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1、6G Lean RAN White Paper（2022）China Mobile Research InstitutePrefaceThis white paper aims to put forward the driving force analysis,architecture design,key technologies and challenges by China Mobile for6G lean radio access network.We hope that it can provide reference andguidance for the design sche

2、me of 6G access network architecture andprotocol stack function in the industry.The copyright of this white paper belongs to China Mobile.Withoutauthorization,no institution or individual may copy part or all of thecontents of this white paper.China Mobile6G Lean RAN White Paper（2022）Contents1 Backg

3、round.12 The driving force of 6G lean radio access network.42.1 From build before use to deploy on demand.42.2 From high energy consumption to green network.52.3 From three scenarios to more diversified scenarios.52.4 From flat network to cube network.62.5 From expert experience to high-level networ

4、k autonomy.73 Lean radio access network architecture.94 Key technologies of 6G lean RAN.124.1 Signaling and data decoupling.134.1.1 On demand deployment.144.1.2 Data cell assisted access.154.1.3 Data link establishment and handover.154.2 Lean network functions.164.2.1 Closed-loop QoS management.164.

5、2.2 Intelligent resource control.184.2.3 Flexible link adaptation,ensuring ultimate user experience.194.3 Management and orchestration.215 Future outlook.23References.26List of abbreviations.27China Mobile6G Lean RAN White Paper（2022）11BackgroundWith the rapid expansion of the network scale and the

6、increase of the servicerequirements,the network architecture is becoming more and more complex.Cost andpower consumption are potential problems that need to be solved.In order to solvethese problems,the design of 6th Generation Mobile Networks(6G)will movetowards a simple way and adopt a lightweight

7、 network architecture.We hope that thefuture network will be as concise as possible，support plug-and-play and dynamicswitching,so as to save power consumption and cost.In this white paper,the drivingforce,architecture and key technologies of 6G lean access network are researched andanalyzed.On the o

8、ne hand,the driving force of 6G lean radio access network comes fromthe potential problems of the existing network,on the other hand,it needs to solve thenew requirements and new scenarios introduced with the development.The cost andenergy consumption of radio network are the bottleneck problems of

9、radio networkconstruction.These problems have begun to appear in the 5th Generation MobileNetworks(5G),and they will become more and more prominent for 6G.In 6G,flexible and dynamic networks should be considered and plug-and-play enablingtechnologies should be explored.Signaling and data decoupling

10、is studied as apotentialtechnology.Wideareasignalingcoverageiscarriedoutthroughlow-frequency signaling cells to ensure the reliability of the control plane,such asreliable mobility management and fast service access;On the other hand,dynamicdata cells loading are adopted to improve the data transmis

11、sion capacity of thenetwork and reduce the interference between cells.In terms of new networkapplication scenarios,with ubiquitous network connections,integration of ground,airand space and the introduction of differentiated new application scenarios,using theexisting protocol architecture will inev

12、itably lead to increased complexity.Lean radioaccess network realizes the unified access of a variety of air interface technologies byadopting a unified wireless protocol architecture,functional design and processChina Mobile6G Lean RAN White Paper（2022）2framework,so as to simplify the network 1.The

13、 digitization and intellectualizationof social development have derived a series of new service requirements,such asholographic communication,synaesthesia interconnection,smart medicine,smartfactory,etc.The definition of service requirements has also expanded from threedimensions of delay,bandwidth

14、and number of connections to multiple dimensions2.Traditional connection-oriented communication methods and design ideas basedon data transmission and processing may not cover all the requirements of 6G.Withthe help of data technology,operation technology,information and communicationtechnologies(DO

15、ICT)andothernewmeans,thenetworkcanrealize thesimplification of protocol design,efficient data transmission,robust signaling control,on-demand network function deployment and accurate network services through theenhancement of functions,so as to achieve the effect of strong ability and simplestructur

16、e.The plug-and-play network construction mode enables the number of cells toincrease dynamically according to the development of the services.In hot spot areas,more data cells can be switched on to provide users with better services.In areas withlow service requirements,some data cells can be switch

17、ed off to save the networkenergy consumption,which can directly reduce network construction costs,networkenergy consumption and redundancy,thereby realizing cost and energy savings.Figure 1 shows a schematic diagram of the lean network.Through the accuratecontrol of access points in the cloud combin

18、ed with link management,the functionssuch as self-discovery and self-adding of access points are realized to achieve theflexible expansion of network coverage and the plug and play of nodes 3.China Mobile6G Lean RAN White Paper（2022）3Figure 1.Schematic diagram of the lean networkChina Mobile6G Lean

