Channels Environment Research Articles

Interspectral Error Tracking and Compensation of DSDT in Satellite Internet of Things

With the rapid growth of satellite Internet of Things (SIoT) services, existing frequency band resources are insufficient to meet future business demands. To effectively address this issue, it is necessary to enhance the utilization of existing frequency resources. However, idle frequency resources are typically scattered across multiple bands and vary in bandwidth size. Direct Spectrum Division Transmission (DSDT), dividing a complete signal into sub-spectrum signals for transmission in idle frequency bands, can take the use of fragmented spectrum resources for satellite communication. Nevertheless, the performance of DSDT depends heavily on accurate synchronization toward multiple sub-spectrums. In this paper, an algorithm for error synchronization tracking and compensation is proposed by utilizing the focusing nature of constellation. All sub-spectrums are weighed by the minimum Euclidean distance of the constellation to compensate for amplitude–frequency–phase errors simultaneously. Simulations and experimental verification demonstrate synchronization performance and feasibility of proposed method in a multi-radio frequency channels environment.

Enhancing Corn Pest and Disease Recognition through Deep Learning: A Comprehensive Analysis

Pests and diseases significantly impact the quality and yield of maize. As a result, it is crucial to conduct disease diagnosis and identification for timely intervention and treatment of maize pests and diseases, ultimately enhancing the quality and economic efficiency of maize production. In this study, we present an enhanced maize pest identification model based on ResNet50. The objective was to achieve efficient and accurate identification of maize pests and diseases. By utilizing convolution and pooling operations for extracting shallow-edge features and compressing data, we introduced additional effective channels (environment–cognition–action) into the residual network module. This step addressed the issue of network degradation, establishes connections between channels, and facilitated the extraction of crucial deep features. Finally, experimental validation was performed to achieve 96.02% recognition accuracy using the ResNet50 model. This study successfully achieved the recognition of various maize pests and diseases, including maize leaf blight, Helminthosporium maydis, gray leaf spot, rust disease, stem borer, and corn armyworm. These results offer valuable insights for the intelligent control and management of maize pests and diseases.

HaLow Wi-Fi performance in multiusers and channels environment with MATLAB Simulink

HaLow Wi-Fi performance in multiusers and channels environment with MATLAB Simulink

Design and implementation of enhanced permutation index differential chaos shift keying system

In standard PI-DCSK, information is transmitted by sending reference chaotic signal followed by information bearing signal, which is simply a permutated version of the reference signal. Permutation is performed based on a specific data map. In this paper, a developed version of (PI-DCSK) is presented and tested in AWGN and multipath Rayleigh fading channels environment. Information bearing signal is generated by mapping first set of information bits to the reference bit while the second set is mapped to the permutated-time reversed version of same reference signal. Both versions is added together on the same time slot. At the receiver, each incoming signal undergoes two operations; permutation and time reversal followed by permutation to detect the two different sets of information. This arrangement offers high data rate and reduce the energy requirement utilizing the low cross correlation between the chaotic signal and its time reversed version. The bit error performance is studied using baseband system model and analytically tested using Gaussian Approximation (GA) method. System performance is evaluated analytically to predict the Bit Error Rate (BER) using computer simulations. Results show that system performance is outperform the recent developed one by an average of at 2.25 dB while outperform the other standard chaos based scheme by an average of at same Eb∕N0. Moreover, the analytical form which are developed to predict the BER is validated by simulation.

Spectrum Sensing With Non-Gaussian Noise Over Multi-Path Fading Channels Towards Smart Cities With IoT

As the limited communication spectrum can not meet the demand of the exponential growth of intelligent connected devices in the internet of things(IoT) and typical smart city applications, in this paper, we propose a tractable spectrum sensing method based on Rao detection over non-Gaussian noise, such as generalized Gaussian noise(GGN), Gaussian mixture noise(GMN) and symmetric alpha-stable distribution ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{S}\alpha \text{S}$ </tex-math></inline-formula> ) noise, multi-path fading channels environment to alleviate the issue of spectrum scarcity. In this method, there are unknown parameters in the multi-path fading channels. When the probability density function (P.D.F.) of non-Gaussian noise has a closed-form expression, the spectrum sensing method based on Rao detection is used. Otherwise the P.D.F. for <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{S}\alpha \text{S}$ </tex-math></inline-formula> noise is estimated firstly by using non-parametric kernel estimation method, which addresses the issue that <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{S}\alpha \text{S}$ </tex-math></inline-formula> noise has no closed-form P.D.F. expression, and then the performance of spectrum sensing is derived based on the theory of Rao detection in multi-path fading channels over typical smart city applications. Simulation results show that the accuracy of estimated P.D.F. for <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{S}\alpha \text{S}$ </tex-math></inline-formula> noise and the performance of spectrum sensing under different <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\alpha $ </tex-math></inline-formula> values over indoor, outdoor, and vehicle fading channels environment.

