Patent Description:
The latency of the network links between the UE, base station, and other network entities can slow communication through the network as data traverses each network entity before reaching a destination. For example, data communicated between two UEs may travel from one UE through a base station and core network before reaching another base station and the other UE, resulting in network latency. Several solutions have been developed to improve network latency. However, with recent advancements in wireless communication systems, such as Fifth Generation New Radio (<NUM> NR), new approaches may be available.

<CIT> relates to a method of allocating resources in a mobile telecommunications system. The method comprises: allocating first resources for a first terminal to communicate via a relay node for a device-to-device communication; allocating second resources for a second terminal to communicate via the relay node for the device-to-device communication; notifying the first terminal of the allocated first resources; notifying the second terminal of the allocated second resources; and the first and second terminals exchanging messages for the device-to-device communication via the relay node and using the first and second resources, respectively.

<CIT> discloses a method detecting a sidelink type of a receiving UE by the transmitting UE and the determination of the resources for the direct communication.

<CIT> discloses a method for relay communication in which the relay mode configuration is received directly from the base station.

This document describes methods and apparatuses for dual connectivity with secondary cell-user equipment according to the claims.

The details of one or more aspects of dual connectivity with secondary cell-user equipment are described below. The use of the same reference numbers in different instances in the description and the figures indicate similar elements:.

The invention claimed makes reference to <FIG> and <FIG>. The other examples in the detailed description are meant as useful examples to understand the invention. In conventional wireless communication systems, latency of the network links between the UE, base station, and other network entities can slow communication through the network as data traverses various links between each network entity before reaching a destination. For example, data communicated between two UEs may travel from one UE through a base station and core network before reaching the other UE, resulting in network latency. For time sensitive communications, such as telemetry information, sensor data, or other real-time application data, this network-related latency can degrade performance of the applications that rely on the timing of these communications.

This document describes aspects of dual connectivity with secondary cell-user equipment, which may be implemented to form a base station-user equipment dual connectivity BUDC group or BUDC set between multiple UEs. Generally, the BUDC group includes at least two UEs that communicate through a secondary connection (e.g., a radio access technology (RAT) connection), such as to communicate data packets through a secondary cell provided by one of the UEs. Because the data is communicated with or through the secondary cell-UE of the BUDC group (thereby avoiding base stations and core network), the secondary cell enables low latency communication among the UEs of the BUDC group.

For example, a base station serving as a primary cell can form a BUDC group by configuring a user equipment as a secondary cell-user equipment (SC-UE) to provide a secondary cell. The base station can also grant or assign resources of an air interface for use by the SC-UE to schedule communications of UEs assigned to the BUDC group. The base station and/or SC-UE can then add other UEs to the BUDC group to enable the other UEs to communicate with the SC-UE through the secondary cell. By so doing, the SC-UE can communicate data directly with the other UEs of the BUDC group without communicating through a base station, which decreases latency of communications between the UEs of the BUDC group. As another example, consider UEs configured as respective vehicle computing systems can be added to a BUDC group to enable low latency communication among the UEs. Using the secondary cell of the BUDC group, the UEs can communicate directly (e.g., with the SC-UE or relayed through the SC-UE) to share time sensitive information, such as sensor data or telemetry information, without the latency typically associated with the primary cell and other network entities of a wireless network.

In some aspects, a method performed by a UE configured as a secondary cell-user equipment (SC-UE) for a BUDC group includes receiving, from a base station serving as a primary cell, configuration information for the BUDC group. The method also includes admitting another UE associated with the base station to the BUDC group. The UE schedules, for the other UE, resources of an air interface for communication in a secondary cell provided by the UE for the BUDC group. The UE then communicates data with the other UE of the BUDC group using the scheduled resources of the air interface for communication in the secondary cell.

In other aspects, a method performed by a base station acting as a primary cell to establish a BUDC group for multiple UEs includes selecting a first UE to serve as a SC-UE for the BUDC group. The method also includes granting resources of an air interface to the first UE for use by UEs of the BUDC group to communicate in a secondary cell provided by the first UE. The base station then configures a second UE for addition of the second UE to the BUDC group effective to enable the second UE to communicate with the first UE through the secondary cell. The method further includes communicating, as the primary cell, control-plane information or data with the first UE or the second UE of the BUDC group.

In further aspects, a first user equipment includes a radio frequency (RF) transceiver, as well as a processor and memory system coupled to the RF transceiver. The memory system stores instructions of the first UE that are executable by the processor to direct the first UE to receive, from a base station acting as a primary cell, configuration information for a BUDC group. The first UE is also directed to admit a second UE associated with the base station to the BUDC group. The first UE then schedules, for the second UE, resources of an air interface for communication in a secondary cell provided by the first UE for the BUDC group. The instructions are also executable to communicate data with the second UE of the BUDC group using the scheduled resources of the air interface for communication in the secondary cell.

<FIG> illustrates an example operating environment <NUM> in which various aspects of dual connectivity with secondary cell-user equipment can be implemented. Generally, the example environment <NUM> includes multiple user equipment <NUM> (UE <NUM>), illustrated as UE <NUM>, UE <NUM>, and UE <NUM> of a base station-user equipment dual connectivity (BUDC) group. Each UE <NUM> can communicate with base stations <NUM> (illustrated as base stations <NUM>, <NUM>, <NUM>, and <NUM>) through wireless communication links <NUM> (wireless link <NUM>), illustrated as wireless links <NUM> and <NUM>. Each UE <NUM> in a BUDC group can also communicate with other UE <NUM> of the BUDC group through one or more wireless communication links which are illustrated as wireless links <NUM>, <NUM>, and <NUM>. In some aspects, the wireless links <NUM>, <NUM>, or <NUM> are implemented as a radio access technology connection (e.g., Fifth Generation (<NUM>) or Sixth Generation (<NUM>)) through licensed, unlicensed, or shared frequency spectrum, such as Citizens Band Radio Service (CBRS). The wireless links <NUM>, <NUM>, and <NUM> may enable data-plane (or user-plane) communications among the UE <NUM> of the BUDC group, such as data packet traffic or communication across packet data convergence protocol (PDCP), radio link control (RLC), and medium access control (MAC) layers of the user-plane (e.g., up to layer-<NUM>).

Alternately or additionally, a UE <NUM> of a BUDC group can also communicate with another UE <NUM> through other wireless connections, such as local wireless network connections (not shown). The local wireless network connections of the UEs <NUM> can be implemented as any suitable type of wireless connection or link, such as a millimeter wave (mmWave) link, sub-millimeter wave (sub-mmWave) link, free space optical (FSO) link, wireless local access network (WLAN), wireless personal area network (WPAN), near-field communication (NFC), Bluetooth™, ZigBee™, radar, lidar, sonar, ultrasonic, or the like. In some aspects, the UE <NUM> of the BUDC group can discover, identify, or add a candidate UE <NUM> to the BUDC by communicating with the candidate UE through a local wireless network connection (e.g., WLAN or Bluetooth™).

