1、1/40ContentsChapter 1 Introduction.21.1 Structure.21.2 Background.21.3 Concept and Objectives.3Chapter 2 Scenarios and Requirements.42.1 Scenarios.42.2 Requirements.62.3 Evaluation Metrics.8Chapter 3 System Design.83.1 Characteristics.93.2 Architectures.12Chapter 4 Key Technologies.184.1 Access and

2、Connection Management Technologies.194.2 Networking and Deployment.214.3 Mobility Management Technologies.234.4 Flexible and Efficient User Plane Transmission Technologies.284.5 User-Centric Resource Orchestration.304.6 Distributed Multi-Antenna Technologies.344.7 Terminal Key Technologies.354.8 Use

3、r-Centric Convergence Technologies.36Chapter 5 Summary.37References.37Abbreviations.38Acknowledgment.402/40Chapter 1 Introduction1.1 StructureThe advent of the 6th generation mobile communication network(6G)promises to introducenew performance metrics and application scenarios.A user-centric network

4、 is poised to be a keytechnology driving the realization of the 6G vision,as it breaks away from the traditionalparadigm of a“base station centric”network and effectively integrates with emergingtechnologies in the information industry.The International Telecommunication Union Radiocommunication sec

5、tor(ITU-R)highlights in its Future Technology Trends of TerrestrialInternational Mobile Telecommunications Systems towards 2030 and Beyond report that,as anew type of network architecture,user-centric architecture technology can enhance Radio AccessNetworks(RAN)1.This white paper delves into the res

6、earch on User-Centric Access Network(UCAN)technology for 6G.It begins by introducing the background of UCAN technology research andexplains the concept and goal of user-centric in 6G.Chapter 2 outlines the scene requirements andevaluation metrics for UCAN,while Chapter 3 delves into the design of us

7、er-centric accessnetwork systems,encompassing five major functional characteristics and architectural designs.Chapter 4 discusses the key technologies of the user-centric access network,and Chapter 5concludes and provides a future outlook.1.2BackgroundFaced with increasingly complex network environm

8、ents and diverse service requirements,the limitations of the traditional cellular architecture are becoming increasingly prominent.Thehigh path loss of data transmission at the edge of cells and unpredictable interference fromneighboring cells lead to imbalances in user data rates between the cell c

9、enter and cell edge.Additionally,during mobile transitions,handovers at the cellular edge may cause serviceinterruptions and delays.As the cellular coverage area continues to shrink,these issues becomemore severe.To enhance network quality of service and robustness,various edge enhancementand mobili

10、ty optimization solutions have been proposed,and standardized:For cell edge data transmission,4G and 5G have successively proposed key technologiessuch as Coordinated Multiple Points Transmission/Reception(CoMP)and Multi-TransmissionReception Points(Multi-TRP).CoMP enables different cells within a s

11、ingle base station to sendand receive the same or different data to a single user 2.Multi-TRP allows multiple TRPs tocooperate in sending and receiving the same or different data to a single user 3.However,due tothe limited user scale/coverage area of a single Distributed Unit(DU),the dynamic effect

12、s ofMultiple TRP collaboration are constrained by operations across DUs through the Centralized Unit(CU),and the delay increase/data interruption caused by the terminal switching between DUs,thisoptimization only improves the edge performance with limited gain and brings additional systemcomplexity.

13、To enhance mobility,5G introduced technologies like Conditional HandOver(CHO),Dual3/40Active Protocol Stack(DAPS),and L1/L2-triggered Mobility(LTM)to address service continuityand seamless transition issues during terminal handovers.CHO configures handover conditions tothe User Equipment(UE),allowin

14、g the UE to determine the timing of handovers based onconditions.DAPS activates two protocol stacks simultaneously,ensuring uninterrupted datatransfer during the handover process.LTM,through L1/L2 signaling,performs measurementreporting and cell handovers,reducing mobility delays 3.It can be seen th

15、at CHO,DAPS andLTM are all optimizations of the handover process,and do not eliminate the handover process.The terminals still need to perform handovers when moving,and this will become more frequentin environments with small cell coverage,thereby increasing signaling interactions betweenterminals a

16、nd networks,as well as power consumption for both terminals and networks.Theprevalence of small cell coverage is expected to be even more widespread in 6G.In addition,although these enhanced features provide certain gains,they are all limited and require theterminal to have corresponding capabilitie

17、s,which increases the design complexity of theterminal.Furthermore,solutions based on Centralized Radio Access Network(C-RAN)definingsuper-cell approaches have been discussed in the industry.However,considering the physicallayer design based on existing technologies,such as terminal addressing based

18、 on Physical CellIdentity(PCI)and Cell Radio Network Temporary Identifier(C-RNTI),the max number of user inthe super-cell can only be the maximum supported by the current standard design.This approachnot only fails to fundamentally address the logical constraints of existing radio access networksbut

19、 also introduces an additional layer of logical constraints with super-cell,increasing systemcomplexity.In summary,prior to 6G,mobile communication has been devoted to incremental correctionsbased on the basic architecture of cellular networks.Although some enhancement technologieshave been introduc

20、ed,providing certain performance gains,they are limited by the strong bindingrelationship between base station cells and user terminals.On one hand,they cannotfundamentally solve the problem and are not applicable to all terminals.On the other hand,theyintroduce significant complexity to both base s

21、tations and terminals,hindering device andoperational cost maintenance.1.3 Concept and ObjectivesIn the era of 6G,new trends,driven by new scenarios,frequency bands,and technologies,force us to reconsider,reflect,and expand our understanding of user-centric.In this process,theconcept of User is furt

22、her expanded,encompassing not only to customer(toC)users such asmobile phones but also to business(toB)users/customers,including industry applications andnetwork tenants,covering both content provision and consumption.Centric refers toempowering users with certain autonomy through customizable netwo

23、rks,providing friendlynetwork interaction and customization for users through open network infrastructure(channels,computing power,sensing,intelligence,etc.),and establishing a sound user experience evaluationsystem.The goal of user-centric has been long-standing.From an application layer perspectiv

24、e,end-to-end network services aim to fulfill user demands.Regarding physical layer transmissiontechnology,the best transmission performance involves arbitrary node connections without4/40considering cellular network restrictions.However,these two ideals were practically unattainablein 5G networks.To

25、 achieve the ultimate end-to-end user-centric and optimize physical layertransmissiontechnologywithoutconstraintsfromcellularnetworkarchitecture,logicalreconstruction of access networks is required.6G UCAN,which is not constrained by thedeployment of high-level nodes,serves as an access network cent

26、ered around users and services,flexibly organizing network nodes and resources to serve users.UCAN adapts flexibly to theneeds of users and services,with a design goal of consistent user experience(i.e.,UE can obtainresources for uplink and downlink transmission as needed from any location),avoiding

27、 complexand redundant patchwork construction,and adhering to the laws of technological evolution andindustrial development for system architecture and key technology research 4.Typical definitions of UCAN include:In terms of architecture and networking,the network will provide users with higher free

28、domand support deep customization based on user portrait.Different network architectureorganizations and deployment forms can be used for different users and service applicationsdynamically.The network tracks and maintains user context for the long term,perceives,analyzes,and intelligently predicts

29、information related to users and services,thus segmenting and friendlyhandling user/terminal requests.It quickly constructs new businesses and deploys wirelesstransmission services,providing efficient connection management mechanisms and topologyadaptive mechanisms,such as user-intent-driven and use

30、r-interest-sensing designs.In terms of resources,the development of new technologies such as cloud computing,bigdata,and AI helps the network establish and maintain an overall view and scheduling managementof multi-dimensional resources such as connections,computing power,data,and models.Thisensures

31、 real-time and precise delivery of various resources,such as beams,bandwidth,power,TRP,channels,and link interfaces,optimizing energy and spectrum efficiency,keeping userterminals(groups)always in the optimal service state.In terms of user services,the network grants users greater autonomy,meeting d

32、iverseconnectivity and networking needs for different users/terminals in various scenarios.Users canautonomously select the network type(e.g.,Sidelink,V2X,NTN)based on terminal capabilities,service requirements,and network conditions or make mobility decisions.They can also providefeedback to the ne

33、twork based on service or networking requirements,requesting the network tocoordinate corresponding resources and configurations.This allows users to switch betweenterminals and network(or relay)nodes as needed,offering and using services accordingly.Chapter 2 Scenarios and Requirements2.1ScenariosU

34、ser-centric 6G radio access network,building upon the applications served by 5Gtechnology,will achieve on-demand flexible networking across multiple dimensions,includingspectrum resources,functionality,services,computing power,and security,catering to both toBand toC users.This integration aims to m

35、eet the diverse requirements of emerging fusion services.5/40It not only provides personalized services such as mobility management,policy control,sessioncontrol,and personal data management but also optimizes signaling overhead and networkperformance at the user level.It is poised to become one of

36、the disruptive technologies in the 6Gera.Novel Converged NetworksLooking at the future 6G network,there is an urgent need to achieve full coverage.Itsconverged network deployment types include but are not limited to,ultra-dense networks,wide-area coverage networks,edge cloud networks,integrated spac

37、e-terrestrial networks,andUAV networks.Creating a fusion three-dimensional network is a focal point of 6G development.The user-centric access network can accommodate various network types,such as the Internet ofThings(IoT)and mobile broadband networks.It provides precise services for users under dif

38、ferentnetwork architectures by selecting available access points based on demand.Immersive Service CommunicationWith the rapid development of 5G streaming and multimedia services,immersivecommunication based on Extended Reality(XR)communication,holographic communication,remote multi-sensory intellig

39、ent communication,and other diversified services,is expected tobecome killer applications of 6G,which can provide users with immersive user experiences.Immersive communication scenarios require the network to provide ultra-high data rates andultra-low latency,ultra-high reliability performance guara

40、ntees.To this end,realizing auser-centric access network architecture will become an important consideration for building thisservice.UCAN guarantees independent service transmission for each user through multi-nodecoordination and flexible grouping settings.At the same time,it provides users with m

41、ore flexibleand richer resources to meet the needs of high-traffic services across the network.Communication-Sensing-Computing Integration6G networks can utilize communication signals to achieve sensing functions such asdetection,localization,recognition,and imaging of targets,acquiring environmenta

