Patent Description:
In telecommunication systems, the Packet Data Convergence Protocol (PDCP) sublayer of the radio protocol stack provides services such as transfer of user-plane data, ciphering, integrity protection, etc. For example, the PDCP layer defined for the Evolved Universal Terrestrial Radio Access (EUTRA) radio interface (see 3GPP specification TS <NUM>) and New Radio (NR) (see 3GPP specification TS <NUM>) provides sequencing of protocol data units (PDUs) in the uplink direction (from a user device, also known as a user equipment (UE), to a base station) as well as in the downlink direction (from the base station to the UE). Further, the PDCP sublayer provides services for signaling radio bearers (SRBs) to the Radio Resource Control (RRC) sublayer. The PDCP sublayer also provides services for data radio bearers (DRBs) to a Service Data Adaptation Protocol (SDAP) sublayer or a protocol layer such as an Internet Protocol (IP) layer, an Ethernet protocol layer, and an Internet Control Message Protocol (ICMP) layer. Generally speaking, the UE and a base station can use SRBs to exchange RRC messages as well as non-access stratum (NAS) messages, and can use DRBs to transport data on a user plane.

The UE in some scenarios can concurrently utilize resources of multiple nodes (e.g., base stations or components of a distributed base station or disaggregated base station) of a radio access network (RAN), interconnected by a backhaul. When these network nodes support different radio access technologies (RATs), this type of connectivity is referred to as Multi-Radio Dual Connectivity (MR-DC). When operating in MR-DC, the cell(s) associated with the base station operating as a master node (MN) define a master cell group (MCG), and the cells associated with the base station operating as a secondary node (SN) define the secondary cell group (SCG). The MCG covers a primary cell (PCell) and zero, one, or more secondary cells (SCells), and the SCG covers a primary secondary cell (PSCell) and zero, one, or more SCells. The UE communicates with the MN (via the MCG) and the SN (via the SCG). In other scenarios, the UE utilizes resources of one base station at a time, i.e., single connectivity (SC). The UE in SC only communicates with the MN (via the MCG). One base station and/or the UE determines that the UE should establish a radio connection with another base station. For example, one base station can determine to hand the UE over to the second base station, and initiate a handover procedure. The UE in other scenarios can concurrently utilize resources of a RAN node (e.g., a single base station or a component of a distributed base station or a disaggregated base station), interconnected by a backhaul.

UEs can use several types of SRBs and DRBs. So-called SRB1 resources carry RRC messages, which in some cases include NAS messages over the dedicated control channel (DCCH), and SRB2 resources support RRC messages that include logged measurement information or NAS messages, also over the DCCH but with lower priority than SRB1 resources. More generally, SRB <NUM> and SRB2 resources allow the UE and the MN to exchange RRC messages related to the MN and embed RRC messages related to the SN, and also can be referred to as MCG SRBs. SRB3 resources allow the UE and the SN to exchange RRC messages related to the SN, and can be referred to as SCG SRBs. Split SRBs allow the UE to exchange RRC messages directly with the MN via lower layer resources of the MN and the SN. Further, DRBs terminated at the MN and using the lower-layer resources of only the MN can be referred as MCG DRBs, DRBs terminated at the SN and using the lower-layer resources of only the SN can be referred as SCG DRBs, and DRBs terminated at the MN or SN but using the lower-layer resources of both the MN and the SN can be referred to as split DRBs. DRBs terminated at the MN but using the lower-layer resources of only the SN can be referred to as MN-terminated SCG DRBs. DRBs terminated at the SN but using the lower-layer resources of only the MN can be referred to as SN-terminated MCG DRBs.

UEs can perform handover procedures to switch from one cell to another, whether in single connectivity (SC) or DC operation. These procedures involve messaging (e.g., RRC signaling and preparation) among RAN nodes and the UE. The UE may handover from a cell of a serving base station to a target cell of a target base station, or from a cell of a first distributed unit (DU) of a serving base station to a target cell of a second DU of the same base station, depending on the scenario. In DC scenarios, UEs can perform PSCell change procedures to change PSCells. These procedures involve messaging (e.g., RRC signaling and preparation) among RAN nodes and the UE. The UE may perform PSCell change from a PSCell of a serving SN to a target PSCell of a target SN, or from a PSCell of a source DU of a base station to a PSCell of a target DU of the same base station, depending on the scenario. Further, the UE may perform handover or PSCell change within a cell for synchronous reconfiguration.

Base stations that operate according to fifth-generation (<NUM>) New Radio (NR) requirements support significantly larger bandwidth than fourth-generation (<NUM>) base stations. Accordingly, the Third Generation Partnership Project (3GPP) has proposed that for Release <NUM>, user equipment units (UEs) support a <NUM> bandwidth in frequency range <NUM> (FR1) and a <NUM> bandwidth in frequency range (FR2). Due to the relatively wide bandwidth of a typical carrier, 3GPP has proposed that for Release <NUM>, a <NUM> NR base station can provide multicast and/or broadcast services (MBS) to UEs that can be useful in many content delivery applications, such as transparent IPv4/IPv6 multicast delivery, IPTV, software delivery over wireless, group communications, IoT applications, V2X applications, and emergency messages related to public safety.

However, in some cases, it is not clear how a UE and a base station should configure and manage flows of MBS packets.

<CIT> discusses establishing a MBS connection with a terminal (UE).

<CIT> discloses a method and apparatus for switching between unicast and multicast by considering degraded user experience in a wireless communication system.

<CIT> discloses a method and apparatus for switching between unicast and multicast in a wireless communication system.

<CIT> describes an apparatus and method to support establishment of Radio Bearers at a Base Station and UE to support Multicast data transmission corresponding to a Multicast session modified or established by a <NUM> Core Network.

<CIT> describes a method and apparatus for receiving an MBS service at a UE including, when a handover is detected, receiving via a source base station radio bearer configuration information for receiving MBS session data through a target base station, configuring a bearer accordingly, and receiving the MBS session data over the radio bearer.

A RAN and/or a UE implement the techniques of this disclosure for managing transmission and reception of MBS. A UE can perform a session establishment procedure (e.g., a PDU session establishment procedure) with a core network (CN) via a base station of the RAN. The base station can use a DRB associated with the session to transmit the MBS data packets to the UE. The DRB can be a unicast DRB (i.e., a dedicated DRB allocated to the UE) or a multicast DRB (also referred to herein as an "MRB").

During the session establishment procedure, the base station can send configuration parameters to the UE configuring a first DRB associated with the session. The UE can use this first DRB to transmit an MBS request for an MBS service to the base station. In response to the MBS request, the base station can transmit MBS data packets for the MBS service via the first DRB, or the base station can configure a second DRB associated with the session and can transmit the MBS data packets to the UE via the second DRB.

In some implementations, the base station can use the first or second DRB associated with the session to transmit unicast data packets associated with a unicast service to the UE. Further, the CN can establish multiple PDU sessions for multiple UEs via the base station, respectively. The base station can configure one or more DRBs for the PDU sessions. The base station transmits the same configuration parameters to a first subset of UEs and transmits MBS data packets to the UEs in accordance with the configuration parameters (i.e., the configuration parameters can be for a shared, multicast DRB). For a second subset of UEs, the base station can transmit unicast configuration parameters to each respective UE (i.e., the configuration parameters can be for respective unicast DRBs).

Generally speaking, the techniques of this disclosure allow UEs to receive MBS information via radio resources allocated by a base station of a RAN. To this end, the base station can configure different radio resources in one or multiple overlapping cells to multicast or broadcast ("multicast" or "broadcast" interchangeably referred to as "transmit") MBS data (and associated control information) and/or unicast ("unicast" interchangeably referred to as "transmit") non-MBS data (and associated control information) with one or multiple UEs on the downlink (DL). The base station can also unicast MBS data (and associated control information) to a UE on a dedicated DRB for the UE. The one or more multiple UEs can transmit (i.e., unicast) non-MBS data to the base station on the uplink (UL).

Accordingly, a base station of this disclosure can configure one or more radio bearers to transmit MBS information (i.e., MBS data packets and/or control information) to a UE. A radio bearer that carries MBS information to the UE can be a unicast DRB (i.e., a dedicated DRB for the UE) or a multicast DRB (i.e., a DRB that may be shared by multiple UEs, also referred to as an MBS radio bearer or MRB). For example, the base station can transmit unicast configuration parameters or multicast configuration parameters to the UE to configure the UE to receive MBS information via a unicast DRB or a multicast DRB, respectively. As used in this disclosure, the term DRB may refer to a unicast DRB or a multicast DRB, unless specifically noted otherwise.

<FIG> depicts an example wireless communication system <NUM> that can implement MBS operation techniques of this disclosure. The wireless communication system <NUM> includes UE 102A and UE 102B, as well as base stations <NUM>, 106A, 106B of a radio access network (RAN) (e.g., RAN <NUM>) that are connected to a core network (CN) <NUM>. To ease readability, UE <NUM> is used herein to represent the UE 102A, the UE 102B, or both the UE 102A and UE 102B, unless otherwise specified. The base stations <NUM>, 106A, 106B can be any suitable type, or types, of base stations, such as an evolved node B (eNB), a nextgeneration eNB (ng-eNB), or a <NUM> Node B (gNB), for example. As a more specific example, the base station <NUM> can be an eNB or a gNB, and the base stations 106A and 106B can be gNBs.

The base station <NUM> supports a cell <NUM>, the base station 106A supports a cell 126A, and the base station 106B supports a cell 126B. The cell <NUM> partially overlaps with both of cells 126A and 126B, such that the UE <NUM> can be in range to communicate with base station <NUM> while simultaneously being in range to communicate with base station 106A or 106B (or in range to detect or measure the signal from both base stations 106A and 106B). The overlap can make it possible for the UE <NUM> to hand over between cells (e.g., from cell <NUM> to cell 126A or 126B) or base stations (e.g., from base station <NUM> to base station 106A or base station 106B) before the UE <NUM> experiences radio link failure, for example. Moreover, the overlap allows the various dual connectivity (DC) scenarios discussed below. For example, the UE <NUM> can communicate in DC with the base station <NUM> (operating as an MN) and the base station 106A (operating as an SN) and, upon completing a handover to base station 106B, can communicate with the base station 106B (operating as an MN). As another example, the UE <NUM> can communicate in DC with the base station <NUM> (operating as an MN) and the base station 106A (operating as an SN) and, upon completing an SN change, can communicate with the base station <NUM> (operating as an MN) and the base station 106B (operating as an SN).

More particularly, when the UE <NUM> is in DC with the base station <NUM> and the base station 106A, the base station <NUM> operates as a master eNB (MeNB), a master ng-eNB (Mng-eNB), or a master gNB (MgNB), and the base station 106A operates as a secondary gNB (SgNB) or a secondary ng-eNB (Sng-eNB).

In non-MBS (i.e., unicast) operation, the UE <NUM> can use a radio bearer (e.g., a DRB or an SRB) that at different times terminates at an MN (e.g., the base station <NUM>) or an SN (e.g., the base station 106A). For example, after handover or SN change to the base station 106B, the UE <NUM> can use a radio bearer (e.g., a DRB or an SRB) that at different times terminates at the base station 106B. The UE <NUM> can apply one or more security keys when communicating on the radio bearer, in the UL (from the UE <NUM> to a base station) and/or DL (from a base station to the UE <NUM>) direction. In the non-MBS operation, the UE <NUM> transmits data via the radio bearer on (i.e., within) an uplink BWP of a cell to the base station and/or receives data via the radio bearer on a DL BWP of the cell from the base station. The UL BWP can be an initial UL BWP or a dedicated UL BWP, and the DL BWP can be an initial DL BWP or a dedicated DL BWP. The UE <NUM> can receive paging, system information, public warning message(s), or a random access response on the DL BWP. In such non-MBS operation, the UE <NUM> can be in a connected state. Alternatively, the UE <NUM> can be in an idle or inactive state if the UE <NUM> supports small data transmission in the idle or inactive state.

