Editorial

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Open AccessEditorial

Editorial: Special Issue “Satellite Networks for Massive IoT Communication”

by Riccardo De Gaudenzi and Beatriz Soret

Sensors 2022, 22(11), 4214; https://0-doi-org.brum.beds.ac.uk/10.3390/s22114214 - 01 Jun 2022

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The growing need to interconnect sensors and devices anytime, anywhere is stimulating the design and development of innovative solutions for efficiently supporting a wide variety of applications: from simple low-duty cycle sensors for which energy efficiency and low-cost are of paramount importance, to [...] Read more.

The growing need to interconnect sensors and devices anytime, anywhere is stimulating the design and development of innovative solutions for efficiently supporting a wide variety of applications: from simple low-duty cycle sensors for which energy efficiency and low-cost are of paramount importance, to more demanding platforms (e [...] Full article

(This article belongs to the Special Issue Satellite Networks for Massive IoT Communication)

Research

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15 pages, 3974 KiB

Open AccessArticle

Free Space Ground to Satellite Optical Communications Using Kramers–Kronig Transceiver in the Presence of Atmospheric Turbulence

by Mahdi Naghshvarianjahromi, Shiva Kumar and M. Jamal Deen

Sensors 2022, 22(9), 3435; https://0-doi-org.brum.beds.ac.uk/10.3390/s22093435 - 30 Apr 2022

Cited by 7 | Viewed by 2665

Abstract

Coherent detection provides the optimum performance for free space optical (FSO) communication systems. However, such detection systems are expensive and require digital phase noise compensation. In this paper, the transmission performance of long-haul FSO system for ground-to-satellite communication based on a Kramers–Kronig (KK) [...] Read more.

Coherent detection provides the optimum performance for free space optical (FSO) communication systems. However, such detection systems are expensive and require digital phase noise compensation. In this paper, the transmission performance of long-haul FSO system for ground-to-satellite communication based on a Kramers–Kronig (KK) transceiver is evaluated. KK transceivers utilize inexpensive direct detection receivers and the signal phase is retrieved from the received current using the well-known KK relations. KK transceivers are not sensitive to the laser phase noise and, hence, inexpensive lasers with large linewidths can be used at the transmitter. The transmission performance of coherent and KK transceivers is compared in various scenarios such as satellite-to-ground, satellite-to-satellite, and ground-to-satellite for weak, moderate, and strong turbulence. The results show that the transmission performance of a system based on the KK transceiver is comparable to that based on a coherent transceiver, but at a significantly lower system cost and complexity. It is shown that in the absence of turbulence, the coherent receiver has a ~3 dB performance advantage over the KK receiver. However, in the presence of strong turbulence, this performance advantage becomes negligible. Full article

(This article belongs to the Special Issue Satellite Networks for Massive IoT Communication)

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16 pages, 3256 KiB

Open AccessArticle

Cooperative Reception of Multiple Satellite Downlinks

by Haidar N. Al-Anbagi and Ivo Vertat

Sensors 2022, 22(8), 2856; https://0-doi-org.brum.beds.ac.uk/10.3390/s22082856 - 08 Apr 2022

Cited by 11 | Viewed by 1753

Abstract

Popular small satellites host individual sensors or sensor networks in space but require ground stations with directional antennas on rotators to download sensors’ data. Such ground stations can establish a single downlink communication with only one satellite at a time with high vulnerability [...] Read more.

Popular small satellites host individual sensors or sensor networks in space but require ground stations with directional antennas on rotators to download sensors’ data. Such ground stations can establish a single downlink communication with only one satellite at a time with high vulnerability to system outages when experiencing severe channel impairments or steering engine failures. To contribute to the area of improving the reception quality of small satellites signals, this paper presents a simple receive diversity scheme with proposed processing algorithms to virtually combine satellite downlink streams collected from multiple omnidirectional receivers. These algorithms process multiple received versions of the same signal from multiple geographically separated receiving sites to be combined in one virtual ground station. This virtual ground station helps detect the intended signal more reliably based only on a network of simple and cooperating software-defined radio receivers with omnidirectional antennas. The suggested receive diversity combining techniques can provide significant system performance improvement if compared to the performance of each individual receiving site. In addition, the probability of system outages is decreased even if one or more sites experience severe impairment consequences. Simulation results showed that the bit error rate (BER) of the combined stream is lower than the BER of the best quality receiving site if considered alone. Moreover, virtual ground stations with cooperative omnidirectional reception at geographically separated receivers also allow data to be received from multiple satellites in the same frequency band simultaneously, as software-defined receivers can digitize a wider portion of the frequency band. This can be a significant conceptual advantage as the number of small satellites transmitting data grows, and it is reasonable to avoid the corresponding necessary increase in the number of fully equipped ground stations with rotators. Full article

