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This paper presents an estimation approach within the framework of uplink massive machine-type-communications (mMTC) that considers the energy limitations of the devices. We focus on a scenario where a group of sensors observe a set of parameters and send the measured information to a collector node (CN). The CN is responsible for estimating the original observations, which are spatially correlated and corrupted by measurement and quantization noise. Given the use of Gaussian sources, the minimum mean squared error (MSE) estimation is employed and, when considering temporal evolution, the use of Kalman filters is studied. Based on that, we propose a device selection strategy to reduce the number of active sensors and a quantization scheme with adjustable number of bits to minimize the overall payload. The set of selected sensors and quantization levels are, thus, designed to minimize the MSE. For a more realistic analysis, communication errors are also included by averaging the MSE over the error decoding probabilities. We evaluate the performance of our strategy in a practical mMTC system with synthetic and real databases. Simulation results show that the optimization of the payload and the set of active devices can reduce the power consumption without compromising the estimation accuracy. ; The work presented in this paper has been carried out within the framework of the project ROUTE56 (PID2019-104945GB-I00/ AEI/10.13039/501100011033) funded by the Agencia Estatal de Investigación (Spanish Ministry of Science and Innovation); the FPI grant BES-2017-079994, funded by the Spanish Ministry of Science, Innovation and Universities; and the grant 2017 SGR 578, funded by the Catalan Government (AGAUR, Departament de Rercerca i Universitats, Generalitat de Catalunya). ; Peer Reviewed ; Postprint (author's final draft)

Within the framework of 5G, blockage effects occurring in the mmWave band are critical. Previous works describe the effects of blockages in isolated and multiple links for simple blocking objects, modeled with mathematical tools such as stochastic geometry and random shape theory. Our study uses these tools to characterize a scenario with N links, including the possible correlation among them in terms of blocking for several models of blocking objects. We include numerical evaluations highlighting that assuming independence among the links' blocking elements is a too-brief simplification and does not accurately describe the real scenario. This paper also applies the formulation developed for the case of N links to optimize the relay positioning in mmWave cells for coverage enhancement, that is, to minimize the communication failure probability. We also show that both link budget and blockages affect the optimum positioning of the relays as they are both essential for successful transmission. ; The work presented in this paper has been funded through the projects 5G&B-RUNNER-UPC (Agencia Estatal de Investigación and Fondo Europeo de Desarrollo Regional, TEC2016-77148-C2-1-R / AEI/FEDER, UE) and ROUTE56 (Agencia Estatal de Investigación, PID2019- 104945GB-I00 / AEI / 10.13039/501100011033); and the grant 2017 SGR 578 (Catalan Government—Secretaria d'Universitats i Recerca, Departament d'Empresa i Coneixement, Generalitat de Catalunya, AGAUR). ; Peer Reviewed ; Postprint (published version)

© 2020 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes,creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works. ; Machine-type-communications (MTC) are crucial in the evolution of mobile communication systems. Within this context, we distinguish the so-called massive MTC (mMTC), where a large number of devices coexist in the same geographical area. In the case of sensors, a high correlation in the collected information is expected. In this letter, we evaluate the impact of correlation on the entropy of a set of quantized Gaussian sources. This model allows us to express the sensed data with the data correlation matrix. Given the nature of mMTC, these matrices may be well approximated as rank deficient. Accordingly, we exploit this singularity to design a technique for switching off several sensors that maximizes the entropy under power-related constraints. The discrete optimization problem is transformed into a convex formulation that can be solved numerically. ; This work is supported by the project 5G&B RUNNER-UPC (TEC2016-77148-C2-1-R (AEI/FEDER, UE)) and the research network RED2018-102668-T Red COMONSENS (funded by the Spanish Ministry of Science,Innovation and Universities), the fellowship FPI BES-2017-079994, and the grant 2017 SGR 578 (funded by the Catalan Government - AGAUR). ; Peer Reviewed ; Postprint (author's final draft)

This paper presents the experimental evaluation of an interference-mitigation scheme tailored for heterogeneous multi-cell LTE-based systems. The real-time FPGA-based system implementation was evaluated under realistic operating conditions using the GEDOMIS® testbed. An intensive measurement campaign was conducted to assess the performance-gains of the proposed scheme, considering mobile channels and various levels of noise and interference. ; Grant numbers : This work was partially supported by: the Spanish Government under projects TEC2011-29006-C03-01 (GRE3N-PHY).© 2014 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.

The proceeding at: IEEE 76th Vehicular Technology Conference, took place Québec (Canada), in 2012, September 3-6. The event Web site at: http://www.ieeevtc.org/vtc2012fall/ ; This work deals with the problem of radio resource allocation in a point-to-point multiple-input multiple-output (MIMO) communications system with feedback of channel state information. A total pool of radio resources (power and transmission time) is allocated among training, feedback, and data transmission phases in order to maximize system performance in terms of throughput. The energy consumption associated to the base band signal processing and decoding is also evaluated. This resource allocation problem is studied analytically in a twoway time division duplex (TDD) communications scenario with time correlated channels, where the effect of feedback errors and feedback delay is also taken into account. ; The research leading to these results has received funding from the European Cooperation in Science and Technol-ogy under project COST Action IC0902, from the Spanish Ministry of Economy and Competitiveness (Ministerio de Econom´ıa y Competitividad) under projects TEC2011-29006-C03-02 (GRE3N-LINK-MAC) and TEC2011-29006-C03-03 (GRE3N-SYST), and from the Catalan Government under grant 2009 SGR 891. ; Publicado

