Method and apparatus for functional distribution of RRC in wireless communication system

Abstract

The present disclosure relates to a 5G communication system or a 6G communication system for supporting higher data rates beyond a 4G communication system such as long term evolution (LTE). The present disclosure provides techniques for reconfiguring a radio resource control (RRC) layer in a wireless communication network. The method comprises assigning each of a plurality of functions associated with the RRC layer to at least one of a layer of a plurality of RRC sub-layers, wherein the plurality of RRC sub-layers include an RRC-LI layer, an RRC-L2 layer, and an RRC-L3 layer. The method also comprises mapping each of the plurality of assigned functions to at least one of a plurality of channels for communication using the corresponding at least one RRC sub-layer. The method thereafter comprises defining a message format for at least one of the plurality of RRC sub-layers for communication using the at least one of the plurality of channels.

Description

METHOD AND APPARATUS FOR FUNCTIONAL DISTRIBUTION OF RRC IN WIRELESS COMMUNICATION SYSTEM

[0001] The present disclosure generally relates to the field of wireless communication networks, and more particularly, relates to methods and systems for reconfiguring a Radio Resource Control (RRC) layer in a wireless communication network.

[0002] Considering the development of wireless communication from generation to generation, the technologies have been developed mainly for services targeting humans, such as voice calls, multimedia services, and data services. Following the commercialization of 5G (5th generation) communication systems, it is expected that the number of connected devices will exponentially grow. Increasingly, these will be connected to communication networks. Examples of connected things may include vehicles, robots, drones, home appliances, displays, smart sensors connected to various infrastructures, construction machines, and factory equipment. Mobile devices are expected to evolve in various form-factors, such as augmented reality glasses, virtual reality headsets, and hologram devices. In order to provide various services by connecting hundreds of billions of devices and things in the 6G (6th generation) era, there have been ongoing efforts to develop improved 6G communication systems. For these reasons, 6G communication systems are referred to as beyond-5G systems.

[0003] 6G communication systems, which are expected to be commercialized around 2030, will have a peak data rate of tera (1,000 giga)-level bit per second (bps) and a radio latency less than 100μsec, and thus will be 50 times as fast as 5G communication systems and have the 1 / 10 radio latency thereof.

[0004] In order to accomplish such a high data rate and an ultra-low latency, it has been considered to implement 6G communication systems in a terahertz (THz) band (for example, 95 gigahertz (GHz) to 3THz bands). It is expected that, due to severer path loss and atmospheric absorption in the terahertz bands than those in mmWave bands introduced in 5G, technologies capable of securing the signal transmission distance (that is, coverage) will become more crucial. It is necessary to develop, as major technologies for securing the coverage, Radio Frequency (RF) elements, antennas, novel waveforms having a better coverage than Orthogonal Frequency Division Multiplexing (OFDM), beamforming and massive Multiple-input Multiple-Output (MIMO), Full Dimensional MIMO (FD-MIMO), array antennas, and multiantenna transmission technologies such as large-scale antennas. In addition, there has been ongoing discussion on new technologies for improving the coverage of terahertz-band signals, such as metamaterial-based lenses and antennas, Orbital Angular Momentum (OAM), and Reconfigurable Intelligent Surface (RIS).

[0005] Moreover, in order to improve the spectral efficiency and the overall network performances, the following technologies have been developed for 6G communication systems: a full-duplex technology for enabling an uplink transmission and a downlink transmission to simultaneously use the same frequency resource at the same time; a network technology for utilizing satellites, High-Altitude Platform Stations (HAPS), and the like in an integrated manner; an improved network structure for supporting mobile base stations and the like and enabling network operation optimization and automation and the like; a dynamic spectrum sharing technology via collision avoidance based on a prediction of spectrum usage; an use of Artificial Intelligence (AI) in wireless communication for improvement of overall network operation by utilizing AI from a designing phase for developing 6G and internalizing end-to-end AI support functions; and a next-generation distributed computing technology for overcoming the limit of UE computing ability through reachable super-high-performance communication and computing resources (such as Mobile Edge Computing (MEC), clouds, and the like) over the network. In addition, through designing new protocols to be used in 6G communication systems, developing mechanisms for implementing a hardware-based security environment and safe use of data, and developing technologies for maintaining privacy, attempts to strengthen the connectivity between devices, optimize the network, promote softwarization of network entities, and increase the openness of wireless communications are continuing.

[0006] It is expected that research and development of 6G communication systems in hyper-connectivity, including person to machine (P2M) as well as machine to machine (M2M), will allow the next hyper-connected experience. Particularly, it is expected that services such as truly immersive eXtended Reality (XR), high-fidelity mobile hologram, and digital replica could be provided through 6G communication systems. In addition, services such as remote surgery for security and reliability enhancement, industrial automation, and emergency response will be provided through the 6G communication system such that the technologies could be applied in various fields such as industry, medical care, automobiles, and home appliances.

[0007] There are needs to enhance RRC architecture and related RRC procedure to meet requirements of the next generation wireless communication system.

[0008] This summary is provided to introduce a selection of concepts, in a simplified format, that are further described in the detailed description of the invention. This summary is neither intended to identify key or essential inventive concepts of the invention nor is it intended for determining the scope of the invention.

[0009] According to an embodiment of the disclosure, a method performed by a user equipment (UE) is provided. The method comprises: identifying a plurality of radio resource control (RRC) sublayers including at least two of a first RRC sublayer, a second RRC sublayer, or a third RRC sublayer; and performing an operation for each of the plurality of RRC sublayers.

[0010] According to an embodiment of the disclosure, a user equipment (UE) is provided. The UE comprises: a transceiver; and a controller coupled with the transceiver and configured to: identify a plurality of radio resource control (RRC) sublayers including at least two of a first RRC sublayer, a second RRC sublayer, or a third RRC sublayer, and perform an operation for each of the plurality of RRC sublayers.

[0011] According to one embodiment of the present disclosure, a method for reconfiguring a radio resource control (RRC) layer in a wireless communication network is disclosed. The method comprises assigning each of a plurality of functions associated with the RRC layer to at least one of a RRC sub-layer of a plurality of RRC sub-layers, wherein the plurality of RRC sub-layers include an RRC-L1 layer, an RRC-L2 layer, and an RRC-L3 layer. The method further comprises mapping each of the plurality of assigned functions to at least one of a plurality of channels for communication using the corresponding at least one RRC sub-layer. The method also comprises defining a message format for at least one of the plurality of RRC sub-layers for communication using the at least one of the plurality of channels.

[0012] According to another embodiment of the present disclosure, a system for reconfiguring a Radio Resource Control (RRC) layer in a wireless communication network is disclosed. The system comprises a memory and a processor coupled to the memory. The processor is configured to assign each of a plurality of functions associated with the RRC layer to at least one of a RRC sub-layer of a plurality of RRC sub-layers, wherein the plurality of RRC sub-layers include an RRC-L1 layer, an RRC-L2 layer, and an RRC-L3 layer. The processor is further configured to map each of the plurality of assigned functions to at least one of a plurality of channels for communication using the corresponding at least one RRC sub-layer. The processor is furthermore configured to map each group of functions to a plurality of channels for communication using the corresponding RRC sub-layer. The processor is also configured to define a message format for at least one of the plurality of RRC sub-layers for communication using the at least one of the plurality of channels.

[0013] To further clarify the advantages and features of the present invention, a more particular description of the invention will be rendered by reference to specific embodiments thereof, which is illustrated in the appended drawings. It is appreciated that these drawings depict only typical embodiments of the invention and are therefore not to be considered limiting of its scope. The invention will be described and explained with additional specificity and detail in the accompanying drawings.

[0014] According to various embodiments of the disclosure, RRC structure and RRC procedure can be efficiently enhanced.

[0015] These and other features, aspects, and advantages of the present invention will become better understood when the following detailed description is read with reference to the accompanying drawings in which like characters represent like parts throughout the drawings, wherein:

[0016] FIGURE 1 illustrates an exemplary 5G network architecture, in accordance with prior art;

[0017] FIGURE 2 illustrates an example scenario depicting a control plane 5G protocol stack, in accordance with prior art;

[0018] FIGURE 3 illustrates various functions of a radio resource control (RRC) layer, in accordance with prior art;

[0019] FIGURE 4(a) illustrates configuration control using the RRC layer, in accordance with prior art;

[0020] FIGURE 4(b) illustrates mobility / handover control using the RRC layer, in accordance with prior art;

[0021] FIGUREs 5(a) and 5(b) illustrate exemplary architectures of a wireless communication network, in accordance with an embodiment of the present disclosure;

[0022] FIGURE 6 illustrates a block diagram of a system for reconfiguring a radio resource control (RRC) layer in a wireless communication network, in accordance with an embodiment of the present disclosure;

[0023] FIGURE 7 illustrates a flow diagram depicting a method for reconfiguring the RRC layer in a wireless communication network, in accordance with an embodiment of the present disclosure;

[0024] FIGURE 8 illustrates a protocol stack of RRC sub-layers and its related endpoints for each RRC functionality, in accordance with an embodiment of the present disclosure;

[0025] FIGUREs 9-11 illustrate a mapping of functions of the RRC sub-layers to a plurality of channels, in accordance with an embodiment of the present disclosure;

[0026] FIGURE 12 illustrates a first message format for an RRC-L1 layer, in accordance with an embodiment of the present disclosure;

[0027] FIGUREs 13-14 illustrate exemplary embodiments of a second message format for an RRC-L2 layer, in accordance with different embodiments of the present disclosure;

[0028] FIGUREs 15(a)-15(b) illustrate a signal flow diagram to transmit the SI to the UE, in accordance with different embodiments of the present disclosure;

[0029] FIGURE 16-17 illustrate a call flow diagram to perform an RRC connection setup procedure between a UE and a gNB, in accordance with different embodiments of the present disclosure;

[0030] FIGURE 18 illustrates a block diagram showing a structure of a user equipment (UE) (or a terminal) according to an embodiment of the disclosure; and

[0031] FIGURE 19 illustrates a block diagram showing a structure of a base station according to an embodiment of the disclosure.

