March 2011
Intermediate
680 pages
25h 12m
English
Chapter 11
Comparative Study of Turbo Equalisers1
11.1 Motivation
In Chapter 10, turbo equalisation was investigated in the context of channel coded partial response OMSK systems. The inherent recursive nature of OMSK modulation was exploited in order to achieve large interleaver gains. In this chapter a sound appreciation of the concepts presented in Chapter 10 constitutes a prerequisite, although useful system-performance-related information may be gleaned without understanding the associated iterative equalisation principles.
In this chapter, BPSK modulation is employed in order to investigate the performance of the turbo equaliser in the context of non-recursive modulation systems. In this case the modulator and dispersive channel are viewed as the inner encoder, while the channel encoder employed is perceived to be the outer encoder, as in the SCC scheme described in Section 15.3 of [144]. In addition to convolutional codes and convolutional-coding-based turbo codes, block-coding-based turbo codes are also researched in conjunction with BPSK systems utilising turbo equalisation. With the ever-increasing demand for bandwidth, current systems aim to increase the spectral efficiency by invoking high-rate codes. This has been the motivation for research into block turbo codes, which have been shown by Hagenauer et al. [61] to outperform convolutional turbo codes when the coding rate is higher than 2/3. It was also observed that a rate R = 0.981 block turbo code using BPSK over ...
