6G technology is still in its initial stage of research.It is expected that in the next few years,the world will gradually reach a consensus on visions and key technical parameters of 6G .Focusing on the further expansion of application areas and further enhancement of technical capability,the technical fields were summarized that may be involved in the future 6G radio access,including the coverage expansion based on the satellite-terrestrial integration,millimeter wave and terahertz communications,data-driven network artificial intelligence (AI) and security,large-scale cooperation and cell-free architecture innovation,etc.On this basis,some important technologies,such as ultra-high reliability and low latency,full dynamic radio resource allocation and centimeter level precise positioning,which need to be further broken through in the wide-area Internet of things (IoT) based on the public mobile communication system were analyzed and prospected.Finally,the conclusions were given.
To achieve a deeper level of intelligent communication for human beings,the sixth generation mobile communication system (6G) will realize the extension from the real world to the virtual world.To this end,the “human-machine-thing-genie” problem introduced by 6G was presented,and an evolved dual-world architecture for 6G was proposed.The architecture includes the fourth elements of 6G,genie,in the virtual world.The potential key theories and technologies to support the design and implementation of 6G were proposed and analyzed.
Based on the vision on the 6G wireless communication network,i.e.,global coverage,all spectrums and all applications,we comprehensively survey 6G related wireless channel measurements,channel characteristics,and channel models for all frequency bands and all scenarios.Millimeter wave (mmWave),terahertz (THz),optical band,satellite,unmanned aerial vehicle (UAV),maritime,underwater acoustic,high-speed train (HST),vehicle-to-vehicle (V2V),massive/ultra-massive multiple-input multiple-output (MIMO),orbital angular momentum (OAM),and industry Internet of things (IoT) communication channels were particularly investigated.The related 6G channel measurement and modeling results were also given.Finally,future research challenges on 6G channel measurements and modeling were pointed out.
As the first type of channel code achieving the channel capacity,polar codes are an important candidate for the 6G data transmission.A polarized processing framework for the 6G systems was proposed.In this framework,in order to fulfill the requirement of ultra-reliable transmission,a high-performance coding scheme of concatenated polar code was designed to approach the channel capacity with finite-length.Then,the polar coded MIMO scheme was devised to match the requirement of the high spectrum efficiency.Finally,the scheme of polar coded non-orthogonal multiple access was investigated to improve the transmission capacity.All these schemes indicate that polar processing can dramatically boost the performance of 6G wireless transmission and become a promising direction.
At the beginning of design for the traditional mobile communication systems,security is considered as an independent technology,relying on “patch” and “plug-in” to realize the security protection of wireless communica-tion.The sixth-generation (6G) mobile communication system is designed based on software-defined slicing platform,edge computing,artificial intelligence and big data mining to adapt to different application scenarios and performance objectives,making the traditional network security mechanisms difficult to guarantee 6G's requirements for embed-ded security.6G endogenous security was proposed,the architecture and key technologies of 6G endogenous security were described,the security threats in the new technologies were discussed which 6G would adopt,and the chal-lenges and future research directions of 6G endogenous security were provided.
6G network not only explore higher communication rates but also combine with the emerging technologies such as cloud computing,edge computing,artificial intelligence,and big data,and use a new network architecture to achieve wider interconnection and interoperability across network and domains,and provide an intelligent,safe and efficient technical support for industrial Internet of things,smart cities,and intelligent transportation.Blockchain technology as a decentralized,open and transparent distributed ledger technology can provide strong security for 6G.The integration of blockchain technology and 6G network was studied.Firstly,the difference between 5G and 6G network and the challenges of 6G faced were given,and the research of blockchain technology in spectrum management,mobile edge computing and D2D communication was reviewed.Then,the integration of blockchain technology and 6G emerging network was explored.Thus,the technical challenges in terms of blockchain and the cloud-edge-device network,blockchain and federal learning,blockchain-based resource transactions,and lightweight blockchain for edge network were presented.The corresponding solutions were also given.
The future satellite communications network architecture for 6G was analyzed, studied and imagined.Through introducing the current trends of satellite and ground communications integration, with the current research results of 6G network architecture with its vision and requirements, the technical characteristics of 6G network architecture were summarized.The key role of artificial intelligent (AI) in 6G network was deeply explored based on the research and application analysis of AI in the field of communications.Therefore, the idea of AI enabled 6G satellite communications network overall architecture, RAN architecture, core network architecture were proposed, also with step-by-step evolution and implementation.Finally, the enhanced robust mechanism of 6G satellite communication network based on block-chain was also discussed.
