Frontiers in Space Technologies最新文献

{"title":"A Laser Link From Lunar Surface Employing Line-of-Sight MIMO","authors":"R. Schwarz, D. Giggenbach, Marcus T. Knopp, A. Knopp","doi":"10.3389/frspt.2021.750938","DOIUrl":"https://doi.org/10.3389/frspt.2021.750938","url":null,"abstract":"Future exploration of our planetary system relies on the Moon as a base and stepping stone to other planets. A high-rate data connection to this celestial body is, therefore, imperative. Free-space optical (FSO) communications will enable continuous broadband connectivity to Earth. Currently pursued concepts incorporate data relay satellites orbiting the Moon, where each individual satellite terminal has to overcome the lunar distance facing restraints on telescope apertures and on beam pointing and tracking accuracies. We propose a concept of one dedicated link originating from a robotic telescope station installed on the lunar surface. We study the conceptual architecture of such an FSO ground node at the lunar surface with a spotlight on the link design at the physical layer. In particular, we increase the FSO channel capacity through multiple transmission- and receiving-apertures. Our findings encourage the application of the Line-of-Sight (LOS) multiple-input multiple-output (MIMO) technology to FSO communications at large link distances typically coming along with space missions, as thereby the maximum MIMO capacity can be achieved. Directing our study on the link geometry such connections seem technically feasible at relatively low system complexity with the receivers located at a single site and the transmitters only few meters apart.","PeriodicalId":137674,"journal":{"name":"Frontiers in Space Technologies","volume":"44 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-10-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126737055","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Editorial: Signal Processing for Beyond 5G Non-Terrestrial Networks","authors":"C. Mosquera, Pantelis-Daniel M. Arapoglou","doi":"10.3389/frspt.2021.780171","DOIUrl":"https://doi.org/10.3389/frspt.2021.780171","url":null,"abstract":"Signal processing has long been playing an essential role in wireless terrestrial and satellite communications. Terrestrial networks are deploying new 5G based networks in various frequency bands, some of those in millimetre waves, the traditional realm of satellite networks, so that flexible mechanisms of sharing and coexistence will become more relevant. At the same time, the advent of new non-terrestrial wireless solutions such as High Altitude Platforms or highly dense Low Earth Orbit (LEO) constellations is positioning nonterrestrial networks (NTN) for a more decisive role in global data provision and ubiquitous coverage. However, a full integration between terrestrial and non-terrestrial networks is still not present; the 3rd Generation Partnership Project (3GPP) has concluded some initial studies on the role of NTN in 5G, a Work Item is expected to finalize in 2021, andNTN standardization in 5G is expected to take place in 3GPP Releases 17 and 18. It is likely that for some years to come, both networks will still remain complementary, with a potential real integration given by the timeframe of 6G, where NTN is considered key in providing connectivity to rural and underprivileged areas. There is a strong need for signal processing R&D in the new NTN, which at the same time helps to close the bridgewith terrestrial networks: the farther awaywemove from the physical layer, themore commonalities can be found between space and terrestrial segments. The sharing of radio frequency bands and the dynamic usage of resources allow to operationally reconfigure network connections. In this context, the signal processing in the transmitters, receivers, and network control systems face significant requirements to access frequency resources dynamically, detect interference, optimize the network configuration, and configure the radio resources operationally. Signal processingmust be used to leverage the flexibility of resource allocation in NTN, including GEO, MEO and LEO satellites, aerial platforms and even unmanned aerial vehicles (UAV). Four contributions have been included in this collection to illustrate the key role of signal processing at the interplay with networking, scheduling and antenna technology. The paper “Precoding with Received-Interference Power Control for Multibeam Satellite Communication Systems” (Lagunas et al.) builds on classical zero-forcing based precoders to propose a new scheme to reduce the sensitivity to the user scheduling, making it also possible to operate under overloaded conditions. As the number of beams increases, and aggressive frequency reuse is desired to get the most out of the scarce available spectrum, techniques like that exposed in this paper can help to bridge the gap between