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1st ACM Workshop on Context Sensing and Activity Recognition, CSAR 2015

作者： Xiao, Fu Xie, Xiaohui Zhu, Hai Sun, Lijuan Wang, Ruchuan School of Computer Nanjing University of Posts and Telecommunications China Jiangsu High Technology Research Key Laboratory for Wireless Sensor Networks China Key Lab of Broadband Wireless Communication and Sensor Network Technology China

ISBN: (纸本)9781450338424

WiFi signals have attracted extensive attention for context-aware due to its ubiquity. Traditional WiFi sensing methods mainly adopt Received Signal Strength Indication (RSSI), however the coarse features hamper its expansion. To achieve more finger-grained information, Channel State Information (CSI) is introduced for sensing, based on which, we design a directional human detection scheme via data prediction, which aims to visualize the variations of CSI when human appears. However, this scheme suffers from the limitations caused by the link-centric architecture of WiFi. Considering the demands for omnidirectional coverage of some scenarios (e.g. museum exhibition), we propose a omni-directional detection scheme based on fingerprinting utilizing the relationship between the CSI signal features and locations. Experiments are processed in actual scenarios and experimental results verify the feasibility of our two schemes. © 2015 ACM.

关键词： Channel state information

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Moving Object Distance Estimation Method Based on Target Extraction with a Stereo Camera 4

Moving Object Distance Estimation Method Based on Target Ext...

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4th IEEE International Conference on Image, Vision and Computing, ICIVC 2019

作者： Zhang, Jingyi Chen, Jianxin Lin, Qingyu Cheng, Liming Nanjing University of Posts and Telecommunications Ministry of Education Key Lab of Broadband Wireless Communication and Sensor Network Technology Nanjing China

ISBN: (纸本)9781728123257

Real-time distance estimation with high accuracy is crucial to robot applications such as navigation and obstacle negotiation. However, considering the truth that high accuracy brings huge computation, the previous work either accelerates the distance estimation process through hardware, or only estimates the static objects, or sacrifices accuracy to realize real-time. In order to improve the trade-off between speed and accuracy, in this paper we propose a stereovision-based method that integrates the object detection and tracking into stereo matching. We utilize kernelized correlation filter (KCF) to track the moving object, and then extract target regions from image pair as input images to compute disparity map. In addition, we update each pixel's disparity by a simple but effective approach to further refine disparity map. Eventually, distance is calculated with disparity by triangulation. Experimental results show that our proposed method is suitable for dynamic environment, the extraction method improves the speed of the entire system, and the average accuracy of distance estimation can achieve over 95% from 88cm to 300cm when baseline is 151mm. © 2019 IEEE.

关键词： Stereo vision

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Heart Rate Detection with the Off-the-Shelf Camera: Static to Non-Static 5

Heart Rate Detection with the Off-the-Shelf Camera: Static t...

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5th IEEE International Conference on Signal and Image Processing, ICSIP 2020

作者： Chen, Rui Chen, Jianxin Cheng, LiMing Huang, XiangJun Key Lab of Broadband Wireless Communication and Sensor Network Technology Nanjing University of Posts and Telecommunications Ministry of Education Nanjing China

ISBN: (纸本)9781728168968

Imaging photo-plethysmography (IPPG) technique has been proven to detect heart rate (HR) with a camera. Currently it might be used in a rigid scenario, such as the static subject, the short measurement distance and good illumination. In this paper, we try to relax these constraints by extending the measurement distance and applying it to the non-static subject with IPPG technique using the off-the-shelf camera. To achieve it, the landmark detection method is used to locate the facial region of interest (ROI) for the subject during movements. On this ROI, R/G/B channel signals are extracted with the spatial average of pixels. Then we use a skin appearance model (CHROME) to remove the noise, and HR is estimated from the output of the CHROME through the power spectrum. Experimental results showed that our method works effectively in both static and non-static scenarios. In static scenario, the measurement distance can extend to 4 meters, while the accuracy can reach 86% compared with the results from a finger detection equipment. In non-static scenario, our method achieve better results than previous studies. © 2020 IEEE.

