio beam from lakes and large surfaces are more critical than reflection from terrain with vegetation• Generally, vertical polarization gives reduced reflection especially at lower frequencies• If there is a great risk from reflection ,space diversity should be usedSlide No 126
    127. 127. Microwave Radio Planning and Link Design EM wave Reflection coefficient (ρ)• Reflection can be characterized by its total reflection coefficient ρ• ρ is the quotient between the reflected and incident field• When ρ = 0 nothing will be reflected and when ρ =1 we have specular reflection• reflection coefficient decreases with frequencySlide No 127
    128. 128. Microwave Radio Planning and Link Design EM wave Reflection coefficient-cont. • The resulting electromagnetic field at a receiver antenna is composed of two components,the direct signal and the reflected signal • Since the angle between the both components varies between 0 and 180 the signal will pass through maximum and minimum values respectively Reflection loss (ρ) The figure shows different 5 Amax values of total reflection -5 -15 Amin coefficient, and the minimum -15 and maximum values -25 with respect to them -35 0.2 0.4 0.6 0.8 Total reflection coefficient (ρ)Slide No 128
    129. 129. Microwave Radio Planning and Link Design EM wave Refraction• Refraction occurs because radio waves travel with different velocities in different medium according to their electrical characteristics.• Index of refraction of a medium is the ratio of the velocity of radio waves in space to the velocity of radio waves in that mediumSlide No 129
    130. 130. Microwave Radio Planning and Link Design EM wave Refraction• Radio wave is refracted toward the region with higher index of refraction (denser medium) Incident wave n2 > n1 Reflected wave Medium 1 ,n1 θi θr Medium 2 ,n2 Refracted waveSlide No 130
    131. 131. Microwave Radio Planning and Link Design EM wave Refraction• Refractivity depends on – Pressure – Temperature – Humidity• Refractive Gradient (dN/dh) represents refractive variation with respect to height (h), related to the earth radius.Slide No 131
    132. 132. Microwave Radio Planning and Link Design EM wave Refraction and Ray bending• Refraction cause ray bending in the atmosphere• In free space, the radio wave follows straight line no atmosphere with atmosphereSlide No 132
    133. 133. Microwave Radio Planning and Link Design EM wave Refraction: K-Factor• K is a value to indicate wave bending a K= e r re :is the effective radius of the ray due to refraction a :is the earth radius = 6350 km – For temperate regions : dN/dh = - 40N units per Km, K=4/3=1.33Slide No 133
    134. 134. Microwave Radio Planning and Link Design K-Factor and Path Profile Correction• Path profile must be corrected by K-factor• Radius of earth must be multiplied by K-factor, less curvature of earthSlide No 134
    135. 135. Microwave Radio Planning and Link Design Formation Of Ducts- Refraction and reflectionGround Based Duct: Refraction and reflection• The atmosphere has very dense layer at the ground with a thin layer on top of it.Elevated Duct: Refraction only• The atmosphere has a thick layer in some height above ground.• If both the transmitter and the receiver are within the duct, multiple rays will reach the receiver• If one is inside and the other is outside the duct, nearly no energy will reach the receiverSlide No 135
    136. 136. Microwave Radio Planning and Link Design Formation Of Ducts- Refraction and reflection Elevated DUCT Ground Based DUCT Earth EarthSlide No 136
    137. 137. Microwave Radio Planning and Link Design Formation Of Ducts- Explanation Refraction and reflectionSlide No 137
    138. 138. Microwave Radio Planning and Link Design Ducting Probability- Refraction and reflection• Duct probability percentage of time when dN/dh is less than –100 N units/km per specified month• ITU-R issues DUCT Probability CONTOUR MAPS• The ducting probability follows seasonal variations• This difference in ducting probability can be explained by the difference in temperature and most of all by difference in humidity• From the map the equatorial regions are most vulnerable to ductsSlide No 138
