Interference Avoidance Research Articles

Proposal of Interference Avoidance Method for Generating Ball End-mill Tip Groove Grinding Path

Proposal of Interference Avoidance Method for Generating Ball End-mill Tip Groove Grinding Path

Interference Avoidance through Periodic UAV Scheduling in RIS-Aided UAV Cluster Communications

This article investigates the transmission of downlink control signals for multiple unmanned aerial vehicle (UAV) clusters in collaborative search and rescue operations in mountainous environments. In this scenario, a reconfigurable intelligent surface (RIS) mounted on the UAV is utilized to overcome obstacles between the ground base station (BS) and UAVs. By leveraging the fixed channel of the RIS to the BS, the line-of-sight (LoS) path characteristics of the air-to-air channel, and the position information of the UAV, the RIS forms a directional beam by adjusting the RIS coefficient, which points towards UAVs in the cluster. To ensure low delay in control signaling and UAV state transmission, we adopt semi-persistent scheduling (SPS), which allocates pre-specified periodic intervals to each UAV for the formation of corresponding RIS coefficients. The allocation of time slots is constrained by the transmission intervals required by different UAVs and the number of RISs available. We propose a time slot scheduling scheme for UAVs to reduce inter-cluster interference caused by RIS beams. The time slot allocation problem is formulated as a combinatorial optimization problem. To solve this problem, we first propose an intuitive greedy scheme called local interference minimization (LIM). Building upon the LIM scheme, we propose a rollout-based algorithm called rollout interference minimization (RIM). Through simulation, we compare the LIM and RIM schemes with the benchmark scheduling scheme. The results demonstrate that our proposed scheme significantly reduces interference between UAV clusters while satisfying the conditions of periodic transmission and RIS quantity constraints.

Downlink Power Allocation for CR-NOMA-Based Femtocell D2D Using Greedy Asynchronous Distributed Interference Avoidance Algorithm

This paper focuses on downlink power allocation for a cognitive radio-based non-orthogonal multiple access (CR-NOMA) system in a femtocell environment involving device-to-device (D2D) communication. The proposed power allocation scheme employs the greedy asynchronous distributed interference avoidance (GADIA) algorithm. This research aims to optimize the power allocation in the downlink transmission, considering the unique characteristics of the CR-NOMA-based femtocell D2D system. The GADIA algorithm is utilized to mitigate interference and effectively optimize power allocation across the network. This research uses a fairness index to present a novel fairness-constrained power allocation algorithm for a downlink non-orthogonal multiple access (NOMA) system. Through extensive simulations, the maximum rate under fairness (MRF) algorithm is shown to optimize system performance while maintaining fairness among users effectively. The fairness index is demonstrated to be adaptable to various user counts, offering a specified range with excellent responsiveness. The implementation of the GADIA algorithm exhibits promising results for sub-optimal frequency band distribution within the network. Mathematical models evaluated in MATLAB further confirm the superiority of CR-NOMA over optimum power allocation NOMA (OPA) and fixed power allocation NOMA (FPA) techniques.

Fusion of Centroid-Based Clustering With Graph Clustering: An Expectation-Maximization-Based Hybrid Clustering.

This article extends the expectation-maximization (EM) formulation for the Gaussian mixture model (GMM) with a novel weighted dissimilarity loss. This extension results in the fusion of two different clustering methods, namely, centroid-based clustering and graph clustering in the same framework in order to leverage their advantages. The fusion of centroid-based clustering and graph clustering results in a simple "soft" asynchronous hybrid clustering method. The proposed algorithm may start as a pure centroid-based clustering algorithm (e.g., k -means), and as the time evolves, it may eventually and gradually turn into a pure graph clustering algorithm [e.g., basic greedy asynchronous distributed interference avoidance (GADIA) (Babadi and Tarokh, 2010)] as the algorithm converges and vice versa. The "hard" version of the proposed hybrid algorithm includes the standard Hopfield neural networks (and, thus, Bruck's Ln algorithm by (Bruck, 1990) and the Ising model in statistical mechanics), Babadi and Tarokh's basic GADIA in 2010, and the standard k -means (Steinhaus, 1956), (MacQueen, 1967) [i.e., the Lloyd algorithm (Lloyd, 1957, 1982)] as its special cases. We call the "hard version" of the proposed clustering as "hybrid-nongreedy asynchronous clustering (H-NAC)." We apply the H-NAC to various clustering problems using well-known benchmark datasets. The computer simulations confirm the superior performance of the H-NAC compared to the k -means clustering, k -GADIA, spectral clustering, and a very recent clustering algorithm structured graph learning (SGL) by Kang et al. (2021), which represents one of the state-of-the-art clustering algorithms.

