@article {984, title = {Neural Network Aided Computation of Mutual Information for Adaptation of Spatial Modulation}, journal = { IEEE Transactions on Communications}, year = {2020}, abstract = {

Index Modulations, in the form of Spatial Modulation or Polarized Modulation, are gaining traction for both satellite and terrestrial next generation communication systems. Adaptive Spatial Modulation based links are needed to fully exploit the transmission capacity of time-variant channels. The adaptation of code and/or modulation requires a real-time evaluation of the channel achievable rates. Some existing results in the literature present a computational complexity which scales quadratically with the number of transmit antennas and the constellation order. Moreover, the accuracy of these approximations is low and it can lead to wrong Modulation and Coding Scheme selection. In this work we apply a Multilayer Feedforward Neural Network to compute the achievable rate of a generic Index Modulation link. The case of two antennas/polarizations is analyzed in depth, showing not only a one-hundred fold decrement of the Mean Square Error in the estimation of the capacity as compared with existing analytical approximations, but also a fifty times reduction of the computational complexity. Moreover, the extension to an arbitrary number of antennas is explained and supported with simulations. More generally, neural networks can be considered as promising candidates for the practical estimation of complex metrics in communication related settings.

}, keywords = {ACM, Adaptive Communications, Capacity, Index Modulation, link adaptation, Machine Learning, MFNN, Mutual Information, neural networks, Polarized Modulation, Spatial Modulation}, isbn = {1558-0857 }, issn = {0090-6778 }, doi = {https://doi.org/10.1109/TCOMM.2020.2974215}, author = {Anxo Tato and Carlos Mosquera and Pol Henarejos and Ana P{\'e}rez Neira} } @conference {965, title = {Neural Network Aided Computation of Generalized Spatial Modulation Capacity}, booktitle = {27th European Signal Processing Conference (EUSIPCO)}, year = {2019}, address = {A Coru{\~n}a (Spain)}, abstract = {

Generalized Spatial Modulation (GSM) is being considered for future high-capacity and energy efficient terrestrial networks. A variant such as Polarized Modulation (PMod) has also a role in Dual Polarization Mobile Satellite Systems. The implementation of adaptive GSM systems requires fast methods to evaluate the channel dependent GSM capacity, which amounts to solve multi-dimensional integrals without closed-form solutions. For this purpose, we propose the use of a Multilayer Feedforward Neural Network and an associated feature selection algorithm. The resulting method is highly accurate and with much lower complexity than alternative numerical methods.

}, keywords = {Generalized Spatial Modulation, Index Modulations, Machine Learning, Multilayer Feedforward Neural Network, Polarized Modulation}, author = {Anxo Tato and Carlos Mosquera and Pol Henarejos and Ana P{\'e}rez-Neira} } @conference {923, title = {Channel dependent Mutual Information in Index Modulations}, booktitle = {ICCASP, IEEE International Conference on Acoustics, Speech, and Signal Processing}, year = {2018}, abstract = {

Mutual Information is the metric that is used to perform link adaptation, which allows to achieve rates near capacity. The computation of adaptive transmission modes is achieved by employing the mapping between the Signal to Noise Ratio and the Mutual Information. Due to the high complexity of the computation of the Mutual Information, this process is performed off-line via Monte Carlo simulations, whose results are stored in look-up tables. However, in Index Modulations, such as Spatial Modulation or Polarized Modulation, this is not feasible since the constellation and the Mutual Information are channel dependent and it would require to compute this metric at each time instant if the channel is time varying. In this paper, we propose different approximations in order to obtain a simple closed-form expression that allows to compute the Mutual Information at each time instant and thus, making feasible the link adaptation.

}, author = {Pol Henarejos and Ana P{\'e}rez-Neira and Anxo Tato and Carlos Mosquera} } @conference {934, title = {Practical Implementation of Link Adaptation with Dual Polarized Modulation (Best paper award)}, booktitle = {11th International Symposium on Communication Systems, Networks, and Digital Signal Processing.}, year = {2018}, author = {Anxo Tato and Carlos Mosquera and Pol Henarejos and Ana P{\'e}rez-Neira} } @proceedings {909, title = {Link Adaptation Algorithms for Dual Polarization Mobile Satellite Systems}, journal = {9th EAI International Conference on Wireless and Satellite Systems, WISATS}, volume = {Wireless and Satellite Systems}, year = {2017}, month = {2018}, pages = {52-61}, publisher = {Springer International Publishing}, address = {Oxford}, abstract = {

The use of dual polarization in mobile satellite systems is
very promising as a means for increasing the transmission capacity. In this paper a system which uses simultaneously two orthogonal polarizations in order to communicate with the users is studied. The application of MIMO signal processing techniques along with Adaptive Coding and Modulation in the forward link can provide remarkable throughput gains up to 100 \% when compared with the single polarization system. The gateway is allowed to vary the MIMO and Modulation\  and Coding Schemes for each frame. The selection is done by means of a link adaptation algorithm which uses a tunable margin to achieve a predefined target Frame Error Rate.

}, issn = {978-3-319-76571-6}, author = {Anxo Tato and Pol Henarejos and Carlos Mosquera and Ana P{\'e}rez-Neira} } @conference {841, title = {Advanced Signal Processing Techniques for Fixed and Mobile Satellite Communications}, booktitle = {8th Advanced Satellite Multimedia Systems Conference 14th Signal Processing for Space Communications Workshop}, year = {2016}, month = {09/2016}, keywords = {compass, full duplex, satcom}, author = {Pol Henarejos and Ana P{\'e}rez-Neira and Nicol{\`o} Mazzali and Carlos Mosquera} } @conference {822, title = {Pushing for higher rates and efficiency in Satcom: the different perspectives within SatNExIV}, booktitle = {Twelfth International Symposium on Wireless Communication Systems (ISWCS)}, year = {2015}, address = {Brussels}, keywords = {satcom}, author = {Miguel {\'A}ngel V{\'a}zquez and Ana P{\'e}rez Neira and Carlos Mosquera and Bhavani Shankar and Pol Henarejos and Athanasios Panagopoulos and Giovanni Giambene and Vasilios Siris and George Polyzos and Nader Alagha} }