5,908 research outputs found
Hybrid Satellite-Terrestrial Communication Networks for the Maritime Internet of Things: Key Technologies, Opportunities, and Challenges
With the rapid development of marine activities, there has been an increasing
number of maritime mobile terminals, as well as a growing demand for high-speed
and ultra-reliable maritime communications to keep them connected.
Traditionally, the maritime Internet of Things (IoT) is enabled by maritime
satellites. However, satellites are seriously restricted by their high latency
and relatively low data rate. As an alternative, shore & island-based base
stations (BSs) can be built to extend the coverage of terrestrial networks
using fourth-generation (4G), fifth-generation (5G), and beyond 5G services.
Unmanned aerial vehicles can also be exploited to serve as aerial maritime BSs.
Despite of all these approaches, there are still open issues for an efficient
maritime communication network (MCN). For example, due to the complicated
electromagnetic propagation environment, the limited geometrically available BS
sites, and rigorous service demands from mission-critical applications,
conventional communication and networking theories and methods should be
tailored for maritime scenarios. Towards this end, we provide a survey on the
demand for maritime communications, the state-of-the-art MCNs, and key
technologies for enhancing transmission efficiency, extending network coverage,
and provisioning maritime-specific services. Future challenges in developing an
environment-aware, service-driven, and integrated satellite-air-ground MCN to
be smart enough to utilize external auxiliary information, e.g., sea state and
atmosphere conditions, are also discussed
Architectures and Key Technical Challenges for 5G Systems Incorporating Satellites
Satellite Communication systems are a promising solution to extend and
complement terrestrial networks in unserved or under-served areas. This aspect
is reflected by recent commercial and standardisation endeavours. In
particular, 3GPP recently initiated a Study Item for New Radio-based, i.e., 5G,
Non-Terrestrial Networks aimed at deploying satellite systems either as a
stand-alone solution or as an integration to terrestrial networks in mobile
broadband and machine-type communication scenarios. However, typical satellite
channel impairments, as large path losses, delays, and Doppler shifts, pose
severe challenges to the realisation of a satellite-based NR network. In this
paper, based on the architecture options currently being discussed in the
standardisation fora, we discuss and assess the impact of the satellite channel
characteristics on the physical and Medium Access Control layers, both in terms
of transmitted waveforms and procedures for enhanced Mobile BroadBand (eMBB)
and NarrowBand-Internet of Things (NB-IoT) applications. The proposed analysis
shows that the main technical challenges are related to the PHY/MAC procedures,
in particular Random Access (RA), Timing Advance (TA), and Hybrid Automatic
Repeat reQuest (HARQ) and, depending on the considered service and
architecture, different solutions are proposed.Comment: Submitted to Transactions on Vehicular Technologies, April 201
LEO Satellite Constellations for 5G and Beyond: How Will They Reshape Vertical Domains?
The rapid development of communication technologies in the past decades has
provided immense vertical opportunities for individuals and enterprises.
However, conventional terrestrial cellular networks have unfortunately
neglected the huge geographical digital divide, since high bandwidth wireless
coverage is concentrated to urban areas. To meet the goal of ``connecting the
unconnected'', integrating low Earth orbit (LEO) satellites with the
terrestrial cellular networks has been widely considered as a promising
solution. In this article, we first introduce the development roadmap of LEO
satellite constellations (SatCons), including early attempts in LEO satellites
with the emerging LEO constellations. Further, we discuss the unique
opportunities of employing LEO SatCons for the delivery of integrating 5G
networks. Specifically, we present their key performance indicators, which
offer important guidelines for the design of associated enabling techniques,
and then discuss the potential impact of integrating LEO SatCons with typical
5G use cases, where we engrave our vision of various vertical domains reshaped
by LEO SatCons. Technical challenges are finally provided to specify future
research directions.Comment: 4 figures, 1 table, accepted by Communications Magazin
A COMPREHENSIVE REVIEW OF INTERNET OF THINGS WAVEFORMS FOR A DOD LOW EARTH ORBIT CUBESAT MESH NETWORK
The Department of Defense (DOD) requires the military to provide command and control during missions in locations where terrestrial communications infrastructure is unreliable or unavailable, which results in a high reliance on satellite communications (SATCOM). This is problematic because they use and consume more digital data in the operational environment. The DOD has several forms of data capable of meeting Internet of Things (IoT) transmission parameters that could be diversified onto an IoT network. This research assesses the potential for an IoT satellite constellation in Low Earth Orbit to provide an alternative, space-based communication platform to military units while offering increased overall SATCOM capacity and resiliency. This research explores alternative IoT waveforms and compatible transceivers in place of LoRaWAN for the NPS CENETIX Ortbial-1 CubeSat. The study uses a descriptive comparative research approach to simultaneously assess several variables. Five alternative waveforms—Sigfox, NB-IoT, LTE-M, Wi-sun, and Ingenu—are evaluated. NB-IoT, LTE-M, and Ingenu meet the threshold to be feasible alternatives to replace the LoRaWAN waveform in the Orbital-1 CubeSat. Six potential IoT transceivers are assessed as replacements. Two transceivers for the NB-IoT and LTE-M IoT waveforms and one transceiver from U-blox for the Ingenu waveform are assessed as compliant.Lieutenant, United States NavyApproved for public release. Distribution is unlimited
Integration of Satellites in 5G through LEO Constellations
The standardization of 5G systems is entering in its critical phase, with
3GPP that will publish the PHY standard by June 2017. In order to meet the
demanding 5G requirements both in terms of large throughput and global
connectivity, Satellite Communications provide a valuable resource to extend
and complement terrestrial networks. In this context, we consider a
heterogeneous architecture in which a LEO mega-constellation satellite system
provides backhaul connectivity to terrestrial 5G Relay Nodes, which create an
on-ground 5G network. Since large delays and Doppler shifts related to
satellite channels pose severe challenges to terrestrial-based systems, in this
paper we assess their impact on the future 5G PHY and MAC layer procedures. In
addition, solutions are proposed for Random Access, waveform numerology, and
HARQ procedures.Comment: Submitted to IEEE Global Communications Conference (GLOBECOM) 201
Synergizing Airborne Non-Terrestrial Networks and Reconfigurable Intelligent Surfaces-Aided 6G IoT
On the one hand, Reconfigurable Intelligent Surfaces (RISs) emerge as a
promising solution to meet the demand for higher data rates, improved coverage,
and efficient spectrum utilization. On the other hand, Non-Terrestrial Networks
(NTNs) offer unprecedented possibilities for global connectivity. Moreover, the
NTN can also support the upsurge in the number of Internet of Things (IoT)
devices by providing reliable and ubiquitous connectivity. Although NTNs have
shown promising results, there are several challenges associated with their
usage, such as signal propagation delays, interference, security, etc. In this
article, we have discussed the possibilities of integrating RIS with an NTN
platform to overcome the issues associated with NTN. Furthermore, through
experimental validation, we have demonstrated that the RIS-assisted NTN can
play a pivotal role in improving the performance of the entire communication
system.Comment: 15 pages, 5 figure
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