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Training Module
on
MW radio engineering
Learning today……
Understanding Microwave link : applications, configuration, operating parameters, system calculations
Line of Sight requirements and Antenna Heights Antenna Installation alignment and its parameters,
safety and quality MW Link Installations and commissioning :
standard practices : NEC’s approach Concluding : General site issues: questions &
answers
1
excerpt from theScientific American
July 1892
In the specification to one of his recent patents, Thomas A. Edison says:
“I have discovered that if sufficient elevation be obtained to overcome the curvature of the earth’s surface
and to reduce to the minimum the earth’s absorption, electric signaling between distant points
can be carried on by inductionwithout the use of wires.”
MICROWAVE PATH ENGINEERING – OVER 110 YEARS AGO!
• Operates on a “Line-of-sight" principle
• Use Two antennas aimed directly at one another
• Transmit Digitally modulated Microwave Frequencies through free space from one terminal to another
• Typically transmit simultaneously in both directions (Full Duplex)
Basic characteristics
4 0 0
1 0 0
2 0 0
3 0 0
0 . 5 4 . 54 . 03 . 53 . 02 . 52 . 01 . 51 . 0 5 . 0
T y p i c a l P a t h P r o f i l eD i s t a n c e ( m i l e s )
Line of sight Point to Point MW link
FWS (Point-to-Point Transport) and FWA (BWA, Access) Hops
POP – Point of Presence
PBX
CPECPE
Nodal (Hub) Site
155 Mbit/s Sonet/SDH FWS (Fixed Wireless System) Hop
CPE
ClearBurst MB Point-to-Multipoint FWA (Fixed Wireless Access) Broadband
Links
CPE – Customer’s Premises Equipment:
- Frame Relay- Video Conference
- Sonet/SDH (PTP) - ATM Switch
- LAN/IP - Base Station - T1/E1 - POTS - Sonet/ SDH - ISDN
Deployment and applications
FWS and FWA (BWA) Radio Hops
Sonet/SDH NxOC-3 or NxSTM-1Backbone FWS (Radio-Relay) Hop
OC-12 or STM-4 Fiber Ring
Long Distance 2xT1/E1 Unlicensed Hop
Short Distance 4xT1/E1 HopsAccess Hops
Short Distance SONET/SDH Hop
X
X
Transport HopNMS system
GSM Network layout
Fiber and MW transmission media in GSM/CDMA Networks
23 GHz (OC-3)
38 GHz (N x DS1)
18 GHz (N x DS1) 18 GHz (DS3)
BTS
BSC
MTSO(MSC)
BSC
(DS3 or OC-3NxOC-3 ) or 155 (Nx0C-3) Self-Healing Ring
BTSBTS
BTS
FWS Microwave Applications
PCS/Cellular Site Interconnection MTSO (MSC) - Switching Office BTS - Base StationBSC - Base Station Controller
(North American Hierarchy)
Access and metro /transport networks
Core Network Topologies
Some Attributes of Digital Microwave Radios • Superior availability - route security (no cable cuts)• Rapidly expandable and upgradeable, in-service if protected
• High quality - no multihop “noise” addition
• Rapid deployment over difficult terrain and into urban areas
• Economical - no copper or fiberoptic cable deployment
• Robust to fading and interference
• Insensitive to antenna feeder system and long-delayed on-path echoes
• Highly efficient data and broadband transport
• Exacting in-service visibility of radio hop performance with NMS
• Seamless interconnectivity to an ever-expanding digital transport (fiberoptics and other), PABX/MSC switch, and LAN/IP world.
1 M H z 1 0 M H z 1 0 0 M H z 1 G H z 1 0 G H z 1 0 0 G H z 1 0 1 2 1 0 1 4
M i c r o w a v e s
A M B r o a d c a s t R a d i o U H F T e l e v i s i o n
F M B r o a d c a s t R a d i o
V H F T e l e v i s i o n
M o b i l e R a d i o
S h o r t w a v e R a d i oM o b i l e R a d i o
V i s i b l e L i g h t
F i b e r O p t i c s
1 0 0 0 m( 3 0 0 K H z )
1 m m( 3 0 0 G H z )
1 c m( 3 0 G H z )
1 0 c m( 3 G H z )
1 m( 3 0 0 M H z )
1 0 m( 3 0 M H z )
1 0 0 m( 3 M H z )
Typical Electromagnetic spectrum
3xDS3/OC-3/STS-34xDS3, 4xE3/STM-1
Capacity
GHz T1/E1
DS3 or 28 T1 E3 or 16 E1
Frequency Band: 2 86 1813 23
Backbone Transport
2 T1/E1
4 T1/E1
4211 37
16 T1
NxOC-3/STM-1
10
Network Management
Element Manager
SNMP Interface1:N
Backbone & Access
Unlicensed
1-5mi/2-8km 5-10mi/8-17km7-15mi/12-25km >15-60mi/25-100km
Access
Broadband Wireless Access (FWA)
26
8 E1
Typical Path Lengths:
Transport and Access Bands
Example of capacity and frequency bands
CEPT PDH Hierarchy
140 Mbit/s(1920 Ch)
1
2...
