Backward Compatibility Research Articles

A Reinforcement Learning Handover Parameter Adaptation Method Based on LSTM-Aided Digital Twin for UDN.

Adaptation of handover parameters in ultra-dense networks has always been one of the key issues in optimizing network performance. Aiming at the optimization goal of effective handover ratio, this paper proposes a deep Q-learning (DQN) method that dynamically selects handover parameters according to wireless signal fading conditions. This approach seeks good backward compatibility. In order to enhance the efficiency and performance of the DQN method, Long Short Term Memory (LSTM) is used to build a digital twin and assist the DQN algorithm to achieve a more efficient search. Simulation experiments prove that the enhanced method has a faster convergence speed than the ordinary DQN method, and at the same time, achieves an average effective handover ratio increase of 2.7%. Moreover, in different wireless signal fading intervals, the method proposed in this paper has achieved better performance.

Movement-Based Reliable Mobility Management for Beyond 5G Cellular Networks

Extreme mobility becomes a norm rather than an exception with emergent high-speed rails, drones, industrial IoT, and many more. However, 4G/5G mobility management is not always reliable in extreme mobility, with non-negligible failures and policy conflicts. The root cause is that, existing mobility management is primarily based on wireless signal strength. While reasonable in static and low mobility, it is vulnerable to dramatic wireless dynamics from extreme mobility in triggering, decision, and execution. We devise <monospace xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">REM</monospace> , Reliable Extreme Mobility management for beyond 5G cellular networks while maintaining backward compatibility to 4G/5G. <monospace xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">REM</monospace> shifts to movement-based mobility management in the delay-Doppler domain. Its signaling overlay relaxes feedback via cross-band estimation, simplifies policies with provable conflict freedom, and stabilizes signaling via scheduling-based OTFS modulation. Our evaluation with operational high-speed rail datasets shows that, <monospace xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">REM</monospace> reduces failures comparable to static and low mobility, with low signaling and latency cost. <monospace xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">REM</monospace> reduces the network failures by up to an order of magnitude, eliminates policy conflicts, and improves application performance by 31.8% - 88.3% compared to legacy 4G/5G.

A Simple Solution for the General Fractional Ambartsumian Equation

Fractionalisation and solution of the Ambartsumian equation is considered. The general approach to fractional calculus suitable for applications in physics and engineering is described. It is shown that Liouville-type derivatives are the necessary ones, because they fully preserve backward compatibility with classical results. Such derivatives are used to define and solve the fractional Ambartsumian equation. First, a solution in terms of a slowly convergent fractional Taylor series is obtained. Then, a simple solution expressed in terms of an infinite linear combination of Mittag–Leffler functions is deduced. A fast algorithm, based on a bilinear transformation and using the fast Fourier transform, is described and demonstrated for its approximate numerical realisation.

Is sized typing for Coq practical?

Abstract Contemporary proof assistants such as Coq require that recursive functions be terminating and corecursive functions be productive to maintain logical consistency of their type theories, and some ensure these properties using syntactic checks. However, being syntactic, they are inherently delicate and restrictive, preventing users from easily writing obviously terminating or productive functions at their whim. Meanwhile, there exist many sized type theories that perform type-based termination and productivity checking, including theories based on the Calculus of (Co)Inductive Constructions (CIC), the core calculus underlying Coq. These theories are more robust and compositional in comparison. So why haven’t they been adapted to Coq? In this paper, we venture to answer this question with CIC $\widehat{\ast}$ , a sized type theory based on CIC. It extends past work on sized types in CIC with additional Coq features such as global and local definitions. We also present a corresponding size inference algorithm and implement it within Coq’s kernel; for maximal backward compatibility with existing Coq developments, it requires no additional annotations from the user. In our evaluation of the implementation, we find a severe performance degradation when compiling parts of the Coq standard library, inherent to the algorithm itself. We conclude that if we wish to maintain backward compatibility, using size inference as a replacement for syntactic checking is impractical in terms of performance.

