ADVANCED SYSTEM ARCHITECTURE

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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, θ

fc,



Three type digital modulation:



ASK : Amplitude Shift Keying



PSK : Phase Shift Keying



FSK : Frequency Shift Keying

s t ( )   A cos( 2     f t



)

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Symbol Waveform

1 0 1 0 0

Digital 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 = 2

If M=8 levels then

n = log

𝑀 = log

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 𝜔_𝑐𝑡 + 0𝜋

2 = +𝐴 cos 𝜔_𝑐𝑡 𝑆₁ 𝑡 = 𝐴 cos 𝜔_𝑐𝑡 + 1𝜋

2 = −𝐴 sin 𝜔_𝑐𝑡 𝑆₂ 𝑡 = 𝐴 cos 𝜔_𝑐𝑡 + 2𝜋

2 = −𝐴 cos 𝜔_𝑐𝑡 𝑆₃ 𝑡 = 𝐴 cos 𝜔_𝑐𝑡 + 3𝜋

2 = +𝐴 sin 𝜔_𝑐𝑡

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Another Quadrature Phase Shift Keying (QPSK)

data

θk a

b

00 π/4 01 3π /4 11 5π /4 10 7π /4

2

1

1

2

 1 2

 1

2  1 2

 1 2 1

2

1 2

a

b

𝑆

𝑡 = cos 𝜔

𝑡 + 𝜃

QPSK modulator

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𝑆

𝑡 = cos 𝜔

𝑡 + 𝜋 4

= cos 𝜔

𝑡 cos 𝜋

4 − sin 𝜔

𝑡 sin 𝜋

= 𝑎

cos 𝜔

𝑡 − 𝑏

sin 𝜔

𝑡 4 a

b

x

cos 𝜔

𝑡

x

−sin 𝜔

𝑡

+

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

a

= ± A, ± 3A

b

= ± A, ± 3A

x

cos 𝜔

𝑡

x

−sin 𝜔

𝑡

+

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

16QAM Q

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/14

Saturday,1pm to 5pm is Matlab lab at computer center, please prepare your login ID

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