Satellite communications at KU, KA, and V bands: Propagation impairments and mitigation techniques
TL;DR: This article surveys the alternative fade mitigation techniques for satellite communication systems operating at Ku, Ka and V frequency bands and discusses the specific phenomena influencing the propagation of radiowaves on Earth-space links.
Abstract: This article surveys the alternative fade mitigation techniques for satellite communication systems operating at Ku, Ka and V frequency bands. The specific phenomena influencing the propagation of radiowaves on Earth-space links are also overviewed. Emphasis is placed on modeling, experimental work carried out in the past, and practical implementations related to each mitigation technique.
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TL;DR: An extensive survey of the measurement methods proposed for UAV channel modeling that use low altitude platforms and discusses various channel characterization efforts is provided.
Abstract: Unmanned aerial vehicles (UAVs) have attracted great interest in rapid deployment for both civil and military applications. UAV communication has its own distinctive channel characteristics compared to the widely used cellular or satellite systems. Accurate channel characterization is crucial for the performance optimization and design of efficient UAV communication. However, several challenges exist in UAV channel modeling. For example, the propagation characteristics of UAV channels are under explored for spatial and temporal variations in non–stationary channels. Additionally, airframe shadowing has not yet been investigated for small size rotary UAVs. This paper provides an extensive survey of the measurement methods proposed for UAV channel modeling that use low altitude platforms and discusses various channel characterization efforts. We also review from a contemporary perspective of UAV channel modeling approaches, and outline future research challenges in this domain.
532 citations
Cites background or methods from "Satellite communications at KU, KA,..."
...for land mobile systems have also been thoroughly investigated in [4] and [5]....
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...For example, channel behavior of land mobile satellite systems can be analyzed using the multi–state Markov chain model [4], [5]....
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TL;DR: An overview of the architecture of the LEO satellite constellation-based IoT including the following topics: LEOatellite constellation structure, efficient spectrum allocation, heterogeneous networks compatibility, and access and routing protocols is provided.
Abstract: Internet of Things (IoT) is one of the evolutionary directions of the Internet. This paper focuses on the low earth orbit (LEO) satellite constellation-based IoT services for their irreplaceable functions. In many cases, IoT devices are distributed in remote areas (e.g., desert, ocean, and forest) in some special applications, they are placed in some extreme topography, where are unable to have direct terrestrial network accesses and can only be covered by satellite. Comparing with the traditional geostationary earth orbit (GEO) systems, LEO satellite constellation has the advantages of low propagation delay, small propagation loss and global coverage. Furthermore, revision of existing IoT protocol are necessary to enhance the compatibility of the LEO satellite constellation-based IoT with terrestrial IoT systems. In this paper, we provide an overview of the architecture of the LEO satellite constellation-based IoT including the following topics: LEO satellite constellation structure, efficient spectrum allocation, heterogeneous networks compatibility, and access and routing protocols.
374 citations
TL;DR: This review is built on two pillars, namely fixed satellite and mobile satellite, and special attention is given to the characteristics of the satellite channel, which will ultimately determine the viability of MIMO over satellite.
Abstract: The present article carries out a review of MIMO-based techniques that have been recently proposed for satellite communications. Due to the plethora of MIMO interpretations in terrestrial systems and the particularities of satellite communications, this review is built on two pillars, namely fixed satellite and mobile satellite. Special attention is given to the characteristics of the satellite channel, which will ultimately determine the viability of MIMO over satellite. Finally, some future research directions are identified.
315 citations
Cites background from "Satellite communications at KU, KA,..."
...As also stressed in the FS case, these synthesizers are valuable tools to study the channel dynamics and also aid in the design of FMTs....
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...Long Term Channel Effects: The most important channel effects impairing SatCom at frequencies above 10 GHz are summarized as follows [60]: ◦ Attenuation due to precipitation: When propagating through snow, hail, ice droplets and, predominantly, rain, radiowaves suffer from hydrometeor scattering and absorption....
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...In turn, this type of stochastic modeling offers a powerful tool for the simulation of adaptive FMTs [60], [65]....
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...These adverse tropospheric phenomena, well documented among others in [58], [59], [60], are briefly summarized in the following, distinguishing between long term and dynamic channel effects....
