March 2011
Intermediate
680 pages
25h 12m
English
Chapter 14
Coded Modulation Theory and Performance
14.1 Introduction
In this chapter our elaborations are related to a set of combined error control techniques, where channel coding and modulation are carried out jointly. At the receiver it is possible to employ both iterative and non-iterative detection and, as expected, the latter family of iterative decoders typically achieves a better performance, although at the cost of an increased implementational complexity.
Since we are relying on convolutional coding principles, familiarity with the basic concepts of Chapters 2 and 4 is assumed.
The radio spectrum is a scarce resource. Therefore, one of the most important objectives in the design of digital cellular systems is the efficient exploitation of the available spectrum in order to accommodate the ever-increasing traffic demands. Trellis-Coded Modulation (TCM) [295], which will be detailed in Section 14.2, was proposed originally for Gaussian channels, but it was further developed for applications in mobile communications [296,297]. Turbo Trellis-Coded Modulation (TTCM) [57], which will be discussed in Section 14.4, is a more recent joint coding and modulation scheme that has a structure similar to that of the family of power-efficient binary turbo codes [12], but employs TCM schemes as component codes. TTCM [57] requires an approximately 0.5 dB lower Signal-to-Noise Ratio (SNR) at a Bit Error Ratio (BER) of 1CP4 than binary turbo codes when communicating using 8-level Phase ...
