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7/24/2019 Module 3 Radio mobile propagation system
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Module 3Radio Propagation in Mobile
System
Presented By
Megha Das K
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Summary
Antenna basics Cellular & PCS Antennas
MIMO
Mobile Radio Propagation
1. Free space Propagation Model
2. Two Ra Model
!. Outdoor Indoor Propagation Model
". Fading C#annels
". Raleig# & Ricean $istribution
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Antenna basics
An antenna is a device used to transform an RF signal, traveling on
a conductor, into an electromagnetic wave in free space.
The antenna is the interface between the transmission line and
space
Antennas are passive devices; the power radiated cannot be greater
than the power entering from the transmitter
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Antenna basics
When speaking ofgainin an antenna, gain refers to the idea thatcertain directions are radiated better than others
Antennas are reciprocal - the same design works for receiving
sstems as for transmitting sstems
Simple Antennas ! The "sotropic Radiator would radiate all the
power delivered to it and e#uall in all directions.The isotropic
radiator would also be apoint source
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Antenna basics
Major Difference Between Antennas And Transmission Lines
transmission lineuses conductor to carr voltage $ current
radio signaltravels through air %insulator&
antennasare transducers
- convert voltage$currentinto electric$ magnetic field
- bridges transmission line $ air
- similar to speaker'microphone with acoustic energ
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Antenna basicsTypes of antennas
simple antennas! dipole, long wire
comple( antennas! additional components to
shape radiated field
provide high gain for long distances or weak signal reception
si)e fre#uenc of operation
combinations of identical antennasphased arras electricall shape and steer antenna
Transmit antenna! radiate ma(imum energ into surroundings
Receive antenna! capture ma(imum energ from surrounding radiating transmission line is technicall an antenna good transmission line * poor antenna
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Antenna basics
Transmit & Receive antennastheoreticallyare the same %e.g. radiation fields, antenna gain&
practicalimplementation issue!
transmit antenna handles high powersignal %W-MW&
- large conductors $ high power connectors,
receive antenna handleslow powersignal %mW-uW&
Antenna Performancedepends heavil on
+hannel +haracteristics! obstacles, distances temperature,
ignal Fre#uenc
Antenna imensions
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Antenna basics
Propagation Modes five types
!"# $ro%nd or S%rface wave!follow earths contour affected b natural and man-made terrain salt water forms low loss path several hundred mile range -/ 01) signal
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Antenna basics
!# Space 'ave 2ine of ight %23& wave 4round iffraction allows for greater distance Appro(imate 0a(imum istance,Din miles is
%antenna height in ft&
5o trict ignal Fre#uenc 2imitations
rxtx hh +D*
hrxhtx
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Antenna basics
!(# S)y 'aves
ionosphere
transmittedwave
reflected
wave
refractedwave
skip distance
reflected off ionosphere%6-76 miles high& large ranges possible with single hop or multi-hop transmit angle affects distance, coverage, refracted energ
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Antenna basics
(4) Satellite Waves$esigned to pass t#roug# ionosp#ere into space
uplin% ground to space'
down lin% space to ground'
Fre(uencies )) critical *re(uenc
penetrates ionosp#ere wit#out re*lection
+eosnc#ronous orbit 2!% ,iles snc#roni-ed wit# eart#sorbit'
long distancesresult in #ig# pat# loss
/M energ disperses o0er distances
intensel *ocused bea, i,pro0es e**icienc
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Antenna basics
!*# radar+
re#uires high gain antenna
sensitive low noise receiver
re#uires reflected signal from ob8ect 9 distances are doubled
onl small fraction of transmitted signal reflects back
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Antenna basics
Dipole Antennas!,ert-#+ simple, old, widel used
- root of man advance antennas
consists of spread conductors of wire transmission lines each conductor is : in length total span * < small center gap
gap
: :
Transmission
2ine
Antenna Types
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Antenna basics
M%lti.Band Dipole Antennas
Transmission2ine
='>+
2
+
2
='>
'>'>
use = antennasupport several widel separated fre#uenc bands
e.g.HAM Radio - 3!"MH#-$%MH#
Traps+&,' elements inserted into dipole arms
arms appear to have different lengths at different fre#uencies traps must be suitable for outdoor use ndraffects of trap impact effective dipole arm length-ad8ustable not useful over /601)
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Antenna basics
/lementary Antennas low cost 9 fle(ible solutions
