TY - JOUR T1 - Link Adaptation for Rate Splitting Systems with Partial CSIT JF - IEEE Journal on Selected Areas in Communications Y1 - 2023 A1 - Carlos Mosquera A1 - Felipe Gómez-Cuba ER - TY - JOUR T1 - Link Adaptation and SINR errors in Practical Multicast Multibeam Satellite Systems with Linear Precoding JF - International Journal of Satellite Communications and Networking Y1 - 2020 A1 - Anxo Tato A1 - Stefano Andrenacci A1 - Eva Lagunas A1 - Symeon Chatzinotas A1 - Carlos Mosquera KW - link adaptation KW - multi-beam satellite KW - precoding KW - satellite communications ER - TY - THES T1 - Link Adaptation Techniques for Future Terrestrial and Satellite Communications T2 - Universidade de Vigo Y1 - 2019 A1 - Anxo Tato AB -
The increasing demand of access to data from the users and the enormous number of connected devices requires to enhance the capacity of the wireless networks. They must provide a higher throughput to serve all the requested traffic and they must accommodate the vast number of the Internet of the Things (IoT) devices. In this context, this thesis focus its attention on three different scenarios which have in common that they are a future evolution of current terrestrial and satellite communications systems. These scenarios are Mobile Satellite Systems (MSS), Fixed Satellite Systems (FSS) and next generation 5G networks.
The adoption of Dual Polarization (DP) in MSS along with Multiple Input Multiple Output (MIMO) signal processing techniques allows to double the capacity of previous systems with the same bandwidth and transmit power. On the other hand, the shift to more aggressive frequency reuse patterns in FSS can also provide remarkable gains in the capacity of High Throughput Satellites (HTS) for offering BroadBand Satellite Services (BBS). Linear precoding stands out as a technique to cope with the high level of interference which arises in this scenario. Lastly, energy efficient modulation schemes, like Spatial Modulation (SM) and its many variants, are being proposed for increasing the capacity of future 5G networks since they represent a good trade-off between spectral efficiency, energy efficiency and transmitter complexity.
Adaptive Coding and Modulation (ACM) technology is omnipresent in most of the communication standards since it enables a better exploitation of the system capacity by means of the adaptation of the Modulation and Coding Scheme (MCS). The link adaptation algorithm is responsible for selecting the optimum MCS, as well as other physical layer parameters in some cases, to adapt the transmission bit rate according to the instantaneous channel capacity of the time variant channel. Thus, link adaptation algorithms permit to increase the spectrum efficiency and guarantee a robust communication, adapting the level of redundancy of the coded information bits and the ruggedness of the modulation scheme.
In this thesis, several link adaptation algorithms are proposed for the three considered scenarios and its effectiveness is supported with simulations. Furthermore, an experimental validation of some algorithms is provided using a real satellite link, implemented with Software Defined Radio (SDR) technology. It is also studied how the carrier detection errors in the Channel State Information (CSI) affect linear precoding in FSS. The errors in the users Signal to Interference and Noise Ratio (SINR) that the gateway calculates to allocate MCS to the users is analyzed statistically and geographically. Moreover, a link adaptation algorithm with an adaptive margin per user is shown to allow a robust communication in the presence of SINR errors whereas the throughput of the system is barely compromised. In addition, a new method for making capacity calculations in SM and Generalized SM systems based on a neural network is proposed, which improves both accuracy and computational complexity with regard to the existing analytical approximations in the literature. With regard to MSS using DP, an adaptation mechanism is proposed in order to select the optimum MIMO mode and MCS which offer the highest throughput. Simulation results in a maritime mobile satellite channel show the dependence of the optimum MIMO mode with the average Signal to Noise Ratio (SNR), and how the spectral efficiency can be maximized whereas a target outage probability can be guaranteed. Lastly, the adaptation in SM systems is also addressed and several methods for deciding the coding rate in SM are given. These include the computation of the capacity prior to the adaptation, and also the use of a deep neural network. The latter offers very good results, with a spectral efficiency very close to the maximum achievable value.