(This article belongs to the Special Issue Satellite Networks for Massive IoT Communication)

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26 pages, 897 KiB

Open AccessArticle

A New LoRa-like Transceiver Suited for LEO Satellite Communications

by Mohamed Amine Ben Temim, Guillaume Ferré and Romain Tajan

Sensors 2022, 22(5), 1830; https://0-doi-org.brum.beds.ac.uk/10.3390/s22051830 - 25 Feb 2022

Cited by 10 | Viewed by 3080

Abstract

LoRa is based on the chirp spread spectrum (CSS) modulation, which has been developed for low power and long-range wireless Internet of Things (IoT) communications. The structure of LoRa signals makes their decoding performance extremely sensitive to synchronization errors. To alleviate this constraint, [...] Read more.

LoRa is based on the chirp spread spectrum (CSS) modulation, which has been developed for low power and long-range wireless Internet of Things (IoT) communications. The structure of LoRa signals makes their decoding performance extremely sensitive to synchronization errors. To alleviate this constraint, we propose a modification of the LoRa physical layer, which we refer to as differential CSS (DCSS), associated with an original synchronization algorithm. Based on this modification, we are able to demodulate the received signals without performing a complete frequency synchronization and by tolerating some timing synchronization errors. Hence, our receiver can handle ultra narrow band LoRa-like signals since it has no limitation on the maximum carrier frequency offset, as is actually the case in the deployed LoRa receivers. In addition, in the presence of the Doppler shift varying along the packet duration, DCSS shows better performance than CSS, which makes our proposed receiver a good candidate for communication with a low-Earth orbit (LEO) satellite. Full article

(This article belongs to the Special Issue Satellite Networks for Massive IoT Communication)

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21 pages, 3883 KiB

Open AccessArticle

Recent Advances in Design and Implementation of Satellite Gateways for Massive Uncoordinated Access Networks

by Agostino Isca, Nader Alagha, Riccardo Andreotti and Marco Andrenacci

Sensors 2022, 22(2), 565; https://0-doi-org.brum.beds.ac.uk/10.3390/s22020565 - 12 Jan 2022

Cited by 5 | Viewed by 1878

Abstract

This paper provides an overview of recent results of a design, development and performance evaluation study of satellite gateways to receive and manage the traffic from a large population of uncoordinated user terminals. In particular, direct satellite access scenarios for machine-to-machine communications and [...] Read more.

This paper provides an overview of recent results of a design, development and performance evaluation study of satellite gateways to receive and manage the traffic from a large population of uncoordinated user terminals. In particular, direct satellite access scenarios for machine-to-machine communications and the Internet of Things have been targeted. Tests were carried out in a representative laboratory environment emulating realistic system scenarios. Performance results, as presented in this paper indicate that the proposed gateway architecture, based on an efficient access protocol, is capable of managing a very high number of uncoordinated terminals transmitting short messages with a low duty cycle. The applicability of the proposed solution to both geostationary and non-geostationary satellite systems has also been examined. The key concept of the gateway is based on a novel receiver architecture that implements the linear minimum mean square error (MMSE) spread spectrum signal detection and successive interference cancellation techniques. The receiver uses features such as a multi-stage detector together with a robust preamble detection. The end-to-end solution includes also the use of a new waveform with a quasi-constant envelope at the terminal to modulate and transmit data packets to be received and detected by the gateway via a satellite link. Full article

(This article belongs to the Special Issue Satellite Networks for Massive IoT Communication)

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22 pages, 1161 KiB

Open AccessArticle

Smart Beamforming for Direct LEO Satellite Access of Future IoT

by Marius Caus, Ana Perez-Neira and Eduard Mendez

Sensors 2021, 21(14), 4877; https://0-doi-org.brum.beds.ac.uk/10.3390/s21144877 - 17 Jul 2021

Cited by 12 | Viewed by 4828

Abstract

Non-terrestrial networks (NTN) are expected to play a key role in extending and complementing terrestrial 5G networks in order to provide services to air, sea, and un-served or under-served areas. This paper focuses the attention on the uplink, where terminals are able to [...] Read more.