Multi‐slot reservation‐based multi‐channel MAC protocol for dense wireless ad‐hoc networks

A multi-channel medium access control (MAC) is proposed for dense wireless ad-hoc networks, called MSR-MMAC, which aims to enhance throughput by introducing multi-slot reservation into multiple channels environment. Based on the integration of carrier sense multiple access with collision avoidance and time division multiple access, MSR-MMAC alternately implements contention-based channel access and multiple reservation-based data transmission on a certain frequency channel. Besides, the authors build an enhanced Markov model to analyse the throughput performance of the proposed MSR-MMAC protocol, which is further validated by extensive simulations using ns-2. Simulation results show that the proposed MSR-MMAC protocol reduces the average collision probability and improves throughput significantly.

Long-term sensitization training in Aplysia decreases the excitability of a decision-making neuron through a sodium-dependent mechanism.

In Aplysia, long-term sensitization (LTS) occurs concurrently with a suppression of feeding. At the cellular level, the suppression of feeding is accompanied by decreased excitability of decision-making neuron B51. We examined the contribution of voltage-gated Na+ and K+ channels to B51 decreased excitability. In a pharmacologically isolated Na+ channels environment, LTS training significantly increased B51 firing threshold, compared with untrained controls. Conversely, in a pharmacologically isolated K+ channels environment, no differences were observed between trained and untrained animals in either amplitude or area of B51 K+-dependent depolarizations. These findings suggest that Na+ channels contribute to the decrease in B51 excitability induced by LTS training.

Performance Analysis of STBC/SFBC System in Time-varying and Multi-path Channels

This study analyzed STBC and SFBC-OFDM systems having two or four transmission antennas in the time-varying and multi path fading channels environment. According to the performance analysis result, performance degradation was confirmed in this study, as channel variation period becomes shorter, when orthogonal or quasi-orthogonal STBC/SFBC technique was applied to the system having two or four transmission antennas in the time-varying and multi path fading channels. Also, the detection method using synchronization was applied for performance improvement. As a result of performance analysis on the STBC system in a time-varying channel and on the SFBC-OFDM system in the multi path channel, performance fell, as maximum time delay increased due to coherence time decline arising from the decrease of channel correlation coefficient, respectively, and the increase of the number of taps. However, BER (bit error rate) performance at SNR 25dB or higher was ascertained to improve up to 10 -3 ~10 -4 . Compared to the detection technique using ZF (zero forcing), the MMSE (minimum mean square error) detection technique showed good performance by acquiring 1~5dB or higher SNR gain. But, the ZF detection technique had a merit of being simpler from the hardware complexity aspect, compared to the MMSE detection technique. This study showed a possibility of high speed data transmission without additional bandwidth expansion by increasing the number of transmission antennas as a result of a performance analysis in the time-varying and multi path fading generated according to user mobility in the mobile communications environment.

Robust Control of Networked Systems With Variable Communication Capabilities and Application to a Semi-Active Suspension System

This paper is concerned with a robust control problem of a class of networked systems operated within a multiple communication channels (MCCs) environment. A practical scenario is considered that the active channel in such MCCs for the data communication is switched and the switching is governed by a Markov chain. For each channel, two network-induced imperfections, time delays, and packet dropouts with different characteristics are taken into account. Suppose that the practical plant is subject to energy-bounded disturbance and norm-bounded uncertainties, a robust controller is designed to ensure that the closed-loop system is robustly stable and achieves a disturbance attenuation index against the phenomenon of channel switching. A semi-active suspension system is introduced to illustrate the effectiveness, applicability of the proposed approach, and to demonstrate the advantages of the MCCs scheme within the channel-switching framework.

Full Duplex Relay Based Cognitive Radio System with Physical Layer Network Coding

In this paper, a full duplex relay (FDR) based cognitive radio (CR) system is proposed with two secondary source nodes and two secondary destination nodes. The concept of physical layer network coding (PLNC) is applied on decode and forward (DF) FDR to ensure that both source nodes can transmit data to both destination nodes. Further, the availability of multiple spectrum bands enables CR system to decode source symbols at destination nodes. The major advantage of the proposed system with FDR and PLNC is that it requires only one time slot to send the data from both the source nodes to both the destination nodes. If FDR is replaced with half duplex relay (HDR), 2 time slots are required for the CR system. If PLNC is not applied at the DF relay, the CR system would require 2 or 4 time slots when FDR or HDR is employed, respectively. In Nakagami-$$m$$m fading channels environment, analytical expressions are derived for end-to-end outage performance of the proposed PLNC based system in the presence of echo interference at the FDR and with HDR in the place of FDR. The outage performance of the proposed CR system is analyzed for various scaling and shape parameters of Nakagami-$$m$$m fading channels.

