First radio access network node, user equipment and methods thereof

Abstract

This invention provides a first radio access network node, a user equipment (UE), and a method thereof. The first radio access network (RAN) node is associated with a first radio access technology (RAT). The first RAN node includes: components for communicating with a second RAN node associated with a second RAT; components for providing dual connectivity to the UE using both the first and second RATs, wherein the first RAT is different from the second RAT; and components for receiving information indicating that the UE supports split bearers for dual connectivity. The split bearers include a first type of split bearer split at the first RAN node and a second type of split bearer split at the second RAN node, wherein a first packet data convergence protocol (PDCP) function is used for the first type of split bearer in the first RAN node, and the first PDCP function is also used for the second type of split bearer in the second RAN node.

Description

[0001] This application is a divisional application of Chinese invention patent application filed on January 24, 2018, with application number 201880039415.6 and entitled "Radio Access Network Node, Radio Terminal and Method Thereof". Technical Field

[0002] This invention relates to radio communication systems, and more particularly to communication (multi-connection operation) of a radio terminal simultaneously using multiple cells employing different radio access technologies (RATs) from different radio stations. Background Technology

[0003] The 3rd Generation Partnership Project (3GPP) has standardized fifth-generation mobile communication systems (5G) to make them a commercial reality in 2020 or later. 5G is expected to be realized through continued enhancements / evolution of LTE and LTE-Advanced, as well as innovative enhancements / evolutions through the introduction of new 5G air interfaces (i.e., new radio access technologies (RATs)). These new RATs, for example, support frequency bands higher than those supported by LTE / LTE-Advanced and their continued evolution (e.g., 6 GHz or lower). For instance, the new RATs support centimeter wave bands (10 GHz or higher) and millimeter wave bands (30 GHz or higher).

[0004] In this specification, the fifth-generation mobile communication system is referred to as a 5G system or a Next-Gen (NG) system. The new Radio Access Network (RAN) used in the 5G system is referred to as New Radio (NR), 5G RAT, or NG RAT. The new Radio Access Network (RAN) used in the 5G system is referred to as 5G-RAN or NextGen RAN (NG RAN). The new base station in the 5G-RAN is referred to as NR NodeB (NRNB) or gNodeB (gNB). The new core network used in the 5G system is referred to as the 5G Core Network (5G-CN or 5GC) or NextGenCore (NG Core). The radio terminal capable of connecting to the 5G system (i.e., User Equipment (UE)) is referred to as 5GUE or NextGen UE (NG UE), or simply UE. As standardization efforts progress, official names for the RAT, UE, radio access network, core network, network entities (nodes), and protocol layers used in the 5G system will be determined in the future.

[0005] Unless otherwise specified, the term "LTE" as used in this specification includes enhancements / evolutions of LTE and LTE-Advanced to provide interoperability with 5G systems. Enhancements / evolutions of LTE and LTE-Advanced for interoperability with 5G systems are referred to as LTE-Advanced Pro, LTE+, or enhanced LTE (eLTE). Furthermore, unless otherwise specified, terms related to LTE network and logical entities, such as "Evolved Packet Core (EPC)," "Mobility Management Entity (MME)," "Serving Gateway (S-GW)," and "Packet Data Network (PDN) Gateway (P-GW)," as used in this specification include their enhancements / evolutions to provide interoperability with 5G systems. Enhanced EPC, enhanced MME, enhanced S-GW, and enhanced P-GW are referred to, for example, enhanced EPC (ePEC), enhanced MME (eMME), enhanced S-GW (eS-GW), and enhanced P-GW (eP-GW).

[0006] In LTE and LTE-Advanced, to achieve Quality of Service (QoS) and packet routing, bearers for each QoS level and for each PDN connection are used in both the RAN (i.e., Evolved Universal Terrestrial RAN (E-UTRAN)) and the core network (i.e., EPC). Specifically, in the bearer-based QoS (or bearer-specific QoS) concept, one or more Evolved Packet System (EPS) bearers are configured between the P-GW in the UE and EPC, and multiple Service Data Streams (SDFs) with the same QoS level are transmitted through one EPS bearer that satisfies that QoS. An SDF is one or more packet streams that match an SDF template (i.e., a packet filter) based on Policy and Charging Control (PCC) rules. To achieve packet routing, each packet to be transmitted through the EPS bearer contains information to identify which bearer (i.e., the General Packet Radio Service (GPRS) Tunneling Protocol (GTP) tunnel) the packet is associated with.

[0007] In contrast, regarding 5G systems, the following is discussed: Although radio bearers can be used in NG-RAN, they are not used in 5GC or in the interface between 5GC and NG-RAN (see Non-Patent Literature 1). Specifically, PDU flows are defined instead of EPS bearers, and one or more SDFs are mapped to one or more PDU flows. The PDU flows between the user plane terminal entities (i.e., the entities corresponding to the P-GW in EPC) in the 5G UE and NG Core correspond to EPS bearers in the EPS bearer-based QoS concept. PDU flows correspond to the finest granularity of packet forwarding and processing in the 5G system. That is, the 5G system adopts a flow-based QoS (or flow-specific QoS) concept instead of a bearer-based QoS concept. In the flow-based QoS concept, QoS is processed for each PDU flow. In the QoS framework of the 5G system, PDU flows are identified by the PDU flow ID included in the header of the Service Data Unit encapsulating the tunnel of the NG3 interface. The NG3 interface is the user plane interface between 5GC and gNB (i.e., NG-RAN). The association between a 5G UE and the data network is called a "PDU session." The term "PDU session" corresponds to the term "PDN connection" in LTE and LTE-Advanced. Multiple PDU streams can be configured within a single PDU session.

[0008] PDU flows are also known as "QoS flows." QoS flows represent the finest granularity of QoS processing in 5G systems. User plane services within a PDU session that share the same NG3 tag value correspond to QoS flows. The NG3 tag corresponds to the PDU flow ID mentioned above, and is also referred to as the QoS flow ID or flow identifier (FII).

[0009] Figure 1 This illustrates the basic architecture of a 5G system. The UE establishes one or more Signaling Radio Bearers (SRBs) and one or more Data Radio Bearers (DRBs) with the gNB. The 5GC and gNB establish the control plane interface and user plane interface used by the UE. The control plane interface between the 5GC and gNB (i.e., the RAN) is called the NG2 interface or NG-c interface and is used for the transmission of Non-Access Stratum (NAS) information and control information (e.g., NG2 AP information elements) between the 5GC and gNB. The user plane interface between the 5GC and gNB (i.e., the RAN) is called the NG3 interface or NG-u interface and is used for transmitting packets of one or more PDU streams in the UE's PDU session.

[0010] Notice, Figure 1 The architecture shown is just one of the 5G architecture options (or deployment scenarios). Figure 1The architecture shown is referred to as "Standalone NR (in the NextGen System)" or "Option 2". 3GPP also discussed several network architectures used for multi-connectivity operations employing E-UTRA and NR radio access technologies. Multi-connectivity operations using E-UTRA and NR radio access technologies are referred to as Multiple RAT Dual Connectivity (MR-DC). MR-DC is a dual connectivity between E-UTRA and NR nodes.

[0011] In MR-DC, one of the E-UTRA node (i.e., eNB) and the NR node (i.e., gNB) operates as the primary node (MN), while the other operates as the secondary node (SN), and at least the MN is connected to the core network. The MN provides the UE with one or more primary cell groups (MCG) cells, while the SN provides the UE with one or more secondary cell groups (SCG) cells. MR-DC includes "MRDC utilizing EPC" and "MRDC utilizing 5GC".

[0012] MRDC utilizing EPC includes E-UTRA-NR dual connectivity (EN-DC). In EN-DC, the UE connects to an eNB operating as an MN and a gNB operating as an SN. Furthermore, the eNB (i.e., the primary eNB) connects to the EPC, while the gNB (i.e., the secondary gNB) connects to the primary eNB via an X2 interface.

[0013] MRDC utilizing 5GC includes NR-E-UTRA dual connectivity (NE-DC) and E-UTRA-NR dual connectivity (NG-EN-DC). In NE-DC, the UE connects to a gNB operating as an MN and an eNB operating as an SN. The gNB (i.e., the primary gNB) is connected to the 5GC, and the eNB (i.e., the secondary eNB) is connected to the primary gNB via the Xn interface. On the other hand, in NG-EN-DC, the UE connects to an eNB operating as an MN and a gNB operating as an SN. The eNB (i.e., the primary eNB) is connected to the 5GC, and the gNB (i.e., the secondary gNB) is connected to the primary eNB via the Xn interface.

[0014] Figure 2 , 3 Figures 4 and 5 show the network structures of the three DC types mentioned above: EN-DC, NE-DC, and NG-EN-DC, respectively. Figure 5 This shows the SRB and DRB supported by these three DC types. Note that... Figure 5 This shows the bearer types to be supported in 3GPP Release 15, which is currently under discussion in 3GPP. Therefore, the bearer types supported by the three DC types can be compared with... Figure 5 The bearer types shown are different.

[0015] The MCG SRB is an SRB established between the UE and the MN. Radio Resource Control Protocol Data Units (RRC PDUs) generated by the SN can be transmitted to the UE via the MN and the MCG SRB. Optionally, the UE can establish an SRB (SCG SRB) with the SN to directly transmit the RRC PDUs used by the SN between the UE and the SN. The MCG splits the SRB, which makes it possible to replicate the RRC PDUs generated by the MN.

[0016] MCG bearers are user plane bearers where the radio protocol resides only within the MCG. MCG split bearers are user plane bearers where the radio protocol splits at MN and belongs to both the MCG and SCG. SCG bearers are user plane bearers where the radio protocol resides only within the SCG. SCG split bearers are user plane bearers where the radio protocol splits at SN and belongs to both the SCG and MCG.

[0017] Note that the Layer 2 functionality of gNB(NR) differs from that of eNB(LTE). For example, gNB(NR) Layer 2 comprises four sublayers: Serving Data Adaptive Protocol (SDAP) sublayer, Packet Data Convergence Protocol (PDCP) sublayer, Radio Link Control (RLC) sublayer, and Medium Access Control (MAC) sublayer. In the NR PDCP sublayer, the PDCP sequence number (SN) used by the DRB is 12 or 18 bits in size, which is a subset of the possible values ​​of the LTE PDCP SN size (i.e., 7, 12, 15, or 18 bits). However, in the case of an eNB(LTE) connected to a 5GC, eNB(LTE) Layer 2 includes the SDAP sublayer.

[0018] 3GPP also discussed the introduction of unified split bearers. The purpose of introducing unified split bearers is to use the same protocols, structures, and processes for both MCG split bearers and SCG split bearers as much as possible, thereby simplifying specifications and UE implementation. As a specific means of this introduction, a common (single) PDCP layer has been proposed (see Non-Patent Document 1). The common PDCP layer supports both MCG split bearers and SCG split bearers. For example, the common PDCP layer can be the same as the PDCP layer used for NR standalone network operation (NR PDCP layer).

[0019] Non-Patent Document 1 proposes that, in the absence of movement of the PDCP termination point, handover between split bearers and non-split bearers should be possible without the need for re-establishment of PDCP. Non-Patent Document 1 further proposes that a PDCP version identical to the one already used for split bearers when the UE is only operating in LTE should be configurable, enabling handover to and from split bearers without PDCP re-establishment due to protocol changes.

[0020] Existing technical documents

[0021] Non-patent literature

[0022] [Non-Patent Literature 1] 3GPP Tdoc R2-1704414, Ericsson, "On the different bearer options", 3GPP TSG-RAN WG2 Meeting #98, May 2017 Summary of the Invention

[0023] The problem the invention aims to solve

[0024] As mentioned above, Non-Patent Document 1 proposes a common (single) PDCP layer supporting both MCG split bearers and SCG split bearers. This common PDCP layer can be referred to as a unified PDCP layer. However, it is unclear how a common (or unified) PDCP layer should be implemented in radio communication networks (e.g., 3GPP networks).

[0025] One of the objectives of the embodiments disclosed herein is to provide apparatus, methods, and procedures for assisting in the implementation of a common (or unified) PDCP layer in radio communication networks. It should be noted that this objective is only one of the objectives of the embodiments disclosed herein. Other objectives or problems, as well as novel features, will become apparent from the following description and accompanying drawings.

