| 1. |
- Abdu, Tedros Salih, et al.
(author)
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Demand-Aware Onboard Payload Processor Management for High Throughput NGSO Satellite Systems
- 2023
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In: IEEE Transactions on Aerospace and Electronic Systems. - : Institute of Electrical and Electronics Engineers (IEEE). - 0018-9251. ; , s. 1-18
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Journal article (peer-reviewed)abstract
- High-Throughput Satellite (HTS) systems with digital payload technology have been identified as a key enabler to support 5G/6G high-data connectivity with wider coverage area. The satellite community has extensively explored resource allocation methods to achieve this target. Typically, these methods do not consider the intrinsic architecture of the flexible satellite digital payload, which consists of multiple processors responsible for receiving, processing, and transmitting the signals. This paper presents a demand-aware onboard processor management scheme for broadband Non-Geostationary (NGSO) satellites. In this context, we formulate an optimization problem to minimize the number of active on-board processors while meeting the system constraints and user requirements. As the problem is non-convex, we solve it in two steps. First, we transform the problem into demand-driven bandwidth allocation while fixing the number of processors. Second, using the bandwidth allocation solution, we determine the required number of processors with two methods: 1) sequential optimization with the Branch & Bound method and 2) Bin Packing with Next Fit, First Fit, and Best Fit methods. Finally, we demonstrate the proposed methods with extensive numerical results. It is shown that the Branch & Bound, Best Fit, and First Fit methods manage the processors better than the Next Fit method. Furthermore, Branch & Bound requires fewer processors than the above methods.
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| 2. |
- Bui, Van-Phuc, et al.
(author)
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Robust Congestion Control for Demand-Based Optimization in Precoded Multi-Beam High Throughput Satellite Communications
- 2022
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In: IEEE Transactions on Communications. - : Institute of Electrical and Electronics Engineers (IEEE). - 0090-6778. ; 70:10, s. 6918-6937
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Journal article (peer-reviewed)abstract
- High-throughput satellite communication systems are growing in strategic importance thanks to their role in delivering broadband services to mobile platforms and residences and/or businesses in rural and remote regions globally. Although precoding has emerged as a prominent technique to meet ever-increasing user demands, there is a lack of studies dealing with congestion control. This paper enhances the performance of multi-beam high throughput geostationary satellite systems under congestion, where the users' quality of service (QoS) demands cannot be fully satisfied with limited resources. In particular, we propose congestion control strategies, relying on simple power control schemes. We formulate a multi-objective optimization framework balancing the system sum-rate and the number of users satisfying their QoS requirements. Next, we propose two novel approaches that effectively handle the proposed multi-objective optimization problem. The former is a model-based approach that relies on the weighted sum method to enrich the number of satisfied users by solving a series of the sum-rate optimization problems in an iterative manner. The latter is a data-driven approach that offers a low-cost solution by utilizing supervised learning and exploiting the optimization structures as continuous mappings. The proposed general framework is evaluated for different linear precoding techniques, for which the low computational complexity algorithms are designed. Numerical results manifest that our proposed framework effectively handles the congestion issue and brings superior improvements of rate satisfaction to many users than previous works. Furthermore, the proposed algorithms show low run-time and make them realistic for practical systems.
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| 3. |
- Casini, Enrico, et al.
(author)
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Reduced Front-End Reception Requirements for Satellite Broadcast using Interference Processing
- 2008
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In: IEEE Transactions on Consumer Electronics. - 0098-3063. ; 54:4, s. 1555-1563
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Journal article (peer-reviewed)abstract
- The problem of fixed satellite broadcast reception is considered. The possibility of reducing the requirements on the antenna front-end dimensions is investigated. Interference processing and mitigation techniques are employed to cope with the increased level of adjacent system interference at the satellite broadcast receiver resulting from the less directive antenna. A novel satellite reception front-end antenna based on a multiple input receiver is proposed to adapt the interference processing methods to the broadcast reception scenario. The potential performance of the devised scheme is thoroughly discussed and assessed by extensive software simulations.
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| 4. |
- Christopoulos, Dimitrios, et al.
(author)
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Linear and nonlinear techniques for multibeam joint processing in satellite communications
- 2012
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In: EURASIP Journal on Wireless Communications and Networking. - : Springer Science and Business Media LLC. - 1687-1472 .- 1687-1499. ; , s. 162-
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Journal article (peer-reviewed)abstract
- Existing satellite communication standards such as DVB-S2, operate under highly-efficient adaptive coding and modulation schemes thus making significant progress in improving the spectral efficiencies of digital satellite broadcast systems. However, the constantly increasing demand for broadband and interactive satellite links emanates the need to apply novel interference mitigation techniques, striving towards Terabit throughput. In this direction, the objective of the present contribution is to investigate joint multiuser processing techniques for multibeam satellite systems. In the forward link, the performance of linear precoding is investigated with optimal nonlinear precoding (i.e., dirty article coding) acting as the upper performance limit. To this end, the resulting power and precoder design problems are approached through optimization methods. Similarly, in the return link the concept of linear filtering (i.e., linear minimum mean square error) is studied with the optimal successive interference cancelation acting as the performance limit. The derived capacity curves for both scenarios are compared to conventional satellite systems where beams are processed independently and interbeam interference is mitigated through a four color frequency reuse scheme, in order to quantify the potential gain of the proposed techniques.
