On-demand multicast control channel message

Abstract

Methods, systems, and devices are described for on-demand multicast control channel (MCCH) messages. A user equipment (UE) can receive, from a base station, system information indicating a MCCH message configuration. Based on receiving the MCCH message configuration, the UE can transmit a request for the MCCH message. For example, the UE can transmit the request for the MCCH message by a random access preamble or a radio resource control (RRC) message. After transmitting the request, the UE can receive the MCCH message according to the MCCH message configuration. That is, the base station can receive the request and transmit the MCCH message in response to the request. The MCCH message can indicate a multicast service radio bearer (MRB) configuration for receiving multicast traffic. Thus, the UE can receive multicast traffic from the base station according to the MRB configuration.

Description

[0001] Cross-references

[0002] This patent application claims priority to U.S. patent application No. 17 / 141,206, entitled “ON-DEMAND MULTICAST CONTROL CHANNEL MESSAGES,” filed by ZHU et al. on January 4, 2021, and U.S. provisional patent application No. 62 / 989,373, entitled “ON-DEMAND MULTICAST CONTROL CHANNEL MESSAGES,” filed by ZHU et al. on March 13, 2020, each of which is assigned to the assignee of this application. Technical Field

[0003] The following relates generally to wireless communications, and more particularly to on-demand multicast control channel messages. Background Art

[0004] Wireless communication systems are widely deployed to provide various types of communication content, such as voice, video, packet data, messaging, broadcast, and the like. These systems may be able to support communication with multiple users by sharing available system resources (e.g., time, frequency, and power). Examples of such multiple access systems include fourth generation (4G) systems (such as long term evolution (LTE) systems, advanced LTE (LTE-A) systems, or LTE-A Pro systems), and fifth generation (5G) systems, which may be referred to as new radio (NR) systems. These systems may employ various technologies, such as code division multiple access (CDMA), time division multiple access (TDMA), frequency division multiple access (FDMA), orthogonal frequency division multiple access (OFDMA), or discrete Fourier transform spread orthogonal frequency division multiplexing (DFT-S-OFDM). A wireless multiple access communication system may include one or more base stations or one or more network access nodes, each base station or network access node simultaneously supporting communication with multiple communication devices, which may be further referred to as user equipment (UE).

[0005] The UE may receive broadcast or multicast traffic from a base station via a Multicast Service Radio Bearer (MRB).The UE may determine a Multicast Control Channel (MCCH) configuration for receiving multicast traffic from the base station based on receiving an MRB configuration message indicating the MRB configuration.

[0006] Overview

[0007] The described techniques relate to improved methods, systems, devices, or apparatuses that support on-demand multicast control channel (MCCH) messages. Generally, a user equipment (UE) can receive, from a base station, a system information block (SIB) indicating a configuration of a MCCH message. Based on receiving the indication of the configuration of the MCCH message, the UE can transmit, to the base station, a request for the MCCH message. In one example, the UE can transmit the request for the MCCH message to the base station over a random access preamble. Here, the UE can receive a random access response (RAR) message from the base station, and then the UE can monitor a physical downlink control channel (PDCCH) for the MCCH message. In another example, the UE can transmit the request for the MCCH message to the base station over a radio resource control (RRC) message. Here, the UE can subsequently monitor the PDCCH for the MCCH message. Additionally or alternatively, the UE can receive the MCCH message over a RRC message received from the base station. In either example, the MCCH message can indicate a configuration of a multicast service radio bearer (MRB) associated with multicast traffic from the base station. The UE can then receive the multicast traffic from the base station in accordance with the MRB configuration.

[0008] A method of wireless communication is described at a UE. The method can include receiving, from a base station, system information indicating a configuration of a MCCH message, transmitting, to the base station, a request for the MCCH message, receiving, in accordance with the configuration of the MCCH message and in response to the transmission of the request, the MCCH message indicating a configuration of a MRB, and receiving multicast traffic from the base station in accordance with the configuration of the MRB.

[0009] An apparatus for wireless communication at a UE is described. The apparatus can include a processor, memory coupled with the processor, and instructions stored in the memory. The instructions can be executable by the processor to cause the apparatus to receive, from a base station, system information indicating a configuration of a MCCH message, transmit, to the base station, a request for the MCCH message, receive, in accordance with the configuration of the MCCH message and in response to the transmission of the request, the MCCH message indicating a configuration of a MRB, and receive multicast traffic from the base station in accordance with the configuration of the MRB.

[0010] Another apparatus for wireless communication at a UE is described. The apparatus can include means for receiving, from a base station, system information indicating a configuration of a MCCH message, transmitting, to the base station, a request for the MCCH message, receiving, in accordance with the configuration of the MCCH message and in response to the transmission of the request, the MCCH message indicating a configuration of a MRB, and receiving multicast traffic from the base station in accordance with the configuration of the MRB.

[0011] A non-transitory computer-readable medium storing code for wireless communications at a UE is described. The code can include instructions executable by a processor to receive, from a base station, system information indicating a MCCH message configuration, transmit, to the base station, a request for a MCCH message, receive, from the base station, the MCCH message indicating a MRB configuration in accordance with the MCCH message configuration and in response to the transmission of the request, and receive, from the base station, multicast traffic in accordance with the MRB configuration.

[0012] In some examples of the method, apparatuses, and non-transitory computer- readable medium described herein, transmitting the request for the MCCH message can include further operations, features, means, or instructions for transmitting the request to the base station over a random access preamble within a random access occasion indicated by the MCCH message request configuration within the system information.

[0013] Some examples of the method, apparatuses, and non-transitory computer- readable medium described herein can further include operations, features, means, or instructions for receiving a RAR message from the base station, where receiving the MCCH message can be based on receiving the RAR message.

[0014] Some examples of the method, apparatuses, and non-transitory computer- readable medium described herein can further include operations, features, means, or instructions for determining to transmit the request over the random access preamble based on the system information including the MCCH message request configuration.

[0015] In some examples of the method, apparatuses, and non-transitory computer- readable medium described herein, transmitting the request for the MCCH message can include further operations, features, means, or instructions for transmitting the request over a RRC request message.

[0016] In some examples of the method, apparatuses, and non-transitory computer- readable medium described herein, the RRC request message can be included within a payload of an RRC system information request, an RRC MCCH request, or a first random access message of a two-step random access procedure.

[0017] In some examples of the method, apparatuses, and non-transitory computer- readable medium described herein, receiving the MCCH message can include further operations, features, means, or instructions for receiving the MCCH message over a RRC configuration message in response to the RRC request message.

[0018] Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein can further include operations, features, means for, or instructions for determining to transmit the request by the RRC request message based on an absence of an MCCH message request configuration within the system information.

[0019] In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, the system information indicates an MCCH message request configuration; and transmitting the request can further include operations, features, means for, or instructions for transmitting the request in accordance with the MCCH message request configuration.

[0020] In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, the MCCH message request configuration includes at least one of an indication of a time period for transmitting the request or a resource for transmitting the request.

[0021] Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein can further include operations, features, means for, or instructions for monitoring a PDCCH for the MCCH message in accordance with the MCCH message configuration, where receiving the MCCH message can be based on monitoring the PDCCH.

[0022] In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, monitoring the PDCCH can further include operations, features, means for, or instructions for monitoring a control resource set of the PDCCH indicated by the system information.

[0023] In some examples of the method, apparatuses, and non-transitory computer- readable medium described herein, the control resource set can be associated with a monitoring time window, a monitoring period, a monitoring offset, or a combination thereof.

[0024] In some examples of the method, apparatuses, and non-transitory computer- readable medium described herein, the MCCH message can be associated with a set of delay-sensitive MRB configurations that includes the MRB configuration.

[0025] In some examples of the method, apparatuses, and non-transitory computer- readable medium described herein, the MCCH message can be associated with a set of MRB configurations that can be delay-insensitive, and the set of MRB configurations includes the MRB configuration.

[0026] Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein can further include operations, features, means, or instructions for transmitting the request for the MCCH message can be based on the system information indicating that the MCCH message will be receivable on demand.

[0027] Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein can further include operations, features, means, or instructions for determining a service group associated with the multicast traffic, where receiving the MCCH message can be based on the determined service group.

[0028] In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, determining the service group can further include operations, features, means, or instructions for determining a service group identifier associated with the service group based on an MRB context or a multicast broadcast service identifier.

[0029] In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, the MCCH message includes both an on-demand MCCH message and a periodic MCCH message.

[0030] Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein can further include operations, features, means, or instructions for performing a cell reselection procedure from a first base station to a second base station, where the base station can be the first base station; determining, based on a same zone identifier with a first MCCH message and a second MCCH message associated with the second base station, that the second base station transmits the multicast traffic according to the MRB configuration, where the MCCH message can be the first MCCH message; and determining to refrain from monitoring system information from the second base station based on determining that the second base station transmits the multicast traffic according to the MRB configuration.

[0031] In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, the system information includes an indication of the zone identifier.

[0032] Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein can further include operations, features, means, or instructions for determining to perform a cell reselection procedure from a first base station, where the base station can be a second base station; receiving an initial multicast control message from the first base station based on determining to perform the cell reselection procedure; determining, based on the initial multicast control message, that the second base station transmits the multicast traffic; and performing the cell reselection procedure from the first base station to the second base station based on determining that the second base station transmits the multicast traffic, where receiving the system information can be based on performing the cell reselection procedure.

[0033] Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein can further include operations, features, means for performing, or instructions for causing an apparatus to receive that the system information can be based on the UE performing a cell reselection procedure, the UE performing a cell selection procedure, the UE performing a handover procedure, a change associated with the MCCH message, or a combination thereof.

[0034] In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, the MCCH message configuration includes at least one of an indication of a search space associated with the MCCH message or a time period for receiving the MCCH message.

[0035] In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, the MRB configuration can be a multicast / broadcast service radio bearer configuration and the multicast traffic can be multicast / broadcast traffic.

[0036] In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, the MCCH message configuration includes an indication of a repetition period of the MCCH message, an identifier associated with the multicast traffic, one or more time slots associated with the MCCH message, a modification period associated with the MCCH message, a new service start, or a combination thereof.

[0037] A method of wireless communication is described at a base station. The method can include transmitting, to a UE, system information indicating a MCCH message configuration, receiving, from the UE, a request for a MCCH message, transmitting, in accordance with the MCCH message configuration and in response to receiving the request, a MCCH message indicating an MRB configuration, and transmitting, to the UE, multicast traffic in accordance with the MRB configuration.

[0038] An apparatus for wireless communication at a base station is described. The apparatus can include a processor, memory coupled with the processor, and instructions stored in the memory. The instructions can be executable by the processor to cause the apparatus to transmit, to a UE, system information indicating a MCCH message configuration, receive, from the UE, a request for a MCCH message, transmit, in accordance with the MCCH message configuration and in response to receiving the request, a MCCH message indicating an MRB configuration, and transmit, to the UE, multicast traffic in accordance with the MRB configuration.

[0039] Another apparatus for wireless communication at a base station is described. The apparatus can include means for transmitting, to a UE, system information indicating a MCCH message configuration, receiving, from the UE, a request for a MCCH message, transmitting, in accordance with the MCCH message configuration and in response to the reception of the request, a MCCH message indicating an MRB configuration, and transmitting, to the UE, multicast traffic in accordance with the MRB configuration.

[0040] A non-transitory computer-readable medium storing code for wireless communication at a base station is described. The code can include instructions executable by a processor to transmit, to a UE, system information indicating a MCCH message configuration, receive, from the UE, a request for a MCCH message, transmit, in accordance with the MCCH message configuration and in response to the reception of the request, a MCCH message indicating an MRB configuration, and transmit, to the UE, multicast traffic in accordance with the MRB configuration.

[0041] In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, receiving the request for the MCCH message can include further operations, features, means, or instructions for receiving the request from the UE over a random access preamble within a random access occasion indicated by the MCCH message request configuration within the system information.

[0042] Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein can further include operations, features, means, or instructions for transmitting a RAR message to the UE, where transmitting the MCCH message can be based on receiving the RAR information.

[0043] In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, the request can be received over the random access preamble based on the system information including the MCCH message request configuration.

[0044] In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, receiving the request for the MCCH message can include further operations, features, means, or instructions for receiving the request over a RRC request message.

[0045] In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, the RRC request message can be included within a RRC connection request or within a payload of a first random access message in a two-step random access procedure.

[0046] In some examples of the method, apparatus, and non-transitory computer-readable medium described herein, transmitting the MCCH message can further include operations, features, means, or instructions for transmitting the MCCH message through an RRC configuration message in response to the RRC request message.

[0047] In some examples of the method, apparatus, and non-transitory computer-readable medium described herein, the request can be received through the RRC request message based on an absence of a MCCH message request configuration within the system information.

[0048] In some examples of the method, apparatus, and non-transitory computer-readable medium described herein, the system information indicates a MCCH message request configuration; and receiving the request can further include operations, features, means, or instructions for receiving the request in accordance with the MCCH message request configuration.

[0049] In some examples of the method, apparatus, and non-transitory computer-readable medium described herein, the MCCH message request configuration includes at least one of an indication of a time period for transmitting the request by the UE or a resource for transmitting the request by the UE.

[0050] In some examples of the method, apparatus, and non-transitory computer-readable medium described herein, transmitting the MCCH message can further include operations, features, means, or instructions for transmitting the MCCH message through a PDCCH in accordance with the MCCH message configuration.

[0051] In some examples of the method, apparatus, and non-transitory computer-readable medium described herein, transmitting the MCCH message through the PDCCH can further include operations, features, means, or instructions for transmitting the MCCH message within a control resource set indicated by the system information.

[0052] In some examples of the method, apparatus, and non-transitory computer-readable medium described herein, the control resource set can be associated with a monitoring time window, a monitoring period, a monitoring offset, or a combination thereof.

[0053] In some examples of the method, apparatus, and non-transitory computer-readable medium described herein, the MCCH message can be a first MCCH message, and the first MCCH message can be associated with a first MRB configuration set including at least the MRB configuration.

[0054] Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein can further include operations, features, means for, or instructions for transmitting a second MCCH message associated with a second set of MRB configurations, where one of the first set of MRB configurations or the second set of MRB configurations is delay sensitive.

[0055] Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein can further include operations, features, means for, or instructions for receiving a request for the MCCH message can be based on the system information indicating that the MCCH message can be transmitted on demand.

[0056] Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein can further include operations, features, means for, or instructions for determining a service group associated with the multicast traffic, where transmitting the MCCH message can be based on the determined service group.

[0057] In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, determining the service group can further include operations, features, means for, or instructions for determining a service group identifier associated with the service group based on an MRB context or a multicast broadcast service identifier.