Lipid Affinity to the Voltage-Gated Potassium Channel KvAP

Voltage-gated potassium channels (KV) are formed by a central conducting pore surrounded by four voltage sensor domains. Functional studies have revealed that biophysical properties of lipid molecules in the channels environment can have strong effects on the activity of KV channels. Here, we investigated the influence of different lipids as well as their affinity to KvAP channels. We carried out electrophysiology measurements by fusing vesicles containing purified channels into planar lipid bilayers with varied lipid compositions. We found that KvAP properties are mainly determined by the lipid composition in the vesicles and not the lipids in the bulk bilayer, suggesting that KvAP has a preferential affinity to the lipids it comes in contact with first. It also shows that there is very limited exchange of the annular lipids around the channels. Even with time and at higher temperature, lipids from the bilayer did not mix with those of the vesicles, suggesting a strong channel-lipid interaction or confinement of lipid molecules to a microdomain around the channel. The annular lipids in immediate proximity of the VSD determines the mid-activation point of KvAP. Additionally, a bulk effect from positively charged lipids forming the bilayer affected the slope of the conductance-voltage curves. Here, the energy barriers and thus the kinetic rates of pore opening and entering the inactivated state are affected. This effect could be neutralized by addition of counter charges to the bilayer. Our results suggest that the binding site proposed also for other Kv channels has a similar affinity for different phospho- and non-phospholipids whereas exchange with bulk lipids is very restricted. Apart from the structural information, this has also implications on the experimental design when working with membrane proteins reconstituted in planar lipid bilayer.

Physical Layer Authentication over MIMO Fading Wiretap Channels

In a wide band and multipath rich environment, precise channel estimation allows authenticating the source and protecting the integrity of a message at the physical layer without the need of a pre-shared secret key. This allows also a reduction of the burden on the authentication protocols at higher layers. In this paper we develop an authentication scheme in the framework of hypothesis testing that suits a multiple wiretap channels environment with correlated fading, as is the case of multiple input multiple output (MIMO) systems and/or orthogonal frequency division multiplexing (OFDM) modulation. By allowing some degree of correlation among the channels, we formulate the optimal attack strategy for the cases of both single attempt and multiple repeated trials. For the latter scenario, due to the complexity of the optimal solution, we also develop a simpler suboptimal attack strategy. The performance of the proposed methods is evaluated in a MIMO/OFDM scenario and numerical results show the merits of the proposed approaches that can be adopted as a layer one authentication mechanism.

Diagenetic characteristics and reservoir quality of the Lower Cretaceous Biyadh sandstones at Kharir oilfield in the western central Masila Basin, Yemen

The Lower Cretaceous Biyadh Formation in the Masila Basin is an important hydrocarbon reservoir. However, in spite of its importance as a reservoir, published studies on the Biyadh Formation more specifically on the diagenesis and relate with reservoir quality, are limited. Based on core samples from one well in the Kharir oilfield, western central Masila Basin, this study reports the lithologic and diagenetic characteristics of this reservoir. The Biyadh sandstones are very fine to very coarse-grained, moderate to well sorted quartzarenite and quartzwacke. The diagenetic processes recognized include mechanical compaction, cementation (carbonate, clay minerals, quartz overgrowths, and a minor amount of pyrite), and dissolution of the calcite cement and feldspar grains. The widespread occurrences of early calcite cement suggest that the Biyadh sandstones lost a significant amount of primary porosity at a very early stage of its diagenetic history. Based on the framework grain–cement relationships, precipitation of the early calcite cement was either accompanied or followed by the development of part of the pore-lining and pore-filling clay cements. Secondary porosity development occurred due to partial to complete dissolution of early calcite cement and feldspar grains. In addition to calcite, several different clay minerals including kaolinite and chlorite occur as pore-filling and pore-lining cements. Kaolinite largely occurs as vermiform and accelerated the minor porosity loss due to pore-occlusion. Chlorite coating grains helps to retain primary porosity a by retarding the envelopment of quartz overgrowths. Porosity and permeability data exhibit good inverse correlation with cement. Thus, reservoir quality is controlled by pore occluding cement. Diagenetic history of the Biyadh sandstones as established here is expected to help better understanding and exploitation of this reservoir. The relation between diagenesis and reservoir quality is as follows: the initial porosity was decreased by compaction and cementation and then increased by dissolution of early calcite cement and feldspar grains. The reservoir quality is also affected by depositional environment controls of grain size, sorting and matrix. Thus, best good quality reservoir rocks were deposited in braided river channels environment, where no inhibited authigenic clays and high percentages of detrital quartz.