[0026] Solution for solving the problem

[0027] In a first aspect, the primary RAN node associated with the primary RAT includes a memory and at least one processor coupled to the memory. The at least one processor is configured to communicate with a secondary RAN node associated with the secondary RAT and to provide dual connectivity to the radio terminal using both the primary RAT and the secondary RAT. The at least one processor is further configured to: in response to receiving terminal capability information from the radio terminal or the core network indicating that the radio terminal supports split bearers, use a Packet Data Convergence Protocol (PDCP) entity for the primary cell group split bearer used by the radio terminal, the PDCP entity providing unified PDCP functionality. The unified PDCP functionality is used for both the primary cell group split bearer and the secondary cell group split bearer. The primary cell group split bearer is a user plane bearer that is split at the primary RAN node and belongs to both the primary cell group provided by the primary RAN node and the secondary cell group provided by the secondary RAN node. The secondary cell group split bearer is a user plane bearer that is split at the secondary RAN node and belongs to both the secondary cell group and the primary cell group.

[0028] In a second aspect, the secondary RAN node configured to support the secondary RAT includes a memory and at least one processor coupled to the memory. The at least one processor is configured to communicate with the primary RAN node supporting the primary RAT and to provide dual connectivity to the radio terminal using both the primary and secondary RATs. The at least one processor is further configured to, upon receiving terminal capability information from the radio terminal or the core network indicating that the radio terminal supports split bearers, use a Packet Data Convergence Protocol (PDCP) entity for the secondary cell group split bearer used by the radio terminal, the PDCP entity providing unified PDCP functionality.

[0029] In a third aspect, the radio terminal includes at least one radio transceiver and at least one processor. The at least one radio transceiver is configured to communicate with both a primary radio access network (RAN) node associated with a primary radio access technology (RAT) and a secondary RAN node associated with a secondary RAT. The at least one processor is configured to perform dual connectivity using the primary RAT and the secondary RAT via the at least one radio transceiver. The at least one processor is configured to, in the case that the radio terminal supports split bearers, send terminal capability information indicating that the radio terminal supports split bearers to the primary RAN node. Furthermore, the at least one processor is also configured to, in the case that the radio terminal supports split bearers, use a Packet Data Convergence Protocol (PDCP) entity for the primary cell group split bearers used by the radio terminal, the PDCP entity providing unified PDCP functionality.

[0030] In the fourth aspect, the methods used by the primary RAN node associated with the primary RAT include:

[0031] (a) Communicates with the secondary RAN node associated with the primary RAT and provides dual connectivity to the radio terminal using both the primary RAT and the secondary RAT; and

[0032] (b) In response to receiving terminal capability information from the radio terminal or core network indicating that the radio terminal supports split bearers, a Packet Data Convergence Protocol (PDCP) entity is used for the primary cell group split bearer used by the radio terminal, the PDCP entity providing unified PDCP functionality.

[0033] In the fifth aspect, the methods used to configure secondary RAN nodes to support secondary RATs include:

[0034] (a) Communicate with the primary RAN node supporting the primary RAT and provide dual connectivity to radio terminals using both the primary RAT and the secondary RAT; and

[0035] (b) When the primary RAN node receives terminal capability information from the radio terminal or the core network indicating that the radio terminal supports split bearers, a Packet Data Convergence Protocol (PDCP) entity is used for the secondary cell group split bearers used by the radio terminal, which provides unified PDCP functionality.

[0036] In the sixth aspect, the methods used by the radio terminal include:

[0037] (a) Dual connectivity using the primary RAT and the secondary RAT is performed via a radio transceiver configured to communicate with both a primary radio access network (RAN) node associated with the primary radio access technology (RAT) and a secondary RAN node associated with the secondary RAT.

[0038] (b) If the radio terminal supports split bearers, send terminal capability information indicating that the radio terminal supports split bearers to the primary RAN node; and

[0039] (c) Where the radio terminal supports split bearers, a Packet Data Convergence Protocol (PDCP) entity is used for the primary cell group split bearers used by the radio terminal, which provides unified PDCP functionality.

[0040] In a seventh aspect, the primary RAN node associated with the primary RAT includes a memory and at least one processor coupled to the memory. The at least one processor is configured to communicate with a secondary RAN node associated with the secondary RAT and to provide dual connectivity to the radio terminal using both the primary and secondary RATs. The at least one processor is also configured to, in the case that the radio terminal does not support split bearers, use a PDCP entity for providing first Packet Data Convergence Protocol (PDCP) functionality corresponding to the primary RAT for the primary cell group bearer used by the radio terminal. Furthermore, the at least one processor is configured to, in the case that the radio terminal supports split bearers, use a PDCP entity for providing unified PDCP functionality for the primary cell group bearer used by the radio terminal, regardless of whether dual connectivity is initiated for the radio terminal. The primary cell group bearer is a user plane bearer where the radio protocol resides only in the primary cell group.

[0041] In an eighth aspect, the radio terminal includes at least one radio transceiver and at least one processor. The at least one radio transceiver is configured to communicate with both a primary radio access network (RAN) node associated with a primary radio access technology (RAT) and a secondary RAN node associated with a secondary RAT. The at least one processor is configured to perform dual connectivity using the primary RAT and the secondary RAT via the at least one radio transceiver. The at least one processor is further configured to, in the case that the radio terminal does not support split bearers, use a PDCP entity for providing first packet data convergence protocol (PDCP) functionality corresponding to the primary RAT for the primary cell group bearer used by the radio terminal. Furthermore, the at least one processor is configured to, in the case that the radio terminal supports split bearers, use a PDCP entity for providing unified PDCP functionality for the primary cell group bearer used by the radio terminal, regardless of whether dual connectivity is initiated for the radio terminal.

[0042] In the ninth aspect, the methods used by the primary RAN node associated with the primary RAT include:

[0043] (a) Communicate with the secondary RAN node associated with the secondary RAT and provide dual connectivity to the radio terminal using the primary RAT and the secondary RAT;

[0044] (b) In the case that the radio terminal does not support split bearers, a PDCP entity is used for providing first packet data convergence protocol (PDCP) functionality corresponding to the primary RAT for the primary cell group bearer used by the radio terminal; and

[0045] (c) In the case that the radio terminal supports split bearer, regardless of whether dual connectivity is initiated for the radio terminal, a PDCP entity for providing unified PDCP functionality is used for the primary cell group bearer used by the radio terminal.

[0046] In the tenth aspect, the methods used in radio terminals include:

[0047] (a) Dual connectivity using the primary RAT and the secondary RAT is performed via a radio transceiver configured to communicate with both a primary radio access network (RAN) node associated with the primary radio access technology (RAT) and a secondary RAN node associated with the secondary RAT.

[0048] (b) In the case that the radio terminal does not support split bearers, a PDCP entity is used for providing first packet data convergence protocol (PDCP) functionality corresponding to the primary RAT for the primary cell group bearer used by the radio terminal; and

[0049] (c) In the case that the radio terminal supports split bearer, regardless of whether dual connectivity is initiated for the radio terminal, a PDCP entity for providing unified PDCP functionality is used for the primary cell group bearer used by the radio terminal.

[0050] In the eleventh aspect, the program includes instructions (software code) that, when loaded into a computer, cause the computer to perform the methods according to the fourth, fifth, sixth, ninth, or tenth aspects described above.

[0051] The effects of the invention

[0052] Based on the above aspects, devices, methods, and procedures can be provided to assist in implementing a common (or unified) PDCP layer in radio communication networks. Attached Figure Description

[0053] Figure 1 This is a diagram illustrating the basic architecture of a 5G system;

[0054] Figure 2 This is a diagram showing the network structure of EN-DC;

[0055] Figure 3 This is a diagram showing the network structure of NE-DC;

[0056] Figure 4 This is a diagram showing the network structure of NG-EN-DC;

[0057] Figure 5 This is a table showing the bearer types supported by the three DC types currently discussed in 3GPP;

[0058] Figure 6 This is a diagram illustrating an example of the structure of a radio communication network according to several embodiments;

[0059] Figure 7 This is a diagram illustrating the radio protocol architecture used for split bearers according to various embodiments;

[0060] Figure 8 This is a sequence diagram illustrating an example of a process for establishing an MCG splitting bearer according to a first embodiment;

[0061] Figure 9 This is a sequence diagram illustrating an example of a process for establishing an SCG splitting bearer according to a first embodiment;

[0062] Figure 10 This is a sequence diagram illustrating an example of an MR-DC initiation process involving the establishment of an MCG split bearer according to a second embodiment;

[0063] Figure 11 This is a sequence diagram illustrating an example of an MR-DC initiation process involving the establishment of an SCG bearer or an SCG split bearer according to a second embodiment;

[0064] Figure 12 This is a sequence diagram illustrating an example of the process for establishing an RRC connection and user plane bearer according to the fourth embodiment;

[0065] Figure 13 This is a sequence diagram illustrating an example of the process for establishing an RRC connection and user plane bearer according to the fourth embodiment;

[0066] Figure 14 This is a block diagram illustrating an example structure of a master node according to several embodiments;

[0067] Figure 15 This is a block diagram illustrating structural examples of a UE according to various embodiments; and

[0068] Figure 16 This is a block diagram illustrating an example structure of a core network node according to several embodiments. Detailed Implementation

[0069] The specific embodiments will now be described in detail with reference to the accompanying drawings. In all the drawings, the same or corresponding elements are represented by the same symbols, and repeated descriptions have been omitted for clarity.

[0070] The embodiments described below can be used individually, or two or more of these embodiments can be suitably combined with each other. These embodiments include novel features that differ from one another. Therefore, these embodiments help to achieve different purposes or solve different problems, and help to obtain different advantages.

[0071] The following description of the embodiments focuses primarily on 3GPP Multiple RAT Dual Connectivity (MR-DC) using E-UTRA and NR. However, these embodiments can be applied to other radio communication systems that support DC architectures using other different RATs.

[0072] First Embodiment

[0073] Figure 6 Examples of the structure of a radio communication network according to several embodiments, including this embodiment, are shown. Figure 6 In the example shown, the radio communication network includes a primary node (MN) 1, a secondary node (SN) 2, a UE 3, and a core network 4. Figure 6 The radio communication network shown supports multiple RAT dual connectivity (MR-DC). More specifically, one of MN 1 and SN 2 is an E-UTRA node (i.e., eNB), and the other is an NR node (i.e., gNB). At least MN 1 is connected to core network 4 via interface 601. SN 2 can also be connected to core network 4 via interface 604. In the case of MRDC using EPC, core network 4 is EPC, while in the case of MRDC using 5GC, core network 4 is 5GC. In the case of MRDC using EPC, interfaces 601 and 604 are S1 interfaces (i.e., S1-MME and S1-U), while in the case of MRDC using 5GC, interfaces 601 and 604 are NG interfaces (i.e., NG-c and NG-U or NG2 and NG3). MN 1 and SN 2 are connected to each other via interface 603. In the case of MRDC using EPC, interface 603 is an X2 interface, while in the case of MRDC using 5GC, interface 603 is an Xn interface.

[0074] Core network 4 includes one or more control plane (CP) nodes 5 and one or more user plane (UP) nodes 6. CP nodes 5 may also be referred to as Control Plane Network Functions (CP NFs). UP nodes 6 may be referred to as User Plane Network Functions (UP NFs). In the case of MRDC utilizing EPC, for example, one or more CP nodes 5 include MME and Policy and Charging Rules Function (PCRF), while one or more UP nodes 6 include S-GW and P-GW. In the case of MRDC utilizing 5GC, for example, one or more CP nodes 5 include Access and Mobility Management Functions (AMF), Session Management Functions (SMF), and Policy Control Functions (PCF), while one or more UP nodes 6 include User Plane Functions (UPFs).