[0058] In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, the MCCH message includes both an on-demand MCCH message and a periodic MCCH message.

[0059] Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein can further include operations, features, means for, or instructions for transmitting the system information can be based on: the UE performing a cell reselection procedure, the UE performing a cell selection procedure, the UE performing a handover procedure, a change associated with the MCCH message, or a combination thereof.

[0060] In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, the MCCH message configuration includes at least one of an indication of a search space associated with the MCCH message or a period for receiving the MCCH message.

[0061] In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, the MRB configuration can be a multicast / broadcast service radio bearer configuration and the multicast traffic can be multicast / broadcast traffic.

[0062] In some examples of the method, apparatuses, and non-transitory computer- readable medium described herein, the MCCH message configuration includes an indication of a repetition period of the MCCH message, an identifier associated with the multicast traffic, one or more slots associated with the MCCH message, a modification period associated with the MCCH message, a start of a new service, or a combination thereof. BRIEF DESCRIPTION OF DRAWINGS

[0064] Figure 1 An example of a process flow that supports on-demand multicast control channel (MCCH) messages is illustrated in accordance with aspects of the present disclosure.

[0065] Figure 2 An example of a process flow that supports on-demand MCCH messages is illustrated in accordance with aspects of the present disclosure.

[0066] Figure 3 An example of a process flow that supports on-demand MCCH messages is illustrated in accordance with aspects of the present disclosure.

[0067] Figure 4 An example of a process flow that supports on-demand MCCH messages is illustrated in accordance with aspects of the present disclosure.

[0068] Figure 5 An example of a process flow that supports on-demand MCCH messages is illustrated in accordance with aspects of the present disclosure.

[0069] Figure 6 And Figure 7 A block diagram of a device that supports on-demand MCCH messages is shown in accordance with aspects of the present disclosure.

[0070] Figure 8 A block diagram of a UE coding manager that supports on-demand MCCH messages is shown in accordance with aspects of the present disclosure.

[0071] Figure 9 A diagram of a system including a device that supports on-demand MCCH messages is shown in accordance with aspects of the present disclosure.

[0072] Figure 10 And Figure 11 A block diagram of a device that supports on-demand MCCH messages is shown in accordance with aspects of the present disclosure.

[0073] Figure 12 A block diagram of a device that supports on-demand MCCH messages is shown in accordance with aspects of the present disclosure.

[0074] Figure 13 A diagram of a system including a device that supports on-demand MCCH messages is shown in accordance with aspects of the present disclosure.

[0075] Figures 14 to 19 Shown is a flow chart illustrating a method of supporting on-demand MCCH messages according to aspects of the present disclosure.

[0076] Detailed description

[0077] In some wireless communication systems, a base station may transmit multicast traffic to one or more user equipments (UEs) via a multicast service radio bearer (MRB). The base station may indicate the configuration for the MRB within a multicast control channel (MCCH) message. Furthermore, the base station may indicate the MCCH message configuration via system information transmitted to the one or more UEs. In some cases, the base station may transmit an MCCH message indicating the MRB configuration according to a periodicity defined by the system information. Here, the one or more UEs may monitor a physical downlink control channel (PDCCH) to search for MCCH messages transmitted according to the periodicity. In some cases, the UE may begin monitoring the PDCCH to search for the MCCH message shortly after the base station transmits the MCCH message. Here, the UE may monitor the PDCCH for a relatively long period of time (for example, compared to a UE that begins monitoring the PDCCH to search for the MCCH message long after the base station transmits the MCCH message). Therefore, due to the periodic MCCH message transmission, there may be a delay associated with the UE receiving the MCCH message. The delay in receiving the MCCH message may additionally introduce a waiting time for the one or more UEs receiving the multicast traffic.

[0078] In some cases, the base station can transmit the MCCH message on-demand (e.g., in addition to periodically transmitting the MCCH message, in place of periodically transmitting the MCCH message). Here, the UE can transmit a request for the MCCH message, and the base station can transmit the MCCH message to the UE in response to the request. As a result, the UE can not monitor the PDCCH for the MCCH message for an extended period of time (e.g., according to a periodicity of the MCCH message), and can instead receive the MCCH message on-demand. This can reduce latency associated with receiving the MCCH message and can increase a speed of communications associated with the UE and the base station. The UE can transmit the request after receiving system information indicating the MCCH configuration. In one example, the UE can transmit the request for the MCCH message to the base station through a random access preamble. Here, the UE can receive a random access response (RAR) message from the base station, and then the UE can monitor the PDCCH for the MCCH message. In another example, the UE can transmit the request for the MCCH to the base station through a radio resource control (RRC) message. Here, the UE can monitor the PDCCH for the MCCH message or can receive the MCCH message through an RRC message received from the base station. In either example, the MCCH message can indicate a configuration of an MRB associated with multicast traffic, and the UE can receive the multicast traffic from the base station according to the MRB configuration.

[0079] Aspects of the disclosure are initially described in the context of a wireless communications system. Aspects of the disclosure are subsequently described in the context of process flows. Aspects of the disclosure are further illustrated by and described in connection with apparatus diagrams, system diagrams, and flowcharts related to on-demand MCCH messages.

[0080] Figure 1 An example of a wireless communications system 100 that supports on-demand MCCH messages is illustrated in accordance with aspects of the present disclosure. The wireless communications system 100 can include one or more base stations 105, one or more UEs 115, and a core network 130. In some examples, the wireless communications system 100 can be a Long Term Evolution (LTE) network, an LTE- Advanced (LTE-A) network, an LTE-A Pro network, or a New Radio (NR) network. In some examples, the wireless communications system 100 can support enhanced broadband communications, ultra-reliable (e.g., mission critical) communications, low latency communications, communications with low-cost and low-complexity devices, or any combination thereof.

[0081] The base stations 105 can be dispersed throughout the geographic area 100 and can be

[0082] The UEs 115 can be dispersed throughout the coverage areas 110 of the wireless communications system 100, and each UE 115 can be stationary or mobile, or both at different times. The UEs 115 can be devices in different forms or have different capabilities. Some example UEs 115 are illustrated in FIG. 1. A UE 115, as used herein, can include a device that has a wireless Figure 1 Some of the example UEs 115 are illustrated in FIG. 1. The UEs 115 described herein can be able to communicate with various types of devices, such as other UEs 115, base stations 105, or network equipment (e.g., core network nodes, relay devices, integrated access and backhaul (IAB) nodes, or other network equipment), as shown in FIG. 1. Figure 1

[0083] The base stations 105 can communicate with the core network 130, or with one another, or both. For example, base stations 105 can interface with the core network 130 through one or more backhaul links 120 (e.g., via an SI, N2, N3, or other interface). The base stations 105 can communicate with one another over the backhaul links 120 (e.g., via an X2, Xn, or other interface) directly (e.g., directly between base stations 105), or indirectly (e.g., via the core network 130), or both. In some examples, the backhaul links 120 can be or include one or more wireless links.

[0084] One or more of the base stations 105 described herein can include or can be referred to by a base transceiver station, a radio base station, an access point, a radio transceiver, a NodeB, an eNodeB (eNB), a next-generation NodeB or giga-NodeB (either of which can be referred to as a gNB), a Home NodeB, a Home eNodeB, or other suitable terminology.

[0085] ​A UE 115 can include or can be referred to as a mobile device, a wireless device, a remote device, a handheld device, or a subscriber device, or some other suitable terminology, where the “device” can also be referred to as a unit, a station, a terminal, or a client, among other examples. A UE 115 can also include or can be referred to as a personal electronic device such as a cellular phone, a personal digital assistant (PDA), a tablet computer, a laptop computer, or a personal computer. In some examples, a UE 115 can include or be referred to as a wireless local loop (WLL) station, an Internet of Things (IoT) device, an Internet of Everything (IoE) device, or a machine type communications (MTC) device, among other examples, which can be implemented in various objects such as appliances or vehicles, meters or instruments, among other examples.

[0086] The UEs 115 described herein can be able to communicate with various types of devices, such as other UEs 115 that can sometimes act as relays or Figure 1 as shown in FIG. 1.

[0087] The UEs 115 and the base stations 105 can wirelessly communicate with one another via one or more communication links 125 over one or more carriers. The

[0088] Signal waveforms transmitted over a carrier can be composed of multiple subcarriers (e.g., using multi-carrier modulation (MCM) techniques such as orthogonal frequency division multiplexing (OFDM) or discrete Fourier transform spread OFDM (DFT-S-OFDM)). In a system employing MCM techniques, a resource element can consist of one symbol period (e.g., the duration of one modulation symbol) and one subcarrier, where the symbol period and subcarrier spacing are inversely related. The number of bits carried by each resource element can depend on the modulation scheme (e.g., the order of the modulation scheme, the code rate of the modulation scheme, or both). Thus, the more resource elements that a UE 115 receives and the higher the order of the modulation scheme, the higher the data rates for the UE 115. A wireless communications resource can refer to a combination of a radio frequency spectrum resource, a time resource, and a spatial resource (e.g., spatial layers or beams), and the use of multiple spatial layers can further increase the data rate for communications with a UE 115.

[0089] Time intervals for a base station 105 or UE 115 can be expressed in multiples of a basic time unit, which may, for example, be a sampling period of Ts=1 / (Δfmax·N) seconds, where Δfmax can represent the maximum supported subcarrier spacing, and N can represent the maximum supported discrete Fourier transform (DFT) size. Time intervals of a base station 105 can also be expressed in multiples of a basic time unit s =1 / (Δf max ·N f ) seconds, where Δf max may represent the maximum supported subcarrier spacing, and N f may represent the maximum supported discrete Fourier transform (DFT) size. Time intervals of a base station 105 can also be expressed in multiples of a basic time unit

[0090] Each frame can include a plurality of consecutive numbered subframes or slots, and each subframe or slot can have the same duration. In some examples, a frame can be divided (e.g., in the time domain) into subframes, and each subframe can be further divided into a number of slots. Alternatively, each frame can include a variable number of slots, and the number of slots can depend on the subcarrier spacing. Each slot can include a number of symbol periods (e.g., depending on the length of the cyclic prefix prepended to each symbol period). In some wireless communications systems 100, a slot can be further divided into multiple mini-slots containing one or more symbols. Excluding the cyclic prefix, each symbol period can contain one or more (e.g., N f ) sampling periods. The duration of a symbol period can depend on the subcarrier spacing or the operating band.

[0091] A subframe, a slot, a mini-slot, or a symbol can be the smallest scheduling unit (e.g., in the time domain) of the wireless communications system 100 and can be referred to as a transmission time interval (TTI). In some examples, the TTI duration (e.g., the number of symbol periods in a TTI) can be variable. Additionally or alternatively, the smallest scheduling unit of the wireless communications system 100 can be dynamically selected (e.g., in bursts of shortened TTIs (sTTIs)).

[0092] Physical channels can be multiplexed on a carrier according to various techniques. A physical control channel and a physical data channel can be multiplexed on a downlink carrier, for example, using one or more of time division multiplexing (TDM) techniques, frequency division multiplexing (FDM) techniques, or hybrid TDM-FDM techniques. A control region (e.g., a control resource set (CORESET)) for a physical control channel can be defined in terms of number of symbol periods and can extend across the system bandwidth or a subset of the system bandwidth of the carrier. One or more control regions (e.g., CORESETs) can be configured for a set of UEs 115. For example, one or more of the UEs 115 can monitor or search control regions according to one or more search space sets, and each search space set can comprise one or more control channel candidates arranged in an aggregation level of one or more of a set of aggregation levels. An aggregation level for a control channel candidate can refer to a number of control channel resources (e.g., control channel elements (CCEs)) associated with encoded information for a control information format having a given payload size. Search space sets can include common search space sets configured for sending control information to multiple UEs 115 and UE-specific search space sets configured for sending control information to a specific UE 115.

[0093] Each base station 105 can provide communication coverage for one or more cells (e.g., macro cells, small cells, hot spots, or other types of cells, or any combination thereof) The term “cell” can refer to a logical communication entity used for communication with a base station 105 (e.g., on a carrier) and can be associated with a identifier, such as a physical cell identifier (PCID), a virtual cell identifier (VCID), or otherwise, used to distinguish neighboring cells. In some examples, the cell can also refer to a geographical area 110 or a subset of a geographical area 110 (e.g., a sector) over which a logical communication entity operates. The size of such a cell can depend on various factors such as capabilities of the base station 105, and can range from a small area (e.g., a structure, a subset of a structure) to a large area. For example, a cell can be or include a building, a subset of a building, or an outdoor space between or overlapping with geographical areas 110, among other examples.

[0094] In some examples, base stations 105 can be mobile and, therefore, provide communication coverage for mobile geographic coverage areas 110. In some examples, different geographic coverage areas 110 associated with different technologies can overlap, but the different geographic coverage areas 110 can be supported by the same base station 105. In other examples, overlapping geographic coverage areas 110 associated with different technologies can be supported by different base stations 105. The wireless communication system 100 can include, for example, a heterogeneous network in which different types of base stations 105 provide coverage for various geographic coverage areas 110 using the same or different radio access technologies.

[0095] The wireless communication system 100 can be configured to support ultra-reliable communication or low-latency communication or various combinations thereof. For example, the wireless communication system 100 can be configured to support ultra-reliable low-latency communication (URLLC) or mission-critical communication. The UE 115 can be designed to support ultra-reliable, low-latency or critical functions (e.g., mission-critical functions). Ultra-reliable communication can include private communication or group communication and can be supported by one or more mission-critical services such as mission-critical push-to-talk (MCPTT), mission-critical video (MCVideo), or mission-critical data (MCData). Support for mission-critical functions can include prioritization of services, and mission-critical services can be used for public safety or general commercial applications. The terms ultra-reliable, low-latency, mission-critical, and ultra-reliable low-latency can be used interchangeably herein.

[0096] In some examples, UE 115 may also be able to communicate directly with other UEs 115 over a device-to-device (D2D) communication link 135 (e.g., using a peer-to-peer (P2P) or D2D protocol). One or more UEs 115 utilizing D2D communication may be within the geographic coverage area 110 of base station 105. Other UEs 115 in such a group may be outside the geographic coverage area 110 of base station 105 or otherwise unable to receive transmissions from base station 105. In some examples, groups of UEs 115 communicating via D2D communication may utilize a one-to-many (1:M) system, in which each UE 115 transmits to every other UE 115 in the group. In some examples, base station 105 facilitates the scheduling of resources for D2D communication. In other cases, D2D communication is performed between UEs 115 without involving base station 105.

