Patent Description:
Aspects of the present disclosure generally relate to wireless communication and specifically, to a method and an apparatus for maintaining a multicast/broadcast radio bearer in an idle state or an inactive state.

Typical wireless communication systems may employ multiple-access technologies capable of supporting communication with multiple users by sharing available system resources (for example, bandwidth, or transmit power, among other examples, or a combination thereof).

The above multiple access technologies have been adopted in various telecommunication standards to provide a common protocol that enables different user equipments (UEs) to communicate on a municipal, national, regional, and even global level. New Radio (NR), which may also be referred to as <NUM>, is a set of enhancements to the LTE mobile standard promulgated by the 3GPP. NR is designed to better support mobile broadband Internet access by improving spectral efficiency, lowering costs, improving services, making use of new spectrum, and better integrating with other open standards using orthogonal frequency division multiplexing (OFDM) with a cyclic prefix (CP) (CP-OFDM) on the downlink (DL), using CP-OFDM or SC-FDMA (for example, also known as discrete Fourier transform spread OFDM (DFT-s-OFDM)) on the uplink (UL), as well as supporting beamforming, multiple-input multiple-output (MIMO) antenna technology, and carrier aggregation. Preferably, these improvements are applicable to other multiple access technologies and the telecommunication standards that employ these technologies.

Support for multicast or broadcast (sometimes referred to herein as multicast/broadcast) services is being added to NR. In NR, a UE may be capable of receiving, for example, multicast/broadcast services in a mixed mode or a broadcast mode. Using mixed mode, multicast/broadcast services may be delivered using either a multicast/broadcast radio bearer (MRB) or a dedicated radio bearer (DRB) for a UE in a radio resource control (RRC) connected state. Using broadcast mode, multicast/broadcast services may be delivered using an MRB for a UE in an RRC connected state, an RRC idle state, or an RRC inactive state. However, the delivery of multicast/broadcast services in the RRC idle state or the RRC inactive state may increase UE power consumption for these states that were, on the contrary, designed to reduce UE power consumption. "<NPL>, and "<NPL>) are prior art to the subject matter of this invention.

The following aspects are not part of the claimed invention but merely examples helpful to understand the invention. In some aspects, a non-transitory computer-readable medium may store one or more instructions for wireless communication. The one or more instructions, when executed by one or more processors of a UE, may cause the UE to receive a configuration for an MRB in an RLC acknowledged mode. The one or more instructions may cause the UE to enter an idle state or an inactive state after the MRB has been configured. The one or more instructions may cause the UE to maintain the MRB while the UE is in the idle state or the inactive state subject to one or more limitations associated with maintaining the MRB in the idle state or the inactive state.

In some aspects, an apparatus for wireless communication may include means for receiving a configuration for an MRB in an RLC acknowledged mode. The apparatus may include means for entering an idle state or an inactive state after the MRB has been configured. The apparatus may include means for maintaining the MRB while the apparatus is in the idle state or the inactive state subject to one or more limitations associated with maintaining the MRB in the idle state or the inactive state.

In some aspects, a method of wireless communication performed by a UE includes receiving a configuration for an MRB in an RLC acknowledged mode. The method may include storing a context associated with the MRB in a memory of the UE based at least in part on the configuration. The method may include entering an idle state or an inactive state, after the MRB has been configured and the context has been stored, without removing the context from the memory. The method may include maintaining the MRB while the UE is in the idle state or the inactive state subject to one or more limitations associated with maintaining the MRB in the idle state or the inactive state based at least in part on entering the idle state or the inactive state without removing the context from the memory.

In some aspects, a UE for wireless communication includes a memory and one or more processors operatively coupled to the memory. The memory and the one or more processors may be configured to receive a configuration for an MRB in an RLC acknowledged mode. The memory and the one or more processors may be configured to store a context associated with the MRB in the memory based at least in part on the configuration. The memory and the one or more processors may be configured to enter an idle state or an inactive state, after the MRB has been configured and the context has been stored, without removing the context from the memory. The memory and the one or more processors may be configured to maintain the MRB while the UE is in the idle state or the inactive state subject to one or more limitations associated with maintaining the MRB in the idle state or the inactive state based at least in part on entering the idle state or the inactive state without removing the context from the memory.

In some aspects, a non-transitory computer-readable medium may store one or more instructions for wireless communication. The one or more instructions, when executed by one or more processors of a UE, may cause the UE to receive a configuration for an MRB in an RLC acknowledged mode. The one or more instructions may cause the UE to store a context associated with the MRB in the memory based at least in part on the configuration. The one or more instructions may cause the UE to enter an idle state or an inactive state, after the MRB has been configured and the context has been stored, without removing the context from the memory. The one or more instructions may cause the UE to maintain the MRB while the UE is in the idle state or the inactive state subject to one or more limitations associated with maintaining the MRB in the idle state or the inactive state based at least in part on entering the idle state or the inactive state without removing the context from the memory.

In some aspects, an apparatus for wireless communication may include means for receiving a configuration for an MRB in an RLC acknowledged mode. The apparatus may include means for storing a context associated with the MRB in a memory of the UE based at least in part on the configuration. The apparatus may include means for entering an idle state or an inactive state, after the MRB has been configured and the context has been stored, without removing the context from the memory. The apparatus may include means for maintaining the MRB while the UE is in the idle state or the inactive state subject to one or more limitations associated with maintaining the MRB in the idle state or the inactive state based at least in part on entering the idle state or the inactive state without removing the context from the memory.

Aspects generally include a method, apparatus, system, computer program product, non-transitory computer-readable medium, user equipment, base station, wireless communication device, or processing system as substantially described with reference to and as illustrated by the drawings and specification.

The foregoing has outlined rather broadly the features and technical advantages of examples in accordance with the disclosure in order that the detailed description that follows may be better understood.

It is to be noted, however, that the appended drawings illustrate only some typical aspects of this disclosure and are therefore not to be considered limiting of its scope, for the description may admit to other equally effective aspects.

This disclosure may, however, be embodied in many different forms and are not to be construed as limited to any specific structure or function presented throughout this disclosure. Based on the teachings herein one skilled in the art may appreciate that the scope of the disclosure is intended to cover any aspect of the disclosure disclosed herein, whether implemented independently of or combined with any other aspect of the disclosure. For example, an apparatus may be implemented or a method may be practiced using any quantity of the aspects set forth herein. Any aspect of the disclosure disclosed herein may be embodied by one or more elements of a claim.

These apparatuses and techniques will be described in the following detailed description and illustrated in the accompanying drawings by various blocks, modules, components, circuits, steps, processes, or algorithms, among other examples, or combinations thereof (collectively referred to as "elements").

