interleave division multiple access (idma)

8/18/2019 Interleave Division Multiple Access (Idma)

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Outlines…

What is Multiple Access & Why?

Review Of Multiple Access

What is CDMA?

Disadvantage of CDMA

IDMA introduction

Interleaving principle

!ypes of Interleaver

IDMA "tructure

IDMA #s CDMA

$eatures of IDMA

$uture %nhanceent

References


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M'(!I)(% ACC%""*MA+

General wireless cellular systems are multi-users

systems.

Multiple access techniques are used to allow a large

number of mobile users to share the allocated

spectrum in the most efficient manner.

Following multiple access techniques are using this

approaches –

1. FDMA

. !DMA

". #DMA


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$R%,'%-C. DI#I"IO- M'(!I)(% ACC%""

$n FDMA entire band of frequency is di%idedinto number of &F channel.

$ndi%idual channel are assign to indi%idual user

and each user is allocated a unique frequency

band or channel.


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!IM% DI#I"IO- M'(!I)(% ACC%""

$n !DMA 'ystem di%ide the radio spectrum into

time slots and in one slot only one user is

allocated to transmit or recei%e.


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COD% DI#I"IO- M'(!I)(% ACC%""

#DMA is a method in which users occupy thesame time and frequency allocations( and are

channeli)ed by unique assigned codes.

*arrowband message signal multiplied by

wideband spreading signal( or code word.#DMA is a spread spectrum.


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CDMA !RA-"MI!!%R


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/%-%RA!IO- O$ ")R%ADI-/ "%,'%-C%

Following technique to be used for the

spreading sequence generation.

+F'&

,A+' #D/


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(I-%AR $%%D0AC1 "2I$! R%/I"!%R


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WA("2 COD%


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DI"AD#A-!A/%" O$ CDMA

!he performance is mainly limited by multipleaccess interference 0MA$ and inter symbolinterference 0$'$.

2rocessing gain is reduced considerably withincrement in users per sector.

!he comple3ity of decoder increases withincrement in user count

&equirement of %ery precise power control(

powerful multi-user detection( requirement of&A4/ recei%er( and costly sectori)ed antennas(

becomes highly desirable


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I-!%R(%A#% DI#I"IO- M'(!I)(%

ACC%""*IDMA+

$t is a multiple access technique in which

$nterlea%er are used as the only means of user

separation.


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I-!%R(%A#I-/

$nterlea%ing is a process of rearranging theordering of a data sequence in a one to one

deterministic format.

$nterlea%ing is the only means to separate the

layers6users.


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I-!%R(%A#I-/ )RI-CI)(%

+et #7 8c9( c1 (...... c*-1 : be a sequence of length *.

An interlea%er maps # onto a sequence such that ; is a

permutation of the elements of #.

#onsidering # and ; as a pair of *-dimensional %ectors(there is one-to-one correspondence between each

element of # and each element of ;( as shown in Figure


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!.)%" O$ I-!%R(%A#%R"

&andom $nterlea%ers

Master &andom $nterlea%ers

!ree


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COM)ARI"O- O$ I-!%R(%A#%R


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IDMA "C2%M% !RA-"MI!!%R


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IDMA #" CDMA "C2%M%


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$%A!'R%" O$ IDMA "C2%M%

+ow recei%er cost(

'imple treatment of $'$(

#ross-cell interference mitigation(

Di%ersity against fading(

igh power efficiency

igh spectral efficiency


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$'!'R% %-2A-C%M%-!

$dma scheme used not only in cellular

communication but also in under water

communication.

$dma is fourth generation0=g research. 'ome more

researches are under process for ma5ing the data

transmission efficient.

pen the new path for future optical communication

with idma scheme incorporated with tree based

interlea%ers.


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Thank YouThank You

interleave division multiple access (idma)

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