Patent Description:
Document <CIT> describes a method and apparatus for communicating in a communication system. The method comprises determining, based on a communication boundary of a first subframe associated with a first carrier, a second subframe associated with a second carrier and performing communication on the second carrier based on the second subframe.

In accordance with the present invention methods, apparatuses and a computer program, as set forth in the independent claims, respectively, are provided. Without limiting the scope of this disclosure, some features will now be discussed briefly. After considering this discussion, and particularly after reading the section entitled "Detailed Description" one will understand how the features of this disclosure provide advantages that include improved utilization of time and frequency resources of a spectrum assigned to a network operator.

Certain aspects provide a method for wireless communication by a User Equipment (UE). The method generally includes receiving downlink control information (DCI) scheduling uplink resources on a secondary cell (SCell) configured on a first spectrum, the scheduled uplink resources to be used for transmitting uplink feedback for at least one downlink transmission on at least one of a primary cell (PCell) or another Scell configured on a second spectrum, wherein a single physical uplink control channel (PUCCH) is allowed to be configured on one of the first or second spectrums and wherein once configured the PUCCH cannot be switched between the first and second spectrums; and transmitting the uplink feedback using the scheduled uplink resources in the first spectrum.

Certain aspects provide a method for wireless communication by a Base Station (BS). The method generally includes transmitting downlink control information (DCI) scheduling uplink resources for a user equipment (UE) on a secondary cell (SCell) configured on a first spectrum, the scheduled uplink resources to be used for transmitting uplink feedback for at least one downlink transmission by the BS on at least one of a primary cell (PCell) or another Scell configured on a second spectrum, wherein a single physical uplink control channel (PUCCH) is allowed to be configured on one of the first or second spectrums and wherein once configured the PUCCH cannot be switched between the first and second spectrums; transmitting the at least one downlink transmission in the second spectrum; and receiving the uplink feedback from the UE using the scheduled uplink resources in the first spectrum.

Certain aspects of the present disclosure provide an apparatus for wireless communication by a UE. The apparatus generally includes at least one processor and a memory coupled to the at least one processor. The at least one processor is generally configured to receive downlink control information (DCI) scheduling uplink resources on a secondary cell (SCell) configured on a first spectrum, the scheduled uplink resources to be used for transmitting uplink feedback for at least one downlink transmission on at least one of a primary cell (PCell) or another Scell configured on a second spectrum, wherein a single physical uplink control channel (PUCCH) is allowed to be configured on one of the first or second spectrums and wherein once configured the PUCCH cannot be switched between the first and second spectrums; and transmit the uplink feedback using the scheduled uplink resources in the first spectrum.

Certain aspects of the present disclosure provide an apparatus for wireless communication by a BS. The apparatus generally includes at least one processor and a memory coupled to the at least one processor. The at least one processor is generally configured to transmit downlink control information (DCI) scheduling uplink resources for a user equipment (UE) on a secondary cell (SCell) configured on a first spectrum, the scheduled uplink resources to be used for transmitting uplink feedback for at least one downlink transmission by the BS on at least one of a primary cell (PCell) or another Scell configured on a second spectrum, wherein a single physical uplink control channel (PUCCH) is allowed to be configured on one of the first or second spectrums and wherein once configured the PUCCH cannot be switched between the first and second spectrums; transmit the at least one downlink transmission in the second spectrum; and receive the uplink feedback from the UE using the scheduled uplink resources in the first spectrum.

Certain aspects of the present disclosure provide a computer-readable medium for wireless communication by a UE, the computer-readable medium storing instructions which when processed by at least one processor perform a method. The method generally including receiving downlink control information (DCI) scheduling uplink resources on a secondary cell (SCell) configured on a first spectrum, the scheduled uplink resources to be used for transmitting uplink feedback for at least one downlink transmission on at least one of a primary cell (PCell) or another Scell configured on a second spectrum, wherein a single physical uplink control channel (PUCCH) is allowed to be configured on one of the first or second spectrums and wherein once configured the PUCCH cannot be switched between the first and second spectrums; and transmitting the uplink feedback using the scheduled uplink resources in the first spectrum.