Support for multicast or broadcast (sometimes referred to herein as multicast/broadcast) services is being added to New Radio (NR). In NR, a user equipment (UE) may be capable of receiving, for example, multicast/broadcast services in a mixed mode or a broadcast mode. Using mixed mode, multicast/broadcast services may be delivered using either a multicast/broadcast radio bearer (MRB) or a dedicated radio bearer (DRB) for a UE in a radio resource control (RRC) connected state. Using broadcast mode, multicast/broadcast services may be delivered using an MRB for a UE in an RRC connected state, an RRC idle state, or an RRC inactive state. However, the delivery of multicast/broadcast services in the RRC idle state or the RRC inactive state may increase UE power consumption for these states that were, on the contrary, designed to reduce UE power consumption.

Various aspects generally relate to maintaining an MRB in an RRC idle state or an RRC inactive state. Some aspects more specifically relate to maintaining the MRB while the UE is in the RRC idle state or the RRC inactive state subject to one or more limitations associated with maintaining the MRB in the RRC idle state or the RRC inactive state. In some aspects, the procedures for receiving multicast/broadcast traffic in the RRC idle state or the RRC inactive state may differ from corresponding procedures in the RRC connected state due to different operating characteristics associated with these states. Thus, in some aspects, the one or more limitations apply to the MRB while the UE is in the RRC idle state or the RRC inactive state, and do not apply to the MRB while the UE is in an RRC connected state. In some aspects, the one or more limitations relate to permitted signaling in the idle/inactive state or the use of one or more timers by the UE in the idle/inactive state, among other examples.

Particular aspects of the subject matter described in this disclosure can be implemented to realize one or more of the following potential advantages. In some examples, the described techniques can be used to enable a UE to reliably receive multicast/broadcast traffic while in an RRC idle state or an RRC inactive state. Furthermore, the described techniques can be used to conserve power or other UE resources in the RRC idle state or the RRC inactive state (e.g., as compared to the RRC connected state) while enabling reliable reception of multicast/broadcast traffic.

<FIG> is a block diagram illustrating an example wireless network in accordance with various aspects of the present disclosure. The wireless network may be a Long Term Evolution (LTE) network or some other wireless network, such as a <NUM> or NR network. The wireless network may include a quantity of base stations (BSs) <NUM> (shown as BS 110a, BS 110b, BS 110c, and BS 110d) and other network entities. A BS is an entity that communicates with user equipment (UE(s)) and may also be referred to as a Node B, an eNodeB, an eNB, a gNB, a NR BS, a <NUM> node B (NB), an access point (AP), or a transmit receive point (TRP), among other examples, or combinations thereof (these terms are used interchangeably herein). In 3GPP, the term "cell" can refer to a coverage area of a BS or a BS subsystem serving this coverage area, depending on the context in which the term is used.

A BS may provide communication coverage for a macro cell, a pico cell, a femto cell, or another type of cell. A macro cell may cover a relatively large geographic area (for example, several kilometers in radius) and may allow unrestricted access by UEs with service subscription. A femto cell may cover a relatively small geographic area (for example, a home) and may allow restricted access by UEs having association with the femto cell (for example, UEs in a closed subscriber group (CSG)). A BS may support one or multiple (for example, three) cells.

The wireless network may be a heterogeneous network that includes BSs of different types, for example, macro BSs, pico BSs, femto BSs, or relay BSs, among other examples, or combinations thereof. These different types of BSs may have different transmit power levels, different coverage areas, and different impacts on interference in the wireless network. For example, macro BSs may have a high transmit power level (for example, <NUM> to <NUM> Watts) whereas pico BSs, femto BSs, and relay BSs may have lower transmit power levels (for example, <NUM> to <NUM> Watts). A network controller <NUM> may couple to the set of BSs 102a, 102b, 110a and 110b, and may provide coordination and control for these BSs. The BSs may also communicate with one another, for example, directly or indirectly via a wireless or wireline backhaul.

In some aspects, a cell may not be stationary, rather, the geographic area of the cell may move in accordance with the location of a mobile BS. In some aspects, the BSs may be interconnected to one another or to one or more other BSs or network nodes (not shown) in the wireless network through various types of backhaul interfaces such as a direct physical connection, or a virtual network, among other examples, or combinations thereof using any suitable transport network.

The wireless network may also include relay stations. A relay station is an entity that can receive a transmission of data from an upstream station (for example, a BS or a UE) and send a transmission of the data to a downstream station (for example, a UE or a BS). In the example shown in <FIG>, a relay station <NUM>10d may communicate with macro BS 110a and a UE 120d in order to facilitate communication between BS 110a and UE 120d. A relay station may also be referred to as a relay BS, a relay base station, or a relay, among other examples, or combinations thereof.

UEs <NUM> (for example, 120a, 120b, 120c) may be dispersed throughout the wireless network, and each UE may be stationary or mobile. A UE may also be referred to as an access terminal, a terminal, a mobile station, a subscriber unit, or a station, among other examples, or combinations thereof. A UE may be a cellular phone (for example, a smart phone), a personal digital assistant (PDA), a wireless modem, a wireless communication device, a handheld device, a laptop computer, a cordless phone, a wireless local loop (WLL) station, a tablet, a camera, a gaming device, a netbook, a smartbook, an ultrabook, a medical device or equipment, biometric sensors/devices, wearable devices (smart watches, smart clothing, smart glasses, smart wrist bands, smart jewelry (for example, smart ring, smart bracelet)), an entertainment device (for example, a music or video device, or a satellite radio), a vehicular component or sensor, smart meters/sensors, industrial manufacturing equipment, a global positioning system device, or any other suitable device that is configured to communicate via a wireless medium.

MTC and eMTC UEs include, for example, robots, drones, remote devices, sensors, meters, monitors or location tags, among other examples, or combinations thereof, that may communicate with a base station, another device (for example, remote device), or some other entity. A wireless node may provide, for example, connectivity for or to a network (for example, a wide area network such as Internet or a cellular network) via a wired or wireless communication link. Some UEs may be considered Internet-of Things (IoT) devices, or may be implemented as NB-IoT (narrowband internet of things) devices. UE <NUM> may be included inside a housing that houses components of UE <NUM>, such as processor components, or memory components, among other examples, or combinations thereof.

In general, any quantity of wireless networks may be deployed in a given geographic area. Each wireless network may support a particular radio access technology (RAT) and may operate on one or more frequencies or frequency channels. A frequency may also be referred to as a carrier among other examples.

In some aspects, two or more UEs <NUM> (for example, shown as UE 120a and UE 120e) may communicate directly with one another using one or more sidelink channels (for example, without using a base station <NUM> as an intermediary). For example, the UEs <NUM> may communicate using peer-to-peer (P2P) communications, device-to-device (D2D) communications, a vehicle-to-everything (V2X) protocol (for example, which may include a vehicle-to-vehicle (V2V) protocol, or a vehicle-to-infrastructure (V2I) protocol, among other examples, or combinations thereof), or a mesh network, among other examples, or combinations thereof. In such examples, the UE <NUM> may perform scheduling operations, resource selection operations, or other operations described elsewhere herein as being performed by the base station <NUM>.

