fa pe

1
??f?a??? ?p????????e?

• Communication Link Analysis
• ???ep????????a?? S?st?µata ?a?
• ?p?????sµ?? T???ß??

2
Communication End-to-End System

• ?e??t? t?? Receiver Front End ?a? t?? ?a?a????
  (Channel)

3
Communication Budget Analysis (1/2)

• Communication Link analysis µe?et? ???????? t?
  s?st?µa
• ??a??e? ???????? t? t??ep????????a?? s?st?µa ap?
  t? p??? µ???? t? ???? t?? p????f???a?
• Link budget (LB) ap?te?e?ta? ap? t?? ?p?????sµ?
  t??
• ???s?µ? ?s??? s?µat?? st? d??t?
• Interfering noise power p?? ?p???e? st? d??t?
• LB e??a? ??a? ?s?????sµ?? ap? gains ?a? losses
  t?? t??ep????????a??? st???e??? (components) st??
  p?µp?d??t?
• ?e????? pa??µet??? t?? communication link e??a?
  stat?st????
• ?p?µ???? t? link budget ???e? e?t?µ?s? ??p????
  pa?aµ?t???
• S??p?? t?? link budget
• ?a ß?e? t? p?a?µat??? s?µe?? ?e?t?????a?
  (operating point) t?? s?st?µat??
• ?eßa???e? ?t? BER ? apa?t?s? s?st?µat?? (system
  requirement)
• To LB e??a? t? ßas??? e??a?e?? p?? d??e? t?
  d??at?t?ta st?? system engineer ?a ?a????se? t?
  s??????? ep?d?s? t?? s?st?µat??
• ?? LB de???e? t? s??????? s?ed?asµ? t?? s?st?µat??

4
Communication Budget Analysis (2/2)

• ?p? t? LB ??p???? µp??e? ?a ??????e? a? t?
  s?st?µa ?a ??a??p???se? t?? p??d?a??af?? µe
  µe???? pe???????, marginally ? ?a? ?a?????
• LB s?????? ???s?µ?p??e?ta? ?? score sheet st??
  a????s? ??a
• system tradeoffs
• configuration changes
• subsystem interdependence
• ?? LB µp??e? ?a ß????se? st?? ?a????sµ? t??
  equipment weight, size, power requirement,
  technical risk ?a? cost.

5
?a??de??µa e??? Satellite System Model

• Se ??a satellite channel, ??a pa??de??µa,
  ?p?????? d??f??a losses
• Losses ? degradation p???a????ta? ap? signal
  loss, noise ? ap? signal loss ?a? noise µa??.

Transponder
6
Radio Wave Propagation

7

Communication Link Modeling (1/4)

8
Communication Link Modeling (2/4)

9

Communication Link Modeling (3/4)

• ??a ?s?t??p??? ?e?a?a e??a? ?da???? ?e?a?a ?
  ?p??a a?t???ß??e? ?s?? µe µ??ad?a?? gain p???
  ???e ?ate????s?
• S?????? ???s?µ?p??e?ta? ?? ?e?a?a a?af???? se
  as??µate? ep?????.
• ? Effective Isotropic Radiated Power (EIRP)
  ????eta? ??
• ???a? ? µ???st? a?t???ß????µe?? ?s??? p??
  d?at??eta? ap? t?? Tx p??? t?? ?ate????s? t??
  µ???st?? gain

10

Communication Link Modeling (4/4)

• ? ?s??? p?? a?t???ß??e? µ?a ?e?a?a µetaß???eta?
  µe t?? ?ate????s?
• G?a p?a?µat???? ?e?a?e? ???s?µ?p??e?ta? ?
  Effective Radiated Power (ERP).

