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A video presenting this paper is available in YouTube here: http://www.youtube.com/watch?v=cNgCJK4oimM&feature=youtu.be; A key challenge of future mobile communications 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-Output (MIMO) technologies. This motivates the proposal of an emerging wireless communications concept conceived for single-RF large-scale MIMO communications, which is termed as Spatial Modulation (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 inter-disciplinary 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.

In this paper, we address the relay assignment in cooperative networks based on order statistics. We consider a network comprising a cluster of transmitting sources, a cluster of relay nodes and a single destination. This is motivated by the fact that the existing relay assignment schemes don't achieve diversity for the network configuration under consideration. We assume that the cooperation is in the amplify-and-forward (AF) mode, but proposed scheme is applicable to the decode-and-forward (DF) mode. In the relay assignment process, the source nodes that have weaker source-destination links, have higher priority in relay selection. We analyze the probability density function (PDF) and the average bit error rate (BER) for the proposed scheme where we invoke important results that we first derive for simple two-hop networks. Specifically, we calculate the exact expression for the PDF of the end-to-end signal-to-noise ratio (SNR). Compared to other relay assignment schemes (like maximizing sum of SNR values or maximizing the minimum selected SNR), the proposed scheme has the advantages of simplicity, higher diversity order and fairness.

This paper deals with relay assignment in cooperative networks based on the max-min criterion. A simple algorithm is proposed in order to find the optimum relay assignment permutation to avoid brute-force prohibitive search method. It is assumed that there are N source-destination pairs and M relays in the network. The problem is how to assign each relay to a source-destination pair in order to achieve the highest diversity order. The proposed algorithm achieves the maximum spatial diversity for all of the nodes and leads us to simplify the analysis and simulation of the optimal answer. It is shown that the Probability Density Function (PDF) of the end-to-end signal-to-noise ratio (SNR) after relay assignment can be expressed as a weighted sum of the order statistics of the PDF of individual end-to-end links. Since the analytical calculation of the weighting coefficients in the mentioned weighting sum becomes difficult, we propose an approximation in order to calculate the mentioned weighting coefficients. The validity of this fit is shown through some simulations.