In this example, the UE <NUM> is implemented as a smartphone. Although illustrated as a smartphone, the UE <NUM> may be implemented as any suitable computing or electronic device, such as a smart watch, mobile communication device, modem, cellular phone, gaming device, navigation device, media device, laptop computer, desktop computer, tablet computer, smart appliance, vehicle-based communication system, vehicle telemetry system, traffic monitoring/control equipment, an Internet-of-things (IoT) device (e.g., sensor node, controller/actuator node, combination thereof), and the like. The base stations <NUM> (e.g., an Evolved Universal Terrestrial Radio Access Network Node B, E-UTRAN Node B, evolved Node B, eNodeB, eNB, Next Generation Node B, gNode B, gNB, or the like) may be implemented in a primary cell, macrocell, microcell, small cell, picocell, or the like, or any combination thereof.

In some aspects, a base station <NUM> selects UEs <NUM> and provides configuration information to the UEs <NUM> in order to establish the BUDC group. The base station can also manage membership of the BUDC group (e.g., add or remove LTEs) or grant resources to the BUDC group to enable wireless links between the UEs <NUM>. For example, the base station <NUM> can assign or grant (e.g., semi-persistent scheduling) resources of an air interface to a secondary cell-user equipment (SC-UE) of the BUDC that provides a secondary cell for communication among the UEs of the BUDC group. The SC-UE can then schedule, from the assigned resources, uplink or downlink resources for the UEs of the BUDC group to communicate within the secondary cell.

The base stations <NUM> communicate with the UE <NUM> through the wireless links <NUM> and <NUM>, which may be implemented as any suitable type of wireless link. The wireless links <NUM> and <NUM> include control and data communication, such as downlink of data and control information communicated from the base stations <NUM> to the UE <NUM>, uplink of other data and control information communicated from the UE <NUM> to the base stations <NUM>, or both. The wireless links <NUM> may include one or more wireless links (e.g., radio links) or bearers implemented using any suitable communication protocol or standard, or combination of communication protocols or standards, such as 3rd Generation Partnership Project Long-Term Evolution (3GPP LTE), Fifth Generation New Radio (SGNR), Sixth Generation (<NUM>), and so forth. Multiple wireless links <NUM> may be aggregated in a carrier aggregation to provide a higher data rate for the UE <NUM>. Multiple wireless links <NUM> from multiple base stations <NUM> may be configured for Coordinated Multipoint (CoMP) communication with the UE <NUM>. Additionally, multiple wireless links <NUM> may be configured for single-RAT dual connectivity or multi-RAT dual connectivity (MR-DC). Each of these various multiple-link situations tends to increase the power consumption of the UE <NUM>.

The base stations <NUM> collectively form a Radio Access Network <NUM> (e.g., RAN, Evolved Universal Terrestrial Radio Access Network, E-UTRAN, <NUM> NR RAN or NR RAN). The RANs <NUM> are illustrated as an NR RAN <NUM> and an E-UTRAN <NUM>. The base stations <NUM> and <NUM> in the NR RAN <NUM> are connected to a Fifth Generation Core <NUM> (5GC <NUM>) network. The base stations <NUM> and <NUM> in the E-UTRAN <NUM> connect to an Evolved Packet Core <NUM> (EPC <NUM>). Alternately or additionally, the base station <NUM> may connect to both the 5GC <NUM> and EPC <NUM> networks.

The base stations <NUM> and <NUM> connect, at <NUM> and <NUM> respectively, to the 5GC <NUM> through an NG2 interface for control-plane signaling and using an NG3 interface for user-plane data communications. The base stations <NUM> and <NUM> connect, at <NUM> and <NUM> respectively, to the EPC <NUM> using an S1 interface for control-plane signaling and user-plane data communications. Optionally or additionally, if the base station <NUM> connects to the 5GC <NUM> and EPC <NUM> networks, the base station <NUM> connects to the 5GC <NUM> using an NG2 interface for control-plane signaling and through an NG3 interface for user-plane data communications, at <NUM>.

In addition to connections to core networks, the base stations <NUM> may communicate with each other. For example, the base stations <NUM> and <NUM> communicate through an Xn interface at <NUM> and the base stations <NUM> and <NUM> communicate through an X2 interface at <NUM> to exchange user-plane and control-plane data. The interface or link at <NUM> or <NUM> between the base stations <NUM> can be implemented as any suitable type of link, such as a mmWave link, a sub-mmWave link, or a FSO link. At least one base station <NUM> (base station <NUM> and/or base station <NUM>) in the NR RAN <NUM> can communicate with at least one base station <NUM> (base station <NUM> and/or base station <NUM>) in the E-UTRAN <NUM> using an Xn interface <NUM>. In aspects, base stations <NUM> in different RANs (e.g., master base stations <NUM> of each RAN) communicate with one another using an Xn interface such as Xn interface <NUM>.

The 5GC <NUM> includes an Access and Mobility Management Function <NUM> (AMF <NUM>), which provides control-plane functions, such as registration and authentication of multiple UE <NUM>, authorization, and mobility management in the <NUM> NR network. The EPC <NUM> includes a Mobility Management Entity <NUM> (MME <NUM>), which provides control-plane functions, such as registration and authentication of multiple UE <NUM>, authorization, or mobility management in the E-UTRA network. The AMF <NUM> and the MME <NUM> communicate with the base stations <NUM> in the RANs <NUM> and also communicate with multiple UE <NUM>, using the base stations <NUM>.

<FIG> illustrates an example device diagram <NUM> of the user equipment <NUM> and base stations <NUM>. Each of the UEs <NUM> is capable of serving as an SC-UE which will be described further. Generally, the device diagram <NUM> describes network entities that can implement various aspects of dual connectivity with secondary cell-user equipment. <FIG> shows respective instances of the UEs <NUM> and the base stations <NUM>. The UEs <NUM> or the base stations <NUM> may include additional functions and interfaces that are omitted from <FIG> for the sake visual brevity. The UE <NUM> includes antennas <NUM>, a radio frequency front end <NUM> (RF front end <NUM>), and radio-frequency transceivers that include an LTE transceiver <NUM>, a <NUM> NR transceiver <NUM>, and a <NUM> transceiver <NUM> for communicating with other UEs <NUM>, base stations <NUM> in the <NUM> RAN <NUM>, and/or the E-UTRAN <NUM>. The UE <NUM> includes one or more additional transceivers (e.g., local wireless network transceiver <NUM>) for communicating over one or more local wireless networks (e.g., WLAN, WPAN, Bluetooth™, NFC, Wi-Fi-Direct, IEEE <NUM>. <NUM>, ZigBee, Thread, mmWave, sub-mmWave, FSO, radar, lidar, sonar, ultrasonic) with at least one other UE of the BUDC group. The RF front end <NUM> of the UE <NUM> can couple or connect the LTE transceiver <NUM>, the <NUM> NR transceiver <NUM>, the <NUM> transceiver <NUM>, and the local wireless network transceiver <NUM> to the antennas <NUM> to facilitate various types of wireless communication.