[0075] UE 3 supports multiple RAT dual connectivity (MR-DC). Specifically, UE 3 supports multi-connectivity operation using E-UTRA and NR radio access technologies. In the following description, the RAT supported by MN 1 is referred to as the primary RAT, and the RAT supported by SN 2 is referred to as the secondary RAT. In other words, MN 1 and SN 2 are associated with the primary RAT and secondary RAT, respectively. In the cases of EN-DC and NG-EN-DC, MN 1 is the primary eNB, SN 2 is the secondary gNB, the primary RAT is E-UTRA, and the secondary RAT is NR (5G RAT). On the other hand, in the case of NE-DC, MN 1 is the primary gNB, SN 2 is the secondary eNB, the primary RAT is NR (5G RAT), and the secondary RAT is E-UTRA. UE 3 has the ability to communicate simultaneously with MN 1, which is associated with the primary RAT, and SN 2, which is associated with the secondary RAT. In other words, UE 3 has the ability to aggregate cells belonging to the primary cell group (MCG) provided by MN 1 with cells belonging to the secondary cell group (SCG) provided by SN 2. The MCG includes one or more cells provided from the primary RAT. The SCG includes one or more cells provided from the secondary RAT. The air interface 602 between MN 1 and UE 3 provides control plane connections (e.g., RRC connections) and user plane connections (e.g., user plane bearers). On the other hand, the air interface 605 between gNB 2 and UE 3 includes at least a user plane connection, but air interface 605 does not need to include a control plane connection.

[0076] Figure 7The radio protocol architecture used for the MCG split bearer and SCG split bearer according to this embodiment is shown. As explained above, the MCG split bearer is a user plane bearer where the radio protocol splits at MN 1 and belongs to both MCG and SCG. The SCG split bearer is a user plane bearer where the radio protocol splits at SN 2 and belongs to both SCG and MCG. Although EN-DC is assumed in this example, the radio protocol architecture used for the split bearers in NE-DC and NG-EN-DC is essentially the same, except that there is an SDAP layer above the unified PDCP layer. Figure 7 The architecture shown is the same.

[0077] like Figure 7 As shown, in this embodiment, a unified PDCP layer is used. The unified PDCP layer can also be referred to as a single or common PDCP layer. The unified PDCP layer can be used for both MCG split bearers and SCG split bearers. Figure 7 The unified PDCP entities 711 and 721, located on the transmitting sides of MN 1 and SN 2 respectively, are PDCP entities in the unified PDCP layer and provide unified PDCP functions corresponding to the unified PDCP layer. The unified PDCP functions are used for both MCG split bearers and SCG split bearers. The unified PDCP functions, or unified PDCP entities 711 and 721, can be implemented in various ways, such as those shown below.

[0078] In some implementations, the unified PDCP function can be a shared function of both the MN PDCP function (e.g., LTE PDCP function) corresponding to the primary RAT (e.g., E-UTRA) and the SN PDCP function (e.g., NR PDCP function) corresponding to the secondary RAT (e.g., NR). In other words, the unified PDCP function can be a common subset of the MN PDCP function (e.g., LTE PDCP function) and the SN PDCP function (e.g., NR PDCP function).

[0079] In some implementations, a unified PDCP function can be achieved by executing the MN PDCP function (e.g., NRPDCP function) corresponding to the primary RAT (e.g., NR) as one of the modes (or sub-modes) of the SN PDCP function (e.g., LTE PDCP function) corresponding to the secondary RAT (e.g., LTE).

[0080] In some implementations, a unified PDCP function can be achieved by executing the SN PDCP function (e.g., NRPDCP function) corresponding to the secondary RAT (e.g., NR) as one of the modes (or sub-modes) of the MN PDCP function (e.g., LTE PDCP function) corresponding to the primary RAT (e.g., LTE).

[0081] In some implementations, SN PDCP functions (e.g., NR PDCP functions) can be a subset of MN PDCP functions (e.g., LTE PDCP functions). In this case, the unified PDCP function can be the same as the SN PDCP function, or a subset of the SN PDCP function.

[0082] In some implementations, the MN PDCP function (e.g., the LTE PDCP function) can be a subset of the SN PDCP function (e.g., the NR PDCP function). In this case, the unified PDCP function can be the same as the MN PDCP function, or a subset of the MN PDCP function.

[0083] In some implementations, unified PDCP entities 711 and 721 can be implemented in the following way: the MNPDCP entity of MN 1 (e.g., the LTE PDCP entity) has a configuration that is at least partially common to (or the same as) the configuration of the SN PDCP entity of SN 2 (e.g., the NR PDCP entity).

[0084] In some implementations, unified PDCP entities 711 and 721 can be implemented in the following way: the SNPDCP entity of SN 2 (e.g., the LTE PDCP entity) has a configuration that is at least partially common to (or the same as) the configuration of the MN PDCP entity of MN 1 (e.g., the NR PDCP entity).

[0085] In some implementations, a unified PDCP layer can be implemented in the following way: the MN PDCP layer (e.g., the LTE PDCP layer) performs the functions of the SN PDCP layer (e.g., the NR PDCP layer).

[0086] In some implementations, a unified PDCP layer can be implemented in the following way: the SN PDCP layer (e.g., the LTE PDCP layer) performs the functions of the MN PDCP layer (e.g., the NR PDCP layer).

[0087] In some implementations, in order to provide unified PDCP functionality, an SN PDCP (e.g., NR PDCP) layer module that operates as an upper (or sub) layer of the MN PDCP (e.g., LTE PDCP) layer can be located in MN 1.

[0088] In some implementations, in order to provide unified PDCP functionality, an MN PDCP (e.g., NR PDCP) layer module that operates as an upper (or sub) layer of the SN PDCP (e.g., LTE PDCP) layer can be located in SN 2.

[0089] In some implementations, MeNB 1, SgNB 2 and UE 3 can each prepare a PDCP entity that provides unified PDCP functionality by establishing, re-establishing or reconfiguring a PDCP entity with both MNPDCP and SN PDCP functionality, or by switching the mode (or sub-mode) of the PDCP entity.

[0090] MN RLC entity 712, which serves as the RLC entity for the MCG split bearer located in MN 1, receives PDCP PDUs from the unified PDCP entity 711 located in MN 1 and provides the RLC PDUs to MN MAC entity 714. Conversely, MN RLC entity 713, which serves as the RLC entity for the SCG split bearer located in MN 1, receives PDCP PDUs from the unified PDCP entity 721 located in SN 2 and provides the RLC PDUs to MN MAC entity 714. MN MAC entity 714 is the MAC entity used by UE 3 located in MN 1. MN RLC entities 712 and 713, and MN MAC entity 714, provide RLC and MAC functions compliant with the primary RAT (e.g., E-UTRA).

[0091] SN RLC entity 722, which serves as the RLC entity for the SCG split bearer in SN 2, receives PDCP PDUs from the unified PDCP entity 721 in SN 2 and provides the RLC PDUs to SN MAC entity 724. Conversely, SN RLC entity 723, which serves as the RLC entity for the MCG split bearer in SN 2, receives PDCP PDUs from the unified PDCP entity 711 in MN 1 and provides the RLC PDUs to SN MAC entity 724. SN MAC entity 724 is the MAC entity used by UE 3 in SN 2. SN RLC entities 722 and 723, and SN MAC entity 724, provide RLC and MAC functions compliant with secondary RAT (e.g., NR).

[0092] like Figure 7The unified PDCP entities 731 and 735, located on the receiving side of UE 3, are PDCP entities in the unified PDCP layer and provide unified PDCP functions corresponding to the unified PDCP layer. Unified PDCP entities 731 and 735 can be implemented in the same manner as those for the unified PDCP entities 711 and 721 described above. The method of implementing unified PDCP entities 731 and 735 in UE 3 can differ from the method of implementing unified PDCP entities 711 and 721 in MN 1 and SN 2.

[0093] MN MAC entity 734 is a MAC entity located in UE 3 for communicating with MN 1 via the MCG cell. MN MAC entity 734 receives MAC PDUs from a lower layer (i.e., the physical layer) (not shown) and provides MAC SDUs (RLC PDUs) to MN RLC entities 732 and 733. MN RLC entity 732, as an RLC entity used for MCG split bearers in UE 3, provides RLC SDUs (PDCP PDUs) to unified PDCP entity 731. On the other hand, MN RLC entity 733, as an RLC entity used for SCG split bearers in UE 3, provides RLC SDUs (PDCP PDUs) to unified PDCP entity 735. MN RLC entities 732 and 733, and MN MAC entity 734, provide RLC and MAC functions compliant with the primary RAT (e.g., E-UTRA).

[0094] SN MAC entity 738 is a MAC entity located in UE 3 for communicating with SN 2 via the SCG cell. SN MAC entity 738 receives MAC PDUs from a lower layer (i.e., the physical layer) (not shown) and provides MAC SDUs (RLC PDUs) to SN RLC entities 736 and 737. SN RLC entity 736, as the RLC entity used for SCG split bearers in UE 3, provides RLC SDUs (PDCP PDUs) to unified PDCP entity 735. On the other hand, SN RLC entity 737, as the RLC entity used for MCG split bearers in UE 3, provides RLC SDUs (PDCP PDUs) to unified PDCP entity 731. SN RLC entities 736 and 737, as well as SN MAC entity 738, provide RLC and MAC functions compliant with secondary RATs (e.g., NR).

[0095] The operation of MN 1, SN 2, and UE 3 according to this embodiment will be described below. MN 1 is configured to communicate with SN 2 associated with the secondary RAT and provide UE 3 with dual connectivity using both the primary and secondary RATs. MN 1 is also configured to configure (or establish) a PDCP entity 711 providing unified PDCP functionality and use this PDCP entity 711 for the MCG split bearer used by UE 3 in response to receiving UE capability information indicating that UE 3 supports split bearers from UE 3 or core network 4. In addition, in order to configure PDCP entity 731 in UE 3 to provide unified PDCP functionality, MN 1 sends unified PDCP configuration information (e.g., unified PDCP-config) related to the MCG split bearer to UE 3. UE 3 receives the unified PDCP configuration information related to the MCG split bearer and configures (or establishes) the unified PDCP entity 731 used by the MCG split bearer based on this information. Therefore, UE 3 uses the unified PDCP entity 731 to provide unified PDCP functionality for the MCG split bearer used by UE 3.

[0096] SN 2 is configured to communicate with MN 1, which is associated with the primary RAT, and to provide UE 3 with dual connectivity using both the primary and secondary RATs. SN 2 is also configured to configure (or establish) a PDCP entity 721 for providing unified PDCP functionality, and to use this PDCP entity 721 for the SCG split bearers used by UE 3, provided that MN 1 has received UE capability information from UE 3 or core network 4 indicating that UE 3 supports split bearers. Additionally, to configure PDCP entity 735 in UE 3 to provide unified PDCP functionality, SN 2 sends unified PDCP configuration information (e.g., unifiedPDCP-config) related to SCG split bearers to UE 3. This PDCP configuration information can be sent to UE 3 via MN 1, or directly from SN 2 to UE 3 if an RRC connection between SN 2 and UE 3 is available. UE 3 receives the unified PDCP configuration information related to SCG split bearers and configures (or establishes) the unified PDCP entity 735 used by the SCG split bearers based on this information. Therefore, for the SCG split bearer used by UE 3, UE 3 uses the unified PDCP entity 735 for providing unified PDCP functionality.

[0097] In the above example, it is assumed that UE capabilities are specified assuming that UE 3, which supports unified PDCP functionality, always supports both MCG split bearers and SCG split bearers. In other words, it is assumed that: a UE capability related to split bearer support indicates support for both MCG split bearers and SCG split bearers, and UE 3 supporting split bearers supports unified PDCP functionality. Optionally, separate UE capabilities can be specified for MCG split bearers and SCG split bearers respectively. In other words, separate UE capabilities can be specified for MCG split bearers and SCG split bearers respectively, and UE 3 supporting at least one of the two types of split bearers can support unified PDCP functionality.

[0098] Furthermore, UE capability information can explicitly or implicitly indicate that UE 3 supports split bearers in MR-DC. UE capability information can be, for example, information indicating whether UE 3 supports unified bearers (e.g., unified bearer support). Optionally, UE capability information can be information indicating whether UE 3 supports unified PDCP (e.g., unified PDCP support). Optionally, UE capability information can be information indicating whether UE 3 supports MR-DC (i.e., EN-DC, NG-EN-DC, NE-DC, or any combination thereof) (e.g., EN-DC support, NG-EN-DC support, NE-DC support).

[0099] Figure 8 This is a sequence diagram illustrating an example of the process for establishing an MCG split bearer according to this embodiment. Figure 8 An example of EN-DC is shown. Specifically, in Figure 8 In this configuration, MN 1 is the primary eNB (MeNB), SN 2 is the secondary gNB (SgNB), and the core network 4 is the EPC. In step 801, UE 3 establishes an RRC connection with MeNB 1, establishes a non-access stratum (NAS) connection with EPC 4 (e.g., an MME used as CP node 5) via MeNB 1, and establishes an MCG bearer in the MCG cell provided by MeNB 1.

