Published in last 1 year |  In last 2 years |  In last 3 years |  All
 Select Signal Detection and Channel Estimation in OTFS NAIKOTI Ashwitha, CHOCKALINGAM Ananthanarayanan ZTE Communications    2021, 19 (4): 16-33.   DOI: 10.12142/ZTECOM.202104003 Abstract （253）   HTML （8）    PDF （2749KB）（494）       Save Orthogonal time frequency space (OTFS) modulation is a recently proposed modulation scheme that exhibits robust performance in high-Doppler environments. It is a two-dimensional modulation scheme where information symbols are multiplexed in the delay-Doppler (DD) domain. Also, the channel is viewed in the DD domain where the channel response is sparse and time-invariant for a long time. This simplifies channel estimation in the DD domain. This paper presents an overview of the state-of-the-art approaches in OTFS signal detection and DD channel estimation. We classify the signal detection approaches into three categories, namely, low-complexity linear detection, approximate maximum a posteriori (MAP) detection, and deep neural network (DNN) based detection. Similarly, we classify the DD channel estimation approaches into three categories, namely, separate pilot approach, embedded pilot approach, and superimposed pilot approach. We compile and present an overview of some of the key algorithms under these categories and illustrate their performance and complexity attributes.
 Select Payload Encoding Representation from Transformer for Encrypted Traffic Classification HE Hongye, YANG Zhiguo, CHEN Xiangning ZTE Communications    2021, 19 (4): 90-97.   DOI: 10.12142/ZTECOM.202104010 Abstract （173）   HTML （23）    PDF （965KB）（209）       Save Traffic identification becomes more important, yet more challenging as related encryption techniques are rapidly developing nowadays. Unlike recent deep learning methods that apply image processing to solve such encrypted traffic problems, in this paper, we propose a method named Payload Encoding Representation from Transformer (PERT) to perform automatic traffic feature extraction using a state-of-the-art dynamic word embedding technique. By implementing traffic classification experiments on a public encrypted traffic data set and our captured Android HTTPS traffic, we prove the proposed method can achieve an obvious better effectiveness than other compared baselines. To the best of our knowledge, this is the first time the encrypted traffic classification with the dynamic word embedding has been addressed.
 Select Enabling Energy Efficiency in 5G Network LIU Zhuang, GAO Yin, LI Dapeng, CHEN Jiajun, HAN Jiren ZTE Communications    2021, 19 (1): 20-29.   DOI: 10.12142/ZTECOM.202101004 Abstract （168）   HTML （4）    PDF （1356KB）（216）       Save The mobile Internet and Internet of Things are considered the main driving forces of 5G, as they require an ultra-dense deployment of small base stations to meet the increasing traffic demands. 5G new radio (NR) access is designed to enable denser network deployments, while leading to a significant concern about the network energy consumption. Energy consumption is a main part of network operational expense (OPEX), and base stations work as the main energy consumption equipment in the radio access network (RAN). In order to achieve RAN energy efficiency (EE), switching off cells is a strategy to reduce the energy consumption of networks during off-peak conditions. This paper introduces NR cell switching on/off schemes in 3GPP to achieve energy efficiency in 5G RAN, including intra-system energy saving (ES) scheme and inter-system ES scheme. Additionally, NR architectural features including central unit/distributed unit (CU/DU) split and dual connectivity (DC) are also considered in NR energy saving. How to apply artificial intelligence (AI) into 5G networks is a new topic in 3GPP, and we also propose a machine learning (ML) based scheme to save energy by switching off the cell selected relying on the load prediction. According to the experiment results in the real wireless environment, the ML based ES scheme can reduce more power consumption than the conventional ES scheme without load prediction.
 Select Recent Developments of Transmissive Reconfigurable Intelligent Surfaces: A Review TANG Junwen, XU Shenheng, YANG Fan, LI Maokun ZTE Communications    2022, 20 (1): 21-27.   DOI: 10.12142/ZTECOM.202201004 Abstract （145）   HTML （12）    PDF （1869KB）（257）       Save Reconfigurable intelligent surface (RIS) is considered as one of the key technologies for the next-generation mobile communication systems. The transmissive RIS is able to achieve dynamic beamforming capability while transmitting an in-band RF signal through its aperture, and has promising prospects in various practical application scenarios. This paper reviews some of the latest developments of the transmissive RIS. The approaches for transmissive RIS designs are classified and described briefly. Numerous designs with different phase resolutions, such as 1-bit, 2-bit or continuous 360° phase shifts, are presented, with detailed discussions on their operating mechanisms and transmission performances. The design solutions for various transmissive RIS elements are summarized and compared.
 Select A Survey on Low Complexity Detectors for OTFS Systems ZHANG Zhengquan, LIU Heng, WANG Qianli, FAN Pingzhi ZTE Communications    2021, 19 (4): 3-15.   DOI: 10.12142/ZTECOM.202104002 Abstract （135）   HTML （11）    PDF （1427KB）（263）       Save The newly emerging orthogonal time frequency space (OTFS) modulation can obtain delay-Doppler diversity gain to significantly improve the system performance in high mobility wireless communication scenarios such as vehicle-to-everything (V2X), high-speed railway and unmanned aerial vehicles (UAV), by employing inverse symplectic finite Fourier transform (ISFFT) and symplectic finite Fourier transform (SFFT). However, OTFS modulation will dramatically increase system complexity, especially at the receiver side. Thus, designing low complexity OTFS receiver is a key issue for OTFS modulation to be adopted by new-generation wireless communication systems. In this paper, we review low complexity OTFS detectors and provide some insights on future researches. We firstly present the OTFS system model and basic principles, followed by an overview of OTFS detector structures, classifications and comparative discussion. We also survey the principles of OTFS detection algorithms. Furthermore, we discuss the design of hybrid OTFS and orthogonal frequency division multiplexing (OFDM) detectors in single user and multi-user multi-waveform communication systems. Finally, we address the main challenges in designing low complexity OTFS detectors and identify some future research directions.
