pinecone/core-2020-05-10-deduplication huggingface dataset:
Sequential geophysical and flow inversion to characterize fracture
  networks in subsurface systems

Subsurface applications including geothermal, geological carbon
sequestration, oil and gas, etc., typically involve maximizing either the
extraction of energy or the storage of fluids. Characterizing the subsurface is
extremely complex due to heterogeneity and anisotropy. Due to this complexity,
there are uncertainties in the subsurface parameters, which need to be
estimated from multiple diverse as well as fragmented data streams. In this
paper, we present a non-intrusive sequential inversion framework, for
integrating data from geophysical and flow sources to constraint subsurface
Discrete Fracture Networks (DFN). In this approach, we first estimate bounds on
the statistics for the DFN fracture orientations using microseismic data. These
bounds are estimated through a combination of a focal mechanism (physics-based
approach) and clustering analysis (statistical approach) of seismic data. Then,
the fracture lengths are constrained based on the flow data. The efficacy of
this multi-physics based sequential inversion is demonstrated through a
representative synthetic example.Comment: 32 pages, 14 figure
On the quality of VoIP with DCCP for satellite communications

We present experimental results for the performance of selected voice codecs using DCCP with CCID4 congestion control over a satellite link. We evaluate the performance of both constant and variable data rate speech codecs for a number of simultaneous calls using the ITU E-model. We analyse the sources of packet losses and additionally analyse the effect of jitter which is one of the crucial parameters contributing to VoIP quality and has, to the best of our knowledge, not been considered previously in the published DCCP performance results. We propose modifications to the CCID4 algorithm and demonstrate how these improve the VoIP performance, without the need for additional link information other than what is already monitored by CCID4. We also demonstrate the fairness of the proposed modifications to other flows. Although the recently adopted changes to TFRC specification alleviate some of the performance issues for VoIP on satellite links, we argue that the characteristics of commercial satellite links necessitate consideration of further improvements. We identify the additional benefit of DCCP when used in VoIP admission control mechanisms and draw conclusions about the advantages and disadvantages of the proposed DCCP/CCID4 congestion control mechanism for use with VoIP applications
Physical layer DVB-SH performance prediction based on mutual information

Digital Video Broadcasting-Satellite Handled (DVB-SH) is a hybrid satellite terrestrial broadcasting standard dedicated to provide video or audio services for handheld terminals. On the satellite part, this standard can make use of interleaving mechanisms to mitigate the effects of the Land Mobile Satellite channel. As a result, these mechanisms enable the in-time distribution of a codeword over a duration ranging from 100 ms to about 30 s, depending on their parameters. This mechanism significantly improves the error recovery performance of the code; however in the literature, a theoretical evaluation at system level of this improvement is missing. Moreover, carrying out Monte-Carlo simulations implementing real decoding processes on significant traveled distances is time prohibitive.\ud
We propose hereafter a prediction method compatible with fast simulations to quantitatively evaluate the system performance in terms of Rate, Erroneous Second Ratio, and zapping time. This method is based on the computation of the mutual information between emitted and received symbols for QPSK modulation and turbo coding.\ud
We demonstrate that our method reaches a prediction precision of the order of 0.1 dB, which is significantly better than two classical prediction methods. Moreover, our solution reduces the simulation time by a factor of 500 compared with Monte-Carlo. Beyond DVB-SH application, the presented approach can be applied in a large panel of satellite mobile systems and is completely new for the satellite community
Cyclic redundancy check-based detection algorithms for automatic identification system signals received by satellite

This paper addresses the problem of demodulating signals transmitted in the automatic identification system. The main characteristics of such signals consist of two points: (i) they are modulated using a trellis-coded modulation,\ud
more precisely a Gaussian minimum shift keying modulation; and (ii) they are submitted to a bit stuffing procedure, which makes more difficult the detection of the transmitted information bits. This paper presents several demodulation algorithms developed in different contexts: mono-user and multi-user transmissions, and known/unknown phase shift. The proposed receiver uses the cyclic redundancy check (CRC) present in the automatic\ud
identification system signals for error correction and not for error detection only. By using this CRC, a particular Viterbi algorithm, on the basis of a so-called extended trellis, is developed. This trellis is defined by extended states\ud
composed of a trellis code state and a CRC state. Moreover, specific conditional transitions are defined to take into account the possible presence of stuffing bits. The algorithms proposed in the multi-user scenario present a small increase of computation complexity with respect to the mono-user algorithms. Some performance results are presented for several scenarios in the context of the automatic identification system and compared with those of existing techniques developed in similar scenarios
Optimized Handover and Resource Management: An 802.21 Based Scheme to Optimize Handover and Resource Management in Hybrid Satellite-Terrestrial Networks

