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SYSTEM ARCHITECTURE

ADVANCED SYSTEM ARCHITECTURE

BATEMAN

Chapter6: Multi-level digital modulation

2013/Fall-Winter Term

Monday 12:50

Room# 1-322 or 5F Meeting Room

Instructor: Fire Tom Wada, Professor

Chapter6: Multi-level digital modulation

6.1 Introduction

6.2 M-ary Amplitude Shift Keying (M-ary ASK)

6.3 M-ary Frequency Shift Keying (M-ary FSK)

6.4 M-ary Phase Shift Keying (M-ary PSK)

6.5 Combined Amplitude and Phase Keying (QAM/APK)

6.6 Relative performance of multi-level bandpass

modulation formats

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12/1/2013 Fire Wada Lab 3

Previous Chapter 5

Digital modulation basics

Digital modulation modulates three parameters of sinusoidal signal.

A, θk fc,

Three type digital modulation: ASK : Amplitude Shift Keying

PSK : Phase Shift Keying

FSK : Frequency Shift Keying

s t A f tc k( ) cos( ) 2

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Symbol Waveform

1 0 1 0 0Digital Information

carrier

ASK

PSK

FSK

Symbol length

Chapter6: Multi-level digital modulation

6.1 Introduction

6.2 M-ary Amplitude Shift Keying (M-ary ASK)

6.3 M-ary Frequency Shift Keying (M-ary FSK)

6.4 M-ary Phase Shift Keying (M-ary PSK)

6.5 Combined Amplitude and Phase Keying (QAM/APK)

6.6 Relative performance of multi-level bandpass

modulation formats

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M-ary ASK

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Bit

information

M-level

signal

𝑀 = 2𝑛

If M=8 levels then

n = log2𝑀 = log2 8 = 3 𝑏𝑖𝑡

Up

conversion

Down

conversion

Performance of M-ary ASK When M is increased, number of bits transferred

is increased. But need better SNR (Eb/N0).

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Chapter6: Multi-level digital modulation

6.1 Introduction

6.2 M-ary Amplitude Shift Keying (M-ary ASK)

6.3 M-ary Frequency Shift Keying (M-ary FSK) SKIP

6.4 M-ary Phase Shift Keying (M-ary PSK)

6.5 Combined Amplitude and Phase Keying (QAM/APK)

6.6 Relative performance of multi-level bandpass

modulation formats

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Quadrature Phase Shift Keying (QPSK)

4 Orthogonal waves are used!

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𝑆0 𝑡 = 𝐴 cos 𝜔𝑐𝑡 +0𝜋

2= +𝐴 cos 𝜔𝑐𝑡

𝑆1 𝑡 = 𝐴 cos 𝜔𝑐𝑡 +1𝜋

2= −𝐴 sin 𝜔𝑐𝑡

𝑆2 𝑡 = 𝐴 cos 𝜔𝑐𝑡 +2𝜋

2= −𝐴 cos 𝜔𝑐𝑡

𝑆3 𝑡 = 𝐴 cos 𝜔𝑐𝑡 +3𝜋

2= +𝐴 sin 𝜔𝑐𝑡

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Another Quadrature Phase Shift Keying

(QPSK)

data θk ak bk

00 π/4

01 3π /4

11 5π /4

10 7π /4

2

1 1

2

1

2

1

21

2

1

2

1

2

1

2

ak

bk

𝑆𝑘 𝑡 = cos 𝜔𝑐𝑡 + 𝜃𝑘

QPSK modulator

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𝑆0 𝑡 = cos 𝜔𝑐𝑡 +𝜋

4= cos 𝜔𝑐𝑡 cos

𝜋

4− sin 𝜔𝑐𝑡 sin

𝜋

4= 𝑎0cos 𝜔𝑐𝑡 − 𝑏0 sin 𝜔𝑐𝑡

a0

b0

x

cos 𝜔𝑐𝑡

x

−sin 𝜔𝑐𝑡

+

Bit error performance of QPSK

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Symbol error performance of QPSK

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π/4 QPSK

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Performance of M-ary PSK

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Chapter6: Multi-level digital modulation

6.1 Introduction

6.2 M-ary Amplitude Shift Keying (M-ary ASK)

6.3 M-ary Frequency Shift Keying (M-ary FSK) SKIP

6.4 M-ary Phase Shift Keying (M-ary PSK)

6.5 Combined Amplitude and Phase Keying (QAM/APK)

6.6 Relative performance of multi-level bandpass

modulation formats

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QAM generation

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I

Q

16QAM

a0=±A,±3A

b0 =±A, ±3A

x

cos 𝜔𝑐𝑡

x

−sin 𝜔𝑐𝑡

+

A 3A-A-3A

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Quadrature Amplitude Modulation (QAM)

I

Q

I

Q

16QAM 64QAM

Example 6.1

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Raised cosine filtering

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Solution 6.1

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16-PSK vs 16-QAM

Example 6.2

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I

Q16QAM

Solution 6.2

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111 uW

Example 6.3

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Solution 6.3

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BER performance of QAM

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Chapter6: Multi-level digital modulation

6.1 Introduction

6.2 M-ary Amplitude Shift Keying (M-ary ASK)

6.3 M-ary Frequency Shift Keying (M-ary FSK) SKIP

6.4 M-ary Phase Shift Keying (M-ary PSK)

6.5 Combined Amplitude and Phase Keying (QAM/APK)

6.6 Relative performance of multi-level bandpass

modulation formats

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BER comparison

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Close to Shannon limit

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16QAM

QPSK

Need two presenter

Each presenter shall chose two problems from

6.1 to 6.10. The one for even and the other for

odd problems.

Show your answer at the beginning of next

lecture. Each has 5 minutes.

Next lecture will be 12/9 (mon)

Dec/14th Saturday,1pm to 5pm is Matlab lab at

computer center, please prepare your login ID

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