 Select Dual‑Polarized RIS‑Based STBC Transmission with Polarization Coupling Analysis ZHOU Mingyong, CHEN Xiangyu, TANG Wankai, KE Jun Chen, JIN Shi, CHENG Qiang, CUI Tie Jun ZTE Communications    2022, 20 (1): 63-75.   DOI: 10.12142/ZTECOM.202201009 Abstract （131）   HTML （18）    PDF （1409KB）（225）       Save The rapid development of the reconfigurable intelligent surface (RIS) technology has given rise to a new paradigm of wireless transmitters. At present, most research works on RIS-based transmitters focus on single-polarized RISs. In this paper, we propose a dual-polarized RIS-based transmitter, which realizes 4-transmit space-time block coding (STBC) transmission by properly partitioning RIS’s unit cells and utilizing the degree of freedom of polarization. The proposed scheme is evaluated through a prototype system that utilizes a fabricated dual-polarized phase-adjustable RIS. In particular, the polarization coupling phenomenon in each unit cell of the employed dual-polarized RIS is modeled and analyzed. The experimental results are in good agreement with the theoretical modeling and analysis results, and an initial research effort is made on characterizing the polarization coupling property in the dual-polarized RIS.
 Select Advanced Space Laser Communication Technology on CubeSats LI Li, ZHANG Xuejiao, ZHANG Jianhua, XU Changzhi, JIN Yi ZTE Communications    2020, 18 (4): 45-54.   DOI: 10.12142/ZTECOM.202004007 Abstract （127）   HTML （16）    PDF （3658KB）（174）       Save The free space optical communication plays an important role in space-terrestrial integrated network due to its advantages including great improvement of data rate performance, low cost, security enhancement when compared with conventional radio frequency (RF) technology. Meanwhile, CubeSats become popular in low earth orbit (LEO) network because of the low cost, fast response and the possibility of constituting constellations and formations to execute missions that a single large satellite cannot do. However, it is a difficult task to build an optical communication link between the CubeSats. In this paper, the cutting-edge laser technology progress on the CubeSats is reviewed. The characters of laser link on the CubeSat and the key techniques in the laser communication terminal (LCT) design are demonstrated.
 Select General Introduction of Non-Terrestrial Networks for New Radio HAN Jiren, GAO Yin ZTE Communications    2022, 20 (S1): 72-78.   DOI: 10.12142/ZTECOM.2022S1010 Abstract （125）   HTML （11）    PDF （1266KB）（87）       Save In the new radio (NR) access technology, non-terrestrial networks (NTN) are introduced to meet the requirement of anywhere and anytime connections from the world market. With the introduction of NTN, the NR system is able to offer the wide-area coverage and ensure the service availability for users. In this paper, the general aspects of NTN are introduced, including the NTN architecture overview, the impact of NTN on next-generation radio access network (NG-RAN) interface functions, mobility scenarios and other NTN related issues. The current progress in 3GPP Release 17 is also provided.
 Select Recent Progress in Research and Development of Reconfigurable Intelligent Surface YUAN Yifei, GU Qi, WANG Anna, WU Dan, LI Ya ZTE Communications    2022, 20 (1): 3-13.   DOI: 10.12142/ZTECOM.202201002 Abstract （125）   HTML （21）    PDF （2269KB）（325）       Save We aim to provide a comprehensive overview of the progress in research and development of the reconfigurable intelligent surface (RIS) over the last 2–3 years in this paper, especially when the RIS is used as relays in next-generation mobile networks. Major areas of research in academia are outlined, including fundamental performance, channel estimation, joint optimization with antenna precoding at base stations, propagation channel modeling and meta-material devices of RIS elements. Development in industry is surveyed from the aspects of performance potentials and issues, realistic joint optimization algorithms, control mechanisms, field trials and related activities in standardization development organizations (SDOs). Our views on how to carry out the engineering-aspect study on RIS for 6G systems are also presented, which cover the realistic performance, the comparison with other topological improvements, approaches for channel modeling, factors for designing control mechanisms and the timeline for RIS standardization.
 Select Message Passing Based Detection for Orthogonal Time Frequency Space Modulation YUAN Zhengdao, LIU Fei, GUO Qinghua, WANG Zhongyong ZTE Communications    2021, 19 (4): 34-44.   DOI: 10.12142/ZTECOM.202104004 Abstract （119）   HTML （5）    PDF （2103KB）（171）       Save The orthogonal time frequency space (OTFS) modulation has emerged as a promising modulation scheme for wireless communications in high-mobility scenarios. An efficient detector is of paramount importance to harvesting the time and frequency diversities promised by OTFS. Recently, some message passing based detectors have been developed by exploiting the features of the OTFS channel matrices. In this paper, we provide an overview of some recent message passing based OTFS detectors, compare their performance, and shed some light on potential research on the design of message passing based OTFS receivers.
