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The Study of Modulation Schemes ??????????

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Title: The Study of Modulation Schemes Author: motao Last modified by: MOTOR Created Date: 7/1/2005 5:11:34 PM Document presentation format – PowerPoint PPT presentation

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Title: The Study of Modulation Schemes ??????????


1
The Study of Modulation Schemes??????????
2
Elliptical Modulated Signal
Current Schemes
Sine Wave Signal
Circle
Proposed Schemes
Elliptical Modulated Signal
Ellipse
3
Flexibility of Elliptical Modulation
  • Traditional Modulation Schemes
  • ASK, FSK, PSK
  • AM, FM, PM
  • Transformation of Carrier Signal
  • in Amplitude, Phase and Frequency

Proposed Modulation Schemes
Amplitude, Phase , Frequency
and Eccentricity,
Inclination Angle, Rotation Frequency, Rotation
Direction
4
Concept Theory
P
R 2
a
R 1
r
?
o
a
F
-F
-b
Semi-major axis (a)
? Revolution Angle a Offset Inclination
Angle ?r the revolution frequency of the
carrier eccentricity
5
Concept Theory
P
R 2
a
R 1
r
?
o
a
F
-F
-b
Semi-major axis (a)
? Revolution Angle a Offset Inclination
Angle ?r is the revolution frequency of the
carrier ?i is the rotation frequency of the
carrier
6
Elliptical Modulation Schemes
Basic Schemes
  • Eccentricity Shift Keying (ESK)
  • Inclination Angle Shift Keying (IASK)
  • Rotation Frequency Shift Keying (RFSK)

7
Inclination Angle Shift Keying
(IASK)
Binary 0
Binary 1
8
Inclination Angle Shift Keying Signal (
,ec 0.3, 0.6, 0.9)
9
Rotation Frequency Shift Keying (RFSK)
where wi is modulation variable
Binary 0
Binary 1
10
4-ary EPSK(Elliptical Phase Shift Keying)
Offset inclination angle phase
where ?i and ?j can have N and K discrete
values respectively. M NK
4-ary Elliptical Phase Shift Keying (N2K2,
BPSKIASK)
(?i ,?j) (p/4, p/4) (3p/4, 3p/4)
(p/4, 5p/4) (3p/4, 7p/4)
where integer i 0,1,2,3
11
Correlation Coefficient
where integer i 0,1,2,3, and corresponding
signals are defined as S1, S2, S3, S4.
CS1S2_SIN CS2S3_COS CS3S4_SIN CS4S1_COS
- CS1S2_COS CS2S3_SIN CS3S4_COS CS4S1_SIN
ec 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9
? 0.005 0.020 0.047 0.087 0.144 0.222 0.334 0.500 0.786
12
Mathematical Analysis of BER
ec 0.9 0.8 0.7 0.6 0.5 0.4
a 1.51A 1.29A 1.18A 1.11A 1.07A 1.04A
BER comparison
13
Modulation and Demodulation
Carrier recovery circuit
LPF
block
Advantage can be strenthened by increasing
eccentricity
14
Simulation Results on BER Performance
In Rayleigh fading channel
Under AWGN
  • 4-EPSK outperforms QPSK
  • error performance is directly proportional to the
    value of eccentricity
  • Both results are consistent with conclusions
    achieved from mathematical
  • analysis and demodulation illustration.

15
Proposal of 8-ary EPSK
  • 8-ary Elliptical Phase Shift Keying ( N2K4)

where i 0,1,2,3 j0,1
16
Mathematical Analysis of BER
Euclidean distance comparison
BER comparison
ec 0.9 0.8 0.7 0.6 0.5 0.4
a 1.51A 1.29A 1.18A 1.11A 1.07A 1.04A
rmin 0.47A 0.55A 0.59A 0.63A 0.65A 0.67A
17
Receiver of 8-EPSK signals




18
Effect of Eccentricity to Performance of 8-EPSK
Under AWGN
19
Performance Comparison between 8PSK 8-EPSK at
eccentricity of larger than 0.5
Rayleigh fading channel
20
New Concept of Waveform
inclination angle
frequency
eccentricity
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