阅读说明：本技术 主蜂窝小区群和副蜂窝小区群共存 (Primary and secondary cell groups co-exist ) 是由 P·P·L·昂 晓风·王 J·蒙托约 P·盖尔 陈万士 H·李 J·B·索里亚加 于 2019-03-22 设计创作，主要内容包括：描述了用于无线通信的方法、系统和设备。无线通信网络可以为双连通性中的蜂窝小区群设置优先级。较高优先级蜂窝小区群(例如主蜂窝小区群MCG或副蜂窝小区群SCG)可以保留时隙,并且例如通过回程连接向较低优先级蜂窝小区群(例如互补即SCG或MCG)指示所保留时隙。高优先级蜂窝小区群还可指示附加的、非所保留时隙,较低优先级蜂窝小区群可以将其保留或用于调度。蜂窝小区群之一可以在双连通性中向用户装备(UE)传送时隙格式指示(SFI)以指示时隙保留。在一些情形中,混合自动重复请求(HARQ)定时参数可基于所保留时隙的数目。在一些情形中,功率控制可基于UE是否能够同时进行上行链路和下行链路传输来改变。(Methods, systems, and devices for wireless communication are described. The wireless communication network may prioritize cell groups in dual connectivity. A higher priority cell group (e.g., primary cell group MCG or secondary cell group SCG) may reserve time slots and indicate the reserved time slots to a lower priority cell group (e.g., complementary or SCG or MCG), e.g., over a backhaul connection. The high priority cell group may also indicate additional, unreserved time slots that a lower priority cell group may reserve or use for scheduling. One of the cell groups may transmit a Slot Format Indication (SFI) to a User Equipment (UE) in dual connectivity to indicate a slot reservation. In some cases, a hybrid automatic repeat request (HARQ) timing parameter may be based on the number of reserved slots. In some cases, power control may change based on whether the UE is capable of simultaneous uplink and downlink transmissions.)

1. A method for wireless communication at a User Equipment (UE), comprising:

identifying that the UE is operating in dual connectivity with a primary cell group and a secondary cell group;

receiving, from the primary cell group, an indication of a reserved Transmission Time Interval (TTI) reserved for priority Uplink (UL) communications with the primary cell group;

identifying additional TTIs available for UL communication with the primary cell group or the secondary cell group;

transmitting one or more UL messages to the primary cell group using the reserved TTI; and

transmitting one or more UL messages to the primary cell group or the secondary cell group using the additional TTIs.

2. The method of claim 1, further comprising:

receiving a schedule of using one or more of the additional TTIs for UL communication with the primary cell group or the secondary cell group, the schedule facilitating avoidance of UL transmissions to both the primary cell group and the secondary cell group at the same time, wherein transmitting one or more UL messages using the additional TTIs is in accordance with the schedule.

3. The method of claim 1, further comprising:

receiving, from the secondary cell group, an indication of an additional reserved TTI that can be reserved for UL communications with the secondary cell group, wherein the reserved TTI and the additional reserved TTI are disjoint in time; and

transmitting one or more UL messages to the secondary cell group using the additional reserved TTIs.

4. The method of claim 1, further comprising:

determining that a UL message to the primary cell group and a UL message to the secondary cell group are both scheduled for a same one of the additional TTIs;

identifying a priority between a UL message destined for the primary cell group and a UL message destined for the secondary cell group; and

transmitting one of a UL message to the primary cell group or a UL message to the secondary cell group during the TTI based on the priority.

5. The method of claim 1, wherein receiving the indication of the reserved TTI comprises:

receiving a Slot Format Indication (SFI) identifying a configuration for an UL TTI, a Downlink (DL) TTI, an unknown TTI, or a combination thereof, wherein the reserved TTI comprises the UL TTI.

6. The method of claim 1, wherein the indication further indicates a Downlink (DL) TTI, an unknown TTI, or both, reserved for communication with the primary cell group.

7. The method of claim 1, wherein the primary cell group is configured for Time Division Duplex (TDD) operation and the secondary cell group is configured for Frequency Division Duplex (FDD) operation, wherein UL transmissions to the secondary cell group are time division shared with Supplemental Uplink (SUL) transmissions to the primary cell group.

