WO2021037043A1

WO2021037043A1 - Acknowledgment feedback for carrier aggregation

Info

Publication number: WO2021037043A1
Application number: PCT/CN2020/111290
Authority: WO
Inventors: Bo Chen; Chao Wei; Peng Cheng; Chenxi HAO; Ruiming Zheng; Yu Zhang; Hao Xu
Original assignee: Qualcomm Incorporated
Priority date: 2019-08-30
Filing date: 2020-08-26
Publication date: 2021-03-04
Also published as: WO2021035667A1

Abstract

Methods, systems, and devices for wireless communications are described. A user equipment (UE) in a carrier aggregation configuration may switch transmission of uplink control information (UCI) for a primary cell (PCell) group from a primary physical uplink control channel (PUCCH) initially configured for the PCell group to a secondary PUCCH initially configured for a secondary cell (SCell) group. In some cases, the UE may receive a configuration for the primary PUCCH and then may receive a reconfiguration for the primary PUCCH with an SCell PUCCH parameter or an SCell PUCCH enablement parameter to enable transmitting the UCI for the PCell group in the SCell PUCCH. In some cases, the UE may receive separate configurations for each of the primary PUCCH and the secondary PUCCH, and the UE may determine which PUCCH to use for transmitting the UCI for the PCell group based on activation or deactivation signaling.

Description

ACKNOWLEDGMENT FEEDBACK FOR CARRIER AGGREGATION

CROSS REFERENCE

The present Application for Patent claims the benefit of PCT Application No. PCT/CN2019/103581 by CHEN et al., entitled “ACKNOWLEDGMENT FEEDBACK FOR CARRIER AGGREGATION, ” filed August 30, 2019, assigned to the assignee hereof.

BACKGROUND

The following relates generally to wireless communications, and more specifically to acknowledgment (ACK) feedback for carrier aggregation (CA) .

Wireless communications systems are widely deployed to provide various types of communication content such as voice, video, packet data, messaging, broadcast, and so on. These systems may be capable of supporting communication with multiple users by sharing the 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, LTE-Advanced (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 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 communications system may include a number of base stations or network access nodes, each simultaneously supporting communication for multiple communication devices, which may be otherwise known as user equipment (UE) .

In some wireless communications systems, a UE may support CA, where the UE communicates with multiple cells simultaneously. For example, the UE may communicate with a first base station (e.g., a primary cell (PCell) ) and with a second base station (e.g., a secondary cell (SCell) ) at the same time. Additionally or alternatively, a single base station may include multiple cells (e.g., both a PCell and an SCell) , where the UE communicates with two or more cells on the single base station at the same time. In some cases, one or more of the cells may be grouped into a PCell group, which may include the PCell and one or more SCells. Additionally, one or more SCells may be grouped into an SCell group. Communications on each cell group may be independent of each other. Techniques are desired for leveraging the simultaneous communications occurring on the multiple cells for more efficient communications with the different cell groups.

SUMMARY

The described techniques relate to improved methods, systems, devices, and apparatuses that support acknowledgment (ACK) feedback for carrier aggregation (CA) . Generally, the described techniques provide for a user equipment (UE) in a CA configuration that is able to switch transmission of uplink control information (UCI) for a primary cell (PCell) group from a primary physical uplink control channel (PUCCH) initially configured for the PCell to a secondary PUCCH initially configured for a secondary cell (SCell) of an SCell group. For example, the UE may include a switching capability supporting at least dynamic switching to transmit UCI on the secondary PUCCH. In some cases, the UE may receive a configuration for the primary PUCCH, and when the SCell group (e.g., or a single SCell) is added to the CA configuration, the primary PUCCH configuration may be reconfigured with an SCell PUCCH parameter to enable the UE to use the secondary PUCCH for transmitting the UCI for the PCell group (e.g., based on a synchronization completion, random access channel (RACH) procedure, reconfiguration timer expiring, processing time expiring, etc. ) .

Additionally or alternatively, the primary PUCCH configuration may be reconfigured with an SCell PUCCH enablement parameter to enable the UE to use the secondary PUCCH for transmitting the UCI for the PCell group (e.g., without additional conditions to be met) . In some cases, the UE may receive separate configurations for each of the primary PUCCH and the secondary PUCCH, and the UE may determine which PUCCH to use for transmitting the UCI for the PCell group based on activation/deactivation signaling. For example, the activation/deactivation signaling may include a medium access control (MAC) control element (CE) activation/deactivation signal for the secondary PUCCH, a radio resource control (RRC) activation/deactivation signal for the secondary PUCCH, a downlink control information (DCI) signal with a downlink grant indicating which PUCCH to use, or a combination thereof.

A method of wireless communications at a UE is described. The method may include identifying a CA configuration including a PCell group having a PCell configured with a primary uplink control channel (e.g., primary PUCCH, PUCCH PCell, etc. ) and an SCell group having an SCell configured with a secondary uplink control channel (e.g., secondary PUCCH, PUCCH SCell, etc. ) , identifying that the UE has a switching capability supporting at least dynamic switching of transmission of UCI for the PCell group between the primary uplink control channel and the secondary uplink control channel, selecting the secondary uplink control channel to transmit the UCI for the PCell group based on the switching capability of the UE, and transmitting the UCI for the PCell group on the selected secondary uplink control channel.

An apparatus for wireless communications at a UE is described. The apparatus may include a processor, memory coupled with the processor, and instructions stored in the memory. The instructions may be executable by the processor to cause the apparatus to identify a CA configuration including a PCell group having a PCell configured with a primary uplink control channel and an SCell group having an SCell configured with a secondary uplink control channel, identify that the UE has a switching capability supporting at least dynamic switching of transmission of UCI for the PCell group between the primary uplink control channel and the secondary uplink control channel, select the secondary uplink control channel to transmit the UCI for the PCell group based on the switching capability of the UE, and transmit the UCI for the PCell group on the selected secondary uplink control channel.

Another apparatus for wireless communications at a UE is described. The apparatus may include means for identifying a CA configuration including a PCell group having a PCell configured with a primary uplink control channel and an SCell group having an SCell configured with a secondary uplink control channel, identifying that the UE has a switching capability supporting at least dynamic switching of transmission of UCI for the PCell group between the primary uplink control channel and the secondary uplink control channel, selecting the secondary uplink control channel to transmit the UCI for the PCell group based on the switching capability of the UE, and transmitting the UCI for the PCell group on the selected secondary uplink control channel.

A non-transitory computer-readable medium storing code for wireless communications at a UE is described. The code may include instructions executable by a processor to identify a CA configuration including a PCell group having a PCell configured with a primary uplink control channel and an SCell group having an SCell configured with a secondary uplink control channel, identify that the UE has a switching capability supporting at least dynamic switching of transmission of UCI for the PCell group between the primary uplink control channel and the secondary uplink control channel, select the secondary uplink control channel to transmit the UCI for the PCell group based on the switching capability of the UE, and transmit the UCI for the PCell group on the selected secondary uplink control channel.

Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein may further include operations, features, means, or instructions for receiving an uplink control channel configuration message for the primary uplink control channel including an SCell uplink control channel parameter, where the SCell uplink control channel parameter enables the UE to transmit the UCI for the PCell group on the secondary uplink control channel.

Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein may further include operations, features, means, or instructions for identifying that the secondary uplink control channel may be enabled based on a reconfiguration of the CA configuration, where the reconfiguration results from completion of a random access procedure with the SCell of the SCell group.

Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein may further include operations, features, means, or instructions for identifying that the secondary uplink control channel may be enabled based on expiration of a reconfiguration timer.

Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein may further include operations, features, means, or instructions for transmitting the UCI for the PCell group on the secondary uplink control channel after expiration of a configuration processing time threshold.

Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein may further include operations, features, means, or instructions for receiving an indicator to switch from the secondary uplink control channel to the primary uplink control channel for transmitting the UCI.

Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein may further include operations, features, means, or instructions for releasing the SCell group, and selecting the primary uplink control channel for transmitting the UCI for the PCell group based on releasing the SCell group.

Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein may further include operations, features, means, or instructions for receiving an uplink control channel configuration message for the primary uplink control channel, identifying an activation of the SCell group, and receiving an uplink control channel reconfiguration message for the primary uplink control channel including an SCell uplink control channel enablement parameter, where the SCell uplink control channel enablement parameter enables the UE to transmit the UCI for the PCell group on the secondary uplink control channel.

Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein may further include operations, features, means, or instructions for receiving a second uplink control channel reconfiguration message for the primary uplink control channel deleting the SCell uplink control channel enablement parameter, where the second uplink control channel reconfiguration message indicates for the UE to transmit the UCI on the primary uplink control channel based on the SCell uplink control channel enablement parameter being deleted.

Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein may further include operations, features, means, or instructions for receiving a first uplink control channel configuration message for the primary uplink control channel, and receiving a second uplink control channel configuration message for the secondary uplink control channel, where the secondary uplink control channel may be selected to transmit the UCI for the PCell group based on the first uplink control channel configuration message and the second uplink control channel configuration message.

Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein may further include operations, features, means, or instructions for receiving an indicator to enable the secondary uplink control channel, where the UE transmits the UCI for the PCell group on the secondary uplink control channel based on the indicator enabling the secondary uplink control channel.

Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein may further include operations, features, means, or instructions for receiving the indicator to disable the secondary uplink control channel, where the UE transmits the UCI for the PCell group on the primary uplink control channel based on the indicator disabling the secondary uplink control channel.

In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, the indicator may be received via MAC CE, RRC signaling, DCI signaling, or a combination thereof.

In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, the indication may include DCI with a downlink grant configuring the UE to transmit the UCI on the secondary uplink control channel.

In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, the PCell group may include a first subcarrier spacing (SCS) , and the SCell group may include a second SCS that may be different than the first SCS.

In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, the UCI may include ACK feedback, channel state information (CSI) reports, or a combination thereof.

A method of wireless communications at a base station is described. The method may include identifying, for communications with a UE, a CA configuration including a PCell group having a PCell configured with a primary uplink control channel (e.g., primary PUCCH, PUCCH PCell, etc. ) and an SCell group having an SCell configured with a secondary uplink control channel (e.g., secondary PUCCH, PUCCH SCell, etc. ) , identifying that the UE has a switching capability supporting at least dynamic switching of transmission of UCI for the PCell group between the primary uplink control channel and the secondary uplink control channel, and receiving, from the UE, the UCI for the PCell group on the secondary uplink control channel based on the switching capability.

An apparatus for wireless communications at a base station is described. The apparatus may include a processor, memory coupled with the processor, and instructions stored in the memory. The instructions may be executable by the processor to cause the apparatus to identify, for communications with a UE, a CA configuration including a PCell group having a PCell configured with a primary uplink control channel and an SCell group having an SCell configured with a secondary uplink control channel, identify that the UE has a switching capability supporting at least dynamic switching of transmission of UCI for the PCell group between the primary uplink control channel and the secondary uplink control channel, and receive, from the UE, the UCI for the PCell group on the secondary uplink control channel based on the switching capability.

Another apparatus for wireless communications at a base station is described. The apparatus may include means for identifying, for communications with a UE, a CA configuration including a PCell group having a PCell configured with a primary uplink control channel and an SCell group having an SCell configured with a secondary uplink control channel, identifying that the UE has a switching capability supporting at least dynamic switching of transmission of UCI for the PCell group between the primary uplink control channel and the secondary uplink control channel, and receiving, from the UE, the UCI for the PCell group on the secondary uplink control channel based on the switching capability.

A non-transitory computer-readable medium storing code for wireless communications at a base station is described. The code may include instructions executable by a processor to identify, for communications with a UE, a CA configuration including a PCell group having a PCell configured with a primary uplink control channel and an SCell group having an SCell configured with a secondary uplink control channel, identify that the UE has a switching capability supporting at least dynamic switching of transmission of UCI for the PCell group between the primary uplink control channel and the secondary uplink control channel, and receive, from the UE, the UCI for the PCell group on the secondary uplink control channel based on the switching capability.

Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein may further include operations, features, means, or instructions for transmitting, to the UE, an uplink control channel configuration message for the primary uplink control channel including an SCell uplink control channel parameter, where the SCell uplink control channel parameter enables the UE to transmit the UCI for the PCell group on the secondary uplink control channel.

In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, the UCI for the PCell group may be received on the secondary uplink control channel based on a reconfiguration of the CA configuration, completion of a random access procedure for the SCell of the SCell group, a reconfiguration timer expiration, a processing time threshold expiration, or a combination thereof.

Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein may further include operations, features, means, or instructions for transmitting, to the UE, an indication to switch from the secondary uplink control channel to the primary uplink control channel for transmitting the UCI, where the UCI may be received on the primary uplink control channel based on the transmitted indication to switch.

Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein may further include operations, features, means, or instructions for transmitting an uplink control channel configuration message for the primary uplink control channel, identifying an activation of the SCell group, and transmitting an uplink control channel reconfiguration message for the primary uplink control channel including an SCell uplink control channel enablement parameter, where the SCell uplink control channel enablement parameter enables the UE to transmit the UCI for the PCell group on the secondary uplink control channel.

Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein may further include operations, features, means, or instructions for transmitting a second uplink control channel reconfiguration message for the primary uplink control channel deleting the SCell uplink control channel enablement parameter, where the second uplink control channel reconfiguration message indicates for the UE to transmit the UCI on the primary uplink control channel based on the SCell uplink control channel enablement parameter being deleted.

Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein may further include operations, features, means, or instructions for transmitting a first uplink control channel configuration message for the primary uplink control channel, and transmitting a second uplink control channel configuration message for the secondary uplink control channel, where the UCI for the PCell group may be received on the secondary uplink control channel based on the first uplink control channel configuration message and the second uplink control channel configuration message.

Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein may further include operations, features, means, or instructions for transmitting an indicator to enable the secondary uplink control channel, where the UCI for the PCell group may be received on the secondary uplink control channel based on the indicator enabling the secondary uplink control channel.

Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein may further include operations, features, means, or instructions for transmitting the indicator to disable the secondary uplink control channel, where the UCI for the PCell group may be received on the primary uplink control channel based on the indicator disabling the secondary uplink control channel.

In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, the indicator may be transmitted via MAC CE, RRC signaling, DCI signaling, or a combination thereof.

In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, the indication may include DCI with a downlink grant configuring the UE to transmit the UCI on the secondary uplink control channel, where the UCI may be received on the secondary uplink control channel based at least according to the configured uplink control channel.

In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, the PCell group may include a first SCS, and the SCell group may include a second SCS that may be different than the first SCS.

In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, the UCI may include ACK feedback, CSI reports, or a combination thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. FIG. 1 illustrates an example of a system for wireless communications that supports acknowledgment (ACK) feedback for carrier aggregation (CA) in accordance with aspects of the present disclosure.

FIG. 2 illustrates an example of a wireless communications system that supports ACK feedback for CA in accordance with aspects of the present disclosure.

FIGs. 3A and 3B illustrate examples of physical uplink control channel (PUCCH) configurations that support ACK feedback for CA in accordance with aspects of the present disclosure.

FIGs. 4A and 4B illustrate example of a downlink retransmission signalings that supports ACK feedback for CA in accordance with aspects of the present disclosure.

FIG. 5 illustrates an example of a process flow that supports ACK feedback for CA in accordance with aspects of the present disclosure.

