Multiple Channel Model Research Articles

Real-FlexE: Real-time Flexible channel Emulator

In digital communications, accurately modeling and replicating the channel effects between a transmitter and receiver is essential to assess their impact on transmitted data. Access to a real-time channel emulator is therefore crucial in the development of telecommunication systems. This paper presents a configurable, flexible, and high-performance FPGA-based channel emulator that supports multiple channel models, including Doppler, AWGN, and multi-path Fading. We explore bit-width precision in the components and present trade-offs between quality and resource utilization. Our exploration demonstrates ∼25%–∼45% savings in various resources while maintaining the accuracy of the channel effects and operating at a high throughput of 500 Msps.

Multiple Channels Model Based on Mel Spectrogram for Classifying Abnormalities in Lung Sound

Lung sound analysis plays an important role in the assessment and diagnosis of respiratory conditions and diseases. It can provide valuable information about the functioning of the respiratory system, including the airways, lungs, and associated structures. By analyzing the characteristics of lung sounds, healthcare professionals can gain insights into the presence of abnormalities, such as airway obstructions, lung diseases, and respiratory infections. In this paper, a multiple channel model for processing and classifying abnormalities in lung sound is proposed, which utilize the characteristics of Mel spectrogram and the Empirical Mode Decomposition (EMD). Unlike previous research which directly convert the lung sound into scalogram or spectrogram, the pre-processing of the original audio signal is considered and focused in this paper. This pre-processing step includes denoising, resampling, padding and augmentation, which incredibly increase the quality of the input signal. Finally, the multiple channel is put into the VGG16 deep learning model to classify the abnormalities in lung sound, including wheezes, crackles, and both. The model is trained and tested on the benchmark ICBHI dataset. The proposed model has shown better performance when compared with the state-of-the-art researches.

Non-line-of-sight multiple reflection underwater wireless optical communications channel model based on a capillary waves rough sea surface.

In a non-line-of sight reflective underwater wireless optical communications (UWOC) link, the transmitted beam relies on reflections from the sea surface to propagate to the underwater receiver. Most previous research on reflective channels has sufficiently considered single reflections from a smooth or rough surface, while ignoring the effect of multiple reflections. In fact, a rough sea surface may cause the reflected photons to hit the sea surface again, which is referred as a multiple reflection process. To make up for deficiencies in the existing literature, we first construct a capillary waves rough sea surface model, and then present a multiple reflection channel model with the help of the Monte Carlo ray tracing approach. The path loss and channel impulse response (CIR) were further evaluated based on the model for different communications scenarios. Numerical results suggest that multiple reflections increase the path loss by more than about 5dB, and reduce the CIR amplitude to less than one-third compared to a single reflection. The work done in this paper aims to provide theoretical support for UWOC system design.

Dynamic MmWave channel reconstruction of MIMO OTA testing for handover scenarios

The evaluation of handover performance is essential for ensuring seamless user experience under innovative application scenarios in the fifth generation (5G) and beyond era, including autonomous driving, mobile augmented and virtual reality. However, due to the hardware constrains of a sectored multiprobe anechoic chamber (SMPAC), switching among multiple channel models is of low precision with a high cost in traditional over-the-air (OTA) test solutions. In this paper, we present an efficient and repeatable emulation strategy to reconstruct dynamic millimeter-wave (mmWave) channels in laboratories for multiple-input multiple-output (MIMO) mobile devices. Firstly, we propose a novel evaluation metric, called average power angular spectrum similarity percentage (APSP), which minimizes the unexpected impact induced by the indefinite condition of adaptive antenna arrays in mmWave terminals during handover process. Moreover, we propose a partitioned probe configuration strategy by designing a beam directivity-based switching circuit, which enables quick changes of probe configurations in SMPAC. Simulation results demonstrate the effectiveness of the proposed algorithms, thus providing a guideline for the reconstruction of the dynamic channel in different scenarios with resource limitation.

A Wavelength-Dependent Visible Light Communication Channel Model for Underground Environments and Its Performance Using a Color-Shift Keying Modulation Scheme