[0032] Further, skilled artisans will appreciate that elements in the drawings are illustrated for simplicity and may not have necessarily been drawn to scale. For example, the flow charts illustrate the method in terms of the most prominent steps involved to help to improve understanding of aspects of the present invention. Furthermore, in terms of the construction of the system, one or more components of the system may have been represented in the drawings by conventional symbols, and the drawings may show only those specific details that are pertinent to understanding the embodiments of the present invention so as not to obscure the drawings with details that will be readily apparent to those of ordinary skill in the art having the benefit of the description herein.

[0033] For the purpose of promoting an understanding of the principles of the invention, reference will now be made to the embodiment illustrated in the drawings and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended, such alterations and further modifications in the illustrated system, and such further applications of the principles of the invention as illustrated therein being contemplated as would normally occur to one skilled in the art to which the invention relates.

[0034] It will be understood by those skilled in the art that the foregoing general description and the following detailed description are explanatory of the invention and are not intended to be restrictive thereof.

[0035] Reference throughout this specification to “an aspect”, “another aspect” or similar language means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, appearances of the phrase “in an embodiment”, “in another embodiment” and similar language throughout this specification may, but do not necessarily, all refer to the same embodiment.

[0036] The terms “comprises”, “comprising”, or any other variations thereof, are intended to cover a non-exclusive inclusion, such that a process or method that comprises a list of steps does not include only those steps but may include other steps not expressly listed or inherent to such process or method. Similarly, one or more devices or sub-systems or elements or structures or components proceeded by “comprises... a” does not, without more constraints, preclude the existence of other devices or other sub-systems or other elements or other structures or other components or additional devices or additional sub-systems or additional elements or additional structures or additional components.

[0037] The words / phrases "exemplary", “example”, “illustration”, “in an instance”, “and the like”, “and so on”, “etc.”, “etcetera”, “e.g.,”, “i.e.,” are merely used herein to mean "serving as an example, instance, or illustration." Any embodiment or implementation of the present subject matter described herein using the words / phrases "exemplary", “example”, “illustration”, “in an instance”, “and the like”, “and so on”, “etc.”, “etcetera”, “e.g.,”, “i.e.,” is not necessarily to be construed as preferred or advantageous over other embodiments.

[0038] Embodiments herein may be described and illustrated in terms of blocks which carry out a described function or functions. These blocks, which may be referred to herein as managers, units, modules, hardware components or the like, are physically implemented by analog and / or digital circuits such as logic gates, integrated circuits, microprocessors, microcontrollers, memory circuits, passive electronic components, active electronic components, optical components, hardwired circuits and the like, and may optionally be driven by a firmware. The circuits may, for example, be embodied in one or more semiconductor chips, or on substrate supports such as printed circuit boards and the like. The circuits constituting a block may be implemented by dedicated hardware, or by a processor (e.g., one or more programmed microprocessors and associated circuitry), or by a combination of dedicated hardware to perform some functions of the block and a processor to perform other functions of the block. Each block of the embodiments may be physically separated into two or more interacting and discrete blocks without departing from the scope of the disclosure. Likewise, the blocks of the embodiments may be physically combined into more complex blocks without departing from the scope of the disclosure.

[0039] It should be noted that elements in the drawings are illustrated for the purposes of this description and ease of understanding and may not have necessarily been drawn to scale. For example, the flowcharts / sequence diagrams illustrate the method in terms of the steps required for understanding of aspects of the embodiments as disclosed herein. Furthermore, in terms of the construction of the device, one or more components of the device may have been represented in the drawings by conventional symbols, and the drawings may show only those specific details that are pertinent to understanding the present embodiments so as not to obscure the drawings with details that will be readily apparent to those of ordinary skill in the art having the benefit of the description herein. Furthermore, in terms of the system, one or more components / modules which comprise the system may have been represented in the drawings by conventional symbols, and the drawings may show only those specific details that are pertinent to understanding the present embodiments so as not to obscure the drawings with details that will be readily apparent to those of ordinary skill in the art having the benefit of the description herein.

[0040] The accompanying drawings are used to help easily understand various technical features and it should be understood that the embodiments presented herein are not limited by the accompanying drawings. As such, the present disclosure should be construed to extend to any modifications, equivalents, and substitutes in addition to those which are particularly set out in the accompanying drawings and the corresponding description. Usage of words such as first, second, third etc., to describe components / elements / steps is for the purposes of this description and should not be construed as sequential ordering / placement / occurrence unless specified otherwise.

[0041] The various embodiments discussed below for describing the principles of the disclosure in the patent document are for illustration only and should not be interpreted as limiting the scope of the disclosure in any way. Those skilled in the art will understand that the principles of the disclosure can be implemented in any suitably arranged wireless communication system. For example, although the following detailed description of the embodiments of the disclosure will be directed to LTE and / or 5G communication systems, those skilled in the art will understand that the main points of the disclosure can also be applied to other communication systems with similar technical backgrounds and channel formats with slight modifications without departing from the scope of the disclosure. The technical schemes of the embodiments of the present application can be applied to various communication systems, and for example, the communication systems may include global systems for mobile communications (GSM), code division multiple access (CDMA) systems, wideband code division multiple access (WCDMA) systems, general packet radio service (GPRS) systems, long term evolution (LTE) systems, LTE frequency division duplex (FDD) systems, LTE time division duplex (TDD) systems, universal mobile telecommunications system (UMTS), worldwide interoperability for microwave access (WiMAX) communication systems, 5th generation (5G) systems or new radio (NR) systems, etc. In addition, the technical schemes of the embodiments of the present application can be applied to future-oriented communication technologies. In addition, the technical schemes of the embodiments of the present application can be applied to future-oriented communication technologies.

[0042] Hereinafter, embodiments of the disclosure will be described in detail with reference to the accompanying drawings. It should be noted that the same reference numerals in different drawings will be used to refer to the same elements already described.

[0043] The embodiments herein and the various features and advantageous details thereof are explained more fully with reference to the non-limiting embodiments that are illustrated in the accompanying drawings and detailed in the following description. Descriptions of well-known components and processing techniques are omitted so as to not unnecessarily obscure the embodiments herein. Also, the various embodiments described herein are not necessarily mutually exclusive, as some embodiments can be combined with one or more other embodiments to form new embodiments. The term “or” as used herein, refers to a non-exclusive or, unless otherwise indicated. The examples used herein are intended merely to facilitate an understanding of ways in which the embodiments herein can be practiced and to further enable those skilled in the art to practice the embodiments herein. Accordingly, the examples are not be construed as limiting the scope of the embodiments herein.

[0044] In recent years, several broadband wireless technologies have been developed to meet the growing number of broadband subscribers by providing better applications and services. A second-generation (2G) wireless communication system was developed to provide voice services while ensuring the mobility of users. A third-generation (3G) wireless communication system supports not only voice services but also data services. In recent years, a fourth-generation (4G) wireless communication system has been developed to provide high-speed data services. However, currently, the 4G wireless communication system suffers from a lack of resources to meet the growing demand for high-speed data services. This problem is solved by deploying a fifth-generation (5G) wireless communication system to meet the ever-growing demand for high-speed data services. In addition to mobile broadband services, the 5G wireless communication system supports various use cases ranging from ultra-reliable low-latency communications to massive machine-type communications.

[0045] Fig. 1 illustrates an exemplary 5G network architecture, in accordance with prior art. As shown in Fig. 1, the 5G network architecture 100 consists of two parts, i.e., a next-generation radio access network (NG-RAN) and a 5G core (5GC) network. The 5GC network is based on service architecture, but the communication between the NG-RAN and the 5GC network is still point-to-point and uses a Next-Generation Application Protocol (NGAP) interface. As shown in Fig. 1, the NG-RAN 101 consisting of a set of g-NodeB (gNBs) 105 is connected to the 5GC network 103 through a New Generation (NG) interface 107. The gNBs 105 can be interconnected through an Xn interface. The gNB 105 consists of a gNB-Central Unit (CU) 105a and one or more gNB-Distributed Units (DUs) 105b. The gNB-CU 105a and the gNB-DUs 105b are connected via an F1 interface.

[0046] Due to the evolution from proprietary hardware-based RAN to virtualized RAN, the RAN functions can be placed anywhere from an edge to a cloud. For example, the RAN functionalities can be placed at the same location as core Network Functions (NFs). However, RAN can only interact with a single core network entity, for example, an Access and Mobility Management Function (AMF). The RAN, as well as AMF, becomes an anchor for all control messages of a User Equipment (UE) connected with the 5G network. Each of these messages has to pass through these network entities. Control plane signaling is required to establish a connection with both the RAN and the core network, and accordingly, a control plane stack is designed to maintain the connection between the RAN and core network. Fig. 2 illustrates an example scenario depicting a control plane 5G protocol stack, in accordance with prior art.