Multi-channel Scheduling with Interference Avoidance and Precedence Based Algorithm in Wireless Mesh Networks

Wireless Mesh Networks (WMNs) is the wireless networking domain that has been preferentially attracted by many researchers. Multi radio and multichannel WMN has limited channels due to the constraints given by interferences caused internally and externally within the channels. The research is focused on maximizing the performance in multi radio and multi channel WMNs. The channel overlapping that happens partially can overcome this limitation of resources. Interference Avoidance and Precedence Based Algorithm(IAPB) is proposed to reduce the interferences that occur in WMNs and improve the performance.The interference involved during the usage of channels can be reduced by using the channels with less interference. The interference involved is reduced by consideration of precedence level of interference during assignment of channel. The proposed algorithm results in performance improvement in terms of network throughput, the packet loss, delay involved in the reduction of interference.

Co-frequency interference analysis and avoidance between NGSO constellations: Challenges, techniques, and trends

Co-frequency interference analysis and avoidance between NGSO constellations: Challenges, techniques, and trends

Empowering Visually Impaired through the Assistance of SAHAYAK – A Walking Aid for the Blind

To help blind people overcoming difficulty in their movement in the physical environment and even in their home, a study on an engineering concept is very much necessary. So, our research comes out with an aid that will help blind people in their surroundings. It can detect any obstacle that will block the path of the blind. And The motion of the user can be sensed by the bot. Thus, Blind people can comfortably receive the help of our bot in assisting their movement from one place to another. This paper describes about an automated vehicle which can be controlled by an ultrasonic sensor to avoid obstacles when they move in their environment. Our automated robotic system is made up of an ultrasonic sensor and Arduino micro controller controls our automated bot. It is located in the front part of the bot. The ultrasonic sensor retrieves the data from the environment through the sensors attached to the bot. When any obstacle is detected then immediately that path is changed and an obstacle free path is chosen. The bot wheel is moved based on the data received by the controller from the sensor. The direction and wheel movement of the bot and will be decided from the ultrasonic sensor sensing and also using wheel encoder. It is used for detection and avoidance of interference. The controller is also programmed to be used with an android application.

Minimum Friction Coefficient-Based Precision Manipulation Workspace Analysis of the Three-Fingered Metamorphic Hand

Abstract Reconfigurable robotic hands can constitute one of the future trends of dexterous manipulator design, as they can strike a balance between precision, force exertion, flexibility, and adaptability. However, the feasible manipulation workspace of a reconfigurable robotic hand, the metamorphic hand, is complex as the finger operation planes alter with the reconfigurable palm’s motions. Different useful workspace approaches and grasp quality metrics have been introduced, but a precision manipulation workspace (PMW) approach for reconfigurable robotic hands has yet to be presented. This paper presents a hand workspace taxonomy based on previous studies, and a new approach to obtaining a PMW of a robotic hand which satisfies three properties: force closure, singularity avoidance, and interference avoidance. A grasp quality metric, termed the minimum friction coefficient (MFC), is introduced to indicate the force-closure conditions of a robotic hand’s configurations. Unlike the previous grasp quality metrics targeting online grasp-planning tasks, this MFC-based measure focuses on the offline design of robotic hands. This method is essential for conducting grasp planning, design optimization, and actuation reduction for reconfigurable robotic hands. Further, the approach is applied to a three-fingered metamorphic hand, and the results are studied thoroughly.