    139. 139. Microwave Radio Planning and Link DesignITU-R DUCT Probability CONTOUR MAPSSlide No 139
    140. 140. Microwave Radio Planning and Link DesignMultipath Propagation - Refraction and reflection• Multipath propagation occurs when there are more than one ray reach the receiver • Disadvantages: – Signal strength changes rapidly over a short time and distance – Multipath delays which causes time dispersion – Random frequency modulation due to Doppler shifts – Delay spread of the received signal • Multipath transmission is the main cause of fading • Fading is explained in later slidesSlide No 140
    141. 141. Microwave Radio Planning and Link Design Diffraction• Diffraction occurs and causes increase in transmission loss when the size of obstacle between transmitter and receiver is large compared to wavelength• Diffraction effects are faster and more accentuated with increased obstruction for frequencies above 1 GHz• Transmission obstruction loss over irregular terrain is complicated function of frequency, path geometry, vegetation density and other less significant variable• Practical methods are used to estimate the obstruction losses.Slide No 141
    142. 142. Microwave Radio Planning and Link Design Diffraction lossPractical methods are used to estimate the obstruction losses• Terrain Averaging: ITU-R P.530-7 – Diffraction loss in this method can be approximated for losses greater than 15 dB Ad = -20h/F1 + 10 (dB) : ITU-R P.530-7 Where, Ad : diffraction loss. h: height difference between most significant blockage and path trajectory. F1: radius of first freznal zoneSlide No 142
    143. 143. Microwave Radio Planning and Link Design Knife edge models• Knife edge approximation is used when the obstruction is sharp and inside the first freznal zone – Single Knife edge – Bullington – Epostein-Peterson – Japanese AtlasSlide No 143
    144. 144. Microwave Radio Planning and Link Design Absorption• At frequency above 10 GHz the propagation of radio waves through the atmosphere of the earth is strongly effected by resonant absorption of electromagnetic energy by molecular water vapor and oxygen Slide No 144
    145. 145. Microwave Radio Planning and Link Design Rain Attenuation• When radio waves interact with raindrops the electromagnetic wave will scatter• The attenuation depends on frequency band, specially for frequencies above 10 GHz• The rain attenuation calculated by introducing reduction factor and then effective path length• The rain attenuation depends on the rain rate, which obtained from long term measurement and very short integration time• The Earth is divided into 16 different rain zonesSlide No 145
    146. 146. Microwave Radio Planning and Link Design Rain Attenuation• Rain rate is measured to estimate attenuation because it is hard to actually count the number of raindrops and measure their individual sizes so• Rainfall is measured in millimeters [mm], and rain intensity in millimeters pr. hour [mm/h].• Since the radio waves are a time varying electromagnetic field, the incident field will induce a dipole moment in the raindrop will therefore act as an antenna and re-radiate the energy.• A raindrop is an antenna with low directivity and some energy will be re-radiated in arbitrary directions giving a net loss of energy in the direction towards the receiver.Slide No 146
    147. 147. Microwave Radio Planning and Link Design Raindrop shape• As the raindrops increase in size, they depart from the spherical shape• Raindrops are more extended in the horizontal direction and consequently will attenuate horizontal polarized waves more than the vertical polarized.• This means that vertical polarizationis favorable at high frequencieswhere outage due to rain is dominant.Slide No 147