 Select End-to-End Chinese Entity Recognition Based on BERT-BiLSTM-ATT-CRF LI Daiyi, TU Yaofeng, ZHOU Xiangsheng, ZHANG Yangming, MA Zongmin ZTE Communications    2022, 20 (S1): 27-35.   DOI: 10.12142/ZTECOM.2022S1005 Abstract （109）   HTML （10）    PDF （436KB）（93）       Save Traditional named entity recognition methods need professional domain knowledge and a large amount of human participation to extract features, as well as the Chinese named entity recognition method based on a neural network model, which brings the problem that vector representation is too singular in the process of character vector representation. To solve the above problem, we propose a Chinese named entity recognition method based on the BERT-BiLSTM-ATT-CRF model. Firstly, we use the bidirectional encoder representations from transformers (BERT) pre-training language model to obtain the semantic vector of the word according to the context information of the word; Secondly, the word vectors trained by BERT are input into the bidirectional long-term and short-term memory network embedded with attention mechanism (BiLSTM-ATT) to capture the most important semantic information in the sentence; Finally, the conditional random field (CRF) is used to learn the dependence between adjacent tags to obtain the global optimal sentence level tag sequence. The experimental results show that the proposed model achieves state-of-the-art performance on both Microsoft Research Asia (MSRA) corpus and people’s daily corpus, with F1 values of 94.77% and 95.97% respectively.
 Select SVM for Constellation Shaped 8QAM PON System LI Zhongya, CHEN Rui, HUANG Xingang, ZHANG Junwen, NIU Wenqing, LU Qiuyi, CHI Nan ZTE Communications    2022, 20 (S1): 64-71.   DOI: 10.12142/ZTECOM.2022S1009 Abstract （107）   HTML （1）    PDF （3357KB）（37）       Save Nonlinearity impairments and distortions have been bothering the bandwidth constrained passive optical network (PON) system for a long time and limiting the development of capacity in the PON system. Unlike other works concentrating on the exploration of the complex equalization algorithm, we investigate the potential of constellation shaping joint support vector machine (SVM) classification scheme. At the transmitter side, the 8 quadrature amplitude modulation (8QAM) constellation is shaped into three designs to mitigate the influence of noise and distortions in the PON channel. On the receiver side, simple multi-class linear SVM classifiers are utilized to replace complex equalization methods. Simulation results show that with the bandwidth of 25 GHz and overall bitrate of 50 Gbit/s, at 10 dBm input optical power of a 20 km standard single mode fiber (SSMF), and under a hard-decision forward error correction (FEC) threshold, transmission can be realized by employing Circular (4, 4) shaped 8QAM joint SVM classifier at the maximal power budget of 37.5 dB.
 Select Kinetic Energy Harvesting Toward Battery-Free IoT: Fundamentals, Co-Design Necessity and Prospects LIANG Junrui, LI Xin, YANG Hailiang ZTE Communications    2021, 19 (1): 48-60.   DOI: 10.12142/ZTECOM.202101007 Abstract （106）   HTML （9）    PDF （1567KB）（365）       Save Energy harvesting (EH) technology is developed with the purpose of harnessing ambient energy in different physical forms. Although the available ambient energy is usually tiny, not comparable to the centralized power generation, it brings out the convenience of on-site power generation by drawing energy from local sources, which meets the emerging power demand of long-lasting, extensively-deployed, and maintenance-free Internet of Things (IoT). Kinetic energy harvesting (KEH) is one of the most promising EH solutions toward the realization of battery-free IoT. The KEH-based battery-free IoT can be extensively deployed in the smart home, smart building, and smart city scenarios, enabling perceptivity, intelligence, and connectivity in many infrastructures. This paper gives a brief introduction to the configurations and basic principles of practical KEH-IoT systems, including their mechanical, electrical, and computing parts. Although there are already a few commercial products in some specific application markets, the understanding and practice in the co-design and optimization of a single KEH-IoT device are far from mature, let alone the conceived multiagent energy-autonomous intelligent systems. Future research and development of the KEH-IoT system beckons for more exchange and collaboration among mechanical, electrical, and computer engineers toward general design guidelines to cope with these interdisciplinary engineering problems.
 Select Some Observations and Thoughts about Reconfigurable Intelligent Surface Application for 5G Evolution and 6G HOU Xiaolin, LI Xiang, WANG Xin, CHEN Lan, SUYAMA Satoshi ZTE Communications    2022, 20 (1): 14-20.   DOI: 10.12142/ZTECOM.202201003 Abstract （103）   HTML （15）    PDF （1684KB）（168）       Save Reconfigurable intelligent surface (RIS) is one of the hottest research topics for 5G evolution and 6G. It is expected that RIS can improve the system capacity and coverage with low cost and power consumption. This paper first discusses typical applications of RIS for 5G evolution and 6G, including RIS-aided smart channels and RIS-aided mega multiple-input multiple-output (MIMO). Then, several observations from RIS trials and system-level simulations are presented, especially those on the deployment strategy and the potential performance gain of RIS for coverage enhancement. The near-field effect and a two-step dynamic RIS beamforming method are also discussed. Finally, we summarize the challenges and opportunities of the RIS technology for 5G evolution and 6G, including hardware design, system and channel modeling, algorithm design and optimization, and standardization. We also suggest a step-by-step commercialization strategy as a conclusion.
 Select QoE Management for 5G New Radio ZHANG Man, LI Dapeng, LIU Zhuang, GAO Yin ZTE Communications    2021, 19 (3): 64-72.   DOI: 10.12142/ZTECOM.202103008 Abstract （100）   HTML （4）    PDF （428KB）（47）       Save Quality of Experience (QoE) is used to monitor the user experience of telecommunication services, which has been studied for a long time. In universal terrestrial radio access network (UTRAN), evolved UTRAN (E-UTRA) and Long Term Evolution (LTE), QoE has also been specified for the improvement of user experience. The 5G New Radio (NR) technology is designed for providing various types of new services, and therefore operators have strong demand to continuously upgrade the 5G network to provide sufficient and good QoE for corresponding services. With new emerging 5G services, 5G QoE management collection aims at specifying the mechanism to collect the experience parameters for the multimedia telephony service for IP multimedia subsystem (IMS), multimedia broadcast and multicast service (MBMS), virtual reality (VR), etc. Taking LTE QoE as a baseline, generic NR QoE management mechanisms for activation, deactivation, configuration, and reporting of QoE measurement are introduced in this paper. Additionally, some enhanced QoE features in NR are discussed, such as radio access network (RAN) overload handling, RAN-visible QoE, per-slice QoE measurement, radio-related measurement, and QoE continuity for mobility. This paper also introduces solutions to NR QoE, which concludes the progress of NR QoE in the 3rd Generation Partnership Project (3GPP).