FIGs. 6 and 7 show block diagrams of devices that support acknowledgment feedback for carrier aggregation in accordance with aspects of the present disclosure.

FIG. 8 shows a block diagram of a user equipment (UE) communications manager that supports acknowledgment feedback for carrier aggregation in accordance with aspects of the present disclosure.

FIG. 9 shows a diagram of a system including a device that supports acknowledgment feedback for carrier aggregation in accordance with aspects of the present disclosure.

FIGs. 10 and 11 show block diagrams of devices that support acknowledgment feedback for carrier aggregation in accordance with aspects of the present disclosure.

FIG. 12 shows a block diagram of a base station communications manager that supports acknowledgment feedback for carrier aggregation in accordance with aspects of the present disclosure.

FIG. 13 shows a diagram of a system including a device that supports acknowledgment feedback for carrier aggregation in accordance with aspects of the present disclosure.

FIGs. 14 through 18 show flowcharts illustrating methods that support acknowledgment feedback for carrier aggregation in accordance with aspects of the present disclosure.

DETAILED DESCRIPTION

In some wireless communications systems, a user equipment (UE) may support carrier aggregation (CA) that includes at least a primary cell (PCell) and a secondary cell (SCell) . Accordingly, the UE may support transmitting separate physical uplink control channels (PUCCHs) to each of the PCell and the SCell. For example, the UE may transmit uplink control information (UCI) for a PCell group (e.g., one or more cells including the PCell) in a primary PUCCH (e.g., PUCCH PCell) configured for the PCell group and may transmit UCI for an SCell group (e.g., one or more cells including the SCell) in a secondary PUCCH (e.g., PUCCH SCell) configured for the SCell group. However, in some cases, the UE may transmit the UCI for the PCell group on the secondary PUCCH to enable faster response and reduce a delay associated with downlink retransmissions for transmissions in the PCell group. As described herein, the UE may support switching (e.g., semi-statically or dynamically) between the primary PUCCH and the secondary PUCCH for transmitting the UCI for the PCell group. Additionally, enablement of such dynamic switching and the timing of the switching (e.g., when enablement takes effect) may be specified in various configuration messages.

In some cases, to enable the switching, a PUCCH configuration message may be transmitted for the PCell. The configuration message may include an added PUCCH SCell parameter to enable the UE to transmit the UCI for the PCell group on the SCell. The timing of the enablement may be based on performance of a RACH on the SCell, expiration of a reconfiguration timer, expiration of a processing time threshold, or a combination thereof. In some cases, the UE may also fallback to the PUCCH configured for the PCell group if the secondary PUCCH/SCell is released.

Additionally or alternatively, a PUCCH configuration message may be transmitted for the PCell after the PUCCH SCell has been activated and is ready for use. The PUCCH configuration message may include an added PUCCH SCell enablement parameter to enable the UE to transmit the UCI for the PCell group on the PUCCH configured/enabled for the SCell. Additionally the PUCCH SCell enablement parameter may be deleted from the PUCCH configuration (e.g., with the UE using the PCell to transmit the UCI) prior to deactivation of the SCell.

In some implementations, respective PUCCH configuration messages may be transmitted for each of the PCell and the SCell. Accordingly, the UE may use the PCell or the SCell based on an indication (e.g., activation or deactivation trigger) for the SCell PUCCH. If activated, the UE may use the PUCCH configured for the SCell, and if deactivated, the UE may use the PUCCH configured for the PCell. The activation/deactivation message may include a medium access control (MAC) control element (CE) enabling the PUCCH configured for the SCell, a radio resource control (RRC) reconfiguration message enabling the PUCCH configured for the SCell, downlink control information (DCI) , etc. For example, for the DCI, a downlink grant received with the DCI may indicate for the UE to transmit the UCI on the PUCCH configured for the PCell or the PUCCH configured for the SCell.

Aspects of the disclosure are initially described in the context of a wireless communications system. Additionally, aspects of the disclosure are illustrated through an additional wireless communications system, PUCCH configurations, a downlink retransmission signaling, and a process flow. Aspects of the disclosure are further illustrated by and described with reference to apparatus diagrams, system diagrams, and flowcharts that relate to ACK feedback for CA.

FIG. 1 illustrates an example of a wireless communications system 100 that supports ACK feedback for CA in accordance with aspects of the present disclosure. The wireless communications system 100 includes base stations 105, UEs 115, and a core network 130. In some examples, the wireless communications system 100 may 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 cases, wireless communications system 100 may support enhanced broadband communications, ultra-reliable (e.g., mission critical) communications, low latency communications, or communications with low-cost and low-complexity devices.

Base stations 105 may wirelessly communicate with UEs 115 via one or more base station antennas. Base stations 105 described herein may include or may be referred to by those skilled in the art as 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 may be referred to as a gNB) , a Home NodeB, a Home eNodeB, or some other suitable terminology. Wireless communications system 100 may include base stations 105 of different types (e.g., macro or small cell base stations) . The UEs 115 described herein may be able to communicate with various types of base stations 105 and network equipment including macro eNBs, small cell eNBs, gNBs, relay base stations, and the like.

Each base station 105 may be associated with a particular geographic coverage area 110 in which communications with various UEs 115 is supported. Each base station 105 may provide communication coverage for a respective geographic coverage area 110 via communication links 125, and communication links 125 between a base station 105 and a UE 115 may utilize one or more carriers. Communication links 125 shown in wireless communications system 100 may include uplink transmissions from a UE 115 to a base station 105, or downlink transmissions from a base station 105 to a UE 115. Downlink transmissions may also be called forward link transmissions while uplink transmissions may also be called reverse link transmissions.

The geographic coverage area 110 for a base station 105 may be divided into sectors making up a portion of the geographic coverage area 110, and each sector may be associated with a cell. For example, each base station 105 may provide communication coverage for a macro cell, a small cell, a hot spot, or other types of cells, or various combinations thereof. In some examples, a base station 105 may be movable and therefore provide communication coverage for a moving geographic coverage area 110. In some examples, different geographic coverage areas 110 associated with different technologies may overlap, and overlapping geographic coverage areas 110 associated with different technologies may be supported by the same base station 105 or by different base stations 105. The wireless communications system 100 may include, for example, a heterogeneous LTE/LTE-A/LTE-A Pro or NR network in which different types of base stations 105 provide coverage for various geographic coverage areas 110.

The term “cell” refers to a logical communication entity used for communication with a base station 105 (e.g., over a carrier) , and may be associated with an identifier for distinguishing neighboring cells (e.g., a physical cell identifier (PCID) , a virtual cell identifier (VCID) ) operating via the same or a different carrier. In some examples, a carrier may support multiple cells, and different cells may be configured according to different protocol types (e.g., machine-type communication (MTC) , narrowband Internet-of-Things (NB-IoT) , enhanced mobile broadband (eMBB) , or others) that may provide access for different types of devices. In some cases, the term “cell” may refer to a portion of a geographic coverage area 110 (e.g., a sector) over which the logical entity operates.

UEs 115 may be dispersed throughout the wireless communications system 100, and each UE 115 may be stationary or mobile. A UE 115 may also 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” may also be referred to as a unit, a station, a terminal, or a client. A UE 115 may be 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 may also refer to a wireless local loop (WLL) station, an Internet of Things (IoT) device, an Internet of Everything (IoE) device, or an MTC device, or the like, which may be implemented in various articles such as appliances, vehicles, meters, or the like.

Some UEs 115, such as MTC or IoT devices, may be low cost or low complexity devices, and may provide for automated communication between machines (e.g., via Machine-to-Machine (M2M) communication) . M2M communication or MTC may refer to data communication technologies that allow devices to communicate with one another or a base station 105 without human intervention. In some examples, M2M communication or MTC may include communications from devices that integrate sensors or meters to measure or capture information and relay that information to a central server or application program that can make use of the information or present the information to humans interacting with the program or application. Some UEs 115 may be designed to collect information or enable automated behavior of machines. Examples of applications for MTC devices include smart metering, inventory monitoring, water level monitoring, equipment monitoring, healthcare monitoring, wildlife monitoring, weather and geological event monitoring, fleet management and tracking, remote security sensing, physical access control, and transaction-based business charging.

Some UEs 115 may be configured to employ operating modes that reduce power consumption, such as half-duplex communications (e.g., a mode that supports one-way communication via transmission or reception, but not transmission and reception simultaneously) . In some examples, half-duplex communications may be performed at a reduced peak rate. Other power conservation techniques for UEs 115 include entering a power saving “deep sleep” mode when not engaging in active communications, or operating over a limited bandwidth (e.g., according to narrowband communications) . In some cases, UEs 115 may be designed to support critical functions (e.g., mission critical functions) , and a wireless communications system 100 may be configured to provide ultra-reliable communications for these functions.

In some cases, a UE 115 may also be able to communicate directly with other UEs 115 (e.g., using a peer-to-peer (P2P) or device-to-device (D2D) protocol) . One or more of a group of UEs 115 utilizing D2D communications may be within the geographic coverage area 110 of a base station 105. Other UEs 115 in such a group may be outside the geographic coverage area 110 of a base station 105, or be otherwise unable to receive transmissions from a base station 105. In some cases, groups of UEs 115 communicating via D2D communications 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 cases, a base station 105 facilitates the scheduling of resources for D2D communications. In other cases, D2D communications are carried out between UEs 115 without the involvement of a base station 105.

Base stations 105 may communicate with the core network 130 and with one another. For example, base stations 105 may interface with the core network 130 through backhaul links 132 (e.g., via an S1, N2, N3, or other interface) . Base stations 105 may communicate with one another over backhaul links 134 (e.g., via an X2, Xn, or other interface) either directly (e.g., directly between base stations 105) or indirectly (e.g., via core network 130) .

The core network 130 may provide user authentication, access authorization, tracking, Internet Protocol (IP) connectivity, and other access, routing, or mobility functions. The core network 130 may be an evolved packet core (EPC) , which may include at least one mobility management entity (MME) , at least one serving gateway (S-GW) , and at least one Packet Data Network (PDN) gateway (P-GW) . The MME may manage non-access stratum (e.g., control plane) functions such as mobility, authentication, and bearer management for UEs 115 served by base stations 105 associated with the EPC. User IP packets may be transferred through the S-GW, which itself may be connected to the P-GW. The P-GW may provide IP address allocation as well as other functions. The P-GW may be connected to the network operators IP services. The operators IP services may include access to the Internet, Intranet (s) , an IP Multimedia Subsystem (IMS) , or a Packet-Switched (PS) Streaming Service.

At least some of the network devices, such as a base station 105, may include subcomponents such as an access network entity, which may be an example of an access node controller (ANC) . Each access network entity may communicate with UEs 115 through a number of other access network transmission entities, which may be referred to as a radio head, a smart radio head, or a transmission/reception point (TRP) . In some configurations, various functions of each access network entity or base station 105 may be distributed across various network devices (e.g., radio heads and access network controllers) or consolidated into a single network device (e.g., a base station 105) .

Wireless communications system 100 may operate using one or more frequency bands, such as 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. UHF waves may be blocked or redirected by buildings and environmental features. However, the waves may penetrate structures sufficiently for a macro cell to provide service to UEs 115 located indoors. Transmission of UHF waves may be associated with smaller antennas and shorter range (e.g., less than 100 km) compared to transmission using the smaller frequencies and longer waves of the high frequency (HF) or very high frequency (VHF) portion of the spectrum below 300 MHz.

Wireless communications system 100 may also operate in a super high frequency (SHF) region using frequency bands from 3 GHz to 30 GHz, also known as the centimeter band. The SHF region includes bands such as the 5 GHz industrial, scientific, and medical (ISM) bands, which may be used opportunistically by devices that may be capable of tolerating interference from other users.

Wireless communications system 100 may also operate in an extremely high frequency (EHF) region of the spectrum (e.g., from 30 GHz to 300 GHz) , also known as the millimeter band. In some examples, wireless communications system 100 may support millimeter wave (mmW) communications between UEs 115 and base stations 105, and EHF antennas of the respective devices may be even smaller and more closely spaced than UHF antennas. In some cases, this may facilitate use of antenna arrays within a UE 115. However, the propagation of EHF transmissions may be subject to even greater atmospheric attenuation and shorter range than SHF or UHF transmissions. Techniques disclosed herein may be employed across transmissions that use one or more different frequency regions, and designated use of bands across these frequency regions may differ by country or regulating body.

In some cases, wireless communications system 100 may utilize both licensed and unlicensed radio frequency spectrum bands. For example, wireless communications system 100 may employ License Assisted Access (LAA) , LTE-Unlicensed (LTE-U) radio access technology, or NR technology in an unlicensed band such as the 5 GHz ISM band. When operating in unlicensed radio frequency spectrum bands, wireless devices such as base stations 105 and UEs 115 may employ listen-before-talk (LBT) procedures to ensure a frequency channel is clear before transmitting data. In some cases, operations in unlicensed bands may be based on a carrier aggregation configuration in conjunction with component carriers operating in a licensed band (e.g., LAA) . Operations in unlicensed spectrum may include downlink transmissions, uplink transmissions, peer-to-peer transmissions, or a combination of these. Duplexing in unlicensed spectrum may be based on frequency division duplexing (FDD) , time division duplexing (TDD) , or a combination of both.

In some examples, base station 105 or UE 115 may be equipped with multiple antennas, which may be used to employ techniques such as transmit diversity, receive diversity, multiple-input multiple-output (MIMO) communications, or beamforming. For example, wireless communications system 100 may use a transmission scheme between a transmitting device (e.g., a base station 105) and a receiving device (e.g., a UE 115) , where the transmitting device is equipped with multiple antennas and the receiving device is equipped with one or more antennas. MIMO communications may employ multipath signal propagation to increase the spectral efficiency by transmitting or receiving multiple signals via different spatial layers, which may be referred to as spatial multiplexing. The multiple signals may, for example, be transmitted by the transmitting device via different antennas or different combinations of antennas. Likewise, the multiple signals may be received by the receiving device via different antennas or different combinations of antennas. Each of the multiple signals may be referred to as a separate spatial stream, and may carry bits associated with the same data stream (e.g., the same codeword) or different data streams. Different spatial layers may be associated with different antenna ports used for channel measurement and reporting. MIMO techniques include single-user MIMO (SU-MIMO) where multiple spatial layers are transmitted to the same receiving device, and multiple-user MIMO (MU-MIMO) where multiple spatial layers are transmitted to multiple devices.

Beamforming, which may also be referred to as spatial filtering, directional transmission, or directional reception, is a signal processing technique that may be used at a transmitting device or a receiving device (e.g., a base station 105 or a UE 115) to shape or steer an antenna beam (e.g., a transmit beam or receive beam) along a spatial path between the transmitting device and the receiving device. Beamforming may be achieved by combining the signals communicated via antenna elements of an antenna array such that signals propagating at particular orientations with respect to an antenna array experience constructive interference while others experience destructive interference. The adjustment of signals communicated via the antenna elements may include a transmitting device or a receiving device applying amplitude and phase offsets to signals carried via each of the antenna elements associated with the device. The adjustments associated with each of the antenna elements may be defined by a beamforming weight set associated with a particular orientation (e.g., with respect to the antenna array of the transmitting device or receiving device, or with respect to some other orientation) .

