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    20 October 2022, Volume 38 Issue 10
    Review
    Research and development of degree distribution in the rateless code
    Yue QIAO, Yusun FU, Muyun YUAN, Jinhui TANG
    2022, 38(10):  1-19.  doi:10.11959/j.issn.1000-0801.2022268
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    As a kind of deletion coding technology, the rateless code reduces feedback retransmission and has the characteristics of flexible bit rate and simple compilation code, which has broad application prospects in many fields.As the basis of rateless code design, degree distribution has a crucial impact on the performance of the rateless code With the wide application of the rateless code, the design of degree distribution also needs to change with changes in scenarios and needs.Firstly, the development and application of the rateless code were discussed.Starting with several classical rateless codes and degree distributions, the current research and development of the degree distribution were summarized and analyzed from three perspectives of application scenarios, optimization targets and existing optimization methods.Finally, the development and application trend of rateless codes and degree distribution were discussed.

    Topic: 6G Wireless Transmission Technology
    Overview of reconfigurable intelligent surface for new-generation mobile communication
    Zilu GAO, Shaohui SUN, Li LI
    2022, 38(10):  20-35.  doi:10.11959/j.issn.1000-0801.2022278
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    Reconfigurable intelligent surface technology, which features low cost, low energy consumption and easy deployment, is the potential key technology of 6G.By intelligently regulating electromagnetic waves in space, RIS can assist in building an intelligent and controllable wireless electromagnetic environment, thus providing a new paradigm for the development of mobile communications.Firstly, the basic principle, main technology advantages and application scenarios were analyzed.Then, the key technologies such as channel estimation and beamforming in RIS aided communication transmission were discussed, and relevant research suggestions were given.Finally, the main challenges of RIS technology in practical application were analyzed from the aspects of hardware implementation, algorithm design and network deployment.

    New multiple access and waveform technology for 6G
    Hua LI, Shiya HAO, Caihong GONG, Qianqian LI, Xiaoming DAI
    2022, 38(10):  36-45.  doi:10.11959/j.issn.1000-0801.2022271
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    With the explosive growth of Internet devices, the 5G new radio (NR) system faces congestion and high latency issues due to the low access efficiency of traditional orthogonal multiple access (OMA).Besides this, the performance of the orthogonal frequency-division multiplexing (OFDM)-based system is severely degraded due to the Doppler effect in high-speed scenarios.To meet the low-latency, high-reliability, and massive connection requirements of 6G communication in high-mobility scenarios, firstly, a novel orthogonal time frequency space (OTFS)-based pattern division multiple access (PDMA) scheme, shortened as OTFS-PDMA, was proposed.Then, the system input-output relationship of different types of PDMA codeword allocation schemes in the delay-Doppler (DD) domain was derived.Finally, a low-complexity expectation propagation algorithm (EPA)-based receiver was proposed.Simulation results illustrate that the proposed OTFS-PDMA scheme achieves significant performance gains over the conventional OTFS-OMA scheme.For regular PDMA patterns, the PDMA codeword allocation has a slight impact on the system performance.For irregular patterns, the centralized spreading method outperforms the discrete one.For discrete spreading scheme, the system can achieve better performance by assigning irregular PDMA spread signals along the Doppler direction.In addition, the proposed EPA receiver outperforms its conventional counterparts.

    Key technologies of satellite communications aided by reconfigurable holographic surfaces
    Xinyuan HU, Ruoqi DENG, Boya DI, Hongliang ZHANG, Lingyang SONG
    2022, 38(10):  46-56.  doi:10.11959/j.issn.1000-0801.2022273
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    Ultra-dense low earth orbit (LEO) satellite communication networks can overcome the scarcity of spectrum resources and the limited coverage of traditional terrestrial networks, and thus have the potential to provide high data rate services and global massive connectivity for terrestrial users.However, due to the high mobility of the satellites, LEO satellite networks put more stringent requirements on antenna technologies in terms of accurate beam steering and high antenna gain.Reconfigurable holographic surface (RHS), as a new type of metamaterial antenna, is investigated to assist LEO satellite communications.The RHS can electronically control the metamaterial units by leveraging the holographic principle to generate desired directional beams.Based on the hardware structure and holographic working principle of RHS, an RHS-assisted multi-satellite communication scheme was proposed, which considered both the LEO satellite tracking scheme and the data transmission scheme.A holographic beamforming optimization algorithm was also designed to maximize the sum rate.Simulation results verify the effectiveness of the proposed scheme and demonstrat that the RHS provids a more cost-effective way to support satellite communications than the conventional phased array antennas.