11
Link ?a??µet???

in dB
Transmitter Parameters
Receiver Parameters
Free Space Loss
Nature
Sometimes the noise figure F is used instead of
the equivalent noise temperature Teq
12
Parameter Variable Definitions

• d Tx-Rx separation
• f Frequency
• ? Wavelength
• D Antenna Diameter
• ? Antenna Efficiency
• Pr Receive power
• Pt Transmit power
• No Thermal noise power
• C Carrier power
• Gt Transmit gain
• Gr Receive gain
• Ls Free space loss
• Laf Antenna Feeder Loss
• Ltf Transmitter Feed Loss
• Lat Atmospheric Loss
• Lrf Rain Fade Loss
• Lp Pointing Loss

Ts System noise temperature Ta
Antenna noise temperature T Feeder
ambient temperature Te Effective
receiver temperature F Noise figure ?
Flux density EIRP Effective Isotropic
Radiated Power G/T Gain-to-Temperature ratio
(Rx sensitivity) C/No Carrier-to-noise
ratio Eb/No Energy per bit to noise ratio Rb
or Rs Channel Bit or Symbol Rate A Area of
antenna Ae Effective area of antenna k
Boltzmanns constant W Noise bandwidth
13
RF Link ?p?????sµ?? (1/5)

• Free space µ??t??? d??d?s?? ???s?µ?p??e?ta? ??a
  ?a p??ß???e? t?? ?s?? t?? s?µat?? ?ta? Tx ?a? Rx
  ????? direct Line-of-Sight (LOS)
• Receiver ß??s?eta? se ap?stas? d (m) ap? t??
  p?µp?
• ?s??? ????? e??a? s????t?s? t?? ap?stas??, d
• ? p????t?ta ?s????, p(d), se ??p??a ap?stas?, d
  e??a?
• ?s??? ?????, Pr, (ep?s?? ???st? ?? Friis free
  space equation) e??a?
• ?p?? Aer e??a? ? effective area t?? ?e?a?a?
  ?????
• ? effective area

14
RF Link ?p?????sµ?? (2/5)

• Antenna effective area Ae ?a? physical area Ap
  s??d???ta? µe t? s???e?t??? ??a??t?ta, (Antenna
  efficiency) ?
• ?? gain t?? ?e?a?a? (?a? transmit ?a? receive)
  d??eta? ap?
• Antenna effective area ??a µ?a ?s?t??p??? ?e?a?a
  (G 1) e??a?
• ? ?s??? ?????, Pr, se ??p??a ap?stas? d ??a
  isotropic antenna e??a?
• ? ????? (4?d/?)2 Ls ????eta? ?? path loss
  factor ? free space loss

15
RF Link ?p?????sµ?? (3/5)

• ??a ep?s?? ?at?????? ???µa e??a? unity-gain
  propagation loss
• S?µe??ste ?t? unity-gain propagation loss e??a?
  s????t?s? t?? s????t?ta? ?a? t?? ap?stas??!!
• Unity-gain propagation loss a?t?p??s?pe?e? µ?a
  ?p??et??? ap??e?a ?s???? st? ???? p?? ?a e??aµe
  a? ? ?e?a?a ????? ?ta? ?s?t??p???
• ?ta? ? ?e?a?a ????? de? e??a? ?s?t??p???
• Ls s??d?e? t?? ?s?? e?p?µp?? µe t?? ?s?? ?????
• Ls 1 d????e? ?aµ?a ap??e?a st? s?st?µa
• ? ?s??? ?????, Pr, µp??e? ?a ??afe? se p?????
  µ??f??

16
RF Link ?p?????sµ?? (4/5)

• ?f?? Pr(d) e??a? s????t?s? t?? ap?stas?? st?
  tet??????, µe???eta? ?s? ? ap?stas? a????e? µe
  ???µ? 20 dB/decade
• ? s???????? attenuation factor, ?, ??a t? RF link
  d??eta? ap?
• ? t?µ? t?? ? se dB µe????? f???? ???µ??eta? Path
  Loss (PL)
• Path Loss d??e? t?? e?as????s? (attenuation) t??
  s?µat?? se dB µeta?? Tx ?a? Rx.