In one example, a base station 105 may use multiple antennas or antenna arrays to conduct beamforming operations for directional communications with a UE 115. For instance, some signals (e.g., synchronization signals, reference signals, beam selection signals, or other control signals) may be transmitted by a base station 105 multiple times in different directions, which may include a signal being transmitted according to different beamforming weight sets associated with different directions of transmission. Transmissions in different beam directions may be used to identify (e.g., by the base station 105 or a receiving device, such as a UE 115) a beam direction for subsequent transmission or reception or both by the base station 105.

Some signals, such as data signals associated with a particular receiving device, may be transmitted by a base station 105 in a single beam direction (e.g., a direction associated with the receiving device, such as a UE 115) . In some examples, the beam direction associated with transmissions along a single beam direction may be determined based at least in in part on a signal that was transmitted in different beam directions. For example, a UE 115 may receive one or more of the signals transmitted by the base station 105 in different directions, and the UE 115 may report to the base station 105 an indication of the signal UE 115 received with a highest signal quality, or an otherwise acceptable signal quality. Although these techniques are described with reference to signals transmitted in one or more directions by a base station 105, a UE 115 may employ similar techniques for transmitting signals multiple times in different directions (e.g., for identifying a beam direction for subsequent transmission or reception by the UE 115) , or transmitting a signal in a single direction (e.g., for transmitting data to a receiving device) .

A receiving device (e.g., a UE 115, which may be an example of a mmW receiving device) may try multiple receive beams when receiving various signals from the base station 105, such as synchronization signals, reference signals, beam selection signals, or other control signals. For example, a receiving device may try multiple receive directions by receiving via different antenna subarrays, by processing received signals according to different antenna subarrays, by receiving according to different receive beamforming weight sets applied to signals received at a plurality of antenna elements of an antenna array, or by processing received signals according to different receive beamforming weight sets applied to signals received at a plurality of antenna elements of an antenna array, any of which may be referred to as “listening” according to different receive beams or receive directions. In some examples, a receiving device may use a single receive beam to receive along a single beam direction (e.g., when receiving a data signal) . The single receive beam may be aligned in a beam direction determined based at least in part on listening according to different receive beam directions (e.g., a beam direction determined to have a highest signal strength, highest signal-to-noise ratio, or otherwise acceptable signal quality based at least in part on listening according to multiple beam directions) .

In some cases, the antennas of a base station 105 or UE 115 may be located within one or more antenna arrays, which may support MIMO operations, or transmit or receive beamforming. For example, one or more base station antennas or antenna arrays may be co-located at an antenna assembly, such as an antenna tower. In some cases, antennas or antenna arrays associated with a base station 105 may be located in diverse geographic locations. A base station 105 may have an antenna array with a number of rows and columns of antenna ports that the base station 105 may use to support beamforming of communications with a UE 115. Likewise, a UE 115 may have one or more antenna arrays that may support various MIMO or beamforming operations.

In some cases, wireless communications system 100 may be a packet-based network that operate according to a layered protocol stack. In the user plane, communications at the bearer or Packet Data Convergence Protocol (PDCP) layer may be IP-based. A Radio Link Control (RLC) layer may perform packet segmentation and reassembly to communicate over logical channels. A MAC layer may perform priority handling and multiplexing of logical channels into transport channels. The MAC layer may also use hybrid automatic repeat request (HARQ) to provide retransmission at the MAC layer to improve link efficiency. In the control plane, the RRC protocol layer may 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 may be mapped to physical channels.

In some cases, UEs 115 and base stations 105 may support retransmissions of data to increase the likelihood that data is received successfully. HARQ feedback is one technique of increasing the likelihood that data is received correctly over a communication link 125. HARQ may include a combination of error detection (e.g., using a cyclic redundancy check (CRC) ) , forward error correction (FEC) , and retransmission (e.g., automatic repeat request (ARQ) ) . HARQ may improve throughput at the MAC layer in poor radio conditions (e.g., signal-to-noise conditions) . In some cases, a wireless device may support same-slot HARQ feedback, where the device may provide HARQ feedback in a specific slot for data received in a previous symbol in the slot. In other cases, the device may provide HARQ feedback in a subsequent slot, or according to some other time interval.

Time intervals in LTE or NR may be expressed in multiples of a basic time unit, which may, for example, refer to a sampling period of T _s = 1/30,720,000 seconds. Time intervals of a communications resource may be organized according to radio frames each having a duration of 10 milliseconds (ms) , where the frame period may be expressed as T _f = 307,200 T _s. The radio frames may be identified by a system frame number (SFN) ranging from 0 to 1023. Each frame may include 10 subframes numbered from 0 to 9, and each subframe may have a duration of 1 ms. A subframe may be further divided into 2 slots each having a duration of 0.5 ms, and each slot may contain 6 or 7 modulation symbol periods (e.g., depending on the length of the cyclic prefix prepended to each symbol period) . Excluding the cyclic prefix, each symbol period may contain 2048 sampling periods. In some cases, a subframe may be the smallest scheduling unit of the wireless communications system 100, and may be referred to as a transmission time interval (TTI) . In other cases, a smallest scheduling unit of the wireless communications system 100 may be shorter than a subframe or may be dynamically selected (e.g., in bursts of shortened TTIs (sTTIs) or in selected component carriers using sTTIs) .

In some wireless communications systems, a slot may further be divided into multiple mini-slots containing one or more symbols. In some instances, a symbol of a mini-slot or a mini-slot may be the smallest unit of scheduling. Each symbol may vary in duration depending on the subcarrier spacing or frequency band of operation, for example. Further, some wireless communications systems may implement slot aggregation in which multiple slots or mini-slots are aggregated together and used for communication between a UE 115 and a base station 105.

The term “carrier” refers to a set of radio frequency spectrum resources having a defined physical layer structure for supporting communications over a communication link 125. For example, a carrier of a communication link 125 may include a portion of a radio frequency spectrum band that is operated according to physical layer channels for a given radio access technology. Each physical layer channel may carry user data, control information, or other signaling. A carrier may be associated with a pre-defined frequency channel (e.g., an evolved universal mobile telecommunication system terrestrial radio access (E-UTRA) absolute radio frequency channel number (EARFCN) ) and may be positioned according to a channel raster for discovery by UEs 115. Carriers may be downlink or uplink (e.g., in an FDD mode) , or be configured to carry downlink and uplink communications (e.g., in a TDD mode) . In some examples, signal waveforms transmitted over a carrier may be made up of multiple sub-carriers (e.g., using multi-carrier modulation (MCM) techniques such as orthogonal frequency division multiplexing (OFDM) or discrete Fourier transform spread OFDM (DFT-S-OFDM) ) .

The organizational structure of the carriers may be different for different radio access technologies (e.g., LTE, LTE-A, LTE-A Pro, NR) . For example, communications over a carrier may be organized according to TTIs or slots, each of which may include user data as well as control information or signaling to support decoding the user data. A carrier may also include dedicated acquisition signaling (e.g., synchronization signals or system information, etc. ) and control signaling that coordinates operation for the carrier. In some examples, (e.g., in a carrier aggregation configuration) , a carrier may also have acquisition signaling or control signaling that coordinates operations for other carriers.

Physical channels may be multiplexed on a carrier according to various techniques. A physical control channel and a physical data channel may be multiplexed on a downlink carrier, for example, using time division multiplexing (TDM) techniques, frequency division multiplexing (FDM) techniques, or hybrid TDM-FDM techniques. In some examples, control information transmitted in a physical control channel may be distributed between different control regions in a cascaded manner (e.g., between a common control region or common search space and one or more UE-specific control regions or UE-specific search spaces) .

A carrier may be associated with a particular bandwidth of the radio frequency spectrum, and in some examples the carrier bandwidth may be referred to as a “system bandwidth” of the carrier or the wireless communications system 100. For example, the carrier bandwidth may be one of a number of predetermined bandwidths for carriers of a particular radio access technology (e.g., 1.4, 3, 5, 10, 15, 20, 40, or 80 MHz) . In some examples, each served UE 115 may be configured for operating over portions or all of the carrier bandwidth. In other examples, some UEs 115 may be configured for operation using a narrowband protocol type that is associated with a predefined portion or range (e.g., set of subcarriers or RBs) within a carrier (e.g., “in-band” deployment of a narrowband protocol type) .

In a system employing MCM techniques, a resource element may consist of one symbol period (e.g., a 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 may depend on the modulation scheme (e.g., the order of the modulation scheme) . Thus, the more resource elements that a UE 115 receives and the higher the order of the modulation scheme, the higher the data rate may be for the UE 115. In MIMO systems, a wireless communications resource may refer to a combination of a radio frequency spectrum resource, a time resource, and a spatial resource (e.g., spatial layers) , and the use of multiple spatial layers may further increase the data rate for communications with a UE 115.

Devices of the wireless communications system 100 (e.g., base stations 105 or UEs 115) may have a hardware configuration that supports communications over a particular carrier bandwidth, or may be configurable to support communications over one of a set of carrier bandwidths. In some examples, the wireless communications system 100 may include base stations 105 or UEs 115 or both that support simultaneous communications via carriers associated with more than one different carrier bandwidth.

Wireless communications system 100 may support communication with a UE 115 on multiple cells or carriers, a feature which may be referred to as CA or multi-carrier operation. A UE 115 may be configured with multiple downlink component carriers (CCs) and one or more uplink CCs according to a CA configuration. CA may be used with both FDD and TDD component carriers.

In some cases, wireless communications system 100 may utilize enhanced CCs (eCCs) . An eCC may be characterized by one or more features including wider carrier or frequency channel bandwidth, shorter symbol duration, shorter TTI duration, or modified control channel configuration. In some cases, an eCC may be associated with a carrier aggregation configuration or a dual connectivity configuration (e.g., when multiple serving cells have a suboptimal or non-ideal backhaul link) . An eCC may also be configured for use in unlicensed spectrum or shared spectrum (e.g., where more than one operator is allowed to use the spectrum) . An eCC characterized by wide carrier bandwidth may include one or more segments that may be utilized by UEs 115 that are not capable of monitoring the whole carrier bandwidth or are otherwise configured to use a limited carrier bandwidth (e.g., to conserve power) .

In some cases, an eCC may utilize a different symbol duration than other component carriers, which may include use of a reduced symbol duration as compared with symbol durations of the other component carriers. A shorter symbol duration may be associated with increased spacing between adjacent subcarriers. A device, such as a UE 115 or base station 105, utilizing eCCs may transmit wideband signals (e.g., according to frequency channel or carrier bandwidths of 20, 40, 60, 80 MHz, etc. ) at reduced symbol durations (e.g., 16.67 microseconds) . A TTI in eCC may consist of one or multiple symbol periods. In some cases, the TTI duration (that is, the number of symbol periods in a TTI) may be variable.

Wireless communications system 100 may be an NR system that may utilize any combination of licensed, shared, and unlicensed spectrum bands, among others. The flexibility of eCC symbol duration and subcarrier spacing may allow for the use of eCC across multiple spectrums. In some examples, NR shared spectrum may increase spectrum utilization and spectral efficiency, specifically through dynamic vertical (e.g., across the frequency domain) and horizontal (e.g., across the time domain) sharing of resources.

In some wireless communications systems (e.g., NR) , a UE 115 may support CA. For example, the UE may communicate with a first base station (e.g., a PCell) and with a second base station (e.g., an SCell) at the same time. Additionally or alternatively, a single base station may include multiple cells (e.g., both a PCell and an SCell) , where the UE communicates with two or more cells on the single base station at the same time. In some cases, one or more of the cells may be grouped into a PCell group, which may include the PCell and one or more SCells. Additionally, one or more of the SCells may be grouped into an SCell group. Communications on each cell group may be independent of each other.

Additionally, a first PUCCH may be configured as PUCCH for the PCell group. The first or primary PUCCH may be configured on the PCell and may be used to transmit control information (e.g., UCI) for the PCell group. A second PUCCH may be configured as PUCCH for the SCell group. The second or secondary PUCCH may be configured on an SCell of the SCell group and may be used to transmit control information for the SCell group. The SCell configured with the PUCCH for the SCell group may be referred to as a PUCCH SCell. For example, a serving cell (e.g., scheduling base station 105 that configures the CA for the UE 115) may configure an uplink CC (e.g., a PCell) in the PCell group to carry a primary PUCCH for transmitting UCI for each cell in the PCell group and may configure a second uplink CC (e.g., a primary SCell (PSCell) ) in the SCell group to carry a secondary PUCCH for transmitting UCI for each cell in the SCell group.

In some cases, the UCI may include HARQ ACK feedback to indicate whether the UE 115 successfully received and decoded downlink transmissions on each cell of each of the PCell group and the SCell group. Accordingly, the UE 115 may transmit ACKs in the corresponding PUCCH if the downlink transmissions in the respective cell group are successfully received and decoded or may transmit a negative ACK (NACK) in the corresponding PUCCH if the downlink transmissions are not successfully received or decoded in the respective cell group. In some cases, the UE 115 may combine the HARQ ACK feedback for each cell in a respective cell group when transmitting the PUCCH for that cell group.

In some cases, the network (e.g., a base station 105, serving cell, etc. ) may configure a single PUCCH (e.g., via a PUCCH-Config message) at least on non-initial bandwidth parts (BWPs) for transmitting UCI (e.g., or other uplink transmissions) for both the PCell group and the SCell group. Additionally or alternatively, if supported by the UE 115, the network may configure an SCell of the SCell group with a PUCCH (e.g., via a second PUCCH-Config message) . For example, as described herein, the PUCCH for the SCell of the SCell group may be an additional configured PUCCH (e.g., secondary PUCCH, PUCCH SCell, etc. ) dedicated to carrying UCI for the cells of the SCell group.

Accordingly, the UCI (e.g., ACK/NACK feedback) on the PUCCH for the PCell group and the UCI (e.g., ACK/NACK feedback) on the PUCCH for the SCell group may be independent of each other. For example, the PCell group may not use the PUCCH configured for the SCell group to feedback UCI for the cells of the PCell group, and the SCell group may not use the PUCCH configured for the PCell to feedback UCI for the cells of the SCell group. However, for some CA band combinations (e.g., TDD+FDD CA with TDD being used for the PCell) , enabling UCI (e.g., ACK/NACK feedback) for cells in the PCell group to be transmitted on the PUCCH configured for the SCell group may reduce the delay of the UCI feedback and data channel retransmission on the PCell for the TDD given a specific TDD frame structure. For example, if the UE 115 does not successfully receive or decode a downlink transmission from at least one of the cells in the PCell group, the UE 115 may transmit a NACK in a next occurring PUCCH for the PCell group, which may not occur for a number of slots (e.g., TTIs) in the future, delaying the corresponding cell from retransmitting the failed downlink transmission.

Conventionally, for a single PUCCH cell group (e.g., a single PUCCH configured on a PCell of the PCell group) , PUCCH signaling of both a PCell and an SCell may be transmitted on the PCell. Additionally, for two PUCCH cell groups (e.g., a primary PUCCH configured on a PCell of the PCell group and a secondary PUCCH configured on a PSCell of the SCell group) , PUCCH signaling of the primary PUCCH cell group (e.g., PCell group) may be transmitted on the PUCCH configured for the PCell (e.g., PUCCH PCell) , and PUCCH signaling of the secondary PUCCH cell group (e.g., SCell group) may be transmitted on the PUCCH configured for the SCell (e.g., PUCCH SCell) . However, as noted above, the two PUCCHs may be independent each other. Accordingly, for the conventional wireless communications systems (e.g., NR, LTE, etc. ) , for two PUCCH cell groups, the UE 115 may not support PUCCH signaling of the primary PUCCH cell group on the PUCCH SCell.

