????S ? :

1
?????? ?????? ???????O??O?

• ????S ?
• ??????????O????? T?????
• ?????S??S? ??. 2
• ??????S ??????S ???????O???S
• ????????? ?????????S????

2
Ge???? µ??t??? d?a???? p???d??de?s??
?? ????t? ?a???? pe?????feta? ?? ??aµµ??? ???????
µetaßa???µe?? s?st?µa. ?aµßa??µe?? s?µa
r(t) s(t) ?
h(t t) n(t) ????st??? ap????s?
h(t t) Sk1L
ak(t)d(t-tk) ??a
r(t) Sk1L ak(t)s(t-tk) n(t)
3
???a??sµ?? d??d?s??

• a????as? (reflection)
• pe????as? (diffraction)
• s??das? (scattering)
• gtep??e?t??? e?as????s? ?a? a??a?? f?s??

4
???a??sµ?? d??d?s??
?????as?

• ???spt?s? t?? ??µat?? se a?t??e?µe?a µe???a se
  s??s? µe t? ?
• ?????as? se ep?f??e?e? p?? d?a???????? pe??????
  µe d?af??et??? d???e?t???? sta?e??
• ?????as? st? ?daf?? (two-ray model)

5
???a??sµ?? d??d?s??
?????as?

• ???spt?s? t?? ??µat?? se a?t??e?µe?a µe a?µ??
  (t?? t???? t?? ? ) p?? ß??s???ta? a??µesa st??
  p?µp? ?a? t? d??t?
• S?µf??a µe t?? a??? t?? Huygen ??a ta s?µe?a t??
  sfa?????? µet?p?? t?? ??µat?? µp????? ?a
  ?e??????? ?? de?te?e???se? s?µe?a??? p????
• ??µ?? t?? ??µat?? ?a? d??d?s? t?? a??µ? ?a? st??
  pe?????? s???? t?? a?t??e?µ????.
• St?? ?????? s????t?te? ?p???e? e???t?s? t??
  fa???µ???? ap? ?e?µet??a t?? a?t??e?µ????,
  p??t?? ?a? f?s? t?? p??sp?pt??t?? ??µat??, e?d??
  p???s??.

6
???a??sµ?? d??d?s??
S??das?

• ???spt?s? t?? ??µat?? se a?t??e?µe?a (?
  ep?f??e?e? µe p??e?????) µe d?ast?se?? µ????te?e?
  ap? t? ?
• ? a???µ?? t?? a?t??e?µ???? ?/?a? p??e????? a??
  µ???da ????? p??pe? ?a e??a? a?????t?? µe?????.
• hc ? /( 8 sin?i ) , ?p?? hc t? ???? t??
  p??e?????
• ?i ?
  ????a p??spt?s??
• G?a ?a ?e??e?ta? a??µa?? ? ep?f??e?a p??pe?
• ( min(h)/max(h)) gt hc

7
??as????s? µe????? ???µa?a?Large scale fading

• ?a??? t? ????t? ap?µa????eta? ap? t? B.S. (10m,
  100m, 1000m) ? t?p??? µ?s? t?µ? t?? ?s???? t??
  ?aµßa??µe??? s?µat?? ?a µe???eta? ßa?µ?a?a af??
  ta ??e?t??µa???t??? ??µata e?as?e???? ?a???
  d?ad?d??ta? st?? ????
• t? fa???µe?? a?t? ep??e??eta? ap? t? a?????f? t??
  ed?f??? ??f??, ß??st?s?, ?t???a, d?af?µ?st????
  p??a??de?

µetad?d?µe?? ?s???
t?p??? µ?s? t?µ? t?? ?aµßa??µe??? ?s???? se
ap?stas? d
path loss
path loss se dB
- a?t?µet?p??eta? µe a???s? t?? µetad?d?µe???
?s????
8
??as????s? µe????? ???µa?a?