Certain aspects of the present disclosure provide a computer-readable medium for wireless communication by a BS, the computer-readable medium storing instructions which when processed by at least one processor perform a method. The method generally includes transmitting downlink control information (DCI) scheduling uplink resources for a user equipment (UE) on a secondary cell (SCell) configured on a first spectrum, the scheduled uplink resources to be used for transmitting uplink feedback for at least one downlink transmission by the BS on at least one of a primary cell (PCell) or another Scell configured on a second spectrum, wherein a single physical uplink control channel (PUCCH) is allowed to be configured on one of the first or second spectrums and wherein once configured the PUCCH cannot be switched between the first and second spectrums; transmitting the at least one downlink transmission in the second spectrum; and receiving the uplink feedback from the UE using the scheduled uplink resources in the first spectrum.

Aspects of the present disclosure provide means for, apparatus, processors, and computer-readable mediums for performing the methods described herein.

Aspects of the present disclosure provide apparatus, methods, processing systems, and computer readable mediums for implementing cross-carrier feedback.

In certain aspects, better utilizing the underutilized or unutilized portions of a spectrum is beneficial from the network operator's perspective as this may lead to cost savings. In certain aspects, one approach to use underutilized or unutilized portions of a spectrum, especially when utilization of uplink resources is considerably less than that of downlink resources, is to implement cross-carrier feedback (also referred to as cross-spectrum feedback). For example, underutilized or unutilized uplink resources of a particular spectrum may be used for providing uplink feedback relating to downlink transmissions on a different spectrum.

In certain aspects, in order to implement the cross-carrier (or cross spectrum) feedback numerous limitations need to be addressed. These limitations may include limitations arising out of the RATs (e.g., NR/LTE) used for the spectrums and current standards agreements (e.g., 3GPP NR/LTE standards agreements) relating to the used RATs on these spectrums.

Certain aspects of the present disclosure discuss techniques for better utilizing spectrum resources given the limitations of the current 3GPP standards. The discussed aspects include improved techniques for using underutilized or unutilized uplink resources of a spectrum for providing uplink feedback relating to downlink transmissions on a different spectrum. These improved techniques enable cross-spectrum feedback in the context of carrier aggregation (CA) and supplementary uplink (SUL) while overcoming one or more of the limitations of CA and SUL discussed above.

The following description provides examples of cross-carrier feedback in communication systems, and is not limiting of the scope, applicability, or examples. Changes may be made in the function and arrangement of elements discussed.

According to certain aspects, the BSs <NUM> and UEs <NUM> may be configured for cross-carrier feedback. As shown in <FIG>, the BS 110a includes a feedback manager <NUM>. The feedback manager <NUM> may be configured to transmit DCI scheduling uplink resources for a user equipment (UE) on a secondary cell (SCell) configured on a first spectrum, the scheduled uplink resources to be used for transmitting uplink feedback for at least one downlink transmission by the BS relating to at least one of a primary cell (PCell) or another Scell configured on a second spectrum, wherein the PUCCH is allowed to be configured only on the PCell; transmit the at least one downlink transmission in the second spectrum; and receive the uplink feedback from the UE using the scheduled uplink resources in the first spectrum, in accordance with aspects of the present disclosure. As shown in <FIG>, the UE 120a includes a feedback manager <NUM>. The feedback manager <NUM> may be configured to receive downlink control information (DCI) scheduling uplink resources on a secondary cell (SCell) configured on a first spectrum, the scheduled uplink resources to be used for transmitting uplink feedback for at least one downlink transmission relating to at least one of a primary cell (PCell) or another Scell configured on a second spectrum, wherein a physical uplink control channel (PUCCH) is allowed to be configured only on the PCell; and transmit the uplink feedback using the scheduled uplink resources in the first spectrum, in accordance with aspects of the present disclosure.