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...Moreover, we can distinguish between different SatCom systems variants depending on [2], [3]: the choice of orbit (GSO vs. NGSO), user mobility (fixed vs. mobile), operating frequency band (UHF, L, S, C, X, Ku, Ka bands), group size of intended users (broadcast, multicast, unicast), multiplexing scheme (single carrier TDM vs. multicarrier OFDM), type of application (delay tolerant vs. delay intolerant), availibility of FMTs (CCM vs. ACM) and so on....
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TL;DR: A generic optimization framework for linear precoding design to handle any objective functions of data rate with general linear and nonlinear power constraints is provided and an iterative algorithm which optimizes the precoding vectors and power allocation alternatingly is proposed and most importantly, the proposed algorithm is proved to always converge.
Abstract: Multibeam satellite systems have been employed to provide interactive broadband services to geographical areas under-served by terrestrial infrastructure. In this context, this paper studies joint multiuser linear precoding design in the forward link of fixed multibeam satellite systems. We provide a generic optimization framework for linear precoding design to handle any objective functions of data rate with general linear and nonlinear power constraints. To achieve this, an iterative algorithm which optimizes the precoding vectors and power allocation alternatingly is proposed and most importantly, the proposed algorithm is proved to always converge. The proposed optimization algorithm is also applicable to nonlinear dirty paper coding. As a special case, a more efficient algorithm is devised to find the optimal solution to the problem of maximizing the proportional fairness among served users. In addition, the aforementioned problems and algorithms are extended to the case that each terminal has multiple co-polarization or dual-polarization antennas. Simulation results demonstrate substantial performance improvement of the proposed schemes over conventional multibeam satellite systems, zero-forcing and regularized zero-forcing precoding schemes in terms of meeting the traffic demand, e.g., using real beam patterns, over twice higher throughput can be achieved compared with the conventional scheme. The performance of the proposed linear precoding scheme is also shown to be very close to the dirty paper coding.
296 citations
Cites methods from "Satellite communications at KU, KA,..."
...By employing a time division multiplexed (TDM) scheme, a single user per beam is served for each time slot....
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TL;DR: A partial zero-forcing approach is proposed for obtaining a low-complexity sub-optimal solution and an iterative algorithm combining semi-definite programming relaxation and the gradient-based method is devised by studying the convexity of the problem.
Abstract: Security threats introduced due to the vulnerability of the transmission medium may hinder the proliferation of Ka band multibeam satellite systems for civil and military data applications. This paper sets the analytical framework and then studies physical layer security techniques for fixed legitimate receivers dispersed throughout multiple beams, each possibly surrounded by multiple (passive) eavesdroppers. The design objective is to minimize via transmit beamforming the costly total transmit power on board the satellite, while satisfying individual intended users' secrecy rate constraints. Assuming state-of-the-art satellite channel models, when perfect channel state information (CSI) about the eavesdroppers is available at the satellite, a partial zero-forcing approach is proposed for obtaining a low-complexity sub-optimal solution. For the optimal solution, an iterative algorithm combining semi-definite programming relaxation and the gradient-based method is devised by studying the convexity of the problem. Furthermore, the use of artificial noise as an additional degree-of-freedom for protection against eavesdroppers is explored. When only partial CSI about the eavesdroppers is available, we study the problem of minimizing the eavesdroppers' received signal to interference-plus-noise ratios. Simulation results demonstrate substantial performance improvements over existing approaches.
164 citations
Cites background from "Satellite communications at KU, KA,..."
...Considering the satellite channel above 10 GHz operating under line-of-sight, it is subjected to various atmospheric fading mechanisms originating in the troposphere, which severely degrade system performance and availability [23]....
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References
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TL;DR: In this paper, the authors characterized the neutral atmosphere for the frequency range from 1 to 300 GHz as a nonturbulent propagation medium and predicted attenuation and propagation delay effects from meteorological data sets: pressure, temperature, humidity, suspended particle concentration, and rain rate.
