Non-periodic sounding reference signal transmission and triggering configuration

Abstract

Methods, systems, and devices for wireless communication that support configuration of aperiodic sounding reference signal transmissions and triggers are described. A base station can transmit, within a first transmission time interval (TTI), a grant that triggers a user equipment (UE) to transmit an aperiodic sounding reference signal (A-SRS), and can identify offset information that indicates a TTI offset relative to the grant. The base station can determine a second TTI for the A-SRS based on the TTI offset. A UE can detect, within the first TTI, the grant that triggers the UE to transmit the A-SRS; identify the offset information that indicates the TTI offset relative to the grant; and determine a second TTI for transmitting the A-SRS based on the TTI offset. The UE can transmit the A-SRS in an SRS resource of the second TTI, and the base station can monitor the SRS resource of the second TTI for the A-SRS.

Description

[0001] This Patent Application is a Continuation of International Application No. PCT / US2019 / 017195, International Filing Date February 8, 2019, entitled “Configuration of Aperiodic Sounding Reference Signal Transmission and Triggering,” assigned to the assignee hereof, and claims priority to U.S. Provisional Patent Application No. 62 / 801,000, filed February 1 1, 2019, entitled “Configuration of Aperiodic Sounding Reference Signal Transmission and Triggering,” assigned to the assignee hereof.

[0002] CROSS-REFERENCE TO RELATED APPLICATIONS

[0003] This Patent Application claims the benefit of Greek Provisional Patent Application No. 20180100057, entitled “Configuration of Aperiodic Sounding Reference Signal Transmission and Triggering,” filed February 15, 2018, by Manolakos et al., and U.S. Patent Application No. 16 / 269,903, entitled “Configuration of Aperiodic Sounding Reference Signal Transmission and Triggering,” filed February 7, 2019, by Manolakos et al., each of which is assigned to the assignee hereof. TECHNICAL FIELD

[0004] The following relates generally to wireless communication, and more specifically to configuration of aperiodic sounding reference signal transmission and triggering. BACKGROUND

[0005] 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 can 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 can be referred to as New Radio (NR) systems. These systems can 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 can include a number of base stations or network access nodes, each simultaneously supporting communication for multiple communication devices, which can be otherwise known as user equipment (UE).

[0006] In some examples of a wireless communication system, communications between a UE and a base station can include communications of sounding reference signals (SRS). SRS can be a signal known to each of the UE and the base station. The UE can transmit SRS, and the base station can receive and measure the SRS for generating a channel estimate of a wireless channel between the UE and the base station. In some cases, the base station can use the channel estimate to identify whether a particular frequency band is experiencing a high level of interference and / or noise, and make a frequency-dependent scheduling determination based on one or more determined channel estimates. In some examples, SRS can be transmitted aperiodically, semi-persistently, or periodically. However, SRS transmission schemes in conventional wireless communication systems are deficient. SUMMARY

[0007] The described techniques relate to improved methods, systems, devices, or apparatuses that support aperiodic sounding reference signal transmission and configuration of triggers. Generally, the described techniques provide for aperiodic triggering of a user equipment (UE) to transmit a sounding reference signal (SRS) in a transmission time interval (TTI) relative to a TTI in which the UE receives a grant. In some examples, a UE can receive a grant triggering transmission of an aperiodic SRS, and the UE can identify offset information indicating a TTI offset between a TTI in which the triggering grant is received and a TTI in which the aperiodic SRS is to be transmitted. In some examples, the TTI in which the aperiodic SRS is to be transmitted can be a function of an amount of time the UE needs to process the grant (relative to when the UE is able to transmit according to the grant).

[0008] In some examples, a UE can receive a downlink control information (DCI) including a downlink grant or an uplink grant, and in response, the UE can transmit a SRS to a base station in a TTI relative to a TTI including the grant. In some examples, the UE can transmit the SRS on a SRS resource in an earliest available TTI after the TTI in which the grant is received, which can be as early as the same TTI including the grant. In some examples, the transmission timing of the SRS can be identified based on TTI offset information. The TTI offset information can be preconfigured to the UE, or received via RRC signaling, or included in the DCI. The UE can identify the TTI offset information and determine the TTI offset, and can use the TTI offset to determine in which TTI relative to the TTI in which the grant is received the SRS is to be transmitted.

[0009] In some cases, a UE can signal its capabilities to a base station, or the base station can be aware of default UE capabilities for UEs operating within a wireless communications system. The base station can determine in which TTI a UE is to be instructed to transmit uplink data or receive downlink data, and generate a grant accordingly. The base station can also identify in which TTI a UE is expected to transmit a SRS relative to the grant based on the signaled UE capabilities or default capabilities. The base station can monitor the SRS resource of the expected TTI for the SRS. Beneficially, the UE can be configured to transmit the SRS at the earliest or earliest available TTI after receiving the DCI.

[0010] A method of wireless communication is described. The method can include detecting, within a first TTI, a grant that triggers a UE to transmit an aperiodic sounding reference signal (A-SRS), identifying offset information that indicates a TTI offset relative to the grant, determining a second TTI for transmitting the A-SRS based at least in part on the TTI offset, and transmitting the A-SRS in a SRS resource of the second TTI.

[0011] An apparatus for wireless communication is described. The apparatus can include means for detecting, within a first TTI, a grant that triggers a UE to transmit an A-SRS, means for identifying offset information that indicates a TTI offset relative to the grant, means for determining a second TTI for transmitting the A-SRS based at least in part on the TTI offset, and means for transmitting the A-SRS in a SRS resource of the second TTI.

[0012] Another apparatus for wireless communication is described. The apparatus can include a processor, memory in electronic communication with the processor, and instructions stored in the memory. The instructions can be operable to cause the processor to detect, within a first TTI, a grant that triggers a UE to transmit an A-SRS, identify offset information that indicates a TTI offset relative to the grant, determine a second TTI for transmitting the A-SRS based at least in part on the TTI offset, and transmit the A-SRS in a SRS resource of the second TTI.

[0013] A non-transitory computer-readable medium for wireless communication is described. The non-transitory computer-readable medium can include instructions operable to cause a processor to detect, within a first TTI, a grant that triggers a UE to transmit an A-SRS, identify offset information that indicates a TTI offset relative to the grant, determine a second TTI for transmitting the A-SRS based at least in part on the TTI offset, and transmit the A-SRS in a SRS resource of the second TTI.

[0014] In some examples of the method, apparatus, and non-transitory computer-readable medium described above, receiving the configuration information configures the UE to transmit the A-SRS within at least one symbol index of a plurality of different symbol indexes of the TTI, where transmitting the A-SRS in the SRS resource of the second TTI further comprises transmitting the A-SRS within at least one symbol period of the second TTI corresponding to the at least one symbol index.

[0015] In some examples of the method, apparatus, and non-transitory computer-readable medium described above, identifying the offset information further comprises receiving the offset information in downlink control information of the first TTI, where the offset information indicates a delay corresponding to a number of TTIs occurring between receiving the grant by the UE and the UE being able to transmit uplink data according to the grant.

[0016] In some examples of the method, apparatus, and non-transitory computer-readable medium described above, determining the second TTI further comprises determining a TTI index after the delay indicated in the offset information, where the second TTI corresponds to the TTI index.

[0017] Some examples of the method, apparatus, and non-transitory computer-readable medium described above can further include processes, features, means, or instructions for transmitting capability information indicating a number of symbol periods between receiving the grant by the UE and the UE being able to transmit uplink data according to the grant, where the delay corresponds to the capability information.

[0018] In some examples of the method, apparatus, and non-transitory computer-readable medium described above, the delay corresponds to specified capability information indicating a number of symbol periods between receiving the grant by the UE and the UE being able to transmit uplink data according to the grant.

[0019] Some examples of the method, apparatus, and non-transitory computer-readable medium described above can further include processes, features, means, or instructions for receiving downlink control information of the first TTI including offset information, where the grant indicates resources of a shared data channel allocated to the UE for transmission of uplink data, and where the offset information can be a bit flag indicating whether the UE can use a first value for a TTI offset indicated in the downlink control information or a second semi-statically configured value for a TTI offset.

[0020] Some examples of the method, apparatus, and non-transitory computer-readable medium described above can further include processes, features, means, or instructions for receiving downlink control information of the first TTI including offset information, where the grant indicates resources in the shared data channel allocated to the UE for transmission of uplink data, and where the offset information includes a bit sequence corresponding to a number of TTIs occurring between reception of the grant by the UE and when the UE can be instructed to transmit uplink data according to the grant.

[0021] Some examples of the method, apparatus, and non-transitory computer-readable medium described above can further include processes, features, means, or instructions for receiving downlink control information of the first TTI including offset information, where the grant indicates resources in the shared data channel allocated to the UE for transmission of uplink data, and where the offset information includes a bit sequence corresponding to a number of TTIs occurring between reception of the grant by the UE and when the UE can be instructed to transmit uplink data according to the grant.

[0022] Some examples of the method, apparatus, and non-transitory computer-readable medium described above can further include processes, features, means, or instructions for receiving control signaling that semi-statically indicates a defined value, where the second value for the TTI offset is a function of the first value for the TTI offset and the defined value.

[0023] In some examples of the method, apparatus, and non-transitory computer-readable medium described above, the first value indicates a gap in TTIs between requesting the grant for uplink data and transmission of the uplink data, and the second TTI can be a TTI occurring before a TTI corresponding to the first value.

[0024] Some examples of the method, apparatus, and non-transitory computer-readable medium described above can further include processes, features, means, or instructions for receiving downlink control information of the first TTI including offset information, where the grant indicates resources in the shared data channel allocated to the UE for reception of downlink data.

[0025] In some examples of the method, apparatus, and non-transitory computer-readable medium described above, the offset information can be a bit sequence included within the downlink control information of the first TTI, the bit sequence corresponding to a number of TTIs occurring between reception of the grant by the UE and when the UE can be instructed to transmit uplink data according to the grant.

[0026] In some examples of the method, apparatus, and non-transitory computer-readable medium described above, the bit sequence can be configured to jointly trigger transmission of a zero-power channel state information reference signal (CSIRS) from the base station and transmission of the A-SPS from the UE.

[0027] In some examples of the method, apparatus, and non-transitory computer-readable medium described above, identifying the second TTI further comprises identifying the second TTI as being offset from the first TTI by a TTI offset.

[0028] In some examples of the method, apparatus, and non-transitory computer-readable medium described above, identifying the second TTI comprises determining that the TTI offset can be a zero TTI offset, where the second TTI and the first TTI can be a same TTI.

[0029] In some examples of the method, apparatus, and non-transitory computer-readable medium described above, identifying the offset information further comprises receiving control signaling that semi-statically configures the UE with the offset information.

[0030] In some examples of the method, apparatus, and non-transitory computer-readable medium described above, identifying the offset information further comprises receiving downlink control information of the first TTI that includes the offset information for dynamically configuring the UE with the TTI offset.

[0031] In some examples of the method, apparatus, and non-transitory computer-readable medium described above, identifying the offset information further comprises retrieving the offset information from a memory, where the UE can be preconfigured with the offset information.

[0032] In some examples of the method, apparatus, and non-transitory computer-readable medium described above, the SRS resource corresponds to a subset of symbol periods within the second TTI.

[0033] A method of wireless communication is described. The method can include detecting, within a first TTI, a grant that triggers a UE to transmit an A-SRS, identifying a second TTI based at least in part on a first number of symbol periods between reception of the grant by the UE and an ability of the UE to transmit uplink data, the first number of symbol periods satisfying or being less than a difference between a number of symbol periods between an SRS resource of the second TTI and a control channel of the first TTI, and transmitting the A-SRS in the SRS resource of the second TTI.

[0034] An apparatus for wireless communication is described. The apparatus can include means for detecting, within a first TTI, a grant triggering a UE to transmit an A-SRS, means for identifying a second TTI based at least in part on a first number of symbol periods between when the grant is received by the UE and when the UE is able to transmit uplink data, the first number of symbol periods meeting or being less than a difference between a number of symbol periods between an SRS resource of the second TTI and a control channel of the first TTI, and means for transmitting the A-SRS in the SRS resource of the second TTI.

[0035] Another apparatus for wireless communication is described. The apparatus can include a processor, memory in electronic communication with the processor, and instructions stored in the memory. The instructions can be operable to cause the processor to detect, within a first TTI, a grant triggering a UE to transmit an A-SRS, identify a second TTI based at least in part on a first number of symbol periods between when the grant is received by the UE and when the UE is able to transmit uplink data, the first number of symbol periods meeting or being less than a difference between a number of symbol periods between an SRS resource of the second TTI and a control channel of the first TTI, and transmit the A-SRS in the SRS resource of the second TTI.

[0036] A non-transitory computer-readable medium for wireless communication is described. The non-transitory computer-readable medium can include instructions operable to cause a processor to detect, within a first TTI, a grant triggering a UE to transmit an A-SRS, identify a second TTI based at least in part on a first number of symbol periods between when the grant is received by the UE and when the UE is able to transmit uplink data, the first number of symbol periods meeting or being less than a difference between a number of symbol periods between an SRS resource of the second TTI and a control channel of the first TTI, and transmit the A-SRS in the SRS resource of the second TTI.

[0037] In some examples of the method, apparatus, and non-transitory computer-readable medium described above, the receiving configuration information configures the UE to transmit the A-SRS within at least one symbol index of a plurality of different symbol indexes of a TTI, where the transmitting the A-SRS in the SRS resource of the second TTI further includes transmitting the A-SRS within at least one symbol period of the second TTI corresponding to the at least one symbol index.

[0038] Some examples of the method, apparatus, and non-transitory computer-readable medium described above can further include processes, features, means, or instructions for transmitting capability information indicating the first number of symbol periods.

[0039] In some examples of the method, apparatus, and non-transitory computer-readable medium described above, the grant indicates resources in the shared data channel allocated to the UE for reception of downlink data.

[0040] In some examples of the method, apparatus, and non-transitory computer-readable medium described above, identifying the second TTI further includes identifying the second TTI based at least in part on a maximum of a second number of symbol periods between reception of the grant by the UE and when the UE can be able to receive the downlink data.

[0041] In some examples of the method, apparatus, and non-transitory computer-readable medium described above, identifying the second TTI further includes determining a maximum of the first number of symbol periods and the second number of symbol periods.

[0042] In some examples of the method, apparatus, and non-transitory computer-readable medium described above, receiving configuration information that configures the UE to transmit the A-SRS within at least one symbol index of a plurality of different symbol indexes of TTIs, where transmitting the A-SRS in the SRS resource of the second TTI further includes transmitting the A-SRS within at least one symbol period of the second TTI corresponding to the at least one symbol index, where the number of symbol periods between the at least one symbol period of the second TTI and the control channel of the first TTI meets or exceeds the maximum.

[0043] Some examples of the method, apparatus, and non-transitory computer-readable medium described above can further include processes, features, means, or instructions for transmitting capability information indicating the first number of symbol periods and the second number of symbol periods.

[0044] In some examples of the method, apparatus, and non-transitory computer-readable medium described above, the first number of symbol periods and the second number of symbol periods can be a specified capability of the UE.

[0045] In some examples of the method, apparatus, and non-transitory computer-readable medium described above, identifying the second TTI includes determining that the second TTI and the first TTI can be a same TTI.

[0046] In some examples of the method, apparatus, and non-transitory computer-readable medium described above, identifying the second TTI includes identifying the second TTI based at least in part on a maximum of a channel state information reference signal (CSI RS) gap and a UE capability delay.

[0047] Some examples of the method, apparatus, and non-transitory computer-readable medium described above can further include processes, features, means, or instructions for processing a usage scenario indication indicating whether the A-SRS can be associated with a channel state information reference signal (CSI RS).

[0048] A method of wireless communication is described. The method can include transmitting a grant triggering a UE to transmit an A-SRS within a first transmission time interval (TTI), identifying offset information indicating a TTI offset relative to the grant, determining a second TTI for the A-SRS based at least in part on the TTI offset, and monitoring SRS resources of the second TTI for the A-SRS.

[0049] An apparatus for wireless communication is described. The apparatus can include means for transmitting a grant triggering a UE to transmit an A-SRS within a first TTI, means for identifying offset information indicating a TTI offset relative to the grant, means for determining a second TTI for the A-SRS based at least in part on the TTI offset, and means for monitoring SRS resources of the second TTI for the A-SRS.

[0050] Another apparatus for wireless communication is described. The apparatus can include a processor, memory in electronic communication with the processor, and instructions stored in the memory. The instructions can be operable to cause the processor to transmit a grant triggering a UE to transmit an A-SRS within a first TTI, identify offset information indicating a TTI offset relative to the grant, determine a second TTI for the A-SRS based at least in part on the TTI offset, and monitor SRS resources of the second TTI for the A-SRS.

[0051] A non-transitory computer-readable medium for wireless communication is described. The non-transitory computer-readable medium can include instructions operable to cause a processor to transmit a grant triggering a UE to transmit an A-SRS within a first TTI, identify offset information indicating a TTI offset relative to the grant, determine a second TTI for the A-SRS based at least in part on the TTI offset, and monitor SRS resources of the second TTI for the A-SRS.

[0052] In some examples of the method, apparatus, and non-transitory computer-readable medium described above, transmitting the configuration information to configure the UE to transmit the A-SRS within at least one symbol index of a plurality of different symbol indexes of a TTI, where monitoring the SRS resources of the second TTI for the A-SRS further includes monitoring at least one symbol period in the second TTI corresponding to the at least one symbol index for the A-SRS.

[0053] Some examples of the method, apparatus, and non-transitory computer-readable medium described above can further include processes, features, means for, or instructions for transmitting, within the first TTI, downlink control information including offset information, where the offset information indicates a delay corresponding to a number of TTIs occurring between receiving the grant by the UE and being able to transmit uplink data by the UE according to the grant.

[0054] In some examples of the method, apparatus, and non-transitory computer-readable medium described above, the offset information corresponds to a TTI index after the delay, and where the second TTI corresponds to the TTI index.