In MBS operation, the UE <NUM> can use a radio bearer (e.g., a DRB or an MRB) that at different times terminates at an MN (e.g., the base station <NUM>) or an SN (e.g., the base station 106A). For example, after handover or SN change to the base station 106B, the UE <NUM> can use a radio bearer (e.g., a DRB or an MRB) that at different times terminates at the base station 106B which can be an MN or SN. The base station can utilize the radio bearer to transmit application-level messages, such as security keys, to the UE <NUM>. In some implementations, the base station (e.g., the MN or SN) can transmit MBS data over dedicated radio resources (i.e., the radio resources dedicated to the UE <NUM>) to the UE <NUM> (e.g., via the DRB or MRB). In such implementations, the base station can apply one or more security keys to protect integrity of MBS data and/or encrypt MBS data and transmits the encrypted and/or integrity protected MBS data over the dedicated radio resources to the UE <NUM>. Correspondingly, the UE <NUM> can apply the one or more security keys to decrypt MBS data and/or check integrity of the MBS data when receiving the MBS data on the radio bearer, in the downlink (from a base station to the UE <NUM>) direction. In other implementations, the base station (e.g., the MN or SN) can transmit MBS data over common radio resources (i.e., the radio resources common to the UE <NUM> and other UE(s)) or a DL BWP of a cell from the base station to the UE <NUM> (e.g., via the DRB or MRB). The DL BWP can be an initial DL BWP, a dedicated DL BWP, or an MBS DL BWP (i.e., a DL BWP specific for MBS or not for unicast). In such implementations, the base station can refrain from applying a security key to MBS data and transmit the MBS data on the radio bearer. Correspondingly, the UE <NUM> can omit applying a security key to MBS data received on the radio bearer. The UE <NUM> can apply an application-level security key, received from the CN <NUM> or an MBS server, to MBS data received on the radio bearer.

The base station <NUM> includes processing hardware <NUM>, which can include one or more general-purpose processors (e.g., central processing units (CPUs)) and a computer-readable memory storing machine-readable instructions executable on the one or more general-purpose processor(s), and/or special-purpose processing units. The processing hardware <NUM> in the example implementation in <FIG> includes a base station MBS controller <NUM> that is configured to manage or control transmission of MBS information received from the CN <NUM> or an edge server. For example, the base station MBS controller <NUM> can be configured to support Radio Resource Control (RRC) configurations, procedures and messaging associated with MBS procedures, and/or to support the necessary operations, as discussed below. The processing hardware <NUM> can include a base station non-MBS controller <NUM> configured to manage or control one or more RRC configurations and/or RRC procedures when the base station <NUM> operates as an MN or SN during a non-MBS operation.

The base station 106A includes processing hardware <NUM>, which can include one or more general-purpose processors (e.g., CPUs) and a computer-readable memory storing machine-readable instructions executable on the general-purpose processor(s), and/or special-purpose processing units. The processing hardware <NUM> in the example implementation of <FIG> includes a base station MBS controller <NUM> that is configured to manage or control transmission of MBS information received from the CN <NUM> or an edge server. For example, the base station MBS controller <NUM> can be configured to support RRC configurations, procedures and messaging associated with MBS procedures, and/or to support the necessary operations, as discussed below. The processing hardware <NUM> can include a base station non-MBS controller <NUM> configured to manage or control one or more RRC configurations and/or RRC procedures when the base station 106A operates as an MN or SN during a non-MBS operation. While not shown in <FIG>, the base station 106B can include processing hardware similar to the processing hardware <NUM> of the base station <NUM> or the processing hardware <NUM> of the base station 106A.

The UE <NUM> includes processing hardware <NUM>, which can include one or more general-purpose processors (e.g., CPUs) and a computer-readable memory storing machine-readable instructions executable on the general-purpose processor(s), and/or special-purpose processing units. The processing hardware <NUM> in the example implementation of <FIG> includes a UE MBS controller <NUM> that is configured to manage or control reception of MBS information. For example, the UE MBS controller <NUM> can be configured to support RRC configurations, procedures and messaging associated with MBS procedures, and/or to support the necessary operations, as discussed below. The processing hardware <NUM> can include a UE non-MBS controller <NUM> configured to manage or control one or more RRC configurations and/or RRC procedures in accordance with any of the implementations discussed below, when the UE <NUM> communicates with an MN and/or an SN during a non-MBS operation.

The CN <NUM> can be an evolved packet core (EPC) <NUM> or a fifth-generation core (5GC) <NUM>, both of which are depicted in <FIG>. The base station <NUM> can be an eNB supporting an S1 interface for communicating with the EPC <NUM>, an ng-eNB supporting an NG interface for communicating with the 5GC <NUM>, or a gNB that supports an NR radio interface as well as an NG interface for communicating with the 5GC <NUM>. The base station 106A can be an EUTRA-NR DC (EN-DC) gNB (en-gNB) with an S1 interface to the EPC <NUM>, an en-gNB that does not connect to the EPC <NUM>, a gNB that supports the NR radio interface and an NG interface to the 5GC <NUM>, or a ng-eNB that supports an EUTRA radio interface and an NG interface to the 5GC <NUM>. To directly exchange messages with each other during the scenarios discussed below, the base stations <NUM>, 106A, and 106B can support an X2 or Xn interface.

Among other components, the EPC <NUM> can include a Serving Gateway (SGW) <NUM>, a Mobility Management Entity (MME) <NUM>, and a Packet Data Network Gateway (PGW) <NUM>. The SGW <NUM> is generally configured to transfer user-plane packets related to audio calls, video calls, Internet traffic, etc., and the MME <NUM> is configured to manage authentication, registration, paging, and other related functions. The PGW <NUM> provides connectivity from the UE to one or more external packet data networks, e.g., an Internet network and/or an Internet Protocol (IP) Multimedia Subsystem (IMS) network. The 5GC <NUM> includes a User Plane Function (UPF) <NUM> and an Access and Mobility Management (AMF) <NUM>, and/or Session Management Function (SMF) <NUM>. The UPF <NUM> is generally configured to transfer user-plane packets related to audio calls, video calls, Internet traffic, etc., the AMF <NUM> is configured to manage authentication, registration, paging, and other related functions, and the SMF <NUM> is configured to manage PDU sessions. The UPF <NUM>, AMF <NUM> and/or the SMF <NUM> can be configured to support MBS. For example, the SMF <NUM> can be configured to manage or control MBS transport, configure the UPF <NUM> and/or RAN <NUM> for MBS flows, and/or manage or configure MBS session(s) or PDU Session(s) for MBS for UE <NUM>. The UPF <NUM> is configured to transfer MBS data packets to audio, video, Internet traffic, etc. to the RAN <NUM>. The UPF <NUM> and/or SMF <NUM> can be configured for both unicast service and MBS, or for MBS only.

Generally, the wireless communication network <NUM> can include any suitable number of base stations supporting NR cells and/or EUTRA cells. More particularly, the EPC <NUM> or the 5GC <NUM> can be connected to any suitable number of base stations supporting NR cells and/or EUTRA cells. Although the examples below refer specifically to specific CN types (EPC, 5GC) and RAT types (<NUM> NR and EUTRA), in general the techniques of this disclosure can also apply to other suitable radio access and/or core network technologies such as sixth generation (<NUM>) radio access and/or <NUM> core network or <NUM> NR-<NUM> DC, for example.

In different configurations or scenarios of the wireless communication system <NUM>, the base station <NUM> can operate as an MeNB, an Mng-eNB, or an MgNB, the base station 106B can operate as an MeNB, an Mng-eNB, an MgNB, an SgNB, or an Sng-eNB, and the base station 106A can operate as an SgNB or an Sng-eNB. The UE <NUM> can communicate with the base station <NUM> and the base station 106A or 106B via the same radio access technology (RAT), such as EUTRA or NR, or via different RATs.

When the base station <NUM> is an MeNB and the base station 106A is an SgNB, the UE <NUM> can be in EN-DC with the MeNB <NUM> and the SgNB 106A. When the base station <NUM> is an Mng-eNB and the base station 106A is an SgNB, the UE <NUM> can be in next generation (NG) EUTRA-NR DC (NGEN-DC) with the Mng-eNB <NUM> and the SgNB 106A. When the base station <NUM> is an MgNB and the base station 106A is an SgNB, the UE <NUM> can be in NR-NR DC (NR-DC) with the MgNB <NUM> and the SgNB 106A. When the base station <NUM> is an MgNB and the base station 106A is an Sng-eNB, the UE <NUM> can be in NR-EUTRA DC (NE-DC) with the MgNB <NUM> and the Sng-eNB 106A.

<FIG> depicts an example, distributed implementation of any one or more of the base stations <NUM>, 106A, 106B. In this implementation, the base station <NUM>, 106A, or 106B includes a central unit (CU) <NUM> and one or more distributed units (DUs) <NUM>. The CU <NUM> includes processing hardware, such as one or more general-purpose processors (e.g., CPUs) and a computer-readable memory storing machine-readable instructions executable on the general-purpose processor(s), and/or special-purpose processing units. For example, the CU <NUM> can include the processing hardware <NUM> or <NUM> of <FIG>.

Each of the DUs <NUM> also includes processing hardware that can include one or more general-purpose processors (e.g., CPUs) and computer-readable memory storing machine-readable instructions executable on the one or more general-purpose processors, and/or special-purpose processing units. For example, the processing hardware can include a medium access control (MAC) controller configured to manage or control one or more MAC operations or procedures (e.g., a random access procedure), and a radio link control (RLC) controller configured to manage or control one or more RLC operations or procedures when the base station (e.g., base station 106A) operates as an MN or an SN. The processing hardware can also include a physical layer controller configured to manage or control one or more physical layer operations or procedures.

In some implementations, the CU <NUM> can include a logical node CU-CP 172A that hosts the control plane part of the Packet Data Convergence Protocol (PDCP) protocol of the CU <NUM> and/or radio resource control (RRC) protocol of the CU <NUM>. The CU <NUM> can also include logical node(s) CU-UP 172B that hosts the user plane part of the PDCP protocol and/or Service Data Adaptation Protocol (SDAP) protocol of the CU <NUM>. The CU-CP 172A can transmit the non-MBS control information and MBS control information, and the CU-UP 172B can transmit the non-MBS data packets and MBS data packets, as described herein.

The CU-CP 172A can be connected to multiple CU-UP 172B through the E1 interface. The CU-CP 172A selects the appropriate CU-UP 172B for the requested services for the UE <NUM>. In some implementations, a single CU-UP 172B can be connected to multiple CU-CP 172A through the E1 interface. The CU-CP 172A can be connected to one or more DU <NUM> through an F1-C interface. The CU-UP 172B can be connected to one or more DU <NUM> through the F1-U interface under the control of the same CU-CP 172A. In some implementations, one DU <NUM> can be connected to multiple CU-UP 172B under the control of the same CU-CP 172A. In such implementations, the connectivity between a CU-UP 172B and a DU <NUM> is established by the CU-CP 172A using Bearer Context Management functions.

<FIG> illustrates, in a simplified manner, an example protocol stack <NUM> according to which the UE <NUM> can communicate with an eNB/ng-eNB or a gNB (e.g., one or more of the base stations <NUM>, 106A, 106B).

In the example stack <NUM>, a physical layer (PHY) 202A of EUTRA provides transport channels to the EUTRA MAC sublayer 204A, which in turn provides logical channels to the EUTRA RLC sublayer 206A. The EUTRA RLC sublayer 206A in turn provides RLC channels to the EUTRA PDCP sublayer <NUM> and, in some cases, to the NR PDCP sublayer <NUM>. Similarly, the NR PHY 202B provides transport channels to the NR MAC sublayer 204B, which in turn provides logical channels to the NR RLC sublayer 206B. The NR RLC sublayer 206B in turn provides RLC channels to the NR PDCP sublayer <NUM>. The UE <NUM>, in some implementations, supports both the EUTRA and the NR stack as shown in <FIG>, to support handover between EUTRA and NR base stations and/or to support DC over EUTRA and NR interfaces. Further, as illustrated in <FIG>, the UE <NUM> can support layering of NR PDCP <NUM> over EUTRA RLC 206A, and an SDAP sublayer <NUM> over the NR PDCP sublayer <NUM>.