19、RAN White Paper（2022）42The driving force of 6G lean radio access network2.1 From build before use to deploy on demandA high-quality communication network is an important basic guarantee for thedevelopment and prosperity of new applications.According to past experience,advanced construction provides

20、an important platform support for applicationinnovation.The network construction adopts the principle of width coverage first andthen depth coverage to continuously improve user experience.As of August 2021,China has built more than one million 5G base stations,accounting for more than70%of the worl

21、ds total 5G base stations.The 5G network has covered allprefecture-level cities across the country,as well as more than 95%of county-levelurban areas and 35%of town areas.The number of 5G users have exceeded 539million.With the rapid expansion of network scale and the increase of servicerequirements

22、,continuing the current network architecture method will lead to higherand higher network costs.As the frequency band becomes higher,the construction ofbase stations will be more intensive under the same network performance and networkquality requirements.Considering that the available frequency ban

23、ds are gettinghigher and higher,if the 6G network continues to follow the current architecture,alarge number of base stations need to be deployed densely to meet the requirements ofcoverage and throughput,which directly leads to further increase in the cost of 6Gnetwork.How to save network costs thr

24、ough technical methods such as architecturedesign without the user experience deterioration is an issue that needs to beconsidered in the early stage of 6G network construction.Lean network architectureand on-demand flexible network deployment are considered as potential approachesfor 6G network dep

25、loyment.Wide-area coverage is achieved through low frequencybands,and hot spot coverage is flexibly and dynamically added on demand.Theplug-and-play method is adopted to ensure the flexible expansion of the network ondemand,so as to realize the network performance according the requirements.China Mo

26、bile6G Lean RAN White Paper（2022）52.2 From high energy consumption to green networkWith the development of technology,the single-bit energy consumption of 5G isone-fifth of that of 4G.Because of the large bit rate and high throughput of 5G basestations,the power consumption of a single station is fo

27、ur times that of 4G.Nowadays,the energy consumption of 5G has received extensive attention in the industry.According to statistics,by 2023,the power consumption of 5G base stations isexpected to account for 1.3%of the electricity consumption of the society.By 2026,the power consumption of 5G base st

28、ations will rise to 2.1%of the electricityconsumption of the whole society.According to the existing network developmenttrend,the complexity of 6G network will increase exponentially.The existing networkhas a single form,the base station has all functions,and the resources of the networkare unbalanc

29、ed,which may further increase the energy consumption.In order torealize a green network,reducing energy consumption is an important issue that mustbe considered and solved in the 6G era.Through the decoupling of signaling functionsand data functions,signaling cells are deployed at low frequencies to

30、 achievewide-area coverage,and dynamically enabled data cell functions can be customizedon demand to reduce network energy consumption.In this way,the networkutilization rate is improved,and energy saving is realized.2.3 From three scenarios to more diversified scenariosThe driving force of network

31、development is the continuous improvement ofhuman well-being.The digitization and intelligence of social development havegenerated a series of new service requirements.By 2030,more applications willemerge to support the digitization of the entire world,such as holographiccommunication,communication

32、and perception interconnection,smart medicaltreatment,and smart factories.Typical application scenarios will also change fromthree major scenarios to more fragmented application scenarios.As shown in Figure2,the definition of 6G service requirements will also introduce new indicators,suchChina Mobil

33、e6G Lean RAN White Paper（2022）6as AI capabilities and perceptual computing capabilities.Service metrics will expandfrom single-point performance requirements to more diverse extreme performancerequirements.6G network should have enough flexibility and expansivity to supportvarious unforeseen new dem

34、ands emerging with the rapid development of society.Figure 2.Key performance indicators of 6G scenario 42.4 From flat network to cube networkFrom the ubiquitous connection needs of human beings,it can be seen that thefuture mobile communication technology is also moving towards full coverage of thes

35、ea,space,air and ground,enabling a wider range of collaborative controlconnections in the network.From the perspective of social development trend,thenetwork from 4G to 5G has become more and more extreme,and its coverage hasbecome wider and wider.However,the coverage rate in some specific areas is

36、stilllow.For example,in order to better meet the needs of environmental monitoring,fieldrescue,and ocean exploration,the communication network must have the ability toChina Mobile6G Lean RAN White Paper（2022）7connect beyond the land and across the ocean,and is distributed in sparsely populatedunmann

37、ed or semi-unmanned areas.It can be seen that the air-space-groundintegrated wireless network is also a part of the lean radio access network.Theair-space-ground integrated network integrates the terrestrial network and thenon-terrestrial network by using a variety of technical means to provide user