[0055] Some examples of the method, apparatus, and non-transitory computer-readable medium described above can further include processes, features, means for, or instructions for receiving capability information indicating a number of symbol periods between receiving the grant by the UE and being able to transmit uplink data by the UE according to the grant, where the delay corresponds to the capability information.

[0056] In some examples of the method, apparatus, and non-transitory computer-readable medium described above, the delay corresponds to specified capability information indicating a number of symbol periods between receiving the grant by the UE and being able to transmit uplink data by the UE according to the grant.

[0057] Some examples of the method, apparatus, and non-transitory computer-readable medium described above can further include processes, features, means for, or instructions for transmitting, in a first TTI, downlink control information including offset information, where the grant indicates resources in a shared data channel allocated to the UE for transmission of uplink data, and where the offset information includes a bit flag indicating whether a first value for a TTI offset indicated in the downlink control information or a second semi-statically configured value for a TTI offset is to be used by the UE.

[0058] Some examples of the method, apparatus, and non-transitory computer-readable medium described above can further include processes, features, means for, or instructions for transmitting, in a first TTI, downlink control information including offset information, where the grant indicates resources in a shared data channel allocated to the UE for transmission of uplink data, and where the offset information includes a bit sequence indicating that a TTI offset corresponds to a number of TTIs occurring between receiving the grant by the UE and being able to transmit uplink data by the UE according to the grant.

[0059] Some examples of the method, apparatus, and non-transitory computer-readable medium described above can further include processes, features, means for, or instructions for transmitting, in the first TTI, downlink control information including offset information, where the grant indicates resources in the shared data channel allocated to the UE for transmission of uplink data, where the offset information includes a bit flag indicating whether the UE can use a first value for a TTI offset or a second value for a TTI offset indicated in the downlink control information.

[0060] Some examples of the method, apparatus, and non-transitory computer-readable medium described above can further include processes, features, means for, or instructions for transmitting control signaling that semi-statically indicates a defined value, where the second value for a TTI offset can be a function of the first value for a TTI offset and the defined value.

[0061] In some examples of the method, apparatus, and non-transitory computer-readable medium described above, the first value indicates a gap between requesting a grant for uplink data and transmission of the uplink data in TTIs, and the second TTI can be a TTI that occurs before a TTI corresponding to the first value.

[0062] Some examples of the method, apparatus, and non-transitory computer-readable medium described above can further include processes, features, means for, or instructions for transmitting, in the first TTI, downlink control information including offset information, where the grant indicates resources in the shared data channel allocated to the UE for reception of downlink data.

[0063] In some examples of the method, apparatus, and non-transitory computer-readable medium described above, the offset information includes a bit sequence corresponding to a number of TTIs that occur between receiving the grant by the UE and when the UE can be instructed to transmit uplink data according to the grant.

[0064] In some examples of the method, apparatus, and non-transitory computer-readable medium described above, the bit sequence can be configured to jointly trigger transmission of a zero-power CSIRS from a base station and transmission of an A-SPS from the UE.

[0065] In some examples of the method, apparatus, and non-transitory computer-readable medium described above, identifying the second TTI further includes identifying the second TTI as being offset from the first TTI by a TTI offset.

[0066] Some examples of the method, apparatus, and non-transitory computer-readable medium described above can further include processes, features, means, or instructions for receiving the A-SRS within the SRS resource of the second TTI. Some examples of the method, apparatus, and non-transitory computer-readable medium described above can further include processes, features, means, or instructions for generating a channel measurement based at least in part on the received A-SRS. Some examples of the method, apparatus, and non-transitory computer-readable medium described above can further include processes, features, means, or instructions for generating a frequency-dependent scheduling decision based at least in part on the channel measurement.

[0067] Some examples of the method, apparatus, and non-transitory computer-readable medium described above can further include processes, features, means, or instructions for transmitting control signaling to semi-statically configure the UE with the offset information.

[0068] Some examples of the method, apparatus, and non-transitory computer-readable medium described above can further include processes, features, means, or instructions for transmitting downlink control information within the first TTI to dynamically configure the UE with the offset information.

[0069] In some examples of the method, apparatus, and non-transitory computer-readable medium described above, the UE can be preconfigured with the TTI offset.

[0070] In some examples of the method, apparatus, and non-transitory computer-readable medium described above, the SRS resource corresponds to a subset of symbol periods within the second TTI.

[0071] In some examples of the method, apparatus, and non-transitory computer-readable medium described above, identifying the second TTI includes determining that the TTI offset can be a zero TTI offset, where the second TTI and the first TTI can be a same TTI.

[0072] A method of wireless communication is described. The method can include transmitting, within a first TTI, a grant that triggers a UE to transmit an A-SRS, identifying a second TTI based at least in part on a first number of symbol periods between receiving the grant by the UE and when the UE can transmit uplink data, the first number of symbol periods satisfying or being less than a difference between a number of symbol periods between an SRS resource of the second TTI and a control channel of the first TTI, and monitoring the SRS resource of the second TTI for the A-SRS.

[0073] An apparatus for wireless communication is described. The apparatus can include means for transmitting, within a first TTI, a grant that triggers a UE to transmit an A-SRS, means for identifying a second TTI based at least in part on a first number of symbol periods between when the grant is received by the UE and when the UE is able to transmit uplink data, the first number of symbol periods meeting or being less than a difference between a number of symbol periods between an SRS resource of the second TTI and a control channel of the first TTI, and means for monitoring the SRS resource of the second TTI for the A-SRS.

[0074] Another apparatus for wireless communication is described. The apparatus can include a processor, memory in electronic communication with the processor, and instructions stored in the memory. The instructions can be operable to cause the processor to transmit, within a first TTI, a grant that triggers a UE to transmit an A-SRS, identify a second TTI based at least in part on a first number of symbol periods between when the grant is received by the UE and when the UE is able to transmit uplink data, the first number of symbol periods meeting or being less than a difference between a number of symbol periods between an SRS resource of the second TTI and a control channel of the first TTI, and monitor the SRS resource of the second TTI for the A-SRS.

[0075] A non-transitory computer-readable medium for wireless communication is described. The non-transitory computer-readable medium can include instructions operable to cause a processor to transmit, within a first TTI, a grant that triggers a UE to transmit an A-SRS, identify a second TTI based at least in part on a first number of symbol periods between when the grant is received by the UE and when the UE is able to transmit uplink data, the first number of symbol periods meeting or being less than a difference between a number of symbol periods between an SRS resource of the second TTI and a control channel of the first TTI, and monitor the SRS resource of the second TTI for the A-SRS.

[0076] In some examples of the method, apparatus, and non-transitory computer-readable medium described above, transmitting configuration information to configure the UE to transmit the A-SRS within at least one symbol index of a plurality of different symbol indexes of a TTI, where monitoring the SRS resource of the second TTI for the A-SRS further includes monitoring for the A-SRS within at least one symbol period in the second TTI that corresponds to the at least one symbol index.

[0077] Some examples of the method, apparatus, and non-transitory computer-readable medium described above can further include processes, features, means, or instructions for receiving capability information indicating the first number of symbol periods.

[0078] In some examples of the method, apparatus, and non-transitory computer-readable medium described above, the grant indicates resources in the shared data channel allocated to the UE for reception of downlink data.

[0079] In some examples of the method, apparatus, and non-transitory computer-readable medium described above, identifying the second TTI further includes identifying the second TTI based at least in part on a number of second symbol periods between reception of the grant by the UE and when the UE can be able to receive the downlink data.

[0080] In some examples of the method, apparatus, and non-transitory computer-readable medium described above, identifying the second TTI further includes determining a maximum of the first number of symbol periods and the second number of symbol periods.

[0081] In some examples of the method, apparatus, and non-transitory computer-readable medium described above, transmitting the configuration information to configure the UE to transmit the A-SRS within at least one symbol index of a plurality of different symbol indexes of the TTI, where monitoring the SRS resource of the second TTI for the A-SRS further includes monitoring the SRS resource of the second TTI for the A-SRS within at least one symbol period corresponding to the at least one symbol index, where a number of symbol periods between the at least one symbol period of the second TTI and the control channel of the first TTI meets or exceeds the maximum value.

[0082] Some examples of the method, apparatus, and non-transitory computer-readable medium described above can further include processes, features, means, or instructions for receiving capability information indicating the first number of symbol periods and the second number of symbol periods.

[0083] In some examples of the method, apparatus, and non-transitory computer-readable medium described above, the first number of symbol periods and the second number of symbol periods correspond to defined capability information of the UE, respectively.

[0084] Some examples of the method, apparatus, and non-transitory computer-readable medium described above can further include processes, features, means, or instructions for receiving the A-SRS within the SRS resource of the second TTI. Some examples of the method, apparatus, and non-transitory computer-readable medium described above can further include processes, features, means, or instructions for generating a channel measurement based at least in part on the received A-SRS. Some examples of the method, apparatus, and non-transitory computer-readable medium described above can further include processes, features, means, or instructions for generating a frequency-dependent scheduling decision based at least in part on the channel measurement.

[0085] In some examples of the method, apparatus, and non-transitory computer-readable medium described above, identifying the second TTI includes determining that the second TTI and the first TTI can be a same TTI. BRIEF DESCRIPTION OF DRAWINGS

[0086] Figure 1 An example of a system for wireless communication is illustrated in accordance with aspects of the present disclosure.

[0087] Figure 2 An example of a system for wireless communication is illustrated in accordance with aspects of the present disclosure.

[0088] Figure 3 An example of a system for wireless communication is illustrated in accordance with aspects of the present disclosure.

[0089] Figure 4 An example of a system for wireless communication is illustrated in accordance with aspects of the present disclosure.

[0090] Figure 5 An example of a system for wireless communication is illustrated in accordance with aspects of the present disclosure.

[0091] Figure 6 An example of a system for wireless communication is illustrated in accordance with aspects of the present disclosure.

[0092] Figure 7 An example of a system for wireless communication is illustrated in accordance with aspects of the present disclosure.

[0093] Figures 8 to 10 A block diagram of a device is shown in accordance with aspects of the present disclosure.

[0094] Figure 11 A block diagram of a system including a UE is illustrated in accordance with aspects of the present disclosure.

[0095] Figures 12 to 14 A block diagram of a device is shown in accordance with aspects of the present disclosure.

[0096] Figure 15 A block diagram of a system including a base station is illustrated in accordance with aspects of the present disclosure.

[0097] Figures 16 to 21 A method for reference signal transmission and triggering is illustrated in accordance with aspects of the present disclosure. DETAILED DESCRIPTION

[0098] The described techniques relate to improved methods, systems, devices, or apparatuses that support configuration of aperiodic sounding reference signal transmissions and triggering. Generally, the described techniques provide for aperiodic triggering of a user equipment (UE) to transmit a sounding reference signal (SRS) in a transmission time interval (TTI) relative to a TTI in which the UE receives a grant of resources. In some examples, the UE can receive a grant triggering transmission of an aperiodic SRS, and the UE can identify offset information indicating a TTI offset between the TTI in which the triggering grant was received and the TTI in which the aperiodic SRS is to be transmitted. In some examples, the TTI in which the aperiodic SRS is to be transmitted can be a function of an amount of time the UE takes to process the grant (relative to a time the UE is able to transmit according to the grant).

[0099] In some examples, a UE can receive a downlink signal (such as a DCI transmission) and can transmit a sounding reference signal (SRS) in reply to the base station. The DCI can include an uplink grant or a downlink grant that can trigger the UE to transmit the SRS in a TTI determined relative to a TTI that includes the grant. The TTI can be a slot, a mini-slot, a frame, a subframe, or any set of contiguous OFDM symbols, or any other time interval. The UE can send the SRS transmission aperiodically, such as in response to receiving the downlink control information (DCI) from the base station. In some cases, the SRS can be transmitted within SRS resources in the earliest available transmission time interval (TTI) relative to when the grant is received, which can be as early as the same TTI that includes the grant.

[0100] The base station can measure the received SRS to generate a channel estimate of a wireless channel between the base station and the UE, and can use the channel estimate when making frequency-dependent scheduling decisions. For example, the base station can continue to schedule the UE in the frequency resources in which the UE transmits the SRS if the channel estimate is satisfactory, and can schedule the UE in different frequency resources if the channel estimate is not satisfactory.

[0101] In some examples, the base station can configure the UE with specific resources within a given TTI on which to transmit the aperiodic SRS. The UE can be configured with the SRS resources via higher layer signaling (e.g., RRC signaling) or can be preconfigured with the SRS resources, which can be one or more contiguous symbol periods (e.g., one or more last symbols of a slot) located at the end of the TTI. The base station can transmit configuration information including one or more symbol indices identifying specific symbol periods within the TTI that are the SRS resources in which the UE transmits the SRS. The UE can utilize the aperiodic SRS transmission configuration to determine in which slot to transmit the SRS on the designated SRS resources.

[0102] In some examples, a UE can transmit a SRS in an earliest available TTI relative to when a grant is received. The UE can determine the earliest available time slot based at least in part on the UE's capability information. That is, upon the UE receiving a DCI including a downlink grant, the UE can take a certain minimum amount of time (e.g., a first delay) to process the DCI triggering the UE to transmit a SRS transmission before transmitting the SRS transmission. In some examples, the UE can be capable of processing the DCI and transmitting the SRS within the same time slot in which the DCI is received. In some examples, the UE can take one or more time slots to process the DCI, and the UE can transmit the SRS in a SRS resource of a next available time slot after the processing of the DCI is complete (e.g., a next time slot index after the time slot index in which the DCI is received). The UE can signal its capability information to its base station, or the base station can be aware of default capability information about UEs operating within its wireless communications system. The base station can generate a DCI and corresponding resource grant according to the signaled or default capability information. The base station can determine, according to the signaled or default capability information, the earliest TTI in which the UE is capable of transmitting a SRS relative to the grant, and can monitor a SRS resource of the TTI for a SRS transmission from the UE.

[0103] In some examples, a UE can transmit a SRS in an earliest available TTI determined based on the UE's capability information after receiving an uplink grant of resources for the UE to transmit uplink data. That is, upon the UE receiving an uplink grant, the UE can take a certain minimum amount of time to process the uplink grant before being able to transmit uplink data according to the grant. In some examples, the base station can be aware of the UE's capability information and generate the uplink grant according to when the UE is capable of transmitting uplink data (relative to when the grant is received). The grant can allocate one or more TTIs to the UE, and the base station can monitor a SRS resource of an earliest TTI of the one or more allocated TTIs for a SRS transmission from the UE. In some examples, the earliest available TTI can be the same TTI in which the DCI is received, or can be a subsequent TTI. In some examples, the base station can not be aware of the UE's capability information. In such examples, the base station can utilize default capability information to determine a TTI in which the UE is expected to transmit a SRS (relative to when the grant is transmitted), and can monitor a SRS resource of the time slot for the SRS.

[0104] In some examples, the UE can identify an offset relative to the TTI in which the trigger grant is received for determining in which TTI to transmit the SRS. In some examples, the DCI can include a bit flag to indicate whether to use a dynamic TTI offset (e.g., in the DCI) or a semi-static offset (e.g., in RRC signaling), and the UE can process the bit flag to determine which offset to use. In some examples, the bit flag can indicate whether to use a dynamic TTI offset (e.g., in the DCI) or a second offset that is a function of the dynamic TTI offset. In some examples, the UE can determine that the TTI offset is a zero TTI offset, and thus the SRS transmission can be in the same TTI in which the DCI is received. In some examples, the UE can determine that the TTI offset is one or more TTIs, and the UE can transmit the SRS in a TTI that is offset from the TTI including the grant by one or more TTIs.

[0105] Aspects of the disclosure are initially described in the context of a wireless communications system. The described techniques provide for aperiodic triggering of a UE to transmit an SRS in a TTI relative to a TTI in which the UE receives a resource grant. Aspects of the disclosure are further illustrated by and described with reference to apparatus diagrams, system diagrams, and flowcharts that relate to configuration of aperiodic sounding reference signal transmissions and triggers.

[0106] Figure 1 An example of a wireless communications system 100 in accordance with various aspects of the present disclosure is illustrated. The wireless communications system 100 includes base stations 105, UEs 115, and a core network 130. In some examples, the wireless communications system 100 can be a Long Term Evolution (LTE) network, an LTE- Advanced (LTE-A) network, an LTE-A Pro network, or a New Radio (NR) network. In some cases, wireless communications system 100 can support enhanced broadband communications, ultra-reliable (e.g., mission critical) communications, low latency communications, or communications with low-cost and low-complexity devices.

[0107] Base stations 105 can wirelessly communicate with UEs 115 via one or more base station antennas. Base stations 105 described herein can include or can 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 can be referred to as a gNB), a Home NodeB, or a Home eNodeB. Wireless communications system 100 can include base stations 105 of different types (e.g., macro or small cell base stations). The UEs 115 described herein can 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.

[0108] Each base station 105 can be associated with a particular geographic coverage area 110 in which communication with various UEs 115 is supported. Each base station 105 can 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 can utilize one or more carriers. Communication links 125 shown in wireless communication system 100 can 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 can also be called forward link transmissions while uplink transmissions can also be called reverse link transmissions.

[0109] The geographic coverage area 110 for a base station 105 can be divided into sectors making up only a portion of the geographic coverage area 110, and each sector can be associated with a cell. For example, each base station 105 can provide communication coverage for a macro cell, a small cell, a hot spot, or other types of cells, or various combinations of these, within a geographic coverage area 110. In some examples, a base station 105 can 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 can overlap, and overlapping geographic coverage areas 110 associated with different technologies can be supported by the same base station 105 or by different base stations 105. The wireless communication system 100 can include, for example, a heterogeneous LTE / LTE-A / LTE-A Pro or NR network in which different types of base stations 105 provide

[0110] The term “cell” refers to a logical communication entity used for communication with a base station 105 (e.g., on a carrier) and can be associated with an identifier for distinguishing between cells of the same or different carriers (e.g., physical cell identifier (PCID), virtual cell identifier (VCID)). In some examples, a carrier can support multiple cells, and different cells can be configured according to different protocol types (e.g., machine type communication (MTC), narrowband internet of things (NB-IoT), enhanced mobile broadband (eMBB), or other) that can provide access for different types of devices. In some cases, the term “cell” can refer to a portion of a geographic coverage area 110 (e.g., a sector) over which a logical entity operates.