CNN Sensor Analytics With Hybrid-Float6 Quantization on Low-Power Embedded FPGAs

The use of artificial intelligence (AI) in sensor analytics is entering a new era based on the use of ubiquitous embedded connected devices. This transformation requires the adoption of design techniques that reconcile accurate results with sustainable system architectures. As such, improving the efficiency of AI hardware engines as well as backward compatibility must be considered. In this paper, we present the Hybrid-Float6 (HF6) quantization and its dedicated hardware design. We propose an optimized multiply-accumulate (MAC) hardware by reducing the mantissa multiplication to a multiplexor-adder operation. We exploit the intrinsic error tolerance of neural networks to further reduce the hardware design with approximation. To preserve model accuracy, we present a quantization-aware training (QAT) method, which in some cases improves accuracy. We demonstrate this concept in 2D convolution layers. We present a lightweight tensor processor (TP) implementing a pipelined vector dot-product. For compatibility and portability, the 6-bit floating-point (FP) is wrapped in the standard FP format, which is automatically extracted by the proposed hardware. The hardware/software architecture is compatible with TensorFlow (TF) Lite. We evaluate the applicability of our approach with a CNN-regression model for anomaly localization in a structural health monitoring (SHM) application based on acoustic emission (AE). The embedded hardware/software framework is demonstrated on XC7Z007S as the smallest Zynq-7000 SoC. The proposed implementation achieves a peak power efficiency and run-time acceleration of 5.7 GFLOPS/s/W and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$48.3\times $ </tex-math></inline-formula> , respectively.

Demonstrating Intra-Spacecraft Optical Wireless Links

In a Spacecraft (SC), a huge amount of cabled electrical connections is needed by many different units to exchange digital data. This increases the overall mass, the space occupancy, and the routing design time. Here, we propose and demonstrate an Optical Wireless Communication (OWC) system that can perfectly replace the MIL-STD-1553B cables inside the SC, providing wireless communication among the satellite units, with full backward compatibility with pre-existing units and protocols. We present the experimental demonstration in the challenging environment of a populated mockup of a real SC, where we connect four different units and exploit the Non Line-of-Sight (NLOS) configuration, i.e. take advantage of the scattering from the walls to overcome the shadowing effects. This OWC technique can effectively reduce the overall weight (more than 50%) and cost of the SC data network. The proposed transceivers are based on a transparent, fully analog solution and are made of Commercial Off-the-Shelf (COTS) components, with features compatible with the space environment. The on-field experiment shows that this is a practical solution for the data networks in future SCs.

Throughput Enhancement of Dynamic Full-Duplex Cellular System by Distributing Base Station Reception Function

In-band full-duplex (IBFD) is a promising technology for improving spectral efficiency beyond 5G and 6G. The dynamic duplex cellular (DDC) system has been proposed as a method for the phased introduction of IBFD into cellular systems while maintaining backward compatibility. Although previous studies have shown that DDC systems can improve the average user throughput, twice the spectral efficiency compared to half-duplex (HD), ideally expected for IBFD, has not been achieved. The main component that disturbs throughput enhancement is the residual component of self-interference (SI) at the base station (BS), which SI cancellers cannot entirely suppress. In this study, we propose a DDC system with a dedicated transmitter (DT) and multiple distributed receivers called remote receivers (RRs) for the BS to reduce the effective SI and enhance uplink reception quality. We implement user equipment scheduling and power control for the DDC system in the topology with DT and multiple RRs and improvement by IBFD. evaluate its performance using computer simulations in a single-cell environment. The proposed DDC system with receiver-distributed topology achieves up to 96% improvement in average user throughput of uplink and downlink from the HD system with the same topology, which is close to the ideal performance.

Implementation of a Digitally Controlled MOS based Tuned Reconfigurable Filter for High Frequency Applications

ith the advent of recent standard of high data rate communication standards, the systems need to meet the requirement of multi-frequency processing. Moreover to achieve backward and forward compatibility across communication standards, reconfigurable and tunable designs are preferred. This paper proposes a fully digital reconfigurable all pass filter (APF) with a tunable passband to meet such requirements. The reconfigurable APF is capable of band tuning using a digital current control source (DCCS) which uses a digital word count making it most effective and simple reconfigurable design than the already reported designs. This can be widely used in different systems, e.g., 5G receivers, radar communication, cyber security, sensor interfaces, etc. This APF is also connected to Schmitt trigger inverter for smooth communication. Moreover, the circuit is designed to be inductor less thus making the design area efficient and suitable for wide range of applications and systems. The proposed design is simulated using 65 nm GPDK CMOS technology that achieves a wideband range of 0.1-15 GHz and achieves a bandwidth of 12.6 GHz with a gain of 15.5dB with a time delay of 1.62ps. The static power consumption of the circuit is only 2.52mW.