[0097] The core network 130 can provide user authentication, access authorization, tracking, Internet Protocol (IP) connectivity, and other access, routing, or mobility functions. The core network 130 can be an evolved packet core (EPC) or 5G core (5GC), which can include at least one control plane entity that manages access and mobility (e.g., a mobility management entity (MME), an access and mobility management function (AMF)) and at least one user plane entity that routes packets or interconnects to external networks (e.g., a serving gateway (S-GW), a Packet Data Network (PDN) gateway (P-GW), or a user plane function (UPF)). The control plane entity can manage non-access stratum (NAS) functions, such as mobility, authentication, and bearer management for UEs 115 served by base stations 105 associated with the core network 130. User IP packets can be transferred through the user plane entity, which can provide IP address allocation as well as other functions. The user plane entity can be connected to the network operators IP services 150. The operators IP services 150 can include access to the Internet, Intranet, IP Multimedia Subsystem (IMS), or a Packet-Switched Streaming Service.

[0098] Some of the network devices, such as a base station 105, can include subcomponents such as an access network entity 140, which can be an example of an access node controller (ANC). Each access network entity 140 can communicate with UEs 115 through one or more other access network transmission entities 145, which can be referred to as radio heads, smart radio heads, or transmission / reception points (TRPs). Each access network transmission entity 145 can include one or more antenna panels. In some configurations, various functions of each access network entity 140 or base station 105 can be distributed across various network devices (e.g., radio heads and ANCs) or consolidated into a single network device (e.g., a base station 105).

[0099] The wireless communications system 100 can operate using one or more frequency bands, often in the range of 300 megahertz (MHz) to 300 gigahertz (GHz). Generally, the region from 300 MHz to 3 GHz is known as the ultra-high frequency (UHF) region or decimeter band, since the wavelengths range from approximately one decimeter to one meter in length. The UHF region includes bands such as the 700 MHz, 800 MHz, 900 MHz, 1.4 GHz, 1.9 GHz, and 2.1 GHz bands. The region from 3 GHz to 30 GHz is known as the super-high frequency (SHF) region or centimeter band, since the wavelengths range from approximately one centimeter to one meter in length. The SHF region includes bands such as the 5 GHz band. The region from 30 GHz to 300 GHz is known as the extremely high frequency (EHF) region or millimeter band, since the wavelengths range from approximately one millimeter to one centimeter in length. The EHF region includes bands such as the 38 GHz and 60 GHz bands. The wireless communications system 100 can support millimeter wave (mmW) communications or centimeter wave communications between UEs 115 and base stations 105, for example.

[0100] The wireless communications system 100 can utilize both licensed and unlicensed radio frequency spectrum bands. For example, the wireless communications system 100 can employ License Assisted Access (LAA), LTE-Unlicensed (LTE-U) radio access technology, or NR technology in an unlicensed frequency band such as the 5 GHz industrial, scientific, and medical (ISM) band. When operating in unlicensed frequency

[0101] Base stations 105 or UEs 115 can be equipped with multiple antennas, which can be used to employ techniques such as transmit diversity, receive diversity, multiple-input multiple-output (MIMO) communications, or beamforming. Base stations 105 or UEs 115 can use their multiple antennas to improve the reliability and throughput of communications. For instance, base stations 105 can use beamforming to focus energy in a communication signal towards a particular set of UEs 115 that are located within a beam coverage area or cell of the base station 105. This directionality of communications can enable spatial reuse of spectrum, increasing the overall capacity of the wireless communications system 100. A receiving device, such as a UE 115, can determine the beam direction of a communication link with a base station 105 by iterating a beam sweep during initial access. The beam sweep can be performed sequentially in different sets of beams. To reduce the time for

[0102] Beamforming, which can also be referred to as spatial filtering, directional transmission, or directional reception, is a signal processing technique that can be used at a transmitting device or a receiving device (e.g., a base station 105, a UE 115) to shape or steer a beam of energy in a specific direction, such as along a line-of-sight. Beamforming can be achieved by combining the signals communicated by antennas of an array of antennas. The signals can be combined in phase and / or amplitude. The signals can be made to appear to come from a direction that is different from the physical location of the array of antennas. In some examples, the array of antennas can be an array of antenna elements for transmitting wireless signals or an array of antenna elements for receiving wireless signals. In the context of receiving devices such as base stations 105, the array of antenna elements can be used to determine a direction of arrival (DOA) of a received signal. The DOA can be determined by processing received signals at the array of antenna elements. The DOA can be determined using a variety of techniques, such as multiple signal classification (MUSIC), multiple signal parameter estimation (ESPRIT), or other techniques.

[0103] The wireless communications system 100 can be a packet-based network that operates according to a layered protocol stack. In the user plane, communications at the bearer or Packet Data Convergence Protocol (PDCP) layer can be IP -based. A Radio Link Control (RLC) layer can perform packet segmentation and reassembly to communicate over logical channels. A Medium Access Control (MAC) layer can perform priority handling and multiplexing of logical channels into transport channels. The MAC layer can also use error detection techniques, error correction techniques, or both, to support retransmissions by the MAC layer to improve link efficiency. In the control plane, the Radio Resource Control (RRC) protocol layer can provide establishment, configuration, and maintenance of an RRC connection between a UE 115 and a base station 105 or core network 130 supporting radio bearers for user plane data. At the physical layer, transport channels can be mapped to physical channels.

[0104] In the wireless communications system 100, a base station 105 can transmit multicast traffic (e.g., multicast / broadcast traffic) to one or more UEs 115 over an MRB. The base station 105 can indicate a configuration for the MRB within a MCCH message. In turn, the base station 105 can indicate the MCCH message configuration through system information transmitted to the one or more UEs 115. In some cases, the base station 105 can transmit the MCCH message indicating the MRB configuration according to a periodicity defined by the system information. Here, the one or more UEs 115 can monitor a PDCCH for the MCCH message transmitted according to the periodicity. In some cases, a UE 115 can begin monitoring the PDCCH for the MCCH message shortly after the base station 105 transmits the MCCH message. Here, the UE 115 can monitor the PDCCH for a relatively large amount of time (e.g., as compared to a UE 115 that begins monitoring the PDCCH for the MCCH message later than the base station 105 transmits the MCCH message). Thus, due to the periodic MCCH message transmissions, there can be a delay associated with the UE 115 receiving the MCCH message. The delay in receiving the MCCH message can additionally introduce latency for the one or more UEs 115 receiving the multicast traffic.

[0105] In some cases, the base station 105 can transmit the MCCH message on-demand (e.g., in addition to periodically transmitting the MCCH message, as an alternative to periodically transmitting the MCCH message). Here, the UE 115 can transmit a request for the MCCH message, and the base station 105 can transmit the MCCH message to the UE 115 in response to the request. As a result, the UE 115 can not monitor the PDCCH for the MCCH message for an extended period of time (e.g., according to a periodicity of the MCCH message), and can instead receive the MCCH message on-demand. This can reduce latency associated with receiving the MCCH message and can increase a speed of communications associated with the UE 115 and the base station 105. The UE 115 can transmit the request after receiving system information indicating the MCCH configuration. In one example, the UE 115 can transmit the request for the MCCH message to the base station 105 through a random access preamble. Here, the UE 115 can receive a RAR message from the base station 105, and then the UE 115 can monitor the PDCCH for the MCCH message. In another example, the UE 115 can transmit the request for the MCCH to the base station 105 through an RRC message. Here, the UE 115 can monitor the PDCCH for the MCCH message or can receive the MCCH message through an RRC message received from the base station 105. In either example, the MCCH message can indicate a configuration of an MRB associated with multicast traffic, and the UE 115 can receive the multicast traffic from the base station 105 according to the MRB configuration.

[0106] Figure 2 An example wireless communication system 200 that supports on-demand MCCH messages is illustrated in accordance with aspects of the present disclosure. In some examples, the wireless communication system 200 can implement aspects of the wireless communication system 100, such as a base station 105-a and a UE 115, which can be examples of the base stations 105 and UEs 115 described with reference to Figure 1 FIG. 1.

[0107] The base station 105-a can be in communication with a UPF 210 through a user plane interface 215. The UPF 210 can receive multicast data 205 (e.g., from a content provider, as described with reference to FIG. 1). The UPF 210 can transmit the multicast data 205 to the base station 105-a through the user plane interface 215. The base station 105-a can transmit the multicast data 205 to the UE 115 through a PDCCH 220 and a PDSCH 225. In some cases, the base station 105-a can transmit the multicast data 205 through a PDSCH 225 without transmitting a PDCCH 220. In some cases, the base station 105-a can transmit the multicast data 205 through a PDCCH 220 without transmitting a PDSCH 225. Figure 1The described core network) and communicates the multicast data 205 to the base station 105-a over a user plane interface 215. The user plane interface 215 can be an example of an MB-N3 interface and can be configured for multicast data flows (e.g., multicast / broadcast traffic) and deliver temporary mobile group identifiers (TMGIs) to the base station 105-a over general packet radio service (GPRS) tunneling protocol (GTP). Additionally, the UPF 210 can transmit the multicast data 205 to the base station 105-a identified by a quality of service (QoS) flow (e.g., a 5G QoS flow). The base station 105-a can additionally be in communication with the AMF 220 over a control signaling interface 225. The AMF 220 can provide control signaling for multicast / broadcast flows, temporary mobile group identities (TMGIs) setup, TMGI modification, or a combination thereof.

[0108] Based on receiving the multicast data 205, the multicast / broadcast QoS flow, and the control signaling, the base station 105-a can map the multicast data 205 to the MRB 230 or a dedicated radio bearer. That is, if the multicast data 205 is associated with a set of UEs 115 (e.g., a multicast service group), the base station 105-a can select the MRB 230 to transmit the multicast data 205 as multicast traffic to the UEs 115. Alternatively, if the multicast data 205 is associated with a single UE 115, the base station 105-a can select to transmit the multicast data 205 over a dedicated radio bearer. Thus, the base station 105-a can dynamically switch between broadcasting data (e.g., over the MRB 230) and unicast data (e.g., over a dedicated radio bearer). In some cases, the base station 105-a can transmit the multicast data 205 to the one or more UEs 115 over a physical downlink shared channel (PDSCH).

[0109] The base station 105-a can transmit multicast traffic to one or more UEs 115. Here, the base station 105-a can transmit multicast traffic through the MRB 230-a to a first set of UEs 115 (e.g., including UEs 115-a and 115-b). Each UE 115 within the first set of UEs 115 can be within a same multicast service group. That is, the base station 105-a can transmit multicast traffic through the MRB 230-a to each UE 115 within the multicast service group. The base station 105-a can also transmit multicast traffic through the MRB 230-b to a second set of UEs 115 (e.g., including UEs 115-c and 115-d). The second set of UEs 115 can correspond to a second multicast service group. That is, the base station 105-a can transmit multicast traffic through the MRB 230-a to the first multicast service group independently of the multicast traffic through the MRB 230-b to the second multicast service group. The base station 105-a can configure a multicast service group identifier for each multicast service group. In some cases, the base station 105-a can indicate the multicast identifier to each UE 115 within the multicast service group as part of the MRB 230 context. In some other cases, the UE 115 can derive the multicast service identifier based on a TMGI or multicast / broadcast flow identifier.

[0110] The UE 115 can receive the multicast traffic through the MRB 230 configured according to the MRB 230. The base station 105-a can indicate the MRB 230 configuration to the UE 115 through a MCCH message transmission (e.g., through a PDCCH or RRC message). The base station 105-a can transmit the MCCH message on-demand (e.g., in addition to periodically transmitting the MCCH message, in place of periodically transmitting the MCCH message). Here, the UE 115 can transmit a request for the MCCH message, and the base station 105-a can transmit the MCCH message to the UE 115 in response to the request. The UE 115 can transmit the request after receiving system information indicating the MCCH configuration. In one example, the UE 115 can transmit the request for the MCCH message through a random access preamble to the base station 105-a. Here, the UE 115 can receive a RAR message from the base station 105-a, and then the UE 115 can monitor the PDCCH for the MCCH message. In another example, the UE 115 can transmit the request for the MCCH through an RRC message to the base station 105-a. Here, the UE 115 can monitor the PDCCH for the MCCH message or can receive the MCCH message through an RRC message received from the base station 105-a. In either example, the MCCH message can indicate a configuration of the MRB 230 associated with the multicast traffic, and the UE 115 can receive the multicast traffic from the base station 105-a according to the MRB 230 configuration.

[0111] Each multicast service group can be supported (e.g., served) by a single base station 105-a or a set of base stations 105. For example, a multicast service group can be associated with an MCCH area served by a set of base stations 105. Here, a UE 115 within the multicast service group can move from one base station 105 to another base station 105 within the same MCCH area and can continue to receive multicast traffic associated with the same multicast service group. That is, an MRB configuration associated with a first base station 105 can also be supported by a second base station 105 within the same MCCH area. Thus, when the UE 115 moves within the MCCH area, the UE 115 can not need to reacquire the MCCH when handing over to the new base station 105.

[0112] Figure 3 An example wireless communications system 300 that supports on-demand MCCH messages is illustrated in accordance with aspects of the present disclosure. In some examples, the wireless communications system 300 can implement aspects of the wireless communications systems described with reference to Figure 1 and Figure 2 For example, the base station 105-b and the UE 115-e can be examples of a base station 105 and a UE 115 described with reference to Figure 1 and Figure 2

[0113] The UE 115-e can be in communication with the base station 105-b through a downlink channel 305 and an uplink channel 310. The base station 105-b can transmit multicast traffic 330 to one or more multicast service groups (e.g., including one or more UEs 115 as described with reference to Figure 2 The base station 105-b can transmit the multicast traffic 330 to the one or more UEs 115 through an MRB. Thus, the UE 115-e can receive the multicast traffic 330 from the base station 105-b according to an MRB configuration. The base station 105-b can indicate the MRB configuration to the UE 115-e through messages illustrated within the wireless communications system 300 exchanged over the downlink channel 305 and the uplink channel 310.

[0114] ​The base station 105-b can transmit system information to the UE 115-e within a system information block (SIB) 315. The base station 105-b can periodically broadcast the SIB 315 or, alternatively, transmit the SIB 315 on-demand. The UE 115-e can determine whether the SIB 315 is broadcast or transmitted on-demand based on a previous system information transmission from the base station 105-b. That is, the base station 105-b can transmit a master information block (e.g., through a single sideband transmission) and a system information block (e.g., through a remaining minimum system information transmission) indicating information related to a periodicity of the SIB 315, a configuration of a request for the SIB 315, or both. For an on-demand SIB 315, the UE 115-e can transmit a request for the SIB 315 through a random access preamble message (e.g., message one of a random access procedure), an RRC system information request (e.g., message three of a random access procedure), an RRC MCCH request, or within a payload of a first random access message (e.g., message “A” of a two-step random access procedure) of a two-step random access procedure. Here, the UE 115-e can receive the SIB 315 in response to transmitting the request for the SIB 315.

