Deep space missions keep pushing for new frontiers affecting a wide spectrum of disciplines. To support the scientific achievements expected from new missions, communication technology is being pushed towards its limits [1]. A need to increase communication links data rate as well as to lower the operative signal-to-noise ratio (SNR) are identified. The adoption of advanced coding schemes such as ...

This paper deals with the feasibility of the new receiver scheme for telecommand space links, based on the adoption of short low-density parity-check codes recently introduced in the standard. Being able to reduce significantly the required signal-to-noise ratio, these codes have an impact on the acquisition, tracking and synchronization issues. All these aspects have been faced, both theoretically and practically through the realization of a breadboard that implements the core elements of the on-board receiver, and is able to demodulate and decode uplink signals employing the new codes. The breadboard incorporates innovative solutions to cope with the acquisition and synchronization problems, and a pioneering implementation of non-iterative decoders based on the most reliable basis algorithm.

This paper reports on an internal study carried out at the European Space Agency (ESA) for assessing the reference performance of Payload Data Transmitters achieved in the mid-term. This assessment is meant to provide input to the ESA roadmaps for the 2023 time frame. The assessment is carried out for various space missions, from low Earth to deep space orbits. Taking advantage of technology evolution combined with innovative architectures and advanced digital signal processing, the paper shows how the data return in several space missions can be dramatically increased by reasonably extrapolating existing RF technology.

Since their dawning, space communications have been among the strongest driving applications for the development of error correcting codes. Indeed, space-to-Earth telemetry (TM) links have extensively exploited advanced coding schemes, from convolutional codes to Reed-Solomon codes (also in concatenated form) and, more recently, from turbo codes to low-density parity-check (LDPC) codes. The efficiency of these schemes has been extensively proved in several papers and reports. The situation is a bit different for Earth-to-space telecommand (TC) links. Space TCs must reliably convey control information as well as software patches from Earth control centers to scientific payload instruments and engineering equipment onboard (O/B) spacecraft. The success of a mission may be compromised because of an error corrupting a TC message: a detected error causing no execution or, even worse, an undetected error causing a wrong execution. This imposes strict constraints on the maximum acceptable detected and undetected error rates.

This paper presents the detailed design and the key system performance results of a comprehensive laboratory demonstrator (testbed) for a hybrid satellite/terrestrial S-band mobile digital broadcasting system. The physical layer is based on an enhanced version of the digital video broadcasting-satellite to handheld (DVB-SH) standard, exploiting dual-polarization multiple-input-multiple-output (MIMO) technology. This complete digital MIMO demonstrator, which is the first of its kind, allows for an in-depth verification and optimization of the MIMO techniques applied to satellite broadcasting networks. Moreover, this demonstrator allows for complementing and confirming the theoretical or simulation-based findings published thus far. It is shown that dual-polarization MIMO diversity is able to provide remarkable gains in terms of satellite/terrestrial transmit power reduction and/or capacity increase compared with more conventional non-MIMO solutions. It is also demonstrated that the adoption of a relatively simple spatial multiplexing MIMO technique represents the best way to grasp these gains. This paper provides an extensive set of laboratory measurement results for existing stochastic satellite and hybrid MIMO channels, as well as results based on an S-band satellite-measured dual-polarization time series recently collected during a campaign sponsored by the European Space Agency. Results obtained using MIMO techniques are also compared with a dual- and single-polarization single-input-single-output (SISO) DVB-SH benchmark system and with computer simulation results.

The work presented in this paper aims at illustrating the improvements foreseen for the Payload Data Transmitter of Near Earth and Deep Space scientific missions. Taking advantage of technology evolution combined with innovative architectures and advanced digital signal processing, the paper shows how to increase dramatically the data return in severely power-constrained scenarios, typical of Deep Space and L2 scientific space missions.

In the frame of the “Advanced Techniques for High Data Rate Links for Earth Exploration Satellites" study, ESA Contract n. 22455/09/NL/JK, a set of SW [1] was developed to allow the system designer computing the end-to-end performance of the data downlink architecture of Earth Observation satellite in LEO orbit when using Variable Coding Modulation (VCM) techniques and comparing it against the achievable figure when Constant Coding Modulation (CCM) is used. In particular, the SW implements modulation and coding described in the CCSDS standard [2], pre-distortion techniques, and on-ground algorithms for mitigation of channel contribution to dual-polarization transmission. Moreover, the SW allows the user selecting the main mission parameters (e.g. orbit, ground station, link availability, non-linear amplifier, on-board RF filters, EIRP etc.) according to its customized scenario. VCM demonstrates the improvement of downlink data rate of Earth Observation satellite in LEO orbit system performance, by adapting case-by-case the coding/modulation scheme, especially for systems characterized by a ground station network based on different climate areas (e.g. Mediterranean, Near Polar, Desert Ground station) [3]. For a K-Band system, considering the typical availability requirement for Earth Observation satellite data downlink (i.e. 99.5%) a special care shall be paid to the atmospheric propagation; it is well known that rain attenuation is the most important impairments for probability lower than about 1%. The total attenuation exceeded for 0.1% of the average year in Ka band can be several dBs larger than attenuation exceeded for the same time percentage during non-rainy periods (about 95% of the total year for European climate). The high difference between atmospheric propagation in rain and non-rainy condition is worth to be further analysed: the disadvantage of dimensioning the link on the average year is to have a reduced throughput even during the clear-sky (i.e. non rainy) periods characterized by low values of atmospheric attenuation.