The EUTRA PDCP sublayer <NUM> and the NR PDCP sublayer <NUM> receive packets (e.g., from an Internet Protocol (IP) layer, layered directly or indirectly over the PDCP layer <NUM> or <NUM>) that can be referred to as service data units (SDUs), and output packets (e.g., to the RLC layer 206A or 206B) that can be referred to as protocol data units (PDUs). Except where the difference between SDUs and PDUs is relevant, this disclosure for simplicity refers to both SDUs and PDUs as "packets". The packets can be MBS packets or non-MBS packets. For example, the MBS packets include MBS data packets including application content for an MBS service (e.g., IPv4/IPv6 multicast delivery, IPTV, software delivery over wireless, group communications, IoT applications, V2X applications, and/or emergency messages related to public safety). In another example, the MBS packets include application control information for the MBS service.

On a control plane, the EUTRA PDCP sublayer <NUM> and the NR PDCP sublayer <NUM> can provide SRBs to exchange RRC messages or non-access-stratum (NAS) messages, for example. On a user plane, the EUTRA PDCP sublayer <NUM> and the NR PDCP sublayer <NUM> can provide DRBs to support data exchange. Data exchanged on the NR PDCP sublayer <NUM> can be SDAP PDUs, Internet Protocol (IP) packets or Ethernet packets.

In scenarios where the UE <NUM> operates in EN-DC with the base station <NUM> operating as an MeNB and the base station 106A operating as an SgNB, the wireless communication system <NUM> can provide the UE <NUM> with an MN-terminated bearer that uses EUTRA PDCP sublayer <NUM>, or an MN-terminated bearer that uses NR PDCP sublayer <NUM>. The wireless communication system <NUM> in various scenarios can also provide the UE <NUM> with an SN-terminated bearer, which uses only the NR PDCP sublayer <NUM>. The MN-terminated bearer can be an MCG bearer, a split bearer, or an MN-terminated SCG bearer. The SN-terminated bearer can be an SCG bearer, a split bearer, or an SN-terminated MCG bearer. The MN-terminated bearer can be an SRB (e.g., SRB1 or SRB2) or a DRB. The SN-terminated bearer can be an SRB or a DRB.

In some implementations, a base station (e.g., base station <NUM>, 106A or 106B) broadcasts MBS data packets via one or more MBS radio bearers (MRB(s)), and in turn the UE <NUM> receives the MBS data packets via the MRB(s). The base station can include configuration(s) of the MRB(s) in multicast configuration parameters (which can also be referred to as MBS configuration parameters) described below. In some implementations, the base station broadcasts the MBS data packets via RLC sublayer <NUM>, MAC sublayer <NUM>, and PHY sublayer <NUM>, and correspondingly, the UE <NUM> uses PHY sublayer <NUM>, MAC sublayer <NUM>, and RLC sublayer <NUM> to receive the MBS data packets. In such implementations, the base station and the UE <NUM> may not use PDCP sublayer <NUM> and a SDAP sublayer <NUM> to communicate the MBS data packets. In other implementations, the base station transmits the MBS data packets via PDCP sublayer <NUM>, RLC sublayer <NUM>, MAC sublayer <NUM>, and PHY sublayer <NUM>, and correspondingly, the UE <NUM> uses PHY sublayer <NUM>, MAC sublayer <NUM>, RLC sublayer <NUM> and PDCP sublayer <NUM> to receive the MBS data packets. In such implementations, the base station and the UE <NUM> may not use a SDAP sublayer <NUM> to communicate the MBS data packets. In yet other implementations, the base station transmits the MBS data packets via the SDAP sublayer <NUM>, PDCP sublayer <NUM>, RLC sublayer <NUM>, MAC sublayer <NUM> and PHY sublayer <NUM>, and correspondingly, the UE <NUM> uses PHY sublayer <NUM>, MAC sublayer <NUM>, RLC sublayer <NUM>, PDCP sublayer <NUM>, and the SDAP sublayer <NUM> to receive the MBS data packets.

<FIG> are messaging diagrams of example scenarios in which a base station, CN, and UE communicate MBS information. Generally speaking, events in <FIG> that are similar are labeled with similar reference numbers (e.g., event 350A is similar to event 350B, 350C, 450A, etc.), with differences discussed below where appropriate. With the exception of the differences shown in the figures and discussed below, any of the alternative implementations discussed with respect to a particular event (e.g., for messaging and processing) may apply to events labeled with similar reference numbers in other figures.

Now referring to a scenario 300A illustrated in <FIG>, the UE <NUM> initially transmits 302A a first PDUSession Establishment Request message for establishing a first PDU Session for MBS to the base station (BS) <NUM>. To indicate that the UE <NUM> is requesting a DRB for receiving MBS information, the UE <NUM> may include a flag or other indication in the PDU Session Establishment Request. For example, the flag may be a data network name (DNN) field set to "MBS" or corresponding to an MBS service. In some implementations, the UE <NUM> initially operates in an idle state or an inactive state (e.g., RRC_IDLE state, RRC_INACTIVE state), or more generally in a state in which there is no active radio connection between the UE <NUM> and the base station <NUM>. Alternatively, the UE <NUM> initially operates in a connected state (e.g., RRC_CONNECTED state), or more generally in a state in which there is an active radio connection between the UE <NUM> and the base station <NUM>.

The base station <NUM> in turn sends 304A the first PDU Session Establishment Request message to the CN <NUM> (e.g., AMF <NUM> and/or SMF <NUM>). In some implementations, the base station <NUM> can send 304A a BS to CN interface message (e.g., NG interface message, INITIAL UE MESSAGE, or UPLINK NAS TRANSPORT message) including the first PDUSession Establishment Request message to the CN <NUM>.

In response to the first PDUSession Establishment Request message, the CN <NUM> sends 306A a first PDU Session Establishment Accept message to the base station <NUM>, which in turn sends 308A the first PDU Session Establishment Accept message to the UE <NUM>. In some implementations, the CN <NUM> sends 306A a CN to BS interface message (e.g., NG interface message or PDU SESSION RESOURCE SETUP REQUEST message) including the first PDU Session Establishment Accept message. In response to the CN to BS interface message, the base station <NUM> transmits 310A an RRC reconfiguration message configuring a first DRB to the UE <NUM>. In some implementations, the base station <NUM> can include the first PDU Session Establishment Accept message in the RRC reconfiguration message that the base station <NUM> transmits 310A. In other implementations, the base station <NUM> can transmit 308A a DL RRC message including the first PDU Session Establishment Accept message to the UE <NUM>. The DL RRC message can be a DLInformationTransfer message, an RRC reconfiguration message, or any suitable RRC message which can include a NAS PDU.

In response to the RRC reconfiguration message that the base station <NUM> transmits 310A, the UE <NUM> can transmit 312A an RRC reconfiguration complete message to the base station <NUM>. In some implementations, after receiving 312A the RRC reconfiguration complete message, the base station <NUM> sends a BS to CN interface message (e.g., PDU SESSION RESOURCE SETUP RESPONSE message) to the CN <NUM> to confirm that the base station <NUM> has configured radio resources for the UE <NUM> for the first PDU Session.

Events 302A, 304A, 306A, 308A, 310A and 312A are collectively referred to as an MBS PDU session establishment procedure 350A.

In some implementations, the UE <NUM> can transmit 314A to the base station <NUM> an MBS request message to request, join, or register a particular MBS service, and the base station <NUM> can send 316A the MBS request message to the CN <NUM>. In one implementation, the UE <NUM> can include the MBS request message in an IP packet and transmit the IP packet to the base station <NUM> via the first DRB. In such implementation, the base station <NUM> sends 316A the IP packet to the CN <NUM> (e.g., UPF <NUM>). In another implementation, UE <NUM> can transmit 314A the MBS request via an SRB (e.g., as a NAS message or an RRC message). For example, UE <NUM> can transmit a NAS message requesting an MBS service to the base station <NUM> via an SRB, and the base station <NUM> in turn sends 316A the NAS message to the CN <NUM> (e.g., AMF <NUM> and/or SMF <NUM>). In other implementations, the UE <NUM> can refrain from sending an explicit MBS request to the base station <NUM>. For example, the PDU Session Establishment Request message (event 302A) may indicate an MBS service that the UE <NUM> is interested in receiving. In yet other implementations, the CN <NUM> can transmit a message to the base station <NUM> requesting that the base station <NUM> transmit an MBS service to the UE <NUM> (e.g., an emergency broadcast).

After the CN <NUM> determines that the base station <NUM> has configured radio resources for the UE <NUM> for the first PDU Session, the CN <NUM> in some implementations can send 318A MBS control information to the base station <NUM>, which in turn transmits 320A the MBS control information to the UE <NUM>, e.g. via an SRB or the first DRB. In particular, in some implementations, a network node (e.g., the CN <NUM> or an MBS server) generates the MBS control information. In one implementation, the network node can include the MBS control information in IP packet(s) and send 318A the IP packet(s) to the base station <NUM>, which in turn transmits 320A the IP packet(s) to the UE <NUM> via the first DRB. In another implementation, the CN <NUM> sends 318A NAS message(s) including the MBS control information to the base station <NUM>. The base station <NUM> in turn sends 320A the NAS message(s) to the UE <NUM> via an SRB. In some implementations, the CN <NUM> and/or base station <NUM> may transmit to the UE <NUM> the MBS control information on a first quality of service (QoS) flow, i.e., the CN <NUM> associates the MBS control information to a first QoS profile of the first QoS flow including a first plurality of QoS parameters. The CN <NUM> and the base station <NUM> enforce the first QoS profile on transmissions of the MBS data packets.

Alternatively, in other implementations, the base station <NUM> generates the MBS control information instead of receiving the MBS control information from the CN <NUM> or an MBS server. The base station <NUM> transmits 320A the MBS control information to the UE <NUM>, e.g. via an SRB or the first DRB.

The MBS control information helps the UE <NUM> to receive 338A MBS data packets. In some implementations, the CN <NUM> can determine that the UE <NUM> has been configured radio resources for the first PDU Session in response to the PDU SESSION RESOURCE SETUP RESPONSE message or the MBS request message. After the CN <NUM> determines that the UE <NUM> has been configured radio resources for the first PDU Session, the CN <NUM> in some implementations sends 338A MBS data packets of the particular MBS service to the base station <NUM>, which in turn transmits the MBS data packets to the UE <NUM> via the first DRB. In cases involving a group of UEs, the CN <NUM> in other implementations can send 338A MBS data packets of the particular MBS service to the base station <NUM> irrespective of whether the UE <NUM> has been configured radio resources for the first PDU Session.

In some implementations, the CN <NUM> and/or base station <NUM> may transmit to the UE <NUM> the MBS data packets on a second quality of service (QoS) flow, i.e., the CN <NUM> associates the MBS data packets to a second QoS profile of the second QoS flow including a second plurality of QoS parameters. The CN <NUM> and the base station <NUM> enforce the second QoS profile on transmissions of the MBS data packets. In other implementations, the CN <NUM> may send the MBS data packets on the first QoS flow. The CN <NUM> and the base station <NUM> enforce the first QoS profile on transmissions of the MBS data packets.

In some implementations, the MBS control information includes security configuration parameters. In one implementation, the security configuration parameters include security key(s) and the UE <NUM> uses the security key(s) to decrypt and/or integrity check the MBS data packets. In another implementation, the UE <NUM> derives security key(s) from the security configuration parameters and uses the security key(s) to decrypt and/or integrity check the MBS data packets.

In other implementations, the MBS control information includes a group identity (e.g., Temporary Mobile Group Identity (TMGI)) or an MBS session identity. The UE <NUM> uses the group identity and/or MBS session identity to receive the MBS data packets.