Wireless communications system 100 may support efficient techniques for a UE 115 being configured with PUCCH configurations on non-initial BWP (s) for a PCell or an SCell or both, where the UE 115 may support transmitting PUCCH signaling of a primary PUCCH cell group (e.g., PCell group) based on switching between a PUCCH configured for the PCell (e.g., primary PUCCH) and a PUCCH configured for the SCell (e.g., secondary PUCCH) statically or dynamically. In some cases, the UE 115 may receive a configuration for the primary PUCCH and then may receive a reconfiguration for the primary PUCCH with an SCell PUCCH parameter or an SCell PUCCH enablement parameter to enable the UE to use the secondary PUCCH for transmitting the UCI for the PCell group. In some cases, the UE may receive separate configurations for each of the primary PUCCH and the secondary PUCCH, and the UE may determine which PUCCH to use for transmitting the UCI for the PCell group based on activation/deactivation signaling.

FIG. 2 illustrates an example of a wireless communications system 200 that supports ACK feedback for CA in accordance with aspects of the present disclosure. In some examples, wireless communications system 200 may implement aspects of wireless communications system 100. Wireless communications system 200 may include a UE 115-a, a PCell 205, and an SCell 210, where UE 115-a corresponds to a UE 115 as described herein with reference to FIG. 1 and PCell 205 and SCell 210 correspond to base stations 105 or cells on a base station 105 as described herein with reference to FIG. 1. While PCell 205 and SCell 210 are shown as separate base stations 105, it is to be understood that both PCell 205 and SCell 210 may be part of the same base station 105. Additionally, as described herein, PCell 205 may be part of a PCell group (e.g., a group of cells or CCs configured for PCell communications, such as one PCell and one or more SCells configured for primary communications) , and SCell 210 may be part of an SCell group (e.g., a group of cells or CCs configured for SCell communications, such as one PSCell and one or more SCells configured for secondary communications) . In some cases, SCell 210 may represent a PSCell of the SCell group. Additionally, PCell 205 and SCell 210 may include different subcarrier spacings (SCSs) .

PCell 205 may communicate with UE 115-a on resources of a carrier 215-a, and SCell 210 may communicate with UE 115-a on resources of a carrier 215-b. In some cases, each cell or CC for the PCell group (e.g., including PCell 205) may use the same carrier 215-a (e.g., via different time or frequency resources or both of carrier 215-a, using different coding layers of a CDMA configuration of carrier 215-a, etc. ) or may use different carriers 215. Similarly, each cell or CC for the SCell group (e.g., including SCell 210) may use the same carrier 215-b or may use different carriers 215.

As described herein, PCell 205 (e.g., a serving cell for UE 115-a) may transmit one or more PUCCH configurations 220 (e.g., PUCCH-Config message (s) transmitted via RRC signaling) to UE 115-a configuring a first PUCCH for the PCell group and a second PUCCH for the SCell group. The first PUCCH and the second PUCCH may be transmitted to PCell 205 and SCell 210, respectively. In some cases, the first PUCCH may be referred to as a PUCCH PCell, a primary PUCCH, etc., and the second PUCCH may be referred to as a PUCCH SCell, a secondary PUCCH, etc. Additionally, the PCell group may be referred to as a primary PUCCH cell group, and the SCell group may be referred to as a secondary PUCCH cell group.

In some cases, UE 115-a may receive one or more downlink transmissions 225 from PCell 205, SCell 210, or both that necessitate UE 115-a to transmit HARQ ACK feedback (e.g., ACK/NACK feedback) to the respective PCell 205 or SCell 210 or both (e.g., based on which cell the downlink transmissions 225 are received) . For example, PCell 205 may transmit a downlink transmission 225-a, and SCell 210 may transmit a downlink transmission 225-b. Accordingly, UE 115-a may transmit HARQ ACK feedback for downlink transmission 225-a on the first PUCCH to PCell 205 and may transmit HARQ ACK feedback for downlink transmission 225-b on the second PUCCH to SCell 210. However, as described herein in FIG. 1, transmitting the HARQ ACK feedback on the respective PUCCHs may increase latency for one or both of the PCell group or the SCell group or both and delay receiving a retransmission of an unsuccessfully received/decoded downlink transmission 225.

Accordingly, UE 115-a may include a switching capability to support static or dynamic switching or both of transmission of the HARQ ACK feedback for the PCell group between the first PUCCH and the second PUCCH. For example, based on the switching capability, UE 115-a may perform a PUCCH determination 230 to determine on which PUCCH to transmit a UCI 235 (e.g., PUCCH transmission carrying, in part, the HARQ ACK feedback) statically or dynamically. As shown, UE 115-a may determine to transmit UCI 235 for both the PCell group and the SCell group on the second PUCCH originally configured for the SCell group only. Additionally, enablement of such dynamic switching and the timing of the switching (e.g., when enablement takes effect) may be specified in various configuration messages (e.g., PUCCH configuration (s) 220) .

In some cases, to enable the switching, a single PUCCH configuration 220 may be transmitted for PCell 205 (e.g., for the PCell group) , where the first PUCCH is configured in PCell 205. Accordingly, when SCell 210 is added to the CA configuration for UE 115-a, PCell 205 (e.g., the network) may reconfigure the single PUCCH configuration 220 in PCell 205 by adding PUCCH SCell parameter configuring the second PUCCH and enabling UE 115-a to transmit UCI 235 for the PCell group and the SCell group on the second PUCCH. In some cases, the single PUCCH configuration 220 and the reconfiguration of the single PUCCH configuration 220 may be transmitted to UE 115-a via RRC signaling.

However, the reconfiguration may include timing issues for UE 115-a not knowing when or how to transmit UCI 235 for both the PCell group and the SCell group on the second PUCCH based on processing the reconfiguration. In order to resolve the timing ambiguity issue of RRC message processing at UE 115-a (e.g., for processing the reconfiguration message to transmit UCI 235 on the second PUCCH) , different options may be used by UE 115-a to determine the timing of enablement for using the second PUCCH for transmitting UCI 235 for both the PCell group and the SCell group. For example, UE 115-a may use the second PUCCH for transmitting UCI 235 after a reconfiguration with synchronization is complete. Accordingly, UE 115-a may complete a random access channel (RACH) procedure in SCell 210 before using the second PUCCH in SCell 210.

Additionally or alternatively, PCell 205 (e.g., the network, serving cell, etc. ) may define a timer in an RRC reconfiguration message, where transmitting UCI 235 on the configured second PUCCH (e.g., PUCCH SCell) may start after the timer expires, and PCell 205 may ensure the second PUCCH for SCell 210 is activated before the timer expires. In some cases, a RRC processing time threshold for this PUCCH configuration (e.g., processing the reconfiguration message) may be defined for UE 115-a, where UE 115-a may start transmitting UCI 235 on the second PUCCH after the specified processing time threshold expires. In some cases, PCell 205 may reconfigure the single PUCCH configuration 220 to fallback transmitting UCI 235 (e.g., PUCCH transmission) from the configured second PUCCH on SCell 210 to the first PUCCH on PCell 205. Additionally or alternatively, UE 115-a may use an autonomous fallback to the first PUCCH on PCell 205 if the configured second PUCCH for SCell 210 is released.

In some implementations, to enable the switching, a single PUCCH configuration 220 may be transmitted for PCell 205 (e.g., for the PCell group) , where the first PUCCH is configured in PCell 205, and when SCell 210 is active, PCell 205 may reconfigure the single PUCCH configuration 220 by adding an enablement parameter for the second PUCCH on SCell 210 (e.g., an enabled PUCCH SCell parameter) . Accordingly, the enablement parameter may enable UE 115-a to transmit the second PUCCH carrying UCI 235 on the SCell 210 as indicated by the enablement parameter. In some cases, PCell 205 (e.g., the network) may reconfigure the single PUCCH configuration 220 by deleting the enablement parameter to enable UE 115-a to transmit UCI 235 on the first PUCCH on PCell 205 before deactivating/remove SCell 210. When transmitting the single PUCCH configuration 220 and the reconfiguration of single PUCCH configuration 220, PCell 205 may transmit the configuration and reconfiguration via RRC signaling.

Additionally or alternatively, PCell 205 (e.g., the network, serving cell, serving base station 105, etc. ) may transmit two PUCCH configurations 220 (e.g., via two PUCCH-Config messages transmitted via RRC signaling) for use to transmit UCI 235 on both the first PUCCH for PCell 205 and the second PUCCH for SCell 210. In some cases, the PUCCH signaling of PCell 205 (e.g., UCI for the PCell group) may be associated with both PUCCH configurations 220 in both the first PUCCH on PCell 205 and the second PUCCH on SCell 210. Subsequently, UE 115-a may use the first PUCCH on PCell 205 or the second PUCCH on SCell 210 based on an indication (e.g., an activation or deactivation trigger) for the second PUCCH on SCell 210 (e.g., SCell PUCCH, PUCCH SCell, etc. ) . For example, transmitting UCI 235 (e.g., PUCCH transmission) on the second PUCCH in SCell 210 (e.g., the PUCCH SCell) may be activated by a MAC CE (e.g., a MAC CE activation message) . Accordingly, if the second PUCCH in SCell 210 is activated, then UE 115-a may transmit UCI 235 on the second PUCCH in SCell 210, and any PUCCH transmissions in PCell 205 may be automatically deactivated. Alternatively, transmission of UCI 235 (e.g., PUCCH transmission) on the second PUCCH in SCell 210 may be deactivated by MAC CE as well (e.g., via a MAC CE deactivation message) , and if the second PUCCH in SCell 210 is deactivated, then transmission of UCI 235 on the first PUCCH in PCell 205 may be automatically activated.

Similarly, but based on a different activation or deactivation trigger indication, UE 115-a may determine which of the first PUCCH or the second PUCCH to use for transmitting UCI 235 based on an RRC message (e.g., an RRC reconfiguration activation or deactivation message) . For example, UCI 235 (e.g., PUCCH transmission) in the second PUCCH in SCell 210 may be activated directly upon RRC reconfiguration via RRC signaling without MAC-CE activation. Additionally, if the second PUCCH is activated, then transmitting UCI for the PCell group on the first PUCCH in PCell 205 may be automatically deactivated. Alternatively, transmitting UCI 235 for the PCell group in the second PUCCH in SCell 210 may be deactivated directly upon RRC reconfiguration via RRC signaling without MAC-CE activation, and if the second PUCCH is deactivated, then transmitting UCI 235 on the first PUCCH (e.g., PUCCH transmission) in PCell 205 may be automatically activated. In some cases, PCell 205 (e.g., the network) may use MAC-CE or DCI to activate/deactivate UCI transmissions in the second PUCCH in SCell 210.

Additionally or alternatively, PCell 205 may transmit the activation or deactivation trigger indication in a DCI to UE 115-a. For example, the DCI may be triggered for dynamical switching from the first PUCCH to the second PUCCH, or vice versa, for transmitting UCI 235 (e.g., HARQ ACK feedback) . Accordingly, for transmitting UCI 235 for the PCell group on the first PUCCH or second PUCCH, the DCI of a downlink grant may configure the transmission of UCI 235 for the PCell group on either the first PUCCH in PCell 205 or in the second PUCCH in SCell 210. By using the DCI (e.g., and downlink grant) to indicate which PUCCH to use for transmitting UCI 235 for the PCell group, UE 115-a may support dynamic switching between the first PUCCH in PCell 205 and the second PUCCH in SCell 210. In some cases, PCell 205 and UE 115-a may use the DCI for determining a PUCCH to transmit UCI 235 for the PCell group when UCI 235 is carrying HARQ ACK feedback but not for carrying channel state information (e.g., CSI reports) . For example, CSI may include a fixed timeline, so dynamically switching which PUCCH to transmit UCI 235 may affect CSI reports transmitted by UE 115-a.

FIGs. 3A and 3B illustrate examples of

PUCCH configurations

300 and 301 that support ACK feedback for CA in accordance with aspects of the present disclosure. In some examples,

PUCCH configurations

300 and 301 may implement aspects of wireless communications systems 100 or wireless communications system 200.

PUCCH configurations

300 and 301 may include a PCell group 305 and an SCell group 310 that a UE 115 uses as part of a CA configuration to simultaneously communicate with multiple cells at once. Each cell group may include a primary cell or CC (e.g., a special cell (SpCell) ) for transmitting and receiving scheduling information for the corresponding cell group. For example, PCell group 305 may include a PCell, and SCell group 310 may include a PSCell.

Additionally, each cell group may include one or more downlink CCs 315 for receiving downlink transmissions for PCell group 305 and SCell group 310 and one or more uplink CCs 320 for transmitting uplink messages to one or more cells in each of PCell group 305 and SCell group 310. In some cases, the UE 115 may transmit UCI 325 for each cell in each PCell group 305 and SCell group 310 based on attempting to receive and decode the downlink transmissions received on downlink CCs 315. For example, UCI 325 may include HARQ ACK feedback to indicate whether the UE 115 successfully received and decoded the downlink transmissions and, if necessary, may indicate for a cell whose downlink transmission was not received or decoded properly to retransmit the downlink transmission (e.g., based on the UE 115 transmitting a NACK) . Accordingly, the UE 115 may transmit UCI 325 for each cell group on a single, respective PUCCH 330 configured by the network (e.g., PCell in PCell group 305) . In some cases, the PUCCHs 330 may be configured via RRC signaling (e.g., in PUCCH-Config message (s) ) .

As shown in PUCCH configuration 300, PCell group 305 may include a first PUCCH 330-a (e.g., primary PUCCH, PUCCH PCell, etc. ) , and SCell group 310 may include a second PUCCH 330-b (e.g., secondary PUCCH, PUCCH SCell, etc. ) . Subsequently, the UE 115 may transmit UCI 325 for all cells in PCell group 305 on first PUCCH 330-a and may transmit UCI 325 for all cells in SCell group 310 on second PUCCH 330-b. However, as described herein with reference to FIGs. 1 and 2, transmitting the UCI 325 for all cells in PCell group 305 on first PUCCH 330-a may cause a delay in transmitting UCI 325 and, as a result, also delay receiving a retransmission of any failed downlink transmissions.

As discussed above with reference to FIG. 2 and as shown in PUCCH configuration 301, the UE 115 may transmit UCI 325 for all cells in PCell group 305 in second PUCCH 330-b along with UCI 325 for all cells in SCell group 310. The UE 115 may transmit UCI 325 for PCell group 305 based on a switching capability to switch transmissions from first PUCCH 330-a to second PUCCH 330-b. Accordingly, the UE 115 may determine when to transmit UCI 325 for PCell group 305 in second PUCCH 330-b or when transmitting UCI 325 for PCell group 305 in second PUCCH 330-b is enabled based on the techniques described herein with reference to FIG. 2. Additionally, while three cells/CCs are shown in each cell group, it is to be understood that more or less than three cells/CCs may be included in each cell group.

FIGs. 4A and 4B illustrate examples of

downlink retransmission signalings

400 and 401 that supports ACK feedback for CA in accordance with aspects of the present disclosure. In some examples,

downlink retransmission signalings

400 and 401 may implement aspects of wireless communications systems 100 wireless communications system 200. Downlink retransmission signalings 400 and 401 may include a PCell group 405 that includes at least a PCell 410 and an SCell group 415 that includes one or more SCells 420 (e.g., one SCell 420 may be an PSCell) . A UE 115 may support a CA configuration that includes PCell group 405 and SCell group 415.

