modul 8.konsep dasar seluler

8/15/2019 Modul 8.Konsep Dasar Seluler

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Modul 8 Konsep Dasar Seluler

Modul 8 - Konsep Seluler

Faculty of Electrical and Communication

Institut Teknologi Telkom

Bandung – 2012


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Subject

a. Concept of cell

b. Frequency Re-Use, Handover

d. Muti le Access : FDMA TDMA CDMA



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Klasifikasi WIRELESS

Fixed

Wireless

Non

Cellular

Cellular

point to point communication, infra

red communication, LMDS,

Microwave communication

contoh :

contoh :

PHS, CT2, PACS, DCS1800,

DECT

Communication

Mobile

Wireless

Non

Cellular

Cellular

contoh :

contoh :

paging system (ERMES, NTT, NEC)

, dispatching system, PAMR (Public

Access Mobile Radio) dsb

GSM, CDMA/IS-95, AMPS, UMTS,

PHS, DCS1800, NMT450, TACS,

C-450, dsb



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Standar Sistem Seluler

Sistem Seluler Analog – Generasi Pertama

AMPS ( Advanced Mobile Phone System )

NMT 450 ( Nordic Mobile Phone )

TACS ( Total Access Communication System )

Sistem Seluler Digital – Generasi Kedua

GSM ( Global System for Mobile Communication )

DAMPS ( Digital AMPS )

CDMA/IS-95

Generasi Ketiga

IMT 2000



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Evolution step GSM GPRS UMTS HSDPA

MSCHLR/AuCEIR

BSCBTS

PSTN

Network

SS7Network

Um

GSMINFRASTRUCTUREPCU

Node-B

RNC

Iu

IWU

Um

Edge

Edge TRX

Abis

HSDPA

HSDPA TRX

Border Gateway(BG)

ServingGPRSSupportNode(SGSN)

GatewayGPRSSupport Node(GGSN)

LawfulInterceptionGateway (LIG)

Inter-PLMNnetwork

GPRSbackbonenetwork

(IP based)Internet

GPRS

INFRASTRUCTURE

INFRASTRUCTURE



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DEFINISI.

Sistem komunikasi yang digunakan untukmemberikan layanan jasa telekomunikasi bagipelanggan bergerak.

Disebut sistem cellular karena daerah layanannyadibagi-bagi menjadi daerah yang kecil-kecil yang

disebut CELL.

SIFAT : Pelanggan mampu bergerak secara bebasdi dalam area layanan sambil berkomunikasi

tanpa terjadi pemutusan hubungan.



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CELL.

DEFINISI :

Area Cakupan (coverage area) dari Radio Base StationMacam-macam :

Omni Cell , Sectored Cell

Ukuran :

Makrocell (< 5km), Microcell (1-2km),Picocell (


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Representasi coverage sistem selular

Realitas ?

Jauh berbeda ! Grid sel teoritik digunakanuntuk mempermudah penggambaran /

perencanaan

keseluruhan daerah service tanpaoverlap dengan luas daerah yang sama



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Type of antenna that is on the BTS

1) Omnidirectional

Tx

Rx

Rx

2) Sectoring 120o

3) Sectoring 60o

Usefulness of the

pattern Sectoring

a. Adding capacityb. Reduce interference



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Type of Cell Configuration

4/17/201311

4 sector ( quad sector )



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Geometri Sel

4/17/201312Modul 8 - Konsep Seluler


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Macrocell, Microcell, dan Picocell ...

Satellite

Cell

Macrocell

4/17/201313

Indoor

Picocells

Microcell



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Mixed Cell Architecture



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What makes cellular radio work?• Frequency Reuse• Channel Sharing (trunk effect)• Handover/Handoff • High Spectral efficiency

Characteristics of Cellular Systems

er re a e cons era ons• Propagation Attenuation is like d - , 2<


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Konsepsi kluster pada CDMA…

Dalam pengertian yang sama, yangsudah kita pahami…ukuran kluster di jaringan selular CDMA, K CDMA = 1,artinya frekuensi operasi yang samaditerapkan disemua sel

Dalam pengertian yang sama, yangsudah kita pahami…ukuran kluster di jaringan selular CDMA, K CDMA = 1,artinya frekuensi operasi yang samaditerapkan disemua sel

4/17/2013 21

Tetapi CDMA memakai konsepclustering untuk perencanaan kodePN, hal ini untuk mencegah

kemungkinan terjadinya aliasingantar kode didalam satu sel. Pada jaringan CDMA, dikenal istilah PN reuse factor



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1. Frequency Re-use2. Konsep Handoff / Handover

• Konsep Frequency Re-use memungkinkan penggunaan frekuensi

yang sama pada sel yang berbeda , diluar jangkauan interferensinya.

