Search

Experiments are a commonly used method of research in software engineering (SE). Researchers report their experiments following detailed guidelines. However, researchers do not, in the field of test-driven development (TDD) at least, specify how they operationalized the response variables and, particularly, the measurement process. This article has three aims: (i) identify the response variable operationalization components in TDD experiments that study external quality; (ii) study their influence on the experimental results; (iii) determine if the experiment reports describe the measurement process components that have an impact on the results. We used two-part sequential mixed methods research. The first part of the research adopts a quantitative approach applying a statistical analysis of the impact of the operationalization components on the experimental results. The second part follows with a qualitative approach applying a systematic mapping study (SMS). The test suites, intervention types and measurers have an influence on the measurements and results of the statistical analysis of TDD experiments in SE. The test suites have a major impact on both the measurements and the results of the experiments. The intervention type has less impact on the results than on the measurements. While the measurers have an impact on the measurements, this is not transferred to the experimental results. On the other hand, the results of our SMS confirm that TDD experiments do not usually report either the test suites, the test case generation method, or the details of how external quality was measured. A measurement protocol should be used to ensure that the measurements made by different measurers are similar. It is necessary to report the test cases, the experimental task and the intervention type in order to be able to reproduce the measurements and statistical analyses, as well as to replicate experiments and build dependable families of experiments. [ABSTRACT FROM AUTHOR]

Abstract In this article an 8-port annular ring-shaped MIMO antenna for 5G and 5G advanced applications is presented. An annular ring on the radiating plane and novel isolator structure on the ground plane are etched over a Rogers RT/Duorid (5870 tm) substrate to achieve high performance antenna for mm wave applications. A systematic study is performed, and an optimized single port antenna (Design-4) is selected among Designs (1-4). The intended 8-port MIMO antenna resonates at 36.4 GHz and exhibits 6.1 GHz (34.2-40.3 GHz) wide bandwidth $$|S_{11}| < -10 \, \text {dB}$$ and 40 dB high isolation level. The proposed antenna covers a complete band of 5G NR-n260 which supports time division duplexing (TDD) mode. Moreover, a unique design of suggested antenna attains a high-level gain of 8.3 dB at 39 GHz and more than 85.2 % radiation efficiency. MIMO characteristics such as ECC, TARC, MEG and CCL are studied and found them in acceptable limit. Additionally, an approach toward massive antenna with 16-port for mmWave applications is also demonstrated. The proposed 16-port massive antenna with more than 22 dB isolation exhibits two bands: first band in 30-33 GHz for ports P9-P16 and second band in 33.5-40.9 GHz for ports P1-P8. A prototype of suggested 8-port antenna is fabricated, tested and validated and found it in close agreement of simulated results.

In this article an 8-port annular ring-shaped MIMO antenna for 5G and 5G advanced applications is presented. An annular ring on the radiating plane and novel isolator structure on the ground plane are etched over a Rogers RT/Duorid (5870 tm) substrate to achieve high performance antenna for mm wave applications. A systematic study is performed, and an optimized single port antenna (Design-4) is selected among Designs (1-4). The intended 8-port MIMO antenna resonates at 36.4 GHz and exhibits 6.1 GHz (34.2-40.3 GHz) wide bandwidth and 40 dB high isolation level. The proposed antenna covers a complete band of 5G NR-n260 which supports time division duplexing (TDD) mode. Moreover, a unique design of suggested antenna attains a high-level gain of 8.3 dB at 39 GHz and more than 85.2 % radiation efficiency. MIMO characteristics such as ECC, TARC, MEG and CCL are studied and found them in acceptable limit. Additionally, an approach toward massive antenna with 16-port for mmWave applications is also demonstrated. The proposed 16-port massive antenna with more than 22 dB isolation exhibits two bands: first band in 30-33 GHz for ports P9-P16 and second band in 33.5-40.9 GHz for ports P1-P8. A prototype of suggested 8-port antenna is fabricated, tested and validated and found it in close agreement of simulated results. [ABSTRACT FROM AUTHOR]

Auxiliary functions in software systems, often overlooked due to their perceived simplicity, play a crucial role in overall system reliability. This study focuses on the effectiveness of agile practices, specifically the pair programming and the test-first programming practices. Despite the importance of these functions, there exists a dearth of empirical evidence on the impact of agile practices on their development, raising questions about their potential to enhance correctness without affecting time-to-market. This paper aims to bridge this gap by comparing the application of agile practices with traditional approaches in the context of auxiliary function development. We conducted six experiments involving 122 participants (85 novices and 37 professionals) who used both traditional and agile methods to develop six auxiliary functions across three different domains. Our analysis of 244 implementations suggests the potential benefits of agile practices in auxiliary function development. Pair programming showed a tendency towards improved correctness, while test-first programming did not significantly extend the total development time, particularly among professionals. However, these findings should be interpreted cautiously as they do not conclusively establish that agile practices outperform traditional approaches universally. As indicated by our results, the potential benefits of agile practices may vary depending on factors such as the programmer's experience level and the nature of the functions being developed. Further research is needed to fully understand the contexts in which these practices can be most effectively applied and to address the potential limitations of our study. [ABSTRACT FROM AUTHOR]

5G NR is a wireless mobile communication system that supports ultra-high speed mobile communications, high reliability services, and large-scale Internet of Things. In a mobile communication environment, the Doppler effect, which is proportional to the speed of travel, causes channel changes over time, which can lead to communication performance degradation. In order to achieve optimal communication performance in a mobile communication environment, it is necessary to predict the Signal to Noise Ratio (SNR) between the base station and the terminal and select and transmit the most appropriate Modulation and Coding Scheme (MCS) accordingly. In this paper, we propose a method for selecting the MCS level of a single antenna based on Convolutional Neural Network (CNN) in 5G NR mobile communication systems. The proposed system assumes a time division duplex (TDD) scheme, measures the SNR at the time of reception, predicts the SNR at the time of future transmission using CNN based on the measured past channel information, and selects the MCS level based on the predicted SNR. Experimental results through computer simulation show that the proposed CNN-based MCS selection method has a lower probability of communication disconnection and higher transmission rate at all speeds compared to the existing average value method based on the average of SNR and the recent value method based on the most recently received SNR. In particular, the transmission speed of the proposed method is about 46% and 4.6% better than the existing average value method and recent value method, respectively, and can be utilized as a technology to increase the transmission speed in 5G mobile communication environment. [ABSTRACT FROM AUTHOR]

