Modul 7 Konsep Dasar Multiple Antena · – high data rate transmission – high mobility – High...

Modul 7 Konsep Dasar Multiple Antena

Modul 7 Multiple Antenna

Faculty of Electrical Engineering

Bandung – 2015

Wireless Communication System

Subject

a. Macam-macam Multiple Antenna (Diversitas dan

MIMO)

b. Model Sistem SISO, SIMO, MISO, MIMO


01

Text Book


02


03


04

Rina P. Astuti6

Multiple Antenna vs Fading05


06

Diversity & MIMO


07


0808


09


10

Multiple Antenna Technique: Four Basic Model


11


12

SISO


Radio transmissions traditionally use one antenna at

the transmitter and one antenna at the receiver.

This system is termed Single Input Single Output

(SISO).

Picture. Single Input Single Output

(SISO)

One antenna at both the transmitter

and the receiver.

Employs no diversity technique.

Both the transmitter and the receiver

have one RF chain (that's coder and

modulator). SISO is relatively simple

and cheap to implement and it has

been used age long since the birth of

radio technology.

It is used in radio and TV broadcast

and our personal wireless

technologies (e.g. Wi-Fi and

Bluetooth).

13

SIMO


To improve performance, a multiple antenna technique has been developed.

A system which uses a single antenna at the transmitter and multiple

antennas at the receiver is named Single Input Multiple Output (SIMO). The

receiver can either choose the best antenna to receive a stronger signal or

combine signals from all antennas in such a way that maximizes SNR

(Signal to Noise Ratio). The first technique is known as switched diversity or

selection diversity. The latter is known as maximal ratio combining (MRC).

Picture. Single Input Multiple Output (SIMO), 1x2

One antenna at the transmitter, two antennas the receiver.

Employs a receive diversity technique.

14

MISO


A system which uses multiple antennas at the transmitter and a

single antenna at the receiver is named Multiple Input Single

Output (MISO). A technique known as Alamouti STC (Space

Time Coding) is employed at the transmitter with two antennas.

STC allows the transmitter to transmit signals (information)

both in time and space, meaning the information is transmitted

by two antennas at two different times consecutively.

Picture. Multiple Input Single Output (MISO), 2x1

Two antennas at the transmitter, one antenna at the receiver.

Employs a transmit diversity technique.

14

MIMO


To multiply throughput of a radio link, multiple antennas (and multiple

RF chains accordingly) are put at both the transmitter and the receiver.

This system is referred to as Multiple Input Multiple Output (MIMO).

A MIMO system with similar count of antennas at both the transmitter

and the receiver in a point-to-point (PTP) link is able to multiply the

system throughput linearly with every additional antenna. For

example, a 2x2 MIMO will double the throughput.

Picture. Multiple Input Multiple Output (MIMO), 2x2

Two antennas at both the transmitter and the receiver.

16


17

Rina P. Astuti

18

19

Objective : to support private and public access

– high data rate transmission

– high mobility

– High signal performance

New transmission

techniques

Selective fading

Costly to estimate

the channel accurately

Performance degradation

Multi users

ProblemsMultiple antennas & multi-carrier techniques

Non coherent transmission scheme

Coding techniques

Multiple access

OFDM, Coded OFDM, OFCDM, MC-CDMA

Differential modulation

outer & inner codingFDMA, TDMA, CDMA

Examples :

Modern Wireless Transceiver


19

21

Data

Source

Estimated

Data

Channel

Decoder

Channel

Encoder

SymbolsT

MC

t,1s,....,1,1s

t,2s,....,1,2s

h11

h12

h22

h21 TX Antenna 2

AWGN NoiseAWGN Noise

t,2r,....,1,2r

t,1r,....,1,1r

RX Antenna 1

RX Antenna 2

Localized Noise

symbolsC tc,....,1c tb,....,1b

Outer Coding

Inner Coding SymbolsT

MC

TX Antenna 1Constellation/Mapper

Demapper

Space Time Encoder

Space Time Decoder

Channel &

Noise

Covariance

Estimator

tb,....,1b ˆˆ tc,....,1c ˆˆ t,1s,....,1,1s ˆˆ

t,2s,....,1,2s ˆˆsymbolsC

Outer Decoding

Inner Decoding

Modulator

CHANNEL

Data

Source

Estimated

Data

Channel

Decoder

Channel

Encoder

Demodulator

Modulator

Fading

Channel

AWGN Noise

tb,....,1b tc,....,1c

Signal

tb,....,1b ˆˆ tc,....,1c ˆˆ

Signal

CHANNEL

Rina Pudji Astuti

20

Innovation of Wireless Systems


21

What is MIMO ?


