No abstract

In this letter, we investigate different signal mappings for bit-interleaved coded modulation (BICM) and their effect on the secrecy information rate of a wire-tap channel exhibiting Rayleigh fading. By focusing on BICM schemes using 64QAM, 16QAM and (1, 5, 10) signal constellations, we show that the optimal mapping depends on the range of signal-tonoise ratios (SNRs) we are interested in. We propose a new mapping algorithm, called maximum error event (MEE), to optimize the secrecy rate over a wide range of SNRs. At low SNR, MEE mapping achieves a lower secrecy rate than other well known mappings, but at medium-to-high SNRs MEE mapping achieves a significantly higher secrecy rate over a wide range of SNRs. Simulation results on 16QAM, 64QAM and (1, 5, 10) constellations are presented to show the achievable secrecy rates of various mappings for BICM from low to high SNRs.

Low-complexity power control and energy harvesting algorithms for wiretap channels employing finite-alphabet input schemes.

Abstract:We study the impact of various modulation mapping strategies and signal constellation shapes on the secrecy rates achievable with bit-interleaved coded modulation (BICM) schemes. Transmission over an ergodic Rayleigh fading channel is assumed throughout this work. Various constellations and mapping techniques are considered in this work to maximize the capacity difference between the main channel and the eavesdropper channel, rather than to optimize the capacity of both channels. We show that in terms of achievable secrecy rate, Gray and Quasi-Gray mappings only perform well at low SNR but outperformed by other mapping techniques when SNR increases. The proper design of signal mapping can significantly enhance the achievable secrecy rate in BICM schemes. It is indicated that the key parameter to the secrecy rate of a BICM system is the distance spectrum of Euclidean distances for mappings.