The proceeding at: 3rd International Workshop on Cognitive Information Processing (CIP 2012), took place 2012, May 28-30, in Baiona, España. The event Web site at http://cip2012.tsc.uc3m.es/ ; In this work we consider the optimization of the power assigned to the user streams in a coordinated base station downlink environment with Orthogonal Frequency Division Modulation (OFDM). In this scenario the base stations perform distributed cooperative processing with a block diagonalization scheme to remove interference among users. Two schemes based on the waterfilling technique are proposed and compared to the optimal solution, which can be obtained numerically, by using convex optimization. We show that the proposed schemes achieve a performance, in terms of weighted sum rate, very close to the optimal, without the heavy computational complexity required by the numerical solution. These sum rates are compared in a simplified scenario consisting of two-user and two-cell. Other more realistic multicell scenario and some examples of achievable rates are presented too. ; The research leading to these results has received funding from the Spanish Government under coordinated projects TEC2008-06327-C03-01/02/03 (MULTI-ADAPTIVE) and TEC2011-29006-C03-01/02/03 (GRE3N) and from EU FP7 project INFSO-ICT-247223 ARTIST 4G. ; Publicado

Interference is a major obstacle in radio communications, especially when opportunistic frequency reuse is an inherent requirement for maximising spectral efficiency in heterogeneous networks. A typical example is encountered in cellular communications where macrocell-edge users receive interference from small cell transmissions that use the same radio frequency band. Innovating interference management algorithms are employed towards this end, which because of their interdependencies with numerous parameters of the target operating scenario and various low-level implementation aspects, need to be prototyped in real-time signal processing platforms in order to be credibly verified. In this paper, we present the development and experimental validation of a macrocell/femtocell coexistence scenario in close to real-life conditions. The inclusion of an agile interference management scheme increased the signal processing complexity at the physical layer. This overhead was appropriately addressed by engaging advanced parallel processing techniques, optimisations of the arithmetic operations and intelligent reuse of logic and memory resources in the field programmable gate array (FPGA)-based baseband processing architecture. ; Grant number : Spanish Ministry of Economy and Competitiveness (Ministerio de Economía y Competitividad) under projects and TEC2011-29006-C03-01 (GRE3N-PHY), and from the Catalan Government under grant 2009 SGR 1046 (SGR-RC).

In this paper, we present an asymptotic analysis of the behavior of a network where the mobile terminals are considered to be battery-powered devices provided with energy harvesting capabilities. The asymptotic analysis is based on a multiuser MIMO resource allocation strategy where the battery status of the mobile terminals are considered explicitly in the proposed allocation policy. We provide some numerical results and analytic expressions of the expected value of the data rates and the battery levels for different decoding power consumption models when convergence is attained. ; Grant numbers : The research leading to these results has received funding from the Spanish Ministry of Economy and Competitiveness (Ministerio de Economía y Competitividad) under projects TEC2011-29006- C03-01 (GRE3N-PHY), and from the Catalan Government under grant 2009 SGR 891.© 2014 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.

The proceeding at: 20th European Wireless 2014, took place 2014, May 14-16, in Barcelona, Spain. ; In this paper, we present an asymptotic analysis of the behavior of a network where the mobile terminals are considered to be battery-powered devices provided with energy harvesting capabilities. The asymptotic analysis is based on a multiuser MIMO resource allocation strategy where the battery status of the mobile terminals are considered explicitly in the proposed allocation policy. We provide some numerical results and analytic expressions of the expected value of the data rates and the battery levels for different decoding power consumption models when convergence is attained. ; The research leading to these results has received funding from the European Commission in the framework of the FP7 Network of Excellence in Wireless COMmunications NEWCOM# (Grant agreement no. 318306), from the Spanish Ministry of Economy and Competitiveness (Ministerio de Economia y Competitividad) under projects TEC2011-29006-C03-01 (GRE3N-PHY), TEC2011-29006-C03-02 (GRE3N-LINK-MAC), TEC2011-29006-C03-03 (GRE3N-SYST) and FPI grant BES-2012-052850, and from the Catalan Government under grant 2009 SGR 891. ; Publicado

Proceeding at: IEEE 8th Sensor Array and Multichannel Signal Processing Workshop (SAM), took place 2014, Jun, 22-25 in Coruña (españa). The event web site of http://www.gtec.udc.es/sam2014/ . ; Characterizing the energy cost of different physical (PHY) layer building blocks is becoming increasingly important in modern cellular-based communications, considering the cross sector requirements for performance enhancements and energy savings. This paper presents energy profiling metrics of different PHY-layer FPGA implementations encountered in modern wireless communication systems. The results give an insight of the distribution of the consumed energy in different baseband building blocks or configurations before and after applying power optimizations in the FPGA design and implementation. ; This work was partially supported by: the Spanish Government under projects TEC2011-29006-C03-01 (GRE3N-PHY), TEC2011-29006-C03-02 (GRE3N-LINKMAC) and TEC2011-29006-C03-03 (GRE3N-SYST); and the European Commission under project NEWCOM# (GA 318306). ; Publicado

Characterizing the energy cost of different physical (PHY) layer building blocks is becoming increasingly important in modern cellular-based communications, considering the cross sector requirements for performance enhancements and energy savings. This paper presents energy profiling metrics of different PHY-layer FPGA implementations encountered in modern wireless communication systems. The results give an insight of the distribution of the consumed energy in different baseband building blocks or configurations before and after applying power optimizations in the FPGA design and implementation. ; Grant numbers : This work was partially supported by: the Spanish Government under projects TEC2011-29006-C03-01 (GRE3N-PHY).© 2014 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.