[0115] The SIB 315 can indicate an MCCH message configuration to the UE 115-e. The UE 115-e can monitor the downlink channel 305 for the SIB 315 for starting MCCH acquisition. The UE 115-e can acquire the MCCH due to cell selection or reselection (e.g., selecting a serving base station 105). For example, prior to cell selection, the UE 115-e can determine that the base station 105-b transmits multicast traffic 330 associated with the UE 115-e by acquiring the MCCH (e.g., receiving and decoding the MCCH message 325) of the base station 105-b. Additionally or alternatively, the UE 115-e can select the base station 105-b and start MCCH acquisition based on cell selection of the base station 105-b. In another example, the UE 115-e can acquire the MCCH due to a handover to a new cell. That is, the UE 115-e can be handed over to the base station 105-b and the UE 115-e can start MCCH acquisition based on the handover. In another example, the UE 115-e can start MCCH acquisition based on receiving an MCCH configuration change indication (e.g., through a downlink control information (DCI) format 1C) or in response to a new service starting (e.g., the UE 115-e is to start receiving the multicast traffic 330).

[0116] The MCCH configuration can indicate a periodicity (e.g., MCCH repetition period) of MCCH message 325 broadcast. The MCCH configuration can further indicate a radio network temporary identifier (RNTI) of the multicast traffic 330. Additionally, the MCCH configuration can indicate a time slot (e.g., within a PDCCH) associated with MCCH message 325. That is, the MCCH configuration can indicate an initial time slot of MCCH message 325 and a duration of MCCH message 325. The MCCH configuration can indicate a search space associated with MCCH message 325 and a time window of a channel (e.g., PDCCH) to monitor for MCCH message 325. The MCCH configuration can also indicate a MCCH modification period associated with the duration of the MCCH message configuration. That is, MCCH message 325 can be reconfigured according to the MCCH modification period. In some cases, a change in the MCCH message configuration can be indicated by a DCI format 1C (e.g., addressed by an RNTI). Thus, if the DCI format 1C indicates a change in the MCCH message configuration, UE 115-e can determine to receive an additional SIB 315 indicating an updated MCCH message configuration after the MCCH modification period.

[0117] The MCCH message configuration can indicate a delivery method of MCCH message 325. That is, MCCH message 325 can be delivered to a multicast service group (e.g., a multicast / broadcast service group) including UE 115-e and the MCCH message configuration can indicate whether MCCH message 325 is broadcast to the multicast service group or transmitted on-demand to UEs 115 within the multicast service group. In some cases, base station 105-b can transmit MCCH message 325 on-demand and through periodic broadcast. Additionally or alternatively, base station 105-b can exclusively transmit MCCH message 325 on-demand. In either case, the MCCH message configuration can optionally indicate a MCCH request configuration for the multicast service group. The MCCH request configuration can indicate a random access occasion for MCCH request 320. The MCCH request configuration can also indicate one or more of a request period of MCCH request 320, a resource (e.g., ra-preamble, ra-ssb-OccasionMaskIndex, ra-AssociationPeriodIndex) of MCCH request 320, a MCCH request 320 monitoring time window, and a MCCH request 320 monitoring period.

[0118] In some cases, UE 115-e can transmit an MCCH request 320 to base station 105-b over uplink channel 310 after receiving SIB 315. That is, UE 115-e can receive SIB 315 and determine that base station 105-b supports on-demand MCCH message transmission based on the MCCH configuration indicated by SIB 315. In cases where the MCCH configuration indicates a configuration of MCCH request 320, UE 115-e can transmit MCCH request 320 through a random access message (e.g., within a random access occasion indicated by the configuration for MCCH request 320). For example, UE 115-e can transmit MCCH request 320 through a random access preamble (e.g., message one of a random access procedure) or a first random access message (e.g., message ‘A’ of a random access procedure) in a two-step random access procedure to base station 105-a. UE 115-e can then monitor downlink channel 305 for a RAR message from base station 105-b. After receiving the RAR message, UE 115-e can monitor downlink channel 305 (e.g., a PDCCH channel) for MCCH message 325. In another example, the MCCH message configuration can not include a configuration for MCCH request 320. Here, UE 115-e can determine to transmit MCCH request 320 through an RRC message (e.g., an RRC MCCHRequest message). UE 115-e can transmit the RRC message (e.g., including MCCH request 320) in an RRC system information request (e.g., message three of a random access procedure), in an RRC MCCH request, or within a payload of a first random access message (e.g., message ‘A’ of a random access procedure) of a two-step random access procedure. Alternatively (e.g., if UE 115-e is in a connected RRC state, such as RRC CONNECTED), UE 115-e can transmit MCCH request 320 through an RRC message. After transmitting MCCH request 320 through an RRC message, UE 115-e can monitor downlink channel 305 (e.g., a PDCCH, RRC) for MCCH message 325.

[0119] The UE 115-e can monitor resources of the MCCH message 325 (e.g., as indicated by the MCCH message configuration). For example, the UE 115-e can monitor a control resource set and search space indicated by the MCCH message configuration to detect the MCCH message 325. That is, the UE 115-e can monitor within the MCCH monitoring time window, within the MCCH monitoring period, and according to the MCCH monitoring offset indicated by the MCCH message configuration. In some cases, the UE 115-e can monitor resources within the PDCCH to detect the MCCH message 325. For example, the UE 115-e can monitor a single frequency network during a slot indicated by the MCCH message configuration and by a beam within the MCCH (e.g., determined based on the MCCH monitoring period and MCCH monitoring offset indicated by the MCCH message configuration). Additionally or alternatively, the UE 115-e can determine that the MCCH message 325 is to be received through RRC signaling.

[0120] The base station 105-b can transmit the MCCH message 325 to the UE 115-e according to the MCCH message configuration indicated within the SIB 315. That is, the base station 105-b can transmit the MCCH message 325 within the MCCH monitoring period, within the MCCH monitoring time window, and according to the MCCH monitoring offset indicated by the MCCH message configuration. The base station 105-b can transmit the MCCH message 325 through the PDCCH or through the RRC message. In some cases, the base station 105-b can transmit multiple MCCH messages 325, where each MCCH message 325 serves a subset of MRBs (e.g., a configuration indicating a portion of the MRBs associated with the base station 105-a). For example, the base station 105-b can transmit a first MCCH message 325 that indicates configurations of MRBs that are associated with a delay sensitive. Additionally, the base station 105-b can transmit a second MCCH message 325 that indicates configurations of MRBs that are not delay sensitive (e.g., associated with normal latency requirements).

[0121] The base station 105-b can transmit the MCCH message 325 in response to the MCCH request 320. Here, the MCCH message 325 can be a subset of MCCH messages 325 that the base station 105-b periodically transmits (e.g., broadcasts to more than one UE 115). That is, the MCCH message 325 can include information pertaining to the UE 115-e and the multicast traffic 330 requested by the UE 115-e (e.g., through the MCCH request 320). Additionally, or alternatively, both periodic and on-demand MCCH messages can be included within the MCCH message 325. In any case, the MCCH message 325 can indicate the MRB configuration to the UE 115-e. The UE 115-e can receive the multicast traffic 330 from the base station 105-b according to the MRB configuration indicated by the MCCH message 325.

[0122] Figure 4 An example process flow 400 that supports on-demand MCCH messages is illustrated in accordance with aspects of the present disclosure. In some examples, process flow 400 can implement aspects of a wireless communications system as described with reference to Figures 1 to 3 FIG. 3. For example, the base station 105-c and the UE 115-f can be examples of the base station 105 and the UE 115 described with reference to Figures 1 to 3 FIG. 3. Process flow 400 can illustrate an example of the UE 115-f transmitting a request for a MCCH message to the base station 105-c in a case where the MCCH message configuration indicates a MCCH request configuration.

[0123] At 405, the base station 105-c can transmit system information to the UE 115-f (e.g., through a SIB). The SIB can indicate a MCCH message configuration to the UE 115-f. The MCCH message configuration can indicate a configuration for receiving a MCCH message in addition to a MCCH request configuration. The MCCH request configuration can include at least one of an indication of a time period for transmitting the request or a resource for transmitting the request. The MCCH message configuration can also include at least one of an indication of a search space associated with the MCCH message or a time period for receiving the MCCH message.

[0124] At 410, the UE 115-f can transmit a random access preamble to the base station 105-c including a request for the MCCH message. The UE 115-f can determine to transmit the request through the random access preamble based on the SIB including the MCCH message request configuration. Additionally, the UE 115-f can transmit the request according to the MCCH message request configuration.

[0125] At 415, UE 115-f can receive the RAR message from the base station. UE 115-f can start monitoring the PDCCH for the MCCH message based on receiving the RAR message from base station 105-c. That is, UE 115-f can monitor the PDCCH for the MCCH message according to the MCCH message configuration. For example, UE 115-f can monitor a control resource set of the PDCCH (e.g., associated with one or more of a monitoring time window, a monitoring period, a monitoring offset) indicated by the SIB.

[0126] At 420, base station 105-c can transmit the MCCH message to UE 115-f according to the MCCH message configuration. UE 115-f can receive the MCCH message based on monitoring the PDCCH. The MCCH message can indicate a MRB configuration (e.g., a multicast / broadcast radio bearer configuration) for multicast traffic (e.g., multicast / broadcast traffic) transmitted by base station 105-c.

[0127] At 425, base station 105-c can transmit the multicast traffic (e.g., the multicast / broadcast traffic) to UE 115-f according to the MRB configuration.

[0128] Figure 5 An example process flow 500 that supports on-demand MCCH messages is illustrated in accordance with aspects of the present disclosure. In some examples, process flow 500 can implement aspects of a wireless communications system as described with reference to Figures 1 to 3 For example, base station 105-d and UE 115-g can be examples of a base station 105 and a UE 115 as described with reference to Figures 1 to 3 Process flow 500 can illustrate an example of UE 115-g transmitting a request for a MCCH message to base station 105-d in a case where the MCCH message configuration fails to indicate a MCCH request configuration.

[0129] At 505, base station 105-d can transmit system information to UE 115-g (e.g., through a SIB). The SIB can indicate a MCCH message configuration to UE 115-g. The MCCH message configuration can also include at least one of an indication of a search space associated with the MCCH message or a period for receiving the MCCH message. Here, the SIB can fail to indicate a MCCH message request configuration.

[0130] At 510, UE 115-g can transmit, to base station 105-d, an RRC message including a request for the MCCH message. UE 115-g can determine to transmit the request over the random access preamble based on an absence of an MCCH message request configuration within the SIB. UE 115-g can transmit the RRC message within an RRC system information request, an RRC MCCH request, or a payload of a first random access message in a two-step random access procedure. After transmitting the RRC message, UE 115-g can begin monitoring a PDCCH for the MCCH message. That is, UE 115-g can monitor the PDCCH for the MCCH message according to the MCCH message configuration. For example, UE 115-g can monitor a control resource set of the PDCCH indicated by the SIB (e.g., associated with one or more of a monitoring time window, a monitoring period, a monitoring offset). In some other cases, UE 115-g can determine that the MCCH message is to be received through an RRC message (e.g., based on the MCCH message configuration).

[0131] At 515, base station 105-d can transmit, to UE 115-g, the MCCH message according to the MCCH message configuration (e.g., through a PDCCH transmission, through RRC signaling). In some cases, UE 115-g can receive the MCCH message based on monitoring the PDCCH. Additionally, or alternatively, UE 115-g can receive the MCCH message through RRC signaling from base station 105-d. The MCCH message can indicate an MRB configuration (e.g., a multicast / broadcast radio bearer configuration) for multicast traffic (e.g., multicast / broadcast traffic) transmitted by base station 105-d.

[0132] At 520, base station 105-d can transmit the multicast traffic (e.g., the multicast / broadcast traffic) to UE 115-g according to the MRB configuration.

[0133] Figure 6 A block diagram 600 of a device 605 that supports on-demand MCCH messages in accordance with aspects of the present disclosure is shown. The device 605 can be an example of aspects of a UE 115 as described herein. The device 605 can include a receiver 610, a UE coding manager 615, and a transmitter 620. The device 605 can also include a processor. The UE coding manager 615 can be implemented at least in part by one or both of a modem and a processor. Each of these components can be in communication with one another (e.g., via one or more buses).

[0134] The receiver 610 can receive information such as packets, user data, or control information associated with various information channels (e.g., control channels, data channels, and information related to on-demand MCCH messages, etc.). Information can be passed on to other components of the device 605. The receiver 610 can be a Figure 9 The described aspects of the transceiver 920 can be implemented in a receiver 610. The receiver 610 can utilize a single antenna or a set of antennas.

[0135] The UE coding manager 615 can receive, from a base station, system information indicating a MCCH message configuration, transmit, to the base station, a request for a MCCH message, receive, from the base station and in accordance with the MCCH message configuration and in response to the transmission of the request, a MCCH message indicating an MRB configuration, and receive, from the base station, multicast traffic in accordance with the MRB configuration. The UE coding manager 615 can be an example of aspects of the UE coding manager 910 described herein.

[0136] The UE coding manager 615, or its sub-components, can be implemented in hardware, code (for example, software or firmware) executed by a processor, or any combination thereof. If implemented in code executed by a processor, the functions of the UE coding manager 615, or its sub-components can be executed by a general-purpose processor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described in the present disclosure.

[0137] The UE coding manager 615, or its sub-components, can be implemented in hardware, code (for example, software or firmware) executed by a processor, or any combination thereof. If implemented in code executed by a processor, the functions of the UE coding manager 615, or its sub-components can be executed by a general-purpose processor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described in the present disclosure.

[0138] The UE decoding manager 615, or its sub-components, can be physically located at various positions, including being distributed so that portions of functions are implemented at different physical locations by one or more physical components. In some examples, the UE decoding manager 615, or its sub-components, can be in different physical locations.

[0139] The transmitter 620 can transmit signals generated by other components of the device 605. In some examples, the transmitter 620 can be collocated with the receiver 610 in a transceiver module. For example, the transmitter 620 can be a example of aspects of the transceiver 920 described with reference to FIG. 9. The transmitter 620 can utilize a single antenna or a set of antennas. Figure 9 The transmitter 620 can transmit signals generated by other components of the device 605. In some examples, the transmitter 620 can be collocated with the receiver 610 in a transceiver module. For example, the transmitter 620 can be a example of aspects of the transceiver 920 described with reference to FIG. 9. The transmitter 620 can utilize a single antenna or a set of antennas.