In some implementations, the RRC reconfiguration message that the base station <NUM> transmits 310A includes a first DRB configuration configuring the first DRB and includes physical layer configuration parameters, MAC configuration parameters, and/or RLC configuration parameters. The base station <NUM> can assign radio resources for transmission of the MBS data packets to a particular UE (e.g., the UE 102A) or a group of UEs (e.g., the UE 102A and the UE 102B, or the UE 102A, the UE 102B, and/or other UE(s) not shown in <FIG> and <FIG>). In case of the group of UEs, the base station <NUM> sends 338A the MBS data packets on radio resources (i.e., radio resources common for the group of UEs) where the group of UEs receives the MBS data packets using the configuration parameters. Thus, each UE in the group of UEs receives 338A the MBS data packets on the same radio resources from the base station <NUM>. Accordingly, the RRC reconfiguration message that the base station <NUM> transmits 310A or the first DRB configuration may include unicast configuration parameters for a particular UE or multicast configuration parameters for a group of UEs.

In cases involving the group of UEs, in some implementations, the base station <NUM> can transmit the first DRB configuration and the configuration parameters to the group of UEs in separate RRC reconfiguration messages. In other implementations, the base station <NUM> can broadcast the first DRB configuration and/or the configuration parameters to the group of UEs (e.g., the base station <NUM> can broadcast the first DRB configuration and/or the configuration parameters in system information block(s) (SIB) to the cell <NUM>). The configuration parameters for the UE <NUM> to receive MBS data packets on the common radio resources may include a radio network temporary identifier (RNTI). The group of the UEs or the UE <NUM> uses the RNTI to receive, on a PDCCH, a DCI with a CRC scrambled with the RNTI and receives a PDSCH in accordance with the DCI. The PDSCH can include a partial MBS data packet and/or at least one MBS data packet. In some implementations, the RNTI can be a group RNTI (G-RNTI) or an MBS-RNTI. In some implementations, the configuration parameters, e.g., for the UE <NUM> to receive MBS data packets on the common radio resources, may include a DL BWP configuration configuring an MBS DL BWP.

In cases involving a particular UE, the base station <NUM> sends 338A the MBS data packets on dedicated radio resources (i.e., dedicated only to the particular UE) where the particular UE receives the MBS packets using the configuration parameters. Thus, the particular UE receive 338A the MBS data packets on the dedicated radio resources from the base station <NUM>.

In some implementations, the RRC reconfiguration message that the base station <NUM> transmits 310A can include a CellGroupConfig information element (IE) configuring the configuration parameters. In other implementations, the RRC reconfiguration message that the base station <NUM> transmits 310A can include an MBS specific IE configuring the configuration parameters. The base station <NUM> can indicate that the first DRB is associated with the first PDU Session in the RRC reconfiguration message that the base station <NUM> transmits 310A. For example, the first DRB configuration can include a PDU session identity of the first PDU Session. In some implementations, the base station configures the UE <NUM> to use an RLC acknowledged mode (AM) for the first DRB in the RLC configuration parameters. In other implementations, the base station configures the UE <NUM> to use an RLC unacknowledged mode (UM) for the first DRB in the RLC configuration parameters.

Before, during or after the MBS PDU session establishment procedure 350A, the UE <NUM> in some implementations can perform a unicast PDU session establishment procedure 360A with the base station <NUM> and the CN <NUM> (e.g., AMF <NUM> and/or SMF <NUM> or another AMF and/or SMF). The UE <NUM> transmits 362A a second PDU Session Establishment Request message for establishing a second PDU Session for one or more unicast services to the base station <NUM>. For example, the one or more unicast services can be a voice call, video call, or internet service (e.g., a service for email, navigation, social media, streaming, gaming, web browsing, etc.).

The base station <NUM> in turn sends 364A the second PDU Session Establishment Request message to the CN <NUM> (e.g., AMF <NUM> and/or SMF <NUM>). In some implementations, the base station <NUM> can send 364A a BS to CN interface message (e.g., NG interface message, INITIAL UE MESSAGE or UPLINK NAS TRANSPORT message) including the second PDUSession Establishment Request message to the CN <NUM>.

In response to the second PDUSession Establishment Request message, the CN <NUM> sends 366A a second PDU Session Establishment Accept message to the base station <NUM>, which in turn sends 368A the second PDU Session Establishment Accept message to the UE <NUM>. In some implementations, the CN <NUM> sends 366A a CN to BS interface message (e.g., NG interface message or PDU SESSION RESOURCE SETUP REQUEST message) including the second PDU Session Establishment Accept message. In response to the CN to BS interface message, the base station <NUM> transmits 370A an RRC reconfiguration message configuring a second DRB to the UE <NUM>. In some implementations, the base station <NUM> can include the second PDU Session Establishment Accept message in the RRC reconfiguration message that the base station <NUM> transmits 370A. In other implementations, the base station <NUM> can transmit 368A a DL RRC message including the second PDU Session Establishment Accept message to the UE <NUM>. The DL RRC message can be a DLInformationTransfer message, an RRC reconfiguration message or any suitable RRC message which can include a NAS PDU.

In response to the RRC reconfiguration message that the UE <NUM> receives 370A, the UE <NUM> can transmit 372A an RRC reconfiguration complete message to the base station <NUM>. In some implementations, after receiving 372A the RRC reconfiguration complete message, the base station <NUM> sends a BS to CN interface message (e.g., PDU SESSION RESOURCE SETUP RESPONSE message) to the CN <NUM> to confirm that the base station <NUM> has configured radio resources for the UE <NUM> for the second PDU Session.

In some implementations, the RRC reconfiguration message that the base station <NUM> transmits 370A includes a second DRB configuration configuring the second DRB and includes physical layer configuration parameters, MAC configuration parameters, and/or RLC configuration parameters configuring radio resources. The base station <NUM> can assign radio resources for unicast packets to a particular UE (e.g., the UE 102A), i.e., the radio resources can be dedicated only to the particular UE. The base station <NUM> transmits unicast packets on dedicated resources to the particular UE and the particular UE transmits unicast packets on dedicated resources to the base station <NUM>.

In some implementations, the RRC reconfiguration message that the base station <NUM> transmits 370A can include a CellGroupConfig information element (IE) configuring the configuration parameters. The base station <NUM> can indicate that the second DRB is associated with the second PDU Session in the RRC reconfiguration message that the base station <NUM> transmits 370A. For example, the second DRB configuration can include a PDU session identity of the second PDU Session. In some implementations, the base station <NUM> configures the UE <NUM> to use an RLC AM for the second DRB in the RLC configuration parameters. In some implementations, the RLC configuration parameters in the RRC reconfiguration message that the base station <NUM> transmits 370A can be the same or different from the RLC configuration parameters in the RRC reconfiguration message that the base station <NUM> transmits 310A.

After configuring the second DRB, the UE <NUM> communicates 374A unicast packets with the CN <NUM> (e.g., UPF <NUM> or another UPF) via the second DRB and the base station <NUM>. In some implementations, the unicast service(s) is/are IMS service(s) (e.g., voice service, supplementary service, and/or short message service) and the UE <NUM> establishes the second PDU Session for the IMS service(s). In such implementations, the UE <NUM> can transmit Session Initiation Protocol (SIP) messages via the second DRB to the base station <NUM>, which in turn sends the SIP messages to the CN <NUM>. Then, the CN <NUM> can send the SIP messages to an IMS network including e.g., a Proxy-Call Session Control Function (P-CSCF), a suitable network node processing the SIP messages, and/or a particular network node processing voice packets. In such implementations, the CN <NUM> can receive SIP messages from the IMS network and transmit the SIP messages to the base station <NUM>, which in turn transmits the SIP messages to the UE <NUM> via the second DRB.

In some implementations, the UE <NUM> sends a SIP message (e.g., SIP INVITE) for a mobile originating voice call via the second DRB to the BS, which in turn sends the SIP message to the CN <NUM>. Then the CN <NUM> sends the SIP message to the IMS network. In other implementations, the IMS network sends a SIP message (e.g., SIP INVITE) for a mobile terminating voice call for the UE <NUM>. The IMS network can send an IMS to CN interface message (e.g., Npcf_PolicyAuthorization_Update message or a suitable Npcf message) to the CN <NUM> for the mobile originating or terminating voice call (e.g., in response to the SIP message received from the UE <NUM> or transmitted by the IMS network). In response to the IMS to CN interface message, the CN <NUM> sends to the base station <NUM> a CN to BS interface message (e.g., PDU Session Resource Modify Request message) causing the base station <NUM> to configure the UE <NUM> a DRB for communicating (e.g., transmitting and/or receiving) voice packets. In response to the CN to BS interface message, the base station <NUM> transmits to the UE <NUM> a third RRC reconfiguration message including a third DRB configuration configuring a third DRB. The UE <NUM> can transmit an RRC reconfiguration complete message to the base station <NUM> in response to the third RRC reconfiguration message. Thus, the UE <NUM> communicates voice packets with the CN <NUM> via the base station <NUM> (over the third DRB). The CN <NUM> can communicate the voice packets with the IMS network.

In some implementations, the CN <NUM> can include a PDU Session Modification Command message in the CN to BS interface message to configure a third quality of service (QoS) flow for transmission of voice packets to and/or from the UE <NUM>. The CN <NUM> associates voice packets to a third QoS profile of the third QoS flow including a third plurality of QoS parameters. The CN <NUM> and the base station <NUM> enforce the third QoS profile on transmissions of the voice packets to and/or from the UE <NUM>. Then the base station <NUM> transmits the PDU Session Modification Command message to the UE <NUM>. In some implementations, the base station <NUM> can include the PDU Session Modification Command message in a DL RRC message and transmit the DL RRC message to the UE <NUM>. For example, the DL RRC message can be the third RRC reconfiguration message, an additional RRC reconfiguration message, or a DLInformationTransfer message. The UE <NUM> can transmit an RRC reconfiguration complete message in response to the additional RRC reconfiguration message. Thus, the UE <NUM> can communicate voice packets on the QoS flow with the CN <NUM> via the base station <NUM> (over the third DRB).

In some implementations, the third RRC reconfiguration message includes physical layer configuration parameters, MAC configuration parameters, and/or RLC configuration parameters. The base station <NUM> can assign radio resources for voice packets to a particular UE (e.g., the UE 102A), i.e., the radio resources are dedicated only to the particular UE. The base station <NUM> transmits voice packets on dedicated resources to the particular UE and the particular UE transmits voice packets on dedicated resources to the base station <NUM>.

In some implementations, the third RRC reconfiguration message can include a CellGroupConfig information element (IE) configuring the configuration parameters. In some implementations, the RLC configuration parameters in the third RRC reconfiguration message can be the same or different from the RLC configuration parameters in the RRC reconfiguration message that the base station <NUM> transmits 370A. In some implementations, the base station <NUM> configures the UE <NUM> to use an RLC UM for the third DRB in the RLC configuration parameters.

The base station <NUM> can indicate that the third DRB is associated with the second PDU Session and/or the QoS flow in the third RRC reconfiguration message. For example, the third DRB configuration can include a PDU session identity of the second PDU Session and/or a QoS flow identity of the third QoS flow.

The UE <NUM> can send a PDU Session Modification Complete message to the CN <NUM> via the base station <NUM> in response to the PDU Session Modification Command message. In some implementations, the UE <NUM> can include the PDUSession Modification Complete message in a UL RRC message and transmit the UL RRC message to the base station <NUM>, which in turn extracts the PDU Session Modification Complete message from the UL RRC message and sends the PDU Session Modification Complete message to the CN <NUM>. In some implementations, the base station <NUM> can send a BS to CN interface message (e.g., PDU Session Resource Modify Response message or Uplink NAS Transport message) including the PDU Session Modification Complete message to the CN <NUM>. The base station <NUM> sends the PDU Session Resource Modify Response message in response to the PDU Session Resource Modify Request message. In some implementations, the UL RRC message can be the RRC reconfiguration complete message responding to the third RRC reconfiguration message or the additional RRC reconfiguration message. In other implementations, the UL RRC message can be a ULInformationTransfer message.

In some implementations, the unicast service(s) is/are Internet service(s) and the UE <NUM> establishes the second PDU Session for the Internet service(s). The UE communicates Internet Protocol (IP) packets with the CN <NUM> via the base station <NUM> (over the second DRB).

