Closed-form multicast precoding for satellite flexible payloads

This paper investigates a novel closed-form noniterative precoding technique for multicast multibeam satellite systems. Next-generation satellite systems will be benefited from the flexible use of the satellite resources especially its power flexible allocation among beams. Intending to obtain a low-computational complexity design, we revisit the well-known signal-to-leakage-and-noise ratio design for multicast transmission. Two alternatives are introduced considering both the physical meaning of the ratio and certain multicast channel vector mapping. We observe the benefits of these techniques in satellite flexible payloads. The proposed technique shows a substantial gain compared to the benchmark according to the numerical simulations. Intuitive insights on the precoding behaviour are also presented.This work is funded by Ministry of Science, Innovation and Universities, Spain, under project TERESA -TEC2017-90093-C3-1-R (AEI/FEDER, UE) and by Catalan government under the grant 2017-SGR-01479.Peer ReviewedPostprint (author's final draft

Shared access satellite-terrestrial reconfigurable backhaul network enabled by smart antennas at mm-wave band

© 2018 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.5G traffic expectations require not only the appropriate access infrastructure, but also the corresponding backhaul infrastructure to ensure a well-balanced network scaling. Optical fibre and terrestrial wireless backhaul will hardly meet 100% coverage and satellite must be considered within the 5G infrastructure to boost ubiquitous and reliable network utilization. This work presents the main outcomes of SANSA project, which proposes a novel solution that overcomes the limitations of the traditional fixed backhaul. It is based on a dynamic integrated satelliteterrestrial backhaul network operating on the mm-wave band. Its key principles are a seamless integration of the satellite segment into terrestrial backhaul networks; a terrestrial wireless network capable of reconfiguring its topology according to traffic demands; and an aggressive frequency reuse within the terrestrial segment and between terrestrial and satellite segments. The two technological enablers of SANSA are smart antenna techniques at mm-wave and a software defined intelligent hybrid network management. This article introduces these 5G enablers, which permit satellite communications to play a key role in different 5G use cases, from the early deployment of 5G services in sparse scenarios to enhanced mobile broadband in denser scenarios.Peer ReviewedPostprint (author's final draft

Kinetic and stoichiometric characterization of anoxic sulfideoxidation by SO-NR mixed cultures from anoxic biotrickling filters.

Monitoring the biological activity in biotrickling filters is difficult since it implies estimating biomass concentration and its growth yield, which can hardly be measured in immobilized biomass systems. In this study, the characterization of a sulfide-oxidizing nitrate-reducing biomass obtained from an anoxic biotrickling filter was performed through the application of respirometric and titrimetric techniques. Previously, the biomass was maintained in a continuous stirred tank reactor under steady-state conditions resulting in a growth yield of 0.328±0.045 g VSS/g S. To properly assess biological activity in respirometric tests, abiotic assays were conducted to characterize the stripping of CO2 and sulfide. The global mass transfer coefficient for both processes was estimated. Subsequently, different respirometric tests were performed: (1) to solve the stoichiometry related to the autotrophic denitrification of sulfide using either nitrate or nitrite as electron acceptors, (2) to evaluate the inhibition caused by nitrite and sulfide on sulfide oxidation, and (3) to propose, calibrate, and validate a kinetic model considering both electron acceptors in the overall anoxic biodesulfurization process. The kinetic model considered a Haldane-type equation to describe sulfide and nitrite inhibitions, a non-competitive inhibition to reflect the effect of sulfide on the elemental sulfur oxidation besides single-step denitrification since no nitrite was produced during the biological assays

Antenna array configurations for massive MIMO outdoor base stations

Massive MIMO predicts unprecedented capacity and energy efficiency improvements in future networks, by the use of base stations with hundreds of antennas. However the crucial question of determining suitable, or even optimal, antenna hardware solutions for deploying such a large number of antennas in constrained physical spaces is still open. Here we analyse the potential benefits of using compact arrays, dual-polarized arrays, and 2D arrays in outdoor scenarios using a realistic 3D spatial channel model and accurate antenna electromagnetic simulations. In particular we show that it is detrimental to reduce the distance between elements below ¿/3. Actually, better performances can be achieved by increasing the number of antennas using dual polarization instead (if random polarization of user antennas is assumed). We also show that good performance can be achieved by using 2D arrays, but at the expense of an increased number of total elements when compared to horizontal linear arrays. © 2014 IEEE.Peer ReviewedPostprint (published version

Low-cost hybrid analog-digital beamformer evaluation in spectrum sharing systems

This paper evaluates different analog-digital beam-forming solutions for future spectrum sharing mm-wave scenarios. In contrast to sub-6 GHz multiantenna schemes where all-digital solutions provide an excellent performance-cost tradeoff, in the mm-wave bands where a very large number of antennas is required, all-digital designs cannot be deployed due to their cost and complexity. In order to solve this problem, sub-array solutions are conceived such that a reduced number of radiofrequency chains are simultaneously connected to different antennas through an analog beamforming network formed by phase shifters (i.e. with no amplitude control). Different connectivity solutions are evaluated; namely, full-connected, localized and interleaved considering that either the phase shifters have full resolution or only one control bit. As reported in the paper, while for the full resolution case the same performance is obtained for all connectivity schemes, in case the phase shifters have one control bit, differences show up. The numerical evaluation is done with an alternating feasible point pursuit successive convex approximation (FPP-SCA) optimization which yields to efficient solutions even for this non-convex optimization problem.Peer Reviewe