[0140] Figure 7 FIG. 7 shows a block diagram of a device 705 that supports on-demand MCCH messages in accordance with aspects of the present disclosure. The device 705 can be an example of aspects of a device 605 or a UE 115 as described herein. The device 705 can include a receiver 710, a UE decoding manager 715, and a transmitter 740. The device 705 can also include a processor. Each of these components can be in communication with one another (e.g., via one or more buses).

[0141] The receiver 710 can receive information such as packets, user data, or control information associated with various information channels (e.g., control channels, data channels, and information related to on-demand MCCH messages, etc.). Information can be passed on to other components of the device 705. The receiver 710 can be an example of aspects of the transceiver 920 described with reference to FIG. 9. The receiver 710 can utilize a single antenna or a set of antennas. Figure 9 The receiver 710 can receive information such as packets, user data, or control information associated with various information channels (e.g., control channels, data channels, and information related to on-demand MCCH messages, etc.). Information can be passed on to other components of the device 705. The receiver 710 can be an example of aspects of the transceiver 920 described with reference to FIG. 9. The receiver 710 can utilize a single antenna or a set of antennas.

[0142] The UE decoding manager 715 can be an example of aspects of the UE decoding manager 615 as described herein. The UE decoding manager 715 can include a system information receiver 720, a request transmitter 725, a MCCH message receiver 730, and a multicast traffic receiver 735. The UE decoding manager 715 can be an example of aspects of the UE decoding manager 910 described herein.

[0143] The system information receiver 720 can receive, from a base station, system information indicating a configuration of MCCH messages.

[0144] The request transmitter 725 can transmit, to a base station, a request for a MCCH message.

[0145] The MCCH message receiver 730 can receive a MCCH message indicating a MRB configuration in accordance with the MCCH message configuration and in response to the transmission of the request.

[0146] The multicast traffic receiver 735 can receive multicast traffic from the base station in accordance with the MRB configuration.

[0147] The transmitter 740 can transmit signals generated by other components of the device 705. In some examples, the transmitter 740 can be collocated with the receiver 710 in a transceiver module. For example, the transmitter 740 can be an example of aspects of the transceiver 920 described with reference to FIG. 9. The transmitter 740 can utilize a single antenna or a set of antennas. Figure 9

[0148] Figure 8 A block diagram 800 of a UE decoding manager 805 that supports on-demand MCCH messages in accordance with aspects of the present disclosure is shown. The UE decoding manager 805 can be an example of aspects of a UE decoding manager 615, a UE decoding manager 715, or a UE decoding manager 910 described herein. The UE decoding manager 805 can include a system information receiver 810, a request transmitter 815, a MCCH message receiver 820, a multicast traffic receiver 825, a MCCH message manager 830, and a cell reselection manager 835. Each of these modules can communicate, directly or indirectly, with one another (e.g., via one or more buses).

[0149] The system information receiver 810 can receive, from a base station, system information indicating a MCCH message configuration. In some cases, the system information indicates a MCCH message request configuration. In some cases, the MCCH message request configuration includes at least one of an indication of a time period for transmitting the request or a resource for transmitting the request. In some instances, the MCCH message configuration includes at least one of an indication of a search space associated with the MCCH message or a time period for receiving the MCCH message. In some examples, the MCCH message configuration includes an indication of a repetition period of the MCCH message, an identifier associated with the multicast traffic, one or more slots associated with the MCCH message, a modification period associated with the MCCH message, a new service start, or a combination thereof.

[0150] In some examples, the system information receiver 810 can receive the system information based on the UE performing a cell reselection procedure, the UE performing a cell selection procedure, the UE performing a handover procedure, a change associated with the MCCH message, or a combination thereof. In some cases, the system information includes an indication of a zone identifier.

[0151] ​Request transmitter 815 can transmit, to the base station, a request for the MCCH message. In some examples, request transmitter 815 can transmit the request for the MCCH message based on the system information indicating that the MCCH message is to be received on-demand.

[0152] In some examples, request transmitter 815 can transmit the request to the base station through a random access preamble within a random access occasion indicated by the MCCH message request configuration within the system information. In some cases, request transmitter 815 can determine to transmit the request through the random access preamble based on the system information including the MCCH message request configuration.

[0153] In some examples, request transmitter 815 can transmit the request through an RRC request message. In some cases, request transmitter 815 can determine to transmit the request through the RRC request message based on an absence of a MCCH message request configuration within the SIB. In some cases, transmitting the request further includes transmitting the request in accordance with the MCCH message request configuration. In some cases, the RRC request message is included within a payload of a first random access message of a two-step random access procedure, an RRC system information request, or an RRC MCCH request.

[0154] MCCH message receiver 820 can receive, in accordance with the MCCH message configuration and in response to the transmission of the request, a MCCH message indicating a MRB configuration. In some cases, the MRB configuration is a multicast / broadcast service radio bearer configuration. In some cases, the MCCH message includes both an on-demand MCCH message and a periodic MCCH message. In some examples, the MCCH message is associated with a set of MRB configurations that includes the MRB configuration that is delay sensitive. In some other examples, the MCCH message is associated with a set of MRB configurations that is delay insensitive. In some instances, the set of MRB configurations includes the MRB configuration. In some examples, MCCH message receiver 820 can receive the MCCH message through an RRC configuration message in response to the RRC request message.

[0155] In some examples, MCCH message receiver 820 can determine a service group associated with the multicast traffic, where receiving the MCCH message is based on the determined service group. In some examples, MCCH message receiver 820 can determine a service group identifier associated with the service group based on a MRB context or a multicast broadcast service identifier.

[0156] Multicast traffic receiver 825 can receive, from the base station, multicast traffic in accordance with the MRB configuration. In some cases, the multicast traffic is multicast / broadcast traffic.

[0157] The MCCH message manager 830 can receive, from a base station, a RAR message, where receiving the MCCH message is based on receiving the RAR message. In some examples, the MCCH message manager 830 can monitor a physical downlink control channel for the MCCH message according to the MCCH message configuration, where receiving the MCCH message is based on monitoring the physical downlink control channel. In some cases, the MCCH message manager 830 can monitor a control resource set of the physical downlink control channel indicated by the system information. In some cases, the control resource set is associated with a monitoring time window, a monitoring period, a monitoring offset, or a combination thereof.

[0158] The cell reselection manager 835 can perform a cell reselection procedure from a first base station to a second base station, where the base station is the first base station. In some examples, the cell reselection manager 835 can determine that the second base station transmits the multicast traffic according to the MRB configuration based on the same area identifier being associated with a first MCCH message and a second MCCH message associated with the second base station, where the MCCH message is the first MCCH message. In some cases, the cell reselection manager 835 can determine to refrain from monitoring for system information from the second base station based on determining that the second base station transmits the multicast traffic according to the MRB configuration.

[0159] In some examples, the cell reselection manager 835 can determine to perform a cell reselection procedure from a first base station, where the base station is a second base station. In some cases, the cell reselection manager 835 can receive an initial multicast control message from the first base station based on determining to perform the cell reselection procedure. In some instances, the cell reselection manager 835 can determine that the second base station transmits the multicast traffic based on the initial multicast control message. In some examples, the cell reselection manager 835 can perform a cell reselection procedure from the first base station to the second base station based on determining that the second base station transmits the multicast traffic, where receiving the system information is based on performing the cell reselection procedure.

[0160] Figure 9 A diagram illustrating a system 900 including a device 905 that supports on-demand MCCH messages in accordance with aspects of the present disclosure is shown. The device 905 can be an example of or include the components of device 605, device 705, or a UE 115 as described herein. The device 905 can include components for bi-directional voice and data communications including components for transmitting and receiving communications, including a UE coding manager 910, an I / O controller 915, a transceiver 920, an antenna 925, memory 930, and a processor 940. These components can be in electronic communication via one or more buses (e.g., bus 945).

[0161] The UE decoding manager 910 can receive, from a base station, system information indicating a MCCH message configuration; transmit, to the base station, a request for a MCCH message; receive, in accordance with the MCCH message configuration and in response to the transmission of the request, a MCCH message indicating an MRB configuration; and receive, from the base station, multicast traffic in accordance with the MRB configuration. At least one implementation can enable the UE decoding manager 910 to receive MCCH messages on demand. Based on implementing this reception, one or more processors of the device 905 (e.g., a processor that controls or is incorporated into the UE decoding manager 910) can experience reduced power consumption and facilitate low-latency communications, among other benefits.

[0162] The I / O controller 915 can manage input and output signals for the device 905. The I / O controller 915 can also manage peripherals not integrated into the device 905. In some cases, the I / O controller 915 can represent a physical connection or port to or another known operating system. In other cases, the I / O controller 915 can represent or interact with a modem, a keyboard, a mouse, a touchscreen, or similar devices. In some cases, the I / O controller 915 can be implemented as part of a processor. In some cases, a user can interact with the device 905 via the I / O controller 915 or via hardware components controlled by the I / O controller 915.

[0163] The transceiver 920 can communicate bi-directionally, via one or more antennas, wired, or wireless links as described above. For example, the transceiver 920 can represent a wireless transceiver and can communicate bi-directionally with another wireless transceiver. The transceiver 920 can also include a modem to modulate the packets and provide the modulated packets to the antennas for transmission, and to demodulate packets received from the antennas.

[0164] In some cases, the wireless device can include a single antenna 925. However, in some cases the device can have more than one antenna 925, which can be capable of concurrently transmitting or receiving multiple wireless transmissions.

[0165] The memory 930 can include random access memory (RAM) and read-only memory (ROM). The memory 930 can store computer-readable, computer-executable code 935 including instructions that, when executed, cause the processor to perform various functions described herein. In some cases, the memory 930 can contain, among other computer-readable code 935, a basic input / output system (BIOS) that can control basic hardware or software operation such as the interaction with peripheral components or devices.

[0166] The processor 940 may include an intelligent hardware device (e.g., a general-purpose processor, a DSP, a CPU, a microcontroller, an ASIC, an FPGA, a programmable logic device, discrete gate or transistor logic components, discrete hardware components, or any combination thereof). In some cases, the processor 940 may be configured to operate a memory array using a memory controller. In other cases, the memory controller may be integrated into the processor 940. The processor 940 may be configured to execute computer-readable instructions stored in a memory (e.g., memory 930) to cause the device 905 to perform various functions (e.g., functions or tasks that support on-demand MCCH messages).

[0167] The code 935 may include instructions for implementing various aspects of the present disclosure, including instructions for supporting wireless communications. The code 935 may be stored in a non-transitory computer-readable medium, such as system memory or other types of memory. In some cases, the code 935 may not be directly executed by the processor 940, but may cause a computer (e.g., when compiled and executed) to perform the functions described herein.

[0168] Figure 10 A block diagram 1000 is shown of a device 1005 that supports on-demand MCCH messages according to aspects of the present disclosure. The device 1005 can be an example of aspects of the base station 105 as described herein. The device 1005 can include a receiver 1010, a communication manager 1015, and a transmitter 1020. The device 1005 can also include a processor. Each of these components can be in communication with each other (e.g., via one or more buses).

[0169] The receiver 1010 may receive information such as packets, user data, or control information associated with various information channels (e.g., control channels, data channels, and information related to on-demand MCCH messages, etc.). The information may be passed to other components of the device 1005. The receiver 1010 may be a reference Figure 13 Examples of aspects of the described transceiver 1320. The receiver 1010 may utilize a single antenna or a collection of antennas.

[0170] The communication manager 1015 may transmit system information indicating an MCCH message configuration to a UE; receive a request for an MCCH message from the UE; transmit an MCCH message indicating an MRB configuration according to the MCCH message configuration and in response to receiving the request; and transmit multicast traffic to the UE according to the MRB configuration. The communication manager 1015 may be an example of aspects of the communication manager 1310 as described herein.

[0171] The communications manager 1015, or its sub-components, can be implemented in hardware, code (e.g., software or firmware) executed by a processor, or any combination thereof. If implemented in code executed by a processor, the functions of the communications manager 1015, or its sub-components can be executed by a general-purpose processor, a DSP, an ASIC, an FPGA or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described in the present disclosure.

[0172] The communications manager 1015, or its sub-components, can be physically located in various places in the apparatus including but not limited to centralized computing devices, decentralized computing devices, or a mix thereof. In some examples, the communications manager 1015, or its sub-components, can be a separate and distinct component in accordance with various aspects of the present disclosure. In some examples, the communications manager 1015, or its sub-components, can be combined with one or more other hardware components, including but not limited to an input / output (I / O) component, a transceiver, a network server, another computing device, one or more other components described in the present disclosure, or a combination thereof in accordance with various aspects of the present disclosure.

[0173] The transmitter 1020 can transmit signals generated by other components of the device 1005. In some examples, the transmitter 1020 can be collocated with a receiver 1010 in a transceiver module. For example, the transmitter 1020 can be an example of aspects of the transmitter 1320 Figure 13 described with reference to FIG. 13. The transmitter 1020 can utilize a single antenna or a set of antennas.

[0174] Figure 11 A block diagram 1100 of a device 1105 that supports on-demand MCCH messages in accordance with aspects of the present disclosure is shown. The device 1105 can be an example of aspects of a device 1005 or a base station 105 as described herein. The device 1105 can include a receiver 1110, a communications manager 1115, and a transmitter 1140. The device 1105 can also include a processor. Each of these components can be in communication with one another (e.g., via one or more buses).

[0175] The receiver 1110 can receive information such as packets, user data, or control information associated with various information channels (e.g., control channels, data channels, and information related to on-demand MCCH messages, etc.). Information can be passed on to other components of the device 1105. The receiver 1110 can be an example of aspects of the transceiver 1320 Figure 13 described with reference to FIG. 13. The receiver 1110 can utilize a single antenna or a set of antennas.

[0176] The communications manager 1115 can be an example of aspects of the communications manager 1015 as described herein. The communications manager 1115 can include a system information transmitter 1120, a MCCH request receiver 1125, a MCCH message transmitter 1130, and a multicast traffic transmitter 1135. The communications manager 1115 can be an example of aspects of the communications manager 1310 as described herein.

[0177] The system information transmitter 1120 can transmit, to a UE, system information indicating a MCCH message configuration.

[0178] The MCCH request receiver 1125 can receive, from the UE, a request for a MCCH message.

[0179] The MCCH message transmitter 1130 can transmit, in accordance with the MCCH message configuration and in response to the reception of the request, a MCCH message indicating a MRB configuration.