Reliable wireless communications are crucial for ensuring workers’ safety in underground tunnels and mines. Visible light communications (VLC) have been proposed as auxiliary systems for short-range wireless communications in underground environments due to their seamless availability, immunity to electromagnetic interference, and illumination capabilities. Although multiple VLC channel models have been proposed for underground mines (UM) so far, none of these models have considered the wavelength dependence of the underground mining VLC channel (UM-VLC). In this paper, we propose a single-input, single-output (SISO), wavelength-dependent UM-VLC channel model considering the wavelength dependence of the light source, reflections, light scattering, and the attenuation due to dust and the photodetector. Since wavelength dependence allows us to model VLC systems more accurately with color-based modulation, such as color-shift keying (CSK), we also propose a wavelength-dependent CSK-based UM-VLC channel model. We define a simulation scenario in an underground mine roadway and calculate the received power, channel impulse response (CIR), signal-to-noise ratio (SNR), signal-to-interference ratio (SIR), root mean square (RMS) delay, and bit error rate (BER). For comparison, we also calculate these parameters for a monochromatic state-of-the-art UM-VLC channel and use it as a reference channel. We find that the inclusion of wavelength-dependency in CSK-based UM-VLC systems plays a significant role in their performance, introducing color distortion that the color calibration algorithm defined in the IEEE 802.15.7 VLC standard finds harder to revert than the linear color distortion induced by monochromatic CSK channels.

QUEUING THEORY APPLICATION AND CUSTOMERS’ TIME MANAGEMENT IN DEPOSIT MONEY BANKS IN NIGERIA

The study examined queuing theory, application and customers time management in deposit money banks in Nigeria.. A comparative analysis between Access Bank PLC branch in Ajilosun and First Bank PLC, Oke Isa, Ado Ekiti, Ekiti State were used as a case study. Data for the study were gathered through observation of the arrival time, time spent waiting in the queue, service time and time of departure customers from the banking hall. The observation time at Access Bank started by 2.30pm and ended 3.44pm which has been previously observed to be the peak period of the bank while the observation time of the First Bank PLC started 3.00pm and ended 4.57pm on different days. Data sourced were fitted into the single and multiple channel models and the results computed and analyzed manually. It was revealed that the mean service rate, the mean time spent in the queue by a customer, and aggregate service rate in the system by a customer at Access bank plc are substantially reduced compared to that of the first bank plc while the waiting line is short most especially for the multiple channels with the real time data processing enhancing the service delivery. It was concluded that despite these differences, queuing system and application of it in the banking industry, especially in the sampled banks is effective in achieving quality service delivery and this is also enhanced by the application of real time data processing adopted by the banks. Therefore, the study recommended that queue management should be employed by banks as it will enhance the quality of service delivery and time management for both banks and the customers. In addition, a single channel for banks that have high traffic intensity rate should be discouraged while a multiple channel should be encouraged as it reduces the waiting time of bank customers in the system. Lastly, idle time of the servers need to be checked as this could lead to more waiting time for customers.

Coverage outcomes (effects), costs, cost-effectiveness, and equity of two combinations of long-lasting insecticidal net (LLIN) distribution channels in Kenya: a two-arm study under operational conditions

BackgroundMalaria-endemic countries distribute long-lasting insecticidal nets (LLINs) through combined channels with ambitious, universal coverage (UC) targets. Kenya has used eight channels with variable results. To inform national decision-makers, this two-arm study compares coverage (effects), costs, cost-effectiveness, and equity of two combinations of LLIN distribution channels in Kenya.MethodsTwo combinations of five delivery channels were compared as ‘intervention’ and ‘control’ arms. The intervention arm comprised four channels: community health volunteer (CHV), antenatal and child health clinics (ANCC), social marketing (SM) and commercial outlets (CO). The control arm consisted of the intervention arm channels except mass campaign (MC) replaced CHV. Primary analysis used random sample household survey data, service-provider costs, and voucher or LLIN distribution data to compare between-arm effects, costs, cost-effectiveness, and equity. Secondary analyses compared costs and equity by channel.ResultsThe multiple distribution channels used in both arms of the study achieved high LLIN ownership and use. The intervention arm had significantly lower reported LLIN use the night before the survey (84·8% [95% CI 83·0–86·4%] versus 89·2% [95% CI 87·8–90·5%], p < 0·0001), higher unit costs ($10·56 versus $7·17), was less cost-effective ($86·44, 95% range $75·77–$102·77 versus $69·20, 95% range $63·66–$77·23) and more inequitable (Concentration index [C.Ind] = 0·076 [95% CI 0·057 to 0·095 versus C.Ind = 0.049 [95% CI 0·030 to 0·067]) than the control arm. Unit cost per LLIN distributed was lowest for MC ($3·10) followed by CHV ($10·81) with both channels being moderately inequitable in favour of least-poor households.ConclusionIn line with best practices, the multiple distribution channel model achieved high LLIN ownership and use in this Kenyan study setting. The control-arm combination, which included MC, was the most cost-effective way to increase UC at household level. Mass campaigns, combined with continuous distribution channels, are an effective and cost-effective way to achieve UC in Kenya. The findings are relevant to other countries and donors seeking to optimise LLIN distribution.Trial registrationThe assignment of the intervention was not at the discretion of the investigators; therefore, this study did not require registration.