In some implementations, the UE <NUM> may include a first Data Network Name (DNN) in the first PDUSession Establishment Request message to indicate a particular data network that the UE <NUM> wishes to access via first PDU Session. In some implementations, the UE <NUM> may include a second DNN in the second PDUSession Establishment Request message to indicate a particular data network that the UE <NUM> wishes to access via the first PDU Session. In other implementations, the UE <NUM> may exclude a DNN in the second PDU Session Establishment Request message. In this case, the second PDU Session may be associated to a default DNN.

In some implementations, the UE <NUM> performs the first unicast PDU session establishment procedure 360A for the IMS service(s) as previously described. In such implementations, the UE <NUM> can perform a second unicast PDU session establishment procedure with the base station <NUM> and the CN <NUM> to establish a third PDU Session for the Internet service(s) similar to the first unicast PDU session establishment procedure 360A. In the second unicast PDU session establishment procedure, the base station <NUM> transmits to the UE <NUM> a fourth RRC reconfiguration message including a fourth DRB configuration configuring a fourth DRB, similar to event 370A. The UE <NUM> and base station <NUM> establish the fourth DRB with the fourth DRB configuration. The UE <NUM> can transmit a fourth RRC reconfiguration complete message to the base station <NUM> in response to the fourth RRC reconfiguration message. The UE <NUM> communicates IP packets of the Internet service(s) with the base station <NUM> (over the fourth DRB) and with the CN <NUM>, similar to event 374A.

In some implementations, the fourth RRC reconfiguration message includes physical layer configuration parameters, MAC configuration parameters, and/or RLC configuration parameters. The base station <NUM> can assign the configuration parameters or radio resources to a particular UE (e.g., the UE 102A) or a group of UEs (e.g., the UE 102A and the UE 102B, or the UE 102A, the UE 102B, and/or other UE(s) not shown in <FIG> and <FIG>). In cases involving the group of UEs, the base station <NUM> sends the MBS data packets on radio resources (i.e., radio resources common for the group of UEs) where the group of UEs receive the MBS data packets using the configuration parameters. Thus, the group of UEs receive the MBS data packets on the same radio resources from the base station <NUM>. In cases involving the group of UEs, the base station <NUM> can transmit the fourth DRB configuration and the configuration parameters to each UE in the group of UEs in separate RRC reconfiguration messages, or in a broadcast (e.g., a broadcast in SIB(s) to the cell <NUM>). The configuration parameters for the UE <NUM> to receive MBS data packets on the common radio resources may include a radio network temporary identifier (RNTI). The group of the UEs or the UE <NUM> uses the RNTI to receive, on a PDCCH, a DCI with a CRC scrambled with the RNTI and receives a PDSCH in accordance with the DCI. The PDSCH can include a partial MBS data packet and/or at least one MBS data packet. In some implementations, the RNTI can be a group RNTI (G-RNTI) or an MBS-RNTI.

In cases involving a particular UE, the base station <NUM> sends the MBS data packets on dedicated radio resources (i.e., dedicated only to the particular UE) where the particular UE receives using the configuration parameters. Thus, the particular UE receives the MBS data packets on the dedicated radio resources from the base station <NUM>.

In some implementations, the fourth RRC reconfiguration message can include a CellGroupConfig information element (IE) configuring the configuration parameters. The base station <NUM> can indicate that the fourth DRB is associated with the third PDU Session in the fourth RRC reconfiguration message. For example, the fourth DRB configuration can include a PDU session identity of the second PDU Session. In some implementations, the base station <NUM> configures the UE <NUM> to use an RLC AM for the fourth DRB in the RLC configuration parameters. In some implementations, the RLC configuration parameters in the fourth RRC reconfiguration message can be the same or different from the RLC configuration parameters in the RRC reconfiguration message that the base station <NUM> transmits 370A.

<FIG> illustrates a scenario 300B similar to the scenario 300A of <FIG>. The scenario 300B is generally similar to the scenario 300A, except that the base station <NUM> configures an additional radio bearer (i.e., a fifth DRB) for transmitting MBS data packets to the UE <NUM>.

Initially, the UE <NUM> performs 350B an MBS PDU session establishment procedure with the CN <NUM> via the base station <NUM>. In some implementations, the UE <NUM> can transmit 314B to the base station <NUM>, via the first DRB, an MBS request message to request, join, or register a particular MBS service. The base station <NUM> sends 316B the MBS request message to the CN <NUM>, which in turn can send the MBS request message to an MBS network (not shown in <FIG> and <FIG>), which may include an Application Function (AF), an MBS Function (MBSF), Multicast Session Function (MSF), and/or one or more suitable network nodes for MBS. As mentioned in connection with event 314A, the UE <NUM> may transmit 314B the MBS request via an SRB or the first DRB, or may refrain from transmitting 314B an explicit request for an MBS service. For example, the PDU Session Establishment Request message (during procedure 350B) may indicate an MBS service that the UE <NUM> is interested in receiving. In yet other implementations, the CN <NUM> can transmit a message to the base station <NUM> requesting that the base station <NUM> transmit an MBS service to the UE <NUM> (e.g., an emergency broadcast).

After establishing the first PDU Session for MBS with the UE <NUM> at event 350B or receiving the MBS request message at event 316B, the CN <NUM> can send 322B to the base station <NUM> a CN to BS interface message (e.g., a PDU SESSION RESOURCE MODIFY REQUEST message) that causes the base station <NUM> to configure a DRB for receiving MBS data packets for the UE <NUM>. In response to the CN to BS interface message, the base station <NUM> transmits 324B to the UE <NUM> an RRC reconfiguration message including a DRB configuration (e.g., a fifth DRB configuration) configuring a DRB (e.g., a fifth DRB). The UE <NUM> can transmit 326B an RRC reconfiguration complete message to the base station <NUM> in response to the RRC reconfiguration message. In response to the CN to BS interface message that the base station <NUM> receives 322B, the base station <NUM> can send 328B a BS to CN interface message (e.g., PDU SESSION RESOURCE MODIFY RESPONSE message) to the CN <NUM> before or after transmitting 324B the RRC reconfiguration message or receiving 326B the RRC reconfiguration complete message.

After the CN <NUM> determines that the base station <NUM> has configured radio resources that the UE <NUM> can use to receive MBS data packets (i.e., the UE <NUM> establishes the fifth DRB), the CN <NUM> sends 338B MBS data packets to the base station <NUM>, which in turn transmits 338B the MBS data packets to the UE <NUM> via the fifth DRB. Thus, the UE <NUM> receives 338B MBS data packets from the base station <NUM> over the fifth DRB. The CN <NUM> can receive the MBS data packets from the MBS network.

In addition, before, during, or after the MBS PDU session establishment procedure 350B, the UE <NUM> can perform 360B a first unicast PDU session establishment procedure with the CN <NUM> via the base station <NUM> and communicate 374B unicast packets with the CN <NUM> via the base station <NUM>.

In some implementations, the RRC reconfiguration message that the base station <NUM> transmits 324B includes physical layer configuration parameters, MAC configuration parameters, and/or RLC configuration parameters configuring radio resources dedicated to the UE <NUM>. For example, the RRC reconfiguration message that the base station <NUM> transmits 324B can include a CellGroupConfig information element (IE) configuring the configuration parameters. In some implementations, the RLC configuration parameters in the RRC reconfiguration message that the base station <NUM> transmits 324B can be the same or different from the RLC configuration parameters in the RRC reconfiguration message the base station <NUM> transmits during the MBS PDU session establishment procedure 350B to configure the first DRB. In some implementations, the base station <NUM> configures the UE <NUM> to use an RLC UM for the fifth DRB in the RLC configuration parameters.

In some implementations, the CN <NUM> can include a PDUSession Modification Command message in the CN to BS interface message the CN <NUM> transmits 322B to configure a quality of service (QoS) flow for the UE <NUM>, similar to the second QoS flow described for <FIG>. The base station <NUM> can include the PDU Session Modification Command message in a DL RRC message and transmit the DL RRC message to the UE <NUM>. For example, the DL RRC message can be the RRC reconfiguration message that the base station <NUM> transmits 324B, an additional RRC reconfiguration message, or a DLInformationTransfer message. The UE <NUM> can transmit an RRC reconfiguration complete message in response to the additional RRC reconfiguration message.

The base station <NUM> can indicate that the fifth DRB is associated with the first PDU Session and/or the QoS flow in the RRC reconfiguration message that the base station <NUM> transmits 324B. For example, the fifth DRB configuration can include a PDU session identity of the first PDU Session and/or a QoS flow identity of the QoS flow.

The UE <NUM> can send a PDU Session Modification Complete message to the CN <NUM> via the base station <NUM> in response to the PDU Session Modification Command message. In some implementations, the UE <NUM> can include the PDUSession Modification Complete message in a UL RRC message and transmit the UL RRC message to the base station <NUM>, which in turn extracts the PDU Session Modification Complete message from the UL RRC message and sends the PDU Session Modification Complete message to the CN <NUM>. In some implementations, the base station <NUM> can include the PDU Session Modification Complete message in the BS to CN interface message that the base station <NUM> transmits 328B. In other implementation, the base station <NUM> can send an additional BS to CN interface message (e.g., Uplink NAS Transport message) including the PDU Session Modification Complete message to the CN <NUM>. In some implementations, the UL RRC message can be the RRC reconfiguration complete message responding to the RRC reconfiguration message that the UE <NUM> receives 324B or the additional RRC reconfiguration message. In other implementations, the UL RRC message can be a ULInformationTransfer message.

After the CN <NUM> determines that the base station <NUM> has configured radio resources for the first PDU Session or for the UE <NUM> to receive MBS data packets, the CN <NUM> in some implementations can send 318B MBS control information to the base station <NUM>, which in turn transmits 320B the MBS control information to the UE <NUM>, e.g. via an SRB, the first DRB, or the fifth DRB. Alternatively, the base station <NUM> generates the MBS control information instead of receiving the MBS control information from the CN <NUM> and transmits 320B the MBS control information to the UE <NUM>, e.g. via an SRB, the first DRB, or the fifth DRB. The MBS control information helps the UE <NUM> to receive 338B MBS data packets. Event 318B can occur before or after event 328B, 322B or 316B. Event 320B can occur before or after event 326B, 324B or 314B.

In some implementations, the CN <NUM> can make the determination that the base station <NUM> has configured radio resources for the first PDU Session in response to the PDU SESSION RESOURCE SETUP RESPONSE message or the MBS request message. In some implementations, the CN <NUM> can make such determination that the UE <NUM> has been configured radio resources for receiving MBS data packets in response to the BS to CN interface message that the CN <NUM> receives 328B or the additional BS to CN interface message. After the CN <NUM> determines that the UE <NUM> has been configured radio resources for receiving MBS data packets, the CN <NUM> in some implementations can send 338B MBS data packets to the base station <NUM>, which in turn transmits the MBS data packets to the UE <NUM> via the fifth DRB. In cases involving a group of UEs, the CN <NUM> in other implementations can send 338B MBS data packets of the particular MBS service to the base station <NUM> irrespective of whetherthe UE <NUM> has been configured radio resources for the first PDU Session.

Turning to <FIG>, a scenario 300C is generally similar to the scenario 300B. However, the UE <NUM> performs 350C a PDU session establishment procedure with the CN <NUM> via the base station <NUM> for both MBS and unicast service(s) (e.g., IMS service(s) and/or internet service). Thus, in contrast to the scenarios 300A and 300B, the UE <NUM> can receive both MBS and unicast service(s) through the same PDU session. The messaging during the PDU session establishment procedure 350C is generally similar to the messaging during the MBS PDU session establishment procedure 350A, except that the UE <NUM> initially transmits a PDUSession Establishment Request message for establishing a PDU session for an MBS service and unicast services to the base station <NUM>, similar to the event 302A.

