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20 February 2020, Volume 36 Issue 2

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Comprehensive Review

Research on consensus mechanism optimization for IoT blockchain

Qijie SONG,Tieming CHEN,Yuan CHEN,Dongjie MA,Zhengqiu WENG

2020, 36(2):  1-12.  doi:10.11959/j.issn.1000-0801.2020037

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The essence of the blockchain is a decentralized distributed ledger system.The Internet of things is interconnected by massive heterogeneous terminals and has natural distributed characteristics.Therefore,the combinedIoT blockchain is widely optimistic.At the same time,due to the heterogeneity of the IoT-aware terminal,the limited computing capacity and the ability of data transmission,the IoT blockchain faces great challenges.The password consensus technology has become a key issue.On the basis of summarizing the current blockchain consensus algorithm,its applicability to the IoT blockchain was analyzed,the current application status of several IoT blockchain platforms and consensus mechanisms was introduced,and the optimization research progress of the consensus mechanismin IoT blockchain was described.Finally,the optimization technology of the IoT blockchain and the potential research directions were summarized.

Research and Development

Multi-server conjunctive keyword searchable encryption scheme based on BDH problem

Yanhua LU,Youliang TIAN,Chen LIU

2020, 36(2):  13-23.  doi:10.11959/j.issn.1000-0801.2020049

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Searchable encryption is a cryptographic primitive that supports users to search for keywords on ciphertext.In view of the low efficiency of traditional single-server searchable encryption schemes,it was based on the advantages of identity management in certificate management.In the multi-serve environment,a bilinear mapping was used to construct an identity-based encryption scheme that supports conjunctive keyword search.In this scheme,the storage and query of the encrypted data were allocated to different servers,and the retrieval efficiency of the user storage and keyword was improved by cooperation.Re-use the encryption and search ability of the connection keywords by using the identity of multi-server and user.At the same time,combine with the searchable encryption method of conjunctive keyword,a new security model was constructed based on bilinear pairing.And under the bilinear Diffie-Hellman problem,the scheme satisfies the ciphertext indistinguishability under selected message attack.

Regional heat and social attribute aware participant selection mechanis in mobile crowd sensing

Luoyong XIANG,Wen CHEN,Luyang ZHANG

2020, 36(2):  24-34.  doi:10.11959/j.issn.1000-0801.2020050

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Aiming at the problem of tasks that are low reliability acquired by platform and difficult to accomplish on time in user sparse area.A participant selection mechanism that combines regional heat and social attribute aware was proposed.Firstly,considering the influence of different regional heat on task completion,the regional heat was evaluated according to the number of active users,the average residence time of users and the completion of historical task.Secondly,in order to analyze the impact of user social attributes on task completion,the user willingness,reputation and activity were calculated by combining the status information of users and the historical task record of users.Finally,by taking the above factors into account,two different mechanisms of participant selection for social attribute perception were designed for high and low heat areas to maximize quality and number oftask completionrespectively.The results show that the proposed mechanism can significantly improve the overall data quality,and can also perform sensing tasks in sparse areas on time.Meanwhile,compared with SUR and GGA-I,the failure rate is reduced by 66.7% and 50.6% respectively.

Hybrid precoding with sub-connected architecture for millimeter wave massive MIMO system

Haiyan CAO,Xiaohui YANG,Wenjuan HU,Zichang MA,Fangmin XU,Xin FANG

2020, 36(2):  35-42.  doi:10.11959/j.issn.1000-0801.2020029

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A hybrid precoding scheme in the millimeter wave massive MIMO system was proposed with sub-connected architecture at the transmitter and digital combining at the receiver.In this scheme,the digital precoder and combiner were designed based on the singular value decomposition (SVD) of the equivalent channel matrix,while the optimal analog precoder was obtained by blocking the equivalent channel to maximize spectral efficiency according to the block diagonalization.Considering the hardware cost and power consumption,the precoding scheme with sub-connected architecture at the receiver was further proposed.Otherwise,the analog precoder and combiner were iteratively updated.Simulation results show that the proposed scheme which focuses on the digital combining at the receiver has better performance than successive interference cancelation (SIC)-based hybrid precoding.In addition,though the proposed scheme which focuses on the hybrid combining with sub-connected architecture at the receiver has worse performance than SIC-based hybrid precoding,the power consumption and hardware cost are greatly reduced.