International audienceSatellite communications can provide fourth generation (4G) networks with large-scale coverage. However, their integration to 4G is challenging because satellite networks have not been designed with handover in mind. The setup of satellite links takes time, and so, handovers must be anticipated long before. This paper proposes a generic scheme based on the Institute of Electrical and Electronics Engineers 802.21 standard to optimize handover and resource management in hybrid satellite-terrestrial networks. Our solution, namely optimized handover and resource management (OHRM), uses the terrestrial interface to prepare handover, which greatly speeds up the establishment of the satellite link. We propose two mechanisms to minimize the waste of bandwidth due to wrong handover predictions. First, we leverage the support of 802.21 in the terrestrial access network to shorten the path of the signaling messages towards the satellite resource manager. Second, we cancel the restoration of the satellite resources when the terrestrial link rolls back. We use OHRM to interconnect a digital video broadcasting and a wireless 4G terrestrial network. However for the simulation tool, we use a WiMAX as the terrestrial technology to illustrate the schemes. The simulation results show that OHRM minimizes the handover delay and the signaling overhead in the terrestrial and satellite networks
On the impact of link layer retransmission schemes on TCP over 4G satellite links

We study the impact of reliability mechanisms introduced at the link layer on the performance of transport protocols in the context of 4G satellite links. Specifically, we design a software module that performs realistic analysis of the network performance, by utilizing real physical layer traces of a 4G satellite service. Based on these traces, our software module produces equivalent link layer traces, as a function of the chosen link layer reliability mechanism. We further utilize the link layer traces within the ns-2 network simulator to evaluate the impact of link layer schemes on the performance of selected Transmission Control Protocol (TCP) variants. We consider erasure coding, selective-repeat automatic request (ARQ) and hybrid-ARQ link layer mechanisms, and TCP Cubic, Compound, Hybla, New Reno and Westwood. We show that, for all target TCP variants, when the throughput of the transport protocol is close to the channel capacity, using the ARQ mechanism is most beneficial for TCP performance improvement. In conditions where the physical channel error rate is high, hybrid-ARQ results in the best performance for all TCP variants considered, with up to 22% improvements compared to other schemes
Smart gateways for terabit/s satellite

To reach the terabit per second of throughput, telecommunication satellites cannot make use of frequency below Ka band only. Therefore, the use of broad portion of the spectrum available at Q/V (40/50 GHz) band is foreseen for the feeder link. This study presents the evaluation of performances of different macro-diversity schemes that may allow mitigating the deep fades experienced at Q/V bands by introducing cooperation and a limited redundancy between the different gateways of the system. Two different solutions are firstly described. The performances resulting from the use of those assumptions are derived in a second stage
S-MIM field trials results

An intelligent transport system open platform integrating the S-band Mobile Interactive Multimedia messaging\ud
return channel protocol over satellite (based on Enhanced Spread Spectrum Aloha) has been developed and tested\ud
under real environment conditions within the framework of SafeTRIP, an FP7 EU-funded project. This paper\ud
presents the first field trials results using the S-band Mobile Interactive Multimedia technology. The introduced\ud
forward and return link outcomes have been derived from mobile field trials carried out in the surroundings of\ud
the German Aerospace Center (DLR) in Germany. Finally the validation of the system performances has been\ud
realized thanks to the use of a traffic emulator that can simulate a large population of Enhanced Spread Spectrum\ud
Aloha terminals
The combined automatic repeat request and rate control mechanism in S-band mobile interactive multimedia asynchronous return link - design background, parameter dimensioning and first experimental results

In the S-band mobile interactive multimedia specification, an asynchronous access using Enhanced Spread Spectrum Aloha random access has been defined for occasional messaging applications. This access scheme is complemented by a combined automatic repeat request and terminal rate control mechanism that is described in this paper. Furthermore, a queuing theory-based model is  developed to describe the behaviour of the automatic repeat request mechanism, and performance results from the first proof-of-concept implementation are presented
A pre-emption framework for UMTS satellite system supporting multimedia traffic