user scheduling and physical layer methods. The paper “Field Trial on 5G New Radio over Satellite” (Völk et al.) contributes with a practical testbed, featuring the use of a GEO satellite for backhauling a 5G mobile node. A commercial off","PeriodicalId":137674,"journal":{"name":"Frontiers in Space Technologies","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-10-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128434544","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Coherent Contention Resolution Diversity Slotted ALOHA: An Improved Multiple Access Method for Satellite IoT System","authors":"Ziwei Liu, Tiantian Zhu, Chen Zhang, Gengxin Zhang, Shanshan Zhao","doi":"10.3389/frspt.2021.755546","DOIUrl":"https://doi.org/10.3389/frspt.2021.755546","url":null,"abstract":"For Beyond 5G/6G system, satellite communication systems become an effective component of the space and terrestrial integrated network. Among typical applications, massive Machine Type of Communication (mMTC) is a promising and challenging application. The demands of low power consumption and light signaling make random access methods as the potential solution. Up to now, contention resolution-based ALOHA methods, such as contention resolution diversity slotted ALOHA (CRDSA), improve the throughput significantly. However, its throughput will meet the inflection point soon with the normalized load increasing since collisionless packets are hardly existing. In fact, the diversity of transmitting packets is not utilized totally. In this paper, an improved random access method, named coherent CRDSA method (C-CRDSA), is proposed. It accumulates replicated packets coherently at receiver and further improve the throughput over CRDSA. Detailed derivations and simulations are given. Simulation results corroborate the effectiveness of the proposed method.","PeriodicalId":137674,"journal":{"name":"Frontiers in Space Technologies","volume":"23 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134531423","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Multi-Satellite Cooperative Beamforming ALOHA for LEO Satellite IoT Networks","authors":"R. Liu, T. Hong, Xiaojin Ding, Yunfeng Wang, Gengxin Zhang","doi":"10.3389/frspt.2021.755520","DOIUrl":"https://doi.org/10.3389/frspt.2021.755520","url":null,"abstract":"In this paper, we proposed a cooperative beamforming ALOHA (CBA) scheme based on linearly constrained minimum variance criterion for low Earth orbit satellite (LEO) IoT networks to solve the problem of ‘deadlock’ in multi-satellite scenario. In multi-satellite overlapping coverage areas, packets can be received by multiple satellite receivers by sending them only once, which forms the concept of spatial diversity. The cooperative beamforming collision resolution technique combined with successive interference cancellation scheme is design to efficiently resolve packet collision by iteration way at the gateway station. The performance of cooperative beamforming ALOHA scheme is evaluated via mathematical analysis and simulations. Simulation results show that the proposed CBA scheme can effectively solve the problem of ‘deadlock’ and improve the performances of random access compared with benchmark problems.","PeriodicalId":137674,"journal":{"name":"Frontiers in Space Technologies","volume":"37 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-10-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132391445","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Contamination Control for Ultra-Sensitive Life-Detection Missions","authors":"J. Eigenbrode, R. Gold, J. Canham, Erich Schulze, A. Davila, A. Seas, T. Errigo, Faith Kujawa, D. Kusnierkiewicz, C. Lorentson, C. McKay","doi":"10.3389/frspt.2021.734423","DOIUrl":"https://doi.org/10.3389/frspt.2021.734423","url":null,"abstract":"A key science priority for planetary exploration is to search for signs of life in our Solar System. Life-detection mission concepts aim to assess whether or not biomolecular signatures of life are present, which requires highly sensitive instrumentation. This introduces greater risk of false positives, and perhaps false negatives. Stringent science-derived contamination requirements for achieving science measurements on life-detection missions necessitate mitigation approaches that minimize, protect from, and prevent science-relevant contamination of critical surfaces of the science payload and provide high confidence to life-detection determinations. To this end, we report on technology advances that focus on understanding contamination transfer from pre-launch processing to end of mission using high-fidelity physics in the form of computational fluid dynamics and sorption physics for monolayer adsorption/desorption, and on developing a new full-spacecraft bio-molecular barrier design that restricts contamination of the spacecraft and instruments by the