At the BS 110a, a transmit processor <NUM> may receive data from a data source <NUM> and control information from a controller/processor <NUM>. The transmit processor <NUM> may also generate reference symbols, such as for the primary synchronization signal (PSS), secondary synchronization signal (SSS), and cell-specific reference signal (CRS). A transmit (TX) multiple-input multiple-output (MIMO) processor <NUM> may perform spatial processing (e.g., precoding) on the data symbols, the control symbols, and/or the reference symbols, if applicable, and may provide output symbol streams to the modulators (MODs) 232a-232t. Downlink signals from modulators 232a-232t may be transmitted via the antennas 234a-234t, respectively.

At the UE 120a, the antennas 252a-252r may receive the downlink signals from the BS 110a and may provide received signals to the demodulators (DEMODs) in transceivers 254a-254r, respectively. A MIMO detector <NUM> may obtain received symbols from all the demodulators 254a-254r, perform MIMO detection on the received symbols if applicable, and provide detected symbols. A receive processor <NUM> may process (e.g., demodulate, deinterleave, and decode) the detected symbols, provide decoded data for the UE 120a to a data sink <NUM>, and provide decoded control information to a controller/processor <NUM>.

On the uplink, at UE 120a, a transmit processor <NUM> may receive and process data (e.g., for the physical uplink shared channel (PUSCH)) from a data source <NUM> and control information (e.g., for the physical uplink control channel (PUCCH) from the controller/processor <NUM>. The symbols from the transmit processor <NUM> may be precoded by a TX MIMO processor <NUM> if applicable, further processed by the demodulators in transceivers 254a-254r (e.g., for SC-FDM, etc.), and transmitted to the BS 110a. At the BS 110a, the uplink signals from the UE 120a may be received by the antennas <NUM>, processed by the modulators <NUM>, detected by a MIMO detector <NUM> if applicable, and further processed by a receive processor <NUM> to obtain decoded data and control information sent by the UE 120a.

The controller/processor <NUM> and/or other processors and modules at the UE 120a may perform or direct the execution of processes for the techniques described herein. For example, as shown in <FIG>, the controller/processor <NUM> of the BS 110a has an feedback manager <NUM> that may be configured for transmit DCI scheduling uplink resources for a user equipment (UE) on a secondary cell (SCell) configured on a first spectrum, the scheduled uplink resources to be used for transmitting uplink feedback for at least one downlink transmission by the BS relating to at least one of a primary cell (PCell) or another Scell configured on a second spectrum, wherein the PUCCH is allowed to be configured only on the PCell; transmit the at least one downlink transmission in the second spectrum; and receive the uplink feedback from the UE using the scheduled uplink resources in the first spectrum, in accordance with aspects of the present disclosure. As shown in <FIG>, the controller/processor <NUM> of the UE 120a has a feedback manager <NUM> that may be configured to receive downlink control information (DCI) scheduling uplink resources on a secondary cell (SCell) configured on a first spectrum, the scheduled uplink resources to be used for transmitting uplink feedback for at least one downlink transmission relating to at least one of a primary cell (PCell) or another Scell configured on a second spectrum, wherein a physical uplink control channel (PUCCH) is allowed to be configured only on the PCell; and transmit the uplink feedback using the scheduled uplink resources in the first spectrum, in accordance with aspects of the present disclosure. Although shown at the Controller/Processor, other components of the UE 120a and BS 110a may be used performing the operations described herein.

The term 'spectrum' (also referred to as 'band') as used in the context of wireless communication technology generally refers to an electromagnetic spectrum containing a set of frequencies (e.g., carrier frequencies) that is available and used for wireless communications between devices of a wireless communications network. Electromagnetic spectrums are generally regulated by national organizations such as the Federal Communications Commission in the U. A and China Telecom Corp. in China, and these organizations determine which frequency ranges can be used for what purpose and by whom. Generally, each network operator in a country is assigned one or more spectrums. In an aspect, these spectrums may include Time Division Duplex (TDD) spectrums and/or Frequency Division Duplex (FDD) spectrums. Further, different spectrums may be used for communications using different Radio Access technologies (RATs). For example, a particular spectrum may be assigned for wireless communications in accordance with LTE or NR set of standards.