In some cases, the UE 115 may use downlink retransmission signaling 400 to transmit HARQ ACK feedback (e.g., UCI) for a received downlink transmission on a physical downlink shared channel (PDSCH) 425, where the HARQ ACK feedback is transmitted on a PUCCH 430. For example, PCell 410 may include one or more downlink slots (e.g., or different length TTIs) , one or more uplink slots, and one or more synchronization signal (SS) /physical broadcast channel (PBCH) blocks (SSBs) . Each of the downlink slots may include a PDSCH 425 for receiving the downlink transmissions, and the uplink slots and SSBs may include a PUCCH 430 (e.g., located at the end of the slot designated for the uplinks or SSBs) for transmitting the HARQ ACK feedback. However, depending on which PUCCH 430 is used for transmitting the HARQ ACK feedback, a delay with transmitting the HARQ ACK feedback and receiving a retransmission for a failed downlink transmission (e.g., unsuccessful reception or decoding) may vary.

As shown with downlink retransmission signaling 400, the UE 115 may receive a PDSCH 425 in a first downlink slot on PCell 410. However, the first opportunity to transmit the HARQ ACK feedback indicating that the PDSCH 425 in the first downlink slot was not correctly received or decoded (e.g., the UE 115 transmits a NACK) may not occur until three slots later when a first available PUCCH 430 is available in an SSB slot. Subsequently, PCell 410 may then not send a retransmission of the failed PDSCH 425 until a next available downlink slot occurring two slots later. As such, the UE 115 may experience a retransmission delay 435-a after first not receiving/decoding the PDSCH 425 in the first downlink slot and receiving the retransmission of the PDSCH 425. Alternatively, SCell group 415 may include a first SCell 420-a that includes all downlink slots and a second SCell 420-b that includes all uplink slots. Accordingly, if the UE 115 fails to receive or decode a PDSCH 425 in a first downlink slot from SCell 420-a, the UE 115 may transmit the NACK in a PUCCH 430 of a subsequent uplink slot (e.g., next occurring slot after the first downlink slot of SCell 420-a) of SCell 420-b. SCell 420-a may then retransmit the PDSCH 425 in a subsequent downlink slot (e.g., next occurring slot after the uplink slot after the uplink slot carrying the PUCCH 430 with the NACK) , resulting a shortened retransmission delay.

Accordingly, as described herein and as shown in downlink retransmission signaling 401, the UE 115 may transmit a NACK (e.g., UCI) for an unsuccessful reception of a PDSCH 425 in a first downlink slot of PCell 410 in a PUCCH 430 of SCell 420-b and then may receive the retransmitted PDSCH 425 in a subsequent downlink slot from PCell 410. As such, the UE 115 may experience a retransmission delay 435-b for receiving a retransmission of a PDSCH 425 for PCell 410, which is shorter then retransmission delay 435-a as illustrated in downlink retransmission signaling 400. In some cases,

downlink retransmission signalings

400 and 401 may represent a TDD+FDD CA configuration with PCell 410 using a TDD configuration and the SCells 420 in SCell group 415 using FDD configurations. Additional CA configurations may benefit from the PUCCH enhancement of the UE 115 switching between PUCCHs of PCell group 405 and SCell group 415 to transmit HARQ ACK feedback (e.g., UCI) for PCell group 405.

FIG. 5 illustrates an example of a process flow 500 that supports ACK feedback for CA in accordance with aspects of the present disclosure. In some examples, process flow 500 may implement aspects of wireless communications systems 100 or wireless communications system 200. Process flow 500 may include a UE 115-b, a PCell 505, and an SCell 510, where UE 115-b corresponds to a UE 115 as described herein with reference to FIGs. 1–4 and PCell 505 and SCell 510 correspond to base stations 105 or cells on a base station 105 as described herein with reference to FIGs. 1–4. While PCell 505 and SCell 510 are shown as separate base stations 105, it is to be understood that both PCell 505 and SCell 510 may be part of the same base station 105. Additionally, as described herein, PCell 505 may be part of a PCell group (e.g., a group of cells or CCs configured for PCell communications, such as one PCell and one or more SCells configured for primary communications) , and SCell 510 may be part of an SCell group (e.g., a group of cells or CCs configured for SCell communications, such as one PSCell and one or more SCells configured for secondary communications) . In some cases, SCell 210 may represent a PSCell of the SCell group.

In the following description of the process flow 500, the operations between UE 115-b, PCell 505, and SCell 510 may be transmitted in a different order than the order shown, or the operations performed by UE 115-b, PCell 505, and SCell 510 may be performed in different orders or at different times. Some operations may also be left out of the process flow 500, or other operations may be added to the process flow 500. It is to be understood that while UE 115-b, PCell 505, and SCell 510 are shown performing a number of the operations of process flow 500, any wireless device may perform the operations shown

At 515, UE 115-b may identify a CA configuration including a PCell group having a PCell 505 configured with a primary uplink control channel (e.g., primary PUCCH, first PUCCH, PUCCH PCell, etc. ) and an SCell group having an SCell 510 configured with a secondary uplink control channel (e.g., secondary PUCCH, second PUCCH, PUCCH SCell, etc. ) . Additionally, PCell 505 or SCell 510 or both may identify the CA configuration as well. In some cases, the PCell group may include a first SCS, and the SCell group may include a second SCS that is different than the first SCS.

At 520, UE 115-b may identify a switching capability supporting at least dynamic switching of transmission of UCI for the PCell group between the primary uplink control channel and the secondary uplink control channel. Additionally, PCell 505 or SCell 510 or both may identify that UE 115-b has this switching capability.

At 525, UE 115-b may receive one or more uplink control channel configuration (e.g., PUCCH configuration) messages from PCell 505. For example, UE 115-b may receive an uplink control channel configuration message for the primary uplink control channel including an SCell uplink control channel parameter, where the SCell uplink control channel parameter enables UE 115-b to transmit the UCI for the PCell group on the secondary uplink control channel. In some cases, UE 115-b may identify that the secondary uplink control channel is enabled based on a reconfiguration of the CA configuration, where the reconfiguration results from completion of a RACH (e.g., random access) procedure with an SCell of the SCell group. Additionally or alternatively, UE 115-b may identify that the secondary uplink control channel is enabled based on expiration of a reconfiguration timer (e.g., RRC reconfiguration timer) .

At 530, UE 115-b may select the secondary uplink control channel to transmit the UCI for the PCell group based on the switching capability. In some cases, UE 115-b may receive an uplink control channel configuration message for the primary uplink control channel, identify an activation of the SCell group, and may receive an uplink control channel reconfiguration message for the primary uplink control channel including an SCell uplink control channel enablement parameter, where the SCell uplink control channel enablement parameter enables the UE to transmit the UCI for the PCell group on the secondary uplink control channel. Additionally or alternatively, UE 115-b may receive a first uplink control channel configuration message for the primary uplink control channel and may receive a second uplink control channel configuration message for the secondary uplink control channel, where the secondary uplink control channel is selected to transmit the UCI for the PCell group based on the first uplink control channel configuration message and the second uplink control channel configuration message.

At 535, UE 115-b may transmit the UCI for the PCell group on the selected secondary uplink control channel. In some cases, the UCI may include ACK feedback (e.g., HARQ ACK feedback, ACK/NACK feedback, etc. ) , CSI reports, or a combination thereof. Additionally, UE 115-b may transmit the UCI for the PCell group on the secondary uplink control channel after expiration of a configuration processing time threshold. In some cases, UE 115-b may receive an indication for enabling the secondary uplink control channel, where the UE transmits the UCI for the PCell group on the secondary uplink control channel based on the indication. For example, the indication may include DCI with a downlink grant configuring the UE to transmit the UCI on the secondary uplink control channel.

At 540, UE 115-b may receive an indication to switch from the secondary uplink control channel to the primary uplink control channel for transmitting the UCI. In some cases, UE 115-b may release the SCell group and may select the primary uplink control channel for transmitting the UCI for the PCell group based on releasing the SCell group. In some cases, UE 115-b may receive a second uplink control channel reconfiguration message for the primary uplink control channel deleting the SCell uplink control channel enablement parameter, where the second uplink control channel reconfiguration message indicates for the UE to transmit the UCI on the primary uplink control channel based on the SCell uplink control channel enablement parameter being deleted.

Additionally or alternatively, UE 115-b may receive an indicator for disabling the secondary uplink control channel, where the UE transmits the UCI for the PCell group on the primary uplink control channel based on the deactivation trigger. In some cases, the indicator may be received via MAC CE, RRC signaling, DCI signaling, or a combination thereof.

FIG. 6 shows a block diagram 600 of a device 605 that supports ACK feedback for CA in accordance with aspects of the present disclosure. The device 605 may be an example of aspects of a UE 115 as described herein. The device 605 may include a receiver 610, a UE communications manager 615, and a transmitter 620. The device 605 may also include a processor. Each of these components may be in communication with one another (e.g., via one or more buses) .

The receiver 610 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 ACK feedback for CA, etc. ) . Information may be passed on to other components of the device 605. The receiver 610 may be an example of aspects of the transceiver 920 described with reference to FIG. 9. The receiver 610 may utilize a single antenna or a set of antennas.

The UE communications manager 615 may identify a CA configuration including a PCell group having a PCell configured with a primary uplink control channel and an SCell group having an SCell configured with a secondary uplink control channel. Additionally, the UE communications manager 615 may identify that the UE has a switching capability supporting at least dynamic switching of transmission of UCI for the PCell group between the primary uplink control channel and the secondary uplink control channel. In some cases, the UE communications manager 615 may select the secondary uplink control channel to transmit the UCI for the PCell group based on the switching capability of the UE. Subsequently, the UE communications manager 615 may transmit the UCI for the PCell group on the selected secondary uplink control channel. The UE communications manager 615 may be an example of aspects of the UE communications manager 910 described herein.

The UE communications manager 615, or its sub-components, may 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 UE communications manager 615, or its sub-components may 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.

The UE communications manager 615, or its sub-components, may be physically located at various positions, including being distributed such that portions of functions are implemented at different physical locations by one or more physical components. In some examples, the UE communications manager 615, or its sub-components, may be a separate and distinct component in accordance with various aspects of the present disclosure. In some examples, the UE communications manager 615, or its sub-components, may 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.

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

In some examples, the communications manager 615 may be implemented as an integrated circuit or chipset for a mobile device modem, and the receiver 610 and transmitter 620 may be implemented as analog components (e.g., amplifiers, filters, antennas) coupled with the mobile device modem to enable wireless transmission and reception over one or more bands.

The communications manager 615 as described herein may be implemented to realize one or more potential advantages. One implementation may allow the device 605 to transmit UCI feedback for cells in the primary PUCCH cell group on PUCCH SCell. Based on the techniques for transmitting UCI feedback for cells in the primary PUCCH cell group on PUCCH SCell, the device 605 may reduce the delay of feedback and, therefore, may support improved feedback procedures.

As such, the device 605 may increase the likelihood of timely transmitting feedback and, accordingly, may communicate over the channel with a greater likelihood of successful communications. In some examples, based on a greater likelihood of successful communications, the device 605 may more efficiently power a processor or one or more processing units associated with a PUCCH configuration and transmitting and receiving communications, which may enable the device 605 to save power and increase battery life.

FIG. 7 shows a block diagram 700 of a device 705 that supports ACK feedback for CA in accordance with aspects of the present disclosure. The device 705 may be an example of aspects of a device 605, or a UE 115 as described herein. The device 705 may include a receiver 710, a UE communications manager 715, and a transmitter 740. The device 705 may also include a processor. Each of these components may be in communication with one another (e.g., via one or more buses) .

The receiver 710 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 ACK feedback for CA, etc. ) . Information may be passed on to other components of the device 705. The receiver 710 may be an example of aspects of the transceiver 920 described with reference to FIG. 9. The receiver 710 may utilize a single antenna or a set of antennas.

The UE communications manager 715 may be an example of aspects of the UE communications manager 615 as described herein. The UE communications manager 715 may include a CA configuration identifier 720, a switching capability identifier 725, a PUCCH selector 730, and an UCI transmitter 735. The UE communications manager 715 may be an example of aspects of the UE communications manager 910 described herein.

The CA configuration identifier 720 may identify a CA configuration including a PCell group having a PCell configured with a primary uplink control channel and an SCell group having an SCell configured with a secondary uplink control channel.

The switching capability identifier 725 may identify that the UE has a switching capability supporting at least dynamic switching of transmission of UCI for the PCell group between the primary uplink control channel and the secondary uplink control channel.

The PUCCH selector 730 may select the secondary uplink control channel to transmit the UCI for the PCell group based on the switching capability of the UE.

The UCI transmitter 735 may transmit the UCI for the PCell group on the selected secondary uplink control channel.

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

FIG. 8 shows a block diagram 800 of a UE communications manager 805 that supports ACK feedback for CA in accordance with aspects of the present disclosure. The UE communications manager 805 may be an example of aspects of a UE communications manager 615, a UE communications manager 715, or a UE communications manager 910 described herein. The UE communications manager 805 may include a CA configuration identifier 810, a switching capability identifier 815, a PUCCH selector 820, an UCI transmitter 825, a PUCCH SCell parameter component 830, a PUCCH SCell enablement component 835, and a multi-PUCCH configuration component 840. Each of these modules may communicate, directly or indirectly, with one another (e.g., via one or more buses) .

The CA configuration identifier 810 may identify a CA configuration including a PCell group having a PCell configured with a primary uplink control channel and an SCell group having an SCell configured with a secondary uplink control channel. In some cases, the PCell group may include a first subcarrier spacing, and the SCell group may include a second subcarrier spacing that is different than the first subcarrier spacing.

The switching capability identifier 815 may identify that the UE has a switching capability supporting at least dynamic switching of transmission of UCI for the PCell group between the primary uplink control channel and the secondary uplink control channel.

The PUCCH selector 820 may select the secondary uplink control channel to transmit the UCI for the PCell group based on the switching capability of the UE.

The UCI transmitter 825 may transmit the UCI for the PCell group on the selected secondary uplink control channel. In some cases, the UCI may include ACK feedback, CSI reports, or a combination thereof.

The PUCCH SCell parameter component 830 may receive an uplink control channel configuration message for the primary uplink control channel including an SCell uplink control channel parameter, where the SCell uplink control channel parameter enables the UE to transmit the UCI for the PCell group on the secondary uplink control channel. In some examples, the PUCCH SCell parameter component 830 may identify that the secondary uplink control channel is enabled based on a reconfiguration of the CA configuration, where the reconfiguration results from completion of a random access (e.g., RACH) procedure with an SCell of the SCell group. Additionally or alternatively, the PUCCH SCell parameter component 830 may identify that the secondary uplink control channel is enabled based on expiration of a reconfiguration timer. In some examples, the PUCCH SCell parameter component 830 may transmit the UCI for the PCell group on the secondary uplink control channel after expiration of a configuration processing time threshold.

In some examples, the PUCCH SCell parameter component 830 may receive an indication to switch from the secondary uplink control channel to the primary uplink control channel for transmitting the UCI. Additionally or alternatively, the PUCCH SCell parameter component 830 may release the SCell group and may select the primary uplink control channel for transmitting the UCI for the PCell group based on releasing the SCell group.

