| 1. |
- Abdu, Tedros Salih, et al.
(författare)
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Demand-Aware Onboard Payload Processor Management for High Throughput NGSO Satellite Systems
- 2023
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Ingår i: IEEE Transactions on Aerospace and Electronic Systems. - : Institute of Electrical and Electronics Engineers (IEEE). - 0018-9251. ; , s. 1-18
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Tidskriftsartikel (refereegranskat)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.
(författare)
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Robust Congestion Control for Demand-Based Optimization in Precoded Multi-Beam High Throughput Satellite Communications
- 2022
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Ingår i: IEEE Transactions on Communications. - : Institute of Electrical and Electronics Engineers (IEEE). - 0090-6778. ; 70:10, s. 6918-6937
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Tidskriftsartikel (refereegranskat)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. |
- Grotz, Joel, et al.
(författare)
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Applicability Of Interference Processing To DTH Reception
- 2006
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Ingår i: Ninth International Workshop on Signal Processing for Space Communications, September 2006.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)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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| 4. |
- Grotz, Joel, et al.
(författare)
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Data-aided frequency synchronization under interference limited conditions
- 2005
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Ingår i: 2005 IEEE 61ST VEHICULAR TECHNOLOGY CONFERENCE. - : IEEE. ; , s. 2683-2686
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Konferensbidrag (refereegranskat)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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| 5. |
- Grotz, Joel, et al.
(författare)
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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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Ingår i: VTC2005-FALL. ; , s. 903-906
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Konferensbidrag (refereegranskat)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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| 6. |
- Grotz, Joel, et al.
(författare)
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Joint channel synchronization under interference limited conditions
- 2007
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Ingår i: IEEE Transactions on Wireless Communications. - : IEEE. - 1536-1276 .- 1558-2248. ; 6:10, s. 3781-3789
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Tidskriftsartikel (refereegranskat)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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| 7. |
- Grotz, Joel, et al.
(författare)
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Signal Detection and Synchronization for Interference Overloaded Satellite Broadcast Reception
- 2010
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Ingår i: IEEE Transactions on Wireless Communications. - : IEEE. - 1536-1276 .- 1558-2248. ; 9:10, s. 3052-3063
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Tidskriftsartikel (refereegranskat)abstract
- We address fixed satellite broadcast reception with the goal of decreasing the aperture of the receiving antenna. The front-end antenna size is commonly determined 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 reception system with. M multiple input elements and with subsequent joint detection of desired and interfering signals that provides reliable communication in the presence of multiple interfering signals. An iterative least squares technique is adopted combining spatial and temporal processing and achieving robustness against pointing errors. Simulation results show how the proposed joint spatial and temporal adapted mechanism outperforms the simple combination of existing techniques under interference overloaded conditions. 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 a DVB-S2 broadcast scenario.
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| 8. |
- Schwarzenbarth, Klaus, et al.
(författare)
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MMSE based interference processing for satellite broadcast reception
- 2007
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Ingår i: 2007 IEEE 65TH VEHICULAR TECHNOLOGY CONFERENCE. - : IEEE. - 9781424402656 ; , s. 1345-1349
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Konferensbidrag (refereegranskat)abstract
- The problem of Adjacent Satellite Interference (ACI) within the Direct-To-Home (DTH) satellite broadcast reception scenario is considered. The use of small DTH front-end reception systems results inevitably in a higher interference level from adjacent satellites using the same frequency band. The growth in satellite communication and the trend to small dishes increases the ACI problem. The general problem of interference limited DTH reception has been studied in recent work, see [2]. This paper extends the work of [21 by considering additionally an MMSE based method based on the proposal by Beidas and Gamal, see [3]. The interference channel model and the iterative interference cancellation algorithm are introduced and applied to the DTH digital broadcast case. Simulations of the interesting scenarios are conducted and discussed. It is shown, that the algorithm works well over large ranges of the considered scenarios of frequency offset and signal power levels.
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