Filter-bank multi-carrier (FBMC) modulations have recently been considered for the emerging wireless communication systems as a means to improve the utilization of the physical resources and the robustness to channel time variations. FBMC divides the overall frequency channel in a set of subchannels of bandwidth proportionally decreasing with the number of subchannels. If the number of subchannels is high enough, the bandwidth of each subchannel is small enough to assume that it is approximately flat. On the other hand, space-division multiple access (SDMA) is a recognized technique to support multiple access in the downlink of a multi-user system. The user signals are precoded at the base station equipped with multiple antennas to separate the users in the spatial domain. The application of SDMA to FBMC is unfortunately difficult when the channel is too frequency selective (or when the number of subchannels to too small) to assume flat subchannels. In that case, the system suffers from inter-symbol and inter-subchannel interference, besides the multi-user interference inherent to SDMA. State-of-the art solutions simply neglect the inter-symbol/subchannel interference. This article proposes a new SDMA precoder for FBMC capable of mitigating the three sources of interference. It is constructed per subchannel in order to keep an acceptable complexity and has the structure of a filter applied on each subchannel and its neighbors at twice the symbol rate. Numerical results demonstrate that the precoder can get rid of all the interference present in the system and benefit therefore from the diversity and power gains achievable with multiple antenna systems.

High throughput satellites have proven to be an excellent solution to provide Internet services to white spots or to complement other existing infrastructures. With the use of multi-beam antennas, the same frequency may be reused dozens of times across a single satellite coverage area, increasing the system capacity and profitability. Legacy frequency reuse patterns such as uncoordinated 4-color scheme ensure interference isolation at the expense of important capacity reduction, using only one fourth of the operator's share in the scarce Ka band. Thus, to increase the per-beam available bandwidth, it is necessary to look for more aggressive and efficient Frequency Reuse schemes, generating higher Co-Channel Interference which has to be analyzed and handled. In this paper, we focus on the DVB-RCS2 return link of a multi-beam satellite and investigate the possibility of reaching the upper bound of a coordinated 2-color system capacity through the use of Interference-aware User Scheduling techniques. We first formalize the problem as an Integer Linear Program and study the impact of greedy simplifications on the optimality and processing times of our optimization models.

Harmonization of terrestrial standards such that they would support satellite elements would offer several benefits. This work has started at 3GPP relating to 5G new radio (NR). Downlink initial access is one of the topics that has to be evaluated in this respect among many others. This paper studies detection of the synchronization signals included in the synchronization (SS) block of the 5G NR signal in satellite channels that have large, up to 720 kHz, Doppler frequency shift at 30 GHz carrier frequency. Furthermore, the reception of system information data in the SS block is considered. It is shown that using dedicated large frequency shift aware detectors it is possible to meet the 5G NR requirements in the detection part. However, the data part cannot be reliably received using one-shot reception at low signalto-noise values. Some alternative solutions are considered and evaluated though some of them require changes to the standard in order to be efficient.

No abstract

Abstract-Digital Video Broadcasting -Satellite -Second Generation (DVB-S2) is the current European standard for satellite broadcast and broadband communications. It relies on high order modulations up to 32-amplitude/phase-shift-keying (APSK) in order to increase the system spectral efficiency. Unfortunately, as the modulation order increases, the receiver becomes more sensitive to physical layer impairments, and notably to the distortions induced by the power amplifier and the channelizing filters aboard the satellite. Pre-distortion of the non-linear satellite channel has been studied for many years. However, the performance of existing pre-distortion algorithms generally becomes poor when high-order modulations are used on a non-linear channel with a long memory. In this paper, we investigate a new iterative method that pre-distorts blocks of transmitted symbols so as to minimize the Euclidian distance between the transmitted and received symbols. We also propose approximations to relax the pre-distorter complexity while keeping its performance acceptable.