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    6G TOWARDS 2030: FROM KEY TECHNOLOGY TO NETWORK ARCHITECTURE
  • 6G TOWARDS 2030: FROM KEY TECHNOLOGY TO NETWORK ARCHITECTURE
    Na Li, Guangyi Liu, Huimin Zhang, Quan Zhao, Yun Zhao, Zhou Tong, Yingying Wang, Junshuai Sun
    2022, 19(3): 1-15.
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    The convergence of information, communication, and data technologies (ICDT) has been identified as one of the developing trends of the sixth generation(6G) network. Service-based architecture (SBA) as one of the promising information technology, has been preliminarily introduced into the fifth generation (5G) core network (CN) and successfully commercialized, which verifies its feasibility and effectiveness. However, SBA mainly focuses on the control plane of CN at present and the SBA-CN user plane is being studied by the industry. In addition to further evolving the SBA-CN, SBA radio access network (RAN) should also be considered to enable an end-toend SBA, so as to meet more comprehensive and extreme requirements of future applications, as well as support fast rollout requirements of RAN devices.
  • 6G TOWARDS 2030: FROM KEY TECHNOLOGY TO NETWORK ARCHITECTURE
    Zheng Hu, Ping Zhang, Chunhong Zhang, Benhui Zhuang, Jianhua Zhang, Shangjing Lin, Tao Sun
    2022, 19(3): 16-35.
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    Sixth Generation (6G) wireless communication network has been expected to provide global coverage, enhanced spectral efficiency, and AI(Artificial Intelligence)-native intelligence, etc. To meet these requirements, the computational concept of Decision-Making of cognition intelligence, its implementation framework adapting to foreseen innovations on networks and services, and its empirical evaluations are key techniques to guarantee the generation-agnostic intelligence evolution of wireless communication networks. In this paper, we propose an Intelligent Decision Making (IDM) framework, acting as the role of network brain, based on Reinforcement Learning modelling philosophy to empower autonomous intelligence evolution capability to 6G network. Besides, usage scenarios and simulation demonstrate the generality and efficiency of IDM. We hope that some of the ideas of IDM will assist the research of 6G network in a new or different light.
  • 6G TOWARDS 2030: FROM KEY TECHNOLOGY TO NETWORK ARCHITECTURE
    Juan Deng, Kaicong Tian, Qingbi Zheng, Jielin Bai, Kuo Cui, Yitong Liu, Guangyi Liu
    2022, 19(3): 36-49.
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    In 5G networks, optimization of antenna beam weights of base stations has become the key application of AI for network optimization. For 6G, higher frequency bands and much denser cells are expected, and the importance of automatic and accurate beamforming assisted by AI will become more prominent. In existing network, servers are “patched” to network equipment to act as a centralized brain for model training and inference leading to high transmission overhead, large inference latency and potential risks of data security. Decentralized architectures have been proposed to achieve flexible parameter configuration and fast local response, but it is inefficient in collecting and sharing global information among base stations. In this paper, we propose a novel solution based on a collaborative cloud edge architecture for multi-cell joint beamforming optimization. We analyze the performance and costs of the proposed solution with two other architectural solutions by simulation. Compared with the centralized solution, our solution improves prediction accuracy by 24.66%, and reduces storage cost by 83.82%. Compared with the decentralized solution, our solution improves prediction accuracy by 68.26%, and improves coverage performance by 0.4dB. At last, the future research work is prospected.
  • 6G TOWARDS 2030: FROM KEY TECHNOLOGY TO NETWORK ARCHITECTURE
    Borui Zhao, Qimei Cui, Shengyuan Liang, Jinli Zhai, Yanzhao Hou, Xueqing Huang, Miao Pan, Xiaofeng Tao
    2022, 19(3): 50-69.
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    As Information, Communications, and Data Technology (ICDT) are deeply integrated, the research of 6G gradually rises. Meanwhile, federated learning (FL) as a distributed artificial intelligence (AI) framework is generally believed to be the most promising solution to achieve “Native AI” in 6G. While the adoption of energy as a metric in AI and wireless networks is emerging, most studies still focused on obtaining high levels of accuracy, with little consideration on new features of future networks and their possible impact on energy consumption. To address this issue, this article focuses on green concerns in FL over 6G. We first analyze and summarize major energy consumption challenges caused by technical characteristics of FL and the dynamical heterogeneity of 6G networks, and model the energy consumption in FL over 6G from aspects of computation and communication. We classify and summarize the basic ways to reduce energy, and present several feasible green designs for FL-based 6G network architecture from three perspectives. According to the simulation results, we provide a useful guideline to researchers that different schemes should be used to achieve the minimum energy consumption at a reasonable cost of learning accuracy for different network scenarios and service requirements in FL-based 6G network.