<FIG> is a block diagram illustrating an example base station (BS) in communication with a user equipment (UE) in a wireless network in accordance with various aspects of the present disclosure.

At base station <NUM>, a transmit processor <NUM> may receive data from a data source <NUM> for one or more UEs, select one or more modulation and coding schemes (MCSs) for each UE based at least in part on channel quality indicators (CQIs) received from the UE, process (for example, encode) the data for each UE based at least in part on the MCS(s) selected for the UE, and provide data symbols for all UEs. Transmit processor <NUM> may also process system information (for example, for semi-static resource partitioning information (SRPI) among other examples) and control information (for example, CQI requests, grants, or upper layer signaling, among other examples, or combinations thereof) and provide overhead symbols and control symbols. Transmit processor <NUM> may also generate reference symbols for reference signals (for example, the cell-specific reference signal (CRS)) and synchronization signals (for example, the primary synchronization signal (PSS) and secondary synchronization signal (SSS)). A transmit (TX) multiple-input multiple-output (MIMO) processor <NUM> may perform spatial processing (for example, precoding) on the data symbols, the control symbols, the overhead symbols, or the reference symbols, if applicable, and may provide T output symbol streams to T modulators (MODs) 232a through 232t. Each MOD <NUM> may process a respective output symbol stream (for example, for OFDM among other examples) to obtain an output sample stream. Each MOD <NUM> may further process (for example, convert to analog, amplify, filter, and upconvert) the output sample stream to obtain a downlink signal. T downlink signals from MODs 232a through 232t may be transmitted via T antennas 234a through 234t, respectively. In accordance with various aspects described in more detail below, the synchronization signals can be generated with location encoding to convey additional information.

At UE <NUM>, antennas 252a through 252r may receive the downlink signals from base station <NUM> or other base stations and may provide received signals to R demodulators (DEMODs) 254a through 254r, respectively. Each DEMOD <NUM> may condition (for example, filter, amplify, downconvert, and digitize) a received signal to obtain input samples. Each DEMOD <NUM> may further process the input samples (for example, for OFDM) to obtain received symbols. A MIMO detector <NUM> may obtain received symbols from all R DEMODs 254a through 254r, perform MIMO detection on the received symbols if applicable, and provide detected symbols. A receive processor <NUM> may process (for example, decode) the detected symbols, provide decoded data for UE <NUM> to a data sink <NUM>, and provide decoded control information and system information to a controller/processor <NUM>. A channel processor may determine a reference signal received power (RSRP), a received signal strength indicator (RSSI), a reference signal received quality (RSRQ), or a channel quality indicator (CQI), among other examples, or combinations thereof.

On the uplink, at UE <NUM>, a transmit processor <NUM> may receive and process data from a data source <NUM> as well as control information (for example, for reports including RSRP, RSSI, RSRQ, or CQI, among other examples, or combinations thereof) from controller/processor <NUM>. The symbols from transmit processor <NUM> may be precoded by a TX MIMO processor <NUM> if applicable, further processed by MODs 254a through 254r (for example, for discrete Fourier transform spread orthogonal frequency division multiplexing (DFT-s-OFDM), or orthogonal frequency division multiplexing (OFDM) with a cyclic prefix (CP) (CP-OFDM), among other examples, or combinations thereof), and transmitted to base station <NUM>. At base station <NUM>, the uplink signals from UE <NUM> and other UEs may be received by antennas <NUM>, processed by DEMODs <NUM>, detected by a MIMO detector <NUM> if applicable, and further processed by a receive processor <NUM> to obtain decoded data and control information sent by UE <NUM>.

Controller/processor <NUM> of base station <NUM>, controller/processor <NUM> of UE <NUM>, or any other component(s) of <FIG> may perform one or more techniques associated with maintaining a multicast/broadcast radio bearer in an idle state or an inactive state, as described in more detail elsewhere herein. For example, controller/processor <NUM> of base station <NUM>, controller/processor <NUM> of UE <NUM>, or any other component(s) of <FIG> may perform or direct operations of, for example, process <NUM> of <FIG>, process <NUM> of <FIG>, or other processes as described herein. Memories <NUM> and <NUM> may store data and program codes for base station <NUM> and UE <NUM>, respectively. A scheduler <NUM> may schedule UEs for data transmission on the downlink or uplink.

In some aspects, UE <NUM> may include means for receiving a configuration for an MRB in an RLC acknowledged mode; means for entering an idle state or an inactive state after the MRB has been configured; means for maintaining the MRB while the UE <NUM> is in the idle state or the inactive state subject to one or more limitations associated with maintaining the MRB in the idle state or the inactive state; among other examples. In some aspects, UE <NUM> includes means for exiting the idle state or the inactive state to enter a connected state. In some aspects, UE <NUM> includes means for communicating using the MRB while in the connected state using the configuration. In some aspects, UE <NUM> includes means for receiving one or more retransmissions via the MRB while in the idle state or the inactive state. In some aspects, UE <NUM> includes means for receiving a polling request, for triggering transmission of an RLC status report, while the UE <NUM> is in the idle state or the inactive state. In some aspects, UE <NUM> includes means for refraining from transmitting the RLC status report in response to the polling request based at least in part on the UE <NUM> being in the idle state or the inactive state and based at least in part on the one or more limitations.

In some aspects, UE <NUM> includes means for receiving a configuration for an MRB in an RLC acknowledged mode; means for storing a context associated with the MRB in a memory of the UE <NUM> based at least in part on the configuration; means for entering an idle state or an inactive state, after the MRB has been configured and the context has been stored, without removing the context from the memory; means for maintaining the MRB while the UE <NUM> is in the idle state or the inactive state subject to one or more limitations associated with maintaining the MRB in the idle state or the inactive state based at least in part on entering the idle state or the inactive state without removing the context from the memory; or a combination thereof.

In some aspects, the means for the UE <NUM> to perform operations or processes described herein may include one or more components of UE <NUM> described in connection with <FIG>, such as antenna <NUM>, demodulator <NUM>, MIMO detector <NUM>, receive processor <NUM>, transmit processor <NUM>, TX MIMO processor <NUM>, modulator <NUM>, controller/processor <NUM>, and/or memory <NUM>.

<FIG> is a block diagram illustrating a logical architecture of a distributed radio access network (RAN) in accordance with various aspects of the present disclosure. One or more entities of a <NUM> network may have a multicast/broadcast (MB) user plane function (MB-UPF) <NUM> and an access and mobility function (AMF) <NUM>. The MB-UPF <NUM> may have an N3 interface <NUM> for delivering an MB-flow <NUM> of packets (for example, in the form of protocol data units (PDUs)) to a <NUM> access node, such as a gNB. The AMF <NUM> may control signaling for MB-flow setup and modification using an N2 interface <NUM> with the gNB.