17
RF Link ?p?????sµ?? (5/5)

• ?p?s?? µp??e? ?a ??afe? ?? e???

18
?a??de??µa 1

• ? d?a??s?µ? ?s??? p?? apa?te?ta? se µ?a ?e?a?a
  ????? e??a? 10-6W (d??ad? -60 dB µe a?af??? t?
  1W). ?? ?e?a?e? e?p?µp?? ?a? ????? ????? ? ???e
  µ?a ap??aß? 40 dB. ? s????t?ta t?? f????t?? p??
  ???s?µ?p??e?ta? e??a? 4GHz ?a? ? ap?stas? µeta??
  t?? ?e?a??? e??a? 30 µ???a. ??e?te t??
  apa?t??µe?? ?s?? t?? p?µp??.
• ?p?µ???? a?t??a??st??ta?

19

?p?????sµ?? Te?µ???? T???ß?? (1/3)

• Teµ???? T???ß?? (Thermal Noise ) ??t?stas??
• T???ß?? p?? ?fe??eta? se d?a??µa?s? t??
  ??e?t????? ?e?µat?? ? ????s?? t?? ??e?t?????? se
  ??a a????
• ???te??p??e?ta? ?? AWG?
• Mean Square Voltage value of noise ??a s????t?te?
  lt6000GHz p??se????eta? µe p??? ?a?? a???ße?a ap?
  t? s??s?
• ?p??
• vn noise voltage
• k Boltzmanns constant, 1.38x10-23 J/K
  -228.6 dBW/KHz
• R resistance, ohms
• W noise bandwidth, Hz
• Ts system temperature, kelvin

20

?p?????sµ?? Te?µ???? T???ß?? (2/3)

• ? ?s??? ????ß??, N, se ??a p??sa?µ?sµ??? f??t??
  d??eta? ap?
• N e??a? a?e???t?t? t?? s????t?ta? (??a a?t?
  ???eta? white)
• ?p?s?? de? e?a?t?ta? ap? t? µ??e??? t??
  a?t?stas??
• ????, e?a?t?ta? ap? t?? ?e?µ???as?a t?? d??t?
• ??t? µa? ?d??e? st?? ?d?a t?? effective noise
  temperature ??a p???? ????ß??
• ? µ???st? single-sided (µ??? ?et???? s????t?te?)
  power spectral density, N0, (noise power se 1-Hz
  bandwidth) e??a?
• ??t? ? ??f?as? ????ß?? ?s??e? ??a ??a ta
  t??ep????????a?? s?st?µata
• S?????? a?af??eta? ?? non-quantum thermal noise

21

?p?????sµ?? Te?µ???? T???ß?? (3/3)

• S?µf??a µe ta p??????µe?a, µ?a ????ß?d??
  a?t?stas? R ?s?d??aµe? µe a????ß? ?d?a? t?µ?? se
  se??? µe p??? ????ß?? µe µ?s? tet?a?????? t?µ?
  t?s??
• ? ?e?µ???? ????ß?? t?? a?t?stas?? µetad?deta?
  µ?s? e??? ??aµµ???? ?????µat?? (d?????) µe
  s????t?s? µetaf???? ?(f), s?µf??a µe t? pa?a??t?
  ?s?d??aµ? ?????µa
• ? fasµat??? p????t?ta ?s???? t?? t?s?? e??d??
  e??a?

R
?(f)
V0

22
????? ????? T???ß?? ???????