Test-driven development (TDD) is an agile practice of writing test code before production code, following three stages: red, green, and refactor. In the red stage, the test code is written; in the green stage, the minimum code necessary to make the test pass is implemented, and in the refactor stage, improvements are made to the code. This practice is widespread across the industry, and various studies have been conducted to understand its benefits and impacts on the software development process. Despite its popularity, TDD studies often focus on the technical aspects of the practice, such as the external/internal quality of the code, productivity, test smells, and code comprehension, rather than the context in which it is practiced. In this paper, we present a systematic literature review using Scopus, Web of Science, and Google Scholar that focuses on the TDD practice and the influences that lead to the introduction of test smells/anti-patterns in the test code. The findings suggest that organizational structure influences the testing strategy. Additionally, there is a tendency to use test smells and TDD anti-patterns interchangeably, and test smells negatively impact code comprehension. Furthermore, TDD styles and the relationship between TDD practice and the generation of test smells are frequently overlooked in the literature. [ABSTRACT FROM AUTHOR]

The usage of manufactured nanoparticles has grown over the past few decades in a variety of fields, including biomedicine, diagnostics, and environmental remediation, raising serious public concerns. Due to their numerous features, magnetic nanoparticles (MNPs) have attracted the most attention among these nanoparticles in the fields of medicine, pharmacology, drug delivery systems, molecular imaging, and biosensing. It is essential to note that whilst the systems' sizes are getting smaller due to the manufacturing of magnetic nanoparticles, the methods used to interpret their properties—bottom-up for the latter and top-down for the former—remain distinct. Here, we emphasise the necessity for a shared perspective whilst outlining the current state of the two domains and offering some predictions for potential future advancements. The review study discusses the use of MNPs in biomedicine, explains how they interact with living things, and assesses their toxicity. Also, clarify biocompatibility and add more information about the drug delivery system, such as targeted drug delivery. A thorough explanation of how MRI and the MNP work together is provided. Particular MNP applications were demonstrated using MRI, CT, and bioimaging. This would allow us to examine drug transport, tumour interaction, and toxicity. Additionally, difficulties with nanoparticles have been discussed, including stability, environmental toxicity, and safety measures. This review attempts to present a comprehensive summary of the state of current knowledge in magnetic nanoparticle research. [ABSTRACT FROM AUTHOR]

Currently in Ukraine, taking into account the development of the latest mobile Internet standards (3G/4G), it is possible to access the Internet even in remote places. There are no wired Internet due to the high cost of installation and maintenance. At the same time, a huge amount of equipment appeared on the market, which allows you to assemble systems for obtaining high-quality Internet over a wireless communication line. This refers to various types of antennas in the 900–2700MHz range, modems and routers with 3G/4G support. The locations of 3G/4G Internet base stations are in district centers predominantly. So, there is a situation that remote villages, settlements do not have the opportunity to get access to high-speed Internet. This especially harms the work of biological stations and rural medical clinics, which are spread over the territory of Ukraine and are often connected in a network. The purpose of the work is to describe briefly some practical results of our own development of providing high-quality mobile communication in some remote places of the territory of the state. To provide this service in remote areas of Ukraine, signal amplification is necessary. In addition, there is a problem with the propagation of radio waves over the rough terrains for the ultra short wave and microwave ranges. To solve this problem, it is proposed to use an external antenna with a high amplification factor, which will be installed at a height of at least 6 meters above the ground to reduce the impact of interference on the path of radio waves. [ABSTRACT FROM AUTHOR]

This article presents fully integrated 39-GHz bidirectional up- and down-conversion mixers for 5G millimeter-wave (mmWave) applications. Fabricated in a 65-nm CMOS process with a 1.2-V supply voltage, the up- and down-conversion mixers consume 39 and 43 mW, respectively. For 5G time-division duplexing (TDD) operation, intermediate-frequency (IF)/local-oscillator (LO)/radio-frequency (RF) T/R switches are introduced. For better isolation and low insertion loss between the up- and down-conversion mixer, a series-shunt single-pole double-throw (SPDT) structure and an equivalent lumped λ/4 transmission line are proposed for IF and RF T/R switches, respectively. To realize compact area and wide bandwidth, a transformer-based matching network is adopted in this design. Targeting multi-channel phased array applications, the measurement result shows that the up-conversion mixer achieves a 2.5-dB peak conversion gain with 6.5 GHz 3-dB bandwidth. Including the insertion loss of the switch and IF signal routing, at the maximum gain of 36.5 GHz, the up-conversion mixer achieves an output 1-dB gain compression point (OP1dB) of 2.5 dBm. Furthermore, the down-conversion mixer achieves a 5-dB peak conversion gain with a 9.7-GHz 3-dB bandwidth.

Densely distributed sensor networks can revolutionize environmental observations by providing real-time data with an unprecedented spatiotemporal resolution. However, field deployments often pose unique challenges in terms of power provisions and wireless connectivity. We present a framework for wirelessly connected distributed sensor arrays for near-surface temperature and/or deformation monitoring. Our research focuses on a novel time division duplex implementation of the LoRa protocol, enabling battery powered base stations and avoiding collisions within the network. In order to minimize transmissions and improve battery life throughout the network, we propose a dedicated delta encoding algorithm that utilizes the spatial and temporal similarity in the acquired data sets. We implemented the developed technologies in a AA battery powered hardware platform that can be used as a wireless data logger or base station, and we conducted an assessment of the power consumption. Without data compression, the projected battery life for a data logger is 4.74 years, and a wireless base stations can last several weeks or months depending on the amount of network traffic. The delta encoding algorithm can further improve this battery life with a factor of up to 3.50. Our results demonstrate the viability of the proposed methods for low-power environmental wireless sensor networks. [ABSTRACT FROM AUTHOR]

