Simulation - CAUcomm.cau.ac.kr/board/data/17_1/Mobile_Comm_Simulation_2017.pdf · – BER (compare with analytic BER curve, Use square root raised cosine filter) ... 16 QAM 4 4 8

Mobile Communications

Chung-Ang University

Mobile Communication Lab

Cho, Yong Soo

Mobile CommunicationSimulation


Cho, Yong Soo



Simulink 6

Start Simulink

Start MATLAB

>> simulink or

Click “Simulink library browser icon


Cho, Yong Soo



Create a new model

Click blank paper icon

New empty model

Simulink 6

Finder tool for

searching models

hierarchical

sub-blocks

Predefined

blocksets


Cho, Yong Soo



Find a block

Type the name of the block in the search window Enter

Ex) display

Or Find the block in blocksets library

Move the block to the desired place

Drag & Drop

or

Right click add to ‘model name’

Simulink 6


Cho, Yong Soo



Simulink 6

Connect each block

Drag & drop from |> to >|

Or Click each block while pressing < Ctrl >

Disconnect block

Click the line and < Delete > or <Ctrl+ X>

Moving block

Drag & drop the block

Flip, Rotate block

Short Key: Flip block <Ctrl+I>, Rotate block <Ctrl+R>

Format

Sample time colors: Show the blocks in the same time with the same color

Signal dimensions: Show dimension of signal

Port data type: Show variable type of output

Simulation

Simulation start <Ctrl+T> Simulation run


Cho, Yong Soo



Simulation Assignment 1 (1)

Simulation Assignment (Block Level)

Raised-cosine pulse spectrum

Plot time / frequency response

Change the value of roll-off factor (0, 0.5, 1)

Eye diagram

Understand how to generate eye diagram

Plot eye diagram

Transversal filter

Plot output signal of transmit filter / eye diagram

Plot output signal of channel / eye diagram

Plot output signal of 3-tap zero forcing equalizer / eye diagram

Plot output signal of 5-tap zero forcing equalizer / eye diagram


Cho, Yong Soo




Raised cosine transmit filter

Filter type : Square root / Normal

Group delay : 4 symbols

Roll-off factor : 0~1

Up sampling : 8

Rolloff factor : 1

Rolloff factor : 0.25

Impulse


Cho, Yong Soo




Eye diagram

Random (1,0) (+1,-1)


Cho, Yong Soo


Chung-Ang University8

Simulation Assignment 1(4)


Cho, Yong Soo





Cho, Yong Soo





Cho, Yong Soo




Transversal filter

Time

Vector

Scope4

Time

Vector

Scope3Time

Vector

Scope2

Time

Vector

Scope1

Unipolar to

Bipolar

Converter

Unipolar to

Bipolar

Converter

In1 Out1

Subsystem

Random

Integer

Random Integer

Generator

Normal

Raised Cosine

Transmit Filter3

Normal

Raised Cosine

Filter

Normal

Raised Cosine

Filter2

Normal

Raised Cosine

Filter1

Discrete-Time

Eye Diagram

Scope3

Discrete-Time

Eye Diagram

Scope2

Discrete-Time

Eye Diagram

Scope1

Discrete-Time

Eye Diagram

Scope

In1 Out1

5Tap EQ

In1 Out1

3Tap EQ


Cho, Yong Soo




Transmit data

4-ary PAM (bipolar)


Cho, Yong Soo




Impulse response of transmit filter & channel

Cn=[0.0, 0.2, 0.9, -0.3, 0.1]

Normalization gain

• Sum ( |Cn| )


Cho, Yong Soo




3-tap zero forcing equalizer


Cho, Yong Soo




5-tap zero forcing equalizer


Cho, Yong Soo




Simulation Assignment (Communication System Level)

Signal generator: Select sine wave(10V , 1kHz)

Plot the waveform of time scope at each stage

Plot impulse / frequency response of normal raised cosine filter (Rolloff factor: 1, 0.25)

– Plot the output of filter (input: impulse) using vector / spectrum scope

Plot the reconstructed sine wave after analog filter

– 10kHz sampling, 64 level quantization

– Modulation = 16QAM

– Buffer size = 4

– Square root raised cosine filter ( group delay = 4)