Network operators are always trying to better utilize the spectrums assigned to them to optimize costs. However, in certain cases some portions of an assigned spectrum are not optimally utilized from the network operator's perspective. For example, traffic in a particular spectrum can be downlink centric and the utilization of spectrum resources (e.g., time and/or frequency resources) assigned for downlink communication is much higher than the utilization of spectrum resources assigned for uplink communication. In certain cases, more than <NUM>% of uplink resources of a spectrum may not be utilized at all. For example, it has been observed that more than <NUM>% of the uplink resources of certain FDD spectrums may remain unutilized when downlink resources of these FDD spectrums are almost exhausted in a busy hour.

It may be noted that cross-carrier feedback and cross-spectrum feedback are used interchangeably throughout this disclosure.

In one example implementation, unutilized FDD uplink resources of a first FDD spectrum may be used to provide uplink feedback relating to TDD downlink transmissions on a second different TDD spectrum. This way, the unutilized FDD uplink resources may be leveraged for improving performance of UEs, for example, of cell edge UEs in terms of throughput as well as delays. Further, by more fully utilizing the spectrum, the network operator saves costs.

<FIG> illustrates an example utilization of uplink resources of an FDD spectrum for providing uplink feedback relating to TDD downlink transmissions carried out using downlink resources of a TDD spectrum, in accordance with certain aspects of the present disclosure.

As shown in <FIG>, the TDD spectrum <NUM> includes downlink slots (slots numbered as one of D-<NUM>, D-<NUM>, D-<NUM>, D-<NUM> and D-<NUM>), uplink slots (slots numbered as U-<NUM>, U-<NUM> and U-<NUM>) and special slots (numbered as S-<NUM> and S-<NUM>). Each of the special slots S-<NUM> and S-<NUM> include <NUM> downlink symbols, <NUM> gap symbols and <NUM> uplink symbols.

As shown, the FDD spectrum <NUM> includes uplink slots (slots numbered as one of U-<NUM>, U-<NUM>, U-<NUM>, U-<NUM> and U-<NUM>) and downlink slots (slots numbered as one of D-<NUM>, D-<NUM>, D-<NUM>, D-<NUM> and D-<NUM>). As shown, for the FDD spectrum, the uplink slots and the downlink slots are allocated on different frequencies/carriers.

In an aspect, uplink feedback corresponding to downlink transmissions (e.g., using the downlink slots of the TDD spectrum) may be transmitted on the FDD spectrum (e.g., using the uplink slots of the FDD spectrum). As noted above, the uplink feedback may use unutilized uplink slots of the FDD spectrum. The unutilized uplink slots may include uplink slots of the FDD spectrum on which no uplink data transmission is scheduled. This cross-spectrum uplink feedback is shown in <FIG> by arrows between the downlink slots of the TDD spectrum and the uplink slots of the FDD spectrum. In an aspect, the uplink feedback may include ACK/NACK feedback, measurement reports and other uplink control information (UCI) including sounding reference signals SRS.

In an aspect, the FDD and TDD spectrums may be assigned for communications using different Radio Access Technologies. For example, the FDD spectrum is assigned for LTE communication and the TDD spectrum is assigned for NR communication. In other aspects, both the FDD and TDD spectrums may be assigned for communication using the same RAT. For example, both the FDD and TDD spectrums may be assigned for NR communication. In an aspect, both the FDD and TDD spectrums may be assigned to a single network operator. In an aspect, the FDD and the TDD spectrums may be assigned to different network operators.