  • 6G TOWARDS 2030: FROM KEY TECHNOLOGY TO NETWORK ARCHITECTURE
    Yuanjie Li, Jincheng Dai, Zhongwei Si, Kai Niu, Chao Dong, Jiaru Lin, Sen Wang, Yifei Yuan
    2022, 19(3): 70-87.
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    Unsourced multiple access (UMA) is a multi-access technology for massive, low-power, uncoordinated, and unsourced Machine Type Communication (MTC) networks. It ensures transmission reliability under the premise of high energy efficiency. Based on the analysis of the 6G MTC key performance indicators (KPIs) and scenario characteristics, this paper summarizes its requirements for radio access networks. Following this, the existing multiple access models are analyzed under these standards to determine UMA's advantages for 6G MTC according to its design characteristics. The critical technology of UMA is the design of its multiple-access coding scheme. Therefore, the existing UMA coding schemes from different coding paradigms are further summarized and compared. In particular, this paper comprehensively considers the energy efficiency and computational complexity of these schemes, studies the changes of the above two indexes with the increase of access scale, and considers the trade-off between the two. It is revealed by the above analysis that some guiding rules of UMA coding design. Finally, the open problems and potentials in this field are given for future research.
  • 6G TOWARDS 2030: FROM KEY TECHNOLOGY TO NETWORK ARCHITECTURE
    Mengting Lou, Jing Jin, Hanning Wang, Dan Wu, Liang Xia, Qixing Wang, Yifei Yuan, Jiangzhou Wang
    2022, 19(3): 88-100.
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    Massive multiple-input multiple-output (MIMO) technology enables higher data rate transmission in the future mobile communications. However, exploiting a large number of antenna elements at base station (BS) makes effective implementation of massive MIMO challenging, due to the size and weight limits of the masssive MIMO that are located on each BS. Therefore, in order to miniaturize the massive MIMO, it is crucial to reduce the number of antenna elements via effective methods such as sparse array synthesis. In this paper, a multiple-pattern synthesis is considered towards convex optimization (CO). The joint convex optimization (JCO) based synthesis is proposed to construct a codebook for beamforming. Then, a criterion containing multiple constraints is developed, in which the sparse array is required to fullfill all constraints. Finally, extensive evaluations are performed under realistic simulation settings. The results show that with the same number of antenna elements, sparse array using the proposed JCO-based synthesis outperforms not only the uniform array, but also the sparse array with the existing CO-based synthesis method. Furthermore, with a half of the number of antenna elements that on the uniform array, the performance of the JCO-based sparse array approaches to that of the uniform array.
  • 6G TOWARDS 2030: FROM KEY TECHNOLOGY TO NETWORK ARCHITECTURE
    Yanfei Dong, Jincheng Dai, Kai Niu, Sen Wang, Yifei Yuan
    2022, 19(3): 101-115.
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    In order to provide ultra low-latency and high energy-efficient communication for intelligences, the sixth generation (6G) wireless communication networks need to break out of the dilemma of the depleting gain of the separated optimization paradigm. In this context, this paper provides a comprehensive tutorial that overview how joint source-channel coding (JSCC) can be employed for improving overall system performance. For the purpose, we first introduce the communication requirements and performance metrics for 6G. Then, we provide an overview of the source-channel separation theorem and why it may not hold in practical applications. In addition, we focus on two new JSCC schemes called the double low-density parity-check (LDPC) codes and the double polar codes, respectively, giving their detailed coding and decoding processes and corresponding performance simulations. In a nutshell, this paper constitutes a tutorial on the JSCC scheme tailored to the needs of future 6G communications.
  • 6G TOWARDS 2030: FROM KEY TECHNOLOGY TO NETWORK ARCHITECTURE
    Dong Wang, Bule Sun, Fanggang Wang, Xiran Li, Pu Yuan, Dajie Jiang
    2022, 19(3): 116-128.
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    This paper investigates the transmission scheme of the orthogonal time frequency space (OTFS) system with multiple antennas. Previous works have studied the multi-antenna transmitter diversity scheme with the ideal pulse shaping in OTFS systems assuming the wireless channels of two consecutive frames duration are invariant. However, the ideal pulse shaping can not be realized in practice and the channel varies rapidly in two consecutive frames in the high-speed mobility scenarios. To this end, we redesign the multi-antenna transmitter diversity scheme to ensure its practicability in the rectangular-pulse-based OTFS systems. At first, the information symbols of each antenna are divided into two half frames along the Doppler domain. Then, the guard symbols are carefully arranged to eliminate the interference between two half frames, and to ensure the equivalent channels of two half frames being identical. By considering the positions of the guard symbols, the transmission codeword is designed and a low complexity linear detection is proposed. Finally, simulation results validate that the bit error rate performance of the proposed scheme has the superiority over the existing works.