[0047] As depicted, a typical 5G Control plane stack consists of a Non-Access Stratum (NAS), RRC at L3, Packet Data Convergence Protocol (PDCP), Radio Link Control (RLC), and Medium Access Control (MAC) at Layer 2, and Physical (PHY) at Layer 1. As shown in Fig. 2, the UE 201 hosts all NAS and access stratum (AS) protocol stack for the control plane that includes NAS, RRC, PDCP, RLC, MAC, and PHY. The gNB-DU 203 hosts the RLC, MAC, and PHY protocol layers. The gNB-CU 205 hosts the RRC and PDCP layers, while the AMF 207 at the 5GC network, hosts the NAS protocol layer. Accordingly, the UE 201 is built with all these layers to establish a connection with the 5GC network and the RAN. The RRC is responsible for message transfer of higher layers like NAS and is responsible for configuration and control of the below layers like PDCP, RLC, MAC, and PHY amongst other functions like connection, mobility, bearer control, and management.

[0048] As shown in Fig. 3, the RRC function directly or indirectly impacts the message transfer, configuration, and control at all the layers, i.e., PHY / Layer 1, PDCP / RLC / MAC or Layer 2, and RRC / NAS / layer 3. However, the NG-RAN architecture is distributed in nature as shown in Fig 1. The gNB-DU hosts the layer 2 protocol stack like RLC, MAC, and layer 1 like PHY. The centralized unit, i.e., gNB-CU hosts the PDCP and RRC layer which is away from the gNB-DU. RRC is however responsible for configuring and controlling all these layers to establish and maintain a radio connection but is away from the actual configuration and control mechanism. A large percentage of configuration parameters in RRC is for configuring the lower layers. This requires close coordination between the lower layer units, functions, distributed units, layer 2 functions, and RRC. The RRC resides in a centralized unit, to build the right configuration messages. Hence, there is a lot of signalling overhead required between multiple gNB-DUs and gNB-CUs to prepare the RRC configuration and associated messages. This can also cause an increase in latency and an inefficient method for configuring the messages.

[0049] In another scenario, like mobility control, even though the lower layers are aware of the measurement reports, the lower layers are unable to take any action as all control is done by RRC, which resides in the CU 405. This again increases the overall latencies and delays the handover procedures which could result in connection losses and re-establishments in the system.

[0050] Figs. 4(a) and 4(b) represent the problem in further details. Fig. 4(a) illustrates configuration control using the RRC layer, in accordance with prior art. As shown in Fig. 4(a), cell group, and radio bearer configuration parameters are transmitted from DU 403 to CU 405 using L1 / L2 layers. Further, the RRC Reconfiguration message with the said parameters is transmitted from CU 405 to UE 401 via DU 403. However, this process has various problems such as system and signalling overhead, multiple dependent nodes for the same function, non-optimum configuration (e.g., in the case of measurements), etc.

[0051] Fig. 4(b) illustrates mobility / handover control using the RRC layer, in accordance with prior art. As shown in Fig. 4(b), L3 measurements are filtered measurements from L1 / L2 to L3 at the UE 401. L1 / L2 measurements from the UE 401 to DU 403 have limited scope as DU 403 has no control or all information. Further, RRC measurement report messages with filtered L3 measurements are transmitted from the UE 401 to CU 405 via DU 403. The CU 405 has mobility / handover control. The DU 403 configures cell groups but has no mobility control. Accordingly, delayed handover control messages can lead to handover failures or higher latencies in the system.

[0052] Since the RRC resides in the CU and manages a significant amount of control signaling for the MAC layer and the PHY layer, it results in a considerable increase in latency and fronthaul load. This is due to the necessity of transmitting all requisite information from the DU to the CU and then sending the response or action back from the CU to the DU. This issue will become more pronounced in 6th Generation (6G) networks due to increased dynamism at the L1 and L2 layers, which require control through the L3 (RRC). Furthermore, 6G networks, which may feature distributed RAN architectures, aim to provide significantly lower latency and more efficient operations. Therefore, it is necessary to redesign the configuration and control mechanisms of the RRC to accommodate the distributed nature of future RAN networks and to mitigate the aforementioned problems.

[0053] The present disclosure provides techniques for defining and managing the RRC functions in a distributed manner across the protocol layers in a service-based architecture for 5G wireless system, 6G wireless system, and beyond. The RRC function resides in layer 3 on a Centralized Unit (CU) according to existing art. The present disclosure provides techniques for distributing RRC functions across both distributed and centralized units. The present disclosure further discloses mechanisms for defining message format and channel mapping changes associated with the distributed RRC functions. Furthermore, the present disclosure discloses call flows for the distributed RRC functions.

[0054] The disclosed techniques are further explained in detail with respect to Figs. 5(a)-17.

[0055] Figs. 5(a) and 5(b) illustrate exemplary architectures of a wireless communication network, in accordance with an embodiment of the present disclosure. Fig. 7 illustrates a flow diagram depicting a method 700 for reconfiguring an RRC layer in the wireless communication network, in accordance with an embodiment of the present disclosure. For the sake of brevity, Figs. 5(a), 5(b), and 6 are explained in conjunction with each other.

[0056] As shown in Fig. 5(a), in an exemplary embodiment, the wireless communication network 500 may comprise an access network / radio access network (RAN) 500a which is connected to a cloud network 500b. As shown in Fig. 5(a), the UE 501, a Baseband Unit (BBU) 503, a Lower Layer Unit (LLU) 505, a Distributed Unit (DU) 507, and a HUB 509. The cloud network 500b may comprise a Centralized Unit (CU) 511, an AMF 513, a Session Management Function (SMF) 515, and other Network Functions (NFs) 517. In an embodiment, RAN 500a is considered to be a service-based RAN, and as a result, DU 507 / CU 511 can interact with any NFs such as AMF 513, SMF 513, and other NFs 517. All the NF nodes can be accessed by module HUB or Control Message Delivery (CMD) node. For example, the DU 511 is connected via a service-based interface to all the NFs like AMF, and SMF in the cloud network 500b including the CU 511 which resides in cloud network 500b. Further, the HUB 509 may act as a single anchor point for all UE messages. The HUB 509 may be an independent module located at a specific NF or located along with the DU 507. All control message transmissions between the UE 501 and the HUB 509 are managed through a single layer. The UE’s control message is parsed at the HUB 509 and then the HUB 509 delivers the message directly to its destination node. There is a Service-Based Interface (SBI) between the HUB 509 and the rest of the NFs 513, 515, and 517. The SBI interface may use HTTP / 2 types or equivalent protocols. As shown in Fig. 5(a), the HUB 509 may connect the DU 507 with the CU 511. Accordingly, Fig. 5(a) illustrates one possible architecture of the wireless communication network, where the CU 511 is in the cloud network 500b and the DU 507 is part of the access network 500a.

[0057] In an alternate embodiment, Fig. 5(b) illustrates another architecture of the wireless communication network, where the CU 511 is also part of the access network 500b and communicates directly with all the NFs 513, 515, and 517 via the SBI. Since the rest of the components in Fig. 5(b) are similar to those in Fig. 5(a), their descriptions are omitted for brevity. Accordingly, the present disclosure provides techniques to distribute RRC functionalities across various components of the wireless communication network 500, as discussed with reference to Figs. 5(a) and 5(b). It should be noted that Fig. 5(a) and 5(b) illustrate the exemplary architecture of the wireless communication network, according to the present disclosure. However, it should be noted that other similar network architectures capable of implementing the disclosed techniques are also within the scope of this disclosure.

[0058] In an embodiment, the access network 500a may perform the techniques as disclosed with reference to Fig. 7. Accordingly, the access network 500a may comprise a system for performing the techniques as disclosed with reference to Fig. 7. Fig. 6 illustrates a block diagram of a system 600 for reconfiguring a radio resource control (RRC) layer in a wireless communication network, in accordance with an embodiment of the present disclosure. The configuration of Fig. 6 may be understood as a part of the configuration of the access network. Further, the method 700 as disclosed below may be implemented in the system 600 according to a further embodiment.

[0059] Referring to Fig. 6, the system 600 may include at least one processor 602, a communication circuit 604 (e.g., communication unit, communicator or communication interface), and a memory 606. The communication circuit 604 may perform functions for transmitting and receiving signals via a wireless channel.

[0060] As an example, the at least one processor 602 may be a single processing unit or a number of units, all of which could include multiple computing units. The processor 602 may be implemented as one or more microprocessors, microcomputers, microcontrollers, digital signal processors, central processing units, state machines, logic circuitries, and / or any devices that manipulate signals based on operational instructions. Among other capabilities, the processor 602 is configured to fetch and execute computer-readable instructions and data stored in the memory 606. The processor 602 may include one or a plurality of processors. At this time, one or a plurality of processors 602 may be a general-purpose processor, such as a Central Processing Unit (CPU), an Application Processor (AP), or the like, a graphics-only processing unit such as a Graphics Processing Unit (GPU), a Visual Processing Unit (VPU), and / or an AI-dedicated processor such as a Neural Processing Unit (NPU). The one or a plurality of processors 602 may control the processing of the input data in accordance with a predefined operating rule or Artificial Intelligence (AI) model stored in the non-volatile memory and the volatile memory, i.e., the memory 606. The predefined operating rule or AI model is provided through training or learning.

[0061] The memory 606 may include any non-transitory computer-readable medium known in the art including, for example, volatile memory, such as Static Random Access Memory (SRAM) and Dynamic Random Access Memory (DRAM), and / or non-volatile memory, such as Read-Only Memory (ROM), erasable programmable ROM, flash memories, hard disks, optical disks, and magnetic tapes.

[0062] Embodiments are exemplary in nature, and the system 600 may include additional components required to implement the desired functionality of the system 600 in accordance with the requirements of the disclosure.