Evaluation model of node importance in directed scale-free network based on cascade failure

Haoran LIU,Xingqi WANG,Yujing DENG,Yuhua QIN

2020, 36(2):  43-51.  doi:10.11959/j.issn.1000-0801.2020042

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In order to evaluate the importance of nodes in a directed scale-free network accurately,the protection strategy can be better implemented and the destruction resistance of the network can be improved.Considering the changes of node load and network connectivity before and after cascading failure,a directed scale-free network node importance evaluation model based on cascading failure was proposed.Firstly,a cascading failure model of directed network was established to deduce the load of nodes before failure.Then,a node importance evaluation model was constructed by combining the node load and its location during data transmission.Experimental results show that when the network is attacked selectively,the number of generated sub-graphs and the network robustness change more obviously after the failure of key nodes measured by the model,providing experimental data for specific applications.

Customer credit modeling and credit granting method based on hybrid algorithm of collaborative filtering and social network

Ke ZHANG,YueJia SUN,Hai HAN

2020, 36(2):  52-60.  doi:10.11959/j.issn.1000-0801.2020048

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With the expansion of market demand for customer credit screening,the traditional FICO credit modeling method relies on a large number of historical credit behavior of trustees,and the limitation of weak ability to identify group attributes is constantly emerging,which causes the problem of cold start of credit scoring.Based on the identity characteristics of the trustee,the initial score through collaborative filtering method was firstly granted,and then the credit evaluation was modified through social network trust graph and group clustering learning results to solve the credit cold start problem during the transition period of scoring.The experimental results show that the credit pre-evaluation error of this method is low and can be smoothly transited to formal evaluation.This method can cultivate good credit habits of trustees in the initial stage of credit,guide the virtuous circle of credit behavior.

Opportunistic cooperative spectrum sensing based on eigenvalue ratio of random matrix

Wuji ZHANG,Shunlan LIU,Jianrong BAO

2020, 36(2):  61-67.  doi:10.11959/j.issn.1000-0801.2020043

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To overcome the deficiencies of low detection probability of traditional spectrum sensing,an EROC spectrum sensing algorithm based on the eigenvalue ratio of a random matrix was proposed.Based on the random detection theory,it used double thresholds and opportunistic cooperation to improve of traditional maximum and minimum eigenvalue (MME) algorithm,and it retained the advantages of the traditional energy detection algorithm.Moreover,on the premise of known false alarm probability,the decision threshold was deduced,and the odd-even slot division was used to effectively realize opportunistic cooperation in reception.Simulation results show that the proposed spectrum sensing algorithm has higher detection probability than MME algorithms in case of low signal-to-noise ratio and low false alarm probability.Therefore,it is suitable for application in wireless communications with deteriorate transmission channels.

Power Informationization Column

Wireless quantum power distribution system based on wireless

Jiawei WU,Yuxiang BIAN,Qing ZHANG,Bao FENG

2020, 36(2):  68-75.  doi:10.11959/j.issn.1000-0801.2020031

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The traditional optical fiberchannel-based key distribution method is limited by the optical fiber resources and construction cost,and it is difficult to meet the security enhancement requirements of the access side massive power service terminals,especially the mobile terminals.In this respect,a wireless channel-based quantum key distribution system was proposed,which was suitable for mass service terminals of power systems.Based on the wireless access requirements of mass service terminals in power system,the overall design of power quantum key distribution system based on wireless channel was given.The functional modules and execution flow of the power quantum key distribution system based on wireless channel were analyzed in detail from three aspects:quantum security service control platform,quantum key storage management platform and massive power service terminal platform.On this basis,combined with the typical power service such as electricity information collection and mobile office,the advantages and prospects of the quantum channel distribution system based on wireless channel applied to the terminal scenario of massive power service were comprehensively analyzed.