Abstract: The neutral atmosphere is characterized for the frequency range from 1 to 300 GHz as a nonturbulent propagation medium. Attenuation and propagation delay effects are predicted from meteorological data sets: pressure, temperature, humidity, suspended particle concentration, and rain rate. The physical data base of the propagation model consists of four terms: (a) resonance information for 30 water vapor and 48 oxygen absorption lines in the form of intensity coefficients and center frequency for each line; (b) a composite (oxygen, water vapor, and nitrogen) continuum spectrum; (c) a hydrosol attenuation term for haze, fog, ,and cloud conditions; and (d) a rain attenuation model. Oxygen lines extend into the mesosphere, where they behave in a complicated manner due to the Zeeman effect. The geomagnetic field strength H is required as an additional input parameter. Each 02 line splits proportionally with H into numerous, sub-lines, which are juxtaposed to form a Zeeman pattern spread over a megahertz scale. Patterns for three main polarization cases are calculated. Detailed examples for model atmospheres provide basic millimeter wave propagation information over the height range 0 to 100 km of the neutral atmosphere.
705 citations
"Satellite communications at KU, KA,..." refers methods in this paper
...Finally, a propagation model taking into account the complex refractive index of the neutral atmosphere predicting path loss and delay for frequencies up to 1THz has been developed [ 26 ]....
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TL;DR: In this article, a procedure for predicting the combined effect of rain attenuation and several other propagation impairments (at frequencies between 4 and 35 GHz) along Earth-satellite paths is presented.
Abstract: The rapid growth of satellite services using higher frequency bands such as the Ka-band has highlighted a need for estimating the combined effect of different propagation impairments. Many projected Ka-band services will use very small terminals and, for some, rain effects may only form a relatively small part of the total propagation link margin. It is therefore necessary to identify and predict the overall impact of every significant attenuating effect along any given path. A procedure for predicting the combined effect of rain attenuation and several other propagation impairments (at frequencies between 4 and 35 GHz) along Earth-satellite paths is presented. Where an accurate model exist for some phenomena, these have been incorporated into the prediction procedure. New models were developed, however, for rain attenuation, cloud attenuation, and low-angle fading to provide more overall accuracy, particularly at very low elevation angles (<10/spl deg/). In the absence of a detailed knowledge of the occurrence probabilities of different impairments, an empirical approach is taken in estimating their combined effects. An evaluation of the procedure is made using slant-path attenuation data that have been collected with simultaneous beacon and radiometer measurements which allow a near complete account of different impairments. Results indicate that the rain attenuation element of the model provides the best average accuracy globally between 10 and 30 GHz and that the combined procedure gives prediction accuracies comparable to uncertainties associated with the year-to-year variability of path attenuation.
295 citations
"Satellite communications at KU, KA,..." refers background in this paper
...For example, the melting layer is associated with low intensity rain, while gaseous absorption increases during rain events due to the increased water vapor content in the atmosphere [ 24 ]....
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TL;DR: A dynamic mathematical model of rain attenuation has been developed and is presented and the application of the model to the statistical analysis of the performance of communications systems is illustrated in this paper.
Abstract: A dynamic mathematical model of rain attenuation has been developed and is presented in this paper. This model permits the expression of analytic relationships between parameters commonly used to describe the properties of interest for communication. The dynamic model is based on the lognormal distribution of rain attenuation and utilizes a memoryless nonlinear device to transform attenuation and rain intensity into a one-dimensional Gaussian stationary Markov process. Hence, only one parameter is required to introduce the dynamic properties of rain attenuation into the model. Experimental results and the known properties of rain have been used to derive and to verify the model; comparative results are presented and demonstrate good correspondence. The application of the model to the statistical analysis of the performance of communications systems is illustrated in the paper. The use of a dynamic rain attenuation model is necessary in order to analyze radio communication systems with transmit power control to offset the effects of rain attenuation, and where the finite response time of the control system affects the performance. An advantage of the model is the simplicity with which it allows simulation of communication link performance under the influence of rain attenuation. Such simulations are of great interest for complex models of adaptive networks where several deteriorating effects, including finite response times, are present.
187 citations
TL;DR: In this article, a new method for cloud attenuation calculation on an earth-satellite link is presented, which uses temperature and humidity profiles as input parameters, and has been applied to radiosonde measurements and to the gridded data of the numerical analyses of ECMWF.
Abstract: A new method for cloud attenuation calculation on an earth–satellite link is presented. The method uses temperature and humidity profiles as input parameters. The method has been applied to radiosonde measurements and to the gridded data of the numerical analyses of ECMWF.
181 citations
"Satellite communications at KU, KA,..." refers background or methods in this paper
...FIGURE 4. Specific attenuation vs. frequency [ 12 ]....
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...Prediction models for this particular attenuation factor have been developed within the framework of ITU-R [11] and elsewhere [ 12 ]....
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