42、l informationfor enhanced user experiences.UCAN not only possesses strong sensing capabilities,includinguser service requirements but also swiftly and uniformly coordinates computing resources amongmultiple users to meet the networks computing demands.This achieves the performance ofintegrated sensi

43、ng,communication,and computation networks 4.Intelligent Service ScenariosIn the era of 6G,with the blueprint of creating a world where everything is intelligentlyconnected,there will be an increasing number of new intelligent terminals.With the assistance ofAI technology,intelligent entities can con

44、tinuously learn and autonomously collaborate,empowering applications in smart healthcare,industrial IoT,smart homes,autonomous driving,and many others.Driven by AI technology,UCAN detects users and their service requirements,adaptively constructs flexible cells for users,and achieves path selection,

45、wireless resourcecoordination,and access node selection network functionalities.Additionally,leveraging thedistributed collaborative capabilities among multiple nodes,it addresses pain points such as datastorage,computation,and privacy protection in intelligent scenarios.6/402.2 Requirements2.2.1 Se

46、amless ConnectivitySeamless connectivity primarily refers to meeting the users need for connectivity andcommunication anytime,anywhere.As service integration progresses and deployment scenariosexpand,users require connectivity and communication in various locations,such as on airplanes,in remote are

47、as,and in maritime zones.To meet the users demand for a seamless connection,the6G network will extend continuously toward the space,air,ground,and sea.The ground cellularnetwork will be integrated with space networks including high-orbit satellite networks,medium-and low-orbit satellite networks,hig

48、h-altitude platforms,and UAV,as shown in Figure 2.2-1.Itwill build global wide-area coverage of a space-air-ground integrated three-dimensional network,achieving the effect that anyone can communicate with anyone at anytime and anywhere.Figure 2.2-1 User-Centric Seamless Connectivity Network2.2.2 Di

49、verse ConnectionsDiverse connectivity mainly refers to the differentiated demand of users for connectioncapabilities.It is necessary to provide users with the best connection service to meet their needs.With the connection of people,machines,and things,and the connection between the physical andvirt

50、ual worlds,there are a large number of connectable physical entities,as shown in Figure 2.2-2,including smart terminals,sensors,wearable devices,vehicles,and industrial control equipment.Due to the diverse requirements of different users for connection capabilities,providing users withoptimal connec

51、tion capabilities and deploying connection functionality on demand requires auser-centric approach.It supports the intelligent interconnection and fusion of various7/40heterogeneous networks,dynamically meeting complex and diverse scenarios and servicerequirements,including future applications like

52、unmanned driving,smart homes,and virtualreality.It meets the demands for high bit rates,low latency jitter,and higher reliability whileachieving network-side integration of multi-access,connections,and services.Figure 2.2-2 User-Centric Diverse Connection Network2.2.3 High-Speed Data TransmissionAs

53、infrastructure such as networks,AI computing,and edge cloud continues to improve,andwith the popularity of online education,live e-commerce,metaverse,remote healthcare,andwidespread entertainment and social activities,there is a continuous increase in user demands forhigh-traffic applications and th

54、e speed of Internet of everything.For instance,metaverse servicesrequire real-time data transmission,real-time audio-video communication,and the capability tosupport multiple users simultaneously online,necessitating networks to provide high-speed,low-latency data services.Therefore,a user-centric n

55、etwork needs to offer high-speed,low-latency,and highly reliable data transmission according to user requirements to better support real-timeand high-speed applications.2.2.4 Data-Driven Computing DemandWith the advent of the 6G era,the degree of digitization is deepening,and global data-driventrend

56、s are accelerating.Real-time data processing and ultra-large-scale device connections willbring people an increasingly sophisticated user experience and convenient life.This trend alsoplaces high demands on information processing capabilities based on computing power.UCANnot only needs to provide ro

57、bust computing support but also requires the ability to dynamicallyschedule personalized resources.The focus will be on how to schedule tasks to match computingresources based on users different task requirements.Designing incentive mechanisms toencourage users to coordinate and allocate computing p

58、ower and ultimately achieve efficientempowerment of computing resources will become one of the key directions for future UCANconsiderations.8/402.3 Evaluation MetricsLatencyControl plane latency refers to the transition time from the most battery-efficient state(e.g.,idle state)to the start of conti

59、nuous data transmission(e.g.,activity state).The goal in 5G is 20ms(eMBB,URLLC).UCAN adopts a cloud-based control plane centralized scheduling system,expanding the 2-step RACH within the CCU(Msg1 and Msg3,Msg2 and Msg4 combining toreduce RACH latency),further reducing control plane latency in 6G.Sim

60、ultaneously,theimprovement in hardware processing capability effectively shortens the message processinglatency for UE and TRP.MobilityMobility interruption time refers to the shortest duration during which a user terminal cannotexchange user plane network packets with any base station during a mobi

61、lity transition.Themobility interruption time delay target of beam mobility and CA mobility described in 5G featuresis 0ms.UCAN uses multiple TRPs to serve a single UE,and the mobility interruption delay isclosely related to the TRP organization problem.Since these TRPs can be located under the same

62、DDU or different DDUs,TRP organization coordinated by CCU and DDU can achieve 0msmobility interruption delay in both inter-DDU and intra-DDU scenarios.System CapacitySystem capacity is defined as the number of users satisfying specific services in a cell orgeographical area(m2).The specific indicato

63、rs are:Y%of UEs in the area meet the requirements.The judgment standard for UEs to meet the requirements is that all flows reach the data error rateand delay budget requirements,that is,more than X%of the data is successfully transmittedwithin the air interface delay budget.Typical values for X and

64、Y are 90 and 99.This definition comes from 3GPP XR capacity evaluation.Immersive services,representedby XR services,are recognized as featured applications in 6G.Immersive services haverequirements for high speed,low latency,and high reliability.Existing single metrics such as peakrate,spectral effi

65、ciency,latency,and reliability are not sufficient to characterize system-levelsatisfaction for such services.To more intuitively reflect the different user and servicerequirements of 6G compared to 5G,it is necessary to define system-level metrics for suchservices.System capacity is an intuitive req

66、uirement for 6G network operation and 6G featureduser satisfaction.Chapter 3 System DesignThe system design of the user-centric access network includes the following paths:1)Realizebasic features such as user-centric connection and transmission through simplified and optimizedunderlying design.2)Imp

67、lement an end-to-end architecture for the user-centric network from theoverall architecture level,adopt a unified and simplified design for different access methods,andintroduce native intelligence,integrated sensing and communication,and computing collaboration.9/403)Explore more innovative designs

68、 to achieve architectures that are more conducive touser-centric,such as new security(e.g.,blockchain)and tight coupling of the application layerwith the access network.Figure 3-1 Design Route of User-Centric Access NetworkThis chapter first introduces the main features of the UCAN system architectu

69、re,and then,addressing the first design route issue,proposes a CCU-DDU-TRP architecture based on theevolution of 5G.Then,based on the research on the follow-up design route issues and theexploration of network architecture evolution,possible design directions are given.3.1 CharacteristicsUser-centri

70、c,as a major feature of 6G networks,enables the network to intelligently sense theusers wireless communication environment,and then flexibly organize the required networkaccess points and resources to serve the user,making the user always feel at the center of thewireless signal coverage.To embody u

71、ser-centric and meet diverse scenarios and needs,user-centric networks mainly possess five key characteristics:deep customization,elasticreconfigurability,openness and compatibility,intelligent adaptive user services,and enhanced userrights.3.1.1 Deep CustomizationIn the traditional sense,a customiz

72、ed network means a dedicated network,that is,using aspecific frequency to serve specific users in a specific area.In the 6G era,the network needs to putuser needs at the core of network design and operation,meet user-specific requirements for thenetwork,provide customized functions and services to i

73、mprove user satisfaction and experience,and enhance network flexibility and adaptability.User-centric deep customization networks aim toprovide highly personalized and customized network services and experiences based on the needsand preferences of different application scenarios and user groups.Fro

74、m a deployment perspective,in the user-centric radio access network,widely deployednetwork nodes will dynamically construct flexible cell for each user based on precise user needs.For each user,the flexible cell is deeply customized in real timeanytime,anywhere,for anyservice,and any user type.User-

75、centric radio access networks are widely applicable to toB andtoC networks.From the network side,network nodes can be deployed and reused efficiently andenergy-efficiently.From the perspective of resources and applications,the network will customize the allocationand optimization of network resource

76、s based on factors such as user location,device type,andnetwork quality to provide optimal performance and user experience.For example,the networkcan provide customized optimization and support based on the applications and services used by10/40users.For specific application scenarios(such as online

77、 gaming and video streaming),the networkcan provide specially optimized bandwidth,latency,and other services to deliver better applicationperformance.Additionally,the network can make autonomous decisions and adjustments based onuser needs and environmental conditions.For example,based on factors su

78、ch as user priority andresource utilization,the network can automatically select the optimal path,allocate the mostsuitable resources,and dynamically adjust in real time.3.1.2 Elastic ReconfigurabilityTraditionalnetworkarchitecturesareoftenbasedonfixedtopologiesandstaticconfigurations.However,with t

79、he development of technologies such as cloud computing,IoT,and5G,user demands for networks have become increasingly diverse and dynamic.User-centricelastic reconfigurable networks aim to provide a better user experience and network resourcemanagement.They achieve this by adapting to changing demands

80、 and environments,supportingemerging application scenarios and service models(such as edge computing,virtual reality,andIoT),thereby enhancing network reliability,resilience,and efficiency.Different from the cellular network that is always activated and waiting for potential users,the user-centric r

81、adio access network is highly scalable and reconfigurable.They canautomatically adapt to changes in the number of users,application requirements,and networktopology.For instance,through elastic reconfiguration and dynamic configuration of network-sidenodes,such as quantity,transmission power,and tra

82、nsmission mechanisms(e.g.,massive MIMO),the network side can optimally control interference and reduce network energy consumption.Apart from conventional communication environments,user-centric radio access networks canalso handle sudden adverse conditions,such as natural disasters.The elastic recon

