Optimized Mappings for Iteratively Decoded BICM on Rayleigh Channels with Interleaving

Abstract

A cost function for the optimization of mappings for bit-interleaved coded modulation systems with iterative decoding (BICM-ID) for a Rayleigh channel with applied IQ interleaving is derived. For this channel model the optimum mapping depends on the channel quality and on the rotation of the signal constellation set. Simulation results reveal that mappings optimized with the new cost function yield a better performance than previously known mappings. Furthermore, a second, easy procedure to obtain the optimum rotation angle for a signal constellation set in conjunction with IQ Interleaving is described.

Algorithm for Generating All Optimal 16-QAM BI-STCM-ID Labelings

“…Taking into account the relation between point-wise distance spectra and the asymptotic coding gain (3) [the elements of all point-wise distance spectra appear in (3)], it is obvious, that two labelings with the same spectral properties yield identical asymptotic coding gain.…”

“…(3). The interested reader is referred to [14] to get known how to obtain e X 2 for LD scheme and to see that LD scheme exhibits full diversity order, i.e., it meets a full-rank criterion, concerned in [18, Sec.…”

“…Some researchers tried moving the position of constellation points for a given modulation order, e.g., [3,4], but in most cases the constellation points were fixed and the research focused on solving a combinatorial problem of associating binary labels with constellation points of well known modulations, like 8-PSK, 16-QAM, and 64-QAM [3,[5][6][7]. Interestingly, in [8] some system performance improvement was obtained by reducing the modulation order and assigning non-unique labels to constellation points.…”

Labeling Diversity for 2x2 WLAN Coded-Cooperative Networks

“…It is a known fact that the Bit Error Rate (BER) performance of Bit-Interleaved Coded Modulation (BICM) depends significantly on the labeling map and is further improved with the help of iterative decoding [16], [17], [18]. However, the cost of improved performance is increased latency of the communication system, which may be one of the critical factors in some applications such as live telemetry and video broadcasts in satellite communication systems [19].…”