[0063] Thereafter, at step 701, the method 700 may include assigning each of a plurality of functions associated with the RRC layer to at least one of a RRC sub-layer of a plurality of RRC sub-layers. In an embodiment, the plurality of RRC sub-layers may include an RRC-L1 layer, an RRC-L2 layer, and an RRC-L3 layer. Accordingly, each of the plurality of functions, as shown in Table 1, is assigned to at least one of the plurality of RRC sub-layers, i.e., the RRC-L1 layer, an RRC-L2 layer, and an RRC-L3 layer. An exemplary assignment of the group of functions to the RRC sub-layers has been shown in Table 1:

[0064] Group of FunctionsRRC functionsRRC-L3 layerRRC-L2 layerRRC-L1 LayerBroadcast of SIMIBXSIBXETWS / CMAS / OtherXRRC connection controlPagingXConnection controlXXConnection state managementXRadio bearerXSecurityXXXConfiguration controlXXXQoS controlXMobilityXXAccess BarringXDC / CA cell managementXXXMeasurementsMeasurement configurationXXXMeasurement gapXMeasurement -ReportXXMISCNAS / CN message transfer (NAS, UE capability)XXSONXXX

[0065] Further, in an embodiment, the assigned functions of the RRC sub-layers can be fluidly moved across different units as per the requirements of the deployments and architecture design of the wireless communication network, such as 5G and / or 6G communication networks. Such an assignment of the RRC sub-layers to different units of the wireless communication network is shown in Fig. 8. As shown in Fig. 8, the UE 801 hosts the Access Stratum (AS) layers 1, 2, 3, and the plurality of sublayers, i.e., RRC-L1 layer, RRC-L2 layer, and RRC-L3 layer and their respective functionalities. In an embodiment, the RRC-L1 layer may be assigned to LLU 803 of the wireless communication network. In an exemplary embodiment, the LLU 803 hosts layer 1, commonly known as the physical layer. The LLU 803 also hosts the RRC-L1 functionalities and associated security services. Further, the RRC-L2 layer to a DU 805 of the wireless communication network. The DU 805 hosts layer 2 which is commonly associated with the functions of bearer management, buffer management, in-sequence delivery of messages, error detection and handling, etc. Similarly, the RRC-L3 layer may be assigned to a CU 807 of the wireless communication network. The CU 807 which can reside either in the cloud network (as shown in Fig. 5(a)) or in the access network (as shown in Fig. 5(b)), hosts the RRC-L3 layer functionality which can include all the functionalities of RRC-CU and any other additional capabilities that are added to layer 3 in the sixth generation communication protocols. The security services are available at CU and DU as well as independently, which may be used by the distributed RRC stack as per its requirement. Hence, in an embodiment, the RRC component is distributed across multiple network elements. Accordingly, the RRC-L3 (RRC-Layer3) resides within the CU 807, and the RRC-L2 (RRC-Layer2) resides in the DU 805 / DU-HUB network element (as shown in Figs. 5(a), 5(b)) and the RRC-L1 (RRC-Layer1) resides over the LLU 803 which carries the higher PHY layer.

[0066] Thereafter, at step 703, the method 700 may include mapping each of the plurality of assigned functions to at least one of a plurality of channels for communication using the corresponding at least one RRC sub-layer. The mapping of the functions to the plurality of channels is further explained with reference to Figs. 9-11. Fig. 9 illustrates a mapping of functions of the RRC-L1 layer to the plurality of channels, in accordance with an embodiment of the present disclosure. In an embodiment, as shown in Fig. 9, one or more of the plurality of functions assigned to the RRC-L1 layer are mapped to a physical channel. The physical channel consists of a Physical Broadcast channel (PBCH), a Physical Downlink Shared Channel (PDSCH), and a Physical Downlink Control Channel (PDCCH). Accordingly, the functions assigned to the RRC-L1 layer can be mapped to these physical channels directly. For example, the Minimum system information, On Demand System information, commonly known as Master Information Block (MIB) and System Information Blocks (SIB), is the set of broadcast channel messages that the network sends on the downlink to share network information. This message can be mapped directly to the PBCH and PDSCH. RRC-L1 layer configuration control messages that include the lower level or physical layer configuration parameters, can be sent over the PDSCH. RRC-L1 measurement configuration and measurement gap-related parameters can be sent over PDSCH. The PDSCH can also be used to send the RRC-L1 CA / DC cell management or SON-related parameters of the physical layer. However, there is a need to define new message formats to decode these RRC-L1 messages on the physical channel, which will be further explained with reference to Fig. 12.

[0067] Fig. 10 illustrates a mapping of functions of the RRC-L2 layer to the plurality of channels, in accordance with an embodiment of the present disclosure. In an embodiment, as shown in Fig. 10, one or more of the plurality of functions assigned to the RRC-L2 layer are mapped to the physical channel, a transport channel, and a logical channel. The transport channel consists of a Downlink shared channel (DL-SCH). The logical channel comprises a Common control channel (CCCH), a Dedicated control channel (DCCH), and a Dedicated traffic channel (DTCH). Accordingly, the functions assigned to the RRC-L2 layer can be mapped to these logical, transport, and physical channels. For example, the connection control function and associated messages are mapped to the CCCH which is sent over DL-SCH in the transport layer and then to PDSCH. The configuration control associated with layer 2, like radio bearer setup, quality of service (QoS) control, etc., are mapped to DCCH on the logical channel which is sent over DL-SCH and then over PDSCH. Further, the measurement control and configuration-related functions and messages that handle the L1 / L2 measurements are mapped to DCCH, then to DL-SCH, and finally sent over to PDSCH. The DU also offers the transfer of higher-layer messages related to service and DC(dual connectivity) / CA(carrier aggregation) management. This function and associated messages are sent on DCCH, DL-SCH, and then PDSCH. However, there is a need to now define new message formats to decode these RRC-L2 messages on these channels, which will be further explained with reference to Figs. 13-14.

[0068] Fig. 11 illustrates a mapping of functions of the RRC-L3 layer to the plurality of channels, in accordance with an embodiment of the present disclosure. In an embodiment, as shown in Fig. 11, one or more of the plurality of functions assigned to the RRC-L3 layer are mapped to the physical channel, a transport channel, and a logical channel. The transport channel consists of DL-SCH (Downlink shared channel), Paging channel (PCH), and Broadcast channel (BCH). The logical channel consists of CCCH, DCCH, Broadcast control channel (BCCH), Paging control channel (PCCH), and DTCH. Accordingly, the functions assigned to the RRC-L3 layer can be mapped to these logical, transport, and physical channels. For example, the connection control and access barring related functions and associated messages are mapped to the CCCH which is sent over DL-SCH in the transport layer and then on PDSCH. The configuration control associated with layer 3, like public land mobile network (PLMN), tracking or radio network area codes, etc, is mapped to DCCH on the logical channel which is sent over DL-SCH and then over PDSCH. Further, the measurement control and configuration-related functions and messages that handle the L3 measurements are mapped to DCCH, then to DL-SCH, and finally sent over to PDSCH. The CU also offers the transfer of higher-layer messages-related services and DC / CA management. This function and associated messages are sent on DCCH, DL-SCH, and then PDSCH. The CU is also associated with handling the higher layer broadcast information like CMAS, and ETWS messages and can use the BCCH, over BCH, and finally, PBCH to transport the associated system information. In order to handle the paging aspects, the paging message is sent over PCCH on a logical channel mapped to PCH and finally sent over PDSCH. The RRC-L3 may use the L3 message format which is as per current defined standards.

[0069] Referring back to Fig. 7, at step 705, the method 700 may include defining a message format for at least one of the plurality of RRC sub-layers for communication using the at least one of the plurality of channels. The message formats are further explained with reference to Figs. 11-13. Fig. 11 illustrates a first message format for the RRC-L1 layer, in accordance with an embodiment of the present disclosure. In an embodiment, a first message format for the RRC-L1 layer may be defined. The first message format may comprise a Downlink Control Information (DCI) bit (X_n) for identifying one of a data packet and an RRC-L1 packet transmitted by the RRC-L1 layer. In an embodiment, the RRC-L1 packet may be a control packet and the data packet may be a regular packet data. The data packet can be transferred from the wireless communication network to the UE or vice versa. The DCI bit (X_n) is used to differentiate the data packet from the RRC-L1 packet. The DCI bit may be sent on the PDCCH channel to configure resources on the PDSCH channel to send the associated data. A new format is defined to send the RRC_L1 messages, as shown in Fig. 11. The DCI bit X_n is used for the transmission of RRC_L1 configuration and information-related packets. Fig. 11 illustrates the format of the DCI bit (X_n), in accordance with an embodiment of the present disclosure. In Fig. 11, the DCI identifier (ID) is a 1-bit identifier of the DCI. This value indicates a DL DCI bit format. Further, a new bit is introduced D / C in the new format for the RRC-L1 layer. The DCI ID bit (D / C) is further explained in below Table 2. The new bit D / C is used to indicate the packet type in DCI. In legacy procedures, DCI always points to the data packet in the downlink. However, in the first message format, i.e., the newly added D / C bit, bit 0 indicates the value of the RRC-L1 layer packet, whereas bit 1 indicates that it is a regular data packet. In an embodiment, the RRC-L1 packet is one of a control packet and an information packet transmitted by the RRC-L1 layer. The remaining bits in the first message format indicate the frequency and time resource allocation and related parameters as used in legacy procedures. A downlink DCI also contains the frequency and time resources for the PDSCH channel. In the associated PDSCH channel, the actual message is sent.