Non-terrestrial networks (NTN) are expected to play a key role in extending and complementing terrestrial 5G networks in order to provide services to air, sea, and un-served or under-served areas. This paper focuses the attention on the uplink, where terminals are able to establish a direct link with the NTN at Ka-band. To reduce the collision probability when a large population of terminals is transmitting simultaneously, we propose a grant-free access scheme called resource sharing beamforming access (RSBA). We study RBSA for low Earth orbit (LEO) satellite communications with massive multiple-input multiple-output (MIMO). The idea is to benefit from the spatial diversity to decode multiple overlapped signals. We have devised a blind and open-loop beamforming technique, where neither the receiver must carry out brute-force search in azimuth and elevation, nor are the terminals required to report channel state information. Upon deriving the theoretical throughput, we show that RBSA is appropriate for grant-free access to LEO satellite, it reduces the probability of collision, and thus it increases the number of terminals that can access the media. Practical implementation aspects have been tackled, such as the estimation of the required statistics, and the determination of the number of users. Full article

(This article belongs to the Special Issue Satellite Networks for Massive IoT Communication)

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20 pages, 958 KiB

Open AccessArticle

Spectral Coexistence of QoS-Constrained and IoT Traffic in Satellite Systems

by Andrea Munari and Federico Clazzer

Sensors 2021, 21(14), 4630; https://0-doi-org.brum.beds.ac.uk/10.3390/s21144630 - 06 Jul 2021

Cited by 5 | Viewed by 1658

Abstract

The flourishing of Internet of Things (IoT) applications, characterized by vast transmitter populations and the sporadic transmission of small data units, demands innovative solutions for the sharing of the wireless medium. In this context, satellite connectivity is an important enabler for all scenarios [...] Read more.

The flourishing of Internet of Things (IoT) applications, characterized by vast transmitter populations and the sporadic transmission of small data units, demands innovative solutions for the sharing of the wireless medium. In this context, satellite connectivity is an important enabler for all scenarios in which terminals are under-served by terrestrial communications and are thus fundamental for providing worldwide coverage. In turn, the design of medium access policies that attain efficient use of the scarce spectrum and can cope with flexible yet unpredictable IoT traffic is of the utmost importance. Starting from these remarks, we investigate in this work the coexistence of a quality of service (QoS)-constrained service with IoT traffic in a shared spectrum as alternative to a more traditional orthogonal allocation among the two services, with an eye on satellite applications. Leaning on analytical tools, we provide achievable rate regions, assuming a slotted ALOHA access method for IoT terminals and accounting for practical aspects, such as the transmission of short packets. Interesting trends emerge, showcasing the benefit of an overlay allocation with respect to segregating the resources for the two services. Full article

(This article belongs to the Special Issue Satellite Networks for Massive IoT Communication)

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31 pages, 8608 KiB

Open AccessArticle

Is Satellite Ahead of Terrestrial in Deploying NOMA for Massive Machine-Type Communications?

by Antonio Arcidiacono, Daniele Finocchiaro, Riccardo De Gaudenzi, Oscar del Rio-Herrero, Stefano Cioni, Marco Andrenacci and Riccardo Andreotti

Sensors 2021, 21(13), 4290; https://0-doi-org.brum.beds.ac.uk/10.3390/s21134290 - 23 Jun 2021

Cited by 5 | Viewed by 2963

Abstract

Non-orthogonal multiple access (NOMA) technologies are considered key technologies for terrestrial 5G massive machine-type communications (mMTC) applications. It is less known that NOMA techniques were pioneered about ten years ago in the satellite domain to match the growing demand for mMTC services. This [...] Read more.

Non-orthogonal multiple access (NOMA) technologies are considered key technologies for terrestrial 5G massive machine-type communications (mMTC) applications. It is less known that NOMA techniques were pioneered about ten years ago in the satellite domain to match the growing demand for mMTC services. This paper presents the key features of the first NOMA-based satellite network, presenting not only the underlying technical solutions and measured performance but also the related deployment over the Eutelsat satellite fleet. In particular, we describe the specific ground segment developments for the user terminals and the gateway station. It is shown that the developed solution, based on an Enhanced Spread ALOHA random access technique, achieves an unprecedented throughput, scalability and service cost and is well matched to several mMTC satellite use cases. The ongoing R&D lines covering both the ground segment capabilities enhancement and the extension to satellite on-board packet demodulation are also outlined. These pioneering NOMA satellite technology developments and in-the-field deployments open up the possibility of developing and exploiting 5G mMTC satellite- and terrestrial-based systems in a synergic and interoperable architecture. Full article

(This article belongs to the Special Issue Satellite Networks for Massive IoT Communication)

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