scholarly journals Recent Advances in Design and Implementation of Satellite Gateways for Massive Uncoordinated Access Networks

Sensors ◽  
2022 ◽  
Vol 22 (2) ◽  
pp. 565
Author(s):  
Agostino Isca ◽  
Nader Alagha ◽  
Riccardo Andreotti ◽  
Marco Andrenacci
Keyword(s):  
Spread Spectrum ◽  
Interference Cancellation ◽  
Minimum Mean Square Error ◽  
Large Population ◽  
Evaluation Study ◽  
Design Development ◽  
Satellite Systems ◽  
Low Duty Cycle ◽  
Multi Stage ◽  
And Performance

This paper provides an overview of recent results of a design, development and performance evaluation study of satellite gateways to receive and manage the traffic from a large population of uncoordinated user terminals. In particular, direct satellite access scenarios for machine-to-machine communications and the Internet of Things have been targeted. Tests were carried out in a representative laboratory environment emulating realistic system scenarios. Performance results, as presented in this paper indicate that the proposed gateway architecture, based on an efficient access protocol, is capable of managing a very high number of uncoordinated terminals transmitting short messages with a low duty cycle. The applicability of the proposed solution to both geostationary and non-geostationary satellite systems has also been examined. The key concept of the gateway is based on a novel receiver architecture that implements the linear minimum mean square error (MMSE) spread spectrum signal detection and successive interference cancellation techniques. The receiver uses features such as a multi-stage detector together with a robust preamble detection. The end-to-end solution includes also the use of a new waveform with a quasi-constant envelope at the terminal to modulate and transmit data packets to be received and detected by the gateway via a satellite link.

PERFORMANCE ANALYSIS OF MULTIPLE ACCESS CHAOTIC-SEQUENCE SPREAD-SPECTRUM COMMUNICATION SYSTEMS USING PARALLEL INTERFERENCE CANCELLATION RECEIVERS

2004 ◽  
Vol 14 (10) ◽  
pp. 3633-3646 ◽  
Author(s):  
WAI M. TAM ◽  
FRANCIS C. M. LAU ◽  
CHI K. TSE
Keyword(s):  
Spread Spectrum ◽  
Interference Cancellation ◽  
Communication Systems ◽  
Multiple Access ◽  
Minimum Mean Square Error ◽  
Chaotic Sequence ◽  
Spread Spectrum Communication ◽  
Parallel Interference Cancellation ◽  
Decorrelating Detector ◽  
Error Detector

In this Letter, we apply combined linear detector/parallel interference cancellation (PIC) detectors to jointly decode symbols in a multiple access chaotic-sequence spread-spectrum communication system. In particular, three different types of linear detectors, namely single-user detector, decorrelating detector and minimum mean-square-error detector, are used to estimate the transmitted symbols at the first stage of the PIC detector. The technique for deriving the approximate bit error rate (BER) is described and computer simulations are performed to verify the analytical BERs.

The Frequency of Occurrence of Handwriting Performance Features Used to Predict Whether Questioned Signatures are Simulated

2018 ◽  
Vol 28 ◽  
pp. 35-42
Author(s):  
David Black ◽  
Bryan Found ◽  
Doug Rogers
Keyword(s):  
Large Population ◽  
Quality Parameters ◽  
Frequency Of Occurrence ◽  
Relative Speed ◽  
Simulation Process ◽  
Spatial Features ◽  
And Performance ◽  
Document Examiners ◽  
Line Trace

Forensic Document Examiners (FDEs) examine the physical morphology and performance attributes of a line trace when comparing questioned to specimen handwriting samples for the purpose of determining authorship. Along with spatial features, the elements of execution of the handwriting are thought to provide information as to whether or not a questioned sample is the product of a disguise or simulation process. Line features such as tremor, pen-lifts, blunt beginning and terminating strokes, indicators of relative speed, splicing and touch ups, are subjectively assessed and used in comparisons by FDEs and can contribute to the formation of an opinion as to the validity of a questioned sample of handwriting or signatures. In spite of the routine use of features such as these, there is little information available regarding the relative frequency of occurrence of these features in populations of disguised and simulated samples when compared to a large population of a single individual’s signature. This study describes a survey of the occurrence of these features in 46 disguised signatures, 620 simulated signatures (produced by 31 different amateur forgers) and 177 genuine signatures. It was found that the presence of splices and touch-ups were particularly good predictors of the simulation process and that all line quality parameters were potentially useful contributors in the determination of the authenticity of questioned signatures. Purchase Article - $10

scholarly journals Low-Process–Voltage–Temperature-Sensitivity Multi-Stage Timing Monitor for System-on-Chip Applications