Parameter Dasar Sistem Cellular

carrier terhadap total daya interferensinya

• Sedangkan Handoff memungkinkan seorang pengguna pindah dari

suatu sel ke sel yang lain tanpa adanya pemutusan hubungan. Terjadi pemindahan frekuensi / kanal secara otomatis yang dilakukan oleh

sistem



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Definisi

Pengulangan frekuensi yang sama pada area yang berbeda di

luar jangkauan interferensinya

F2

JARAK BEBAS INTERFERENSI

Frequency Reuse.

Reuse frekuensiF3F3

F1

1

2

3

1

2

3

1

2

3

Reuse frekuensi



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Latar Belakang Frequency Re-Use.

1. Keterbatasan alokasi frekuensi

2. Keterbatasan area cakupan cell (coverage area).

3. Menaikkan jumlah kanal.

4. Membentuk cluster yang berisi beberapa cell.

5. Co-channel interference.



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Frequnecy Reuse.

1

2

3

1

2

3

freq. reuse pattern / cluster

K= 3

1

2

3

freq. reuse pattern

K= 4

4 2

1

2

3

reuse

1 3

4

2

3

4

1reuse

reuse

reuse



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Frequensi Reuse



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Concept Cluster

• Cluster is a group of cells, each cell has 1 set of frequencies that aredifferent from other cells.

• Size of clusters (denoted = K, often denoted = N) is the number of cells

contained in 1 cluster

ontohK = 3 means there are 3 cells in 1 cluster

K = 4 means there are 4 cells in 1 cluster

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1

2

3

1

2

3

reuse

1

2

3

freq. reuse pattern / cluster

K= 3

1

2

3

req. reuse pa ern

K= 4

4

1

2

3

4

2

3

4

1reuse

reuse

reuse



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KAIDAH PENENTUAN NOMOR SEL.

i,j = 0,1,2,3, ...

sel referensi

i=1

=2z

600

i

1200



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Kaidah Penentuan Nomor Sel Kaidah Parameter Geser

i,j = 0,1,2,3, ...

Lalui sejauh i sel dari sel referensi sepanjang rantai heksagonalnya ( garis lurus yang menghubungkan dua pusat

sel), lalu berputar 60 o berlawanan dengan arah jarum jam,

kemudian lalui sepanjang j sel pada arah tersebut. Pada posisi

akhir disitulah letak freq. reuse nya.

Z

2

= i

2

+ j

2

- 2ij.cos 120

o

Z2 = i2 + 2 + 2.i. 0,5

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i=1

=2

z600

sel referensi

i

1200

Z2 = i2 + j2 + i.j

Z2 K ---- K = ukuran

cluster

K = i2 + j2 + i.j

i = 1 dan j = 1 K = 3

i = 1 dan j = 2 K = 7

i = 0 dan j = 2 K = 4

i = 2 dan j = 0 K = 4

untuk,



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21

1212

2

12

2

12 vvuuvvuuD

21

2o

1212

2o2

12 30sinuuvv30cosuuD

if, 0,0v,u 11

22

v,u integer = ( i , j )

Coordinate Systems

4/17/2013 32

then,

22 jijiD

In the next example,

65,211.22 jijiD 2222

i= 2 and j = 1



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Signal-to-Interference Ratio.

• Consider closest co-channel cells:

• Ukuran Kluster:

7

1

2

3

4

5

6

7

2

1

2

3

4

5

6

min 1 10 10

1 10

SIR log / 1 10log 7 -1 dB

= log / 1 7.78 dB

co

co

K D R

K D R

2 2

• Co-channel ReuseDistance Ratio:

1

2

3

4

5

6

1

2

3

4

5

6

7

1

2

3

4

5

6

7

1

2

3

4

5

6

7

26

7

1

3

4

2

7

2

3

Dco

R

/ 3co D R N



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1

1

1

1

2 33

32

2

Kaidah Penentuan Nomor

Sel Kaidah Parameter Geser

utk i = 1 dan j = 1 K =

3 i = 1 , j = 1

2 2

Contoh # 1 : K = 3

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1

1

12 3

2 32 3

2 3

.