In certain aspects, in order to implement the cross-carrier (or cross spectrum) feedback, similar to the example illustrated in <FIG>, numerous limitations need to be addressed. These limitations may include limitations arising out of the RATs (e.g., NR/LTE) used for the spectrums and current standards agreements (e.g., 3GPP NR/LTE standards agreements) relating to the used RATs on these spectrums.

For example, in the context of carrier aggregation (CA) and supplementary uplink (SUL) the current 3GPP standards only support one PUCCH which cannot be dynamically switched between carriers. Further, in the context of CA, current 3GPP standards (e.g., NR standards) allow PUCCH to be configured only at the PCell.

Going back to the example of <FIG>, if the TDD spectrum is configured as PCell and the FDD spectrum is configured as SCell, PUCCH cannot be configured at the SCell of the FDD spectrum according to the current 3GPP specifications. Thus, UCI including ACK/NACK feedback for the downlink TDD transmissions on the TDD spectrum cannot be transmitted on PUCCH. Further, if no uplink data (e.g., PUSCH data) is scheduled at the SCell of the FDD spectrum, there is no way for the UE to transmit UCI corresponding to the PCell PDSCH of the TDD spectrum.

Alternatively, even if the FDD spectrum is configured as the PCell, there are limitations. For example, when the FDD spectrum has a considerably smaller bandwidth than the TDD spectrum and if the FDD spectrum is configured as the PCell, the scheduling overhead including overhead for scheduling SCell UL and/or DL traffic on the TDD spectrum may occupy a large portion of the bandwidth of the FDD spectrum. For example, if the TDD spectrum has a <NUM> bandwidth and the FDD spectrum has a <NUM> bandwidth, the scheduling overhead on the FDD spectrum for scheduling UL and/or DL traffic on the <NUM> TDD spectrum may occupy a large portion of the much smaller FDD spectrum. Additionally or alternatively, the FDD and TDD spectrums may support different slot lengths, and thus, transmitting scheduling information (e.g., DCI on PDCCH) on the FDD spectrum for scheduling UL and/or DL transmissions on the TDD spectrum may provide reduced flexibility. For example, if the FDD spectrum is assigned for LTE communications and the TDD spectrum is assigned for NR communications, the slot length of the LTE slots which may be <NUM> slots provide reduced flexibility for scheduling UL and/or DL transmissions on the NR slots which may be <NUM> slots.

In the context of supplementary uplink (SUL), even if PUCCH is configured as SUL on the FDD spectrum, there are certain limitations. For example, when the FDD spectrum has a considerably smaller bandwidth than the TDD spectrum and if PUCCH is configured as SUL on the FDD spectrum, the uplink feedback corresponding to the TDD DL transmissions may result in a large overhead as the TDD spectrum may have a large amount of downlink traffic owing to a much larger bandwidth.

Certain aspects of the present disclosure discuss techniques for better utilizing spectrum resources given the limitations of the current 3GPP standards. The discussed aspects include improved techniques for using underutilized or unutilized uplink resources of a spectrum for providing uplink feedback relating to downlink transmissions on a different spectrum. These improved techniques enable cross-spectrum feedback in the context of CA and SUL while overcoming one or more of the limitations of CA and SUL discussed above.

<FIG> illustrates example operations <NUM> that may be performed by a UE for transmitting cross-spectrum feedback, in accordance with certain aspects of the present disclosure.

Operations <NUM> begin, at <NUM>, by receiving DCI that schedules uplink resources on a SCell configured on a first spectrum, the scheduled uplink resources to be used for transmitting uplink feedback for at least one downlink transmission relating to at least one of a PCell or another SCell configured on a second spectrum, wherein a single PUCCH is allowed to be configured on one of the first or second spectrums and wherein once configured the PUCCH cannot be switched between the first and second spectrums.

At <NUM>, the UE transmits the uplink feedback using the scheduled uplink resources in the first spectrum.

<FIG> illustrates example operations <NUM> that may be performed by a Base station (BS) for scheduling cross-spectrum feedback, in accordance with certain aspects of the present disclosure.