Long-distance anti-interference self-feedback regulating fire emergency speaker system

Modern building groups are getting larger and larger, and the lines are getting longer and longer, which directly leads to two major problems. One is that the volume of loudspeakers at the end of the line cannot meet the requirements of normal use. If the power is increased, the loudspeakers near the line will howl and self-excite too much. Second, the power of the power amplifier and the number of loudspeakers cannot be matched exactly. It is urgent to develop fire-fighting loudspeakers or emergency broadcasting systems that can be applied to long-distance transmission, having strong anti-interference ability, and can realize automatic adjustment through feedback. This paper develops a set of intelligent fire broadcast system based on distributed power amplifier, which can realize the following functions: it can connect with other platforms and systems through the big data platform, realize cross-platform, cross-system real-time long-distance playback of the broadcasting system, and solve the problem of terminal volume. By switching channels, power control, etc. Using the near-end strategy optimization algorithm based on tailoring, the optimal joint interference avoidance strategy of the system is obtained to solve the problem of environmental noise interference. Based on the deep reinforcement learning algorithm, the problem of matching the power amplifier power and the number of speakers is solved.

Tool path generation for 5-axis flank milling of ruled surfaces with optimal cutter locations considering multiple geometric constraints

Ruled surfaces found in engineering parts are often blended with a constraint surface, like the blade surface and hub surface of a centrifugal impeller. It is significant to accurately machine these ruled surfaces in flank milling with interference-free and fairing tool path, while current models in fulfilling these goals are complex and rare. In this paper, a tool path planning method with optimal cutter locations (CLs) is proposed for 5-axis flank milling of ruled surfaces under multiple geometric constraints. To be specific, a concise three-point contact tool positioning model is firstly developed for a cylindrical cutter. Different tool orientations arise when varying the three contact positions and a tool orientation pool with acceptable cutter-surface deviation is constructed using a meta-heuristic algorithm. Fairing angular curves are derived from candidates in this pool, and then curve registration for cutter tip point on each determined tool axis is performed in respect of interference avoidance and geometric smoothness. On this basis, an adaptive interval determination model is developed for deviation control of interpolated cutter locations. This model is designed to be independent of the CL optimization process so that multiple CLs can be planned simultaneously with parallel computing technique. Finally, tests are performed on representative surfaces and the results show the method has advantages over previous meta-heuristic tool path planning approaches in both machining accuracy and computation time, and receives the best comprehensive performance compared to other multi-constrained methods when machining an impeller.

A comprehensive review and directions for future research on the integrated scheduling of quay cranes and automated guided vehicles and yard cranes in automated container terminals

Automated Container Terminals (ACTs) have attracted an increasing number of researchers over the last decade, compared to conventional terminals, because of their ability to increase terminal productivity and performance and cope with the increasing containerized trade volumes. Also, there ae several developments in the handling equipment used in ACTs to expand the terminal efficiency and serve large-size vessels efficiently and with lower costs. Due to the fact that in ACTs, all equipment is automatically controlled, interference avoidance between each pair of equipment is important to avoid any disruption or backlog of cargo. Therefore, integrated scheduling of ACT’s handling equipment has been one of the most effective ways to increase the terminal’s performance and equipment utilization and minimize costs. This paper presents a comprehensive review and analysis of the literature addressing the integrated handling equipment scheduling problem in ACTs. Based on the provided gap analysis, the paper discussed the possible directions for future research. After explaining the problem and its importance, the reviewed literature is classified based on four main categories: the type of the integrated problem, the solution techniques, the objectives, and the equipment type used in each study. The main outcome is that most papers that addressed the integrated scheduling problem of handling equipment in automated container terminals generally focused on scheduling only a single type of equipment, mostly the AVs, and assumed that the scheduling of other equipment is known in advance. This opens the arena for addressing the integrated problem as it is illustrated in this paper.

Improved Spread Spectrum Aloha Protocol and Beam-Hopping Approach for Return Channel in Satellite Internet of Things.