In practice, data gathered by wireless sensor networks often belongs in a low-dimensional subspace, but it can present missing as well as corrupted values due to sensor malfunctioning and/or malicious attacks. We study the problem of Maximum Likelihood estimation of the low-rank factors of the underlying structure in such situation, and develop an Expectation-Maximization algorithm to this purpose, together with an effective initialization scheme. The proposed method outperforms previous schemes based on an initial faulty sensor identification stage, and is competitive in terms of complexity and performance with convex optimization-based matrix completion approaches.
JF - European Signal Processing Conference (EUSIPCO) CY - A Coruña, Spain ER - TY - CONF T1 - Link Adaptation and Carriers Detection Errors in Multibeam Satellite Systems with Linear Precoding T2 - 9th Advanced Satellite Multimedia Systems Conference (ASMS) and 15th Signal Processing for Space Communications Workshop (SPSC) Y1 - 2018 A1 - Anxo Tato A1 - Stefano Andrenacci A1 - Chatzinotas, S. A1 - Carlos Mosquera AB -The application of linear precoding at the gateway side enables broadband multibeam satellite systems to use more aggressive frequency reuse patterns increasing the overall capacity of future High Throughput Satellites (HTS). However, although some previous works about precoding consider imperfect CSIT (Chanel State Information at the Transmitter) adding some CSI estimation errors, that is not the main cause of CSI degradation. In practice, receivers can only detect and estimate a few coefficients of the CSI vector being the other nullified, replaced by zeros. This introduces errors in the SINR calculation by the gateway that lead to the assignment of Modulation and Coding Schemes (MCS) over the decoding possibilities of the users, increasing the rate of erroneous frames. In this work, the errors in the SINR calculation caused by the nullification of the CSI are analyzing statistically and geographically using a radiation diagram of 245 beams over Europe. Furthermore, a solution based on a link adaptation algorithm with a per user adaptive margin is proposed, helping to achieve the QEF (Quasi-error Free) target of DVB-S2X systems.
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.
Millimeter communication systems use large antenna arrays to provide good average received power and to take advantage of multi-stream MIMO communication. Unfortunately, due to power consumption in the analog front-end, it is impractical to perform beamforming and fully digital precoding at baseband. Hybrid precoding/combining architectures have been proposed to overcome this limitation. The hybrid structure splits the MIMO processing between the digital and analog domains, while keeping the performance close to that of the fully digital solution. In this paper, we introduce and analyze several algorithms that efficiently design hybrid precoders and combiners starting from the known optimum digital precoder/combiner, which can be computed when perfect channel state information is available. We propose several low complexity solutions which provide different trade-offs between performance and complexity. We show that the proposed iterative solutions perform better in terms of spectral efficiency and/or are faster than previous methods in the literature. All of them provide designs which perform close to the known optimal digital solution. Finally, we study the effects of quantizing the analog component of the hybrid design and show that even with coarse quantization, the average rate performance is good.
VL - 15 IS - 12 ER - TY - CONF T1 - Low Complexity Hybrid Sparse Precoding and Combining in Millimeter Wave MIMO Systems T2 - IEEE Int. Conference on Communications (ICC) Y1 - 2015 A1 - Cristian Rusu A1 - Roi Méndez-Rial A1 - Nuria González-Prelcic A1 - Robert W. Heath Jr. KW - compass KW - mmWave JF - IEEE Int. Conference on Communications (ICC) PB - IEEE CY - London, UK ER - TY - CONF T1 - Low Resolution Adaptive Compressed Sensing for mmWave MIMO receivers T2 - Asilomar Conf. on Signals, Systems, and Computers Y1 - 2015 A1 - C. Rusu A1 - Nuria González-Prelcic A1 - R.W. Heath Jr. KW - compass KW - mmWave JF - Asilomar Conf. on Signals, Systems, and Computers ER - TY - JOUR T1 - Learning-Based Adaptive Transmission for Limited Feedback Multiuser MIMO-OFDM JF - IEEE Transactions on Wireless Communications Y1 - 2014 A1 - Alberto Rico-Alvariño A1 - Robert W. Heath Jr. KW - adaptive signal processing KW - dynacs ER - TY - JOUR T1 - A Least Squares Approach to the Static Traffic Analysis of High-Latency Anonymous Communication Systems JF - IEEE Transactions on Information Forensics and Security Y1 - 2014 A1 - Fernando Pérez-González A1 - Carmela Troncoso A1 - Simon Oya ER - TY - CONF T1 - Low-Power Active Interference Cancellation for OFDM Spectrum Sculpting T2 - European Signal Processing Conference (EUSIPCO) Y1 - 2014 A1 - Schmidt, J.F. A1 - Daniel Romero A1 - R. López-Valcarce AB -Link adaptation in multiple user multiple-input multiple-output orthogonal frequency division multiplexing communication systems is challenging because of the coupling between user selection, mode selection, precoding, and equalization. In this paper, we present a methodology to perform link adaptation under this multiuser setting, focusing on the capabilities of IEEE 802.11ac. We propose to use a machine learning classifier to solve the problem of selecting a proper modulation and coding scheme, combined with a greedy algorithm that performs user and spatial mode selection. We observe that our solution offers good performance in the case of perfect channel state information or high feedback rate, while those scenarios with less feedback suffer some degradation due to inter-user interference.