Events 314C, 316C, 322C, 324C, 326C, 328C, 318C, 336C, and 338C for configuring MBS transmissions to the UE <NUM> may be similar to the events 314B, 316B, 322B, 324B, 326B, 328B, 318B, 336B, and 338B, respectively. Before, after, or during these events for configuring MBS transmissions, the UE <NUM> can transmit 363C a unicast request message to the base station <NUM> in order to request a particular unicast service, and the base station <NUM> can transmit 365C the unicast request message to the CN <NUM>. In some implementations, the UE <NUM> transmits 363C the unicast request message over the first DRB configured during the PDU session establishment procedure 350C. Further, in some implementations, the unicast request message can be a SIP message, discussed above with reference to event 374A.

In response to receiving 365C the unicast request message, the CN <NUM> can transmit 382C a CN to BS interface message (e.g., a PDU SESSION RESOURCE MODIFY REQUEST message) that causes the base station <NUM> to configure a DRB for receiving unicast data packets for the UE <NUM>. In response to receiving 382C the CN to BS interface message, the base station <NUM> transmits 384C to the UE <NUM> an RRC reconfiguration message including a DRB configuration (e.g., a sixth DRB configuration) configuring a DRB (e.g., a sixth DRB). The UE <NUM> can transmit 386C an RRC reconfiguration complete message to the base station <NUM> in response to the RRC reconfiguration message. In response to the CN to BS interface message the base station receives 382C, the base station <NUM> can send 388C a BS to CN interface message (e.g., PDU SESSION RESOURCE MODIFY RESPONSE message) to the CN <NUM> before or after transmitting 384C the RRC reconfiguration message or receiving 386C the RRC reconfiguration complete message. The UE <NUM> can then communicate 374C unicast packets with the CN via the base station <NUM> over the sixth DRB. The messages 382C, 384C, 386C, and 388C for configuring the sixth DRB may be similar to the events 322C, 324C, 326C, and 328C for configuring the fifth DRB, except that that the sixth DRB is for a unicast service rather than an MBS service.

In some implementations, the CN <NUM> can include a PDUSession Modification Command message in the CN to BS interface message to configure a quality of service (QoS) flow for transmission of unicast data packets to and/or from the UE <NUM>. The CN <NUM> associates unicast data packets to a QoS profile of the QoS flow including a plurality of QoS parameters. The CN <NUM> and the base station <NUM> enforce the QoS profile on transmissions of the unicast data packets to and/or from the UE <NUM>. The base station <NUM> then transmits the PDU Session Modification Command message to the UE <NUM>. In some implementations, the base station <NUM> can include the PDU Session Modification Command message in a DL RRC message and transmit the DL RRC message to the UE <NUM>. For example, the DL RRC message can be the RRC reconfiguration message that the base station <NUM> transmits 384C, an additional RRC reconfiguration message, or a DLInformationTransfer message. The UE <NUM> can transmit an RRC reconfiguration complete message in response to the additional RRC reconfiguration message. Thus, the UE <NUM> can communicate unicast data packets on the QoS flow with the CN <NUM> via the base station <NUM> (e.g., over the fifth DRB).

In some implementations, the base station <NUM> can transmit MBS data packets and unicast data packets over the same radio bearer (e.g., the fifth DRB or the sixth DRB) associated with the PDU session (e.g., if similar or the same QoS profiles apply to the MBS data packets and unicast data packets). For example, the UE <NUM> may establish a PDU session in response to a user of the UE <NUM> requesting a web browsing service. While browsing, the user may select an MBS service for viewing, such as a live sporting event. The DRB associated with the PDU session may be configured to transmit both unicast data packets related to the web browsing service and MBS data packets related to the sporting event. In other implementations, the base station transmits MBS data packets and unicast data packets over the fifth DRB and the sixth DRB respectively, e.g., if different QoS profiles apply to the MBS data packets and unicast data packets.

Referring next to <FIG>, during a scenario <NUM>, the base station <NUM> establishes PDU sessions with multiple UEs. The base station <NUM> can utilize the techniques illustrated in <FIG> to transmit MBS data packets over a multicast DRB to a first subset of UEs (i.e., using multicast configuration parameters) and MBS packets over unicast DRBs to respective UEs of a second subset of UEs.

To establish the PDU sessions, the base station <NUM> can utilize the techniques discussed above with reference to <FIG> to establish the PDU sessions. In particular, a UE 102A can perform 450A an MBS PDU session establishment procedure with a CN (e.g., the CN <NUM>) via the base station <NUM> similar to the MBS PDU session establishment procedure 350A or 350B. In some implementations, the UE 102A can perform a PDU session establishment procedure for both MBS and unicast services, similar to the PDU session establishment procedure 350C. Likewise, a UE 102B and a UE 102C perform 450B, 450C MBS PDU session establishment procedures, respectively, with the CN <NUM> via the base station <NUM>, which can be similar to procedures 350A-C. The base station <NUM> can perform the PDU session establishment procedures 450A-C in any order. While not depicted in <FIG> to avoid clutter, the scenario <NUM> may include additional messaging shown in <FIG>, such as MBS request messages and messages including MBS control information (e.g., events 314A-C, 320A-C).

The base station <NUM> can configure the UEs 102A-C to receive MBS data packets using either multicast or unicast configuration parameters. With respect to the UE 102C, for example, the base station <NUM> transmits 452C to the UE 102C an RRC reconfiguration message including unicast configuration parameters that the UE 102C is to use to receive an MBS service. The unicast configuration parameters may configure a unicast DRB. In response, the UE 102C transmits 454C an RRC reconfiguration complete message. The base station <NUM> can then transmit <NUM> MBS data packets to the UE 102C in accordance with the unicast configuration parameters. In the scenario <NUM>, the base station <NUM> transmits 452C the unicast configuration parameters in a dedicated RRC message.

Before or after transmitting 452C the unicast configuration parameters to the UE 102C, the base station <NUM> can transmit 442A to the UE 102A an RRC reconfiguration message including multicast configuration parameters that the UE 102A is to use to receive an MBS service, which may be the same MBS service that the UE 102C receives. In response, the UE 102A transmits 444A an RRC reconfiguration complete message to the base station <NUM>. The multicast configuration parameters may be common multicast configuration parameters that the base station <NUM> can also transmit to other UEs. For example, the base station <NUM> can transmit 442B to the UE 102B an RRC reconfiguration message including the common multicast configuration parameters. In response, the UE 102B transmits 444B an RRC reconfiguration complete message to the base station <NUM>. The base station <NUM> can transmit <NUM> MBS data packets for the MBS service to the UEs 102A and 102B in accordance with the common multicast configuration parameters. In some implementations, the multicast configuration parameters may include a DL BWP configuration configuring an MBS DL BWP.

In the scenario <NUM>, the base station <NUM> transmits 442A, 442B multicast configuration parameters to the individual UEs 102A and 102B using dedicated RRC messaging. In other scenarios, the base station <NUM> can broadcast the multicast configuration parameters in SIB(s) to UEs in the cell <NUM>, including the UE 102A and the UE 102B. UEs in the idle, inactive, or connected states can receive broadcasted parameters, and UEs in the connected state can receive the dedicated RRC messages.

In some implementations, before, during, or after the MBS PDU session establishment procedures 450A and 450B, the UE 102A and the UE 102B can perform unicast PDU session establishment Procedures 460A and 460B, respectively, with CN <NUM> via the base station <NUM>. The UE 102A and the UE 102B can then communicate 474A, 474B unicast packets with the CN <NUM> via the base station <NUM>.

Turning to <FIG>, a scenario <NUM> illustrates messaging that may occur between nodes of a distributed base station. The base station <NUM> includes a DU <NUM> and a CU <NUM>. The messages in the scenario <NUM> that the DU <NUM> and the CU <NUM> exchange may also occur in the scenarios illustrated by <FIG> and <FIG>. Further, while not depicted in <FIG> to avoid clutter, the scenario <NUM> may include additional messaging shown in <FIG>, such as MBS request messages and messages including MBS control information (e.g., events 314A-C, 320A-C).

Initially, the UE <NUM> performs <NUM> an MBS PDU session establishment procedure with a CN (e.g., the CN <NUM>) via the base station <NUM>, similar to the MBS PDU session establishment procedures 350A and 350B. In some implementations, the UE <NUM> performs a PDU session establishment procedure for both MBS and unicast services, similar to the PDU session establishment procedure 350C. In the MBS PDU Session establishment procedure, the UE <NUM> and the CU <NUM> exchanges messages with one another via the DU <NUM>. For example, the UE <NUM> transmits a message (e.g., PDU Session Establishment Request, RRC reconfiguration complete, MBS request, etc.) to the DU <NUM>, which in turn sends a CU to DU message (e.g., a UL RRC Message Transfer message) including the message to the CU <NUM>. Similarly, the CU <NUM> transmits a CU to DU message (e.g., a DL RRC Message Transfer message) including a message (e.g., PDU Session Establishment Accept, RRC reconfiguration, MBS control information, etc.) to the DU <NUM>, which in turn sends the message to the UE <NUM>.

The CU <NUM> transmits <NUM> a first CU to DU message to the DU <NUM> to request the DU to generate multicast configuration parameters for the UE <NUM>. The first CU to DU message can be, for example, a UE Context Setup Request message or a UE Context Modification Request message. The DU <NUM> can generate the multicast configuration parameters and transmit <NUM> the multicast configuration parameters to the CU <NUM> in a first DU to CU message. The first DU to CU message can be, for example, a UE Context Setup Response message or a UE Context Modification Response message. In the scenario <NUM>, the DU generates multicast configuration parameters (e.g., configuration parameters configuring an MRB). In other scenarios, the DU can generate unicast configuration parameters for receiving MBS transmissions, similar to the unicast configuration parameters that the base station <NUM> transmits at event 452C.

The CU <NUM> transmits <NUM> a second CU to DU message to the DU <NUM> including an RRC reconfiguration message including the multicast configuration parameters, and the DU <NUM> forwards <NUM> the RRC reconfiguration message to the UE <NUM>. In response, the UE <NUM> transmits <NUM> an RRC reconfiguration complete message to the DU <NUM>, which in turn transmits <NUM> the RRC reconfiguration complete message in a second DU to CU message to the CU <NUM>. The UE <NUM> communicates <NUM> MBS data packets with the CN <NUM> via the base station <NUM>, where the CU <NUM> transmits the MBS data packets to the UE <NUM> via the DU <NUM>.

<FIG> are flow diagrams of example methods that a base station and/or a UE can implement to manage exchange of control information and data related to MBS.

Turning first to <FIG>, an example method 600A can be implemented in a UE (e.g., the UE <NUM>, 102A, 102B, or 102C). At block 602A, the UE performs a PDU session establishment procedure with a CN (e.g., the CN <NUM>) via a RAN (e.g., the RAN <NUM>) to establish a PDU session for MBS transmissions (e.g., procedures 350A-C, 450A-C, <NUM>). At block 604A, the UE receives an RRC reconfiguration message including configuration parameters from the RAN (e.g., events 310A, 324B, 324C, 452C, 442A, 442B, or <NUM>, or similar events within procedures 350B, 350C, 450A-C, or <NUM>). The configuration parameters are associated with the PDU session established at block 602A. For example, the configuration parameters may configure a radio bearer (e.g., the configuration parameters may be unicast configuration parameters for a DRB or multicast configuration parameters for an MRB) associated with the PDU session.

Next, the UE receives at block 606A MBS packets of a first MBS service using the configuration parameters (e.g., events 338A-C, <NUM>, <NUM>, <NUM>). In some implementations, the UE also receives at block 608A MBS packets of a second MBS service using the configuration parameters.