8. The method of claim 1, further comprising:

identifying an FDD timing configuration for UL transmissions to the secondary cell group that facilitates avoiding UL transmissions to both the primary cell group and the secondary cell group at the same time, wherein transmitting one or more UL messages using the additional TTIs is in accordance with the FDD timing configuration.

9. The method of claim 1, further comprising:

receiving a joint configuration comprising the indication of reserved TTIs reserved for UL or Downlink (DL) communication with the primary cell group and an indication of which of the additional TTIs to be used for UL or DL communication with the primary cell group and which of the additional TTIs to be used for UL or DL communication with the secondary cell group.

10. The method of claim 1, further comprising:

receiving a prioritization configuration comprising the indication of reserved TTIs reserved for UL or Downlink (DL) communication with the primary cell group and an indication of which of the additional TTIs to be used for UL or DL communication with the primary cell group.

11. The method of claim 10, wherein transmitting one or more UL messages to the primary cell group or the secondary cell group using the additional TTIs comprises:

transmitting the one or more UL messages to the secondary cell group during one of the additional TTIs indicated for DL communication with the primary cell group.

12. The method of claim 1, wherein transmitting one or more UL messages to the primary cell group or the secondary cell group using the additional TTIs comprises:

transmitting an UL message to the primary cell group and the secondary cell group during the same TTI.

13. The method of claim 12, further comprising:

prioritizing power control for each of the UL messages transmitted during the same TTI based at least in part on a type of the UL message.

14. The method of claim 12, further comprising:

prioritizing power control for each of the UL messages transmitted during the same TTI based at least in part on a start time of each of the UL messages.

15. The method of claim 12, wherein a maximum power control for UL messages transmitted to the primary cell group and a maximum power control for UL messages transmitted to the secondary cell group during the same TTI are each less than a respective power control for UL transmissions during different TTIs.

16. The method of claim 1, further comprising:

identifying a first TTI duration associated with the primary cell group;

identifying a second TTI duration associated with the group of secondary cells; and

applying a transmit power control scheme based at least in part on the first TTI duration and the second TTI duration.

17. The method of claim 16, wherein applying the transmit power control scheme further comprises:

adjusting a transmit power for UL messages transmitted to the primary cell group and UL messages transmitted to the secondary cell group after a TTI of the first TTI duration based at least in part on the first TTI duration being longer than the second TTI duration.

18. The method of claim 16, wherein applying the transmit power control scheme further comprises:

adjusting a transmit power for UL messages transmitted to the primary cell group and UL messages transmitted to the secondary cell group after a TTI of the second TTI duration based at least in part on the second TTI duration being longer than the first TTI duration.

19. A method for wireless communications at a base station, comprising:

identifying that the base station is operating as a primary cell group in dual connectivity with a User Equipment (UE);

transmitting, to the UE, an indication of a reserved Transmission Time Interval (TTI) reserved for priority Uplink (UL) communication with the primary cell group;

indicating to a secondary cell group the reserved TTI and an additional TTI that can be used for UL communication with the primary cell group or the secondary cell group; and

receiving one or more UL messages from the UE using the reserved TTI.

20. The method of claim 19, further comprising:

transmitting a schedule that utilizes one or more of the additional TTIs for UL communication with the primary cell group or the secondary cell group, the schedule facilitating avoiding UL transmissions to both the primary cell group and the secondary cell group at the same time.

21. The method of claim 19, wherein transmitting the indication of the reserved TTI comprises:

transmitting a Slot Format Indication (SFI) identifying a configuration for an UL TTI, a Downlink (DL) TTI, an unknown TTI, or a combination thereof, wherein the reserved TTI comprises the UL TTI.

22. The method of claim 19, wherein the indication further indicates a Downlink (DL) TTI, an unknown TTI, or both, reserved for communication with the primary cell group.

23. The method of claim 19, wherein the primary cell group is configured for Time Division Duplex (TDD) operation and the secondary cell group is configured for Frequency Division Duplex (FDD) operation, wherein UL transmissions to the secondary cell group are time division shared with Supplemental Uplink (SUL) transmissions to the primary cell group.

24. The method of claim 19, further comprising:

indicating, to the UE, an FDD timing configuration for UL transmissions to the secondary cell group that facilitates avoiding UL transmissions to both the primary cell group and the secondary cell group at the same time.

