Formation-of-Arrays Antenna Technology for High-Throughput Mobile Non-Terrestrial Networks

Abstract

Effective integration of terrestrial and nonterrestrial segments is one of the key research avenues in the design of current and future wireless communication networks. To this aim, modern communication-satellite constellations intend to attain sufficiently high throughput in terms of bit rate per unit area on the ground by rather aggressive patterns of spatial frequency reuse. This goal calls for on-board narrow-beam antennas, whose size turns out to be in many cases incompatible with the size/mass and accommodation constraints of the hosting satellite. This paper investigates the attainable performance of large distributed arrays of antennas implemented as the ensemble of a few to many simpler sub-antennas of smaller sizes, carried by one (small) satellite each. The sub-antennas can in their turn be implemented like (regular) 2D arrays of simple radiating elements, realizing an overall (distributed) antenna architecture that we call "formation of arrays" (FoA). The satellites that implement this radiating architecture need to be relatively close to each other and constitute a formation of flying objects, to be coordinated and controlled as a whole. In this paper, we develop a theoretical analysis of an FoA antenna, and we show how to take advantage of this new technology to improve network throughput in a multi-beam S-band mobile communication network with low-earth or geostationary orbiting satellites directly providing 5G-like communication services to hand-held user terminals.

Distributed Approach to Satellite Direct-to-Cell Connectivity in 6G Non-Terrestrial Networks

“…Nevertheless, swarms of small satellites for D2C connectivity have received limited attention. The paper in [5] presented a formation of sub-arrays in geostationary Earth orbit (GEO) and LEO scenarios, but the LEO performance derived is similar to the conventional approach. The paper in [6] considered a swarm creating a distributed phased array for D2C connectivity, emphasizing the importance of swarm geometry in antenna performance, but considering only one radiating element per small satellite.…”

Optimizing a Formation-of-Arrays (FoA) Satellite Antenna System for Very High-Throughput Communications

“…As is known, the effort of integrating a nonterrestrial segment into current 5G (terrestrial) networks and forthcoming 6G networks is formidable [1]. An analysis performed in [2] concluded that a real integration of the two segments, in particular allowing end-users to utilize a smartphone, calls for the adoption of radically new technologies, such as the distributed very-large antenna 0018-9251 © IEEE for low Earth orbit (LEO) and geostationary Earth orbit (GEO) satellites introduced in [3]: a formation of arrays (FoA). The satellite systems currently deployed to provide direct to hand-held communications (e.g.…”

“…Our 4G service target is justified by the fact that providing 4G-like data rates to a conventional terrestrial hand-held terminal already represents a big technological challenge for the space segment, in particular for a GEO orbit. In terms of our current performance targets, the reader can refer to [3], whereby we size the space segment to provide data rates in the order of Mbps to a conventional low-antenna gain hand-held UT having the characteristic specified by 3GPP 5G NTN documents (e.g. [6]).…”

“…Coming to the subject and contribution of this paper, reference [3] already performed a system-wide analysis from a communication performance perspective (end-user available bit-rate as well as area spectral efficiency) and computed the benefits coming from the adoption of that technology, but it did not address three relevant issues in the design and optimization of the FoA structure, namely, i) intrinsic frequency selectivity of the FoA emission, ii) issues related to power generation to feed each FoA satellite, and iii) optimum configuration of the satellite formation to optimize radio emission and meet certain constraints related to power generation. The three topics that we have just mentioned are the ones that this paper specifically addresses, performing a detailed analysis and providing for each a viable solution.…”

“…In the design of a FoA, one has to consider this issue both in the intrinsic behavior of the antenna array carried by each satellite, and in the formation alignment. Following the approach presented in [3], the FoA is intended to provide 5G-like services at S-band (carrier frequency f 0 = 2.2 GHz) and with a signal bandwidth B RF = 60 MHz, so that the fractional bandwidth of the data-modulated signal is B RF /f 0 ≃ 3%: this setup cannot be considered narrowband for beamforming. Therefore, frequency selectivity may have a non-negligible impact on the digital link performance, and it has to be analyzed in detail -the subject of Sect.…”