[0100] Furthermore, in step 801, MeNB 1 receives UE capability information from UE 3 or EPC 4 (e.g., an MME acting as CP node 5). This UE capability information explicitly or implicitly indicates that UE 3 supports split bearer.

[0101] In step 802, to configure the MCG split bearer used by UE 3, MeNB 1 sends an SgNB Add (or Modify) Request message to SgNB 2 via interface 603 (i.e., the X2 interface). This SgNB Add (or Modify) Request message contains a bearer option information element (IE) set to the value "MCG split bearer". The SgNB Add (or Modify) Request message also contains an RRC container containing an SCG-ConfigInfo message. This SCG-ConfigInfo message includes the configuration used by the MCG split bearer and also includes a drb-type information element (IE) set to the value "MCG split".

[0102] In step 803, SgNB 2 sends an SgNB add (or modify) request confirmation message to MeNB 1 via interface 603 (i.e., the X2 interface). This message contains an RRC container that includes an SCG-Config message. The SCG-Config message includes the SCG configuration used for the MCG split bearer and also includes a drb-type information element (IE) set to the value "MCG split".

[0103] In step 804, MeNB 1 sends an RRC connection reconfiguration message to UE 3. This message contains unified PDCP configuration information (e.g., unified PDCP-config) related to the MCG split bearer. This unified PDCP configuration information enables UE 3 to establish, re-establish, or configure the unified PDCP entity used by the MCG split bearer. The message also contains SCG configuration, which includes the SCG-Config Information Element (IE) and other information used by the NR SCG. A change in bearer type from an MCG bearer to an MCG split bearer can be implicitly represented by the value of the drb-type IE within the SCG-Config IE. Optionally, the RRC connection reconfiguration message can explicitly indicate a change in bearer type from an MCG bearer to an MCG split bearer.

[0104] In step 805, UE 3 prepares the unified PDCP used for MCG split bearers. Similarly, in step 806, MeNB 1 prepares the unified PDCP used for MCG split bearers. The unified PDCP preparation performed by UE 3 in step 805 may include the following processes. The unified PDCP preparation performed by MeNB 1 in step 806 may also include the same processes.

[0105] In the case of directly configuring the MCG split bearer, i.e., when the new bearer (DRB) is initially established as the MCG split bearer, UE 3 establishes a new PDCP entity 731 in the unified PDCP layer for the MCG split bearer to provide unified PDCP functionality. MeNB 1 receives the information required to generate the SCG configuration (e.g., SCG-Config) from SgNB 2 during the SgNB addition or modification process (step 803) and sends the information used for DRB addition (i.e., DrbToAddMod: drb-type: MCGsplit) to UE 3 (step 804).

[0106] When an MCG bearer is changed to a split MCG bearer, UE 3 will re-establish the PDCP entity of the MCG bearer as a unified PDCP entity. UE 3 can re-establish the unified PDCP entity by applying a unified PDCP configuration while reusing a portion of the PDCP configuration of the MCG bearer (i.e., the LTE PDCP-config). UE 3 can also re-establish the unified PDCP entity by applying a new unified PDCP configuration.

[0107] Optionally, if the MCG bearer is changed to an MCG split bearer, UE 3 can reconfigure the PDCP entity of the MCG bearer as a unified PDCP entity. Optionally, UE 3 can switch the operating mode of the PDCP entity of the MCG bearer to a (sub)mode corresponding to unified PDCP. UE 3 can reconfigure the PDCP entity by applying the additional PDCP configuration (unified PDCP-config) required to provide unified PDCP functionality while reusing a portion of the PDCP configuration of the MCG bearer (i.e., LTE PDCP-config).

[0108] That is, the unified PDCP configuration information sent from MN 1 to UE 3 can be the new PDCP configuration information used by the MCG split bearer (i.e., full-config). Alternatively, the unified PDCP configuration information sent from MN 1 to UE 3 can include PDCP configuration information to be added to the PDCP configuration of the MCG bearer (i.e., LTE PDCP-config) (i.e., delta-config) or PDCP configuration information to be deleted from the PDCP configuration of the MCG bearer, in order to configure the unified PDCP entity.

[0109] Return to reference Figure 8In step 807, UE 3 sends an RRC connection reconfiguration complete message to MeNB 1. In step 808, MeNB 1 sends an SgNB add complete message to SgNB 2. In step 809, UE 3 performs a random access procedure to SgNB 2. Therefore, UE 3 is able to receive user plane (UP) data via MCG split bearer (step 810).

[0110] Figure 9 This is a sequence diagram illustrating an example of the process for establishing an SCG split bearer according to this embodiment. Figure 9 An example of EN-DC is shown. Specifically, in Figure 9 In this configuration, MN 1 is the primary eNB (MeNB), SN 2 is the secondary gNB (SgNB), and core network 4 is the EPC. Step 901 is the same as step 801. In step 901, MeNB 1 receives UE capability information from UE 3 or EPC 4 (e.g., the MME acting as CP node 5). This UE capability information explicitly or implicitly indicates that UE 3 supports split bearer.

[0111] In step 902, to configure the SCG split bearer used by UE 3, MeNB 1 sends an SgNB add (or modify) request message to SgNB 2 via interface 603 (i.e., the X2 interface). This SgNB add (or modify) request message contains a bearer option information element (IE) set to the value "SCG split Bearer". The SgNB add (or modify) request message also contains an RRC container containing an SCG-ConfigInfo message. This SCG-ConfigInfo message includes the configuration used for the SCG split bearer and also includes a drb-type information element (IE) set to the value "SCG split".

[0112] In step 903, SgNB 2 sends an SgNB add (or modify) request confirmation message to MeNB 1 via interface 603 (i.e., the X2 interface). This message contains an RRC container that contains an SCG-Config message. The SCG-Config message includes the SCG configuration used for the SCG split bearer and also includes a drb-type information element (IE) set to the value "SCG split". These SCG configurations include unified PDCP configuration information (e.g., unified PDCP-config) related to the SCG split bearer. The SCG configuration may, for example, include a DRB-ToAddModSCG IE containing a drb-type IE set to the value "scg-split" and also a pdcp-ConfigIE representing the unified PDCP configuration.

[0113] In step 904, MeNB 1 sends an RRC connection reconfiguration message to UE 3. This message contains SCG configuration, which includes the SCG-Config Information Element (IE) and other information used by the NR SCG. This SCG configuration includes unified PDCP configuration information (e.g., unified PDCP-config) related to the SCG split bearer. This unified PDCP configuration information enables UE 3 to establish, re-establish, or configure the unified PDCP entity used by the SCG split bearer. Other information used by the NR SCG includes, for example, SCG security. A change in bearer type from an MCG or SCG bearer to an SCG split bearer can be implicitly represented by the value of the drb-type IE in the SCG-Config IE. Alternatively, the RRC connection reconfiguration message can explicitly represent a change in bearer type from an MCG or SCG bearer to an SCG split bearer.

[0114] In step 905, UE 3 prepares the unified PDCP used for SCG split bearers. Similarly, in step 906, SgNB 2 prepares the unified PDCP used for SCG split bearers. The unified PDCP preparation performed by UE 3 in step 905 may include the following processes. The unified PDCP preparation performed by SgNB 2 in step 906 may also include the same processes.

[0115] When an MCG bearer is changed to an SCG split bearer (e.g., during an SgNB addition process), UE 3 establishes a new PDCP entity 735 in the unified PDCP layer for the SCG split bearer to provide unified PDCP functionality. UE 3 may release the PDCP entity used for the MCG bearer. Optionally, UE 3 may maintain the PDCP entity used for the MCG bearer. The maintained PDCP entity can be used to forward flows (PDU flows, QoS flows) that have not yet been moved from the MCG bearer to the SCG split bearer.

[0116] When an SCG bearer is changed to a split SCG bearer (e.g., during an SgNB modification process), UE 3 will re-establish the PDCP entity of the SCG bearer as a unified PDCP. UE 3 can re-establish the unified PDCP entity by applying a unified PDCP configuration while reusing a portion of the PDCP configuration of the SCG bearer (i.e., the NR PDCP-config). UE 3 can also re-establish the unified PDCP entity by applying a new unified PDCP configuration.

[0117] Optionally, when the SCG bearer is changed to an SCG split bearer, UE 3 can reconfigure the PDCP entity of the SCG bearer as a unified PDCP. Optionally, UE 3 can switch the operating mode of the PDCP entity of the SCG bearer to a (sub)mode corresponding to unified PDCP. UE 3 can reconfigure the PDCP entity by applying the additional PDCP configuration (unified PDCP-config) required to provide unified PDCP functionality while reusing a portion of the PDCP configuration of the SCG bearer (i.e., NR PDCP-config).

[0118] Return to reference Figure 9 In step 907, UE 3 sends an RRC connection reconfiguration complete message to MeNB 1. In step 908, MeNB 1 sends an SgNB add complete message to SgNB 2. In step 909, UE 3 performs a random access procedure to SgNB 2. Therefore, UE 3 can receive user plane (UP) data via SCG split bearer (step 910).

[0119] Second Embodiment

[0120] This embodiment provides a variation of the unified PDCP layer implementation in a radio communication network described in the first embodiment. (The remaining text appears to be incomplete and lacks context.) Figure 6 The example shown is the same. The radio protocol architecture used for the MCG split bearer and SCG split bearer according to this embodiment is the same as... Figure 7 The example shown is the same.

[0121] In this embodiment, MN 1 and UE 3 are configured to use a unified PDCP entity for newly configured MCG split bearers, SCG bearers, or SCG split bearers when starting MR-DC. MN 1 and UE 3 are also configured to use a unified PDCP entity to provide unified PDCP functionality for existing MCG bearers used by UE 3 when starting MR-DC. In other words, when UE 3, which supports split bearers in MR-DC, starts MR-DC, MN 1 and UE 3 also use a unified PDCP entity for the MCG bearers used by UE 3, regardless of whether the MCG split bearer is used by UE 3.

[0122] When MN 1 initiates MR-DC with UE 3, MN 1 can newly (re-)establish a unified PDCP entity as the PDCP entity used by UE 3's already established MCG bearer. MN 1 can reuse part of the MCG bearer's PDCP configuration (e.g., LTE PDCP-config) or DRB configuration (e.g., LTE DRB configuration).

[0123] Optionally, when MN 1 initiates MR-DC with UE 3, MN 1 can re-establish the PDCP entity used by the existing MCG bearer for UE 3 in a manner that provides unified PDCP functionality. MN 1 can re-establish the PDCP entity used by the MCG bearer by applying a unified PDCP configuration while reusing a portion of the PDCP configuration of the MCG bearer (e.g., LTE PDCP-config). MN 1 can also re-establish the PDCP entity used by the MCG bearer by applying a new unified PDCP configuration.

[0124] Optionally, when MN 1 initiates MR-DC with UE 3, MN 1 can reconfigure the PDCP entity used by the UE 3's established MCG bearer in a manner that provides unified PDCP functionality. Optionally, UE 3 can switch the operating mode of the PDCP entity of the established MCG bearer to a (sub)mode corresponding to unified PDCP. MN 1 can reconfigure the PDCP entity used by the MCG bearer by applying an additional PDCP configuration (unified PDCP-config) for providing unified PDCP functionality while reusing a portion of the PDCP configuration of the MCG bearer (e.g., LTE PDCP-config).

[0125] Similarly, in this embodiment, UE 3 is configured to use a unified PDCP entity for newly configured MCG split bearers, SCG bearers, or SCG split bearers when UE 3 starts MR-DC. UE 3 is also configured to use the unified PDCP entity for providing unified PDCP functionality for already established MCG bearers when UE 3 starts MR-DC. In other words, when UE 3, which supports split bearers, starts MR-DC, UE 3 uses the unified PDCP entity for MCG bearers regardless of whether MCG split bearers are used by UE 3.

[0126] Figure 10 This is a sequence diagram illustrating an example of the MR-DC initiation process involving the establishment of an MCG split bearer according to this embodiment. Figure 10 An example of EN-DC is shown. Specifically, in Figure 10 In this network, MN 1 is the primary eNB (MeNB), SN 2 is the secondary gNB (SgNB), and the core network 4 is the EPC. Step 1001 involves processing... Figure 8 The processing in step 801 is the same. In step 1001, MeNB 1 receives UE capability information from UE 3 or EPC 4 (e.g., the MME acting as CP node 5). This UE capability information explicitly or implicitly indicates that UE 3 supports split bearer.