Long 'ire Antenna effective wideband antenna
length l * several wavelengths
- used for signals with 6.=l? ? 6.7l
- fre#uenc span * 7!=
drawback for band limited sstems - unavoidable interference
near end driven b ungrounded transmitter output
far end terminated b resistor
- tpicall several hundred $ impedance matched to antenna @
transmitter electrical circuit ground connected to earth
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Antenna basics
0olded Dipole Antenna- basic dipole folded to form complete circuit
- core to man advanced antennas
- mechanicall more rugged than dipole
- =6 more bandwidth than dipole
- input impedance B
- close match to std /66twin lead wire transmission line
- use of different diameter upper $ lower arms
allowsvariable impedance
'
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Antenna basics
Loop & Patch Antenna9 wire bent into loops
Patch Antenna! rectangular conducting area with CC ground plane
Area A
5-turns
(* ma(imum voltage induced in receiver b D0 field
E* magnetic field strength flu( of D0 field
A* area of loop
5* number of turns
f* signal fre#uenc
k* phsical proportionalit factor
(* k%f&)A5Antenna
lane
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Antenna basicsAntenna Types
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Antenna basics
**1"2 dBDipole
(344 dB
5sotropic
Beamwidth
.( dB
$ain !over
isotropic#
Shape6ame Radiation Pattern
4
(4
*4
44
*
"217 dB
"41" dB
.4183 dB
(1"2 dB
71"2 dB
Para9olic
Dipole
,elical
T%rnstile
0%ll 'ave
Loop
:agi
Biconical
,orn
"*"* dB,orn
(34;44"2 dB
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Cellular &
PCS Antennas
Analog cellular on the G76 01) band ince =BHB %e(perimental&, =BG= commercial; analog F0 now mostl phased
out
igital +ellular'+ on G76 and =B66 01) bands
ince I=BB= with immense growth rate stems on the =.B 41) %=B66 01)& band
Jsuall called ersonal +ommunications stems even when technologicall identical to G76 01) sstems %such as "-B7 +0A
or "-=/K T0A&
B66 01) and =.G 41) bands used in Durope and other continents,mainl for 40 %4lobal stem for 0obile communication&
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Cellular & PCS Antennas
Technicall, a cellular sstem has properties! +ellular fre#uenc re-use
1andover %also called handoff&
o do most personal communications sstems %+s& onl e(ception is +T- public cordless %current implementations& without handover
Toda the 5orth American business distinction is sometimesbased on fre#uenc band... G76'B66 01) is described as cellular
including digital cellular such as 40, "-7>, "-=/K
=.B 41) is described as*'+
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Cellular & PCS Antennas
0anual operator-handled mobile radio %=B>7L&
Automatic 0obile Radio, e.g. ecode, "0T %=BK6L&
Trunked radio %=BK6L& cellular-like fre#uenc re-use
but no handoverM
+ellular radio %=BHGL& re#uired new technolog! control of mobile radio operation via messages from base
0obile transmit %T(& fre#uenc and power
+an be changed duringa conversation to select best base station orcompensate for distance
Handovercontinues conversation as mobile station moves from cell tocell
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Cellular & PCS AntennasCellular Frequency Re-use
+ertain tpes of radio modulation e(hibit the Ncapture effectO
When ratio of desired signal power to undesired %interference $noise& power is greater than the Ncapture ratio,O onl the strongerdesired signal is apparent in the output
+apture phenomenon works for +ertain tpes of modulation! F0, hase 0odulation -- but.A0
Eandwidth of signal is tpicall large compared to data rate for auseful capture ratio!
Analog cellular /6 k1)! c.r. is K/'= or =G dE
5arrow band 5A0 =6 k1)! c.r. is 66'= or / dE
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Cellular & PCS AntennasCellular Frequency Plan
Fre#uenc plan depends on capture ratio resulting from RF technolog
Radio signal strength, path loss or distance-related attenuation
Appro(imatel! received power *='distance>in cit /mpirical approximation< not 9ased on theory
D(ponent in range %open space& to > %cluttered urban
environment&
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A fre#uenc plan is characteri)ed b a cell cluster count in
which each fre#uenc is used in one cell
2ow capture ratio, high path loss re#uires small cell cluster %/
or >&
1igh capture ratio, low path loss re#uires large cluster %H or =
or more&
Cellular & PCS AntennasCellular Frequency Plan
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Cellular & PCS Antennas
Frequency Clusters
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Cellular & PCS AntennasCell Splitting
"ncrease of capacit b H in center cell %for n*H plan&
Eut there is a lower limit on cell si)e %due to appro(. min. 7 mWhandset T( power& so ou canPt split again and again withoutlimitation
+ell splitting is the most costl choice, used onl after first usingmethods which add capacit to an e(isting cell site
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Cellular & PCS AntennasGeneral PCS System Structure
O**icial bloc% diagra, *ro, +SM' s#owing ,a3or de*ined inter*aces4.