38、s withbetter quality of service.The non-terrestrial network composed of near-earth satellitesand various aircraft can provide three-dimensional network coverage for remote areas(such as oceans,mountains,etc.),which is conducive to helping the ground networkto achieve ubiquitous coverage in the whole

39、 area.The ground mobile networkprovides basic big data storage and processing capabilities,and can provide highertransmission efficiency.The two complement each other and can realize thetransformation from flat network to cube network.2.5 From expert experience to high-level network autonomyAs of th

40、e end of June 2021,China Mobile has operated 5.28 million base stations,ranking first in the world in total.The large scale of base stations,multi-modecoexistence,large amount of network parameters,and diverse scenarios all putforward high requirements for network operation and maintenance.Facing mo

41、redimensions scenarios,more service types,and more parameter configurations in 6G,the network operation and maintenance methods will move towards a high level ofnetwork autonomy.Virtualization and service based infrastructure provide the basisfor flexible resource allocation at the resource layer,on

42、-demand generation ofnetwork layer functions,and flexible network orchestration,which also aggravates thedifficulty of network management.Orchestration and management are a crucial partof ensuring diverse service experience for users.Efficient orchestration managementcan match resources at the resou

43、rce layer(including radio resources,computingresources,storage resources,deployment space resources,etc.)with networkfunctions to maximize usage efficiency.As network functions become more flexible,the original manual operation and maintenance methods have higher requirements forChina Mobile6G Lean

44、RAN White Paper（2022）8operation and maintenance personnel.The management of the access network domainand the configuration of wireless parameters will become more and more complicatedwith the flexibility of network functions.Access network domain managementthroughexpertexperiencewillbecomeabottlenec

45、kinnetworkoperation,maintenance and management.The 6G lean radio access network also needs toexplore high-level network autonomous operation and maintenance methods based onartificial intelligence(AI)and digital twins for self-optimization,self-evolution,andself-growth to solve potential network eff

46、iciency,cost,and user experience issues.China Mobile6G Lean RAN White Paper（2022）93Lean radio access network architectureIn order to realize cost and energy consumption reduction in the future networkand raise the adaptation capability for new scenarios and demands,6G radio accessnetwork needs to ma

47、ke breakthroughs in architecture design and explore new flexiblearchitecture to adapt to future changing demands.Control plane and user plane decouplingThe requirements of the control plane are different from that of the user plane.The requirements of the control plane include satisfying as many use

48、rs as possible,improving user density and user mobility performance,reducing the handoverfrequency and improving reliability.The requirements of the user plane include higherpeak rate,user experience rate,and traffic density.The traditional base station hasfixed functions,and the use of ultra-dense

49、network to improve the performance ofuser side usually brings about switching,load balancing and interference problems.The 6G lean radio access network realizes wide-area coverage through low-frequencysignaling cell,and on-demand data transmission through medium-high frequency datacell.Combined with

50、 the perception of service demand,the data cell can be turned onor off on demand to realize the reduction of network power consumption.Service based architectureIn the service-based architecture,the functions of base stations can be flexiblymatched.Considering the flexible expansion of the network,c

51、omplete networkfunctions can be provided by reconstructing service functions and the combination ofmultiple services to flexibly support different service scenarios and requirements.Emerging services have obvious personalized requirements,and the network needs tobe able to flexibly adapt to service

52、requirements.Network function design needs toexplore a network function service definition with low cost,good real-timeperformance and adaptability to various business requirements.Through the servicebased architecture,network functions can be customized on demand,resources can beChina Mobile6G Lean

53、 RAN White Paper（2022）10configured on demand,and functions can be dynamically generated,providingarchitectural support for the lean radio access network.Aunified architecture supporting multiple air interface technologiesConsidering differentiated application scenarios such as ground,sea and air,6Gr

54、adio access network will be carried out in accordance with the unified architecturedesign.Through the radio access network supporting the integration of differentaccess systems,the unified access of multi-network including the ground,underwater,satellite is realized.Through the unified control of ai

55、r interface,terminals can accessthe network indiscriminately,thus reducing the complexity of accessing networks.Plug and playWith the booming development of emerging services,the demand for networkcontinues to increase.In some areas with unexpected services,plug and play provideson-demand network co

56、verage,thereby reducing the cost of the network from theperspective of network architecture.To support the above features,wireless network functions can be dividedaccording the dependence of air interface technology:Table 1.Network function and the dependence of air interface technologyDependencyNet

