SwePub
Sök i SwePub databas

  Extended search

Träfflista för sökning "WFRF:(Seco G) "

Search: WFRF:(Seco G)

  • Result 1-48 of 48
Sort/group result
   
EnumerationReferenceCoverFind
1.
  • Ruilope, LM, et al. (author)
  • Design and Baseline Characteristics of the Finerenone in Reducing Cardiovascular Mortality and Morbidity in Diabetic Kidney Disease Trial
  • 2019
  • In: American journal of nephrology. - : S. Karger AG. - 1421-9670 .- 0250-8095. ; 50:5, s. 345-356
  • Journal article (peer-reviewed)abstract
    • <b><i>Background:</i></b> Among people with diabetes, those with kidney disease have exceptionally high rates of cardiovascular (CV) morbidity and mortality and progression of their underlying kidney disease. Finerenone is a novel, nonsteroidal, selective mineralocorticoid receptor antagonist that has shown to reduce albuminuria in type 2 diabetes (T2D) patients with chronic kidney disease (CKD) while revealing only a low risk of hyperkalemia. However, the effect of finerenone on CV and renal outcomes has not yet been investigated in long-term trials. <b><i>Patients and</i></b> <b><i>Methods:</i></b> The Finerenone in Reducing CV Mortality and Morbidity in Diabetic Kidney Disease (FIGARO-DKD) trial aims to assess the efficacy and safety of finerenone compared to placebo at reducing clinically important CV and renal outcomes in T2D patients with CKD. FIGARO-DKD is a randomized, double-blind, placebo-controlled, parallel-group, event-driven trial running in 47 countries with an expected duration of approximately 6 years. FIGARO-DKD randomized 7,437 patients with an estimated glomerular filtration rate ≥25 mL/min/1.73 m<sup>2</sup> and albuminuria (urinary albumin-to-creatinine ratio ≥30 to ≤5,000 mg/g). The study has at least 90% power to detect a 20% reduction in the risk of the primary outcome (overall two-sided significance level α = 0.05), the composite of time to first occurrence of CV death, nonfatal myocardial infarction, nonfatal stroke, or hospitalization for heart failure. <b><i>Conclusions:</i></b> FIGARO-DKD will determine whether an optimally treated cohort of T2D patients with CKD at high risk of CV and renal events will experience cardiorenal benefits with the addition of finerenone to their treatment regimen. Trial Registration: EudraCT number: 2015-000950-39; ClinicalTrials.gov identifier: NCT02545049.
  •  
2.
  • Butler-Laporte, G, et al. (author)
  • Exome-wide association study to identify rare variants influencing COVID-19 outcomes: Results from the Host Genetics Initiative
  • 2022
  • In: PLoS genetics. - : Public Library of Science (PLoS). - 1553-7404 .- 1553-7390. ; 18:11, s. e1010367-
  • Journal article (peer-reviewed)abstract
    • Host genetics is a key determinant of COVID-19 outcomes. Previously, the COVID-19 Host Genetics Initiative genome-wide association study used common variants to identify multiple loci associated with COVID-19 outcomes. However, variants with the largest impact on COVID-19 outcomes are expected to be rare in the population. Hence, studying rare variants may provide additional insights into disease susceptibility and pathogenesis, thereby informing therapeutics development. Here, we combined whole-exome and whole-genome sequencing from 21 cohorts across 12 countries and performed rare variant exome-wide burden analyses for COVID-19 outcomes. In an analysis of 5,085 severe disease cases and 571,737 controls, we observed that carrying a rare deleterious variant in the SARS-CoV-2 sensor toll-like receptor TLR7 (on chromosome X) was associated with a 5.3-fold increase in severe disease (95% CI: 2.75–10.05, p = 5.41x10-7). This association was consistent across sexes. These results further support TLR7 as a genetic determinant of severe disease and suggest that larger studies on rare variants influencing COVID-19 outcomes could provide additional insights.
  •  
3.
  • Wohlfahrt, G., et al. (author)
  • An ecosystem-scale perspective of the net land methanol flux : synthesis of micrometeorological flux measurements
  • 2015
  • In: Atmospheric Chemistry and Physics. - : Copernicus GmbH. - 1680-7324. ; 15:13, s. 7413-7427
  • Journal article (peer-reviewed)abstract
    • Methanol is the second most abundant volatile organic compound in the troposphere and plays a significant role in atmospheric chemistry. While there is consensus about the dominant role of living plants as the major source and the reaction with OH as the major sink of methanol, global methanol budgets diverge considerably in terms of source/sink estimates, reflecting uncertainties in the approaches used to model and the empirical data used to separately constrain these terms. Here we compiled micrometeorological methanol flux data from eight different study sites and reviewed the corresponding literature in order to provide a first cross-site synthesis of the terrestrial ecosystem-scale methanol exchange and present an independent data-driven view of the land-atmosphere methanol exchange. Our study shows that the controls of plant growth on production, and thus the methanol emission magnitude, as well as stomatal conductance on the hourly methanol emission variability, established at the leaf level, hold across sites at the ecosystem level. Unequivocal evidence for bi-directional methanol exchange at the ecosystem scale is presented. Deposition, which at some sites even exceeds methanol emissions, represents an emerging feature of ecosystem-scale measurements and is likely related to environmental factors favouring the formation of surface wetness. Methanol may adsorb to or dissolve in this surface water and eventually be chemically or biologically removed from it. Management activities in agriculture and forestry are shown to increase local methanol emission by orders of magnitude; however, they are neglected at present in global budgets. While contemporary net land methanol budgets are overall consistent with the grand mean of the micrometeorological methanol flux measurements, we caution that the present approach of simulating methanol emission and deposition separately is prone to opposing systematic errors and does not allow for full advantage to be taken of the rich information content of micrometeorological flux measurements.
  •  
4.
  • Abu-Shaban, Z., et al. (author)
  • Near-field Localization with a Reconfigurable Intelligent Surface Acting as Lens
  • 2021
  • In: IEEE International Conference on Communications. - 1550-3607. ; June 2021
  • Conference paper (peer-reviewed)abstract
    • Exploiting wavefront curvature enables localization with limited infrastructure and hardware complexity. With the introduction of reconfigurable intelligent surfaces (RISs), new opportunities arise, in particular when the RIS is functioning as a lens receiver. We investigate the localization of a transmitter using a RIS-based lens in close proximity to a single receive antenna element attached to reception radio frequency chain. We perform a Fisher information analysis, evaluate the impact of different lens configurations, and propose a two-stage localization algorithm. Our results indicate that positional beamforming can lead to better performance when a priori location information is available, while random beamforming is preferred when a priori information is lacking. Our simulation results for a moderate size lens operating at 28 GHz showcased that decimeter-level accuracy can be attained within 3 meters to the lens.
  •  
5.
  •  
6.