25. The method of claim 19, further comprising:

transmitting, to the UE, a joint configuration comprising the indication of reserved TTIs reserved for UL or Downlink (DL) communication with the primary cell group and an indication of which of the additional TTIs to be used for UL or DL communication with the primary cell group and which of the additional TTIs to be used for UL or DL communication with the secondary cell group.

26. The method of claim 19, further comprising:

transmitting a prioritization configuration to the UE, the prioritization configuration including the indication of reserved TTIs reserved for UL or Downlink (DL) communications with the primary cell group and an indication of which of the additional TTIs to be used for UL or DL communications with the primary cell group.

27. An apparatus for wireless communication at a User Equipment (UE), comprising:

means for identifying that the UE is operating in dual connectivity with a primary cell group and a secondary cell group;

means for receiving an indication of a reserved Transmission Time Interval (TTI) reserved for priority Uplink (UL) communication with the primary cell group from the primary cell group;

means for identifying an additional TTI that is available for UL communication with the primary cell group or the secondary cell group;

means for transmitting one or more UL messages to the primary cell group using the reserved TTI; and

means for transmitting one or more UL messages to the primary cell group or the secondary cell group using the additional TTIs.

28. The apparatus of claim 27, further comprising:

means for receiving a schedule using one or more of the additional TTIs for UL communication with the primary cell group or the secondary cell group, the schedule facilitating avoidance of UL transmissions to both the primary cell group and the secondary cell group at the same time, wherein transmitting one or more UL messages using the additional TTIs is in accordance with the schedule.

29. An apparatus for wireless communication at a base station, comprising:

means for identifying that the base station is operating as a primary cell group in dual connectivity with a User Equipment (UE);

means for transmitting an indication of a reserved Transmission Time Interval (TTI) reserved for priority Uplink (UL) communication with the primary cell group to the UE;

means for indicating the reserved TTI to a secondary cell group and an additional TTI that may be used for UL communication with the primary cell group or the secondary cell group; and

means for receiving one or more UL messages from the UE using the reserved TTI.

30. The apparatus of claim 29, further comprising:

means for transmitting a schedule that uses one or more of the additional TTIs for UL communication with the primary cell group or the secondary cell group, the schedule facilitating avoidance of UL transmissions to both the primary cell group and the secondary cell group at the same time.

Background

The following relates generally to wireless communications, and more particularly to primary cell group (MCG) and Secondary Cell Group (SCG) coexistence.

Wireless communication 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 able to support 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 that may be referred to as New Radio (NR) systems. These systems may employ various techniques, 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 OFDM (DFT-S-OFDM). A wireless multiple-access communication system may include several base stations or network access nodes, each supporting communication for multiple communication devices simultaneously, which may otherwise be referred to as User Equipment (UE).

The wireless communication system may implement a dual connectivity scheme in which a UE may be simultaneously connected to a first base station for LTE communications and a second base station for NR communications. In dual connectivity, one of the base stations may be identified as an MCG. The base station (e.g., MCG) may provide an anchor carrier for communicating with the UE. The anchor carrier may be associated with a Radio Access Technology (RAT) of the MCG. A base station that is not an MCG in a dual connectivity scheme may be identified as an SCG. In some examples, the MCG is associated with LTE and controls SCG associated with NR. In other examples, MCGs may be associated with NRs, while SCGs may be associated with LTE. A dual connectivity scheme with NR anchors may provide improved throughput for UEs. However, in either case, whether MCG is associated with NR or LTE, and SCG is associated with a different RAT (LTE or NR, respectively), coexistence issues may arise.

SUMMARY

A wireless communication system may implement a dual connectivity scheme to improve throughput of wireless devices. For example, a User Equipment (UE) may be simultaneously connected to a first base station (e.g., an evolved node B (eNB)) for LTE communications and a second base station (e.g., a next generation node B (gNB)) for New Radio (NR) communications. One of the base stations may provide a primary cell group (MCG) that controls a Secondary Cell Group (SCG). The core network may implement a priority scheme for each Radio Access Technology (RAT) based on whether NR or LTE has a higher priority. A higher priority cell group may reserve time slots across individual cells in a dual connectivity scheme and indicate the reserved time slots to a lower priority cell group (e.g., via a backhaul connection). The higher priority cell group may also indicate additional, unreserved time slots that the lower priority cell group may reserve or use for scheduling. The higher priority cell groups may also independently schedule transmissions on the unreserved, additional time slots. The cell group may transmit a Slot Format Indication (SFI) to the UE to indicate the slot reservation. In some examples, a wireless communication system may utilize a hybrid automatic repeat request (HARQ) timing offset indication based on a number of reserved slots rather than a number of total slots.