Referring next to <FIG>, an example method 600B can be implemented in a UE (e.g., the UE <NUM>, 102A, 102B, or 102C). The method 600B is similar to the method 600A, except that the UE can receive different configuration parameters for receiving the first and the second MBS services, respectively. At block 602B, the UE performs a PDU session establishment procedure with a CN (e.g., the CN <NUM>) via a RAN (e.g., the RAN <NUM>) to establish a PDU session for MBS transmissions (e.g., procedures 350A-C, 450A-C, <NUM>). At block 604B, the UE receives, from the RAN, a first RRC reconfiguration message including first configuration parameters for receiving a first MBS service (e.g., events 310A, 324B, 324C, 452C, 442A, 442B, or <NUM>, or similar events within procedures 350B, 350C, 450A-C, or <NUM>). The first configuration parameters are associated with the PDU session established at block 602B. For example, the first configuration parameters may configure a radio bearer (e.g., the first configuration parameters may be unicast configuration parameters for a DRB or multicast configuration parameters for an MRB) associated with the PDU session. The UE then receives at block 606B MBS packets of the first MBS service from the RAN using the first configuration parameters (e.g., events 338A-C, <NUM>, <NUM>, <NUM>).

At block 608B, the UE also receives, from the RAN, a second RRC reconfiguration message including second configuration parameters for receiving a second MBS service. Similar to the first configuration parameters, the second configuration parameters may configure a radio bearer (e.g., a DRB or an MRB) associated with the PDU session. At block 610B, the UE receives MBS packets of the second MBS service from the RAN using the second configuration parameters.

Turning to <FIG>, an example method 700A can be implemented in a UE (e.g., the UE <NUM>, 102A, 102B, or 102C). At block 702A, the UE performs a PDU session establishment procedure with a CN (e.g., the CN <NUM>) via a RAN (e.g., the RAN <NUM>) to establish a PDU session for MBS transmissions (e.g., procedures 350A-C, 450A-C, <NUM>). At block 704A, the UE receives, from the RAN, a first RRC reconfiguration message including unicast configuration parameters associated with the PDU session (e.g., events 310A, 324B, 324C, 452C, or <NUM>, or similar events within procedures 350B, 350C, 450A-C, or <NUM>). The unicast configuration parameters may configure a unicast DRB. The UE can then receive at block 706A MBS packets of an MBS service from the RAN using the unicast configuration parameters (e.g., events 338A-C, <NUM>, <NUM>). Subsequently to block 706A, at block 708A, the UE receives, from the RAN, a second RRC reconfiguration message including multicast configuration parameters (e.g., events 310A, 324B, 324C, 442A, 442B, or <NUM>, or similar events within procedures 350B, 350C, 450A-C, or <NUM>). The multicast configuration parameters may be associated with the PDU session and may configure an MRB for receiving the MBS service. At block 710A, the UE can switch to receiving MBS packets of the MBS service from the RAN using the multicast configuration parameters (e.g., events 338A-C, <NUM>, <NUM>).

<FIG> illustrates an example method 700B, which can be implemented in a UE (e.g., the UE <NUM>, 102A, 102B, or 102C). The method 700B is similar to the method 700A, except that the UE initially receives MBS packets in accordance with multicast configuration parameters, and subsequently receives MBS packets in accordance with unicast configuration parameters.

At block 702B, the UE performs a PDU session establishment procedure with a CN (e.g., the CN <NUM>) via a RAN (e.g., the RAN <NUM>) to establish a PDU session for MBS transmissions (e.g., procedures 350A-C, 450A-C, <NUM>). At block 704B, the UE receives, from the RAN, a first RRC reconfiguration message including multicast configuration parameters associated with the PDU session (e.g., events 310A, 324B, 324C, 442A, 442B, or <NUM>, or similar events within procedures 350B, 350C, 450A-C, or <NUM>). The UE can then receive at block 706B MBS packets of an MBS service from the RAN using the multicast configuration parameters (e.g., events 338A-C, <NUM>, <NUM>). Subsequently to block 706B, at block 708B, the UE receives, from the RAN, a second RRC reconfiguration message including unicast configuration parameters (e.g., e.g., events 310A, 324B, 324C, 452C, or <NUM>, or similar events within procedures 350B, 350C, 450A-C, or <NUM>). The unicast configuration parameters may be associated with the PDU session and may configure a unicast DRB for receiving the MBS service. At block 710B, the UE can switch to receiving MBS packets of the MBS service from the RAN using the unicast configuration parameters (e.g., event 338A-C, <NUM>, <NUM>).

<FIG> illustrates an example method 700C, which can be implemented in a UE (e.g., the UE <NUM>, 102A, 102B, or 102C). The method 700C is similar to the methods 700A and 700B, except that the UE can use configuration parameters in a first RRC reconfiguration message to receive a first MBS service, and configuration parameters in a second RRC reconfiguration message to receive a second MBS service.

At block 702C, the UE performs a PDU session establishment procedure with a CN (e.g., the CN <NUM>) via a RAN (e.g., the RAN <NUM>) to establish a PDU session for MBS transmissions (e.g., procedures 350A-C, 450A-C, <NUM>). At block 704C, the UE receives, from the RAN, a first RRC reconfiguration message including unicast configuration parameters associated with the PDU session (e.g., e.g., events 310A, 324B, 324C, 452C, or <NUM>, or similar events within procedures 350B, 350C, 450A-C, or <NUM>). The UE can then receive at block 706C MBS packets of a first MBS service from the RAN using the unicast configuration parameters (e.g., events 338A-C, <NUM>, <NUM>). At block 708C, the UE receives, from the RAN, a second RRC reconfiguration message including multicast configuration parameters (e.g., events 310A, 324B, 324C, 442A, 442B, or <NUM>, or similar events within procedures 350B, 350C, 450A-C, or <NUM>). The multicast configuration parameters may be associated with the PDU session and may configure an MRB for receiving an MBS service. At block 710C, the UE can switch to receiving MBS packets of a second MBS service from the RAN using the multicast configuration parameters (e.g., event 338A-C, <NUM>, <NUM>). While <FIG> illustrates using unicast configuration parameters to receive a first MBS service and multicast configuration parameters to receive a second MBS service, the UE can implement a similar method to first use multicast configuration parameters to receive the first MBS service, and subsequently use unicast configuration parameters to receive the second MBS service. In some implementations, the UE can simultaneously receive MBS packets of the first MBS service from the RAN using the unicast configuration parameters and receive MBS packets of the second MBS service from the RAN using the multicast configuration parameters.

Turning to <FIG>, an example method <NUM> can be implemented in a UE (e.g., the UE <NUM>, 102A, 102B, or 102C). In the method <NUM>, the UE transmits an MBS request via a first DRB associated with a PDU session, and receives MBS packets of an MBS service over a second DRB associated with the PDU session.

At block <NUM>, the UE performs a PDU session establishment procedure with a CN (e.g., the CN <NUM>) via a RAN (e.g., the RAN <NUM>) to establish a PDU session for MBS transmissions (e.g., procedures 350A-C, 450A-C, <NUM>). At block <NUM>, the UE receives, from the RAN, a first RRC reconfiguration message configuring a first DRB (e.g., a unicast DRB or an MRB) associated with the PDU session (e.g., event <NUM> or similar events during procedures 350B, 350C, 450A-C, or <NUM>). At block <NUM>, the UE transmits an MBS request via the first DRB requesting an MBS service (e.g., events 314A-C). In response to the MBS request, at block <NUM>, the UE receives, from the RAN, a second RRC reconfiguration message configuring a second DRB (e.g., a unicast DRB or an MRB) associated with the PDU session (e.g., events 342B, 342C). At block <NUM>, the UE receives MBS packets of the MBS service over the second DRB from the RAN (e.g., events 338B, 338C).

Referring next to <FIG>, a base station (e.g., the base station <NUM>, 106A, or 106B) can implement an example method 900A. The method 900A is similar to the method 600A, but the method 900A includes steps implemented by the base station rather than the UE.

At block 902A, the base station receives, from a CN (e.g., the CN <NUM>), a CN to BS interface message requesting configuration of radio resources for a PDU session of a UE (e.g., the UE <NUM>, 102A, 102B, or 102C) (e.g., event 306A, 322B, 322C or similar events within procedures 350B, 350C, 450A-C, or <NUM>). At block 904A, the base station transmits, to the UE in response to the CN to BS interface message, an RRC reconfiguration message including configuration parameters (e.g., events 310A, 324B, 324C, 452C, 442A, 442B, or <NUM>, or similar events within procedures 350B, 350C, 450A-C, or <NUM>). For example, the configuration parameters may configure a radio bearer (e.g., the configuration parameters may be unicast configuration parameters for a DRB or multicast configuration parameters for an MRB) associated with the PDU session. At block 906A, the base station sends a BS to CN interface message to the CN to indicate that configuration of radio resources for the UE is successful (e.g., events 328B, 328C).

At block 908A, the base station transmits MBS packets of a first MBS service to the UE using the configuration parameters associated with the PDU session (e.g., events 338A-C, <NUM>, <NUM>, <NUM>). In some implementations, the base station also transmits at block 910A MBS packets of a second MBS service using the configuration parameters.

<FIG> illustrates an example method 900B that can be implemented in a base station (e.g., the base station <NUM>, 106A, or 106B). The method 900B is similar to the method 900A, except that the base station can transmit a first and a second MBS service using different configuration parameters. Likewise, the method 900B is similar to the method 600B, but the method 900B includes steps implemented by the base station rather than the UE.

At block 902B, the base station receives, from a CN (e.g., the CN <NUM>), a first CN to BS interface message requesting configuration of radio resources for a PDU session of a UE (e.g., the UE <NUM>, 102A, 102B, or 102C) (e.g., event 306A, 322B, 322C or similar events within procedures 350B, 350C, 450A-C, or <NUM>). At block 904B, the base station transmits, to the UE in response to the first CN to BS interface message, a first RRC reconfiguration message including first configuration parameters (e.g., events 310A, 324B, 324C, 452C, 442A, 442B, or <NUM>, or similar events within procedures 350B, 350C, 450A-C, or <NUM>). For example, the first configuration parameters may configure a radio bearer (e.g., the first configuration parameters may be unicast configuration parameters for a DRB or multicast configuration parameters for an MRB) associated with the PDU session. At block 906B, the base station sends a first BS to CN interface message to the CN to indicate that configuration of radio resources for the UE is successful (e.g., events 328B, 328C). At block 908B, the base station transmits MBS packets of a first MBS service to the UE using the first configuration parameters (e.g., events 338A-C, <NUM>, <NUM>, <NUM>).

At block 909B, the base station receives, from the CN, a second CN to BS interface message requesting configuration of radio resources for the PDU session of the UE (e.g., the UE <NUM>, 102A, 102B, or 102C) (e.g., event 306A, 322B, 322C or similar events within procedures 350B, 350C, 450A-C, or <NUM>). At block 910B, the base station transmits to the UE a second RRC reconfiguration message including second configuration parameters in response to the second CN to BS interface message. Similar to the first configuration parameters, the second configuration parameters may configure a radio bearer (e.g., a DRB or an MRB) associated with the PDU session. At block 912B, the base station sends to the CN a second BS to CN interface message to indicate that configuration of radio resources for the UE is successful. At block 914B, the base station transmits MBS packets of a second MBS service to the UE using the second configuration parameters.

In one implementation, the CN can request configuration of radio resources for a first QoS flow and a second QoS flow in the first CN to BS interface message and the second CN to BS interface message, respectively. Accordingly, the base station configures the configuration parameters for the first QoS flow and the configuration parameters for the second QoS flow in the first RRC reconfiguration message and the second RRC reconfiguration message, respectively. In another implementation, the CN can request configuration of radio resources for a first QoS flow and a second QoS flow in a single CN to BS interface message (i.e., the first CN to BS interface message). In this case, the event 909B can be skipped. The base station configures the configuration parameters for the first QoS flow and second QoS flow in the first RRC reconfiguration message and the second RRC reconfiguration message, respectively. Alternatively, the base station configures the configuration parameters for the first QoS flow and second QoS flow in a single RRC reconfiguration message (i.e., the first RRC reconfiguration message). The base station indicates the configuration of radio resources is successful for the first and second QoS flows either at the event 906B or 912B, i.e. one of the events 906B or 912B can be skipped.

In either implementation above, the CN sends MBS packets of the first MBS on the first QoS flow and sends the MBS packets of the second MBS on the second QoS flow to the base station, which in turn transmits the MBS packets of the first MBS and the MBS packets of the second MBS to the UE using the first configuration parameters and the second configuration parameters, respectively.

