Coded Modulation with Signal Space Diversity

Abstract

Signal space diversity (SSD) is a well-known powerand bandwidth-efficient diversity technique with constellation rotation and coordinate interleaving. This paper investigates issues of combining SSD with coded modulation systems (CMSs), e.g., bit-interleaved coded modulation (BICM) and its iterative version, BICM-ID. It demonstrates that the average mutual information (AMI) between the signal after rotated constellation mapping and the signal before or after the soft demapper varies with the rotation angle. A new criterion for determining the optimal rotation angle by maximizing such AMI is therefore proposed. Specific considerations of combining SSD with BICM (BICM-SSD) and BICM-ID (BICM-ID-SSD) are addressed. The demapper's extrinsic information transfer (EXIT) curve in traditional BICM-ID systems exhibits different slopes under different channels, which consequently prevents traditional BICM-ID systems from having simultaneously excellent performance under different channels. It is shown that such a different-slope problem can be simply mitigated by a proper use of SSD. Analysis and simulation show that the proposed BICM-ID-SSD systems hold a near-capacity performance under both additive white Gaussian noise (AWGN) and Rayleigh fading channels simultaneously.

Constant envelope signal space diversity

“…Then, minimizing the average error probability is relevant. By contrast, for systems that use strong channel coding, maximizing other metrics like the mutual information [11], may be more appropriate. Hence, in this work, we are interested in the construction of a set T = {t1, t2, · · · , tN } ⊂ C n , which corresponds to the set of precoder output vectors.…”

Two-way decode-and-forward cooperative systems with signal space diversity

“…In this way, the ordinary constellation is rearranged to the expanded constellation, which contains all possible combinations of different components of signal points in the ordinary constellation. Thus, SSD extracts the inherent diversity from the modulation signal space without adding any extra bandwidth or transmit power [29,30].…”

Rotated Constellations for Improved Time and Frequency Diversity in DVB-NGH

“…Although the theoretical framework has been established in the past [13], previous investigations do not consider the presence of outages in the received signal and generally assume a Gaussian or Rayleigh channel. In comparison, the main novelty of the paper is the investigation of the capabilities of rotated constellations to cope with signal outages in the time and frequency domains, and the performance gains that can be achieved by combining rotated constellations with long TI and TFS in DVB-NGH systems.…”