The antennas <NUM> of the UE <NUM> may include an array of multiple antennas that are configured similar to or differently from each other. The antennas <NUM> and the RF front end <NUM> can be tuned to, and/or be tunable to, one or more frequency bands defined by the 3GPP LTE and <NUM> NR communication standards and implemented by the LTE transceiver <NUM>, and/or the <NUM> NR transceiver <NUM>. Additionally, the antennas <NUM>, the RF front end <NUM>, the LTE transceiver <NUM>, the 5GNR transceiver <NUM>, and/or the <NUM> transceiver <NUM> may be configured to support beamforming for the transmission and reception of communications with the base stations <NUM>. By way of example and not limitation, the antennas <NUM> and the RF front end <NUM> can be implemented for operation in sub-gigahertz bands, sub-<NUM> bands, and/or above <NUM> bands that are defined by the 3GPP LTE and <NUM> NR communication standards (e.g., <NUM>-<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, or <NUM> bands). In addition, the RF front end <NUM> can be tuned to, and/or be tunable to, one or more frequency bands defined and implemented by the local wireless network transceiver <NUM> to support transmission and reception of communications with other UEs in the BUDC group over a local wireless network.

The UE <NUM> includes sensors (not shown) that can be implemented to detect various properties such as temperature, orientation, acceleration, proximity, distance, supplied power, power usage, battery state, or the like. As such, the sensors of the UE <NUM> may include any one or a combination of accelerometers, gyros, depth sensors, distance sensors, temperature sensors, thermistors, battery sensors, and power usage sensors. In various aspects, the UE <NUM> can collect and share data (e.g., vehicle telemetry) from sensors with another UE of the BUDC group, such as a secondary cell-user equipment that is configured to provide the secondary cell for the BUDC group.

The UE <NUM> also includes processor(s) <NUM> and computer-readable storage media <NUM> (CRM <NUM>). The processor <NUM> may be a single core processor or a multiple core processor implemented with a homogenous or heterogenous core structure. The computer-readable storage media described herein excludes propagating signals. CRM <NUM> may include any suitable memory or storage device such as random-access memory (RAM), static RAM (SRAM), dynamic RAM (DRAM), non-volatile RAM (NVRAM), read-only memory (ROM), or Flash memory useable to store device data <NUM> of the UE <NUM>. The device data <NUM> includes user data, multimedia data, beamforming codebooks, applications, and/or an operating system of the UE <NUM>, which are executable by processor(s) <NUM> to enable user-plane communication, control-plane signaling, and user interaction with the UE <NUM>.

In aspects of dual connectivity with secondary cell-user equipment, the CRM <NUM> of the UE <NUM> may also include a secondary cell manager <NUM> and secondary cell data <NUM>. Alternately or additionally, the secondary cell manager <NUM> may be implemented in whole or part as hardware logic or circuitry integrated with or separate from other components of the UE <NUM>. Generally, the secondary cell manager <NUM> of the UE <NUM> can form or manage a BUDC group of UEs <NUM> for which the UE <NUM> provides a secondary cell. A base station <NUM>, serving a primary cell to which the UE <NUM> is associated, can assign or grant the secondary cell manager <NUM> resources of an air interface for use in the secondary cell. The secondary cell manager <NUM> can then schedule the resources of the air interface for use by the UEs <NUM> of the BUDC group to communicate in the secondary cell. In aspects, secondary cell-user equipment facilitates data-plane communication for the UEs <NUM> of the BUDC group through this secondary cell.

The secondary cell data <NUM> may include data received from other UEs <NUM> of the BUDC group, which may be transmitted to the base station <NUM> or another UE <NUM> of the BUDC group. For example, a UE <NUM> serving as a secondary cell-user equipment can receive, aggregate, forward, and/or route data packets among the UEs <NUM> of the BUDC group through the secondary cell to enable low latency communication. With respect to the primary cell, the base station <NUM> provides control-plane signaling or information and data-plane (or user-plane) communication to one or more of the UEs through a connection with the primary cell. Alternately or additionally, the secondary cell manager <NUM> may use the local wireless network transceiver <NUM> to discover or add other UEs to the BUDC group. The implementations and uses of the secondary cell manager <NUM> vary and are described throughout the disclosure.

Aspects and functionalities of the UE <NUM> may be managed by operating system controls presented through an application programming interface (API). In some aspects, the secondary cell manager <NUM> accesses an API or an API service of the UE <NUM> to control aspects and functionalities of the user equipment or transceivers thereof. For example, the secondary cell manager <NUM> can access or utilize the LTE transceiver <NUM>, <NUM> NR transceiver <NUM>, <NUM> transceiver <NUM>, or local wireless network transceiver <NUM> to coordinate with a base station <NUM> or other UEs <NUM> to form and manage a BUDC group for which the UE <NUM> provides a secondary cell for low latency communication. The CRM <NUM> may also include a communication manager (not shown) to manage or provide an interface for communicative functions of the UE <NUM>. The communication manager may also be implemented in whole or part as hardware logic or circuitry integrated with or separate from other components of the UE <NUM>. In at least some aspects, the communication manager configures the RF front end <NUM>, the LTE transceiver <NUM>, the <NUM> NR transceiver <NUM>, <NUM> transceiver <NUM>, and/or the local wireless network transceiver <NUM> to implement the techniques of dual connectivity with secondary cell-user equipment as described herein.

