scholarly journals Efficient Non-Uniform Pilot Design for TDCS

Sensors ◽  
2021 ◽  
Vol 21 (20) ◽  
pp. 6880
Author(s):  
Cheng Chang ◽  
Lina Feng ◽  
Hui Zhou ◽  
Zilong Zhao ◽  
Xin Gu
Keyword(s):  
Fading Channels ◽  
Communication System ◽  
Design Method ◽  
Probability Of Detection ◽  
Block Type ◽  
Data Traffic ◽  
Bit Error Ratio ◽  
Pilot Design ◽  
Low Efficiency ◽  
The Time Domain

The Internet of Things (IoT) leads the era of interconnection, where numerous sensors and devices are being introduced and interconnected. To support such an amount of data traffic, wireless communication technologies have to overcome available spectrum shortage and complex fading channels. The transform domain communication system (TDCS) is a cognitive anti-interference communication system with a low probability of detection and dynamic spectrum sensing and accessing. However, the non-continuous and asymmetric spectrum brings new challenges to the traditional TDCS block-type pilot, which uses a series of discrete symbols in the time domain as pilots. Low efficiency and poor adaptability in fast-varying channels are the main drawbacks for the block-type pilot in TDCS. In this study, a frequency domain non-uniform pilot design method was proposed with intersecting, skewing, and edging of three typical non-uniform pilots. Some numerical examples are also presented with multipath model COST207RAx4 to verify the proposed methods in the bit error ratio and the mean square error. Compared with traditional block-type pilot, the proposed method can adapt to the fast-varying channels, as well as the non-continuous and asymmetric spectrum conditions with much higher efficiency.

Single-Carrier Frequency Domain Equalization for Broadband Cooperative Communications

2010 ◽  
pp. 399-427 ◽  
Author(s):  
Tae-Won Yune ◽  
Dae-Young Seol ◽  
Dongsik Kim ◽  
Gi-Hong Im
Keyword(s):  
Fading Channels ◽  
Cooperative Communications ◽  
Cooperative Diversity ◽  
Spatial Diversity ◽  
Block Type ◽  
Channel Tracking ◽  
Single Carrier ◽  
Space Frequency ◽  
Pilot Design ◽  
Network Form

Cooperative diversity is an effective technique to combat the fading phenomena in wireless communications without additional complexity of multiple antennas. Multiple terminals in the network form a virtual antenna array in a distributed fashion. Even though each of them is equipped with only one antenna, spatial diversity gain can be achieved through cooperation. In this chapter, we discuss relay-assisted single carrier transmissions extending conventional transmit diversity schemes. We focus on distributed space-frequency block coded single carrier transmission, in order to operate over fast fading channels. A pilot design technique is also discussed for channel estimation of this single carrier cooperative system, which shows better channel tracking performance than conventional block-type channel estimations. In addition, spectral efficient cooperative diversity protocols are presented, where the users access a relay simultaneously or transmit superposed data blocks. Interference from the other user is effectively removed by using an iterative detection technique.

A Novel Approach for Designing Boltless Connectors - Example on a New Drilling Riser Connector

2021 ◽  
Author(s):  
Eleonore Roguet ◽  
Emmanuel Persent ◽  
Daniel Averbuch
Keyword(s):  
Finite Element ◽  
Design Process ◽  
Load Transfer ◽  
Design Method ◽  
Experimental Tests ◽  
New Product ◽  
Block Type ◽  
Finite Element Analyses ◽  
Novel Approach ◽  
Structural Tests

Abstract A new method which uses elastic and elasto-plastic Finite Element analyses is developed to design a double breech-block type connector. All relevant criteria proposed by API16F are fulfilled. In addition, plastic and bearing criteria have been added to support the use of lugs for load transfer in the connector. The proposed methodology has been applied and validated through experimental tests at different scales and in particular on laboratory specimens and small-scaled connectors. Based on these last structural tests, a safety factor of almost 8 was obtained for the design method on small-scaled connectors. Prototype tests at scale 1:1 allowed the methodology to be fully validated and a new product to be qualified. Certification bodies validated the whole design process, the employed methodology and the new connector.

Wireless- Powered UAV assisted Communication System in Nakagami-m Fading Channels

2020 ◽  
Author(s):  
Tharindu D. Ponnimbaduge Perera ◽  
Dushantha Nalin K. Jayakody ◽  
Sahil Garg ◽  
Neeraj Kumar ◽  
Ling Cheng
Keyword(s):  
Fading Channels ◽  
Communication System

Design of High-Efficient Bits for Igneous Rock in Xushen Gasfield

2013 ◽  
Vol 385-386 ◽  
pp. 308-311
Author(s):  
Li Gang Zhang ◽  
Tie Yan ◽  
Shi Bin Li
Keyword(s):  
Tungsten Carbide ◽  
Design Method ◽  
Polycrystalline Diamond ◽  
High Hardness ◽  
Rake Angle ◽  
Gas Field ◽  
Working Face ◽  
High Efficient ◽  
Low Efficiency ◽  
Bit Life

