He Xu

Prof. Dr. He Xu

School of Computer Science, Nanjing University of Posts and Telecommunications, Nanjing, 210023, China
orcid

Research Focus & Metrics

Academic Career Length

14Years (2013-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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5 August 2017 in Sensors
Verified
Journal Article
Open access
PDF file
He XuHe Xu
He Xu
YDYe Ding
Ye Ding
PLPeng Li
Peng Li
RWRuchuan Wang
Ruchuan Wang
YLYizhu Li
Yizhu Li
The Global Positioning System (GPS) is widely used in outdoor environmental positioning. However, GPS cannot support indoor positioning because there is no signal for positioning in an indoor environment. Nowadays, there are many situations which require indoor positioning, such as searching for a book in a library, looking for luggage in an airport, emergence navigation for fire alarms, robot location, etc. Many technologies, such as ultrasonic, sensors, Bluetooth, WiFi, magnetic field, Radio Frequency Identification (RFID), etc., are used to perform indoor positioning. Compared with other technologies, RFID used in indoor positioning is more cost and energy efficient. The Traditional RFID indoor positioning algorithm LANDMARC utilizes a Received Signal Strength (RSS) indicator to track objects. However, the RSS value is easily affected by environmental noise and other interference. In this paper, our purpose is to reduce the location fluctuation and error caused by multipath and environmental interference in LANDMARC. We propose a novel indoor positioning algorithm based on Bayesian probability and K-Nearest Neighbor (BKNN). The experimental results show that the Gaussian filter can filter some abnormal RSS values. The proposed BKNN algorithm has the smallest location error compared with the Gaussian-based algorithm, LANDMARC and an improved KNN algorithm. The average error in location estimation is about 15 cm using our method.

4 January 2022 in IEEE Transactions on Intelligent Transportation Systems
Verified
Journal Article
Open access
He XuHe Xu
He Xu
MGMingtao Guo
Mingtao Guo
Nadia NedjahNadia Nedjah
Nadia Nedjah
JZJindan Zhang
Jindan Zhang
PLPeng Li
Peng Li
Aiming at the shortcomings of the current YOLOv3 model, such as large size, slow response speed, and difficulty in deploying to real devices, this paper reconstructs the target detection model YOLOv3, and proposes a new lightweight target detection network YOLOv3-promote: Firstly, the G-Module combined with the Depth-Wise convolution is used to construct the backbone network of the entire model, and the attention mechanism is introduced and added to perform weighting operations on each channel to get more key features and remove redundant features, thereby strengthening the identification ability of feature network model’s to distinguish target objects among background; Secondly, in order to delete some less important channels to achieve the effect of compressing the model size and improving the calculation speed, the size of the scaling factor gamma in the batch normalization layer is used; Finally, based on NVIDIA’s TensorRT framework model conversion and half-precision acceleration were carried out, and the accelerated model was successfully deployed on the embedded platform Jetson Nano. The performed KITTI experimental results show that the inference speed of our proposed method is about 5 times that of the original model, the parameter volume is reduced to one tenth, the mAP is increased from 86.1% of the original model to 93.1%, and the FPS reaches 25.5fps, realizing the requirements of real-time detection with high precision.

10 May 2018 in Sensors
Verified
Journal Article
Open access
PDF file
He XuHe Xu
He Xu
MWManxing Wu
Manxing Wu
PLPeng Li
Peng Li
FZFeng Zhu
Feng Zhu
RWRuchuan Wang
Ruchuan Wang
Nowadays, location-based services, which include services to identify the location of a person or an object, have many uses in social life. Though traditional GPS positioning can provide high quality positioning services in outdoor environments, due to the shielding of buildings and the interference of indoor environments, researchers and enterprises have paid more attention to how to perform high precision indoor positioning. There are many indoor positioning technologies, such as WiFi, Bluetooth, UWB and RFID. RFID positioning technology is favored by researchers because of its lower cost and higher accuracy. One of the methods that is applied to indoor positioning is the LANDMARC algorithm, which uses RFID tags and readers to implement an Indoor Positioning System (IPS). However, the accuracy of the LANDMARC positioning algorithm relies on the density of reference tags and the performance of RFID readers. In this paper, we introduce the weighted path length and support vector regression algorithm to improve the positioning precision of LANDMARC. The results show that the proposed algorithm is effective.