 Select Satellite E2E Network Slicing Based on 5G Technology ZHANG Jing, WEI Xiao, CHENG Junfeng, FENG Xu ZTE Communications    2020, 18 (4): 26-33.   DOI: 10.12142/ZTECOM.202004005 Abstract （93）   HTML （561）    PDF （696KB）（124）       Save We investigate the design of satellite network slicing for the first time to provide customized services for the diversified applications, and propose a novel scheme for satellite end-to-end (E2E) network slicing based on 5G technology, which provides a view of common satellite network slicing and supports flexible network deployment between the satellite and the ground. Specifically, considering the limited satellite network resource and the characteristics of the satellite channel, we propose a novel satellite E2E network slicing architecture. Therein, the deployment of the network functions between the satellite and the ground is coordinately considered. Subsequently, the classification and the isolation technologies of satellite network sub-slices are proposed adaptively based on 5G technology to support resource allocation on demand. Then, we develop the management technologies for the satellite E2E network slicing including slicing key performance indicator (KPI) design, slicing deployment, and slicing management. Finally, the analysis of the challenges and future work shows the potential research in the future.
 Select Study on Security of 5G and Satellite Converged Communication Network YAN Xincheng, TENG Huiyun, PING Li, JIANG Zhihong, ZHOU Na ZTE Communications    2021, 19 (4): 79-89.   DOI: 10.12142/ZTECOM.202104009 Abstract （89）   HTML （7）    PDF （1924KB）（76）       Save The 5G and satellite converged communication network (5G SCCN) is an important component of the integration of satellite-terrestrial networks, the national science, and technology major projects towards 2030. Security is the key to ensuring its operation, but at present, the research in this area has just started in our country. Based on the network characteristics and security risks, we propose the security architecture of the 5G SCCN and systematically sort out the key protection technologies and improvement directions. In particular, unique thinking on the security of lightweight data communication and design reference for the 5G SCCN network architecture is presented. It is expected to provide a piece of reference for the follow-up 5G SCCN security technology research, standard evolution, and industrialization.
 Select Editorial: Special Topic on Federated Learning for IoT and Edge Computing ZTE Communications    2022, 20 (3): 1-2.   DOI: 10.12142/ZTECOM.202203001 Abstract （83）   HTML （2）    PDF （481KB）（56）       Save
 Select Robust Lane Detection and Tracking Based on Machine Vision FAN Guotian, LI Bo, HAN Qin, JIAO Rihua, QU Gang ZTE Communications    2020, 18 (4): 69-77.   DOI: 10.12142/ZTECOM.202004010 Abstract （82）   HTML （49）    PDF （5389KB）（111）       Save Lane detection based on machine vision, a key application in intelligent transportation， is generally characterized by gradient information of lane edge and plays an important role in advanced driver assistance systems (ADAS). However, gradient information varies with illumination changes. In the complex scenes of urban roads, highlight and shadow have effects on the detection, and non-lane objects also lead to false positives. In order to improve the accuracy of detection and meet the robustness requirement, this paper proposes a method of using top-hat transformation to enhance the contrast and filter out the interference of non-lane objects. And then the threshold segmentation algorithm based on local statistical information and Hough transform algorithm with polar angle and distance constraint are used for lane fitting. Finally, Kalman filter is used to correct lane lines which are wrong detected or missed. The experimental results show that computation times meet the real-time requirements, and the overall detection rate of the proposed method is 95.63%.
 Select Adaptability Analysis of IP Routing Protocol in Broadband LEO Constellation Systems SUN Chenhua, YIN Bo, LI Xudong, TIAN Xing, PANG Ce ZTE Communications    2020, 18 (4): 34-44.   DOI: 10.12142/ZTECOM.202004006 Abstract （77）   HTML （349）    PDF （4590KB）（52）       Save With the inclusion of satellite Internet as the information infrastructure in China’s “new infrastructure” category, relevant domestic industries and scientific research institutes have successively carried out the design of broadband low earth orbit (LEO) constellation systems and key technical research. As the core technology for the satellite-to-ground network communications of a broadband LEO constellation system, routing technology is extremely important for the efficient and reliable transmission of various service data. Focusing on the two important broadband LEO constellation systems in China, in-depth analysis and simulation of the high dynamics of the satellite-to-ground satellites are conducted in this paper to obtain more accurate network topology changes and characteristics; then the adaptability of the ground standard IP routing protocol to the broadband LEO constellation system is analyzed, and an LEO constellation simulation scenario is built with the Opnet software. The simulation results of the convergence performance of the standard IP routing protocol are produced. The results show that the IP protocol does not perform well for LEO satellite constellation networks. Based on the studies, some solutions are proposed to take full advantages of the characteristics of LEO satellite systems. These can also provide a reference for the choice of inter-satellite routing architecture and protocol technology for broadband LEO constellation in the future development.