0
0+
E+ ET
E+ ET
E+
ET
ET
A
A-bis
Jm
12R Q2R
Au+
D"R
30+
to T5
to other 0+s
Q2R
4
E
D
+
F
econd Q2R is optional
E
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VR !ata "ase
0isleading name- NQisitedO 2ocation Register
ata needed to communicate with a 0 D#uipment identit and authentication-related data
2ast known 2ocation Area %2A& group of cellsS
ower +lass, other phsical attributes of 0
2ist of special services available to this subscriber e.g. circuit-switched FA, etc.S
0ore data entered while engaged in a +all +urrent cell
Dncrption kes
etc.
Cellular & PCS Antennas
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#R !ata "ase
1ome 2ocation Register 5eed not be part of the 0+
3ne 12R can be shared b several 0+s ome operators plan a single regional 12R for shared use b several 0+s
+ontains NeverthingO permanent about the customer
"0", "0D", irector 5umber, classes of service, etc. +urrent cit and 2A
particularl when not in home sstem %when NroamingO&
Authentication related information
"n some implementations 12R and Q2R are thesamephsical
data base Q2R records distinguished logicall via Nactive in Q2RO bits
Cellular & PCS Antennas
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"ase Station Assembly
Antennas Transmit +ombiner rocessing
Receive 0ulti-coupler'2ow 5oise istribution Amplifier
Ease Transceiver
Transmitter ection Receiver ection
Antenna iversit rocessing in Receiver
Ease tation +ontroller
upport e#uipment! power, air conditioning,
Cellular & PCS Antennas
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"ase Station $quipment
5ot shown! band pass or band re8ect filters in antenna lines, power e#uipment, air-
conditioning, test transceiver, alarm e#uipment, etc.
T(
ant.
E+
ET
A-bis
ET6
ET=
ETn
111
A
first
R(
ant.second
R(
ant.
T(
+ombiner
R(
multi-
coupler
R(
multi-
coupler
E+F
ETwo standardi-ed interfaces !A and A9is in $SM# permit competitive s%ppliers for 9ase e=%ipment
Cellular & PCS Antennas
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%nside te "o'es
Transmit +ombiner contains Tunable resonant cavit filters irectional couplers
"ts purpose! feed mostT( power to T( antenna, notto other
transmitters %where the signal power does no good and maeven cause overheating or damage&
Receive multi-coupler is RF low-noise pre-amplifier similar to TQ communit antenna distribution sstem
distributes R( signal to all receivers at same level the would get froman unshared R( antenna
Cellular & PCS Antennas
C ll l & PCS A t
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(y ) "ase R' Antennas*
ual antennas diversit improves base reception sensitivit b asmuch as to 7 dE vis-U-vis a single antenna
pacing of antennas should be oddmultiple of l'>, preferabl
VGl apart
everal methods for diversit combining! witching'selection
D#ual gain
0a(imal ratio
vendor design choice, not standardi)ed
Cellular & PCS Antennas
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(y +#F "ands*
NEecause the are availableO is a legal'historical reason onl,although ver significant... Q1F and below, absolutel no available bandsM
Former point-point microwave and militar bands were made available around 41)band
till some incumbent microwave sstems
4overnment auctioned bands to highest bidder in =BB6s trong financial motive to move #uickl
Technological reasons! J1F follows Nline of sightO propagation
2ittle'no over-hori)on or NskipO radio propagation
0F, 1F short-wave bands would be impractical for cellular 1F bands re#uire much more costl components, and some bands are used for
e(tensive installed microwave or have strong atmospheric attenuation
Cellular & PCS Antennas
Cellular & PCS Antennas
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,ort American ./ M#0 "and Cellular
Spectrum
3riginal /6 k1) carriers =-KKK assigned =BG= Additional carriers assigned =BGH 5o more carriers likel until after ear 666 3perator optional additional "-=/K setup carriers in middle of AP and EP sub-
bands. 3rdinaril used for voice "-=/K allows an fre#uenc to be used for T0A setup carrier "-B7 uses =6 NchunksO each =.7 01) bandwidth
Paired Bands
ownlink- Forward ub-bandJplink-Reverse sub-band 0R band
G>
01)
G>B
01)
GKB
01)GB>
01)
G7
01)
G/7
01)G>7
01)
G>K.7
01)
GB6
01)GB=.7
01)
GG6
01)
GH6
01)
A>> A A> B>B
".(((??".
