Pol Henarejos - Academia.edu (original) (raw)

Papers by Pol Henarejos

arXiv (Cornell University), Jul 14, 2023

SatNEx IV project aims at studying medium and long term directions of satellite telecommunication... more SatNEx IV project aims at studying medium and long term directions of satellite telecommunication systems for any of the commercial or institutional applications that can be considered appealing by key players although still not mature enough for attracting industry or initiating dedicated ESA R&D activities. This paper summarizes the first year activities identified as very promising techniques for next generation satellite communication systems. Concretely, very high throughput satellite trunking, physical layer advances for fullduplex and multipolarization systems, network coding applications and multiple access schemes for information centric networking are briefly presented. For all the activities, we identify the scenarios under study so as the preliminary technical solutions to be further investigated.

In this paper we propose and investigate a cross-layer multiuser scheduling strategy for the supp... more In this paper we propose and investigate a cross-layer multiuser scheduling strategy for the support of heterogeneous traffic in the downlink of a MIMO-OFDMA system. It jointly considers different objectives: maximize the sum-rate on the radio channel, ensure a fair allocation of resources among users belonging to the same traffic class, consider the dynamics of traffic sources by looking at the delay of data packets in the queues, contribute to maximize quality of service figures at the application level. To exploit temporal diversity and to reduce complexity, the ergodic weighted sum-rate is maximized and dual optimization with stochastic approximation is applied to derive on-line algorithms. The numerical results show the capability of the scheduler to allocate physical layer resources according to rate constraints imposed for each different traffic class and with fairness inside each class, even in presence of different channels conditions and different network loads.

Signal Processing, Dec 1, 2012

ABSTRACT This paper presents a low-complexity algorithm for multiuser scheduling and resource all... more ABSTRACT This paper presents a low-complexity algorithm for multiuser scheduling and resource allocation in the Multiple Input Single Output (MISO) downlink channel with Orthogonal Frequency Division Multiple Access (OFDMA). The goal of the algorithm is to maximize the sum-rate on the radio channel and to ensure that the rate assignment is suitably balanced among users. The proposed algorithm uses partial Channel State Information (CSI) and therefore has a reduced feedback requirement. It also allows an on-line implementation, based on an ergodic optimization framework with dual optimization and stochastic approximation. Performance and complexity reduction are quantified by considering comparison with other solutions in a realistic single-cell system configuration. It is shown that the algorithm is effective to balance average rate among users even in heterogeneous and non-stationary channel conditions with lower computational complexity and feedback requirements.

IEEE Transactions on Communications, Nov 1, 2018

In this paper we present a novel modulation technique for dual polarization communication systems... more In this paper we present a novel modulation technique for dual polarization communication systems, which reduces the error rate compared with the existent schemes. This modulation places the symbols in a 3D constellation, rather than the classic approach of 2D. Adjusting the phase of these symbols depending on the information bits, we are able to increase the bit rate. Hence, the proposed scheme conveys information by selecting both polarization state and the phase of radiated electromagnetic wave. We also analyse the performance of 3D Polarized Modulation (PMod) for different constellation sizes and we obtain a curve of rate adaptation. Finally, we compare the proposed 3D PMod with other existing schemes such as single polarization Phase Shift Keying (PSK) and double polarization Vertical Bell Laboratories Layer Space-Time (V-BLAST), both carrying the same number of information bits. The results show that 3D PMod always outperforms all other schemes, except for low order modulation. Therefore, we can conclude that 3D PMod is an excellent candidate for medium and high modulation order transmissions.

IEEE Transactions on Communications, Oct 1, 2015

This paper presents the novel application of Polarized Modulation (PMod) for increasing the throu... more This paper presents the novel application of Polarized Modulation (PMod) for increasing the throughput in mobile satellite transmissions. One of the major drawbacks in mobile satellite communications is the fact that the power budget is often restrictive, making unaffordable to improve the spectral efficiency without an increment of transmitted power. By using dual polarized antennas in the transmitter and receiver, the PMod technique achieves an improvement in throughput of up to 100% with respect to existing deployments, with an increase of less than 1 dB at low E b /N0 regime. Additionally, the proposed scheme implies minimum hardware modifications with respect to the existing dual polarized systems and does not require additional channel state information at the transmitter; thus it can be used in current deployments. Demodulation (i.e. detection and decoding) alternatives, with different processing complexity and performance, are studied. The results are validated in a typical mobile interactive scenario, the newest version of TS 102 744 standard (Broadband Global Area Network (BGAN)), which aims to provide interactive mobile satellite communications.

Upcoming modern communications are based on 5G specifications and aim at providing solutions for ... more Upcoming modern communications are based on 5G specifications and aim at providing solutions for novel vertical industries. One of the major changes of the physical layer is the use of Low-Density Parity-Check (LDPC) code for channel coding. Although LDPC codes introduce additional computational complexity compared with the previous generation, where Turbocodes where used, LDPC codes provide a reasonable trade-off in terms of complexity-Bit Error Rate (BER). In parallel to this, Deep Learning algorithms are experiencing a new revolution, specially to image and video processing. In this context, there are some approaches that can be exploited in radio communications. In this paper we propose to use Autoencoding Neural Networks (ANN) jointly with a Deep Neural Network (DNN) to construct Autoencoding Deep Neural Networks (ADNN) for demapping and decoding. The results will unveil that, for a particular BER target, 3 dB less of Signal to Noise Ratio (SNR) is required, in Additive White Gaussian Noise (AWGN) channels.

arXiv (Cornell University), 2015

5G has a main requirement of highly flexible, ultralow latency and ultra-high bandwidth virtualiz... more 5G has a main requirement of highly flexible, ultralow latency and ultra-high bandwidth virtualized infrastructure in order to deliver end-to-end services. This requirement can be met by efficiently integrating all network segments (radio access, aggregation and core) with heterogeneous wireless and optical technologies (5G, mmWave, LTE/LTE-A, Wi-Fi, Ethernet, MPLS, WDM, software-defined optical transmission, etc.), and massive computing and storage cloud services (offered in edge/core data centers). This paper introduces the preliminary architecture aiming at integrating three consolidated and standalone experimental infrastructures at CTTC, in order to deploy the required end-to-end top-to-bottom converged infrastructure pointed out above for testing and developing advanced 5G services.