22

Required Knowledge


23


24


25


26

MIMO Operation


27


28

Macam-2 Teknik Space Time

Teknik Space Time

(MIMO)

Memaksimalkan

Diversitas

Memaksimalkan

Laju Data

Space Time

Block Codes

Space Time

Trellis Codes

Layered ST

architecture

Threaded ST

architecture

Other Inner

code

performance-rate complexity tradeoffs

Rina Pudji Astuti

29

Multiple Antenna Technique

Two popular techniques in MIMO wireless systems:

Spatial Diversity: Increased SNR

• Receive and transmit diversity mitigates

fading and improves link quality

Spatial Multiplexing: Increased rate

• Spatial multiplexing yields substantial

increase spectral efficiency


30

Spatial Diversity and Spatial Multiplexing

Spatial Diversity

– Signal copies are transferred from multiple antennas or

received at more than one antenna

– redundancy is provided by employing an array of

antennas, with a minimum separation of λ/2 between

neighbouring antennas

Spatial Multiplexing

– the system is able to carry more than one data stream

over one frequency, simultaneously

31

33

Spatial MultiplexingMaximize Data Rate (rate oriented)

• MIMO dengan Skema Vertical Encoding

• MIMO dengan Skema Horizontal Encoding

4:1

Demux

Code / mod

Code / mod

Code / mod

Code / mod

1

2

3

4

t1S

t3S

t4S

t2S

Primitive data

Stream

AntennasSpace

4LAYER

1LAYER

2LAYER

3LAYER

4-D vector symbols duration

( Antenna )

Time

1

2

4

3

Temporal Code +

Interleaving +

Symbol Mapper Demultiplex

TM:1

SymbolsT

MC

SymbolsT

MC

TMTMC

symbolsCbitsq

32

Rina Pudji Astuti34

• MIMO dengan Skema Diagonal Encoding

4:1

Demux

Code / mod layer A

Code / mod layer B

Code / mod layer C

Code / mod layer D

1

2

3

4

Primitive data

Stream

AntennasSpace

4LAYER

1LAYER

2LAYER

3LAYER

4-D vector symbols duration

( Antenna )

Layer A

Layer A

Layer A

Layer A

Layer A

Layer D

Layer D

Layer D

Layer D

Layer C

Layer C

Layer C

Layer B

Layer B

Layer A

Layer A

Layer A

Layer A

Layer ALayer D

Layer D

Layer B

Layer C

Layer C

Layer C

Layer B

Layer B

Layer B

Time

1

2

4

3

Spatial Multiplexing33


MIMO channels can be decomposed into a number of R parallel

independent channels → Multiplexing Gain

– Principle: Transmit independent data signals from different antennas to

increase the throughput, capacity.

Source: An Overview of MIMO Systems in Wireless Communications

www.iet.ntnu.no/projects/beats/Documents/mimo.pdf

34



Spatial multiplexing bertujuan untuk meningkatkan kapasitas dengan

cara mengirimkan beberapa aliran data secara paralel pada waktu yang

bersamaan.

Prinsip kerja dari spatial multiplexing adalah mengirim sinyal dari

dua atau lebih antenna yang berbeda dengan beberapa aliran data dan

aliran data dipisahkan dipenerima dengan proses signal processing,

oleh karena itu peningkatan bit rate berdasarkan konfigurasi antenna

mimo ( 2 untuk antenna mimo 2 by 2 and 4 untuk antena mimo 4 by 4)