Network slicing scheme for heterogeneous power wireless communication networks

Yan ZHEN,Mengyue YU,Haibo ZHAO

2020, 36(2):  76-82.  doi:10.11959/j.issn.1000-0801.2020028

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Targeted at power communication networks,the concepts of vertical and horizontal slicing was introduced,the slicing enabler technologies,then explain the technial challenges of realizing network slicing in power communication networks,finally a slicing scheme for heterogeneous power wireless communication networks was proposed in which vertical slicing guarantees specific applications’ quality and horizontal slicing improves efficiency and flexibility of system entities and terminal devices.

Application of 5G to current differential protection of distribution network

Yuxiang LV,Yang YANG,Yawen DONG,Yucheng WANG

2020, 36(2):  83-89.  doi:10.11959/j.issn.1000-0801.2020032

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Driven by the strategy of grid as a Platform,Hub,and Sharing as well as the construction of Energy Internet and Ubiquitous power Internet of Things declared by Sate Grid Corporation of China,the intelligent distribution network evolves towards Distribution Internet of Things in a gridding and multi-source manner.The traditional distribution network protection and feeder automation barely meets the self-healing requirements of a strong distribution network.The current differential protection is prevailing due to its favorable quick-acting,sensitivity and selectivity.The existing communication solutions baring protection signals includes:fiber channel,230MHz/1.8GHz private wireless network,etc.However,the above methods are usually costly and perhaps with poor stability and low real-time performance.An realistic baring scheme for current differential protection of distribution network over the fifth generation communication system (5G) was proposed,where the of sampling data transmission between differential protection devices was realized based on 5G new radio technology.Thanks to the advantages of low latency,high capacity,security,etc.,5G-based differential protection can dynamically adjust the configuration to accommodate the topology changes,and thus can reduce the transformation and maintenance cost of distribution network.

Dispatch automation system based low voltage distributed photovoltaic power station connected estimation model

Dayan MA,Xiangying XIE,Zhixiong NA,Wentao SHEN,Fanteng MENG

2020, 36(2):  90-94.  doi:10.11959/j.issn.1000-0801.2020046

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A large number of distributed photovoltaic access grids pose great challenges to the safe and stable operation of the grid.In view of the fact that the dispatching automation system did not realize the real-time acquisition and monitoring of low-voltage distributed photovoltaic data,the station estimation method was proposed as an auxiliary means for real-time acquisition of low-voltage distributed photovoltaic power plants,and the comprehensive low-voltage distributed photovoltaic power plants were estimateed through appropriate algorithms.Through case analysis,the deviation between the estimated value and the measured value was basically controlled within 8%,which proved the accuracy of the estimated model.This method is of great significance for the power dispatching department to strengthen the operation monitoring and statistical management of distributed photovoltaics,and to reasonably arrange the dispatching plan and coordinate the power supply.

Improved ant colony algorithm based cloud computing user task scheduling algorithm

Sining LUO,Hualong WANG,Hongyu LI,Wei PENG

2020, 36(2):  95-100.  doi:10.11959/j.issn.1000-0801.2020047

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In recent years,with the development of power information,more and more power applications and tasks are deployed in the cloud.Because of the dynamic heterogeneity of cloud resources and power applications,it is a challenge in the cloud computing system to realize resource division and task scheduling.Power applications need to be able to achieve a rapid response and minimum completion time,and schedulers should consider the load of each cloud computing node to ensure the reliability of cloud computing.A task scheduling algorithm based on the algorithm of improving an ant colony was proposed to solve the problem of task scheduling in virtual machines.Through the improvement of the standard ant colony algorithm,the task scheduling time was reduced and load balancing was realized while minimizing the overall completion time.The results show that the algorithm can shorten the task scheduling time and realize the load balancing of cloud nodes,which provides technical basis for the optimization of power cloud computing.

Operation Technology

Customer-centered mobile network intelligent operation approach

Kai LI,Wei LIU,Guiyang LUO,Jinglin LI

2020, 36(2):  101-108.  doi:10.11959/j.issn.1000-0801.2020024

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The rapid development of new types of services places greater demands on support ability of the personalized service in mobile communication systems.Traditional intelligent pipe carriers only consider limited factors such as current traffic status of the network and number of loading binding quantity,indicating that they don’t take account of the demands and features of wireless customers.Meanwhile,the rule-based method is overwhelmed due to numerous metrics of the wireless network,the complicated correlation among them and heterogeneous requirements of metrics from various users.Therefore,a user-centric intelligent network operation service was proposed,which utilized machine learning and deep learning method.The service had the ability to learn the correlation between user QoS guarantee requirements and wireless network metric status to construct a joint support architecture based on user requirements and wireless network status.The validity of the method on real data was verified.