In order to meetthe requirements of intelligently adapting to the needs of human-machine-thing deep interconnection,the sixth-generation mobile communication system (6G) will be based on full spectrum,face all scenarios and support all services.Endogenous intelligence is the core component of 6G and an inevitable trend driving 5G evolution.The characteristics and compositions of artificial intelligence driven 6G endogenous intelligent networks were discussed.The key technologies of endogenous intelligent network and current status of industrial applications were also described.Further,domestic and foreign related progress and standardization works were introduced,and also position future challenges were prospected.
2020 marked the first year of the era of 5G commercialization in China and the inception of worldwide research in 6G.Compared with 5G networks, 6G networks will have larger information capacity, higher transmission rate, lower transmission delay, larger number of connected devices, higher spectrum efficiency, higher energy efficiency, and can support applications with higher mobile speed.Therefore, 6G networks will involve many new key technologies and also face many challenges.The background, development, typical applications, performance indicators, network architecture, key technologies and future challenges of 6G were systematically reviewed, which are expected to provide some reference for future 6G networks related research.
The development of the Internet of things has led to the deployment and application of various real-time monitoring systems (such as intelligent driving) and status update systems (such as industrial control).For the above systems,the freshness of information is particularly important.If the destination receives outdated information,it may reduce the accuracy and reliability of the system’s decision-making and cause severe security risks.In the future 6G network,the freshness of information will become increasingly important for information update applications.In order to characterize the freshness of information effectively,the academic world has proposed the concept of age of information (AoI).Recently,AoI has quickly become a new performance index and research hotspot of wireless systems.Firstly the research history of information age was reviewed.Then,the key issues of AoI introduced in different network models (such as single-user networks,single-hop networks,and multi-user networks) were analyzed.Finally the future research trend was prospected.
The concept of 6G has been proposed and has attracted the wide attention of academe.Generally speaking, the 6G network will optimize the performance of 5G, and expand the network scenarios which are difficult to achieve within 5G.However, the introduction of new scenarios and technologies will also bring new security threats to cyber security.The research progress on the key technologies and implementation methods of the 6G were conducted.To summarize a vision of core technologies of 6G, the research work of major 5G/6G research institutions, companies and enterprises were focused on .On this basis, the possible security problems and security challenges in 6G network were put forward.Finally, according to the existing network techniques, the possible solutions and proposed a general security model for 6G networks were discussed.
With the development of the Internet of things,multiple real-time applications will emerge in future 6G communication network.Driven by demands on low-latency services of multiple real-time applications,mobile edge computing (MEC) will become an important technology to improve the user experience and reduce the network cost.However,the computing capacity of a single MEC server is limited,which induces that it is difficult to meet the low-latency requirement of data processing for the computation-intensive applications.A heterogeneous multi-layer mobile edge computing (HetMEC) network architecture was proposed to jointly utilize the computing and transmission resources of both the cloud computing center and multi-layer MEC servers.By reasonably dividing and offloading computing tasks,reliable and efficient computing services were provided for edge applications.Simulation results show that the proposed algorithm could effectively reduce the processing latency,improve the network processing rate and robustness.
Facing the 6G era, the network will usher in new application scenarios and new performance requirements.Diversified application and communication scenarios, extremely heterogeneous communication networks, and extreme performance service requirements will all put forward higher requirements for mobile communication networks.On the basis of summarizing network intelligence in 5G and 5G-Advanced networks, the definition of intelligent-endogenesisin 6G networks and four major characteristics of 6G network architecture for intelligent-endogenesis were proposed, and the potential key technologies of intelligent-endogenesisin 6G network was analyzed, and finally combined with two application scenarios to further explore the concept of network architecture for intelligent-endogenesis.
With the rapid development of smart city,smart manufacturing and other industries,machine-type communication has gained much attention of academia and industry.The extent of function integration and intelligence of machine-type communication network has become increasingly high,which imposes more stringent requirements on network delay,reliability,number of connected devices,peak rate,security and scalability.Based on analyzing the change of performance requirements,key technology and corresponding network architecture of machine-type communication network in 4G,5G to future 6G system,the intelligent sensing-communication-computation integrated network architecture was proposed for 6G machine-type communication network.