[0111] The UEs 115 can be dispersed throughout the wireless communication system 100, and each UE 115 can be stationary or mobile. A UE 115 can 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” can also be referred to as a unit, a station, a terminal, or a client. A UE 115 can also 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 can 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, among other examples, which can be implemented in various articles such as electric meters, appliances, vehicles, instruments, or the like.

[0112] Some UEs 115, such as MTC or IoT devices, can be low cost or low complexity devices, and can provide for automated communication between machines (e.g., via machine-to-machine (M2M) communication). M2M communication or MTC can refer to data communication technologies that allow devices to communicate with one another or a base station 105 without the need for human intervention. In some examples, M2M communication or MTC can 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 that information or present that information to humans in interaction with the program or applications. Some UEs 115 can 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, health care monitoring, wildlife monitoring, weather and geological event monitoring, fleet management, remote security sensing, physical access control, and transaction-based business charging.

[0113] Some UEs 115 can be configured to employ operating modes that reduce power consumption, such as a half-duplex communication (e.g., a mode where transmission and reception are not simultaneous, such as time division duplex (TDD) for example). In some examples, a half-duplex communication can 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, long

[0114] In some cases, a UE 115 can 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 can be within the geographic coverage area 110 of a base station 105. Other UEs 115 in the group can 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 can 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.

[0115] Base stations 105 can communicate with the core network 130 and with one another. For example, base stations 105 can interface with the core network 130 through backhaul links 132 (e.g., via an SI or other interface). Base stations 105 can also communicate with one another, e.g., directly or

[0116] The core network 130 can provide user authentication, access authorization, tracking, Internet Protocol (IP) connectivity, and other access, routing, or mobility functions. The core network 130 can be an evolved packet core (EPC), which can 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 can 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 can be transferred through the S-GW, which can be connected to the P-GW. The P-GW can provide IP address allocation as well as other functions. The P-GW can be connected to the network operators IP services. The operators IP services can include the Internet, an intranet, an IP multimedia subsystem (IMS), or a packet-switched (PS) streaming service.

[0117] At least some of the network devices, such as a base station 105, can include subcomponents such as an access network entity, which can be an example of an access node controller (ANC). Each access network entity can communicate with UEs 115 through a number of other access network transmission entities, which can 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 can 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).

[0118] Wireless communications system 100 can operate using one or more frequency bands, often in the range of 300 MHz to 300 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 can be blocked or redirected by buildings and environmental features. However, the waves can penetrate structures sufficiently for a macro cell to provide service within an indoor location. Further, UHF waves are

[0119] Wireless communications system 100 can also operate in a super high frequency (SHF) region using frequency bands from 3 GHz to 30 GHz, also known as the centimeter band. In some examples, wireless communications system 100 can support millimeter wave (mmW) communications between UEs 115 and base stations 105, and EHF antennas of the respective devices can be even smaller and more closely spaced than UHF antennas. In some examples, this can

[0120] Wireless communications system 100 can also operate in an extremely high frequency (EHF) region using frequency bands from 30 GHz to 300 GHz, also known as the millimeter band. In some examples, wireless communications system 100 can support mmW communications between UEs 115 and base stations 105, and EHF antennas of the respective devices can be even smaller and more closely spaced than UHF antennas. In some cases, this can facilitate using antenna arrays that provide beamforming or the like. However, the propagation of EHF transmissions can be subject to even more significant atmospheric attenuation and shorter range than SHF or UHF transmissions. The techniques disclosed herein can be employed across transmissions that use one or more different frequency regions, and designated use of bands across these frequency regions can differ by country or regulating body.

[0121] In some cases, the wireless communications system 100 can utilize both licensed and unlicensed radio frequency spectrum bands. For example, the wireless communications system 100 can employ License Assisted Access (LAA), LTE-Unlicensed (LTE-U) radio access technology, or NR technology in an unlicensed frequency band such as the 5 GHz ISM band. When operating in unlicensed frequency

[0122] In some examples, base station 105 or UE 115 can be equipped with multiple antennas, which can be used to employ techniques such as transmit diversity, receive diversity, multiple-input multiple-output (MIMO) communications, or beamforming. For example, wireless communications system 100 can 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 devices are equipped with one or more antennas. MIMO communications can employ multipath signal propagation to increase the spectral efficiency of a frequency channel. The multiple antennas can transmit or receive multiple

[0123] Beamforming (which can also be referred to as spatial filtering, directional transmission, or directional reception) is a signal processing technique that can be used at a transmitting device or receiving device (e.g., a base station 105 or a UE 115) to shape or steer a beam of energy in a specific direction. Beamforming can be achieved by combining the signals communicated by antennas of an antenna array in such a way that signals at particular orientations experience constructive interference while others experience destructive interference. The combination of signals can be performed in analog or digital domain. The techniques presented can be used for mmW or sub-mmW communications. Beamforming can be achieved in the analog or digital domain. In the analog domain, a separate amplitude and phase adjustment can be applied to each antenna element of an antenna array. In the digital domain, the beamforming can be achieved by adjusting signals in the digital processing (e.g., before conversion to analog for transmission). The beamforming can be dynamic, where the beamforming weights are changed on a periodic basis, or on-demand, where the beamforming weights are changed in response to a request or trigger.

[0124] In one example, a base station 105 can 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) can be transmitted by a base station 105 multiple times in different directions, which can include a signal being transmitted according to different beamforming weight sets associated with different directions of transmission. Transmissions in different beam directions can 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 and / or reception by the base station 105. Some signals, such as data signals associated with a particular receiving device, can be transmitted by the 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 in a single beam direction can be determined based at least in part on a signal that was transmitted in different beam directions. For example, a UE 115 can receive one or more of the signals transmitted by the base station 105 in different directions, and the UE 115 can report to the base station 105 an indication of the signal it received with a highest signal quality, or other acceptable signal quality. Although these techniques are described with reference to signals transmitted in one or more directions by the base station 105, a UE 115 can employ similar techniques for transmitting signals in different directions (e.g., for identifying a beam direction for subsequent transmission or reception by the UE 115), or for transmitting a signal in a single direction (e.g., for communicating data to a receiving device).

[0125] A receiving device (e.g., a UE 115, which can be an example of a mmW receiving device) can try multiple receive beams while 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 can try multiple receive directions by differentially rotating a polarization plane of an antenna, using a different antenna subarray, using a different set of antenna elements to receive signals, or any combination of these or the like. In some examples, the receiving device can try multiple receive directions by rotating an antenna array or a subset of the antenna elements of the antenna array by different amounts. In some examples, the receiving device can use a single receive beam to receive signals along a single beam direction (e.g., when receiving data signals). The single receive beam can be aligned in a beam direction determined based at least in part on listening to signals from different beam directions (e.g., determined based at least in part on listening to a set of synchronization signals, reference signals, or other control signals from different beam directions).

[0126] In some cases, antennas of a base station 105 or a UE 115 can be located within one or more antenna arrays that can support MIMO operations or transmit or receive beamforming. For example, one or more base station antennas or antenna arrays can 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 can be located in different geographic locations. A base station 105 can have an antenna array with a number of rows and columns of antenna ports that the base station 105 can use for beamforming in support of communications with a UE 115. Likewise, a UE 115 can have one or more antenna arrays that can support various MIMO or beamforming operations.

[0127] In some cases, the wireless communications system 100 can be a packet-based network that operates according to a layered protocol stack. In the user plane, communications at the bearer or Packet Data Convergence Protocol (PDCP) layer can be IP -based. A Radio Link Control (RLC) layer can in some cases perform packet segmentation and reassembly to communicate over logical channels. A Medium Access Control (MAC) layer can perform priority handling and multiplexing of logical channels into transport channels. The MAC layer can also use hybrid automatic repeat request (HARQ) to provide retransmission at the MAC layer to improve link efficiency. In the control plane, the Radio Resource Control (RRC) protocol layer can provide establishment, configuration, and maintenance of an RRC connection between a UE 115 and a base station 105 or core network 130 supporting radio bearers for user plane data. At the physical (PHY) layer, transport channels can be mapped to physical channels.

[0128] In some cases, UEs 115 and base stations 105 can support retransmissions of data to increase the likelihood that data is received successfully. HARQ feedback is a technique

[0129] Time intervals in LTE or NR can be expressed in multiples of a basic time unit, which may, for example, be the sampling period T s = 1 / 30,720,000 seconds of a Cosmic Microwave Background (CMB) radiation power spectrum. Time intervals of a communications resource can be organized as radio frames, each f = 307,200 T s . The radio frames can be identified by a system frame number (SFN) ranging from 0 to 1023. Each frame can include 10 subframes numbered from 0 to 9, and each subframe can have a duration of 1 ms. A subframe can be further divided into 2 slots each having a duration of 0.5 ms, and each slot containing 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 can contain 2048 sampling periods. In some cases, a subframe can be the smallest scheduling unit of the wireless communications system 100, and can be referred to as a transmission time interval (TTI). In other cases, a smallest scheduling unit of the wireless communications system 100 can be shorter than a subframe or can be dynamically selected (e.g., in bursts of shortened TTIs (sTTIs) or in selected component carriers using sTTIs).

[0130] In some wireless communications systems, a slot can be further divided into multiple mini-slots containing one or more symbols. In some examples, a symbol of a mini-slot or a mini-slot can be the smallest scheduling unit. For example, each symbol can vary in length depending on the subcarrier spacing or frequency band of operation. Further, some wireless communications systems can implement slot aggregation, where multiple slots or mini-slots are aggregated together and used for communications between a UE 115 and a base station 105.

[0131] 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 can include a portion of a radio frequency spectrum band that operates according to physical layer channels for a given radio access technology. Each physical layer channel can carry user data, control information, or other signaling. A carrier can be associated with a pre-defined frequency channel (e.g., an E-UTRA absolute radio frequency channel number (EARFCN)) and can be positioned relative to other carriers according to a channel raster for discovery by UEs 115. A carrier can be a downlink or uplink (e.g., in FDD mode) or be configured to carry downlink and uplink communications (e.g., in TDD mode). In some examples, signal waveforms transmitted over a carrier can be made up of multiple sub- carriers (e.g., using multi-carrier modulation (MCM) techniques such as OFDM or DFT-s-OFDM).

[0132] The organizational structure for carriers can be different for different radio access technologies (e.g., LTE, LTE-A, LTE-A Pro, NR, etc.). For example, communications over a carrier can be organized according to TTIs or slots, each of which can include user data as well as control information or signaling to support decoding the user data. A carrier can also include dedicated acquisition signaling (e.g., synchronization signals or system information, etc.) and control signaling that coordinates operations among carriers. In some examples (e.g., in carrier aggregation configurations), a carrier can also have acquisition signaling or control signaling that coordinates operations for other carriers.

[0133] Physical channels can be multiplexed on a carrier according to various techniques. A physical control channel and a physical data channel can be multiplexed on a downlink carrier, for example, using 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 can 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).

[0134] A carrier can be associated with a particular bandwidth of the radio frequency spectrum, and in some examples the carrier bandwidth can be referred to as a “system bandwidth” of the carrier or wireless communications system 100. For example, the carrier bandwidth can be one of a set of predetermined bandwidths for the carrier 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 can be configured for operating over portions or all of the carrier bandwidth. In other examples, some UEs 115 can be configured for operation using a narrowband protocol type associated with a predefined portion or range (e.g., set of subcarriers or RBs) within a carrier (e.g., “in-band” deployment of the narrowband protocol type).

[0135] In a system employing MCM techniques, a resource element can 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 can 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 can be for the UE 115. In MIMO systems, a wireless communications resource can refer to a combination of a radio frequency spectrum resource, a time resource, and a spatial resource (e.g., spatial layers), and the use of multiple spatial layers can further increase the data rate for communications with a UE 115.

[0136] Devices of the wireless communications system 100 (e.g., base stations 105 or UEs 115) can have a hardware configuration that supports communications over a particular carrier bandwidth, or can be configurable to support communications over one of a set of carrier bandwidths. In some examples, the wireless communications system 100 can include base stations 105 and / or UEs that can support simultaneous communications via carriers associated with more than one different carrier bandwidth.

[0137] Wireless communications system 100 can support communications with UEs 115 on multiple cells or carriers, a feature which can be referred to as carrier aggregation (CA) or multi-carrier operation. A UE 115 can be configured with multiple downlink CCs and one or more uplink CCs depending on the carrier aggregation configuration. Carrier aggregation can be used with both FDD and TDD component carriers.

[0138] In some cases, wireless communications system 100 can utilize enhanced component carriers (eCCs). An eCC can 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 can 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 can 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 bandwidths can include one or more segments that can be utilized by UEs 115 that are not capable of monitoring the whole carrier bandwidth or that are otherwise configured to use a limited carrier bandwidth (e.g., to conserve power).

[0139] In some cases, an eCC can utilize a different symbol duration than other CCs, which can include use of a reduced symbol duration as compared with symbol durations of the other CCs. A shorter symbol duration can be associated with increased spacing between adjacent subcarriers. A device, such as a UE 115 or base station 105, utilizing eCCs can 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 can include one or more symbol periods. In some cases, the TTI duration (i.e., the number of symbol periods in a TTI) can be variable.

[0140] Wireless communications systems such as NR systems can utilize any combination of licensed, shared, and unlicensed spectrum bands, among others. The flexibility of eCC symbol duration and subcarrier spacing can allow for the use of eCC across multiple spectrums. In some examples, NR shared spectrum can increase spectrum utilization and spectral efficiency, specifically through dynamic vertical (e.g., across frequency) and horizontal (e.g., across time) sharing of resources.

[0141] In some examples, a base station 105 can transmit downlink control information (DCI) including a downlink grant or an uplink grant for a UE 115, and in response, the UE 115 can transmit a SRS to the base station 105. The timing at which the UE 115 sends the SRS transmission can be relative to the TTI in which the UE 115 received the DCI, and can be a function of how long it takes for the UE 115 to process the DCI before the UE 115 is able to transmit in response to the DCI. In some examples, the UE 115 can transmit the SRS on SRS resources in the earliest TTI after the TTI in which the grant was received, which can be as early as the same TTI that includes the grant. In some examples, the transmission timing of the SRS can be identified based on TTI offset information. The UE can be preconfigured with the TTI offset information, or the TTI offset information can be received via RRC signaling, or included in the DCI. The UE can process the TTI offset information for determining a TTI offset, and can use the TTI offset to determine in which TTI relative to the TTI in which the grant was received the SRS is to be transmitted.

[0142] In some cases, a UE 115 can signal its capabilities to a base station 105, or the base station 105 can be aware of a default UE capability for UEs operating within the wireless communications system 100. The base station 105 can determine in which TTI to instruct the UE 115 to transmit uplink data or receive downlink data, and generate a grant accordingly. The base station 105 can also identify in which TTI the UE 115 is expected to transmit a SRS relative to the grant based on the signaled UE capabilities or the default capability. The base station 105 can monitor SRS resources of the expected TTI for the SRS. Beneficially, the UE 115 can be configured to transmit a SRS at an earlier or earliest available TTI after receiving a DCI.

[0143] Figure 2 An example of a wireless communications system 200 in accordance with various aspects of the present disclosure is illustrated. In some examples, the wireless communications system 200 can implement aspects of the wireless communications system 100. In some examples, the transmission timing of an aperiodic SRS can be triggered by receiving an uplink grant or a downlink grant.

[0144] In some cases, an aperiodic SRS can be transmitted on an SRS resource in the earliest available TTI after a grant is triggered. For example, base station 105-a can communicate with various devices within geographic coverage area 110-a. Base station 105-a can communicate with UE 115-a via bi-directional link 205. Base station 105-a can transmit downlink signal 210 via bi-directional link 205. In some examples, downlink signal 210 can include DCI. The DCI can include a downlink grant or an uplink grant, and additional information regarding timing of a subsequent transmission. For example, the DCI included in downlink signal 210 can include TTI offset information (e.g., slot offset information) indicating zero or more TTIs after the reception of downlink signal 210 in which UE 115-a is to transmit uplink signal 215 including an aperiodic SRS. Base station 105-a can use the received SRS to perform channel estimation, and can generate a frequency-dependent scheduling decision based on the channel estimation.

[0145] An aperiodic SRS transmission configuration can allow a UE to transmit an SRS with a minimum timing based on capability information of the UE (e.g., a processing capability of UE 115-a). For example, UE 115-a can receive a DCI signal, and can be able to process the received DCI and transmit a corresponding SRS within a certain minimum amount of time. Additionally, the aperiodic SRS transmission configuration can account for differences in triggering, signaling, and timing constraints based on capability information of UE 115-a when the DCI includes a downlink grant and when the DCI includes an uplink grant. In some cases, the minimum amount of processing time used by UE 115-a can differ based on whether UE 115-a receives a downlink grant or an uplink grant on downlink signal 210. In some examples, determining when to transmit an SRS can vary based on different minimum processing times.

[0146] In some examples, base station 105-a can configure UE 115-a with a particular resource within a given TTI on which to transmit an aperiodic SRS. For example, UE 115-a can be configured via higher layer signaling (e.g., RRC signaling) indicating that an SRS resource can be located at the end of a TTI (e.g., one or more last symbols of a slot).

[0147] In some examples, UE 115-a can transmit the SRS in the earliest available slot after receiving the downlink grant. The earliest available slot can be a function of the capability of UE 115-a. That is, upon receiving the downlink grant, UE 115-a can take a certain minimum amount of time (e.g., a first delay including a first number of symbol periods) to process the downlink grant before transmitting the SRS. In some examples, the UE can be capable of transmitting the SRS using the SRS resource in the same slot in which the DCI is received, or can take longer to process the DCI and transmit the SRS in the SRS resource of a subsequent slot (e.g., a next slot index after the slot index in which the DCI is received). In some examples, UE 115-a can transmit capability information indicating a number of symbol periods between reception of a grant and when UE 115-a is capable of transmitting uplink data according to the grant. Base station 105-a can receive the capability information and can instruct UE 115-a in the DCI to transmit the SRS in the SRS resource of the first slot in which UE 115-a is capable of transmitting the SRS.