In some cases, the UE may be capable of dual uplink transmission on the NR carrier and the LTE carrier during the unreserved time slots. The core network may prioritize the uplink channels of the MCG and SCG if the UE is capable of dynamic power control. For example, the MCG uplink control channel may have a higher priority than the SCG uplink control channel, or the MCG uplink data channel may have the same priority as the SCG uplink data channel, or any MCG uplink channel may have a higher priority than the corresponding SCG uplink channel, among other configurations. The UE may be configured to reduce or decrease the transmit power of the channel based on the priority of the channel and the transmission start time of the channel. In some other examples, the time slots reserved for LTE and the time slots reserved for NR may have different power configurations. For example, the exclusive reserved time slot may have a larger transmit power limit. The unreserved time slots may have a smaller transmit power limit. The UE may follow a maximum power level independently configured for MCG and SCG.

A method of wireless communication at a UE is described. The method can comprise the following steps: identifying that the UE is operating in dual connectivity with a primary cell group and a secondary cell group; receiving, from a primary cell group, an indication of a reserved Transmission Time Interval (TTI) reserved for priority Uplink (UL) communications with the primary cell group; identifying an additional TTI that can be used for UL communication with a primary cell group or a secondary cell group; transmitting one or more UL messages to the primary cell group using the reserved TTI; and transmitting one or more UL messages to the primary cell group or the secondary cell group using the additional TTIs.

An apparatus for wireless communication at a UE is described. The apparatus may include a processor, a memory in electronic communication with the processor, and instructions stored in the memory. The instructions are executable by the processor to cause the apparatus to: identifying that the UE is operating in dual connectivity with a primary cell group and a secondary cell group; receiving, from a primary cell group, an indication of a reserved TTI reserved for priority UL communication with the primary cell group; identifying an additional TTI that can be used for UL communication with a primary cell group or a secondary cell group; transmitting one or more UL messages to the primary cell group using the reserved TTI; and transmitting one or more UL messages to the primary cell group or the secondary cell group using the additional TTIs.

Another apparatus for wireless communication at a UE is described. The apparatus may include: identifying that the UE is operating in dual connectivity with a primary cell group and a secondary cell group, receiving an indication of a reserved TTI reserved for priority UL communication with the primary cell group from the primary cell group; identifying an additional TTI that can be used for UL communication with a primary cell group or a secondary cell group; transmitting one or more UL messages to the primary cell group using the reserved TTI; and transmitting one or more UL messages to the primary cell group or the secondary cell group using the additional TTIs.

A non-transitory computer-readable medium storing code for wireless communication at a UE is described. The code may include instructions executable by a processor for: identifying that the UE is operating in dual connectivity with a primary cell group and a secondary cell group, receiving an indication of a reserved TTI reserved for priority UL communication with the primary cell group from the primary cell group; identifying an additional TTI that can be used for UL communication with a primary cell group or a secondary cell group; transmitting one or more UL messages to the primary cell group using the reserved TTI; and transmitting one or more UL messages to the primary cell group or the secondary cell group using the additional TTIs.

Some examples of the methods, apparatus (devices), and non-transitory computer-readable media described herein may further include operations, features, means, or instructions for: the method may include receiving, from a secondary cell group, an indication of additional reserved TTIs that may be reserved for UL communication with the secondary cell group, wherein the reserved TTIs and the additional reserved TTIs may be disjoint in time, and transmitting one or more UL messages to the secondary cell group using the additional reserved TTIs. Some examples of the methods, apparatus (devices), and non-transitory computer-readable media described herein may further include operations, features, means, or instructions for: receiving a schedule that utilizes one or more additional TTIs for UL communication with the primary cell group or the secondary cell group that facilitates avoiding UL transmissions to both the primary cell group and the secondary cell group at the same time, wherein transmitting one or more UL messages using the additional TTIs may be in accordance with the schedule.

