Multilevel coded modulation for unequal error protection and multistage decoding. II. Asymmetric constellations

Abstract

In this paper, multilevel coded asymmetric modulation with multistage decoding and unequal error protection (UEP) is discussed. These results further emphasize the fact that unconventional signal set partitionings are more promising than traditional (Ungerboeck-type) partitionings, to achieve UEP capabilities with multilevel coding and multistage decoding. Three types of unconventional partitionings are analyzed for asymmetric 8-PSK and 16-QAM constellations over the additive white Gaussian noise channel to introduce design guidelines. Generalizations to other PSK and QAM type constellations follow the same lines. Upper bounds on the bit-error probability based on union bound arguments are first derived. In some cases, these bounds become loose due to the large overlappings of decision regions associated with asymmetric constellations and unconventional partitionings. To overcome this problem, simpler and tighter approximated bounds are derived. Based on these bounds, it is shown that additional refinements can be achieved in the construction of multilevel UEP codes, by introducing asymmetries in PSK and QAM signal constellations. Index Terms-Asymmetric constellations, multilevel coded modulation, multistage decoding, unequal error protection, union bound. I. INTRODUCTION U NCONVENTIONAL signal set partitionings are a good approach to achieve unequal error protection (UEP) capabilities in multilevel coded modulation and multistage decoding [1], as shown in the companion paper [2]. In general,

On the Design of Modern Multilevel Coded Modulation for Unequal Error Protection

“…Similar to [6], in this work the only designable parameter for non-uniform 8PSK is the angle γ between two adjacent points within the same quadrant, as shown in Fig. 5.…”

“…This idea was further combined with non-standard partitioning to maximize the minimum Euclidean distance for MLC in [4]. In [5], [6], the design of both bits-to-symbol mapping and nonuniformly spaced constellation was done based on approximate upper bounds of the bit error rate (BER) and Euclidean distance. For Rayleigh fast fading channel, Hamming codes were used to demonstrate the UEP capability in [7].…”

Hierarchical Colour-Shift-Keying Aided Layered Video Streaming for the Visible Light Downlink

“…Multilevel coded modulation was originally proposed by Calderbank and Seshadri for providing UEP [72], where the 2-dimensional signal constellation is partitioned into disjoint subsets and the bit streams of different importance are carefully mapped to the different-integrity bit-positions of the constellation subsets. Later the theoretical upper bounds and the computer simulation-based performance of multilevel block coded modulations designed for UEP and multistage decoding were presented in [90], [91]. Aydinlik and Salehi [59], as well as Kim et al [92] improved the set partitioning of QAM used by TCM to achieve an improved UEP performance.…”

“…Both multilevel coded (MLC) modulation [59], [72], [90]- [93] and hierarchical modulation (HM) [77], [78], [81], [84], [85], [87], [94]- [98] have attracted substantial research attention, albeit the latter one can be considered as a special subset of the former one. Multilevel coded modulation was originally proposed by Calderbank and Seshadri for providing UEP [72], where the 2-dimensional signal constellation is partitioned into disjoint subsets and the bit streams of different importance are carefully mapped to the different-integrity bit-positions of the constellation subsets.…”

A method for the construction of hierarchical generalized space shift keying (GSSK) modulation for unequal error protection

“…This strategy was extensively studied in the context of uncoded modulations such as pulse/quadrature amplitude modulation (PAM/QAM) [1] and phase shift keying (PSK) [2]. UEP was also studied in the context of combined coding and modulation [3][4][5][6][7][8], where the construction of coded modulations for UEP is achieved by signal set partitioning and code selection. Modulations with UEP capabilities have found applications in multimedia communications [9][10][11], broadcasting [12,13], and relay communications [14].…”