The gNB may include a central unit (CU), shown as gNB-CU <NUM>. The gNB may also include one or more distributed units (DUs), shown as DU1 <NUM> and DU2 <NUM>. The DU1 <NUM> and the DU2 <NUM> may be configured to individually (for example, via dynamic selection) or jointly (for example, via joint transmission) serve traffic to a UE. As shown, DU1 <NUM> may serve traffic to a first UE or a first group of UEs <NUM> using a first multicast/broadcast radio bearer (MRB), shown as MRB1 <NUM>, and DU2 <NUM> may serve traffic to a second UE or a second group of UEs <NUM> using a second MRB, shown as MRB2 <NUM>.

Support for multicast or broadcast (sometimes referred to herein as multicast/broadcast) services is being added to NR. In NR, a UE may be capable of receiving, for example, multicast/broadcast services in a mixed mode or a broadcast mode. Using mixed mode, multicast/broadcast services may be delivered using either an MRB (a multicast/broadcast bearer) or a dedicated radio bearer (DRB) for a UE in an RRC connected state. Using broadcast mode, multicast/broadcast services may be delivered using an MRB for a UE in an RRC connected state, an RRC idle state, or an RRC inactive state. Some techniques and apparatuses described herein enable a UE to reliably receive multicast/broadcast traffic while in an RRC idle state or an RRC inactive state. As described in more detail below, the procedures for receiving multicast/broadcast traffic in the RRC idle state or the RRC inactive state may differ from corresponding procedures in the RRC connected state due to different operating characteristics of these states.

<FIG> is a state machine diagram illustrating states of a radio resource control (RRC) procedure and transitions between the states in accordance with various aspects of the present disclosure. As shown, a UE may transition among an RRC connected state <NUM>, an RRC idle state <NUM>, and an RRC inactive state <NUM>. An RRC procedure may be used, for example, for connection establishment, re-establishment, or release between a UE and a base station, for on-demand transfer of system information, for suspension or resumption of an RRC connection, for signaling relating to handover, or for radio link handling, among other examples.

Upon powering on, a UE may enter the RRC idle state <NUM>. The UE may transition from the RRC idle state <NUM> to the RRC connected state <NUM> via RRC connection establishment <NUM> (sometimes referred to as attaching to the network). The UE may transition from the RRC connected state <NUM> to the RRC idle state <NUM> via RRC connection release <NUM> (sometimes referred to as detaching from the network) or due to a connection failure. Alternatively, the UE may transition from the RRC connected state <NUM> to the RRC inactive state <NUM> via RRC connection suspension <NUM> (also referred to as RRC suspend or RRC release with suspend). In the RRC inactive state, the UE maintains the RRC connection while reducing signaling and power consumption. In the RRC inactive state <NUM>, the UE may transition to the RRC connected state <NUM> via RRC connection resumption <NUM> (also referred to as RRC resume), or may transition to the RRC idle state <NUM> via RRC connection release <NUM> or due to a connection failure. In the RRC connected state <NUM> and the RRC inactive state <NUM>, the UE is registered with and connected to the core network. In the RRC idle state <NUM>, the UE is de-registered from the core network.

In the RRC connected state <NUM>, a core network to RAN connection may be established for the UE for both the user plane and the control plane, the UE may be capable of communicating using the RAN connection (for example, a base station connection) and the core network, the UE and the RAN may store an access stratum context for the UE, the RAN may store information indicating the cell that is serving the UE, unicast data may be transferred between the RAN and the UE, the network may control mobility of the UE (including, for example, UE measurements), and the UE may be capable of operating in a connected mode discontinuous reception (CDRX) mode for power saving.

In the RRC idle state <NUM>, the UE may be capable of selecting a public land mobile network (PLMN), receiving system information messages, having mobility for cell re-selection, receiving pages initiated and managed by the core network, and operating in a discontinuous reception (DRX) mode for power saving.

In the RRC inactive state <NUM>, the UE may be capable of receiving system information messages, having mobility for cell re-selection, receiving pages initiated and managed by the RAN, and operating in a DRX mode for power saving. Furthermore, an RRC connection between the UE and the RAN (and the RAN and the core network) remains established for the UE, the UE continues to store an access stratum context for the UE, and the RAN may continue to store information indicating the cell that is serving the UE. Because both the UE and the base station store an access stratum context for the UE in the RRC inactive state <NUM>, transitioning from the RRC inactive state <NUM> to the RRC connected state <NUM> does not require non-access stratum (NAS) signaling, which extends UE battery life and reduces latency in transitioning to the RRC connected state <NUM> as compared to transitioning from the RRC idle state <NUM> to the RRC connected state <NUM>. In some aspects, the UE may transition from the RRC connected state <NUM> to the RRC inactive state <NUM> due to lack of activity (for example, based at least in part on a timer).

Some techniques and apparatuses described herein enable a UE to reliably receive multicast/broadcast traffic while in an RRC idle state or an RRC inactive state. As described in more detail below, the procedures for receiving multicast/broadcast traffic in the RRC idle state or the RRC inactive state may differ from corresponding procedures in the RRC connected state due to different operating characteristics associated with these states.

<FIG> is a diagram illustrating a maintaining of a multicast/broadcast radio bearer in an idle state or an inactive state in accordance with the claimed invention As shown in <FIG>, a UE <NUM> and a base station <NUM> may communicate with one another.

In a first operation <NUM>, the base station <NUM> may transmit, to the UE <NUM>, a configuration for an MRB <NUM> in a radio link control (RLC) acknowledged mode (AM). In RLC AM, reliable transmission of multicast/broadcast traffic may be supported using acknowledgment (ACK) or negative acknowledgement (NACK) feedback and retransmissions. In some aspects, the ACK or NACK (sometimes referred to as ACK/NACK) feedback may be transmitted by the UE <NUM> in an RLC status report. In some aspects, the base station <NUM> may transmit the configuration in a configuration message, such as an RRC message (for example, an RRC configuration message or an RRC reconfiguration message, among other examples). The base station <NUM> and the UE <NUM> may establish an MRB <NUM> based at least in part on the MRB configuration.

As shown, the MRB configuration may indicate a multicast/broadcast control channel (MCCH) for transmission of multicast/broadcast control messages. Additionally or alternatively, the MRB configuration may indicate a multicast/broadcast traffic channel (MTCH) for transmission of multicast/broadcast data. For example, the MRB configuration may indicate resources (such as time domain resources, frequency domain resources, or spatial domain resources, among other examples) allocated to the MCCH and the MTCH. Additionally or alternatively, the MRB configuration may indicate a group radio network temporary identifier (G-RNTI) associated with the MRB <NUM>. The G-RNTI may be used to transmit (such as by scrambling) communications on the MRB <NUM> and to receive (such as by descrambling) communications on the MRB <NUM>. In some aspects, different multicast/broadcast subscriptions may be associated with different G-RNTIs.