1
2...
2
3
1
30/31*
4E1
E2
E3
16
34 Mbit/s(480 Ch)
1234
E3
34.368 Mbit/s(480 Ch)
8.448 Mbit/s(120 Ch)
2.048 Mbit/s(30/31 Ch)
PCM ChannelBanks
M34-140Radio MUX
1stOrder
CEPT Hierarchy is the international TDM digital standard everywhere except North America (USA, Canada), Taiwan, Korea and Japan.
1234
M8-34
3rdOrder
E4
Skip Mux
M2-8
2ndOrder
M2-34
Skip mux
VF/data/LAN/IP andteleconferencing circuits
16 x 2.048 Mbit/s E1 Trunks
PDH -Plesiochronous(asynchronous) DigitalHierarchy
*30 VF Channels with signaling channel or 31x64 kbit/s Data Channels (no signaling)
TDM: CEPT PDH Hierarchy
Voice Channel
Equivalent
130120480
1920/1890*
Desig-nation
E0E1E2E3E4
No. of E1 Trunks
30/31 = 1E114
1664/63*
Bit Rate(kbit/s)
642,0488,448
34,368139,264
LineCode
AMIHDB3HDB3HDB3CMI
*63 E1 (1890 VF ch) are mapped in Synchronous Digital Hierarchy (SDH)
AMI, HDB3, & CMI codes are bipolar.
Cable types: 120Ω Twisted Pair, 75Ω Coax(Length/type assigned for 6 dB maximum loss)Ref: ITU-T G.703, G.704
CEPT PCM Analog-Digital PCM Quantizing Code is A-Law
PDH - Plesiochronous Digital Hierarchy
SDH Fundamentals: Rates
Line Rate(Mbit/s)
SDH Signal PDH Signal# E1 (2048 kbit/s)
VF Transport
2.048 VC - 12 1 30
34.368 VC - 3 16 480
51.84 Sub-STM-1* 21 630
139.264 VC - 4 64 1,920
155.52 STM - 1 63 1,890
622.08 STM - 4 252 7,560
2488.32 STM - 16 1,088 30,240
9953.28 STM - 64 4,032 120,960
SDH Synchronous Digital Hierarchy PDH Plesiochronous Digital Hierarchy*Sub-STM-1 RR-STM, STM-0 = 51 Mbit/s for Radio Relay)Ref.: ITU-R Rec. F.750-3 (1997)
Radio or Fibre
Fibre
1:N Radio or Fibre
SDH Fundamentals: Mux
Note: Bold indicates commonly available multiplexer interface
RRRP
NNI
SDH Synchronous Digital HierarchySTM Synchronous Transport ModuleVC Virtual ContainerTU Tributary UnitTUG Tributary Unit GroupAU Administration UnitAUG Administration Unit GroupATM Asynchronous Transport ModeRRRP Radio-Relay Reference PointNNI Network Node InterfaceSub-STM-1 = RR-STM (52 Mbit/s for radio) = STM-0
ATM
x4
Pointer Processing
MultiplexingAligningMapping
DS1 VC11 TU11
VC3
VC12
VC2 TUG-2
TUG-3
VC3
VC4 AU4
AUG STM-N
E1DS1
DS2
E3DS3
E4
x1
x1x1
x1
x3x3
x3
x7
x3
AU3
x1
TU12
TU-3x1
Sub-STM-1
TU-2
Basic Building blocks of MW Link
Basic Building blocks of MW Link
Circulator, Filter(CBN)
WaveguideRFRF
Circulator, Filter(CBN)
Waveguidef [GHz]
Channel
BB = Basebande.g. 155 Mbit/s
Classical Design
Channel
Demodulator16 - 128 QAM
Modulator16 - 128 QAM
IF = Intermediate frequencye.g. 140 MHz
RF = Radio frequencye.g. 7.5 GHz, 18.7 GHz
TXTransmitter
RXReceiver
Basic blocks of radio
IDU
Important to know…
IDU Functional blocks
ODU configuration
ODU Layout
• Outdoor Units (ODUs) are software configurable so that capacity upgrades can be made without climbing towers.
