MMSE Performance Analysis of Generalized Multibeam Satellite Channels (original) (raw)

Multi-User Detection in Multibeam Mobile Satellite Systems: A Fair Performance Evaluation

2013 IEEE 77th Vehicular Technology Conference (VTC Spring), 2013

Multi-User Detection (MUD) techniques are currently being examined as promising technologies for the next generation of broadband, interactive, multibeam, satellite communication (SatCom) systems. Results in the existing literature have shown that when full frequency and polarization reuse is employed and user signals are jointly processed at the gateway, more than threefold gains in terms of spectral efficiency over conventional systems can be obtained. However, the information theoretic results for the capacity of the multibeam satellite channel, are given under ideal assumptions, disregarding the implementation constraints of such an approach. Considering a real system implementation, the adoption of full resource reuse is bound to increase the payload complexity and power consumption. Since the novel techniques require extra payload resources, fairness issues in the comparison among the two approaches arise. The present contribution evaluates in a fair manner, the performance of the return link (RL) of a SatCom system serving mobile users that are jointly decoded at the receiver. More specifically, the achievable spectral efficiency of the assumed system is compared to a conventional system under the constraint of equal physical layer resource utilization. Furthermore, realistic link budgets for the RL of mobile SatComs are presented, thus allowing the comparison of the systems in terms of achievable throughput. Since the proposed systems operate under the same payload requirements as the conventional systems, the comparison can be regarded as fair. Finally, existing analytical formulas are also employed to provide closed form descriptions of the performance of clustered multibeam MUD, thus introducing insights on how the performance scales with respect to the system parameters.

Iterative interference cancellation and channel estimation in multibeam satellite systems

International Journal of Satellite Communications and Networking, 2007

This paper deals with the use of non-linear multiuser detection techniques to mitigate co-channel interference on the reverse link of multibeam satellite systems. These techniques allow more capacity efficient frequency reuse strategies than classical ones, as they make possible to cope with lower C/I. The considered system takes as a starting point the DVB-RCS standard, with the use of convolutional coding, and the use of the Ka-band.We propose different iterative interference cancellation schemes, which operate at the beamformer outputs, and which use information from decoders. The proposed receivers assume an initial single-user synchronization step: frame synchronization and timing recovery, and then perform channel estimation: beamformer coefficients; signal carrier phases and signal amplitudes.In a first step, these receivers are evaluated by simulation in terms of bit error rate and of channel estimation error on two interference configurations. For one of these receivers, sensitivity to imperfect timing recovery and to low-frequency offsets from user terminals is evaluated.In a second step, since the receiver performances highly depend on the interference configuration, we propose an approach to evaluate performances on a multibeam coverage (by taking into account the variability of interference configurations on the coverage). This method is used to compare different receivers on an example based on a coverage designed on a digital focal array feed reflector antenna. Copyright © 2007 John Wiley & Sons, Ltd.

Multiuser detection performance in multibeam satellite links under imperfect CSI

2012 Conference Record of the Forty Sixth Asilomar Conference on Signals, Systems and Computers (ASILOMAR), 2012

In multibeam satellite systems, there is a growing need for signal processing techniques able to mitigate the interference among beams, since they could enable a much more aggressive spectrum reuse. In this paper, we investigate the effect of the absence of perfect Channel State Information (CSI) at the receiver end of the multibeam satellite return link. Under the assumption of a large number of beams, random matrix theory tools are used to obtain closed-form expressions of the performance for a given channel matrix and different profiles of estimation errors.

Co-channel interference cancellation at the user terminal in multibeam satellite systems

2014 7th Advanced Satellite Multimedia Systems Conference and the 13th Signal Processing for Space Communications Workshop (ASMS/SPSC), 2014

We study the applicability of soft interference cancellation in the forward link of commercial multibeam satellite systems with focus on mobile terminals. We adopt a standard currently used in commercial satellite systems as a reference. The multibeam satellite antenna radiation diagram has been generated using a physical optics reflector model, while state-ofthe art channel models have been used for the land mobile satellite (LMS) channel. The interference pattern has been derived through a system simulator developed by the European Space Agency (ESA). Starting from the analysis of the interference pattern we study the application of a low complexity soft interference cancellation scheme. Our results show that, under realistic interference and propagation conditions and for existing standards, a two-colors frequency reuse scheme can be employed while guaranteeing service availability across the coverage and keeping the complexity at the user terminals relatively low. 1 this may not be the case if techniques such as time-frequency packing are applied [12]. However, this falls out of the scope of the present work.