– Analog filter order = 3, 18

Signal generator: Select Random(10V, 1kHz)

Plot analytic BER curve (0~10dB) using equation

– BPSK, QPSK, 16QAM, 64QAM

Plot simulation result by changing Eb/No (step size: 1dB) for different modulation order

– BER (compare with analytic BER curve, Use square root raised cosine filter)

– EYE diagram (Use normal / square root raised cosine filter)

– Constellation (Use square root raised cosine filter at both transmit and receive sides)


Cho, Yong Soo




Basic Communication Blocks


Cho, Yong Soo




Sampling

Message signal

Sine wave : amplitude=10, 1kHz

Random : amplitude=10, 1kHz

Pulse Generator

Frequency : 10kHz, oversampling (5 times)

Pulse width : 0.025%

– Similar to discrete impulse

Sine wave

Impulse


Cho, Yong Soo




Quantization

Quantizer blockset

Quantization interval: 10/32 → -10 ~ +10 (64 level)

Continuous level → discrete level

PCM generation

Uniform encoder (output: integer type)

Need an integer to bit converter

Output of PCM generator: 6bits

Buffer

Output of Buffer: 4bits (16QAM)

Modulation

Select Blockset corresponding to modulation order

Constellation ordering : Gray code


Cho, Yong Soo




AWGN channel Mode : EbNo

Number of bits per symbol and symbol period need to be selected

according to modulation order Number of bits per symbol : 4bits

Symbol period : 1/6e4*4/8

Raised cosine receive filter Filter type : square root

Input sample per symbol : 8

Group delay : 4 symbols

Roll-off factor : 0.25

Down sampling : 8

Demodulation Select Blockset corresponding to modulation order

Constellation ordering : Gray code

Buffer1 Input: 4bits, Output: 6bits

Error rate calculation System delay : Group delay * bits per symbol * 2

16QAM : 4*4*2

Output data : port


Cho, Yong Soo




Uniform decoder

Analog Filter

Method : Butterworth

Type : Lowpass

Filter order : 3, 18

Passband edge freq. : 2kHz

Order : 18Order : 3


Cho, Yong Soo




Parameter setting depending on modulation order

Buffer size and Group delay need to be changed because of internal characteristic of Raised cosine filter block

Modulation Buffer size Group delay(Raised cosine filter)

B P S K 4 4

Q P S K 4 2

16 QAM

4 4

8 2

64 QAM

6 4

6 2

12 4

12 2


Cho, Yong Soo




Constellation / Eye diagram (Eb/No : 4dB)

Eye diagram: both Normal / Square root raised cosine filter

BPSK

QPSK

Normal raised cosine Square root raised cosine



Cho, Yong Soo




16QAM

64QAMNormal raised cosine Square root raised cosine



Cho, Yong Soo




BER curve

Use Matlab internal function erfc()

Run simulation time : more than 105

0 1 2 3 4 5 6 7 8 9 1010

-3

10-2

10-1

100

BER Curve for AWGN Channel (Analytic / Simulation)

EbN0[dB]

BE

R

Analytic-16QAM

Analytic-64QAM

Simulation-16QAM

Simulation-64QAM


Cho, Yong Soo




Direct-Sequence Spread Spectrum and Multi-path Fading Channel


Cho, Yong Soo




Simulation Assignment

DS-SS

Generate the PN sequence in textbook and plot autocorrelation property

Plot time-domain and frequency-domain characteristics of the spread signal

Plot BER curve when narrow-band interference signal is present

1-tap Rayleigh fading channel

Plot the magnitude of signal before and after Rayleigh fading channel

Plot impulse response

Plot frequency response

Plot Doppler spectrum

Compare with analytic BER curve

Plot distributions of amplitude, real, and image signal

3-tap Rayleigh fading channel

Plot impulse response

Plot frequency response

Plot Doppler spectrum

Plot BER curve

Plot BER curve when Rake receiver is used


Cho, Yong Soo




DS-SS (PG = 15)