Turning to <FIG>, a base station (e.g., the base station <NUM>, 106A, or 106B) can implement an example method 1000A. The method 1000A is similar to the method 700A, but the method 1000A includes steps implemented by the base station rather than the UE. At block 1002A, the base station receives, from a CN (e.g., the CN <NUM>), a first CN to BS interface message requesting configuration of radio resources for a PDU session of a UE (e.g., the UE <NUM>, 102A, 102B, or 102C) (e.g., event 306A, 322B, 322C or similar events within procedures 350B, 350C, 450A-C, or <NUM>). At block 1004A, the base station transmits to the UE a first RRC reconfiguration message including unicast configuration parameters, in response to the CN to BS interface message (e.g., events 310A, 324B, 324C, 452C, or <NUM>, or similar events within procedures 350B, 350C, 450A-C, or <NUM>). The unicast configuration parameters may configure a unicast DRB. The base station then transmits at block 1006A MBS packets of an MBS service to the UE using the unicast configuration parameters (e.g., events 338A-C, <NUM>, <NUM>). Subsequently to block 1006A, at block 1008A, the base station transmits to the UE a second RRC reconfiguration message including multicast configuration parameters (e.g., events 310A, 324B, 324C, 442A, 442B, or <NUM>, or similar events within procedures 350B, 350C, 450A-C, or <NUM>). At block 1010A, the base station transmits MBS packets of the MBS service to the UE using the multicast configuration parameters (e.g., events 338A-C, <NUM>, <NUM>).

<FIG> illustrates an example method 1000B that can be implemented in a base station (e.g., the base station <NUM>, 106A, or 106B). The method 1000B is similar to the method 1000A, except that the base station initially transmits MBS packets in accordance with multicast configuration parameters, and subsequently transmits MBS packets in accordance with unicast configuration parameters. Likewise, the method 1000B is similar to the method 700B, but the method 1000B includes steps implemented by the base station rather than the UE.

At block 1002B, the base station receives, from a CN (e.g., the CN <NUM>), a first CN to BS interface message requesting configuration of radio resources for a PDU session of a UE (e.g., the UE <NUM>, 102A, 102B, or 102C) (e.g., event 306A, 322B, 322C or similar events within procedures 350B, 350C, 450A-C, or <NUM>). At block 1004B, the base station transmits to the UE a first RRC reconfiguration message including multicast configuration parameters, in response to the CN to BS interface message (e.g., events 310A, 324B, 324C, 442A. 442B, or <NUM>, or similar events within procedures 350B, 350C, 450A-C, or <NUM>). The base station then transmits at block 1006B MBS packets of an MBS service to the UE using the multicast configuration parameters (e.g., events 338A-C, <NUM>, <NUM>). Subsequently to block 1006B, at block 1008B, the base station transmits to the UE a second RRC reconfiguration message including unicast configuration parameters (e.g., events 310A, 324B, 324C, 452C, or <NUM>, or similar events within procedures 350B, 350C, 450A-C, or <NUM>). At block 1010B, the base station transmits MBS packets of the MBS service to the UE using the unicast configuration parameters (e.g., events 338A-C, <NUM>, <NUM>).

<FIG> illustrates an example method 1000C that can be implemented in a base station (e.g., the base station <NUM>, 106A, or 106B). The method 1000C is similar to the methods 1000A and 1000B, except that the base station initially transmits MBS packets of a first MBS service in accordance with unicast configuration parameters, and subsequently transmits MBS packets of a second MBS service in accordance with multicast configuration parameters. Likewise, the method 1000C is similar to the method 700C, but the method 1000C includes steps implemented by the base station rather than the UE.

At block 1002C, the base station receives, from a CN (e.g., the CN <NUM>), a first CN to BS interface message requesting configuration of radio resources for a PDU session of a UE (e.g., the UE <NUM>, 102A, 102B, or 102C) (e.g., event 306A, 322B, 322C or similar events within procedures 350B, 350C, 450A-C, or <NUM>). At block 1004C, the base station transmits to the UE a first RRC reconfiguration message including unicast configuration parameters, in response to the CN to BS interface message (e.g., events 310A, 324B, 324C, 452C, or <NUM>, or similar events within procedures 350B, 350C, 450A-C, or <NUM>). The base station then transmits at block 1006C MBS packets of a first MBS service to the UE using the unicast configuration parameters (e.g., events 338A-C, <NUM>, <NUM>). At block 1008C, the base station transmits to the UE a second RRC reconfiguration message including multicast configuration parameters (e.g., events 310A, 324B, 324C, 442A, 442B, or <NUM>, or similar events within procedures 350B, 350C, 450A-C, or <NUM>). At block 1010C, the base station transmits MBS packets of a second MBS service to the UE using the multicast configuration parameters (e.g., events 338A-C, <NUM>, <NUM>). While <FIG> illustrates using unicast configuration parameters to transmit a first MBS service and multicast configuration parameters to transmit a second MBS, the base station can implement a similar method to first use multicast configuration parameters to transmit the first MBS service, and subsequently use unicast configuration parameters to transmit the second MBS service. In some implementations, the base station stops transmitting MBS packets of the first MBS to the UE after transmitting MBS packets of the second MBS, e.g., if the UE switches to receiving MBS packets of the second MBS from the BS. In other implementations, the base station continues transmitting MBS packets of the first MBS to the UE if the UE is capable of simultaneously receiving the first MBS and second MBS or if the UE does not indicate that the UE is no longer interested in receiving the first MBS or does not indicate that the UE wishes to stop receiving the first MBS.

Turning to <FIG>, an example method <NUM> can be implemented in a base station (e.g., the base station <NUM>, 106A, or 106B). The method <NUM> is similar to the method <NUM>, but the method <NUM> includes steps implemented by the base station rather than the UE. At block <NUM>, the base station receives from a CN (e.g., the CN <NUM>) a first CN to BS interface message requesting resources for a PDU session (e.g., event 306A or similar events during procedures 350B, 350C, 450A-C, or <NUM>). At block <NUM>, the base station transmits to a UE (e.g., the UE <NUM>, 102A, 102B, or 102C) a first RRC reconfiguration message configuring a first DRB (e.g., a unicast DRB or an MRB) associated with the PDU session (e.g., event <NUM> or similar events during procedures 350B, 350C, 450A-C, or <NUM>). At block <NUM>, the base station receives an MBS request from the UE via the first DRB request an MBS service (e.g., events 314A-C). The base station may forward the MBS request to the CN (e.g., events 316A-C). At block <NUM>, the base station receives from the CN a second CN to BS interface message request resources for the PDU session (e.g., events 322B, 322C). In response, the base station transmits at block <NUM> a second RRC reconfiguration message to the UE configuring a second DRB (e.g., a unicast DRB or an MRB) associated with the PDU session (e.g., events 342B, 342C). At block <NUM>, the base station transmits MBS packets of the MBS service over the second DRB to the UE (e.g., events 338B, 338C).

In some implementations, the CN can request configuration of radio resources for a first QoS flow and a second QoS flow in the first CN to BS interface message and second CN to BS interface message, respectively. Accordingly, the base station configures the first DRB for the first QoS flow and the second DRB for the second QoS flow in the first RRC reconfiguration message and the second RRC reconfiguration message, respectively. The CN sends MBS data packets of the MBS on the second QoS flow to the base station, which in turn transmits the MBS data packets of the MBS to the UE over the second DRB. The CN may transmit MBS control information of the MBS on the first QoS flow to the base station, which in turn transmits the MBS control information over the first DRB.

Referring next to <FIG>, an example method <NUM> can be implemented in a CU (e.g., the CU <NUM>). At block <NUM>, the CU sends a CU to DU message to a DU (e.g., the DU <NUM>) to request an MBS service (e.g., event <NUM>). At block <NUM>, the CU receives a DU to CU message from the DU that includes multicast configuration parameters (e.g., event <NUM>). Next, at block <NUM>, the CU transmits an RRC reconfiguration message including the multicast configuration parameters to a UE (e.g., the UE <NUM>, 102A, 102B, or 102C) via the DU (e.g., events <NUM>, <NUM>). At block <NUM>, the CU transmits MBS packets of the MBS service to the UE via the DU (e.g., event <NUM>).

Referring next to <FIG>, an example method <NUM> can be implemented in a DU (e.g., the DU <NUM>). At block <NUM>, the DU receives a CU to DU message from a CU (e.g., the CU <NUM>) requesting an MBS service (e.g., event <NUM>). At block <NUM>, the DU sends a DU to CU message including multicast configuration parameters to the CU in response to the CU to DU message (e.g., event <NUM>). The DU can then transmit at block <NUM> MBS packets of the MBS service to a UE (e.g., the UE <NUM>, 102A, 102B, or 102C) using the multicast configuration parameters (e.g., event <NUM>).

Turning to <FIG>, an example method <NUM> can be implemented in a base station (e.g., the base station <NUM>, 106A, or 106B) for managing communication of MBS. The base station can perform the method <NUM> using processing hardware (e.g., the processing hardware <NUM> or <NUM>). At block <NUM>, the base station causes establishment of a session (e.g., a PDU session) for transmitting MBS data packets from a CN (e.g., the CN <NUM>) to a UE (e.g., the UE <NUM>, 102A, 102B, or 102C) (e.g., procedures 350B, 350C, 450A-C, or <NUM>). Causing the establishment of the session may include configuring radio resources (e.g., DRBs) for the session. At block <NUM>, the base station transmits configuration parameters associated with the session to the UE (e.g., events 310A, 324B, 324C, 452C, 442A, 442B, or <NUM>, or similar events within procedures 350B, 350C, 450A-C, or <NUM>). The configuration parameters can be unicast configuration parameters (e.g., parameters configuring a unicast DRB) or multicast configuration parameters (e.g., parameters configuring a multicast DRB, such as an MRB). At block <NUM>, the base station transmits MBS data packets to the UE in accordance with the configuration parameters (e.g., events 338A-C, <NUM>, <NUM>, <NUM>).

Referring next to <FIG>, an example method <NUM> can be implemented in a UE (e.g., the UE <NUM>, 102A, 102B, or 102C) for managing reception of MBS. The UE can perform the method <NUM> using processing hardware (e.g., the processing hardware <NUM>). At block <NUM>, the UE establishes a session (e.g., a PDU session) for receiving MBS data packets from a CN (e.g., the CN <NUM>) via a base station (e.g., the base station <NUM>, 106A, or 106B) (e.g., procedures 350B, 350C, 450A-C, or <NUM>). At block <NUM>, the UE receives configuration parameters associated with the session from the base station (e.g., events 310A, 324B, 324C, 452C, 442A, 442B, or <NUM>, or similar events within procedures 350B, 350C, 450A-C, or <NUM>). The configuration parameters can be unicast configuration parameters (e.g., parameters configuring a unicast DRB) or multicast configuration parameters (e.g., parameters configuring a multicast DRB, such as an MRB). At block <NUM>, the UE receives MBS data packets from the base station in accordance with the configuration parameters (e.g., events 338A-C, <NUM>, <NUM>, <NUM>).

Claim 1:
A method in a base station for managing communication of multicast and/or broadcast services, MBMS, the method comprising:
causing (350A), by the base station, establishment of a first protocol data unit, PDU, session for transmitting MBS data packets of an MBS service from a core network,CN, (ON) to a first user equipment, UE, the causing including
receiving (302A), from the first UE, a first request to establish the first PDU session, the first request indicating the MBS service, and
transmitting (304A) the first request to the CN;
transmitting (<NUM>,308A)), to the first UE, configuration parameters associated with the first PDU session;
causing (450B) establishment of a second PDU session for transmitting the MBS data packets from the CN to a second UE, the causing including
receiving, from the second UE, a second request to establish the second PDU session, the second request indicating the MBS service, and
transmitting the second request to the CN;
transmitting (452C), to the second UE, the configuration parameters; and
transmitting (<NUM>), to the first UE and the second UE, the MBS data packets in accordance with the configuration parameters.