83、figurablenetwork supports the robustness and self-healing capability of network access.The design andapplication of flexible cell can promote the flexibility of network facilities and achieve rapidnetwork deployment.Changes within a certain range of the network will not destroy the networksability t

84、o meet user needs.Network resources(such as bandwidth,storage,and computing capabilities)can bevirtualized and pooled to more flexibly allocate them to different users and applications.Thenetwork can monitor and analyze the utilization of network resources in real time,sense changesin user demands b

85、ased on real-time network state,and adjust and reconfigure network-side nodesand resources automatically to provide optimal network services.3.1.3 Openness and CompatibilityIn traditional network models,networks are typically closed,limiting interoperabilitybetween users and other networks and servi

86、ces.However,with the acceleration of networkdevelopment and digital transformation,there is a growing demand for seamless connections andintegration across networks and platforms.User-centric open and compatible networks will applyto various types of network-side access points,providing users with a

87、n open,interoperable,andflexible network environment to meet diverse application and service requirements,facilitating theinterconnection of various applications and services.11/40In the 6G era,different types of network-side access points and wireless interface types(macro base stations,satellite p

88、latforms,UAV,V2X,IAB,etc.)will coexist in the same network.User-centric radio access networks will flexibly detect and construct various network-side accesspoints,support multiple access technologies(such as wired,wireless,and fiber optics),andseamlessly integrate with different platforms and device

89、s.The user-centric radio access network can also be compatible with other network types,suchas co-networking with macro cellular networks and satellite-terrestrial converged networks.Thenetwork can be compatible with different network technologies and protocols,providing openinterfaces and standards

90、 for different networks and services to connect and interact,achievingcross-network connectivity and interoperability.In addition,the user-centric network encourages data sharing and openness,allowingdifferent nodes to share and utilize data resources.Moreover,the network empowers users withmore con

91、trol and autonomy,enabling them to independently choose and manage networkconnections and services.3.1.4 IntelligentAdaptive User ServiceIn traditional service models,services are often generic and standardized,unable to meet thepersonalized needs of different users.User-centric intelligent adaptive

92、 user service networksleverage artificial intelligence and adaptive technologies to analyze and understand user behavior,preferences,and contextual information,providing users with intelligent,personalized,andautomated service experiences.User-centric radio access networks dynamically detect user be

93、havior and service demands.For different types of terminals and services,the network can adaptively construct flexible cellsfor users based on their actual needs.Network services automatically make decisions andoptimization based on intelligent algorithms and rules.It can automatically adjust servic

94、e policiesbased on the users geographic location,context information,and real-time data to provide a betteruser experience.Through continuous learning and iteration,utilizing machine learning(ML)and adaptivealgorithms,the network can continually optimize service models,improve the understanding ofus

95、er needs,and enhance service quality.Network services can provide support across multiplechannels and platforms to accommodate diverse user needs,offering a consistent serviceexperience across different devices,applications,and social media,achieving seamless integrationacross platforms.Furthermore,

96、in 6G,users requiring specific services can access as multiple UEs.In certaincases,the relationship between users and UE needs to be reconsidered.New service formsintroduce the demand for multi-mode coordination,such as co-flow and multi-model requirementsfor XR and holographic service,requiring coo

97、rdination between UEs to meet specific servicerequirements.In some new scenarios,such as smart homes,industrial IoT,and local area networks,the aggregation of UEs needs to be considered.12/403.1.5 Enhanced User RightsIn the traditional IMT telecommunication technology system,the network equipmentven

98、dor,telecom operator,and terminal vendor each have well-defined and relatively fixedrights allocation(such as roles,positions,rights,and benefits)and value spaces.With thedevelopment of 6G technologies such as intelligent computing,distributed computing,andspace-air-ground integration,and the increa

99、sing demand for more autonomy from numerous toBindustry customers,the concept of the user-centric rights system is introduced.Rights refer tothe roles,positions,rights,benefits,etc.,allocated to specific entities in the 6G system.Operationssuch as the distribution,modification,and trading based on r

100、ights can lead to greatervalue-creation spaces.The main entities with rights in the 6G wireless system include telecomoperators,special network element node owners,and super terminal users.Rights include,butare not limited to,network construction participation rights,service control dominance rights

101、,anddigital asset ownership rights.The user-centric rights system introduces new means of rights control,including userparticipation,resource openness,service creation platforms,asset transaction flow,and varioustechnical means related to user rights.This contributes to the prosperity of DOICT busin

102、essmodels,continuously enhances the value creation space of the 6G wireless system,and constantlyimproves the participation contribution and interest value feedback of multiple user entities.3.2Architectures3.2.1 CCU-DDU-TRPArchitectureThe 6G user-centric wireless access network maintains the consis

103、tency of user connectionsthrough network cloudification,and based on the sensing of user information(location,service),dynamically organizes network-side nodes,interfaces,and resources to flexibly match userterminal needs.In a simplified way,it can realize on-demand satisfaction of any location,anyc

104、apability,and any type of terminal,and ultimately form an access network architecture withflexible connections of multiple network nodes and multiple terminals.The basic architecture ofUCAN is shown in the figure.The main design includes cloud-based control layer and distributedaccess layer.13/40Fig

105、ure 3.2-1 UCAN ArchitectureBased on cloud-based control layer signaling,which uniquely identifies and tracks userservice requirements,UCAN guarantees the effectiveness of user/UE context and service-relatedconfigurations on a large scale.This realization of user-level flexible cell simplifies user m

106、obilityprocesses,serving as the carrier for control continuity.The distributed access layer enables users to obtain service data through the nearest datasource through localized data transmission and transmits it over the air interface through theoptimal path,achieving low latency,high reliability a

107、nd large capacity,and is the carrier of datacontinuity.On the one hand,it needs to quickly obtain upper-layer packet data,and on the otherhand,it needs to ensure zero-interrupt delay and transmission rate guarantee during usermovement.At the same time,it uses the simplest method to ensure that the U

108、E is always at thecenter of the flexible cell through multiple TRP coordinated transmission and other methods,avoiding complex operations such as handover.Specifically,based on different scenario requirements,the basic UCAN architecture can beexpanded and refined into the following forms:1)Refined A

109、rchitecture for toC ScenariosFigure 3.2-2 Architecture for toC ScenariosMain Functions:14/40Cloud-Based Control Unit(CCU):Provides the management plane and control planefunctions of the network.It includes traditional control plane functions,such as systeminformation management related to AS/NAS,est

110、ablishment/maintenance/release of RadioResource Control(RRC)connections,paging control and security functions,including bearermanagement,mobility management,UE measurement,report management and NAS informationtransmission.CCU also performs management plane functions in UCAN,such as UE contextmanagem

111、ent and TRP management.Leveraging cloudification characteristics,the CCU supports service-oriented networkfunctions and native intelligent.For instance,the State Management Function(SNF)can offerunified context management of multiple control plane functions,and the central-level AI functionprovides

112、intelligent control over overall wireless resources,data resources,computing resources,AI models,and instance resources in near real-time(10ms).Distributed Data Unit(DDU):As the anchor point of the user plane(UP),DDU manages thebasic UP functions,including service flow mapping,resource allocation,an

113、d reliable transmissionof the air interface.It receives data from the core network user plane(such as UPF),or directlyfrom the data center/application,caches data and forwards it to the TRP that constitutes theflexible cell.DDU also undertakes resource management,TRP node selection,L1 measurementand

114、 management,and dynamic resource scheduling functions and middle-layer AI functions,which provide management and control of data resources,computing resources,and AI model andinstance resources in DDU.Access Point(TRP):In the RAN,TRP connects directly to UE.TRPs in UCAN can beconstructed using L1,L2

115、,or L3 network entities.If the TRP is an independent base station node,such as a vehicle-mounted base station,UAV,or satellite base station,then the TRP is an L3 node.For a low-cost TRP,it can be used as a Remote Radio Head(RRH)with low physical layer nodes.In other cases,UP functions can be deploye

116、d between DDU and TRP as needed based on user andservice requirements.The flexible deployment of UP function modules is widely applicable tofixed or semi-static TRP nodes and various users and services.TRP is the network node that buildsflexible units for corresponding user services.Additionally,TRP

117、 provides wireless-relatedfunctions and deploys AI instances.2)Refined Architecture for toB ScenariosFigure 3.2-3 Architecture for toB ScenariosMain Functions:15/40CCU:In the toB architecture,the CCU can be self-built by users or shared with toC in theform of user-customized spaces.The user-customiz

118、ed space connects to the users dedicatedservice node in the CN,where the user is the administrator of customized space permissions(access,view,operate),ensuring the security of user services and privacy.In addition,the CCU inthe toB scenario can consider a more closely coordinated mode with the CN C

119、P.DDU and TRP:In the toB architecture,both DDU and TRP have highly customized features.DDU supports DDU-H and DDU-L modes,while TRP supports flexible UP protocol functionsfrom L1 to L3.DDU-H and the sinking CN UP can be co-deployed with the users MEC.For datacollection scenarios,DDU-H is adaptable t

120、o various network access points and can utilize WLANto provide latency-insensitive,high-bandwidth upload services.For interactive scenarios,serviceswith moderate communication metrics can be provided through flexible combinations of DDU-Land TRP.For control scenarios,low latency and high reliability

121、 services are provided through TRPdirectly connected to CN UP and multiple TRP links.Intelligence:In the toB architecture,high-level automation deployment,operation,andmaintenance will be achieved through intelligence,reducing the threshold for networkconstruction and usage,and realizing cost reduct

122、ion and efficiency improvement.3.2.2 Distributed NetworkArchitecture DesignTo achieve end-to-end unity and simplicity centered around the user,a flexible distributeddesign can be employed.This distributed network architecture possesses the followingcharacteristics:Diverse integration of access modes

123、:6G networks consist of numerous user networks(subnets),and users from different subnets may access the 6G network in various ways.Therefore,the distributed network integrates diverse access modes and coordinatesmulti-access paths to provide users with more reliable and efficient connection channels

124、.On-demand deployment of connection functions:Due to the differentiated requirements ofdifferent users for connection capabilities,the distributed network needs to flexiblydeploy the control plane and user plane in a relatively wide area to provide users withoptimal connection capabilities.Multi-par