The device diagram for the base stations <NUM>, shown in <FIG>, includes a single network node (e.g., a gNode B). The functionality of the base stations <NUM> may be distributed across multiple network nodes or devices and may be distributed in any fashion suitable to perform the functions described herein. The base stations <NUM> include antennas <NUM>, a radio frequency front end <NUM> (RF front end <NUM>), one or more LTE transceivers <NUM>, one or more 5GNR transceivers <NUM>, and/or one or more <NUM> transceivers <NUM> for communicating with the UE <NUM>. The RF front end <NUM> of the base stations <NUM> can couple or connect the LTE transceivers <NUM>, the <NUM> NR transceivers <NUM>, and the <NUM> transceivers <NUM> to the antennas <NUM> to facilitate various types of wireless communication. The antennas <NUM> of the base stations <NUM> may include an array of multiple antennas that are configured similar to or differently from each other. The antennas <NUM> and the RF front end <NUM> can be tuned to, and/or be tunable to, one or more frequency bands defined by the 3GPP LTE and <NUM> NR communication standards, and implemented by the LTE transceivers <NUM>, the <NUM> NR transceivers <NUM>, and/or the <NUM> transceivers <NUM>. Additionally, the antennas <NUM>, the RF front end <NUM>, the LTE transceivers <NUM>, the 5GNR transceivers <NUM>, and/or <NUM> transceivers <NUM> may be configured to support beamforming, such as Massive-MIMO, for the transmission and reception of communications with any UE <NUM> in a BUDC group through a primary cell (e.g., cell provided by the base station <NUM>).

The base stations <NUM> also include processor(s) <NUM> and computer-readable storage media <NUM> (CRM <NUM>). The processor <NUM> may be a single core processor or a multiple core processor composed of a variety of materials, such as silicon, polysilicon, high-K dielectric, copper, and so on. CRM <NUM> may include any suitable memory or storage device such as random-access memory (RAM), static RAM (SRAM), dynamic RAM (DRAM), non-volatile RAM (NVRAM), read-only memory (ROM), or Flash memory useable to store device data <NUM> of the base stations <NUM>. The device data <NUM> includes network scheduling data, radio resource management data, beamforming codebooks, applications, and/or an operating system of the base stations <NUM>, which are executable by processor(s) <NUM> to enable communication with the UE <NUM>.

In aspects, the CRM <NUM> of the base station <NUM> also includes a base station-user equipment dual connectivity (BUDC) group coordinator <NUM> for forming and managing BUDC groups of UEs <NUM>. Alternately or additionally, the BUDC group coordinator <NUM> may be implemented in whole or part as hardware logic or circuitry integrated with or separate from other components of the base station <NUM>. Generally, the BUDC group coordinator <NUM> enables the base station <NUM> to establish a BUDC group of UEs <NUM>, manage resources allocated to the BUDC group for a secondary cell, and manage UE membership of the BUDC group, such as by adding or removing UEs <NUM> from the BUDC group (or secondary cell). For example, the BUDC group coordinator can send layer-<NUM> messages to the SC-UE or a potential UE group member to configure, add, or remove that specific UE into or from the secondary cell of the BUDC group.

The BUDC group coordinator <NUM> of the base station <NUM> may also enable or configure a local wireless network connection between the UEs <NUM> of the BUDC group, such as to facilitate sharing of BUDC group information, encryption keys, resource scheduling information, or the like. For example, the BUDC group coordinator <NUM> may configure a local wireless network connection that is available for multiple UEs <NUM> of the BUDC group and then provide an indication of the configuration (e.g., channel, frequency, or network identifier) to at least one of the UEs <NUM>. By so doing, a UE acting as a SC-UE can coordinate resources or access to the secondary cell of the BUDC group through local wireless network connections with the other UEs.

CRM <NUM> also includes a base station manager <NUM>. Alternately or additionally, the base station manager <NUM> may be implemented in whole or part as hardware logic or circuitry integrated with or separate from other components of the base stations <NUM>. In at least some aspects, the base station manager <NUM> configures the LTE transceivers <NUM>, <NUM> NR transceivers <NUM>, and <NUM> transceiver <NUM> for communication with the UE <NUM>, as well as communication with a core network. The base stations <NUM> include an inter-base station interface <NUM>, such as an Xn and/or X2 interface, which the base station manager <NUM> configures to exchange user-plane and control-plane data between another base station <NUM>, to manage the communication of the base stations <NUM> with the UE <NUM>. The base stations <NUM> include a core network interface <NUM> that the base station manager <NUM> configures to exchange user-plane and control-plane data with core network functions and/or entities.

<FIG> illustrates an air interface resource at <NUM> that extends between user equipment and/or a base station through which various aspects dual connectivity with secondary cell-user equipment can be implemented. The air interface <NUM> may utilize licensed, unlicensed, or shared license radio spectrum (e.g., CBRS), in multiple frequency bands, to enable wireless links between UEs (secondary cell) or with a base station (primary cell) in accordance with <NUM>, <NUM>, or other communication standards. In aspects, a base station may grant or allocate a set of resources (e.g., through semi-persistent scheduling) to a SC-UE to be used for communications of a BUDC group secondary cell. For example, a SC-UE providing a secondary cell can schedule resources for other UEs of the BUDC group. Accordingly, granted resources or scheduled resources described herein may refer to frequency, time, or units of resources for an air interface, such as the air interface <NUM> described with reference to <FIG>.

The air interface resource <NUM> can be divided into resource units <NUM>, each of which occupies some intersection of frequency spectrum and elapsed time. A portion of the air interface resource <NUM> is illustrated graphically in a grid or matrix having multiple resource blocks <NUM>, including example resource blocks <NUM>, <NUM>, <NUM>, <NUM>. An example of a resource unit <NUM> therefore includes at least one resource block <NUM>. As shown, time is depicted along the horizontal dimension as the abscissa axis, and frequency is depicted along the vertical dimension as the ordinate axis. The air interface resource <NUM>, as defined by a given communication protocol or standard, may span any suitable specified frequency range, and/or may be divided into intervals of any specified duration. Increments of time can correspond to, for example, milliseconds (mSec). Increments of frequency can correspond to, for example, megahertz (MHz).

In example operations generally, the base stations <NUM> allocate portions (e.g., resource units <NUM>) of the air interface resource <NUM> for uplink and downlink communications. In aspects of dual connectivity, an SC-UE may also schedule resources of the air interface for UEs of the BUDC group for communication in a secondary cell. Alternately or additionally, a base station can provide control-plane signaling to configure and manage wireless links of the secondary cell. Each resource block <NUM> of network access resources may be allocated to support respective wireless communication links <NUM> of multiple user equipment <NUM>. In the lower left corner of the grid, the resource block <NUM> may span, as defined by a given communication protocol, a specified frequency range <NUM> and comprise multiple subcarriers or frequency sub-bands. The resource block <NUM> may include any suitable number of subcarriers (e.g., <NUM>) that each correspond to a respective portion (e.g., <NUM>) of the specified frequency range <NUM> (e.g., <NUM>). The resource block <NUM> may also span, as defined by the given communication protocol, a specified time interval <NUM> or time slot (e.g., lasting approximately one-half millisecond or <NUM> orthogonal frequency-division multiplexing (OFDM) symbols). The time interval <NUM> includes subintervals that may each correspond to a symbol, such as an OFDM symbol. As shown in <FIG>, each resource block <NUM> may include multiple resource elements <NUM> (REs) that correspond to, or are defined by, a subcarrier of the frequency range <NUM> and a subinterval (or symbol) of the time interval <NUM>. Alternatively, a given resource element <NUM> may span more than one frequency subcarrier or symbol. Thus, a resource unit <NUM> may include at least one resource block <NUM>, at least one resource element <NUM>, and so forth.

