Multi-User Detection and Multi-User Decoding in Multiple Access Systems


Over the past decade, much work has been done in the area of multi-user detection (MUD). These efforts have now led to a thorough understanding of the principles at play and thus to a structured theory and framework for design and analysis. Within the past few years, joint decoding of coded CDMA has also matured and there is now a firm understanding of iterative decoding techniques based on turbo principles. This tutorial is intended to provide an overview of the fundamental theory and current understanding of joint multi-user detection and decoding.

This introductory tutorial is divided into three parts, namely,

  • Part I: Introduction
  • Part II: Multi-User Detection Strategies
  • Part III: Multi-User Decoding Strategies

The first part provides a general introduction into multiple access systems and the principles applied in multi-user detection. Part II is intended to provide a firm understanding of the main multi-user detection structures suggested in the literature. The tutorial will focus on the optimal ML detector, linear detectors and especially on iterative interference cancellation strategies as they are particularly interesting for practical implementation. Also some recent advances using heuristic approaches and probabilistic data association are discussed. This provides a broad foundation within the area upon which a detailed discussion of iterative joint decoding strategies for coded CDMA can be based. In Part III, joint decoding of coded CDMA is discussed in some detail and especially iterative joint decoding based on turbo principles and linear MUD strategies are considered. Recent non-linear approaches are also discussed as well as the use of transfer analysis in terms of EXIT charts and variance tracing for performance evaluation.

Course Outline

Part I: Introduction

  • Introduction
  • Linear Multiple Access Channel Model
  • Code Division Multiple Access
  • Principles of Detection

Part II: Multi-User Detection Strategies

  • Introduction
    • Historical perspective
  • One-Shot Detection
    • Optimal (0,1)-constrained ML detection
    • Linear detection
  • Iterative Detection (Multi-Stage Interference Cancellation)
    • Linear interference cancellation
    • Weighted linear interference cancellation
    • Non-linear interference cancellation
  • Heuristic Search Algorithms
    • Local search
    • Iterative local search
    • Tabu search
  • Probabilistic Data Association Detection

Part III: Multi-User Decoding Strategies

  • Joint Decoding of Coded CDMA
    • Optimal decoding
    • Linear pre-processing single user decoding
    • Iterative decoding strategies
    • Reduced complexity iterative decoding strategies
    • Iterative Transfer Analysis

© Tero Suutari, CWC