Techno-economics of Fiber vs. Microwave for Mobile Transport Network Deployments [Invited]

One of the challenges for network operators is to design and deploy cost-efficient transport networks (TNs) to meet the high capacity and strict latency/reliability requirements of today’s emerging services. Therefore, they need to consider different aspects, including the appropriate technology, the level of reconfigurability, and the functional split option. A crucial aspect of network design is assessing the impact of these aspects against the total cost of ownership (TCO), latency, and reliability performance of a given solution. For this reason, this paper proposes a framework to investigate the TCO, latency, and reliability performance of a set of fiber and microwave-based TN architectures. They are categorized based on their baseband functional split option and the reconfigurability capabilities of the equipment used. The results, based on real data from a non-incumbent operator, show that in most of the considered scenarios, a microwavebased TN exhibits lower TCO than a fiber-based one. The TCO gain may vary with the choice of the functional split option, geo-type, reconfigurability features, fiber trenching costs, and cost of microwave equipment, with a more significant impact in a dense urban geo-type, where for a low layer functional split option the fiber- and microwave-based architectures have a comparable TCO. Finally, it was found that the considered fiber and microwave architectures have almost similar average latency and connection availability performance. Both are suitable to meet the service requirements of 5G and beyond 5G services in most of the considered scenarios. Only in extreme latency-critical scenarios, a small number of the cells might not fully satisfy the latency requirements of a low layer split option due to multiple microwave hops in the microwave-based architecture

Lasercomm Activities at the German Aerospace Center’s Institute of Communications and Navigation

The German Aerospace Center (DLR) has a heritage of more than 25 years in working on optical inter-satellite and satellite-to-ground links. The Institute of Communications and Navigation (IKN), as a research organization of DLR, has developed coherent homodyne BPSK transmission schemes with world record sensitivity as they are now implemented in the space-proven Laser Communication Terminals (LCT) for the European Data Relay System (EDRS). Further research being pursued at IKN includes the development of transmission systems optimized for atmospheric scenarios such as LEO downlinks, aircraft downlinks and inter-HAP links (High Altitude Platforms). For such scenarios with extreme index-of-refraction turbulence, robust adaptive optics technologies have been investigated and suitable data transceivers have been tested. Furthermore, several verification campaigns with prototype flight terminals and optical ground stations (fixed and transportable) have been performed in recent years, providing a large data basis for optimizing the long-range FSO technology

Missions of Small Satellites Launched by the J-I Launch Vehicle

This paper presents the concept of the small satellites launched by the 1-1 launch vehicle of the National Space Development Agency of JAPAN (NASDA). On this concept, the missions of the small satellites are for the experiment and the validation of the earth observation. The satellite communications, and the others on orbit. For efficient achievements of these missions, the common satellite bus will be adopted for the solid launch vehicle J-I, in order to develop the each small satellite system quickly by low-cost

Current optical technologies for wireless access

The objective of this paper is to describe recent activities and investigations on free-space optics (FSO) or optical wireless and the excellent results achieved within SatNEx an EU-framework 6th programme and IC 0802 a COST action. In a first part, the FSO technology is briefly discussed. In a second part, we mention some performance evaluation criterions for the FSO. In third part, we briefly discuss some optical signal propagation experiments through the atmosphere by mentioning network architectures for FSO and then discuss the recent investigations in airborne and satellite application experiments for FSO. In part four, we mention some recent investigation results on modelling the FSO channel under fog conditions and atmospheric turbulence. Additionally, some recent major performance improvement results obtained by employing hybrid systems and using some specific modulation and coding schemes are presented

Gateway Station Geographical Planning for Emerging Non-Geostationary Satellites Constellations

Among the recent advances and innovations in satellite communications, Non-Geostationary Orbit (NGSO) satellite constellations are gaining popularity as a viable option for providing widespread broadband internet access and backhauling services. However, a more complex ground segment with multiple ground stations is necessary due to these satellites' high speeds and low altitudes. The complete dimensioning of the ground segment, including gateway optimal placement and the number of ground access points, remains a relevant open challenge. In this article, we provide an overview of the key factors that shall be considered for NGSO gateway station geographical planning. Subsequently, we propose a ground segment dimensioning approach that combines several criteria, such as rain attenuation, elevation angle, visibility, geographical constraints, and user traffic demands. The operational concept is first discussed, followed by a methodology that combines all these constraints into a single map-grid to select the best position for each gateway. Furthermore, a case study is presented, which demonstrates the performance of the proposed methodology, for one example constellation. Finally, we highlight relevant open challenges and key research directions in this area.Comment: 8 page

Scenario on Orbital Experiment System using Small Satellites of NASDA

This paper presents the scenario on orbital experiment system using small satellites of the National Space Development Agency of JAPAN (NASDA). On this scenario, the main missions of the small satellites are the experiment of the earth observation, the satellite communications, and the others on orbit. And the small satellites will be launched by the small launch vehicle J-I of NASDA. As the first mission of this scenario, NASDA had studied the Optical Inter-orbit Communication Engineering Test Satellite (OICETS) system, and has started its development from the spring of 1993. Through this study, the small common satellite bus had been studied for the OICETS mission and other future missions. As the second mission, the Maneuvering, Rendezvous, and Docking Technology Experiment (MATEX) mission is studied now

Non-Terrestrial Networks in the 6G Era: Challenges and Opportunities

Many organizations recognize non-terrestrial networks (NTNs) as a key component to provide cost-effective and high-capacity connectivity in future 6th generation (6G) wireless networks. Despite this premise, there are still many questions to be answered for proper network design, including those associated to latency and coverage constraints. In this paper, after reviewing research activities on NTNs, we present the characteristics and enabling technologies of NTNs in the 6G landscape and shed light on the challenges in the field that are still open for future research. As a case study, we evaluate the performance of an NTN scenario in which satellites use millimeter wave (mmWave) frequencies to provide access connectivity to on-the-ground mobile terminals as a function of different networking configurations.Comment: 8 pages, 4 figures, 2 tables, submitted for publication to the IEE

Testbed Emulator of Satellite-to-Ground FSO Downlink Affected by Atmospheric Seeing Including Scintillations and Clouds

Free Space Optics (FSO) technology enabling next-generation near-Earth communication is prone to severe propagation losses due to atmospheric-turbulence-induced fading and Mie scattering (clouds). As an alternative to the real-time evaluation of the weather effects over optical signal, a state-of-the-art laboratory testbed for verification of slant APD-based (Avalanche Photodiode) FSO links in laboratory conditions is proposed. In particular, a hardware channel emulator representing an FSO channel by means of fiber-coupled Variable Optical Attenuator (VOA) controlled by driver board and software is utilized. While atmospheric scintillation data are generated based on Radiosonde Observation (RAOB) databases combined with a statistical design approach, cloud attenuation is introduced using Mie theory together with empirical Log-Normal modeling. The estimation of atmospheric-turbulence-induced losses within the emulated optical downlink is done with an FSO IM/DD prototype (Intensity Modulation/Direct Detection) relying on two different data throughputs using a transmitter with external and internal modulation. Moreover, the receiver under-test is a high-speed 10 Gbps APD photodetector with integrated Transimpedance Amplifier (TIA) typically installed in OGSs (Optical Ground Stations) for LEO/GEO satellite communication. The overall testbed performance is addressed by a BER tester and a digital oscilloscope, providing BER graphs and eye diagrams that prove the applied approach for testing APD-TIA in the presence of weather-based disruptions. Furthermore, the testbed benefits from the used beam camera that measures the quality of the generated FSO beam