Stateful Logic Using Phase Change Memory

Stateful logic is a digital processing-in-memory (PIM) technique that could address von Neumann memory bottleneck challenges while maintaining backward compatibility with standard von Neumann architectures. In stateful logic, memory cells are used to perform the logic operations without reading or moving any data outside the memory array. Stateful logic has been previously demonstrated using several resistive memory types, mostly resistive RAM (RRAM). Here, we present a new method to design stateful logic using a different resistive memory-phase change memory (PCM). We propose and experimentally demonstrate four logic gate types (NOR, IMPLY, OR, NIMP) using commonly used PCM materials. Our stateful logic circuits are different than previously proposed circuits due to the different switching mechanisms and functionality of PCM compared to RRAM. Since the proposed stateful logic forms a functionally complete set, these gates enable the sequential execution of any logic function within the memory, paving the way to PCM-based digital PIM systems.

Don’t Look Back? Backward Compatibility in the Video Gaming Industry

Backward compatibility is a governance strategy that can be adopted by platform owners to build indirect network effects and encourage owners of older compatible software to update to newer hardware models. Previous research shows backward compatibility has a positive effect on hardware sales. However, there is limited evidence concerning the other associated costs and benefits. In particular, there is a lack of evidence on the effect of backward compatibility on software sales despite its importance in understanding the full range of possible network and sales displacement effects associated with the strategy. Using weekly software-level sales data from the U.S. video gaming industry, we find that backward-compatible hardware associates with increased sales of software released for the previous hardware generation. However, we find that the introduction of backward compatibility may not increase the sales of new hardware if the feature is not available immediately at launch. Further, we show that the increased sales of software for the old hardware platform may cannibalize software sales for the new platform. Overall, our results suggest that backward compatibility is time-sensitive and involves several important trade-offs. We, therefore, conclude that the use of backward compatibility needs to be carefully considered by platform owners prior to implementation.

TAUOLA update for decay channels with e+e− pairs in the final state

With the arrival of high luminosity B-factories like the Belle II experiment, τ decay measurements have become more precise than ever, allowing rarer processes to be explored, and finer details of τ decays to be studied. These are important to understand the spectrum of intermediate particles produced in τ decays. Therefore Monte Carlo generators, like the TAUOLA program, have to facilitate precision analysis as well as confront new models that constantly emerge with the availability of high statistics experimental data. New decay channels and models may lead to large variation of matrix elements size within the available phase space, as in the case when e+e− pairs are present in final state. It requires appropriate presampler of the phase space generator and a proper documentation to help users introduce their own models. While releasing a new update, it is important for the TAUOLA Monte Carlo library to maintain the general structure of the previous versions to preserve backward compatibility. The aim is to minimize changes from the user perspective. This paper presents a demonstration of new models implementation facilitated by the current update. Program summaryProgram Title: tauola-bbbCPC Library link to program files:https://doi.org/10.17632/3hyw3f7v32.1Licensing provisions: GPLv2Programming language:FORTRAN/C++Journal reference of previous version: Comput. Phys. Comm., 232:220–236, 2018Does the new version supersede the previous version?: NoReasons for the new version: Meeting the needs of present day experiments.Summary of revisions: Phase space presamplers enriched with the possibility to generate narrow peaks of e+e− pairs, if present in matrix elements of 4- and 5-body decay channels and due to electromagnetic or New Physics interactions. The examples of physical models are implemented for: τ−→π−e−e+ντ, τ−→ν¯μμ−e−e+ντ and τ−→ν¯ee−e−e+ντ channels, which are used for the collected new algorithm validations.Nature of problem: Present day experiments, in particular Belle II, have the capability to measure extremely rare, not yet measured τ decays, as well as precise measurements of known decay channels. They require a Monte Carlo generator capable of generating all desired decays. They also need the possibility to modify and test new models for such decays. At the same time the default initialization of the event generator should contain decent modeling of known τ decays.Solution method: The new version supplements previous publications on TAUOLA. Phase-space presamplers and new decay channels with additional light lepton pairs are introduced.Additional comments including restrictions and unusual features: TAR BALL of the future versions of the program may become available through:http://wasm.web.cern.ch/wasm/Welcome.html; its sub-pages http://tauolapp.web.cern.ch/tauolapp/ or http://wasm.web.cern.ch/wasm/f77.html

Comparative study for evaluating the cost efficiency of 5G Ethernet mobile fronthaul networks

With the advances in mobile network technologies, the fronthaul is being evolved to centralized and cloud networks, leading to the emergence of various optical multiplexing architectures. Among others, the Ethernet-based packet switching network is considered one of the most promising concepts due to the inherent merits of Ethernet such as backward compatibility, high reliability, and cost reduction. This work aims at evaluating the Ethernet-based mobile fronthaul network by comparing it with other configuration options. In particular, we calculate and compare the total cost of ownership (TCO) in order to emphasize the cost efficiency of the 5G Ethernet fronthaul network. For this, we analyze the packet aggregation capabilities of the Ethernet fronthaul through queueing latency modeling. Hence, we show that the statistical multiplexing enabled by packet switching reduces the cost related to optical transceiver modules and subsequently fiber optic cabling, which eventually allows for the TCO to be less than 70% of the active transparent system.

