Nonlinear Digital Encoders for Data Communications

Calin Vladeanu is Associate Professor of telecommunications at the University Politehnica of Bucharest, Romania. His current research interests include turbo-coded modulations for wireless communications, applications of nonlinear sequence generators for spreading and channel coding. He is the author of three books (in Romanian) dedicated to CDMA mobile systems. Safwan El Assad is Associate Professor at the University of Nantes, France. His current research interests are in the field of chaos-based exchanged and stored information security, including chaos-based cryptography and crypto-compression systems for secure data transmission and storing, chaos-based watermarking and steganography.

• Preface ixIntroduction xiChapter 1. Applications of Nonlinear Digital Encoders 11.1. Secure communications using nonlinear digital encoders 11.1.1. The general nonlinear digital encoder scheme 31.1.2. Quasi-chaotic sequence properties 51.1.3. An example of simple nonlinear digital encoder: the Frey chaotic encoder 71.1.4. Simulation results revealing the quasi-chaotic properties for the sequences generated using the Frey encoder 91.2. Chaotic spreading sequences for direct-sequence code division multiple access 151.3. Sequence synchronization in discrete-time nonlinear systems 191.3.1. An example of sequence synchronization using the inverse system 191.3.2. The dead-beat synchronization method 231.3.3. A communication scheme using the dead-beat synchronization 25Chapter 2. Presentation of the Frey Nonlinear Encoder as a Digital Filter 292.1. The mathematical analysis of the Frey encoder 292.2. The definitions and properties of the unsigned and 2’s complement signed sample operators 302.3. The properties of the LCIRC nonlinear function used in the Frey encoder scheme 382.4. The simulation of the Frey sequence generator block in Simulink: some practical considerations 412.4.1. The transmitter chaotic sequence generator 412.4.2. The receiver chaotic sequence generator and the dead-beat synchronization with the transmitter block 432.4.3. The Simulink implementations for the blocks used in the Frey chaotic codec 45Chapter 3. Trellis-Coded Modulation Schemes Using Nonlinear Digital Encoders 493.1. The presentation of the Frey nonlinear encoder as a convolutional encoder 493.2. Frey encoder trellis design optimization methods for pulse amplitude – trellis-coded modulation (TCM) schemes 543.2.1. Increasing the coding gain by reducing the representation code word length in the input 563.2.2. Equivalence between a nonlinear and a linear encoder in a particular case 663.2.3. Generalized optimum encoder for a PAM-TCM transmission 693.2.4. Increasing the coding gain by increasing the number of outputs 753.3. Optimum nonlinear encoders for phase shift keying – TCM schemes 843.3.1. Rate-1/2 optimum encoder for a QPSK-TCM transmission 843.3.2. Generalized optimum encoder for a PSK-TCM transmission 853.4. Optimum nonlinear encoders for quadrature amplitude modulation – TCM schemes 893.5. Performance analysis of TCM data communications using modified nonlinear digital encoders: simulation results 91Chapter 4. Parallel Turbo Trellis-Coded Modulation Schemes Using Nonlinear Digital Encoders 974.1. Recursive convolutional-left circulate (RC-LCIRC) encoder in a turbo trellis-coded modulation (TTCM) scheme 974.2. New recursive and systematic convolutional nonlinear encoders for parallel TTCM schemes 1004.3. Punctured TTCM transmissions using recursive systematic convolutional nonlinear encoders 1084.4. Extrinsic information transfer (EXIT) charts analysis for TTCM schemes using nonlinear RSC encoders 1144.5. Performance analysis of TTCM data communications using nonlinear digital encoders: simulation results 115Appendix 133Bibliography 145Index 151