Introduction: Type 2 diabetes mellitus (T2DM) is a non-communicable disease with a high prevalence in Indonesia. T2DM is caused by insulin resistance and relative insulin deficiency. One of the therapy for T2DM is insulin administration which is injected into the subcutaneous tissue. The absorption of insulin in the subcutaneous tissue is influenced by many factors, one of which is the thickness of subcutaneous fat. This study aimed to determine the correlation between the skinfold thickness of T2DM patients with the total daily dose of insulin needed every day. Methods: This was an observational analytic study using a cross-sectional design to analyze the correlation between subcutaneous fat thickness represented by skinfold thickness and the total daily dose of insulin of T2DM patients. Measurement of skinfold thickness was carried out on the triceps using a skinfold caliper. Data on the patient's total daily dose of insulin were obtained from medical records. Results: A total of 53 patients were included in this study. The patient's mean triceps skinfold thickness was 26.29±8.72 mm. The mean total daily dose of insulin was 40.96±18.01 IU. The results of the Spearman Rank correlation test showed a significant correlation between skinfold thickness on the triceps and the patient's total daily dose of insulin (p

Due to the ongoing trend of digitalization, the importance of software for today’s society is continuously increasing. Naturally, there is also a huge interest in improving its quality, which led to a highly active research community dedicated to this aim. Consequently, a plethora of propositions, tools, and methods emerged from the corresponding efforts. One of the approaches that have become highly prominent is the concept of test-driven development (TDD) that increases the quality of created software by restructuring the development process. However, such a big change to the followed procedures is usually also accompanied by major challenges that pose a risk for the achievement of the set targets. In order to find ways to overcome them, or at least to mitigate their impact, it is necessary to identify them and to subsequently raise awareness. Furthermore, since the effect of TDD on productivity and quality is already extensively researched, this work focuses only on issues besides these aspects. For this purpose, a literature review is presented that focuses on the challenges of TDD. In doing so, challenges that can be attributed to the three categories of people, software, and process are identified and potential avenues for future research are discussed.

Test-driven development (TDD) is an agile practice of writing test code before production code, following three stages: red, green, and refactor. In the red stage, the test code is written; in the green stage, the minimum code necessary to make the test pass is implemented, and in the refactor stage, improvements are made to the code. This practice is widespread across the industry, and various studies have been conducted to understand its benefits and impacts on the software development process. Despite its popularity, TDD studies often focus on the technical aspects of the practice, such as the external/internal quality of the code, productivity, test smells, and code comprehension, rather than the context in which it is practiced. In this paper, we present a systematic literature review using Scopus, Web of Science, and Google Scholar that focuses on the TDD practice and the influences that lead to the introduction of test smells/anti-patterns in the test code. The findings suggest that organizational structure influences the testing strategy. Additionally, there is a tendency to use test smells and TDD anti-patterns interchangeably, and test smells negatively impact code comprehension. Furthermore, TDD styles and the relationship between TDD practice and the generation of test smells are frequently overlooked in the literature.

In this study, an in vitro experimental system is developed for fifth-generation (5G) 3.5 GHz exposures. A radial transmission line (RTL) housed in an incubator can support the single-mode propagation at a 3.5 GHz band. A conical antenna is also placed at the center of an RTL to ensure field symmetries. A 5G signal generator along with a customized power amplifier can create 5G new radio time division duplex (TDD) waveforms. Additionally, a feedback scheme implemented by employing a directional coupler and power meter allows power control to ensure a steady output power. The system is evaluated based on temperature measurements using the initial temperature slope and nonlinear curve fitting to determine the specific absorption rate (SAR) values. Comparing SARs obtained from a “worst-case” signal of a maximum power condition with the values obtained from a “TDD” signal of an actual 5G TDD transmission gives the initial slope ratio of 0.741, which is very similar to the theoretical duty cycle of 0.743. It is also shown that the average output power, water temperature, incubator air temperature, and CO2 density are adequately controlled for appropriate in vitro experiments.

With new services emerging in fifth generation (5G)-advanced, the evolution in duplex modes plays an important role to meet more stringent requirements for both downlink (DL) and uplink (UL) transmissions. In this paper, sub-band full duplex (SBFD) at base station (BS) is studied as an attainable evolution of the traditional time division duplex (TDD). Both user equipment (UE) transparent SBFD and UE perceptive SBFD are proposed and studied to serve different types of UEs. To tackle the interference introduced by SBFD, a model including both BS self-interference and cross-link interference (CLI) is presented as a first step, and new interference management schemes are proposed. Three approaches to mitigate BS self-interference, namely the passive suppression, analog interference cancellation and digital interference cancellation are analyzed. A new framework for CLI management is illustrated along with enhancements for interference identification, spatial domain interference coordination and power domain adjustment. To validate the feasibility and performance of the proposed SBFD methods under indoor and dense urban scenarios, system-level simulations (SLSs) are carried out and a proof-of-concept (PoC) is developed for the purpose of obtaining experimental results.

Robust, fault tolerant, and available systems are fundamental for the adoption of Internet of Things (IoT) in critical domains, such as finance, health, and safety. The IoT infrastructure is often used to collect a large amount of data to meet the business demands of Smart Cities, Industry 4.0, and Smart Home, but there is a opportunity to use these data to intrinsically monitor an IoT system in an autonomous way. A Test Driven Development (TDD) approach for automatic module assessment for ESP32 and ESP8266 IoT development devices based on unsupervised Machine Learning (ML) is proposed to monitor IoT device status. A framework consisting of business drivers, non-functional requirements, engineering view, dynamic system evaluation, and recommendations phases is proposed to be used with the TDD development tool. The proposal is evaluated in academic and smart home study cases with 25 devices, consisting of 15 different firmware versions collected in one week, with a total of over 550,000 IoT status readings. The K-Means algorithm was applied to free memory available, internal temperature, and Wi-Fi level metrics to automatically monitor the IoT devices under development to identify device constraints violation and provide insights for monitoring frequency configuration of different firmware versions. To the best of the authors' knowledge, it is the first TDD approach for IoT module automatic assessment which uses machine learning based on the real testbed data. The IoT status monitoring and the Python scripts for model training and inference with K-Means algorithm are available under a Creative Commons license. [ABSTRACT FROM AUTHOR]