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| 5. |
- Grotz, Joel, et al.
(author)
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Applicability Of Interference Processing To DTH Reception
- 2006
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In: Ninth International Workshop on Signal Processing for Space Communications, September 2006.
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Conference paper (other academic/artistic)abstract
- Today fixed satellite broadcast reception has to compete efficiently with other means of broadcast content delivery to end-users. The ease of reception is essential to maintain a high penetration rate under more competitive conditions. The introduction of DVB-S2 increases efficiency and allows for a higher throughput or a reduction of the reception equipment requirements. This means that a robust broadcast reception is conceivable with a reduced direct-to-home (DTH) antenna size. The current interference situation at common geostationary broadcast positions dictates the spatial discrimination requirements of common direct-to-home (DTH) reception antennas. A more robust coding rate or a relaxation of the frequency coordination constraints would obviously relax the requirements on the reception front-end but only at the expense of a reduced aggregate efficiency. The use of known interference processing schemes for DTH reception has been investigated under dual reception path scenarios, see [1]. The present work extends the concept by introducing linear pre-processing (LPP) to combine coherent reception paths. These mechanisms will only be practical if the transmitted broadcast signals are compliant with established standards (ie. DVB-S [5] or DVB-S2 [4]). The maximization of the efficiency is a main objective under given reception environments. We show how multi-user detection techniques can increase efficiency and allow reduced antenna size under realistic conditions.
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| 6. |
- Grotz, Joel, et al.
(author)
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Data-aided frequency synchronization under interference limited conditions
- 2005
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In: 2005 IEEE 61ST VEHICULAR TECHNOLOGY CONFERENCE. - : IEEE. ; , s. 2683-2686
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Conference paper (peer-reviewed)abstract
- Data-aided multi-user burst frequency synchronization under interference limited conditions is analyzed. It is assumed that a unique-word based synchronization mechanism is used to achieve synchronization. In a first approach this unique-word is assumed to be located at the beginning of the burst structure. The interference represents frequency-adjacent bursts that are coarsely time synchronous. This corresponds to a typical multi frequency (MF) TDMA system with co-channel interference (CCI) limited minimal frequency separation. A novel approach is analyzed to reduce the interference impact of the carrier offset estimation, applying interference cancellation iteratively to increase the estimation accuracy. We demonstrate improved frequency synchronization with this novel approach of iterative burst synchronization.
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| 7. |
- Grotz, Joel, et al.
(author)
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Decision-directed interference cancellation applied to satellite broadcast reception : 2005 IEEE 62ND VEHICULAR TECHNOLOGY CONFERENCE, 1-4, PROCEEDINGS
- 2005
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In: VTC2005-FALL. ; , s. 903-906
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Conference paper (peer-reviewed)abstract
- This paper investigates the usage of established interference cancellation techniques applied to the simultaneous reception of geostationary satellite broadcast signals from two or more satellites. In particular the reduction of interference from adjacent satellites is of interest, which would allow a reduction of the antenna size and the requirements on the directivity of the installation. The rejection of unwanted adjacent satellite interferers can imply a large equivalent parabolic reflector size to achieve the required spatial separation of the signals. The usage of small and cheap reception antennas at the end-user premises can be facilitated by the reduction of the requirements on the antenna characteristics in terms of adjacent satellite interference rejection, in particular for the joint reception of signals from two or more simultaneous geostationary orbital locations. In this study the novel approach of using simple decision directed interference reduction techniques at the symbol detection level is considered to relax the requirements on the reception system front-end.
