The present article carries out a review of MIMO-based techniques that have been recently proposed for satellite communications. Due to the plethora of MIMO interpretations in terrestrial systems and the particularities of satellite communications, this review is built on two pillars, namely fixed satellite and mobile satellite. Special attention is given to the characteristics of the satellite channel, which will ultimately determine the viability of MIMO over satellite. Finally, some future research directions are identified.

MIMO over Satellite: A Review

This paper deals with the problem of precoding in multibeam satellite systems. In contrast to general multiuser multiple-input-multiple-output cellular schemes, multibeam satellite architectures suffer from different challenges. First, satellite communications standards embed more than one user in each frame in order to increase the channel coding gain. This leads to the different so-called multigroup multicast models, whose optimization requires computationally complex operations. Second, when the data traffic is generated by several Earth stations (gateways), the precoding matrix must be distributively computed and meet additional payload restrictions. Third, since the feedback channel is adverse (large delay and quantization errors), the precoding must be able to deal with such uncertainties. In order to solve the aforementioned problems, we propose a two-stage precoding design in order to both limit the multibeam interference and to enhance the intra-beam minimum user signal power (i.e., the one that dictates the rate allocation per beam). A robust version of the proposed precoder based on a first perturbation model is presented. This mechanism behaves well when the channel state information is corrupted. Furthermore, we propose a per beam user grouping mechanism together with its robust version in order to increase the precoding gain. Finally, a method for dealing with the multiple gateway architecture is presented, which offers high throughputs with a low inter-gateway communication. The conceived designs are evaluated with a close-to-real beam pattern and the latest broadband communication standard for satellite communications.

/pdf/generalized-multicast-multibeam-precoding-for-satellite-4s9q9npo0x.pdf

Generalized Multicast Multibeam Precoding for Satellite Communications

Applicability of cognitive radio (CR) techniques to satellite communications is investigated and classification for the possible applications is foreseen in this paper. The proposed application scenarios include a) secondary use of satellite spectrum by a terrestrial system, b) secondary use of terrestrial spectrum by a satellite system, and c) a hybrid scenario where terrestrial network coverage is expanded by the use of satellite spots. Key challenges and enabling technologies for each scenario are discussed. Link budget analyses and system simulations are used to define operational limits for interference management in the mentioned scenarios regarding spectrum sensing, transmission power control, and directional antennas. The results show that CR techniques should be applied with caution in satellite bands. However, obvious potential to improve the spectrum efficiency can be seen in each scenario.

Application of cognitive radio techniques to satellite communication

This letter studies the potential capacity advantages of introducing a dual polarization per beam paradigm instead of the conventional single polarization per beam in mobile satellite broadcasting systems. This enables the application of MIMO techniques, not yet thoroughly investigated for mobile satellite systems. We engage in a fair system performance comparison between single polarization SISO and dual polarization non-MIMO and MIMO configurations based on the DVB-SH state-of-the-art mobile satellite standard. Along the course, the major advantages and pitfalls of a dual polarization per beam system from an interference, antenna, payload, and capacity perspective are highlighted.

To MIMO or Not To MIMO in Mobile Satellite Broadcasting Systems

This paper deals with the problem of precoding in multibeam satellite systems. In contrast to general multiuser multiple-input-multiple-output (MIMO) cellular schemes, multibeam satellite architectures suffer from different challenges. First, satellite communications standards embed more than one user in each frame in order to increase the channel coding gain. This leads to the different so-called multigroup multicast model, whose optimization requires computationally complex operations. Second, when the data traffic is generated by several Earth stations (gateways), the precoding matrix must be distributively computed and attain additional payload restrictions. Third, since the feedback channel is adverse (large delay and quantization errors), the precoding must be able to deal with such uncertainties. In order to solve the aforementioned problems, we propose a two-stage precoding design in order to both limit the multibeam interference and to enhance the intra-beam minimum user signal power (i.e. the one that dictates the rate allocation per beam). A robust version of the proposed precoder based on a first perturbation model is presented. This mechanism behaves well when the channel state information is corrupted. Furthermore, we propose a per beam user grouping mechanism together with its robust version in order to increase the precoding gain. Finally, a method for dealing with the multiple gateway architecture is presented, which offers high throughputs with a low inter-gateway communication. The conceived designs are evaluated in a close-to-real beam pattern and the latest broadband communication standard for satellite communications.

/pdf/generalized-multicast-multibeam-precoding-for-satellite-28nmitji56.pdf

This Letter addresses the statistical modeling of dual-polarized MIMO-LMS fading channels. In the absence of accurate experimental results, a statistical model for the characterization of MIMO-LMS channels is proposed based on consolidation of available experimental results for SISO-LMS and MIMO wireless channels as well as on their extrapolation to the MIMO-LMS case of interest. Moreover, a step-by-step methodology for the simulation and time-series generation of the proposed MIMO-LMS channel model is provided, which is useful for the design and performance assessment of MIMO-LMS transmission systems. The proposed model incorporates the effects of all relevant critical channel aspects in a flexible and fully-parameterized way.

https://upcommons.upc.edu/bitstream/handle/2117/10874/StatisticalModeling.pdf;sequence=1

Statistical Modeling of Dual-Polarized MIMO Land Mobile Satellite Channels

This paper addresses statistical modeling of MIMO LMS channels for satellite digital multimedia broadcasting (SDMB) applications. Dual polarization diversity is particularly considered. In the absence of accurate experimental MIMO LMS channel models in the literature, emphasis is put on the sound consolidation of available channel models for relevant single-input single-output (SISO) LMS and MIMO terrestrial wireless communications as well as on their novel extrapolation to the MIMO LMS case of interest. An accurate statistical model for L/S-band correlated dual circularly polarized 2×2 MIMO LMS channels is derived, which is fully-parameterized and can be further fine-tuned based on new available experimental results. Useful numerical results on the MIMO LMS channel capacity statistics are also presented illustrating the effect of several critical channel modeling parameters. (5 pages)

E. Casini

Papers

Statistical Modeling of Dual-Polarized MIMO Land Mobile Satellite Channels

On the statistical modeling of MIMO land mobile satellite channels: a consolidated approach