[0148] In some examples, UE 115-a can transmit the SRS in the earliest available slot after receiving the uplink grant according to the capability information of UE 115-a. Upon receiving the uplink grant, UE 115-a can take a certain minimum amount of time (e.g., one or more symbol periods) to process the uplink grant before being capable of transmitting uplink data and / or the SRS. In some examples, UE 115-a can transmit capability information to base station 105-a, and base station 105-a can determine when UE 115-a is capable of transmitting uplink data and / or the SRS (relative to when the grant is received). Reception of the grant can trigger UE 115-a to transmit the SRS in the earliest available slot relative to when UE 115-a receives the grant. Base station 105-a can monitor the SRS resource of the earliest available slot and receive the SRS transmission in the SRS resource of the slot. The earliest available slot can be the same slot in which the DCI is received or a subsequent slot.

[0149] In some examples, the base station 105-a can be unaware of the capability information of the UE 115-a. In such examples, the base station 105-a can assume specified capability information (e.g., a default capability) regarding how long the UE 115-a takes to transmit a SRS relative to when a grant is received. For example, the base station 105-a can determine a maximum of the delay regarding how long the UE 115-a takes to process a downlink grant and when the UE 115-a is able to receive downlink data, and the delay regarding how long the UE 115-a takes to process an uplink grant and when the UE 115-a is able to transmit uplink data. The base station 105-a can determine a number of zero or more slots between when the UE 115-a receives a grant and when the UE is able to transmit uplink data according to the grant based on the specified capability information. The base station 105-a can then generate a grant based on the determined number of slots to instruct the UE 115-a to transmit uplink data according to the grant. The UE 115-a can transmit a SRS in a SRS resource of a first slot of the slots in which the UE 115-a is granted resources to transmit uplink data and / or receive downlink data.

[0150] In some examples, the UE 115-a can identify a slot offset relative to when a trigger grant is received. In some examples, a DCI including an uplink grant can indicate a slot offset between a slot in which the DCI is received and a slot in which a SRS is to be transmitted. In some examples, the slot offset can be indicated during higher layer signaling (e.g., RRC signaling), or the UE 115-a can be preconfigured with the slot offset. The UE 115-a can utilize the slot offset to determine in which slot to transmit the SRS. For example, the UE 115-a can determine to transmit a SRS in a configured SRS resource in a slot that is in the same slot that the grant allocates resources to the UE 115-a for transmission of uplink data, a slot that occurs one or more slots after the slot that the grant allocates resources to the UE 115-a for transmission of uplink data, or a slot that occurs one or more slots before the slot that the grant allocates resources to the UE 115-a for transmission of uplink data.

[0151] In some examples, a DCI including an uplink grant can include a sequence of bits. The sequence of bits can indicate timing and offset information for an uplink transmission to indicate a slot offset. The sequence of bits can include a bit flag, or the bit flag can be a bit in addition to the sequence of bits. A bit flag having a first value (e.g., a bit with a value of zero) can indicate that a dynamic slot offset indicated in the DCI is to be used, while a second value (e.g., a bit with a value of one) indicates that a semi-static slot offset configured via RRC signaling is to be used. In another example, a bit flag can have a first value (e.g., a bit with a value of zero) to indicate that a dynamic slot offset is to be used, and a second value (e.g., a bit with a value of one) that indicates that a different slot offset (e.g., a slot immediately before or after a slot corresponding to the dynamic slot offset) is to be used as a function of the dynamic slot offset. In some examples, instead of adding a bit flag to the DCI, one of the bits in the sequence of bits can be repurposed and used as the bit flag, and fewer bits can be used to indicate the timing of the uplink transmission.

[0152] In some examples, some types of DCI can not conventionally include a sequence of bits. For example, generally, downlink DCI does not include such a sequence of bits for indicating timing of an uplink transmission. In such examples, similar to the discussion of uplink DCI, the DCI can include an additional field with a sequence of bits indicating timing of an uplink transmission, as described above. The sequence of bits can also include a bit flag, as described herein.

[0153] Some examples of the wireless communications system 100 can support SRS transmission timing related to HARQ transmission timing and data transmission timing. These transmission timings can be a function of a capability of the UE 115. Figure 3 An example of transmission timing 300 is illustrated in accordance with various aspects of the present disclosure. Techniques used in the transmission timing 300 can be implemented by a UE 115 and a base station 105, which can be examples of the corresponding devices as described with reference to the wireless communications systems 100 and 200.

[0154] A wireless communication system can support wireless communication such as New Radio (NR) (e.g., 5G). In such a system, a slot can include a control channel 305 (such as control channels 305-a and 305-b depicted in slot n and slot n+1) and a shared data channel corresponding to the remaining one or more symbol periods of a particular slot. The depicted slots are examples of TTIs. The control channel 305 can include DCI including resource grants to UEs 115, and the control channel 305 can be located in the beginning portion of a slot. In an example, a slot can have 14 symbol periods, with the slot index ranging from 0 to 13, and the control channel 305 can be the first one or more symbol periods of the slot (e.g., symbols corresponding to slot index (SI) 0 and SI 1).

[0155] A UE 115 can support SRS transmissions on SRS resources 315 of a slot. The SRS resources 315 can be located in the last portion of a slot (e.g., SI 13 of slot n), and the SRS resources 315 can span a set of one or more contiguous symbols (e.g., 1, 2, or 4 contiguous symbols). In some examples, for each SRS resource, the SRS resources 315 can correspond to up to 4 ports. In some cases, all ports of an SRS resource can be sounded in each symbol.

[0156] The transmission of SRS can be aperiodic and can be triggered by receiving DCI in a control channel 305, which can carry DCI including a downlink grant. In some examples, the SRS transmission can be semi-persistent or periodic and can be a wideband transmission or a subband transmission. In some cases, the SRS bandwidth can be a multiple of 4 physical resource blocks (PRBs).

[0157] In some examples, a wireless communication system (e.g., NR) can support various configurations at a UE 115. In some cases, the wireless communication system can support switching between fractional bands for SRS transmissions on a component carrier (CC). The switching can be supported when a UE 115 is not capable of transmitting on the fractional bands in a CC simultaneously. In some examples, a fractional band can be defined as a bandwidth part. A UE 115 can be configured with multiple resources, which can be clustered based on use cases. For example, the resource clustering can be different for channel state information (CSI) acquisition, uplink non-codebook precoding, or uplink analog beamforming. In some examples, the wireless communication system can support SRS transmissions, where a set of parameters can be configured for a particular UE or group of UEs. In some cases, the wireless communication system can support SRS antenna switching within a carrier.

[0158] SRS transmissions and other uplink transmissions can be determined based on capability information of the UE 115. That is, the capability information of the UE 115 can include a minimum processing time in the form of symbols and absolute time in microseconds (ps). For example, the UE 115 can utilize a specified number of OFDM symbols (e.g., a minimum number of symbols) to process a physical downlink grant. This minimum number of OFDM symbols can be referred to as a first delay, or as NO. NO can span from the end of a control channel including a downlink grant for the UE 115 to the beginning of resources of a shared data channel (such as a physical downlink shared channel (PDSCH)) allocated to the UE 115 in the downlink grant. In some cases, the UE 115 can utilize a specified number of OFDM symbols (e.g., a minimum number) to process the PDSCH. This specified number of OFDM symbols can be referred to as a second delay, or as N1. From the perspective of the UE 115, N1 can span from the end of a control channel 305 received on the PDSCH that can include a downlink signal to the earliest possible beginning of a corresponding uplink ACK / NACK.

[0159] The UE 115 can utilize a specified number of OFDM symbols (e.g., a minimum number) to process a physical downlink control channel. This specified number of OFDM symbols can be referred to as a third delay, or as N2. N2 can span from the end of a PDCCH containing an uplink grant to the earliest possible transmission of uplink data 325 by the UE 115 on a shared data channel (such as a physical uplink shared channel (PUSCH)). In some examples, N1 and N2 can or can not include a timing advance (TA). In some examples, if a timing offset between reception of a DCI transmission and transmission of a scheduled uplink transmission at the UE 115 does not satisfy the capability information of the UE 115 (e.g., does not satisfy one or both of NO and N2), the base station 105 can not expect to receive the uplink transmission.

[0160] In some examples, SRS transmissions and other uplink transmissions can be determined based on one or more timing relationships. The timing relationships can be defined by slot offsets. For example, a delay in slots can occur between receiving a DL grant in control channel 305-a and receiving corresponding downlink data 310 (e.g., PDSCH data) on a shared data channel. This delay can be referred to as a slot offset K0. In some examples, a delay in slots can occur between receiving downlink data (e.g., PDSCH data) by a UE 115 and the UE 115 transmitting a corresponding uplink ACK / NACK. This delay can be referred to as a slot offset K1. A delay can occur between receiving an uplink grant in a control channel 305 by a UE 115 and the UE 115 transmitting uplink data 325 (e.g., PUSCH data) on a shared data channel in accordance with the grant. This delay can be referred to as a slot offset K2. In some examples, a delay in slots can occur between a base station 105 receiving an ACK / NACK signal corresponding to downlink data previously transmitted to a UE 115 and retransmitting downlink data corresponding to the ACK / NACK signal. This delay can be referred to as a slot offset K3. The slot offsets described above can be utilized, for example, in the case where a UE is configured with a single numerology with slot-level scheduling and a single transmit power transmission.

[0161] In some examples, an indication of one or more slot offsets can be included in a DCI transmission. For example, as described in more detail above, a UE 115 can receive a bit sequence including an indication of a slot offset K2. Additionally or alternatively, the UE 115 can be preconfigured or configured via higher layer signaling (RRC signaling) to know a default value of the slot offset K2. In some examples, the UE 115 can determine which SRS resource to utilize to transmit an SRS (relative to when the grant is received) based at least in part on the slot offset (e.g., K2). Figure 5 As described in more detail above, a UE 115 can receive a bit sequence including an indication of a slot offset K2. Additionally or alternatively, the UE 115 can be preconfigured or configured via higher layer signaling (RRC signaling) to know a default value of the slot offset K2. In some examples, the UE 115 can determine which SRS resource to utilize to transmit an SRS (relative to when the grant is received) based at least in part on the slot offset (e.g., K2).

[0162] In some cases, the wireless communication system can support a minimum value of K0, allowing downlink assignment and scheduled uplink or downlink data transmission to occur within the same time slot. For example, UE 115 may receive downlink grants in control channel 305-a in time slot n. If UE 115 has the capability to do so, it may receive downlink data 310 in one or more symbol periods after the end of control channel 305. In this case, K0 = 0, and UE 115 may receive downlink data 310 in the same time slot n as control channel 305-a, which includes downlink grants. In some examples, if UE 115 has this capability, it may receive downlink data 310 and transmit uplink ACK / NACK within the same time slot n. In such examples, K1 = 0. Similarly, if UE 115 has sufficient processing power, UE 115 can receive uplink permission in control channel 305-b in time slot n+1, and can transmit uplink data 325 in the same time slot n+1. In this case, K2 = 0.

[0163] The aperiodic SRS transmission configuration can specify the minimum timing between receiving the DCI and transmitting the aperiodic SRS. In some cases, base station 105 may or may not be aware of UE 115's capabilities, and the aperiodic SRS transmission configuration can be determined accordingly. For example, UE 115 may have already established an RRC connection with base station 105 and initiated wireless communication, but UE 115 may not have yet advertised its capabilities to base station 105. Furthermore, when the DCI includes uplink permission and carries downlink permission, the aperiodic SRS transmission configuration can be used to determine the minimum timing between the DCI and the SRS transmission.

[0164] In some examples, SRS transmissions can be sent at the earliest available time slot relative to the granted time slot, based on the capability information of the UE 115 indicated to the base station 105. Figure 4 Examples of timeline 400 according to various aspects of this disclosure are explained. In some examples, timeline 400 may implement various aspects of wireless communication system 100. The techniques used in transmitting timeline 400 may be implemented by UE 115 and base station 105, which may be examples of corresponding devices as described with reference to wireless communication systems 100 and 200.

[0165] The symbols of a time slot (such as symbol 405) can be indexed and scheduled across one or more time slots (e.g., time slot n, time slot n+1, time slot n+2, etc.). Figure 4In some examples, 'u' can represent an uplink symbol, 'd' can represent a downlink symbol, and 'g' can represent a guard period. In some examples, the base station 105 can configure the UE 115 with an SRS resource, which can be located at the end of a slot. The SRS resource can be an adjacent symbol period and can be located in the last symbol or symbols of slot n. In some examples, the SRS resource 415 can span 1 symbol, 2 symbols, or 4 symbols. The UE 115 can receive the DCI and can expect to transmit an SRS in the SRS resource of the earliest available slot according to the capability information of the UE 115. In some cases, the base station 105 can transmit configuration information that configures the UE 115 to transmit an aperiodic SRS within at least one symbol index of a plurality of symbol indices of a slot. The at least one symbol index can correspond to a symbol period that defines the SRS resource 415 within the slot.

[0166] In some examples, the DCI 410 can include a resource grant for the UE 115. The base station 105 can allocate resources to the UE 115 in the grant based on a signaled or designated (e.g., default) capability of the UE 115. The UE 115 can be expected to transmit an SRS in an SRS resource with respect to a first available slot of a slot that includes the grant, given that sufficient time has passed according to the signaled or default capability of the UE 115.

[0167] In an example, the signaled or default capability of the UE 115 can indicate that the UE 115 is capable of processing the DCI 410 in less than 14 symbol periods. The UE 115 can detect the grant in the DCI 410 that triggers the UE 115 to transmit an aperiodic SRS within slot n. The UE 115 can identify in which slot to transmit the SRS based on a first number of symbol periods between receiving the grant by the UE 115 and the UE 115 being capable of transmitting uplink data. The first number of symbol periods corresponds to a N0 latency 420 that represents a minimum amount of symbol periods needed for the UE 115 to process a downlink grant and receive downlink data according to the signaled or default capability of the UE 115. In another example, the first number of symbol periods corresponds to a N2 latency 430 that represents a minimum amount of symbol periods needed for the UE 115 to process an uplink grant and transmit according to the uplink grant according to the signaled or default capability of the UE 115.

[0168] In a first example, a UE 115 can signal its capability information to a base station 105, and the base station 105 can use the capability information when generating a DCI 410-a including a downlink grant for the UE 115. In an example, the base station 105 can process the capability information received from the UE 115 for determining a N0 delay 420. For example, in slot n, the N0 delay 420-a can be less than a difference 425-a. The difference 425-a can represent a number of symbol periods between a first symbol period of the SRS resource 415-a and a last symbol period of a control channel of slot n including the DCI 410-a. The base station 105 can identify, based on the capability information, that the UE 115 is capable of processing the grant and transmitting uplink data in the same slot (e.g., within slot n). The base station can generate, in the DCI 410-a, a downlink grant that grants the UE 115 resources for reception of downlink data in slot n. The UE 115 can process the DCI 410 and identify that it is to transmit a SRS in the SRS resource 415-a within the same slot including the downlink grant in the DCI 410-a. Thus, because the N0 delay 420-a is less than the difference 425-a, slot n is the earliest available slot, and the UE 115 can transmit the SRS in the SRS resource 415-a instead of in a subsequent slot, such as slot n+1. The base station 105 can monitor the SRS resource 415-a for the SRS transmitted by the UE 115.

[0169] In another example, the capability information can indicate that the N0 delay 420-b is greater than the difference 425-a, but less than the difference 425-b, and thus the UE 115 can identify that it is to transmit a SRS in the SRS resource 415-b within the next slot (e.g., slot n+1) after the slot including the downlink grant in the DCI 410-a. The base station 105 can monitor the SRS resource 415-b for the SRS transmitted by the UE 115. The techniques described herein can be applied to determine to transmit a SRS in a subsequent slot for a longer N0 delay.

[0170] Slot n+2 corresponds to DCI 410-b including an uplink grant for UE 115. The base station 105 can use the capability information received from UE 115 in generating DCI 410-b including an uplink grant for UE 115. In an example, the base station 105 can process the capability information received from UE 115 for determining N2 delay 430-a. The base station 105 can identify, based on the capability information, that UE 115 is capable of processing the grant and transmitting uplink data in the same slot. For example, at slot n+2, N2 delay 430-a can be less than difference 425-c (e.g., between the last symbol period of the control channel including DCI 410-b and the first symbol period of SRS resource 415-c), and thus UE 115 can identify that it will transmit SRS in SRS resource 415-c within the same slot including the uplink grant in DCI 410-b. Thus, slot n+2 is the earliest available slot, and UE 115 transmits SRS in SRS resource 415-c rather than in a subsequent slot, such as slot n+3. The base station 105 can monitor SRS resource 415-c for SRS transmitted by UE 115.

[0171] In another example, N2 delay 430-b can be greater than difference 425-c, but less than difference 425-d, and thus UE 115 can identify that it will transmit SRS in SRS resource 415-d within the next slot (e.g., slot n+3) after slot n+2 including the uplink grant in DCI 410-b. The base station 105 can monitor SRS resource 415-d for SRS transmitted by UE 115. The techniques described herein can be applied to determine to transmit SRS in a subsequent slot for a longer N2 delay.

[0172] In some examples, UE 115 can not have signaled its capability information to base station 105, and the base station 105 can use specified (e.g., default) capability information in generating DCI 410 including a downlink grant for UE 115. For example, in Figure 4In this case, the N0 delay 420-c can represent a default N0 delay, and the N2 delay 430-c can represent a default N2 delay. Assuming that sufficient time has passed according to the maximum of the default capabilities (e.g., the maximum of the N0 delay and the N2 delay), the UE 115 is expected to transmit the SRS in the SRS resource of the first available slot corresponding to the grant. In the depicted example, the larger delay is the N2 delay 430-c. For example, in slot n, the N2 delay 430-c can be greater than the difference 425-a and less than the difference 425-b. The base station 105 can identify, based on the default capability information, that the UE 115 is capable of processing the grant and transmitting uplink data in the next slot (e.g., slot n+1) after the slot including the DCI 410-a with the downlink grant. The UE 115 can identify that it will transmit the SRS in the SRS resource 415-b within the next slot (e.g., slot n+1) after the slot including the downlink grant in the DCI 410-a. The base station 105 can monitor the SRS resource 415-b for the SRS transmitted by the UE 115. The techniques described herein can be applied to determine to transmit the SRS in a subsequent slot in the event of a maximum of the default capabilities being longer.