The PUCCH SCell enablement component 835 may receive an uplink control channel configuration message for the primary uplink control channel and may identify an activation of the SCell group. Accordingly, the PUCCH SCell enablement component 835 may receive an uplink control channel reconfiguration message for the primary uplink control channel including an SCell uplink control channel enablement parameter, where the SCell uplink control channel enablement parameter enables the UE to transmit the UCI for the PCell group on the secondary uplink control channel. In some examples, the PUCCH SCell enablement component 835 may receive a second uplink control channel reconfiguration message for the primary uplink control channel deleting the SCell uplink control channel enablement parameter, where the second uplink control channel reconfiguration message indicates for the UE to transmit the UCI on the primary uplink control channel based on the SCell uplink control channel enablement parameter being deleted.

The multi-PUCCH configuration component 840 may receive a first uplink control channel configuration message for the primary uplink control channel and may receive a second uplink control channel configuration message for the secondary uplink control channel, where the secondary uplink control channel is selected to transmit the UCI for the PCell group based on the first uplink control channel configuration message and the second uplink control channel configuration message. In some examples, the multi-PUCCH configuration component 840 may receive an indication for enabling the secondary uplink control channel, where the UE transmits the UCI for the PCell group on the secondary uplink control channel based on the indication.

Additionally or alternatively, the multi-PUCCH configuration component 840 may receive an indicator for disabling the secondary uplink control channel, where the UE transmits the UCI for the PCell group on the primary uplink control channel based on the indicator for disabling the secondary uplink control channel. In some cases, the indicator may be received via MAC CE, RRC signaling, DCI signaling, or a combination thereof. For example, the indication may include DCI with a downlink grant configuring the UE to transmit the UCI on the secondary uplink control channel.

FIG. 9 shows a diagram of a system 900 including a device 905 that supports ACK feedback for CA in accordance with aspects of the present disclosure. The device 905 may be an example of or include the components of device 605, device 705, or a UE 115 as described herein. The device 905 may include components for bi-directional voice and data communications including components for transmitting and receiving communications, including a UE communications manager 910, an I/O controller 915, a transceiver 920, an antenna 925, memory 930, and a processor 940. These components may be in electronic communication via one or more buses (e.g., bus 945) .

The UE communications manager 910 may identify a CA configuration including a PCell group having a PCell configured with a primary uplink control channel and an SCell group having an SCell configured with a secondary uplink control channel. Additionally, the UE communications manager 910 may identify that the UE has a switching capability supporting at least dynamic switching of transmission of UCI for the PCell group between the primary uplink control channel and the secondary uplink control channel. In some cases, the UE communications manager 910 may select the secondary uplink control channel to transmit the UCI for the PCell group based on the switching capability of the UE. Subsequently, the UE communications manager 910 may transmit the UCI for the PCell group on the selected secondary uplink control channel.

The I/O controller 915 may manage input and output signals for the device 905. The I/O controller 915 may also manage peripherals not integrated into the device 905. In some cases, the I/O controller 915 may represent a physical connection or port to an external peripheral. In some cases, the I/O controller 915 may utilize an operating system such as

or another known operating system. In other cases, the I/O controller 915 may represent or interact with a modem, a keyboard, a mouse, a touchscreen, or a similar device. In some cases, the I/O controller 915 may be implemented as part of a processor. In some cases, a user may interact with the device 905 via the I/O controller 915 or via hardware components controlled by the I/O controller 915.

The transceiver 920 may communicate bi-directionally, via one or more antennas, wired, or wireless links as described herein. For example, the transceiver 920 may represent a wireless transceiver and may communicate bi-directionally with another wireless transceiver. The transceiver 920 may 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.

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

The memory 930 may include random-access memory (RAM) and read-only memory (ROM) . The memory 930 may 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 may contain, among other things, a basic I/O system (BIOS) which may control basic hardware or software operation such as the interaction with peripheral components or devices.

The processor 940 may include an intelligent hardware device, (e.g., a general-purpose processor, a DSP, a central processing unit (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 cases, the processor 940 may be configured to operate a memory array using a memory controller. In other cases, a 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., the memory 930) to cause the device 905 to perform various functions (e.g., functions or tasks supporting ACK feedback for CA) .

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

FIG. 10 shows a block diagram 1000 of a device 1005 that supports ACK feedback for CA in accordance with aspects of the present disclosure. The device 1005 may be an example of aspects of a base station 105 as described herein. The device 1005 may include a receiver 1010, a base station communications manager 1015, and a transmitter 1020. The device 1005 may also include a processor. Each of these components may be in communication with one another (e.g., via one or more buses) .

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 ACK feedback for CA, etc. ) . Information may be passed on to other components of the device 1005. The receiver 1010 may be an example of aspects of the transceiver 1320 described with reference to FIG. 13. The receiver 1010 may utilize a single antenna or a set of antennas.

The base station communications manager 1015 may identify, for communications with a UE, a CA configuration including a PCell group having a PCell configured with a primary uplink control channel and an SCell group having an SCell configured with a secondary uplink control channel. Additionally, the base station communications manager 1015 may identify that the UE has a switching capability supporting at least dynamic switching of transmission of UCI for the PCell group between the primary uplink control channel and the secondary uplink control channel. In some cases, the base station communications manager 1015 may receive, from the UE, the UCI for the PCell group on the secondary uplink control channel based on the switching capability. The base station communications manager 1015 may be an example of aspects of the base station communications manager 1310 described herein.

The base station communications manager 1015, or its sub-components, may 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 base station communications manager 1015, or its sub-components may 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.

The base station communications manager 1015, or its sub-components, may be physically located at various positions, including being distributed such that portions of functions are implemented at different physical locations by one or more physical components. In some examples, the base station communications manager 1015, or its sub-components, may be a separate and distinct component in accordance with various aspects of the present disclosure. In some examples, the base station communications manager 1015, or its sub-components, may be combined with one or more other hardware components, including but not limited to an 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.

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

FIG. 11 shows a block diagram 1100 of a device 1105 that supports ACK feedback for CA in accordance with aspects of the present disclosure. The device 1105 may be an example of aspects of a device 1005, or a base station 105 as described herein. The device 1105 may include a receiver 1110, a base station communications manager 1115, and a transmitter 1135. The device 1105 may also include a processor. Each of these components may be in communication with one another (e.g., via one or more buses) .

The receiver 1110 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 ACK feedback for CA, etc. ) . Information may be passed on to other components of the device 1105. The receiver 1110 may be an example of aspects of the transceiver 1320 described with reference to FIG. 13. The receiver 1110 may utilize a single antenna or a set of antennas.

The base station communications manager 1115 may be an example of aspects of the base station communications manager 1015 as described herein. The base station communications manager 1115 may include a CA configuration component 1120, a switching capability component 1125, and an UCI receiver 1130. The base station communications manager 1115 may be an example of aspects of the base station communications manager 1310 described herein.

The CA configuration component 1120 may identify, for communications with a UE, a CA configuration including a PCell group having a PCell configured with a primary uplink control channel and an SCell group having an SCell configured with a secondary uplink control channel.

The switching capability component 1125 may identify that the UE has a switching capability supporting at least dynamic switching of transmission of UCI for the PCell group between the primary uplink control channel and the secondary uplink control channel.

The UCI receiver 1130 may receive, from the UE, the UCI for the PCell group on the secondary uplink control channel based on the switching capability.

The transmitter 1135 may transmit signals generated by other components of the device 1105. In some examples, the transmitter 1135 may be collocated with a receiver 1110 in a transceiver module. For example, the transmitter 1135 may be an example of aspects of the transceiver 1320 described with reference to FIG. 13. The transmitter 1135 may utilize a single antenna or a set of antennas.

FIG. 12 shows a block diagram 1200 of a base station communications manager 1205 that supports ACK feedback for CA in accordance with aspects of the present disclosure. The base station communications manager 1205 may be an example of aspects of a base station communications manager 1015, a base station communications manager 1115, or a base station communications manager 1310 described herein. The base station communications manager 1205 may include a CA configuration component 1210, a switching capability component 1215, an UCI receiver 1220, a PUCCH configuration transmitter 1225, a PUCCH SCell enablement transmitter 1230, and an indication component 1235. Each of these modules may communicate, directly or indirectly, with one another (e.g., via one or more buses) .

The CA configuration component 1210 may identify, for communications with a UE, a CA configuration including a PCell group having a PCell configured with a primary uplink control channel and an SCell group having an SCell configured with a secondary uplink control channel. In some cases, the PCell group may include a first subcarrier spacing, and the SCell group may include a second subcarrier spacing that is different than the first subcarrier spacing.

The switching capability component 1215 may identify that the UE has a switching capability supporting at least dynamic switching of transmission of UCI for the PCell group between the primary uplink control channel and the secondary uplink control channel.

The UCI receiver 1220 may receive, from the UE, the UCI for the PCell group on the secondary uplink control channel based on the switching capability. In some cases, the UCI may include ACK feedback, CSI reports, or a combination thereof.

The PUCCH configuration transmitter 1225 may transmit, to the UE, an uplink control channel configuration message for the primary uplink control channel including an SCell uplink control channel parameter, where the SCell uplink control channel parameter enables the UE to transmit the UCI for the PCell group on the secondary uplink control channel. In some examples, the PUCCH configuration transmitter 1225 may transmit, to the UE, an indication to switch from the secondary uplink control channel to the primary uplink control channel for transmitting the UCI, where the UCI is received on the primary uplink control channel based on the transmitted indication to switch. Additionally, the UCI for the PCell group may be received on the secondary uplink control channel based on a reconfiguration of the CA configuration, completion of a random access procedure for the SCell of the SCell group, a reconfiguration timer expiration, a processing time threshold expiration, or a combination thereof.

The PUCCH SCell enablement transmitter 1230 may transmit an uplink control channel configuration message for the primary uplink control channel and may identify an activation of the SCell group. Accordingly, the PUCCH SCell enablement transmitter 1230 may transmit an uplink control channel reconfiguration message for the primary uplink control channel including an SCell uplink control channel enablement parameter, where the SCell uplink control channel enablement parameter enables the UE to transmit the UCI for the PCell group on the secondary uplink control channel. In some examples, the PUCCH SCell enablement transmitter 1230 may transmit a second uplink control channel reconfiguration message for the primary uplink control channel deleting the SCell uplink control channel enablement parameter, where the second uplink control channel reconfiguration message indicates for the UE to transmit the UCI on the primary uplink control channel based on the SCell uplink control channel enablement parameter being deleted.

The indication component 1235 may transmit a first uplink control channel configuration message for the primary uplink control channel and may transmit a second uplink control channel configuration message for the secondary uplink control channel, where the UCI for the PCell group is received on the secondary uplink control channel based on the first uplink control channel configuration message and the second uplink control channel configuration message. In some examples, the indication component 1235 may transmit an indication for enabling the secondary uplink control channel, where the UCI for the PCell group is received on the secondary uplink control channel based on the indication.

Additionally or alternatively, the indication component 1235 may transmit an indicator for disabling the secondary uplink control channel, where the UCI for the PCell group is received on the primary uplink control channel based on the indicator for disabling the secondary uplink control channel. In some cases, the indicator may be transmitted via MAC CE, RRC signaling, DCI signaling, or a combination thereof. For example, the indication may include DCI with a downlink grant configuring the UE to transmit the UCI on the secondary uplink control channel, and where the UCI is received on the secondary uplink control channel based at least according to the configured uplink control channel.

FIG. 13 shows a diagram of a system 1300 including a device 1305 that supports ACK feedback for CA in accordance with aspects of the present disclosure. The device 1305 may be an example of or include the components of device 1005, device 1105, or a base station 105 as described herein. The device 1305 may include components for bi-directional voice and data communications including components for transmitting and receiving communications, including a base station 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 may be in electronic communication via one or more buses (e.g., bus 1350) .

The base station communications manager 1310 may identify, for communications with a UE, a CA configuration including a PCell group having a PCell configured with a primary uplink control channel and an SCell group having an SCell configured with a secondary uplink control channel. Additionally, the base station communications manager 1310 may identify that the UE has a switching capability supporting at least dynamic switching of transmission of UCI for the PCell group between the primary uplink control channel and the secondary uplink control channel. In some cases, the base station communications manager 1310 may receive, from the UE, the UCI for the PCell group on the secondary uplink control channel based on the switching capability.

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

The transceiver 1320 may communicate bi-directionally, via one or more antennas, wired, or wireless links as described herein. For example, the transceiver 1320 may represent a wireless transceiver and may communicate bi-directionally with another wireless transceiver. The transceiver 1320 may 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.

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

The memory 1330 may include RAM, ROM, or a combination thereof. The memory 1330 may 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 may contain, among other things, a BIOS which may control basic hardware or software operation such as the interaction with peripheral components or devices.

The processor 1340 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, a discrete gate or transistor logic component, a discrete hardware component, or any combination thereof) . In some cases, the processor 1340 may be configured to operate a memory array using a memory controller. In some cases, a memory controller may be integrated into processor 1340. The processor 1340 may 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 supporting ACK feedback for CA) .

The inter-station communications manager 1345 may manage communications with other base station 105 and may include a controller or scheduler for controlling communications with UEs 115 in cooperation with other base stations 105. For example, the inter-station communications manager 1345 may coordinate scheduling for transmissions to UEs 115 for various interference mitigation techniques such as beamforming or joint transmission. In some examples, the inter-station communications manager 1345 may provide an X2 interface within an LTE/LTE-A wireless communication network technology to provide communication between base stations 105.

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

FIG. 14 shows a flowchart illustrating a method 1400 that supports ACK feedback for CA in accordance with aspects of the present disclosure. The operations of method 1400 may be implemented by a UE 115 or its components as described herein. For example, the operations of method 1400 may be performed by a UE communications manager as described with reference to FIGs. 6 through 9. In some examples, a UE may execute a set of instructions to control the functional elements of the UE to perform the functions described herein. Additionally or alternatively, a UE may perform aspects of the functions described herein using special-purpose hardware.

At 1405, the UE may identify a CA configuration including a PCell group having a PCell configured with a primary uplink control channel and an SCell group having an SCell configured with a secondary uplink control channel. The operations of 1405 may be performed according to the methods described herein. In some examples, aspects of the operations of 1405 may be performed by a CA configuration identifier as described with reference to FIGs. 6 through 9.

At 1410, the UE may identify that the UE has a switching capability supporting at least dynamic switching of transmission of UCI for the PCell group between the primary uplink control channel and the secondary uplink control channel. The operations of 1410 may be performed according to the methods described herein. In some examples, aspects of the operations of 1410 may be performed by a switching capability identifier as described with reference to FIGs. 6 through 9.

At 1415, the UE may select the secondary uplink control channel to transmit the UCI for the PCell group based on the switching capability of the UE. The operations of 1415 may be performed according to the methods described herein. In some examples, aspects of the operations of 1415 may be performed by a PUCCH selector as described with reference to FIGs. 6 through 9.

At 1420, the UE may transmit the UCI for the PCell group on the selected secondary uplink control channel. The operations of 1420 may be performed according to the methods described herein. In some examples, aspects of the operations of 1420 may be performed by an UCI transmitter as described with reference to FIGs. 6 through 9.