This paper examines potential performances of the Spread Spectrum-based random access technique and proposes an Improved Spread Spectrum Aloha (ISSA) protocol for the return channel in satellite Internet of Things (IoT) based on the beam-hopping technique. The key design driver and detailed solution of ISSA protocol are presented in this work and it is shown that the proposed protocol achieves high throughput and low collision probability. To match user/traffic distribution, delay requirement and channel condition with beam allocation better, a low-complexity heuristic beam scheduling algorithm and a more effective Maximum-Weighted Clique (MWC) algorithm have been proposed. The heuristic algorithm considers the user/traffic distribution, inter-beam interference, and fairness primarily. However, the MWC algorithm gives considerations not only on above factors, but also on delay requirement and channel condition (path loss and rain attenuation) to maximize system capacity. The beam angle and interference avoidance threshold are proposed to measure the inter-beam interference, and the link propagation loss and rain attenuation are considered meanwhile in the channel condition. In the MWC algorithm, we construct an auxiliary graph to find the maximum-weighted clique and derive the weighting approach to be applied in different application scenarios. The performance evaluation of our ISSA protocol compared with the SSA protocol is presented, which achieves a gain of 16.7%. The simulation of the ISSA protocol combined with round robin, heuristic, and MWC beam scheduling for the return link in beam-hopping satellite IoTs is also provided. The results indicate that the throughput in nonuniform user distribution is much lower than in the uniform case without the beam scheduling algorithm. Through the application of the scheduling algorithm, the throughput performance can approach the uniform distribution. Finally, the degree of user satisfaction with different scheduling approaches is presented, which validates the effectiveness of heuristic and MWC algorithms.

Multi-Satellite Beam Hopping Based on Load Balancing and Interference Avoidance for NGSO Satellite Communication Systems

Due to the non-uniform distribution of the ground traffic demand and the high mobility of non-geostationary orbit (NGSO) satellites, how to make full use of the limited beam resources to serve users flexibly and efficiently is a brand-new challenge for NGSO communication systems. In order to achieve efficient spectrum utilization, the combination of full frequency multiplexing and beam hopping is a major trend in future satellite communication systems. However, conventional beam hopping methods are mainly based on geostationary satellites, which do not take into account the interference between satellites. This paper proposes a multi-satellite beam hopping algorithm based on load balancing and interference avoidance, which takes advantage of the multiple coverage features in the NGSO constellation and avoids intra-satellite interference and inter-satellite interference by designing beam-hopping patterns with spatial isolation characteristics. In particular, we decompose the multi-satellite beam hopping problem into three sub-problems, which are the multi-satellite load balancing problem, the single-satellite beam hopping pattern design problem, and the multi-satellite interference avoidance problem. Simulation results demonstrate that the proposed method reduces the load gap among satellites by about 72.5% and the average traffic satisfaction rate can reach 81.4%. Besides, our method has the lowest unmet capacity compared with other benchmarks, achieving better offered-requested data match.

NGSO Satellites Beam Hopping Strategy Based on Load Balancing and Interference Avoidance for Coexistence With GSO Systems

Non-geostationary orbit (NGSO) satellite communication system plays an important role in achieving seamless global coverage and addressing the digital divide. The uneven distribution of terrestrial users and the high mobility of NGSO satellites put forward higher requirements for resource management. In this letter, we propose a multi-satellite beam hopping scheme based on load balancing and interference avoidance, where the complicated multi-satellite joint beam hopping problem is decomposed into two sub-problems, namely the satellite-cell assignment problem and joint multi-satellite beam hopping pattern design problem. On the one hand, we rationally assign cells to different satellites for balancing the traffic load among satellites and reducing the interference to geostationary earth orbit (GSO) ground stations. On the other hand, an iterative multi-satellite beam hopping pattern design scheme based on minimizing co-channel interference criterion is adopted to achieve on-demand service. Simulation results indicate that the performance of load balancing and interference avoidance are improved compared to the maximum elevation angle access strategy. Besides, the proposed scheme outperforms other benchmarks in terms of the traffic satisfaction rate, and the optimality gap is only 0.1%.