57、work functionClosely relatedPHY，Scheduling and resource allocation in MACRelatedRRCRelatively independentPDUprocessing,i.e.encryptionanddecryption,integrity protection and reordering,and so onAccording to the characteristics of different network functions,networkfunctions can be divided into four pa

58、rts:radio resource control,high-layer packetprocessing,air interface adaptation and physical layer processing.The lean radioaccess network architecture adopts the form of cloud-edge-end collaboration.Itdynamically allocates radio,computing,and storage resources on demand andgenerates network functio

59、ns through orchestration and management.High-layerChina Mobile6G Lean RAN White Paper（2022）11packet processing and radio resource control can be deployed in the cloud,and theadvantages of DOICT and intelligent can be fully utilized to analyze the network stateand service model,and the capability of

60、service packet type awareness can be realizedto enable self-optimization of network control.The network selects an appropriatedata transmission link based on the data packet type analysis results and servicerequirements.Through air interface adaptation,the network selects appropriatephysical layer p

61、rocessing according to the requirements of high-layer packetprocessing,and realizes network and service adaptation and the integration andunification of multiple air interface access.Air interface adaptation also includesnetwork management of edge devices.Through self-configuration of edge devices o

62、nthe cloud,edge devices can be plugged and played.By detecting network resourceusage,network status,users and services,and combining artificial intelligence andother technologies,network orchestration management predicts network status andpossible performance deterioration,and updates network orches

63、tration managementpolicies in advance.The possible architecture of lean radio access network is given inFigure 3.On the basis of service based architecture,network functions are generatedand deployed on demand,control plane and user plane are designed separately,andedge devices are self-managed to r

64、ealize the integration and unification of various airinterface access and plug and play.Figure 3.The lean network architectureChina Mobile6G Lean RAN White Paper（2022）124Key technologies of 6G lean RANFrom the perspective of reducing cost and power consumption,and improvingthe adaptability of new se

65、rvices and new scenarios,the 6G lean radio access networkproposes a flexible and scalable access network architecture.At the same time,thelean radio access network also needs a series of key technologies to cooperate withthis architecture to achieve breakthroughs in the form of network construction,

66、meetextreme service requirements flexibly and on demand,realize the three-dimensionalfull coverage of the air,ground and sea,reduce network costs and energyconsumption,and achieve a high level of network autonomy.Signaling and datadecoupling,lean network function design,and network management and or

67、chestrationare the three most important aspects.Under the traditional network deployment,signaling and data are delivered through the same base station,and the functions ofthe base station are unified and undifferentiated.For signaling and data decoupling,the base stations are divided into independe

68、nt signaling base stations and data basestations according to their functions.The signaling base station realizes wide areacoverage,and the data base station realizes on-demand deep coverage,providingtechnical support for reducing network cost and power consumption.In terms of leannetwork functions,

69、the rapid development of intelligence has introduced new ideas forprotocol stack design.We can learn from the experience of intelligence and explorethe impact on standard and protocol function design in the aspects of service qualityreliability,link adaptation,data packet feature mining,and wireless

70、 resource control.In terms of network management and orchestration,the plug-and-play link controltechnology canquickly identify newly added nodes,automaticallyestablishconnections,and dynamically provide service according to service requirements.Thus,the cost,energy consumption and scale redundancy

71、of the network can be effectivelyreduced,and cost and power consumption can be saved.China Mobile6G Lean RAN White Paper（2022）134.1 Signaling and data decouplingThe traditional network topology is relatively static.As the frequency bands usedincreases,the network becomes denser and the cost increase

72、s.Facing the sharpincrease of wireless network cost and energy consumption,the decoupling ofsignaling and data will change the way of network construction,and the network willtransform from high energy consumption to green energy saving.Different from thetraditional CU-DU architecture,which divides

73、network functions horizontally,thearchitecture of signaling base stations and data base stations is divided verticallyaccording to specific functions.The signaling base station is responsible for thesignaling plane function,and the signaling cell performs wide-area signaling coveragethrough low-freq

74、uency to ensure the reliability of the control plane,such as reliablemobility management and fast service access.One signaling base station maycorrespond to multiple signaling cells.The signaling cell focuses on signaling planeprocessing and is the anchor point of the radio resource control(RRC)func

75、tion.Thedata base station performs user plane operations and is responsible for datatransmission.It can quickly upgrade the data processing capability of the network in aplug-and-play manner.A cell responsible for data transmission is called a data cell,and one data base station may correspond to mu