YesThe pre-emption procedure is an important part of the Radio Resource Management (RRM) when dealing with the emergency traffic. It allows resources to be allocated to higher priority connections by pre-empting lower priority connections. The provision of the pre-emption mechanism becomes much more important in the case of satellite systems
such as the Inmarsat Broadband Global Area Network (BGAN) system which aids in providing the communication during a catastrophe. This paper focuses on the preemption framework for a UMTS based satellite systems. Three algorithms have been proposed, Greedy, SubSetSum and Fuzzy pre-emption algorithm. Extensive simulations are carried out for the three algorithms and their performances are compared against each other. Simulation results show that the Fuzzy pre-emption algorithm performs better than the other two algorithms.European Space Agency/Inmarsa
Communication satellite power amplifiers: current and future SSPA and TWTA technologies

This study captures the state of current satellite transponder technology, specifically, solid-state power amplifiers (SSPAs) and traveling wave tube amplifiers (TWTAs), and describes expected future advances, including GaN SSPAs. The findings of five previous SSPA and TWTA studies, including the 1991 European Space and Technology Center study, the 1993 National Aeronautics and Space Administration study, and three Boeing studies conducted in 2005, 2008, and 2013, are tabulated and summarized. The results of these studies are then compared with new analyses of two validated sources of amplifier data: a commercially licensed database, Seradata's Spacetrak, and a publicly available database, Gunter's Space Page. The new analyses consider a total of 18,902 amplifiers (6428 TWTAs, 2158 SSPAs, and 10,316 unspecified amplifiers) onboard 565 communications satellites launched from 1982 to 2016. This new study contains the largest number of satellites and amplifiers to date and compares output power, redundancy, and bandwidth capabilities. We find an increase in output power from the 1993 study of >200% for Ku-band TWTAs and C-band SSPAs, and >1000% increase for C-band TWTAs. The ratio of operational to redundant amplifiers is 10 times higher for TWTAs than SSPAs, and the majority of amplifiers over the past 30 years operate with bandwidth less than 100 MHz. A second analysis is conducted using failure records and telemetry of 16 geostationary satellites equipped with 659 amplifiers: 535 SSPAs and 124 TWTAs. We find that <2% of TWTAs and 5% of SSPAs experience anomalies. Overall, this research was performed to update and clarify how the power and bandwidth needs and redundancy trends of the SatCom community have evolved over the past 30 years
Predictive relay-selection cooperative diversity in land mobile satellite systems

Cooperative diversity protocols promise a new dimension of diversity that
provides better communication by engaging nearby relays in forming a ‘virtual’ array
of antennas for combined signal transmission. The current incremental cooperative
diversity algorithms incrementally select best relay(s) to cooperate based on the channel
quality reported by the relays. However, the algorithms do not take into consideration
the fact that the chosen best relay(s) at estimation may not always be best at the time of
communication. This is due to the time delay between the relay selection and its
transmission of signal (problem of outdated Channel Quality Information). To solve this
problem, the concept of channel prediction is introduced and employed whereby each
relay determines a predicted value of its Channel Quality Information (CQI) based on
its past measurements. The paper therefore develops a novel predictive relay-selection
(PRS) cooperative diversity model which seeks to improve Land Mobile Satellite (LMS)
communication through prediction protocols. In the model, the chosen best relay is the
one with the best predicted CQI value instead of the traditional outdated one.
Performance analysis of outage probability and average bit error probability for the
newly developed PRS cooperation shows that the PRS cooperation is better than direct
and outdated CQI relay communication.http://onlinelibrary.wiley.com/doi/10.1002/sat.11182017-03-31hb2016Electrical, Electronic and Computer Engineerin
Co-channel interference cancelation at the user terminal in multibeam satellite systems

We study the applicability of soft interference cancelation in the forward link of multibeam satellite systems with\ud
focus on mobile terminals. We adopt a standard currently used in commercial satellite systems as a reference. The\ud
multibeam satellite antenna radiation diagram has been generated using a physical optics re¿ector model while a\ud
widely adopted channel model has been used for the land mobile satellite channel. The interference pattern has\ud
been derived using a system simulator developed by the European Space Agency. Starting from the analysis of\ud
the interference pattern, we study the application of a low-complexity soft interference cancelation scheme for\ud
commercial applications. Our results show that, under realistic conditions, a two-colors frequency reuse scheme\ud
can be employed while guaranteeing service availability across the coverage and keeping the complexity at the\ud
user terminals relatively low.Peer ReviewedPostprint (author's final draft
DTN routing for quasi-deterministic networks with application to LEO constellations