Additionally or alternatively, the MRB configuration may indicate a retransmission configuration for multicast/broadcast traffic transmitted via the MRB <NUM>. For example, the MRB configuration may indicate whether retransmissions are unicast retransmissions (which may use a cell radio network temporary identifier (C-RNTI) in a similar manner as a G-RNTI), multicast/broadcast retransmissions (which may use a G-RNTI, as described above), or capable of being switched between unicast and multicast/broadcast. In some aspects, the retransmission configuration may indicate one or more resources to be used for retransmissions (for example, for preconfigured retransmissions).

Additionally or alternatively, the MRB configuration may indicate an idle/inactive state configuration for the MRB <NUM>. The term idle/inactive state may be used herein to refer to the idle state (such as an RRC idle state <NUM>), the inactive state (such as an RRC inactive state <NUM>), or both. In some aspects, the MRB configuration may indicate whether the MRB <NUM> is permitted to be maintained during the idle/inactive state (for example, to enable or disable multicast/broadcast communication via the MRB <NUM> in the idle/inactive state, or by continuing to store a context in memory rather than deleting the context upon exiting the RRC connected state and entering the idle/inactive state). Additionally or alternatively, the MRB configuration may indicate one or more limitations associated with the MRB <NUM> for the idle/inactive state. In some aspects, the one or more limitations apply to the MRB <NUM> while the UE <NUM> is in the idle state or the inactive state, and do not apply to the MRB <NUM> while the UE <NUM> is in a connected state (such as an RRC connected state). The one or more limitations may relate to, for example, permitted signaling in the idle/inactive state (such as signaling of an RLC status report or a response to a polling request, among other examples) or the use of one or more timers by the UE <NUM> in the idle/inactive state, among other examples. In some aspects, a limitation may disable, for the idle/inactive state, signaling that is used in the connected state. Additionally or alternatively, a limitation may disable a timer, that is used in the connected state, for the idle/inactive state.

Although the one or more limitations are described above and shown in <FIG> as being indicated in the MRB configuration, in some aspects, one or more limitations may not be signaled in the MRB configuration. For example, one or more limitations may be autonomously applied by the UE <NUM> in the idle/inactive state without receiving an indication of those one or more limitations.

In a second operation <NUM>, the base station <NUM> and the UE <NUM> may communicate in a connected mode, such as the RRC connected mode <NUM> described above in connection with <FIG>. For example, the base station <NUM> may transmit multicast/broadcast control information to the UE <NUM> via the MRB <NUM> (such as on the MCCH). The base station <NUM> may transmit multicast/broadcast data to the UE <NUM> via the MRB <NUM> (such as on the MTCH). When the connection between the UE <NUM> and the base station <NUM> is established (such as by an RRC connection establishment procedure), the UE <NUM> may transition from an RRC idle state <NUM> to an RRC connected state <NUM>.

To communicate in the RRC connected state <NUM> for multicast/broadcast services, a connection may be established between the base station <NUM> and a core network for both the user plane (such as via an N3 interface with an MB-UPF <NUM>) and the control plane (such as via an N2 interface with an AMF <NUM>). Additionally or alternatively, the UE <NUM> and the base station <NUM> may store an access stratum (AS) context for the UE <NUM>, the base station <NUM> may store information indicating the cell that is serving the UE <NUM>, multicast/broadcast data may be transferred between the base station <NUM> and the UE <NUM>, the AMF <NUM> may control mobility of the UE <NUM>, and the UE <NUM> may obtain and report measurements, among other examples.

In a third operation <NUM>, the UE <NUM> may transition from the connected state to an idle state or an inactive state after the MRB <NUM> has been configured, such as by exiting the connected state and entering one of the idle state or the inactive state. For example, the UE <NUM> may transition from an RRC connected state <NUM> to an RRC idle state <NUM> via RRC connection release <NUM> (sometimes referred to as detaching from the network). Alternatively, the UE may transition from the RRC connected state <NUM> to the RRC inactive state <NUM> via RRC connection suspension <NUM> (also referred to as RRC suspend or RRC release with suspend).

In a fourth operation <NUM>, the UE <NUM> and the base station <NUM> may maintain the MRB <NUM> while the UE <NUM> is in the idle state or the inactive state. For example, the UE <NUM> and the base station <NUM> may maintain the MRB <NUM> by storing or continuing to store a context (e.g., an AS context or an MRB context) in memory rather than deleting the context upon exiting the connected state and entering the idle/inactive state. The context may indicate, for example, a bearer identifier that identifies the MRB, quality of service information associated with the MRB, information indicated in the MRB configuration, or a combination thereof. In some aspects, the base station <NUM> may maintain the MRB <NUM> by maintaining (e.g., storing in memory) the MRB configuration for the MRB <NUM>, which may indicate an MCCH, an MTCH, resources allocated to the MCCH or the MTCH, a G-RNTI associated with the MRB <NUM>, a retransmission configuration for the MRB <NUM>, an idle/inactive state configuration for the MRB <NUM>, the one or more limitations associated with maintaining the MRB <NUM> in the idle/inactive state, or a combination thereof, as described above. By maintaining the MRB <NUM>, the base station <NUM> may be capable of transmitting multicast/broadcast communications to the UE <NUM> while the UE <NUM> is in the idle state or the inactive state, which conserves UE resources (such as memory resources, processing resources, or battery power, among other examples) while enabling reliable multicast/broadcast communications. However, to conserve UE resources, the MRB <NUM> may be maintained subject to one or more limitations.

As described above, the one or more limitations apply to the MRB <NUM> while the UE <NUM> is in the idle state or the inactive state, and do not apply to the MRB <NUM> while the UE <NUM> is in the connected state. The one or more limitations may relate to, for example, permitted signaling in the idle/inactive state (such as signaling of an RLC status report or a response to a polling request, among other examples) or the use of one or more timers by the UE <NUM> in the idle/inactive state, among other examples. In some aspects, a limitation may disable, for the idle/inactive state, signaling that is used in the connected state. In such examples, the UE <NUM> may apply the limitation while the UE <NUM> is in the idle/inactive state by refraining from transmitting one or more signals or messages that are prohibited by the limitation. In the claimed invention, a limitation disables a timer, that is used in the connected state, for the idle/inactive state. In such a case, the UE <NUM> applies the limitation while the UE <NUM> is in the idle/inactive state by refraining from using a timer that is prohibited by the limitation.