Future wireless networks will require advance physical-layer techniques to meet the requirements of Internet of Everything (IoE) applications and massive communication systems. To this end, a massive MIMO (m-MIMO) system is to date considered one of the key technologies for future wireless networks. This is due to the capability of m-MIMO to bring a significant improvement in the spectral efficiency and energy efficiency. However, designing an efficient downlink (DL) training sequence for fast channel state information (CSI) estimation, i.e., with limited coherence time, in a frequency division duplex (FDD) m-MIMO system when users exhibit different correlation patterns, i.e., span distinct channel covariance matrices, is to date very challenging. Although advanced iterative algorithms have been developed to address this challenge, they exhibit slow convergence speed and thus deliver high latency and computational complexity. To overcome this challenge, we propose a computationally efficient conjugate gradient-descent (CGD) algorithm based on the Riemannian manifold in order to optimize the DL training sequence at base station (BS), while improving the convergence rate to provide a fast CSI estimation for an FDD m-MIMO system. To this end, the sum rate and the computational complexity performances of the proposed training solution are compared with the state-of-the-art iterative algorithms. The results show that the proposed training solution maximizes the achievable sum rate performance, while delivering a lower overall computational complexity owing to a faster convergence rate in comparison to the state-of-the-art iterative algorithms. [ABSTRACT FROM AUTHOR]

The 5G non-public network deployments for industrial applications are becoming highly interesting for industries and enterprises owing to dependable wireless performance characteristics. With an increasing trend of network deployments in local licensed and/or shared spectrum, coexistence issues naturally arise. In this article, we present our detailed empirical results on the performance impact of a 5G NR indoor non-public network from a 5G NR outdoor network operating in the same mid-band spectrum. We present experimental results on the uplink and downlink performance impact of a non-public indoor network deployed on an industrial shopfloor. Our results quantify the impact on the uplink and downlink performance characteristics based on realistic traffic loads in a non-public indoor network when using synchronized and unsynchronized Time Division Duplex (TDD) patterns, different UE deployment locations and interference levels. We also present results on mitigating interference effects through robust link adaptation techniques. We believe that this is the first article, which reports quantified 5G NR cochannel coexistence results based on a detailed and systematic study, and provides signficant insights on the cochannel coexistence behavior in realistic deployment scenarios of an industrial shopfloor. [ABSTRACT FROM AUTHOR]

Objective: Continuous subcutaneous insulin infusion (CSII) in youths with type 1 diabetes (T1D) is often associated with lower HbA1c, lower total daily insulin dose (TDD), and lower body mass index (BMI) compared with multiple daily injections (MDI). Individual responses to CSII are diverse. The aim was to identify unique three‐variate patterns of HbA1c, BMI standard deviation score (SDS), and TDD after switching to CSII. Methods: Five thousand one hundred and thirty‐three youths (≤20 years; 48% boys; median age at pump start 12.5 years) with T1D duration ≥3 years at CSII initiation were selected from the multicenter DPV registry. We applied group‐based multitrajectory modeling to identify groups of individuals following similar trajectories. Measurements were aggregated quarterly during a 3‐year follow‐up period. Trajectory variables were changes of HbA1c, BMI‐SDS, and TDD from baseline (delta = quarterly aggregated values at each time point [i] minus the respective baseline value). Results: Four groups of diverging Delta‐HbA1c, Delta‐BMI‐SDS, and Delta‐TDD patterns were identified. All showed improvements in HbA1c during the first 3 months. Group 1 (12%) was characterized by modest HbA1c increase thereafter, TDD reduction, and stable BMI‐SDS. In Group 2 (39%), increasing HbA1c, decreasing BMI‐SDS, and stable TDD were found. By contrast, sustainably improved HbA1c, increasing BMI‐SDS, and stable TDD were observed in Group 3 (32%). Group 4 (17%) was characterized by increasing levels for HbA1c, BMI‐SDS, and TDD. Between‐group differences in baseline HbA1c, BMI‐SDS, TDD as well as in sex ratio, age at diabetes onset and at pump start were observed. Conclusions: Definite trajectories of glycemic control, BMI, and TDD over 3 years after CSII initiation were identified in youths with T1D allowing a more personalized treatment recommendation. [ABSTRACT FROM AUTHOR]

Bidirectional electric vehicle supply equipment and charging stations (EVSE) offer new business models and can provide services to the electrical grid. The smart grid lab in Vienna gives unique testing possibilities of future smart grids, as different type of electrical equipment can be operated at a reconstructed, well-known distribution grid. In this work the harmonic and supraharmonic emissions of a bidirectional EVSE are measured according to IEC61000-4-7 and IEC61000-4-30 Ed3 standard as well as the high-frequency grid impedance. In addition, the efficiency and the power factor are determined at various operating points. Although THDi at nominal power (10 kW) is very low and the efficiency and power factor is very high, at low power levels the opposite situation arise. Supraharmonic emissions remain stable independent of the charging/discharging power, and both wideband and narrowband emissions occur. The additional capacitance when connecting the EVSE impacts the high-frequency grid impedance substantially and generates resonance points. [ABSTRACT FROM AUTHOR]

Massive multiple-input multiple-output (MIMO) employs a large antenna array and is used as a key technology in 5G communication standards. In this work, time-division duplex (TDD) is used for uplink (UL) and downlink (DL) channels as the same bandwidth can be utilized for bidirectional data transfer. This paper proposes a computationally efficient adaptive algorithm based channel estimation model. These models are applicable to multiuser MIMO (MU-MIMO) systems, which are comprised of a large number of channel coefficients. Channel state information (CSI) is acquired from estimated channel coefficients of the UL channel, and CSI of DL is obtained through channel reciprocity. The dynamic characteristics of MIMO channels are generally sparse in nature, and the degree of sparseness varies over time. Convex combination-based modeling with the introduction of l0 norm penalty to Least mean squares (LMS) algorithm develops an efficient and stable sparse channel estimation model, which is the most significant contribution of the paper. The research work presented in the paper has simultaneously focused on channel estimation using the convex combination of momentum-fractional LMS approach and equalization for massive MIMO channels. The simulation result exhibits that the proposed method outperforms the existing conventional compressed sensing (CS) based channel estimation. The UL and DL performance of the system was investigated in terms of bit error rate (BER), mean square error (MSE), and channel capacity calculated from estimated CSI. [ABSTRACT FROM AUTHOR]