  • AI-EMPOWERED FUTURE COMMUNICATION NETWORKS
  • AI-EMPOWERED FUTURE COMMUNICATION NETWORKS
    DePeng Jin, Xiaoming Tao, Xiaofeng Zhong, Jintao Wang
    2022, 19(3): 129-131.
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  • 6G TOWARDS 2030: FROM KEY TECHNOLOGY TO NETWORK ARCHITECTURE
  • 6G TOWARDS 2030: FROM KEY TECHNOLOGY TO NETWORK ARCHITECTURE
    Fubin Wang, Xuan Huang, Fang Yang, Hui Yang, Jun Wang, Jian Song
    2022, 19(3): 132-144.
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    The ubiquitous deployment and restricted consumption are the requirements restricting the development of Internet of Things. Thus, a promising technology named Internet of Lamps (IoL) is discussed in this paper to address these challenges. Compared with other communication networks, the remarkable advantage of IoL is that it can make full use of the existing lighting networks with sufficient power supply. The lamps can be connected to the Internet through wired power line communication and/or wireless communication, while the integration of integrated sensing, hybrid interconnection, and intelligent illumination is realized. In this paper, the IoL is discussed from three aspects including sensing layer, network layer, and application layer, realizing the comprehensive upgrade based on the conventional communication and illumination systems. Meanwhile, several novel technologies of IoL are discussed based on the requirements of sensing, communication, and control, which have put forward practical solutions to the issues faced by IoL. Moreover, the challenges and opportunities for IoL are highlighted from various parts of the system structure, so as to provide future insights and potential trends for researchers in this field.
  • 6G TOWARDS 2030: FROM KEY TECHNOLOGY TO NETWORK ARCHITECTURE
    Xiaofeng Zhong, Chenchen Fan, Shidong Zhou
    2022, 19(3): 145-157.
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    Compared with wired communication, the wireless communication link is more vulnerable to be attacked or eavesdropped because of its broadcast nature. To prevent eavesdropping, many researches on transmission techniques or cryptographic methods are carried out. This paper proposes a new index parameter named as eavesdropping area, to evaluate the anti-eavesdropping performance of wireless system. Given the locations of legitimate transmitter and receiver, eavesdropping area index describes the total area of eavesdropping regions where messages can be wiretapped in the whole evaluating region. This paper gives detailed explanations about its concept and deduces mathematical formulas about performance curves based on region classification. Corresponding key system parameters are analyzed, including the characteristics of eavesdropping region, transmitted beam pattern, beam direction, receiver sensitivity, eavesdropping sensitivity, path loss exponent and so on. The proposed index can give an insight on the confirmation of high-risk eavesdropping region and formulating optimal transmitting scheme for the confidential communications to decrease the eavesdropping probability.
  • 6G TOWARDS 2030: FROM KEY TECHNOLOGY TO NETWORK ARCHITECTURE
    Xuantao Lyu, Wei Feng, Ning Ge, Xianbin Wang
    2022, 19(3): 158-171.
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    The highly dynamic channel (HDC) in an extremely dynamic environment mainly has fast time-varying nonstationary characteristics. In this article, we focus on the most difficult HDC case, where the channel coherence time is less than the symbol period. To this end, we propose a symbol detector based on a long short-term memory (LSTM) neural network. Taking the sampling sequence of each received symbol as the LSTM unit's input data has the advantage of making full use of received information to obtain better performance. In addition, using the basic expansion model (BEM) as the preprocessing unit significantly reduces the number of neural network parameters. Finally, the simulation part uses the highly dynamic plasma sheath channel (HDPSC) data measured from shock tube experiments. The results show that the proposed BEM-LSTM-based detector has better performance and does not require channel estimation or channel model information.
  • 6G TOWARDS 2030: FROM KEY TECHNOLOGY TO NETWORK ARCHITECTURE
    Zhaohui Huang, Dongxuan He, Jiaxuan Chen, Zhaocheng Wang, Sheng Chen
    2022, 19(3): 172-180.
