最新刊期
卷 37 ， 期 4 ， 2021
- 摘要：The particularity of the urban rail transit environment leads to the problems such as reducing communication reliability, delay performance and operating efficiency bottlenecks.Therefore, the demand for urban rail communication was analyzed from the perspective of overall operational efficiency.New intelligent communication control technologies such as T2T (train to train) communication, 5G, artificial intelligence, and mobile edge computing were combined to summarize and prospect the key technologies of urban rail communication.Then, a new type of urban rail communication network architecture was proposed.Finally, the research direction and challenges of smart urban rail communication technology were discussed, which also provided a research foundation for the development of smart cities.关键词：urban rail transit;train control system;train to train communication;mobile edge computing;artificial intelligence1295|2110|0更新时间：2024-06-05
- 摘要：The conducted measurement campaigns at home and abroad were presented.Meanwhile, proposals and standard channel models from the international standardization organization were reviewed.The propagation characteristics of massive MIMO wireless channels were investigated based on the indoor and outdoor measurements.Moreover, the traditional and novel methods of channel modeling were analyzed.Finally, open research issues were presented.关键词：massive MIMO;wireless channel;channel measurement;channel modeling1190|2348|0更新时间：2024-06-05
Comprehensive Review
- 摘要：As the 5G mobile network is closely integrated with government, medical, financial and other industries related to national economy and people’s livelihood, the security of the data carried by 5G network is crucial.5G data and flow scenarios were firstly analyzed, then 5G data was classified.Combining with the protection requirements of the life cycle of data, an innovative 5G data security labeling model based on graph database was proposed, which could meet the protection requirements of static classification and dynamic flow simultaneously.Based on this model, 5G data security protection mechanism was constructed from three aspects of node security, data flow monitoring and data security risk disposal, realizing life-cycle protection of 5G data.关键词：5G security;data security;data flow;data category;security model722|978|0更新时间：2024-06-05
- 摘要：To reflect the availability status of the Internet of things (IoT) under malware diffusion, an availability evaluation method of IoT based on the extended epidemic model SEIRD and Markov chain was proposed.According to actual states of IoT nodes, the classic epidemic model SIR was extended to establish the node state transition model SEIRD.From the dynamic change process of each state of IoT nodes, the dynamic probability equations of IoT nodes belonging to five states were constructed, the Markov matrix reflecting the state transition was obtained, and an availability calculation method of an IoT node was achieved.Taking typical star and cluster IoT topologies as examples, the availability evaluation methods of the whole IoT with different topologies were given.Experiments provide suggestions for administrators how to reasonably deploy the number of normal working nodes and routes.The research results have theoretical significance for improving IoT availability and promoting the successful IoT applications.关键词：IoT;malware;epidemic model;Markov chain;availability630|594|0更新时间：2024-06-05
- 摘要：Non-orthogonal multiple access (NOMA) has recently attracted wide attention as a promising multiple access technology adopted in 5G cellular networks.In order to improve the spectrum efficiency, coverage and anti-noise performance of NOMA technology, while reduce the energy consumption of the system, a simultaneous wireless information and power transfer (SWIPT) cooperative network uplink NOMA transmission system based on orthogonal index modulation multiple access (IMMA) technology was designed, hereafter was denoted as QIMMA-SWIPT.Specifically, the QIMMA system was formed by multiple remote users, and it improved the spectrum efficiency and anti-noise performance as well as expanded the communication coverage and reduced the energy consumption of the system by decoding and forwarding relay cooperative transmission with SWIPT technology.The theoretical upper bound of the average bit error rate of QIMMA-SWIPT was derived.Simulation and analysis demonstrate that, under the same spectrum efficiency, the bit error rate performance of the cooperative QIMMA-SWIPT system is better than that of the cooperative IMMA-SWIPT and SCMA-SWIPT systems.In addition, the effects of power cut factor and source-to-relay distance on bit error performance were also deeply analyzed.关键词：SWIPT;non-orthogonal multiple access;power-splitting;index modulation327|682|0更新时间：2024-06-05
- 摘要：Anomalous data, which deviates from a large number of normal data, has a negative impact and contains a risk on various systems.Anomaly detection can detect anomalies in the data and provide important support for the normal operation of various systems, which has important practical significance.An anomaly detection algorithm based on Gaussian mixture variational auto encoder network was proposed, in which a variational autoencoder was built to extract the features of the input data based on Gaussian mixture distribution, and using this variational autoencoder to construct a deep support vector network to compress the feature space and find the minimum hyper sphere to separate the normal data and the abnormal data.Anomalies can be detected by the score from the Euclidean distance from the feature of data to the center of the hypersphere.The proposed algorithm was evaluated on the benchmark datasets MNIST and Fashion-MNIST, and the corresponding average AUC are 0.954 and 0.937 respectively.The experimental results show that the proposed algorithm achieves preferable effects.关键词：anomaly detection;variational autoencoder;Gaussian mixture distribution;hypersphere353|812|0更新时间：2024-06-05