[0173] In some examples, triggering the UE 115 to transmit in which TTI can be associated with a channel state information (CSI) reference signal (RS) and a CSI RS gap. In some cases, a specified (e.g., minimum) time interval (e.g., N (in symbols)) can occur between the DCI trigger and the A-SRS transmission, and can have the same range of candidate values as N2. In some examples, there can be a minimum time interval (e.g., 42 symbols) between the reception of an aperiodic channel state information reference signal (A-CSI RS) and when the UE 115 is expected to update its A-SRS precoding. This minimum time interval can be referred to as a CSI RS gap. The UE 115 is not expected to have updated its A-SRS precoding until the CSI RS gap has elapsed.

[0174] Transmission of the SRS can account for a minimum time interval (e.g., CSIRS gap) between transmission of the associated CSIRS and the transmission of the SRS relative to the grant. In some examples, the UE 115 and the base station 105 can identify whether the SRS is associated with the CSIRS. In determining the earliest available slot to transmit the SRS, the earliest available slot can be determined based on the CSIRS gap (e.g., minimum time interval) and the UE capability delay (e.g., N0 and / or N2 delay). For downlink transmissions, the UE 115 and the base station 105 can identify the maximum of the CSIRS gap and the UE capability delay (e.g., N0 delay). The maximum can be the longer of the two in terms of number of time or symbols. Similar to the above discussion of determining in which SRS resource 415 to transmit the SRS based on the N0 delay, the maximum of the CSIRS gap and the UE capability delay can be used by the UE 115 and the base station 105 to determine the earliest available slot (e.g., earliest available TTI) in which to communicate the SRS relative to the slot including the downlink grant. For uplink transmissions, the UE 115 and the base station 105 can identify the maximum of the CSIRS gap and the UE capability delay (e.g., N2 delay). Similar to the above discussion of determining in which SRS resource 415 to transmit the SRS based on the N2 delay, the maximum of the CSIRS gap and the UE capability delay can be used by the UE 115 and the base station 105 to determine the earliest available slot (e.g., earliest available TTI) in which to communicate the SRS relative to the slot including the uplink grant. In an example, the maximum between 42 symbols and the earliest available slot (e.g., earliest possible TTI) can be determined such that the UE capability (e.g., N0 and / or N2) is satisfied.

[0175] In some instances, an aperiodic SRS resource associated with a CSIRS can be a SRS resource corresponding to an uplink non-codebook precoding usage case, and can correspond to a usage case or usage case indication following (e.g., equal to) the uplink non-codebook precoding. The DCI, for example, can include a usage case indication having a first value indicating that the SRS resource is associated with the CSIRS and a second value indicating that the SRS resource is not associated with the CSIRS. The usage case indication can trigger the UE 115 to use the CSIRS delay and the maximum of the N0 delay and / or N2 delay, the N0 delay, or the N2 delay in determining in which TTI (e.g., slot) relative to the TTI including the grant to transmit the SRS.

[0176] The transmission timing of the SRS relative to the grant received in the DCI can be determined based on slot offset information. The slot offset information can be received in the DCI via RRC signaling or can be preconfigured at the UE 115 and the base station 105. Figure 5An example of a timeline 500 in accordance with various aspects of the present disclosure is illustrated. In some examples, the timeline 500 can implement aspects of the wireless communications system 100. Techniques used in the timeline 500 can be implemented by UEs 115 and base stations 105, which can be examples of the corresponding devices as described with reference to the wireless communications systems 100 and 200.

[0177] The transmission timing of the SRS relative to the grant can be based on slot offset information. In some examples, a base station 105 can transmit configuration information that configures a UE 115 with SRS resources 515 of a TTI. The TTI (e.g., a slot) can be composed of a set of symbol periods, and a set of symbol indices can correspond to respective symbol periods in the set of symbol periods. The configuration information can identify a set, for example, composed of one or more symbol indices to identify the SRS resources 515 within a slot. In some examples, the configuration information can identify a set of one or more symbol indices to identify the SRS resources 515 within a slot. Figure 5 In some examples, a slot n can include 14 symbols, and the configuration information can indicate that a symbol index corresponding to the last symbol period of the slot is to be used as the SRS resource 515. The configuration information can identify more than one symbol index, and thus the SRS resource 515 can be more than one symbol period of a slot.

[0178] The timing of the SRS transmission relative to the grant can depend, at least in part, on whether the base station 105 is aware of the capability information of the UE 115. For example, if the base station 105 is aware of the capability information of the UE 115 (e.g., an amount of time or number of symbols used by the UE 115 to process the DCI 510), the base station 105 can convey slot offset information via RRC signaling or in the DCI. The slot offset information can indicate information used to identify a slot offset (e.g., the slot offset 525). The slot offset information can permit the UE 115 to determine in which slot relative to the slot that includes the DCI 510 with resource grant for the UE 115 to transmit the SRS.

[0179] In some examples, a base station 105 can configure a UE 115 with slot offset information via RRC signaling. The slot offset information can indicate a slot offset, and the UE 115 can use the slot offset to determine in which slot relative to the slot including the grant for the UE 115 to transmit the SRS. The slot offset information can indicate a slot offset of zero or more slots. For example, the slot offset 520 can correspond to a zero slot offset 520, a one slot offset 525, and / or a multiple slot offset 530 (e.g., a two slot offset). A slot offset configured via RRC signaling can be referred to as a semi-static slot offset. For example, if the DCI 510-a includes a resource grant to the UE 115, the UE 115 can identify the semi-static slot offset. For a zero slot offset, the UE 115 can transmit the SRS in the SRS resource 515-a (e.g., in the same slot including the grant). For a one slot offset, the UE 115 can transmit the SRS in the SRS resource 515-b (e.g., in the next slot after the slot including the grant). For a two slot offset, the UE 115 can transmit the SRS in the SRS resource 515-c (e.g., in the two slots after the slot including the grant). The base station 105 that transmitted the DCI 510-a is aware of the semi-static slot offset and monitors for SRS transmissions in the SRS resource 515 corresponding to the semi-static slot offset. These techniques can be extended to semi-static slot offsets with any number of slot offsets.

[0180] In some examples, a base station 105 can configure a UE 115 with slot offset information in a DCI. Similar to the discussion provided above, the slot offset information in the DCI can indicate in which slot, relative to a slot that includes a grant for the UE 115, the UE 115 is to transmit a SRS. In an example, the DCI 510 can include a grant of uplink resources and offset information that indicates a slot index. The slot index can identify a slot in which the UE 115 is to transmit uplink data (e.g., the slot index can follow a K2 value reported in the DCI 510). The UE 115 can transmit a SRS in a SRS resource 515 of a slot that corresponds to the slot index indicated in the DCI 510. In an example, if the DCI 510-a includes a resource grant to the UE 115, the offset information can include a slot index for a zero slot offset (e.g., in the same slot that includes the grant), a one slot offset (e.g., in a slot n+1 that is one slot after the slot n that includes the grant), or a two slot offset (e.g., in a slot n+2 that is two slots after the slot n that includes the grant). The slot index can indicate an additional offset. Since the UE 115 is configured with the location of the SRS resource 515 in each slot, the UE 115 can transmit a SRS in a slot (e.g., in one of the SRS resources 515-a, 515-b, or 515-c) that corresponds to the slot index indicated in the DCI 510-a. Similarly, the base station 105 that transmitted the DCI 510-a is aware of the offset information included in the DCI 510-a and monitors for SRS transmissions in the SRS resources 515 that correspond to the offset information indicated in the DCI 510-a.

[0181] For the DCI 510-a that includes a resource grant to the UE 115 for transmission of uplink data, the offset information in the DCI 510-a can be a sequence of bits to indicate uplink timing. In some examples, the sequence of bits can include three bits to indicate a K2 offset relative to a slot that includes the grant (e.g., a K2 offset to indicate PUSCH timing). The UE 115 can transmit a SRS in a SRS resource 515 of a same slot indicated by the K2 offset. For example, the base station 105 can set the K2 offset in the DCI 510-a to K2 = 1 to instruct the UE 115 to transmit uplink data in a next slot (e.g., slot n+1). The UE 115 can process the DCI 510-a in the slot n to identify the K2 offset and transmit a SRS in the SRS resource 515-b of the slot n+1. In some examples, the UE 115 can transmit a SRS in a SRS resource 515 of a slot that occurs after the slot indicated by the K2 offset.

[0182] In some examples, one of the bits in the bit sequence of DCI 510-a can be a bit flag, or the bit flag can be an additional bit other than the bit sequence. In some examples, instead of adding an additional 1-bit flag to a 3-bit sequence, the 3-bit sequence can be reduced to a 2-bit sequence (e.g., using two bits to signal the K2 offset), and the third bit can be repurposed as the 1-bit flag described above.

[0183] In some cases, the base station 105 can switch the bit flag to indicate which of a plurality of slot offsets to use. In an example, the base station 105 can switch the bit flag in DCI 510-a to indicate whether the UE 115 is to use a dynamic slot offset or a semi-static offset. If the UE 115 is to use a dynamic slot offset, the bit flag can have a first value (e.g., a bit value of zero) that indicates that the UE 115 is to use the offset information included in DCI 510-a to identify a dynamic slot offset. If the UE 115 is to use a semi-static slot offset, the bit flag can have a second value (e.g., a bit value of one) that indicates that the UE 115 is to use a semi-static slot offset received via RRC signaling. In an example, the dynamic slot offset is that the UE 115 is to transmit a SRS in a SRS resource of the same slot that includes a resource grant for the UE 115, and the semi-static slot offset can be that the UE 115 is to transmit a SRS in a SRS resource of a slot that occurs two slots after the slot in which the resource grant for the UE 115 is received. In Figure 5 In an example, for example, a bit flag having a first value can instruct the UE 115 to transmit a SRS in SRS resource 515-a (e.g., in slot n that also includes the grant in DCI 510-a), and a bit flag having a second value can instruct the UE 115 to transmit a SRS in SRS resource 515-c (e.g., in slot n+2 that occurs two slots after slot n that includes the grant in DCI 510-a).

[0184] The base station 105 can switch a bit flag to indicate whether to use a dynamic slot offset or a second offset that is a function of the dynamic slot offset. For example, a bit flag with a first value (e.g., a bit value of zero) for a TTI offset can be an offset K2 indicated in the DCI 510-a, and a bit flag with a second value (e.g., a bit value of zero) for a TTI offset can be the offset K2 plus a constant offset c. In some cases, c can be a constant value from a set of integer values (e.g., -1 and 1). The value of c can be RRC configured, or can be configured by a medium access control (MAC) control element (CE) transmitted by the base station 105 to the UE 115. In some examples, the first value can indicate a gap between a grant requesting uplink data and a transmission of the uplink data in TTIs (e.g., indicating an offset K2), and the constant value c can be used to cause the UE 115 to transmit an SRS before or after a TTI in which the UE transmits uplink data (e.g., before or after a TTI corresponding to the offset K2). In some such examples, if the slot offset K2 is equal to the slot offset 525 (e.g., to indicate slot n + 1), the 1-bit flag can indicate whether the UE 115 should transmit an SRS at the slot offset 520 in slot n (e.g., K2 - 1) or at the slot offset 530 in slot n + 2 (e.g., K2 + 1). The base station 105 can use the bit flag in the DCI 510-a to control whether the UE 115 transmits an SRS before, in, or after a slot in which the UE 115 is granted resources to transmit uplink data (e.g., before or after a slot corresponding to an indicated slot in the offset K2).

[0185] Unlike uplink grants, downlink grants in DCI do not conventionally include bits to indicate PUSCH timing (e.g., an offset K2). To remedy this deficiency, according to examples described herein, slot offset information can be conveyed via RRC signaling. When the DCI 510-a includes a grant of downlink resources for the UE 115, the UE 115 can use the slot offset information configured via RRC signaling to determine a slot offset (e.g., identify a semi-static slot offset) and determine which slot relative to the slot that includes the grant to use to transmit an SRS. In an example, the semi-static slot offset can be a slot in which the UE 115 is to transmit an SRS in an SRS resource of the next slot after the slot in which the grant of resources for the UE 115 is received. In some examples, the UE 115 can be configured to transmit an SRS in the SRS resource of the slot that is a function of the slot offset (e.g., a function of the slot offset plus a constant offset c). In some examples, the UE 115 can be configured to transmit an SRS in the SRS resource of the slot that is a function of the slot offset (e.g., a function of the slot offset plus a constant offset c) and a function of the constant offset c (e.g., a function of the slot offset plus the constant offset c plus a constant offset d). In some examples, the UE 115 can be configured to transmit an SRS in the SRS resource of the slot that is a function of the slot offset (e.g., a function of the slot offset plus a constant offset c) and a function of the constant offset c (e.g., a function of the slot offset plus the constant offset c plus a constant offset d) and a function of the constant offset d (e.g., a function of the slot offset plus the constant offset c plus the constant offset d plus a constant offset e). Figure 5In some examples, the DCI 510 including a downlink grant is configured to include a bit sequence that indicates a K2 offset for PUSCH timing similar to the bit sequence described with respect to the DCI including an uplink grant. The bit sequence can include, for example, up to 3 bits. One of the 3 bits can be configured as a 1-bit flag as described herein for switching between a dynamic slot offset and a semi-static offset, or for switching between a dynamic slot offset and a dynamic slot offset plus or minus a constant value.

[0186] In some examples, the DCI 510 including a downlink grant is configured to include a bit sequence that indicates a K2 offset for PUSCH timing similar to the bit sequence described with respect to the DCI including an uplink grant. The bit sequence can include, for example, up to 3 bits. One of the 3 bits can be configured as a 1-bit flag as described herein for switching between a dynamic slot offset and a semi-static offset, or for switching between a dynamic slot offset and a dynamic slot offset plus or minus a constant value.

[0187] In some examples, the DCI 510 can be a bit sequence that is a joint field for indicating transmission of a reference signal and for triggering the UE 115 to transmit a SRS. For example, the DCI 510 can include a field for jointly indicating that the base station 105 is transmitting a zero-power channel state information reference signal (ZP-CSI RS) and triggering the UE 115 to transmit a SRS. The bit sequence can include a set of bits (e.g., 1 to 3 bits) to indicate that the base station 105 is transmitting a ZP-CSI RS, and to indicate offset information for identifying a slot offset. The UE 115 can process the bit sequence to determine that it is to monitor for a ZP-CSI RS transmitted by the base station 105, and is to transmit a SRS in a slot relative to the slot including the DCI 510. The UE 115 can determine in which slot to transmit the SRS according to the techniques described herein.

[0188] Figure 6 An example of a process flow 600 in accordance with various aspects of the present disclosure is illustrated. In some examples, process flow 600 can implement aspects of wireless communication system 100. The techniques used in process flow 600 can be implemented by UE 115-b and base station 105-b, which can be examples of the corresponding devices as described with reference to wireless communication systems 100 and 200.

[0189] At 605, the base station 105-b transmits a trigger grant to the UE 115-b. The trigger grant can be an uplink grant or a downlink grant. The trigger grant can be included in a DCI transmission. At 610, the UE 115-b detects the trigger grant in a first TTI. The grant can trigger the UE to transmit an aperiodic SRS.

[0190] At 615, UE 115-b identifies offset information that indicates a TTI offset relative to the grant received at 605. The offset information can be a TTI offset preconfigured at UE 115-b, can be indicated via RRC signaling, or can be included in the same DCI transmission in which the triggering grant is received 605. In some cases, the offset information can be based on the uplink grant and a time (e.g., K2) between the grant at 605 and the corresponding scheduled uplink transmission. In some cases, the offset information can be based on K2 and some additional value (e.g., -1 or 1) that indicates that the second TTI is earlier than, equal to, or later than K2. In some examples, the offset information is a bit sequence that can include a bit flag.

[0191] At 620, UE 115-b determines a second TTI for transmitting the aperiodic SRS based at least in part on the TTI offset identified at 615. UE 115-b can identify the SRS resource, for example, in the last 1, 2, or 4 symbols of a plurality of TTIs. UE 115-a can determine the second TTI as being offset from the first TTI that includes the grant by the TTI offset. In some examples, the TTI offset can be a zero TTI offset, and thus the second TTI and the first TTI can be the same TTI. If the second TTI has been identified based on the offset information, UE 115-b can identify the SRS resource corresponding to the second TTI.

[0192] At 625, base station 105-b can identify offset information that indicates a TTI offset relative to the grant transmitted at 605. Base station 105-b can identify the offset information based on the same considerations described with respect to UE 115-b at 615 and with respect to Figures 4-5 base station 105-b at 625. At 630, base station 105-b determines a second TTI for the aperiodic SRS based at least in part on the TTI offset. Base station 105-b can determine the second TTI based on the same considerations described with respect to UE 115-b at 620 and with respect to Figures 4-5 base station 105-b at 630.

[0193] At 635, base station 105-b monitors at least one symbol period of the second TTI corresponding to at least one symbol index of the SRS resource for the aperiodic SRS. At 640, UE 115-b transmits and base station 105-b receives the aperiodic SRS in the SRS resource of the second TTI.

[0194] At 645, the base station 105-b generates a channel measurement based at least in part on the aperiodic SRS received at 640. At 650, the base station 105-b generates a frequency-dependent scheduling decision based at least in part on the channel measurement. The base station 105-b can perform subsequent communications with the UE 115-b based on the generated scheduling decision.