In example implementations, user equipment <NUM> (one of which is shown) are communicating with the base stations <NUM> (one of which is shown, e.g., primary cell) or another user equipment <NUM> (e.g., secondary cell) through access provided by portions of the air interface resource <NUM>. The base station manager <NUM> or secondary cell manager <NUM> (shown in <FIG>) may determine a respective data-rate, type of information, or amount of information (e.g., data or control information) to be communicated (e.g., transmitted) by the user equipment <NUM>. For example, the base station manager <NUM> (e.g. for the primary cell) or secondary cell manager <NUM> (e.g., for the secondary cell) can determine that each user equipment <NUM> is to transmit at a different respective data rate or transmit a different respective amount of information. The base station manager <NUM> or secondary cell manager <NUM> then allocates one or more resource blocks <NUM> to user equipment <NUM> of the BUDC group based on the determined data rate or amount of information.

Additionally, or in the alternative to block-level resource grants, the base station manager <NUM> or secondary cell manager <NUM> may allocate resource units at an element-level. Thus, the base station manager <NUM> may allocate one or more resource elements <NUM> or individual subcarriers to different user equipment <NUM>. By so doing, one resource block <NUM> can be allocated to facilitate network access for multiple user equipment <NUM>. Accordingly, the base station manager <NUM> or secondary cell manager <NUM> may allocate, at various granularities, one or up to all subcarriers or resource elements <NUM> of a resource block <NUM> to one user equipment <NUM> or divided across multiple user equipment <NUM>, thereby enabling higher network utilization or increased spectrum efficiency.

The base station manager <NUM> or secondary cell manager <NUM> can therefore allocate air interface resource <NUM> by resource unit <NUM>, resource block <NUM>, frequency carrier, time interval, resource element <NUM>, frequency subcarrier, time subinterval, symbol, spreading code, some combination thereof, and so forth. Based on respective allocations of resource units <NUM>, the base station manager <NUM> or secondary cell manager <NUM> can transmit respective messages to the multiple user equipment <NUM> indicating the respective allocation of resource units <NUM> to each user equipment <NUM>. Each message may enable a respective user equipment <NUM> to queue the information or configure the LTE transceiver <NUM>, the <NUM> NR transceiver <NUM>, and/or the <NUM> transceiver <NUM> to communicate via the allocated resource units <NUM> of the air interface resource <NUM>.

<FIG> illustrates an example environment at <NUM> in which a base station-user equipment dual connectivity (BUDC) group <NUM> is implemented in accordance with various aspects. In this example, connection with a radio access network is provided by the base station <NUM> as a primary cell and respective connections with other UEs are provided by a SC-UE <NUM> acting as a secondary cell. In other words, each of the UEs may have dual connectivity to the radio access network through the base station <NUM> (or another base station) as a primary cell (or master cell) and/or to other UEs of the BUDC group <NUM> through the SC-UE <NUM> as the secondary cell.

In this example, assume that base station <NUM>, as a primary cell, manages UEs <NUM> through <NUM> and maintains respective wireless links <NUM> and <NUM> of the primary cell to enable connection with the radio access network (not all primary cell connections are shown). To form the BUDC group <NUM>, the BUDC group coordinator <NUM> selects the UE <NUM> as the SC-UE <NUM> for the BUDC group. The BUDC group coordinator <NUM> of the base station <NUM> can then provide an SPS grant of resources to the SC-UE <NUM> for communication with other UEs <NUM> of the BUDC group <NUM>. For example, the SC-UE <NUM> can schedule the granted resources to subordinate UEs <NUM> of the BUDC group <NUM> for uplink or downlink data traffic in the secondary cell of the SC-UE <NUM>. By so doing, the SC-UE <NUM> can communicate data directly with the other UEs <NUM> of the BUDC group without communicating through the base station <NUM>, which decreases latency of communications among the UEs of the BUDC group. Using the secondary cell of the BUDC group, the UEs <NUM> can communicate directly (e.g., with the SC-UE or relayed through the SC-UE) to share time sensitive information, such as sensor data or telemetry information, without the latency typically associated with the primary cell and other network entities of a wireless network.

In some aspects of dual connectivity, the secondary cell manager <NUM> of the UE <NUM> can communicate with other UEs <NUM> of the BUDC in the secondary cell through the data-plane or layer-<NUM> messages. As such, the base station <NUM> may provide control-plane signaling or information for respective connections to support dual connectivity with the primary cell of the base station <NUM> and secondary cell implemented by an SC-UE of the BUDC group. Accordingly, the base station <NUM> and secondary cell manager <NUM> of the UE <NUM> may negotiate or coordinate when adding, removing, or managing other UEs <NUM> of the BUDC group.

<FIG> and <FIG> illustrate an example of data and control transactions at <NUM> between a base station and user equipment in accordance with aspects of dual connectivity with secondary cell-user equipment. The base station <NUM> and the UEs <NUM> through <NUM> may be implemented similar to the entities described with reference to <FIG>. Generally, the transactions of <FIG> and <FIG> are described in the context of the environment of <FIG> in which a base station <NUM> and SC-UE <NUM> provide dual connectivity through a primary cell and secondary cell, respectively. As such, the base station <NUM> and UE <NUM>, configured as the SC-UE <NUM>, may coordinate to form a BUDC group <NUM> in which the UEs <NUM> through <NUM> can communicate with the base station <NUM> or through the SC-UE <NUM> for low latency data communications.

At <NUM>, the UE <NUM> provides an indication to the base station <NUM> of capabilities to act or assume the role of SC-UE for a BUDC group <NUM>. The indication of capabilities may include an indication of any one or more of an available battery power, available processing power, available memory for BUDC group data, and/or communication capabilities, such as a transceiver configuration or radio capabilities.

At <NUM>, the base station <NUM> configures the UE <NUM> as the SC-UE <NUM> for the BUDC group <NUM>. The base station <NUM> may also grant resources of an air interface to the SC-UE <NUM> for the BUDC group, such as through a semi-persistent scheduling grant or assignment of the resources. In some cases, the base station <NUM> sends a layer-<NUM> message to configure the SC-UE <NUM> of the BUDC group. Alternately or additionally, the base station <NUM> can provide an encryption key for use by the UEs of the BUDC group for secure communications in a secondary cell.