For example, a limitation may prohibit the UE <NUM> from transmitting an RLC status report while the UE <NUM> is in the idle state or the inactive state. An RLC status report may be used to indicate an ACK or a NACK to a communication received via the MRB <NUM>. By disabling ACK/NACK reporting for the UE <NUM>, the UE <NUM> may conserve UE resources in the idle state or the inactive state. However, the UE <NUM> may still be capable of receiving retransmissions via the MRB <NUM> due to RLC status reports transmitted by other UEs <NUM>. In some aspects, the UE <NUM> may monitor for retransmissions on the MRB <NUM> while in the idle/inactive state based at least in part on a retransmission configuration, as described above. Additionally or alternatively, the UE <NUM> may monitor for multicast/broadcast control information (such as on the MCCH) while in the idle/inactive state (such as on preconfigured resources) to identify resources via which the retransmissions are to be transmitted.

The base station <NUM> may use RLC status reports to determine multicast/broadcast data transmissions to be retransmitted. When RLC status reports are disabled for UEs <NUM> in the idle/inactive state, the base station <NUM> bases retransmission decisions for a multicast/broadcast subscription on a subset of UEs <NUM> that are subscribed to receive the multicast/broadcast subscription (for example, only the UEs <NUM> that are in a connected state, and not the UEs <NUM> that are in the idle state or the inactive state). Thus, in some aspects, the base station <NUM> may use a different parameter (for example, a different threshold) to determine whether to retransmit an RLC packet (a multicast/broadcast communication) when an MRB <NUM> is permitted to be maintained in the idle/inactive state, as compared to when the MRB <NUM> is not permitted to be maintained in the idle/inactive state. Additionally or alternatively, the base station <NUM> may modify a retransmission factor (e.g., by increasing a retransmission factor, by increasing a quantity of retransmissions, by decreasing a retransmission factor, or by decreasing a quantity of retransmissions, among other examples) when an MRB <NUM> is permitted to be maintained in the idle/inactive state, as compared to when the MRB <NUM> is not permitted to be maintained in the idle/inactive state. In some aspects, the base station <NUM> may determine the parameter or the retransmission factor based at least in part on a quantity of UEs <NUM> in an idle mode, a quantity of UEs <NUM> in an inactive mode, one or more measurements received from UEs <NUM> in a connected mode, one or more measurements received from UEs <NUM> prior to those UEs <NUM> transitioning to the idle mode or the inactive mode (for example, a last measurement before transitioning), or a combination thereof.

As another example, a limitation may cause the UE <NUM> to ignore a polling request, for triggering transmission of an RLC status report, while the UE <NUM> is in the idle state or the inactive state. The base station <NUM> may transmit the polling request to trigger UEs <NUM>, that receive the polling request, to transmit an RLC status report. A polling request may include, for example, a polling bit transmitted in a downlink acknowledged mode data (AMD) PDU. In some aspects, if the UE <NUM> is prohibited from reporting an RLC status report in the idle/inactive state, and the UE <NUM> receives a polling request (such as a polling bit) that would trigger transmission of an RLC status report if the UE <NUM> were in the connected state, then the UE <NUM> may ignore the polling request if the UE <NUM> is in the idle/inactive state. By ignoring the polling request, the UE <NUM> refrains from transmitting an RLC status report in response to the polling request.

As another example, a limitation may cause the UE <NUM> to disable or refrain from using a status prohibit timer. A status prohibit timer may be associated with preventing transmission of multiple RLC status reports within a time period defined by the status prohibit timer. For example, while in the connected state, the UE <NUM> may transmit an RLC status report (such as in response to a first polling request), and may then start the status prohibit timer. If the UE <NUM> receives a second polling request before the status prohibit timer expires, then the UE <NUM> may refrain from transmitting an RLC status report in response to the second polling request. However, in the idle/inactive state, RLC status reporting may be disabled. As a result, the UE <NUM> can conserve UE resources by disabling the status prohibit timer because the UE <NUM> will not transmit any RLC status reports while in the idle/inactive mode.

As another example, a limitation may cause the UE <NUM> to disable or refrain from using a reassembly timer. The reassembly timer may be associated with discarding an incomplete RLC packet responsive to all segments of the RLC packet not being received within a time period defined by the reassembly timer. For example, while in the connected state, the UE <NUM> may receive a segment of an RLC packet, and may then start a reassembly timer associated with the RLC packet. If the UE <NUM> does not receive all segments of the RLC packet before the reassembly timer expires, then the UE <NUM> may discard the RLC packet and may transmit a NACK for the RLC packet. However, in the idle/inactive state, RLC status reporting (including ACK/NACK reporting) may be disabled. As a result, the UE <NUM> can conserve UE resources by disabling the status reassembly timer because the UE <NUM> will not transmit a NACK due to discarding the RLC packet.

In some aspects, the UE <NUM> may exit the idle/inactive state and enter the connected state. In such examples, the UE <NUM> may use the maintained MRB <NUM> to communicate in the connected state. However, the UE <NUM> may not be subject to the one or more limitations while in the connected state.

By maintaining the MRB <NUM> in the idle/inactive state, the UE <NUM> can receive multicast/broadcast traffic while in the idle/inactive state, thereby reducing latency, improving reliability, and reducing signaling overhead (such as signaling overhead used to establish the MRB <NUM>). Furthermore, by maintaining the MRB <NUM> in the idle/inactive state subject to one or more limitations described herein, the UE <NUM> can conserve resources (such as memory resources, processing resources, or battery power, among other examples) in the idle/inactive state. Furthermore, the UE <NUM> can use the maintained MRB <NUM> when transitioning from the idle/inactive state to the connected state, which reduces latency and conserves signaling overhead associated with establishing the MRB <NUM>.

<FIG> is a flowchart illustrating a process <NUM> performed, by a UE in accordance with the claimed invention. The claimed process concerns a UE (for example, UE <NUM>) performing operations relating to maintaining an MRB in an idle state or an inactive state.

As shown in <FIG> process <NUM> includes receiving a configuration for an MRB in an RLC acknowledged mode (block <NUM>). For example, the UE (for example, using receive processor <NUM>, controller/processor <NUM>, or memory <NUM>, among other examples) may receive a configuration for an MRB in an RLC acknowledged mode, as described above.

As further shown in <FIG>, process <NUM> includes entering an idle state or an inactive state after the MRB has been configured (block <NUM>). For example, the UE (for example, using receive processor <NUM>, transmit processor <NUM>, controller/processor <NUM>, or memory <NUM>, among other examples) may enter an idle state or an inactive state after the MRB has been configured, as described above.

As further shown in <FIG>, process <NUM> includes maintaining the MRB while the UE is in the idle state or the inactive state, subject to one or more limitations associated with maintaining the MRB in the idle state or the inactive state (block <NUM>). For example, the UE (for example, using receive processor <NUM>, transmit processor <NUM>, controller/processor <NUM>, or memory <NUM>, among other examples) may maintain the MRB while the UE is in the idle state or the inactive state subject to one or more limitations associated with maintaining the MRB in the idle state or the inactive state, as described above.