Some examples of the methods, apparatus (devices), and non-transitory computer-readable media described herein may further include operations, features, means, or instructions for: the method may include determining that a UL message to a primary cell group and a UL message to a secondary cell group may both be scheduled for the same one of additional TTIs, identifying a priority between the UL message to the primary cell group and the UL message to the secondary cell group, and transmitting one of the UL message to the primary cell group or the UL message to the secondary cell group during the TTI based on the priority. In some examples of the methods, apparatuses (devices), and non-transitory computer-readable media described herein, receiving an indication of a reserved TTI may include operations, features, apparatuses, or instructions to: a Slot Format Indication (SFI) is received that identifies a configuration for an UL TTI, a Downlink (DL) TTI, an unknown TTI, or a combination thereof, wherein the reserved TTI includes the UL TTI.

In some examples of the methods, apparatuses (devices), and non-transitory computer-readable media described herein, receiving an SFI may include operations, features, apparatuses, or instructions for: a configured SFI is received that is cell-specific. In some examples of the methods, apparatuses (devices), and non-transitory computer-readable media described herein, receiving an SFI may include operations, features, apparatuses, or instructions for: receiving a UE-specific configured SFI, wherein the UE-specific configured SFI overrides any received cell-specific configured SFI. In some examples of the methods, apparatuses (devices), and non-transitory computer-readable media described herein, receiving an SFI may include operations, features, apparatuses, or instructions for: a dynamic SFI is received via DCI, where the dynamic SFI may be specific to an upcoming TTI or set of TTIs.

In some examples of the methods, apparatuses (devices), and non-transitory computer-readable media described herein, the indication further indicates a DL TTI, an unknown TTI, or both that may be reserved for communication with the primary cell group. In some examples of the methods, apparatuses (devices), and non-transitory computer-readable media described herein, a primary cell group may be configured for Time Division Duplex (TDD) operation, while a secondary cell group may be configured for Frequency Division Duplex (FDD) operation. Some examples of the methods, apparatus (devices), and non-transitory computer-readable media described herein may further include operations, features, means, or instructions for: both the primary and secondary cell groups may be configured for FDD operation. In some examples of the methods, apparatuses (devices), and non-transitory computer-readable media described herein, a primary cell group may be configured for TDD operation and a secondary cell group may be configured for FDD operation, where UL transmissions to the secondary cell group are time-shared with Supplemental Uplink (SUL) transmissions to the primary cell group.

Some examples of the methods, apparatus (devices), and non-transitory computer-readable media described herein may further include operations, features, means, or instructions for: both the primary cell group and the secondary cell group may be configured for TDD operation. Some examples of the methods, apparatus (devices), and non-transitory computer-readable media described herein may further include operations, features, means, or instructions for: an FDD timing configuration for UL transmissions to a secondary cell group is identified that facilitates avoiding UL transmissions to both the primary cell group and the secondary cell group at the same time, wherein transmitting one or more UL messages using additional TTIs can be in accordance with the FDD timing configuration.

In some examples of the methods, apparatuses (devices), and non-transitory computer-readable media described herein, the one or more UL messages transmitted using the additional TTIs include an LTE Physical Random Access Channel (PRACH) message, a Sounding Reference Signal (SRS) message, an HARQ message, or a combination thereof. Some examples of the methods, apparatus (devices), and non-transitory computer-readable media described herein may further include operations, features, means, or instructions for: a joint configuration is received that includes an indication of reserved TTIs that may be reserved for UL or DL communications with the primary cell group and an indication of which additional TTIs may be used for UL or DL communications with the primary cell group and which additional TTIs may be used for UL or DL communications with the secondary cell group.

Some examples of the methods, apparatus (devices), and non-transitory computer-readable media described herein may further include operations, features, means, or instructions for: a prioritization configuration is received that includes an indication of reserved TTIs that may be reserved for UL or DL communications with a primary cell group and an indication of which additional TTIs may be used for UL or DL communications with the primary cell group. In some examples of the methods, apparatuses (devices), and non-transitory computer-readable media described herein, transmitting one or more UL messages to a primary cell group or a secondary cell group using additional TTIs may include operations, features, apparatuses, or instructions to: transmitting one or more UL messages to the secondary cell group during one of the additional TTIs indicated for DL communication with the primary cell group.