 Select OTFS Enabled NOMA for MMTC Systems over LEO Satellite MA Yiyan, MA Guoyu, WANG Ning, ZHONG Zhangdui, AI Bo ZTE Communications    2021, 19 (4): 63-70.   DOI: 10.12142/ZTECOM.202104007 Abstract （76）   HTML （3）    PDF （528KB）（158）       Save As a complement of terrestrial networks, non-terrestrial networks (NTN) have advantages of wide-area coverage and service continuity. The NTN is potential to play an important role in the 5G new radio (NR) and beyond. To enable the massive machine type communications (mMTC), the low earth orbit (LEO) satellite is preferred due to its lower transmission delay and path loss. However, the LEO satellite may generate notable Doppler shifts to degrade the system performance. Recently, orthogonal time frequency space (OTFS) modulation has been proposed. It provides the opportunity to allocate delay Doppler (DD) domain resources, which is promising for mitigating the effect of high mobility. Besides, as the LEO satellite constellation systems such as Starlink are thriving, the space spectrum resources have become increasingly scarce. Therefore, non-orthogonal multiple access (NOMA) is considered as a candidate technology to realize mMTC with limited spectrum resources. In this paper, the application of OTFS enabled NOMA for mMTC over the LEO satellite is investigated. The LEO satellite based mMTC system and the OTFS-NOMA schemes are described. Subsequently, the challenges of applying OTFS and NOMA into LEO satellite mMTC systems are discussed. Finally, the potential technologies for the systems are investigated.
 Select DDoS Attack Detection Method for Space-Based Network Based on SDN Architecture JIA Min, SHU Yuejie, GUO Qing, GAO Zihe, XIE Suofei ZTE Communications    2020, 18 (4): 18-25.   DOI: 10.12142/ZTECOM.202004004 Abstract （74）   HTML （128）    PDF （1428KB）（78）       Save With the development of satellite communications, the number of satellite nodes is constantly increasing, which undoubtedly increases the difficulty of maintaining network security. Combining software defined network (SDN) with traditional space-based networks provides a new class of ideas for solving this problem. However, because of the highly centralized network management of the SDN controller, once the SDN controller is destroyed by network attacks, the network it manages will be paralyzed due to loss of control. One of the main security threats to SDN controllers is Distributed Denial of Service (DDoS) attacks, so how to detect DDoS attacks scientifically has become a hot topic among SDN security management. This paper proposes a DDoS attack detection method for space-based networks based on SDN architecture. This attack detection method combines the optimized Long Short-Term Memory (LSTM) deep learning model and Support Vector Machine (SVM), which can not only make classification judgments on the time series, but also achieve the purpose of detecting and judging through the flow characteristics of a period of time. In addition, it can reduce the detection time as well as the system burden.
 Select Programmable Metasurface for Simultaneously Wireless Information and Power Transfer System CHANG Mingyang, HAN Jiaqi, MA Xiangjin, XUE Hao, WU Xiaonan, LI Long, CUI Tiejun ZTE Communications    2022, 20 (2): 48-62.   DOI: 10.12142/ZTECOM.202202008 Abstract （74）   HTML （2）    PDF （5135KB）（61）       Save Implementing self-sustainable wireless communication systems is urgent and challenging for 5G and 6G technologies. In this paper, we elaborate on a system solution using the programmable metasurface (PMS) for simultaneous wireless information and power transfers (SWIPT), offering an optimized wireless energy management network. Both transmitting and receiving sides of the proposed solution are presented in detail. On the transmitting side, employing the wireless power transfer (WPT) technique, we present versatile power conveying strategies for near-field or far-field targets, single or multiple targets, and equal or unequal power targets. On the receiving side, utilizing the wireless energy harvesting (WEH) technique, we report our work on multi-functional rectifying metasurfaces that collect the wirelessly transmitted energy and the ambient energy. More importantly, a numerical model based on the plane-wave angular spectrum method is investigated to accurately calculate the radiation fields of PMS in the Fresnel and Fraunhofer regions. With this model, the efficiencies of WPT between the transmitter and the receiver are analyzed. Finally, future research directions are discussed, and integrated PMS for wireless information and wireless power is outlined.
 Select Cost-Effective Task Scheduling for Collaborative Cross-Edge Analytics ZHAO Kongyange, GAO Bin, ZHOU Zhi ZTE Communications    2021, 19 (2): 11-19.   DOI: 10.12142/ZTECOM.202102003 Abstract （71）   HTML （2）    PDF （648KB）（21）       Save Collaborative cross-edge analytics is a new computing paradigm in which Internet of Things (IoT) data analytics is performed across multiple geographically dispersed edge clouds. Existing work on collaborative cross-edge analytics mostly focuses on reducing either analytics response time or wide-area network (WAN) traffic volume. In this work, we empirically demonstrate that reducing either analytics response time or network traffic volume does not necessarily minimize the WAN traffic cost, due to the price heterogeneity of WAN links. To explicitly leverage the price heterogeneity for WAN cost minimization, we propose to schedule analytic tasks based on both price and bandwidth heterogeneities. Unfortunately, the problem of WAN cost minimization underperformance constraint is shown non-deterministic polynomial (NP)-hard and thus computationally intractable for large inputs. To address this challenge, we propose price- and performance-aware geo-distributed analytics (PPGA) , an efficient task scheduling heuristic that improves the cost-efficiency of IoT data analytic jobs across edge datacenters. We implement PPGA based on Apache Spark and conduct extensive experiments on Amazon EC2 to verify the efficacy of PPGA.