[0070] DCI formatUsage0_0Scheduling of PUSCH in one cell0_1Scheduling of one or multiple PUSCH in one cell, or indicating downlink feedback information for configured grant PUSCH (CG-DFI)0_2Scheduling of PUSCH in one cell1_0Scheduling of PDSCH in one cell1_1Scheduling of one or multiple PDSCH in one cell, and / or triggering one-shot HARQ-ACK codebook feedback1_2Scheduling of PDSCH in one cell2_0Notifying a group of UEs of the slot format, available RB sets, COT duration, and search space set group switching2_1Notifying a group of UEs of the PRB(s) and OFDM symbol(s) where UE may assume no transmission is intended for the UE2_2Transmission of TPC commands for PUCCH and PUSCH2_3Transmission of a group of TPC commands for SRS transmissions by one or more UEs2_4Notifying a group of UEs of the PRB(s) and OFDM symbol(s) where UE cancels the corresponding UL transmission from the UE2_5Notifying the availability of soft resources as defined in Clause 9.3.1 of [10, TS 38.473]2_6Notifying the power-saving information outside DRX Active Time for one or more UEs2_7Notifying paging early indication and TRS availability indication for one or more UEs.3_0Scheduling of NR side link in one cell3_1Scheduling of LTE side link in one cell4_0Scheduling of PDSCH with CRC scrambled by MCCH-RNTI / G-RNTI for broadcast4_1Scheduling of PDSCH with CRC scrambled by G-RNTI / G-CS-RNTI for multicast4_2Scheduling of PDSCH with CRC scrambled by G-RNTI / G-CS-RNTI for multicastX_nTransmission of RRC_L1 configuration and Information packets

[0071] Further, the first message format may include a plurality of bits identifying a type of message transmitted by the RRC-L1 layer, as illustrated in Fig 11. The transmitted message may belong to one or more of the plurality of functions assigned to the RRC-L1 layer. For example, the transmitted message may be an MIB message, an SIB message, a configuration message, a cell management message, or any other message transmitted by the RRC-L1 layer. In an example, the message type is a 3-bit field that can be extended to 4-bit or higher. The corresponding message contents in the PDSCH control packet are the message that contains MIB contents, SIB packet, etc. Further, the AS security service is applied on the RRC-L1 layer packets as well as on PDSCH. The format for the plurality of bits identifying the type of message is further explained in Table 3:

[0072] Message Type (3 bits)Message ContentsMIB (000)MIB contentsSIB (001)SIB packetConfiguration (010)Configuration Type (2 bits)Measurement or Connection configuration detailsMeasurement Configuration(00)Measurement configuration packetConnection Control(01)Connection Control packetReserved (10-11)Reserved for future useCell mgmt. (011)Cell Management Type (2 bits)Measurement gap / CA / DC / SON cell mgmt. detailsMeasurement Gap (00)Measurement gap managementCarrier Aggregation (01)Carrier Aggregation cell managementDual Connectivity(01)Dual connectivity managementReserved (10-11)Reserved for future use100-111Reserved

[0073] As shown in Table 3, the message contains a message type field with 3 bits and further contains MIB and SIB message contents. Furthermore, for each message type, there can be a configuration or cell management type field that further helps to distinguish whether the message is of a particular configuration or cell management type.

[0074] Fig. 13 illustrates a first exemplary embodiment of a second message format for the RRC-L2 layer, in accordance with an embodiment of the present disclosure. In an embodiment, a second message format for the RRC-L2 layer may be defined. In the first embodiment, the second message format may comprise a Packet Data Unit (PDU) bit for identifying one of a data packet and an RRC-L2 packet transmitted by the RRC-L2 layer. The data packet may be a regular packet data and can be transferred from the wireless communication network to the UE or vice versa. The PCU bit is used to differentiate the data packet from the RRC-L2 packet. The RRC-L2 packet may be one of a Packet Data Convergence Protocol (PDCP) control packet and an information packet. An exemplary second message format is illustrated in Fig 13. As shown in Fig. 13, the second message format may consist of the PDU bit, i.e., a D / C bit, which is associated with either RRC-L2 control or layer 2 control message. As shown in Fig. 13, if the value of the D / C bit is 0, then the packet is the RRC-L2 packet. However, if the value of the D / C bit is 1, then the packet is the data packet. Further, the second message format may include a plurality of bits identifying a type of message transmitted by the RRC-L2 layer. The plurality of bits has been illustrated as the PDU type in Fig. 13. The transmitted message may belong to one or more of the plurality of functions assigned to the RRC-L2 layer. For example, the transmitted message may include, but is not limited to, RRC-L2 connection control message, configuration control message for QoS, radio bearer setup message, mobility control message, upper layer message transfer, SON message, and other miscellaneous actions. In an exemplary embodiment, as shown in Fig. 13, the PDU type is a 3-bit field that may be extended to 4-bit or higher. Further, the AS security service is on these packets as well. The PDU type details are further expanded in below Table 4:

[0075] PDU TypeDescription000PDCP Status Report001Interspersed ROHC Feedback010RRC-L2 Connection Control011Configuration Control (QoS, DRB, Measurements)100Mobility Control101Upper-layer message transfer110SON, others111Reserved

[0076] As per the current specification of a PDCP control PDU, the first two PDU types, i.e., PDCP Status Report and Interspersed ROHC feedback are already defined. The disclosed techniques utilize the remaining PDU types to identify the RRC-L2 layer control messages.

[0077] Fig. 14 illustrates a second exemplary embodiment of a second message format for the RRC-L2 layer, in accordance with an embodiment of the present disclosure. In the second embodiment, the second message format may be defined as a Medium Access Control (MAC) control element (CE). Accordingly, the MAC CE may be used to indicate the RRC-L2 messages. In an embodiment, the MAC CE may comprise a logical channel identifier (LCID) for identifying a type of message transmitted by the RRC-L2 layer. The transmitted message may belong to one or more of the plurality of functions assigned to the RRC-L2 layer. The transmitted message may correspond to the transmitted message of Fig. 13. As shown in Fig. 14, in the new RRC-L2 control messages over the MAC CE, there can be a single configuration control activation or deactivation command that identifies whether a particular configuration can be activated or deactivated instead of sending the complete configuration to the UE over a MAC PDU. Alternatively, it is also possible to send the configuration control message in MAC Control PDU. The table in Fig. 14 shows the mapping of the index to Logical channel ID (LCID) values. In an embodiment, new values are added to the LCID to include Configuration control that can be activated or deactivated. The configuration is present earlier in a different layer and the RRC-L2 layer can just activate or deactivate the message. Similarly, an entry can be added for the Mobility control command that shall process mobility at the RRC-L2 layer.

[0078] In a further embodiment of the present disclosure, System information (SI) may also be transmitted using the plurality of RRC sub-layers, as defined above with respect to Figs. 7-14. Accordingly, the SI may be broadcast in two different ways based on the deployment of CU in the cloud network or the access network, as shown in Figs. 15(a)-15(b). All system information in the current architecture is broadcast from the CU. However, as discussed, the RRC functionalities have been assigned to different RC sub-layers. Accordingly, the entity closest to the UE, which is the LLU, forms the system information related to cell selection, reselection, etc., as these mainly consist of physical layer signal parameters and priorities. Since the LLU is responsible for PHY layer functionalities, the configuration and information required for the System Information or Master Information Block are available directly at the LLU. However, when higher layer information needs to be broadcasted, such as CMAS or ETWS, the RRC-L3 layer is responsible for the broadcast. This division of responsibilities is beneficial because the RRC-L3 layer, which may reside in the cloud, can collect the necessary information from the NFs for such emergency broadcasts and then transmit it to the UE. As shown in Fig. 15(a), the RRC-L1 layer 1503 broadcasts the Minimum System Information like MIB and SIB. Similarly, the RRC-L1 layer 1504 also broadcasts the can also take care of broadcasting the on-demand SI. All such Minimum and On Demand SI information usually contains the threshold parameters, reselection parameters, and lower layer configurations. These parameters and configurations may be maintained and broadcasted by the LLU 1504 rather than the CU 1508. Accordingly, coordination between the LLU 1504 and the CU 1508 for configuring and controlling the above parameters may be avoided. Similarly, there are certain system information messages like CMAS and ETWS, which broadcast emergency-related information and are usually triggered from the core network. These messages also carry configurations and information from the central unit in the core network. Accordingly, these SI messages are broadcasted from the RRC-L3 layer 1508. As shown in Fig. 15(a), the CU 1508 is a part of the access network. However, as shown in Fig. 15(b), the CU 1508 is part of the cloud network. Accordingly, as discussed above, the SI messages may be broadcast to the UE in both scenarios using the RRC sub-layers. Furthermore, these messages are indicative and can also overall cover the new system information messages that can come in a 6G communication network. Accordingly, the LLU can broadcast information related to its systems, and higher-layer units may send broadcast information related to their systems.

[0079] In an embodiment, the RRC connection setup procedure between the UE and the gNB, such as may be performed using the RRC sub-layers, as shown in Fig. 16. As shown in Fig. 16, the DU / RRC-L2 layer 1606 may form a service-based interface with the core network and may interact with any NF, such as AMF 1610 in the core network. At step 1601, the UE 1602 is in IDLE mode. Accordingly, the LLU / RRC-L1 layer 1604 transmits one of the MIB and SIB messages to the UE 1602 in a periodic manner on the broadcast channel following the channel mapping described in Fig 9. At step 1603a, the UE 1602 needs to establish the RRC connection. Accordingly, at step 1603a, the DU / RRC-L2 layer 1606 receives an uplink layer 3 message, i.e., UL L3 message from the UE 1602. The UL L3 message is received on SRB0 which is the default signaling radio bearer. The radio bearer is established between the UE 1602 and the DU / RRC-L2 layer 1606. The UL L3 message is sent in UplinkInformationMessage Transfer on the default signaling radio bearer to the DU / RRC-L2 layer 1606. In an exemplary embodiment, the UL L3 message IE required to transfer the RRC setup request is shown below table 5:

[0080]

[0081] The IEDedicatedL3-Messageis used to transfer UE-specific L3 layer information between the CU / RRC-L3 layer 1608 and the UE 1602. The DU / RRC-L2 layer 1606 is transparent for this information.