Some examples of the methods, apparatus (devices), and non-transitory computer-readable media described herein may further include operations, features, means, or instructions for: a parameter is identified that indicates a time offset for UL transmission of HARQ feedback after receipt of the data message, wherein the time offset may be transmitted for the number of reserved TTIs and in accordance with the parameter. In some examples of the methods, apparatuses (devices), and non-transitory computer-readable media described herein, transmitting one or more UL messages to a primary cell group or a secondary cell group using additional TTIs may include operations, features, apparatuses, or instructions to: the UL message is transmitted to the primary cell group and the secondary cell group during different TTIs. In some examples of the methods, apparatuses (devices), and non-transitory computer-readable media described herein, transmitting one or more UL messages to a primary cell group or a secondary cell group using additional TTIs may include operations, features, apparatuses, or instructions to: transmitting the UL message to the primary cell group and the secondary cell group during the same TTI.

Some examples of the methods, apparatus (devices), and non-transitory computer-readable media described herein may further include operations, features, means, or instructions for: power control is prioritized for each of the UL messages transmitted during the same TTI based on the type of UL message. Some examples of the methods, apparatus (devices), and non-transitory computer-readable media described herein may further include operations, features, means, or instructions for: power control is prioritized for each of the UL messages transmitted during the same TTI based on a start time of each UL message. In some examples of the methods, apparatuses (devices), and non-transitory computer-readable media described herein, a maximum power control for UL messages transmitted to a primary cell group and a maximum power control for UL messages transmitted to a secondary cell group during the same TTI may each be less than the respective power controls for UL transmissions during different TTIs.

Some examples of the methods, apparatus (devices), and non-transitory computer-readable media described herein may further include operations, features, means, or instructions for: the method includes identifying a first TTI duration associated with a primary cell group, identifying a second TTI duration associated with a secondary cell group, and applying a transmission power control scheme based at least in part on the first TTI duration and the second TTI duration. In some examples of the methods, apparatuses (devices), and non-transitory computer-readable media described herein, applying the transmission power control scheme further comprises adjusting the transmission power for the UL message transmitted to the primary cell group and the UL message transmitted to the secondary cell group after the TTI of the first TTI duration based at least in part on the first TTI duration being longer than the second TTI duration. In some examples of the methods, apparatuses (devices), and non-transitory computer-readable media described herein, applying the transmission power control scheme further comprises adjusting the transmission power for the UL message transmitted to the primary cell group and the UL message transmitted to the secondary cell group after a TTI of the second TTI duration based at least in part on the second TTI duration being longer than the first TTI duration.

A method of wireless communication at a base station is described. The method can comprise the following steps: identifying that a base station is operating as a primary cell group in dual connectivity with a UE; transmitting, to the UE, an indication of a reserved TTI reserved for priority UL communication with the primary cell group; indicating to the secondary cell group a reserved TTI and an additional TTI available for UL communication with the primary cell group or the secondary cell group; and receiving one or more UL messages from the UE using the reserved TTI.

An apparatus for wireless communication at a base station is described. The apparatus may include a processor, a memory in electronic communication with the processor, and instructions stored in the memory. The instructions are executable by the processor to cause the apparatus to: identifying that a base station is operating as a primary cell group in dual connectivity with a UE; transmitting, to the UE, an indication of a reserved TTI reserved for priority UL communication with the primary cell group; indicating to the secondary cell group a reserved TTI and an additional TTI available for UL communication with the primary cell group or the secondary cell group; and receiving one or more UL messages from the UE using the reserved TTI.

Another apparatus for wireless communication at a base station is described. The apparatus may include: identifying that a base station is operating as a primary cell group in dual connectivity with a UE; transmitting, to the UE, an indication of a reserved TTI reserved for priority UL communication with the primary cell group; indicating to the secondary cell group a reserved TTI and an additional TTI available for UL communication with the primary cell group or the secondary cell group; and receiving one or more UL messages from the UE using the reserved TTI.