Sumber interferensi

maksimum = 6.

Kluster



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Contoh # 2 : K = 4

46,3K 3Q

4 jijiK

2 j,0i

22

4/17/2013 35

Kluster



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Contoh # 3 : K = 7



58,4K 3Q

7 jijiK

2 j,1i

22

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Kluster



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Contoh # 4 : K = 12



12 jijiK

2 j,2i

22

Kluster

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6K 3Q



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Example # 5 : K = 19

55,7K 3Q

19 jijiK

2 j,3i

22

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Cluster



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Various values of K or N clusters, which may occur

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Example Cluster in GSM

K = 7

1 kluster

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Channel capacity of each cell

K

RF chchannel of number

BW

BW N

RF ch

Alokasi

• Number of channelsper cell expressed bythe following formula :

BW

1 2 3 1' 2' 3'n n' 1'' 2'' 3'' n''

4/17/2013 41

K = 3

F3F2F1

F1

F2

F3

F1

F2

F3

It can be concluded, the number

of carrier frequencies in one cell

is more than one ….



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Cell Splitting

• To increase the capacity, the operator performs cell splittings

1

0

2

1

0

0

1

P

P

R

R

C

C

before cell splitting after cell s littin

4/17/2013



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Cell Splitting.

Diperlukan pada saat :- Kepadatan trafik dalam cell meningkat.

- Kanal yang ada tidak mampu melayani.



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Performance Parameters

F1

F3 F2

Jarak 'bebas' interferensi

Sinyal yang diinginkan = C

C/I ( Carrier to Interference Ratio )

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titik A

Sinyal interferensi = I

• From the picture above, the worst case conditions exist at point A

• carrier power to interference power (C / I = Carrier to Interference)

must remain greater than or equal of the C / I the minimum required

by the relevant cellular systems



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41

R

D

N I

C

K D 3 N

K

I

C 29

AMPS, C/I = 18 dB

748,69

6.63

9

63

N

K

C/I minimum depending on the cellular system which isimplemented …

C/I minimum

4/17/2013 45

R

D

R

GSM, C/I = 12 dB

426,39

6.16

9

16

N

K

N = Number of cell interference

K = Cluster Size



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LA 1

LA 5

Location Area and Cell Identity

CI 1

CI 2CI 3

VLR MS C

LA 3LA 2

4/17/2013



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Handover

Handover adalah proses pengalihan kanal

traffic pada MS yang sedang digunakan untuk

berkomunikasi tanpa terjadinya pemutusan

hubungan



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Definition of HandOver

Handover is the process of transfer of user traffic channels at the time

of active users without termination and without intervention from theuser.

Handoff is no different except that the term handoff handover used in

the U.S., while the term handover is used in Europe.

Events hand over (HO) 'generally' occur because movement of the MS

so that out of the scope of coverage of the cell of origin and entry of .

MS movement

HO

F1

HO

F2

Sel #1 Sel #2 Sel #3

F3

F1 ke F2 F2 ke F3

4/17/2013



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Handover is a facility in celular system to guarantee

communication continously if customer move from one cellto other cell.

Handover Handover



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Flowchart Handover Process

Measurement

Decision

Eksekusi



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The basic reason for the handoff

• MS out of the scope of the BTS (RF criteria )

• To balance the network load (Network criteria)

-Received signal level is too low

- Bit error rate (BER) is too high

- Traffic in one cell is too high that some MS 'handed

over' to another cell

o e: an ar recor e reasons o an over

2 Phase handoff ...1. MONITORING PHASE

2. HANDOVER HANDLING PHASE


•Measuring the quality of the signal and 'see 'the possibility of

alternative radio link

• Initiation handoff if necessary

• Determination of the point of attachment (PoA) new

• Initiation of the possibility of re-routing procedure


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Type of HandOver :