With the development of mobile communication technology towards marginalization and distributed structure,the traditional network security method of external border protection will be faced with more and more challenges.The emerging network security accidents also show that it is necessary to grow self-adaptive,independent and self-growing security capabilities from the information system,that is,endogenous security.Blockchain,as a de-centralized shared ledger and database,has the characteristics of decentralization,immutability,leaving traces throughout,traceability,collective maintenance,openness and transparency,etc.,which can greatly meet the needs of endogenous security design.Therefore,the necessity and demand of endogenous security was described,then the blockchain technology as an important means to realize endogenous security was introduced,the main research progress,difficulties and challenges faced by blockchain were analyzed,and the future research direction and oppor-tunities were put forward.
In the era of the 6G cellular networks,the base station (BS) should be able to provide seamless connectivity for a large number of Internet of things (IoT) devices distributed in various areas.However,constrained by their locations,some IoT devices may possess unreliable communication channels to the BS due to the obstacles between them.It is a big obstacle on the roadmap towards the massively connected IoT networks in the era of 6G .To tackle this challenge,the possibility was studied to employ the newly emerging technique of intelligent reflecting surface (IRS) for enhancing the strength of the IoT devices’ signals at the BS.Specifically,the transmit power minimization problem in an uplink IoT communication system was focused on,where the overhead for channel estimation was taken into account.On one hand,for the case where the BS was equipped with a small or moderate number of antennas,an iterative algorithm was proposed to jointly optimize the user power allocation,the IRS reflecting coefficients,and the BS beamforming vectors.On the other hand,for the case where the BS had a massive number of antennas,i.e.,massive multiple-input multiple-output (MIMO),a low-complexity design of the user power allocation,the IRS reflecting coefficients,and the BS beamforming vectors was provided in a closed-form.Numerical results validate the great potential of IRS for enhancing massive connectivity in the future 6G-assisted IoT networks.
To satisfy the requirements of full-spectrum,full-scenario and full-service networking in the future Internet of things,the intent-driven radio access network (ID-RAN) is proposed for the 6G wireless communication system to decrease the networking costs and save the labor expense,while enhancing the intelligent capabilities of the radio access network.Based on the artificial intelligence,network function virtualization and software-defined networking,the intents from applications,performance requirements and networking status can be translated to the configuration and optimization strategies by the proposed ID-RAN,which enables 6G work efficiently,flexibility and elastically.The system architecture of ID-RAN was proposed firstly,and then the principles and solutions of key techniques were formulated,including intent translation,conflict resolution,configuration trigger,performance evaluation and optimization.Meanwhile,the open software-defined hardware platform for ID-RAN was built,and the corresponding performances aimed for 6G were presented.
While the commercial deployment and promotion of 5G is ongoing, mobile communication networks are still facing three fundamental challenges, i. e. , spectrum resource scarcity, especially for low-frequency spectrum, exacerbated by fragmented spectrum allocation, user-centric network service provision when facing billions of personalized user demands in the era of Internet of everything (IoE), and proliferating operation costs mainly due to huge energy consumption of network infrastructure. To address these issues, it is imperative to consider and develop disruptive technologies in the next generation mobile communication networks, namely 6G. In this paper, by studying brain neurons and the neurotransmission, we propose the fully-decoupled radio access network(FD-RAN). In the FD-RAN, base stations (BSs) are physically decoupled into control BSs and data BSs, and the data BSs are further physically split into uplink BSs and downlink BSs. We first review the fundamentals of neurotransmission and then propose the 6G design principles inspired by the neurotransmission. Based on the principles, we propose the FD-RAN architecture, elastic resource cooperation in FD-RAN, and improved transport service layer design. The proposed fully decoupled and flexible architecture can profoundly facilitate resource cooperation to enhance the spectrum utilization, reduce the network energy consumption and improve the quality of user experience. Future research topics in this direction are envisioned and discussed.
To realize Internet of everything (IoE),the 6G cellular Internet of things (IoT) network need to provide wireless access with low power,massive connectivity and wide coverage.Through the analysis and research on the massive access technology in 6G cellular IoT network,especially in combination with the sporadic characteristics of IoT applications,a new access framework based on the grant-free random access protocol was designed to facilitate efficient massive access with limited spectrum resources.The proposed framework consisted of two phases.One was joint activity detection and channel estimation.The other was data transmission,which was divided into two categories,uplink data transmission and downlink data transmission,according to the different directions of data transmission.Due to the uncertainty of channel state information at the base station under the massive grant-free random access and considering the low power demand of 6G IoT devices,two robust uplink and downlink access algorithms were designed by maximizing the system energy efficiency.Extensive simulation results validate the effectiveness and robustness of the proposed algorithm.