• Indoor Units (IDUs) support capacities of 2/4E1, 4/8E1, 16E1, E3, 4/8DS-1, or DS3 and are frequency independent so that they can be used with any ODU of like capacity.– Minimal Installation time– Single coaxial cable connection between IDU and ODU– Dual polarity DC input of (±21.6 to ±60 VDC)– Adjustable transmit output power– Frequency/channel setting via keypad or laptop PC– Diagnostic loopbacks accessible via laptop PC– Capacity to store 25 different channel plans
ODU functional modules
LineInterfac
e
MUX MOD
DEMUX DEMOD AGC N-plexor
LIU Input MUX PLL TX FPGA
TX IF PLL TX IF
RX FPGADEMUX FrameFrame SyncPrivate Link
DEMOD LockLow BER (>1e-9)High BER (>1e-3)
AGC
ODU Communication
N-plexor
ALC
≈
≈
PAIF LO RT 1848 PLL
Synth Up Conv. Osc UnlockSynth TX Offset VoltageSynth TX Main Loop UnlockSynth TX Offset Loop Unlock
Synth Rx Main Loop UnlockSynth Rx Offset Loop UnlockSynth Rx Offset Loop Voltage
TX Synth
RX Synth
LNA
PA
70MHz
310MHz
2158MHz
1778MHz
Line Interfac
e
MUX MOD
DEMUX DEMOD AGC N-plexor
LIU InputMUX PLLTX FPGA
TX IF PLL TX IF
RX FPGADEMUX FrameFrame SyncPrivate Link
DEMOD LockLow BER (>1e-9)High BER (>1e-3)
AGC
ODU Communication
N-plexor
ALC
≈
≈
PAIF LO RT 1848 PLL
Synth Up Conv. Osc UnlockSynth TX Offset VoltageSynth TX Main Loop UnlockSynth TX Offset Loop Unlock
Synth Rx Main Loop UnlockSynth Rx Offset Loop UnlockSynth Rx Offset Loop Voltage
TX Synth
RX Synth
LNA
PA
70MHz
310MHz
2158MHz
1778MHz
Far End SP Far End RF Plug-in
Near End RF Plug-inNear End SP
Link Block Diagram
Link Block Diagram
IDU-Indoor Unit
ODU Components
Signals on IF cable –IDU-ODU
Protection and Diversity
Protection Schemes and
Diversity Arrangements
Protection and Diversity
The Need for Protection and Diversity
In the past, short traffic interruptions without traffic disconnect in microwave links were often acceptable to many private users.
Expectations changed with the digital microwave transport of MSC-cell site data, ATM, high speed data transfer, teleconferencing, imaging (medical, etc.), and such technology as the new digital mobile trunking systems.
Excessive numbers of short fade hits (circuit interruptions) are now barely tolerable, except in LAN/IP transport and access (millimeterwave) hops impacted by rain cells, long-term outages (traffic disconnects) are usually unacceptable.
