Four-Dimensional Constellations for Dual-Polarized Satellite Communications

In this paper, we investigate the performance of constellations optimized for transmissions in dual-polar mobile satellite applications. These four-dimensional constellations (inphase and quadrature per polarization) are designed for joint transmission over the two polarizations. Such constellations enhance the reliability of the system by providing certain redundancy into their design. Their performance is compared with transmission of independent 2D constellations over each polarization. As performance metrics, the pragmatic achievable mutual information and the bit error rate have been considered. The gains serve to indicate the need to further investigate 4D constellation design and its application in dual-polar MIMO systems

Constellation Design in Four Dimensions under Average Power Constraint

In this paper we address the problem of constellation design in four dimensional space (4D) under average power constraint. We compare the performance of best lattice constellations with those optimized without any constraint on their structure. Even though the lattice based constellations provide the best minimum distance, usually they do not allow for a good binary labelling. Therefore, in more realistic system scenarios, up to a 2 dB gain can be obtained by properly optimizing the constellation and the corresponding binary labelling. We also investigate the performance of 4D constellations obtained by the Cartesian product of two 2D constellations

Return Link Optimized Resource Allocation for Satellite Communications in the Ku/Ka-Band

Broadband satellite networks play an important role in today’s worldwide telecommunication infrastructure, providing services to an increasing number of users. Therefore, an efficient management of the spectrum resources is required in order to meet the fast-growing service demand. To this purpose, this paper addresses the optimization of the return carrier frequency plan for a broadband network benefiting from adaptive return channel selection (ARCS). The optimization problem is formulated as a multiobjective instance aiming at minimizing the total bandwidth and the unused throughput by using integer linear programming techniques. So as to capture events in which multiple terminals experience fade simultaneously, the spatial correlation of the attenuation fields has been incorporated in the optimization process. Moreover, physical layer characteristics and a minimum guaranteed throughput per user have been included as optimization constraints. Hence, the final outcome of this paper is a general technique providing an optimized carrier allocation plan, i.e., the number of carriers required to cover a certain area and guarantee a given throughput to each user

Four-Dimensional Constellations for Dual-Polarized Satellite Communications

Abstract-In this paper, we investigate the performance of constellations optimized for transmissions in dual-polar mobile satellite applications. These four-dimensional constellations (inphase and quadrature per polarization) are designed for joint transmission over the two polarizations. Such constellations enhance the reliability of the system by providing certain redundancy into their design. Their performance is compared with transmission of independent 2D constellations over each polarization. As performance metrics, the pragmatic achievable mutual information and the bit error rate have been considered. The gains serve to indicate the need to further investigate 4D constellation design and its application in dual-polar MIMO systems

Advanced Signal Processing Techniques for Fixed and Mobile Satellite Communications

Enabling ultra fast systems has been widely investigated during recent decades. Although polarization has been deployed from the beginning in satellite communications, nowadays it is being exploited to increase the throughput of satellite links. More precisely, the application of diversity techniques to the polarization domain may provide reliable, robust, and fast satellite communications. Better and more flexible spectrum use is also possible if transmission and reception can take place simultaneously in close or even overlapping frequency bands. In this paper we investigate novel signal processing techniques to increase the throughput of satellite communications in fixed and mobile scenarios. First, we investigate four-dimensional (4D) constellations for the forward link. Second, we focus on the mobile scenario and introduce an adaptive algorithm which selects the optimal tuple of modulation order, coding rate, and MIMO scheme that maximizes the throughput constraint to a maximum packet error rate. Finally, we describe the operation of radio transceivers which cancel actively the self-interference posed by the transmit signal when operating in full-duplex mode

Enhancing mobile services with DVB-S2X superframing

DVB-S2X is the cornerstone for satellite communication standards forming the state of the art of broadband satellite waveforms. In this paper, we propose new application scenarios and advanced techniques, including a reference design implementing superframing, predistortion, a robust synchronization chain, and a plug-and-play channel interleaver. We demonstrate by means of software simulations and hardware tests that the DVB-S2X can be a common technology enabler for land-mobile, aeronautical, and maritime satellite scenarios in addition to the more traditional VSAT scenario, even in very challenging conditions (eg, very low signal-to-noise ratio)

On-board Signal Predistortion for Digital Transparent Satellites

On-board processing (OBP), a paradigm that allows for manipulation of the signal at the satellite transponder, is being embraced by a large section of the satellite community. Exploiting OBP can lead to efficient implementation, bandwidth saving, lower redundancy, and better performance. Enabling processing aboard a satellite necessitates re-assessing the implementation of a number of signal processing techniques which, so far, have been ground-centric. In this work, we investigate the possibility of implementing signal predistortion (SPD) aboard a satellite having digital transparent processor (DTP). Such satellites employ transponders that allow for the implementation of limited functionalities in the digital domain. On-board predistortion can then be performed on the digitized data and can provide better performance compared to on-ground techniques. However, the conversion to the digital domain performed by an analog-to-digital converter (ADC) introduces different types of noise. Among these, the clock jitter requires the implementation of estimation and compensation algorithms. In this paper we propose a reduced-complexity on-board signal predistortion algorithm capable of post-compensating the jitter introduced by the ADC, and pre-compensating the distortion generated by the amplifier

Performance Analysis of Noncoherent Frame Synchronization in Satellite Communications with Frequency Uncertainty

Emerging markets for satellite communications, such as maritime and aeronautical applications, require reliable communications in challenging conditions and low-cost, low-complexity user terminals. In this perspective, the synchronization chain is a fundamental part of the receiver and its design becomes critical. When a quadricorrelator is used as first stage of the synchronization chain so as to perform a coarse frequency estimation, then a noncoherent algorithm for frame synchronization can be employed as second stage. A popular algorithm for frame synchronization is the post-detection integration (PDI), whose noncoherent version (NCPDI) is quite robust to non-negligible residual frequency offsets. In this paper we will assess the performance of NCPDI in presence of a random uniformly-distributed residual frequency offset and will find a closed-form approximation for the probability of detection. Moreover, we will optimize the design parameters of NCPDI for a system operating at very low signal-to-noise ratio (VL-SNR) by minimizing the probability of missed detection for a given probability of false alarm

Two-Leg Deep Space Relay Architectures: Performance, Challenges, and Perspectives

In this paper, architectures for interplanetary communications that feature the use of a data relay are investigated. In the considered "two-leg" architecture, a spacecraft orbiting the Earth, or in orbit at a Lagrange point, receives data from a deep space probe (leg-1) and relays them towards ground (leg-2). Different wireless technologies for the interplanetary link, namely, radio frequencies above the Ka band and optical frequencies, are considered. Moreover, the cases of transparent and regenerative relaying as well as different different orbital configurations are addressed, offering a thorough analysis of such systems from different viewpoints. Results show that, under certain constraints in terms of pointing accuracy and onboard antenna size, the adoption of a two-leg architecture can achieve the data rates supported by direct space-to-Earth link configurations with remarkably smaller ground station antennas.Comment: 17 pages, 7 figures, 13 tables. To appear in IEEE Transactions on Aerospace and Electronic Systems, 202