At <NUM>, the base station <NUM> configures or negotiates, with the SC-UE <NUM>, the addition of UE <NUM> to the BUDC group of the SC-UE. The base station can select the UE <NUM> for the BUDC group based on one or more of a use profile of the UE (e.g., vehicle-based, sensor-enabled, user-based, and so on), an application of the UE (e.g., application layer communications with other UEs), a location of the UE, a proximity of the UE relative to the SC-UE, and/or a mobility state (e.g., high-mobility, medium-mobility, low-mobility, or normal-mobility state) of the UE. The base station can send a message to the SC-UE requesting addition of the UE <NUM> to the BUDC group, which the SC-UE may accept or decline, such as when available power or processing resources are constrained or insufficient to support SC-UE duties. Here, assume that the SC-UE accepts admission of the UE <NUM> to the BUDC group.

At <NUM>, the base station <NUM> configures the UE <NUM> for the BUDC group <NUM> and adds the UE <NUM> to the BUDC group for dual connectivity. In some aspects, the base station <NUM> sends a layer-<NUM> (e.g., Service Data Adaptation Protocol layer) message to the UE <NUM> to direct or request the UE to join the BUDC group. At <NUM>, the base station <NUM> and the SC-UE <NUM> exchange control-plane information or user-plane data through the primary cell of the base station <NUM>. As noted, the base station <NUM> can provide control-plane signaling and user-plane data for UEs of the BUDC group as the primary cell, and the SC-UE <NUM> can provide user-plane data communication for the UEs of the BUDC group as the secondary cell.

At <NUM>, the base station <NUM> configures or negotiates, with the SC-UE <NUM>, the addition of UE <NUM> to the BUDC group (or secondary cell) of the SC-UE. As described herein, the base station <NUM> can select UE <NUM> for addition to the BUDC group and request that the SC-UE accept the addition of the UE <NUM> to the BUDC group. At <NUM>, the base station <NUM> configures the UE <NUM> for the BUDC group <NUM> and adds the UE <NUM> to the BUDC group for dual connectivity. The base station <NUM> can send a layer-<NUM> message to the UE <NUM> to configure the UE <NUM> and/or direct the UE to join the BUDC group.

At <NUM>, the base station <NUM> configures or negotiates, with the SC-UE <NUM>, the addition of UE <NUM> to the BUDC group (or secondary cell) of the SC-UE. The base station <NUM> can select UE <NUM> for addition to the BUDC group and request that the SC-UE accept the addition of the UE <NUM> to the BUDC group. At <NUM>, the base station <NUM> configures the UE <NUM> for the BUDC group <NUM> and adds the UE <NUM> to the BUDC group for dual connectivity. The base station <NUM> can send a layer-<NUM> or layer-<NUM> message to the UE <NUM> to configure the UE <NUM> and/or direct the UE to join the BUDC group.

Continuing to <NUM> of <FIG>, the base station <NUM> and the UE <NUM> of the BUDC group exchange control-plane information or data through the primary cell of the base station <NUM> at <NUM>. As noted, the base station <NUM> can provide control-plane signaling and user-plane data for UEs of the BUDC group as the primary cell. At <NUM>, the SC-UE <NUM> broadcasts data to the member UEs <NUM> of the BUDC group, which in this example include the UE <NUM>, UE <NUM>, and UE <NUM>. The broadcast data may include aggregate data received from multiple UEs of the BUDC group (not shown), such as aggregate sensor information.

At <NUM>, the SC-UE <NUM> and the UE <NUM> of the BUDC group exchange unicast data. The unicast data may include data packets relayed or routed by the SC-UE from other UEs of the BUDC group. In some cases, the unicast data includes aggregate data collected from multiple other UEs of the BUDC group (not shown). At <NUM>, the SC-UE <NUM> and the UE <NUM> of the BUDC group exchange unicast data. Similarly, the unicast data may include data packets relayed or routed by the SC-UE from other UEs of the BUDC group.

At <NUM>, the base station <NUM> and the UE <NUM> of the BUDC group exchange control-plane information or data through the primary cell of the base station <NUM>. As noted, the base station <NUM> provides control-plane signaling and user-plane data for UEs of the BUDC group as the primary cell. At <NUM>, the SC-UE <NUM> and the UE <NUM> of the BUDC group exchange unicast data. At <NUM>, the base station <NUM> and the UE <NUM> of the BUDC group exchange control-plane information or data through the primary cell of the base station <NUM>.

<FIG> illustrates an example of transactions at <NUM> between a secondary cell-user equipment and other user equipment in accordance with aspects of dual connectivity with secondary cell-user equipment. The base station <NUM> and the UEs <NUM> through <NUM> may be implemented similar to the entities described with reference to <FIG>. Generally, the transactions of <FIG> are described in the context of the environment of <FIG> in which a base station <NUM> and SC-UE <NUM> provide dual connectivity through a primary cell and secondary cell, respectively.

At <NUM>, the UE <NUM> provides an indication to the base station <NUM> of capabilities to act or assume the role of SC-UE for a BUDC group <NUM>. This indication may include indicating that the UE <NUM> includes a secondary cell manager <NUM> for enabling SC-UE capabilities or providing the secondary cell for the BUDC group.

At <NUM>, the base station <NUM> configures the UE <NUM> as the SC-UE <NUM> for the BUDC group <NUM>. The base station <NUM> may grant resources of an air interface to the SC-UE <NUM> for the BUDC group or an encryption key for use in securing secondary cell communications among the UEs of the BUDC group.

At <NUM>, the SC-UE <NUM> adds the UE <NUM> to the BUDC group. The SC-UE <NUM> may coordinate the addition of the UE <NUM> through a local wireless network connection, such as a Bluetooth™ or WLAN connection. For example, the SC-UE may provide to the UE <NUM>, through the local wireless network connection, an identifier associated with the BUDC group or the encryption key for the secondary cell. At <NUM>, the SC-UE <NUM> notifies the base station <NUM> that the UE <NUM> was added to the BUDC group. At <NUM>, the base station <NUM> then configures the UE <NUM> for dual connectivity in the BUDC group. In some aspects, the base station <NUM> sends a layer-<NUM> message to the UE <NUM> to configure the UE <NUM> for operation in the BUDC group.