87
Protection Schemes
*Reverse Channel Switch command from far end receivers ** If FD is permitted
Equipment degradation, failure:– 1+1, hot-standby or on-line modules …HS– 1:N, one standby for >2 modules ……..HS
Antenna system misalignment, failure:– Split transmitters + RCS* ………….HS+ST– Two-dish hybrid diversity** ….HD, SD+ FD– Self-healing ring (loop) architecture …..SR
Protection Types
1+1 hot-standby protection …………………….HS
1+1 on-line (paralleled elements) protection ...HS
1:N module protection ………………………….HS
1:N multiline protection …………….HS or HS+FD
Split transmitters with RCS* ……….……...HS+ST
Self-healing ring (or loop) architecture …….….SR
*Reverse Channel Switch command triggered by the dual failure (outage) of both far-end receivers
Protected & Diversity - Dual Antenna
CBN
10dBCBN
1+0 Equipment Protection - "1+1 HSB" Configuration
RPS RPS
f1f1af1
f1af1`f1bf1`f1b
f1a
f1a
TX
TX
Station BStation A
Ch. 1(STM-1)
Ch. 1(STM-1)
DM RXf1b
DM RXf1b 10dBOP
PR f1b PR
TX MDf1b
TX MD
OP
OP
PR
MD
MD
RXf1a
RXf1a
DM
DM
PR
OP
1+0 Equipment Protection - Space Diversity
f1f1af1
f1af1`f1bf1`f1b
CBN
Station BStation A
Ch. 1(STM-1)
Ch. 1(STM-1)RPS RPS
f1b PR
TX MDf1b
TX MD
OP
OP
PR
MD
MDf1a
f1a
TX
TX
CBN
RXf1a
RXf1a
DM
DM
PR
OP
CBN
CBN
DM RXf1b
DM RXf1bOP
PR
Frequency (GHz)
Minimum Spacing (m)
Ideal Spacing (m)
6,8 4,5 10
7 4,5 10
13 2,5 5
15 2,0 5
Typical spacing for SD
∆ ∆
Microwave Radio Technology - Space Diversity
DMRX
TX MDCBNMain
+DMRX
TXMD CBNMain
+
STM-1 STM-1
CBNDiv
RX
Lengthcompensation
CBNDiv
RX
SD +HSB
TXMDCh. 1
(STM-1)
DM RX
horizontal f1a
f1b
Ch. 1(STM-1)
DMRX
TX MD
f1a
f1b horizontal
140MHz
140MHzCBN CBN
Ch. 2(STM-1)
DMRX
TX MD
f1a
f1b
TXMDCh. 2
(STM-1)
DM RXvertical
f1a
f1b vertical
140MHz
140MHz
PWPW
CBN CBN
OP2f1
OP2f1
V
f1OP1f1
OP1
f
H
Block Diagram - 2+0 Configuration with XPIC
Clock synchronizationData compensation
V VH H
2 Waveguidepro Station
Microwave Radio Technology - Frequency Diversity
f1a
f3a
f1b
RPS CBNChannel 1
MD TX
MD TX
DMf3b
RX
RXDM
f1 f3f
f3f3af3
f3af1
f1af1
f1af3’f3bf3’f3b
f1’f1bf1’f1b
Hot-Standby & Space Diversity
Hot Standby Terminal Hot Standby Terminal with Space Diversity Receivers
*
* Power splitters in digital radios are always asymmetrical, not 3/3 dB as in analog radios, as data are errorlessly switched - not combined as are analog radio basebands. A 3/3 dB RF receiver splitter provides no protection benefits over the 1/7 dB splitter, and will lower fade margins 2 dB for 58% more outage time.
Splitter/Combiners
Waveguide Coupler Primary Path Insertion Loss
Standby Pass Insertion Loss
6 dB unequal coupler 1.6 dB 6.4 dB
3 dB equal splitter 3.5 dB 3.5 dB
RFD Configurations
1+0 1+1 HH
2+0 1+1 HS
Hybrid module for NEC radios
Cost-effective method of providing T1/E1 trunk redundancy in mixed radio, fiberoptics, span lines.
Protects against Path, Site, and Equipment Failures with non-protected radio repeaters - lowers costs ~40%.
Only protection from long-term periods of unavailability due to fiber cuts, power fades such as heavy rain at higher frequencies, infrastructure failures, etc.
Operation, fault location, testing, and maintenance are simplified.
A ring-closure microwave hop (perhaps longer or with degraded performance) or other T1/E1 trunk for ring closure (fiber, leased line) is necessary.
Benefits of Ring Protection
Ring (Loop) Protection (SR)
Component mountings- IF Module
The IF Module (IFM) consists of the following items: TX IF assembly RX IF assembly DC-DC converter
dB
dB
dB
dB
2 *
Syn
2 * Syn
DC
DC CPU
dB
dB
High integratedRF Module RF Diplexer
Modulare ODU-Design
IF
Antenna
OP
f1
H
V
STM-1
DPU
EOW
Modulator
Demodulator
Power Supply
IDU
Broad Band Filter
ODUcoax.cable
Frequencies 7 up to 38 GHz
Operation mode 1+0 with integrated antenna In some cases of interest in an offer because of the lowest price
Some more configurations..