Group Decision Support System (GDSS) dengan Metode Entropy untuk Menentukan Prioritas Antrian Layanan Rumah Sakit Menggunakan Multiple Channel Model (M/M/s)

Layanan sistem antrian di di Rumah Sakit mengalami masalah bahwa antrian layanan lebih lama dari pada pelayanan kesehatanya sendiri. Atas dasar hal tersebut dibutuhkan sebuah model yang mampu memberikan layanan antri yang tepat sasaran dan memberikan rasa keadilan kepada pengantri. Dalam paper ini digunakan 10 kriteria untuk menentukan prioritas antrian yakni: Faktor Risiko Penyakit, Biaya Perawatan, Tenaga Medis, Peralatan Kesehatan, Waktu tunggu, Jarak Domisili Pasien, Usia, Jenis Kelamin, Jumlah pasien yang dilayani diunit yang dituju dan Keputusan Pimpinan. Ke-10 kriteria ini agar diperoleh hasil yang lebih objektif dikombinasikan dengan Group Decision Making Tipe 2 (GDM2) dan metode entropy untuk mengevaluasi antrian model Multiple Channel Model (M/M/s). Jumlah loket layanan sangat berpengaruh terhadap jumlah antrian dan waktu layanan. Kesimpulan yang didapat bahwa menambah jumlah loket layanan sebanyak dua kali lipat dari akan memangkas 1/2 dari jumlah orang yang dilayani per-satuan waktu pada setiap jalur antrian terutama direntang waktu antara jam 8.00 wib s.d. 10.00 wib. Selain itu berdasarkan penilaian Decision Maker (DM) dalam kelompok pengambil keputusan, kriteria biaya adalah faktor paling penting atau kritis ketika memberikan prioritas layanan diikuti dengan kriteria keputusan pimpinan dan faktor risiko penyakit. Penambahan kategori-kategori penyakit yang berbahaya dalam sistem antrian dapat membuat sistem ini menjadi lebih baik.

Design of Communication Systems Using Deep Learning: A Variational Inference Perspective

Recent research in the design of end to end communication system using deep learning has produced models which can outperform traditional communication schemes. Most of these architectures leveraged autoencoders to design the encoder at the transmitter and decoder at the receiver and train them jointly by modeling transmit symbols as latent codes from the encoder. However, in communication systems, the receiver has to work with noise corrupted versions of transmit symbols. Traditional autoencoders are not designed to work with latent codes corrupted with noise. In this work, we provide a framework to design end to end communication systems which accounts for the existence of noise corrupted transmit symbols. The proposed method uses deep neural architecture. An objective function for optimizing these models is derived based on the concepts of variational inference. Further, domain knowledge such as channel type can be systematically integrated into the objective. Through numerical simulation, the proposed method is shown to consistently produce models with better packing density and achieving it faster in multiple popular channel models as compared to the previous works leveraging deep learning models.

TDOA-Based Mobile Localization Using Particle Filter With Multiple Motion and Channel Models

TDOA-Based Mobile Localization Using Particle Filter With Multiple Motion and Channel Models

Effect of heat losses on monolithic reactors for VOC abatement

In this contribution a theoretical study of the thermal effects due to heat losses on monolithic reactors for the catalytic combustion of VOC is carried out.To describe the performance of the reactor under steady-state non-isothermal non-adiabatic conditions a heterogeneous 1D Multiple Channel Model is considered, where the monolith is represented by several zones in the form of square concentric rings, each one represented by a square section single channel. Internal and external mass transfer diffusional limitations are taken into account as well as external heat transfer resistance. Heat transfer by conduction through the solid (cordierite) is considered along the cross-section coordinate of the monolith, i.e., from the central zones to peripheral zones at lower temperatures.Although an efficient thermal insulation is selected, the channels of the periphery can operate several degrees colder that the channels of the central zones, these lower temperatures are associated to non-complete VOC conversions, which are emitted into the atmosphere. Studies of parametric sensitivity with respect of inlet temperature reveals that heat losses become more relevant when the reactor is operating near the Emission Limit Value.In relation to design considerations, as the reactor scale decreases and the external area/volume ratio increases, the effect of heat losses on VOC emissions is magnified. The inlet temperature set point should be high enough to prevent high VOC emissions due to lower inlet VOC concentration in a heat loss scenario. This results in higher energetic requirements to ensure VOC complete conversion.To face the reactor performance issues related with heat losses to the environment, optimized designs were proposed aiming to increase the residence times in peripheral zones, which effectively enhance the reactor performance.

