231 research outputs found
Generic Optimization of Linear Precoding in Multibeam Satellite Systems
Multibeam satellite systems have been employed to provide interactive
broadband services to geographical areas under-served by terrestrial
infrastructure. In this context, this paper studies joint multiuser linear
precoding design in the forward link of fixed multibeam satellite systems. We
provide a generic optimization framework for linear precoding design to handle
any objective functions of data rate with general linear and nonlinear power
constraints. To achieve this, an iterative algorithm which optimizes the
precoding vectors and power allocation alternatingly is proposed and most
importantly, the proposed algorithm is proved to always converge. The proposed
optimization algorithm is also applicable to nonlinear dirty paper coding. In
addition, the aforementioned problems and algorithms are extended to the case
that each terminal has multiple co-polarization or dual-polarization antennas.
Simulation results demonstrate substantial performance improvement of the
proposed schemes over conventional multibeam satellite systems, zero-forcing
and regularized zero-forcing precoding schemes in terms of meeting the traffic
demand. The performance of the proposed linear precoding scheme is also shown
to be very close to the dirty paper coding
Carrier Aggregation in Multi-Beam High Throughput Satellite Systems
Carrier Aggregation (CA) is an integral part of current terrestrial networks.
Its ability to enhance the peak data rate, to efficiently utilize the limited
available spectrum resources and to satisfy the demand for data-hungry
applications has drawn large attention from different wireless network
communities. Given the benefits of CA in the terrestrial wireless environment,
it is of great interest to analyze and evaluate the potential impact of CA in
the satellite domain. In this paper, we study CA in multibeam high throughput
satellite systems. We consider both inter-transponder and intra-transponder CA
at the satellite payload level of the communication stack, and we address the
problem of carrier-user assignment assuming that multiple users can be
multiplexed in each carrier. The transmission parameters of different carriers
are generated considering the transmission characteristics of carriers in
different transponders. In particular, we propose a flexible carrier allocation
approach for a CA-enabled multibeam satellite system targeting a proportionally
fair user demand satisfaction. Simulation results and analysis shed some light
on this rather unexplored scenario and demonstrate the feasibility of the CA in
satellite communication systems
Energy-efficient link resource allocation in the multibeam satellite downlink under QoS constraints
The paper proposes a novel adaptive coding and modulation scheme, based on DVB-S2X standard, which ensure very high spectral efficiency, and an energy-efficient power control (PC) algorithm to optimize the goodput over a multibeam satellite downlink. Results show performance improvement whenand compared withto conventional PC approaches based on rate satisfaction
A methodology to benchmark flexible payload architectures in a megaconstellation use case
International audienceThis paper proposes a methodology to benchmark satellite payload architectures and find the optimal trade-offs between high flexibility and low complexity. High flexibility would enable the satellite to adapt to various distributions of user terminals on the ground and fulfill the data rate demand of these users. Besides, low complexity is required to keep satellite networks competitive in the context of emerging 5G networks. To estimate the flexibility of a payload, an indicator to characterize the non-uniformity of user distributions is proposed. Each benchmarked payload may be characterized by a graph relating the throughput to this parameter further denoted mu. The payload provides the same throughput trends for different scenarios of user distributions with the same mu parameter. As a consequence, the average capacity of the system may be estimated by (a) calculating the probability distribution of mu over the orbit and (b) integrating the throughput based on this payload response. It thus results in a straightforward way for benchmarking payloads directly on an estimation of the averaged capacity, accounting for the user distribution over the earth. A simulation platform has been developed to characterize the payload throughput including the implementation of a resource allocation algorithm that accounts for constraints of various payloads. Using this definition and the developed tool, we benchmark a bent-pipe architecture, a beam hopping architecture and a hybrid beam-steering architecture for a LEO megaconstellation use case. The methodology showcases the interest for investigating different payload architectures depending on realistic traffic scenario analysis
Application of advanced on-board processing concepts to future satellite communications systems: Bibliography
Abstracts are presented of a literature survey of reports concerning the application of signal processing concepts. Approximately 300 references are included
Secure Satellite Communication Systems Design with Individual Secrecy Rate Constraints
In this paper, we study multibeam satellite secure communication through
physical (PHY) layer security techniques, i.e., joint power control and
beamforming. By first assuming that the Channel State Information (CSI) is
available and the beamforming weights are fixed, a novel secure satellite
system design is investigated to minimize the transmit power with individual
secrecy rate constraints. An iterative algorithm is proposed to obtain an
optimized power allocation strategy. Moreover, sub-optimal beamforming weights
are obtained by completely eliminating the co-channel interference and nulling
the eavesdroppers' signal simultaneously. In order to obtain jointly optimized
power allocation and beamforming strategy in some practical cases, e.g., with
certain estimation errors of the CSI, we further evaluate the impact of the
eavesdropper's CSI on the secure multibeam satellite system design. The
convergence of the iterative algorithm is proven under justifiable assumptions.
The performance is evaluated by taking into account the impact of the number of
antenna elements, number of beams, individual secrecy rate requirement, and
CSI. The proposed novel secure multibeam satellite system design can achieve
optimized power allocation to ensure the minimum individual secrecy rate
requirement. The results show that the joint beamforming scheme is more
favorable than fixed beamforming scheme, especially in the cases of a larger
number of satellite antenna elements and higher secrecy rate requirement.
Finally, we compare the results under the current satellite air-interface in
DVB-S2 and the results under Gaussian inputs.Comment: 34 pages, 10 figures, 1 table, submitted to "Transactions on
Information Forensics and Security
Destination-directed, packet-switching architecture for 30/20-GHz FDMA/TDM geostationary communications satellite network
A destination-directed packet switching architecture for a 30/20-GHz frequency division multiple access/time division multiplexed (FDMA/TDM) geostationary satellite communications network is discussed. Critical subsystems and problem areas are identified and addressed. Efforts have concentrated heavily on the space segment; however, the ground segment has been considered concurrently to ensure cost efficiency and realistic operational constraints
Evolution of High Throughput Satellite Systems: Vision, Requirements, and Key Technologies
High throughput satellites (HTS), with their digital payload technology, are
expected to play a key role as enablers of the upcoming 6G networks. HTS are
mainly designed to provide higher data rates and capacities. Fueled by
technological advancements including beamforming, advanced modulation
techniques, reconfigurable phased array technologies, and electronically
steerable antennas, HTS have emerged as a fundamental component for future
network generation. This paper offers a comprehensive state-of-the-art of HTS
systems, with a focus on standardization, patents, channel multiple access
techniques, routing, load balancing, and the role of software-defined
networking (SDN). In addition, we provide a vision for next-satellite systems
that we named as extremely-HTS (EHTS) toward autonomous satellites supported by
the main requirements and key technologies expected for these systems. The EHTS
system will be designed such that it maximizes spectrum reuse and data rates,
and flexibly steers the capacity to satisfy user demand. We introduce a novel
architecture for future regenerative payloads while summarizing the challenges
imposed by this architecture
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