Operations <NUM> begin, at <NUM>, by transmitting DCI that schedules uplink resources for a UE on a SCell configured on a first spectrum, the scheduled uplink resources to be used for transmitting uplink feedback for at least one downlink transmission by the BS relating to at least one of a primary cell PCell or another Scell configured on a second spectrum, wherein a single PUCCH is allowed to be configured on one of the first or second spectrums and wherein once configured the PUCCH cannot be switched between the first and second spectrums.

At <NUM>, the BS transmits the at least one downlink transmission in the second spectrum.

At <NUM>, the BS receives the uplink feedback from the UE using the scheduled uplink resources in the first spectrum.

In an aspect, first spectrum is an FDD spectrum and the scheduled uplink resources include resources configured for uplink FDD transmissions, and wherein second spectrum is a TDD spectrum and the downlink transmissions include downlink TDD transmissions scheduled on the second spectrum.

In an aspect, the DCI may be transmitted in the first spectrum or the second spectrum.

In certain aspects, in order to implement the cross-spectrum feedback, additional uplink feedback including (e.g., additional UCI not defined in current 3GPP standards) may be defined, for example, when a carrier/cell does not have configured PUCCH for transmission of uplink feedback. This additional UCI may include ACK/NACK feedback for providing feedback for DL transmissions on a different spectrum, measurement reports such as PCell measurement reports including interference measurements (based on Channel State Information (CSI)-Interference Measurement (IM)) and RSRP, RSRQ, and SNR measurements (based on CSI-RS or SSB). The additional UCI may further include uplink channel sounding (e.g., Aperiodic SRS) and positioning information (e.g., based on positioning reference signals, PRS).

In certain aspects, the additional UCI may be transmitted by the UE using DCI/PDCCH scheduled contention-free random access (CFRA). In the context of cross-spectrum feedback, this method may be used when PUCCH is not scheduled for the spectrum (e.g., FDD spectrum of <FIG>) to be used for the UCI feedback. For example, when the TDD spectrum is configured as PCell, PUCCH is not allowed to be configured on the FDD spectrum in accordance with the current 3GPP standards. In such a case, the uplink feedback may be transmitted using the additional UCI as discussed in aspects of the present disclosure. Generally, for CFRA, the BS schedules the transmission configuration of the CFRA procedure including time and frequency resources for each UE (UE-specific configuration) when the UE is in a connected mode, wherein the scheduled time and frequency resources are to be used by the UE for transmitting RACH messages to the BS. In an aspect, the scheduled time and frequency resources include uplink resources scheduled for transmitting a PUSCH payload of certain RACH messages to be transmitted by the UE. This ensures that the UE has dedicated resources for random access as compared to contention based random access when the UE randomly selects resources for transmitting a RACH preamble and the contention is resolved later. Thus, in an aspect, using the CFRA procedures for UCI feedback helps achieve the required latency requirements for communication between the BS and the UE.

In an aspect, a <NUM>-step CFRA procedure or a <NUM>-step CFRA procedure may be used for transmitting the UCI. When using the <NUM>-step CFRA procedure, a PUSCH payload portion of a first message (MSG-A) of the <NUM>-step CFRA procedure may be used to transmit the UCI. When using the <NUM>-step CFRA procedure, a PUSCH payload portion of a third message (MSG-<NUM>) of the <NUM>-step CFRA procedure may be used to transmit the UCI. As noted above, the PUSCH payloads of MSG-A and MSG-<NUM> are scheduled by DCI.