  • Chen, Hui, 1992, et al. (author)
  • RISs and Sidelink Communications in Smart Cities: The Key to Seamless Localization and Sensing
  • 2023
  • In: IEEE Communications Magazine. - 0163-6804 .- 1558-1896. ; 61:8, s. 140-146
  • Journal article (peer-reviewed)abstract
    • A smart city involves, among other elements, intelligent transportation, crowd monitoring, and digital twins, each of which requires information exchange via wireless communication links and localization of connected devices and passive objects (including people). Although localization and sensing (L&S) are envisioned as core functions of future communication systems, they have inherently different demands in terms of infrastructure compared to communications. Wireless communications generally requires a connection to only a single access point (AP), while L&S demand simultaneous line-of-sight propagation paths to several APs, which serve as location and orientation anchors. Hence, a smart city deployment optimized for communication will be insufficient to meet stringent L&S requirements. In this article, we argue that the emerging technologies of reconfigurable intelligent surfaces (RISs) and sidelink communications constitute the key to providing ubiquitous coverage for L&S in smart cities with low-cost and energy-efficient technical solutions. To this end, we propose and evaluate AP-coordinated and self-coordinated RIS-enabled L&S architectures and detail three groups of application scenarios, relying on low-complexity beacons, cooperative localization, and full-duplex transceivers. A list of practical issues and consequent open research challenges of the proposed L&S systems is also provided.
  •  
7.
  • Destino, G., et al. (author)
  • Performance Analysis of Hybrid 5G-GNSS Localization
  • 2018
  • In: Conference Record - Asilomar Conference on Signals, Systems and Computers. - 1058-6393. ; 2018-October, s. 8-12
  • Conference paper (peer-reviewed)abstract
    • We consider a novel positioning solution combining millimeter wave (mmW) 5G and Global Navigation Satellite System (GNSS) technologies. The study is carried out theoretically by deriving the Fisher Information Matrix (FIM) of a combined 5G-GNSS positioning system and, subsequently, the position, rotation and clock-bias error lower bounds. We pursue a two-step approach, namely, computing first the FIM for the channel parameters, and then transforming it into the FIM of the position, rotation and clock-bias. The analysis shows advantages of the hybrid positioning in terms of i) localization accuracy, ii) coverage, iii) precise rotation estimation and iv) clock-error estimation. In other words, we demonstrate that a tight coupling of the two technologies can provide mutual benefits.
  •  
8.
  •  
9.
  • Ghazalian, Reza, et al. (author)
  • Joint 3D User and 6D Hybrid Reconfigurable Intelligent Surface Localization
  • 2024
  • In: IEEE Transactions on Vehicular Technology. - 0018-9545 .- 1939-9359. ; In Press
  • Journal article (peer-reviewed)abstract
    • The latest assessments of the emerging technologies for reconfigurable intelligent surfaces (RISs) have indicated the concept's significant potential for localization and sensing, either as individual or simultaneously realized tasks. However, in the vast majority of those studies, the RIS state (i.e., its position and rotation angles) is required to be known a priori. In this paper, we address the problem of the joint three-dimensional (3D) localization of a hybrid RIS (HRIS) and a user. The most cost- and power-efficient hybrid version of an RIS is equipped with a single reception radio-frequency chain and meta-atoms capable of simultaneous reconfigurable reflection and sensing. This dual functionality is controlled by adjustable power splitters embedded at each hybrid meta-atom. Focusing on a downlink scenario where a multi-antenna base station transmits multicarrier signals to a user via an HRIS, we propose a multistage approach to jointly estimate the metasurface's 3D position and 3D rotation matrix (i.e., 6D parameter estimation) as well as the user's 3D position. Our simulation results verify the validity of the proposed estimator via extensive comparisons of the root-mean-square error of the state estimations with the Cram´er-Rao lower bound (CRB), which is analytically derived. Furthermore, it is showcased that there exists an optimal hybrid reconfigurable intelligent surface (HRIS) power splitting ratio for the desired multi-parameter estimation problem. We also study the robustness of the proposed method in the presence of scattering points in the wireless propagation environment.
  •  
10.
  • Ghazalian, Reza, et al. (author)
  • Joint User Localization and Location Calibration of A Hybrid Reconfigurable Intelligent Surface
  • 2024
  • In: IEEE Transactions on Vehicular Technology. - 0018-9545 .- 1939-9359. ; 73:1, s. 1435-1440
  • Journal article (peer-reviewed)abstract
    • The recent research in the emerging technology of reconfigurable intelligent surfaces (RISs) has identified its high potential for localization and sensing. However, to accurately localize a user placed in the area of influence of an RIS, the RIS location needs to be known a priori and its phase profile is required to be optimized for localization. In this paper, we study the problem of the joint localization of a hybrid RIS (HRIS) and a user, considering that the former is equipped with a single reception radio-frequency (RF) chain enabling simultaneous tunable reflections and sensing via power splitting. Focusing on the downlink of a multi-antenna base station, we present a multi-stage approach for the estimation of the HRIS position and orientation as well as the user position. Our simulation results, including comparisons with the Cramér-Rao lower bounds, demonstrate the efficiency of the proposed localization approach, while showcasing that there exists an optimal HRIS power splitting ratio for the desired multi-parameter estimation problem.
  •  
11.
  • Ghazalian, Reza, et al. (author)
  • RIS Position and Orientation Estimation via Multi-Carrier Transmissions and Multiple Receivers
  • 2023
  • In: IEEE International Conference on Communications. - 1550-3607. ; 2023-May, s. 2915-2920
  • Conference paper (peer-reviewed)abstract
    • Reconfigurable intelligent surfaces (RISs) are considered as an enabling technology for the upcoming sixth generation of wireless systems, exhibiting significant potential for radio localization and sensing. An RIS is usually treated as an anchor point with known position and orientation when deployed to offer user localization. However, it can also be attached to a user to enable its localization in a semi-passive manner. In this paper, we consider a static user equipped with an RIS and study the RIS localization problem (i.e., joint three-dimensional position and orientation estimation), when operating in a system comprising a single-antenna transmitter and multiple synchronized single-antenna receivers with known locations. We present a multi-stage estimator using time-of-arrival and spatial frequency measurements, and derive the Cramér-Rao lower bounds for the estimated parameters to validate the estimator's performance. Our simulation results demonstrate the efficiency of the proposed RIS state estimation approach under various system operation parameters.
  •  
12.
  • Keykhosravi, Kamran, 1990, et al. (author)
  • RIS-Enabled Self-Localization: Leveraging Controllable Reflections With Zero Access Points
  • 2022
  • In: IEEE International Conference on Communications. - 1550-3607. ; 2022-May, s. 2852-2857
  • Conference paper (peer-reviewed)abstract
    • Reconfigurable intelligent surfaces (RISs) are one of the most promising technological enablers of the next (6th) generation of wireless systems. In this paper, we introduce a novel use-case of the RIS technology in radio localization, which is enabling the user to estimate its own position via transmitting orthogonal frequency-division multiplexing (OFDM) pilots and processing the signal reflected from the RIS. We demonstrate that user localization in this scenario is possible by deriving Cramér-Rao lower bounds on the positioning error and devising a low-complexity position estimation algorithm. We consider random and directional RIS phase profiles and apply a specific temporal coding to them, such that the reflected signal from the RIS can be separated from the uncontrolled multipath. Finally, we assess the performance of our position estimator for an example system, and show that the proposed algorithm can attain the derived bound at high signal-to-noise ratio values.