Message signal : Binary random (sampling time : 1e-3/2)

Modulation : QPSK

PN sequence : PN sequence generator

sampling time : 1e-3/15

Generator polynomial : [1 1 0 0 1]

Normalizing gain : 1/sqrt(15)

Autocorrelation property of PN sequence using M-file

0 5 10 15 20 25 30-0.2

0

0.2

0.4

0.6

0.8

1

1.2


Cho, Yong Soo




Spreading effect

Time domain

Message

Real

Message

Imag

Code

Spread

Real

Spread

Imag


Cho, Yong Soo




15 ⅹspreading

Spreading effect

Frequency domain

Pulse shaping using raised cosine filter

Increase frequency dimension

using Up sampling in Raised cosine filter

Raised cosine filter parameter (unspread)

– Roll-off factor : 0

– Up sampling : 30

Raised cosine filter parameter (spread)

– Roll-off factor : 0

– Up sampling of spread : 2


Cho, Yong Soo




DS-SS BER Curve with Jamming signal


Cho, Yong Soo




DS-SS BER Curve with Jamming signal

Jamming signal

Sine wave : 0.5V, 250Hz

Frequency spectrum

0 1 2 3 4 5 6 7 8 9 1010

-6

10-5

10-4

10-3

10-2

10-1

100

BER Curve for AWGN Channel (Analytic / Simulation)

EbN0[dB]

BE

R

Analytic-QPSK

Spread-QPSK

Unspread-QPSK


Cho, Yong Soo




1-Tap Rayleigh channel

Maximum Doppler shift : 10Hz

Correspond to the speed of 10.8km/hr when carrier frequency is 1GHz

0 5 10 15 20 25 3010

-7

10-6

10-5

10-4

10-3

10-2

10-1

100

Eb/N0 (dB)

BE

R

BER Curve for Rayleigh Channel(Analytic / Simulation)

Analytic-AWGN QPSK

Analytic-Rayleigh QPSK

Simulation

Magnitude

After Rayleigh channel

Magnitude

Before Rayleigh channel


Cho, Yong Soo




Distribution for Rayleigh Fading Channel

Use Histogram after saving to Workspace

Compare with Analytic Gaussian / Rayleigh distribution

0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 50

500

1000

1500

2000

2500

3000

3500

4000

4500Distribution for Magnitude

-5 -4 -3 -2 -1 0 1 2 3 4 50

1000

2000

3000

4000

5000

6000Distribution for Imag Signal

-5 -4 -3 -2 -1 0 1 2 3 4 50

1000

2000

3000

4000

5000

6000Distribution for Real Signal


Cho, Yong Soo




Multi-path Rayleigh Fading Channel

Maximum Doppler shift : 10Hz

Delay vector : [0 1e-3/15 2e-3/15]

Gain vector in dB : [0 -3 -6]

0 5 10 15 20 25 3010

-7

10-6

10-5

10-4

10-3

10-2

10-1

100

Eb/N0 (dB)

BE

R

BER Curve for Rayleigh Channel(QPSK)

Analytic-AWGN QPSK


Multi-path Simulation


Cho, Yong Soo




AWGN

Number of bits per symbol : 30bits (QPSK)

Symbol period : 1e-3

Channel Estimation

Estimate magnitude and phase of each tap using impulse response


Cho, Yong Soo




Rake Receiver

Use 3 fingers

Despread the signal for each tap

Use MRC Combining


Cho, Yong Soo




MRC Combining


Cho, Yong Soo




Multi-path Rayleigh Fading Channel with Rake Receiver

0 2 4 6 8 10 12 14 16 18 2010

-7

10-6

10-5

10-4

10-3

10-2

10-1

100

Eb/N0 (dB)

BE

R

BER Curve for Rayleigh Channel(QPSK)

Analytic-AWGN QPSK


Multi-path, No Rake Receiver

Multi-path, Rake Receiver

Documents

Simulation - CAUcomm.cau.ac.kr/board/data/17_1/Mobile_Comm_Simulation_2017.pdf · – BER (compare with analytic BER curve, Use square root raised cosine filter) ... 16 QAM 4 4 8