Multiuser detection in multibeam satellite systems: Theoretical analysis and practical schemes

2015 IEEE 16th International Workshop on Signal Processing Advances in Wireless Communications (SPAWC), 2015

We consider the rates achievable by a user in a multibeam satellite system for unicast applications, and propose alternatives to the conventional single-user symbol-by-symbol detection applied at user terminals. Single-user detection is known to suffer from strong degradation when the terminal is located near the edge of the coverage area of a beam, and when aggressive frequency reuse is adopted. For this reason, we consider multiuser detection, and take into account the strongest interfering signal. We also analyze two additional transmission strategies requiring modifications at medium access control layer. We describe an information-theoretic framework to compare the different strategies by computing the information rate of the user in the reference beam. Furthermore, we analyze the performance of coded schemes that could approach the information-theoretic limits. We show that classical codes from the DVB-S2(X) standard are not suitable when multiuser detection is adopted, and we propose two ways to improve the performance, based on the redesign of the code and of the bit mapping.

Performance analysis of multiuser detection for multibeam satellites under rain fading

2012 6th Advanced Satellite Multimedia Systems Conference (ASMS) and 12th Signal Processing for Space Communications Workshop (SPSC), 2012

Multibeam satellite systems are nowadays widely employed, and their use is expected to grow in the next decades. This has raised the interest for signal processing techniques able to mitigate the interference among beams, since they could enable a much more aggressive spectrum reuse. From an engineering point of view, the system design must consider as an option aggressive frequency reuse patterns, with the need to evaluate the performance of the corresponding interfering canceling techniques for the usual impairments and non-idealities of the satellite link. In this paper, we investigate the effect of a practical impairment of great importance, namely, the attenuation due to the rain, on the performance of a return link which performs MMSE interference canceling. Analytical expressions are derived for a number of performance measures based on the statistical characterization of the rain attenuation.

Capacity analysis of multibeam joint decoding over composite satellite channels

2011 Conference Record of the Forty Fifth Asilomar Conference on Signals, Systems and Computers (ASILOMAR), 2011

The throughput of current multibeam satellite systems is limited by self interference. Interference mitigation techniques have the potential to significantly increase the spectral efficiency of these satellite communication systems. The present contribution investigates the ergodic capacity of the return link of a multibeam satellite system, where full frequency reuse is employed and user signals are jointly processed at the gateway. The proposed model incorporates correlated satellite antennas over Rician channels which represent some inherent characteristics of satellite communications. Additionally, the effects of shadowing caused by user mobility, are modeled via the lognormal distribution. Hence, a composite Rician/lognormal fading channel with fully correlated receive antennas is considered. For this channel, a new lower bound on the ergodic capacity is analytically deduced and verified through simulations.

Interference Coordination for the Return Link of a Multibeam Satellite System

Future internet demands are being increased dramatically year by year. Terrestrial systems are unable to satisfy these demands in all geographical areas and thus broadband access by satellite is a key service provision platform. Considering the traffic demands, the raw capacity should approach a Terabit/s by 2020 to meet these demands. The satellite communications network will be a star-based topology, where User Terminals (UT) from multiple beams communicate via central Gateway Earth Stations (GES). The return link from UT to satellite will use DVB-RCS2 Multi-Frequency Time Division Multiple Access (MF-TDMA) transmission scheme in Ka band (30GHz), while the return feeder link from satellite to GES in Q band (40 GHz). Due to generation of large number of narrow user beams, the interference starts becoming a limiting factor in the system’s dimensioning. Herein, interference coordination schemes, borrowed from terrestrial cellular systems, are examined in terms of applicability and C/I performance. In addition, an algorithm for dynamic interference coordination is proposed to schedule the transmissions of the users in time-frequency domain of the return link, aiming to improve the C/I. The performance of these schemes and the proposed algorithm is assessed over a 302 user beams satellite system with practical antenna radiation patterns.

Message-Splitting for Interference Cancellation in Multibeam Satellite Systems

2018 9th Advanced Satellite Multimedia Systems Conference and the 15th Signal Processing for Space Communications Workshop (ASMS/SPSC), 2018

This paper investigates a novel technique to deal with the interference in the forward link of multibeam satellite systems when aggressive frequency reuse schemes are employed. Taking into account only magnitude information about the forward channel, the gateway judiciously splits the messages to be transmitted into private and public parts. At the receive terminals, partial cancellation of the public messages is applied prior to private message detection. The practical significance of the absence of channel phase information is stressed and complemented by some additional insights on the implementation. Our numerical results show that, in terms of average total throughput, this technique combined with a 2-colour frequency reuse scheme can outperform a classic orthogonal system with a conservative 4-colour frequency reuse scheme, despite the additional co-channel interference.

On the Application of Multiuser Detection in Multibeam Satellite Systems

We study the achievable rates by a single user in multibeam satellite scenarios. We show alternatives to the conventional symbol-by-symbol detection applied at user terminals. Single user detection is known to suffer from strong degradation when the terminal is located near the edge of the coverage area, and when aggressive frequency reuse is adopted. For this reason, we consider multiuser detection, and take into account the strongest interfering signal. Moreover, we analyze a different transmission strategy, where the signals from two adjacent beams jointly serve two users in a time division multiplexing fashion. We describe an information-theoretic framework to compare different transmission/detection strategies by computing the information rate of the user in the reference beam.