A large‐scale empirical study of low‐level function use in Ethereum smart contracts and automated replacement

AbstractThe Ethereum blockchain stores and executes complex logic via smart contracts written in Solidity, a high‐level programming language. The Solidity language (in its early versions) provides features to exercise fine‐grained control over smart contracts, whose usage is discouraged by later‐released Solidity documentation, but nonetheless supported in later versions for backward compatibility. We define these features as low‐level functions. However, the high‐volume of transactions and the improper use of low‐level functions lead to security exploits with heavy financial loss. Consequently, the documentation suggests secure alternatives to the use of low‐level functions. In this article, we first perform an empirical study on the use of low‐level functions in Ethereum smart contracts. We study a smart contract dataset consisting of over 2,100,000 real‐world smart contracts. We find that low‐level functions are widely used and that the majority of these uses are gratuitous. We then propose GoHigh, a source‐to‐source transformation tool to eliminate low‐level function‐related vulnerabilities, by replacing low‐level functions with secure alternatives. Our experimental evaluation on the dataset shows that GoHigh successfully replaces all low‐level functions with 4.9% fewer compiler warnings. Further, no unintended side‐effects are introduced in 80% of the contracts, and the remaining 20% are not verifiable due to their external dependency. GoHigh saves more than 5% of the gas cost of the contract. Finally, GoHigh takes 7 s on average per contract.

Integration and commissioning of the ATLAS Tile Demonstrator Module for Run 3

The electronics of the Tile Calorimeter at the ATLAS experiment will be replaced for the HL-LHC. The TileCal Phase-II upgrade project has undertaken an extensive R&D program. A Demonstrator module containing the upgraded on-detector readout electronics was built in 2014, evaluated in seven test beam campaigns, and inserted into one of the Tile Calorimeter modules at the ATLAS experiment in 2019. The module also provides backward compatibility of the Demonstrator module with the present ATLAS systems. We present the current status and test results from the Demonstrator module currently running at ATLAS.

Research on the design and verification of the charging compatibility for electric vehicle ChaoJi charging

The international mainstream DC charging systems CHAdeMO 2.0 in Japan, GB/T 2015 in China, CCS1/CCS2 in Europe, and the U.S. have different control pilot circuit and the coupler designs. Control pilot circuit is an important component of the electric vehicle (EV) charging system and is used to monitor the function of the interaction between the EV and the electric vehicle supply equipment (EVSE). Existing system designs can make the difficult to achieve the compatibility between different charging systems, and reduce the user experience. This study first analyzes the practical applications of four existing mainstream DC charging systems. There are certain defects in structural design, safety, compatibility, and control pilot function, the introduction of a new generation of ChaoJi charging technology will change all these. Meanwhile the vehicle adapter design solution can perfectly solve the problem of physical compatibility between the existing charging system and ChaoJi vehicle. In addition, a new control pilot circuit design is proposed, to identify normal charging and abnormal states by hard node signals and states switches. By building a test environment, this new control pilot circuit has proven to its excellent characteristics in terms of fault monitoring, backward compatibility, and future-proof applications. ChaoJi charging technology has been adopted by CHAdeMO 3.0, laying the foundation for a globally harmonized charging system.

Extending the Heat Index

Abstract The heat index is a widely used measure of apparent temperature that accounts for the effects of humidity using Steadman’s model of human thermoregulation. Steadman’s model, however, gives unphysical results when the air is too hot and humid or too cold and dry, leading to an undefined heat index. For example, at a relative humidity of 80%, the heat index is only defined for temperatures in the range of 288–304 K (59°–88°F). Here, Steadman’s thermoregulation model is extended to define the heat index for all combinations of temperature and humidity, allowing for an assessment of Earth’s future habitability. The extended heat index can be mapped onto physiological responses of an idealized human, such as heat exhaustion, heat stroke, and even heat death, providing an indication of regional health outcomes for different degrees of global warming. Significance Statement The existing heat index is well-defined for most combinations of high temperature and humidity experienced on Earth in the preindustrial climate, but global warming is increasingly generating conditions for which the heat index is undefined. Therefore, an extension of the original heat index is needed. When extending the heat index, we use the same physiological model as in the original work of Steadman to ensure backward compatibility. Following Steadman, each value of the heat index is mapped onto a measurable physiological variable, which can be useful for assessing the health impacts of various combinations of temperature and humidity, especially for outdoor workers.