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    Terahertz wireless communication has been regarded as an emerging technology to satisfy the ever-increasing demand of ultra-high-speed wireless communications. However, affected by the imperfections of cheap and energy-efficient Terahertz devices, Terahertz signals suffer from serve hybrid distortions, including in-phase/quadrature imbalance, phase noise and nonlinearity, which degrade the demodulation performance significantly. To improve the robustness against these hybrid distortions, an improved autoencoder is proposed, which includes coding the transmitted symbols at the transmitter and decoding the corresponding signals at the receiver. Moreover, due to the lack of information of Terahertz channel during the training of the autoencoder, a fitting network is proposed to approximate the characteristics of Terahertz channel, which provides an approximation of the gradients of loss. Simulation results show that our proposed autoencoder with fitting network can recover the transmitted symbols under serious hybrid distortions, and improves the demodulation performance significantly.
  • 6G TOWARDS 2030: FROM KEY TECHNOLOGY TO NETWORK ARCHITECTURE
    Chenmin Sha, Shidong Zhou
    2022, 19(3): 181-191.
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    We try to extend the current configured-grant (CG) uplink scheme in 5G New Radio (NR) to support massive potential users and study activity detection under this scenario. Characteristics of the continuously varying channel and the multiple repetition scheme are utilized to improve the detection accuracy, which can be an enhancement to existing activity detection algorithms. Numerical results under 3GPP TDL (Tapped Delay Line) fading channel show the superiority of our algorithm. And system-level simulation reveals that enhancements on activity detection can improve reliability and reduce latency.
  • 6G TOWARDS 2030: FROM KEY TECHNOLOGY TO NETWORK ARCHITECTURE
    Chao Zhang, Kewu Peng, Zhitong He, Yonglin Xue, Hui Yang
    2022, 19(3): 192-201.
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    As the 2nd generation digital terrestrial television broadcasting (DTTB) standard, digital terrestrial/television multimedia broadcasting - advanced (DTMB-A) can provide higher spectrum efficiency and transmission reliability by adopting flexible frame structure and advanced forward error correction coding compared with the 1st generation DTTB systems. In order to increase the flexibility and robustness of the DTTB network, the frequency reuse scheme of factor one (reuse-1) is proposed, where the same RF channel is used by different stations covering the adjacent service areas.However, it demands a very low carrier-to-noise ratio (C/N) threshold below 0 dB at the DTTB physical layer. In this paper, a robust broadcasting technique is proposed based on DTMB-A with newly designed low-rate low density parity check (LDPC) codes. By adopting quasi-cyclic (QC) Raptor-like structure and progressive lifting method, the high performance low-rate LDPC codes are designed supporting multiple code lengths. Both density-evolution analyses and laboratory measurements demonstrate that DTMB-A with low-rate coding can complete the demodulation reliably with the C/N threshold below 0 dB, which is one important necessary condition to support frequency reuse-1 scheme.
  • THEORIES & SECURITY
  • THEORIES & SECURITY
    Jielun Zhang, Fuhao Li, Feng Ye
    2022, 19(3): 202-214.
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    Network traffic classification is essential in supporting network measurement and management. Many existing traffic classification approaches provide application-level results regardless of the network quality of service (QoS) requirements. In practice, traffic flows from the same application may have irregular network behaviors that should be identified to various QoS classes for best network resource management. To address the issues, we propose to conduct traffic classification with two newly defined QoS-aware features, i.e., inter-APP similarity and intra-APP diversity. The inter-APP similarity represents the close QoS association between the traffic flows that originate from the different Internet applications. The intra-APP diversity describes the QoS variety of the traffic even among those originated from the same Internet application. The core of performing the QoS-aware feature extraction is a Long-Short Term Memory neural network based Autoencoder (LSTM-AE). The QoS-aware features extracted by the encoder part of the LSTM-AE are then clustered into the corresponding QoS classes. Real-life data from multiple applications are collected to evaluate the proposed QoS-aware network traffic classification approach. The evaluation results demonstrate the efficacy of the extracted QoS-aware features in supporting the traffic classification, which can further contribute to future network measurement and management.
  • THEORIES & SECURITY
    Yi Wang, Yubo Peng, Li Chen, Yanzhong Duan, Jing Li
    2022, 19(3): 215-229.
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    Wireless sensor networks are widely used in today's fields, such as scientific research, industry and agriculture. However, due to the influence of its geographical location and the problems of low coverage and waste of resources caused by random placement, it is very important to adopt appropriate strategies to improve its coverage. To this end, an improved GND-DE (Global and Neighborhood Difference Guided DE) algorithm is proposed. This algorithm uses both the global topology structure and the neighborhood topology structure, combined with the evaluation of contemporary optimization results, and selects the results from the two topology structures. The value-dominant individual, the individual to be evolved and the two dominant individuals calculate the difference operator corresponding to the two topological structures; a diversity neighborhood topology is proposed for the creation of the neighborhood topology; at the same time, the algorithm step size factor F is adaptively adjusted and the JADE external archive mutation strategy is introduced to eliminate the possibility of algorithm search stagnation. In order to verify the effectiveness of its improved algorithm, compared with other mainstream improved algorithms on the CEC2017 test set, it shows that its optimization efficiency and convergence are better than other comparison algorithms; finally, GND-DE is applied to WSN node coverage optimization, which proves the feasibility of its optimization strategy.