Electronics ◽  
2021 ◽  
Vol 10 (13) ◽  
pp. 1587
Author(s):  
Duo Sheng ◽  
Hsueh-Ru Lin ◽  
Li Tai
Keyword(s):  
High Performance ◽  
Power Reduction ◽  
System On Chip ◽  
Timing Information ◽  
Multi Stage ◽  
Dynamic Voltage ◽  
And Performance ◽  
On Chip ◽  
Maximum Measurement ◽  
Maximum Measurement Error

High performance and complex system-on-chip (SoC) design require a throughput and stable timing monitor to reduce the impacts of uncertain timing and implement the dynamic voltage and frequency scaling (DVFS) scheme for overall power reduction. This paper presents a multi-stage timing monitor, combining three timing-monitoring stages to achieve a high timing-monitoring resolution and a wide timing-monitoring range simultaneously. Additionally, because the proposed timing monitor has high immunity to the process–voltage–temperature (PVT) variation, it provides a more stable time-monitoring results. The time-monitoring resolution and range of the proposed timing monitor are 47 ps and 2.2 µs, respectively, and the maximum measurement error is 0.06%. Therefore, the proposed multi-stage timing monitor provides not only the timing information of the specified signals to maintain the functionality and performance of the SoC, but also makes the operation of the DVFS scheme more efficient and accurate in SoC design.

The Design, Development and Performance of Indair and Mardair Flares

1977 ◽  
Author(s):  
J. Wilkins ◽  
R.E. Witheridge ◽  
D.H. Desty ◽  
J.T.M. Mason ◽  
N. Newby
Keyword(s):  
Design Development ◽  
And Performance

Design and performance of deep well dewatering: a case study

1998 ◽  
Vol 35 (1) ◽  
pp. 81-95 ◽  
Author(s):  
D W Sargent ◽  
R D Beckie ◽  
G Smith
Keyword(s):  
Soil Mechanics ◽  
Data Gathering ◽  
Monitoring Program ◽  
Treatment Plant ◽  
Pumping Test ◽  
Observational Method ◽  
Design Development ◽  
Deep Well ◽  
And Performance

This paper reviews the process used to design the construction dewatering system at the Influent Pumping Station at Annacis Island Wastewater Treatment Plant. The design process followed the "observational method," as applied to soil mechanics by K. Terzaghi and set out by R.B. Peck in the Ninth Rankine Lecture. The design was based on a working hypothesis of behaviour anticipated under the most probable conditions identified in the data gathering and assessment program. The sensitivity of the design was evaluated by considering potentially unfavourable conditions evident in the available data. The design development included a review of monitoring feedback obtained during the pumping-well installation, a pumping test, and the dewatering system start-up. The monitoring program and review process are presented.Key words: dewatering, observational method, case study, pumping test.

scholarly journals Hydropower, Geothermal, and Ocean Energy

MRS Bulletin ◽  
2008 ◽  
Vol 33 (4) ◽  
pp. 389-395 ◽  
Author(s):  
Ralph E.H. Sims
Keyword(s):  
Renewable Energy ◽  
Large Scale ◽  
New Technologies ◽  
Materials Science ◽  
Development Stage ◽  
Design Development ◽  
Ocean Energy ◽  
Improve Design ◽  
And Performance ◽  
Improve Reliability

AbstractSome forms of renewable energy have long contributed to electricity generation, whereas others are just emerging. For example, large-scale hydropower is a mature technology generating about 16% of global electricity, and many smaller scale systems are also being installed worldwide. Future opportunities to improve the technology are limited but include upgrading of existing plants to gain greater performance efficiencies and reduced maintenance. Geothermal energy, widely used for power generation and direct heat applications, is also mature, but new technologies could improve plant designs, extend their lifetimes, and improve reliability. By contrast, ocean energy is an emerging renewable energy technology. Design, development, and testing of a myriad of devices remain mainly in the research and development stage, with many opportunities for materials science to improve design and performance, reduce costly maintenance procedures, and extend plant operating lifetimes under the harsh marine environment.

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