Technology advances every day because the business world should not be left behind in it, so there is the adoption of new ways of doing business. This is how ICT (Information and Communication Technologies) plays a key role in these new companies converting traditional processes such as bringing your customers through a web converting to e-Commerce, to a digital process. Due to the rise of ICT has been the implementation of electronic billing systems, this type of systems come to stay; improvements are given based on an already predetermined structure, mapping in a better way the taxes and operations of taxpayers. Then, this type of business implies having well-trained IT and accounting staff that allows the online sending of the CPE (electronic receipts). Therefore, this project seeks to improve an internal process in the development phase of the OSE BIZ LINKS that grants validity to electronic receipts, for we will use tools that can be reusable over time, such as Data-Driven Testing, which is a testing technique that has as its pillar two types of data: real data (functional test results) and expected data (results that should have each functional test case), making a comparison of both proceedings to report according to each data compared in this process. [ABSTRACT FROM AUTHOR]

Test-driven development (TDD) is an agile development technology that involves the running of many test cases. The software is likely to be more robust when more test cases are executed in a certain time. For this, it is important to find the combination of number of threads and test cases which can lead to the lowest average running time of a single test case aiming at different computers. It can improve the performance of TDD. Therefore, this paper proposed a method for this problem. First, it tests the three-dimensional raw data in computers with different cores. Second, these data are changed into two-dimensional data after dimensionality reduction. This facilitates the generation of fitting functions. Also, the fitting function of new data waiting for prediction is generated after dimensionality reduction. At last, similarity calculations between the fitting functions of raw and new data are carried out by using Euclidean distance similarity algorithms. Experimental results show that data based on dual-core computer have higher similarities with four new data, such as 81.25%, 100%, 81.25%, and 100%. Thus, the data of dual-core computer have higher reference credibility in predicting the average running time of a single test case of the new data for different computers. In summary, the performance of TDD can be improved after applying the proposed method. [ABSTRACT FROM AUTHOR]

Multiband operation in millimeter wave (mmWave) will obtain lots of performance gain by offering larger bandwidth. However, the prerequisite is the acquisition of accurate channel state information (CSI), which is a knotty task with hybrid analog/digital architecture. This study devotes to efficiently reconstruct and track the time drifting multiband channel to keep CSI precise in time division duplex (TDD) mmWave multiple-input-multiple-output system with hybrid analog/digital architecture. Utilizing spatial reciprocity, an efficient multiband channel reconstruction scheme is introduced, which elaborately estimates the central sub-band channel and then reconstructs side sub-band channels from the central one. To this end, a beam training-based Newtonized orthogonal matching pursuit (BT-NOMP) algorithm is proposed to estimate the central sub-band channel. With the help of frequency-independent parameters extracted from BT-NOMP, side sub-bands channel can be well reconstructed with additional low-complexity path gains estimation process. Furthermore, to avoid frequent channel reconstruction in a slightly drifting channel meanwhile keep the CSI accurate, a rotated beam-based channel tracking algorithm is developed using historical observations of channel parameters. Numerical results prove the efficiency of the proposed multiband channel reconstruction scheme and the accuracy of the channel tracking algorithm. [ABSTRACT FROM AUTHOR]

Massive Multiple Input Multiple Output (MIMO) is an essential component for future wireless cellular networks. One of its biggest advantages is to use the 5G spectrum more intelligently by extending both coverage (via high gain adaptive beamforming) and capacity (via high order spatial multiplexing). In this paper, we evaluate the performance of Time-division duplex (TDD)-based massive MIMO deployment scenario in one of the commercial sites in Turkey. Our experimental results reveal three major contributions: (i) TDD-based massive MIMO in 10 Mhz reveals up to 212% and 50% higher cell throughput compared to Frequency-division duplex (FDD)-based MIMO deployments with 10 Mhz and 20 Mhz respectively. The Downlink (DL) throughput is also observed to be better in mid/far points. (ii) Together with the usage of TDD-based massive MIMO inside the same commercial site, median values of total cell traffic, Uplink (UL) Spectral Efficiency (SE) and DL schedule Transmission Time Interval (TTI) duty cycle have improved 38%, 9% and 14.5% compared to FDD-based MIMO scenario respectively. (iii) Finally, we address some of the challenges of the massive MIMO deployments and the possible trade-offs that can be observed in terms of Radio Resource Control (RRC)-connected User Equipments (UEs), cell throughput, available Sounding Reference Signal (SRS) resources and pairing opportunities provided by massive MIMO.

Abstract Energy-saving for the LTE-A network with relay nodes in TDD mode is addressed in this paper, and integrated sleep scheduling schemes for relay nodes and user devices under a base station are designed. The authors’ two previously proposed ideas, namely, Load-Based Power Saving (LBPS) and Virtual Time, are adopted in the design, and two strategies, namely, top-down and bottom-up each with three LBPS schemes are proposed. In the top-down strategy, the load as well as the channel quality on the backhaul link is first considered to determine the sleep pattern for all relay nodes, and then the sleep schedule for UEs under each relay node is determined accordingly. On the contrary, the load and the channel quality on the access links are first considered and then integrated into the sleep schedule on the backhaul link. Two associated mechanisms for the proposed LBPS schemes to operate in the virtual time domain are also proposed in the paper, i.e., calculation of the virtual subframe capacity and the mapping mechanisms from the virtual time to the actual time. The benefit of the proposed schemes in power saving over the standard-based scheme is demonstrated by the simulation study, and the bottom-up scheme of BU-Split outperforms the other schemes under equally distributed input load as well as the hotspot scenario. Discussion on the tradeoff of the processing overhead and the performance for the proposed schemes is presented in the paper.