The paper aims at providing a preview of the performance evolution for a specific category of space mission, namely the high data rate payload data telemetry from a low Earth orbit (LEO) spacecraft to ground for Earth observation data downlink. This is done in order to assess the potential of the next generation of these systems as well as to provide a performance benchmark against which future developments –also based on alternative technologies such as optical transmission– may be compared. The key improvements come from adopting different link adaptation schemes.

Future high performance Earth Observation satellites in Low Earth Orbit (LEO) will be equipped with high rate telemetry architectures either based on X-Band (375MHz, from 8.025 GHz up to 8.4 GHz) in dual-polarization or on K-Band (25.5GHz up to 27 GHz); in particular, the migration to the K-Band is expected in case the available X-Band will not be able to sustain the mission requirements. They will be also characterized by the on-board availability of a set of coding and modulation schemes at several spectral efficiencies and different Signal-to-Noise Ratio (SNR) thresholds; these will enable the usage of Variable Coding Modulation (VCM) techniques to improve the system performance by adapting case-by-case the coding/modulation scheme to the actual local atmospheric conditions. Among the requirements that a communication system engineer shall consider in the design of the telemetry architecture, the link availability is usually not considered as a critical parameter: for X-Band is it a common approach to size the system at 99.5% of link availability at the end of coverage area i.e. at 5° of elevation angle of the ground station antenna. This paper will show that for future K-Band transmission the target link availability need to be carefully evaluated in dependence of the required data timeliness: as a general rule, a trade-off among data timeliness and overall data throughput is expected to be necessary before sizing the communication architecture.

SUMMARY In this paper, a proposal is sketched for realizing high data rate downlinks in next‐generation Ka band low Earth orbit (LEO) Earth Observation (EO) systems. The work aims at realistically assessing the throughput advantage stemming from link adaptation strategies—embraced by most wireless and satellite communication standards—compared with non‐adaptive transmission, which is the approach followed in conventional X band EO systems. The transmission strategies examined include constant, (static and dynamic) variable, and adaptive flavors of coding and modulation, each representing a different performance/system complexity trade‐off. Practicality is pursued to the extent possible by incorporating state‐of‐the‐art orbital, ground station, spacecraft, propagation, physical layer, and system implementation characteristics. The results manifest that under particular conditions, link adaptation offers throughput improvements of up to 100% against non‐adaptive transmission schemes in Ka band LEO EO systems. Copyright © 2012 John Wiley & Sons, Ltd.

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.

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.

In this paper, a preliminary investigation is carried out on the possible advantages of employing cooperative diversity to support next generation deep space networks envisaged to operate at Ka band. The background idea is to benefit from recent advances in cooperative protocols by relaying downlink signals from the spacecraft through a geostationary satellite to mitigate tropospheric fading. Numerical comparisons based on the outage probability for practical system parameters reveal great performance improvements.

Disclosed herein is a method comprising using a first frequency for communication in a first direction with an infrastructure node and a second frequency for communication in a second direction with the infrastructure node during a normal operation phase in a wireless network. The method may further comprise reversing the frequencies used for the communication in the first and second directions with the infrastructure node during a link reversal phase.

La presente invention concerne la minimisation d'un retard du a des demandes de repetition automatique dans un systeme de communication multi-saut, qui peut etre accomplie pour optimiser les performances d'applications contraintes par les delais, comme le protocole de voix sur Internet, VoIP). Le protocole decrit en rapport avec ces modes de realisation peut reduire les retransmissions possibles au premier saut (le saut reliant un nœud mobile a un nœud de relais). Certains modes de realisation peuvent donc proteger la liaison la plus susceptible d'erreur tout en reduisant le delai general experimente par l'utilisateur.

In this paper, the transmission of VoIP over WCDMA is considered, focusing on the enhanced uplink HSUPA. The main limitation to system capacity in such a scenario is the constant presence of an uplink control channel. A technical solution to overcome such a problem is presented and assessed by means of link simulations.