[0180] The multicast traffic transmitter 1135 can transmit, to the UE, multicast traffic in accordance with the MRB configuration.

[0181] The transmitter 1140 can transmit signals generated by other components of the device 1105. In some examples, the transmitter 1140 can be collocated with the receiver 1110 in a transceiver module. For example, the transmitter 1140 can be an example of aspects of the transceiver 1320 described with reference to FIG. 13. The transmitter 1140 can utilize a single antenna or a set of antennas. Figure 13

[0182] Figure 12 A block diagram 1200 of a communications manager 1205 that supports on-demand MCCH messages in accordance with aspects of the present disclosure is shown. The communications manager 1205 can be an example of aspects of a communications manager 1015, a communications manager 1115, or a communications manager 1310 as described herein. The communications manager 1205 can include a system information transmitter 1210, a MCCH request receiver 1215, a MCCH message transmitter 1220, a multicast traffic transmitter 1225, a RAR transmitter 1230, and a serving group manager 1235. Each of these modules can communicate, directly or indirectly, with one another (e.g., via one or more buses).

[0183] ​The system information transmitter 1210 can transmit system information to a UE indicating a MCCH message configuration. In some examples, the system information transmitter 1210 can transmit the system information based on the UE performing a cell reselection procedure, the UE performing a cell selection procedure, the UE performing a handover procedure, a change associated with the MCCH message, or a combination thereof. In some cases, the system information indicates a MCCH message request configuration. In some instances, the MCCH message request configuration includes at least one of an indication of a time period for transmitting the request by the UE or a resource for transmitting the request by the UE. In some examples, the MCCH message configuration includes at least one of an indication of a search space associated with the MCCH message or a time period for receiving the MCCH message. In some cases, the MCCH message configuration includes an indication of a repetition period of the MCCH message, an identifier associated with the multicast traffic, one or more slots associated with the MCCH message, a modification period associated with the MCCH message, a new service start, or a combination thereof.

[0184] The MCCH request receiver 1215 can receive a request for a MCCH message from the UE. In some examples, the MCCH request receiver 1215 can receive the request from the UE through a random access preamble within a random access occasion indicated by a MCCH message request configuration within the system information. In some cases, the MCCH request receiver 1215 can receive the request through an RRC request message. In some instances, receiving the request further includes receiving the request in accordance with the MCCH message request configuration. In some examples, the MCCH request receiver 1215 can receive the request for the MCCH message based on system information indicating that the MCCH message is to be transmitted on-demand. In some cases, receiving the request through the random access preamble is based on the system information including the MCCH message request configuration. In some instances, the RRC request message is included within an RRC system information request, an RRC MCCH request, or a payload of a first random access message of a two-step random access procedure. In some examples, receiving the request through the RRC request message is based on an absence of a MCCH message request configuration within the SIB.

[0185] The MCCH message transmitter 1220 can transmit a MCCH message indicating the MRB configuration in accordance with the MCCH message configuration and in response to the reception of the request. In some examples, the MCCH message transmitter 1220 can transmit the MCCH message by an RRC configuration message in response to the RRC request message. In some cases, the MCCH message transmitter 1220 can transmit the MCCH message over a physical downlink control channel in accordance with the MCCH message configuration. In some instances, the MCCH message transmitter 1220 can transmit the MCCH message within a control resource set indicated by the system information. In some cases, the control resource set is associated with a monitoring time window, a monitoring period, a monitoring offset, or a combination thereof.

[0186] In some examples, the MCCH message is a first MCCH message. In some cases, the first MCCH message is associated with a first MRB configuration set including at least the MRB configuration. Here, the MCCH message transmitter 1220 can transmit a second MCCH message associated with a second MRB configuration set, where one of the first MRB configuration set or the second MRB configuration set is delay sensitive. In some instances, the MCCH message includes both an on-demand MCCH message and a periodic MCCH message. In some cases, the MRB configuration is a multicast / broadcast service radio bearer configuration.

[0187] The multicast traffic transmitter 1225 can transmit multicast traffic to the UE in accordance with the MRB configuration. In some cases, the multicast traffic is multicast / broadcast traffic.

[0188] The RAR transmitter 1230 can transmit a RAR message to the UE, where transmitting the MCCH message is based on receiving the RAR message.

[0189] The service group manager 1235 can determine a service group associated with the multicast traffic, where transmitting the MCCH message is based on the determined service group. In some examples, the service group manager 1235 can determine a service group identifier associated with the service group based on a MRB context or a multicast broadcast service identifier.

[0190] Figure 13A diagram of a system 1300 including a device 1305 that supports on-demand MCCH messages in accordance with aspects of the present disclosure is shown. The device 1305 can be an example of or include the components of device 1005, device 1105, or a base station 105 as described herein. The device 1305 can include components for bi-directional voice and data communications including components for transmitting and receiving communications, including a communications manager 1310, a network communications manager 1315, a transceiver 1320, an antenna 1325, memory 1330, a processor 1340, and an inter-station communications manager 1345. These components can be in electronic communication via one or more buses (e.g., bus 1350).

[0191] The communications manager 1310 can transmit, to a UE, system information indicating a MCCH message configuration; receive, from the UE, a request for a MCCH message; transmit, in accordance with the MCCH message configuration and in response to the reception of the request, a MCCH message indicating a MRB configuration; and transmit, to the UE in accordance with the MRB configuration, multicast traffic.

[0192] The network communications manager 1315 can manage communications with a core network (e.g., via one or more wired backhaul links). For example, the network communications manager 1315 can manage the transfer of data communications for client devices, such as one or more UEs 115.

[0193] The transceiver 1320 can communicate bi-directionally, via one or more antennas, wired, or wireless links as described above. For example, the transceiver 1320 can represent a wireless transceiver and can communicate bi-directionally with another wireless transceiver. The transceiver 1320 also can include a modem to modulate the packets and to provide the modulated packets to the antennas for transmission, and to demodulate packets received from the antennas.

[0194] In some cases, the wireless device can include a single antenna 1325. However, in some cases the device can have more than one antenna 1325, which can be capable of concurrently transmitting or receiving multiple wireless transmissions.

[0195] The memory 1330 can include RAM, ROM, or a combination thereof. The memory 1330 can store computer-readable code 1335 including instructions that, when executed by a processor (e.g., the processor 1340), cause the device to perform various functions described herein. In some cases, the memory 1330 can include, for example, a BIOS, which can control basic hardware or software operation such as the interaction with peripheral components or devices.

[0196] The processor 1340 can include an intelligent hardware device, (e.g., a general- purpose processor, a DSP, a CPU, a microcontroller, an ASIC, an FPGA, a programmable logic device, a discrete gate or transistor logic component, a discrete hardware component, or any combination thereof). In some examples, the processor 1340 can be configured to operate a memory array using a memory controller. In some examples, a memory controller can be integrated into the processor 1340. The processor 1340 can be configured to execute computer-readable instructions stored in a memory (e.g., the memory 1330) to cause the device 1305 to perform various functions (e.g., functions or tasks for supporting on-demand MCCH messages).

[0197] The inter-station communications manager 1345 can manage communications with other base station 105 and can include a controller or scheduler for controlling

[0198] The code 1335 can include instructions for implementing aspects of the present disclosure, including instructions for supporting wireless communications. The code 1335 can be stored in a non-transitory computer-readable medium such as system memory or other type of memory. In some examples, the code 1335 can not be directly executable by the processor 1340 but can cause a computer (e.g., when compiled and executed) to perform functions described herein.

[0199] Figure 14 A method 1400 for supporting on-demand MCCH messages is shown and described in accordance with aspects of the present disclosure. Operations of the method 1400 can be implemented by a UE 115 or its components as described herein. For example, the operations of the method 1400 can be performed by a UE coding manager as described with reference to FIG. 6. In some examples, a UE can execute a set of instructions to control its functional elements to perform the functions described below. Additionally or alternatively, the UE can perform aspects of the functions described below using special-purpose hardware. Figures 6 to 9

[0200] At 1405, the UE can receive, from a base station, system information indicating a configuration of MCCH messages. The operations of 1405 can be performed according to the methods described herein. In some examples, aspects of the operations of 1405 can be performed by a system information receiver as described with reference to FIG. 6. Figures 6 to 9

[0201] ​​At 1410, the UE can transmit, to the base station, a request for the MCCH message. The operations of 1410 can be performed according to the methods described herein. In some examples, aspects of the operations of 1410 can be performed by a request transmitter as described with reference to Figures 6 to 9

[0202] At 1415, the UE can receive, in accordance with the MCCH message and in response to the transmission of the request, a MCCH message indicating a MRB configuration. The operations of 1415 can be performed according to the methods described herein. In some examples, aspects of the operations of 1415 can be performed by a MCCH message receiver as described with reference to Figures 6 to 9

[0203] At 1420, the UE can receive, from the base station, multicast traffic in accordance with the MRB configuration. The operations of 1420 can be performed according to the methods described herein. In some examples, aspects of the operations of 1420 can be performed by a multicast traffic receiver as described with reference to Figures 6 to 9

[0204] Figure 15 A method 1500 that supports on-demand MCCH messages is shown and described in accordance with aspects of the present disclosure. The operations of method 1500 can be implemented by a UE 115 or its components as described herein. For example, the operations of method 1500 can be performed by a UE coding manager as described with reference to Figures 6 to 9

[0205] At 1505, the UE can receive, from a base station, system information indicating a MCCH message configuration. The operations of 1505 can be performed according to the methods described herein. In some examples, aspects of the operations of 1505 can be performed by a system information receiver as described with reference to Figures 6 to 9

[0206] At 1510, the UE can determine to transmit the request over the random access preamble based on the system information including the MCCH message request configuration. The operations of 1510 can be performed according to the methods described herein. In some examples, aspects of the operations of 1510 can be performed by a request transmitter as described with reference to Figures 6 to 9

[0207] ​​​​​​At 1515, the UE can transmit, to the base station, a request for the MCCH message through a random access preamble to the base station within a random access occasion indicated by the MCCH message request configuration within the system information. The operations of 1535 can be performed according to the methods described herein. In some examples, aspects of the operations of 1535 can be performed by a request transmitter as described with reference to Figures 6 to 9 FIG. 19.

[0208] At 1520, the UE can receive a RAR message from the base station, where receiving the MCCH message is based on receiving the RAR message. The operations of 1520 can be performed according to the methods described herein. In some examples, aspects of the operations of 1520 can be performed by a MCCH message manager as described with reference to Figures 6 to 9 FIG. 19.

[0209] At 1525, the UE can receive, in accordance with the MCCH message configuration and in response to the transmission of the request, a MCCH message indicating a MRB configuration. The operations of 1525 can be performed according to the methods described herein. In some examples, aspects of the operations of 15255 can be performed by a MCCH message receiver as described with reference to Figures 6 to 9 FIG. 19.

[0210] At 1530, the UE can receive, from the base station, multicast traffic in accordance with the MRB configuration. The operations of 1530 can be performed according to the methods described herein. In some examples, aspects of the operations of 1530 can be performed by a multicast traffic receiver as described with reference to Figures 6 to 9 FIG. 19.

[0211] Figure 16 A method 1600 that supports on-demand MCCH messages is shown and described in accordance with aspects of the present disclosure. The operations of method 1600 can be implemented by a UE 115 or its components as described herein. For example, the operations of method 1600 can be performed by a UE coding manager as described with reference to Figures 6 to 9 FIG. 19.

[0212] At 1605, the UE can receive, from a base station, system information indicating a MCCH message configuration. The operations of 1605 can be performed according to the methods described herein. In some examples, aspects of the operations of 1605 can be performed by a system information receiver as described with reference to Figures 6 to 9 FIG. 19.

[0213] At 1610, the UE can determine to transmit the request through the RRC request message based on an absence of an MCCH message request configuration within the SIB. The operations of 1610 can be performed according to the methods described herein. In some examples, aspects of the operations of 1610 can be performed by a request transmitter as described with reference to FIGs. 9 through 12. Figures 6 to 9

[0214] At 1615, the UE can transmit, to the base station, a request for an MCCH message through the RRC request message. The operations of 1630 can be performed according to the methods described herein. In some examples, aspects of the operations of 1630 can be performed by a request transmitter as described with reference to FIGs. 9 through 12. Figures 6 to 9

[0215] At 1620, the UE can receive, in accordance with the MCCH message configuration and in response to the transmission of the request, an MCCH message indicating an MRB configuration. The operations of 1620 can be performed according to the methods described herein. In some examples, aspects of the operations of 1620 can be performed by an MCCH message receiver as described with reference to FIGs. 9 through 12. Figures 6 to 9

[0216] At 1625, the UE can receive multicast traffic from the base station in accordance with the MRB configuration. The operations of 1625 can be performed according to the methods described herein. In some examples, aspects of the operations of 1625 can be performed by a multicast traffic receiver as described with reference to FIGs. 9 through 12. Figures 6 to 9

[0217] Figure 17 A method 1700 that supports on-demand MCCH messages is shown and described in accordance with aspects of the present disclosure. The operations of method 1700 can be implemented by a base station 105 or its components as described herein. For example, the operations of method 1700 can be performed by a communications manager as described with reference to FIGs. 9 through 12. In some examples, a base station can execute a set of instructions to control the functional elements of the base station to perform the functions described below. Additionally or alternatively, the base station can perform aspects of the functions described below using special-purpose hardware. Figures 10 to 13

[0218] At 1705, the base station can transmit, to a UE, system information indicating an MCCH message configuration. The operations of 1705 can be performed according to the methods described herein. In some examples, aspects of the operations of 1705 can be performed by a system information transmitter as described with reference to FIGs. 9 through 12. Figures 10 to 13

[0219] At 1710, the base station can receive, from a UE, a request for an MCCH message. The operations of 1710 can be performed according to the methods described herein. In some examples, aspects of the operations of 1710 can be performed by a request receiver as described with reference to FIGs. 9 through 12. Figures 10 to 13 ​​​​​​The described MCCH request receiver performs.

[0220] At 1715, the base station can transmit a MCCH message indicating the MRB configuration in accordance with the MCCH message configuration and in response to the reception of the request. The operations of 1715 can be performed according to the methods described herein. In some examples, aspects of the operations of 1715 can be performed by a MCCH message transmitter as described with reference to Figures 10 to 13 The described MCCH message transmitter performs.

[0221] At 1720, the base station can transmit multicast traffic to the UE in accordance with the MRB configuration. The operations of 1720 can be performed according to the methods described herein. In some examples, aspects of the operations of 1720 can be performed by a multicast traffic transmitter as described with reference to Figures 10 to 13 The described multicast traffic transmitter performs.