[0195] Figure 7 An example of a process flow 700 in accordance with various aspects of the present disclosure is illustrated. In some examples, process flow 700 can implement aspects of wireless communications system 100. Techniques used in process flow 700 can be implemented by a UE 115-c and a base station 105-c, which can be examples of the corresponding devices as described with reference to wireless communications systems 100 and 200.

[0196] At 705, the UE 115-c can transmit capability information to the base station 105-c. The capability information can indicate, for example, one or both of an N0 delay and an N2 delay of the UE 115-c. Operation 705 is optional and can be skipped. If skipped, the base station 105-c can utilize designated capability information (e.g., default capability information indicating a default N0 delay and N2 delay) regarding UEs operating within a wireless communications system, such as system 100.

[0197] At 710, the base station 105-c transmits, in a TTI, a DCI granting resources to the UE 115-a, where the grant is in accordance with the signaled or designated capability information. The grant can trigger the UE 115-c to transmit an aperiodic SRS. The trigger grant can be an uplink grant or a downlink grant. At 715, the UE 115-c can detect the grant triggering transmission of the aperiodic SRS. The grant can be detected within the first TTI.

[0198] At 720, the UE 115-c can identify a second TTI based at least in part on a first number of symbol periods between reception of the grant by the UE and the UE being able to transmit uplink data (e.g., based on the N0 delay or the N2 delay). The first number of symbol periods can satisfy or be less than a difference between a number of symbol periods between the SRS resource of the second TTI and a control channel of the first TTI. The first number of symbol periods can be a number of symbol periods indicated in the capability information transmitted by the UE 115-c at 705. That is, if the first number of symbol periods is less than or equal to a difference between the control channel (e.g., of slot n in 720) and the SRS resource (e.g., SRS resource 415-a) of the first TTI, the UE 115-c can identify the second TTI based at least in part on the first number of symbol periods. Figure 4 Figure 4 ​If the first number of symbol periods is greater than the difference between the control channel and the SRS resource of the first TTI (e.g., difference 425-b), then the second TTI can be a subsequent TTI of the first TTI (e.g., the aperiodic SRS can be transmitted on the SRS resource 415-b of slot n+1, which is subsequent to the slot n in which the grant was received 710). At 725, the base station 105-c can identify the second TTI for the aperiodic SRS, similar to the process described at 720 with respect to UE 115-c.

[0199] At 730, the base station 105-c can monitor the SRS resource of the second TTI. The monitoring can occur within at least one symbol period of the second TTI that is configured with the SRS resource. At 735, the UE 115-c can transmit and the base station 105-c can receive the aperiodic SRS in the SRS resource of the second TTI.

[0200] At 740, the base station 105-c can generate channel measurements based at least in part on the received aperiodic SRS. At 745, the base station 105-c can generate a frequency- dependent scheduling decision based at least in part on the channel measurements. The base station 105-c can communicate subsequent communications with the UE 115-c based on the generated scheduling decision.

[0201] Beneficially, the techniques described herein can provide for triggering a UE to transmit an SRS in a TTI relative to a TTI that includes a grant.

[0202] Figure 8 A block diagram 800 of a wireless device 805 in accordance with aspects of the present disclosure is shown. The wireless device 805 can be an example of aspects of a user equipment (UE) 115 as described herein. The wireless device 805 can include a receiver 810, a UE communications manager 815, and a transmitter 820. The wireless device 805 can also include a processor. Each of these components can be in communication with one another (e.g., via one or more buses).

[0203] The receiver 810 can receive information such as packets, user data, or control information associated with various information channels (e.g., control channels, data channels, and information related to reference signal transmission and triggering, etc.). Information can be passed on to other components of the device. The receiver 810 can be a receiver as Figure 11 The described transceiver 1135 can be an example of a transmitter as described herein. The transmitter 820 can utilize a single antenna or a set of antennas.

[0204] The UE communications manager 815 can be an example of a transmitter as described herein. The receiver 810 can utilize a single antenna or a set of antennas. Figure 11Examples of aspects of the described UE communication manager 1115.

[0205] The UE communication manager 815 and / or at least some of its various subcomponents can be implemented in hardware, software executed by a processor, firmware, or any combination thereof. If implemented in software executed by a processor, the functions of the UE communication manager 815 and / or at least some of its various sub-components can be executed by a general-purpose processor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), an 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 communication manager 815 and / or at least some of its various sub-components can be physically located in various places in the apparatus including but not limited to with the processor, so that the functionality of the UE communication manager 815 and / or at least some of its various sub-components can be shared among various physical resources in a pool of resources, or distributed among multiple physical resources each dedicated to specific functionality. In some examples, the UE communication manager 815 and / or at least some of its various sub-components can be a separate and distinct component in accordance with various aspects of the present disclosure. In other examples, the UE communication manager 815 and / or at least some of its various sub-components can 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.

[0206] The UE communication manager 815 can detect, within a first transmission time interval (TTI), a grant triggering the UE to transmit an aperiodic sounding reference signal (A-SRS); identify offset information indicating a TTI offset relative to the TTI of the grant; determine a second TTI for transmitting the A-SRS based on the TTI offset; and transmit the A-SRS in SRS resources of the second TTI. The UE communication manager 815 can also detect, within a first transmission time interval (TTI), a grant triggering the UE to transmit an aperiodic sounding reference signal (A-SRS); identify a second TTI based on a number of first symbol periods between receiving the grant by the UE and the UE being able to transmit uplink data, the number of first symbol periods satisfying or being less than a difference between a number of symbol periods between SRS resources of the second TTI and a control channel of the first TTI; and transmit the A-SRS in the SRS resources of the second TTI.

[0207] The transmitter 820 can transmit signals generated by other components of the device. In some examples, the transmitter 820 can be collocated with a receiver 810 in a transceiver module. For example, the transmitter 820 can be an example of the transceiver 1135 described with reference to FIG. 11. The transmitter 820 can utilize a single antenna or a set of antennas. Figure 11 Examples of aspects of the described transceiver 1135. The transmitter 820 can utilize a single antenna or a set of antennas.

[0208] Figure 9 A block diagram 900 of a wireless device 905 is shown, in accordance with aspects of the present disclosure. The wireless device 905 can be an example of aspects of a wireless device 805 or a UE 115 as described with reference to FIG. 9. The wireless device 905 can include a receiver 910, a UE communications manager 915, and a transmitter 920. The wireless device 905 can also include a processor. Each of these components can be in communication with one another (e.g., via one or more buses). Figure 8

[0209] The receiver 910 can receive information such as packets, user data, or control information associated with various information channels (e.g., control channels, data channels, and information related to reference signal transmission and triggering, etc.). Information can be passed on to other components of the device. The receiver 910 can be an example of aspects of the transceiver 1135 described with reference to FIG. 11. The receiver 910 can utilize a single antenna or a set of antennas. Figure 11

[0210] The UE communications manager 915 can be an example of aspects of the UE communications manager 1115 described with reference to FIG. 11. Figure 11

[0211] The UE communications manager 915 can also include a detection component 925, an offset information component 930, an A-SRS component 935, and a TTI identifier component 940.

[0212] The detection component 925 can detect, within a first TTI, a grant triggering a user equipment (UE) to transmit an aperiodic sounding reference signal (A-SRS); and receive a downlink control information including offset information in the first TTI, where the grant indicates resources in a shared data channel allocated to the UE for transmission of uplink data, and where the offset information includes a bit sequence corresponding to a number of TTIs occurring between receiving the grant by the UE and instructing the UE to transmit uplink data in accordance with the grant. In some cases, the grant indicates resources in the shared data channel allocated to the UE for reception of downlink data.

[0213] ​​​The offset information component 930 can identify offset information indicating a TTI offset relative to a grant; receive downlink control information in a first TTI including the offset information, where the grant indicates resources in a shared data channel allocated to the UE for transmission of uplink data, and where the offset information is a bit flag indicating whether the UE is to use a first value for the TTI offset indicated in the downlink control information or a second semi-statically configured value for the TTI offset; receive downlink control information in a first TTI including the offset information, where the grant indicates resources in a shared data channel allocated to the UE for transmission of uplink data, and where the offset information includes a bit flag indicating whether the UE is to use a first value for the TTI offset indicated in the downlink control information or a second value for the TTI offset; and receive control signaling semi-statically indicating a defined value, where the second value for the TTI offset is a function of the first value for the TTI offset and the defined value. In some cases, identifying the offset information further includes retrieving the offset information from memory, where the UE is preconfigured with the offset information. In some cases, identifying the offset information further includes receiving the offset information in the downlink control information of the first TTI, where the offset information indicates a delay corresponding to a number of TTIs occurring between receiving the grant by the UE and instructing the UE to transmit uplink data according to the grant. In some cases, identifying the second TTI further includes identifying the second TTI as being offset from the first TTI by the TTI offset. In some cases, identifying the second TTI includes determining that the TTI offset is a zero TTI offset, where the second TTI and the first TTI are the same TTI. In some cases, identifying the offset information further includes receiving control signaling semi-statically configuring the UE with the offset information. In some cases, identifying the offset information further includes receiving downlink control information in the first TTI including offset information for dynamically configuring the UE with the TTI offset. In some cases, the first value is K2 and the second TTI is a TTI occurring before the TTI corresponding to the first value.

[0214] The A-SRS component 935 can determine a second TTI for transmitting an A-SRS based on the TTI offset; transmit the A-SRS in an SRS resource of the second TTI; and transmit the A-SRS in an SRS resource of the second TTI. In some cases, determining the second TTI further includes determining a TTI index after a delay indicated in the offset information, where the second TTI corresponds to the TTI index. In some cases, the SRS resource corresponds to a subset of symbol periods within the second TTI.

[0215] TTI identifier component 940 may identify a second TTI based on a first number of symbol cycles between when the UE receives permission and when the UE is able to transmit uplink data, the first number of symbol cycles being equal to or less than the difference in the number of symbol cycles between the SRS resources of the second TTI and the control channel of the first TTI. In some cases, identifying the second TTI further includes identifying the second TTI based on a second number of symbol cycles between when the UE receives permission and when the UE is able to receive downlink data. In some cases, identifying the second TTI further includes determining the maximum of the first number of symbol cycles and the second number of symbol cycles. In some cases, the first number of symbol cycles and the second number of symbol cycles are specified capabilities of the UE. In some cases, identifying the second TTI includes determining that the second TTI and the first TTI are the same TTI.

[0216] Transmitter 920 can transmit signals generated by other components of the device. In some examples, transmitter 920 may coexist with receiver 910 in a transceiver module. For example, transmitter 920 may be a reference... Figure 11 Examples of various aspects of the transceiver 1135 described. The transmitter 920 may utilize a single antenna or an array of antennas.

[0217] Figure 10 A block diagram 1000 of a UE communication manager 1015 according to various aspects of this disclosure is shown. The UE communication manager 1015 may be a reference... Figure 8 , 9 Examples of aspects of the UE communication manager 815, UE communication manager 915, or UE communication manager 1115 described in section 11. The UE communication manager 1015 may include a detection component 1020, an offset information component 1025, an A-SRS component 1030, a TTI identifier component 1035, a configuration information component 1040, a capability information component 1045, and a control information component 1050. Each of these modules may communicate directly or indirectly with each other (e.g., via one or more buses).

[0218] The detection component 1020 can detect permission to trigger the UE to transmit an aperiodic probe reference signal (A-SRS) within a first TTI; and receive downlink control information in the first TTI including offset information, wherein the permission indicates resources allocated to the UE in the shared data channel for uplink data transmission, and wherein the offset information includes a bit sequence corresponding to the number of TTIs occurring between the UE receiving the permission and instructing the UE to transmit uplink data according to the permission. In some cases, the permission indicates resources allocated to the UE in the shared data channel for downlink data reception.

[0219] Offset information component 1025 can identify offset information indicating a TTI offset relative to a grant; receive downlink control information in a first TTI including the offset information, where the grant indicates resources in a shared data channel allocated to the UE for transmission of uplink data, and where the offset information is a bit flag indicating whether the UE is to use a first value for the TTI offset indicated in the downlink control information or a second semi-statically configured value for the TTI offset; receive downlink control information in a first TTI including the offset information, where the grant indicates resources in a shared data channel allocated to the UE for transmission of uplink data, and where the offset information includes a bit flag indicating whether the UE is to use a first value for the TTI offset indicated in the downlink control information or a second value for the TTI offset; and receive control signaling semi-statically indicating a defined value, where the second value for the TTI offset is a function of the first value for the TTI offset and the defined value. In some cases, identifying the offset information further includes retrieving the offset information from memory, where the UE is preconfigured with the offset information. In some cases, identifying the offset information further includes receiving the offset information in the downlink control information of the first TTI, where the offset information indicates a delay corresponding to a number of TTIs occurring between receiving the grant by the UE and instructing the UE to transmit uplink data according to the grant. In some cases, identifying the second TTI further includes identifying the second TTI as being offset from the first TTI by the TTI offset. In some cases, identifying the second TTI includes determining that the TTI offset is a zero TTI offset, where the second TTI and the first TTI are the same TTI. In some cases, identifying the offset information further includes receiving control signaling semi-statically configuring the UE with the offset information. In some cases, identifying the offset information further includes receiving downlink control information in the first TTI including offset information for dynamically configuring the UE with the TTI offset. In some cases, the first value is K2 and the second TTI is a TTI occurring before the TTI corresponding to the first value.

[0220] A-SRS component 1030 can determine a second TTI for transmitting an A-SRS based on the TTI offset; transmit the A-SRS in an SRS resource of the second TTI; and transmit the A-SRS in an SRS resource of the second TTI. In some cases, determining the second TTI further includes determining a TTI index after a delay indicated in the offset information, where the second TTI corresponds to the TTI index. In some cases, the SRS resource corresponds to a subset of symbol periods within the second TTI.

[0221] The TTI identifier component 1035 can identify the second TTI based on a first number of symbol periods between receiving the grant by the UE and the UE being able to transmit uplink data, the first number of symbol periods meeting or being less than a difference between a number of symbol periods between the SRS resource of the second TTI and the control channel of the first TTI. In some cases, identifying the second TTI further includes identifying the second TTI based on a second number of symbol periods between receiving the grant by the UE and the UE being able to receive downlink data. In some cases, identifying the second TTI further includes determining a maximum of the first number of symbol periods and the second number of symbol periods. In some cases, the first number of symbol periods and the second number of symbol periods are a specified capability of the UE. In some cases, identifying the second TTI includes determining that the second TTI and the first TTI are a same TTI.

[0222] The configuration information component 1040 can receive configuration information configuring the UE to transmit the A-SRS within at least one symbol index of a set of different symbol indexes of a TTI, where transmitting the A-SRS in the SRS resource of the second TTI further includes transmitting the A-SRS within at least one symbol period of the second TTI corresponding to the at least one symbol index. In some cases, receiving configuration information configuring the UE to transmit the A-SRS within at least one symbol index of a set of different symbol indexes of a TTI, where transmitting the A-SRS in the SRS resource of the second TTI further includes transmitting the A-SRS within at least one symbol period of the second TTI corresponding to the at least one symbol index. In some cases, receiving configuration information configuring the UE to transmit the A-SRS within at least one symbol index of a set of different symbol indexes of a TTI, where transmitting the A-SRS in the SRS resource of the second TTI further includes transmitting the A-SRS within at least one symbol period of the second TTI corresponding to the at least one symbol index, where a number of symbol periods between the at least one symbol period of the second TTI and the control channel of the first TTI meets or exceeds a maximum value.

[0223] The capability information component 1045 can transmit capability information indicating a number of symbol periods between receiving a grant by the UE and the UE being able to transmit uplink data in accordance with the grant, where the latency corresponds to the capability information; transmit capability information indicating a first number of symbol periods; and transmit capability information indicating the first number of symbol periods and a second number of symbol periods. In some examples, the latency corresponds to specified capability information indicating a number of symbol periods between receiving a grant by the UE and the UE being able to transmit uplink data in accordance with the grant.

[0224] The control information component 1050 can receive downlink control information in a first TTI that includes offset information, where the grant indicates resources in a shared data channel allocated to the UE for reception of downlink data. In some cases, the offset information is a sequence of bits included within the downlink control information of the first TTI that corresponds to a number of TTIs that occur between reception of the grant by the UE and the UE being able to transmit uplink data according to the grant. In some cases, the sequence of bits is configured to jointly trigger transmission of a zero-power channel state information reference signal (channel state information (CSI)-RS) from the base station and transmission of an A-SPS from the UE.

[0225] Figure 11 A diagram includes a system 1100 including a device 1105 in accordance with aspects of the present disclosure is shown. The device 1105 can be an example of or include the components of wireless device 805, wireless device 905, or a UE 115 as described above, e.g., with reference to Figure 8 and 9 The device 1105 can include components for bi-directional voice and data communications including components for transmitting and receiving communications, including a UE communications manager 1115, a processor 1120, memory 1125, software 1130, a transceiver 1135, an antenna 1140, and an I / O controller 1145. These components can be in electronic communication via one or more buses (e.g., bus 1110). The device 1105 can communicate wirelessly with one or more base stations 105.

[0226] The processor 1120 can 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 1120 can be configured to operate a memory array using a memory controller. In other cases, a memory controller can be integrated into the processor 1120. The processor 1120 can be configured to execute computer-readable instructions stored in the memory to perform various

[0227] The memory 1125 can include random access memory (RAM) and read only memory (ROM). The memory 1125 can store computer-readable, computer-executable software 1130 including instructions that, when executed, cause the processor to perform various functions described herein. In some cases, the memory 1125 can contain, among other computer-readable or computer-executable software, a basic input / output system (BIOS) which can control basic hardware or software operation such as the interaction with peripheral components or devices.

[0228] Software 1130 can include code to implement aspects of the present disclosure, including code to support reference signal transmission and triggering. Software 1130 can be stored in a non-transitory computer-readable medium such as system memory or other memory. In some cases, the software 1130 can not be directly executable by the processor but can cause a computer (e.g., when compiled and executed) to perform functions described herein.

[0229] Transceiver 1135 can communicate bi-directionally, via one or more antennas, wired, or wireless links as described above. For example, transceiver 1135 can represent a wireless transceiver and can communicate bi-directionally with another wireless transceiver. The transceiver 1135 can also include a modem to modulate the packets and provide the modulated packets to the antennas for transmission, and to demodulate packets received from the antennas.