I. Internal HandOver (Controlled by oleh BSC)

1. Intra-cell HandOver: transfer relationship to a different channel on the samesingle base station.

2. Inter-cell HandOver: the transfer relationships between different base stationsin a single BSC

Definition of ………continued

II. External HandOver (Controlled by oleh MSC)

1. Intra MSC Handover : the transfer of the relations between the BSC in a singleMSC.

2. Inter MSC Handover : displacement relationships that occur in 2 different MSC .



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Handover Types

Intra-cell

BSCBTS

f 1, TS 1

f 2, TS 2

Intra-BSS

BSC

BTS

BTS

MSC

Handover

performed

Handover erformed

GSM handover mechanism


Intra-MSC

MSC

BSS

BSS

Inter-MSC

MSC - BMSC - A

MSC - C

basic

subsequent

MSC

4/17/2013


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The basic reason for the handoff …continuation

- Often due tonarrowband

interference

- The most common case

- 2 cases: (1)-cell inter / intra-BSC, (2) inter-BSC / Intra-MSC

- BSC HO operation, assign anew channel in the cell andremove the old channels in theprevious cell

- Controlled by MSC



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The reason for the handoff ... RF criteria



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S I E M E N S S I E M E N S



MSC/VLR

Cell

Global

Identity

(CGI)

old VLR new MSC

Location

Area Id

(LAI)

LAI -> VLRISD CGI -> MSCID

BSS

BSS

BSS

Mechanism for handover


Handover Roaming

SIM

old LAI

SIM

old LAI

4/17/2013


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Mechanism for handover ...



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Mechanism for handover ...



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Measurement:

connection quality & strength:

strength of serving BTS &

surrounding BTSs

MS

Measurement:

connection quality & strength,

distance measurement (TA)

BTS

Measurement report

Timing Advance,

Power control

Measurement value processing

(averaging, limit values,..)Measurementre ort



Handover Decision

BSC

HO

decision

Evaluation list

(suitable BTSs for HO...)

Initiation of HO type

Handover BSC/

MSC4/17/2013


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BTS

BTS

BTSMSC (A)

VLR

Handover example

BSC

BSC to MSC (A):

HO please!

cell B

MSC (B)

B



BTS

BTSBTS

MSC (B)

BSC

BTS

Level:cell A

cell Bcell C

BTS

A

C

1. BSC: HO necessary

2. Parallel connection setup

3. MS changes phys. channel

4. Original connection released4/17/2013


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The steps Handover in CDMA

(1) MS is only serviced by cell A and active set consists only of pilots A. MS

measuring the pilot B (Ec / Io), acquired a tendency> T_ADD. MS sends a messagethe measured pilot B and B move from pilot status to the candidate neighbor set.

(2) the MS receives a message from cell A cell B contains the PN offset and Walsh

code allocation for the TCH and MS start communications using the TCH tsb.

(3) MS B move the pilot status of the candidate set to the active set, the MS sends a . .

(4) MS detect the pilot A fall


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Handoff Process

Ec/I 0

Active set 1 pilot A

Active set

2 pilot A & B Active set 1 pilot B

Cell-A Cell-B MS

The steps Handover in CDMA

T_ADD

T_DROP

Jarak (1)

Start T_TDROP

(2) (3) (4) (5) (6)(7)



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Soft handoff : During the handoff process of MS is connected to two or threebase stations

The same signal is sent from BS1 and BS2 within one RNC, Except Power Control

Command

BSC Soft handoff area MSC

Use Rake receiver

Down-link

BTS BTS MS



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Neighbor BTS Neighbor BTS

Soft-handoff Continuation

Serv BTS



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Softer HandOver

Sector 1

RNC

Sector 2

BS

• The same signal is sent from both sectors to an MS



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BSC

Sektor B

Softer handoff: the transfer service from one sector to another within a

single cell. The direction of down-link with soft handoff is the up-link selectionprocess occurs in the BTS .

Sektor A Sektor C

BTS



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Hard handoff

CDMA to CDMA handoff involves two carriers (can be different operators) is often called the D to D handoff . .

CDMA to Analog handoff, also called the D to A handoff.

F1

F1+n



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Maintenance set Status Active set : contains the pilots from several cells or sectors that are

actively communicating with the MS on the traffic channel. If the

active set contains only one pilot only, the MS is not in soft handoff

condition.