launch vehicle hardware. The bio-molecular barrier isolates the spacecraft from biological, molecular, and particulate contamination from the external environment. Models were used to evaluate contamination transport for a designs reference mission that utilizes the barrier. Results of the modeling verify the efficacy of the barrier and an in-cruise decontamination activity. Overall mission contamination tracking from launch to science operations demonstrated exceptionally low probability on contamination impacting science measurements, meeting the stringent contamination requirements of femtomolar levels of compounds. These advances will enable planetary missions that aim to detect and identify signatures of life in our Solar System.","PeriodicalId":137674,"journal":{"name":"Frontiers in Space Technologies","volume":"20 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-10-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127876351","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Design and Implementation of Blind Source Separation Based on BP Neural Network in Space-Based AIS","authors":"Chengjie Li, Lidong Zhu, Zhongqiang Luo, Zhen Zhang, Yilun Liu, Ying Yang","doi":"10.3389/frspt.2021.756478","DOIUrl":"https://doi.org/10.3389/frspt.2021.756478","url":null,"abstract":"In space-based AIS (Automatic Identification System), due to the high orbit and wide coverage of the satellite, there are many self-organizing communities within the observation range of the satellite, and the signals will inevitably conflict, which reduces the probability of ship detection. In this paper, to improve system processing power and security, according to the characteristics of neural network that can efficiently find the optimal solution of a problem, proposes a method that combines the problem of blind source separation with BP neural network, using the generated suitable data set to train the neural network, thereby automatically generating a traditional blind signal separation algorithm with a more stable separation effect. At last, through the simulation results of combining the blind source separation problem with BP neural network, the performance and stability of the space-based AIS can be effectively improved.","PeriodicalId":137674,"journal":{"name":"Frontiers in Space Technologies","volume":"87 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-09-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114997656","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Miniaturised Instrumentation for the Detection of Biosignatures in Ocean Worlds of the Solar System","authors":"J. Chela-Flores","doi":"10.3389/frspt.2021.703809","DOIUrl":"https://doi.org/10.3389/frspt.2021.703809","url":null,"abstract":"This review of miniaturised instrumentation is motivated by the ongoing and forthcoming exploration of the confirmed, or candidate ocean worlds of the Solar System. It begins with a section on the evolution of instrumentation itself, ranging from the early efforts up to the current rich-heritage miniaturised mass spectrometers approved for missions to the Jovian system. The geochemistry of sulphur stable isotopes was introduced for life detection at the beginning of the present century. Miniaturised instruments allow the measurement of geochemical biosignatures with their underlying biogenic coding, which are more robust after death than cellular organic molecules. The role of known stable sulphur isotope fractionation by sulphate-reducing bacteria is discussed. Habitable ocean worlds are discussed, beginning with analogies from the first ocean world known in the Solar System that has always being available for scientific exploration, our own. Instrumentation can allow the search for biosignatures, not only on the icy Galilean moons, but also beyond. Observed sulphur fractionation on Earth suggests a testable “Sulphur Hypothesis”, namely throughout the Solar System chemoautotrophy, past or present, has left, or are leaving biosignatures codified in sulphur fractionations. A preliminary feasible test is provided with a discussion of a previously formulated “Sulphur Dilemma”: It was the Galileo mission that forced it upon us, when the Europan sulphur patches of non-ice surficial elements were discovered. Biogenic fractionations up to and beyond δ34S = −70‰ denote biogenic, rather than inorganic processes, which are measurable with the available high sensitivity miniaturised mass spectrometers. Finally, we comment on the long-term exploration of ocean worlds in the neighbourhood of the gas and ice giants.","PeriodicalId":137674,"journal":{"name":"Frontiers in Space Technologies","volume":"299 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-07-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131510298","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Precoding With Received-Interference Power Control for Multibeam