- 摘要：Network time delay is one of the key indexes to evaluate network performance.Principal component analysis (PCA) is a kind of multivariable analysis and declination algorithm commonly used in the field of data mining.Based on PCA analysis of time delay in large IP networks, aiming to find out the deep reason of time delay and the interdependencies among nodes of the network, a scientific and reasonable network time delay evaluation system was built, and effective suggestions for IP network construction and optimization were finally got.The off-line analysis of the historical network delay is only a preliminary application of the PCA.In the future, PCA can be applied to the real-time on-line monitoring and analysis of the network performance, such as network traffic, network delay, network packet loss, etc., in combination with the network topology, current network traffic direction, routing, distance and other related factors, thus the efficiency and quality of network operations can be further improved.关键词：network time delay;principal component analysis;coefficient matrix;proportion of variance328|412|0更新时间：2024-06-05
- 摘要：Compared with the predecessor standards, versatile video coding (VVC) significantly improves compression efficiency by a quadtree with nested multi-type tree (QTMT) structure but at the expense of extremely high coding complexity.To reduce the coding complexity of VVC, a fast QTMT partition method was proposed based on deep learning.Firstly, an attention-asymmetric convolutional neural network was proposed to predict the probability of partition modes.Then, the fast decision of partition modes based on the threshold was proposed.Finally, the cost of coding performance and time was proposed to obtain the optimal threshold, and the threshold decision method was proposed.Experimental results at different levels show that the proposed method achieves an average time saving of 48.62%/52.93%/62.01% with the negligible BDBR of 1.05%/1.33%/2.38%.Such results demonstrate that the proposed method significantly outperforms other state-of-the-art methods.关键词：VVC;QTMT;fast partition decision;deep learning515|625|0更新时间：2024-06-05
- 摘要：In order to reduce the peak-to-average power ratio (PAPR) and the implementation complexity of generalized frequency division multiplexing (GFDM) system, the TSLM algorithm based on T-transform and selective mapping (SLM) was proposed.The design idea of the TSLM algorithm was to use the SLM algorithm to increase the number of GFDM time-domain alternative signals to reduce the PAPR, and to use the T-transform to realize the joint operation of the Walsh-Hadamard transform and the inverse discrete Fourier transform to reduce the complexity of the system.To further reduce the PAPR of the GFDM system, the TCSLM algorithm combining the TSLM algorithm and the conversion vector (CV) was proposed, and the CV vector was used to increase the number of GFDM time-domain alternative signals.The results show that when the number of subcarriers is 64, the number of sub symbols is 3 and the number of phase sequences is 2, compared with the SLM algorithm, the implementation complexity of the TSLM and TCSLM algorithm decreases by about 21.9% and 60.9%, respectively.When the complementary cumulative distribution function (CCDF) is 10-3, the PAPR of the TSLM and TCSLM algorithm decreases by about 0.6 dB and 1 dB, respectively.The error performance of the TSLM and the TCSLM algorithm is improved by about 2 dB when the bit error rate is 10-3.关键词：generalized frequency division multiplexing;peak to average power ratio;selective mapping;conversion vector, bit error rate399|407|0更新时间：2024-06-05
- 摘要：Antenna azimuth was seen as a key factor in the quality of mobile communications, and its accuracy will directly affect the quality of network optimization.An antenna azimuth diagnosis method was proposed based on multi-layer perceptron.The azimuth was divided into 12 interval classes, each class covered a range of 30°, that was,[0, 30°) was recorded as class 0, …,[330°, 360°) was recorded as class 11.The multi-layer perceptron algorithm was used to identify the range of the antenna azimuth angle and automatically identify the angle range of the antenna azimuth angle, which provided effective data support for the network optimization engineer to determine the actual network coverage problem, and greatly reduced workload and labor cost in verifying antenna performance.Experimental results show that the method can effectively and quickly discriminate the antenna azimuth interval class, and the recognition accuracy reaches 92.6%, which is higher than the classification accuracy of random forest and logistic regression classification algorithms.关键词：antenna azimuth angle;multi-layer perceptron;back propagation algorithm;neural network;network optimization264|473|0更新时间：2024-06-05
- 摘要：The point cloud registration method can effectively complete the registration of point clouds with different overlap rates and various sizes, and ensure the accuracy of the 3D reconstruction model.To address the above issues, a partial overlapping point cloud registration method based on dynamic feature matching named PPCR was proposed.Firstly, the point cloud was divided into sub-point clouds based on the Euclidean distance segmentation method.Secondly, the features of sub-point clouds were extracted.Since the sizes of different point clouds are varied, the scales of the extracted features are also different.Thus, a dynamic time warping (DTW) algorithm was proposed to map the sub-point clouds.Finally, the registration algorithm was iterated to obtain the translation and rotation matrix between point clouds.This matrix was used to complete the registration and stitching between point clouds.Experimental results show that the proposed method can effectively solve the registration problems of partially overlapping point clouds and point clouds with different scales.关键词：lidar;overlapping point cloud;point cloud segmentation;point cloud mapping;point cloud registration630|732|0更新时间：2024-06-05