The process <NUM> may include additional aspects, such as any single aspect or any combination of aspects described below or in connection with one or more other processes described elsewhere herein.

In a first aspect, the one or more limitations apply to the MRB while the UE is in the idle state or the inactive state and do not apply to the MRB while the UE is in a connected state.

In a second aspect, alone or in combination with the first aspect, process <NUM> includes exiting the idle state or the inactive state to enter a connected state, and communicating using the MRB while in the connected state using the configuration.

In a third aspect, alone or in combination with one or more of the first and second aspects, process <NUM> includes receiving one or more retransmissions via the MRB while in the idle state or the inactive state.

In a fourth aspect, alone or in combination with one or more of the first through third aspects, the one or more limitations prohibit the UE from transmitting an RLC status report while the UE is in the idle state or the inactive state.

In a fifth aspect, alone or in combination with one or more of the first through fourth aspects, the one or more limitations cause the UE to ignore a polling request, for triggering transmission of an RLC status report, while the UE is in the idle state or the inactive state.

In a sixth aspect, alone or in combination with one or more of the first through fifth aspects, process <NUM> includes receiving a polling request, for triggering transmission of an RLC status report, while the UE is in the idle state or the inactive state; and refraining from transmitting the RLC status report in response to the polling request based at least in part on the UE being in the idle state or the inactive state and based at least in part on the one or more limitations.

In the claimed invention, alone or in combination with one or more of the first through sixth aspects, the one or more limitations cause the UE to refrain from using one or more timers while the UE is in the idle state or the inactive state.

In an eighth aspect, alone or in combination with one or more of the first through seventh aspects, the one or more timers include a status prohibit timer associated with preventing transmission of multiple RLC status reports within a time period defined by the status prohibit timer.

In a ninth aspect, alone or in combination with one or more of the first through eighth aspects, the one or more timers include a reassembly timer associated with discarding an incomplete RLC packet responsive to all segments of the RLC packet not being received within a time period defined by the reassembly timer.

In a tenth aspect, alone or in combination with one or more of the first through ninth aspects, maintaining the MRB includes storing a context associated with the MRB in memory of the UE rather than deleting the context from memory upon entering the idle state or the inactive state.

Additionally or alternatively, two or more of the blocks of process <NUM> may be performed in parallel.

<FIG> is a block diagram of an example apparatus <NUM> for wireless communication in accordance with various aspects of the present disclosure. The apparatus <NUM> may be a UE, or a UE may include the apparatus <NUM>. In some aspects, the apparatus <NUM> includes a reception component <NUM>, a communication manager <NUM>, and a transmission component <NUM>, which may be in communication with one another (for example, via one or more buses). As shown, the apparatus <NUM> may communicate with another apparatus <NUM> (such as a UE, a base station, or another wireless communication device) using the reception component <NUM> and the transmission component <NUM>.

In some aspects, the apparatus <NUM> may be configured to perform one or more operations described herein in connection with <FIG>. Additionally or alternatively, the apparatus <NUM> may be configured to perform one or more processes described herein, such as process <NUM> of <FIG>, process <NUM> of <FIG>, or a combination thereof. In some aspects, the apparatus <NUM> may include one or more components of the UE described above in connection with <FIG>.

The reception component <NUM> may provide received communications to one or more other components of the apparatus <NUM>, such as the communication manager <NUM>. In some aspects, the reception component <NUM> may perform signal processing on the received communications (such as filtering, amplification, demodulation, analog-to-digital conversion, demultiplexing, deinterleaving, de-mapping, equalization, interference cancellation, or decoding, among other examples), and may provide the processed signals to the one or more other components.

In some aspects, the communication manager <NUM> may generate communications and may transmit the generated communications to the transmission component <NUM> for transmission to the apparatus <NUM>.

The communication manager <NUM> may receive or may cause the reception component <NUM> to receive a configuration for an MRB in an RLC acknowledged mode. The communication manager <NUM> may enter an idle state or an inactive state after the MRB has been configured. The communication manager <NUM> may maintain the MRB while the apparatus <NUM> is in the idle state or the inactive state subject to one or more limitations associated with maintaining the MRB in the idle state or the inactive state. The communication manager <NUM> may exit the idle state or the inactive state to enter a connected state. The communication manager <NUM> may communicate using the MRB while in the connected state using the configuration. The communication manager <NUM> may receive or may cause the reception component <NUM> to receive one or more retransmissions via the MRB while in the idle state or the inactive state. The communication manager <NUM> may receive or may cause the reception component <NUM> to receive a polling request, for triggering transmission of an RLC status report, while the apparatus <NUM> is in the idle state or the inactive state. The communication manager <NUM> refrain from transmitting or may cause the transmission component <NUM> to refrain from transmitting the RLC status report in response to the polling request based at least in part on the apparatus <NUM> being in the idle state or the inactive state and based at least in part on the one or more limitations. In some aspects, the communication manager <NUM> may include a controller/processor, a memory, or a combination thereof, of the UE described above in connection with <FIG>.

In some aspects, the communication manager <NUM> may include a set of components, such as a state switching component <NUM>, an MRB maintenance component <NUM>, or a combination thereof. Alternatively, the set of components may be separate and distinct from the communication manager <NUM>. In some aspects, one or more components of the set of components may include or may be implemented within a controller/processor, a memory, or a combination thereof, of the UE described above in connection with <FIG>. Additionally or alternatively, one or more components of the set of components may be implemented at least in part as software stored in a memory. For example, a component (or a portion of a component) may be implemented as instructions or code stored in a non-transitory computer-readable medium and executable by a controller or a processor to perform the functions or operations of the component.

The reception component <NUM> may receive a configuration for an MRB in an RLC acknowledged mode. The state switching component <NUM> may cause the apparatus <NUM> to enter an idle state or an inactive state after the MRB has been configured. The MRB maintenance component <NUM> may maintain the MRB while the apparatus <NUM> is in the idle state or the inactive state subject to one or more limitations associated with maintaining the MRB in the idle state or the inactive state. The state switching component <NUM> may cause the apparatus <NUM> to exit the idle state or the inactive state to enter a connected state. The reception component <NUM> and/or the transmission component <NUM> may communicate using the MRB while in the connected state using the configuration. The reception component <NUM> may receive one or more retransmissions via the MRB while in the idle state or the inactive state. The reception component <NUM> may receive a polling request, for triggering transmission of an RLC status report, while the apparatus <NUM> is in the idle state or the inactive state. The transmission component <NUM> to refrain from transmitting the RLC status report in response to the polling request based at least in part on the apparatus <NUM> being in the idle state or the inactive state and based at least in part on the one or more limitations.