An Investigation of Self-Interference Reduction Strategy in a Spatially Correlated MIMO Channel

One of the efficient ways to transmit high data rate is by employing a multiple-input multiple-output (MIMO) transmission. One of the MIMO schemes, known as spatial multiplexing (SM), relies on the linear independence data streams from different transmit antennas to exploit the capacity from the fading channels. Consequently, SM suffers from the effect of spatial correlation which is the limiting factor in achieving the capacity benefit that SM can offer. In an attempt to increase the robustness of the SM transmission in a wide range of correlated channels, the use of dynamic subcarrier allocation (DSA) is investigated. The effective signal-to-interference-and-noise ratio (SINR) metric is used as the performance metric to determine the subcarrier quality which can then be utilised in the allocation. Two novel variants of the subcarrier allocation scheme are proposed. It is shown that the DSA-SINR approach improves the BER performance of SM transmission in highly correlated channels environment.

Design of Networked Controller for Ball and Beam System under Feedback Channels Constraints

A controller is designed for the ball and beam system under the limited feedback channels environment. We introduce a binary-valued function to establish measurement communication sequences, which describe the state of sensors that can access network to send measure signals at any one time. The model of networked system is built, then the controllability and observability to ensure the stability of the system is discussed. A networked controller is designed according to the stochastic control theory. Finally the numerical examples illustrate the effectiveness for the proposed method.

New and exceptional discovery in the Upper Cretaceous of the Iberian Peninsula: the palaeontological site of “Lo Hueco”, Cuenca, Spain

The palaeontological site of “Lo Hueco” was discovered in Cuenca, Spain, in 2007. It includes a stratigraphic interval in “Garumn” facies belonging to the upper part of the Villalba de la Sierra Formation. A succession of versicolor marly mudstone levels (V, G1, R1, G2, R2 and M) can be observed at the site studied. This succession is partially modified by a sandy channel structure (C) and by a sulphated interval (S). The C structure and the G1, G2 and R2 (lower part) levels have an extremely rich and varied fossil concentration and have provided to date more than 8500 macroremains. These are mainly from vertebrates, but also from plants and invertebrates. In general, vertebrates are represented by mineralized bones with an early infilling of gypsum, a ferruginous crust, and a secondary precipitation of gypsum; invertebrates by internal moulds; and plants by carbonized remains. Among the vertebrates, titanosaur dinosaurs (some of them with partially articulated skeletons) are by far the most common representatives, although lepisosteid fishes, bothremydid turtles, squamate lizards, eusuchian crocodiles, and ornithischian and theropod dinosaurs are also well represented. The relative stratigraphic position and the palaeontological content of this site allow to attribute it to the upper Campanian-lower Maastrichtian. Interpretation of its materials suggests a near coast muddy flood plain crossed by distributary sandy channels environment, exposed to brackish to fresh water aquatic influence.

Advertising channel selection in a segmented market

We consider a market with a finite number of segments and assume that several advertising channels are available, with different diffusion spectra and efficiencies. The problem of the choice of an advertising channel to direct the pre-launch campaign for a new product is analyzed in two steps. First, an optimal control problem is solved explicitly in order to determine the optimal advertising policy for each channel. Then a maximum profit channel is chosen. In a simulation example we consider the choice of a newspaper among six available and analyze the relations among the firm target market and the advertising channels environment which induce the optimal decision.

The Orange Juice Distribution Channel: Some Characteristics, Opportunities and Threats.

The fruit juice market is growing for several years, and will be continuing to expand, mainly because these products are aligned with general trends regarding food and beverage consumption. Several changes are taking place in the fruit juice distribution channels environment in Europe, a growing importance of food-service, the penetration of the global beverage brands (mainly Coca-Cola/Minute Maid and Pepsi/Tropicana), the concentration in retailing and also in the FCOJ (Frozen Concentrated Orange Juice) supply. These changes are threatening and also bringing opportunities to companies. This paper has two objectives. The first is to provide a general overview about the agents in the European marketing channels of the FCOJ, focusing on the final juice consumers, retailing, food service and the beverage industry. The framework for this part is build up of the marketing channel concepts and functions (Stern et al., 1996; Berman, 1996; Rosembloom, 1999), and data was gathered from the literature about fruit juices and provided by European companies in interviews. The second objective is to produce a strategic analysis of these agents in the channel, listing opportunities and threats for the following years, using the strategic SWOT (strong and weak points, opportunities and threats) analysis (Johnson & Scholes, 1997). According to the Authors, “a SWOT analysis can be a useful way to summarise the relationship between key environmental influences, the strategic capability of the organisation and hence the agenda for developing new strategies (p. 174)”. The analysis will not be done for a particular company, but for the whole industry, and further, as a suggestion, each company can use the listed points to evaluate itself. The Journal of Food Technology in Africa Volume 5 Number 2 (April - June 2000), pp. 52-58