    Pattern division random access (PDRA) scheme for mMIMO systems
    Xiaoming DAI, Lizhuo PANG, Zheng CHANG, Xinyue ZHANG, Yiran XING, Xiyuan WANG
    2022, 38(10):  57-66.  doi:10.11959/j.issn.1000-0801.2022277
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    To enhance the massive machine-type communications (mMTC) random access (RA) performance, a pattern division random access (PDRA) scheme was proposed for massive multiple-input multiple-output (mMIMO) systems.In this scheme, the pilot contention space was expanded to the pattern-domain.To enlarge the size of contention space without resorting to increasing the physical resources, the pattern-domain pilot was constructed based on the superposition of L cyclically-shifted Zadoff-Chu (ZC) sequences.Simulation results illustrate that the PDRA scheme can reduce pilot collision probability significantly, and improve the access success probability compared with the conventional RA scheme, without compromising excessively on channel estimation and data detection performance.

    Research and Development
    A real-time detection method for multi-scale ships in complex scenes
    Weina ZHOU, Lu LIU
    2022, 38(10):  67-78.  doi:10.11959/j.issn.1000-0801.2022258
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    Ship detection plays an important role in tasks such as military reconnaissance, maritime target tracking, and maritime traffic control.However, due to the influence of variable sizes of ships and complex background of sea surface, detecting multi-scale ships remains a challenge in complex sea surfaces.To solve this problem, an improved YOLOv4 method based on multi-layers information interactive fusion and attention mechanism was proposed.Multi-layers information interactive fusion (MLIF) and multi-attention receptive field (MARF) were applied and combined reasonably to build a bidirectional fine-grained feature pyramid.MLIF was used to fuse feature of different scales, which not only concatenated high-level semantic features from deep layers, but also reshaped richer features from shallower layers.MARF consisted of receptive field block (RFB) and attention mechanism module, which effectively emphasized the important features and suppressed unnecessary ones.In addition, to further evaluate the performance of the proposed method, experiments were carried out on Singapore maritime dataset (SMD).The results illustrate that the method proposed can effectively solve the problem of difficult detection of multi-scale ships in complex marine environment, and meet the real-time requirements at the same time.

    SSCANL decoder based joint iterative detection and decoding algorithm
    Chongyang LIU, Rui GUO
    2022, 38(10):  79-88.  doi:10.11959/j.issn.1000-0801.2022086
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    In order to improve the receiver performance of the sparse code multiple access (SCMA) system based on polar codes, the cyclic redundancy check (CRC) aided joint iterative detection and decoding receiver scheme based on simplify soft cancellation list (SSCANL) decoder (C-JIDD-SSCANL) was proposed.A polar code decoder in the C-JIDD-SSCANL receiver used the SSCANL algorithm.In this algorithm, decoding node deletion technology was used to simplify L times of soft cancellation (SCAN) decoding required by soft cancellation list (SCANL) algorithm by deleting frozen bit nodes, then the computational process of soft information update between nodes was simplified, and the computational complexity of decoding algorithm was reduced.The simulation results show that the SSCANL algorithm can obtain the same performance as the SCANL algorithm, and its computational complexity is reduced compared with the SCANL algorithm.Compared with the joint iterative detection and decoding scheme based on SCAN decoder (JIDD-SCAN) and the CRC aided joint iterative detection and decoding scheme based on SCAN decoder (C-JIDD-SCAN), the performance of C-JIDD-SSCANL receiver scheme based on SSCANL decoder is improved by about 0.65 dB and 0.59 dB respectively when the bit error rate is 10-4.

    Ebbinghaus forgetting curve and attention mechanism based recommendation algorithm
    Nan JIN, Ruiqin WANG, Yuecong LU
    2022, 38(10):  89-97.  doi:10.11959/j.issn.1000-0801.2022266
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    Traditional attention-based recommendation algorithms only use position embeddings to model user behavior sequences, however, ignore specific timestamp information, resulting in poor recommendation performance and overfitting of model training.The multi-task matrix factorization recommendation model based on time attention was proposed, which used the attention mechanism to extract the neighborhood information for the user and item embedding, and used the Ebbinghaus forgetting curve to describe the changing characteristics of user interests over time.The model training process introduced a reinforcement learning strategy of experience replay to simulate the human memory review process.Experimental results on real datasets show that the proposed model has better recommendation performance than existing recommendation models.