 Select Markovian Cascaded Channel Estimation for RIS Aided Massive MIMO Using 1‑Bit ADCs and Oversampling SHAO Zhichao, YAN Wenjing, YUAN Xiaojun ZTE Communications    2022, 20 (1): 48-56.   DOI: 10.12142/ZTECOM.202201007 Abstract （70）   HTML （8）    PDF （1115KB）（123）       Save A reconfigurable intelligent surface (RIS) aided massive multiple-input multiple-output (MIMO) system is considered, where the base station employs a large antenna array with low-cost and low-power 1-bit analog-to-digital converters (ADCs). To compensate for the performance loss caused by the coarse quantization, oversampling is applied at the receiver. The main challenge for the acquisition of cascaded channel state information in such a system is to handle the distortion caused by the 1-bit quantization and the sample correlation caused by oversampling. In this work, Bussgang decomposition is applied to deal with the coarse quantization, and a Markov chain is developed to characterize the banded structure of the oversampling filter. An approximate message-passing based algorithm is proposed for the estimation of the cascaded channels. Simulation results demonstrate that our proposed 1-bit systems with oversampling can approach the 2-bit systems in terms of the mean square error performance while the former consumes much less power at the receiver.
 Select Derivative-Based Envelope Design Technique for Wideband Envelope Tracking Power Amplifier with Digital Predistortion YI Xueya, CHEN Jixin, CHEN Peng, NING Dongfang, YU Chao ZTE Communications    2022, 20 (S1): 22-26.   DOI: 10.12142/ZTECOM.2022S1004 Abstract （67）   HTML （10）    PDF （878KB）（95）       Save A novel envelope design for an envelope tracking (ET) power amplifier (PA) based on its derivatives is proposed, which can trade well off between bandwidth reduction and tracking accuracy. This paper theoretically analyzes how to choose an envelope design that can track the original envelope closely and reduce its bandwidth, and then demonstrates an example to validate this idea. The generalized memory polynomial (GMP) model is applied to compensate for the nonlinearity of ET PA with the proposed envelope design. Experiments are carried out on an ET system that is operated with the center frequency of 3.5 GHz and excited by a 20 MHz LTE signal, which show that the proposed envelope design can make a good trade-off between envelope bandwidth and efficiency, and satisfactory linearization performance can be realized.
 Select RIS: Spatial‑Wideband Effect Analysis and Off‑Grid Channel Estimation JIAN Mengnan, ZHANG Nan, CHEN Yijian ZTE Communications    2022, 20 (1): 57-62.   DOI: 10.12142/ZTECOM.202201008 Abstract （65）   HTML （6）    PDF （1069KB）（92）       Save As a critical candidate technology for 5G-advanced and 6G, reconfigurable intelligent surfaces (RIS) have received extensive attention from academia and industry. RIS has the promising features of passiveness, reconfigurable ability, and low cost. RIS channel estimation faces the challenges of high matrix dimension, passive estimation, and spatial-wideband effect. In this article, we analyze the impact of the spatial-wideband effect on the RIS channel to account for the propagation delay across RIS elements and estimate sparse channel parameters such as angle and gain through a super-resolution compressive sensing (CS) algorithm. The simulation results explore the influence of the spatial-wideband effect on the RIS channel and verify the effectiveness of the proposed algorithm.
 Select Design of Raptor-Like Rate Compatible SC-LDPC Codes SHI Xiangyi, HAN Tongzhou, TIAN Hai, ZHAO Danfeng ZTE Communications    2022, 20 (S1): 16-21.   DOI: 10.12142/ZTECOM.2022S1003 Abstract （61）   HTML （170）    PDF （1213KB）（52）       Save This paper proposes a family of raptor-like rate-compatible spatially coupled low-density parity-check (RL-RC-SC-LDPC) codes from RL-RC-LDPC block codes. There are two important keys. One is the performance of the base matrix. RL-LDPC codes have been adopted in the technical specification of 5G new radio (5G-NR). We use the 5G NR LDPC code as the base matrix. The other is the edge coupling design. In this regard, we have designed a rate-compatible coupling algorithm, which can improve performance under multiple code rates. The constructed RL-RC-SC-LDPC code property requires a large coupling length $L$ and thus we improved the reciprocal channel approximation (RCA) algorithm and proposed a sliding window RCA algorithm. It can provide lower complexity and latency than RCA algorithm. The code family shows improved thresholds close to the Shannon limit and finite-length performance compared with 5G NR LDPC codes for the additive white Gaussian noise (AWGN) channel.
 Select Coded Orthogonal Time Frequency Space Modulation LIU Mengmeng, LI Shuangyang, ZHANG Chunqiong, WANG Boyu, BAI Baoming ZTE Communications    2021, 19 (4): 54-62.   DOI: 10.12142/ZTECOM.202104006 Abstract （56）   HTML （6）    PDF （1327KB）（118）       Save Orthogonal time frequency space (OTFS) modulation is a novel two-dimensional modulation scheme for high-Doppler fading scenarios, which is implemented in the delay-Doppler (DD) domain. In time and frequency selective channels, OTFS modulation is more robust than the popular orthogonal frequency division multiplexing (OFDM) modulation technique. To further improve transmission reliability, some channel coding schemes are used in the OTFS modulation system. In this paper, the coded OTFS modulation system is considered and introduced in detail. Furthermore, the performance of the uncoded/coded OTFS system and OFDM system is analyzed with different relative speeds, modulation schemes, and iterations. Simulation results show that the OTFS system has the potential of full diversity gain and better robustness under high mobility scenarios.