11 February 2018 in Education Sciences
Verified
Journal Article
Open access
PDF file
PTPing Tan
Ping Tan
HWHan Wu
Han Wu
PLPeng Li
Peng Li
He XuHe Xu
He Xu
Currently, Internet of Things (IoT) technologies are used in many areas, such as intelligent transportation, smart city, hospital, games, education. Earlier interactive response system uses infrared or radio frequency (RF) wireless communication technologies to transmit the students’ answer to teachers’ managerment system, where there exists high cost, inconvenient usage, difficult deployment. How to use IoT to improve the quality of higher education becomes a very important topic in the researh area of teaching. Radio Frequency Identification (RFID) is one of key technologies to implement IoT applications, and most of universities use the High Frequency (HF) RFID card as the students’ identification devices in China. In this paper, a kind of WiFi supported RFID reader (WiRF) is implemented using open source hardware platforms, such as Node MCU and RFID-RC522. Then the proposed WiRF system is used to assist teacher to perform automatic attendance record and students’ behavior record. In addition, Quick Response (QR) code is another technology to enable IoT. In this paper, QR code is designed to quickly access course video and perform real-time interactive response in the classroom, which will provide multidimensional learning and strengthen the motivation of students’ learning. This IoT system can improve the attendance of students, and give a positive impact on students’ learning process for higher education.

1 January 2022 in Journal of Algorithms & Computational Technology
Verified
Journal Article
Open access
He XuHe Xu
He Xu
LZLin Zhang
Lin Zhang
PLPeng Li
Peng Li
FZFeng Zhu
Feng Zhu
The main task of outlier detection is to detect data objects which have a different mechanism from the conventional data set. The existing outlier detection methods are mainly divided into two directions: local outliers and global outliers. Aiming at the limitations of the existing outlier detection methods, we propose a novel outlier detection algorithm which is named as kNN-LOF. First, the k-nearest neighbors algorithm is applied to divide different areas for outlier attributes, which is more suitable for outlier detection in different density distributions. Secondly, a hierarchical adjacency order is proposed to hierarchize the neighborhood range according to the link distance. The average sequence distance is calculated from the data objects in the hierarchy, and the reachable distance of an object is redefined to introduce a new local outlier factor. Experimental results show that the proposed algorithm has good performance in improving the accuracy of outlier detection.

2 March 2018 in Sensors
Verified
Journal Article
Open access
PDF file
He XuHe Xu
He Xu
JDJie Ding
Jie Ding
PLPeng Li
Peng Li
FZFeng Zhu
Feng Zhu
RWRuchuan Wang
Ruchuan Wang
With the fast development of the Internet of Things, Radio Frequency Identification (RFID) has been widely applied into many areas. Nevertheless, security problems of the RFID technology are also gradually exposed, when it provides life convenience. In particular, the appearance of a large number of fake and counterfeit goods has caused massive loss for both producers and customers, for which the clone tag is a serious security threat. If attackers acquire the complete information of a tag, they can then obtain the unique identifier of the tag by some technological means. In general, because there is no extra identifier of a tag, it is difficult to distinguish an original tag and its clone one. Once the legal tag data is obtained, attackers can be able to clone this tag. Therefore, this paper shows an efficient RFID mutual verification protocol. This protocol is based on the Physical Unclonable Function (PUF) and the lightweight cryptography to achieve efficient verification of a single tag. The protocol includes three process: tag recognition, mutual verification and update. The tag recognition is that the reader recognizes the tag; mutual verification is that the reader and tag mutually verify the authenticity of each other; update is supposed to maintain the latest secret key for the following verification. Analysis results show that this protocol has a good balance between performance and security.