76、ltiple data cells.The data cell focuseson the processing of data.Through the decoupling of data and signaling carried bydifferent frequency bands,wide-area coverage of signaling and deep coverage of dataplane can be achieved,and the number of handovers can be reduced.On the otherhand,the data cell f

77、unction can be generated on demand and dynamically turned onand off.Flexible data base station loading can reduce the energy consumption of thenetwork on the premise of ensuring the network data transmission capability.Thisprovides a new idea for network deployment.The network capabilities can bedyn

78、amically adjusted according to network conditions to match the actual needs.China Mobile6G Lean RAN White Paper（2022）14Figure 4.Schematic diagram of signaling cell and data cell4.1.1On demand deploymentThe tidal effect generally exists in office buildings,schools,residential areas,etc.In different a

79、reas and time periods,the degree of busyness and leisure of the cell isdifferent.The distribution of network data services is also unbalanced,and a largenumber of data services occur in a small number of areas.In order to adapt to thegrowth of services,data cells can be dynamically activated on dema

80、nd to ensure thecoverage of hots pot areas.Through real-time perception of service requirements andnetwork status,more data cells are turned on in hots pot areas to provide betterservices to users,and some data cells are closed in areas with lower servicerequirements to save energy.In the case of de

81、coupling of signaling and data,enablingdata cells on demand not only ensures the availability of connections,but also reducesunnecessary power consumption,realizing flexible matching of networks and services.Starting from the needs of the service,combined with the topological connection ofthe data c

82、ells,a policy of turning on the data cells on demand is generated,so as tofurther reduce the energy consumption on the basis of meeting the needs of users.Inaddition,the data cell function can also be customized according to the scenario,andthe data cell function can be flexibly configured according

83、 to the needs of differenttypes of services,such as flexible configuration of physical layer bandwidth,datapacket processing method,etc.,so as to better match the current service types andChina Mobile6G Lean RAN White Paper（2022）15characteristics.Through the unified arrangement and management of net

84、workcomputing power,radio resources,hardware resources and other shared resources andnetwork functions,the network cost and energy consumption can be further reduced.4.1.2Data cell assisted accessAs the anchor of the signaling plane function,the signaling cell is responsible forthe processing of sig

85、naling plane functions such as user access,RRC connection statemanagement and handover.Users usually access the network through signaling cells,but the access user capacity of signaling cells is limited by physical resources such asaccess resources.In order to further improve the access capacity of

86、the access network,user access assisted by data cell resources is explored.Through the random accessresources configured by the data cell,more users can use the resources in the data cellto perform random access.The data cell forwards the signaling related to randomaccess to the signaling cell,and t

87、he signaling cell performs RRC connection control.Correspondingly,the transmission mechanism of the system information can also befurther lean,for example,the method of acquiring the system information of the datacell on demand.4.1.3Data link establishment and handoverAfter the data cell is loaded,i

88、t needs to establish a handshake with the signalingcell,and sends the configuration of the data cell to the signaling cell at the same time.The signaling cell should save the configuration of the data cells within its coverage.The selection of the serving data cell is an important step that the term

89、inal needs toperform before data transmission.The network needs to formulate a unified data cellselection strategy.For example,as the user moves within the coverage of thesignaling cell,the users signaling plane anchor point does not change,but the datacell that serves the user may change,and the da

90、ta link needs to support adaptivehandover to ensure a consistent user experience.China Mobile6G Lean RAN White Paper（2022）164.2 Lean network functionsThe development of society has derived users higher requirements for latency,reliability,and mobility.Traditional connection oriented communication me

91、thods anddesign ideas based on data transmission and processing may not cover themulti-dimensional requirements derived from the development of society.Therefore,it is necessary to explore the enhanced design of lean network protocol functions.Driven by DOICT and other new technologies,the design id

92、ea of 6G protocol systemwill move towards the combination of simplicity and intelligence.It adopts alightweight network architecture and intelligently adjusts the network capabilityaccording to the network state to match the network capability with the actual demand.The function design of lean netwo

93、rk includes three parts:closed-loop quality ofservice(QoS)management,intelligent resource control and flexible link adaptation.Closed-loop QoS management is oriented to the new requirements of the network.Itflexibly adapts to the service requirements through the closed-loop QoS statusreporting,and f

94、lexibly adjusts the network resource scheduling through the QoS statusperceived by RAN to meet the service requirements.Intelligent resource controlintroduces artificial intelligence to optimize network control methods on the basis oftraditional expert experience,and reduces the complexity of networ

