C05-Satellite_Systems.ppt

8/16/2019 C05-Satellite_Systems.ppt

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5.1

Mobile Communications

Chapter 5: Satellite Systems

History

Basics

Localization

Handover

Routing

Systems


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5.2

History of satellite communication

1945 Artur !. !lar"e #u$lises an essay a$out %&'tra

(errestrial Relays)

195* first satellite S+,(-/

190 first reflecting communication satellite &!H

1903 first geostationary satellite S-!

1905 first commercial geostationary satellite Satellit %&arly Bird)

6-(&LSA( 78 24 du#le' tele#one cannels or 1 (cannel: 1.5 years lifetime

19*0 tree ARSA( satellites for maritime communication

19;2 first mo$ile satellite tele#one system -ARSA(1993 first digital satellite tele#one system

199; glo$al satellite systems for small mo$ile #ones


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5.3

A##lications

(raditionally

=eater satellites

radio and ( $roadcast satellites

military satellites

satellites for navigation and localization 6e.g.: >+S7

(elecommunication

glo$al tele#one connections $ac"$one for glo$al net=or"s

connections for communication in remote #laces or underdevelo#ed areas

glo$al mo$ile communication

satellite systems to e'tend cellular #one systems 6e.g.: >S or A+S7

re#laced $y fi$er o#tics


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5.4

$ase station

or gate=ay

!lassical satellite systems

nter Satellite Lin"

6SL7o$ile ,ser

Lin" 6,L7 >ate=ay Lin"

6>?L7

foot#rint

small cells

6s#ot$eams7

,ser data

+S(-S@- >S

>?L

,L

+S(-8 +u$lic S=itced

(ele#one -et=or"


5/21


6/21

5.0

Satellite #eriod and or$its

1 2 3 4 '10 m

24

2

10

12

;

4

radius

satellite

#eriod FGvelocity F '1 "mCG

synchronous distance

35,786 km


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5.*

Basics

elli#tical or circular or$its

com#lete rotation time de#ends on distance satellite


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5.9

&levation

Elevation:angle ε $et=een center of satellite $eamand surface

εminimal elevation:

elevation needed at least

to communicate =it te satellite

f o o t p r

i n t


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5.1

Lin" $udget of satellites

+arameters li"e attenuation or received #o=er determined $y four

#arameters8

sending #o=er

gain of sending antenna

distance $et=een sender

and receiver

gain of receiving antenna+ro$lems

varying strengt of received signal due to multi#at #ro#agation

interru#tions due to sado=ing of signal 6no LS7

+ossi$le solutions

Lin" argin to eliminate variations in signal strengt

satellite diversity 6usage of several visi$le satellites at te same time7

el#s to use less sending #o=er

2

4

=c

f r L

π

L8 Loss

f8 carrier freEuency

r8 distance

c8 s#eed of ligt


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5.11

Atmos#eric attenuation

&'am#le8 satellite systems at 4Hz

elevation of te satellite

5 1 2 3 4 5

Attenuation of

te signal in I

1

2

3

4

5

rain a$sor#tion

fog a$sor#tion

atmos#eric

a$sor#tion

ε


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5.12

our different ty#es of satellite or$its can $e identified de#ending

on te sa#e and diameter of te or$it8

>&8 geostationary or$it: ca. 30 "m a$ove eart surface

L& 6Lo= &art r$it78 ca. 5 < 15 "m

& 6edium &art r$it7 or ! 6ntermediate !ircular r$it78

ca. 0 < 2 "m

H& 6Higly &lli#tical r$it7 elli#tical or$its

r$its


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5.13

r$its

eart

35*0; /m1

1

L&

6>lo$alstar:

rdium7

H&

inner and outer an

Allen $elts

& 6!7

>& 6nmarsat7

an


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5.14

>eostationary satellites

r$it 35:*;0 "m distance to eart surface: or$it in eEuatorial #lane

6inclination 7

com#lete rotation e'actly one day: satellite is syncronous to eart

rotation

fi' antenna #ositions: no adJusting necessary

satellites ty#ically ave a large foot#rint 6u# to 34I of eart surfaceK7:

terefore difficult to reuse freEuencies

$ad elevations in areas =it latitude a$ove 0 due to fi'ed #osition

a$ove te eEuator

ig transmit #o=er needed

ig latency due to long distance 6ca. 2*5 ms7

not useful for glo$al coverage for small mo$ile #ones and data

transmission: ty#ically used for radio and ( transmission


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5.15

L& systems

r$it ca. 5 < 15 "m a$ove eart surface

visi$ility of a satellite ca. 1 < 4 minutes

glo$al radio coverage #ossi$le latency com#ara$le =it terrestrial long distance

connections: ca. 5 < 1 ms smaller foot#rints: $etter freEuency reuse

$ut no= andover necessary from one satellite to anoter many satellites necessary for glo$al coverage

more com#le' systems due to moving satellites

&'am#les8

ridium 6start 199;: 00 satellites7 Ban"ru#tcy in 2: deal =it ,S @o@ 6free use:saving from )deor$iting7

>lo$alstar 6start 1999: 4; satellites7 -ot many customers 6218 447: lo= stand


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5.10

& systems

r$it ca. 5 < 12 "m a$ove eart surface

com#arison =it L& systems8

slo=er moving satellites

less satellites needed

sim#ler system design

for many connections no and


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5.1*

Routing

ne solution8 inter satellite lin"s 6SL7

reduced num$er of gate=ays needed

for=ard connections or data #ac"ets =itin te satellite net=or" as

long as #ossi$le

only one u#lin" and one do=nlin" #er direction needed for te

connection of t=o mo$ile #ones

+ro$lems8 more com#le' focusing of antennas $et=een satellites

ig system com#le'ity due to moving routers

iger fuel consum#tion

tus sorter lifetime

ridium and (eledesic #lanned =it SL

ter systems use gate=ays and additionally terrestrial net=or"s


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5.1;

Localization of mo$ile stations

ecanisms similar to >S

>ate=ays maintain registers =it user data

HLR 6Home Location Register78 static user data

LR 6isitor Location Register78 6last "no=n7 location of te mo$ile station

S,R 6Satellite ,ser a##ing Register78

satellite assigned to a mo$ile station

#ositions of all satellites

Registration of mo$ile stations

Localization of te mo$ile station via te satelliteNs #osition

reEuesting user data from HLR

u#dating LR and S,R

!alling a mo$ile station localization using HLRCLR similar to >S

connection setu# using te a##ro#riate satellite


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5.19

Handover in satellite systems

Several additional situations for andover in satellite systems

com#ared to cellular terrestrial mo$ile #one net=or"s caused

$y te movement of te satellites ntra satellite andover

andover from one s#ot $eam to anoter

mo$ile station still in te foot#rint of te satellite: $ut in anoter cell

nter satellite andover

andover from one satellite to anoter satellite mo$ile station leaves te foot#rint of one satellite

>ate=ay andover

Handover from one gate=ay to anoter

mo$ile station still in te foot#rint of a satellite: $ut gate=ay leaves te

foot#rint

nter system andover

Handover from te satellite net=or" to a terrestrial cellular net=or"

mo$ile station can reac a terrestrial net=or" again =ic migt $e

cea#er: as a lo=er latency etc.


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5.2

vervie= of L&C& systems

Iridium Globalstar ICO Teledesic

# satellites 00 O 0 4; O 4 1 O 2 2;;

altitude!m" *; 1414 139 ca. *

coverae glo$al ±*H latitude glo$al glo$al

min$elevation

;H 2H 2H 4H

fre%uencies&G'(

circa")

1.0 S29.2 ↑

19.5 ↓23.3 SL

1.0 S ↑

2.5 S ↓

5.1 ↑0.9 ↓

2 S ↑

2.2 S ↓

5.2 ↑* ↓

19 ↓

2;.; ↑

02 SL

accessmethod

@AC(@A !@A @AC(@A @AC(@A

IS* yes no no yesbit rate 2.4 "$itCs 9.0 "$itCs 4.; "$itCs 04 $itCs ↓

2C04 $itCs ↑

# channels 4 2* 45 25*ifetime&years)

5


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5.21

Additional Study

Satellite Based nternet

urong Hu and . . /. Li: )Satellite

C05-Satellite_Systems.ppt

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