JF - 21st European Signal Processing Conference 2013 (EUSIPCO 2013) CY - Marrakech, Morocco ER - TY - RPRT T1 - Least Squares Disclosure Attacks: User Profiling for Mix-based Anonymous Communication Systems Y1 - 2013 A1 - Fernando Pérez-González A1 - Carmela Troncoso PB - University of Vigo CY - Vigo ER - TY - CONF T1 - Link Adaptation in MIMO-OFDM with Practical Impairments T2 - Asilomar Conference on Signals Systems and Computers Y1 - 2013 A1 - Alberto Rico-Alvariño A1 - Robert W. Heath Jr. KW - dynacs KW - link adaptation KW - MIMO-OFDM JF - Asilomar Conference on Signals Systems and Computers ER - TY - CONF T1 - Localization of Forgeries in MPEG-2 Video through GOP Size and DQ analysis T2 - IEEE International Workshop on Multimedia Signal Processing (MMSP) Y1 - 2013 A1 - Daniele Labartino A1 - Tiziano Bianchi A1 - Alessia De Rosa A1 - Marco Fontani A1 - David Vázquez-Padín A1 - Alessandro Piva A1 - Mauro Barni AB -This work addresses forgery localization in MPEG-2 compressed videos. The proposed method is based on the analysis of Double Quantization (DQ) traces in frames that were encoded twice as intra (i.e., I-frames). Employing a state-of-the-art method, such frames are located in the video under analysis by estimating the size of the Group Of Pictures (GOP) that was used in the first compression; then, the DQ analysis is devised for the MPEG-2 encoding scheme and applied to frames that were intra-coded in both the first and second compression. In such a way, regions that were manipulated between the two encodings are detected. Compared to existing methods based on double quantization analysis, the proposed scheme makes forgery localization possible on a wider range of settings.
