PREFACE The increasing demand on high data rate and quality of service
in wireless communication has to cope with limited bandwidth and energy
resources. More than 50 years ago, Shannon has paved the way to optimal
usage of bandwidth and energy resources by bounding the spectral
efficiency vs. signal to noise ratio trade-off. However, as any
information theorist, Shannon told us what is the best we can do but not
how to do it [1]. In this view, turbo codes are like a dream come
true: they allow approaching the theoretical Shannon capacity limit very
closely. However, for the designer who wants to implement these codes,
at first sight they appear to be a nightmare. We came a huge step closer
in striving the theoretical limit, but see the historical axiom repeated
on a different scale: we know we can achieve excellent performance with
turbo codes, but not how to realize this in real devices.