Calculation and error bound of Min-approximated bitwise log-likelihood ratios of generalised M-ary PAM

Abstract

In modern digital communication systems, a high-order modulation and advanced channel coding are often jointly used to increase the spectral efficiency and coding gain. In this work, the authors investigate a computationally efficient method for evaluating the bitwise log-likelihood ratios of generalised M-ary pulse amplitude modulation (PAM) signals with the Min approximation. The proposed scheme is simple and can be applied to demodulate the M-ary PAM having an arbitrary symbol spacing and a bit stream mapping. The computational complexity and upper bounds of the approximation error are also provided for a better understanding of the proposed scheme.

Keywords

• computational complexity
• channel coding
• digital communication
• pulse amplitude modulation
• channel coding
• spectral efficiency
• coding gain
• computationally efficient method
• ary pam signals
• min approximation
• computational complexity
• upper bounds
• approximation error
• min-approximated bitwise log-likelihood ratios
• modern digital communication systems
• high-order modulation