[0082] At step 1603b, the DU / RRC-L2 layer 1606 transmits a service request to the CU / RRC-L3 layer 1608 using the service-based framework of services and service operation. The service request, i.e., Ndu_RRC_Setup_request can be a service operation between the DU / RRC-L2 layer 1606 and the CU / RRC-L3 layer 1608, which can transfer the dedicated UL L3 message to the CU / RRC-L3 layer 1608 via the DU / RRC-L2 layer 1606.

[0083] At step 1605a, the CU / RRC-L3 layer 1608 transmits a Ndu_RRC_Setup_response to the DU / RRC-L2 layer 1606 with the relevant connection control information. At step 1605b, internal signaling with RRC setup request-related details between the DU / RRC-L2 layer 1606 and the LLU / RRC-L1 layer 1604, are provided so that the LLU / RRC-L1 layer 1604 is aware of the connection control. At step 1607a, the DU / RRC-L2 layer 1606 transmits an RRC-L2 setup message to the UE 1602 that also piggybacks the RRCSetup message from the CU / RRC-L3 layer 1608 which it received in step 1611a. The IE changes of the new message are shown below table 6:

[0084]

[0085] The IE RRC_CU_Setup can include any specific information or identifier from the CU / RRC-L3 layer 1608 that is necessary for the connection setup including cell level info, plmn info, area codes, etc.

[0086] At step 1607b, the LLU / RRC-L1 layer 1604 transmits an RRC-L1-Setup request message to the UE 1602 with lower layer configurations. The details of the IE are shown below table 7:

[0087]

[0088] At step 1609, the UE 1602 transmits the RRC setup complete notification to the DU / RRC-L2 layer 1606. At step 1611a, the DU / RRC-L2 layer 1606 transmits RRCsetupcomplete notify (service-based message) to the CU / RRC-L3 layer 1608. Accordingly, the RRC-L3 layer 1608 receives the RRC setup complete notification from the UE 1602 via the RRC-L2 layer 1606. At step 1611b, the internal signaling is sent from the DU / RRC-L2 layer 1606 to the LLU / RRC-L1 layer 1604 to indicate the connection setup.

[0089] Fig. 17 illustrates a call flow diagram to perform the RRC connection setup procedure between the UE and the gNB, in accordance with another embodiment of the present disclosure. As shown in Fig. 17, the CU / RRC-L3 layer 1708 may form a service-based interface with the core network and may interact with any NF, such as AMF 1710 in the core network. At step 1701, the UE 1702 is in IDLE mode. Accordingly, the LLU / RRC-L1 layer 1704 transmits one of the MIB and SIB messages to the UE 1702 in a periodic manner on the broadcast channel following the channel mapping described in Fig 9.

[0090] At step 1703, the UE 1702 needs to establish the RRC connection. Accordingly, at step 1703, the CU / RRC-L3 layer 1708 receives an uplink layer 3 messages, i.e., UL L3 message from the UE 1702. The UL L3 message is received on SRB0 which is the default signaling radio bearer. The radio bearer is established between the UE 1602 and the CU / RRC-L3 layer 1708. The UL L3 message is sent in UplinkInformationMessage Transfer on the default signaling radio bearer to the CU / RRC-L3 layer 1708. At steps 1705a and 1705b, the CU / RRC-L3 layer 1708 the CU propagates the RRCsetup request message to the DU / RRC-L2 layer 1706 and the LLU / RRC-L1 layer 1704 respectively. Accordingly, the CU / RRC-L3 layer 1708 transmits the RRC setup request message to the UE 1702 via the DU / RRC-L2 layer 1706. At step 1707a, the CU / RRC-L3 layer 1708 transmits an RRC-L3 setup request message to the UE 1702. The details of the RRC-L3 setup request message are shown below table 8:

[0091]

[0092] This IE contains all the relevant information related to connection control at the CU / RRC-L3 layer 1708 which includes, the identifiers, area codes, PLMN identity, etc.

[0093] At step 1707b, the DU / RRC-L2 layer 1706 transmits an RRC-L2 setup request message to the UE 1702 including the radio bearer configurations, as shown below table 9:

[0094]

[0095] At step 1707c, the LLU / RRC-L1 layer 1704 transmits an RRC-L1 setup request with the physical layer configurations to the UE 1702. The physical layer configurations are shown below table 10:

[0096]

[0097] At step 1709, the CU / RRC-L3 layer 1708 receives the RRC setup complete message from the UE 1702. At step 1711, the CU / RRC-L3 layer 1708 transmits internal signalling to the DU / RRC-L2 layer 1706 and the LLU / RRC-L1 layer 1704 to inform about the RRC setup completion.

[0098] In a further embodiment, the configuration control parameters may be transmitted using the RRC sub-layers. Configuration control in the existing architecture is all sent and prepared by the CU. The CU however needs to synchronize with the lower layer entities, DU and RU / BBU, etc., to prepare the lower layer parameters. As known in the art, a large part of the RRC configuration consists of lower-layer parameters. Hence, in an embodiment of the present disclosure, each of the RRC sub-layers is responsible for configuring its parameters and can communicate the same to the UE. Hence, the physical configuration, radio bearer configuration, and L3 level configuration are dissociated and sent separately to the UE by the corresponding RRC sub-layer.

[0099] In a further embodiment, connection control may be maintained using the RRC sub-layers. In the existing art, the connection control is maintained over both the CU and the AMF. Associated state management is also present in both entities. However, in an embodiment of the present disclosure, a single connection state management is maintained at the CU which is in the cloud, and the RRC connection setup is handled by the DU while notifying the CU to keep the state controls.

[0100] In the present disclosure, the mobility control function of the RRC layer may be performed using the RRC sub-layers. In the existing art, measurement parameters are all physical layer parameters. However, the lower layer units do not have the control or visibility to make handover decisions based on these parameters. Additionally, lower-layer entities lack the authority to configure parameters such as measurement gaps, timing, and thresholds. This problem is addressed in the present disclosure, where lower-layer entities can configure their parameters. If a lower layer measurement report needs to be transmitted, the DU takes the mobility decisions. However, if an L3 level measurement report needs to be transmitted, the CU must be notified. Thus, mobility control is split between the CU and the DU.

[0101] Accordingly, the present disclosure provides techniques for reconfiguration of the RRC layer. The present disclosure also defines the distribution of the RRC functions and its associated protocol stack for functions such as broadcast of SI, RRC connection setup, measurement control, etc., across the access stratum layers, etc. The present disclosure also defines channel mapping for the RRC-L1, RRC-L2 and RRC-L3 layers. The present disclosure also defines the message format required to transmit the RRC-L1 and RRC-L2 messages.

[0102] FIGURE 18 illustrates a block diagram showing a structure of a user equipment (UE) (or a terminal) according to an embodiment of the disclosure; and

[0103] As shown in FIG. 18, a terminal according to an embodiment may include a transceiver 1810, a memory 1820, and a processor (or a controller) 1830. The transceiver 1810, the memory 1820, and the processor (or controller) 1830 of the terminal may operate according to a communication method of the terminal described above. However, the components of the terminal are not limited thereto. For example, the terminal may include more or fewer components than those described in Fig. 18. In addition, the processor (or controller) 1830, the transceiver 1810, and the memory 1820 may be implemented as a single chip. Also, the processor (or controller) 1830 may include at least one processor.

[0104] The transceiver 1810 collectively refers to a terminal station receiver and a terminal transmitter, and may transmit / receive a signal to / from a base station or another terminal. The signal transmitted or received to or from the terminal may include control information and data. The transceiver 1810 may include a RF transmitter for up-converting and amplifying a frequency of a transmitted signal, and a RF receiver for amplifying low-noise and down-converting a frequency of a received signal. However, this is only an example of the transceiver 1810 and components of the transceiver 1810 are not limited to the RF transmitter and the RF receiver.

[0105] Also, the transceiver 1810 may receive and output, to the processor (or controller) 1830, a signal through a wireless channel, and transmit a signal output from the processor (or controller) 1830 through the wireless channel.

[0106] The memory 1820 may store a program and data required for operations of the terminal. Also, the memory 1820 may store control information or data included in a signal obtained by the terminal. The memory 1820 may be a storage medium, such as read-only memory (ROM), random access memory (RAM), a hard disk, a CD-ROM, and a DVD, or a combination of storage media.

[0107] The processor (or controller) 1830 may control a series of processes such that the terminal operates as described above. For example, the processor (or controller) 1830 may receive a data signal and / or a control signal, and the processor (or controller) 1830 may determine a result of receiving the signal transmitted by the base station and / or the other terminal.

[0108] FIGURE 19 illustrates a block diagram showing a structure of a base station according to an embodiment of the disclosure.

[0109] As shown in FIG. 19, the base station of the present disclosure may include a transceiver 1910, a memory 1920, and a processor (or, a controller) 1930. The transceiver 1910, the memory 1920, and the processor (or controller) 1930 of the base station may operate according to a communication method of the base station described above. However, the components of the base station are not limited thereto. For example, the base station may include more or fewer components than those described in Fig. 19. In addition, the processor (or controller) 1930, the transceiver 1910, and the memory 1920 may be implemented as a single chip. Also, the processor (or controller) 1930 may include at least one processor.

[0110] The transceiver 1910 collectively refers to a base station receiver and a base station transmitter, and may transmit / receive a signal to / from a terminal, another base station, and / or a core network function(s) (or entity(s)). The signal transmitted or received to or from the base station may include control information and data. The transceiver 1910 may include a RF transmitter for up-converting and amplifying a frequency of a transmitted signal, and a RF receiver for amplifying low-noise and down-converting a frequency of a received signal. However, this is only an example of the transceiver 1910 and components of the transceiver 1910 are not limited to the RF transmitter and the RF receiver.