• ? s??????? ?s??? ????ß?? p?? ?pe?s???eta? se ??a
  s?st?µa e?a?t?ta? ap? ??a ?a?a?t???st??? µ??e???
  p?? ???µ??eta? ?s?d??aµ? tet?a?????? e????
  f?sµat?? ??a ??aµµ??? s?st?µata, ?p?? e??s??t??,
  ?t?.
• Ge???? ? fasµat??? ap????s? ???e s?st?µat?? G(f)
  (??a ?a? t?? e??s??t??) de? µp??e? ?a e??a? ?
  ?d?a (sta?e??) ??a ??? t? e???? s????t?t?? p??
  pe???e? t? d?????.
• G?a?t? ß??s???µe t? ?s?d??aµ? e???? ?????, BN,
  ?ts? ?ste
• ?p?te
• ?p?? G0 e??a? ? t?µ? t?? G(ff0) ?(f0)2, µe
  f0 t? ?e?t???? s????t?ta.

23
?s?d??aµ? (??e????) Te?µ???as?a ???????

• ?? ?e???s??µe ?t? ??a d????? ?d??e?ta? ap? µ?a
  p??? ????ß?? p?? ??e? ?e?µ???as?a ????ß?? ?s
• ?? t? d?a??s?µ? ???d?? t?? d?????? e??a? G ?a?
  t? ?s?d??aµ? e???? ????? e??a? ??, t?te ? ?s???
  ????ß?? e??a?
• ?p?? ?n e??a? ? ?s??? ????ß?? st?? ???d? t??
  d?????? p?? ?fe??eta? st?? es?te????? p????
  ????ß?? t?? d??????.
• Ge????, µp????µe ?a ?e????µe t? d????? NOISELESS
  ?a? ?a ??ß??µe ?p??? t?? a???µ??? ????ß? p??
  p???a?e?, ??t??ta? t? p??? ????ß?? µe µ?a ??a
  ?e?µ???as?a ????ß?? st?? e?s?d? ?s?e (Te
  ???eta? ?s?d??aµ? ?e?µ???as?a e?s?d?? t??
  d??????). ?p?µ????

24
?a??de??µa 2

• ??a ?e?a?a ??e? ?e?µ???as?a ????ß?? ?ant 10oK.
  S??d?eta? se ??a d??t? p?? ??e? ?s?d??aµ?
  ?e?µ???as?a ????ß?? ?e140oK. ?? d?a??s?µ? ???d??
  t?? d??t? st?? ?e?t???? s????t?ta e??a? G1010
  ?a? t? e???? ????? ????ß?? e??a? ??1.5105Hz.
  ?p?????ste t? d?a??s?µ? ?s?? ????ß?? e??d??.
• ? fasµat??? p????t?ta t?? d?a??s?µ?? ?s???? t??
  ?e?a?a? e??a? kTant (single sided!!). ? ????ß??
  t?? d??t? µp??e? ?a ??f?e? a??????ta? t?
  ?e?µ???as?a p???? ?at? ?e. ?p?µ???? ? s???????
  e?e???? ?e?µ???as?a p???? e??a? ? Tant?e.
• ? fasµat??? p????t?ta t?? e?e???? d?a??s?µ??
  ?s???? st?? e?s?d? t?? d??t? e??a?
• ? d?a??s?µ? ?s??? st?? ???d? t?? d??t? e??a?

25
?fa?µ??? ?s?d??aµ?? ?e?µ???as?a? se e??s??t??
G100 Nn10µW
Ni1 µW

Nout GNiNn 110µW

G100 Noiseless
NoutG(NiNni) 110µW
Ni1 µW

Nni0.1 µW
? es?te????? ????ß?? d?????? ?s?d??aµe? µe
ep?p??s?et? ?e?µ???as?a e?s?d?? !!!!
T???ß?? e?s?d??
26
?e??t?? T???ß?? (Noise Figure) F

• Noise Figure, F
• F, s??d?e? t? SNR st?? e?s?d? e??? s?st?µat?? µe
  t? SNR st?? ???d? t?? s?st?µat??
• ?et??e? t?? µe??s? t?? SNR p?? p???a?e? t?
  s?st?µa
• ???a? µ?a pa??µet??? p?? e?f???e? t? ????ß? p??
  p???a?e? ??a d????? s?st?µa, se s??s? µe µ?a
  reference noise source