    148. 148. Microwave Radio Planning and Link Design Fading• The radio waves undergo variations while traveling in the atmosphere due to atmospheric changes. The received signal fades around nominal value.• Multipath Fading is due to metrological conditions in the space separating the transmitter and the receiver which cause detrimental effects to the received signalSlide No 148
    149. 149. Microwave Radio Planning and Link Design Fade Margins• Fade Margin is extra power• Fade Margins will be explained in link design for the following:• Multipath Fading – Flat Fading – Selective Fading• Rain FadingSlide No 149
    150. 150. Microwave Radio Planning and Link Design Mutipath Fading• As the fading margin increased the probability of the signal to drop below the receiver threshold is decreased• Flat fading or non-selective occurs when all components of the useful signal are affected equally• Frequency selective fading occurs if some of the spectral components are reduced causing distortion• Total fading Ptot =Pflat + PselSlide No 150
    151. 151. Microwave Radio Planning and Link Design Mutipath Fading• The impacts of multipath fading can be summarized as follows: – It reduces the signal-to-noise ratio and consequently increases the bit-error-rate (BER) – It reduces the carrier-to-interference (C/I) ratio and consequently increases the BER – It distorts the digital pulse waveform resulting in increased intersymbol interference and BER – It introduces crosstalk between the two orthogonal carriers, the I-rail and the Q-rail, and consequently increases the BERSlide No 151
    152. 152. Microwave Radio Planning and Link Design Mutipath Fading P Flat fading Normal signal Frequency selective fadingSlide No 152
    153. 153. Microwave Radio Planning and Link Design Microwave Link Planning and DesignSlide No 153
    154. 154. Microwave Radio Planning and Link Design Hop Calculations (Design) Predictable Statistically Predictable Free Space Loss Gas Absorption Rain fading Multipath fading Obstacle Loss Always present and predictable Not always present Predictable but statistically if present predictable Link Budget Fading prediction Performance & Availability ObjectivesSlide No 154
    155. 155. Microwave Radio Planning and Link Design Path Profile• Path profile is essentially a plot of the elevation of the earth as function of the distance along the path between the transmitter and receiver• The purpose of path profile: – To check the free line of sight – To check the clearance of the path to avoid obstacle attenuation – When determining the fading of received signalSlide No 155
    156. 156. Microwave Radio Planning and Link Design Path Profile Example• Path profiles are necessary to determine site locations and antenna heightsSlide No 156
    157. 157. Microwave Radio Planning and Link Design Path Profile: Clearance of Path• Design objective: Full clearance of direct line-of-sight and and an ellipsoid zone surrounding the direct line-of-sight• The ellipsoid zone is called the Fresnel ZoneSlide No 157
    158. 158. Microwave Radio Planning and Link Design Path Profile: Fresnel Zone ExampleSlide No 158
    159. 159. Microwave Radio Planning and Link Design Fresnel Zone• Fresnal Zone is defined as the zone shaped as ellipsoid with its focal point at the antennas on both ends of the path• If there is no obstacle within first Fresnel zone ,the obstacle attenuation can be ignored and the path is cleared• Equation of path of ellipsoid λ d1 + d 2 − d = 2Slide No 159
    160. 160. Microwave Radio Planning and Link Design Fresnel Zone Equation• First Fresnel zone radius d1 × d 2 F1 = 17.3 × [m] d× f• Fresnel zone – Exercise: Calculate the fresnel zone radius at mid path for the following cases – 1. f= 15GHz, K=4/3, d=10km – 2. f = 15GHz, K=4/3, d=20km• Solution: = 17.3 × 5×5 = 7m – 1. F1 (radius) 15 × 10 10 × 10 = 17.3 × = 10m – 2. F1 (radius) 15 × 20Slide No 160