[0230] In some cases, the wireless device can include a single antenna 1140. However, in some cases the device can have more than one antenna 1140, which can be capable of concurrently transmitting or receiving multiple wireless transmissions.

[0231] I / O controller 1145 can manage input and output signals for device 1105. I / O controller 1145 can also manage peripherals not integrated into device 1105. In some cases, I / O controller 1145 can represent a physical connection or port to or another known operating system. In other cases, I / O controller 1145 can represent a modem, a keyboard, a mouse, a touchscreen, or similar device, or interaction with such devices. In some cases, I / O controller 1145 can be implemented as part of a processor. In some cases, a user can interact with device 1105 via I / O controller 1145 or via hardware components controlled by I / O controller 1145.

[0232] Figure 12 A block diagram 1200 of a wireless device 1205 in accordance with aspects of the present disclosure is shown. The wireless device 1205 can be an example of aspects of a base station 105 as described herein. The wireless device 1205 can include a receiver 1210, a base station communications manager 1215, and a transmitter 1220. The wireless device 1205 can also include a processor. Each of these components can be in communication with one another (e.g., via one or more buses).

[0233] The receiver 1210 can receive information such as packets, user data, or control information associated with various information channels (e.g., control channels, data channels, and information related to reference signal transmission and triggering, etc.). Information can be passed on to other components of the device. The receiver 1210 can be a Figure 15 The described aspects of the transceiver 1535 can be implemented. The receiver 1210 can utilize a single antenna or a set of antennas.

[0234] The base station communications manager 1215 can be an example of Figure 15 the described aspects of the base station communications manager 1515.

[0235] The base station communications manager 1215 and / or at least some of its various sub-components can be implemented in hardware, software executed by a processor, firmware, or any combination thereof. If implemented in software executed by a processor, the functions of the base station communications manager 1215 and / or at least some of its various sub-components can be executed by a general-purpose processor, a DSP, an ASIC, an FPGA or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described in the present disclosure. The base station communications manager 1215 and / or at least some of its various sub-components can be physically located in various places at different times, including being distributed over multiple locations both locally and remotely. In some examples, at least some of the base station communications manager 1215 and / or its various sub-components can be a separate and distinct component in accordance with various aspects of the present disclosure. In other examples, at least some of the base station communications manager 1215 and / or its various sub-components can 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.

[0236] The base station communications manager 1215 can transmit, within a first TTI, a grant that triggers a UE to transmit an aperiodic sounding reference signal (A-SRS); identify offset information indicating a TTI offset relative to the grant; determine a second TTI for the A-SRS based on the TTI offset; and monitor an SRS resource of the second TTI for the A-SRS. The base station communications manager 1215 can also transmit, within a first TTI, a grant that triggers a UE to transmit an aperiodic sounding reference signal (A-SRS); identify a second TTI based on a number of first symbol periods between receiving the grant by the UE and the UE being able to transmit uplink data, the number of first symbol periods satisfying or being less than a difference between a number of symbol periods between an SRS resource of the second TTI and a control channel of the first TTI; and monitor the SRS resource of the second TTI for the A-SRS.

[0237] The transmitter 1220 can transmit signals generated by other components of the device. In some examples, the transmitter 1220 can be collocated with a receiver 1210 in a transceiver module. For example, the transmitter 1220 can be a Figure 15 The described aspects of the transceiver 1535 can be implemented in a transmitter 1220. The transmitter 1220 can utilize a single antenna or a set of antennas.

[0238] Figure 13 A block diagram 1300 of a wireless device 1305 in accordance with aspects of the present disclosure is shown. The wireless device 1305 can be an example of aspects of a wireless device 1205 or a base station 105 as described with reference to Figure 12 The wireless device 1305 can include a receiver 1310, a base station communications manager 1315, and a transmitter 1320. The wireless device 1305 can also include a processor. Each of these components can be in communication with one another (e.g., via one or more buses).

[0239] The receiver 1310 can receive information such as packets, user data, or control information associated with various information channels (e.g., control channels, data channels, and information related to reference signal transmission and triggering, etc.). Information can be passed on to other components of the device. The receiver 1310 can be an example of aspects of the transceiver 1535 described with reference to Figure 15 The described aspects of the transceiver 1535 can be implemented in a receiver 1310. The receiver 1310 can utilize a single antenna or a set of antennas.

[0240] The base station communications manager 1315 can be an example of aspects of the base station communications manager 1515 described with reference to Figure 15 The described aspects of the base station communications manager 1515 can be implemented to realize one or more potential advantages. For example, a base station can transmit a grant that triggers a UE to transmit an A-SRS. The base station can identify an offset information indicating a TTI offset relative to the grant. The base station can determine a second TTI for the A-SRS based on the TTI offset. The base station can monitor an SRS resource of the second TTI for the A-SRS.

[0241] The base station communications manager 1315 can also include a resource grant component 1325, an offset information component 1330, a TTI identifier component 1335, and a monitoring component 1340.

[0242] The resource grant component 1325 can transmit, within the first TTI, a grant triggering the UE to transmit an aperiodic sounding reference signal (A-SRS). In some cases, the grant indicates resources in a shared data channel allocated to the UE for reception of downlink data.

[0243] The offset information component 1330 can identify offset information indicating a TTI offset relative to the grant. In some cases, the offset information corresponds to a TTI index after a delay, and where the second TTI corresponds to the TTI index. In some cases, the offset information includes a bit sequence corresponding to a number of TTIs occurring between reception of the grant by the UE and an instruction for the UE to transmit uplink data according to the grant. In some cases, the bit sequence is configured to jointly trigger transmission of a zero-power channel state information reference signal (CSIRS) from the base station and transmission of the A-SRS from the UE. In some cases, the UE is preconfigured with the TTI offset.

[0244] The TTI identifier component 1335 can determine a second TTI for the A-SRS based on the TTI offset; and identify the second TTI based on a first number of symbol periods between reception of the grant by the UE and an ability of the UE to transmit uplink data that satisfies or is less than a difference between a number of symbol periods between SRS resources of the second TTI and a control channel of the first TTI. In some cases, identifying the second TTI further includes identifying the second TTI as being offset from the first TTI by the TTI offset. In some cases, identifying the second TTI includes determining that the TTI offset is a zero TTI offset, where the second TTI and the first TTI are the same TTI. In some cases, identifying the second TTI further includes identifying the second TTI based on a second number of symbol periods between reception of the grant by the UE and an ability of the UE to receive downlink data. In some cases, identifying the second TTI further includes determining a maximum of the first number of symbol periods and the second number of symbol periods. In some cases, identifying the second TTI includes determining that the second TTI and the first TTI are the same TTI.

[0245] The monitoring component 1340 can monitor the SRS resources of the second TTI for the A-SRS, and monitor the SRS resources of the second TTI for the A-SRS.

[0246] The transmitter 1320 can transmit signals generated by other components of the device. In some examples, the transmitter 1320 can be collocated with a receiver 1310 in a transceiver module. For example, the transmitter 1320 can be an example of aspects of the transceiver 1535 described Figure 15 described aspects of the transceiver 1535. The transmitter 1320 can utilize a single antenna or a set of antennas.

[0247] Figure 14 A block diagram 1400 of a base station communications manager 1415 in accordance with aspects of the present disclosure is shown. The base station communications manager 1415 can be an example of aspects of the base station communications managers 1515 described with reference to Figure 12 、 13 and 15. The base station communications manager 1415 can include resource grant component 1420, offset information component 1425, TTI identifier component 1430, monitoring component 1435, configuration information component 1440, control information component 1445, capability information component 1450, A-SRS component 1455, measurement component 1460, and scheduling component 1465. Each of these modules can communicate, directly or indirectly, with one another (e.g., via one or more buses).

[0248] The resource grant component 1420 can transmit, within a first TTI, a grant that triggers a UE to transmit an aperiodic sounding reference signal (A-SRS). In some cases, the grant indicates resources in a shared data channel allocated to the UE for reception of downlink data.

[0249] The offset information component 1425 can identify offset information indicating a TTI offset relative to the grant. In some cases, the offset information corresponds to a TTI index after a delay, and where the second TTI corresponds to the TTI index. In some cases, the offset information includes a sequence of bits corresponding to a number of TTIs that occur between reception of the grant by the UE and an instruction for the UE to transmit uplink data in accordance with the grant. In some cases, the sequence of bits is configured to jointly trigger transmission of a zero-power channel state information reference signal (CSIRS) from the base station and transmission of the A-SRS from the UE. In some cases, the UE is preconfigured with the TTI offset.

[0250] The TTI identifier component 1430 can determine a second TTI for the A-SRS based on the TTI offset; and identify the second TTI based on a number of first symbol periods between receiving the grant by the UE and the UE being able to transmit uplink data that satisfies or is less than a difference between a number of symbol periods between the SRS resource of the second TTI and the control channel of the first TTI. In some cases, identifying the second TTI further includes identifying the second TTI as being offset from the first TTI by the TTI offset. In some cases, identifying the second TTI includes determining that the TTI offset is a zero TTI offset, where the second TTI and the first TTI are the same TTI. In some cases, identifying the second TTI further includes identifying the second TTI based on a number of second symbol periods between receiving the grant by the UE and the UE being able to receive downlink data. In some cases, identifying the second TTI further includes determining a maximum of the number of first symbol periods and the number of second symbol periods. In some cases, identifying the second TTI includes determining that the second TTI and the first TTI are the same TTI.

[0251] The monitoring component 1435 can monitor the SRS resource of the second TTI for the A-SRS, and monitor the SRS resource of the second TTI for the A-SRS.

[0252] The configuration information component 1440 can transmit configuration information to configure the UE to transmit the A-SRS within at least one symbol index of a set of different symbol indexes of a TTI, where monitoring the SRS resource of the second TTI for the A-SRS further includes monitoring at least one symbol period in the second TTI corresponding to the at least one symbol index for the A-SRS. In some cases, transmitting configuration information to configure the UE to transmit the A-SRS within at least one symbol index of a set of different symbol indexes of a TTI, where monitoring the SRS resource of the second TTI for the A-SRS further includes monitoring for the A-SRS within the at least one symbol period in the second TTI corresponding to the at least one symbol index. In some cases, transmitting configuration information to configure the UE to transmit the A-SRS within at least one symbol index of a set of different symbol indexes of a TTI, where monitoring the SRS resource of the second TTI for the A-SRS further includes monitoring the SRS resource of the second TTI for the A-SRS within the at least one symbol period in the second TTI corresponding to the at least one symbol index, where a number of symbol periods between the at least one symbol period of the second TTI and the control channel of the first TTI satisfies or exceeds a maximum value.

[0253] The control information component 1445 can transmit, within a first TTI, downlink control information that includes offset information, where the offset information indicates a delay corresponding to a number of TTIs that occur between a grant being received by the UE and the UE being instructed to transmit uplink data according to the grant; transmit, in a first TTI, downlink control information that includes offset information, where the grant indicates resources in a shared data channel allocated to the UE for transmission of uplink data, and where the offset information includes a bit flag that indicates whether the UE is to use a first value for a TTI offset indicated in the downlink control information or a second semi-statically configured value for the TTI offset; transmit, in a first TTI, downlink control information that includes offset information, where the grant indicates resources in a shared data channel allocated to the UE for transmission of uplink data, and where the offset information includes a bit sequence that indicates that a TTI offset corresponds to a number of TTIs that occur between the grant being received by the UE and the UE being instructed to transmit uplink data according to the grant; transmit, in a first TTI, downlink control information that includes offset information, where the grant indicates resources in a shared data channel allocated to the UE for transmission of uplink data, where the offset information includes a bit flag that indicates whether the UE is to use a first value for a TTI offset indicated in the downlink control information or a second value for the TTI offset; transmit control signaling that semi-statically indicates a defined value, where the second value for the TTI offset is a function of the first value for the TTI offset and the defined value; transmit, in a first TTI, downlink control information that includes offset information, where the grant indicates resources in a shared data channel allocated to the UE for reception of downlink data; transmit control signaling to semi-statically configure the UE with the offset information; and transmit, within a first TTI, downlink control information to dynamically configure the UE with the offset information. In some cases, the first value is K2, and the second TTI is a TTI that occurs before a TTI corresponding to the first value.

[0254] The capability information component 1450 can receive capability information that indicates a number of symbol periods between a grant being received by the UE and the UE being able to transmit uplink data according to the grant, where the delay corresponds to the capability information; receive capability information that indicates a first number of symbol periods; and receive capability information that indicates a first number of symbol periods and a second number of symbol periods. In some examples, the delay corresponds to specified capability information that indicates a number of symbol periods between a grant being received by the UE and the UE being able to transmit uplink data according to the grant. In some cases, the first number of symbol periods and the second number of symbol periods correspond to defined capability information of the UE, respectively.

[0255] A-SRS component 1455 can receive an A-SRS within an SRS resource of the second TTI. In some cases, the SRS resource corresponds to a subset of symbol periods within the second TTI.

[0256] Measurement component 1460 can generate a channel measurement based on the received A-SRS.

[0257] Scheduling component 1465 can generate a frequency-dependent scheduling decision based on the channel measurement.

[0258] Figure 15 A diagram includes a system 1500 including a device 1505 in accordance with aspects of the present disclosure is shown. The device 1505 can be an example of or include the components of base station 105 as described above, e.g., with reference to Figure 1 The device 1505 can be an example of or include the components of base station 105 as described above, e.g., with reference to FIG. 1. The device 1505 can include components for bi-directional voice and data communications including components for transmitting and receiving communications, including base station communications manager 1515, processor 1520, memory 1525, software 1530, transceiver 1535, antenna 1540, network communications manager 1545, and inter-station communications manager 1550. These components can be in electronic communication via one or more buses (e.g., bus 1510). The device 1505 can communicate wirelessly with one or more UEs 115.

[0259] The processor 1520 can include an intelligent hardware device, (e.g., a general- purpose processor, a DSP, a CPU, a microcontroller, an ASIC, an FPGA, a programmable logic device, a discrete gate or transistor logic component, a discrete hardware component, or any combination thereof). In some cases, the processor 1520 can be configured to operate a memory array using a memory controller. In other cases, a memory controller can be integrated into the processor 1520. The processor 1520 can be configured to execute computer-readable instructions stored in the memory to perform various

[0260] The memory 1525 can include RAM and ROM. The memory 1525 can store computer-readable, computer-executable software 1530 including instructions that, when executed, cause the processor to perform various functions described herein. In some cases, the memory 1525 can contain, among other computer-readable or computer-executable software 1530, a BIOS which can control basic hardware or software operation such as the interaction with peripheral components or devices.

[0261] Software 1530 can include code to implement aspects of the present disclosure, including code to support reference signal transmission and triggering. Software 1530 can be stored in a non-transitory computer-readable medium such as system memory or other memory. In some cases, the software 1530 can not be directly executable by the processor but can cause a computer (e.g., when compiled and executed) to perform functions described herein.

[0262] Transceiver 1535 can communicate bi-directionally, via one or more antennas, wired, or wireless links as described above. For example, transceiver 1535 can represent a wireless transceiver and can communicate bi-directionally with another wireless transceiver. The transceiver 1535 can also include a modem to modulate the packets and provide the modulated packets to the antennas for transmission, and to demodulate packets received from the antennas.

[0263] In some cases, the wireless device can include a single antenna 1540. However, in some cases the device can have more than one antenna 1540, which can be capable of concurrently transmitting or receiving multiple wireless transmissions.

[0264] Network communications manager 1545 can manage communications with the core network (e.g., via one or more wired backhaul links). For example, the network communications manager 1545 can manage the transfer of data communications for client devices, such as one or more UEs 115.

[0265] Inter-station communications manager 1550 can manage communications with other base station 105, and can include a controller or scheduler to coordinate scheduling of communications with UEs 115 by other base stations 105. For example, the inter-station communications manager 1550 can coordinate scheduling of transmissions to UEs 115 for various interference mitigation techniques such as beamforming or joint transmission. In some examples, inter-station communications manager 1550 can provide an X2 interface within a Long Term Evolution (LTE) / LTE-A wireless communication network technology to provide communication between base stations 105.

[0266] Figure 16 A method 1600 for reference signal transmission and triggering is illustrated, in accordance with aspects of the present disclosure. Operations of method 1600 can be implemented by a UE 115 or its components as described herein. For example, operations of method 1600 can be performed by a UE communications manager as described with reference to FIG. 11. In some examples, a UE 115 can execute a set of codes to control the functional elements of the device to perform the functions described below. Additionally or alternatively, the UE 115 can perform aspects of the functions described below using special-purpose hardware. Figures 8 to 11

[0267] ​At 1605, the UE 115 can detect, within a first transmission time interval (TTI), a grant that triggers the UE to transmit an aperiodic sounding reference signal (A-SRS). The operations of 1605 can be performed according to the methods described herein. In certain examples, aspects of the operations of 1605 can be performed by a detection component as described with reference to Figures 8 to 11 FIG. 19.

[0268] At 1610, the UE 115 can identify offset information that indicates an offset relative to a TTI of the grant. The operations of 1610 can be performed according to the methods described herein. In certain examples, aspects of the operations of 1610 can be performed by an offset information component as described with reference to Figures 8 to 11 FIG. 19.

[0269] At 1615, the UE 115 can determine a second TTI for transmitting the A-SRS based at least in part on the TTI offset. The operations of 1615 can be performed according to the methods described herein. In certain examples, aspects of the operations of 1615 can be performed by an A-SRS component as described with reference to Figures 8 to 11 FIG. 19.

[0270] At 1620, the UE 115 can transmit the A-SRS in an SRS resource of the second TTI. The operations of 1620 can be performed according to the methods described herein. In certain examples, aspects of the operations of 1620 can be performed by an A-SRS component as described with reference to Figures 8 to 11 FIG. 19.