125、ty collaboration of computing functions:With the increasing requirements ofapplications,it has become a common trend that computing needs to be gradually sunkand diffused to the network edge for users.6G networks will form a super networkcomputingservicethatorchestratesandschedulesnetwork-nativecomp

126、utingcapabilities(including computing power,algorithms,and data)for a large number ofusers.On-demand orchestration of data functions:Different users have different requirements fordata processing.The 6G network will provide a unified distributed data framework toefficiently cope with complex data ap

127、plication modes.Decentralized trust based on consensus mechanism:The 6G distributed network will builda decentralized trust architecture to ensure that multi-party trust can be establishedquickly and accurately,providing strong security support for building and maintaining astable,fair,and open 6G c

128、ooperative business ecosystem.16/40Figure 3.2-4 Distributed Network Architecture3.2.3 Multi-Access ConvergenceArchitecture DesignA user-centric network needs to integrate different types of network-side access points andwireless interfaces,such as base stations,satellite platforms,Sidelink nodes,UAV

129、,V2X,IAB,andtheir corresponding air interfaces and backhaul links.Based on user demands,an access networkcentered on users needs to be rapidly and seamlessly organized,enabling users to participate morein defining,configuring,and controlling relevant network functions that provide services.It offers

130、support for multimodal technologies and collaborative use of multiple terminals,dynamicallymatching and updating network configurations in real time according to user environments andservices.The design aims to create a user-centric,multi-network node,and multi-terminal flexibleconnection converged

131、network.UCAN enhances user involvement at different levels through a layered convergencemechanism,ensuring unified,intelligent,and diverse connectivity services:Application service layer:At the network edge,by establishing a collaboration mechanismbetween the access network and MEC,the multi-access

132、capability fusion of the accessnetwork and MEC is enhanced.User and terminal needs are obtained,refined,andprocessed in a friendly manner at the application layer.Real-time network state and userneeds are quickly orchestrated and managed,helping the network to provide suitableconnection capabilities

133、 and service transmission according to user service types.Mobile network layer:Based on the information interaction between the network and users17/40and the network internal access network and core network,the network schedules usersto flexibly switch between different network systems according to

134、user service types andreal-time radio network and air interface environment.It realizes efficient orchestrationand on-demand service provision of cellular and non-cellular,3GPP and non-3GPPnetwork systems,terrestrial and non-terrestrial networks,and base stations and relaynodes.Accessnetworklayer:Wi

135、ththehelpoftechnologiessuchascloudification,service-oriented architecture,network modularization,and functional componentization,the elastic customization of the network protocol stack and the plug-and-play of accesspoints(network elements)can be realized.It can provide users with on-demanddeploymen

136、t and dynamic control of network functions and nodes,and provide accessand services for different types of terminals and services.Air interface layer:Together with the network architecture,it explores fusion designsolutions for different technology regimes and protocols.It achieves non-discriminator

137、ynetwork access and management for terminals under different links through unified airinterface control,reducing the complexity of terminal access and network equipment.For instance,enabling users to freely switch between terminals and network(relay)nodes,accessing and using services provided by oth

138、er terminals(or base stations),oracting as a network(relay)to provide network configuration and management for thesame or different users terminals(groups).Figure 3.2-5 User-Centric Converged Network ArchitectureTo achieve a user-centric multi-access deep converged network,it is necessary to carry o

139、utunified process and protocol design for different types of terminals and users,and different typesof network access points.This ensures that the user-centric network possesses unified control andcoordinated scheduling capabilities for converged access.These capabilities include multi-access18/40sc

140、heduling,mobility management,session management,user-plane management,QoS,servicecontinuity assurance,and security authentication.The goal is to achieve the optimal match ofresource utilization,service requirements,and user experience.In the subsequent chapters,exploration will be conducted from var

141、ious perspectives such as multi-air-interface convergedaccess,plug-and-play network elements,user-centric mobility,and user rights enhancement,andintroduce the corresponding key technologies.Additionally,it is also possible to combineintegrated sensing and communication to provide the access network

142、 with real-time sensing ofnetwork state,users,and surrounding environment.Based on native intelligent capabilities,diverse connection orchestration,scheduling,and transmission management will be employed toensure the continuity and service quality of connection control and service data transmission.

143、Chapter 4 Key TechnologiesThis chapter introduces key technologies centered on the user to empower the UCANnetwork architecture.The aim is to meet user connectivity needs in various scenarios,providinghigh-speed data transmission and a consistent experience.Through friendly network interactionand cu

144、stomization,users gain higher autonomy,enabling user-centric connection and transmissionservices.Figure 4-1 User-Centric Key Technologies19/404.1Access and Connection Management Technologies4.1.1 Multi-Air-Interface Convergence TechnologiesIn the face of differentiated coverage over land,sea,and air

145、,and to better meet user needs,the radio access network of 6G needs to be designed with a unified architecture.Users can achievemulti-network converged access including ground,underwater and satellite.Through unifiedcontrol of the air interface,users can achieve seamless network access and reduce th

146、e complexityof terminal access to the network.Regarding the convergence of satellite and terrestrial networks,the user-centric 6Gsatellite-ground fusion communication network exhibits characteristics such as multi-layerstereoscopic structure,diverse terminals,highly dynamic spatial nodes,limited res

147、ources in spatialnodes,variable topology structures,high propagation delay in satellite links,and vulnerability ofsatellite broadcast transmission links to attacks.It faces significant challenges in terms oftransmission efficiency,interference management,mobility management,security,and privacy.Long

148、-distance between satellite and ground causes significant transmission delays,and thedelay rapidly changes with satellite movement.To address the challenges of large andunstable transmission delays in satellite-ground converged networks,consider adoptingnon-orthogonal multiple access technology to i

149、ncrease transmission opportunities,enhance support for a larger number of users,and effectively reduce access and datatransmission delays.This may involve dynamically enabling or disabling HybridAutomaticRepeatRequest(HARQ)functionalitybasedonscenedynamics.Additionally,applying satellite-ground coop

150、erative batch access mechanisms,whereground macro base stations aggregate user requests in a given area and make batchaccess decisions and resource allocations on behalf of satellites,reduces unnecessarydelays caused by individual user random access to satellites.In a satellite-ground integrated com

151、munication system,addressing interference issueswithin the same satellite system,between satellite systems,and between satellites andthe ground is crucial.Key technologies such as spectrum allocation,beamforming,reinforcement learning,federated learning,and cognitive radio are essential to avoidinte

152、rference between telecom devices in the satellite-ground converged network.Flexible spectrum usage can be employed to better utilize the spectrum.Using 3Dbeamforming antennas on satellites can further mitigate interference to terrestrialnetworks.4.1.2 System Information Set and Flexible TRPAccessUCA

153、N can adopt the classification method of 5G system information,including basic systeminformation and other system information.The transmission of system information still combinescontinuous broadcasting and on-demand methods.However,in 6G,the generation andtransmission nodes of system information ca

154、n be optimized based on user requirements andnetwork deployment.20/40For basic system information,especially access-related information,system information settechnology can be introduced.This involves aggregating system information(SI)related tomultiple carriers and sending them on a single carrier(

155、referred to as a system information set).This approach allows carriers not sending SI to remain in sleep mode for a longer time.Forinstance,a low-frequency,broad-coverage TRP can send a system information set containingsystem information for all network nodes within its coverage area,while high-freq

156、uency TRPsmay not need to send system information.From the network perspective,this reduces base stationpower consumption,SI transmission workload,and overhead(configuration,scheduling),simplifying network operations.From the terminal perspective,it reduces the complexity ofdetection.System informat

157、ion set management includes three steps:1)System information collection:A central control node is responsible for collecting,integrating,and selecting proxy nodes(nodesresponsible for centralized system information publication)within a certain range for cell systeminformation.2)System information in

158、tegration:After the central control node collects systeminformation from multiple cells,it integrates and categorizes them into common systeminformation and differential system information.This categorization reduces the workload andoverhead(configuration,scheduling)of system information publication

159、,simplifying networkoperations.3)System Information Transmission:Common system information can be send byproxy nodes,and differential system information can be send by source cells or by proxy nodesuniformly.Additionally,for other system information,they can be uniformly notified by the carriersendi

160、ng system information set.Terminals can initiate on-demand requests at any network node,and the network side can send dedicated signals to terminals or broadcast information to terminalsbased on the smaller area TRP/carrier to which the terminal belongs.After terminals receive the system information

161、 through broadcasting,they can obtainresource configuration for multiple Random Access Channels(RACH).Different access channelscorrespond to different frequency resources and beams.Terminals can select the optimal RACHresource for access based on coverage,frequency,and air interface quality.Optimal

162、RACHselection can improve access success rates and rapidly establish connections and services on themost optimal frequency band in terms of coverage/energy efficiency.Furthermore,6G terminals have more flexible options for choosing access nodes compared to5G.Access nodes can be selected by terminals

163、 or the network,using either single-TRP randomaccess processes or multiple TRP joint random access.Single-TRP random access refers to the UEchoosing an access point based on the downlink signal measurements sent by the access nodes,initiating the access process on the chosen access point.Multiple TR

164、P random access means thatthe network configures the same access resources for multiple nodes.When a UE initiates anaccess request,these network nodes can receive and measure the access request information,determining which access nodes can better serve the UE.4.1.3 UE Connection StatesAfter the ter

165、minal initially accesses the network,it can remain in the RRC_CONNECTEDcontinuously.After that,unless the UE leaves the CCU area or disconnects from the network,theUEs RRC state has only one RRC_CONNECTED(That is,RRC_IDLE,RRC_INACTIVE and21/40other RRC states defined in 4G and 5G are not considered)

166、.Under the RRC_CONNECTED,based on the presence of stable physical layer channels,it is divided into two sub-states:non-active and active.Both states are sub-states under the RRC_CONNECTED.Specifically:Non-active state:This is the terminals power-saving state.The network and the terminalmainly mainta

167、in security context and bear context.It can also have a complete Data Radio Bearer(DRB)configuration.There is no fixed physical layer channel between the terminal and thenetwork,meaning the terminal does not maintain fixed active air interface resources with specificDDU/TRP.When a specific DDU/TRP n