A non-transitory computer-readable medium storing code for wireless communication at a base station is described. The code may include instructions executable by a processor for: identifying that a base station is operating as a primary cell group in dual connectivity with a UE; transmitting, to the UE, an indication of a reserved TTI reserved for priority UL communication with the primary cell group; indicating to the secondary cell group a reserved TTI and an additional TTI available for UL communication with the primary cell group or the secondary cell group; and receiving one or more UL messages from the UE using the reserved TTI.

Some examples of the methods, apparatus (devices), and non-transitory computer-readable media described herein may further include operations, features, means, or instructions for: the method includes transmitting a schedule that utilizes one or more additional TTIs for UL communication with the primary cell group or the secondary cell group that facilitates avoiding UL transmissions to both the primary cell group and the secondary cell group at the same time. In some examples of the methods, apparatuses (devices), and non-transitory computer-readable media described herein, transmitting an indication of a reserved TTI may include operations, features, apparatuses, or instructions to: transmitting an SFI identifying a configuration for an UL TTI, a DLTTI, an unknown TTI, or a combination thereof, wherein the reserved TTI comprises an UL TTI. In some examples of the methods, apparatuses (devices), and non-transitory computer-readable media described herein, transmitting the SFI may include operations, features, apparatuses, or instructions for: transmitting a cell-specific configured SFI.

In some examples of the methods, apparatuses (devices), and non-transitory computer-readable media described herein, transmitting the SFI may include operations, features, apparatuses, or instructions for: transmitting a UE-specific configured SFI, wherein the UE-specific configured SFI overrides any previously transmitted cell-specific configured SFI. In some examples of the methods, apparatuses (devices), and non-transitory computer-readable media described herein, transmitting the SFI may include operations, features, apparatuses, or instructions for: a dynamic SFI is transmitted via the DCI, where the dynamic SFI may be specific to an upcoming TTI or set of TTIs. In some examples of the methods, apparatuses (devices), and non-transitory computer-readable media described herein, the indication further indicates a DL TTI, an unknown TTI, or both that may be reserved for communication with the primary cell group. In some examples of the methods, apparatus (devices), and non-transitory computer-readable media described herein, a primary cell group may be configured for TDD operation and a secondary cell group may be configured for FDD operation.

Some examples of the methods, apparatus (devices), and non-transitory computer-readable media described herein may further include operations, features, means, or instructions for: both the primary and secondary cell groups may be configured for FDD operation. In some examples of the methods, apparatuses (devices), and non-transitory computer-readable media described herein, a primary cell group may be configured for TDD operation and a secondary cell group may be configured for FDD operation, where UL transmissions to the secondary cell group are time-shared with SUL transmissions to the primary cell group. Some examples of the methods, apparatus (devices), and non-transitory computer-readable media described herein may further include operations, features, means, or instructions for: both the primary cell group and the secondary cell group may be configured for TDD operation.

Some examples of the methods, apparatus (devices), and non-transitory computer-readable media described herein may further include operations, features, means, or instructions for: an FDD timing configuration for UL transmissions to the secondary cell group is indicated to the UE, the FDD timing configuration facilitating avoidance of UL transmissions to both the primary cell group and the secondary cell group at the same time. Some examples of the methods, apparatus (devices), and non-transitory computer-readable media described herein may further include operations, features, means, or instructions for: transmitting, to the UE, a joint configuration that includes an indication of reserved TTIs that may be reserved for UL or DL communication with the primary cell group, and an indication of which additional TTIs may be used for UL or DL communication with the primary cell group and which additional TTIs may be used for UL or DL communication with the secondary cell group.

Some examples of the methods, apparatus (devices), and non-transitory computer-readable media described herein may further include operations, features, means, or instructions for: transmitting a prioritization configuration to the UE, the prioritization configuration including an indication of reserved TTIs that may be reserved for UL or DL communication with the primary cell group, and an indication of which additional TTIs may be used for UL or DL communication with the primary cell group. Some examples of the methods, apparatus (devices), and non-transitory computer-readable media described herein may further include operations, features, means, or instructions for: transmitting a parameter to the UE indicating a time offset for UL transmission of HARQ feedback after receipt of the data message, wherein the time offset may be by a number of reserved TTIs, and receiving the HARQ feedback according to the parameter.