[0271] Figure 17 A method 1700 for reference signal transmission and triggering is shown and described with reference to FIG. 17. The operations of method 1700 can be implemented by a UE 115 or its components as described herein. For example, the operations of method 1700 can be performed by a UE communications manager as described with reference to Figures 8 to 11 FIG. 19. In some examples, a UE 115 can execute a set of codes to control the functional elements of the device to perform the functions described below. Additionally or alternatively, the UE 115 can perform aspects of the functions described below using special-purpose hardware.

[0272] At 1705, the UE 115 can detect, within a first transmission time interval (TTI), a grant that triggers the UE to transmit an aperiodic sounding reference signal (A-SRS). The operations of 1705 can be performed according to the methods described herein. In certain examples, aspects of the operations of 1705 can be performed by a detection component as described with reference to Figures 8 to 11 FIG. 19.

[0273] At 1710, the UE 115 can receive downlink control information including offset information in a first TTI, where the grant indicates resources in a shared data channel allocated to the UE for transmission of uplink data, and where the offset information is a bit flag indicating whether the UE is to use a first value for a TTI offset indicated in the downlink control information or a second semi-statically configured value for a TTI offset. The operations of 1710 can be performed according to the methods described herein. In certain examples, aspects of the operations of 1710 can be performed by an offset information component as described with reference to Figures 8 to 11

[0274] At 1715, the UE 115 can identify offset information indicating a TTI offset relative to the grant. The operations of 1715 can be performed according to the methods described herein. In certain examples, aspects of the operations of 1715 can be performed by an offset information component as described with reference to Figures 8 to 11

[0275] At 1720, the UE 115 can determine a second TTI for transmitting the A-SRS based at least in part on the TTI offset. The operations of 1720 can be performed according to the methods described herein. In certain examples, aspects of the operations of 1720 can be performed by an A-SRS component as described with reference to Figures 8 to 11

[0276] At 1725, the UE 115 can transmit the A-SRS in SRS resources of the second TTI. The operations of 1725 can be performed according to the methods described herein. In certain examples, aspects of the operations of 1725 can be performed by an A-SRS component as described with reference to Figures 8 to 11

[0277] Figure 18 A method 1800 for reference signal transmission and triggering is shown and described in accordance with aspects of the present disclosure. The operations of method 1800 can be implemented by a UE 115 or its components as described herein. For example, the operations of method 1800 can be performed by a UE communications manager as described with reference to Figures 8 to 11

[0278] At 1805, the UE 115 can detect, within a first transmission time interval (TTI), a grant triggering the UE to transmit an aperiodic sounding reference signal (A-SRS). The operations of 1805 can be performed according to the methods described herein. In certain examples, aspects of the operations of 1805 can be performed by a grant component as described with reference to Figures 8 to 11 ​​​​​The described detection component to perform.

[0279] At 1810, the UE 115 can identify a second TTI based at least in part on a first number of symbol periods between receiving a grant by the UE and the UE being able to transmit uplink data, the first number of symbol periods meeting or being less than a difference between a number of symbol periods between an SRS resource of the second TTI and a control channel of the first TTI. The operations of 1810 can be performed according to the methods described herein. In certain examples, aspects of the operations of 1810 can be performed by an TTI identifier component as described with reference to Figures 8 to 11 The described TTI identifier component to perform.

[0280] At 1815, the UE 115 can transmit the A-SRS in the SRS resource of the second TTI. The operations of 1815 can be performed according to the methods described herein. In certain examples, aspects of the operations of 1815 can be performed by an A-SRS component as described with reference to Figures 8 to 11 The described A-SRS component to perform.

[0281] Figure 19 A method 1900 for reference signal transmission and triggering is shown that illustrates aspects of the present disclosure. The operations of method 1900 can be implemented by a UE 115 or its components as described herein. For example, the operations of method 1900 can be performed by a UE communications manager as described with reference to Figures 8 to 11 FIGS. 13 through 17. In some examples, a UE 115 can execute a set of codes to control the functional elements of the device to perform the functions described below. Additionally or alternatively, the UE 115 can perform aspects of the functions described below using special-purpose hardware. The UE 115 can operate using

[0282] At 1905, the UE 115 can transmit capability information indicating a first number of symbol periods. The operations of 1905 can be performed according to the methods described herein. In certain examples, aspects of the operations of 1905 can be performed by a capability information component as described with reference to Figures 8 to 11 The described capability information component to perform.

[0283] At 1910, the UE 115 can detect, within a first transmission time interval (TTI), a grant triggering the UE to transmit an aperiodic sounding reference signal (A-SRS). The operations of 1910 can be performed according to the methods described herein. In certain examples, aspects of the operations of 1910 can be performed by a detection component as described with reference to Figures 8 to 11 The described detection component to perform.

[0284] At 1915, the UE 115 can identify a second TTI based at least in part on a first number of symbol periods between receiving the grant by the UE and the UE being able to transmit uplink data, the first number of symbol periods satisfying or being less than a difference between a number of symbol periods between the SRS resource of the second TTI and a control channel of the first TTI. The operations of 1915 can be performed according to the methods described herein. In certain examples, aspects of the operations of 1915 can be performed by a TTI identifier component as described with reference to Figures 8 to 11 FIG. 19.

[0285] At 1920, the UE 115 can transmit the A-SRS in the SRS resource of the second TTI. The operations of 1920 can be performed according to the methods described herein. In certain examples, aspects of the operations of 1920 can be performed by an A-SRS component as described with reference to Figures 8 to 11 FIG. 19.

[0286] Figure 20 A method 2000 for reference signal transmission and triggering is shown and described in accordance with aspects of the present disclosure. The operations of method 2000 can be implemented by a base station 105 or its components as described herein. For example, the operations of method 2000 can be performed by a base station communications manager as described with reference to Figures 12 to 15 FIG. 19.

[0287] At 2005, the base station 105 can transmit a grant that triggers a user equipment (UE) to transmit an aperiodic sounding reference signal (A-SRS) within a first transmission time interval (TTI). The operations of 2005 can be performed according to the methods described herein. In certain examples, aspects of the operations of 2005 can be performed by a resource grant component as described with reference to Figures 12 to 15 FIG. 19.

[0288] At 2010, the base station 105 can identify offset information that indicates a TTI offset relative to the grant. The operations of 2010 can be performed according to the methods described herein. In certain examples, aspects of the operations of 2010 can be performed by an offset information component as described with reference to Figures 12 to 15 FIG. 19.

[0289] At 2015, the base station 105 can determine a second TTI for the A-SRS based at least in part on the TTI offset. The operations of 2015 can be performed according to the methods described herein. In certain examples, aspects of the operations of 2015 can be performed by a TTI identifier component as described with reference to Figures 12 to 15 FIG. 19.

[0290] At 2020, the base station 105 can monitor the SRS resource of the second TTI for the A-SRS. The operations of 2020 can be performed according to the methods described herein. In some examples, aspects of the operations of 2020 can be performed by a monitoring component as described with reference to Figures 12 to 15 FIG. 13.

[0291] Figure 21 A method 2100 for reference signal transmission and triggering is shown illustrating a flowchart in accordance with aspects of the present disclosure. Operations of method 2100 can be implemented by a base station 105 or its components as described herein. For example, the operations of method 2100 can be performed by a base station communications manager as described with reference to Figures 12 to 15 FIG. 13. In some examples, a base station 105 can execute a set of codes to control the functional elements of the device to perform the functions described below. Additionally or alternatively, the base station 105 can perform aspects of the functions described below using special-purpose hardware.

[0292] At 2105, the base station 105 can transmit, within a first transmission time interval (TTI), a grant that triggers a user equipment (UE) to transmit an aperiodic sounding reference signal (A-SRS). The operations of 2105 can be performed according to the methods described herein. In some examples, aspects of the operations of 2105 can be performed by a resource grant component as described with reference to Figures 12 to 15 FIG. 13.

[0293] At 2110, the base station 105 can identify a second TTI based at least in part on a first number of symbol periods between reception of the grant by the UE and when the UE is able to transmit uplink data, the first number of symbol periods satisfying or being less than a difference between a number of symbol periods between an SRS resource of the second TTI and a control channel of the first TTI. The operations of 2110 can be performed according to the methods described herein. In some examples, aspects of the operations of 2110 can be performed by a TTI identifier component as described with reference to Figures 12 to 15 FIG. 13.

[0294] At 2115, the base station 105 can monitor the SRS resource of the second TTI for the A-SRS. The operations of 2115 can be performed according to the methods described herein. In some examples, aspects of the operations of 2115 can be performed by a monitoring component as described with reference to Figures 12 to 15 FIG. 13.

[0295] implementations, and that the operations and / or steps can be rearranged or otherwise modified and that other implementations are possible. Further, aspects from two or more of the methods can be combined.

[0296] The techniques described herein can be used for various wireless communication 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 can 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 can be commonly referred to as CDMA2000 IX, IX, etc. IS-856 (TIA-856) is commonly referred to as CDMA2000 lxEV-DO, High Rate Packet Data (HRPD), etc. UTRA includes Wideband CDMA (WCDMA) and other variants of CDMA. A TDMA system can implement a radio technology such as Global System for Mobile Communications (GSM).

[0297] An OFDMA system can 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 can be used for the systems and radio technologies mentioned above as well as other systems and radio technologies. While aspects of an LTE, LTE-A, LTE-A Pro, or NR system can be described

[0298] Macrocells typically cover a relatively large geographic area (e.g., an area with a radius of several kilometers) and allow unrestricted access by UE 115 with a service subscription to a network provider. Small cells may be associated with a lower-power base station 105 (compared to macrocells) and may operate in the same or different (e.g., licensed, unlicensed, etc.) frequency bands as macrocells. Depending on the examples, small cells may include picocells, femtocells, and microcells. Picocells may, for example, cover a smaller geographic area and allow unrestricted access by UE 115 with a service subscription to a network provider. Femtocells may also cover a smaller geographic area (e.g., a residential area) and provide restricted access by UE 115 associated with that femtocell (e.g., UE 115 in a closed subscriber group (CSG), UE 115 of a user in a residence, etc.). The eNB used for a macrocell may be referred to as a macro eNB. eNBs used for small cells may be referred to as small cell eNBs, pico eNBs, femto eNBs, or home eNBs. An eNB can support one or more (e.g., two, three, four, etc.) cells and can also support communication using one or more component carriers.

[0299] One or more wireless communication systems 100 described herein can support synchronous or asynchronous operation. For synchronous operation, base stations 105 can have similar frame timing, and transmissions from different base stations 105 can be approximately time-aligned. For asynchronous operation, base stations 105 can have different frame timing, and transmissions from different base stations 105 may not be time-aligned. The techniques described herein can be used for both synchronous and asynchronous operation.

[0300] The information and signals described herein can be represented using any of a wide variety of different techniques and methods. For example, data, instructions, commands, information, signals, bits, symbols, and chips that may be referred to throughout the above description can be represented by voltage, current, electromagnetic waves, magnetic fields or magnetic particles, light fields or light particles, or any combination thereof.

[0301] The various illustrative blocks and modules described in connection with the disclosure herein can be implemented or performed with 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 (PLD), discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general-purpose processor can be a microprocessor, but in the alternative, the processor can be any conventional processor, controller, microcontroller, or state machine. A processor can also be implemented as a combination of computing devices (e.g., a combination of a DSP and a microprocessor, multiple microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration).

[0302] The functions described herein can be implemented in hardware, software executed by a processor, firmware, or any combination thereof. If implemented in software executed by a processor, the functions can be stored on or transmitted over as one or more instructions or code on a computer-readable medium. Other examples and implementations are within the scope of the disclosure and appended claims. For example, due to the nature of software, functions described above can be implemented using software executed by a processor, hardware, firmware, hardwiring, or combinations of any of these. Features implementing functions can also be physically located at various positions, including being distributed such that portions of functions are implemented at different physical locations.

[0303] Computer-readable media includes both non-transitory computer storage media and communication media including any medium that facilitates transfer of a computer program from one place to another. A non-transitory storage medium can be any available medium that can be accessed by a general purpose or special purpose computer. By way of example, and not limitation, non-transitory computer-readable media can include random-access memory (RAM), read-only memory (ROM), electrically erasable programmable read only memory (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.

[0304] As used herein, including in the claims “or” as used in a list of items (for example, 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

[0305] In the drawings, like reference numerals can be used to denote similar components throughout the several views. Additionally, various components of the same type can be distinguished from each other by following the convention of numbering them with the first two digits making up the existing drawing number and the third and fourth digits being the duplicate number particular to the same drawing figure. If, in the specification, only a single drawing figure is referred to, this is simply intended to mean that a like component in more than one drawing figure is intended to be referred to.

[0306] The description set forth herein, in connection with the appended drawings, describes example configurations and does not represent all the examples that can be implemented or that are within the scope of the claims. The term "exemplary" used herein means "serving as an example, instance, or illustration," and not "preferred" over other examples. The detailed description includes specific details for the purpose of providing an understanding of the described techniques. These techniques, however, can be practiced without these specific details. In some instances, well-known structures and devices are shown in block diagram form in order to avoid obscuring the concepts of the described examples.

[0307] The description herein is presented to enable any 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 can be applied to other variations without departing from the scope of the disclosure. Thus, the disclosure is not to be limited to the examples and designs described herein but is to be accorded the broadest scope consistent with the principles and novel features disclosed herein.

Claims

1. An apparatus for wireless communication, comprising: a memory; and at least one processor coupled to the memory, wherein the apparatus is configured to: detect, within a first transmission time interval (TTI), a downlink control information that triggers a user equipment (UE) to transmit an aperiodic sounding reference signal (A-SRS); identify a first number of symbol periods between reception of the downlink control information by the UE and an ability of the UE to transmit uplink data; identify a second TTI based on the first number of symbol periods; and transmit the A-SRS in an SRS resource of the second TTI.

2. The apparatus of claim 1, wherein the apparatus is configured to: receive the downlink control information of the first TTI including offset information, wherein the downlink control information indicates resources in a shared data channel allocated to the UE for receiving downlink data.

3. The apparatus of claim 2, wherein the offset information is a sequence of bits included in the downlink control information of the first TTI, wherein transmission of the A-SRS is based on the sequence of bits.

4. The apparatus of claim 3, wherein the sequence of bits includes zero bits, one bit, two bits, or three bits.

5. The apparatus of claim 3, wherein the sequence of bits corresponds to a number of TTIs occurring between reception of the downlink control information by the UE and an ability of the UE to receive downlink data in accordance with the downlink control information.

6. The apparatus of claim 3, wherein the sequence of bits is configured to jointly trigger transmission of a zero-power channel state information (CSI)-RS from a network device and transmission of the A-SRS from the UE.

7. The apparatus of claim 1, wherein the downlink control information indicates resources in a shared data channel allocated to the UE for receiving downlink data.

8. The apparatus of claim 7, wherein to identify the second TTI, the apparatus is configured to: identify the second TTI based on a second number of symbol periods between reception of the downlink control information by the UE and an ability of the UE to receive downlink data.

9. The apparatus of claim 8, wherein to identify the second TTI, wherein the apparatus is configured to: determine a maximum of the first number of symbol periods and the second number of symbol periods.

10. The apparatus of claim 9, wherein the apparatus is configured to: receive configuration information that configures the UE to transmit the A-SRS within at least one symbol index of a plurality of different symbol indexes of a TTI, wherein to transmit the A-SRS in the SRS resource of the second TTI, the apparatus is further configured to: transmit the A-SRS within at least one symbol period in the second TTI corresponding to the at least one symbol index, wherein a number of symbol periods between the at least one symbol period of the second TTI and a control channel of the first TTI meets or exceeds the maximum. ​ ​ 11. The apparatus of claim 8, wherein the apparatus is configured to: transmit capability information indicating the first number of symbol periods and the second number of symbol periods.

12. The apparatus of claim 8, wherein the first number of symbol periods and the second number of symbol periods are specified capabilities of the UE.

13. The apparatus of claim 1, wherein to identify the second TTI, the apparatus is configured to determine that the second TTI and the first TTI are a same TTI.

14. The apparatus of claim 1, wherein the first number of symbol periods is equal to or less than a difference between a number of symbol periods between an SRS resource of the second TTI and a control channel of the first TTI.

15. The apparatus of claim 1, the apparatus configured to: receive configuration information configuring the UE to transmit the A-SRS within at least one symbol index of a plurality of different symbol indexes of a TTI, wherein to transmit the A-SRS in the SRS resource of the second TTI, the apparatus is configured to: transmit the A-SRS within at least one symbol period of the second TTI corresponding to the at least one symbol index, wherein the first number of symbol periods meets or exceeds a difference between a number of symbol periods between the at least one symbol period of the second TTI and a control channel of the first transmission time interval (TTI).

16. The apparatus of claim 1, wherein to identify the second TTI, the apparatus is configured to: identify a sounding reference signal (SRS) slot offset indicating the second TTI relative to the first TTI, wherein the SRS slot offset is configured via radio resource control signaling.

17. The apparatus of claim 1, wherein the downlink control information comprises a downlink grant, and wherein the downlink grant triggers the UE to transmit the A-SRS.

18. An apparatus for wireless communication, comprising: a memory; and at least one processor coupled to the memory, wherein the apparatus is configured to: transmit capability information indicating that a user equipment (UE) is capable of transmitting an uplink transmission including a sounding reference signal in a same transmission time interval (TTI) in which a grant is received; detect, within a first TTI, a grant triggering the UE to transmit an aperiodic sounding reference signal (A-SRS); identify a second TTI based on a first number of symbol periods between reception of the grant by the UE and the capability of the UE to transmit the uplink transmission, the first number of symbol periods meeting or being less than a number of symbol periods between an SRS resource of the second TTI and a control channel of the first TTI; and transmit the A-SRS in the SRS resource of the second TTI.

19. The apparatus of claim 18, wherein the apparatus is configured to: ​ receive configuration information, the configuration information configuring the UE to transmit the A-SRS within at least one symbol index of a plurality of different symbol indexes of a TTI, wherein to transmit the A-SRS in the SRS resource of the second TTI, the apparatus is configured to: transmit the A-SRS within at least one symbol period of the second TTI corresponding to the at least one symbol index.

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