Top 10% Award
ER - TY - Generic T1 - Locating Tor hidden services through an interval-based traffic-correlation attack T2 - 2013 IEEE Conference on Communications and Network Security (CNS) Y1 - 2013 A1 - Juan A. Elices A1 - Fernando Pérez-González JF - 2013 IEEE Conference on Communications and Network Security (CNS) CY - Washington, DC ER - TY - CONF T1 - Low Complexity Primary User Protection for Cognitive OFDM T2 - European Signal Processing Conf. (EUSIPCO), Marrakech (Morocco) Y1 - 2013 A1 - Schmidt, J.F. A1 - R. López-Valcarce KW - cognitive radio KW - dynacs KW - spectrum shaping JF - European Signal Processing Conf. (EUSIPCO), Marrakech (Morocco) ER - TY - CONF T1 - A Least Squares approach to user profiling in pool mix-based anonymous communication systems. T2 - IEEE International Workshop on Information Forensics and Security (WIFS) Y1 - 2012 A1 - Fernando Pérez-González A1 - Carmela Troncoso JF - IEEE International Workshop on Information Forensics and Security (WIFS) CY - Tenerife, Spain ER - TY - JOUR T1 - Low-Complexity Channel Prediction Using Approximated Recursive DCT JF - Circuits and Systems I: Regular Papers, IEEE Transactions on Y1 - 2011 A1 - Schmidt, J.F. A1 - Cousseau, J.E. A1 - Wichman, R. A1 - Werner, S. KW - autoregressive modeling KW - autoregressive processes KW - basis expansion model KW - channel estimator KW - computational complexity KW - DCT KW - discrete cosine transform KW - discrete cosine transforms KW - Doppler frequencies KW - filter bank KW - Kalman filters KW - low-complexity channel prediction KW - OFDM modulation KW - OFDM systems KW - recursive formulation KW - steady-state Kalman filter KW - sum-of-sinusoids channel predictors KW - time-varying channels VL - 58 ER - TY - CONF T1 - Leaving Timing Channel Fingerprints in Hidden Service Log Files T2 - Digital Forensic Research Workshop Annual Conference (DFRWS) Y1 - 2010 A1 - Bilal Shebaro A1 - Fernando Pérez-González A1 - Jedidiah R. Crandall KW - data hiding KW - fingerprints KW - hidden services KW - timestamps KW - timing channel KW - tor network KW - watermarking JF - Digital Forensic Research Workshop Annual Conference (DFRWS) CY - Portland, Oregon ER - TY - JOUR T1 - Leaving Timing Channel Fingerprints in Hidden Service Log Files JF - Digital Investigation Y1 - 2010 A1 - Bilal Shebaro A1 - Fernando Pérez-González A1 - Jedidiah R. Crandall KW - data-hiding KW - fingerprints KW - hidden services KW - timestamps KW - timing channel KW - tor network KW - watermarking N1 - doi:10.1016/j.diin.2010.05.013 ER - TY - CONF T1 - Lattice implementation of Sum-squared Auto-correlation Minimization (SAM) channel shortener T2 - European Signal Processing Conference (EUSIPCO) Y1 - 2008 A1 - E. Ben Salem A1 - R. López-Valcarce A1 - S. Cherif A1 - H. Besbes KW - Blind Adaptation KW - Lattice KW - SAM JF - European Signal Processing Conference (EUSIPCO) CY - Lausanne, Switzerland ER - TY - JOUR T1 - Linear Boundary Extensions for Finite Length Signals and Paraunitary Two-Channel Filter Banks JF - IEEE Transactions on Signal Processing Y1 - 2004 A1 - M. Elena Domínguez-Jiménez A1 - Nuria González-Prelcic VL - 52 ER - TY - CONF T1 - Link Design for Satellite Based Services in the Fast Train Environment T2 - International Conference on Advanced Satellite Mobile Systems (ASMS) Y1 - 2003 A1 - Sandro Scalise A1 - Paolo Conforto A1 - Marcos Álvarez-Díaz A1 - Giorgio Sciascia A1 - Rodolfo Mura A1 - Harald Ernst KW - Digital Communications KW - satellite communications JF - International Conference on Advanced Satellite Mobile Systems (ASMS) CY - ESRIN, Frascati, Italy ER - TY - CONF T1 - Link Performance for Mobile Satellite Based Services in Ku-Band T2 - AIAA International Communications Satellite Systems Conference (ICSSC) Y1 - 2003 A1 - Giorgio Sciascia A1 - Sandro Scalise A1 - Harald Ernst A1 - Marcos Álvarez-Díaz A1 - Matthias Holzbock A1 - Rodolfo Mura KW - Digital Communications KW - satellite communications JF - AIAA International Communications Satellite Systems Conference (ICSSC) CY - Yokohama, Japan ER - TY - CONF T1 - A low complexity all-digital DS-SS transceiver for power-line communications T2 - International Symposium on Power Line Communications and Its Applications (ISPLC) Y1 - 2003 A1 - M. Ferreiro A1 - M. Cacheda A1 - C. Mosquera KW - DS-SS KW - modem KW - PLC JF - International Symposium on Power Line Communications and Its Applications (ISPLC) ER -