Dependency Smells in JavaScript Projects

Dependency management in modern software development poses many challenges for developers who wish to stay up to date with the latest features and fixes whilst ensuring backwards compatibility. Project maintainers have opted for varied, and sometimes conflicting, approaches for maintaining their dependencies. Opting for unsuitable approaches can introduce bugs and vulnerabilities into the project, introduce breaking changes, cause extraneous installations, and reduce dependency understandability, making it harder for others to contribute effectively. In this paper, we empirically examine evidence of recurring dependency management issues (dependency smells). We look at the commit data for a dataset of 1,146 active JavaScript repositories to catalog, quantify and understand dependency smells. Through a series of surveys with practitioners, we identify and quantify seven dependency smells with varying degrees of popularity and investigate why they are introduced throughout project history. Our findings indicate that dependency smells are prevalent in JavaScript projects with two or more distinct smells appearing in 80 percent of the projects, but they generally infect a minority of a project’s dependencies. Our observations show that the number of dependency smells tend to increase over time. Practitioners agree that dependency smells bring about many problems including security threats, bugs, dependency breakage, runtime errors, and other maintenance issues. These smells are generally introduced as developers react to dependency misbehaviour and the shortcomings of the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">npm</i> ecosystem.

A comparison of bone age assessments using automated and manual methods in children of Indian ethnicity.

Bone age is useful for pediatric endocrinologists in evaluating various disorders related to growth and puberty. Traditional methods of bone age assessment, namely Greulich and Pyle (GP) and Tanner-Whitehouse (TW), have intra- and interobserver variations. Use of computer-automated methods like BoneXpert might overcome these subjective variations. The aim of our study was to assess the validity of BoneXpert in comparison to manual GP and TW methods for assessing bone age in children of Asian Indian ethnicity. We extracted from a previous study the deidentified left hand radiographs of 920 healthy children aged 2-19 years. We compared bone age as determined by four well-trained manual raters using GP and TW methods with the BoneXpert ratings. We computed accuracy using root mean square error (RMSE) to assess how close the bone age estimated by BoneXpert was to the reference rating. The standard deviations (SDs) of rating among the four manual raters were 0.52 years, 0.52 years and 0.47 years for GP, TW2 and TW3 methods, respectively. The RMSEs between the automated bone age estimates and the true ratings were 0.39 years, 0.41 years and 0.36 years, respectively, for the same methods. The RMSE values were significantly lower in girls than in boys (0.53, 0.5 and 0.47 vs. 0.39, 0.47 and 0.4) by all the methods; however, no such difference was noted in classification by body mass index. The best agreement between BoneXpert and manual rating was obtained by using 50% weight on carpals (GP50). The carpal bone age was retarded in Indian children, more so in boys. BoneXpert was accurate and performed well in estimating bone age by both GP and TW methods in healthy Asian Indian children; the error was larger in boys. The GP50 establishes "backward compatibility" with manual rating.

Software quality and backward compatibility in the video game industry

Software quality and backward compatibility in the video game industry

Vehicular Wireless Communication Standards

Autonomous vehicles (AVs) are the future of mobility. Safe and reliable AVs are required for widespread adoption by a community which is only possible if these AVs can communicate with each other &amp;amp; with other entities in a highly efficient way. AVs require ultra-reliable communications for safety-critical applications to ensure safe driving. Existing vehicular communication standards, i.e., IEEE 802.11p (DSRC), ITS-G5, &amp;amp; LTE, etc., do not meet the requirements of high throughput, ultra-high reliability, and ultra-low latency along with other issues. To address these challenges, IEEE 802.11bd &amp;amp; 5G NR-V2X standards provide more efficient and reliable communication, however, these standards are in the developing stage. Existing literature generally discusses the features of these standards only and does not discuss the drawbacks. Similarly, existing literature does not discuss the comparison between these standards or discusses a comparison between any two standards only. However, this work comprehensively describes different issues/challenges faced by these standards. This work also comprehensively provides a comparison among these standards along with their salient features. The work also describes spectrum management issues comprehensively, i.e., interoperability issues, co-existence with Wi-Fi, etc. The work also describes different other issues comprehensively along with recommendations. The work describes that 802.11bd and 5G NR are the two potential future standards for efficient vehicle communications; however, these standards must be able to provide backward compatibility, interoperability, and co-existence with current and previous standards.