    161. 161. Microwave Radio Planning and Link Design Fresnel Zone Radii calculations “Table Tool”Frequency Distance in kmGHz 4.0 10.0 15.0 20.0 30.0 40.07.0 9.2 12.7 13.3 15.0 17.3 18.613.0 10.3 13.6 12.1 13.6 13.8 14.215.0 10.1 14.2 11.3 13.4 12.4 13.118.0 9.2 15.2 10.6 13.8 11.6 13.023.0 7.7 17.1 9.6 14.7 10.9 13.426.0 6.7 19.6 8.6 16.0 10.1 14.138.0 5.1 23.9 7.3 18.1 9.1 15.2Slide No 161
    162. 162. Microwave Radio Planning and Link DesignObstacle Loss: Fresnel Zone is not Cleared Obstacle Loss Knife Edge obstacle loss Smooth spherical obstacle lossSlide No 162
    163. 163. Microwave Radio Planning and Link Design Knife Edge Losses 0 0 6 12 20 dBSlide No 163
    164. 164. Microwave Radio Planning and Link Design Smooth Spherical Earth Losses 30 20 10 dBSlide No 164
    165. 165. Microwave Radio Planning and Link Design Line-Of-Sight Survey LOS• LOS Survey – To verify that the proposed network design is feasible considering LOS constraintsSlide No 165
    166. 166. Microwave Radio Planning and Link Design Line-Of-Sight Survey- Flowchart Network Design Update the design LOS Survey LOS ReportSlide No 166
    167. 167. Microwave Radio Planning and Link Design LOS Survey EquipmentNecessary: Optional:• Compass • Clinometer• Maps : 50 k or better • Altimeter• Digital Camera • Laptop• GPS Navigator • Spectrum analyzer• Binoculars • Antenna horn• Hand-held communication • Low noise amplifier equipment• Signaling mirrors • TheodoliteSlide No 167
    168. 168. Microwave Radio Planning and Link Design LOS Survey Procedure - Preparation• Preparation – Maps of 1:50k scale or better to be used and prepared – List of hops to be surveyed – Critical obstacles should be marked in order to verify LOS in the field – Organize transport and accommodation – Organize access and authorization to the sites – Prepare LOS survey formSlide No 168
    169. 169. Microwave Radio Planning and Link Design LOS Survey Procedure - Field• Verification of sites positions and altitudes• Confirmation of line-of-sight using – GPS – Compass – Binocular – And other methods in the next slide• Take photographs• Estimate required tower heights• Path and propagation notesSlide No 169
    170. 170. Microwave Radio Planning and Link Design Other Methods of LOS Survey• Mirrors• Flash• Balloon• Portable MW Equipment• Driving along the path and taking GPS and altitude measurements for different points along it.Slide No 170
    171. 171. Microwave Radio Planning and Link Design LOS Survey Report• Site Data – Name – Coordinates – Height – Address• Proposed Tower Height• LOS Confirmation• Azimuth and Elevation• Path short description• PhotographsSlide No 171
    172. 172. Microwave Radio Planning and Link Design Link Budget• Includes all gains and losses as the signal passes from transmitter to the receiver.• It is used to calculate fade margin which is used to estimate the performance of radio link system.Slide No 172
    173. 173. Microwave Radio Planning and Link Design Link Budget• Link budget is the sum of all losses and gains of the signal between the transmitter output and the receiver input.• Items related to the link budget – Transmitted power – Received power – Feeder loss – Antenna gain – Free space loss – Attenuations• Used to calculate received signal level (fading is ignored)Slide No 173
    174. 174. Microwave Radio Planning and Link Design Link Budget (con’d) Pin = Pout − ∑ L + ∑ G − FSL − A Where, Pin = Received power (dBm) Pout = Transmitted power (dBm) L = Antenna feeder loss (dB) G = Antenna gain (dBi) FSL = Free space loss (dB) (between isotropic antennas) A = Attenuations (dB)Slide No 174
    175. 175. Microwave Radio Planning and Link Design Link Budget Gt Gr Tx Rx Output Antenna power gain Free space loss + atmospheric atten. Feeder Branching Received loss loss Feeder power Antenna loss Branching gain loss Fade Margin Receiver thresholdSlide No 175