<FIG> is a flowchart illustrating an example process <NUM> performed, for example, by a UE in accordance with various aspects of the present disclosure. Example process <NUM> is an example where the UE (for example, UE <NUM>) performs operations associated with maintaining a multicast/broadcast radio bearer in an idle state or an inactive state.

As shown in <FIG>, in some aspects, process <NUM> may include receiving a configuration for an MRB in an RLC acknowledged mode (block <NUM>). For example, the UE (such as by using reception component <NUM>, depicted in <FIG>) may receive a configuration for an MRB in an RLC acknowledged mode, as described above.

As further shown in <FIG>, in some aspects, process <NUM> may include storing a context associated with the MRB in a memory of the UE based at least in part on the configuration (block <NUM>). For example, the UE (such as by using context storage component <NUM>, depicted in <FIG>) may store a context associated with the MRB in a memory of the UE based at least in part on the configuration, as described above.

As further shown in <FIG>, in some aspects, process <NUM> may include entering an idle state or an inactive state, after the MRB has been configured and the context has been stored, without removing the context from the memory (block <NUM>). For example, the UE (such as by using state switching component <NUM>, depicted in Figure XXXX) may enter an idle state or an inactive state, after the MRB has been configured and the context has been stored, without removing the context from the memory, as described above.

As further shown in <FIG>, in some aspects, process <NUM> may include maintaining the MRB while the UE is in the idle state or the inactive state subject to one or more limitations associated with maintaining the MRB in the idle state or the inactive state based at least in part on entering the idle state or the inactive state without removing the context from the memory (block <NUM>). For example, the UE (such as by using MRB maintenance component <NUM>, depicted in <FIG>) may maintain the MRB while the UE is in the idle state or the inactive state subject to one or more limitations associated with maintaining the MRB in the idle state or the inactive state based at least in part on entering the idle state or the inactive state without removing the context from the memory, as described above.

Process <NUM> may include additional aspects, such as any single aspect or any combination of aspects described below or in connection with one or more other processes described elsewhere herein.

In a first additional aspect, the one or more limitations apply to the MRB while the UE is in the idle state or the inactive state and do not apply to the MRB while the UE is in a connected state.

In a second additional aspect, alone or in combination with the first aspect, the one or more limitations prohibit the UE from transmitting an RLC status report while the UE is in the idle state or the inactive state.

In a third additional aspect, alone or in combination with one or more of the first and second aspects, the one or more limitations cause the UE to ignore a polling request, for triggering transmission of an RLC status report, while the UE is in the idle state or the inactive state.

In a fourth additional aspect, alone or in combination with one or more of the first through third aspects, the one or more limitations cause the UE to refrain from using one or more timers while the UE is in the idle state or the inactive state.

The communication manager <NUM> may receive or may cause the reception component <NUM> to receive a configuration for an MRB in an RLC acknowledged mode. The communication manager <NUM> may store a context associated with the MRB in a memory of the UE based at least in part on the configuration. The communication manager <NUM> may cause the apparatus <NUM> to enter an idle state or an inactive state, after the MRB has been configured and the context has been stored, without removing the context from the memory. The communication manager <NUM> may maintain the MRB while the UE is in the idle state or the inactive state subject to one or more limitations associated with maintaining the MRB in the idle state or the inactive state based at least in part on entering the idle state or the inactive state without removing the context from the memory. In some aspects, the communication manager <NUM> may perform one or more operations described elsewhere herein as being performed by one or more components of the communication manager <NUM>.

The communication manager <NUM> may include a controller/processor, a memory, or a combination thereof, of the UE described above in connection with <FIG>. In some aspects, the communication manager <NUM> includes a set of components, such as a context storage component <NUM>, a state switching component <NUM>, an MRB maintenance component <NUM>, or a combination thereof. Alternatively, the set of components may be separate and distinct from the communication manager <NUM>. In some aspects, one or more components of the set of components may include or may be implemented within a controller/processor, a memory, or a combination thereof, of the UE described above in connection with <FIG>. Additionally or alternatively, one or more components of the set of components may be implemented at least in part as software stored in a memory. For example, a component (or a portion of a component) may be implemented as instructions or code stored in a non-transitory computer-readable medium and executable by a controller or a processor to perform the functions or operations of the component.

The reception component <NUM> may receive a configuration for an MRB in an RLC acknowledged mode. The context storage component <NUM> may store a context associated with the MRB in a memory of the UE based at least in part on the configuration. The state switching component <NUM>, the context storage component <NUM>, or a combination thereof may enter or may cause the apparatus <NUM> to enter an idle state or an inactive state, after the MRB has been configured and the context has been stored, without removing the context from the memory. The MRB maintenance component <NUM>, the context storage component <NUM>, or a combination thereof may maintain the MRB while the UE is in the idle state or the inactive state subject to one or more limitations associated with maintaining the MRB in the idle state or the inactive state based at least in part on entering the idle state or the inactive state without removing the context from the memory.

As used herein, satisfying a threshold may refer to a value being greater than the threshold, greater than or equal to the threshold, less than the threshold, less than or equal to the threshold, equal to the threshold, or not equal to the threshold, among other examples, or combinations thereof.

It will be apparent that systems or methods described herein may be implemented in different forms of hardware, firmware, or a combination of hardware and software. The actual specialized control hardware or software code used to implement these systems or methods is not limiting of the aspects. Thus, the operation and behavior of the systems or methods were described herein without reference to specific software code-it being understood that software and hardware can be designed to implement the systems or methods based, at least in part, on the description herein.

Even though particular combinations of features are recited in the claims or disclosed in the specification, these combinations are not intended to limit the disclosure of various aspects. In fact, many of these features may be combined in ways not specifically recited in the claims or disclosed in the specification. As an example, "at least one of a, b, or c" is intended to cover a, b, c, a-b, a-c, b-c, and a-b-c, as well as any combination with multiples of the same element (for example, a-a, a-a-a, a-a-b, a-a-c, a-b-b, a-c-c, b-b, b-b-b, b-b-c, c-c, and c-c-c or any other ordering of a, b, and c).

Claim 1:
A method of wireless communication performed by a user equipment, UE (<NUM>), comprising:
receiving (<NUM>, <NUM>) a configuration for a multicast/broadcast radio bearer, MRB in a radio link control, RLC, acknowledged mode;
entering (<NUM>, <NUM>) an idle state or an inactive state after the MRB has been configured; and
maintaining (<NUM>, <NUM>) the MRB while the UE is in the idle state or the inactive state, the method characterized in that:
the maintaining is subject to one or more limitations associated with maintaining the MRB in the idle state or the inactive state, wherein the one or more limitations cause the UE (<NUM>) to refrain from using one or more timers while the UE is in the idle state or the inactive state.