Considering the heterogeneity of various IoT system and the single point failure of centralized data-processing platform,a decentralized IoT data sharing and storage method based on blockchain technology was proposed.The block consensus and decentralized storage of shared data were realized through the PoS consensus mechanism.A block layered propagation mechanism between consensus node and verified node was proposed based on the Gossip protocol.The block propagation delay model and decentralization evaluation model of blockchain networks were derived.The trade-off between the block propagation delay and the decentralization degree of networks was analyzed.The simulation results demonstrate that the block propagation delay and degree of network decentralization decrease with the increase of minimal capabilities of consensus nodes.As an application example,in the trajectory data sharing scenario of confirmed patients,the data sharing smart contract is implemented and tested based on the Ethereum development platform.
For supporting location based differentiated services better, 6G has a more stringent requirement on high-precision positioning.Firstly, the principles, characteristics, advantages and disadvantages of the existing indoor positioning techniques were introduced.Then, indoor positioning systems integrating multiple techniques were discussed to overcome the drawbacks of using only a single technique.Moreover, the advances in cooperative positioning systems involving multi-devices and multi-networks were presented with the summary and analysis of centralized and distributed implementation architectures.Finally, the opportunities and challenges faced by 6G indoor positioning were pointed out.
Analsisand outlook for satellite communication access and mobility management technology in 6G network was presented.Firstly, the access technology of current global representative satellite mobile communications system was introduced, as well as the international standardization organization research status of 5G NR satellite access technology.According to the challenges for 6G satellite communications network access, some solutions regarding to 6G satellite communications access were proposed respectively from the aspects of extremely simple access, extremely intelligent access.Furthermore, according to the demand of massive terminals handoff in the high dynamic scenario of 6G satellite communications, the flexible handoff scheme based on cloud channel technology, which supported batch massive terminals mobility management for across satellites and beams, was proposed.
The requirements and the fl exible and reconfi gurable network architecture for the space-integrated-ground information network was proposed based on analyzed the 6G network vision and challenges faced by the space-integrated-ground information network.Based on the proposed network architecture, the intelligent network management and control architecture and the virtualization technology of the space-integrated-ground information network were proposed to realized the dynamic confi gurability of the network.
The intelligent information society, which is highly digitized, intelligence inspired, and globally data driven, will be deployed in the next decade. The next 6G wireless communication networks are the key to achieve this grand blueprint, which is expected to connect everything, provide full dimensional wireless coverage and integrate all functions to support full-vertical applications. Recent research reveals that intelligent reflecting surface(IRS)with wireless environment control capability is a promising technology for 6G networks. Specifically, IRS can intelligently control the wavefront, e. g. , the phase, amplitude, frequency, and even polarization by massive tunable elements, thus achieving fine-grained 3-D passive beamforming. In this paper, we first give a blueprint of the next 6G networks including the vision, typical scenarios, and key performance indicators(KPIs). Then, we provide an overview of IRS including the new signal model, hardware architecture, and competitive advantages in 6G networks. Besides, we discuss the potential application of IRS in the connectivity of 6G networks in detail, including intelligent and controllable wireless environment, ubiquitous connectivity, deep connectivity, and holographic connectivity. At last, we summarize the challenges of IRS application and deployment in 6G networks. As a timely review of IRS, our summary will be of interest to both researchers and practitioners engaging in IRS for 6G networks.
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.
mMTC (massive machine-type communication) is one of the three major application scenarios of 5G network,but it is highly likely that the truly mature Internet of everything may not be realized until the future 6G network.In order to realize the deep immersive ubiquitous connection network,6G IoT will simultaneously provide all-round services such as high data rate,low latency,high reliability and massive connections.Firstly,the 6G was prospected and the technical challenges of 6G IoT were summarized.Then the existing physical layer transmission technologies of IoT were reviewed.Next,the promising symbiotic transmission technologies for 6G IoT were introduced and discussed,which enable the possibility that active transmission and passive transmission facilitates each other and provide a new solution for 6G IoT transmission.Finally,some possible future research directions were presented for symbiotic transmission in 6G IoT.