We propose a novel DTN routing algorithm, called DQN, specifically designed for quasi-deterministic networks with an application to satellite constellations. We demonstrate that our proposal efficiently forwards the information over a satellite network derived from the Orbcomm topology while keeping a low replication overhead. We compare our algorithm against other well-known DTN routing schemes and show that we obtain the lowest replication ratio with a delivery ratio of the same order of magnitude than a reference theoretical optimal routing. We also analyze the impact of terrestrial gateways density and analyze DQN performances in heterogeneous cases
Software-defined satellite cloud RAN

This is the peer reviewed version of the following article: Ahmed, T., Dubois, E., Dupé, J.-B., Ferrús, R., Gélard, P., and Kuhn, N. (2018) Software-defined satellite cloud RAN. Int. J. Satell. Commun. Network., 36: 108–133, which has been published in final form at 10.1002/sat.1206. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving.This paper provides an assessment study on the virtualization of a Digital Video Broadcasting - Satellite - Second Generation (DVB-S2)/ Digital Video Broadcasting - Return Channel Satellite - Second Generation (DVB-RCS2) satellite ground infrastructure and proposes a framework, named Satellite Cloud Radio Access Network (SatCloudRAN), that aims to ease the integration of satellite components in forthcoming 5G systems. Special attention is given to the design of SatCloudRAN by considering the split and placement of virtualized and nonvirtualized functions while taking into account the characteristics of the transport links connecting both type of functions. We assess how virtualization and softwarization technologies, namely, network function virtualization and software-defined networking, can deliver part of the satellite gateway functionalities as virtual network functions and achieve a flexible and programmable control and management of satellite infrastructure. Under the network function virtualization paradigm, building virtual network function blocks that compose a satellite gateway have been identified, and their interaction exhibited. This paper also gives insights on how the SatCloudRAN approach can allow operators to provide software-defined networking-based (1) bandwidth on demand, (2) dynamic Quality of Service, and (3) satellite gateway diversity.Peer ReviewedPreprin
Combining PSA fading estimation techniques for TCM and diversity reception in Rician fading channels

In this paper, a novel pilot-symbol-aided (PSA) technique is proposed for fading estimation in the land mobile satellite fading channels. The proposed technique combines the fading estimates obtained from a bandwidth-efficient technique and a conventional technique according to the signal-to-noise ratios (SNRs) of the fading estimates. To enhance the transmission quality, trellis-coded modulation (TCM) and diversity reception are employed in the system, and the combined estimates are subsequently used to correct the channel fading effects, to weight the signals from different diversity branches, and to provide channel state information of the Viterbi decoder. Monte Carlo computer simulation has been used to study the bit-error-rate (BER) performance of the proposed technique on trellis-coded 16-ary quadrature amplitude modulation in the frequency non-selective Rician fading channels. Results have shown that the proposed PSA technique requires a very low bandwidth redundancy to provide satisfactory BER performance at low SNRs, and thus is suitable for use with TCM and diversity reception to achieve both bandwidth and power-efficient transmission.postprin
Networking issues in IP multicast over satellite

This paper describes the issues that arise when using satellites for IP multicast, with the emphasis on multicast protocols and how their implementation depends on the satellite communications platform. Various link layer standards such as DVB-S, DVB-RCS and ATM can be used in satellites with on-board processing, and applied to meet user and network requirements for IP multicast. The paper provides an overview of the networking issues and their interactions. Specifically, we show how multicast networking protocols have to be modified to take into account the satellite link characteristics: these protocols include IGMP, multicast routing protocols and reliable multicast protocols. We also discuss how security systems support IP multicast
Dynamic resource allocation based on a TCP-MAC cross-layer approach for DVB-RCS satellite networks

Satellite communication networks can provide multimedia broadband services to fixed and mobile users in several scenarios where terrestrial networks are not present or where they need to be complemented. Moreover, satellite links can be useful to bypass crowded terrestrial networks, thus helping in reducing congestion. In such a scenario, characterized by a high propagation delay and a radio channel affected by losses, standard bandwidth allocation schemes prove to be inefficient when Transmission Control Protocol (TCP) is running. Hence, we propose a novel resource allocation scheme based on the cross-layer interaction between TCP and Medium Access Control (MAC) layers. The interest is here in achieving an efficient transfer of files by means of the FTP application protocol. Our scheme permits to avoid network congestion, to reduce the average file transfer time and to achieve a fair sharing of resources among competing flows. The allocation technique has been applied to an Interactive Satellite Network (ISN) based on the DVB-RCS standard with a group of fixed satellite terminals, which communicate with a Netivork Control Center (NCC) through a geostationary bent-pipe satellite, according to a classical star topology. Results are obtained through a network simulator. Copyright (c) 2006 John Wiley & Sons, Ltd