Adaptive Coded Modulation for Transmission over Fading Channels - Adaptive Signal Processing in Wireless Communications - page 70

3
Adaptive Coded
Modulation for
Transmission over
Fading Channels

3.1 Introduction ............................................................ 71
3.2 Adaptive System Model ......................................... 75
Model for a Wireless Link • Adaptation in
Response to Path Loss/Shadowing • Analytic
Model for Fine-Scale Adaptation
3.3 Adaptivity in Single-Input Single-Output
Systems ..................................................................... 80
Information heoretic Bounds • Design
for Uncoded Systems • Coded Modulation
Structures • Designing with a Given Coded
Modulation Structure
3.4 Adaptivity in Multiantenna Systems ................... 88
Information heoretic Considerations •
Adaptive Coded Modulation for MIMO Systems
3.5 Conclusions.............................................................. 90
References ........................................................................... 91

Dennis L. Goeckel
University of Massachusetts

3.1 Introduction

The main goal of modern communications systems is to make universal high-speed
access to information a reality. Under nearly any realizable scenario, the end user in
such a system is free of tethers, thus making robust high-speed data transfer across the
wireless channel a topic of extreme importance. However, the wireless channel presents
a number of challenges. In particular, the wireless signal experiences [55]:

1. Path loss: The signal attenuates with distance from the transmitter.

2. Shadowing: Large objects between the transmitter and receiver can obstruct the
radio signal.

3. Multipath fading: Reflections from objects in the environment can add construc-
tively or destructively at the receiver.