[0111] Also, the transceiver 1910 may receive and output, to the processor (or controller) 1930, a signal through a wireless channel, and transmit a signal output from the processor (or controller) 1930 through the wireless channel.

[0112] The memory 1920 may store a program and data required for operations of the base station. Also, the memory 1920 may store control information or data included in a signal obtained by the base station. The memory 1920 may be a storage medium, such as ROM, RAM, a hard disk, a CD-ROM, and a DVD, or a combination of storage media.

[0113] The processor (or controller) 1930 may control a series of processes such that the base station operates as described above. For example, the processor (or controller) 1930 may receive a data signal and / or a control signal, and the processor (or controller) 1930 may determine a result of receiving the signal transmitted by the terminal and / or the core network function.

[0114] Accordingly, the present disclosure provides various advantages. The present disclosure reduces system and signalling overhead in performing RRC functions by distributing the RRC functions over different units so that each can operate independently. For example, if the MAC layer has a configuration change, it needs to inform the RRC layer about the changes, and then the RRC layer shall update the configuration changes at MAC over the air. However, as per the present disclosure, the MAC layer can directly send a MAC layer configuration to update its values to the UE without requiring communication over multiple nodes and then sending a Layer 3 message. Accordingly, system and signalling overhead at the network side and processing overhead at the UE side are significantly reduced, since all layers need not be involved in configuration and control processing. Further, the present disclosure helps in avoiding delayed handovers or failures due to handovers as they are localized per layer. Further, the present disclosure also reduces latencies in the system.

[0115] According to an embodiment of the disclosure, a method for reconfiguring a radio resource control (RRC) layer in a wireless communication network comprises: assigning (701) each of a plurality of functions associated with the RRC layer to at least one of a RRC sub-layer of a plurality of RRC sub-layers, wherein the plurality of RRC sub-layers include an RRC-L1 layer, an RRC-L2 layer, and an RRC-L3 layer; mapping (703) each of the plurality of assigned functions to at least one of a plurality of channels for communication using the corresponding at least one RRC sub-layer; and defining (705) a message format for at least one of the plurality of RRC sub-layers for communication using the at least one of the plurality of channels.

[0116] According to an embodiment of the disclosure, the method further comprises: assigning the RRC-L1 layer to a lower layer unit (LLU) of the wireless communication network; assigning the RRC-L2 layer to a distributed unit (DU) of the wireless communication network; and assigning the RRC-L3 layer to a centralized unit (CU) of the wireless communication network.

[0117] According to an embodiment of the disclosure, wherein mapping each of the plurality of assigned functions comprises: mapping one or more of the plurality of functions assigned to the RRC-L1 layer to a physical channel comprising a Physical Broadcast channel (PBCH), a Physical downlink Shared Channel (PDSCH), and a Physical downlink Control Channel (PDCCH); mapping one or more of the plurality of functions assigned to the RRC-L2 layer to one or more of the physical channel, a transport channel comprising a Downlink shared channel (DL-SCH), and a logical channel comprising a Common control channel (CCCH), a Dedicated Common control channel (DCCH), and a Dedicated traffic channel (DTCH); and mapping one or more of the plurality of functions assigned to the RRC-L3 layer to one or more of the physical channel, a transport channel comprising the DL-SCH, a Paging Channel (PCH), and a Broadcast Channel (BCH), and a logical channel comprising the CCCH, the DCCH, the DTCH, a Broadcast common control channel (BCCH), and a Paging control channel (PCCH).

[0118] According to an embodiment of the disclosure, wherein the defining the message format comprises: defining a first message format for the RRC-L1 layer, wherein the first message format comprises a Downlink Control Information (DCI) bit (X_n) for identifying one of a data packet and an RRC-L1 packet transmitted by the RRC-L1 layer.

[0119] According to an embodiment of the disclosure, wherein the RRC-L1 packet is one of a control packet and an information packet transmitted by the RRC-L1 layer.

[0120] According to an embodiment of the disclosure, wherein the first message format comprises a plurality of bits identifying a type of message transmitted by the RRC-L1 layer, wherein the transmitted message belongs to one or more of the plurality of functions assigned to the RRC-L1 layer.

[0121] According to an embodiment of the disclosure, wherein the defining the message format comprises: defining a second message format for the RRC-L2 layer, wherein the second message format comprises a Packet Data Unit (PDU) bit for identifying one of a data packet and an RRC-L2 packet transmitted by the RRC-L2 layer.

[0122] According to an embodiment of the disclosure, wherein the RRC-L2 packet is one of a Packet Data Convergence Protocol (PDCP) control packet and an information packet.

[0123] According to an embodiment of the disclosure, wherein the second message format comprises a plurality of bits identifying a type of message transmitted by the RRC-L2 layer, wherein the transmitted message belongs to one or more of the plurality of functions assigned to the RRC-L2 layer.

[0124] According to an embodiment of the disclosure, wherein the defining the message format comprises: defining a second message format for the RRC-L2 layer, wherein the second message format is defined in a Medium Access Control (MAC) control element (CE).

[0125] According to an embodiment of the disclosure, wherein the MAC CE comprises a logical channel identifier (LCID) for identifying a type of message transmitted by the RRC-L2 layer, wherein the transmitted message belongs to one or more of the plurality of functions assigned to the RRC-L2 layer.

[0126] According to an embodiment of the disclosure, the method further comprises: broadcasting system information (SI) from a network function (NF) to a user equipment (UE) associated with the wireless communication network, using the plurality of RRC sub-layers, wherein a minimum and / or on demand SI information is broadcasted by the RRC-L1 layer to the UE and one or more system information messages are broadcasted by the RRC-L3 layer to the UE.

[0127] According to an embodiment of the disclosure, the method further comprises: performing an RRC connection setup process between a user equipment (UE) and a gNB associated with the wireless communication network, using the plurality of RRC sub-layers, wherein performing the RRC connection setup process comprises: transmitting one of a master information block (MIB) message and a master information block (SIB) message from the RRC-L1 layer to the UE; receiving, by the RRC-L3 layer, an uplink layer 3 (UL-L3) message requesting the RRC connection setup from the UE via the RRC-L2 layer; transmitting, by the RRC-L3 layer, an RRC setup response message to the UE via the RRC-L2 layer; transmitting an RRC-L2 setup message from the RRC-L2 layer to the UE; transmitting an RRC-L1 setup message from the RRC-L1 layer to the UE; and receiving, by the RRC-L3 layer, an RRC setup complete notification from the UE via the RRC-L2 layer.

[0128] According to an embodiment of the disclosure, the method further comprises: performing an RRC connection setup process between a user equipment (UE) and a gNB associated with the wireless communication network, using the plurality of RRC sub-layers, wherein performing the RRC connection setup process comprises: transmitting one of a MIB message and a SIB message from the RRC-L1 layer to the UE; receiving, by the RRC-L3 layer, an uplink layer 3 (UL-L3) message requesting the RRC connection setup from the UE; transmitting, by the RRC-L3 layer, an RRC setup request message to the UE via the RRC-L2 layer; transmitting an RRC-L23 setup message from the RRC-L3 layer to the UE; transmitting an RRC-L2 setup message from the RRC-L2 layer to the UE; transmitting an RRC-L1 setup message from the RRC-L1 layer to the UE; and receiving, by the RRC-L3 layer, an RRC setup complete notification from the UE.

[0129] According to an embodiment of the disclosure, a system for reconfiguring a radio resource control (RRC) layer in a wireless communication network comprises: a memory (606); and a processor (602) coupled to the memory (606) and configured to: assign each of a plurality of functions associated with the RRC layer to at least one of a RRC sub-layer of a plurality of RRC sub-layers, wherein the plurality of RRC sub-layers include an RRC-L1 layer, an RRC-L2 layer, and an RRC-L3 layer; map each of the plurality of assigned functions to at least one of a plurality of channels for communication using the corresponding at least one RRC sub-layer; and define a message format for at least one of the plurality of RRC sub-layers for communication using the at least one of the plurality of channels.

[0130] According to an embodiment of the disclosure, wherein the processor is further configured to: assign the RRC-L1 layer to a lower layer unit (LLU) of the wireless communication network; assign the RRC-L2 layer to a distributed unit (DU) of the wireless communication network; and assign the RRC-L3 layer to a centralized unit (CU) of the wireless communication network.

[0131] According to an embodiment of the disclosure, wherein the processor is configured to map each of the plurality of assigned functions by: mapping one or more of the plurality of functions assigned to the RRC-L1 layer to a physical channel comprising a Physical Broadcast channel (PBCH), a Physical downlink Shared Channel (PDSCH), and a Physical downlink Control Channel (PDCCH); mapping one or more of the plurality of functions assigned to the RRC-L2 layer to the physical channel, a transport channel comprising a Downlink shared channel (DL-SCH), and a logical channel comprising a Common control channel (CCCH), a Dedicated Common control channel (DCCH), and a Dedicated traffic channel (DTCH); and mapping one or more of the plurality of functions assigned to the RRC-L3 layer to the physical channel, a transport channel comprising the DL-SCH, a Paging Channel (PCH), and a Broadcast Channel (BCH), and a logical channel comprising the CCCH, the DCCH, the DTCH, a Broadcast common control channel (BCCH), and a Paging control channel (PCCH).

[0132] According to an embodiment of the disclosure, wherein the processor is configured to define the message format by: defining a first message format for the RRC-L1 layer, wherein the first message format comprises a Downlink Control Information (DCI) bit (X_n) for identifying one of a data packet and an RRC-L1 packet transmitted by the RRC-L1 layer.