• ?pa?te?ta? ? µ??te??p???s? t?? fa???µ????
  µe????? ???µa?a? ?ste ?a e??a? d??at? ?
  p??ß?e?? t?? µ?s?? ?aµßa??µe??? ?s???? se ??p???
  s?µe?? t?? ??????? ?a? ? p??sd????sµ?? ßas????
  p?s?t?t?? ?p?? ?s??? µet?d?s??, pe??????
  ???????, ?ata????s? e????e?a? ap? t? ????t?
  te?µat??? ??p.

Friis free space equation
inverse n-th power propagation model
do reference distance, PL path loss
Log-distance PL model
Log-normal shadowing
9
??as????s? µe????? ???µa?a?

• ???t??a d??d?s?? se e??te???? ????
  (outdoor)
• Okumura ?at?????? ??a ast???? pe??????
• L50 LF Amu(f,d) G(hte) G(hre)
  GAREA
• L50 median value of propagation
  loss
• LF free space propagation loss
• Amu median attenuation relative to
  free space
• G(hte) BS antenna height gain factor
• G(hre) MS antenna height gain factor
• GAREA Gain due to the type of
  environment
• Hata, PCS (EURO-COST)

???t??a d??d?s?? se es?te???? ???? (indoor)
10
??as????s? µ????? ???µa?a?Small scale fading

• a??µa ?a? a? t? ????t? µeta???e?ta? e????sta
  (10cm, 20cm, 30cm) ? st??µ?a?a t?µ? t?? ?s????
  t?? ?aµßa??µe??? s?µat?? ?a a???µe???eta?
  d?aµat??? (30-40dB)
• a?t? ?fe??eta? st? ?t? t? ?aµßa??µe?? ped??
  e??a? t? ?????sµa p????? s???st?s?? (????)
  e???µe??? ap? d?af??et???? ?ate????se?? µe
  t??a?e? f?se??

- a?t?µet?p??eta? µe epe?e??as?a s?µat?? ?a? ???
µe a???s? ?s????
11
?ata??µ??
?ata??µ? Rayleigh
?ata??µ? Rice
12
?ata??µ??
? pa?????ta? ?
p??f?? Ricean e?as????s?? ??a sta?µ? ?????µe?? µe
50 km/h, K0, 4, 8, 16, 32 dB
13
?ata??µ??
?ata??µ?? ap? µet??se?? ?a? t? ta???asµ? t??? µe
?e???t???? ?ata??µ?? (cumulative distribution for
three small-scale fading measurements)
14
??p?? e?as????s?? µ????? ???µa?a?
15
? ????st??? ap????s? t?? ?a?a????

• a? ?e???s??µe t? µet?d?s? e??? f????t?? s?µat??
  sta fc Hz
• ?p?? t? ?s?d??aµ? (µ??ad???)
  ?at?pe?at? s?µa
• p???d??µ? d??d?s?
• ??????t?a ????s? µe ta??t?ta ?
• t? n-?st? ??µa p?? ?aµß??eta? ?p? ????a an(t)
  ??e? µetat?p?sµ??? t?? ???µast??? s????t?ta
  e?p?µp??, (µetat?p?s? Doppler) ?at?
• ?p??
• ep?p???? ??a t? n-?st? ??µa
• e?as????s?
• ?a??st???s?
• a??a?? f?s?? ap? a?a???se??

16
? ????st??? ap????s? t?? ?a?a????

• ?aµßa??µe?? s?µa
• ?p??
  t? ?s?d??aµ? (µ??ad???) ?at?pe?at? s?µa
• ? ???? t?? f?s?? a?apa??stata? ap??? ap? µ?a
  µetaß??t?
• ??a ? ????st??? ap????s? t?? µ??t???? ßas????
  ????? ?a e??a?

17
? ????st??? ap????s? t?? ?a?a????
18
???s?µ???s? ?at? Jakes

• d?as???p?st?? ?µ???µ??fa t?p??et?µ????
  a??µ????a?? ???? ap? t? ????t? (se a??a??et?
  ap?stas?)
• ??a ta d?as???p?sµ??a s?µata ????? t? ?d?? µ?t??
  a??? t??a?e? f?se??
• a? t? p????? t?? µ???pat??? e??a? pe??tt??
  a???µ?? ?a? ?aµ?a ????a ?f???? de? ?s??ta? µe
  p/2 d?asfa???eta? ? stas?µ?t?ta
• ? s????t?s? a?t?s?s??t?s??
  µ????e? µe t? s????t?s? Bessel ?a? ? p??s????s?
  p?a?t??? e??a? a??et? ?a??