In an aspect, the <NUM>-step CFRA and the <NUM>-step CFRA have different latency performance in the context of transmitting the UCI. For example, since MSG-A is the first message of the <NUM>-step CFRA, the <NUM>-step CFRA has a better latency performance. In an aspect, one of the two CFRA procedures may be configured based on the latency requirement of the information to be included in the UCI. In an aspect, since the <NUM>-step CFRA has a better latency performance, the <NUM>-step CFRA using MSG-A PUSCH payload for transmitting UCI is preferable for low latency UCI report such as including ACK/CSI-IM (layer <NUM> environment). In an aspect, since the <NUM>-step CFRA using MSG-<NUM> for UCI transmission has a reduced latency performance, it is acceptable for transmission of UCI such as including RSRP/RSRQ/SNR (e.g., layer <NUM> environment) report that has a more relaxed latency requirement. Thus, in an aspect, the BS could schedule <NUM>-step or <NUM>-step CFRA based on the feedback UCI type. In an aspect, the <NUM>-step CFRA is configured for feedback with a stricter latency requirement such as including ACK/CSI-IM. In an aspect, the <NUM>-step or <NUM>-step CFRA may be configured for the feedback with a more relaxed latency requirement such as including RSRP/RSRQ/SNR.

As noted above, the uplink transmission configuration for the CFRA is user specific. Thus, the PDCCH used for scheduling the CFRA is in a user-specific search space. In an aspect, an identifier used for scrambling the cyclic redundancy check (CRC) can be UE specific or cell specific.

In an aspect, in order to guarantee the latency requirements (e.g. HARQ timeline, CSI measurement etc.) of communication between the BS and UE, the RACH Occasions (ROs) may be configured in different carriers of the same time position. This ensures alignment in the time domain to achieve the required latency by providing more flexibility in the frequency domain.

In certain aspects, the downlink grant included in the DCI/PDCCH for scheduling the CFRA may include several elements to facilitate the UCI feedback in the RACH messages. In an aspect, to facilitate ACK/NACK feedback to be included in the UCI, the DL grant includes one or more of a Downlink Assignment Index (DAI) to very the HARQ process, one or more HARQ process numbers corresponding to one or more HARQ processes for which feedback is to be included in the uplink feedback, information relating to time and frequency resources assigned to one or more RACH occasions (ROs) to be used for transmitting the uplink feedback, an indicator indicating whether transmitting the uplink feedback using the RACH procedure is enabled, indication of the SCell to be used for transmitting the uplink feedback, or configuration of a sounding reference signal (SRS) to be transmitted in the measurement report. In an aspect, multiple HARQ process numbers are included in the DL grant if ACK/NACKs corresponding to multiple HARQ processes are expected to be bundled in MSG-A/MSG-<NUM>. In an aspect, the time information corresponding to the ROs includes a parameter 'K1' that indicates the ACK/NACK slot number to be used.

In an aspect, to facilitate measurement report feedback to be included in the UCI, the DL grant includes configuration of reference signals including configuration for CSI-RS, Synchronization Signal Block (SSB), Positioning Reference Signals (PRS). In an aspect, one or more measurement reports based on one or more of these reference signals is included in the UCI feedback in MSG-A/MSG-<NUM>.

In an aspect, the DL grant further includes SRS configuration for SRS to be transmitted in the UCI feedback for use in UL measurements by the BS. Additionally or alternatively, MSG-A may be configured to be a short version which can allow A-SRS within one slot. This may lead to power savings as MSG-A is transmitted in one slot instead of multiple slots.

In an aspect, both single feedback and bundled feedback from a single UE may be supported for transmission feedback using the CFRA messages. For example, <NUM> bit ACK/NACK for a single HARQ process or multiple bits ACK/NACK for multiple HARQ processes may be supported in a single UL UCI transmission.

In an aspect, UE identifier (e.g. RNTI) may be transmitted in MSG-A/MSG-<NUM> to help BS to associate a received UCI feedback with transmitting UE and HARQ process or measurement request. In an aspect, the UE ID could be one or a combination of a sequence ID (configured by BS), a payload content and scrambling of MSG A/MSG <NUM> CRC.