Development of a real‐scale cooling module for a PV power plant

The goal of this study is to develop units of a photovoltaic (PV) cooling system and evaluate its performance, aiming at commercial electricity production, once the increase in electricity output is obtained by cooling down the temperature of the PV module. The methodology covers the description of production procedures, control and verification of three different models of the cooling system, of which two are sheet-and-tube types, with different diameters of coil curvature (85 and 140 mm), and one is a multi-channel type model. Results show that the production of the two sheet-and-tube models presented no issues during their construction and operating phases, while the multiple-channel model presented some complications at the construction phase (e.g. the thickness of the sheets hampered the welding process, leading to leakages during the tightness tests). The empirical control tests showed that the temperature of the PV module with a cooling system applied remains lower than the nominal operating cell temperature, whereas the PV modules without a cooling system presented temperatures higher than 68.1°C. Thus, the authors conclude that the most appropriate model for large-scale production applied at PV systems is the coil one, with 85 mm of the diameter of coil curvature.

Adaptive threshold device for detection of reflections based visible light communication

One of the major restriction of existing visible light communication (VLC) systems is the limitation of channel transmission bandwidth which can be used in such systems. In this paper, an optimal and a suboptimal receiver are proposed to increase the on-off keying (OOK) transmission rate and hence to increase bandwidth efficiency of VLC system when a multiple reflections channel model is used to characterize the impacts of reflections in VLC signal propagation. Optimal detector consists of a simple receiver with a memory to find the optimal threshold based on the previous detected data. The error probability of the proposed detector is derived in the closed form and compared with the simulation results. It is demonstrated that the proposed detectors can improve the transmitting bandwidth close to the 3-dB bandwidth of the LOS channel model (which is several hundred MHz), whereas bit-error-rate (BER) remains low, in particular where the optimal detection is utilized.

Transient thermal–hydraulic analysis of a space thermionic reactor

Nuclear power can serve as a durable energy source for future space exploitation and exploration. According to the special features of the space power system, a transient analysis code, TASTIN (Transient Analysis code of Space Thermionic Nuclear reactor), is developed to analyze the thermal–hydraulic characteristics of the TOPAZ-II system. The point reactor kinetics equations with six-family delayed neutrons are applied to calculate the fission power, considering the temperature reactivity feedback effects of the moderator, UO2 fuel, electrodes in the core and the reactivity insertion of control and safety drums. The thermal–hydraulic analysis of the core is carried out with multiple-channel model. A detailed tube-fin radiator model is also established and the finite difference method is used to calculate the conduction with radiation of the fin. The steady state calculation results are in good agreement with the design values. From both the partial loss of flow accident and the overpower transient, the moderator has the dominant temperature effect, account for positive reactivity temperature coefficient of the reactor. In addition, the results of the accidents above also prove that the reactor system has a sufficient safety margin during these typical accidents.

RELAP5 analyses on the influence of multi-dimensional flow in the core on core cooling during LSTF cold-leg intermediate break LOCA experiments in the OECD/NEA ROSA-2 Project

Test-2 and Test-7 of the second Organization for Economic Co-operation and Development / Nuclear Energy Agency (OECD/NEA) Rig-of-Safety Assessment (ROSA-2) Project were performed with the Large Scale Test Facility (LSTF), which simulated thermal-hydraulic responses during a pressurized water reactor cold-leg intermediate break loss-of-coolant accident (IBLOCA). Test-2 simulated 17% cold-leg break with single failure of an emergency core cooling system (ECCS). The core liquid level decreased to the bottom at loop seal clearing (LSC), causing high cladding temperature excursion. Test-7 simulated 13% cold-leg break with full injection of the ECCS. Compared to Test-2, the cladding surface temperature in Test-7 was quite low due to greater liquid level recovery after the LSC. To well understand the observed phenomena and to improve the best-estimate code predictive capability, RELAP5 post-test analyses were performed. The RELAP5 analyses employed two core models: one is a single-channel core model that simulates the whole core with one channel of a vertical stack of nine equal-height volumes, and the other is a multiple-channel core model that is composed of three channels in which adjacent vertically stacked volumes are horizontally connected with cross-flow junctions. The analyses with the multi-channel core model predicted better than with the single-channel core model for such parameters as core-collapsed liquid level and cladding surface temperature for both Test-2 and Test-7, by more realistically representing multi-dimensional flow in the core. Such a practical method for better representation of multi-dimensional flows turned out to be important to improve the IBLOCA analysis.