Satellite Communication Systems","authors":"E. Lagunas, A. Pérez-Neira, M. Martínez, M. Lagunas, M. Vázquez, B. Ottersten","doi":"10.3389/frspt.2021.662883","DOIUrl":"https://doi.org/10.3389/frspt.2021.662883","url":null,"abstract":"Zero-Forcing (ZF) and Regularized Zero-Forcing (RZF) precoding are low-complexity sub-optimal solutions widely accepted in the satellite communications community to mitigate the resulting co-channel interference caused by aggressive frequency reuse. However, both are sensitive to the conditioning of the channel matrix, which can greatly reduce the achievable gains. This paper brings the attention to the benefits of a design that allows some residual received interference power at the co-channel users. The motivation behind this approach is to relax the dependence on the matrix inversion procedure involved in conventional precoding schemes. In particular, the proposed scheme aims to be less sensitive to the user scheduling, which is one of the key limiting factors for the practical implementation of precoding. Furthermore, the proposed technique can also cope with more users than satellite beams. In fact, the proposed precoder can be tuned to control the interference towards the co-channel beams, which is a desirable feature that is not met by the existing RZF solutions. The design is formulated as a non-convex optimization and we study various algorithms in order to obtain a practical solution. Supporting results based on numerical simulations show that the proposed precoding implementations are able to outperform the conventional ZF and RZF schemes.","PeriodicalId":137674,"journal":{"name":"Frontiers in Space Technologies","volume":"14 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-05-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131221482","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Comparison of Submillinewton Thrust Measurements Between a Laser Interferometer and a Load Cell on a Pendulum Balance","authors":"D. Tsifakis, C. Charles, R. Boswell","doi":"10.3389/frspt.2021.632358","DOIUrl":"https://doi.org/10.3389/frspt.2021.632358","url":null,"abstract":"Reliable measurements of thrust from systems to be flown on satellites are essential to ensure repeatable maneuvering capability of small nanosatellites. Thrusters can be used to vary spacecraft orientation, detumbling, and orbit change. Tests have been conducted in a low-pressure vacuum system using a cold gas prototype thruster and two independently calibrated methods: a four-point pendulum with a laser interferometer displacement sensor and a load cell, both of which have measurement capabilities from tens of micronewtons to tens of millinewtons. The agreement is very good, lending confidence in both methods. The advantages and disadvantages of both methods will be discussed. They include absolute accuracy, low thrust accuracy, temporal resolution, simplicity of operation, cost, and sensitivity to vibrations generated by laboratory equipment such as pumps, fans, bumps, and human movement.","PeriodicalId":137674,"journal":{"name":"Frontiers in Space Technologies","volume":"52 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-04-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121485828","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A Hybrid Beamforming Design for Massive MIMO LEO Satellite Communications","authors":"J. Palacios, N. González-Prelcic, C. Mosquera, Takayuki Shimizu, Chang-Heng Wang","doi":"10.3389/frspt.2021.696464","DOIUrl":"https://doi.org/10.3389/frspt.2021.696464","url":null,"abstract":"5G and future cellular networks intend to incorporate low earth orbit (LEO) satellite communication systems (SatCom) to solve the coverage and availability problems that cannot be addressed by satellite-based or ground-based infrastructure alone. This integration of terrestrial and non terrestrial networks poses many technical challenges which need to be identified and addressed. To this aim, we design and simulate the downlink of a LEO SatCom compatible with 5G NR, with a special focus on the design of the beamforming codebook at the satellite side. The performance of this approach is evaluated for the link between a LEO satellite and a mobile terminal in the Ku band, assuming a realistic channel model and commercial antenna array designs, both at the satellite and the terminal. Simulation results provide insights on open research challenges related to analog codebook design and hybrid beamforming strategies, requirements of the antenna terminals to provide a given SNR, or required beam reconfiguration capabilities among others.","PeriodicalId":137674,"journal":{"name":"Frontiers in Space Technologies","volume":"07 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-04-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127730140","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}