The use of dual polarization in mobile satellite systems is very promising for increasing the cha... more The use of dual polarization in mobile satellite systems is very promising for increasing the channel capacity. Polarized Modulation is proposed in this paper for use in practical systems, by providing simple equations for computing its capacity and featuring a link adaptation algorithm. This scheme shows remarkable gains in the spectral efficiency when compared with single polarization and other multi-antenna techniques such as V-BLAST. Polarized Modulation is a particular instance of more general Index Modulations, which are being considered for 5G networks. Thus, the proposed link adaptation algorithm could find synergies with current activities for future terrestrial networks.

IEEE Transactions on Communications, May 1, 2020

Index Modulations, in the form of Spatial Modulation or Polarized Modulation, are gaining tractio... more 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.

Interference Management is a vast topic present in many disciplines. The majority of wireless sta... more Interference Management is a vast topic present in many disciplines. The majority of wireless standards suffer the drawback of interference intrusion and the network efficiency drop due to that. Traditionally, interference management has been addressed by proposing signal processing techniques that minimize their effects locally. However, the fast evolution of future communications makes difficult to adapt to new era. In this paper we propose the use of Deep Learning techniques to present a compact system for interference management. In particular, we describe two subsystems capable to detect the presence of interference, even in high Signal to Interference Ratio (SIR), and interference classification in several radio standards. Finally, we present results based on real signals captured from terrestrial and satellite networks and the conclusions unveil the courageous future of AI and wireless communications.

arXiv (Cornell University), Jul 25, 2018

Mutual Information is the metric that is used to perform link adaptation, which allows to achieve... more 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.

Zenodo (CERN European Organization for Nuclear Research), Aug 28, 2017

In this paper, we employ the non-orthogonal multiple access (NOMA) technique to convey joint broa... more In this paper, we employ the non-orthogonal multiple access (NOMA) technique to convey joint broadcast and multicast streams to a set of users. Thanks to the spatial beamforming, different groups of users is able to receive different streams in addition to the common broadcast information. With the proposed scheme, the same time-frequency resources can be shared between different streams, without requiring additional bandwidth. The transmitter implementation is presented and two receiver classes are considered based on Successive Interference Cancellation (SIC) and Joint Decoding (JD) approaches. In addition to the performance assessment via simulation, a real hardware proof of concept implementation of the proposed technique is performed in order to show the practical viability of the proposed scheme.

arXiv (Cornell University), Jul 16, 2020

Second, I also would thank to my family. They are always to my side. They interest for all my job... more Second, I also would thank to my family. They are always to my side. They interest for all my jobs and specially with this master thesis. Thanks, thanks, thanks. Third, to my CTTC colleges. Most of them are at the same situation as me. And they also know the hard task of combining the normal job and the PhD. pursue. There are not enough coffees to thank you. Finally, and not less important, to my advisor. She guided me for many years and advised me to get my results, even before ending my degree. Thank you, Ana. And if you are reading this and you do not know who am I, also thank you. Probably you arrived here motivated by finding solutions to your problems. I bet that I have not any of them. But I hope to wake up an interest on you about the passionate world of implementing theoretical technologies to real devices.

Generalized Spatial Modulation (GSM) is being considered for future high-capacity and energy effi... more 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.

IEEE Communications Magazine, Feb 1, 2021

This paper introduces the application of machine learning (ML)-based procedures in real-world sat... more This paper introduces the application of machine learning (ML)-based procedures in real-world satellite communication operations. While the application of ML in image processing has led to unprecedented advantages in new services and products, the application of ML in wireless systems is still on its infancy. In particular, this paper focuses on the introduction ML-based mechanisms in satellite network operation centers such as interference detection, flexible payload configuration and congestion prediction. Three different use cases are described and the proposed ML models are introduced. All the models have been constructed using real data and considering current operations. As reported in the numerical results, the ML-based proposed techniques can improve a certain key performance indicator of each use case at least a 10%. In light of the results, the proposed techniques are useful in the process of automating satellite communication systems.

arXiv (Cornell University), Mar 20, 2018

This work presents a resource allocation algorithm in K-user, M-subcarrier and NT-antenna systems... more This work presents a resource allocation algorithm in K-user, M-subcarrier and NT-antenna systems for on-line scheduling. To exploit temporal diversity and to reduce complexity, the ergodic sum rate is maximized instead of the instantaneous one. Dual optimization is applied to further diminish complexity together with a stochastic approximation, which is more suitable for online algorithms. Weighted sum rate is considered so that users can be either prioritized by higher layers or differentiated by proportional rate constraints. The performance and complexity of this algorithm is compared with well-known benchmarks and also evaluated under real system conditions for the MIMO Broadcast channel.

arXiv (Cornell University), Jul 15, 2020

(Spain) 2. Eutelsat, Paris (France) 3. GMV Aerospace and Defense, Tres Cantos (Spain) 4. Reply, T... more (Spain) 2. Eutelsat, Paris (France) 3. GMV Aerospace and Defense, Tres Cantos (Spain) 4. Reply, Turin (Italy) 5 .