168、eeds to be activated for transmission,the correspondingphysical layer configuration can be pre-configured and activated on demand.Active state:This is the state where the terminal can continuously transmit data.The usercontext is maintained,and the terminal maintains UEs physical layer channel with

169、the networkand maintains the activated air interface resources/physical layer configuration with one or morespecific DDU/TRPs.Only in the active state can flexible cell be formed and flexible cellmanagement be performed.4.2Networking and DeploymentTo achieve the goals of cost reduction,energy consum

170、ption reduction,and adaptability tonew scenarios and demands,the 6G radio access network(RAN)needs to break through inarchitectural design and explore new flexible networking and deployment key technologies toadapt to future evolving requirements.4.2.1 Plug-and-Play Network Element TechnologyWith th

171、e rapid development of emerging services,diversified service needs continue toincrease,and the burst characteristics of services also increase.The existing always-on mechanismof network elements has the problems of high energy consumption and large interference.Therefore,a dynamic network element st

172、ate management mechanism is needed.When users needit,new network elements can be turned on or added.Through this plug-and-play method,on-demand coverage and services can be provided to better meet user needs.When new network nodes join the network,they should be able to quickly handshake,achieve cov

173、erage expansion,and deploy network functions on demand,effectively reducingnetwork energy consumption and functional redundancy,saving network costs.By allocatingsuitable resources,such as computation power,storage,and wireless resources,to the network andcoordinating with on-demand generated networ

174、k functions,based on artificial intelligence anddigital twins,a self-optimized,self-evolving,and self-growing high-level network autonomousoperation method can be implemented to address potential efficiency,cost,and user experienceissues.The management of networks with plug-and-play nodes mainly foc

175、uses on three aspects:access point sensing,access point self-configuration and self-optimization,and cloud-edgecollaborative control.Access point sensing:In a scenario with various coexisting access node types,it involvessensing various types of access requests for different access nodes and initiat

176、ing appropriate22/40handshake and control signal procedures.For different types of access points,accurateidentification and rapid completion of access are required for flexible expansion to achievecoverage.This necessitates standardized handshake processes and parameters for mutualrecognition betwee

177、n nodes.Self-optimization and self-configuration of access nodes mean that when access points arenewlyaddedtothenetwork,theycanautomaticallycompleteconfigurationandself-generation.When access points are running,they adjust parameters,self-optimize,andautomatically improve services based on real-time

178、 scenarios to better meet user needs.4.2.2 Deployment Based on CCU-DDU-TRPArchitectureScheme 1:Joint deployment with 5GSuitable for early 6G deployment,where the 6G user-centric network collaborates with 5G.5G is responsible for broad coverage,while 6G focuses on dense deployment in specific areas(e

179、.g.,using the 6GHz frequency band).Unified networking with 5G enables smooth deployment.Moreover,5G cellular networks can utilize low-frequency deployment for coverage assurance,while the user-centric network emphasizes data transmission,achieving the separation of thecontrol plane and user plane,an

180、d separation of coverage and data transmission.Scheme 2:Heterogeneous networking based on UCAN architectureInheterogeneousnetworking,the low-frequency TRP handlescoverage,managingconnection control and control plane signaling.The high-frequency TRP is responsible for datatransmission,handling user p

181、lane function.Both high-frequency and low-frequency TRPs connectdirectly to the cloud-based CCU.The high-frequency TRP can serve as a pure data transmissionchannel that does not support user access or it can support user access.If the high-frequency TRPsupports user access,relevant air interface res

182、ource configuration information can be sent by thelow-frequency TRP.Scheme 3:Continuous coverage in typical frequency bands(e.g.,6GHz)Homogeneous independent networking is particularly suitable for local coverage scenarios.When the coverage range of a single TRP is limited,a flexible cell(fCell)appr

183、oach can beemployed to enhance coverage.Methods for expanding coverage include:Option 1:Multiple TRPs in a large area are connected to one DDU and managed by a largeMAC,similar to the situation a single 5G cell with remote radio unit.Option 2:TRPs are connected to different DDUs.Different DDUs have

184、different coverageranges.When multiple TRPs are organized into fCells,it involves the coordination of multipleMACs.In actual deployment,Option 1,Option 2,and Option 1+2 all exist.Scheme 4:Further integration with other access technologies,such as NTN and SLThe UCAN based on CCU-DDU-TRP can be furthe

185、r expanded by incorporating the airinterface channels of NTN network(Scenario 1)or SL network(Scenario 2)as a part of theflexible cell.This aspect requires in-depth research.In the figure,the blue and red lines representequivalent entities for control signaling and data flow,not the connection relat

186、ionship.23/40Figure 4.2-1 Converged Networking4.3 Mobility Management TechnologiesMobility management has been a focal point in the IT and communication industry,posing acritical challenge when adopting a user-centric approach.This section unfolds UCAN-relatedresearch progress from various perspecti

187、ves.Addressing the strong binding between traditionalcells and users,the key technologies include the decomposition and expansion of the cell model toachieve service and resource decoupling and mobility centered on services.Additionally,dynamicorganization of network nodes for flexible cell technolo

188、gy allowing users to follow,improvementof mobility under idle and connected states for user-centric experience,and mobility based on userautonomous selection to meet diverse service needs and network environments are proposed ascritical technologies.4.3.1 Service-Centric MobilityIn existing protocol

189、s,when the cell changes,the user initiates a random access process toobtain the uplink synchronization of the new cell,and the users existing bearer is reconfigured,and the service entity corresponding to the service of data transmission is also reset orre-established.Additionally,when the target ce

190、ll and source cell belong to different CUs,keychanges are involved for security reasons.Obviously,the existing protocols do not achieve theeffect of resource and service decoupling,so when the cell changes,the data transmission serviceis also interrupted accordingly.In practical applications,the phy

191、sical resources and transceivers inevitably change frequentlyduring UE movement.If the service for each user is briefly interrupted with every resourcehandover,it significantly impacts the user experience.To address this issue,it is essential to decouple services and resources,shifting the mobilitya

192、nchor from physical cells to L2/L3 services.Resource handover,including carrier and TRP24/40handover,should primarily occur through flexible handover at the lower-layer L1 withoutaffecting L2/L3 services.This service-centric mobility,achieved through the decoupling of L1links and L2/L3 services and

193、the resource set of L1 links,ensures continuous service when theterminal moves from the source cell to the target cell.Even if there are changes in L1 links(carrier/TRP),the L2 transmission service(and the corresponding L3 connection service above)can maintain continuous service without the need for

194、 resetting or reconstruction of L2 protocolfunction anchors.This approach maximizes the smooth continuity of service operations,achievingseamless mobility.To achieve services unaffected by resource changes,the concept of cells in the cell modelneeds to be expanded.The cell model can be decomposed in

195、to service resource set,carrierresource set,and TRP resource set.With the expansion of the cell concept,the provided servicesbecome regional rather than cellular.Multiple transceiver nodes and carrier resources in theservice region are centrally managed,facilitating rapid interaction and saving sign

196、aling overhead.The handover procedure in the service region can also be appropriately simplified.As users move,if there are changes in carriers and/or TRPs in the service area,the users service transmissionservice remains uninterrupted,demonstrating the decoupling of services and resources.To suppor

197、tthis seamless continuity,the MAC entity should not be reset,and the RLC/PDCP/SDAP entitiesshould not be reconstructed,while the RRC entity connection should not be reconstructed 5 6.In the service-centric mobility scheme,the network configures a resource set for the UE,which includes multiple TRPs

198、and the corresponding carrier configuration.The UE can activatemultiple resource sets according to its own situation,and it can flexibly handover betweenresource sets.The resource set handover method mainly includes two parts:resourcepre-configuration and resource handover.Resourcepre-configurationi

199、nvolvesthenetworkconfiguringmultipleTRPsandcorresponding carrier resources for the UE through high-level signaling.The UE receives andstores multiple resource configuration information from the network.When the networkdetermines the need for resource handover,it sends L1 signaling to the terminal.Th

200、e terminalretrieves valid target resource information from the resource handover indication field.Alternatively,the UE can autonomously determine the need for resource handover and,ifnecessary,notify the network through signaling.The network then informs the UE to executeresource handover through L1

201、 signaling.To achieve UEs unconscious handover,in addition to resource configuration,the followingaspects also need to be considered:terminal processing complexity,standardized interfacesbetween DUs,time delay in TRP interaction,and advanced acquisition of CU deployment and TA.1)Terminal processing:

202、The terminal needs to support configuration information inmultiple spatial and frequency domains.2)CU deployment:Inter-CU handover involves key updates.To avoid the impact of keyupdates on UE service,the continuous security needs to be considered.3)DU interfaces:Considering standardized interfaces b

203、etween DUs and fast contexttransfer.4)TA acquisition:Initiated random access can cause temporary service interruption,notsuitable for high-latency services.A scheme for advanced TA measurement needs to beconsidered.25/404.3.2 Mobility Based on Flexible CellThe most critical challenge in a user-centr

204、ic access network is ensuring that users consistentlyreceive optimal quality of service.As users move and service requirements change,servicesprovided by traditional access networks face challenges from various factors such as wirelessenvironment changes and limitations in network device capabilitie

205、s.Dynamically and flexiblyorganizing access network nodes to form a user-level flexible cell that is available anytime andanywhere will be the key technology to solve this problem.As users move,channel conditions,signal quality,and service data volume will change continuously.By organizing a set ofd

206、ynamically changing access points,the network can ensure seamless service for each user.Asshown in the figure below,a TRPG is constructed by multiple TRPs,and each TRPG continuouslyupdates its TRPs with the users movement,eventually forming a user-centric flexible cell.Figure 4.3-1 User-Centric Flex

207、ible Cell ModelTo achieve this flexible and uninterrupted flexible cell concept,it is necessary to ensure thatthis user-centric access set is always in a free and borderless state.In other words,users shouldconstantly feel at the center of continuous wireless signal coverage,experiencing uninterrupt