95、k control,andrealizes network self-optimization and self-control.Flexible link adaptation simplifiesthe design of radio link,and realizes the flexible on-demand matching betweenservice requirements and radio links through intelligently analyzing data packetcharacteristics.4.2.1Closed-loop QoS manage

96、ment6G era will be a highly data-driven and intelligent era.New services such asholographic image,extended reality(XR)service,virtual space perception andinteraction have put forward more extreme requirements for the service qualityassurance of 6G networks.The bottleneck of QoS guarantee lies in the

97、 air interfaceChina Mobile6G Lean RAN White Paper（2022）17capability.How to combine the air interface capability with service requirements isthe core issue of wireless side QoS guarantee.With different service characteristics,users have different experiences on whether QoS can be satisfied.For exampl

98、e,forautomatic driving services,once QoS cannot be guaranteed,the user experience willdeteriorate rapidly;for video services,if QoS cannot be guaranteed temporarily,theuser experience will not deteriorate rapidly.In the traditional QoS architecture,the Internet Protocol(IP)packet flow is firstmapped

99、 to the QoS flow,and it is sent to the opposite end through the wireless bearerof the air interface 5.The access network completes the mapping of QoS flow todata radio bearer(DRB),as shown in Figure 5 6.Due to the changes of air interfaceenvironment and network state,the satisfaction of QoS is a dyn

100、amic process.Usually,the base station maps the data packets with similar QoS requirements to the sameradio bearer,and meets the users QoS requirements by scheduling of the data bearer.Figure 5.QoS architectureFor 6G new services,a new QoS mechanism should be designed to guarantee theflexible and ext

101、reme service requirements.Based on end-to-end QoS constraints,closed-loop QoS control realizes on-demand air interface services and efficientnetwork capabilities with relatively limited air interface resources according to theservice experience fed back by the terminal and the real-time air interfac

102、etransmission characteristics.As shown in Figure 6,the network realizes QoS detection,China Mobile6G Lean RAN White Paper（2022）18modeling and adaptive adjustment of bearer services through flexible QoS detectionmechanism combined with artificial intelligence/big data technology.Based on theservice e

103、xperience fed back by the UE,the access network intelligently judges thechange trend of the subsequent service experience,and provides QoS guaranteeintervention in advance.Figure 6.Closed loop architecture combining data characteristics and QoS feedback4.2.2Intelligent resource controlIn order to me

104、et the multi-dimensional needs of users in new 6G scenarios suchas holographic communication,communication and perception interconnection,6Gnetworks require more efficient resource control to ensure the ultimate userexperience.Resource control performs physical resource,data bearer,RRC state,handove

105、r and other related control through RRC configuration.The configuration ofnetwork parameters directly determines the performance of the network.Thetraditional resource control method is based on expert experience.However,with theincrease of service types and the expansion of network scale,the tradit

106、ional resourcecontrolbasedonexpertexperiencepresentstheproblemsofinaccuracy,time-consuming and high cost.In order to solve this problem,the introduction of AItechnology provides effective technical means.Intelligent resource control generatesChina Mobile6G Lean RAN White Paper（2022）19intelligent dec

107、ision-making by collecting physical environment,user status andbusiness-related information,combined with AI and expert experience.Intelligentresource control utilizes the closed-loop mechanism of data collection,training,reasoning,and verification,combined with the performance evaluation system,tof

108、urther extend the previous expert experience control system into a self-optimizingand autonomous intelligent control system.Combined with fault analysis and rootcause location,network intelligent control can discover potential problems in thecontrol process in a timely manner and achieve closed-loop

109、 management and control.Intelligent network control can be used in various scenarios,such as handover,accesscontrol,link control,and energy saving,to endow the network with new capabilitiesthrough intelligent decision-making.Taking handover as an example,intelligentnetwork control can perform intell

110、igent analysis according to user environment,movement trajectory,and service characteristics,and generate suitable handoverstrategies.The network comprehensively determines the handover strategy withreference to the air interface environment and the handover delay and reliabilityrequirements of diff

111、erent services.By monitoring the handover performance,thenetwork continuously optimizes the intelligent handover strategy to realize theself-optimization of the intelligent control strategy.4.2.3Flexible link adaptation,ensuring ultimate user experienceThe diversified services of 6G require more fle

112、xibility of radio links in network.Taking 5G downlink data as an example,as shown in Figure 7,through QoS flow,data packets are mapped to radio bearers,radio link control(RLC)channels,logicalchannels and finally to transmission channels 6.Carrier aggregation and dualconnection respectively implement