Taking full advantage of fog radio access network (F-RAN),non-orthogonal multiple access techniques,and artificial intelligence techniques,smart fog radio access networks (S-FRAN) have been envisioned as a promising framework to fulfill the stringent requirements of 6G wireless network,such as ultra-high data rate,ultra-low latency,and ultra-large number of devices.The principles of S-RAN were firstly presented.Based on which,the key technol-ogies,research progress and standardization of S-FRAN were introduced.Finally,the challenges of S-FRAN were identified.
The satellite Internet of things (SIoT) is regarded as a feasible scheme to realize the vision of the “ubiquitous connection” in 6G.The relatively high-speed movement between the mobile satellite and the terminal causes service continuity problems.The mobility management technology of the SIoT was expounded.New challenges to the mobility management of the SIoT caused by the dual-mobility,wide-area coverage and non-uniform demand were analyzed.Key techniques of the mobility management of the SIoT in 6G from aspects of the mobility management architecture,prediction and enhancement were discussed.
With the development of the ground-air-space integrated information network,satellite networks and ground mobile networks serve as space and ground fundamental infrastructures,respectively.While various aerial platforms such as drones constitute air mobile networks to connect space and ground infrastructures.As an important form of 6G,aviation 6G will include new types of air-to-air,air-to-ground and air-to-space communication and networking techniques.An important issue for aviation 6G is how to efficiently use spectrum resources.Based on the challenges of aviation 6G and electromagnetic spectrum space,a spectrum cognitive intelligent management and control architecture for aviation 6G was proposed,and the functions were elaborated of the four main modules in the architecture,namely spectrum cloud,spectrum control link,device spectrum software defined and spectrum sensor network.Three key technologies of spectrum cognitive intelligent management and control for aviation 6G were analyzed and discussed,namely intelligent three-dimensional spectrum space digital twins,3D spectrum intelligent decision,and rapid collaborative learning of spectrum mapping.It is expected to provide guidance and suggestions for the subsequent research on aviation 6G and spectrum intelligent management and control.
Aiming at the problem that the future B5G/6G network is a complex intelligent network with large connections, coupled with the comprehensive application of 3G, 4G, 5G and even 6G, the future networks will inevitably become extremely complex, a three-three-three network architecture was proposed that was a network that includes three types of networks (core network, access network and terminal network), three resources (frequency band, power and time consumptions) and three requirements (active, work and service), which was a three-dimensional comprehensive optimization system architecture, referred to as the three-three-three network.Furthermore, the mathematical basic formulas of the three-dimensional complex network were analyzed, the knowledge + data-driven learning model and the optimization method of intelligent processing using the knowledge learning mechanism were presented.Finally, the numerical example and reachable performance of the three-three-three network were given.Those results demonstrate that the proposed network architecture and the learning optimization mechanism are beneficial for designing future large-connected complex intelligent networks.
Based on 26 GHz indoor channel measurements, the blockage attenuation of human bodies was investigated. 2-ray and 4-ray human blockage models were proposed by calculation of the Vogler's multiple knife-edge diffraction field. Results show that 4-ray model fits quite well with measurement data. Human block attenuations are slightly bigger with 1 GHz than with 500 MHz bandwidth. In the blockage measurement of one person moving along the connec-tion line between the transmitter (TX) and receiver (RX), the smallest attenuation is found when the person is located at the middle of the connection line, and the biggest attenuation is observed when the person is nearest from the RX position. In the blockage measurements by multiple human bodies, the attenuation is bigger in the cases which the persons cross the TX-RX connection line with their front faces directed to the horn aperture at the RX than the cases with their lat-eral faces directed to the RX horn aperture. The blockage attenuation is larger with the increase of person numbers, about 5～8 dB more attenuation per person. The results can be used for design of mm-wave 26 GHz indoor communi-cations systems.
In order to solve the data security problem of data sharing in the fog radio access network in the 6G mobile communication system, an endogenous secure data sharing mechanism that realized local differential privacy and dynamic batch auditing was proposed.First, the user ran the RAPPOR algorithm locally on the data to protect data privacy.Next, the fog access point cached and preprocessed the data.Then the high power node performed a data integrity audit based on the BLS signature and Merkle hash tree on the data cached on the fog access point.Finally, the BBU pool infered the original distribution of shared data through statistical analysis.Security analysis and simulation show that the proposed mechanism realizes the local differential privacy of users, supports secure multi-client batch audit and data dynamic operation, and has high efficiency in time, space and communication.
