TABLE OF CONTENTS Power and bandwidth are limited resources in modern communications systems. Efficient exploitation of these resources will invariably involve an increase in the complexity of a communication system. If the signal set dimensionality per information bit is unchanged, the spectral efficiency remains unchanged. Even though double-binary CRSC codes have an excellent performance, they are limited by the QPSK modulation to a bandwidth efficiency of less than 2bits/s/Hz, as well as the limit on puncturing. There are only limited number of parity bits to be punctured to achieve higher bandwidth efficiency. For example, the number of parity bits left in each encoder for the code rate 6/7 is only 1/12 of the information bits.
In this chapter, the design of a triple-binary CRSC code [110] is presented. This code is intended for being used with 8PSK modulation. The turbo encoder design involves the component encoder design, the interleaver design and the puncturer design. Certain special conditions need to be met at the encoder and the iterative decoder need to be adapted to symbol-by-symbol decoding.
[110]Yingzi Gao, Design and Implementation of Non-binary Convolutional Turbo Code, M. A. Sc. thesis, Dept. of Elect. & Comp. Eng., Concordia University, Dec. 2001.
Using double-binary codes as component codes represents a simple means to reduce the correlation effects that have a direct incidence on the erroneous paths in the trellises [89]. The use of double-binary turbo codes lead to a lowered path error density and...