FIG. 15 shows a flowchart illustrating a method 1500 that supports ACK feedback for CA in accordance with aspects of the present disclosure. The operations of method 1500 may be implemented by a UE 115 or its components as described herein. For example, the operations of method 1500 may be performed by a UE communications manager as described with reference to FIGs. 6 through 9. In some examples, a UE may execute a set of instructions to control the functional elements of the UE to perform the functions described herein. Additionally or alternatively, a UE may perform aspects of the functions described herein using special-purpose hardware.

At 1505, the UE may identify a CA configuration including a PCell group having a PCell configured with a primary uplink control channel and an SCell group having an SCell configured with a secondary uplink control channel. The operations of 1505 may be performed according to the methods described herein. In some examples, aspects of the operations of 1505 may be performed by a CA configuration identifier as described with reference to FIGs. 6 through 9.

At 1510, the UE may identify that the UE has a switching capability supporting at least dynamic switching of transmission of UCI for the PCell group between the primary uplink control channel and the secondary uplink control channel. The operations of 1510 may be performed according to the methods described herein. In some examples, aspects of the operations of 1510 may be performed by a switching capability identifier as described with reference to FIGs. 6 through 9.

At 1515, the UE may receive an uplink control channel configuration message for the primary uplink control channel including an SCell uplink control channel parameter, where the SCell uplink control channel parameter enables the UE to transmit the UCI for the PCell group on the secondary uplink control channel. The operations of 1515 may be performed according to the methods described herein. In some examples, aspects of the operations of 1515 may be performed by a PUCCH SCell parameter component as described with reference to FIGs. 6 through 9.

At 1520, the UE may select the secondary uplink control channel to transmit the UCI for the PCell group based on the switching capability of the UE. The operations of 1520 may be performed according to the methods described herein. In some examples, aspects of the operations of 1520 may be performed by a PUCCH selector as described with reference to FIGs. 6 through 9.

At 1525, the UE may transmit the UCI for the PCell group on the selected secondary uplink control channel. The operations of 1525 may be performed according to the methods described herein. In some examples, aspects of the operations of 1525 may be performed by an UCI transmitter as described with reference to FIGs. 6 through 9.

FIG. 16 shows a flowchart illustrating a method 1600 that supports ACK feedback for CA in accordance with aspects of the present disclosure. The operations of method 1600 may be implemented by a UE 115 or its components as described herein. For example, the operations of method 1600 may be performed by a UE communications manager as described with reference to FIGs. 6 through 9. In some examples, a UE may execute a set of instructions to control the functional elements of the UE to perform the functions described herein. Additionally or alternatively, a UE may perform aspects of the functions described herein using special-purpose hardware.

At 1605, the UE may identify a CA configuration including a PCell group having a PCell configured with a primary uplink control channel and an SCell group having an SCell configured with a secondary uplink control channel. The operations of 1605 may be performed according to the methods described herein. In some examples, aspects of the operations of 1605 may be performed by a CA configuration identifier as described with reference to FIGs. 6 through 9.

At 1610, the UE may identify that the UE has a switching capability supporting at least dynamic switching of transmission of UCI for the PCell group between the primary uplink control channel and the secondary uplink control channel. The operations of 1610 may be performed according to the methods described herein. In some examples, aspects of the operations of 1610 may be performed by a switching capability identifier as described with reference to FIGs. 6 through 9.

At 1615, the UE may receive an uplink control channel reconfiguration message for the primary uplink control channel including an SCell uplink control channel enablement parameter, where the SCell uplink control channel enablement parameter enables the UE to transmit the UCI for the PCell group on the secondary uplink control channel. The operations of 1615 may be performed according to the methods described herein. In some examples, aspects of the operations of 1615 may be performed by a PUCCH SCell enablement component as described with reference to FIGs. 6 through 9.

At 1620, the UE may select the secondary uplink control channel to transmit the UCI for the PCell group based on the switching capability of the UE. The operations of 1620 may be performed according to the methods described herein. In some examples, aspects of the operations of 1620 may be performed by a PUCCH selector as described with reference to FIGs. 6 through 9.

At 1625, the UE may transmit the UCI for the PCell group on the selected secondary uplink control channel. The operations of 1625 may be performed according to the methods described herein. In some examples, aspects of the operations of 1625 may be performed by an UCI transmitter as described with reference to FIGs. 6 through 9.

At 1630, the UE may receive an uplink control channel configuration message for the primary uplink control channel. The operations of 1630 may be performed according to the methods described herein. In some examples, aspects of the operations of 1630 may be performed by a PUCCH SCell enablement component as described with reference to FIGs. 6 through 9.

At 1635, the UE may identify an activation of the SCell group. The operations of 1635 may be performed according to the methods described herein. In some examples, aspects of the operations of 1635 may be performed by a PUCCH SCell enablement component as described with reference to FIGs. 6 through 9.

FIG. 17 shows a flowchart illustrating a method 1700 that supports ACK feedback for CA in accordance with aspects of the present disclosure. The operations of method 1700 may be implemented by a UE 115 or its components as described herein. For example, the operations of method 1700 may be performed by a UE communications manager as described with reference to FIGs. 6 through 9. In some examples, a UE may execute a set of instructions to control the functional elements of the UE to perform the functions described herein. Additionally or alternatively, a UE may perform aspects of the functions described herein using special-purpose hardware.

At 1705, the UE may identify a CA configuration including a PCell group having a PCell configured with a primary uplink control channel and an SCell group having an SCell configured with a secondary uplink control channel. The operations of 1705 may be performed according to the methods described herein. In some examples, aspects of the operations of 1705 may be performed by a CA configuration identifier as described with reference to FIGs. 6 through 9.

At 1710, the UE may identify that the UE has a switching capability supporting at least dynamic switching of transmission of UCI for the PCell group between the primary uplink control channel and the secondary uplink control channel. The operations of 1710 may be performed according to the methods described herein. In some examples, aspects of the operations of 1710 may be performed by a switching capability identifier as described with reference to FIGs. 6 through 9.

At 1715, the UE may receive a first uplink control channel configuration message for the primary uplink control channel. The operations of 1715 may be performed according to the methods described herein. In some examples, aspects of the operations of 1715 may be performed by a multi-PUCCH configuration component as described with reference to FIGs. 6 through 9.

At 1720, the UE may receive a second uplink control channel configuration message for the secondary uplink control channel, where the secondary uplink control channel is selected to transmit the UCI for the PCell group based on the first uplink control channel configuration message and the second uplink control channel configuration message. The operations of 1720 may be performed according to the methods described herein. In some examples, aspects of the operations of 1720 may be performed by a multi-PUCCH configuration component as described with reference to FIGs. 6 through 9.

At 1725, the UE may select the secondary uplink control channel to transmit the UCI for the PCell group based on the switching capability of the UE. The operations of 1725 may be performed according to the methods described herein. In some examples, aspects of the operations of 1725 may be performed by a PUCCH selector as described with reference to FIGs. 6 through 9.

At 1730, the UE may transmit the UCI for the PCell group on the selected secondary uplink control channel. The operations of 1730 may be performed according to the methods described herein. In some examples, aspects of the operations of 1730 may be performed by an UCI transmitter as described with reference to FIGs. 6 through 9.

FIG. 18 shows a flowchart illustrating a method 1800 that supports ACK feedback for CA in accordance with aspects of the present disclosure. The operations of method 1800 may be implemented by a base station 105 or its components as described herein. For example, the operations of method 1800 may be performed by a base station communications manager as described with reference to FIGs. 10 through 13. In some examples, a base station may execute a set of instructions to control the functional elements of the base station to perform the functions described herein. Additionally or alternatively, a base station may perform aspects of the functions described herein using special-purpose hardware.

At 1805, the base station may identify, for communications with a UE, a CA configuration including a PCell group having a PCell configured with a primary uplink control channel and an SCell group having an SCell configured with a secondary uplink control channel. The operations of 1805 may be performed according to the methods described herein. In some examples, aspects of the operations of 1805 may be performed by a CA configuration component as described with reference to FIGs. 10 through 13.

At 1810, the base station may identify that the UE has a switching capability supporting at least dynamic switching of transmission of UCI for the PCell group between the primary uplink control channel and the secondary uplink control channel. The operations of 1810 may be performed according to the methods described herein. In some examples, aspects of the operations of 1810 may be performed by a switching capability component as described with reference to FIGs. 10 through 13.

At 1815, the base station may receive, from the UE, the UCI for the PCell group on the secondary uplink control channel based on the switching capability. The operations of 1815 may be performed according to the methods described herein. In some examples, aspects of the operations of 1815 may be performed by an UCI receiver as described with reference to FIGs. 10 through 13.

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

The following provides an overview of examples of the present disclosure:

Example 1: A method for wireless communications at a UE, comprising: identifying a carrier aggregation configuration comprising a primary cell group having a primary cell configured with a primary uplink control channel and a secondary cell group having a secondary cell configured with a secondary uplink control channel; identifying that the UE has a switching capability supporting at least dynamic switching of transmission of uplink control information for the primary cell group between the primary uplink control channel and the secondary uplink control channel; selecting the secondary uplink control channel to transmit the uplink control information for the primary cell group based at least in part on the switching capability of the UE; and transmitting the uplink control information for the primary cell group on the selected secondary uplink control channel.

Example 2: The method of example 1, further comprising: receiving an uplink control channel configuration message for the primary uplink control channel comprising a secondary cell uplink control channel parameter, wherein the secondary cell uplink control channel parameter enables the UE to transmit the uplink control information for the primary cell group on the secondary uplink control channel.

Example 3: The method of example 2, further comprising: identifying that the secondary uplink control channel is enabled based at least in part on a reconfiguration of the carrier aggregation configuration, wherein the reconfiguration results from completion of a random access procedure with a secondary cell of the secondary cell group.

Example 4: The method of example 2, further comprising: identifying that the secondary uplink control channel is enabled based at least in part on expiration of a reconfiguration timer.

Example 5: The method of example 2, further comprising: transmitting the uplink control information for the primary cell group on the secondary uplink control channel after expiration of a configuration processing time threshold.

Example 6: The method of example 2, further comprising: receiving an indication to switch from the secondary uplink control channel to the primary uplink control channel for transmitting the uplink control information.

Example 7: The method of any of example 2, further comprising: releasing the secondary cell group; and selecting the primary uplink control channel for transmitting the uplink control information for the primary cell group based at least in part on releasing the secondary cell group.

Example 8: The method of any of examples 1 to 7, further comprising: receiving an uplink control channel configuration message for the primary uplink control channel; identifying an activation of the secondary cell group; and receiving an uplink control channel reconfiguration message for the primary uplink control channel comprising a secondary cell uplink control channel enablement parameter, wherein the secondary cell uplink control channel enablement parameter enables the UE to transmit the uplink control information for the primary cell group on the secondary uplink control channel.

Example 9: The method of any of examples 1 to 8, further comprising: receiving a second uplink control channel reconfiguration message for the primary uplink control channel deleting the secondary cell uplink control channel enablement parameter, wherein the second uplink control channel reconfiguration message indicates for the UE to transmit the uplink control information on the primary uplink control channel based at least in part on the secondary cell uplink control channel enablement parameter being deleted.

Example 10: The method of any of examples 1 to 9, further comprising: receiving a first uplink control channel configuration message for the primary uplink control channel; and receiving a second uplink control channel configuration message for the secondary uplink control channel, wherein the secondary uplink control channel is selected to transmit the uplink control information for the primary cell group based at least in part on the first uplink control channel configuration message and the second uplink control channel configuration message.

Example 11: The method of example 10, further comprising: receiving an indicator to enable the secondary uplink control channel, wherein the UE transmits the uplink control information for the primary cell group on the secondary uplink control channel based at least in part on the indicator enabling the secondary uplink control channel.

Example 12: The method of example 11, further comprising: receiving the indicator to disable the secondary uplink control channel, wherein the UE transmits the uplink control information for the primary cell group on the primary uplink control channel based at least in part on the indicator disabling the secondary uplink control channel.

Example 13: The method of example 12, wherein the indicator is received via medium access control (MAC) control element, radio resource control signaling, downlink control information signaling, or a combination thereof.

Example 14: The method of any of example 12, wherein the indicator comprises downlink control information with a downlink grant configuring the UE to transmit the uplink control information on the secondary uplink control channel.

Example 15: The method of any of examples 1 to 14, wherein the primary cell group comprises a first subcarrier spacing, and the secondary cell group comprises a second subcarrier spacing that is different than the first subcarrier spacing.

Example 16: The method of any of examples 1 to 15, wherein the uplink control information comprises acknowledgment feedback, channel state information reports, or a combination thereof.

Example 17: An apparatus comprising at least one means for performing a method of any examples 1 to 16.

Example 18: An apparatus for wireless communications comprising a processor; memory coupled with the processor; and instructions stored in the memory and executable by the processor to cause the apparatus to perform a method of any of examples 1 to 16.

Example 19: A non-transitory computer-readable medium storing code for wireless communications, the code comprising instructions executable by a processor to perform a method of any of examples 1 to 16.

Example 20: A method for wireless communications at a base station, comprising: identifying, for communications with a UE, a carrier aggregation configuration comprising a primary cell group having a primary cell configured with a primary uplink control channel and a secondary cell group having a secondary cell configured with a secondary uplink control channel; identifying that the UE has a switching capability supporting at least dynamic switching of transmission of uplink control information for the primary cell group between the primary uplink control channel and the secondary uplink control channel; and receiving, from the UE, the uplink control information for the primary cell group on the secondary uplink control channel based at least in part on the switching capability.

Example 21: The method of example 20, further comprising: transmitting, to the UE, an uplink control channel configuration message for the primary uplink control channel comprising a secondary cell uplink control channel parameter, wherein the secondary cell uplink control channel parameter enables the UE to transmit the uplink control information for the primary cell group on the secondary uplink control channel.

Example 22: The method of example 21, wherein the uplink control information for the primary cell group is received on the secondary uplink control channel based at least in part on a reconfiguration of the carrier aggregation configuration, completion of a random access procedure for the secondary cell of the secondary cell group, a reconfiguration timer expiration, a processing time threshold expiration, or a combination thereof.

Example 23: The method of example 21, further comprising: transmitting, to the UE, an indication to switch from the secondary uplink control channel to the primary uplink control channel for transmitting the uplink control information, wherein the uplink control information is received on the primary uplink control channel based at least in part on the transmitted indication to switch.

Example 24: The method of any of examples 20 to 23, further comprising: transmitting an uplink control channel configuration message for the primary uplink control channel; identifying an activation of the secondary cell group; and transmitting an uplink control channel reconfiguration message for the primary uplink control channel comprising a secondary cell uplink control channel enablement parameter, wherein the secondary cell uplink control channel enablement parameter enables the UE to transmit the uplink control information for the primary cell group on the secondary uplink control channel.

Example 25: The method of example 24, further comprising: transmitting a second uplink control channel reconfiguration message for the primary uplink control channel deleting the secondary cell uplink control channel enablement parameter, wherein the second uplink control channel reconfiguration message indicates for the UE to transmit the uplink control information on the primary uplink control channel based at least in part on the secondary cell uplink control channel enablement parameter being deleted.

Example 26: The method of any of examples 20 to 25, further comprising: transmitting a first uplink control channel configuration message for the primary uplink control channel; and transmitting a second uplink control channel configuration message for the secondary uplink control channel, wherein the uplink control information for the primary cell group is received on the secondary uplink control channel based at least in part on the first uplink control channel configuration message and the second uplink control channel configuration message.