Loose Coupling: An Invisible Thread in the History of Technology

We present an interdisciplinary survey of the history of loosely coupled systems. We apply the presented concepts in communication networks and suggest hybrid self-organizing networks (SONs) as a universal model for future networks. Self-organizing networks can fulfill the tight requirements of future networks but are challenging to use due to their complexity and immaturity. Moreover, the lack of an externally defined goal and centralized control has resulted in many distributed self-organizing systems failing. This is because the nonlinear relationships between the system parts result in emergence, i.e., we cannot predict the behavior of the whole from the behavior of the parts. Furthermore, a set of local optima does not produce a global optimum. Hybrid SONs tackle these challenges with loose or weak coupling of interacting agents that combine centralized control for global optimization with distributed control for local optimization. In the loose centralized control of almost autonomous agents, decisions are made mostly locally with small delays. This architecture has beneficial properties such as stability, obtained by decoupling the feedback loops: vertically with time-scale separation and horizontally with interference avoidance. Applications of loose coupling include modular electronics and computer design, structured software design, and service-oriented architectures, especially for microservices. Cross-layer design for network optimization is a new reason to use loose coupling in networks to improve stability. We also summarize some recent trends and present a roadmap to the future. We expect that loose coupling will be widely used in self-organizing networks of future wireless systems.

Optimization of Cognitive Femtocell Network via Oppositional Beetle Swarm Optimization Algorithm

In past decades, cellular networks have raised the usage of spectrum resources due to the victory of mobile broadband services. Mobile devices create massive data than ever before, facing the way cellular networks are installed presently for satisfying the increased traffic requirements. The development of a new exclusive spectrum offered to meet up the traffic requirements is challenging as spectrum resources are limited, hence costly. Cognitive radio technology is presented to increase the pool of existing spectrum resources for mobile users via Femtocells, placed on the top of the available macrocell network for sharing the same spectrum. Nevertheless, the concurrent reuse of spectrum resources from Femto networks poses destructive interference on macro networks. To resolve this issue, this paper introduces an optimal channel allocation model using the Oppositional Beetle Swarm Optimization Algorithm (OBSOA) to allocate the channel with interference avoidance. A new OBSOA is derived in this paper by the inclusion of opposition-based learning (OBL) in BSOA. This algorithm allocates the channels used by PUs (PUs) to the secondary users (SUs) in such a way that interference is minimized. This proposed approach is implemented in the MATrix LABoratory (MATLAB) platform. The performance of this proposed approach is evaluated in terms of several measures and the experimental outcome verified the superior nature of the OBSOA-based channel allocation model. OBSOA model has resulted in a maximum signal-to-interference-plus-noise ratio value of 86.42 dB.

Artificial Intelligence and Internet of Things Enabled Intelligent Framework for Active and Healthy Living

Obesity poses several challenges to healthcare and the well-being of individuals. It can be linked to several life-threatening diseases. Surgery is a viable option in some instances to reduce obesity-related risks and enable weight loss. State-of-the-art technologies have the potential for long-term benefits in post-surgery living. In this work, an Internet of Things (IoT) framework is proposed to effectively communicate the daily living data and exercise routine of surgery patients and patients with excessive weight. The proposed IoT framework aims to enable seamless communications from wearable sensors and body networks to the cloud to create an accurate profile of the patients. It also attempts to automate the data analysis and represent the facts about a patient. The IoT framework proposes a co-channel interference avoidance mechanism and the ability to communicate higher activity data with minimal impact on the bandwidth requirements of the system. The proposed IoT framework also benefits from machine learning based activity classification systems, with relatively high accuracy, which allow the communicated data to be translated into meaningful information.

Advancing X-ray Luminescence for Imaging, Biosensing, and Theragnostics.