  •  
13.
  • Kim, Hyowon, 1987, et al. (author)
  • RIS-Aided Monostatic Sensing and Object Detection with Single and Double Bounce Multipath
  • 2023
  • In: 2023 IEEE International Conference on Communications Workshops: Sustainable Communications for Renaissance, ICC Workshops 2023. ; , s. 1883-1889
  • Conference paper (peer-reviewed)abstract
    • We propose a framework for monostatic sensing by a user equipment (UE), aided by a reconfigurable intelligent surface (RIS) in environments with single- and double-bounce signal propagation. We design appropriate UE-side precoding and combining, to facilitate signal separation. We derive the adaptive detection probabilities of the resolvable signals, based on the geometric channel parameters of the links. Then, we estimate the passive objects using both the double-bounce signals via passive RIS (i.e., RIS-sensing) and the single-bounce multipath direct to the objects (i.e., non-RIS-sensing), based on a mapping filter. Finally, we provide numerical results to demonstrate that effective sensing can be achieved through the proposed framework.
  •  
14.
  • Abu-Shaban, Z., et al. (author)
  • Error Bounds for Uplink and Downlink 3D Localization in 5G Millimeter Wave Systems
  • 2018
  • In: IEEE Transactions on Wireless Communications. - 1558-2248 .- 1536-1276. ; 17:8, s. 4939-4954
  • Journal article (peer-reviewed)abstract
    • Location-aware communication systems are expected to play a pivotal part in the next generation of mobile communication networks. Therefore, there is a need to understand the localization limits in these networks, particularly, using millimeter-wave technology (mm-wave). Towards that, we address the uplink and downlink localization limits in terms of 3D position and orientation error bounds for mm-wave multipath channels. We also carry out a detailed analysis of the dependence of the bounds on different system parameters. Our key findings indicate that the uplink and downlink behave differently in two distinct ways. First of all, the error bounds have different scaling factors with respect to the number of antennas in the uplink and downlink. Secondly, uplink localization is sensitive to the orientation angle of the user equipment (UE), whereas downlink is not. Moreover, in the considered outdoor scenarios, the non-line-of-sight paths generally improve localization when a line-of-sight path exists. Finally, our numerical results show that mm-wave systems are capable of localizing a UE with sub-meter position error, and sub-degree orientation error.
  •  
15.
  • Abu-Shaban, Z., et al. (author)
  • Performance Analysis for Autonomous Vehicle 5g-Assisted Positioning in GNSS-Challenged Environments
  • 2020
  • In: 2020 IEEE/ION Position, Location and Navigation Symposium, PLANS 2020. ; , s. 996-1003
  • Conference paper (peer-reviewed)abstract
    • Standalone Global Navigation Satellite Systems (GNSS) are known to provide a positioning accuracy of a few meters in open sky conditions. This accuracy can drop significantly when the line-of-sight (LOS) paths to some GNSS satellites are obstructed, e.g., in urban canyons or underground tunnels. To overcome this issue, the general approach is usually to augment GNSS systems with other dedicated subsystems to help cover the gaps arising from obscured LOS. Positioning in 5G has attracted some attention lately, mainly due to the possibility to provide cm-level accuracy using 5G signals and infrastructure, effectively imposing no additional cost. In this paper, we study the hybridization of GNSS and 5G positioning in terms of achievable position and velocity error bounds. We focus on scenarios where satellite visibility is constrained by the environment geometry, and where the GNSS and 5G positioning systems fail to perform individually or provide prohibitively large error.
  •  
16.
  • Abu-Shaban, Z., et al. (author)
  • Performance of location and orientation estimation in 5G mmWave systems: Uplink vs downlink
  • 2018
  • In: IEEE Wireless Communications and Networking Conference, WCNC. - 1525-3511. ; 2018-April, s. 1-6
  • Conference paper (peer-reviewed)abstract
    • The fifth generation of mobile communications (5G) is expected to exploit the concept of location-aware communication systems. Therefore, there is a need to understand the localization limits in these networks, particularly, using millimeter-wave technology (mmWave). Contributing to this understanding, we consider single-anchor localization limits in terms of 3D position and orientation error bounds for mmWave multipath channels, for both the uplink and downlink. It is found that uplink localization is sensitive to the orientation angle of the user equipment (UE), whereas downlink is not. Moreover, in the considered outdoor scenarios, reflected and scattered paths generally improve localization. Finally, using detailed numerical simulations, we show that mmWave systems are in theory capable of localizing a UE with sub-meter position error, and sub-degree orientation error.
  •  
17.
  • Abu-Shaban, Z., et al. (author)
  • Random-phase beamforming for initial access in millimeter-wave cellular networks
  • 2016
  • In: Proceedings - IEEE Global Communications Conference, GLOBECOM. - 2334-0983 .- 2576-6813.
  • Conference paper (peer-reviewed)abstract
    • The utilization of the millimeter-wave frequency band (mm-wave) in the fifth generation ({5G}) of mobile communication is a highly-debated current topic. Mm-wave MIMO systems will use arrays with large number of antennas at the transmitter and the receiver, implemented on a relatively small area. With the inherent high directivity of these arrays, algorithms to help the user equipment find the base station and establish a communication link should be carefully designed. Towards that, we examine two beamforming schemes, namely, random-phase beamforming (RPBF) and directional beamforming (DBF), and test their impact on the Cram\'er-Rao lower bounds (CRB) of jointly estimating the direction-of-arrival, direction-of-departure, time-of-arrival, and the complex channel gain, under the line-of-sight channel model. The results show that the application of RPBF is more appropriate in the considered scenario as it attains a lower CRB with fewer beams compared to DBF.
  •  
18.
  • Abu-Shaban, Z., et al. (author)
  • Single-anchor two-way localization bounds for 5G mmWave systems
  • 2020
  • In: IEEE Transactions on Vehicular Technology. - 0018-9545 .- 1939-9359. ; 69:6, s. 6388-6400
  • Journal article (peer-reviewed)abstract
    • Recently, millimeter-wave (mmWave) 5G localization has been shown to be to provide centimeter-level accuracy, lending itself to many location-aware applications, e.g., connected autonomous vehicles (CAVs). One assumption usually made in the investigation of localization methods is that the user equipment (UE), i.e., a CAV, and the base station (BS) are time synchronized. In this paper, we remove this assumption and investigate two two-way localization protocols: (i) a round-trip localization protocol (RLP), whereby the BS and UE exchange signals in two rounds of transmission and then localization is achieved using the signal received in the second round; (ii) a collaborative localization protocol (CLP), whereby localization is achieved using the signals received in the two rounds. We derive the position and orientation error bounds applying beamforming at both ends and compare them to the traditional one-way localization. Our results show that mmWave localization is mainly limited by the angular rather than the temporal estimation and that CLP significantly outperforms RLP. Our simulations also show that it is more beneficial to have more antennas at the BS than at the UE.
  •  
19.