[0222] Figure 18 A method 1800 that supports on-demand MCCH messages is shown that illustrates aspects in accordance with the present disclosure. The operations of method 1800 can be implemented by a base station 105 or its components as described herein. For example, the operations of method 1800 can be performed by a communications manager as described with reference to Figures 10 to 13 FIGS. 13 through 17, as described herein. In some examples, a base station can execute a set of instructions to control the functional elements of the base station to perform the functions described below. Additionally or alternatively, the base station can perform aspects of the functions described below using special-purpose hardware.

[0223] At 1805, the base station can transmit system information to a UE indicating a MCCH message configuration. The operations of 1805 can be performed according to the methods described herein. In some examples, aspects of the operations of 1805 can be performed by a system information transmitter as described with reference to Figures 10 to 13 The described system information transmitter performs.

[0224] At 1810, the base station can receive a request for a MCCH message from a UE in a random access preamble from the UE within a random access occasion indicated by the MCCH message request configuration within the system information. The operations of 1830 can be performed according to the methods described herein. In some examples, aspects of the operations of 1830 can be performed by a MCCH request receiver as described with reference to Figures 10 to 13 The described MCCH request receiver performs.

[0225] At 1815, the base station can transmit a RAR message to the UE, where transmitting the MCCH message is based on receiving the RAR message. The operations of 1815 can be performed according to the methods described herein. In some examples, aspects of the operations of 1815 can be performed by a RAR transmitter as described with reference to Figures 10 to 13 The described RAR transmitter performs.

[0226] At 1820, the base station can transmit, in accordance with the MCCH message configuration and in response to the reception of the request, a MCCH message indicating a MRB configuration. The operations of 1820 can be performed according to the methods described herein. In some examples, aspects of the operations of 1820 can be performed by a MCCH message transmitter as described with reference to Figures 10 to 13 FIG. 19.

[0227] At 1825, the base station can transmit, in accordance with the MRB configuration, multicast traffic to the UE. The operations of 1825 can be performed according to the methods described herein. In some examples, aspects of the operations of 1825 can be performed by a multicast traffic transmitter as described with reference to Figures 10 to 13 FIG. 19.

[0228] Figure 19 A method 1900 that supports on-demand MCCH messages is shown and described in accordance with aspects of the present disclosure. The operations of method 1900 can be implemented by a base station 105 or its components as described herein. For example, the operations of method 1900 can be performed by a communications manager as described with reference to Figures 10 to 13 FIG. 19. In some examples, a base station can execute a set of instructions to control its functional elements to perform the functions described below. Additionally or alternatively, the base station can perform aspects of the functions described below using special-purpose hardware.

[0229] At 1905, the base station can transmit, to a UE, system information indicating a MCCH message configuration. The operations of 1905 can be performed according to the methods described herein. In some examples, aspects of the operations of 1905 can be performed by a system information transmitter as described with reference to Figures 10 to 13 FIG. 19.

[0230] At 1910, the base station can receive, from the UE, a request for the MCCH message by a RRC request message. The operations of 1925 can be performed according to the methods described herein. In some examples, aspects of the operations of 1925 can be performed by a MCCH request receiver as described with reference to Figures 10 to 13 FIG. 19.

[0231] At 1915, the base station can transmit, in accordance with the MCCH message configuration and in response to the reception of the request, a MCCH message indicating a MRB configuration. The operations of 1915 can be performed according to the methods described herein. In some examples, aspects of the operations of 1915 can be performed by a MCCH message transmitter as described with reference to Figures 10 to 13 FIG. 19.

[0232] At 1920, the base station can transmit, in accordance with the MRB configuration, multicast traffic to the UE. The operations of 1920 can be performed according to the methods described herein. In some examples, aspects of the operations of 1920 can be performed by a multicast traffic transmitter as described with reference to Figures 10 to 13The described multicast traffic transmitter to perform.

[0233] It should be noted that the methods described herein describe possible implementations, and that the operations and the steps can be rearranged or otherwise modified and that other implementations are possible. Further, aspects from two or more of the methods can be combined.

[0234] An overview of examples of the present disclosure is provided below:

[0235] Example 1 : A method for wireless communication at a user equipment (UE), comprising: receiving, from a base station, system information indicating a multicast control channel message configuration; transmitting, to the base station, a request for a multicast control channel message; receiving, in accordance with the multicast control channel message configuration and in response to the transmission of the request, a multicast control channel message indicating a multicast service radio bearer configuration; and receiving, from the base station, multicast traffic in accordance with the multicast service radio bearer configuration.

[0236] Example 2: The method of example 1, wherein transmitting the request for the multicast control channel message further comprises: transmitting the request to the base station through a random access preamble within a random access occasion indicated by the multicast control channel message request configuration within the system information.

[0237] Example 3: The method of example 2, further comprising: receiving, from the base station, a random access response message, wherein receiving the multicast control channel message is based at least in part on receiving the random access response message.

[0238] Example 4: The method of any one of examples 2-3, further comprising: determining to transmit the request through the random access preamble based at least in part on the system information including the multicast control channel message request configuration.

[0239] Example 5: The method of any one of examples 1-4, wherein transmitting the request for the multicast control channel message further comprises: transmitting the request through a radio resource control request message.

[0240] Example 6: The method of example 5, wherein the radio resource control request message is included within a payload of a first random access message in a two-step random access procedure, a radio resource control system information request, a radio resource control multicast control channel request, or a radio resource control configuration message.

[0241] Example 7: The method of any one of examples 5-6, wherein receiving the multicast control channel message further comprises: receiving the multicast control channel message through a radio resource control configuration message in response to the radio resource control request message.

[0242] Example 8: The method of any of Examples 5 through 7, further comprising determining to transmit the request through the radio resource control request message based at least in part on an absence of a multicast control channel message request configuration within the system information.

[0243] Example 9: The method of any of Examples 1 through 8, wherein: the system information indicates a multicast control channel message request configuration; and transmitting the request further comprises transmitting the request in accordance with the multicast control channel message request configuration.

[0244] Example 10: The method of Example 9, wherein the multicast control channel message request configuration comprises at least one of an indication of a time period for transmitting the request or a resource for transmitting the request.

[0245] Example 11: The method of any of Examples 1 through 9, further comprising monitoring a physical downlink control channel for the multicast control channel message in accordance with the multicast control channel message configuration, wherein receiving the multicast control channel message is based at least in part on monitoring the physical downlink control channel.

[0246] Example 12: The method of Example 11, wherein monitoring the physical downlink control channel further comprises monitoring a control resource set of the physical downlink control channel indicated by the system information.

[0247] Example 13: The method of Example 12, wherein the control resource set is associated with a monitoring time window, a monitoring period, a monitoring offset, or a combination thereof.

[0248] Example 14: The method of any of Examples 1 through 13, wherein

[0249] the multicast control channel message is associated with a set of delay-sensitive multicast service radio bearer configurations comprising the multicast service radio bearer configuration.

[0250] Example 15: The method of any of Examples 1 through 14, wherein: the multicast control channel message is associated with a set of delay-insensitive multicast service radio bearer configurations; and the set of multicast service radio bearer configurations comprises the multicast service radio bearer configuration.

[0251] Example 16: The method of any of Examples 1 through 15, wherein: transmitting the request for the multicast control channel message is based at least in part on the system information indicating that the multicast control channel message is to be received on-demand.

[0252] Example 17: The method of any of Examples 1 through 16, further comprising determining a service group associated with the multicast traffic, wherein receiving the multicast control channel message is based at least in part on the determined service group.

[0253] Example 18: The method of example 17, wherein determining the service group further comprises: determining a service group identifier associated with the service group based at least in part on a multicast service radio bearer context or a multicast broadcast service identifier.

[0254] Example 19: The method of any of examples 1 to 18, wherein the multicast control channel message comprises both an on-demand multicast control channel message and a periodic multicast control channel message.

[0255] Example 20: The method of any of examples 1 to 19, further comprising: performing a cell reselection procedure from a first base station to a second base station, wherein the base station is the first base station; determining that the second base station transmits the multicast traffic according to the multicast service radio bearer configuration based at least in part on a same zone identifier associated with a first multicast control channel message and a second multicast control channel message associated with the second base station, wherein the multicast control channel message is the first multicast control channel message; and determining to refrain from monitoring for system information from the second base station based at least in part on determining that the second base station transmits the multicast traffic according to the multicast service radio bearer configuration.

[0256] Example 21: The method of example 20, wherein the system information comprises an indication of the zone identifier.

[0257] Example 22: The method of any of examples 1 to 21, further comprising: determining to perform a cell reselection procedure from a first base station, wherein the base station is a second base station; receiving an initial multicast control message from the first base station based at least in part on determining to perform the cell reselection procedure; determining that the second base station transmits the multicast traffic based at least in part on the initial multicast control message; and performing the cell reselection procedure from the first base station to the second base station based at least in part on determining that the second base station transmits the multicast traffic, wherein receiving the system information is based at least in part on performing the cell reselection procedure.

[0258] Example 23: The method of any of examples 1 to 22, wherein: receiving the system information is based at least in part on: the UE performing a cell reselection procedure, the UE performing a cell selection procedure, the UE performing a handover procedure, a change associated with the multicast control channel message, or a combination thereof.

[0259] Example 24: The method of any of examples 1 to 23, wherein the multicast control channel message configuration comprises at least one of an indication of a search space associated with the multicast control channel message or a time period for receiving the multicast control channel message.

[0260] Example 25: The method of any one of Examples 1 to 24, wherein: the multicast service radio bearer configuration is a multicast / broadcast service radio bearer configuration; and the multicast traffic is multicast / broadcast traffic.

[0261] Example 26: The method of any one of Examples 1 to 25, wherein

[0262] The multicast control channel message configuration includes an indication of a repetition period of the multicast control channel message, an identifier associated with the multicast traffic, one or more time slots associated with the multicast control channel message, a modification period associated with the multicast control channel message, a new service start, or a combination thereof.

[0263] Example 27: A method for wireless communication at a base station, comprising: transmitting system information indicating a multicast control channel message configuration to a user equipment (UE); receiving a request for a multicast control channel message from the UE; transmitting a multicast control channel message indicating a multicast service radio bearer configuration based on the multicast control channel message configuration and in response to receiving the request; and transmitting multicast traffic to the UE based on the multicast service radio bearer configuration.

[0264] Example 28: The method of Example 27, wherein receiving the request for the multicast control channel message further comprises receiving the request from the UE via a random access preamble within a random access opportunity indicated by the multicast control channel message request configuration within the system information.

[0265] Example 29: The method of Example 28, further comprising: transmitting a random access response message to the UE, wherein transmitting the multicast control channel message is based at least in part on receiving the random access response message.

[0266] Example 30: The method of any one of Examples 28 to 29, wherein the request is received via the random access preamble based at least in part on the system information including the multicast control channel message request configuration.

[0267] Example 31: The method of any one of Examples 27 to 30, wherein receiving the request for the multicast control channel message further comprises receiving the request via a radio resource control request message.

[0268] Example 32: The method of Example 31, wherein the radio resource control request message is included within a radio resource control connection request or within a payload of a first random access message of a two-step random access procedure.

[0269] Example 33: The method of any of Examples 31-32, wherein transmitting the multicast control channel message further comprises: transmitting the multicast control channel message by a radio resource control configuration message in response to the radio resource control request message.

[0270] Example 34: The method of any of Examples 31-33, wherein

[0271] the request is received by the radio resource control request message based at least in part on an absence of a multicast control channel message request configuration within the system information.

[0272] Example 35: The method of any of Examples 27-34, wherein: the system information indicates a multicast control channel message request configuration; and receiving the request further comprises receiving the request according to the multicast control channel message request configuration.

[0273] Example 36: The method of Example 35, wherein the multicast control channel message request configuration comprises at least one of an indication of a time period for transmitting the request by the UE or a resource for transmitting the request by the UE.

[0274] Example 37: The method of any of Examples 27-36, wherein transmitting the multicast control channel message further comprises: transmitting the multicast control channel message by a physical downlink control channel according to a multicast control channel message configuration.

[0275] Example 38: The method of Example 37, wherein transmitting the multicast control channel message by the physical downlink control channel further comprises: transmitting the multicast control channel message within a control resource set indicated by the system information.

[0276] Example 39: The method of any of Examples 37-38, wherein the control resource set is associated with a monitoring time window, a monitoring time period, a monitoring offset, or a combination thereof.

[0277] Example 40: The method of any of Examples 27-39, wherein: the multicast control channel message is a first multicast control channel message; and the first multicast control channel message is associated with a first set of multicast service radio bearer configurations comprising at least the multicast service radio bearer configuration.

[0278] Example 41: The method of Example 40, further comprising: transmitting a second multicast control channel message associated with a second set of multicast service radio bearer configurations, wherein one of the first set of multicast service radio bearer configurations or the second set of multicast service radio bearer configurations is delay sensitive.

[0279] Example 42: The method of any of Examples 27 to 41, wherein: receiving the request for the multicast control channel message is based at least in part on the system information indicating that the multicast control channel message is to be transmitted on-demand.

[0280] Example 43: The method of any of Examples 27 to 42, further comprising: determining a service group associated with the multicast traffic, wherein transmitting the multicast control channel message is based at least in part on the determined service group.

[0281] Example 44: The method of Example 43, wherein determining the service group further comprises: determining a service group identifier associated with the service group based at least in part on a multicast service radio bearer context or a multicast broadcast service identifier.

[0282] Example 45: The method of any of Examples 27 to 44, wherein the multicast control channel message comprises both an on-demand multicast control channel message and a periodic multicast control channel message.

[0283] Example 46: The method of any of Examples 27 to 45, wherein: transmitting the system information is based at least in part on: a UE performing a cell reselection procedure, a UE performing a cell selection procedure, a UE performing a handover procedure, a change associated with the multicast control channel message, or a combination thereof.

[0284] Example 47: The method of any of Examples 27 to 46, wherein the multicast control channel message configuration comprises at least one of an indication of a search space associated with the multicast control channel message or a time period for receiving the multicast control channel message.

[0285] Example 48: The method of any of Examples 27 to 47, wherein: the multicast service radio bearer is configured as a multicast / broadcast service radio bearer configuration; and the multicast traffic is multicast / broadcast traffic.

[0286] Example 49: The method of any of Examples 27 to 48, wherein the multicast control channel message configuration comprises an indication of: a repetition period of the multicast control channel message, an identifier associated with the multicast traffic, one or more time slots associated with the multicast control channel message, a modification period associated with the multicast control channel message, a new service start, or a combination thereof.

[0287] Example 50: An apparatus for wireless communication at a UE, comprising at least one means for performing a method of any of Examples 1 to 26.