ConspectusX-ray luminescence is an optical phenomenon in which chemical compounds known as scintillators can emit short-wavelength light upon the excitation of X-ray photons. Since X-rays exhibit well-recognized advantages of deep penetration toward tissues and a minimal autofluorescence background in biological samples, X-ray luminescence has been increasingly becoming a promising optical tool for tackling the challenges in the fields of imaging, biosensing, and theragnostics. In recent years, the emergence of nanocrystal scintillators have further expanded the application scenarios of X-ray luminescence, such as high-resolution X-ray imaging, autofluorescence-free detection of biomarkers, and noninvasive phototherapy in deep tissues. Meanwhile, X-ray luminescence holds great promise in breaking the depth dependency of deep-seated lesion treatment and achieving synergistic radiotherapy with phototherapy.In this Account, we provide an overview of recent advances in developing advanced X-ray luminescence for applications in imaging, biosensing, theragnostics, and optogenetics neuromodulation. We first introduce solution-processed lead halide all-inorganic perovskite nanocrystal scintillators that are able to convert X-ray photons to multicolor X-ray luminescence. We have developed a perovskite nanoscintillator-based X-ray detector for high-resolution X-ray imaging of the internal structure of electronic circuits and biological samples. We further advanced the development of flexible X-ray luminescence imaging using solution-processable lanthanide-doped nanoscintillators featuring long-lived X-ray luminescence to image three-dimensional irregularly shaped objects. We also outline the general principles of high-contrast in vivo X-ray luminescence imaging which combines nanoscintillators with functional biomolecules such as aptamers, peptides, and antibodies. High-quality X-ray luminescence nanoprobes were engineered to achieve the high-sensitivity detection of various biomarkers, which enabled the avoidance of interference from the biological matrix autofluorescence and photon scattering. By marrying X-ray luminescence probes with stimuli-responsive materials, multifunctional theragnostic nanosystems were constructed for on-demand synergistic gas radiotherapy with excellent therapeutic effects. By taking advantage of the capability of X-rays to penetrate the skull, we also demonstrated the development of controllable, wireless optogenetic neuromodulation using X-ray luminescence probes while obviating damage from traditional optical fibers. Furthermore, we discussed in detail some challenges and future development of X-ray luminescence in terms of scintillator synthesis and surface modification, mechanism studies, and their other potential applications to provide useful guidance for further advancing the development of X-ray luminescence.

Cross-Technology Communication for the Internet of Things: A Survey

The ever-developing Internet of Things (IoT) brings the prosperity of wireless sensing and control applications. In many scenarios, different wireless technologies coexist in the shared frequency medium as well as the physical space. Such wireless coexistence may lead to serious cross-technology interference (CTI) problems, e.g., channel competition, signal collision, and throughput degradation. Compared with traditional methods like interference avoidance, tolerance, and concurrency mechanism, direct and timely information exchange among heterogeneous devices is therefore a fundamental requirement to ensure the usability, inter-operability, and reliability of the IoT. Under this circumstance, Cross-Technology Communication (CTC) technique thus becomes a hot topic in both academic and industrial fields, which aims at directly exchanging data among heterogeneous devices that follow different standards. This paper comprehensively summarizes the CTC techniques and reveals that the key challenge for CTC lies in the heterogeneity of IoT devices, including the incompatibility of technical standards and the asymmetry of connection capability. Based on the above finding, we present a taxonomy of the existing CTC works (packet-level CTCs and physical-level CTCs) and compare the existing CTC techniques in terms of throughput, reliability, hardware modification, and concurrency.

Design and Analysis of Frequency Hopping-Aided FMCW-Based Integrated Radar and Communication Systems

Although the frequency-modulated continuous-wave (FMCW)-based scheme has been considered a candidate for realizing integrated radar-communication (RadCom) systems, it is limited by low spectral efficiency. Thus, this study proposes a frequency hopping-aided FMCW-based RadCom system along with the corresponding radar detection and communication signal demodulation approaches. The proposed system can significantly improve the transmission rate with slight radar performance degradation. In addition, both the radar and communication subsystems of the proposed RadCom system are analyzed. Consequently, a symbol interleaving approach that can mitigate radar performance degradation is proposed. Furthermore, the interference is shown to not degrade the radar performance significantly because of frequency hopping. However, to address the issue of the interference significantly degrading communication performance, interference avoidance and mitigation approaches using scheduling and interference rejection combining, respectively, are proposed. Simulations are conducted to evaluate the proposed RadCom system. The results validate the analysis and demonstrate that the proposed RadCom system can provide radar detection performance that is almost identical to conventional FMCW radar with a high transmission rate. Furthermore, the results confirm the effectiveness of the proposed interleaving and interference management methods.