  • De Lima, Carlos, et al. (author)
  • Convergent Communication, Sensing and Localization in 6G Systems: An Overview of Technologies, Opportunities and Challenges
  • 2021
  • In: IEEE Access. - 2169-3536 .- 2169-3536. ; 9, s. 26902-26925
  • Research review (peer-reviewed)abstract
    • Herein, we focus on convergent 6G communication, localization and sensing systems by identifying key technology enablers, discussing their underlying challenges, implementation issues, and recommending potential solutions. Moreover, we discuss exciting new opportunities for integrated localization and sensing applications, which will disrupt traditional design principles and revolutionize the way we live, interact with our environment, and do business. Regarding potential enabling technologies, 6G will continue to develop towards even higher frequency ranges, wider bandwidths, and massive antenna arrays. In turn, this will enable sensing solutions with very fine range, Doppler, and angular resolutions, as well as localization to cm-level degree of accuracy. Besides, new materials, device types, and reconfigurable surfaces will allow network operators to reshape and control the electromagnetic response of the environment. At the same time, machine learning and artificial intelligence will leverage the unprecedented availability of data and computing resources to tackle the biggest and hardest problems in wireless communication systems. As a result, 6G will be truly intelligent wireless systems that will provide not only ubiquitous communication but also empower high accuracy localization and high-resolution sensing services. They will become the catalyst for this revolution by bringing about a unique new set of features and service capabilities, where localization and sensing will coexist with communication, continuously sharing the available resources in time, frequency, and space. This work concludes by highlighting foundational research challenges, as well as implications and opportunities related to privacy, security, and trust.
  •  
20.
  • Fascista, Alessio, et al. (author)
  • Downlink Single-Snapshot Localization and Mapping with a Single-Antenna Receiver
  • 2021
  • In: IEEE Transactions on Wireless Communications. - 1558-2248 .- 1536-1276. ; 20:7, s. 4672-4684
  • Journal article (peer-reviewed)abstract
    • 5G mmWave MIMO systems enable accurate estimation of the user position and mapping of the radio environment using a single snapshot when both the base station (BS) and user are equipped with large antenna arrays. However, massive arrays are initially expected only at the BS side, likely leaving users with one or very few antennas. In this paper, we propose a novel method for single-snapshot localization and mapping in the more challenging case of a user equipped with a single-antenna receiver. The joint maximum likelihood (ML) estimation problem is formulated and its solution formally derived. To avoid the burden of a full-dimensional search over the space of the unknown parameters, we present a novel practical approach that exploits the sparsity of mmWave channels to compute an approximate joint ML estimate. A thorough analysis, including the derivation of the Cramér-Rao lower bounds, reveals that accurate localization and mapping can be achieved also in a MISO setup even when the direct line-of-sight path between the BS and the user is severely attenuated.
  •  
21.
  • Fascista, Alessio, et al. (author)
  • Low-Complexity Accurate Mmwave Positioning for Single-Antenna Users Based on Angle-of-Departure and Adaptive Beamforming
  • 2020
  • In: ICASSP, IEEE International Conference on Acoustics, Speech and Signal Processing - Proceedings. - 1520-6149. ; 2020-May, s. 4866-4870
  • Conference paper (peer-reviewed)abstract
    • The problem of position estimation of a mobile user equipped with a single antenna receiver using downlink transmissions is addressed. The advantages of this setup compared to the classical MIMO and uplink scenarios are analyzed in terms of achievable theoretical performance (Cramér-Rao bounds) considering a realistic power budget. Based on this analysis, a low-complexity two-step algorithm with improved localization performance is proposed, which first performs a (coarse) angle of departure estimation and then precodes the down-link signal to introduce beamforming towards the user direction. Results demonstrate that position estimation in downlink can be potentially much more accurate than in uplink, even in presence of multiple users in the system.
  •  
22.
  • Fascista, Alessio, et al. (author)
  • Low-Complexity Downlink Channel Estimation in mmWave Multiple-Input Single-Output Systems
  • 2022
  • In: IEEE Wireless Communications Letters. - 2162-2345 .- 2162-2337. ; 11:3, s. 518-522
  • Journal article (peer-reviewed)abstract
    • This paper tackles the problem of channel estimation in mmWave multiple-input single-output systems, where users are equipped with single-antenna receivers. By leveraging broadcast transmissions in the downlink channel, two novel low-complexity estimation approaches are devised, able to operate even in presence of a reduced number of transmit antennas or limited bandwidth. Numerical results show that the proposed algorithms provide accurate estimates of the channel parameters, achieving at the same time about 50% complexity reduction compared to existing approaches.
  •  
23.
  • Fascista, Alessio, et al. (author)
  • RIS-aided joint localization and synchronization with a single-antenna mmwave receiver
  • 2021
  • In: ICASSP, IEEE International Conference on Acoustics, Speech and Signal Processing - Proceedings. - 1520-6149. ; 2021-June, s. 4455-4459
  • Conference paper (peer-reviewed)abstract
    • MmWave multiple-input single-output (MISO) systems using a single-antenna receiver are regarded as a promising solution for the near future, before the full-fledged 5G MIMO will be widespread. However, for MISO systems synchronization cannot be performed jointly with user localization unless two-way transmissions are used. In this paper we show that thanks to the use of a reconfigurable intelligent surface (RIS), joint localization and synchronization is possible with only downlink MISO transmissions. The direct maximum likelihood (ML) estimator for the position and clock offset is derived. To obtain a good initialization for the ML optimization, a decoupled, relaxed estimator of position and delays is also devised, which does not require knowledge of the clock offset. Results show that the proposed approach attains the Cramér-Rao lower bound even for moderate values of the system parameters.
  •  
24.
  • Fascista, Alessio, et al. (author)
  • RIS-aided Joint Localization and Synchronization with a Single-Antenna Receiver: Beamforming Design and Low-Complexity Estimation
  • 2022
  • In: IEEE Journal on Selected Topics in Signal Processing. - 1941-0484 .- 1932-4553. ; 16:5, s. 1141-1156
  • Journal article (peer-reviewed)abstract
    • Reconfigurable intelligent surfaces (RISs) have attracted enormous interest thanks to their ability to overcome line-of-sight blockages in mmWave systems, enabling in turn accurate localization with minimal infrastructure. Less investigated are however the benefits of exploiting RIS with suitably designed beamforming strategies for optimized localization and synchronization performance. In this paper, a novel low-complexity method for joint localization and synchronization based on an optimized design of the base station (BS) active precoding and RIS passive phase profiles is proposed, for the challenging case of a single-antenna receiver. The theoretical position error bound is first derived and used as metric to jointly optimize the BS-RIS beamforming, assuming a priori knowledge of the user position. By exploiting the low-dimensional structure of the solution, a novel codebook-based robust design strategy with optimized beam power allocation is then proposed, which provides low-complexity while taking into account the uncertainty on the user position. Finally, a reduced-complexity maximum-likelihood based estimation procedure is devised to jointly recover the user position and the synchronization offset. Extensive numerical analysis shows that the proposed joint BS-RIS beamforming scheme provides enhanced localization and synchronization performance compared to existing solutions, with the proposed estimator attaining the theoretical bounds even at low signal-to-noise-ratio and in the presence of additional uncontrollable multipath propagation.