At <NUM>, the SC-UE <NUM> selects the UE <NUM> for addition to the BUDC group <NUM>. The SC-UE can select the UE <NUM> for addition to the BUDC group based on any one or more of a use profile of the UE, an application of the UE (e.g., application layer communication with other UEs), a location of the UE, a proximity of the UE with the SC-UE, and/or a mobility state of the UE. At <NUM>, the SC-UE <NUM> requests (or suggests), to the base station <NUM>, the addition of the UE <NUM> to the BUDC group. At <NUM>, the base station <NUM> configures the UE <NUM> for the BUDC group <NUM> and adds the UE <NUM> to the BUDC group for dual connectivity. The base station <NUM> can send a layer-<NUM> message to the UE <NUM> to configure the UE <NUM> and direct the UE <NUM> to join the BUDC group.

At <NUM>, the SC-UE <NUM> selects the UE <NUM> for addition to the BUDC group <NUM>. The SC-UE can select the UE <NUM> for addition to the BUDC group based on any suitable criteria, such as a location of the UE, a proximity of the UE with the SC-UE, and/or a mobility state of the UE. At <NUM>, the SC-UE <NUM> also requests (or suggests), to the base station <NUM>, the addition of the UE <NUM> to the BUDC group. At <NUM>, the base station <NUM> then configures the UE <NUM> for the BUDC group <NUM> and adds the UE <NUM> to the BUDC group for dual connectivity. In some cases, the base station <NUM> sends a layer-<NUM> message to the UE <NUM> to configure the UE <NUM> and direct the UE to join the BUDC group.

At <NUM>, the SC-UE <NUM> broadcasts data to the member UEs <NUM> of the BUDC group, which in this example include the UE <NUM>, UE <NUM>, and UE <NUM>. The broadcast data may include aggregate data received from multiple UEs of the BUDC group (not shown), such as aggregate sensor information that is useful to one or more of the member UEs of the BUDC group.

Example methods <NUM> through <NUM> are described with reference to <FIG> in accordance with one or more aspects of dual connectivity with secondary cell-user equipment. The order in which the method blocks are described are not intended to be construed as a limitation, and any number of the described method blocks can be skipped or combined in any order to implement a method or an alternate method. Generally, any of the components, modules, methods, and operations described herein can be implemented using software, firmware, hardware (e.g., fixed logic circuitry), manual processing, or any combination thereof. Some operations of the example methods may be described in the general context of executable instructions stored on computer-readable storage memory that is local and/or remote to a computer processing system, and implementations can include software applications, programs, functions, and the like. Alternatively, or additionally, any of the functionality described herein can be performed, at least in part, by one or more hardware logic components, such as, and without limitation, Field-programmable Gate Arrays (FPGAs), Application-specific Integrated Circuits (ASICs), Application-specific Standard Products (ASSPs), System-on-a-chip systems (SoCs), Complex Programmable Logic Devices (CPLDs), and the like.

<FIG> illustrates an example method <NUM> for forming a base station-user equipment dual connectivity (BUDC) group in accordance with one or more aspects. In some implementations, operations of the method <NUM> are performed by a BUDC group coordinator <NUM> of a base station <NUM>. Alternately or additionally, the operations of the method <NUM> can be implemented by or with other entities described herein, such as the secondary cell manager <NUM> of the UE <NUM>.

At <NUM>, a user equipment (UE) is selected to serve as a secondary cell-UE (SC-UE) for a BUDC group. The selection of the UE may be made based on an indication or information that the UE includes capabilities to serve as the SC-UE for the BUDC. For example, a base station may poll multiple UEs to determine which UEs of a primary cell are capable of serving or acting as the SC-UE. As such, the base station may receive an indication or information from a UE indicating that the UE includes SC-UE capabilities or has sufficient resources (e.g., battery capacity or processing power) available to act as the SC-UE. Alternately or additionally, the UE can be selected based on location, proximity, and/or mobility with respect to one or more candidate UEs for the BUDC group or the base station.

At <NUM>, resources of an air interface are granted to the SC-UE for use by UEs of the BUDC group for communication. By so doing, the base station can specify the frequency resources used by the SC-UE to communicate with other UEs of BUDC group. In some cases, the base station provides an SPS grant of the resources to the SC-UE, which can then use these resources to schedule communication with subordinate UEs in a secondary cell. The connection in the secondary cell between the SC-UE and other UEs of the BUDC group may use a <NUM> RAT or <NUM>. Alternately or additionally, the secondary connection may utilize a licensed frequency band, an unlicensed frequency band, and/or shared spectrum, such as CBRS.

At <NUM>, another UE is selected for addition to the BUDC group. The base station can select the UE for the BUDC group based on any one or more of a use profile of the UE, an application of the UE (e.g., application layer communication with other UEs), a location of the UE, a proximity of the UE with the SC-UE, and/or a mobility state of the UE. Alternately or additionally, the SC-UE of the BUDC group can also allow other UEs to enter the group, such as by autonomously allowing the UE or requesting that the base station add a particular UE as suggested by the SC-UE.

At <NUM>, the addition of the UE to the BUDC group is negotiated with the SC-UE of the BUDC group. For example, the base station can send a message to the SC-UE requesting addition of the selected UE to the BUDC group. The SC-UE may accept this request to add the UE to the BUDC group or decline the request, such as when available battery power of the SC-UE is limited, or processing resources of the SC-UE are taxed.

At <NUM>, the UE selected for addition to the BUDC group is configured based on the negotiation with the SC-UE. The base station can send a layer-<NUM> message to the selected UE to configure the selected UE and direct the UE to join the BUDC group. In some cases, the base station also provides an encryption key to the UE for use in secure communications in the secondary cell of the BUDC group. Optionally, from operation <NUM>, the method <NUM> may return to operation <NUM> to perform additional iterations in which one or more other UEs are added to the BUDC group.

Optionally at <NUM>, control information or data is communicated with the SC-UE or one of the UEs of the BUDC group. The communications between the base station and the SC-UE or UE may be uplink communications (i.e., transmission from the SC-UE and/or UE to the base station), downlink communications (i.e., transmission from the base station to the SC-UE and/UE), or both. As described herein, the control-plane for each dual-connectivity UE of the BUDC group may come from one or more base stations. With respect to the data-plane, the data-plane communications can come from the SC-UE (e.g., secondary cell) and/or the base stations (e.g., primary cell).

Optionally at <NUM>, one of the UEs is removed from the BUDC group. In some cases, the UE is selected for removal when membership of the BUDC group is reviewed or a state of the UE changes with respect to the BUDC group or the SC-UE. For example, the UE may be selected for removal responsive to a change in one of the location of the UE, the proximity of the UE with the SC-UE, or the mobility state of the UE. Alternately or additionally, the base station can send a layer-<NUM> message or layer-<NUM> message to the UE to direct the UE to leave the BUDC group.