To get channel state information (CSI) at a base station (BS), most of researches on massive multiple-input multiple-output (MIMO) systems consider time division duplexing (TDD) to get benefit from the uplink and downlink channel reciprocity. Even in TDD, however, the BS still needs to transmit downlink training signals, which are referred to as channel state information reference signals (CSI-RSs) in the 3GPP standard, to support spatial multiplexing in practice. This is because there are many cases that the number of transmit antennas is less than the number of receive antennas at a user equipment (UE) due to power consumption and circuit complexity issues. Because of this mismatch, uplink sounding reference signals (SRSs) from the UE are not enough for the BS to obtain full downlink MIMO CSI. Therefore, after receiving the downlink CSI-RSs, the UE needs to feedback quantized CSI to the BS using a pre-defined codebook to support spatial multiplexing. In this paper, possible approaches to reconstruct full downlink MIMO CSI at the BS are proposed by exploiting both the SRS and quantized downlink CSI considering practical antenna structures with reduced downlink CSI-RS overhead. Numerical results show that the spectral efficiencies by spatial multiplexing based on the proposed downlink MIMO CSI reconstruction techniques outperform the conventional methods solely based on the quantized CSI. [ABSTRACT FROM AUTHOR]

Hybrid precoding is used in millimeter wave (mmWave) massive multiple-input multiple-output (MIMO) systems instead of full digital precoding to reduce the cost and power consumption. Conventional hybrid precoding however requires complex channel estimation before beamforming. In this paper, we propose a low complexity low-cost channel estimation-free deep direct beamforming method composed of two basic steps-beam impulse and beamforming for time division duplex (TDD). This method is built upon randomized singular value decomposition (RSVD) and can directly complete the process of beamforming. Furthermore, a realistic dataset of mmWave channel-DeepMIMO is adopted to evaluate and determine the practicability of this method. The simulation results demonstrate that the proposed deep direct beamforming achieves high performance while its complexity and power consumption are very low. Compared with other methods without perfect channel status information (CSI), the proposed method costs less and requires lower computational resources while achieves higher spectral efficiency. Furthermore, the RSVD can be easily combined with conventional beamforming methods hence the proposed method is easily extendable to other applications. [ABSTRACT FROM AUTHOR]

A wideband antenna design with double negative metamaterial (DNG) has been designed and evaluated for 4 G and 5 G applications. The antenna design is investigated for wideband operations for 5 G NR (New Radio) n78 band and TDD LTE (Long Term Evolution) bands from LTE band no. 33 to 43. The design is ruled out for size miniaturisation and wide bandwidth using a radiating-folded dipole. The radiating elements can be tuned to adapt to different configurations using controlling parameters. Moreover, the antenna designed is also investigated for SAR, gain, polarisation and efficiency using metamaterial integration. CST microwave studio is used for designing and analysis of the design and the results are validated for the fabricated prototype. The measured and simulated results are in good agreement with each other and proofs to be a good design for 4 G and 5 G communications. [ABSTRACT FROM AUTHOR]

Test-driven development (TDD) is a popular design approach used by the developers with testing being the important software development driving factor. On the other hand, mutation testing is considered one of the most effective testing techniques. However, there is not so much research on combining these two techniques together. In this paper, we propose a novel, hybrid approach called TDD+M which combines test-driven development process together with the mutation approach. The aim was to check whether this modified approach allows the developers to write a better quality code. We verify our approach by conducting a controlled experiment and we show that it achieves better results than the sole TDD technique. The experiment involved 22 computer science students split into eight groups. Four groups (TDD+M) were using our approach, the other four (TDD) – a normal TDD process. We performed a cross-experiment by measuring the code coverage and mutation coverage for each combination (code of group X, tests from group Y). The TDD+M tests achieved better coverage on the code from TDD groups than the TDD tests on their own code (53.3% vs. 33.5% statement coverage and 64.9% vs. 37.5% mutation coverage). The TDD+M tests also found more post-release defects in the TDD code than TDD tests in the TDD+M code. The experiment showed that adding mutation into the TDD process allows the developers to provide better, stronger tests and to write a better quality code. [ABSTRACT FROM AUTHOR]

Software engineering (SE) experiments suffer from threats to validity that may impact their results. Replication allows researchers building on top of previous experiments' weaknesses and increasing the reliability of the findings. Illustrating the benefits of replication to increase the reliability of the findings and uncover moderator variables. We replicate an experiment on test-driven development (TDD) and address some of its threats to validity and those of a previous replication. We compare the replications' results and hypothesize on plausible moderators impacting results. Differences across TDD replications' results might be due to the operationalization of the response variables, the allocation of subjects to treatments, the allowance to work outside the laboratory, the provision of stubs, or the task. Replications allow examining the robustness of the findings, hypothesizing on plausible moderators influencing results, and strengthening the evidence obtained. [ABSTRACT FROM AUTHOR]

Thanks to the digitization and softwarization of radio communication, the development cycle of new radio technologies can be significantly accelerated by prototyping on software-defined radio (SDR) platforms. However, a slow turnaround time (TT) of the front-end of an SDR for switching from receiving mode to transmitting mode or vice versa, are jeopardizing the prototyping of wireless protocols, standards, or systems with stringent latency requirements. In this paper, a novel solution called BaseBand processing unit operating in Half Duplex mode and analog Radio Frequency front-end operating in Full Duplex mode, BBHD-RFFD, is presented to reduce the TT on SDR. A prototype is realized on the widely adopted AD9361 radio frequency frontend to prove the validity of the proposed solution. Experiments unveil that for any type of application, the TT in time division duplex (TDD) operation mode can be reduced to zero by the BBHD-RFFD approach, with negligible impact on the communication system in terms of receiver sensitivity. The impact is measured for an in-house IEEE 802.15.4 compliant transceiver. When compared against the conventional TDD approach, only a 7.5-dB degradation is observed with the BBHD-RFFD approach. The measured sensitivity of -91 dBm is still well above the minimum level (i.e., -85 dBm at 2.4 GHz) defined by the IEEE 802.15.4 standard.