19
???f?? ?ata??µ?? ?s????

• ??a ??a? e?peµp?µe?? ????st??? pa?µ?, p??
  µetaß???eta? ? µ?s? ?aµßa??µe?? ?s??? ??
  s????t?s? t?? ???????? ?a??st???s??

20
?as???? pa??µet??? t?? p???d??de?s??

• µ???st? ep?p???? ?a??st???s?
• ?p??µa ?a??ste??se?? RMS ? t?p??? ap????s? ap?
  t? µ?s? ep?p???? ?a??st???s? (?p?? ? ???e tn
  e??a? ????sµ??? µe t?? a?t?st???? ?s??)
• s?????? ??a aµe??t?? ISI

• rule of thumb a? T e??a? gt10 f???? t? ?p??µa
  ?a??ste??se?? RMS,
• t?te de?
  ??e???eta? ?s?st??µ?s? ??a BER t??????st?? 10-3

• t?p???? t?µ??
• µa????????? 0.1-10 µs (worst 25 µs)
• µ?????????? 10-100 ns (worst 3 µs)
• indoor, µe???? ?t???? µe p???? µeta????? tµ?µata
  ?a? a????µata (worst 400 ns)
• indoor, µ???? ?t???? 30-60 ns (worst 250 ns)

21
?as???? pa??µet??? t?? p???d??de?s??

• s????t?s? a?t?s?s??t?s?? st?? ???? t??
  s????t?t?? s?s??t?s? µeta?? d?? s????t????
  s???st?s?? ap?stas?? ?f

s??s? t?? p??f?? ?ata??µ?? ?s???? µe t?? R(?f)

• e???? ????? s?????? µ?t?? t?? e????? s????t?t??
  ?at? t? ?p??? t? ?a???? pe??? ??e? t?? fasµat????
  s???st?se? µe pe??p?? ?s? ???d?? ?a? ??aµµ??? f?s?

• s??s? µe t? ?p??µa ?a??ste??se?? RMS

e???? ????? s??????
e???? ????? s?µat??

• frequency-nonselective (flat) fading

• frequency-selective fading gt ISI

22
? ??????? µetaßa???µe?? f?s? t?? d?a????
p???d??de?s??

• s????t?s? a?t?s?s??t?s?? st? ped?? t?? ??????
  s?s??t?s? t?? ap????s?? t?? ?a?a???? se d?? ?d?a
  ?µ?t??a µe ??????? d?af??? ?t

• ?????? s?????? µ?t?? t?? a?aµe??µe??? ??????
  ?at? t?? ?p??? ? ap????s? t?? ?a?a???? e??a?
  ??s?ast??? aµet?ß??t?

• Doppler power spectrum
  ?? f?sµa ?s???? t?? ?aµßa??µe??? s?µat?? ?ta?
  µetad?deta? ??a ?a?a?? ?µ?t??? µe s????t?ta fc
  

• Doppler spread width of the Doppler power
  spectrum

• slow fading

• fast fading

23
Type of fading w.r.t. T and B
B
T
st
Bd
B
T
24
??as??p?s? ?a?a?t???st????
?a??de??µa flat fading slow fading
condition
or
u100 km/h, fc1800 MHz gt ?17cm Bd163 Hz
(GSM B200 ?Hz) , Bd (27.7m/sec) /
(0.17m) st1.5 µs gt Bc1/(51.5µs)133 ?Hz ?
? gtgt ?d (slow fading) and ?c ? ? (tends to be
frequency selective)

• rule of thumb for insignificant ISI

?a??de??µa 2 Mbits/s gt Tbit500 ns 1
symbol4 bits gt T2000ns gt stlt200 ns