  • THEORIES & SECURITY
    Xinhua Jiang, Ning Li, Yan Guo, Jie Liu, Cong Wang
    2022, 19(3): 230-244.
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    In the multi-target localization based on Compressed Sensing (CS), the sensing matrix's characteristic is significant to the localization accuracy. To improve the CS-based localization approach's performance, we propose a sensing matrix optimization method in this paper, which considers the optimization under the guidance of the $t\%$-averaged mutual coherence. First, we study sensing matrix optimization and model it as a constrained combinatorial optimization problem. Second, the $t\%$-averaged mutual coherence is adopted as the optimality index to evaluate the quality of different sensing matrixes, where the threshold $t$ is derived through the K-means clustering. With the settled optimality index, a hybrid metaheuristic algorithm named Genetic Algorithm-Tabu Local Search (GA-TLS) is proposed to address the combinatorial optimization problem to obtain the final optimized sensing matrix. Extensive simulation results reveal that the CS localization approaches using different recovery algorithms benefit from the proposed sensing matrix optimization method, with much less localization error compared to the traditional sensing matrix optimization methods.
  • EMERGING TECHNOLOGIES & APPLICATIONS
  • EMERGING TECHNOLOGIES & APPLICATIONS
    Junhua Wu, Xiaofei Sheng, Guangshun Li, Kan Yu, Junke Liu
    2022, 19(3): 245-257.
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    Edge computing is a highly virtualized paradigm that can services the Internet of Things(IoT) devices more efficiently. It is a non-trivial extension of cloud computing, which can not only meet the big data processing requirements of cloud computing, but also collect and analyze distributed data. However, it inherits many security and privacy challenges of cloud computing, such as: authentication and access control. To address these problem, we proposed a new efficient privacy-preserving aggregation scheme for edge computing. Our scheme consists of two steps. First, we divided the data of the end users with the Simulated Annealing Module Partition (SAMP) algorithm. And then, the end sensors and edge nodes performed respectively differential aggregation mechanism with the Differential Aggregation Encryption (DAE) algorithm which can make noise interference and encryption algorithm with trusted authority (TA). Experiment results show that the DAE can preserve user privacy, and has significantly less computation and communication overhead than existing approaches.
  • EMERGING TECHNOLOGIES & APPLICATIONS
    Zhiwei Liu, Yang Cao, Peng Gao, Xinhai Hua, Dongcheng Zhang, Tao Jiang
    2022, 19(3): 258-278.
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    Introducing multi-UAV network with flexible deployment into mobile edge computing(MEC) can effectively improve the quality of service of Internet-of-Things services, reduce the coverage cost and resource waste rate of edge nodes, and also bring some challenges. This paper first introduces the current situation and pain points of mobile edge computing, then analyzes the significance and value of using multi-UAV network to assist mobile edge computing, and summarizes its key technologies and typical applications. In the end, some open research problems and technology prospects of multi-UAV network assisted intelligent edge computing are put forward, which provide new ideas for the future development of this field.
  • EMERGING TECHNOLOGIES & APPLICATIONS
    Chengwen Zhang, LiankaiWang, Libin Jiao, Shipeng Wang, Jun Shi, Jia Yue
    2022, 19(3): 279-289.
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    In recent years, LoRa has been extensively researched in the satellite Internet of Things (IoT). However, the multiple access technology of LoRa is still one of the bottlenecks of satellite IoT. To improve the multiple access performance of LoRa satellite IoT, based on the orthogonality of LoRa symbols in the fractional domain, this paper proposes a low complexity Orthogonal LoRa Multiple Access (OLMA) algorithm for multiple LoRa users occupying the same frequency bandwidth. The algorithm introduces the address code to divide the fractional bandwidth into multiple parts, and the OLMA users with different address codes occupy different parts to transmit the information code, thus avoiding mutual interference caused by collisions in the same frequency bandwidth. The multiple access capability of OLMA can be flexibly configured only by simply adjusting the length of the address code according to the actual application requirements of data transmission. Theoretical analysis and simulation results show that the OLMA algorithm can greatly improve the multiple access capability and the total transmission bit rate of LoRa IoT without changing the existing LoRa modulation parameters and process.