208、edservice with non-redundant signaling transmission while ensuring robust security mechanisms toprotect user data.Specifically,cloudification networks maintain user context and maintainconsistency with high-layer configurations,dynamically organizing network-side nodes andresources through user loca

209、tion and service sensing to provide robust continuous control.In a large area,the network can uniquely identify and track user service requirements,maintaining continuity in the control plane(including the continuity of bearer configurations andrelated transmission parameters)under normal mobility.I

210、n other words,all accessible TRPs canrecognize the UE and continuously provide robust services to the UE.This can be achievedthrough cloudification of the control plane,where CCU serves as both the cloudized logic unit andthe control plane anchor point for serving UE.By adopting the State Network Fu

211、nction(SNF),which is a part of the access network,all26/40contextual information in network elements is uniformly stored and managed.SNF can be flexiblydeployed in the network according to the specific form of CCU,and provides data services andsubscription notification services for context establish

212、ment,update,query,and deletion.SNF canbe deployed on the same platform as CCU as an independent information storage node(especiallysuitable for service-oriented CCU)to realize persistent information storage and sharing.It can alsoexist in the form of distributed functional modules in CCU or even DDU

213、 to provide informationstorage,management,and synchronization.This ensures the effectiveness of UE context andservice configuration in a cloud-based large area,keeping the terminal in RRC-connected statesince the initial access to the network,distinguishing between power-saving state and continuousd

214、ata transmission state based on the stability of the physical layer channel.Therefore,considering mobility based on UCAN primarily involves two scenarios:Intra-DDU and Inter-DDU.In the former,since the RLC/MAC layer is not rebuilt,servicecontinuity is maintained.In the latter,flexible RRC,pre-establ

215、ished RLC/MAC layers,andsolutions such as mapping between old and new protocol layers can be introduced.For instance,the network can pre-configure RRC parameters associated with network-side nodes or physicallayer resources for the terminal.When the terminal associates with the corresponding network

216、node or uses the corresponding physical resource for access/transmission,the corresponding RRCparameters take effect.This allows for rapid application of new RRC parameters when theterminal accesses different network nodes or different physical layer resources.4.3.3 User-Experience-Centric MobilityU

217、ser-centric mobility is characterized by prioritizing user experience.This can be dividedinto two situations:idle mode mobility and connected mode mobility.User-centric idle mode mobilityIdle mode mobility is manifested as allowing the UE to remain in the network that bestmatches the service require

218、ments while minimizing UE power consumption,as long as keepingthe UE reachable during paging and meeting the users service establishment delay requirement.With the evolution and deployment of cellular communication technologies through 6 generations,operators often maintain multiple sets of cellular

219、 networks simultaneously.To facilitate UEresidence in the network that best matches user service demands,the network needs to provideinformation to idle mode UEs,such as supported service types,load information,and networkdeployment purposes,through system information.Additionally,the network should

220、 minimize cellreselection during deployment.For instance,guiding UEs to stay on the frequency layer ofmacrocells or using SFN technology to improve the frequency layer of coverage areas can reducepotential cell reselection measurements and system information acquisition,thereby extendingstandby time

221、.User-centric connected mode mobilityIn 5G,several processes like CHO,DAPS,and LTM have been introduced to optimize userhandover experiences.CHO achieves a reduction in handover triggering time by pre-configuringhandover conditions and target cell parameters for the UE.This approach omits the tradit

222、ional L3handover process,including measurement reporting and handover command issuance,therebyshortening the time required for triggering a switch.It prevents the occurrence of handover-relatedsignaling transmission failures caused by adverse channel conditions before the switch,thus27/40reducing th

223、e probability of handover failure.DAPS achieves zero-time interruption of datatransmission during handover by allowing UE to transmit in both source and target cellssimultaneously.LTM greatly reduces the data interruption delay during handover by replacing L3measurement report and handover command w

224、ith L1/L2 signaling,but does not support handoverprocess with key change.In addition to their respective application limitations,in 5G,mechanismssuch as CHO,DAPS,and LTM cannot be combined,hindering further improvement in userexperience.In 6G,the focus is on expanding the applicable scenarios and co

225、mbining the use of CHO,DAPS,and LTM to achieve the design goal of user-centric connected mode mobility and provide amore seamless and flawless handover experience.This is reflected primarily in:Handover preparation:The network pre-configures a set of candidate target cells for the UE,involving measu

226、rementconfiguration,resource configuration,etc.The UE performs measurements based on networkindications.Optionally,the UE can synchronize with candidate target cells in the intermittentperiod between communication with the source cell,measuring factors such as the beam quality ofcandidate target cel

227、ls.Handover execution:The UE triggers the switch based on network-indicated target cell/network load informationor evaluates the switch based on measurement results/data transmission experience.Handover execution:During the handover execution,UE L2 remains unchanged to achieve lossless handover.When

228、 the source and target L2 entities(MAC,RLC,PDCP)are located in the same physical nodeon the network side,the UE only needs to apply the target cells L1 configuration instead of thesource cells L1 configuration,maintaining L2 entity continuity during the switch.When thesource and target L2 entities a

229、re in different physical nodes,the UE can generate a new set of L2entities connected to the target network L2 entity,simultaneously maintaining both source andtarget L2 entities.The source L2 entity is released only after all pending data in the source L2entity has been transmitted,completing the ha

230、ndover process.Due to synchronization with candidate target cells and completion of beam qualitymeasurements in the handover preparation phase,the required time during the handover executionprocess is extremely short,similar to intra-cell beam handover in 5G,achieving a consistentseamless handover e

231、xperience for UE within and between cells.Failure recovery:Handover failures can significantly impact user experience.In user-centric mobilitymechanisms,candidate target cell configurations are pre-configured for the UE.Therefore,in caseof beam or wireless link failures in the source cell,the UE can

232、 autonomously select a suitabletarget cell based on the pre-configured candidate target cell configurations and apply them tohandover to the target cell,reducing potential data interruption time and minimizing data loss.Traditional handoverfailure handling processes are triggeredonly when none of th

233、epre-configured candidate target cells are suitable for access.4.3.4 User-Need-Centric MobilityAs communication technology continues to evolve,and with the increasing support and28/40introduction of critical features,a variety of network access or collaboration options have emergedto be chosen by us

234、ers for the diverse connection needs of users with varying connectioncapabilities.Such diverse connection modes give users greater autonomy in choosing their ownmodes of connection.In terms of mobility,users can make decisions regarding network access and mobility basedon different service requireme

235、nts and the surrounding network environment:Selection of different network access methods:This includes forming an access network architecture with flexible connections betweendifferent network nodes and multiple terminals when different network access methods areintegrated.Thesemethodsmayincludedif

236、ferentcommunicationsystems(RAT),distributed/centralized antennas,different transmission modes(relay or direct connection),satellites,and UAVs,providing users with services that meet various needs and connectivitycapabilities.In such scenarios,the UE needs to have the ability to judge network coverag

237、e,coupled with auxiliary information provided by the network,such as satellite coverageinformation,UE-requested high-frequency cell or TRP access information,to choose theappropriate method of network access.Besides coverage considerations,UEs service requirements,such as terminal backupoperations,n

238、eed to be taken into account.For instance,in industrial scenarios with ultra-highreliability requirements,like smart grid fault detection or remote operation of robotic arms insmart factories,hot backup may be necessary,meaning participating terminals need to stay onlinecontinuously,transmitting the

239、 same data as collaborating terminals.In this scenario,the UE canrequest the network to associate with the collaborating UE so that the network can subsequentlyuse the same resources for group scheduling of these UEs.Mobility decisions based on user requirements:With the expansion of AI computing ca

240、pabilities,UE can combine its own servicerequirements and predictions to assist base stations or make independent decisions on whether toinitiate cell reselection or handover.UE can autonomously determine the target cell,frequency,and beam change information by predicting the mobile trajectory and b

241、eam information,reducingmeasurements to achieve energy efficiency.It can also report relevant predictive information toassist base stations in configuring appropriate measurement targets,cell bias parameters,eventreporting parameters,and candidate cells for CHO.Simultaneously,considering user servic

242、e requirements,such as during a handover,especiallyin CHO,combining the service or functional support of the target cell is essential for selectingbetter relevant cells.4.4 Flexible and Efficient User Plane Transmission Technologies4.4.1 Flexible Protocol StackThe current wireless communication prot

243、ocol stack follows a layered architecture,whereeach layer contains fixed functionalities with a fixed execution sequence.This rigid and tightlycoupled protocol stack greatly limits the capabilities of 6G networks.To overcome the constraints29/40of this rigid architecture and adapt to the development

244、 of 6G,a stack-free user plane design isproposed,breaking the limitations imposed by the protocol stack layers.The stack-free design andits key technologies ensure the ability of the 6G user plane to adapt to the complex and dynamicscenarios and service requirements of the future.1)Functional compon

245、entizationBy componentizing the user plane functions,the original fixed function execution order ofthe protocol stack is broken,and the function component order can be changed,components canbe switched on or off,or added/deleted,to customize the site according to personalized needs.Atthe same time,t

246、he user plane functional componentization extracts common components andcommon processes to reduce the protocol complexity.In the new user plane architecture,independent components are aggregated to form a functional component library,which not onlysupports functional decoupling,but also makes it ea

247、sy to introduce new components and replaceand upgrade components.By configuring,orchestrating and managing the components in thecomponent library,the user plane can adaptively construct data transmission chains according tovarious personalized needs.Functional componentization provides the foundatio

248、n for user planefunction customization and flexible orchestration,and allows for real-time dynamic control offield-level orchestration and component switching.2)Single-domain and multi-domain orchestrationWith all components co-deployed,orchestrated,and processed in parallel for a singlenetwork pack

249、et,single-domain/single-hop scenarios such as MEC and CU-DU co-location can besupported.Single-domain orchestration not only reduces latency and improves throughput,butalso provides cross-component computing resource scheduling and overall QoS assurance.Thestack-free user plane supports cross-domain

250、/multi-hop deployment,which is highly adaptable tomulti-level deployment scenarios,multiple connections,and MESH networking.By deployingcomponents on demand,more functional split modes are added besides CU/DU separation,whichincreases deployment flexibility.For example,for space-air-ground NTN/satel