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| 8. |
- Grotz, Joel, 1974-
(author)
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Interference Mitigation and Synchronization for Satellite Communications
- 2008
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Doctoral thesis (other academic/artistic)abstract
- Within this thesis, the satellite broadcast scenario of geostationary satellites is reviewed. The densely crowded geostationary arc in the common broadcast frequencies may create significant interference from adjacent satellites (ASI). The possible use of multiple-input receivers and of interference processing techniques is analyzed in this specific context. In addition the synchronization problem is studied under interference limited conditions for broadcast as well as broadband satellite systems.We address fixed satellite broadcast reception with the goal of decreasing the aperture of the receiving antenna. The front-end antenna size is commonly defined by the presence of interference from adjacent satellites. A small antenna aperture leads to interference from neighboring satellites utilizing the same frequency bands. We propose a multi-input reception system with subsequent joint detection which provides reliable communication in the presence of multiple interfering signals. An iterative least square technique is adopted combining spatial and temporal processing. This approach achieves robustness against pointing errors and against changing interference scenarios. Different temporal interference processing methods are evaluated, including Minimum Mean Square Error (MMSE) based iterative soft-decision interference cancellation as well as Iterative Least Square with Projection (ILSP) based approaches, which include spatial and temporal iterations. Furthermore the potential of an additional convolutional channel decoding step in the interference cancellation mechanism is verified.Also, we demonstrate how to accurately synchronize the signals as part of the detection procedure. The technique is evaluated in a realistic simulation study representing the conditions encountered in typical broadcast scenarios.In a second part of the thesis the problem of synchronization is reviewed in the context of interference limited scenarios for broadband satellite return channels. Spectral efficiency is of great concern in the return channel of satellite based broadband systems. In recent work the feasibility of increased efficiency by reducing channel spacing below the Symbol Rate was demonstrated using joint detection and decoding for a synchronized system. We extend this work by addressing the critical synchronization problem in the presence of adjacent channel interference (ACI) which limits performance as carrier spacing is reduced.A pilot sequence aided joint synchronization scheme for a multi-frequency time division multiple access (MF-TDMA) system is proposed. Based on a maximum likelihood (ML) criterion, the channel parameters, including frequency, time and phase are jointly estimated for the channel of interest and the adjacent channels. The impact of ACI on the synchronization and detection performance is investigated. It is shown that joint channel parameter estimation outperforms single carrier synchronization with reasonable additional computational complexity in the receiver. Based on the proposed synchronization scheme in conjunction with an appropriate joint detection mechanism the carrier spacing can be reduced significantly compared to current systems providing a substantial increase in spectral efficiency
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| 9. |
- Grotz, Joel, et al.
(author)
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Joint channel synchronization under interference limited conditions
- 2007
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In: IEEE Transactions on Wireless Communications. - : IEEE. - 1536-1276 .- 1558-2248. ; 6:10, s. 3781-3789
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Journal article (peer-reviewed)abstract
- Spectral efficiency is of great concern in the return channel of satellite based broadband systems. In [1] the feasibility of increased efficiency by reducing channel spacing below the Symbol Rate was demonstrated using joint detection and decoding for a synchronized system. We extend this work by addressing the critical synchronization problem in the presence of adjacent channel interference (ACI) which limits performance as carrier spacing is reduced. A pilot sequence aided joint synchronization scheme for a multi-frequency time division multiple access (MF-TDMA) system is proposed. Based on a maximum likelihood (ML) criterion, the channel parameters, including frequency, time and phase are jointly estimated for the channel of interest and the adjacent channels. The impact of ACI on the synchronization and detection performance is investigated. It is shown that joint channel parameter estimation outperforms single carrier synchronization with reasonable additional computational complexity in the receiver. Based on the proposed synchronization scheme in conjunction with an appropriate joint detection mechanism, see [1], carrier spacing can be reduced significantly compared to current systems providing a substantial increase in spectral efficiency.
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| 10. |
- Grotz, Joel, et al.
(author)
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MULTI INPUT LNB – DEMONSTRATOR OF A REFLECTOR FEED ARRAY RECEIVER FOR SATELLITE BROADCAST RECEPTION
- 2012
-
Conference paper (peer-reviewed)abstract
- A demonstrator setup of a customized receiver antenna, a multi-input low noise block down-converter (MLNB) is presented in this paper. This antenna concept is based on a reflector feed array reception antenna for satellite Ku-band broadcast reception. In specific circumstances the Ku-band broadcast reception can be subject to interference form adjacent satellites give the customer demand for compact and easy to install reception antennas suitable for direct-to-home (DTH) reception. In this context a compact 45cm Ku-band reception antenna with coherent 3-element feed has been defined according to specific reception system requirements for broadcast system and setup and tested in the context of the ESA ARTES 5.2 Project. The demonstrator consist of an antenna prototype conceived by FTA Inverto for coherent reception of 3 feeds and a beamforming chipset from ASTRON operating in L-band and based on an NXP SiGe technology and chipset processes as well as beamforming control software from SES TechCom. Antenna measurements in a compact antenna test range (CATR) as well as over satellite demonstrate the achievable reception gain re-configurability which permits to adapt the broadcast antenna front end to different reception scenarios. The demonstrated benefits to satellite broadcast reception are to first provide an antenna system to mitigate adjacent satellite interference via reconfigure antenna gain nulling, second provide an antenna system for reception of any desired satellite signal within a given azimuth opening angle as well as third provide assistance at installation via an auto-fine-pointing procedure. This paper presents the demonstrator setup and justifies and explains the design choices in the context of the framing commercial requirements. Furthermore the antenna simulations and measurement results are presented here in view of the technical specification defined. The antenna re-configurability and control procedures are presented as well as the related reconfiguration example results and performance.
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