关键词： Cameras

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Joint Optimization of Resource Allocation and Trajectory Based on User Trajectory for UAV-Assisted Backscatter Communication System

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China communications 2024年第2期21卷 197-209页

作者： Peizhong Xie Junjie Jiang Ting Li Yin Lu School of Communication and Information Engineering Nanjing University of Posts and TelecommunicationsNanjing 210003China Key Lab of Broadband Wireless Communication and Sensor Network Technology(Nanjing University of Posts and Telecommunications) Ministry of EducationNanjing 210003China

The Backscatter communication has gained widespread attention from academia and industry in recent years. In this paper, A method of resource allocation and trajectory optimization is proposed for UAV-assisted backscatter communication based on user trajectory. This paper will establish an optimization problem of jointly optimizing the UAV trajectories, UAV transmission power and BD scheduling based on the large-scale channel state signals estimated in advance of the known user trajectories, taking into account the constraints of BD data and working energy consumption, to maximize the energy efficiency of the system. The problem is a non-convex optimization problem in fractional form, and there is nonlinear coupling between optimization *** iterative algorithm is proposed based on Dinkelbach algorithm, block coordinate descent method and continuous convex optimization technology. First, the objective function is converted into a non-fractional programming problem based on Dinkelbach method,and then the block coordinate descent method is used to decompose the original complex problem into three independent sub-problems. Finally, the successive convex approximation method is used to solve the trajectory optimization sub-problem. The simulation results show that the proposed scheme and algorithm have obvious energy efficiency gains compared with the comparison scheme.

关键词： energy efficiency joint optimization UAV-assisted backscatter communication user trajectory

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A novel adaptive resource allocation algorithm for multiuser ofdm-based cognitive radio systems

A novel adaptive resource allocation algorithm for multiuser...

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International Conference on network Computing and Information Security

作者： Jian, Zhang Qi, Zhu Key Lab of Broadband Wireless Communication and Sensor Network Technology Nanjing University of Posts and Telecommunications Ministry of Education Nanjing China

ISBN: (纸本)9780769543550

Cognitive radio(CR) is a concept to improve the utilization of scarce spectrum resources in wireless communication, and orthogonal frequency division multiplexing (OFDM) is regarded as the best technology to match with the CR systems. In this paper, a new adaptive resource allocation algorithm for OFDM CR systems is presented. This algorithm solves the optimization problem based on maximize the total transmit bit rates of secondary users, on the one hand, the total transmit power of secondary users should below the transmit power constraint, on the other hand, the interference to primary users should under the maximum interference level, then allocate sub channels by an improved Hungarian Algorithm, and load bits and power by greedy algorithm. Simulation results show that the proposed algorithm can improve the system throughput comparing with some other sub optimal algorithms. © 2011 IEEE.

关键词： Cognitive radio

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Research on Functional Test of Mobile APP Based on Robot 5

Research on Functional Test of Mobile APP Based on Robot

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5th IEEE International Conference on Signal and Image Processing, ICSIP 2020

作者： Pan, Zhaolai Chen, Jianxin Yao, Ling Chen, ZhuAn Nanjing University of Posts and Telecommunications Ministry of Education Key Lab of Broadband Wireless Communication and Sensor Network Technology Nanjing China

ISBN: (纸本)9781728168968

With the rapid popularization of smartphones, various applications (Application: APP) have come into being. Therefore, automated testing of mobile applications is particularly important. At present, the automated testing on the market is often completed through test frameworks. However, when using the test framework we need to consider the compatibility of the mobile platform system. What's worse, accessing multiple apps at the same time has a bad impact on accuracy. In view of these problems, a robot-based automated test system for mobile applications is proposed. Firstly, a wireless projection technology is utilized to project the screen of a mobile device onto a computer screen. Then, the optical character recognition (OCR) algorithm and the normalized correlation matching algorithm are used to position the coordinates of the elements. Finally, the robot performs a click operation under control. The experimental results show that the system can achieve cross-platform testing, including automatically testing Chinese software or English software on Android and iOS platforms, and also has high accuracy and robustness. © 2020 IEEE.

关键词： Software testing

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3D Modeling of the Rotationally Symmetric Objects Using Kinect 4

3D Modeling of the Rotationally Symmetric Objects Using Kine...