 Select RecCac: Recommendation-Empowered Cooperative Edge Caching for Internet of Things HAN Suning, LI Xiuhua, SUN Chuan, WANG Xiaofei, LEUNG Victor C. M. ZTE Communications    2021, 19 (2): 2-10.   DOI: 10.12142/ZTECOM.202102002 Abstract （55）   HTML （7）    PDF （1161KB）（37）       Save Edge caching is an emerging technology for supporting massive content access in mobile edge networks to address rapidly growing Internet of Things (IoT) services and content applications. However, the edge server is limited with the computation/storage capacity, which causes a low cache hit. Cooperative edge caching jointing neighbor edge servers is regarded as a promising technique to improve cache hit and reduce congestion of the networks. Further, recommender systems can provide personalized content services to meet user’s requirements in the entertainment-oriented mobile networks. Therefore, we investigate the issue of joint cooperative edge caching and recommender systems to achieve additional cache gains by the soft caching framework. To measure the cache profits, the optimization problem is formulated as a 0–1 Integer Linear Programming (ILP), which is NP-hard. Specifically, the method of processing content requests is defined as server actions, we determine the server actions to maximize the quality of experience (QoE). We propose a cache-friendly heuristic algorithm to solve it. Simulation results demonstrate that the proposed framework has superior performance in improving the QoE.
 Select Green Air-Ground Integrated Heterogeneous Network in 6G Era WU Huici, LI Hanjie, TAO Xiaofeng ZTE Communications    2021, 19 (1): 39-47.   DOI: 10.12142/ZTECOM.202101006 Abstract （55）   HTML （8）    PDF （1388KB）（66）       Save The research of three-dimensional integrated communication technology plays a key role in achieving the ubiquitous connectivity, ultra-high data rates, and emergency communications in the sixth generation (6G) networks. Aerial networking provides a promising solution to flexible, scalable, low-cost and reliable coverage for wireless devices. The integration of aerial network and terrestrial network has been an inevitable paradigm in the 6G era. However, energy-efficient communications and networking among aerial network and terrestrial network face great challenges. This paper is dedicated to discussing green communications of the air-ground integrated heterogeneous network (AGIHN). We first provide a brief introduction to the characteristics of AGIHN in 6G networks. Further, we analyze the challenges of green AGIHN from the aspects of green terrestrial networks and green aerial networks. Finally, several solutions to and key technologies of the green AGIHN are discussed.
 Select Space‑Terrestrial Integrated Architecture for Internet of Things ZHANG Gengxin, DING Xiaojin, QU Zhicheng ZTE Communications    2020, 18 (4): 3-9.   DOI: 10.12142/ZTECOM.202004002 Abstract （55）   HTML （233）    PDF （1092KB）（72）       Save To realize the ultimate vision of Internet of Things (IoT), only depending on terrestrial network is far from enough. As a supplement and extension of terrestrial network, satellite network can offer powerful support to realize the depth and breadth of the coverage. However, existing satellite networks are usually designed for particular purposes. Moreover, traditional satellite networks and terrestrial networks are developed and operated separately, consequently they cannot meet the need of network flexibility required by IoT. In this paper, a space-terrestrial architecture is conceived for constructing a space-terrestrial based IoT (ST-IoT) system. Additionally, a reliable identification procedure, an integrated access and communication procedure, as well as a clustering cooperative transmission strategy are also presented.
 Select Resource Allocation for Two‑Tier RIS‑Assisted Heterogeneous NOMA Networks XU Yongjun, YANG Zhaohui, HUANG Chongwen, YUEN Chau, GUI Guan ZTE Communications    2022, 20 (1): 36-47.   DOI: 10.12142/ZTECOM.202201006 Abstract （54）   HTML （1）    PDF （1761KB）（122）       Save Reconfigurable intelligent surface (RIS) as a promising technology has been proposed to change weak communication environments. However, most of the current resource allocation (RA) schemes have focused on RIS-assisted homogeneous networks, and there is still no open works about RA schemes of RIS-assisted heterogeneous networks (HetNets). In this paper, we design an RA scheme for a RIS-assisted HetNet with non-orthogonal multiple access to improve spectrum efficiency and transmission rates. In particular, we jointly optimize the transmit power of the small-cell base station and the phase-shift matrix of the RIS to maximize the sum rates of all small-cell users, subject to the unit modulus constraint, the minimum signal-to-interference-plus-noise ratio constraint, and the cross-tier interference constraint for protecting communication quality of microcell users. An efficient suboptimal RA scheme is proposed based on the alternating iteration approach, and successive convex approximation and logarithmic transformation approach. Simulation results verify the effectiveness of the proposed scheme in terms of data rates.
 Select Super Resolution Sensing Technique for Distributed Resource Monitoring on Edge Clouds YANG Han, CHEN Xu, ZHOU Zhi ZTE Communications    2021, 19 (3): 73-80.   DOI: 10.12142/ZTECOM.202103009 Abstract （53）   HTML （5）    PDF （1092KB）（54）       Save With the vigorous development of mobile networks, the number of devices at the network edge is growing rapidly and the massive amount of data generated by the devices brings a huge challenge of response latency and communication burden. Existing resource monitoring systems are widely deployed in cloud data centers, but it is difficult for traditional resource monitoring solutions to handle the massive data generated by thousands of edge devices. To address these challenges, we propose a super resolution sensing (SRS) method for distributed resource monitoring, which can be used to recover reliable and accurate high-frequency data from low-frequency sampled resource monitoring data. Experiments based on the proposed SRS model are also conducted and the experimental results show that it can effectively reduce the errors generated when recovering low-frequency monitoring data to high-frequency data, and verify the effectiveness and practical value of applying SRS method for resource monitoring on edge clouds.