<FIG> illustrates an example method <NUM> for admitting user equipment to a base station-user equipment dual connectivity (BUDC) group. In some aspects, operations of the method <NUM> are implemented by or with a secondary cell manager <NUM> of a UE <NUM>. Alternately or additionally, the operations of the method <NUM> can be implemented by other entities described herein, such as another UE or a base station associated with a BUDC group <NUM>.

At <NUM>, a UE provides in indication for secondary cell-user equipment (SC-UE) capability for a BUDC group. This indication may include indicating that the UE <NUM> includes a secondary cell manager <NUM> for enabling SC-UE capabilities or providing the secondary cell for the BUDC group.

At <NUM>, configuration information to serve as SC-UE for a BUDC group is received from a base station acting as a primary cell. In some cases, the base station provides an SPS grant of the resources to the SC-UE, which can then use these resources to schedule communication with subordinate UEs in a secondary cell. The connection in the secondary cell between the SC-UE and other UEs of the BUDC group may use a <NUM> RAT or <NUM>. Alternately or additionally, the secondary connection may utilize a licensed frequency band, an unlicensed frequency band, and/or shared spectrum, such as CBRS.

At <NUM>, a request is received from the base station to admit a UE to the BUDC group. The request may identify the UE that the base station has selected for addition to the BUDC group. Alternately or additionally, the SC-UE can also allow another UE to enter the group, such as by allowing the UE autonomously or requesting that the base station add a particular UE as suggested by the SC-UE.

Optionally at <NUM>, the SC-UE declines the request of the base station to admit the UE to the BUDC group. For example, the SC-UE may decline the request to add the UE in response to determining that the SC-UE lacks sufficient battery power or processing overhead to manage another UE in the BUDC group. Optionally at <NUM>, the SC-UE accepts the request of the base station to admit the UE to the BUDC group. To do so, the SC-UE may reply to the base station indicating acceptance of the request to add the UE to the BUDC group.

At <NUM>, resources of an air interface are scheduled for the UE admitted to the BUDC group. As described herein, the SC-UE can schedule, for the UE, uplink and/or downlink resources assigned to the SC-UE for communication in the secondary cell of the BUDC group. In some cases, the SC-UE also transmits synchronization pilots and other reference signals to enable the UE to synchronize with the SC-UE for communication in the secondary cell.

At <NUM>, the SC-UE communicates with the UE using the scheduled resources of the air interface in the secondary cell. The communications between the SC-UE and the UE may be uplink communications (i.e., transmission from the UE to the SC-UE), downlink communications (i.e., transmission from the SC-UE to the UE), or both. The secondary cell associated with the SC-UE may include a data radio bearer for each corresponding UE in the BUDC group. Generally, the SC-UE can perform up to layer-<NUM> messaging and communicate data packets for the UEs in the BUDC group. For example, the SC-UE can forward or send packets from one UE to another UE of the BUDC group based on a respective MAC ID or RNTI of each UE. In such cases, the SC-UE may implement a MAC ID or RNTI routing table or map for data traffic among the UEs of the BUDC group. For instance, one UE to which data packets are routed may act as data master, aggregator, or modifier for an application executing on one or more of the UEs of the BUDC group. Alternately or additionally, the SC-UE may perform data packet filtering based on a MAC ID of the UE or use RNTI mapping and routing for exchanging data packets with the UE.

Optionally at <NUM>, the SC-UE communicates with the base station that is acting as the primary cell. For example, the SC-UE may communicate with the primary cell of the base station to access data or resources of the wireless network for which the base station serves as the primary cell. Additionally, the control-plane for the SC-UE of the BUDC group may come from the base station while the SC-UE serves to support the data-plane of the secondary cell.

<FIG> illustrates an example method <NUM> for communicating with a base station of a primary cell and secondary cell-user equipment of a dual connectivity (BUDC) group. In some aspects, operations of the method <NUM> are implemented by or with a UE <NUM> of a BUDC group. Alternately or additionally, the operations of the method <NUM> can be implemented by other entities described herein, such as another UE associated with a BUDC group <NUM>.

At <NUM>, configuration information for admittance to a BUDC group is received from a base station. The configuration information may be received through a layer-<NUM> message from the base station, which provides control-plane signaling and user-plane data to the UE as a primary cell.

At <NUM>, an indication of scheduled air interface resources is received from a secondary cell-user equipment (SC-UE) of the BUDC group. The SC-UE may provide the indication of scheduled resources through a layer-<NUM> message for a connection with a secondary cell of SC-UE or BUDC group. In some cases, the UE synchronizes with the SC-UE based on synchronization pilots and other reference signals provided by the SC-UE for secondary cell communication.

Optionally at <NUM>, the UE receives broadcast data that is transmitted by the SC-UE to UEs of the BUDC group. The UE receives the broadcast data from the SC-UE through the secondary cell of the BUDC group. In some cases, the broadcast data includes aggregate data and/or data received from other UEs of the BUDC group.

Optionally at <NUM>, the UE communicates unicast data with the SC-UE via the scheduled resources of the air interface. The unicast data may be filtered to the UE based on a MAC ID of the UE or routed to the UE based on an RNTI of the UE. Optionally at <NUM>, UE may also communicate control-plane information or user-plane data with the base station serving as the primary cell for the BUDC group.

Claim 1:
A method (<NUM>) performed by a first user equipment, UE, (<NUM>) for providing a secondary cell to one or more user equipments, UEs, (<NUM>-<NUM>) in a base station-user equipment dual connectivity, BUDC, group (<NUM>), the BUDC group (<NUM>) comprising the first UE (<NUM>) and the one or more UEs (<NUM>-<NUM>), the method comprising:
receiving (<NUM>), at the first UE (<NUM>) and from a base station (<NUM>), configuration information to serve as a secondary cell-user equipment, SC-UE, (<NUM>) that provides the secondary cell for the BUDC group (<NUM>), the base station (<NUM>) providing a primary connection within a primary cell for the one or more UEs (<NUM>-<NUM>) of the BUDC group (<NUM>);
providing, to a second UE (<NUM>) connected to the base station (<NUM>), access to the secondary cell for a secondary connection by admitting the second UE (<NUM>) to the BUDC group (<NUM>);
scheduling (<NUM>), for the second UE (<NUM>), resources of an air interface for communication in the secondary cell provided by the first UE (<NUM>) for the one or more UEs (<NUM>-<NUM>) of the BUDC group (<NUM>); and
communicating (<NUM>) data with the second UE (<NUM>) of the BUDC group (<NUM>) using the resources of the air interface that are scheduled for communication in the secondary cell.