- 摘要：5G base station has a significant increase in its full-load power consumption compared to 4G base stations due to multiple transceiver channels, wide bandwidth, high traffic and high transmission power.In the early stage of 5G development, since there may be scenarios without users for a long time in the current network base stations, intermittent shutdown of the base stations can play a role in energy saving.However, the intermittent shutdown of the base station saves energy and condensation occurs inside the equipment , which will cause corrosion and burn down of devices and PCB, resulting in the failure of base station equipment.The basic principle of condensation was introduced, the condensation experiment was designed and the comparative verification was carried onto the base station equipment, the causes of condensation on the base station equipment were analyzed, and finally the suggestion for the use scheme of the base station equipment to avoid condensation was given.关键词：5G;base station equipment;condensation;intermittent shutdown;deep sleep474|999|0更新时间：2024-06-05
Research and Development
- 摘要：As many carriers are stopping SDH/MSTP investment, OTN networks will replace SDH networks gradually and extend to the edge of the metro network, thus introducing new requirements for OTN technologies.In view of the challenges and new services requirements of the development of the metro optical transport network, the M-OTN technology with the optical service unit (OSU) as the core and optimized for the metro application was proposed.The progress of standardization and main contents of OSU technical standards were introduced, including OSU frame structure and overheads, OSU management frames, OSU hitless bandwidth adjustment mechanism.The consideration on M-OTN equipment types and existing network evolution strategy was given.The M-OTN prototype systems from mainstream manufacturers were tested.Test results show that OSU technology has significant advantages in latency, hitless bandwidth adjustment and transport efficiency.关键词：M-OTN;OSU;hitless bandwidth adjustment829|878|0更新时间：2024-06-05
- 摘要：The power consumption of 5G UE is much serious than 4G UE due to larger bandwidth, massive MIMO, and higher data rate and has been one of the important reason affecting users’ experience of 5G network.3GPP has promoted the study and standardization of NR UE power saving techniques, which the R16 techniques is designed for RRC_connected mode and the started R17 techniques focus on RRC_idle mode.The power consumption of NR UE in RRC_idle was analyzed and compared with LTE UE.The power saving techniques to solve the power consumption in paging and tracking procedure were proposed and the power saving gain were also evaluated.The proposed techniques can reduce 5G UE power consumption and be applicable to future 5G commercial UE.关键词：UE power saving;RRC_Idle mode;paging;TRS764|861|0更新时间：2024-06-05
- 摘要：Wi-Fi 6 was the new name of IEEE 802.11ax by the Wi-Fi Alliance to facilitate the promotion of new Wi-Fi technology.Wi-Fi 6 technology focused on improving multi-user performance and efficiency in dense deployment scenario.Introducing OFDMA, UL MU-MIMO and other multi-user collaboration technologies, greatly increases system capacity and reduces transmission delay.The principles of OFDMA, MU-MIMO, MU-RTS/CTS technologies were described, the communication process in multi-user scenario was introduced in detail, and the UL and DL simultaneous user numbers of Wi-Fi 6 were analyzed in theory.Finally, the application potential of Wi-Fi 6 were discussed.关键词：Wi-Fi 6;OFDMA;MU-MIMO;multi-user352|776|0更新时间：2024-06-05
- 摘要：During the 4G construction period, there were problems such as lack of antenna coverage resources at the base station site, and difficulty in coordination with residential property management.In 5G era, it is difficult to add poles at existing sites.Therefore, it is urgent to propose a solution of common antenna of 4G/5G, and to deploy quickly.The solution of 4G/5G common antenna was discussed, and a suitable solution for China Telecom’s single pole network construction was proposed.It can reduce the cost of the tower renting and network operation.At the same time, it can prove the convenience and efficiency of 5G network deployment.关键词：4G/5G common antenna;single pole;passive All in One;passive + active All in One572|697|0更新时间：2024-06-05
- 摘要：5G has entered the stage of scale deployment, and indoor is one of the key scenes.With the evolution of new technology, indoor new coverage solutions emerge in endlessly, such as RRU/pRRU+RF power amplifier, multi-channel joint transceiver technology, frequency conversion system, etc.Compared with the traditional compartment coverage scheme, new coverage solutions have the characteristics of low cost and good performance.The technical principle, basic performance, key problems and industrial status of the new coverage solutions were innovatively and comprehensively analyzed, and the corresponding target scenarios and deployment suggestions were summarized through actual pilot verification.关键词：indoor new coverage solution;RF power amplifier;multi-channel combining;frequency conversion508|1455|0更新时间：2024-06-05
Engineering and Application
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