  •  
25.
  • Fascista, Alessio, et al. (author)
  • Uplink Joint Positioning and Synchronization in Cell-Free Deployments with Radio Stripes
  • 2023
  • In: 2023 IEEE International Conference on Communications Workshops: Sustainable Communications for Renaissance, ICC Workshops 2023. ; , s. 1330-1336
  • Conference paper (peer-reviewed)abstract
    • Radio stripes (RSs) is an emerging technology in beyond 5G and 6G wireless networks to support the deployment of cell-free architectures. In this paper, we investigate the potential use of RSs to enable joint positioning and synchronization in the uplink channel at sub-6 GHz bands. The considered scenario consists of a single-antenna user equipment (UE) that communicates with a network of multiple-antenna RSs distributed over a wide area. The UE is assumed to be unsynchronized to the RSs network, while individual RSs are time- and phase-synchronized. We formulate the problem of joint estimation of position, clock offset and phase offset of the UE and derive the corresponding maximum-likelihood (ML) estimator, both with and without exploiting carrier phase information. To gain fundamental insights into the achievable performance, we also conduct a Fisher information analysis and inspect the theoretical lower bounds numerically. Simulation results demonstrate that promising positioning and synchronization performance can be obtained in cell-free architectures supported by RSs, revealing at the same time the benefits of carrier phase exploitation through phase-synchronized RSs.
  •  
26.
  • Garcia, Gabriel, 1985, et al. (author)
  • Transmitter Beam Selection in Millimeter-Wave MIMO with In-Band Position-Aiding
  • 2018
  • In: IEEE Transactions on Wireless Communications. - 1558-2248 .- 1536-1276. ; 17:9, s. 6082-6092
  • Journal article (peer-reviewed)abstract
    • Emerging wireless communication systems will be characterized by a tight coupling between communication and positioning. This is particularly apparent in millimeter-wave (mm-wave) communications, where devices use a large number of antennas, and the propagation is well described by geometric channel models. For mm-wave communications, initial access, consisting in the beam selection and alignment of two devices, is challenging and time consuming in the absence of location information. Conversely, accurate positioning relies on high-quality communication links with proper beam alignment. This paper studies this interaction and proposes a new position-aided transmitter beam selection protocol, which considers the problem of joint communication and positioning in scenarios with direct line-of-sight and scattering. Simulation results show significant reductions in latency with respect to a standard protocol.
  •  
27.
  • Garcia, Nil, 1983, et al. (author)
  • Cramér-Rao Bound Analysis of Radars for Extended Vehicular Targets With Known and Unknown Shape
  • 2022
  • In: IEEE Transactions on Signal Processing. - 1941-0476 .- 1053-587X. ; 70, s. 3280-3295
  • Journal article (peer-reviewed)abstract
    • Due to their shorter operating range and large bandwidth, automotive radars can resolve many reflections from their targets of interest, mainly vehicles. This calls for the use of extended-target models in place of simpler and more widely-adopted point-like target models. However, despite some preliminary work, the fundamental connection between the radar’s accuracy as a function of the target vehicle state (range, orientation, shape) and radar properties remains largely unknown for extended targets. In this work, we first devise a mathematically tractable analytical model for a vehicle with arbitrary shape, modeled as an extended target parameterized by the center position, the orientation (heading) and the perimeter contour. We show that the derived expressions of the backscatter signal are tractable and correctly capture the effects of the extended-vehicle shape. Analytical derivations of the exact and approximate hybrid Cramér-Rao bounds for the position, orientation and contour are provided, which reveal connections with the case of point-like target and uncover the main dependencies with the received energy, bandwidth, and array size. The theoretical investigation is performed on the two different cases of known and unknown vehicle shape. Insightful simulation results are finally presented to validate the theoretical findings, including an analysis of the diversity effect of multiple radars sensing the extended target.
  •  
28.
  • Gertzell, Philip, et al. (author)
  • 5G multi-BS positioning with a single-antenna receiver
  • 2020
  • In: IEEE International Symposium on Personal, Indoor and Mobile Radio Communications, PIMRC. ; 2020-August
  • Conference paper (peer-reviewed)abstract
    • Cellular localization generally relies on timedifference-of-arrival (TDOA) measurements. In this paper, we investigate a novel scenario where the mobile user estimates its own position by jointly exploiting TDOA and angle of departure (AOD) measurements, which are estimated from downlink transmissions in a millimeter-wave (mmWave) multiple-input singleoutput (MISO) setup. We first perform a Fisher information analysis to derive the lower bounds on the estimation accuracy, and then propose a novel localization algorithm, which is able to provide improved performance also with few transmit antennas and limited bandwidth.
  •  
29.
  • Gruber, CEM, et al. (author)
  • Geographical Variability Affects CCHFV Detection by RT-PCR: A Tool for In-Silico Evaluation of Molecular Assays
  • 2019
  • In: Viruses. - : MDPI AG. - 1999-4915. ; 11:10
  • Journal article (peer-reviewed)abstract
    • The Crimean–Congo hemorrhagic fever virus (CCHFV) is considered to be a major emerging infectious threat, according to the WHO R&D blueprint. A wide range of CCHFV molecular assays have been developed, employing varied primer/probe combinations. The high genetic variability of CCHFV often hampers the efficacy of available molecular tests and can affect their diagnostic potential. Recently, increasing numbers of complete CCHFV genomic sequences have become available, allowing a better appreciation of the genomic evolution of this virus. We summarized the current knowledge on molecular methods and developed a new bioinformatics tool to evaluate the existing assays for CCHFV detection, with a special focus on strains circulating in different geographical areas. Twenty-two molecular methods and 181 sequences of CCHFV were collected, respectively, from PubMed and GenBank databases. Up to 28 mismatches between primers and probes of each assay and CCHFV strains were detected through in-silico PCR analysis. Combinations of up to three molecular methods markedly decreased the number of mismatches within most geographic areas. These results supported the good practice of CCHFV detection of performing more than one assay, aimed for different sequence targets. The choice of the most appropriate tests must take into account patient’s travel history and geographic distribution of the different CCHFV strains.
  •  
30.
  • Kakkavas, Anastasios, et al. (author)
  • 5G downlink multi-beam signal design for LOS positioning
  • 2019
  • In: 2019 IEEE Global Communications Conference, GLOBECOM 2019 - Proceedings.
  • Conference paper (peer-reviewed)abstract
    • In this work, we study optimal transmit strategies for minimizing the positioning error bound in a line-of-sight scenario, under different levels of prior knowledge of the channel parameters. For the case of perfect prior knowledge, we prove that two beams are optimal, and determine their beam directions and optimal power allocation. For the imperfect prior knowledge case, we compute the optimal power allocation among the beams of a codebook for two different robustness-related objectives, namely average or maximum squared position error bound minimization. Our numerical results show that our low-complexity approach can outperform existing methods that entail higher signaling and computational overhead.
  •  
31.