[0127] In step 1002, in order to initiate EN-DC with UE 3, MeNB 1 sends an SgNB Add Request message to SgNB2 via interface 603 (i.e., the X2 interface). This SgNB Add Request message contains... Figure 8 In step 802 of the SgNB add (or modify) request message, the information element (IE) contained in the message is the same as the information element (IE).

[0128] In step 1003, SgNB 2 sends an SgNB add request confirmation message to MeNB 1 via interface 603 (i.e., the X2 interface). This SgNB add request confirmation message contains... Figure 8 The SgNB Add (or Modify) Request Confirmation Message in step 803 contains the same information element (IE) as the information element (IE).

[0129] Processing steps 1004-1010 and Figure 8The processing in steps 804-810 is the same. However, the RRC connection reconfiguration message in step 1004 also includes unified PDCP configuration information related to the MCG bearer. For example, the RRC connection reconfiguration message may include a DRB-ToAddModList IE indicating the addition and deletion of an MCG bearer or the modification of an MCG bearer, and the DRB-ToAddModList IE may also include a DRB-ToAddMod IE containing a pdcp-Config IE indicating unified PDCP configuration. In step 1005, in addition to preparing the unified PDCP entity used for the MCG split bearer, UE 3 also establishes, re-establishes, or reconfigures the PDCP entity used for the already established MCG bearer to apply unified PDCP to that MCG bearer as well. Optionally, UE 3 may switch the operating mode of the PDCP entity of the already established MCG bearer to a (sub)mode corresponding to unified PDCP. Similarly, in step 1006, in addition to preparing the unified PDCP entity used for the MCG split bearer, MeNB 1 also establishes, re-establishes, or reconfigures the PDCP entity used for the MCG bearer already established for UE 3, so that the unified PDCP can also be applied to that MCG bearer. Optionally, MeNB 1 can switch the operating mode of the PDCP entity for the MCG bearer already established for UE 3 to a (sub)mode corresponding to the unified PDCP.

[0130] Figure 11 This is a sequence diagram illustrating an example of an MR-DC initiation process involving the establishment of an SCG bearer or an SCG split bearer according to this embodiment. Figure 11 An example of EN-DC is shown. Specifically, in Figure 11 In this network, MN 1 is the primary eNB (MeNB), SN 2 is the secondary gNB (SgNB), and the core network 4 is an EPC. Step 1101 involves processing... Figure 8 The process in step 1101 is the same. In step 1101, MeNB1 receives UE capability information from UE 3 or EPC 4 (e.g., the MME acting as CP node 5). This UE capability information explicitly or implicitly indicates that UE 3 supports split bearer.

[0131] In step 1102, to initiate EN-DC with UE 3, MeNB 1 sends an SgNB Add Request message to SgNB2 via interface 603 (i.e., the X2 interface). This SgNB Add Request message contains a Bearer Option Information Element (IE) set to the value "SCG bearer" or "SCG split bearer". The SgNB Add (or Modify) Request message also contains an RRC container, which includes an SCG-ConfigInfo message. This SCG-ConfigInfo message includes the configuration used for the SCG split bearer and also includes a drb-type information element (IE) set to the value "SCG" or "SCG split".

[0132] In step 1103, SgNB 2 sends an SgNB Add Request Confirmation Message to MeNB 1 via interface 603 (i.e., the X2 interface). This message contains an RRC container that includes an SCG-Config message. The SCG-Config message includes the SCG configuration used for the SCG split bearer and also includes a drb-type information element (IE) set to the value "SCG" or "SCG split".

[0133] Processing steps 1104-1110 and Figure 9 The processing of steps 904-910 is the same. However, the RRC connection reconfiguration message in step 1104 also includes unified PDCP configuration information related to the MCG bearer. For example, the RRC connection reconfiguration message may include a DRB-ToAddModList IE indicating the addition and deletion of an MCG bearer or the modification of an MCG bearer, and the DRB-ToAddModList IE may include a DRB-ToAddModIE containing a pdcp-Config IE indicating unified PDCP configuration. In step 1105, in addition to preparing the unified PDCP entity used for the SCG bearer or SCG split bearer, UE 3 also establishes, re-establishes, or reconfigures the PDCP entity used for the already established MCG bearer, or switches the (sub)mode of the PDCP entity used for the MCG bearer to apply unified PDCP to the MCG bearer as well. In step 1106, SgNB 2 prepares the unified PDCP used for the SCG split bearer or SCG bearer.

[0134] Figure 11The process shown also includes step 1106B. In step 1006B, MeNB 1 establishes, re-establishes, or reconfigures the PDCP entity used for the MCG bearer already established for UE 3, or switches the (sub)mode of the PDCP entity used for the MCG bearer to apply the same unified PDCP to the MCG bearer.

[0135] As described above, when MR-DC is initiated, the radio communication system according to this embodiment applies PDCP not only to split bearers but also to other bearers (such as already established MCG bearers). Therefore, processing latency during bearer type changes from other bearer types (MCG bearers, SCG bearers) to split bearers or from split bearers to other bearer types can be reduced. This processing latency includes, for example, the re-establishment of at least one of the PDCP entity and RLC entity, or the reset of the MAC entity, or both.

[0136] Third Embodiment

[0137] This embodiment provides a variation of the unified PDCP layer implementation in a radio communication network described in the second embodiment. (The text then abruptly shifts to a seemingly unrelated topic: a structural example of a radio communication network according to this embodiment.) Figure 6 The example shown is the same. The radio protocol architecture used for the MCG split bearer and SCG split bearer according to this embodiment is the same as... Figure 7 The example shown is the same.

[0138] In this embodiment, SN 2 and UE 3 are configured to establish, re-establish, or reconfigure the PDCP entity used by the already established SCG bearer, or switch the (sub)mode of the PDCP entity used by the SCG bearer, in the manner of providing unified PDCP functionality, when a unified PDCP entity is established for the SCG split bearer to provide unified PDCP functionality.

[0139] Fourth embodiment

[0140] This embodiment provides a variation of the unified PDCP layer implementation in a radio communication network described in the first and second embodiments. Figure 6 The example shown is the same. The radio protocol architecture used for the MCG split bearer and SCG split bearer according to this embodiment is the same as... Figure 7 The example shown is the same.

[0141] In this embodiment, MN 1 is configured to use a PDCP entity to provide MN PDCP functionality corresponding to the primary RAT for the MCG bearer used by UE3 when UE 3 does not support split bearers in MR-DC. MN 1 is also configured to use a unified PDCP entity to provide unified PDCP functionality for the MCG bearer used by UE 3 when UE 3 supports split bearers in MR-DC, regardless of whether MR-DC is started for UE 3. In other words, MN 1 is configured to use a unified PDCP entity for the MCG bearer used by UE 3 before MR-DC is started for UE 3 when UE 3 supports split bearers in MR-DC.

[0142] UE 3 is configured to use a PDCP entity to provide MN PDCP functionality corresponding to the primary RAT for the MCG bearers used by UE 3, provided that UE 3 does not support split bearers in MR-DC. UE 3 is also configured to use a unified PDCP entity to provide unified PDCP functionality for the MCG bearers used by UE 3, regardless of whether MR-DC is initiated for UE 3, provided that UE 3 supports split bearers in MR-DC. In other words, UE 3 is configured to use a unified PDCP entity for the MCG bearers used by UE 3 before MR-DC is initiated for UE 3, provided that UE 3 supports split bearers in MR-DC.

[0143] Figure 12 This is a sequence diagram illustrating an example of the process for establishing an RRC connection and user plane bearer according to this embodiment. Figure 12 An example of EN-DC is shown. Specifically, in Figure 12 In this network, MN 1 is the primary eNB (MeNB), SN 2 is the secondary gNB (SgNB), and the core network 4 is the EPC.

[0144] Steps 1201-1203 illustrate the RRC connection establishment process. In step 1201, UE 3 sends an RRC connection request message to MeNB 1. In step 1202, MeNB 1 sends an RRC connection setup message to UE 3. In step 1203, UE 3 sends an RRC connection setup complete message to MeNB 1. This RRC connection setup complete message includes an initial NAS message (e.g., a service request message) from UE 3 to EPC 4.

[0145] In step 1204, MeNB 1 sends an INITIALUE MESSAGE message to EPC 4 containing the initial NAS message received from UE 3. In step 1205, EPC 4 (e.g., the MME acting as CP node 5) sends an INITIAL CONTEXT SETUP REQUEST message to MeNB 1. This INITIAL CONTEXTSETUP REQUEST message contains UE radio access capability information, including UE capability information elements indicating that UE 3 supports split bearers (e.g., "split bearer support" or "unified bearer support"). The name of the UE capability information element (IE) indicating support for split bearers in the MR-DC can be "unified PDCP support," "EN-DC support," "NG-EN-DC support," or "NE-DC support."

[0146] In step 1206, MeNB 1 performs access layer (AS) security activation with UE 3.

[0147] In step 1207, MeNB 1 sends an RRC connection reconfiguration message to UE 3. This RRC connection reconfiguration message contains the DRB configuration to be applied to the MCG bearer. The PDCP configuration (PDCP-Config) contains the PDCP configuration (PDCP-Config) used to utilize the unified PDCP employed by the MCG bearer.

[0148] In step 1208, UE 3 prepares the unified PDCP used for MCG bearers. Similarly, in step 1209, MeNB 1 prepares the unified PDCP used for MCG bearers. Specifically, MeNB 1 and UE 3 each establish a new unified PDCP entity as the PDCP entity used for MCG bearers.

[0149] In step 1210, UE 3 sends an RRC connection reconfiguration complete message to MeNB 1. In step 1211, MeNB 1 sends an INITIAL CONTEXT SETUP RESPONSE message to EPC 4.

[0150] In step 1212, a new (MCG) bearer can be established based on the NAS Extended Service Request message.

[0151] In step 1213, an SgNB addition process is performed to initiate the MR-DC (i.e., EN-DC in this example). This SgNB addition process can be based on a specific example, such as that described in the first embodiment. Figure 8 Or 9) one of them.

[0152] exist Figure 12 In the illustrated process, EPC 4 (e.g., the MME acting as CP node 5) sends UE capability information to MeNB 1 indicating that UE 3 supports split bearer. Optionally, UE 3 may send this UE capability information to MeNB 1.

[0153] In some implementations, UE 3 can send UE capability information to MeNB 1 during the RRC connection establishment process (steps 1201-1203).

[0154] In some implementations, UE 3 can send UE capability information to MeNB 1 using an RRC connection request message (step 1201). Therefore, MeNB 1 can know whether UE 3 supports split bearers before an RRC connection is established. Thus, for example, MeNB 1 can use unified PDCP for the PDCP configuration of the signaling radio bearer (SRB 1) used to transmit RRC messages. Specifically, MeNB 1 can send an RRC connection setup message to UE 3 (step 1202) containing information indicating the use of unified PDCP (unified PDCP indication) or containing PDCP configuration corresponding to unified PDCP functionality.

[0155] In some implementations, UE 3 can use a third message (i.e., message 3 (Msg3)) instead of an RRC connection request message to send UE capability information to MeNB 1 during the random access procedure. The third message carrying UE capability information during the random access procedure can be, for example, an RRC connection re-establishment request message, an RRC connection restoration request message, or an RRC connection activation request message. The RRC connection activation request message is sent by the UE to request a transition from the (newly introduced in 5G) RRC_INACTIVE state to the RRC_CONNECTED state.

[0156] The UE capability information sent from UE 3 to MeNB 1 during the RRC connection establishment process can be referred to as an "early UE capability indication". This UE capability information can be defined as an RRC Information Element (IE). This RRC IE can be referred to as, for example, a "splitBearer (support) IE", a "unifiedBearer (support) IE", or a "unifiedPDCP (support) IE". This UE capability information can be an interoperability test (IOT) bit. The IOT bit is a flag indicating that the interoperability test is complete. Optionally, an RRC IE (e.g., earlyCapabilityIndicationIE) can be defined for multiple purposes, and information related to MR-DC can be collected in a single field (e.g., MultiRAT-DC, MR-DC) within the RRC IE. The UE capability information can then be sent using subfields included in the field related to MR-DC (e.g., the splitBearer subfield or the unified PDCP subfield).