Example 27: The method of example 26, further comprising: transmitting an indication for enabling the secondary uplink control channel, wherein the uplink control information for the primary cell group is received on the secondary uplink control channel based at least in part on the indication.

Example 28: The method of example 27, further comprising: transmitting an indication for disabling the secondary uplink control channel, wherein the uplink control information for the primary cell group is received on the primary uplink control channel based at least in part on the indication.

Example 29: The method of example 28, wherein the indication is transmitted via medium access control (MAC) control element, radio resource control signaling, downlink control information signaling, or a combination thereof.

Example 30: The method of any of example 27, wherein the indication for enabling the secondary uplink control channel comprises downlink control information with a downlink grant configuring the UE to transmit the uplink control information on the secondary uplink control channel, and wherein the uplink control information is received on the secondary uplink control channel based at least according to the configured uplink control channel.

Example 31: The method of any of examples 20 to 30, wherein the primary cell group comprises a first subcarrier spacing, and the secondary cell group comprises a second subcarrier spacing that is different than the first subcarrier spacing.

Example 32: The method of any of examples 20 to 31, wherein the uplink control information comprises acknowledgment feedback, channel state information reports, or a combination thereof.

Example 33: An apparatus comprising at least one means for performing a method of any examples 20 to 32.

Example 34: An apparatus for wireless communications comprising a processor; memory coupled with the processor; and instructions stored in the memory and executable by the processor to cause the apparatus to perform a method of any of examples 20 to 32.

Example 35: A non-transitory computer-readable medium storing code for wireless communications, the code comprising instructions executable by a processor to perform a method of any of examples 20 to 32.

Techniques described herein may be used for various wireless communications systems such as code division multiple access (CDMA) , time division multiple access (TDMA) , frequency division multiple access (FDMA) , orthogonal frequency division multiple access (OFDMA) , single carrier frequency division multiple access (SC-FDMA) , and other systems. A CDMA system may implement a radio technology such as CDMA2000, Universal Terrestrial Radio Access (UTRA) , etc. CDMA2000 covers IS-2000, IS-95, and IS-856 standards. IS-2000 Releases may be commonly referred to as CDMA2000 1X, 1X, etc. IS-856 (TIA-856) is commonly referred to as CDMA2000 1xEV-DO, High Rate Packet Data (HRPD) , etc. UTRA includes Wideband CDMA (WCDMA) and other variants of CDMA. A TDMA system may implement a radio technology such as Global System for Mobile Communications (GSM) .

An OFDMA system may implement a radio technology such as Ultra Mobile Broadband (UMB) , Evolved UTRA (E-UTRA) , Institute of Electrical and Electronics Engineers (IEEE) 802.11 (Wi-Fi) , IEEE 802.16 (WiMAX) , IEEE 802.20, Flash-OFDM, etc. UTRA and E-UTRA are part of Universal Mobile Telecommunications System (UMTS) . LTE, LTE-A, and LTE-A Pro are releases of UMTS that use E-UTRA. UTRA, E-UTRA, UMTS, LTE, LTE-A, LTE-A Pro, NR, and GSM are described in documents from the organization named “3rd Generation Partnership Project” (3GPP) . CDMA2000 and UMB are described in documents from an organization named “3rd Generation Partnership Project 2” (3GPP2) . The techniques described herein may be used for the systems and radio technologies mentioned herein as well as other systems and radio technologies. While aspects of an LTE, LTE-A, LTE-A Pro, or NR system may be described for purposes of example, and LTE, LTE-A, LTE-A Pro, or NR terminology may be used in much of the description, the techniques described herein are applicable beyond LTE, LTE-A, LTE-A Pro, or NR applications.

A macro cell generally covers a relatively large geographic area (e.g., several kilometers in radius) and may allow unrestricted access by UEs with service subscriptions with the network provider. A small cell may be associated with a lower-powered base station, as compared with a macro cell, and a small cell may operate in the same or different (e.g., licensed, unlicensed, etc. ) frequency bands as macro cells. Small cells may include pico cells, femto cells, and micro cells according to various examples. A pico cell, for example, may cover a small geographic area and may allow unrestricted access by UEs with service subscriptions with the network provider. A femto cell may also cover a small geographic area (e.g., a home) and may provide restricted access by UEs having an association with the femto cell (e.g., UEs in a closed subscriber group (CSG) , UEs for users in the home, and the like) . An eNB for a macro cell may be referred to as a macro eNB. An eNB for a small cell may be referred to as a small cell eNB, a pico eNB, a femto eNB, or a home eNB. An eNB may support one or multiple (e.g., two, three, four, and the like) cells, and may also support communications using one or multiple component carriers.

The wireless communications systems described herein may support synchronous or asynchronous operation. For synchronous operation, the base stations may have similar frame timing, and transmissions from different base stations may be approximately aligned in time. For asynchronous operation, the base stations may have different frame timing, and transmissions from different base stations may not be aligned in time. The techniques described herein may be used for either synchronous or asynchronous operations.

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

The various illustrative blocks and modules described in connection with the disclosure herein may be implemented or performed with 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 herein. A general-purpose processor may be a microprocessor, but in the alternative, the processor may be any conventional processor, controller, microcontroller, or state machine. A processor may 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) .

The functions described herein may be implemented in hardware, software executed by a processor, firmware, or any combination thereof. If implemented in software executed by a processor, the functions may 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 may also be physically located at various positions, including being distributed such that portions of functions are implemented at different physical locations.

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 may 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 may include random-access memory (RAM) , read-only memory (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 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.

As used herein, including in the claims, “or” as used in a list of items (e.g., a list of items prefaced by a phrase 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 exemplary step that is described as “based on condition A” may 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. ”

In the appended figures, similar components or features may have the same reference label. Further, various components of the same type may be distinguished by following the reference label by a dash and a second label that distinguishes among the similar components. If just the first reference label is used in the specification, the description is applicable to any one of the similar components having the same first reference label irrespective of the second reference label, or other subsequent reference label.

The description set forth herein, in connection with the appended drawings, describes example configurations and does not represent all the examples that may be implemented or that are within the scope of the claims. The term “exemplary” used herein means “serving as an example, instance, or illustration, ” and not “preferred” or “advantageous over other examples. ” The detailed description includes specific details for the purpose of providing an understanding of the described techniques. These techniques, however, may 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.

The description herein is provided to enable a person skilled in the art to make or use the disclosure. Various modifications to the disclosure will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other variations without departing from the scope of the disclosure. Thus, the disclosure is not 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

A method for wireless communications at a user equipment (UE) , comprising:

identifying a carrier aggregation configuration comprising a primary cell group having a primary cell configured with a primary uplink control channel and a secondary cell group having a secondary cell configured with a secondary uplink control channel;

identifying that the UE has a switching capability supporting at least dynamic switching of transmission of uplink control information for the primary cell group between the primary uplink control channel and the secondary uplink control channel;

selecting the secondary uplink control channel to transmit the uplink control information for the primary cell group based at least in part on the switching capability of the UE; and

transmitting the uplink control information for the primary cell group on the selected secondary uplink control channel.
The method of claim 1, further comprising:

receiving an uplink control channel configuration message for the primary uplink control channel comprising a secondary cell uplink control channel parameter, wherein the secondary cell uplink control channel parameter enables the UE to transmit the uplink control information for the primary cell group on the secondary uplink control channel.
The method of claim 2, further comprising:

identifying that the secondary uplink control channel is enabled based at least in part on a reconfiguration of the carrier aggregation configuration, wherein the reconfiguration results from completion of a random access procedure with the secondary cell of the secondary cell group.
The method of claim 2, further comprising:

identifying that the secondary uplink control channel is enabled based at least in part on expiration of a reconfiguration timer.
The method of claim 2, further comprising:

transmitting the uplink control information for the primary cell group on the secondary uplink control channel after expiration of a configuration processing time threshold.
The method of claim 2, further comprising:

receiving an indication to switch from the secondary uplink control channel to the primary uplink control channel for transmitting the uplink control information.
The method of claim 2, further comprising:

releasing the secondary cell group; and

selecting the primary uplink control channel for transmitting the uplink control information for the primary cell group based at least in part on releasing the secondary cell group.
The method of claim 2, further comprising:

receiving a second uplink control channel reconfiguration message for the primary uplink control channel deleting the secondary cell uplink control channel parameter, wherein the second uplink control channel reconfiguration message indicates for the UE to transmit the uplink control information on the primary uplink control channel based at least in part on the secondary cell uplink control channel parameter being deleted.
The method of claim 1, further comprising:

receiving a first uplink control channel configuration message for the primary uplink control channel; and

receiving a second uplink control channel configuration message for the secondary uplink control channel, wherein the secondary uplink control channel is selected to transmit the uplink control information for the primary cell group based at least in part on the first uplink control channel configuration message and the second uplink control channel configuration message.
The method of claim 9, further comprising:

receiving an indicator to enable the secondary uplink control channel, wherein the UE transmits the uplink control information for the primary cell group on the secondary uplink control channel based at least in part on the indicator enabling the secondary uplink control channel.
The method of claim 10, further comprising:

receiving the indicator to disable the secondary uplink control channel, wherein the UE transmits the uplink control information for the primary cell group on the primary uplink control channel based at least in part on the indicator disabling the secondary uplink control channel.
The method of claim 11, wherein the indicator is received via medium access control (MAC) control element, radio resource control signaling, downlink control information signaling, or a combination thereof.
An apparatus for wireless communications at a user equipment (UE) , comprising:

a processor,

memory coupled with the processor; and

instructions stored in the memory and executable by the processor to cause the apparatus to:

identify a carrier aggregation configuration comprising a primary cell group having a primary cell configured with a primary uplink control channel and a secondary cell group having a secondary cell configured with a secondary uplink control channel;

identify that the UE has a switching capability supporting at least dynamic switching of transmission of uplink control information for the primary cell group between the primary uplink control channel and the secondary uplink control channel;

select the secondary uplink control channel to transmit the uplink control information for the primary cell group based at least in part on the switching capability of the UE; and

transmit the uplink control information for the primary cell group on the selected secondary uplink control channel.
The apparatus of claim 13, wherein the instructions are further executable by the processor to cause the apparatus to:

receive an uplink control channel configuration message for the primary uplink control channel comprising a secondary cell uplink control channel parameter, wherein the secondary cell uplink control channel parameter enables the UE to transmit the uplink control information for the primary cell group on the secondary uplink control channel.
The apparatus of claim 14, wherein the instructions are further executable by the processor to cause the apparatus to:

identify that the secondary uplink control channel is enabled based at least in part on a reconfiguration of the carrier aggregation configuration, wherein the reconfiguration results from completion of a random access procedure with the secondary cell of the secondary cell group.
The apparatus of claim 14, wherein the instructions are further executable by the processor to cause the apparatus to:

identify that the secondary uplink control channel is enabled based at least in part on expiration of a reconfiguration timer.
The apparatus of claim 14, wherein the instructions are further executable by the processor to cause the apparatus to:

transmit the uplink control information for the primary cell group on the secondary uplink control channel after expiration of a configuration processing time threshold.
The apparatus of claim 14, wherein the instructions are further executable by the processor to cause the apparatus to:

receive an indication to switch from the secondary uplink control channel to the primary uplink control channel for transmitting the uplink control information.
The apparatus of claim 14, wherein the instructions are further executable by the processor to cause the apparatus to:

release the secondary cell group; and

select the primary uplink control channel for transmitting the uplink control information for the primary cell group based at least in part on releasing the secondary cell group.
The apparatus of claim 14, wherein the instructions are further executable by the processor to cause the apparatus to:

receive a second uplink control channel reconfiguration message for the primary uplink control channel deleting the secondary cell uplink control channel parameter, wherein the second uplink control channel reconfiguration message indicates for the UE to transmit the uplink control information on the primary uplink control channel based at least in part on the secondary cell uplink control channel parameter being deleted.
The apparatus of claim 13, wherein the instructions are further executable by the processor to cause the apparatus to:

receive a first uplink control channel configuration message for the primary uplink control channel; and

receive a second uplink control channel configuration message for the secondary uplink control channel, wherein the secondary uplink control channel is selected to transmit the uplink control information for the primary cell group based at least in part on the first uplink control channel configuration message and the second uplink control channel configuration message.
The apparatus of claim 21, wherein the instructions are further executable by the processor to cause the apparatus to:

receive an indicator to enable the secondary uplink control channel, wherein the UE transmits the uplink control information for the primary cell group on the secondary uplink control channel based at least in part on the indicator enabling the secondary uplink control channel.
The apparatus of claim 22, wherein the instructions are further executable by the processor to cause the apparatus to:

receive the indicator to disable the secondary uplink control channel, wherein the UE transmits the uplink control information for the primary cell group on the primary uplink control channel based at least in part on the indicator disabling the secondary uplink control channel.
The apparatus of claim 23, wherein the indicator is received via medium access control (MAC) control element, radio resource control signaling, downlink control information signaling, or a combination thereof.
An apparatus for wireless communications at a user equipment (UE) , comprising:

means for identifying a carrier aggregation configuration comprising a primary cell group having a primary cell configured with a primary uplink control channel and a secondary cell group having a secondary cell configured with a secondary uplink control channel;

means for identifying that the UE has a switching capability supporting at least dynamic switching of transmission of uplink control information for the primary cell group between the primary uplink control channel and the secondary uplink control channel;

means for selecting the secondary uplink control channel to transmit the uplink control information for the primary cell group based at least in part on the switching capability of the UE; and

means for transmitting the uplink control information for the primary cell group on the selected secondary uplink control channel.
The apparatus of claim 25, further comprising:

means for receiving an uplink control channel configuration message for the primary uplink control channel comprising a secondary cell uplink control channel parameter, wherein the secondary cell uplink control channel parameter enables the UE to transmit the uplink control information for the primary cell group on the secondary uplink control channel.
The apparatus of claim 26, further comprising:

means for identifying that the secondary uplink control channel is enabled based at least in part on a reconfiguration of the carrier aggregation configuration, wherein the reconfiguration results from completion of a random access procedure with the secondary cell of the secondary cell group.
The apparatus of claim 26, further comprising:

means for identifying that the secondary uplink control channel is enabled based at least in part on expiration of a reconfiguration timer.
The apparatus of claim 25, further comprising:

means for receiving a first uplink control channel configuration message for the primary uplink control channel; and

means for receiving a second uplink control channel configuration message for the secondary uplink control channel, wherein the secondary uplink control channel is selected to transmit the uplink control information for the primary cell group based at least in part on the first uplink control channel configuration message and the second uplink control channel configuration message.
A non-transitory computer-readable medium storing code for wireless communications at a user equipment (UE) , the code comprising instructions executable by a processor to:

identify a carrier aggregation configuration comprising a primary cell group having a primary cell configured with a primary uplink control channel and a secondary cell group having a secondary cell configured with a secondary uplink control channel;

identify that the UE has a switching capability supporting at least dynamic switching of transmission of uplink control information for the primary cell group between the primary uplink control channel and the secondary uplink control channel;

select the secondary uplink control channel to transmit the uplink control information for the primary cell group based at least in part on the switching capability of the UE; and

transmit the uplink control information for the primary cell group on the selected secondary uplink control channel.