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Advanced Research and Engineering Solutions (ARES) A Advanced R Research and E Engineering S Solutions (ARES)

Asymmetric Modulation for Cognitive Radio and Intelligent Environments

2004 Software Defined Radio Technical Conference and Product Exposition

Eric Kreb Scientific Applications International Corporation krebe@saic.com Robert Morelos-Zaragoza San Jose State University r.morelos-zaragoza@ieee.org

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Outline

• Introduction
• Asymmetric Modulation

– Design – Mathematical Analysis – Graphical Analysis

• Asymmetric Coherence
• Opportunities for Intelligent Environments
• Conclusion

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Complex Baseband System Model

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Orthogonal Basis Functions

∫

T dt

∫

T dt

∫

T dt 1

φ

2

φ

N

φ

1 i

s

2 i

s

iN

s

i

s

1

φ

2

φ

N

φ

1 i

s

2 i

s

iN

s

i

s

) (t sI ) (t s

Q

) (t s ) (t s ) (t sI ) (t s

Q

) 2 (

1

t f COS

c

π φ =

2

φ ) 2 (

1

t f COS

c

π φ =

2

φ

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Common Modulation Schemes

Constant Envelope Modulated Envelope

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Asymmetric Modulation Design

AsPSK

Asymmetric Phase-Shift Keying

AsQAM

Asymmetric Quadrature Amplitude Modulation

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Asymmetric Phase-Shift Keying

Mapping Functions

1 1

2 ) 1 ( πα α + − = x y

) 1 (

2 2

) 2 (

α α

π

−

= x y

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AsPSK: Constellations

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AsPSK: Expected BER in AWGN

( ) ( )

              − − ⋅ ⋅ ⋅ ⋅ ≈ M M N E M Q P

B b

α π 1 sin lg 2

1

( )

( )

                        − ⋅ ⋅ ⋅ ≈

−α

π

1 2

1 sin lg 2 M M N E M Q P

B b

AsPSK-1 & AsPSK- 2

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AsPSK: Dynamic Control

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AsQAM: Lattice Structure

QAM vs AsQAM

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AsQAM: Lattice Structures

Direct Comparison

• f

Square Lattice & Simplex Lattice

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AsQAM: Constellations

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AsQAM: BER in AWGN

        ≈

_

5 2 4 3 N E Q P

B QAM b

        ≈

_

3 2 2 N E Q P

B AsQAM b

QAM & AsQAM

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AsQAM vs. Standard QAM

Nearest-Neighbor Distances

0.6325 16-QAM 0.6659 4 0.6690 3 0.6688 2 0.6761 1 16-AsQAM- 1

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Clock Synchronization

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Coherent & Noncoherent Receivers

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Detector Simulations

AsPSK- 1 AsPSK- 2

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Opportunities for Intelligent Environments

• Dynamic Design
• Synchronization and Data Transfer Modes
• Low Priority Data Transfer at Low Cost
• Continuous and Discrete Constellation

Monitoring

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Conclusion

• Discrete and Continuous Dynamic Designs
• Optimal Lattice Structure
• Asymmetric Coherence
• Environmental Intelligence Capability

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References

[1]

• S. Haykin, Communication Systems, 4th ed., New York: Wiley, 2001

[2]

• M. Isaka, M. Fossorier, R. Morelos-Zaragoza, S. Lin, H. Imai, “Multilevel Coded

Modulation for Unequal Error Protection and Multistage Decoding – Part II: Asymmetric Constellations,” IEEE Transactions on Communications, no. 5, pp. 774-786, May 2000 [3]

• L. Venkata Subramaniam, S. Rajan, R. Bahl, “Performance of 4- and 8-State TCM

Schemes with Asymmetric 8-PSK in Fading Channels,” IEEE Transactions on Vehicular Technology, vol. 49, No. 1, pg 211-219, January 2000 [4]

• F. Sanzi, M. C. Necker, “Totally Blind APP Channel Estimation with Higher

Order Modulation Schemes,” Proceedings of the Vehicular Technology Conference, Orlando, October 2003 [5]

• G. Colavope, R. Raheli, “On Noncoherent Sequence Detection of Coded QAM,”

IEEE Communications Letters, Vol. 2, No. 8, August 1998