35


MIMO Multiplexing

Data is not redundant – less diversity but less repetition

Provides multiplexing gain to increase data-rate

Low (no) diversity compared with STC


36

38

Maximize Diversity Transmission Scheme

(performance oriented) in MIMO Wireless Systems

Transceiver

System

Coherent Ch. Scheme

Non Coherent Ch

Scheme

Traditional Inner

Coding

Differential Modulation

Differential Inner

Coding

Transmission

Scheme

Channel State

Information

with channel

estimation

scheme

With or Non

Channel State

Information

with

differential

modulation

e.g. Space time

block code, STTC

Unitary code, etc

e.g. D-STBC,

D-Unitary code,

DUSTF code,

MC-CDMA Multilevel

Coding etc

OFDM

Coded OFDM

MC CDMA

Multicarrier

Techniques

Rina Pudji Astuti

37

Spatial Diversity

Improves the signal quality and achieves a higher SNR at the receiver-

side

Principle of diversity relies on the transmission of structured

redundancy

xiyi

38

Spatial Diversity


Beberapa replika sinyal informasi dikirim dari beberapa antenna

yang berbeda (data informasi yang dikirim yaitu data info asli dan

replika). Tujuan spatial diversity yaitu untuk meningkatkan SNR

dengan cara mengurangi fading dan meningkatkan kualitas link antara

pengirim dengan penerima.

39


40

Rina P. Astuti42

• Space Time Block Code (STBC) [Alamouti1998]

– At the Receivers, after demodulator :

dual diversity

Combiner

Estimate

Antena

Pemancar

(Jamak)

*

2C,1C

*

1C,2C

*

2C,1C h

h 2C,1C

~~

2h,1h~~

ncHy . 21 yyy

Tcc ][ 21c

12

21

hh

hhH

2

1

12

21

21 ]~~[y

y

hh

hhcc

'2

'1

2212

2

2

2

122111

2

2

2

1

nn

nhnhchhnhnhchh

2

2

2

1 hhg

Space Time Coding

virtual MIMO matrix

41

Rina P. Astuti

43

Space Time Coding

• Space Time Block Code (STBC) [Tarokh1999]

• Alamouti Model, 2 Tx antennas and 2 Rx

• At the Receivers, after demodulator :

• Quadruple diversity

4

3

34

43

2

1

12

21

21

~~

y

y

hh

hh

y

y

hh

hhcc

1

443322111

2

4

2

3

2

2

2

1

n

nhnhnhnhchhhh

2

443312212

2

4

2

3

2

2

2

1

n

nhnhnhnhchhhh

'.~ ng cc

2

4

2

3

2

2

2

1 hhhhg

42

• Space Time Trellis Code (STTC) [Tarokh1998]

– 2 – space time code, 4 PSK, 4 – state, 2 b/s/Hz

Deretan bit masukan

Derajat memory: dan , dengan , sehingga jumlah state

Pasangan koefisien pengkode:

dimana.

KeluaranSTTC: dengan

0

2

1

3

10 11 12 13

20 21 22 23

30 31 32 33

00 01 02 03 Input : 02321103

Tx1 : 00232110

Tx2 : 0232110302

1

3

Space Time Coding

,,,,1111

kkk dddd ,,,,2222

kkk dddd

,

.

1v2v 21 vvv 42 v

1

2,

1

1,

1

2,1

1

1,1

1

2,0

1

1,0

1

11,,,,, vv gggggg g

2

2,

2

1,

2

2,1

2

1,1

2

2,0

2

1,0

2

11,,,,, vv gggggg g 3,2,1,0,

j

lig

4mod)(2

1 0

,

j

v

i

j

ik

j

lil

j

dgks 2,1l

Rina P. Astuti

43

Space Time Coding

Aliran bit masukan, d : merupakan masukan sebuah modulasi M-PSK yang difungsikan sebagai pemeta simbol(mapper), dimana

Pengkode STTC yang terdiri dari m feedforward shift register akan memetakan deretan bit masukan menjadi himpunan sinyal M-PSK.

Deretan bit masukan ke k, dimasukkan ke shift register ke k dan dikalikan dengan sebuah himpunan koefisien pengkode, berupa himpunan konstelasi M-PSK. Keluaran pengkode pada saat k, berupa sinyal-sinyal termodulasi membentuk simbol berbasis ruang-waktu (space time symbol), dapat dinyatakan sebagai berikut:

,,,, 10 kdddd

Tm

kkkk ddd ,,,21 d

TMk ksksks

T)(,),(),( 11 s

Mdgksm

j

v

i

j

ik

j

lil

j

mod)(1 0

,

TM

j

lig ,

kv

kv

adalah jumlah antena pemancar

adalah elemen himpunan konstelasi M-PSK

adalah derajat memori shift register ke kRina P. Astuti

44

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