OP
f1
H
V
Frequencies 7 up to 38 GHz
STM-1
DPU
EOW
Modulator
Demodulator
Power Supply
Broad Band Filter
ODUcoax.cable
wave guide
IDU 155-16/128 LS
Operation mode 1+0 with separate antenna
Operation mode 1+1 HSB with integrated antenna
Frequencies 7 up to 38 GHz
f1
H
V
BK
DPU
EOWModulator
Demodulator
Power Supply
DPU
EOWModulator
Demodulator
Power Supply
ODU
ODU
Coupler
coax.cable
Slave-IDU
Master-IDU
1,3 dB
6,3 dB
Operation mode 1+1 HSB with integrated antenna
Frequencies 7 up to 38 GHz
f1
H
V
BK
DPU
EOWModulator
Demodulator
Power Supply
DPU
EOWModulator
Demodulator
Power Supply
ODU
ODU
Coupler
coax.cable
Slave-IDU
Master-IDU
1,3 dB
6,3 dB
Operation mode 4+0 or 2x(1+1) dual polarized CCDP with XPIC
STM-1 DPU
EOWModulator
Demodulator
Power Supply
DPU
EOWModulator
Demodulator
Power Supply
4 x IDU 155-16/128 LS
OMT
Waveguide
Wave-guide
STM-1
Frequencies 7 up to 38 GHz
f1
f1
H
V
f3
f3
OP1
OP3
OP2
OP4
ODU LX – Adjacent ChannelsODU S – 1 Ch. to be left
ODU
ODUCoupler
STM-1 DPU
EOWModulator
Demodulator
Power Supply
DPU
EOWModulator
Demodulator
Power Supply
STM-1
ODU
ODUCoupler
Operation mode 4+0, coupler version in dual polarized ACAP
STM-1 DPU
EOWModulator
Demodulator
Power Supply
DPU
EOWModulator
Demodulator
Power Supply
4 x IDU
OMT
Waveguide
Wave-guide
STM-1f2
f1
H
V
f4
f3
OP1
OP3
OP2
OP4
Frequencies 7 up to 38 GHz
ODU
ODUCoupler
STM-1 DPU
EOWModulator
Demodulator
Power Supply
DPU
EOWModulator
Demodulator
Power Supply
STM-1
ODU
ODUCoupler
90°
Hhorizontal
Frequency Patterns - Transmission via 2 Polarizations
1. Polarization
2. Polarization
V: vertical
Orthomode transducer(OMT)
V
TXMD
DM RX
f1a
f1b
CBNf1f1
TXMD
DM RX
f1a
f1b
CBN
f1f1
H
VH
Waveguide V
Waveguide H
Operational parameters and system planning
Microwave Frequency Required Necessary Antenna Gain Maximum Distance between terminals Receive Signal Level Margin Link availability
Understanding operating parameters
Understanding operating parameters
Understanding Threshold for receivers
TX
Terms of Microwave Radio Technology - System Overview
Max. powere.g. +31 dBm
[1.25 W]
Output power
min. powere.g. -73 dBm
[50 pW]
Fadingmargin
Free space attenuation e.g. 143.9 dB(Distance d = 50 km)
(Frequency: f = 7.5 GHz)
( )f[GHz]d[km]log2092.40
a ⋅⋅+=
CBNwaveguide
e.g.5.3 dB
CBNwaveguide
Antennagaine.g.
41.4 dB
Antennagaine.g.
41.4 dB
CBNwaveguide
CBNwaveguide
e.g.5.3 dB
System attenuation
(e.g. 71.7 dB)
Input power
RX
System gain
SYSTEM GAIN (to 10-3 BER or
LOF)Top of Bay Antenna Port
123
Transmitter Output Interface
Repeater Station
Top of Bay Antenna Port
RSL IN
1 2 3
ReceiverInput Interface
SYSTEM GAIN. dB
XMTR Power Out - RCVR RSL In (for 10-3 BER) at the Antenna
Ports. Typically 100 dB
NPL - NET PATH LOSS. dB
Waveguide In Site A to Waveguide Out at Site B. Typically 60 dB
(Excluding Fade Activity)
RECEIVER RSL INPUT. dB
RSL = XMTR Power Out - NPL
THERMAL FADE MARGIN. dB
TFM = System Gain - NPL
NET PATH LOSS (NPL)
FREE SPACE LOSS
(NO FADE)
Terminal Station
EIRP = P0 - Lf + Ga (FCC/ETSI Constraints)
Ga
Lf
P0
System Gain, Net Path Loss
Receive signal level calculation
RSL(dBm) = Tx power(dBm) + Tx antenna gain(dBi) - Free Space Loss(dB) – Branching Loss – Feeder cable loss + Rcv antenna gain (dBi) where Free Space Loss(dB) = 32.4 + 20logF +20logD where: D is Kms, F is MHzFor example:Given: Path Distance of 10 Kms, Radio Frequency is 7 GHz, Tx Power is 20 dBm, and Antenna Gain(both sides) is 38 dBi
•Free Space Loss = 32.4+20log(10)+20log(7000) = 32.4+20+76.90 = 129.30 dB
•RSL(dBm) = 20 dBm + 38 dBi – 129.3 dB + 38 dBi = - 33.3 dBm
Receive signal level margin
• Directly determines the availability of the link by providing threshold “cushion” against signal fade due to environmental conditions, i.e. rain, snow, hail, etc.