Candidate set : containing pilots with adequate Ec/I0

as a candidate for handoff, meaning a pilot who

> _

included as a candidate. One pilot will be moved to

neighbor set strong position if the signal falls below the pilot

T_DROP drop threshold for the duration of greater than T_TDROP

Neighbor set : contains the pilots was a neighbor of cell

serving active MS but outside the active and candidate sets

Remaining set : pilots outside of the above.



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Multiple Access

Multiple access adalah suatu teknik yang

memungkinkan satu titik (Base Station) dapat

diakses oleh beberapa titik tanpa saling

mengganggu.


Multiple Access Methods


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FDMA (Frequency Division Multiple Access): Simple, intermodulation

effect, low spectral efficiency TDMA ( Time Division Multiple Access ):higher spectral efficiency,

needs Synchronization

CDMA (Code Division Multiple Access ):higher spectral efficiency, MAI-

limited capacity, needs power control

.

F

. . . . .


F1

F2

F3

.

.

.

CH 1

CH 2

CH 3BW

F

.

T1

BW

t

. . . . .

T2 T3

C 1

Code

t

F

C 2

C 3

FDMA

TDMA

CDMA




76/85

Frequency Division Multiple Access Principles A voice channel uses the

same frequency band all

the time

– Other users must use other

frequencies



reserved for signaling

F1

F2

F3

.

.

.

CH 1

CH 2

CH 3BW

F



77/85

Time Division Multiple Access Principles

A voice channel shares thesame frequency band withother voice channels

– Each channel getsassigned to a periodic

time slot



Signaling still use adedicated frequency band

.

T1

BW

F

t

. . . . .

T2 T3



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Code Division Multiple Access (CDMA)

In CDMA, the narrowband message signal is multiplied by a very largebandwidth signal called spreading signal (code) before modulation andtransmission over the air. This is called spreading.

CDMA is also called DSSS (Direct Sequence Spread Spectrum). DSSS is amore general term.

Message consists of symbols

Has symbol period and hence, symbol rate


prea ng s gna co e cons s s o c ps Has Chip period and and hence, chip rate

Spreading signal use a pseudo-noise (PN) sequence (a pseudo-random sequence)

PN sequence is called a codeword

Each user has its own cordword

Codewords are orthogonal. (low autocorrelation)

Chip rate is oder of magnitude larger than the symbol rate. The receiver correlator distinguishes the senders signal by examining the

wideband signal with the same time-synchronized spreading code

The sent signal is recovered by despreading process at the receiver.




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CDMA Advantages

Low power spectral density. Signal is spread over a larger frequency band

Other systems suffer less from the transmitter

Interference limited operation All frequency spectrum is used

Privacy The codeword is known only between the sender and receiver. Hence other

users can not decode the messages that are in transit


Reduction of multipath affects by using a larger spectrum

Random access possible Users can start their transmission at any time

Cell capacity is not concerete fixed like in TDMA or FDMA systems.Has soft capacity

Higher capacity than TDMA and FDMA No frequency management

No equalizers needed

No guard time needed

Enables soft handoff


M lti l A CDMA


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Multiple Access CDMA

CDMA : 1 waktu, 1 frekuensi, pembeda: kode unik

yang berbeda



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Modulasi QPSK (Quadrature Phase Shift Keying)

Modulasi CDMA = QPSK

QPSK = 4 simbol, 1 simbol = 2 bit, beda fasa 450

Konstelasi :


Spreading


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Spreading

O Spreading = proses menempatkan sinyal informasi pada pita

yang lebih lebar dengan memanfaatkan kode khusus


Matriks Hadamard


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Matriks Hadamard

Berdasarkan pernyataan pada CDMA System

Engineering Hand Book , Matriks Hadamard

merupakan matriks yang berisikan +1 dan -1.

Bentuk Matriks Hadamard :


Walsh Code


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Walsh Code

Walsh Code dimanfaatkan untuk melakukan spreading

,dibentuk berdasarkan matriks hadamard

Secara grafis, spreading dilakukan dengan penerapan

operasi XOR antara urutan data informasi dengan

urutan Walsh Code

modul 8.konsep dasar seluler

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