251、lite networks,somenon-real-time components can be placed in the sky and some real-time components can be placedlocally;for industrial application scenarios,components can be opened or closed according toservice needs.Public components can be used to connect two different domains,such as the corenetw

252、ork and the access network.3)Component intelligence and deep collaborationThrough intelligent configuration,orchestration,and management of user plane components,the user plane architecture can also incorporate big data andAI algorithm engines to improve theintelligence level of the user plane.For e

253、xample,AI model training can be conducted forcomponents to improve their processing capability;intelligent policy analysis can be performedfor components to make policy recommendations;and intelligent QoS control can be implementedfor components to achieve finer and more accurate data transmission q

254、uality assurance.In addition,by deeply collaborating different components,the collaboration,robustness,flexibility,andscalability of the components can be improved.For example,when the previous componentprocesses a network packet,the next component will prepare the cache and reserve resources inadva

255、nce;the components will be tightly orchestrated and coordinated to achieve one-time readingand batch processing of the data cache.This component pre-processing method can deeplycustomize and finely control the data transmission latency,thereby further improving the dataprocessing efficiency.30/404.4

256、.2 Coordinated Scheduling and Continuous TransmissionUCAN,based on the dynamic organization of network nodes in flexible cells,aims tomaintain user plane continuity while ensuring fast acquisition of upper-layer packet data andguaranteeing zero interruption latency and high transmission rate during

257、user mobility.The rapidacquisition of upper-layer packet data can be achieved through the combination of access networkuser plane localization and core network user plane localization.Zero interruption andtransmission rate assurance are accomplished through flexible organization of TRPs,coordinating

258、the scheduling and transmission of TRP groups.To facilitate UE mobility between TRPs simplywithout complex operations such as handover,the network keeps UE at the center of the cell byenabling coordinated transmission across multiple TRPs.During Inter-DDU situation,a G1interface is established for d

259、ata forwarding and real-time schedule,assisting DDU in achievinglayered multidimensional information collaboration.This involves information collaborationbased on different protocol layers,various dimensions(PRB scheduling,interference information,data information,etc.),and cooperative scheduling ba

260、sed on this information.The physical layercan utilize any resources and transmission mechanisms within the flexible cell,converting moreinterference signals into useful resources to enhance resource utilization efficiency.Additionally,research on novel scheduling algorithms tailored for flexible cel

261、ls is required.User-centric scheduling algorithms need to consider resource collaboration among multiplenetwork nodes,effectively satisfying individual terminals by multiple network nodes,andachieving efficient scheduling from multiple points to multiple terminals.Balancing therequirements and compl

262、exities of scheduling algorithms in the aspects of multi-node resourcescheduling,interference under multiple node transmission,and the balance between overhead andgain becomes challenging.4.5User-Centric Resource OrchestrationThrough the fusion of multiple frequency bands and multiple spatial domain

263、s,user-centricnetwork resource orchestration and dynamic scheduling are realized.The contents include theorchestration of high-and low-frequency resources,the orchestration of uplink and downlinkrelationships,and the flexible combination and deployment of different carrier frequency bands.Furthermor

264、e,cross-layer resource orchestration is formed between resource layers and betweenresource layers and service layers.Different services can flexibly select different resources 7.4.5.1 Key Technologies in Frequency DomainSpectrum resources are the most basic and important resources of radio access ne

265、tworks.From 1G to the current 5G,spectrum resources are being continuously developed and used.Thephysical characteristics of different frequency bands are also becoming increasingly distinct as thetransition from the sub-1GHz band to the 6GHz and above frequency band,with higher frequencypoints and

266、wider carrier bandwidth.From a service perspective,mobile communication needs to cope with an increasing variety31/40of service types.Moreover,the demands of services for performance metrics such as throughput,latency,and reliability,are also becoming more extensive and diversified.Radio access netw

267、orksthat rely solely on the spectrum resources of one or two frequency bands may no longer be able tomeet the performance requirements of emerging services.Therefore,in many cases,radio accessnetworks need to integrate and utilize multi-frequency bands or even the entire frequency bandresources to a

268、chieve higher and more diversified performance.These spectrum resources mayhave different characteristics,such as different frequencies,bandwidths,and subcarrier spacing.How to use these characteristics well to a certain extent determines the ability of radio accessnetworks to adapt to service.There

269、fore,how to efficiently use full-spectrum resources has become a problem that mobilecommunications attaches great importance to and needs to be studied seriously,including:how toefficiently use refarmed spectrum resources,how to efficiently use newly added spectrumresources and how to efficiently us

270、e full frequency band spectrum resources.1)Carrier aggregationIn the carrier aggregation scheme,a cell includes baseband carriers,radio frequency carriers,and the mapping relationship between baseband and radio frequency carriers.In a multi-carrierscenario,one baseband carrier in the cell maps to mu

271、ltiple radio frequency carriers.Theconfiguration,scheduling,and resource allocation of physical channels/signals in the cell arebased on baseband carriers.For energy-saving considerations,the carrier aggregation schemeintroduces mechanisms for activating/deactivating radio frequency carriers,activat

272、ing/deactivatingbaseband carriers,and activating/deactivating the mapping relationship between radio frequencycarriers and baseband carriers.Unlike existing mechanisms for carrier activation/deactivation,when a radio frequency carrier is activated,the corresponding mapping relationship is notnecessa

273、rily activated and depends on whether the mapping relationship between this radiofrequency carrier and baseband carrier is activated.However,when a radio frequency carrier isdeactivated,thecorrespondingmappingrelationshipisalsodeactivated.Similarly,theactivation/deactivation mechanism of baseband ca

274、rriers is similar to that of radio frequencycarriers.In addition to radio frequency carriers and baseband carriers,the mapping relationshipbetween radio frequency carriers and baseband carriers can also be activated and deactivated.Initially,the base station configures the mapping relationship betwe

275、en radio frequency carriers andbaseband carriers by signaling to the UE.When this mapping relationship is activated,the UE andthe base station use it.Conversely,when this mapping relationship is deactivated,the UE and thebase station cease to use it.2)Uplink-downlink decouplingIn the uplink-downlink

276、 decoupling scheme,a cell includes an uplink resource set and adownlink resource set.The uplink resource set consists of multiple uplink carriers,each with itsuplink physical resources,including uplink physical channels and uplink reference signals.Similarly,the downlink resource set consists of mul

277、tiple downlink carriers,each with its downlinkphysical resources,including downlink physical channels and downlink reference signals.Thecore of the scheme lies in the decoupling between the uplink resource set and the downlinkresource set,manifested in several aspects:There is no frequency band rest

278、riction between uplink carriers in the uplink resource set anddownlink carriers in the downlink resource set.Uplink carriers and downlink carriers can be in thesame frequency band or different frequency bands.32/40There is no restriction on the number of uplink carriers and downlink carriers between

279、 theuplink resource set and the downlink resource set.The number of uplink carriers can be greaterthan,less than,or equal to the number of downlink carriers.There is no restriction on the scheduling and feedback relationship between uplink carriersand downlink carriers.Any downlink carrier can sched

280、ule any one or more uplink carriers,andany uplink carrier can provide feedback information to any one or more downlink carriers.Feedback information includes but is not limited to Hybrid Automatic Repeat reQuest(HARQ)ACK/NACK information and feedback information in AM mode.4.5.2 Spacial Domain Relat

281、ed TechnologiesThe main future solutions in the spacial domain dimension include Multi-TRP and TRPdecoupling for uplink and downlink.Multi-TRP can effectively solve the problems of throughput limitation,user capacitylimitation,and frequent cell handover caused by the increase of TRP density.Specific

282、ally,multipleTRPs collaborate to provide uplink and downlink transmission services for users within thecoverage,thus converting interference into useful signals.On the other hand,L1 beam switchingis used instead of cell handover to achieve mobility management.To balance capacity and coverage,a netwo

283、rk architecture utilizing uplink-downlinkdecoupling TRP is employed for data transmission between UE and the network.This means thatthe uplink and downlink transmissions are handled by different TRPs,ensuring both downlinkcapacity and uplink coverage.This ensures both downlink capacity and uplink co

284、verage.Taking the example of a typical commercial indoor window-edge scenario,UE near indoorwindows can receive signals from both outdoor macro TRP and indoor TRP.However,due toconstraints such as limited uplink power and penetration loss,uplink transmission from UE tooutdoor macro TRP is restricted

285、,resulting in lower uplink signal intensity at the receiving end andaffecting demodulation.Conversely,the uplink signals sent by UE to outdoor macro TRP mayinterfere with the uplink reception of indoor TRP.To address such situations,an uplink-downlink decoupling TRP network architecture isemployed.I

286、n this scheme,UE can perform downlink transmission based on outdoor macro TRPand uplink transmission based on indoor TRP.UE can benefit from the high downlink capacityprovided by outdoor macro TRP while ensuring uplink coverage through indoor TRP.Compared with traditional network nodes,in the TRP ne

287、tworking scheme with uplink anddownlink decoupling,the uplink and downlink of a cell can correspond to different TRPrespectively.This networking scheme can realize flexible deployment of uplink and downlink TRP,customize link coverage on demand,and adapt to extreme scenarios.Therefore,the TRPnetwork

288、ing scheme with uplink and downlink decoupling has a wide range of applications,including but not limited to the above indoor window scene,and far beyond that.Furthermore,when the uplink and downlink no longer rely on a single TRP,but a TRP set orTRP cluster,the TRP networking scheme with uplink and

289、 downlink decoupling will be strongerand have a wider range of applications.For example,collaboration within the TRP set can be usedfor interference coordination and mobility management.33/404.5.3 Physical Channel OrchestrationBefore a user equipment can transmit data with the network,it must connec

290、t to the networkthrough the initial access process.The initial access procedure includes cell search,systeminformation reception,and random access.Cell search is the procedure by which a user equipmentuses the primary synchronization signal(PSS)and secondary synchronization signal(SSS)of thecell to

291、perform downlink time and frequency synchronization,and to obtain the physical cellidentity.After completing synchronization through cell search,the user equipment receives anddecodes the system information to obtain the system information necessary for subsequent randomaccess.Afterobtainingthesyste