MAC Protocol Design and Performance Analysis for Random Access Cognitive Radio Networks

In this paper, we consider the medium access control (MAC) protocol design for random access cognitive radio network (CRN). Based on asynchronous spectrum sensing technique and RTS/CTS mechanism, a new MAC protocol, namely, cognitive-radio-based carrier sense medium access with collision avoidance (CR-CSMA/CA) is proposed to coordinate the channel access of secondary network as well as protect the operation of primary network, which applies to both single and multiple channel models. Using the G/G/1 queuing model with consideration of unsaturated and saturated network condition, we develop a framework to analyze the proposed MAC protocol and also derive closed-form expressions of specific performance metrics such as normalized throughput, average packet service time, etc. Performance evaluations illustrate and validate that the performance of CR-CSMA/CA varies with the offered traffic load of secondary network and the spectrum utilization rate of primary network, respectively, and also show that CR-CSMA/CA outperforms other relevant MAC protocols.

Testing the horizontal-vertical stereo anisotropy with the critical-band masking paradigm

Stereo vision has a well-known anisotropy: At low frequencies, horizontally oriented sinusoidal depth corrugations are easier to detect than vertically oriented corrugations (both defined by horizontal disparities). Previously, Serrano-Pedraza and Read (2010) suggested that this stereo anisotropy may arise because the stereo system uses multiple spatial-frequency disparity channels for detecting horizontally oriented modulations but only one for vertically oriented modulations. Here, we tested this hypothesis using the critical-band masking paradigm. In the first experiment, we measured disparity thresholds for horizontal and vertical sinusoids near the peak of the disparity sensitivity function (0.4 cycles/°), in the presence of either broadband or notched noise. We fitted the power-masking model to our results assuming a channel centered on 0.4 cycles/°. The estimated channel bandwidths were 2.95 octaves for horizontal and 2.62 octaves for vertical corrugations. In our second experiment we measured disparity thresholds for horizontal and vertical sinusoids of 0.1 cycles/° in the presence of band-pass noise centered on 0.4 cycles/° with a bandwidth of 0.5 octaves. This mask had only a small effect on the disparity thresholds, for either horizontal or vertical corrugations. We simulated the detection thresholds using the power-masking model with the parameters obtained in the first experiment and assuming either single-channel and multiple-channel detection. The multiple-channel model predicted the thresholds much better for both horizontal and vertical corrugations. We conclude that the human stereo system must contain multiple independent disparity channels for detecting horizontally oriented and vertically oriented depth modulations.

Development of a transient thermal-hydraulic code for analysis of China Demonstration Fast Reactor

The transient thermal-hydraulic code THACOS is under development for analysis of China Demonstration Fast Reactor. Applying modular technology, the code contains the core module, the pump module, the sodium pool module and the heat exchanger module and each module could operate separately. It can provide one-dimensional thermal-hydraulic simulation for the primary sodium coolant loop. The point reactor kinetics equations with six-group delayed neutrons have been applied to calculate the core power considering reactivity feedbacks caused by the Doppler effect, coolant density, axial expansion of fuel rods and radial expansion of the core. Multiple-channel model is applied to depict the core. Compressible homogenous flow model is used for the two-phase flow of sodium. The calculated results show that sodium boiling will occur quickly under the ULOF accident without any shutdown rods insertion. While, with the insertion of three hydraulically suspended shutdown rods, the core could be shut down safely and boiling will not occur in a short period of time. Obviously, the passive hydraulically suspended shutdown rods could keep the core safe under ULOF accidents.

多チャネル機構モデルによる Helmholtz-Hering 錯視の解析

多チャネル機構モデルによる Helmholtz-Hering 錯視の解析

Parity-Check Network Coding for Multiple Access Relay Channel in Wireless Sensor Cooperative Communications

A recently developed theory suggests that network coding is a generalization of source coding and channel coding and thus yields a significant performance improvement in terms of throughput and spatial diversity. This paper proposes a cooperative design of a parity-check network coding scheme in the context of a two-source multiple access relay channel (MARC) model, a common compact model in hierarchical wireless sensor networks (WSNs). The scheme uses Low-Density Parity-Check (LDPC) as the surrogate to build up a layered structure which encapsulates the multiple constituent LDPC codes in the source and relay nodes. Specifically, the relay node decodes the messages from two sources, which are used to generate extra parity-check bits by a random network coding procedure to fill up the rate gap between Source-Relay and Source-Destination transmissions. Then, we derived the key algebraic relationships among multidimensional LDPC constituent codes as one of the constraints for code profile optimization. These extra check bits are sent to the destination to realize a cooperative diversity as well as to approach MARC decode-and-forward (DF) capacity.