Techniques for quality assurance have to deal with the complexity of software systems and the high probabilities of new errors appearing in any stage of the software life cycle. Software testing is a widely used approach but, due to the costs involved in this process, development teams often debate its applicability in their projects. In the endeavor to reduce the complexity of this process, this study presents an approach for software development based in Test-Driven Development (TDD) supported by Model-Based Testing (MBT) tools to allow automatic test-case generation. The approach, called MoFQA (Model-First Quality Assurance), consists of two main aspects: i) a method to drive software development based on testing techniques which defines steps and recom-mended practices; and, ii) a tool-set to allow clients and stakeholders to model system requirements, testers to create models that represent unit and abstract tests, and transformation tools used to generate executable tests. The tools that MoFQA provides are focusing on web applications. In order to validate the MoFQA tools, two validation experiences are presented.

W artykule przedstawiono jeden z problemów występujących podczas korzystania ze standardu C++14 wraz z biblioteką Google Mock. Na podstawie wprowadzonego problemu omówiono możliwe rozwiązania, a także zaprezentowano poprawiony schemat dla podejścia TDD.

Channel estimation is an essential component, in which channel state information playing very important role in wireless communications. But acquiring CSI in practice is a challenging issue for massive MIMO systems. To reduce the over burden for obtaining channel impulse response of huge Multi input multi output system channel reciprocity in TDD domain is suggested, because the forward link channel data can be derived from the reverse link signal without any feedback involvement. Because of mismatches at uplink, downlink channels maintaining reciprocity in TDD systems is impractical. We study the impact of multiplicative reciprocity error for precoders (Zero forcing, MMSE and MRT) performance along with channel estimation error. In this paper effect of RF mismatches impact on linear precoders is analyzed and simulated in terms of SINR versus SNR under additive white Gaussian noise. [ABSTRACT FROM AUTHOR]

In time-division duplexing (TDD) massive multiple-input multiple-output (MIMO) systems, the reciprocity between the downlink (DL) and the uplink (UL) channels can be utilized to infer the DL channel state information (CSI) with the acquired uplink (UL) CSI. However, the end-to-end UL and DL channel reciprocity are broken when there are mismatches in the radio frequency (RF) analog circuits among different antennas at the base station (BS). Without accurate calibration, there will be severe system performance degradation. This paper studies the internal self-calibration scheme to recover all the unknown full calibration coefficients when different BS antennas are interconnected via hardware transmission lines. On the one hand, we derive the calibration performance for an arbitrary interconnection network in closed-form and obtain closed-form Cramer-Rao lower bound (CRLB) expressions when $(M-1)$ transmission lines are consumed and $M$ denotes the total number of BS antennas. On the other hand, we prove that the star interconnection network is optimal for internal full self-calibration due to its lowest CRLB. Numerical simulation are carried out to verify our theoretical analyses and results. [ABSTRACT FROM AUTHOR]

Competing Interests: Jeffrey A. Klein owns HK Surgical, Inc (a surgical supply and equipment company that develops infiltration pumps that can be used for Tumescent Drug Delivery). Jeffrey A. Klein and Paytra A. Klein have patents regarding Tumescent Drug Delivery.

Using skin patches to deliver drugs is dependable and doesn't have the same issues as permeation enhancers, which help drugs get through the skin but struggle because of the skin's natural barrier. Strategies are required to increase topical bioavailability to enhance drug absorption. Natural compounds offer a promising solution by temporarily reducing skin barrier resistance and improving drug absorption. Natural substances allow a wider variety of medications to be distributed through the stratum corneum, offering a dependable approach to enhancing transdermal drug delivery. Natural substances have distinct advantages as permeability enhancers. They are pharmacologically effective and safe, inactive, non-allergenic, and non-irritating. These characteristics ensure their suitability for use without causing adverse effects. Natural compounds are readily available and well tolerated by the body. Studies investigating the structure-activity relationship of natural chemicals have demonstrated significant enhancer effects. By understanding the connection between chemical composition and enhancer activity, researchers can identify effective natural compounds for improving drug penetration. In conclusion, current research focuses on utilizing natural compounds as permeability enhancers in transdermal therapy systems. These substances offer safety, non-toxicity, pharmacological inactivity, and non-irritation. Through structure-activity relationship investigations, promising advancements have been made in enhancing drug delivery. Using natural compounds holds enormous potential for improving the penetration of trans-dermally delivered medications., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.net.)

In this paper, we propose a method to reuse the cyclic-prefix (CP) intervals of an ongoing OFDM link, by another link, without degrading the OFDM link performance. We label the link that reuses the CP-intervals as CPLink, as they use only the CP-intervals of the ongoing link labeled, MainLink. We leverage the fact that the most commonly used OFDM receivers discard the samples in CP-intervals to design the CPLink that ensures below-noise-floor interference at every MainLink-receiver. The key contribution in this paper is the design and study of zero-knowledge CPLink, in which the CPLink-transmitter ensures below-noise-floor interference at every MainLink-receiver with no knowledge about the locations or the number of MainLink-receivers. We analytically show that the zero-knowledge CPLink capacity is positive. For LTE frame structure with 20-MHz bandwidth and 2-km cell-radius, we evaluate the CPLink for two kinds of CPLink-receivers: full-duplex base-station and a half-duplex device. Even for the cell-edge CPLink-transmitters, full-duplex zero-knowledge CPLink data rates can be up to 20 Mbps (60 Mbps) when the CP duration is ~7% (25%) of the data-symbol duration. The half-duplex CPLink rate is 5–40 Mbps when the CPLink-transmitter is within 250 m of CPLink-receiver. CPLink capacity is found to increase near-linearly with the CP duration, thus mitigating CP overhead. [ABSTRACT FROM AUTHOR]

One of the biggest challenges in operating massive multiple-input multiple-output systems is the acquisition of accurate channel state information at the transmitter. To take up this challenge, time division duplex is more favorable thanks to its channel reciprocity between downlink and uplink. However, while the propagation channel over the air is reciprocal, the radio-frequency front-ends in the transceivers are not. Therefore, calibration is required to compensate the RF hardware asymmetry. Although various over-the-air calibration methods exist to address the above problem, this paper offers a unified representation of these algorithms, providing a higher level view on the calibration problem, and introduces innovations on calibration methods. We present a novel family of calibration methods, based on antenna grouping, which improves accuracy and speeds up the calibration process compared to existing methods. We then provide the Cramér–Rao bound as the performance evaluation benchmark and compare maximum likelihood and least squares estimators. We also differentiate between the coherent and non-coherent accumulation of calibration measurements, and point out that enabling non-coherent accumulation allows the training to be spread in time, minimizing the impact to the data service. Overall, these results have special value in allowing the design of reciprocity calibration techniques that are both accurate and resource-effective. [ABSTRACT FROM AUTHOR]

