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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
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4 sector ( quad sector )
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Geometri Sel
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Macrocell, Microcell, dan Picocell ...
Satellite
Cell
Macrocell
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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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Kaidah Penentuan Nomor
Sel Kaidah Parameter Geser
Contoh # 2 : K = 4
46,3K 3Q
4 jijiK
2 j,0i
22
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Kluster
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Contoh # 3 : K = 7
Kaidah Penentuan Nomor
Sel Kaidah Parameter Geser
58,4K 3Q
7 jijiK
2 j,1i
22
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Kluster
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Contoh # 4 : K = 12
Kaidah Penentuan Nomor
Sel Kaidah Parameter Geser
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''
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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
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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
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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
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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
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•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
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Intra-MSC
MSC
BSS
BSS
Inter-MSC
MSC - BMSC - A
MSC - C
basic
subsequent
MSC
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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
S I E M E N S S I E M E N S
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
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Handover Roaming
SIM
old LAI
SIM
old LAI
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Mechanism for handover ...
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Mechanism for handover ...
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GSM handover mechanism
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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
GSM handover mechanism
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Handover Decision
BSC
HO
decision
Evaluation list
(suitable BTSs for HO...)
Initiation of HO type
Handover BSC/
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BTS
BTS
BTSMSC (A)
VLR
Handover example
BSC
BSC to MSC (A):
HO please!
cell B
MSC (B)
B
GSM handover mechanism
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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.
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Multiple Access Methods
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Multiple Access Methods
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Multiple Access Methods
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Multiple Access Methods
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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
. . . . .
Multiple Access Methods
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
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Multiple Access Methods
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Frequency Division Multiple Access Principles A voice channel uses the
same frequency band all
the time
– Other users must use other
frequencies
Multiple Access Methods
Modul 8 - Konsep Seluler
reserved for signaling
F1
F2
F3
.
.
.
CH 1
CH 2
CH 3BW
F
Multiple Access Methods
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Time Division Multiple Access Principles
A voice channel shares thesame frequency band withother voice channels
– Each channel getsassigned to a periodic
time slot
Multiple Access Methods
Modul 8 - Konsep Seluler
Signaling still use adedicated frequency band
.
T1
BW
F
t
. . . . .
T2 T3
Multiple Access Methods
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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
Multiple Access Methods
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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Multiple Access Methods
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Multiple Access Methods
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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
Multiple Access Methods
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
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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 :
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Spreading
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Spreading
O Spreading = proses menempatkan sinyal informasi pada pita
yang lebih lebar dengan memanfaatkan kode khusus
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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 :
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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