    Improved ResNet algorithm based intelligent interference identification
    Jian MA, Guangjin ZHANG, Lei ZHANG, Jingwei DAI
    2022, 38(10):  98-106.  doi:10.11959/j.issn.1000-0801.2022233
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    The labor cost of the current network operation and maintenance is high and the efficiency is low.How to quickly and accurately identify the type of network interference, and improve the work efficiency of the maintenance personnel has become an urgent problem to be solved.An intelligent interference identification method of improved deep residual network (ResNet) was studied.The interference data was collected and preprocessedby connecting with the communication interference data interface of the operator's northbound network management.The type of itwaslabelled and corrected by the current network experts to form an offline interference data set.Then the interference frequency domain information was used to generate the interference spectrum waveform image, and performed image processing and data processing for different interference types.After that, the traditional Res Net algorithm was improved according to the business characteristics to extract the features of single interference type.The features were weighted in the compound interference type to identify any type of interference.Finally, the interference data was identified online by importing the trained model, which effectively improved the accuracy and efficiency of interference identification.

    Intent-driven cloud-network convergence on-demand orchestration
    Lulu ZHANG, Chungang YANG, Dong WANG, Ying OUYANG, Tong LI, Junjie GUO, Ru DONG
    2022, 38(10):  107-119.  doi:10.11959/j.issn.1000-0801.2022272
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    With the rapid development of cloud computing and Internet technology, user service demands show a diversified development trend, and cloud-network convergence has become an important choice for the development of the current information and communication industry.At present, cloud-network convergence only achieves simple cloud-network interconnection, which can not overcome the heavy problems of diversified service demands and massive heterogeneous resource supply.Therefore, promoting cloud-network convergence still requires strengthening the on-demand delivery capability of cloud services.Intent-driven network, as a new networking paradigm, becomes a viable option to solve this dilemma.The research status of cloud-network convergence was sorted out, and the research necessity of intention-driven cloud-network convergence business on-demand orchestration was summarized.Furthermore, the intent-driven cloud-network convergence architecture and its key technologies were proposed and analyzed, and on this basis, an on-demand orchestration model of cloud business was proposed.Finally, in the hybrid cloud interconnection and industrial Internet scenarios, the intent-driven on-demand orchestration model of cloud business was analyzed, and the future prospects were introduced.

    Research on SDN based tactical communication network architecture
    Tai LIU, Chao ZHU, Yi CHENG, Yiming WANG
    2022, 38(10):  120-130.  doi:10.11959/j.issn.1000-0801.2022236
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    Tactical communication networks has high dynamic, weak connection, low bandwidth, multi-link backup, SDN (software defined network) technology decouples from hardware and software through traditional network control devices, software the core control functions, get a global view through centralized control policies, so as to realize the flexible scheduling of resources and the efficient utilization of channel resources, promote the development of tactical communication networks more intelligent and flexible adaptive.The development status and advantages of software defined network were firstly introduced, the problems of traditional architecture of tactical communication networks were analyzed, including the application of SDN in the field of foreign military tactical communication.Then, the feasible idea of the application of SDN in the field of military communication was put forward, as well as the application scenarios were conceived.Finally, the feasibility of the application of SDN in military communication was summarized.

    Research on 4G/5G voice quality optimization based on data mining and geographic visualization
    Jian HU, Lei SUN, Yiyan YIN, Xiaokang YANG, Jingui BAI, Yejiang ZHANG
    2022, 38(10):  131-139.  doi:10.11959/j.issn.1000-0801.2022243
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    Traditional voice quality optimization relies on field test, case accumulation and expert experience.It is costly and inefficient to analyze problems by manual test.Through the application of data mining, decision tree machine learning algorithm, geographic visualization and other technologies, a voice experience optimization visualization platform based on big data analysis was developed, which could effectively identify the laws in voice big data, and realize the functions of correlation analysis between user voice experience index and wireless network performance index, intelligent recognition of degradation threshold and image analysis of poor quality areas.It is conducive to reduce the skill threshold of network engineers, improve the work efficiency of network optimization, save network operation and maintenance costs, and provide accurate and effective voice experience improvement solutions for the industry.