"4(
337.
7"3
7"7.
7??((2.333
A>> A A> B>B
".(((??".
"4(
337.
7"3
7"7.
7??((2.333
Set%p.control carriers !" each operator#
Speciali-ed
Mo9ile Radio
%se
Cellular & PCS Antennas
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,ort American 12// M#0 "and PCS Spectrum
i Elocks A $ E are for use in 0etropolitan Trading Areas %0TAs&
i Elocks +, , D $ F for use in Easic Trading Areas %ETAs& suburban or ruralS
i "n an service area, >6 01) block combinations are permitted
i +ellular operators are eligible for onl one =6 01) block in their e(isting
services areas
0@@ P@S Spectr%m Allocation . %ne ?< "??2
=GG7
01)
ata Qoice
Paired Bands
2icensed ownlink2icensed Jplink Jnlicensed
0TAE
T
A0TA
E
T
A
E
T
AETA
A E D F +
0TAE
T
A0TA
E
T
A
E
T
AETA
A E D F +
=G76
01)
=B=6
01)
=B/6
01)
=BB6
01)
=GK7
01)
=GH6
01)
=GB6
01)
=GB7
01)
=B6
01)=BK7
01)
=BH6
01)
=BH7
01)
=B76
01)=B>7
01)
Cellular & PCS Antennas
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M%M
"n radio, m%ltiple.inp%t and m%ltiple.o%tp%t,or M5M%pronounced as Xm-mohX or Xme-mohX&, is a method for
multipling the capacit of a radio link using multiple transmit and
receive antennas to e(ploit multipath propagation
0"03 has become an essential element of wireless communication
standards including Wi-Fi,/4$>4.
0ore recentl, 0"03 has been applied to power-linecommunication for /-wire installations as part of "TJ 4.hn standard
and 1omelug AQ specification.
M%M
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Aspirations 4Matematical5 o6 a System
!esigner
5ig# data rate
Yualit
Achieve
N+hannel +apacit %+&O
0inimi)e robabilit of Drror %e&
Real-life "ssues
0inimi)e comple(it'cost of
implementation of proposed
stem
0inimi)e transmission power
re#uired %translates into 5R&
0inimi)e Eandwidth %fre#uenc
spectrum& Jsed
M%M
M%M
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Antenna Con6igurations
Single6Input6Single6Output SISO' antenna sste,
Theoreticall, the =4bps barrier can be achieved using this configuration
if ou are allowed to use much power and as much EW as ou so pleaseM
D(tensive research has been done on "3 under power and EW
constraints. A combination a smart modulation, coding and multiple(ingtechni#ues have ielded good results but far from the =4bps barrier
channel
Cser data stream
Cser data stream
M%M
M%M
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M%M Antenna Con6iguration
Cser data streamCser data stream
1
1
"
MT
1
1
1
"
MR
1
1
1
1
1
channel
7se ,ultiple trans,it and ,ultiple recei0e antennas *or a
single user
5ow this sstem promises enormous data ratesM
M%M
M%M
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!ata +nits
Will use the following terms loosel and interchangeabl,
Eits %lowest level&!
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Sannon7s Capacity 4C5
4iven a unit of EW %1)&, the ma( error-free transmission rate is+ * log%=
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Spectral $66iciency
pectral efficiencies of some widel used modulation schemes
The Whole point! 4iven an acceptable e , realistic power and EWlimits, 0"03 stems using smart modulation schemes provide
much higher spectral efficiencies than traditional "3
Sc#e,e b8s85-
9PS: 1
;PS: 2
1
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M%M System Model
Cser data stream
1
1
Cser data stream
1
1
1
1@hannel
Matri; ,
s=
s
s0
s
=
0
yTransmitted
vector
Received
vector
1
1
h=
= h=
M%M
M%M
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M%M System Model
y* ,s< n
Where ,*
h== h= LL.. h0=
h= h LL.. h0
h=0 h0 LL.. h00. . LL.. .
0T
0R
hij is a @omple; $a%ssian random varia9le
that models fading gain 9etween the ith
transmit and jth receive antenna
M%M
M%M
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Capacity o6 M%M Cannelsy ,s E n
Let the transmitted vector s 9e a random vector to 9e very general and n is normali-ed noise1 Let the totaltransmitted power availa9le per sym9ol period 9e P1 Then