In this study, the scaling laws of optimal training lengths were investigated for time-division duplexing massive multiple-input multiple-output systems. First, the generalized asymptotic achievable rate was derived by taking into account both uplink and downlink training. From the general form, the achievable rates of zero-forcing (ZF) and matched filter (MF) precoders are directly obtained by using the mean and variance of the effective channel. Then, we analyzed the rate gaps of ZF and MF with respect to uplink and downlink training, respectively. According to the analysis of rate gaps, it is shown that the achievable rates are more dominated by the uplink training than downlink training for both ZF and MF. The joint optimization problem for training lengths maximizing the spectral efficiency is formulated as a function of rate gaps. To study the scaling of optimal training lengths with the system parameters, we derived the optimal training lengths as a closed-form expression by using an approximation for the logarithm function. From the analysis, it is shown that the optimal training lengths decrease as the number of antennas increases, and increase as the coherence block length increases. In addition, the optimal training lengths increase as the transmit power increases for ZF, whereas it does not change for MF. Finally, we investigated the superior region for noncoherent detection (which means only statistical information is used for demodulation without downlink training) with the system parameters by comparing the spectral efficiency with and without downlink training. [ABSTRACT FROM AUTHOR]

Purpose: To report embolization of the thoracic duct by direct injection of N-butyl-2-cyanoacrylate (NBCA) glue via a puncture needle.Materials and Methods: Two cases of high output chylothorax were successfully treated with direct injection of N-butyl-2-cyanoacrylate (NBCA) glue via a puncture needle. In them, conventional thoracic duct embolization (TDE) was attempted, but the cisterna chyli was absent on intranodal lymphangiography, and probably for this reason catheterization of the thoracic duct was unsuccessful. Contrast material injection via a puncture needle, however, clearly showed a leak from the thoracic duct, prompting us to attempt embolization of the thoracic duct by direct injection of NBCA glue via the needle.Results: Thoracic duct embolization by direct injection of NBCA glue via a puncture needle was technically successful in both patients. No minor or major complication occurred. Both patients disappeared chylothorax after this treatment.Conclusion: This embolization method can be useful for treatment of chylothorax when conventional TDE is not achievable. [ABSTRACT FROM AUTHOR]

Downlink beamforming in Massive multiple-input and multiple-output (MIMO) either relies on uplink pilot measurements—exploiting reciprocity and time-division duplexing operation, or on the use of a predetermined grid of beams with user equipments reporting their preferred beams, mostly in frequency-division duplexing operation. Massive MIMO in its originally conceived form uses the first strategy, with uplink pilots, whereas there is currently significant commercial interest in the second, grid-of-beams. It has been analytically shown that with isotropic scattering (independent Rayleigh fading) the first approach outperforms the second. Nevertheless, there remains controversy regarding their relative performance in practical channels. In this contribution, the performances of these two strategies are compared using measured channel data at 2.6 GHz. [ABSTRACT FROM PUBLISHER]

A single junction gallium arsenide (GaAs) solar cell on silicon (Si) substrate with energy conversion efficiency of 11.88% under the AM1.5 G spectrum at 1 sun intensity without an anti-reflection coating (ARC) has been developed. This development was enabled by utilizing an intermediate, thin arsenic-doped germanium (As-doped Ge) buffer layer. The thin epitaxial Ge layer (< 2 µm) grown on the Si substrate created a virtual Ge-on-Si (Ge/Si) substrate for subsequent growth of the GaAs solar cell, providing low threading dislocation density (TDD) of < 5 × 10 6 cm −2 . The energy conversion efficiency could be further improved to 16% upon optimizing the ARC and metal coverage. Hence, a manufacturable III-V photovoltaic on a large-area Si substrate has become possible. [ABSTRACT FROM AUTHOR]

Future multi-input multi-output (MIMO) wireless communications systems will use beamforming as a first-step towards realizing the capacity requirements necessitated by the exponential increase in data demands. The focus of this work is on beam alignment for time-division duplexing (TDD) systems, for which we propose a number of novel algorithms. These algorithms seek to obtain good estimates of the optimal beamformer/combiner pair (which are the dominant singular vectors of the channel matrix). They are motivated by the power method, an iterative algorithm to determine eigenvalues and eigenvectors through repeated matrix multiplication. In contrast to the basic power method which considers only the most recent iteration and assumes noiseless links, the proposed techniques consider information from all the previous iterations of the algorithm and combine them in different ways. The first technique (Sequential Least-Squares method) sequentially constructs a least-squares estimate of the channel matrix, which is then used to calculate the beamformer/combiner pair estimate. The second technique (Summed Power method) aims to mitigate the effect of noise by using a linear combination of the previously tried beams to calculate the next beam, providing improved performance in the low-SNR regime (typical for mmWave systems) with minimal complexity/feedback overhead. A third technique (Least-Squares Initialized Summed Power method ) combines the good performance of the first technique at the high-SNR regime with the low-complexity advantage of the second technique by priming the summed power method with initial estimates from the sequential method. [ABSTRACT FROM PUBLISHER]

We study an uplink scenario of single-cell multi-user massive multiple-input multiple-output (mMIMO) communication systems with a semi-orthogonal multiple-access (SOMA), where the channel state information is acquired by transmitting uplink pilot signals superimposed on uplink data signals. We analytically find the optimal resource allocation parameters; e.g., pilot and data transmit power and training duration, which maximize achievable sum-rates by minimum mean-square error (MMSE) channel estimation and maximum ratio combining (MRC) for data detection. Our results indicate that the optimized SOMA encouragingly outperforms the optimized conventional time-division duplex protocol in terms of both energy- and spectral efficiency. [ABSTRACT FROM PUBLISHER]