In an aspect, group feedback may be supported in a single uplink feedback transmission in a PUSCH payload MSG-A/MSG-<NUM>. Further, a single UCI transmission can include feedback relating to cells of a single cell group or cells of multiple cell groups. For example, the UCI feedback can be for multiple carriers including Pcell and Scells in one cell group, or cells from different cell groups (e.g., Group <NUM> Pcell + Group <NUM> pcell/scell).

In accordance with current NR standards, if PUSCH is configured for a cell, UCI can be piggybacked on to the PUSCH resources. That is UCI can be transmitted using PUSCH resources. Thus, in an aspect, in the context of cross-spectrum scheduling, if at least one SCell is scheduled on a spectrum (e.g., FDD spectrum of <FIG>) to be used for uplink feedback of DL transmissions on a different spectrum (e.g., TDD spectrum), and if PUSCH is configured for the SCell, BS does not schedule the CFRA for UCI feedback as UCI this is already supported by PUSCH piggybacking. In this case, UCI feedback (e.g., including the additional UCI discussed above) can be transmitted piggybacked on the configured SCell PUSCH. In an aspect, the piggybacked UCI method may be used when PUCCH is configured as SUL. In this context, by transmitting the UCI piggybacked on PUSCH instead of transmitting on PUCCH, large feedback overheads may be avoided on the PUCCH. In the example of <FIG>, if PUCCH is configured as SUL on the FDD spectrum, the UCI is transmitted using PUSCH resources of the FDD spectrum instead of using the PUCCH resources of the FDD spectrum.

In certain aspects, when the UE does not have any data to transmit on the PUSCH, the entire PUSCH resources can be used to transmit the UCI. In this context, all frequencies and symbols configured for PUSCH are allocated for the UCI transmission. Current NR standards define a beta_offset when UCI transmission is piggybacked on PUSCH. The beta_offset is used by the UE to calculate how much resource in the PUSCH is to be used for UCI transmission. To enable the UCI to use the full PUSCH resource, a new beta_offset may be defined for this UCI only mode in order to enable the UE to use the entire PUSCH resource for the UCI transmission. In an aspect, a new indicator may be defined to indicate to the UE that a PUSCH is a UCI only PUSCH. Optionally, the CRC of the UCI feedback may be scrambled by a new RNTI.

In certain aspects, in order to randomize interference, the UCI (transmitted in the CFRA messages or piggybacked on PUSCH) may be scrambled. The UE ID can be UE specific or cell specific. The UE ID can be included in the PUSCH. A cell specific scrambling ID can be a function of C-RNTI, cell ID of PCell or carrier ID of cell group. A UE specific scrambling ID can be a function of a UE specific RNTI, cell ID of PCell, or carrier ID of cell group. In an aspect, the same scrambling ID or different scrambling IDs can be used for UCI and PUSCH.

In an aspect, if multiple carriers are configured, the BS selects one or more carriers for the UCI feedback in accordance with aspects discussed in this disclosure.

The method steps and/or actions may be interchanged with one another. In other words, unless a specific order of steps or actions is specified, the order and/or use of specific steps and/or actions may be modified.

Thus, reference to an element in the singular is not intended to mean "one and only one" unless specifically so stated, but rather "one or more.

For example, such a computer program product may comprise a computer-readable medium having instructions stored (and/or encoded) thereon, the instructions being executable by one or more processors to perform the operations described herein, for example, instructions for performing the operations described herein and illustrated in <FIG> and/or <FIG>.

Claim 1:
A method (<NUM>) for wireless communication by a User Equipment, UE, comprising:
receiving (<NUM>) downlink control information, DCI, scheduling uplink resources on a secondary cell, SCell, configured on a first spectrum, the scheduled uplink resources to be used for transmitting uplink feedback for at least one downlink transmission on at least one of a primary cell, PCell, or another SCell configured on a second spectrum, wherein a single physical uplink control channel, PUCCH, is allowed to be configured on one of the first or second spectrums and wherein once configured the PUCCH cannot be switched between the first and second spectrums; and
transmitting (<NUM>) the uplink feedback using the scheduled uplink resources in the first spectrum.