Capacity-achieving CPM schemes

TL;DR

This paper introduces a pragmatic, low-complexity coded CPM scheme that approaches capacity by optimizing bit-to-waveform mapping and combining with outer convolutional codes, achieving near-capacity performance with reduced complexity.

Contribution

It proposes a capacity-achieving pragmatic CPM scheme with optimized bit mapping, simplifying receiver design while maintaining near-capacity performance.

Findings

Schemes perform close to CPM capacity

Reduced receiver complexity due to separation of functions

Optimized bit mapping enhances spectral efficiency

Abstract

The pragmatic approach to coded continuous-phase modulation (CPM) is proposed as a capacity-achieving low-complexity alternative to the serially-concatenated CPM (SC-CPM) coding scheme. In this paper, we first perform a selection of the best spectrally-efficient CPM modulations to be embedded into SC-CPM schemes. Then, we consider the pragmatic capacity (a.k.a. BICM capacity) of CPM modulations and optimize it through a careful design of the mapping between input bits and CPM waveforms. The so obtained schemes are cascaded with an outer serially-concatenated convolutional code to form a pragmatic coded-modulation system. The resulting schemes exhibit performance very close to the CPM capacity without requiring iterations between the outer decoder and the CPM demodulator. As a result, the receiver exhibits reduced complexity and increased flexibility due to the separation of the demodulation and decoding functions.