  • Kakkavas, Anastasios, et al. (author)
  • Position Information from Reflecting Surfaces
  • 2021
  • In: IEEE Wireless Communications Letters. - 2162-2345 .- 2162-2337. ; 10:6, s. 1300-1304
  • Journal article (peer-reviewed)abstract
    • In the context of positioning an agent with a single-anchor, this contribution focuses on the Fisher information about the position, orientation and clock offset of the agent provided by single-bounce reflections. The availability of prior knowledge of the agent’s environment is taken into account via a prior distribution of the position of virtual anchors, and the rank, intensity and direction of provided information is studied. We show that when no prior knowledge is available, single-bounce reflections offer position information in the direction parallel to the reflecting surface, irrespective of the agent’s and anchor’s locations. We provide a geometrically intuitive explanation of the results and present numerical examples demonstrating their potential implications.
  •  
32.
  • Kakkavas, Anastasios, et al. (author)
  • Power Allocation and Parameter Estimation for Multipath-based 5G Positioning
  • 2021
  • In: IEEE Transactions on Wireless Communications. - 1558-2248 .- 1536-1276. ; 20:11, s. 7302-7316
  • Journal article (peer-reviewed)abstract
    • We consider a single-anchor multiple-input multiple-output orthogonal frequency-division multiplexing system with imperfectly synchronized transmitter (Tx) and receiver (Rx) clocks, where the Rx estimates its position based on the received reference signals. The Tx, having (imperfect) prior knowledge about the Rx location and the surrounding geometry, transmits reference signals based on a set of fixed beams. We develop strategies for the power allocation among the beams aiming to minimize the expected Cramér-Rao lower bound for Rx positioning. Additional constraints on the design are included to make the optimized power allocation robust to uncertainty on the line-of-sight (LOS) path direction. Furthermore, the effect of clock asynchronism on the proposed allocation strategies is studied. Our evaluation results show that, for non-negligible synchronization error, it is optimal to allocate a large fraction of the available power for the illumination of the non-LOS (NLOS) paths, which help resolve the clock offset. In addition, the complexity reduction achieved by our proposed suboptimal approach incurs only a small performance degradation. We also propose an off-grid compressed sensing-based position estimation algorithm, which exploits the information on the clock offset provided by NLOS paths, and show that it is asymptotically efficient.
  •  
33.
  • Keskin, Furkan, 1988, et al. (author)
  • Optimal Spatial Signal Design for mmWave Positioning under Imperfect Synchronization
  • 2022
  • In: IEEE Transactions on Vehicular Technology. - 0018-9545 .- 1939-9359. ; 71:5, s. 5558-5563
  • Journal article (peer-reviewed)abstract
    • We consider the problem of spatial signal design for multipath-assisted mmWave positioning under limited prior knowledge on the users location and clock bias. We propose an optimal robust design and, based on the low-dimensional precoder structure under perfect prior knowledge, a codebook-based heuristic design with optimized beam power allocation. Through numerical results, we characterize different position-error-bound (PEB) regimes with respect to clock bias uncertainty and show that the proposed low-complexity codebook-based designs outperform the conventional directional beam codebook and achieve near-optimal PEB performance for both analog and digital architectures.
  •  
34.
  • Keskin, Musa Furkan, 1988, et al. (author)
  • ESPRIT-Oriented Precoder Design for mmWave Channel Estimation
  • 2023
  • In: 2023 IEEE International Conference on Communications Workshops: Sustainable Communications for Renaissance, ICC Workshops 2023. ; , s. 903-908
  • Conference paper (peer-reviewed)abstract
    • We consider the problem of ESPRIT-oriented precoder design for beamspace angle-of-departure (AoD) estimation in downlink mmWave multiple-input single-output communications. Standard precoders (i.e., directional/sum beams) yield poor performance in AoD estimation, while Cramer-Rao bound-optimized precoders undermine the so-called shift invariance property (SIP) of ESPRIT. To tackle this issue, the problem of designing ESPRIT-oriented precoders is formulated to jointly optimize over the precoding matrix and the SIP-restoring matrix of ESPRIT. We develop an alternating optimization approach that updates these two matrices under unit-modulus constraints for analog beamforming architectures. Simulation results demonstrate the validity of the proposed approach while providing valuable insights on the beampatterns of the ESPRIT-oriented precoders.
  •  
35.
  • Keykhosravi, Kamran, 1990, et al. (author)
  • RIS-Enabled SISO Localization under User Mobility and Spatial-Wideband Effects
  • 2022
  • In: IEEE Journal on Selected Topics in Signal Processing. - 1941-0484 .- 1932-4553. ; 16:5, s. 1125-1140
  • Journal article (peer-reviewed)abstract
    • Reconfigurable intelligent surface (RIS) is a promising technological enabler for the 6th generation (6G) of wireless systems with applications in localization and communication. In this paper, we consider the problem of positioning a single-antenna user in 3D space based on the received signal from a single-antenna base station and reflected signal from an RIS by taking into account the mobility of the user and spatial-wideband (WB) effects. To do so, we first derive the spatial-WB channel model under the far-field assumption, for orthogonal frequency-division multiplexing signal transmission with the user having a constant velocity. We derive the Cram\'er Rao bounds to serve as a benchmark. Furthermore, we devise a low-complexity estimator that attains the bounds in high signal-to-noise ratios. Our estimator neglects the spatial-WB effects and deals with the user mobility by estimating the radial velocities and compensating for their effects in an iterative fashion. We show that the spatial-WB effects can degrade the localization accuracy for large RIS sizes and large signal bandwidths as the direction of arrival or departure deviate from the RIS normal. In particular, for a 64 $\times$ 64 RIS, the proposed estimator is resilient against the spatial-WB effects up to 140 MHz bandwidth. Regarding user mobility, our results suggest that the velocity of the user influences neither the bounds nor the accuracy of our estimator. Specifically, we observe that the state of the user with a high speed (42 m/s) can be estimated virtually with the same accuracy as a static user.
  •  
36.
  • Keykhosravi, Kamran, 1990, et al. (author)
  • Semi-Passive 3D Positioning of Multiple RIS-Enabled Users
  • 2021
  • In: IEEE Transactions on Vehicular Technology. - 0018-9545 .- 1939-9359. ; 70:10, s. 11073-11077
  • Journal article (peer-reviewed)abstract
    • Reconfigurable intelligent surfaces (RISs) are set to be a revolutionary technology in the 6th generation of wireless systems. In this work, we study the application of RIS in a multi-user passive localization scenario, where we have one transmitter (TX) and multiple asynchronous receivers (RXs) with known locations. Classical approaches fail in this scenario due to lack of synchronization and lack of data association between multi-static measurements and users. To resolve this, we consider each user to be equipped with an RIS, and show that we can avoid the data association problem and estimate users' 3D position with submeter accuracy in a large area around the transmitter, using time-of-arrival measurements at the RXs. We develop a low-complexity estimator that attains the corresponding Cram\'er-Rao bound as well as a novel RIS phase profile design to remove inter-path interference.
  •  
37.