[0133] According to an embodiment of the disclosure, wherein the RRC-L1 packet is one of a control packet and an information packet transmitted by the RRC-L1 layer.

[0134] According to an embodiment of the disclosure, wherein the first message format comprises a plurality of bits identifying a type of message transmitted by the RRC-L1 layer, wherein the transmitted message belongs to one or more of the plurality of functions assigned to the RRC-L1 layer.

[0135] According to an embodiment of the disclosure, wherein the processor is configured to define the message format by: defining a second message format for the RRC-L2 layer, wherein the second message format comprises a Packet Data Unit (PDU) bit for identifying one of a data packet and an RRC-L2 packet transmitted by the RRC-L2 layer.

[0136] According to an embodiment of the disclosure, wherein the RRC-L2 packet is one of a Packet Data Convergence Protocol (PDCP) control packet and an information packet.

[0137] According to an embodiment of the disclosure, wherein the second message format comprises a plurality of bits identifying a type of message transmitted by the RRC-L2 layer, wherein the transmitted message belongs to one or more of the plurality of functions assigned to the RRC-L2 layer.

[0138] According to an embodiment of the disclosure, wherein the processor is configured to define the message format by: defining a second message format for the RRC-L2 layer, wherein the second message format is defined in a Medium Access Control (MAC) control element (CE).

[0139] According to an embodiment of the disclosure, wherein the MAC CE comprises a logical channel identifier (LCID) for identifying a type of message transmitted by the RRC-L2 layer, wherein the transmitted message belongs to one or more of the plurality of functions assigned to the RRC-L2 layer.

[0140] According to an embodiment of the disclosure, wherein the processor is further configured to: broadcast system information (SI) from a network function (NF) to a user equipment (UE) associated with the wireless communication network, using the plurality of RRC sub-layers, wherein a minimum and / or on demand SI information is broadcasted by the RRC-L1 layer to the UE and one or more system information messages are broadcasted by the RRC-L3 layer to the UE.

[0141] According to an embodiment of the disclosure, wherein the processor is further configured to: perform an RRC connection setup process between a user equipment (UE) and a g-NB associated with the wireless communication network, using the plurality of RRC sub-layers, wherein performing the RRC connection setup process comprises: transmitting one of a master information block (MIB) message and a master information block (SIB) message from the RRC-L1 layer to the UE; receiving, by the RRC-L3 layer, an uplink layer 3 (UL-L3) message requesting the RRC connection setup from the UE via the RRC-L2 layer; transmitting, by the RRC-L3 layer, an RRC setup response message to the UE via the RRC-L2 layer; transmitting an RRC-L2 setup message from the RRC-L2 layer message to the UE; transmitting an RRC-L1 setup message from the RRC-L1 layer message to the UE; and receiving, by the RRC-L3 layer, an RRC setup complete notification from the UE via the RRC-L2 layer.

[0142] According to an embodiment of the disclosure, wherein the processor is further configured to: perform an RRC connection setup process between a user equipment (UE) and a network function (NF) associated with the wireless communication network, using the plurality of RRC sub-layers, wherein performing the RRC connection setup process comprises: transmitting a MIB / SIB message from the RRC-L1 layer to the UE; receiving, by the RRC-L3 layer, an uplink layer 3 (UL-L3) message requesting the RRC connection setup from the UE; transmitting, by the RRC-L3 layer, an RRC setup request message to the UE via the RRC-L2 layer; transmitting an RRC-L23 setup message from the RRC-L3 layer to the UE; transmitting an RRC-L2 setup message from the RRC-L2 layer to the UE; transmitting an RRC-L1 setup message from the RRC-L1 layer to the UE; and receiving, by the RRC-L3 layer, an RRC setup complete notification from the UE.

[0143] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skilled in the art to which this invention belongs. The system, methods, and examples provided herein are illustrative only and not intended to be limiting.

[0144] Benefits, other advantages, and solutions to problems have been described above with regard to specific embodiments. However, the benefits, advantages, solutions to problems, and any component(s) that may cause any benefit, advantage, or solution to occur or become more pronounced are not to be construed as a critical, required, or essential feature or component of any or all the claims.

[0145] While specific language has been used to describe the present subject matter, any limitations arising on account thereto, are not intended. As would be apparent to a person in the art, various working modifications may be made to the method in order to implement the inventive concept as taught herein. The drawings and the foregoing description give examples of embodiments. Those skilled in the art will appreciate that one or more of the described elements may well be combined into a single functional element. Alternatively, certain elements may be split into multiple functional elements. Elements from one embodiment may be added to another embodiment.

Claims

1.A method performed by a user equipment (UE) in a wireless communication system, the method comprising:identifying a plurality of radio resource control (RRC) sublayers including at least two of a first RRC sublayer, a second RRC sublayer, or a third RRC sublayer; andperforming an operation for each of the plurality of RRC sublayers.2.The method of claim 1, wherein the first RRC sublayer corresponds to a lower layer unit (LLU) of a base station,wherein the second RRC sublayer corresponds to a distributed unit (DU) of the base station, andwherein the third RRC sublayer corresponds to a central unit (CU) of the base station.3.The method of claim 2, wherein a first operation for the first RRC sublayer comprises a first function associated with at least one of a physical broadcast channel (PBCH), a physical downlink shared channel (PDSCH), or a physical downlink control channel (PDCCH).4.The method of claim 3, wherein the first function comprises at least one of a master information block (MIB) related function, a system information block (SIB) related function, a configuration control, a measurement configuration, a measurement gap management, a carrier aggregation (CA) cell management, a dual connectivity (DC) cell management, or a self organizing network (SON) management.5.The method of claim 2, wherein a second operation for the second RRC sublayer comprises a second function associated with at least one of a downlink shared channel (DL-SCH), a common control channel (CCCH), a dedicated control channel (DCCH), or a dedicated traffic channel (DTCH).6.The method of claim 5, wherein the second function comprises at least one of a measurement and mobility control, a connection control, a quality of service (QoS) configuration control, a data radio bearer (DRB) configuration control, a measurement and mobility control, a layer 1 / layer 2 measurement control, a non-access stratum (NAS) message transfer, a carrier aggregation (CA) cell management, a dual connectivity (DC) cell management, or a self organizing network (SON) management.7.The method of claim 2, wherein a third operation for the third RRC sublayer comprises a third function associated with at least one of a broadcast channel (BCH), a downlink shared channel (DL-SCH), a paging channel (PCH), a broadcast control channel (BCCH), a common control channel (CCCH), a dedicated control channel (DCCH), a dedicated traffic channel (DTCH), or a paging control channel (PCCH).8.The method of claim 7, wherein the third function comprises at least one of a commercial mobile alert system (CMAS), an earthquake and tsunami warning system (ETWS), a higher layer system information block (SIB) related function, a connection control, an access barring, a public land mobile network (PLMN) configuration control, a tracking area code (TAC) configuration control, a layer 3 measurement and mobility control, a non-access stratum (NAS) message transfer, a carrier aggregation (CA) cell management, a dual connectivity (DC) cell management, or a self organizing network (SON) management.9.A user equipment (UE) in a wireless communication system, the UE comprising:a transceiver; anda controller coupled with the transceiver and configured to:identify a plurality of radio resource control (RRC) sublayers including at least two of a first RRC sublayer, a second RRC sublayer, or a third RRC sublayer, andperform an operation for each of the plurality of RRC sublayers.10.The UE of claim 9, wherein the first RRC sublayer corresponds to a lower layer unit (LLU) of a base station,wherein the second RRC sublayer corresponds to a distributed unit (DU) of the base station, andwherein the third RRC sublayer corresponds to a central unit (CU) of the base station.11.The UE of claim 10, wherein a first operation for the first RRC sublayer comprises a first function associated with at least one of a physical broadcast channel (PBCH), a physical downlink shared channel (PDSCH), or a physical downlink control channel (PDCCH).12.The UE of claim 11, wherein the first function comprises at least one of a master information block (MIB) related function, a system information block (SIB) related function, a configuration control, a measurement configuration, a measurement gap management, a carrier aggregation (CA) cell management, a dual connectivity (DC) cell management, or a self organizing network (SON) management.13.The UE of claim 10, wherein a second operation for the second RRC sublayer comprises a second function associated with at least one of a downlink shared channel (DL-SCH), a common control channel (CCCH), a dedicated control channel (DCCH), or a dedicated traffic channel (DTCH).14.The UE of claim 12, wherein the second function comprises at least one of a measurement and mobility control, a connection control, a quality of service (QoS) configuration control, a data radio bearer (DRB) configuration control, a measurement and mobility control, a layer 1 / layer 2 measurement control, a non-access stratum (NAS) message transfer, a carrier aggregation (CA) cell management, a dual connectivity (DC) cell management, or a self organizing network (SON) management.15.The UE of claim 10, wherein a third operation for the third RRC sublayer comprises a third function associated with at least one of a broadcast channel (BCH), a downlink shared channel (DL-SCH), a paging channel (PCH), a broadcast control channel (BCCH), a common control channel (CCCH), a dedicated control channel (DCCH), a dedicated traffic channel (DTCH), or a paging control channel (PCCH), andwherein the third function comprises at least one of a commercial mobile alert system (CMAS), an earthquake and tsunami warning system (ETWS), a higher layer system information block (SIB) related function, a connection control, an access barring, a public land mobile network (PLMN) configuration control, a tracking area code (TAC) configuration control, a layer 3 measurement and mobility control, a non-access stratum (NAS) message transfer, a carrier aggregation (CA) cell management, a dual connectivity (DC) cell management, or a self organizing network (SON) management.

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