113、 one-to-many mapping from logical channels totransmission channels and radio bearers to RLC channels.The network dynamicallyadjusts the configuration of radio bearer,RLC channel and logical channel by RRC orMAC based on terminal service and air interface status.In this data processing,IPpackets for

114、each service are processed by each protocol layer to generate data packetsChina Mobile6G Lean RAN White Paper（2022）20that can be understood by the peer layer,then the peer protocol layer receives the datapackets from the peer layer and sends them to the upper layer for processing.Theresult of this p

115、rocessing method is that the multi-layer processing leads to a largelatency,and the functional redundancy between layers also reduces the processingefficiency.Figure 7.Downlink data mapping diagramFacing 6G,in order to better adapt to service type changes,improve networkflexibility,and avoid frequen

116、t link configuration updates,data links can be dividedinto upper-layer data links and lower-layer data links.Upper-layer data links are closeto services,and lower-layer data links are more related to air interface.Eachlower-layer data link can transmit and receive data from multiple upper-layer data

117、links,and each upper-layer data link can be mapped to multiple lower-layer data links,thus flexible mapping between upper-layer links and lower-layer links can beachieved.The network configures a set of lower-layer links for each user that meet allpossible service QoS requirements.With the help of i

118、ntelligence,the network selectsappropriate lower-layer links from the set based on service QoS characteristic values.China Mobile6G Lean RAN White Paper（2022）21The network allows flexible mapping between upper-layer links and lower-layer linksto dynamically load and delete links.In Figure 8,accordin

119、g to QoS requirements ofservice flows,service characteristics including packet size,service cycle,transmissionrate and latency,as well as the air interface status of the lower-layer links,such as linkcongestion and air interface quality,the network determines the upper-layer links andone or more low

120、er-layer links from the lower-layer links set.Lower-layer links cancarry packets from different users and services with similar QoS requirements andservice characteristics.The network can dynamically update the mapping betweenupper-layer links and lower-layer links to realize link adaptation and lin

121、k selectionbased on the air interface environment and service requirements.Figure 8.Flexible link adaptation4.3 Management and orchestrationIn order to support the three-dimensional full scenario coverage,6G radio accessnetworkneedstohaveabilitiesofplugandplay,self-optimizationandself-growth.6G lean

122、 radio access network requires capabilities of efficientmanagement and orchestration.Network orchestration,which can allocate appropriatecomputing power,storage,wireless and other resources for the network,combinedwith on demand generation of network function,based on artificial intelligence anddigi

123、tal twin,the self-optimization,self-evolution,self-growth of the high-levelnetwork autonomy operation and maintenance method can be realized for solvingChina Mobile6G Lean RAN White Paper（2022）22potential problems of network efficiency,cost and user experience.When newnetwork nodes access the networ

124、k,they can quickly shake hands and plug and play toachieve coverage expansion and on-demand network function deployment,which caneffectively reduce network power consumption and function redundancy and savenetwork costs.Network management of plug and play network nodes is mainlyembodied in three asp

125、ects:access point awareness,access point self-configuration andself-optimization,and cloud-edge collaborative control.Access point awareness refersto the ability to sense access requests of different types of nodes and start appropriatehandshake and control signaling processes.For different types of

126、 access points,it isnecessary to accurately identify and quickly complete access to achieve flexibleexpansion of coverage.The self-optimization and self-configuration of access pointscan automatically complete the configuration and realize self-generation when anaccess point is added to the network.

127、During running period of the access point,parameters can be adjusted and automatically optimized according to real-timescenarios,and services can be improved as needed,so that user requirements can besatisfied better.Cloud-edge collaborative control refers to the collaborative controlbetween cloud a

128、nd edge access points.Cloud provides flexible control of edgeincluding access control,automatic allocation of bandwidth resources,and inter-linkcoordination.Edge access point controls resources within the range based on cloudconfiguration.In this case,high-rate and efficient transmission channels an

129、d large andhigh real-time transmission bandwidth are required between cloud and edge to ensurereal-time information exchange through plug and play interfaces.China Mobile6G Lean RAN White Paper（2022）235Future outlookLooking back on the past year,the industry-university-research ecosystem for 6Gnetwo

130、rk has shown a thriving situation.China Mobile proposed lean network as oneof the characteristics of 6G networks in 2020.This white paper starts from the drivingforce of the 6G lean radio access network,and introduces the architecture and theinvolved key technologies of the lean radio access network

131、.Looking forward to thefuture,the lean radio access network also needs to consider the following pointsaspects:Standards and product ecosystemThe development of technology is inseparable from complete and healthystandards and product ecosystem.Lean network proposes signaling base stations anddata ba