[0157] Optionally, the UE capability information (i.e., early UE capability indication) can be defined as a MAC control element (CE). This MAC CE can be referred to, for example, as a "Split Bearer (Supported) MAC CE," a "Unified Bearer (Supported) MAC CE," or a "Unified PDCP (Supported) MAC CE." Optionally, a MAC CE (e.g., an early capability indication MAC CE) can be defined for early UE capability indications that will be used for multiple purposes, and a bitmap in this MAC CE can be used to transmit MR-DC related information including the early UE capability indication.

[0158] Optionally, this UE capability information (i.e., early UE capability indication) can be defined as the logical channel ID (LCID) of the uplink (UL) common control channel (CCCH) (i.e., the UL LCID (SRB0) of the CCCH). This UE capability information can be defined as a new LCID that is different from the LCIDs of other CCCHs to indicate support for split bearers. If UE 3 supports split bearers, UE 3 can use this new LCID to send a third message (e.g., an RRC connection request message).

[0159] According to the above method, the network (e.g., MN or SN 2 or both) can know early in the RRC connection establishment phase that UE 3 supports split bearers and its unified PDCP in MR-DC. By using the unified PDCP from the new bearer establishment phase, processing delays such as handover between LTE PDCP and unified PDCP can be omitted.

[0160] Figure 13 This is a sequence diagram illustrating an example of using the aforementioned early UE capability indication. Figure 13 An example of EN-DC is shown. Specifically, in Figure 13 In this network, MN 1 is the primary eNB (MeNB), SN 2 is the secondary gNB (SgNB), and the core network 4 is the EPC.

[0161] Steps 1301–1303 illustrate the RRC connection establishment process. In step 1301, UE 3 sends an RRC connection request message to MeNB 1, which includes an indication of early UE capability supporting split bearers. In step 1302, MeNB 1 sends an RRC connection setup message to UE 3. This RRC connection setup message includes information indicating the use of Unified PDCP (Unified PDCP indication) or includes PDCP configuration corresponding to Unified PDCP functionality. In step 1303, UE 3 sends an RRC connection setup complete message to MeNB 1. The RRC connection setup complete message includes an initial NAS message (e.g., a service request message) from UE 3 to EPC 4.

[0162] In step 1304, MeNB 1 sends an INITIALUE MESSAGE message containing the initial NAS message received from UE 3 to EPC 4. In step 1305, EPC 4 sends an INITIAL CONTEXT SETUP REQUEST message to MeNB 1.

[0163] In step 1306, UE 3 prepares the unified PDCP for the signaling radio bearer (SRB 1) used to transmit RRC messages, according to the processing specified in the unified PDCP specification or according to the PDCP configuration received in step 1302. Similarly, in step 1307, MeNB 1 prepares the unified PDCP for the signaling radio bearer (SRB 1). That is, MeNB 1 and UE 3 each establish a new unified PDCP entity as the PDCP entity used for the signaling radio bearer (SRB 1).

[0164] In step 1308, MeNB 1 performs AS security activation with UE 3. This AS security activation is performed via a signaling radio bearer (SRB 1) using unified PDCP or applying a PDCP configuration corresponding to the unified PDCP function.

[0165] In step 1309, MeNB 1 sends an RRC connection reconfiguration message to UE 3. This RRC connection reconfiguration message contains the DRB configuration to be applied to the MCG bearer. The PDCP configuration (PDCP-Config) contains the PDCP configuration (PDCP-Config) used to utilize the unified PDCP employed by the MCG bearer.

[0166] Processing in steps 1310 to 1313 Figure 12 The processes in steps 1210 to 1213 shown are the same.

[0167] UE 3 may send the aforementioned early UE capability indication only under specific conditions. These specific conditions may include, for example, broadcasting information in UE 3's serving cell (e.g., PCell) indicating MN 1's (i.e., the serving RAN node, such as eNB or gNB) support for MR-DC (or split bearers within MR-DC) or Unified PDCP. Alternatively, UE 3 may broadcast information in UE 3's serving cell indicating that MN 1 permits the transmission of the early UE capability indication. Optionally, MN 1 may request the early UE capability indication from UE 3 via message 4 (e.g., RRC connection setup) during random access, and UE 3 may respond to this request by sending the early UE capability indication via message 5 (e.g., RRC connection setup complete).

[0168] Fifth Embodiment

[0169] This embodiment provides specific examples of the unified PDCP configuration described in the first to fourth embodiments. The structural example of the radio communication network according to this embodiment is also provided. Figure 6 The example shown is the same. The radio protocol architecture used for the MCG split bearer and SCG split bearer according to this embodiment is the same as... Figure 7 The example shown is the same.

[0170] As an example, an LTE PDCP-config may include at least one of the following: discardTimer; rlc-AM; rlc-UM; headerCompression; rn-IntegrityProtection; pdcp-SN-Size; ul-DataSplitDRB-ViaSCG; and t-Reordering.

[0171] The discardTimer field indicates the duration (ms) of the valid PDCP SDU obtained from the upper layer. The UE discards the PDCPSDU when the discardTimer expires or when the PDCP status report confirms the successful delivery of the PDCP SDU.

[0172] The rlc-AM field is required for setting up the PDCP entity used by the radio bearer configured with RLC Acknowledgment Mode (AM). rlc-AM includes "statusReportRequired", which indicates whether the UE should send a PDCP status report in response to PDCP entity re-establishment and PDCP data recovery.

[0173] The rlc-UM field is required to configure the PDCP entity used for radio bearers configured with RLC Unacknowledged Mode (UM). rlc-UM includes pdcp-SN-Size (i.e., 7-bit, 12-bit, 15-bit, or 18-bit).

[0174] The headerCompression field includes Robust Header Compression (ROHC) information to be used for header compression at the PDCP layer. The ROHC information also includes a Maximum Context Identifier (maxCID) and a profile. The profile defines a specific combination of protocols at the network layer, transport layer, and upper layers.

[0175] The rn-IntegrityProtectio field indicates whether integrity protection or verification should be applied to all subsequent packets received and sent by the relay node.

[0176] The ul-DataSplitDRB-ViaSCG field indicates whether the UE should send the PDCP PDU via SCG.

[0177] The t-Reordering field indicates the value (ms) of the reordering timer.

[0178] On the other hand, the NR PDCP-config may include at least one of the information elements included in the existing LTE PDCP-config. For example, as mentioned above, the number of possible values ​​for pdcp-SN-Size in the NR PDCP-config may be smaller than the number of possible values ​​for pdcp-SN-Size in the NR PDCP-config (i.e., 12 bits or 18 bits). Alternatively or additionally, the NR PDCP-config may include additional information elements not included in the existing LTE PDCP-config. Additional information elements may include “ul-DataSplitDRB-ViaUnifiedSplitBearer” (or “ul-DataSplitDRB-ViaMCGSplitBearer” or “ul-DataSplitDRB-ViaSCGSplitBearer”) indicating whether the UE should transmit the PDCP PDU via a unified split bearer (or MCG split bearer or SCG split bearer). Additional information elements may include information related to obtaining SDAP PDUs from the SDAP sublayer or delivering PDCP SDUs to the SDAP sublayer.

[0179] As mentioned above, the Unified PDCP config can be the same as the NR PDCP-config or the LTE PDCP-config, can be a subset of the NR PDCP-config or the LTE PDCP-config, or can be a common subset (common part) between the NR PDCP-config and the LTE PDCP-config.

[0180] The NR PDCP-config can be included as a subset of the LTE PDCP-config and sent from MN1 to UE3, or the NR PDCP-config can be sent from MN1 to UE3 in addition to the LTE PDCP-config.

[0181] The Unified PDCP config can be included as a subset in the LTE PDCP-config or NRPDCP-config and sent from MN 1 to UE 3, or the Unified PDCP config can also be sent from MN 1 to UE 3 in addition to the LTE PDCP-config and NRPDCP-config.

[0182] When the Unified PDCP config is included as a subset in each of the LTE PDCP-config and the NR PDCP-config, the UE 3 can recognize that the Unified PDCP configuration is activated provided that the two Unified PDCP configs included in the LTE PDCP-config and the NR PDCP-config are at least partially consistent with each other.

[0183] The following provides a structural example of MN 1, SN 2, UE 3 and CP node 5 according to the above embodiments. Figure 14 This is a block diagram illustrating an example structure of MN 1 according to the above embodiment. The structure of SN 2 can be the same as... Figure 14 Same as shown. Reference Figure 14 MN 1 includes an RF transceiver 1401, a network interface 1403, a processor 1404, and a memory 1405. The RF transceiver 1401 performs analog RF signal processing to communicate with a UE, including UE3. The RF transceiver 1401 may include multiple transceivers. The RF transceiver 1401 is coupled to an antenna array 1402 and a processor 1404. The RF transceiver 1401 receives modulated symbol data from the processor 1404, generates a transmit RF signal, and supplies the transmit RF signal to the antenna array 1402. Furthermore, the RF transceiver 1401 generates a baseband receive signal based on the receive RF signal received by the antenna array 1402 and supplies the baseband receive signal to the processor 1404.

[0184] Network interface 1403 is used to communicate with network nodes (e.g., SN 2, CP node 5, and UP node 6). Network interface 1403 may include, for example, a network interface card (NIC) compliant with the IEEE 802.3 family.

[0185] Processor 1404 performs digital baseband signal processing (i.e., data plane processing) and control plane processing for radio communication. Processor 1404 may include multiple processors. Processor 1404 may include, for example, a modem processor (e.g., a digital signal processor (DSP)) for performing digital baseband signal processing and a protocol stack processor (e.g., a central processing unit (CPU) or microprocessor unit (MPU)) for performing control plane processing.

[0186] Memory 1405 includes a combination of volatile and non-volatile memory. Volatile memory may be, for example, static random access memory (SRAM), dynamic RAM (DRAM), or a combination thereof. Non-volatile memory may be, for example, mask read-only memory (MROM), electrically erasable programmable ROM (EEPROM), flash memory, hard disk drive, or any combination thereof. Memory 1405 may include storage units located remotely from processor 1404. In this case, processor 1404 may access memory 1405 via network interface 1403 or an I / O interface (not shown).

[0187] Memory 1405 may store one or more software modules (computer programs) 1406, which include instructions and data for performing the processing of MN 1 as described in the above embodiments. In some implementations, processor 1404 may be configured to load software modules 1406 from memory 1405 and execute the loaded software modules to perform the processing of MN 1 as described in the above embodiments.

[0188] Figure 15 This is a block diagram illustrating an example of the structure of UE 3. A radio frequency (RF) transceiver 1501 performs analog RF signal processing to communicate with MN 1 and SN 2. RF transceiver 1501 may include multiple transceivers. The analog RF signal processing performed by RF transceiver 1501 includes up-conversion, down-conversion, and amplification. RF transceiver 1501 is coupled to antenna array 1502 and baseband processor 1503. RF transceiver 1501 receives modulated symbol data (or OFDM symbol data) from baseband processor 1503, generates a transmit RF signal, and supplies the transmit RF signal to antenna array 1502. Furthermore, RF transceiver 1501 generates a baseband receive signal based on the receive RF signal received by antenna array 1502 and supplies the baseband receive signal to baseband processor 1503.

[0189] The baseband processor 1503 performs digital baseband signal processing (i.e., data plane processing) and control plane processing for radio communication. Digital baseband signal processing includes (a) data compression / decompression, (b) data segmentation / concatenation, (c) synthesis / decomposition of transmission formats (i.e., transmission frames), (d) channel coding / decoding, (e) modulation (i.e., symbol mapping) / demodulation, and (f) generation of OFDM symbol data (i.e., baseband OFDM signals) via inverse fast Fourier transform (IFFT). On the other hand, control plane processing includes communication management at layers 1 (e.g., transmission power control), 2 (e.g., radio resource management and hybrid automatic repeat request (HARQ) processing), and 3 (e.g., signaling related to attachment, mobility, and call management).

[0190] The digital baseband signal processing of the baseband processor 1503 may include, for example, signal processing at the Packet Data Convergence Protocol (PDCP) layer, Radio Link Control (RLC) layer, MAC layer, and PHY layer. Furthermore, the control plane processing performed by the baseband processor 1503 may include processing of Non-Access Stratum (NAS) protocols, RRC protocols, and MAC CE.