[0288] Example 51: An apparatus for wireless communication at a UE, comprising a processor; memory coupled to the processor; and instructions stored in the memory and executable by the processor to implement a method of any of examples 1-26.

[0289] Example 52: A non-transitory computer-readable medium storing code for wireless communication at a UE, the code comprising instructions executable by a processor to perform a method of any of examples 1-26.

[0290] Example 53: An apparatus for wireless communication at a base station comprising at least one means for performing a method of any of examples 27-49.

[0291] Example 54: Example 43: An apparatus for wireless communication at a base station, comprising a processor; memory coupled to the processor; and instructions stored in the memory and executable by the processor to implement a method of any of examples 27-49.

[0292] Example 55: A non-transitory computer-readable medium storing code for wireless communication at a base station, the code comprising instructions executable by a processor to perform a method of any of examples 27-49.

[0293] Although aspects of an LTE, LTE-A, LTE-A Pro, or NR system can be described for purposes of example, and LTE, LTE-A, LTE-A Pro, or NR terminology can be used in much of the description, aspects of the described techniques can be applicable to other communication systems including 5thGeneration (5G) networks and / or other non-LTE, non-NR networks including Ultra Mobile Broadband (UMB), Institute of Electrical and Electronics Engineers (IEEE) 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, Flash-OFDM, and others.

[0294] Information and signals described herein can be represented using any of a variety of different technologies and techniques. For example, data, instructions, commands, information, signals, bits, symbols, and chips that can be referenced throughout the description can be represented by voltages, currents, electromagnetic waves, magnetic fields or particles, optical fields or particles, or any combination thereof.

[0295] The various illustrative blocks and components described herein can be implemented or performed with a general-purpose processor, a DSP, an ASIC, a CPU, a FPGA or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general-purpose processor can be a microprocessor, but in the alternative, the processor can be any processor, controller, microcontroller, or state machine. A processor can also be implemented as a combination of computing devices (e.g., a combination of a DSP and a microprocessor, multiple microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration).

[0296] The functions described herein can be implemented in hardware, software executed by a processor, firmware, or any combination thereof. If implemented in software executed by a processor, the functions can be stored on or transmitted over as one or more instructions or code on a computer-readable medium. Other examples and implementations are within the scope of the disclosure and appended claims. For example, due to the nature of software, functions described herein can be implemented using software executed by a processor, hardware, firmware, hardwiring, or combinations of any of these. Features implementing functions can also be physically located at various positions, including being distributed such that portions of functions are implemented at different physical locations.

[0297] Computer-readable media includes both non-transitory computer storage media and communication media including any medium that facilitates transfer of a computer program from one place to another. A non-transitory storage medium can be any available medium that can be accessed by a general purpose or special purpose computer. By way of example, and not limitation, non-transitory computer-readable media can comprise RAM, ROM, electrically erasable programmable ROM (EEPROM), flash memory, compact disk (CD) ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other non-transitory medium that can be used to carry or store desired program code means in the form of instructions or data structures and that can be accessed by a general-purpose or special-purpose computer, or a general-purpose or special-purpose processor. Also, any connection is properly termed a computer-readable medium. For example, if the software is transmitted from a website, server, or other remote source using a coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL), or wireless technologies such as infrared, radio, and microwave, then the coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwave are included in the definition of computer-readable medium. Disk and disc, as used herein, include CD, laser disc, optical disc, digital versatile disc (DVD), floppy disk and Blu-ray disc where disks usually reproduce data magnetically, while discs reproduce data optically with lasers. Combinations of the above are also included within the scope of computer-readable media.

[0298] As used herein, including in the claims “or” as used in a list of items (for example, a list of items prefaced by a term such as “at least one of’ or “one or more of’) indicates an inclusive list such that, for example, a list of at least one of A, B, or C means A or B or C or AB or AC or BC or ABC (i.e., A and B and C). Also, as used herein, the phrase “based on” shall not be construed as a reference to a closed set of conditions. For example, an example step that is described as “based on condition A” can be based on both a condition A and a condition B without departing from the scope of the present disclosure. In other words, as used herein, the phrase “based on” shall be construed in the same manner as the phrase “based at least in part on.”

[0299] In the drawings, like reference numerals can be used to denote similar components throughout the several views. Further, various components of the same type can be distinguished by following the convention of placing the primary reference number designating the component, followed by the hundreds digit, which denotes the specific drawing figure in which that component is first introduced, followed by a dashed line. If, in addition, a second digit appears after the hundreds digit, it designates the specific instance of the component in the figure. Thus, for instance, a second instance of a component first introduced in FIG. 1A can be designated R50, as in FIG. IB.

[0300] The description set forth herein, in connection with the appended drawings, describes example configurations and does not represent all the examples that can be implemented or that are within the scope of the claims. The term “example” used herein means “serving as an example, instance, or illustration,” and not “preferred” or “superior” over other examples. The detailed description includes specific details for the purpose of providing an understanding of the described techniques. These techniques, however, can be practiced without these specific details. In some instances, well-known structures and devices are shown in block diagram form in order to avoid obscuring the concepts of the described examples.

[0301] The description herein is presented to enable any person skilled in the art to make or use the present disclosure. Various modifications to the disclosure will be readily apparent to those skilled in the art, and the generic principles defined herein can be applied to other variations without departing from the scope of the disclosure. Thus, the present disclosure is not to be limited to the examples and designs described herein but is to be accorded the broadest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for wireless communication at a user equipment (UE), comprising: receiving system information from a network device, the system information indicating a multicast control channel message configuration and a multicast control channel message request configuration; transmitting a request for a multicast control channel message to the network device according to the multicast control channel message request configuration indicated in the system information after receiving the system information; receiving the multicast control channel message according to the multicast control channel message configuration and in response to transmission of the request, wherein the multicast control channel message indicates a multicast service radio bearer configuration; as well as Multicast traffic is received from the network device according to the multicast service radio bearer configuration.

2. The method of claim 1 , wherein transmitting the request for the multicast control channel message further comprises: determining, based at least in part on the system information including the multicast control channel message request configuration, that the request is to be transmitted via a random access preamble; transmitting the request to the network device via the random access preamble within a random access opportunity indicated by the multicast control channel message request configuration within the system information; as well as A random access response message is received from the network device, wherein receiving the multicast control channel message is based at least in part on receiving the random access response message.

3. The method of claim 1 , wherein transmitting the request for the multicast control channel message further comprises: The request is transmitted by a radio resource control request message, wherein the radio resource control request message is included in a payload of a radio resource control system information request, a radio resource control multicast control channel request, or a first random access message in a two-step random access procedure.

4. The method of claim 3, wherein: Receiving the multicast control channel message further includes receiving the multicast control channel message through a radio resource control configuration message in response to the radio resource control request message.

5. The method of claim 1, wherein: The system information indicates that the multicast control channel message request configuration includes at least one of an indication of a time period for transmitting the request or resources for transmitting the request; and Transmitting the request further comprises transmitting the request according to the multicast control channel message request configuration.

6. The method of claim 1, further comprising: monitoring a physical downlink control channel for the multicast control channel message according to the multicast control channel message configuration, wherein receiving the multicast control channel message is based at least in part on monitoring the physical downlink control channel; and A control resource set of the physical downlink control channel indicated by the system information is monitored, wherein the control resource set is associated with a monitoring time window, a monitoring period, a monitoring offset, or a combination thereof.

7. The method of claim 1, wherein the multicast control channel message is associated with a delay-sensitive multicast service radio bearer configuration set including the multicast service radio bearer configuration.

8. The method of claim 1, wherein: The multicast control channel message is associated with a delay-insensitive multicast service radio bearer configuration set; and The multicast service radio bearer configuration set includes the multicast service radio bearer configuration.

9. The method of claim 1, wherein: Transmitting the request for the multicast control channel message is based at least in part on the system information indicating that the multicast control channel message is to be received on demand.

10. The method of claim 1, further comprising: determining a service group associated with the multicast traffic, wherein receiving the multicast control channel message is based at least in part on the determined service group; as well as A service group identifier associated with the service group is determined based at least in part on a multicast service radio bearer context or a multicast broadcast service identifier.

11. The method of claim 1, wherein the multicast control channel message comprises both an on-demand multicast control channel message and a periodic multicast control channel message.

12. The method of claim 1, further comprising: performing a cell reselection procedure from a first network device to a second network device, wherein the network device is the first network device; determining that the second network device transmits the multicast traffic according to the multicast service radio bearer configuration based at least in part on a same area identifier associated with a first multicast control channel message and a second multicast control channel message associated with the second network device, wherein the multicast control channel message is the first multicast control channel message; as well as A determination is made to refrain from monitoring the system information from the second network device based at least in part on a determination that the second network device transmits the multicast traffic according to the multicast service radio bearer configuration, wherein the system information includes an indication of the same area identifier.

13. The method of claim 1, further comprising: determining to perform a cell reselection procedure from a first network device, wherein the network device is a second network device; receiving an initial multicast control message from the first network device based at least in part on determining to perform the cell reselection procedure; determining, based at least in part on the initial multicast control message, that the second network device transmits the multicast traffic; as well as The cell reselection procedure is performed from the first network device to the second network device based at least in part on determining that the second network device transmits the multicast traffic, wherein receiving the system information is based at least in part on performing the cell reselection procedure.

14. The method of claim 1, wherein: Receiving the system information is based at least in part on the UE performing a cell reselection procedure, the UE performing a cell selection procedure, the UE performing a handover procedure, a change associated with the multicast control channel message, or a combination thereof.

15. The method of claim 1 , wherein the multicast control channel message configuration comprises an indication of a search space associated with the multicast control channel message, a time period for receiving the multicast control channel message, a repetition period of the multicast control channel message, an identifier associated with the multicast traffic, one or more time slots associated with the multicast control channel message, a modification period associated with the multicast control channel message, a new service start, or a combination thereof.

16. The method of claim 1, wherein: The multicast service radio bearer configuration is a multicast / broadcast service radio bearer configuration; and The multicast traffic is multicast / broadcast traffic.

17. A method for wireless communication at a network device, comprising: transmitting system information to a user equipment (UE), the system information indicating a multicast control channel message configuration and a multicast control channel message request configuration; receiving a request for a multicast control channel message from the UE according to the multicast control channel message request configuration indicated in the system information after transmitting the system information; transmitting the multicast control channel message according to the multicast control channel message configuration and in response to receiving the request, wherein the multicast control channel message indicates a multicast service radio bearer configuration; and Multicast traffic is transmitted to the UE according to the multicast service radio bearer configuration.

18. The method of claim 17, wherein receiving the request for the multicast control channel message further comprises: Based at least in part on the system information including the multicast control channel message request configuration within the system information, the request is received from the UE via a random access preamble within a random access opportunity indicated by the multicast control channel message request configuration.

19. The method of claim 18, further comprising: A random access response message is transmitted to the UE, wherein transmitting the multicast control channel message is based at least in part on transmitting the random access response message.

20. The method of claim 17, wherein receiving the request for the multicast control channel message further comprises: The request is received via a radio resource control request message, wherein the radio resource control request message is included within a radio resource control connection request or within a payload of a first random access message in a two-step random access procedure.

21. The method of claim 20, wherein: Transmitting the multicast control channel message further includes transmitting the multicast control channel message through a radio resource control configuration message in response to the radio resource control request message.

22. The method of claim 17, wherein: The system information indicates that the multicast control channel message request configuration includes at least one of an indication of a time period for transmitting the request by the UE or resources for transmitting the request by the UE; and Receiving the request further includes receiving the request according to the multicast control channel message request configuration.

23. The method of claim 17, wherein transmitting the multicast control channel message further comprises: transmitting the multicast control channel message via a physical downlink control channel according to the multicast control channel message configuration; as well as The multicast control channel message is transmitted over the physical downlink control channel within a control resource set indicated by the system information, wherein the control resource set is associated with a monitoring time window, a monitoring period, a monitoring offset, or a combination thereof.

24. The method of claim 17, wherein: The multicast control channel message is a first multicast control channel message; and The first multicast control channel message is associated with a first multicast service radio bearer configuration set including at least the multicast service radio bearer configuration.

25. The method of claim 24, further comprising: A second multicast control channel message associated with a second multicast service radio bearer configuration set is transmitted, wherein one of the first multicast service radio bearer configuration set or the second multicast service radio bearer configuration set is delay sensitive.

26. The method of claim 17, wherein: Receiving the request for the multicast control channel message is based at least in part on the system information indicating that the multicast control channel message is to be transmitted on demand.

27. The method of claim 17, further comprising: determining a service group associated with the multicast traffic, wherein transmitting the multicast control channel message is based at least in part on the determined service group; as well as A service group identifier associated with the service group is determined based at least in part on a multicast service radio bearer context or a multicast broadcast service identifier.

28. The method of claim 17, wherein: Transmitting the system information is based at least in part on the UE performing a cell reselection procedure, the UE performing a cell selection procedure, the UE performing a handover procedure, a change associated with the multicast control channel message, or a combination thereof.

29. An apparatus for wireless communication at a user equipment (UE), comprising: means for receiving system information from a network device, the system information indicating a multicast control channel message configuration and a multicast control channel message request configuration; means for transmitting a request for a multicast control channel message to the network device according to the multicast control channel message request configuration indicated in the system information after receiving the system information; means for receiving the multicast control channel message in accordance with the multicast control channel message configuration and in response to transmission of the request, wherein the multicast control channel message indicates a multicast service radio bearer configuration; as well as Means for receiving multicast traffic from the network device according to the multicast service radio bearer configuration.

30. A device for wireless communication at a network device, comprising: means for transmitting system information to a user equipment (UE), the system information indicating system information of a multicast control channel message configuration and a multicast control channel message request configuration; means for receiving a request for a multicast control channel message from the UE according to the multicast control channel message request configuration indicated in the system information after transmitting the system information; means for transmitting the multicast control channel message in accordance with the multicast control channel message configuration and in response to receipt of the request, wherein the multicast control channel message indicates a multicast service radio bearer configuration; as well as means for transmitting multicast traffic to the UE according to the multicast service radio bearer configuration.

31. An apparatus for wireless communication at a user equipment (UE), comprising: one or more processors; a memory coupled to the one or more processors; as well as Instructions stored in the memory, wherein the instructions are executable by the one or more processors to cause the apparatus to perform the method according to any one of claims 1 to 16.

32. An apparatus for wireless communication at a network device, comprising: one or more processors; a memory coupled to the one or more processors; as well as Instructions stored in the memory, wherein the instructions are executable by the one or more processors to cause the apparatus to perform the method according to any one of claims 17 to 28.

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