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4th IEEE International Conference on Image, Vision and Computing, ICIVC 2019

作者： DIng, Jie Chen, Jianxin Zhou, Anqi Chen, Zhimin Nanjing University of Posts and Telecommunications Ministry of Education Key Lab of Broadband Wireless Communication and Sensor Network Technology Nanjing China

ISBN: (纸本)9781728123257

With the appearance of RGB-D cameras, 3D reconstruction becomes convenient. Previous studies focused on the objects with strong structural features. But for the objects with weak structure, such as rotationally symmetric objects. There is no solution. In this paper, we propose a method to model the rotationally symmetric objects. In this method, we scan the object in one view and the point cloud is projected to the 2D space. Then, we extract the boundary of the point cloud. And the Least Square is adopted to fit the extracted boundary to improve the accuracy of the boundary. At last, we rotate the fitting boundary and get the model. To verify the effectiveness of our method, several experiments have been performed to evaluate the error of the models. In addition, we use it to reconstruct the object with the hole on one side. And the results show the efficiency and computational complexity of our method. © 2019 IEEE.

关键词： 3D modeling

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Work chain-based inverse kinematics of robot to imitate human motion with Kinect

Work chain-based inverse kinematics of robot to imitate huma...

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作者： Zhang, Ming Chen, Jianxin Wei, Xin Zhang, Dezhou Key Lab of Broadband Wireless Communication and Sensor Network Technology Nanjing University of Posts and Telecommunications Ministry of Education Nanjing China

The ability to realize human-motion imitation using robots is closely related to developments in the field of artificial intelligence. However, it is not easy to imitate human motions entirely owing to the physical differences between the human body and robots. In this paper, we propose a work chain-based inverse kinematics to enable a robot to imitate the human motion of upper limbs in real time. Two work chains are built on each arm to ensure that there is motion similarity, such as the end effector trajectory and the joint-angle configuration. In addition, a two-phase filter is used to remove the interference and noise, together with a self-collision avoidance scheme to maintain the stability of the robot during the imitation. Experimental results verify the effectiveness of our solution on the humanoid robot Nao-H25 in terms of accuracy and real-time performance. © 2018 ETRI

关键词： Anthropomorphic robots

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An Optimization Method to Maximize the Service Quality of SCMA Grant-Free Access with MPR 13

An Optimization Method to Maximize the Service Quality of SC...

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13th International Conference on wireless communications and Signal Processing, WCSP 2021

作者： Wang, Lei Xu, Jing Qi, Ting Jiang, Xue Cui, Jingwu Zheng, Baoyu Nanjing University of Posts and Telecommunications Key Lab of Broadband Wireless Communication and Sensor Network Technology Ministry of Education Nanjing China

ISBN: (纸本)9781665407854

Grant-free access successfully reduces the overhead and delay of signaling in the scenario of ultra-reliable low-latency communications (URLLC). However, it is also prone to conflict in the case of high load, resulting the lose of spectrum efficiency, reduced reliability and increased delay. In this paper, we realize K-multipacket reception (K-MPR) with sparse code multiple access (SCMA) technology to improve spectrum efficiency and throughput, and yet its implementation greatly increases the difficulty of ensuring the reliability of data transmission. Therefore, we propose an optimization method to maximize service quality of SCMA grant-free access with MPR. First, we investigate the behaviors of transient system via Markov chain to obtain reliability under delay constraints. Furthermore, we use dichotomy to calculate the minimum MPR ability value K. The simulation results show the validity of theoretical analysis. The proposed scheme maintains the increasing trend of reliability under delay constraints and tradeoff between throughput and reliability under delay constraints is presented, while optimal tradeoff between spectrum efficiency and reliability is achieved. © 2021 IEEE.

关键词： Reliability

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An improved flooding protocol based on network coding

An improved flooding protocol based on network coding

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International Conference on Information technology and Computer Application Engineering, ITCAE 2014

作者： Zhang, Li Na Zhang, Deng Yin Ji, Ying Tian Key Lab of Broadband Wireless Communication and Sensor Network Technology Nanjing University of Posts and Telecommunications Ministry of Education Nanjing China

ISBN: (纸本)9781138027176

network coding allows network node to process data by the traditional method of data forwarding, which can effectively improve network throughput, robustness and reliability. In this paper, we propose an improved flooding protocol NCFD (network coding of flooding), which combines network coding technology with flooding protocol, adopting linear network coding technology based on multipath propagation. Computer simulation results show that NCFD could significantly reduce network energy consumption and data redundancy. © 2015 Taylor & Francis Group, London.

关键词： network coding

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