67 research outputs found
DVB-S2x Enabled Precoding for High Throughput Satellite Systems
Multi-user Multiple-Input Multiple-Output (MU-MIMO) has allowed recent
releases of terrestrial LTE standards to achieve significant improvements in
terms of offered system capacity. The publications of the DVB-S2x standard and
particularly of its novel superframe structure is a key enabler for applying
similar interference management techniques -such as precoding- to multibeam
High Throughput Satellite (HTS) systems. This paper presents results resulting
from European Space Agency (ESA) funded R&D activities concerning the practical
issues that arise when precoding is applied over an aggressive frequency re-use
HTS network. In addressing these issues, the paper also proposes pragmatic
solutions that have been developed in order to overcome these limitations.
Through the application of a comprehensive system simulator, it is demonstrated
that important capacity gains (beyond 40%) are to be expected from applying
precoding even after introducing a number of significant practical impairments
Multicast Multigroup Precoding and User Scheduling for Frame-Based Satellite Communications
The present work focuses on the forward link of a broadband multibeam
satellite system that aggressively reuses the user link frequency resources.
Two fundamental practical challenges, namely the need to frame multiple users
per transmission and the per-antenna transmit power limitations, are addressed.
To this end, the so-called frame-based precoding problem is optimally solved
using the principles of physical layer multicasting to multiple co-channel
groups under per-antenna constraints. In this context, a novel optimization
problem that aims at maximizing the system sum rate under individual power
constraints is proposed. Added to that, the formulation is further extended to
include availability constraints. As a result, the high gains of the sum rate
optimal design are traded off to satisfy the stringent availability
requirements of satellite systems. Moreover, the throughput maximization with a
granular spectral efficiency versus SINR function, is formulated and solved.
Finally, a multicast-aware user scheduling policy, based on the channel state
information, is developed. Thus, substantial multiuser diversity gains are
gleaned. Numerical results over a realistic simulation environment exhibit as
much as 30% gains over conventional systems, even for 7 users per frame,
without modifying the framing structure of legacy communication standards.Comment: Accepted for publication to the IEEE Transactions on Wireless
Communications, 201
End-to-end Precoding Validation over a Live GEO Satellite Forward Link
In this paper we demonstrate end-to-end precoded multi-user multiple-input
single-output (MU-MISO) communications over a live GEO satellite link. Precoded
communications enable full frequency reuse (FFR) schemes in satellite
communications (SATCOM) to achieve broader service availability and higher
spectrum efficiency than with the conventional four-color (4CR) and two-color
(2CR) reuse approaches. In this scope, we develop an over-the-air test-bed for
end-to-end precoding validations. We use an actual multi-beam satellite to
transmit and receive precoded signals using the DVB-S2X standard based gateway
and user terminals. The developed system is capable of end-to-end real-time
communications over the satellite link including channel measurements and
precompensation. It is shown, that by successfully canceling inter-user
interference in the actual satellite FFR link precoding brings gains in terms
of enhanced SINR and increased system goodput.Comment: Submitted to IEEE Access Journa
Hardware Precoding Demonstration in Multi-Beam UHTS Communications under Realistic Payload Characteristics
In this paper, we present a new hardware test-bed to demonstrate closed-loop precoded communications for interference mitigation in multi-beam ultra high throughput satellite systems under realistic payload and channel impairments. We build the test-bed to demonstrate a real-time channel aided precoded transmission under realistic conditions such as the power constraints and satellite-payload non-linearities. We develop a scalable architecture of an SDR platform with the DVB-S2X piloting. The SDR platform consists of two parts: analog-to-digital (ADC) and digital-to-analog (DAC) converters preceded by radio frequency (RF) front-end and Field-Programmable Gate Array (FPGA) backend. The former introduces realistic impairments in the transmission chain such as carrier frequency and phase misalignments, quantization noise of multichannel ADC and DAC and non-linearities of RF components. It allows evaluating the performance of the precoded transmission in a more realistic environment rather than using only numerical simulations. We benchmark the performance of the communication standard in realistic channel scenarios, evaluate received signal
SNR, and measure the actual channel throughput using LDPC codes
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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