[0191] The baseband processor 1503 may include a modem processor (e.g., a DSP) for performing digital baseband signal processing and a protocol stack processor (e.g., a CPU or MPU) for performing control plane processing. In this case, the protocol stack processor for performing control plane processing may be integrated with the application processor 1504, which will be described later.

[0192] Application processor 1504 is also referred to as CPU, MPU, microprocessor, or processor core. Application processor 1504 may include multiple processors (processor cores). Application processor 1504 loads system software programs (operating system (OS)) and various application programs (e.g., call applications, web browsers, email programs, camera operation applications, and music player applications) from memory 1506 or from other memory (not shown), and executes these programs to provide various functions of UE 3.

[0193] In some implementations, such as Figure 15 As shown by the dashed line (1505), the baseband processor 1503 and application processor 1504 can be integrated on a single chip. In other words, the baseband processor 1503 and application processor 1504 can be implemented in a single system-on-a-chip (SoC) device 1505. SoC devices may be referred to as large-scale integration (LSI) or chipsets.

[0194] Memory 1506 is volatile memory, non-volatile memory, or a combination thereof. Memory 1506 may include multiple physically independent memory devices. Volatile memory is, for example, SRAM, DRAM, or a combination thereof. Non-volatile memory is, for example, MROM, EEPROM, flash memory, hard disk drive, or any combination thereof. Memory 1506 may include, for example, external memory devices accessible from baseband processor 1503, application processor 1504, and SoC 1505. Memory 1506 may include internal memory devices integrated into baseband processor 1503, application processor 1504, or SoC 1505. Furthermore, memory 1506 may include memory in a Universal Integrated Circuit Card (UICC).

[0195] The memory 1506 may store one or more software modules (computer programs) 1507, which include instructions and data for performing the processing of UE 3 as described in the above embodiments. In some implementations, the baseband processor 1503 or the application processor 1504 may load these software modules 1507 from the memory 1506 and execute the loaded software modules to perform the processing of UE 3 as described in the above embodiments with reference to the accompanying drawings.

[0196] Figure 16 This is a block diagram illustrating an example structure of CP node 5 according to the above embodiment. (See reference...) Figure 16 CP node 5 includes a network interface 1601, a processor 1602, and a memory 1603. The network interface 1601 is used to communicate with network nodes (e.g., RAN nodes and other core network nodes). The network interface 1601 may, for example, include a network interface card (NIC) compliant with the IEEE 802.3 family.

[0197] Processor 1602 may be, for example, a microprocessor, an MPU, or a CPU. Processor 1602 may include multiple processors.

[0198] Memory 1603 includes a combination of volatile and non-volatile memory. Volatile memory may be, for example, SRAM, DRAM, or a combination thereof. Non-volatile memory may be, for example, MROM, PROM, flash memory, hard disk drive, or any combination thereof. Memory 1603 may include storage units located geographically away from processor 1602. In this case, processor 1602 may access memory 1603 via network interface 1601 or an I / O interface (not shown).

[0199] The memory 1603 may store one or more software modules (computer programs) 1604, which include instructions and data for performing the processing of CP node 5 as described in the above embodiments. In some implementations, the processor 1602 may be configured to load one or more software modules 1604 from the memory 1603 and execute the loaded software modules to perform the processing of CP node 5 as described in the above embodiments.

[0200] As referenced above Figure 14 , 15As described in Figure 16, the processors included in MN 1, SN 2, UE 3, and CP node 5 according to the above embodiments each execute one or more programs, which include instructions for causing the computer to perform the algorithms illustrated with reference to the accompanying drawings. The programs can be stored and provided to the computer using any type of non-transitory computer-readable medium. Non-transitory computer-readable media include any type of tangible storage medium. Examples of non-transitory computer-readable media include magnetic storage media (such as floppy disks, magnetic tapes, hard disk drives, etc.), optical-magnetic storage media (e.g., magneto-optical disks), compact optical disc read-only memory (CD-ROM), CD-R, CD-R / W, and semiconductor memories (such as mask ROMs, programmable ROMs (PROMs), erasable PROMs (EPROMs), flash ROMs, random access memory (RAMs), etc.). The programs can be provided to the computer using any type of transient computer-readable medium. Examples of transient computer-readable media include electrical signals, optical signals, and electromagnetic waves. Transient computer-readable media can provide the programs to the computer via wired communication lines (e.g., electrical wires and optical fibers) or wireless communication lines.

[0201] Other embodiments

[0202] The above embodiments primarily illustrate examples of EN-DC. The structure and operation of the devices described in these embodiments can be used for NE-DC and NG-EN-DC.

[0203] The above embodiments provide examples of information elements (e.g., SCG-ConfigInfo, SCG-Config) and messages transmitted between MN 1 and SN 2 having the names and structures of a hypothetical LTE DC. However, the names and structures of information elements and messages in an MR-DC may differ from those in an LTE DC. For example, at least some of the information elements included in SCG-ConfigInfo and SCG-Config may be defined as information elements of the X2 interface (or Xn interface) between MN 1 and SN 2.

[0204] The above embodiments primarily illustrate DRB and MCG SRB. However, the unified PDCP described in the above embodiments can be used for other radio bearers, including MCG split SRB and SCG SRB. Furthermore, the configuration (or establishment) of the unified PDCP can be implicitly represented by the configuration of the split bearer (e.g., a DRB configuration with drbType "split"). Optionally, the flag "unified" for explicitly representing the configuration (or establishment) of the unified PDCP can be added to the PDCP configuration (PDCPConfig).

[0205] The above embodiments can be applied to mobile scenarios. During a mobility process, for example, MN 1, SN 2, and UE 3 can change (or fall back) from the unified PDCP to an existing PDCP (e.g., LTE PDCP). Mobility here can include one or both of intra-SN changes (e.g., PSCell change) and inter-SN changes (SN change), as well as handover. The objects to be controlled here can be all bearers affected by mobility to some extent. For example, during handover, all bearers using the unified PDCP can be considered as the objects of PDCP change control. During intra-SN / inter-SN changes, SCG split bearers can be considered as the objects of PDCP change control. Optionally, when UE 3 using the unified PDCP in the source cell performs a handover to the target cell, UE 3 can continue to use the unified PDCP unless the target cell does not support split bearers (i.e., unified bearers or unified PDCP). If the target cell does not support split bearers, UE 3 can change (fall back) from the unified PDCP to an existing PDCP (e.g., LTE PDCP).

[0206] In the above embodiments, where the unified PDCP includes functions and processes different from those of the existing PDCP (i.e., MN PDCP or SN PDCP), other (sub)layers can operate with respect to these differences, or the unified PDCP can operate with respect to these differences. For example, although the amount of data waiting to be transmitted between the LTE PDCP and MAC (buffer size) has been defined as "data available for transmission," it has been discussed that the amount of data waiting to be transmitted between the NR PDCP and MAC be specified as "data volume." For example, when the NR PDCP is used as the unified PDCP, one or both of the LTE MAC and NR PDCP (i.e., the unified PDCP) in the EN-DC MeNB and UE MCG can operate with respect to these differences.

[0207] The MN 1 and SN 2 described in the above embodiments can be implemented based on the Cloud Radio Access Network (C-RAN) concept. C-RAN is also known as a centralized RAN. In this case, the processing and operations performed by MN 1 and SN 2 as described in the above embodiments can be provided by a digital unit (DU) included in the C-RAN architecture, or by a combination of a DU and a radio unit (RU). A DU is also known as a baseband unit (BBU) or a central unit (CU). A RU is also known as a remote radio headend (RRH), a remote radio equipment (RRE), a distributed unit (DU), or a transmit and receive point (TRP). That is, the processing and operations performed by MN 1 and SN 2 as described in the above embodiments can be provided by one or more radio stations (or RAN nodes).

[0208] Furthermore, the above embodiments are merely examples of applications of the technical ideas obtained by the inventors. These technical ideas are not limited to the above embodiments, and various modifications can be made to these technical ideas.

[0209] For example, all or part of the above embodiments may be described in, but not limited to, the following supplementary description.

[0210] (Supplementary Note 1)

[0211] A primary radio access network node, or primary RAN node, associated with a primary radio access technology, or primary RAT, includes: a memory; and at least one processor coupled to the memory and configured to: communicate with a secondary RAN node associated with a secondary RAT, and provide dual connectivity to a radio terminal using both the primary and secondary RATs; in the case that the radio terminal does not support split bearers, use a PDCP entity for providing a first packet data aggregation protocol function, or a first PDCP function, corresponding to the primary RAT for the primary cell group bearer used by the radio terminal; and in the case that the radio terminal supports split bearers, regardless of whether the split bearer is initiated for the radio terminal... Dual connectivity is provided, for the primary cell group bearer used by the radio terminal, using a PDCP entity to provide unified PDCP functionality, wherein the unified PDCP functionality is used for both primary cell group split bearers and secondary cell group split bearers, wherein the primary cell group split bearer is a user plane bearer that the radio protocol splits at the primary RAN node and belongs to both the primary cell group provided by the primary RAN node and the secondary cell group provided by the secondary RAN node, wherein the secondary cell group split bearer is a user plane bearer that the radio protocol splits at the secondary RAN node and belongs to both the secondary cell group and the primary cell group, and wherein the primary cell group bearer is a user plane bearer in which the radio protocol resides only in the primary cell group.

[0212] (Supplementary Note 2)

[0213] According to the primary RAN node described in Supplementary Explanation 1, the unified PDCP function is a common function of both the first PDCP function corresponding to the primary RAT and the second PDCP function corresponding to the secondary RAT.

[0214] (Supplementary Note 3)

[0215] According to the primary RAN node described in Supplementary Explanation 1, the unified PDCP function is a common subset between the first PDCP function corresponding to the primary RAT and the second PDCP function corresponding to the secondary RAT.

[0216] (Supplementary Note 4)

[0217] According to the primary RAN node described in Supplementary Explanation 1, the second PDCP function corresponding to the secondary RAT is a subset of the first PDCP function corresponding to the primary RAT, and the unified PDCP function is the same as or a subset of the second PDCP function corresponding to the secondary RAT.

[0218] (Supplementary Note 5)

[0219] According to any one of Supplementary Notes 1 to 4, the primary RAN node, wherein the at least one processor is configured to: during the Radio Resource Control (RRC) connection establishment process, receive from the radio terminal terminal terminal terminal capability information indicating whether the radio terminal supports split bearers.

[0220] (Supplementary Note 6)

[0221] According to the primary RAN node described in Supplementary Note 5, the at least one processor is configured to: receive an RRC connection request message containing terminal capability information from the radio terminal; and, if the terminal capability information indicates that the radio terminal supports split bearers, send an RRC connection setting message to the radio terminal, wherein the RRC connection setting message contains information indicating the use of the unified PDCP function or contains PDCP configuration corresponding to the unified PDCP function.

[0222] (Supplementary Note 7)

[0223] According to the primary RAN node described in Supplementary Note 6, the at least one processor is configured to perform access layer security activation with the radio terminal via a signaling radio bearer to which the PDCP configuration corresponding to the unified PDCP function is applied.

[0224] (Supplementary Note 8)

[0225] According to any one of Supplementary Notes 5 to 7, the primary RAN node, wherein the terminal capability information is defined as an RRC information element.

[0226] (Supplementary Note 9)

[0227] According to any one of Supplementary Explanations 5 to 7, the primary RAN node, wherein the terminal capability information is defined as a Media Access Control (MAC) CE.

[0228] (Supplementary Note 10)

[0229] According to any one of Supplementary Explanations 5 to 7, the primary RAN node, wherein the terminal capability information is defined as the logical channel ID (LCID) of the common control channel (CCCH).