• Rain data for geographic location is needed to calculate availability once RSL margin is known.
System Gain, Net Path Loss RF Signal, Noise, and Interference Levels Static and Dynamic Thresholds Microwave Spectral Efficiency QAM, QPSK Modulation DSSS, OFDM/COFDM Signal Spreading Microwave Spectrum Calculations Co-Channel Dual Polarization (CCDP) Latency ATPC and DTPC Frequency Bands, Interference, Terrain Scatter Frequency Band Selection
Technical Topics that define Digital Radio Hops
Technology
ATPC and DTPC
DTPC – Dynamic Transmit Power Control (TRuepoint, Galaxy 23)ATPC – Automatic Transmit Power Control (all other radios)
ATPC or DTPC, features that reduce transmit powers except with far-end receiver alarms during deep fades, are occasionally assigned to some microwave links for one of the following reasons:
Prevents receiver front-end overload in higher frequency links assigned high rain fade margins
Complies with FCC (and other) EIRP constraints in short hops, <17 km in the 6 GHz bands and <5 km at 10 and 11 GHz,
Prevents receiver overload in shorter 6, 10, and 11 GHz paths requiring large antennas in frequency-congested areas
Reduces interference levels at hubbing sites and into adjacent links in frequency-congested areas.
ATPC
ATPC
DTPC/ATPC
-10
-20
-30
-40
-50
-60
-70
-80
Rec
eive
Sig
nal
Le v
el,
dB
m
+20
+10
0
-10
0 10 20 30 40 50 60 1-Hour of Rain Fade Activity, Minutes
Tran
smit ter O
utp
ut P
ow
er , dB
m
Fad
e D
epth
, d
B
0
-10
-20
-30
-40
-50
-60
-70
Transmit and Receive RF Levels During 1-Hour Fade Activity in a High Fade Margin (60dB) 23 GHz DTPC Link.
RSL follows fades below the “setting point”, -45 dBm in this example
RSLw/DTPC
Fade Depth,RSL w/o DTPC
Outage Threshold
NoOutage
DTPC RSL
Setting Point
-45 dBm
TransmitterOutput
10-6 BER Receiver Overload Error-free
Time
RSL
ATPC Off
ATPC On
Fading
Stopped Fading
7/10 dB
7/10 dB
15/18 dB BER = 10 -11
BER = 10 -6
10 –6 Th + 15/18 dB
Un-Fading
ATPC
Important to know…
Useful 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% efficiency) 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 (4/3rds, 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
Important to know…
Site Details Address, Lat-Long, Azimuth wrt North, equipment layout
Access /permission/approach road
Link Budget Expected Receive level/ Fade Margin
Tx Planner/Operator
Frequency of operations and Tx power;
Type of antenna, Height of antenna, Polarization
LOS cleared
Cabling details External alarm termination details/color code
NMS IP address/DCN planning /cabling/router/converter
Traffic E1/STM1 termination /Through
EOW, Auxiliary channels/Sideway E1
Frequency Sub Band [GHz]
Duplex [MHz]
10 350 10224
10574
350 10252
10602
Capacity BW [MHz] / Channel Raster
16 E1 28
8 E1 14
4 E1 7
2 E1 3.5
25 MHz Channel Filter Bandwidth
16 E1 CAPACITY
5.5 MHz 14 MHz 5.5 MHz
Understanding Frequency plan
Co- and adjacent-channel interference
Low fade margins
Antenna k-factor decoupling
Antenna misalignments
Dispersive (spectrum-distorting) fades
Ducting, defocusing, and obstruction fades
EMI and other environmental effects
Effective diversity arrangements lessen the impact of otherwise unacceptable conditions:
Fade Margin Degradations