 Select Orthogonal Time Frequency Space Modulation in Multiple-Antenna Systems WANG Dong, WANG Fanggang, LI Xiran, YUAN Pu, JIANG Dajie ZTE Communications    2021, 19 (4): 71-78.   DOI: 10.12142/ZTECOM.202104008 Abstract （52）   HTML （3）    PDF （1729KB）（169）       Save The application of the orthogonal time frequency space (OTFS) modulation in multiple-antenna systems is investigated. The diversity and/or the multiplexing gain can be achieved by deploying various multiple-antenna techniques, and thus the reliability and/or the spectral efficiency are improved correspondingly. We provide two classes of OTFS-based multiple-antenna approaches for both the open-loop and the closed-loop systems. Specifically, in the open-loop system, a transmitting diversity approach, which resembles the space-time coding technique, is proposed by allocating the information symbols appropriately in the delay-Doppler domain. In the closed-loop system, we adopt the Tomlinson-Harashima precoding in our derived delay-Doppler equivalent transmission model. Numerical evaluations demonstrate the advantages of applying the multiple-antenna techniques to the OTFS. At last, several challenges and opportunities are presented.
 Select Efficient Network Slicing with Dynamic Resource Allocation JI Hong, ZHANG Tianxiang, ZHANG Kai, WANG Wanyuan, WU Weiwei ZTE Communications    2021, 19 (1): 11-19.   DOI: 10.12142/ZTECOM.202101003 Abstract （52）   HTML （3）    PDF （1347KB）（49）       Save With the rapid development of wireless network technologies and the growing demand for a high quality of service (QoS), the effective management of network resources has attracted a lot of attention. For example, in a practical scenario, when a network shock occurs, a batch of affected flows needs to be rerouted to respond to the network shock to bring the entire network deployment back to the optimal state, and in the process of rerouting a batch of flows, the entire response time needs to be as short as possible. Specifically, we reduce the time consumed for routing by slicing, but the routing success rate after slicing is reduced compared with the unsliced case. In this context, we propose a two-stage dynamic network resource allocation framework that first makes decisions on the slices to which flows are assigned, and coordinates resources among slices to ensure a comparable routing success rate as in the unsliced case, while taking advantage of the time efficiency gains from slicing.
 Select IRS‑Enabled Spectrum Sharing: Interference Modeling, Channel Estimation and Robust Passive Beamforming GUAN Xinrong, WU Qingqing ZTE Communications    2022, 20 (1): 28-35.   DOI: 10.12142/ZTECOM.202201005 Abstract （52）   HTML （4）    PDF （1134KB）（86）       Save Intelligent reflecting surface (IRS), with its unique capability of smartly reconfiguring wireless channels, provides a new solution to improving spectrum efficiency, reducing energy consumption and saving deployment/hardware cost for future wireless networks. In this paper, IRS-enabled spectrum sharing is investigated, from the perspectives of interference modeling, efficient channel estimation and robust passive beamforming design. Specifically, we first characterize the interference in a spectrum sharing system consisting of a single primary user (PU) pair and a single secondary user (SU) pair, and extend it to the large-scale network by leveraging the Poisson point process (PPP). Then, we propose an efficient channel estimation framework based on decoupling the cascaded IRS channels. Moreover, the tradeoff between spectrum efficiency and energy efficiency is derived from the view of channel estimation accuracy. Finally, we discuss the robust passive beamforming design in presence of imperfect channel estimation and nonideal/discrete phase shifts. It is hoped that this paper provides useful guidance for unlocking the full potential of IRS for achieving efficient spectrum sharing for future wireless networks.
 Select High-Power Simultaneous Wireless Information and Power Transfer: Injection-Locked Magnetron Technology YANG Bo, MITANI Tomohiko, SHINOHARA Naoki, ZHANG Huaiqing ZTE Communications    2022, 20 (2): 3-12.   DOI: 10.12142/ZTECOM.202202002 Abstract （51）   HTML （19）    PDF （4645KB）（68）       Save Applications using simultaneous wireless information and power transfer (SWIPT) have increased significantly. Wireless communication technologies can be combined with the Internet of Things to develop many innovative applications using SWIPT, which is mainly based on wireless energy harvesting from electromagnetic waves used in communications. Wireless power transfer that uses magnetrons has been developed for communication technologies. Injection-locked magnetrons that can be used to facilitate high-power SWIPT for several devices are reviewed in this paper. This new technology is expected to pave the way for promoting the application of SWIPT in a wide range of fields.
 Select Editorial: Special Topic on Future Advanced Satellite Communication Systems and Applications ZTE Communications    2020, 18 (4): 1-2.   DOI: 10.12142/ZTECOM.202004001 Abstract （51）   HTML （16）    PDF （487KB）（37）       Save
 Select An Improved Parasitic Parameter Extraction Method for InP HEMT DUAN Lanyan, LU Hongliang, QI Junjun, ZHANG Yuming, ZHANG Yimen ZTE Communications    2022, 20 (S1): 1-6.   DOI: 10.12142/ZTECOM.2022S1001 Abstract （51）   HTML （180）    PDF （2023KB）（85）       Save An improved parasitic parameter extraction method for InP high electron mobility transistor (HEMT) is presented. Parasitic parameter extraction is the first step of model parameter extraction and its accuracy has a great impact on the subsequent internal parameter extraction. It is necessary to accurately determine and effectively eliminate the parasitic effect, so as to avoid the error propagation to the internal circuit parameters. In this paper, in order to obtain higher accuracy of parasitic parameters, parasitic parameters are extracted based on traditional analytical method and optimization algorithm to obtain the best parasitic parameters. The validity of the proposed parasitic parameter extraction method is verified with excellent agreement between the measured and modeled S-parameters up to 40 GHz for InP HEMT. In 0.1–40 GHz InP HEMT, the average relative error of the optimization algorithm is about 9% higher than that of the analysis method, which verifies the validity of the parasitic parameter extraction method. The extraction of parasitic parameters not only provides a foundation for the high-precision extraction of small signal intrinsic parameters of HEMT devices, but also lays a foundation for the high-precision extraction of equivalent circuit model parameters of large signal and noise signals of HEMT devices.