    Engineering and Application
    Study on evolution of NR duplex operation
    Ting KE, Xinghua SONG, Fei WANG, Zhiheng GUO, Tuo YANG, Chunxia GUO, Chengcheng HAN, Yunfeng LIU, Zhenyu LI
    2022, 38(10):  140-152.  doi:10.11959/j.issn.1000-0801.2022050
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    Subband non-overlapping full duplex (SBFD) at gNB side within a conventional TDD band was considered as a key feature of 5G-Advanced to fulfill the challenging requirements of low latency and high uplink throughput emerging in vertical industry and industrial internet.Meanwhile, gNB-to-gNB cross-link interference handling needed to be enhanced to enable different TDD configurations for both public network (Macro) and vertical network (Micro) applied in the same frequency band.With a thorough analysis on the interference characteristic in the potential deployment scenarios for both different TDD configurations and subband non-overlapping full duplex, various feasible interference handling schemes to fulfill the challenging deployment requirements for vertical industry and industrial internet were presented, and the feasibility of above duplex enhancement schemes was checked via link budget, simulation and proof-of-concept prototype.

    Analysis of telecom operators’ IoT strategy from the perspective of 2G/3G transition
    Xiaozhong LIU, Junyu FANG, Yongbin JIANG
    2022, 38(10):  153-162.  doi:10.11959/j.issn.1000-0801.2022255
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    In the context of 2G/3G transition, it is a general trend for NB-IoT and LTE Cat.1 to undertake their business development.On the basis of reviewing and analyzing the current status and trends of the 2G/3G-IoT (Internet of things) business, sorting out the IoT business development strategies of the three major domestic telecom operators at the terminal, network and application levels, the three existing business models of telecom operators in the NB-IoT and LTE Cat.1 business area were summarized, including traffic-oriented, platform-supported, and application-enabled.Finally, from three aspects of business opportunity expansion, product marketing and team services, the future upgrade of the business model was prospeted.

    Research and practice of OTN controller northbound unified interface model
    Yanxia TAN, Yanlei ZHENG, Guangquan WANG, He ZHANG
    2022, 38(10):  163-172.  doi:10.11959/j.issn.1000-0801.2022270
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    In the software defined optical transport network (SDOTN) architecture, the manufacturer’s controller system is required to be connected to the optical transport network (OTN) orchestrator system through the northbound interface.However, there is currently no unified northbound interface standard, which brings many problems to the automatic provisioning of cross-domain and cross-vendor end-to-end services in SDOTN.The status and problems of OTN controller northbound open interface standards were expounded, and the current mainstream transport application programming interface (TAPI) and abstraction and control of traffic engineering network (ACTN) northbound interface standards from the perspective of network models were compared and analyzed.Finally, the research practice of China Unicom in the standardization of ACTN unified interface model and the construction of management and control system were introduced, and an outlook on the follow-up research and development direction was provided.

    Research and application of 5G cloud-network-edge-end integrated in-depth security protection system
    Guoxin ZHANG
    2022, 38(10):  173-179.  doi:10.11959/j.issn.1000-0801.2022276
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    A 5G cloud-network-edge-end integrated in-depth security protection implementation scheme was innovatively proposed, the network security protection system of 5G customized network was explored, and the basic architecture, characteristics, implementation scheme and application effect of the system were introduced.In the implementation plan, two key points were emphasized.Firstly, by deploying the security system of the four aspects of the 5G cloud network, the edge and the end, the multi-level and multi-dimensional security protection capability was formed.Secondly, the operation process of the adaptation system, including one-key reinforcement, security defense, situational awareness and one-key emergency response was established.Finally, the practical application effect of the 5G cloud-network-edge-end integrated in-depth security protection system was given.

    5G architectural evolution Option4 technology analysis and deployment suggestions
    Songtao GAO, Xiangchen MA, Yiming YU, Du PAN
    2022, 38(10):  180-186.  doi:10.11959/j.issn.1000-0801.2022148
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    Option4 architecture improves 5G network performance by aggregating 4G link capabilities on the basis of 5G SA, while taking into account the existing 4G user experience.It is a potential 5G architecture evolution direction that operators are concerned about.The technical principles of Option4 was introduced, the key performance of Option4 from multiple dimensions was analyzed in detail, the impact of Option4 on the complexity of operation and maintenance was discussed, and 5G Option4 architecture deployment suggestions were proposed.

Copyright Information
Authorized by: China Association for Science and Technology
Sponsored by: China Institute of Communications
Posts and Telecom Press Co., Ltd.
Publisher: Beijing Xintong Media Co., Ltd.
Editor-in-Chief: Chen Shanzhi
Editorial Director: Li Caishan
Address: F2, Beiyang Chenguang Building, Shunbatiao No.1 Courtyard, Fengtai District, Beijing, China
Postal Code: 100079
Tel: 010-53879277
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E-mail: dxkx@ptpress.com.cn
Mailing Code: 2-397
ISSN 1000-0801
CN 11-2103/TN
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