المؤلفون: Bin Liu, Yu Wu, Qijia Zheng, Lu Su, Yan Lu, Chenglin Miao, Jinyang Huang, Chang Wen Chen, Jianchun Liu

المصدر: IEEE Transactions on Mobile Computing. 22:2938-2954

مصطلحات موضوعية: Computer Networks and Communications, Computer science, business.industry, Real-time computing, Co-channel interference, Interference (wave propagation), Activity recognition, Robustness (computer science), Channel state information, Component (UML), Wireless, Electrical and Electronic Engineering, business, Wireless sensor network, Software

الوصف: Driven by a wide range of essential applications, significant achievements are made to explore WiFi-based Human Activity Recognition (HAR) techniques that utilize the information collected by commercial off-the-shelf WiFi infrastructures to infer human activities without the need for subjects to carry any devices. Although existing WiFi-based HAR systems achieve satisfactory performance in some instances, they are faced with a severe challenge that the impacts of ubiquitous Co-channel Interference (CCI) on WiFi signals are inevitable. This downgrades the performance of these HAR systems significantly. To address this challenge, we propose PhaseAnti, a novel WiFi-based HAR system to exploit the CCI-independent phase component, Nonlinear Phase Error Variation (NLPEV), of WiFi Channel State Information to cope with the negative effects of CCI. The stability of NLPEV data and the sensibility of this component to motions are rigorously analyzed. Furthermore, validated by extensive properly designed experiments, this phase component across subcarriers is invariant under various CCI scenarios while sufficiently distinct for different motions. Therefore, the NLPEV data can be used and processed effectively to perform HAR in CCI scenarios. Extensive experiments with various daily activities in different indoor rooms demonstrate the superior effectiveness and generalizability of the proposed PhaseAnti system under various CCI scenarios.

الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_________::d30d515bd8f7e40ee3d58ca609fb715aTest
https://doi.org/10.1109/tmc.2021.3127721Test

المؤلفون: Yiu-Wing Leung, Shuwei Qiu, Joseph Kee-Yin Ng, Xiaowen Chu

المصدر: IEEE Transactions on Mobile Computing. 22:2771-2788

مصطلحات موضوعية: Computer Networks and Communications, Computer science, business.industry, Quality of service, ComputerSystemsOrganization_COMPUTER-COMMUNICATIONNETWORKS, Fault tolerance, Interference (wave propagation), IEEE 802.11ax, Power (physics), Point (geometry), Electrical and Electronic Engineering, business, Greedy algorithm, Throughput (business), Software, Computer network

الوصف: IEEE 802.11ax is the standard for the new generation WiFi networks. In this paper, we formulate the problem of joint access point (AP) placement and power-channel-resource unit assignment for 802.11ax-based dense WiFi. The objective is to minimize the number of APs. Two quality-of-service (QoS) requirements are to be fulfilled: (1) a two-tier throughput requirement which ensures that the throughput of each station is good enough, and (2) a fault tolerance requirement which ensures that the stations could still use WiFi even when some APs fail. We prove that this problem is NP-hard. To tackle this problem, we first develop an analytic model to derive the throughput of each station under the OFDMA mechanism and a widely used interference model. We then design a heuristic algorithm to find high-quality solutions with polynomial time complexity. Simulation results under both fixed-user and mobile-user cases show that: (1) when the area is small (50 x 50 m2), our algorithm gives the optimal solutions; when the area is larger (80 x 60 m2), our algorithm can reduce the number of APs by 34.9-87.7% as compared to the Random and Greedy algorithms. (2) Our algorithm can always get feasible solutions that fulfill the QoS requirements.

الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_________::fd6aea2855c5b56cd304da98d0b0d139Test
https://doi.org/10.1109/tmc.2021.3129596Test

المؤلفون: Dan Keun Sung, Xinming Zhang, Hui Zhang

المصدر: IEEE Transactions on Mobile Computing. 22:1880-1893

مصطلحات موضوعية: Computer Networks and Communications, business.industry, Computer science, Retransmission, ComputerSystemsOrganization_COMPUTER-COMMUNICATIONNETWORKS, Latency (audio), Data_CODINGANDINFORMATIONTHEORY, Interference (wave propagation), law.invention, Relay, law, Metric (mathematics), Redundancy (engineering), Overhead (computing), Electrical and Electronic Engineering, business, Software, Selection (genetic algorithm), Computer network

الوصف: In VANETs, it is important to support fast and reliable multi-hop broadcast for safety-related applications. The performance of multi-hop broadcast schemes is greatly affected by relay selection strategies. However, the relationship between the relay selection strategies and the expected broadcast performance has not been fully characterized yet. Furthermore, conventional broadcast schemes usually attempt to minimize the waiting time difference between adjacent relay candidates to reduce the waiting time overhead, which makes the relay selection process vulnerable to internal interference, occurring due to retransmissions from previous forwarders and transmissions from redundant relays. In this paper, we jointly take both of the relay selection and the internal interference mitigation into account and propose a fast, reliable, opportunistic multi-hop broadcast scheme, in which we utilize a novel metric called the expected broadcast speed in relay selection and propose a delayed retransmission mechanism to mitigate the adverse effect of retransmissions from previous forwarders and an expected redundancy probability based mechanism to mitigate the adverse effect of redundant relays. The performance evaluation results show that the proposed scheme yields the best broadcast performance among the four schemes in terms of the broadcast coverage ratio and the end-to-end delivery latency.

الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_________::3edf7e5ffe048be6beec26d962c48309Test
https://doi.org/10.1109/tmc.2021.3119015Test

المؤلفون: Tatsuaki Kimura

المصدر: IEEE Transactions on Mobile Computing. 22:2205-2220

مصطلحات موضوعية: symbols.namesake, Computer Networks and Communications, Computer science, symbols, Statistical physics, Electrical and Electronic Engineering, Interference (wave propagation), Poisson distribution, Software

الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_________::6764e15cc2a885b1240e43bbe21440d0Test
https://doi.org/10.1109/tmc.2021.3116314Test

المؤلفون: Chao Xu, Zexing Yu, Fei Du, Jiaying Sun

المصدر: Chinese Journal of Aeronautics. 35:208-221

مصطلحات موضوعية: Physics, Guided wave testing, Fuselage, Wave propagation, Scattering, Mechanical Engineering, Acoustics, Aerospace Engineering, Sensitivity (control systems), Time domain, Interference (wave propagation), Finite element method

الوصف: Stiffened panels have been widely utilized in fuselages and wings as critical load-bearing components. These structures are prone to be damaged under long-term and extreme loads, and their health monitoring has been a common concern. The guided wave-based monitoring method is regarded as an efficient approach to detect the damage in stiffened plates because of its wide monitoring range and high sensitivity to micro-damage. Efficient simulation of wave propagation can theoretically demonstrate the detection mechanism of the method. In this study, a Time-Domain Spectral Finite Element Method (TD-SFEM) is adopted to study the wavefield in stiffened plates, where continuous Absorbing Layers with Increasing Damping (ALID) strategy is proposed to circumvent the disturbance of reflected waves on boundaries. After the convergence analysis, the developed TD-SFEM with ALID is validated by the finite element method first. Then, wave scattering and the influence of the stiffener are investigated in detail by comparing the results with the non-stiffened structure. Finally, the effects of the parameters of the stiffener, such as the height and width, on wave propagation are studied, respectively. The results illustrate that the proposed TD-SFEM with ALID is an efficient approach to study the wave propagation in the stiffened plate and can reveal the mechanism of influence of the stiffener. It is found that the height of the stiffener changes the interference of wavefield in the plate, while the effects of the width are mainly in wave scattering and mode conversion.

الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_________::9080aa0f944dab8132d91f29a43525bfTest
https://doi.org/10.1016/j.cja.2021.11.014Test

المؤلفون: Avik Banerjee, Santi P. Maity

المصدر: IEEE Transactions on Mobile Computing. 22:299-310

مصطلحات موضوعية: Computer Networks and Communications, business.industry, Computer science, Node (networking), Eavesdropping, Throughput, Jamming, Transmitter power output, Interference (wave propagation), Cognitive radio, Electrical and Electronic Engineering, business, Software, Data transmission, Computer network

الوصف: This work considers a cognitive radio (CR) network consisting of a set of CR transmit-receive node pairs, one fusion center (FC), multiple primary user emulation attack (PUEA) nodes, an eavesdropper (Eav) node and a set of friendly jammers for protection of CR data from eavesdropping. At the initial time slot, simultaneous energy harvesting (EH) and spectrum sensing are done through power splitting (PS). CR nodes then amplify and forward the samples of primary user (PU) and the PUEA to the FC for cooperative spectrum sensing (CSS). Based on CSS decision, CR transmit nodes either perform EH over the entire duration or make an opportunistic data transmission in time division mode. The closed form expressions of the optimal sensing duration, power allocation factor and transmit power for each secondary user (SU) are found. The sum secondary throughput of the network is maximized under the constraints of meeting the sensing reliability of the PU, individual energy causality for each SU and the best selected jammer, interference at the PU receiver, individual secondary and secrecy outage probability. Simulation results show a performance gain on the maximum value of the sum secondary throughput by ~ 17.56% and ~ 49.69% over the existing works.

الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_________::7a4b9bbfb4c7623b44618953cd98472cTest
https://doi.org/10.1109/tmc.2021.3068797Test

المؤلفون: B.P. Vijay Kumar, Syed Musthak Ahmed, Mahendhra Nanjappa Giri Prasad

المصدر: Materials Today: Proceedings. 80:1747-1750

مصطلحات موضوعية: Computational model, Hidden node problem, business.industry, Computer science, Quality of service, ComputerSystemsOrganization_COMPUTER-COMMUNICATIONNETWORKS, Throughput, General Medicine, Interference (wave propagation), Multipath routing, Routing (electronic design automation), business, Wireless sensor network, Computer network

الوصف: The proposed approach is designed to boost the IEEE 802.15.4 / ZigBee-based WSN streaming efficiency by introducing multipurpose routing. We investigate how those networks can be designed in order to achieve optimum throughput using computational models to explain intra-track and inter-track interference in multipath routing networks. One mode of action in particular – Spatial-TDMA (S-TDMA), Zig Bee dependent WSNs, will greatly reduce the amount of interference, both in one- and multi-track environments. It is also seen that two-way networks can be stronger than their one-way counterparts by means of deliberately selected implementation parameters. Finally, a greater degree of spatial isolation between the routes used indicates improved average efficiency in multi-path scenarios. The simulation is one of our results.

الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_________::4cb458e080e349d99800fff9df66b331Test
https://doi.org/10.1016/j.matpr.2021.05.498Test

المؤلفون: Bang Chul Jung, Yongjae Kim, Janghyuk Youn

المصدر: ICT Express. 8:485-489

مصطلحات موضوعية: Scheme (programming language), Computational complexity theory, Computer Networks and Communications, business.industry, Computer science, ComputerSystemsOrganization_COMPUTER-COMMUNICATIONNETWORKS, Interference (wave propagation), Power (physics), Artificial Intelligence, Hardware and Architecture, Telecommunications link, Electronic engineering, Wireless, Antenna (radio), business, computer, Software, Energy (signal processing), Computer Science::Information Theory, Information Systems, computer.programming_language

الوصف: We propose a novel interference alignment (IA) technique with receive antenna partitioning (RAP) for simultaneous wireless information and power transfer (SWIPT)-enabled downlink fog radio access networks (F-RANs). The basic idea of the proposed scheme is to apply a generalized downlink IA for each access point (AP) and to divide receive antennas at each user into two groups for information decoding (ID) and energy harvesting (EH), respectively. With the proposed scheme, an optimal receive antenna configuration at each user is obtained to maximize the weighted sum of achievable rate and the sum of harvested energy of the network. Also we develop an antenna configuration selection algorithm to obtain near-optimal performance with low computational complexity. Through extensive computer simulations, it is shown that the proposed scheme significantly improves a rate-energy region compared with existing techniques.

الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_________::bcfebad691e0f1c19b64451e9537a34cTest
https://doi.org/10.1016/j.icte.2021.09.011Test

المؤلفون: Wei Pan, Chenxi Xu, Kao-Shing Hwang, Nanding Wang

المصدر: IEEE Transactions on Cognitive and Developmental Systems. 14:1486-1495

مصطلحات موضوعية: Average return, Experience sampling method, Artificial Intelligence, Computer science, business.industry, Multi-agent system, Generalization (learning), Stability (learning theory), Reinforcement learning, Artificial intelligence, business, Interference (wave propagation), Software

الوصف: Multi-agent reinforcement learning is widely used and can successfully solve many problems in the real world. In the multi-agent reinforcement learning system, a global critic network is used to guide each agent’s strategy to update to learn the most beneficial strategy for the collective. However, the global critic network also makes the current agent’s learning be affected by other agents’ strategies, which leads to unstable learning. To solve this problem, we propose Dynamic Decomposed Multi-Agent Deep Deterministic Policy Gradient (DD-MADDPG): a new network that considers both global and local evaluations and adaptively adjusts the agent’s attention to the two evaluations. Besides, the use of the experience replay buffer by Multi-Agent Deep Deterministic Policy Gradient(MADDPG) produces outdated experience, and the outdated strategies of other agents further affect the learning of the current agent. To reduce the influence of other agents’ outdated experience, we propose TDError and Time-based experience sampling (T2-PER) based on DD-MADDPG. We evaluate the proposed algorithm’s performance according to the learning stability and the average return obtained by the agents. We have conducted experiments in the MPE environment. The results show that the proposed method has better stability and higher learning efficiency than MADDPG and has a certain generalization ability.

الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_________::ba44256d85c186706bf397ca6e688cceTest
https://doi.org/10.1109/tcds.2021.3110959Test

المؤلفون: Huadong Ma, Anfu Zhou, Dongzhu Xu, Yi Yang, Teng Wei, Jianhua Liu, Kun Liang

المصدر: IEEE Transactions on Mobile Computing. 21:4439-4455

مصطلحات موضوعية: Computer Networks and Communications, Computer science, Wireless network, Distributed computing, Testbed, Extremely high frequency, Graph (abstract data type), Network performance, Electrical and Electronic Engineering, Reuse, Interference (wave propagation), Software, Scheduling (computing)

الوصف: Millimeter wave (mmWave) wireless networks are envisioned to bring a very high degree of spatial reuse, i.e., multiple links can operate simultaneously without interference. The vision, however, is becoming doubtful, as recent studies found that non-negligible interference exists due to imperfect beam patterns. In this paper, we extensively measure the spatial reuse issue in a dense 60 GHz mmWave network consisting of multiple access points (AP) and users. Our measurement quantifies the impact of interference on network performance and finds that the existing prediction based on interference-resolving approaches are insufficient. Motivated by the findings, we propose MDSR, which enhances the spatial reuse in 60 GHz mmWave networks. Instead of relying on interference prediction, MDSR takes a new measurement principle of building a conflict graph that implicitly takes into account the impact of both beam imperfection and reflections. Using the conflict graph, MDSR improves the spatial reuse from three dimensions: AP association, user scheduling, and beam selection, which can determine the optimal AP-user-beam combination and minimize interference in each scheduling cycle. We prototype and evaluate MDSR on the testbed using commodity mmWave radios. The evaluation results demonstrate that MDSR improves network throughput by multi-folds compared with the state-of-the-art one.

الوصول الحر: https://explore.openaire.eu/search/publication?articleId=doi_________::50957bba0f91a7c2f5c3e38fa6e32c55Test
https://doi.org/10.1109/tmc.2021.3082209Test