Course #81

Modulation, Coding, and Iterative Techniques for Optimal Detection in Wireless Communications

November 22-26, 2010. Barcelona, Spain

INSTRUCTOR
Professor Sergio Benedetto, Politecnico di Torino, Italy
Professor Guido Montorsi, Politecnico di Torino, Italy

TECHNOLOGY FOCUS
Wireless communication systems had been designed primarily for voice services. First generation cellular systems were analog in nature, thus unsuitable to data transmission. The driving force for the second (digital) cellular generation was increased capacity to accommodate the high demand for new customers, so that data services came just a fall-out of the digital technology, and were limited to very low data rates. 
The explosion of Internet usage, with the ever increasing demand for the downloading of large bulk of data in multimedia services, on one hand, and the gradual predominance of wireless communication over the wired one, made second generation cellular systems fully inadequate. For this reason, third generation was designed focusing on Internet, rather than voice, services, and this will be even more the case for the generations to follow. 
The resulting, high data rates that are needed to satisfy the users' requests, together with the severe limitations in the available bandwidth devoted to cellular services, force wireless communication systems to face ever increasing challenges on severe bandwidth and energy constraints. The present and future of wireless communications is then dependent on the possibility of fully exploiting the available bandwidth by increasing as much as possible the efficiency of its use. 
Moreover, the time-varying characteristics of the wireless channel, and its frequency selectivity induced by the multipath fading, pose severe challenges to the system designer in order to cope with the high quality of service required for multimedia applications. Very recent tools like Adaptive coding and modulation, multi-antenna transmitter and receiver (MIMO), turbo and LDPC codes, iterative co-decoding and reception techniques based on the turbo principle are revolutionizing the theory and practice of digital communication.

COURSE CONTENT
This course focuses on techniques to reliably communicate digital information over the wireless channel. It provides the fundamental trade-offs between bandwidth, energy and performance, and explains in detail the main tools available to improve the performance of digital wireless transmission, such as bandwidth-efficient modulation schemes, MIMO and space-time coding, turbo and LDPVC codes, iterative demodulation and decoding, carrier and clock synchronisation. 
A peculiar, unique feature of the course will be the focus on the "how" and "why" (as opposite to the "how" only) of those techniques, driving the course attendees to capture the full rationale of the main choices that have been made at standardization level. 
To deepen the knowledge of each topic, and to make the attendees be able to use in their everyday professional activities the explained concepts, each day in the course will be concluded by a software-lab session, in which C-language programs implementing the main algorithms described in that day will be explained, used, and made freely available to course attendees. The C program are part of a simulation package fully developed by the course instructors, and fulfill the requisites of speed and generality that distinguishes a professional simulation tool from a toy instrument.

Monday 

Introduction to Wireless Communication: a Bit of History

The Limits Imposed by Information Theory to Communication Systems

• The Shannon Theorem 
• The Rate-Distortion Capacity of Additive White Gaussian Noise and Fading Channels 
• The Minimum Signal-to-Noise Ratio vs. Bandwidth Efficiency for Reliable Communication 

M-ary Coherent Modulation

• QPSK and M-PSK Modulation 
• M-QAM Modulation 
• Optimum Coherent Receivers
• Differential Demodulation of PSK Signals
• Orthogonal Frequency Modulation 

Modulation Schemes on the Performance Plan

• Spectral Efficiency versus Signal-to-Noise Ratio per Information Bit 
• Practical Applications of the Various Modulation Schemes 

Carrie and Symbol Synchronization in Digital Transmission 

Computer Session 

• Capacity Evaluation of Various Channels by Analysis/Simulation 

Tuesday 

Linear Channel Impairment and Adaptive Equalization

• The Nyquist Criterion to Avoid Intersymbol Interference 
• Linear and Decision Feedback Adaptive Equalization 
• Maximum-Likelihood Sequence Receiver: The Viterbi processor 

The Wireless Communication Channel

• The Free-Space Propagation Equation 
• Antenna Gain and Effective Area
• Impairments of Real Radio Channels 
• The Multipath Fading Channel: Frequency and time selectivity 
• The Taxonomy of Fading Channels

Constraints Imposed by the Fading Channel on Modulation Schemes

• From QPSK to Offset-QPSK to MSK: Nonlinear impairments and interchannel interference 
• The pi/4-QPSK Modulation 

Constant Envelope, Continuous Phase Modulation

• MSK, Full and Partial Response CPM 
• GMSK, SFSK 
• Coherent and Non-coherent Receivers for CPM Signals

Performance of Digital Modulation over the Fading Channel

Modulation Schemes Adopted in Wireless Communication Standards 

Computer Session 

• Linear, Decision-Feedback Equalizer and Maximum-Likelihood Sequence Receivers
• CPM Spectra and Receiver 

Wednesday 

Channel Coding: A Taxonomy

Block Codes

• Linear Block Codes
• Detection and Correction Capability
• Design Parameters
• Cyclic Block Codes
• BCH and Reed-Solomon Codes 
• Performance of Algebraic Hard Decoding of Block Codes 
• Performance of Soft Decoding of Block Codes 

Convolutional Codes

• Trellis Description 
• The Viterbi Decoding Algorithm 

Interleaving for the Bursty Channel

Concatenated Codes

Turbo Codes

• Maximum-Likelihood Performance 
• Design 
• Iterative Decoding Algorithm 
• Performance 
• Practical Implementation: DSP, FPGA, VLSI 

Low-density Parity-check Codes

• Regular and Irregular LDPC Codes 
• Iterative Decoding Algorithm 

Thursday

Turbo Iterative Decoding Algorithm

• A heuristic Justification of the Iterative Algorithm
• Optimum and Sub-Optimum SISO Algorithms
• Additive Version of the SISO Algorithm

Message-Passing Decoding Algorithm for LDPC Codes

Practical Implementation Issues: Degree of parallelism, fixed-point implementation

Bandwidth and Power Efficient Codes

• Trellis-Coded and Turbo-Trellis-Coded Modulation 

Computer Session 

• The Iterative Turbo Decoding Algorithm and the Message Passing LDPC Decoding Algorithm

Friday 

Access Techniques 

Fundamentals of Code Division Multiple Access 

Multi-User Detection

• Optimal and Sub-Optimal Detectors 
• Turbo Multi-User Detection 

Multiple-Input Multiple-Output (MIMO) Systems

Single user MIMO 

• Motivations
• Fundamentals of Wireless Channels
• Performance of Fading Channels
• Diversity
• Space Diversity: SIMO, MISO
• Channel Capacity
• Fixed Channel 
• Slow fading Channel
• Fast fading Channel
• Point-to-Point MIMO
• Fixed Channel
• Multipath Fast Fading Channel
• Slow Fading Channel
• Diversity-Multiplexing Trade-Off

Multi user MIMO

• Uplink-Downlink Duality Principle
• Uplink and Downlink Capacities

Space Time Codes

• Block and Convolutional ST codes
• Orthogonal and Quasi-Orthogonal ST Codes

Computer Session

• TCM and ST Codes Bounds

Regular Course Fee: EUR 2995

Early Registration Course Fee:  EUR 2725
This applies to firm registrations received 2 months before course start. 

University Student and Faculty Rate:
Two university participants are welcome to attend for one course fee if payment is to be made from university funds.

Deliverables:
The course fee covers tuition, course material, and the day conference packages (morning/afternoon refreshments, lunches etc.,) paid on your behalf to the course venue. Accommodation is not included.