292、minformation,theuserequipmentcompletesuplinksynchronization through random access,and enters the RRC connected state from the RRC_IDLEstate or RRC_INACTIVE state,preparing for uplink and downlink data transmission.As can be seen from the above communication channel establishment procedure,thecommuni

293、cationprocedureofthemobilecommunicationsystemmustfirstestablishacommunication channel through signaling before the user equipment can transmit data to and fromthe outside world.Taking the downlink data of the user equipment as an example,after the serviceis initiated,the signaling interaction proces

294、s is as follows:First,the paging process is used to helpthe network page the user equipment that is currently in the RRC_IDLE state or RRC_INACTIVEstate.Assuming that the user equipment is in the RRC_IDLE state,the core network will transmitthe paging message to the user equipment.Secondly,upon rece

295、iving the paging message,the NASlayer of the user equipment triggers a service request.Simultaneously,the upper layer of the userequipment triggers the MAC layer to initiate a random access request and sends the random accessrequest through the physical layer.Through the RRC connection establishment

296、 request,RRCconnection establishment and RRC connection establishment completion procedure,the corenetwork establishes an RRC connections.Subsequently,with the established downlink and uplinkchannels between the core network and the user equipment,the user plane tunnel is ready totransmit and receiv

297、e network packets.The aforementioned data transmission method may not be suitable for all services.To meetthe diverse needs of users facing different services at different times,the physical channel setscorresponding to users can vary.In scenarios with high user density and sporadic small servicepac

298、kets,energy-efficient orchestration,utilizing synchronization signals and lightweight datathrough SSB,avoids the need for receiving system information,connection establishment,andPDCCH reception.In scenarios with high user density and periodic service packets,cost-savingorchestration enables the dec

299、oupling of system information,control information,and servicechannels,with centralized transmission of system and control information.In routine servicescenarios,conventional orchestration involves terminal reception of synchronization messages andsystem information,completing the connection establi

300、shment,and using PDCCH and PDSCH forcontrol information and data reception.4.5.4 Transmission Channel VirtualizationIn addressing challenges presented by network packets,such as XR,where a large number ofpackets package multiple Code Blocks(CBs)into a Transport Block(TB),and any error in a CB34/40co

301、uld result in the entire TB being undeliverable,leading to significant delays.The cell supportsthe decoupling of transmission channels into physical channels and the pooling of transmissionchannels,from which a transmission channel virtualization scheme is derived.The transmission channel virtualiza

302、tion scheme splits the original one data flow,onetransmission channel,and one TB into multiple data subflows,multiple transmission channels,and multiple TBs.In this way,even if any TB fails at the receiving end,it will not affect thesubmission of other TBs.To efficiently schedule the above multiple

303、TBs,the transmission channel virtualizationscheme also introduces the concept of TB Group(TBG).TBG contains multiple TBs,which canreuse the same scheduling signal,or in other words,one DCI schedules all TBs in TBG.Inaddition,the cell can choose to map the TBs in TBG in the frequency domain or in the

304、 timedomain according to the delay requirements and spectrum interference conditions.It can also mapin the frequency-time domain first in the frequency domain and then in the time domain,or first inthe time domain and then in the frequency domain.4.6 Distributed Multi-Antenna TechnologiesThe volume,

305、weight,and windward area of 6G antenna systems will increase.Consideringthe limitations of site resources,the distributed deployment method of disassembling anddispersing massive MIMO systems to various sites can provide another implementation path forthe expansion of the equivalent antenna array sc

306、ale.Through the distributed deployment ofmassive MIMO systems,not only can the effective antenna array size be significantly expanded,but it can also increase the angular expansion of signals,reducing the correlation of the equivalentMIMO channel.This results in higher spatial degrees of freedom and

307、 increased channel capacity.Leveragingadvancedsignalcooperationprocessingsolutions,multiplenodesdispersedgeographically can form signal patterns with better spatial aggregation effects.This accuratelyshapes high-quality network coverage at user locations,significantly enhancing spectral efficiency.W

308、ith an increasing number of distributed nodes,signal propagation distances shorten,enabling thesystem to maintain information transmission quality with lower transmit power,leading to higherenergy efficiency.Additionally,as the frequency band increases,factors such as user mobility andobstruction ca

309、n cause a drastic deterioration in link quality.The distributed deployment of massiveMIMO systems utilizes spatial redundancy through multi-site cooperation,improving thereliability of transmission and ensuring stable and balanced user experiences at differentgeographical locations.In a user-centric

310、 system architecture,the network coverage in a region is no longer staticallydetermined by pre-planned cells,and the wireless transmission of each user is not bound to aspecific network transmission point and cell,but is planned and dynamically generated for users,so that the network capacity matche

311、s the needs of users or applications in a specific space andtime.The network selects a set of appropriate transmission points based on the users servicerequirements and the environment to form network coverage for the user,and the varioustransmission points in the region jointly provide services for

312、 the user.Under this new system architecture,distributed multi-antenna technology can provide a solidair interface transmission foundation for user-centric access networks,and the user-centric system35/40architecture can also create important network structure support for the performance advantages

313、ofdistributed massive MIMO technology:With the widespread distributed deployment of numerous transmission points,antennas arepositioned near users,ensuring a sufficient number of antennas and transmission points aroundany user.Through collaborative transmission/reception between these points,a dynam

314、ic networkcoverage is formed around the user,keeping the user at the center of the network coverage at alltimes.This significantly enhances transmission efficiency and user experience,effectivelysupporting a user-centric system architecture.In a user-centric system architecture,distributed multi-ant

315、enna systems gain greaterflexibility in collaborative cluster selection,resource allocation,and user scheduling.Thisflexibility allows breaking through the limitations of single-point or static collaboration clusters.With a more extensive spatial domain,a broader spectrum,and a larger potential user

316、 schedulingset,a more global approach is employed to obtain more comprehensive channel and interferenceinformation,showcasing the performance gains of collaborative scheduling and cooperativetransmission/reception for multiple sites and users.4.7 Terminal Key Technologies4.7.1 Enhancement of User Ri

317、ghtsThe user-centric rights system encompasses the following key aspects:The right of participating in network planningA super terminal or special network element,following negotiation and authorization withthe operator,can serve as a legitimate service or relay node.It takes on functions like centr

318、alizeddata forwarding,resource coordination,and interference control.Based on actual contributions tonetwork planning,reductions in service latency,spectrum utilization efficiency,interferencesuppression,and other metrics,it receives corresponding value feedback or rewards.The right of service contr

319、olFollowing negotiation and authorization with the operator,a super terminal or specialnetwork element can actively request and specify its desired resource policies and RRCconfigurations for specific service scenarios.For instance,it can provide resource demandquantities and QoS parameter configura

320、tions.Through the Rights Allocation Change Process,itcommits to paying transaction costs and bearing the consequences for such actions.The right of the ownership of digital assetsAfter negotiation and authorization with the operator,a super terminal UE or special networkelement can,based on internal

321、 computing capabilities,perform intelligent model training andinference,or possess sensing capabilities.It uploads or processes preliminary sensing content forthe base station,creating digital assets(e.g.,datasets,AI model algorithms,sensing data)specific to its device.Based on actual contributions

322、in terms of computing power,storage,sensing,and intelligence,it receives corresponding value feedback or rewards.36/404.8 User-Centric Convergence Technologies4.8.1 NativeAIO-RAN,an organization with the goal of openness,intelligence,virtualization,and fullinteroperability,has an intelligent network

323、 architecture comprising two core parts:theNon-Real-Time RAN Intelligent Controller(Non-RT RIC)and the Near-Real-Time RANIntelligent Controller(Near-RT RIC).O-RAN completes both Non-RT RIC and Near-RT RIC,working together to actively optimize and adjust network load balancing,mobility management,mul

324、ti-connection control,QoS management,and energy-efficient networking based on AI 8.O-RAN realizes embedded AI in radio networks based on existing 3GPP network interfaces,and has good compatibility with 3GPP networks.For 6G UCAN in the future,a furtherreconfiguration of inter-layer relationships and

325、functions within the radio access network isrequired to achieve native AI.The native AI in 6G networks involves internally conductingAI-related tasks such as data collection,pre-processing,model training,model inference,modelevaluation,and deeply integrating AI requirements(computing power,data,algo

326、rithms,connections)with 6G network functions,protocols,and processes.In the native AI UCAN,intelligence is embedded as a native feature,acting as a hub thattraverses both the control plane and the user plane,connecting the radio access network into anatively intelligent whole.As described in 3.2.1,t

327、he intelligent plane comprises intelligent entitiesat different hierarchies,launching and operating corresponding AI modules and processes basedon different functional requirements,AI algorithms,and models.The intelligent plane possessesfunctions such as environmental and service awareness,intellige

328、nt management,control,computation,and coordination specifically tailored for the control plane and user plane functionwithin the radio access network architecture 9.Perceive and acquire spectrum information in the user-centric area,combining the actualwireless frequency usage in adjacent regions,to

329、achieve dynamic spectrum sharingcontrol for network access points,thereby enhancing system spectral efficiency.Enable dynamic interference management,effectively addressing persistent challenges inwireless communication networks related to frequency resource planning andmanagement.Implement network

330、resource usage control based on service flow predictions,achievingmore efficient energy utilization in the network.Intelligently organize and orchestrate various network functions as needed for theuser-centric radio access network,facilitating the autonomous evolution of networkarchitecture.Data col

331、lection,a critical factor affecting the effectiveness ofAI model training and inference,requires careful framework and process design.The intelligent plane can perform data collectionthrough traditional control planes and user planes or utilize new data functionalities introduced in6G(such as data c

332、ollection frameworks or data planes)for required data collection and processing.However,further research and comparison are needed for these two solutions,considering theevolution of access network architecture,especially whether 6G access networks willsimultaneously introduce independent intelligen

333、t planes and data planes.Regardless of the final37/40form of integration of intelligence and data into the network,as relatively independent yet closelyrelated functional services,they will undoubtedly be the most crucial components of 6G UCAN.Chapter 5 SummaryFor a long time,user-centric network has been a research focus in the field of mobilecommunications,receiving widespread attention from aca