  • Keykhosravi, Kamran, 1990, et al. (author)
  • SISO RIS-Enabled Joint 3D Downlink Localization and Synchronization
  • 2021
  • In: IEEE International Conference on Communications. - 1550-3607.
  • Conference paper (peer-reviewed)abstract
    • We consider the problem of joint three-dimensional localization and synchronization for a single-input single-output (SISO) multi-carrier system in the presence of a reconfigurable intelligent surface (RIS), equipped with a uniform planar array. First, we derive the Cramér-Rao bounds (CRBs) on the estimation error of the channel parameters, namely, the angle-of-departure (AOD), composed of azimuth and elevation, from RIS to the user equipment (UE) and times-of-arrival (TOAs) for the path from the base station (BS) to UE and BS-RISUE reflection. In order to avoid high-dimensional search over the parameter space, we devise a low-complexity estimation algorithm that performs two 1D searches over the TOAs and one 2D search over the AODs. Simulation results demonstrate that the considered RIS-aided wireless system can provide submeter-level positioning and synchronization accuracy, materializing the positioning capability of Beyond 5G networks even with single-antenna BS and UE. Furthermore, the proposed estimator is shown to attain the CRB at a wide interval of distances between UE and RIS. Finally, we also investigate the scaling of the position error bound with the number of RIS elements.
  •  
38.
  • Nazari, Mohammad Ali, 1987, et al. (author)
  • MmWave 6D Radio Localization with a Snapshot Observation from a Single BS
  • 2023
  • In: IEEE Transactions on Vehicular Technology. - 0018-9545 .- 1939-9359. ; 72:7, s. 8914-8928
  • Journal article (peer-reviewed)abstract
    • Accurate and ubiquitous localization is crucial for a variety of applications such as logistics, navigation, intelligent transport, monitoring, control, and also for the benefit of communications. Exploiting millimeter-wave (mmWave) signals in 5G and Beyond 5G systems can provide accurate localization with limited infrastructure. We consider the single base station (BS) localization problem and extend it to 3D position and 3D orientation estimation of an unsynchronized multi-antenna user equipment (UE), using downlink multiple-input multiple-output orthogonal frequency-division multiplexing (MIMO-OFDM) signals. Through a Fisher information analysis, we show that the problem is often identifiable, provided that there is at least one multipath component in addition to the line-of-sight (LoS), even if the position of corresponding incidence point (IP) is a priori unknown. Subsequently, we pose a maximum likelihood (ML) estimation problem, to jointly estimate the 3D position and 3D orientation of the UE as well as several nuisance parameters (the UE clock offset and the positions of IPs corresponding to the multipath). The ML problem is a high-dimensional nonconvex optimization problem over a product of Euclidean and non-Euclidean manifolds. To avoid complex exhaustive search procedures, we propose a geometric initial estimate of all parameters, which reduces the problem to a 1-dimensional search over a finite interval. Numerical results show the efficiency of the proposed ad-hoc estimation, whose gap to the Cramér-Rao bound (CRB) is tightened using the ML estimation.
  •  
39.
  • Peng, Bile, 1985, et al. (author)
  • Communication Scheduling by Deep Reinforcement Learning for Remote Traffic State Estimation with Bayesian Inference
  • 2022
  • In: IEEE Transactions on Vehicular Technology. - 0018-9545 .- 1939-9359. ; 71:4, s. 4287-4300
  • Journal article (peer-reviewed)abstract
    • Traffic awareness is the prerequisite of autonomous driving. Given the limitation of on-board sensors (e.g., precision and price), remote measurement from either infrastructure or other vehicles can improve traffic safety. However, the wireless communication carrying the measurement result undergoes fading, noise and interference and has a certain probability of outage. When the communication fails, the vehicle state can only be predicted by Bayesian filtering with a low precision. Higher communication resource utilization (e.g., transmission power) reduces the outage probability and hence results in an improved estimation precision. The power control subject to an estimate variance constraint is a difficult problem due to the complicated mapping from transmit power to vehicle-state estimate variance. In this paper, we develop an estimator consisting of several Kalman filters (KFs) or extended Kalman filters (EKFs) and an interacting multiple model (IMM) to estimate and predict the vehicle state. We propose to apply deep reinforcement learning (DRL) for the transmit power optimization. In particular, we consider an intersection and a lane-changing scenario and apply proximal policy optimization (PPO) and soft actor-critic (SAC) to train the DRL model. Testing results show satisfactory power control strategies confining estimate variances below given threshold. SAC achieves higher performance compared to PPO.
  •  
40.
  • Peng, Bile, 1985, et al. (author)
  • Decentralized Scheduling for Cooperative Localization With Deep Reinforcement Learning
  • 2019
  • In: IEEE Transactions on Vehicular Technology. - : Institute of Electrical and Electronics Engineers Inc.. - 0018-9545 .- 1939-9359. ; 68:5, s. 4295-4305
  • Journal article (peer-reviewed)abstract
    • Cooperative localization is a promising solution to the vehicular high-accuracy localization problem. Despite its high potential, exhaustive measurement and information exchange between all adjacent vehicles are expensive and impractical for applications with limited resources. Greedy policies or hand-engineering heuristics may not be able to meet the requirement of complicated use cases. In this paper, we formulate a scheduling problem to improve the localization accuracy (measured through the Cramér-Rao lower bound) of every vehicle up to a given threshold using the minimum number of measurements. The problem is cast as a partially observable Markov decision process and solved using decentralized scheduling algorithms with deep reinforcement learning, which allow vehicles to optimize the scheduling (i.e., the instants to execute measurement and information exchange with each adjacent vehicle) in a distributed manner without a central controlling unit. Simulation results show that the proposed algorithms have a significant advantage over random and greedy policies in terms of both required numbers of measurements to localize all nodes and achievable localization precision with limited numbers of measurements.
  •  
41.
  • Shahmansoori, A., et al. (author)
  • Power Allocation for OFDM Wireless Network Localization Under Expectation and Robustness Constraints
  • 2017
  • In: IEEE Transactions on Wireless Communications. - : Institute of Electrical and Electronics Engineers (IEEE). - 1558-2248 .- 1536-1276. ; 16:3, s. 2027-2038
  • Journal article (peer-reviewed)abstract
    • In location-aware wireless networks, mobile nodes (agents) can obtain their positions using range measurements to other nodes with known positions (anchors). Optimal subcarrier power allocation at the anchors reduces positioning error and improves network lifetime and throughput. We present an optimization framework for subcarrier power allocations in network localization with the imperfect knowledge of network parameters based on the fundamental statistical limits. Power allocations with expectation and robustness constraints are obtained using semidefinite optimization problems in noniterative and iterative forms with both unicast and multicast transmissions. Results show that the allocations provide more accurate localization than non-robust designs under channel and agents positions uncertainty.
  •  
42.