????
F??t??
G, BN, Nn
Si Ni
S?GSi NoutGNiNn
27

• ?p??
• Si signal power at the amplifier input port
• Ni noise power at the amplifier input port
• Nni amplifier noise referred to the input port
• G amplifier gain
• ?? Noise figure de? e??a? absolute measure t??
  ????ß?? a??? ??a µ??e??? t?? p?s? pa?ap???
  ????ß?de? e??a? t? s?st?µa se s??s? µe µ?a
  a?af???
• ? a?af??? e??a? ? t?µ? t?? Ni ??a ?e?µ???as?a
  a?af???? ?0290o ?
• ??t? d??e? fasµat??? p????t?ta ?s???? ?0

28
S??s? µeta?? F ?a? Te

• ?p? t?? p??????µe?e? s??se??
• e????a p????pt??? ta e???
• ?p?µ????

29
T???ß?? ap? ??aµµ? µetaf????

• ?st? µ?a ??aµµ? µetaf????, p??sa?µ?sµ??? st??
  a??? ?a? st? t??µa t??. St?? ???d? fa??eta? sa?
  a?t?stas? st? ?e?µ???as?a pe??ß?????t?? t??
  ??aµµ?? T. ???? e??a? ? ?L ?a? ? F µ?a? ??aµµ?? ?
  ?e???? e??? ?p?ß?ßast? µe s??te?est? e?as????s??
  L1/G (Glt1).
• O ????ß?? p?? ?a p????µe st?? ???d? t?? ??aµµ??,
  ?ta? e??a? se ?e?µ???as?a ?, e??a?
• Te????ta? ?t? ? p??? e?s?d?? t?? ??aµµ?? ??e?
  ?iT
• ?????ta? ??a ?e
• ?a? ep?µ????

?ta? ??0 ? FL !!
30

T???ß?? se a??s?de? d?????? (1/4)

• Noise Temperature
• ? ?p?????sµ?? t?? ep?d?s?? e??? RF link s??????
  ???eta? µe ????? t?? ?s?d??aµ?? system noise
  temperature Ts
• ??t? ap?te?e? µ?t?? ep?d?s?? t?? Rx s?st?µat??
  p?? pe???aµß??e? ?e?µ??? ????ß? st? link, radio
  noise ap? t?? atµ?sfa??a ?a? t? outer space, ?a?
  t???? device noise
• ???a? ? temperature p?? ?p???e? st? terminal
  figure of merit (G/Ts)
• ???e st?d?? t?? d??t? ?a?a?t????eta? ap? ??a
  effective ? equivalent noise temperature Te

31

T???ß?? se a??s?de? d?????? (2/4)

• ?eµ???µ??a st?d?a st? s?st?µa ?a?a?t??????ta? ap?
  t? noise figure, F ?a? noise temperature, T
• ?ts?, µ???µe ??a t? s??????? noise temperature,
  Tcomp, ?a? t? s??????? noise figure, Fcomp t??
  d?ad?????? d??????

32

T???ß?? se a??s?de? d?????? (3/4)

• ?p? a?t?? t?? e??s?se??, e??a? fa?e?? ?t? t? 1?
  st?d?? e??a? t? p?? s?µa?t???
• Ta p??pe? ?a ??e? ?s? ???eta? ?aµ???te?? noise
  figure, F1, ?a? noise temperature, T1
• ?p?s?? ?a p??pe? ?a ??e? ?s? ???eta? µe?a??te??
  gain, G1
• St?? p?? p????? pe??pt?se??, µ??te??p????µe t?
  s?st?µa ?? 2 st?d?a µe t? 1? ?a e??a? ? ??aµµ?
  µetaf???? ap? t?? ?e?a?a st? d??t?!
• ?p?µ???? t? ??? composite noise figure ???eta?
  s?µf??a µe t?? p??????µe?? t?p? (?e??? ??0
  290??)