The faster-than-Nyquist (FTN) signaling technology overlaps multiple streams of data within a symbol period by compressing the transmit symbol time/frequency-domain interval, thus breaking the orthogonality of the Nyquist pulse waveform and achieving the purpose of transmitting more data in a limited bandwidth.A relatively comprehensive explanation of the technical principles of FTN was elaborated, its development status was sorted out, and the related key questions——the relationship between FTN capacity and Shannon capacity, and the intrinsic connection of related technologies were answered.Finally, The possibility of FTN application in 6G was discussed, and its value and challenges in 6G were presented.That is, FTN is a highly spectrally efficient transmission scheme that approximates Shannon's capacity, but excessive receiver complexity may be a key impediment to its use in 6G applications.
With the time-delay sensitive compute-intensive tasks growing exponentially, 5G and future 6G mobile cellular communication networks will form differentiated network slices with edge computing resource to service the multiple communication services.To achieve this, the wireless frequency and edge computing resources will be shared among the network slices, thus the efficient management of the resources is of great importance.The demands of resources management in the life duration of the network slice was analyzed.Then the research progress of the corresponding technologies for slices, i.e., access control, resources allocation and stimulating cooperation among terminals, were summarized.And the open research issue was given.Thus, the resources are managed efficiently for the slices with edge computing resource.
Research on 6G has been carried out on a global scale.Focusing on holographic interactive services under 6G, the requirements for future network performance by studying holographic interactive scenarios and services were analyzed.A basis for business requirements for the design and research and technological evolution of 6G networks was provided.The holographic technology and application status, holographic communication and holographic interaction scenarios, as well as the technical indicators and network performance requirements of the scene business were studied.The holographic technology development stage, development maturity, holographic industry chain under 5G, and holographic technology application field distribution were defined.A holographic scene pool and scene characteristics were constructed, and six types of application scenes were formed based on the characteristics.Through the calculation of technical indicators, the bandwidth performance requirements of holographic portrait transmission were proposed.
The recently commercialized fifth-generation (5G) wireless networks have achieved many improvements, including air interface enhancement, spectrum expansion, and network intensification by several key technologies, such as massive multiple-input multipleoutput (MIMO), millimeter-wave communications, and ultra-dense networking. Despite the deployment of 5G commercial systems,wireless communications is still facing many challenges to enable connected intelligence and a myriad of applications such as industrial Internet-ofthings, autonomous systems, brain-computer interfaces, digital twin, tactile Internet, etc. Therefore, it is urgent to start research on the sixth-generation (6G) wireless communication systems. Among the candidate technologies for 6G,cell-free massive MIMO,which combines the advantages of distributed systems and massive MIMO,is a promising solution to enhance the wireless transmission efficiency and provide better coverage. In this paper, we present a comprehensive study on cell-free massive MIMO for 6G wireless communication networks with a special focus on the signal processing perspective. Specifically, we introduce enabling physical layer technologies for cell-free massive MIMO,such as user association,pilot assignment, transmitter, and receiver design, as well as power control and allocation. Furthermore,some current and future research problems are described.
In the future 6G network, machine-type communication will dominate the network traffic.Many vertical applications, such as networked autonomous driving and industrial internet of things, will become new growth points.Such applications usually consist of the collection of status information and distribution of control signals, requiring ultra-low latency.However, this requirement is hard to meet with a large number of end nodes and limited communication resources.In view of this confliction, it was pointed out that the freshness of information should be considered in the status update system instead of just latency.Furthermore, according to the degree of utilization of status information, various measures of information freshness were introduced, and related representative work was summarized.Finally, the future research directions of information freshness and key questions that need to be answered were discussed.
The intelligent terminal will greatly expand the applications of 6G .However,it will also make 6G face with greater security threats.The reliable terminal identification technology is the premise to ensure the security of 6G networks.Firstly,based on the network architecture and terminal characteristics,the requirements and challenges of 6G intelligent terminal identification were summarized.Then,the development trend was put forward for 6G intelligent terminal identification.Finally,physical layer authentication was explored to achieve possible realization of intelligent terminal identity authentication mechanism in 6G networks.
Combined with the value identification for 5G,the prospect of 6G values was made,and the characteristics of coverage,openness,security and independence of 6G were analyzed.It concludes that if 6G is viewed as the fundamentals for developing both the technological innovation and business mode innovation and is put into the top priority satisfying the expectations for experiencing applications and contents of 6G,the 6G may be far better than 5G,not just 1G advantage,numerically.
Volumn Content