Analysis and development suggestions of operators in the field of industrial internet identification analysis system

Yufei CUI,Yunyong ZHANG,Di ZHANG,Xiaoxia WANG,Siyu PAN,Kun LI

2020, 36(2):  109-116.  doi:10.11959/j.issn.1000-0801.2020025

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With the development of industrial internet technology,5G and edge computing,countries have put forward their own industrial Internet development strategies and construction of industrial Internet platform.Cloud edge collaborative industrial Internet platform is an important part of the development of industrial Internet.The way of industrial Internet cloud edge collaboration was introduced,the problems in the process of cloud edge collaboration were expounded,and practices were taken based on data collaboration and model collaboration.

Network optimization and reconstruction for 5G

Lingyi KONG

2020, 36(2):  117-125.  doi:10.11959/j.issn.1000-0801.2020034

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In June 2019,the Ministry of Industry and Information Technology officially issued a 5G commercial license,which accelerated the deployment of telecom operator’s network of 5G.NSA networking is a good choice to deploy 5G networks in the early stage,and SA networking is the target architecture of 5G networks.Based on the network existing,how to smooth evolution to 5G is a problem to be considered.The architecture of 4G networks was introduced briefly,the return bearer network was optimized to meet the bandwidth requirement in the early stage of 5G development,Through NFV technology the EPC was reconstructed based on CUPS architecture to support network evolution better.Finally,the inter working architecture of 4G/5G was introduced,the deployment and evolution scheme for SA network was analyzed,which provides reference for the construction of 5G core network.

6G vision requirements and technology trend prospect

Kejun WEI,Po HU

2020, 36(2):  126-129.  doi:10.11959/j.issn.1000-0801.2020035

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As 5G enter the critical phase of commercial deployment,some countries launched research of the next-generation mobile communication technologies (6G).The development trends of information communication technology was analysed firstly,on this basis,the 6G vision and main features of 6G were discussed,and then the potential technology trends of 6G was analysed,in order to provide direction suggestions for the subsequent 6G research.

Research status and development trend of NB-IoT enhancement technology

Furong XU,Weiwen WENG,Chao ZHANG,Tingting BIAN,Xinli MA,Xiangdong GAO,Xin LI,Lei CAO

2020, 36(2):  130-136.  doi:10.11959/j.issn.1000-0801.2020039

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NB-IoT,which is the key technology of the Internet of things,has received widespread attention from global operators.Firstly,the commercial technologies of NB-IoT was outlined,then the research status of NB-IoT enhancement technology was introduced in detail from the aspects of mobile IoT enhancement technology,positioning enhancement technology,mobility enhancement technology and intelligent network optimization technology,and finally,future evolution of NB-IoT technology was introduced.

Analysis of rural OTN network planning and networking architecture

Wenyue CHEN,Yuneng CHEN,Cheng CHEN,Tingjing ZHANG

2020, 36(2):  137-144.  doi:10.11959/j.issn.1000-0801.2020026

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Optical transport network has become one of the mainstream technologies for transport networks with its technological advantages.The previous OTN was mainly deployed in the county and above.With the vigorous development of family broadband services in rural,it is necessary to sink OTN to the level of rural to meet the needs of rapid development in rural areas.Based on the development of family broadband services,a variety of rural OTN system capacity measurement methods were provided and the best rural OTN system networking architecture was analyzed,which could play the reference and thought for the rural OTN in the related future research.

Unwanted emission OTA test environment analysis of 5G basestation

Jian GONG,Nan NAN

2020, 36(2):  145-150.  doi:10.11959/j.issn.1000-0801.2020036

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Based on the strict unwanted spurious emission OTA requirements of China local regulation for 5G 2 600 MHz Base Station,the path loss of the different chambers including far field,CATR (compact antenna test range),near field,DBFC (dynamic beam forming compact range chamber) and other key factors were presented and analyzed according to the measured data.The compared results in different test environment were also shown and the suggestion for passing the test were given.