132、se stations with customized network functions,intelligence-driven protocolfunction design concepts,and high-level network autonomy technology.Whileenhancing protocol stack design with new technologies such as AI,high-quality datasets,selecting suitable models,and sharing models between different man

133、ufacturersare the keys to enhancing protocol stack design with the help of AI and other newtechnologies,which are inseparable from a healthy open source ecosystem.How tocreate a new industrial ecosystem that combines standards and open source is aquestion that needs to be answered in the future.Netw

134、ork deploymentThe throughput and latency requirements of 6G networks are higher.High-rateand high-efficiency transmission channels and transmission networks with largebandwidth,lowlatency,andflexibletopologyarerequiredforcloud-sidecollaboration in 6G lean radio networks to ensure the real-time infor

135、mationinteraction between plug-and-play interfaces.Network deployment requires anintegrated design of cloud,transmission network and network access points.Thedecoupling of signaling and data requires coordinating the available 6G frequencybands to give full play to the advantages of wide coverage an

136、d flexible service loading.China Mobile6G Lean RAN White Paper（2022）24In addition,we need to consider how to build sensitive and accurate perceptioncapabilities to ensure dynamic and rapid wake-up of network nodes and functions.Computing and processing capacityLean radio network meets the extreme se

137、rvice requirements of 6G through leanarchitecture and intelligent means.The design of lean network puts forward newrequirements for the computing power and storage of the network and terminal,andfurther puts forward new requirements for the chip.Unlimited increase of computingpower demand,especially

138、 the terminal computing power demand,will increase thecost and power consumption of the network.How to find a balance betweencomputing power demand and intelligence is a problem to be faced in the subsequenttechnical scheme design.5G has begun large-scale commercial deployment in the world,and the g

139、lobalindustry is incubating and nurturing services and applications around 2B and 2C.Theexperience and lessons of 5G will become a very important source of innovation for6G research.6G will further inherit and develop the technologies and concepts thathave been verified and feasible in 5G.At the sam

140、e time,6G also needs to look ahead.In terms of requirements,the application scenarios in 6G will be more complex,andmore flexible adaptability needs to be considered at the beginning of network design.The future 6G network needs to be as concise as possible,support plug and play,andsupport dynamic s

141、witching of functions,resources,and capabilities,thereby savingpowerconsumptionandcosts.The6Gleannetworksupportsdistributedground-air-space integration.Through a distributed and unified core network,and aunified access mechanism and protocol process,terminals can access differentsystems,including te

142、rrestrial,underwater,and satellite systems to achieve seamlessconnection and handover of user experience,and ensure 6G coverage anytime andanywhere.The lean network also needs to simplify the protocol as much as possible,and support the network deployment of decoupling of data and signaling links,su

143、chas using low frequencybands for signaling coverage,simplifying mobilitymanagement,ensuring real-time access of users,and switching on high-frequencybands on demand to support the bearing of high-rate services.Cloud-based hardwareChina Mobile6G Lean RAN White Paper（2022）25can be shared among multip

144、le frequency bands and multiple base stations,or sharedamong communication functions,AI,and perception,thereby reducing the overallpower consumption and cost of the network.Therefore,we should not only bedown-to-earth,but also look up at the stars.Lets promote the development of 6G leanradio access

145、networks through the collaboration of industry,university,research andapplication,and explore 6G efficient network solutions together.China Mobile6G Lean RAN White Paper（2022）26References1.China Mobile Research Institute,“White Paper on Technology Trends for2030+R”,Nov.2020.2.China Mobile Research I

146、nstitute,“White Paper on Vision and Requirements for2030+R”,Nov.2020.3.China Mobile Research Institute,“White Paper on the Vision of NetworkArchitecture for 2030+R”,Nov.2020.4.LIU Guangyi,WANG Yingying,WANG Ailing,et al.6G Latest Progress andFutureDevelopmentJ.RadioCommunicationsTechnology,2021,47(6

147、):668-678.5.3GPPTS 23.501,“System Architecture for the 5G System(5GS)S.”6.3GPPTS 38.300,“NR;NR and NG-RAN Overall DescriptionS.”China Mobile6G Lean RAN White Paper（2022）27List of abbreviations4G4th Generation Mobile Networks5G5th Generation Mobile Networks6G6th Generation Mobile NetworksAIArtificial IntelligenceDOICTData，Operation，Information andCommunication TechnologiesIPInternet ProtocolMACMediumAccess ControlQoSQuality of ServiceRLCRadio Link ControlRRCRadio Resource Control