Feed Line
Output
Gtotal ,Fcomp, Tcomp
N
out
L
G1 1/L
L power loss factor
33

T???ß?? se a??s?de? d?????? (4/4)

• ? composite temperature ??a ??aµµ? µetaf????
  d??t? ???eta?
• ?p??
• effective noise temperature t?? d??t?
• reference noise temperature (290? ?)
• ?? ?a? t? noise figure e??a? ??a µ?t?? se s??s?
  µe µ?a a?af???, t? noise temperature de? ??e?
  t?t??? pe?????sµ?
• System Temperature

34
?a??de??µa 3

• ?st? ??a? t?p???? µ??????µat???? d??t??
• S???????? de??t?? ????ß?? t?? d??t?(?e?a?a
  ?e??e?ta? p??? ?d???s??)
• ? ?s?d??aµ? ?e?µ???as?a ????ß?? t?? d??t? e??a?
• ? d?a??s?µ? ?s??? ????ß?? p?? eµfa???eta? st??
  e?s?d? t?? ap?d?aµ??f?t? st? e???? ????? ??
  e??a?

Tant14oK
F6dB
F12dB
Te4oK
???? ap?d?aµ??f?t?
G20dB
G40dB
G30dB
Output
N
out
35
?a??de??µa 4

• ???eta? pa?a??t? to frond end e??? receiver, µe
  noise figure 10dB, Gain 80dB, ?a? bandwidth
  6MHz. H ?s??? e?s?d?? e??a? 10-11W. ?st? ?t? ?
  ??aµµ? µetaf???? de? ??e? ap??e?e? ?a? ?t?
  ?e?µ???as?a ?e?a?a? e??a? 150 K. ?p?????ste ta ?R
  , ?s, Nout SNRin ?a? SNRout

F10dB
G30dB
Tant150oK Sin10-11W
W6MHz
36
3 ?e??pt?se??
Ts ?e?µ???as?a s?st?µat??

• No lossy line
• With lossy line
• With Pre-amplifier between antenna lossy line
  (better performance)

No loss
G, F, TR
TLL
G, F, TR
TLL
G, F, TR
G1, F, Tpre-amp
37

Link Budget Margin (1/2)

• Bit Energy-to-Noise Power ratio, Eb/No
• Se t??ep????????a?? s?st?µata, ?????µe ??a
  s???e???µ??? Eb/No ??a ?a pet????µe ??a
  s???e???µ??? BER
• ?st? M t? margin ? safety factor
• (Eb/No)reqd apa?t??µe?? t?µ? ??a Eb/No
• (Eb/No)r ?aµßa??µe?? ? p?a?µat???
  t?µ? t?? Eb/No
• ?? margin, M, e??a? ? d?af??? µeta?? t??
  apa?t??µe??? Eb/No ?a? t?? ?aµßa??µe??? Eb/No

38

Link Budget Margin (2/2)

• ?p??e? ep?s?? ?a ??afe? ??
• ?p?µ???? se dB
• ?p?s??

S????? d?af???? losses
39
?e?????? t?? ?????t???? RF Link Equations (1/2)

• Wavelength
• Affective Antenna Area
• Antenna Gain
• EIRP
• Lf total loss st? feeder ?a? duplexer

• Flux Density
• Flux Density Received
• ?p?? a? ? ? t?te t? saturation flux density
  st? d???f??? ?p??????eta?
• Free Space Loss

40
?e?????? t?? ?????t???? RF Link Equations (2/2)

• Received Power
• Carrier Power
• Thermal Noise Power
• System Noise Temperature
• (µe ??aµµ? µetaf????)

• Carrier-to-noise ratio
• C/N e?a?t?ta? ap?
• apa?t??µe?? information rate
• apa?t??µe?? SNR ? BER
• modulation µ???d?? ?a? a?t?st???? bandwidth