    176. 176. Microwave Radio Planning and Link Design Link Budget Parameters-Free Space Loss• It is defined as the loss incurred by an electromagnetic wave as is propagates in a straight line through the vacuum  4π  D 2  4π  fD 2 where, Lp =  =  Lp = free space path loss  λ   c  D = distance f = frequency λ = wavelength c = velocity of light in free space (3*108 m/s) Lp(dB) = 92.4 + 20logf(GHz) + 20logD(km)Slide No 176
    177. 177. Microwave Radio Planning and Link Design Link Budget Parameters Free Space Loss Lp Tx RxSlide No 177
    178. 178. Microwave Radio Planning and Link Design Link Budget Parameters• Total Antenna Gain: f Da Ga = 20 log (Da) + 20 log (f) + 17.8• Atmospheric attenuation occurs at higher frequencies , above 15 GHz due a = γ a × d Ato atmospheric gases, and given by: Where d is path link in km , γa is specific attenuation in dB/kmSlide No 178
    179. 179. Microwave Radio Planning and Link Design Link Budget Parameters• Rx Level: Signal strength at the receiving antenna PRx= PTx-LBRL-+GTx-LFS-Lobs+GRx - LTx feeder – LRx feeder Where, PRx : received power level GTx :Tx gain PTx : transmitted power level Lobs :Diffraction loss LBRL : branching loss GRx :Rx gain LFS : free space loss LRx feeder : Rx feeder loss LTx feeder : Tx feeder lossSlide No 179
    180. 180. Microwave Radio Planning and Link Design Fading• Fading types – Multipath Fading; Dominant cause of fading for f < 10 GHz • Flat Fading • Frequency Selective Fading – Rain Fading; Dominant cause of fading for f > 10 GHzSlide No 180
    181. 181. Microwave Radio Planning and Link Design Fade Margin and Availability• Is the difference between the nominal input level and receiver threshold level From Link Budget FM = Received Power – Receiver threshold• Fade margin is designed into the system so as to meet outage objectives during fading conditions• Typical value of Fade Margin is around 40 dB• Availability is calculated from the Fade Margin value as in F.1093, P.530-6, P.530-7, …Slide No 181
    182. 182. Microwave Radio Planning and Link Design Flat Fading ITU-R P.530-7 Pflat =Po . 10–F/10where: – F equals the fade margin – Po the fading occurrence factor Po = k. d3.6 . f0.89 .(1+|Ep|)-1.4Where: – k is geoclimatic factor – d is path length in Km – f is frequency in GHz h − h2 EP = 1 – Ep: path inclination in mrad = dSlide No 182
    183. 183. Microwave Radio Planning and Link Design Flat Fading- cont. ITU-R P.530-7• The geoclimatic (K) depends on type of the path – Inland links Plains: low altitude 0 to 400m above mean sea level Hills: low altitude 0 to 400m above mean sea level Plains: Medium altitude 400 to 700m above mean sea level Hills: Medium altitude 400 to 700m above mean sea level Plains: High altitude more than 700m above mean sea level Hills: High altitude more than 700m above mean sea level Mountains: High altitude more than 700m above mean sea level – Coastal links over/near large bodies of water – Coastal links over/near medium-sized bodies of water – Indistinct path definition• To calculate K value, refer to formulas and tables in ITU-R P.530-7Slide No 183
    184. 184. Microwave Radio Planning and Link DesignFrequency Selective Fading ITU-R F.1093• Result from surface reflections or introduced by atmospheric anomalies such as strong ducting gradients B 2 − τm Psel = 4.3 × 10 20 ×η × W × τr Where, η : Probability of of the occurrence of multipath fading W: Signature width (GHz), equipment dependent B : Signature depth (GHz), equipment dependent τm: Mean value of echo delay τr : Time delay used during measurements of the signature curves (reference delay) ns. Normally 6.3 nsSlide No 184
    185. 185. Microwave Radio Planning and Link Design Frequency Selective Fading ITU-R F.1093  3/ 4   −.2× P0       100   η = 1− e   Where, Po: The fading occurrence factor 1.5 d  τ m = 0.7 ×   Where,  50  d : Path length (km) w/ 2 − Bc W= ∫ −w/ 2 10 20 Where, Bc: Signature depthSlide No 185
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