  • Shahmansoori, A., et al. (author)
  • Robust power allocation for OFDM wireless network localization
  • 2015
  • In: 2015 IEEE International Conference on Communication Workshop, ICCW 2015. - 9781467363051 ; , s. 718-723
  • Conference paper (peer-reviewed)abstract
    • Reliable and accurate localization of users is critical for many applications in wireless networks. In range-based localization, the position of a node (agent) can be estimated using distance measurements to nodes with known positions (anchors). Optimal power allocation of the anchors reduces positioning error and improves network lifetime and throughput. We formulate and solve a robust power allocation optimization problem with a constraint on the localization accuracy for multicast and unicast orthogonal frequency division multiplexing signals. The localization accuracy is expressed in terms of the expected squared position error bound, accounting for uncertainties in the wireless channel as well as in the agents' positions. Simulation results show that robust power allocation improves localization accuracy compared to non-robust power allocation, with only a limited power penalty. © 2015 IEEE.
  •  
43.
  • Sünter, I., et al. (author)
  • Design and testing of a dual-camera payload for ESEO
  • 2016
  • In: Proceedings of the International Astronautical Congress, IAC. - : International Astronautical Federation, IAF.
  • Conference paper (peer-reviewed)abstract
    • Since 2012, European Space Agency (ESA), SITAEL and ten European universities have been developing the European Student Earth Orbiter (ESEO). The satellite bus is being designed, built and tested by SITAEL, whereas the payload modules are being developed by various universities throughout Europe. ESEO is a microsatellite to measure the radiation environment in Low Earth Orbit (LEO), test new technologies in space as well as take photos of Earth and other celestial bodies. The aim of the ESEO optical payload is to produce color images in the visible spectrum, mainly for public outreach purposes. Although, in addition to public outreach, the payload can also be used to monitor plankton blooms or changes in the polar ice caps. This paper presents the design, development and pre-launch testing of a lightweight and power-efficient dual-camera system for ESEO. The two-camera solution enables imaging of the same target with a different field of view. The wide angle camera provides context for telescopic images, making it easier to pinpoint the area that was photographed. The primary camera of the payload is a wide-angle camera based on the ESTCube-1 design with a 4.4 mm telecentric lens, VGA CMOS color sensor and a 700 nm IR cut-off filter. With a field of view of 46° × 35°, the ground resolution of the primary camera is around 1 km per pixel. The secondary camera is telescopic, has a Zeiss C Sonnar T∗ 1.5/50 lens, a 2592×1944 pixel CMOS color sensor and a Schott BG40 filter. With a field of view of 6.63° × 5°, the ground resolution of the secondary camera is about 20 m per pixel. The payload features configurable internal image processing, progressive image compression and non-volatile storage. The resulting payload weighs about 800 g, on average consumes less than 560 mW of power, with peaks up to 1.5 W. The payload is currently being tested and will be launched on ESEO at the end of 2016.
  •  
44.
  • Wu, Yibo, 1996, et al. (author)
  • Cooperative localization with angular measurements and posterior linearization
  • 2020
  • In: 2020 IEEE International Conference on Communications Workshops, ICC Workshops 2020 - Proceedings.
  • Conference paper (peer-reviewed)abstract
    • The application of cooperative localization in vehicular networks is attractive to improve accuracy and coverage of the positioning. Conventional distance measurements between vehicles are limited by the need for synchronization and provide no heading information of the vehicle. To address this, we present a cooperative localization algorithm using posterior linearization belief propagation (PLBP) utilizing angle-of-arrival (AoA)-only measurements. Simulation results show that both directional and positional root mean squared error (RMSE) of vehicles can be decreased significantly and converge to a low value in a few iterations. Furthermore, the influence of parameters for the vehicular network, such as vehicle density, communication radius, prior uncertainty, and AoA measurements noise, is analyzed.
  •  
45.
  • Wymeersch, Henk, 1976, et al. (author)
  • 5G mm Wave Downlink Vehicular Positioning
  • 2018
  • In: 2018 IEEE Global Communications Conference, GLOBECOM 2018 - Proceedings. - 2576-6813 .- 2334-0983. - 9781538647271
  • Conference paper (peer-reviewed)abstract
    • 5G new radio (NR) provides new opportunities for accurate positioning from a single reference station: large bandwidth combined with multiple antennas, at both the base station and user sides, allows for unparalleled angle and delay resolution. Nevertheless, positioning quality is affected by multipath and clock biases. We study, in terms of performance bounds and algorithms, the ability to localize a vehicle in the presence of multipath and unknown user clock bias. We find that when a sufficient number of paths is present, a vehicle can still be localized thanks to redundancy in the geometric constraints. Moreover, the 5G NR signals enable a vehicle to build up a map of the environment.
  •  
46.
  • Wymeersch, Henk, 1976, et al. (author)
  • Adaptive detection probability for mmWave 5G SLAM
  • 2020
  • In: 2nd 6G Wireless Summit 2020: Gain Edge for the 6G Era, 6G SUMMIT 2020.
  • Conference paper (peer-reviewed)abstract
    • In 5G simultaneous localization and mapping (SLAM), estimates of angles and delays of mm Wave channels are used to localize the user equipment and map the environment. The interface from the channel estimator to the SLAM method, which was previously limited to the channel parameters estimates and their uncertainties, is here augmented to include the detection probabilities of hypothesized landmarks, given certain a user location. These detection probabilities are used during data association and measurement update, which are important steps in any SLAM method. Due to the nature of mm Wave communication, these detection probabilities depend on the physical layer signal parameters, including beamforming, precoding, bandwidth, observation time, etc. In this paper, we derive these detection probabilities for different deterministic and stochastic channel models and highlight the importance of beamforming.
  •  
47.
  • Wymeersch, Henk, 1976, et al. (author)
  • Radio Localization and Sensing - Part I: Fundamentals
  • 2022
  • In: IEEE Communications Letters. - 1558-2558 .- 1089-7798. ; 26:12, s. 2816-2820
  • Journal article (peer-reviewed)abstract
    • This letter is part of a two-letter tutorial on radio localization and sensing, with focus on mobile radio systems in 5G mmWave and beyond. Part I introduces the fundamentals, covering an overview of the relevant literature, as well as the different aspects of localization and sensing problems. Then, different performance metrics are presented, which are important in the evaluation of methods. Methods are detailed in the last part of this letter. Part I thus provides the necessary background to delve into more forward-looking problems in Part II.
  •  
48.
  • Wymeersch, Henk, 1976, et al. (author)
  • Radio Localization and Sensing – Part II: State-of-the-art and Challenges
  • 2022
  • In: IEEE Communications Letters. - 1558-2558 .- 1089-7798. ; 26:12, s. 2821-2825
  • Journal article (peer-reviewed)abstract
    • This letter is part of a two-letter tutorial on radio localization and sensing, with a focus on mobile radio systems, i.e., 5G and beyond. Building on Part I, which focused on the fundamentals, here we go deeper into the state-of-the-art advances, as well as 6G, covering enablers and challenges related to modeling, coverage, and accuracy.
  •  
Skapa referenser, mejla, bekava och länka
  • Result 1-48 of 48

Kungliga biblioteket hanterar dina personuppgifter i enlighet med EU:s dataskyddsförordning (2018), GDPR. Läs mer om hur det funkar här.
Så här hanterar KB dina uppgifter vid användning av denna tjänst.

 
pil uppåt Close

Copy and save the link in order to return to this view