The igneous rocks in deep formations of the Xushen gasfield have the following characters: high abrasive property, high hardness, and high drillability, which lead to many drill bit accidents, few footage per bit , low efficiency of drilling, long drilling cycle, these severely restrict the exploration and development process of gas field. According to the features of deep formation, a hybird cutters bit is designed. It has three cones, with the overhang cone , duplicate taper and offset cone characters. The tungsten carbide cutters and the polycrystalline diamond compacts cutters are alternative collocation in the same tooth row in the bit. The exposed height of the tungsten carbide cutters is higher than polycrystalline diamond compacts cutters. The back rake angle of polycrystalline diamond compacts cutters is 10 ~ 40 °, the side rake angle is 10 ~ 30 °. The normal direction of working face stay the same with the composite slip direction, and the side rake pointed at adjacent gullet. Through the design method, it is integrated that the advantages of roller bit and PDC bit, the way of impact breakage and rotational shear breakage and the prominent performance of tungsten carbide cutters and polycrystalline diamond compacts cutters. It can improveROP and bit life.

Comparison of Meteorological Radar Signal Detectability with Noncoherent and Spectral-Based Processing

2016 ◽  
Vol 33 (4) ◽  
pp. 723-739 ◽  
Author(s):  
James B. Mead
Keyword(s):  
Signal Processing ◽  
False Alarm ◽  
False Alarm Rate ◽  
Time Domain ◽  
Spectral Width ◽  
Probability Of Detection ◽  
Spectral Domain ◽  
Processing Gain ◽  
Meteorological Radar ◽  
The Time Domain

AbstractDetection of meteorological radar signals is often carried out using power averaging with noise subtraction either in the time domain or the spectral domain. This paper considers the relative signal processing gain of these two methods, showing a clear advantage for spectral-domain processing when normalized spectral width is less than ~0.1. A simple expression for the optimal discrete Fourier transform (DFT) length to maximize signal processing gain is presented that depends only on the normalized spectral width and the time-domain weighting function. The relative signal processing gain between noncoherent power averaging and spectral processing is found to depend on a variety of parameters, including the radar wavelength, spectral width, available observation time, and the false alarm rate. Expressions presented for the probability of detection for noncoherent and spectral-based processing also depend on these same parameters. Results of this analysis show that DFT-based processing can provide a substantial advantage in signal processing gain and probability of detection, especially when the normalized spectral width is small and when a large number of samples are available. Noncoherent power estimation can provide superior probability of detection when the normalized spectral width is greater than ~0.1, especially when the desired false alarm rate exceeds 10%.

scholarly journals Research on Formation of Microsatellite Communication with Genetic Algorithm

2013 ◽  
Vol 2013 ◽  
pp. 1-7 ◽  
Author(s):  
Guoqiang Wu ◽  
Yuguang Bai ◽  
Zhaowei Sun
Keyword(s):  
Spread Spectrum ◽  
Communication System ◽  
Formation Flying ◽  
Design Method ◽  
Ldpc Code ◽  
Spread Spectrum Communication ◽  
Design System ◽  
Generic Algorithm ◽  
Optimizing Design ◽  
Direct Spread

For the formation of three microsatellites which fly in the same orbit and perform three-dimensional solid mapping for terra, this paper proposes an optimizing design method of space circular formation order based on improved generic algorithm and provides an intersatellite direct spread spectrum communication system. The calculating equation of LEO formation flying satellite intersatellite links is guided by the special requirements of formation-flying microsatellite intersatellite links, and the transmitter power is also confirmed throughout the simulation. The method of space circular formation order optimizing design based on improved generic algorithm is given, and it can keep formation order steady for a long time under various absorb impetus. The intersatellite direct spread spectrum communication system is also provided. It can be found that, when the distance is 1 km and the data rate is 1 Mbps, the input wave matches preferably with the output wave. And LDPC code can improve the communication performance. The correct capability of (512, 256) LDPC code is better than (2, 1, 7) convolution code, distinctively. The design system can satisfy the communication requirements of microsatellites. So, the presented method provides a significant theory foundation for formation-flying and intersatellite communication.

Blind Recognition of Reed-Solomon Codes Based on Histogram Statistic of Galois Field Spectra

2013 ◽  
Vol 791-793 ◽  
pp. 2088-2091
Author(s):  
Hui Xie ◽  
Feng Hua Wang ◽  
Zhi Tao Huang
Keyword(s):  
Reverse Engineering ◽  
Error Rate ◽  
Communication System ◽  
Spectral Characteristics ◽  
Galois Field ◽  
Probability Of Detection ◽  
Noisy Environment ◽  
Engineering Communication ◽  
Rs Code ◽  
Blind Recognition

We focus on the recognition of RS code in a reverse-engineering communication system, and an algorithm based on spectral statistic is proposed, which makes use of the spectral characteristics of RS code. When there are some codes with errors in the observations, the spectral histogram statistic is computed, which can improve the probability of detection in the noisy environment. Experimental results are given to illustrate the performances of the method which can get a 90% probability of detection of (255, 223) RS code in the presence of 0.5% code error rate.

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