[0230] (Supplementary Note 11)

[0231] A radio terminal includes: at least one radio transceiver configured to communicate with both a primary radio access network node (i.e., a primary RAN node) associated with a primary radio access technology (i.e., a primary RAT) and a secondary RAN node associated with a secondary RAT; and at least one processor configured to: perform dual connectivity using the primary RAT and the secondary RAT via the at least one radio transceiver; in the case that the radio terminal does not support split bearers, use a PDCP entity for providing a first packet data aggregation protocol function (i.e., a first PDCP function) corresponding to the primary RAT for the primary cell group bearer used by the radio terminal; and in the case that the radio terminal supports split bearers, regardless of whether it is for the primary RAT or not... The terminal initiates dual connectivity, using a PDCP entity to provide unified PDCP functionality for the primary cell group bearer used by the radio terminal. This unified PDCP functionality is used for both primary cell group split bearers and secondary cell group split bearers. The primary cell group split bearer is a user plane bearer that splits at the primary RAN node and belongs to both the primary cell group provided by the primary RAN node and the secondary cell group provided by the secondary RAN node. The secondary cell group split bearer is a user plane bearer that splits at the secondary RAN node and belongs to both the secondary cell group and the primary cell group. The primary cell group bearer is a user plane bearer where the radio protocol resides only within the primary cell group.

[0232] (Supplementary Note 12)

[0233] According to the radio terminal described in Supplementary Note 11, the at least one processor is configured to: during the Radio Resource Control (RRC) connection establishment process, send terminal capability information indicating whether the radio terminal supports split bearers to the primary RAN node.

[0234] (Supplementary Note 13)

[0235] According to the radio terminal described in Supplementary Note 12, the at least one processor is configured to: send an RRC connection request message containing terminal capability information to the primary RAN node; and receive an RRC connection setting message from the primary RAN node, wherein the RRC connection setting message contains information indicating the use of the unified PDCP function or contains PDCP configuration corresponding to the unified PDCP function.

[0236] (Supplementary Note 14)

[0237] According to the radio terminal described in Supplementary Note 13, the at least one processor is configured to perform access layer security activation with the primary RAN node via a signaling radio bearer to which the PDCP configuration corresponding to the unified PDCP function is applied.

[0238] (Supplementary Note 15)

[0239] A method for a primary radio access network node (RAN node) associated with a primary radio access technology (RAT), the method comprising: communicating with a secondary RAN node associated with a secondary RAT and providing dual connectivity to a radio terminal using the primary RAT and the secondary RAT; when the radio terminal does not support split bearers, using a PDCP entity for providing a first packet data aggregation protocol function (PDCP) corresponding to the primary RAT for the primary cell group bearer used by the radio terminal; and when the radio terminal supports split bearers, regardless of whether dual connectivity is initiated for the radio terminal, for the radio... The primary cell group bearer used by the terminal uses a PDCP entity for providing unified PDCP functionality, wherein the unified PDCP functionality is used for both primary cell group split bearers and secondary cell group split bearers, wherein the primary cell group split bearer is a user plane bearer for which the radio protocol is split at the primary RAN node and belongs to both the primary cell group provided by the primary RAN node and the secondary cell group provided by the secondary RAN node, wherein the secondary cell group split bearer is a user plane bearer for which the radio protocol is split at the secondary RAN node and belongs to both the secondary cell group and the primary cell group, and wherein the primary cell group bearer is a user plane bearer for which the radio protocol is located only in the primary cell group.

[0240] (Supplementary Note 16)

[0241] A method for a radio terminal, the method comprising: establishing dual connectivity using a primary radio access technology (i.e., a primary RAT) and a secondary RAT via a radio transceiver, the radio transceiver being configured to communicate with both a primary radio access network node (i.e., a primary RAN node) associated with the primary RAT and a secondary RAN node associated with the secondary RAT; if the radio terminal does not support split bearers, using a PDCP entity for providing a first packet data aggregation protocol function (i.e., a first PDCP function) corresponding to the primary RAT for the primary cell group bearer used by the radio terminal; and if the radio terminal supports split bearers, regardless of whether dual connectivity is initiated for the radio terminal, targeting... The primary cell group bearer used by the radio terminal uses a PDCP entity for providing unified PDCP functionality, wherein the unified PDCP functionality is used for both primary cell group split bearers and secondary cell group split bearers, wherein the primary cell group split bearer is a user plane bearer that is split at the primary RAN node and belongs to both the primary cell group provided by the primary RAN node and the secondary cell group provided by the secondary RAN node, wherein the secondary cell group split bearer is a user plane bearer that is split at the secondary RAN node and belongs to both the secondary cell group and the primary cell group, and wherein the primary cell group bearer is a user plane bearer in which the radio protocol is located only in the primary cell group.

[0242] (Supplementary Note 17)

[0243] A program is used to enable a computer to perform a method for a primary radio access network node (PRN node) associated with a primary radio access technology (PRT), wherein the method includes: communicating with a secondary RAT associated with a secondary RAT and providing a radio terminal with dual connectivity using the primary RAT and the secondary RAT; if the radio terminal does not support split bearers, using a PDCP entity for providing a first packet data aggregation protocol function (PDCP function) corresponding to the primary RAT for the primary cell group bearer used by the radio terminal; and if the radio terminal supports split bearers, regardless of whether dual connectivity is initiated for the radio terminal, for the primary cell group bearer used by the radio terminal, using a PDCP entity for providing a first packet data aggregation protocol function (PDCP function) corresponding to the primary RAT. The primary cell group bearer used by the radio terminal uses a PDCP entity for providing unified PDCP functionality, wherein the unified PDCP functionality is used for both primary cell group split bearers and secondary cell group split bearers, wherein the primary cell group split bearer is a user plane bearer that the radio protocol splits at the primary RAN node and belongs to both the primary cell group provided by the primary RAN node and the secondary cell group provided by the secondary RAN node, wherein the secondary cell group split bearer is a user plane bearer that the radio protocol splits at the secondary RAN node and belongs to both the secondary cell group and the primary cell group, and wherein the primary cell group bearer is a user plane bearer in which the radio protocol resides only in the primary cell group.

[0244] (Supplementary Note 18)

[0245] A program for enabling a computer to use a method for a radio terminal, wherein the method includes: establishing dual connectivity via a radio transceiver using a primary radio access technology (i.e., a primary RAT) and a secondary RAT, the radio transceiver being configured to communicate with both a primary radio access network node (i.e., a primary RAN node) associated with the primary RAT and a secondary RAN node associated with the secondary RAT; if the radio terminal does not support split bearers, using a PDCP entity for providing a first packet data aggregation protocol function (i.e., a first PDCP function) corresponding to the primary RAT for the primary cell group bearer used by the radio terminal; and if the radio terminal supports split bearers, regardless of whether it is for the radio terminal... Dual connectivity is initiated, and a PDCP entity for providing unified PDCP functionality is used for the primary cell group bearer used by the radio terminal. This unified PDCP functionality is used for both primary cell group split bearers and secondary cell group split bearers. The primary cell group split bearer is a user plane bearer that splits at the primary RAN node and belongs to both the primary cell group provided by the primary RAN node and the secondary cell group provided by the secondary RAN node. The secondary cell group split bearer is a user plane bearer that splits at the secondary RAN node and belongs to both the secondary cell group and the primary cell group. The primary cell group bearer is a user plane bearer where the radio protocol resides only in the primary cell group.

[0246] This application is based on and claims priority to Japanese Patent Application 2017-118095, filed on June 15, 2017, the disclosure of which is incorporated herein by reference in its entirety.

[0247] List of reference numerals

[0248] 1. Master Node (MN)

[0249] 2. Secondary Nodes (SN)

[0250] 3 User Equipment (UE)

[0251] 4 Core Network

[0252] 5. Control Surface (CP) Nodes

[0253] 6 User plane (UP) nodes

[0254] 1401 RF transceiver

[0255] 1404 processor

[0256] 1405 Memory

[0257] 1501 RF Transceiver

[0258] 1503 Baseband Processor

[0259] 1504 Application Processor

[0260] 1506 memory

[0261] 1602 processor

[0262] 1603 memory

Claims

1. A method for a user equipment (UE), the method comprising: Connected to the first radio access node of MN, which acts as the master node serving the main cell group (MCG) in the multi-radio dual connectivity (MR-DC). Connected to the second radio access node, which acts as a secondary node (SN) serving the secondary cell group (SCG) in the MR-DC; and The network sends UE capability information for the MR-DC, wherein the UE capability information includes information elements indicating that the UE supports transmission via both the MCG path and the SCG path for split bearers in the MR-DC, wherein a first packet data convergence protocol function, i.e., a first PDCP function, is used for the split bearers on both the MCG path and the SCG path, wherein the first PDCP function is the New Radio PDCP, i.e., NR PDCP, and wherein, in the case that the MR-DC is E-UTRA-NR dual connectivity, i.e., EN-DC, the MCG path is associated with Evolved Universal Terrestrial Radio Access, i.e., E-UTRA, and the SCG path is associated with NR.

2. The method according to claim 1, wherein In the case where the MR-DC is an MR-DC with an Evolved Packet Core (EPC), the second PDCP function or the first PDCP function is used for the MCG bearers in the MR-DC, and The second PDCP function is E-UTRA PDCP.

3. The method according to claim 1, wherein, The first PDCP function is used for the SCG bearer in the MR-DC.

4. The method according to claim 1, wherein, The splitting carrier terminates in the MN or in the SN.

5. The method according to claim 1, wherein The first type of splitting carrier terminates in the MN, and The second type of split carrier is terminated in the SN.

6. The method according to claim 1, wherein, In the case where the MR-DC is an MR-DC with a 5G core network, namely 5GC, the first PDCP function is used for the MCG bearer in the MR-DC.

7. The method according to claim 1, wherein The UE is provided with NR access from one of the first radio access node and the second radio access node, and The UE is provided with E-UTRA access or NR access from the other of the first radio access node and the second radio access node.

8. The method according to claim 1, wherein, In the case of EN-DC, the MCG path is associated with the NR PDCP, E-UTRA Radio Link Control (E-UTRA RLC), and E-UTRA Medium Access Control (E-UTRA MAC), and the SCG path is associated with the NR PDCP, NR RLC, and NR MAC.

9. The method according to claim 8, wherein, In the case of EN-DC, the NR PDCP, the E-UTRA RLC, and the E-UTRA MAC are used for the MCG path, and the NR PDCP, the NR RLC, and the NR MAC are used for the SCG path.

10. A user equipment, comprising: Components for connecting to the first radio access node that acts as the master node of the primary cell group (MCG) in multiple radio dual connectivity (MR-DC). Components for connecting to a second radio access node that acts as a secondary node (SN) serving the secondary cell group (SCG) in the MR-DC. as well as A component for transmitting UE capability information for the MR-DC to the network, wherein the UE capability information includes information elements indicating that the UE supports transmission via both the MCG path and the SCG path for split bearers in the MR-DC, wherein a first packet data convergence protocol function, i.e., a first PDCP function, is used for the split bearers on both the MCG path and the SCG path, wherein the first PDCP function is the New Radio PDCP, i.e., NR PDCP, and wherein, in the case that the MR-DC is E-UTRA-NR dual connectivity, i.e., EN-DC, the MCG path is associated with Evolved Universal Terrestrial Radio Access, i.e., E-UTRA, and the SCG path is associated with NR.

11. The user equipment according to claim 10, in, In the case where the MR-DC is an MR-DC with an Evolved Packet Core (EPC), the second PDCP function or the first PDCP function is used for the MCG bearers in the MR-DC, and The second PDCP function is E-UTRA PDCP.

12. The user equipment according to claim 10, wherein, The first PDCP function is used for the SCG bearer in the MR-DC.

13. The user equipment according to claim 10, wherein, The splitting carrier terminates in the MN or in the SN.

14. The user equipment according to claim 10, in, The first type of splitting carrier terminates in the MN, and The second type of split carrier is terminated in the SN.

15. The user equipment according to claim 10, wherein, In the case where the MR-DC is an MR-DC with a 5G core network, namely 5GC, the first PDCP function is used for the MCG bearer in the MR-DC.

16. The user equipment according to claim 10, in, The UE is provided with NR access from one of the first radio access node and the second radio access node, and The UE is provided with E-UTRA access or NR access from the other of the first radio access node and the second radio access node.

17. The user equipment according to claim 10, wherein, In the case of EN-DC, the MCG path is associated with the NR PDCP, E-UTRA Radio Link Control (E-UTRA RLC), and E-UTRA Medium Access Control (E-UTRA MAC), and the SCG path is associated with the NR PDCP, NR RLC, and NR MAC.

18. The user equipment according to claim 17, wherein, In the case of EN-DC, the NR PDCP, the E-UTRA RLC, and the E-UTRA MAC are used for the MCG path, and the NR PDCP, the NR RLC, and the NR MAC are used for the SCG path.

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