We present a method for learning nonlinear systems, echo state networks (ESNs). ESNs employ artificial recurrent neural networks in a way that has recently been proposed independently as a learning mechanism in biological brains. The learning method is computationally efficient and easy to use. On a benchmark task of predicting a chaotic time series, accuracy is improved by a factor of 2400 over previous techniques. The potential for engineering applications is illustrated by equalizing a communication channel, where the signal error rate is improved by two orders of magnitude.

This paper compares performance of index modulation (IM) based OFDM to a more flexible version of OFDM, known as OFDM with multiple constellations (OFDM-MConst). To deliver the same spectral efficiency as in the IM-based OFDM, the OFDM-MConst employs different constellations in different subcarriers. The performance comparison between IM-based OFDM and OFDM-MConst is done for both cases of "no precoding" and "with precoding" of data symbols. Thanks to the multipath diversity gain achieved with precoding and enjoyed by all the information bits, the precoded-OFDM-MConst is shown to significantly outperform precoded-IM-based-OFDM systems over frequency-selective Rayleigh fading channels. References [1] Z. Liu, Y. Xin, and G. B. Giannakis, "Linear constellation precoding for ofdm with maximum multipath diversity and coding gains," IEEE Trans. grouping for OFDM with linear constellation precoding over multipath fading channels," IEEE Trans. Veh.

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International audienceA key challenge of future mobile communication research is to strike an attractive compromise between wireless network's area spectral efficiency and energy efficiency. This necessitates a clean-slate approach to wireless system design, embracing the rich body of existing knowledge, especially on multiple-input-multiple-ouput (MIMO) technologies. This motivates the proposal of an emerging wireless communications concept conceived for single-radio-frequency (RF) large-scale MIMO communications, which is termed as SM. The concept of SM has established itself as a beneficial transmission paradigm, subsuming numerous members of the MIMO system family. The research of SM has reached sufficient maturity to motivate its comparison to state-of-the-art MIMO communications, as well as to inspire its application to other emerging wireless systems such as relay-aided, cooperative, small-cell, optical wireless, and power-efficient communications. Furthermore, it has received sufficient research attention to be implemented in testbeds, and it holds the promise of stimulating further vigorous interdisciplinary research in the years to come. This tutorial paper is intended to offer a comprehensive state-of-the-art survey on SM-MIMO research, to provide a critical appraisal of its potential advantages, and to promote the discussion of its beneficial application areas and their research challenges leading to the analysis of the technological issues associated with the implementation of SM-MIMO. The paper is concluded with the description of the world's first experimental activities in this vibrant research field