Antenna array configurations for massive MIMO outdoor base stations

Massive MIMO predicts unprecedented capacity and energy efficiency improvements in future networks, by the use of base stations with hundreds of antennas. However the crucial question of determining suitable, or even optimal, antenna hardware solutions for deploying such a large number of antennas in constrained physical spaces is still open. Here we analyse the potential benefits of using compact arrays, dual-polarized arrays, and 2D arrays in outdoor scenarios using a realistic 3D spatial channel model and accurate antenna electromagnetic simulations. In particular we show that it is detrimental to reduce the distance between elements below ¿/3. Actually, better performances can be achieved by increasing the number of antennas using dual polarization instead (if random polarization of user antennas is assumed). We also show that good performance can be achieved by using 2D arrays, but at the expense of an increased number of total elements when compared to horizontal linear arrays. © 2014 IEEE.Peer Reviewe

Hybrid analog-digital transmit beamforming for spectrum sharing satellite-terrestrial systems

This paper deals with the problem of hybrid analog-digital transmit beamforming under spectrum sharing constraints. Hybrid multiantenna architectures are ideal for high throughput wireless links, where full-digital solutions are extremely expensive due to their the high number of radiofrequency chains and full-analog architectures require complex and lossy beamforming networks. In contrast to the recent works regarding mm-wave precoding, we consider the case where the transmitter is required to limit its array gain to certain angles-of-departure where non-intended receivers are located. This is of great importance in the 18 GHz band where wireless backhaul systems can eventually share the spectrum with satellite systems, leading to a substantial reduction of the spectrum license cost. We propose a general optimization framework based on an alternate analog-digital optimization that can consider any arbitrary sub-array scheme (i.e. interleaved, localized, etc.). At each stage of the analog-digital optimization a quadraticallyconstraint-quadratic-program needs to be solved and it requires the use of novel non-smooth methods. Numerical results show the performance of our method for different scenarios and sub-array schemes.Peer ReviewedPostprint (published version

Hybrid analog-digital transmit beamforming for spectrum sharing satellite-terrestrial systems

This paper deals with the problem of hybrid analog-digital transmit beamforming under spectrum sharing constraints. Hybrid multiantenna architectures are ideal for high throughput wireless links, where full-digital solutions are extremely expensive due to their the high number of radiofrequency chains and full-analog architectures require complex and lossy beamforming networks. In contrast to the recent works regarding mm-wave precoding, we consider the case where the transmitter is required to limit its array gain to certain angles-of-departure where non-intended receivers are located. This is of great importance in the 18 GHz band where wireless backhaul systems can eventually share the spectrum with satellite systems, leading to a substantial reduction of the spectrum license cost. We propose a general optimization framework based on an alternate analog-digital optimization that can consider any arbitrary sub-array scheme (i.e. interleaved, localized, etc.). At each stage of the analog-digital optimization a quadraticallyconstraint-quadratic-program needs to be solved and it requires the use of novel non-smooth methods. Numerical results show the performance of our method for different scenarios and sub-array schemes.Peer Reviewe

Shared access satellite-terrestrial reconfigurable backhaul network enabled by smart antennas at mm-wave band

© 2018 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.5G traffic expectations require not only the appropriate access infrastructure, but also the corresponding backhaul infrastructure to ensure a well-balanced network scaling. Optical fibre and terrestrial wireless backhaul will hardly meet 100% coverage and satellite must be considered within the 5G infrastructure to boost ubiquitous and reliable network utilization. This work presents the main outcomes of SANSA project, which proposes a novel solution that overcomes the limitations of the traditional fixed backhaul. It is based on a dynamic integrated satelliteterrestrial backhaul network operating on the mm-wave band. Its key principles are a seamless integration of the satellite segment into terrestrial backhaul networks; a terrestrial wireless network capable of reconfiguring its topology according to traffic demands; and an aggressive frequency reuse within the terrestrial segment and between terrestrial and satellite segments. The two technological enablers of SANSA are smart antenna techniques at mm-wave and a software defined intelligent hybrid network management. This article introduces these 5G enablers, which permit satellite communications to play a key role in different 5G use cases, from the early deployment of 5G services in sparse scenarios to enhanced mobile broadband in denser scenarios.Peer Reviewe

Shared access satellite-terrestrial reconfigurable backhaul network enabled by smart antennas at mm-wave band

© 2018 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.5G traffic expectations require not only the appropriate access infrastructure, but also the corresponding backhaul infrastructure to ensure a well-balanced network scaling. Optical fibre and terrestrial wireless backhaul will hardly meet 100% coverage and satellite must be considered within the 5G infrastructure to boost ubiquitous and reliable network utilization. This work presents the main outcomes of SANSA project, which proposes a novel solution that overcomes the limitations of the traditional fixed backhaul. It is based on a dynamic integrated satelliteterrestrial backhaul network operating on the mm-wave band. Its key principles are a seamless integration of the satellite segment into terrestrial backhaul networks; a terrestrial wireless network capable of reconfiguring its topology according to traffic demands; and an aggressive frequency reuse within the terrestrial segment and between terrestrial and satellite segments. The two technological enablers of SANSA are smart antenna techniques at mm-wave and a software defined intelligent hybrid network management. This article introduces these 5G enablers, which permit satellite communications to play a key role in different 5G use cases, from the early deployment of 5G services in sparse scenarios to enhanced mobile broadband in denser scenarios.Peer Reviewe