Patent Description:
This disclosure relates to aperiodic CSI-RS reception when it is overlapped in time with a Physical Downlink Shared Channel (PDSCH).

NR uses Cyclic Prefix Orthogonal Frequency Division Multiplexing (CP-OFDM) in both Downlink (DL) (i.e., from a network node, gNB, or base station, to a user equipment or UE) and Uplink (UL) (i.e., from UE to gNB). DFT spread OFDM is also supported in the uplink. In the time domain, NR downlink and uplink are organized into equally sized subframes of <NUM> each. A subframe is further divided into multiple slots of equal duration. The slot length depends on subcarrier spacing. For subcarrier spacing of Δf = <NUM>kHz, there is only one slot per subframe, and each slot consists of <NUM> OFDM symbols.

Data scheduling in NR is typically in slot basis, an example is shown in <FIG> with a <NUM>-symbol slot, where the first two symbols contain Physical Downlink Control Channel (PDCCH) and the rest contains physical shared data channel, either Physical Downlink Shared Channel (PDSCH) or Physical Uplink Shared Channel (PUSCH).

Different subcarrier spacing values are supported in NR. The supported subcarrier spacing values (also referred to as different numerologies) are given by Δf = (<NUM> × <NUM>µ) kHz where µ ∈ {<NUM>,<NUM>,<NUM>,<NUM>,<NUM>}. Δf = <NUM>kHz is the basic subcarrier spacing. The slot durations in millisecond at different subcarrier spacings are given by <MAT>.

In the frequency domain, a system bandwidth is divided into resource blocks (RBs); each corresponds to <NUM> contiguous subcarriers. The RBs are numbered starting with <NUM> from one end of the system bandwidth. The basic NR physical time-frequency resource grid is illustrated in <FIG>, where only one Resource Block (RB) within a <NUM>-symbol slot is shown. One OFDM subcarrier during one OFDM symbol interval forms one Resource Element (RE).

Downlink transmissions can be dynamically scheduled, i.e., in each slot the gNB transmits Downlink Control Information (DCI) over PDCCH about which UE data is to be transmitted to and which RBs and OFDM symbols in the current or future downlink slot the data is transmitted on. PDCCH is typically transmitted in the first few OFDM symbols in each slot in NR. The UE data are carried on PDSCH.

There are three DCI formats defined for scheduling PDSCH in NR, i.e., DCI format 1_0, DCI format 1_1, and DCI format 1_2. DCI format 1_0 has a smaller size than DCI 1_1 and can be used when a UE is not yet connected to the network while DCI format 1_1 can be used for scheduling MIMO (Multiple-Input-Multiple-Output) transmissions with up to <NUM> transport blocks (TBs). DCI format 1_2 is introduced in NR Release <NUM> (Rel-<NUM>) to support configurable size for certain bit fields in the DCI.

One or more of the following bit fields may be included in a DCI: Frequency Domain Resource Assignment (FDRA); Time Domain Resource Assignment (TDRA); Modulation and Coding Scheme (MCS); New data indicator (NDI); Redundancy Version (RV); HARQ process number; PUCCH Resource Indicator (PRI); PDSCH-to-HARQ_feedback timing indicator (K1); Antenna port(s); and Transmission Configuration Indication (TCI).

A UE first detects and decodes PDCCH and if the decoding is successful, it then decodes the corresponding PDSCH based on the decoded DCI carried in the PDCCH. The PDSCH decoding status is sent back to the gNB in the form of HARQ Acknowledgment or HARQ-ACK in a PUCCH resource indicated by the PRI. An example is illustrated in <FIG>. The time offset, T1, between the reception of the DL DCI and the corresponding PDSCH is determined by a slot offset and starting symbol of the PDSCH indicated in the TDRA in the DCI. The time offset, T2, between the reception of the DL DCI and the corresponding HARQ ACK is provided by the PDSCH-to-HARQ_feedback timing indicator in the DCI.

When the UE is scheduled to receive PDSCH by a DCI, the Time domain resource (TDRA) assignment field value m of the DCI provides a row index m + <NUM> to a time domain resource allocation table. When a DCI is detected in a UE specific search space, the PDSCH time domain resource allocation is according to an RRC configured TDRA list by an RRC parameter pdsch-TimeDomainAllocationList provided in a UE specific PDSCH configuration, pdsch-Config. Each TDRA entry in the TDRA list defines a slot offset K<NUM> between the PDSCH and the PDCCH scheduling the PDSCH, a start and length indicator SLIV, the PDSCH mapping type (either Type A or Type B) to be assumed in the PDSCH reception, and optionally a repetition number RepNumR16.

Demodulation Reference Signals (DM-RS) are used for coherent demodulation of PDSCH. The DM-RS is confined to resource blocks carrying the associated PDSCH and is mapped on allocated Resource Elements (REs) of the OFDM time-frequency grid in NR such that the receiver can efficiently handle time/frequency-selective fading radio channels. A PDSCH can have one or multiple DMRS, each associated with an antenna port. The antenna ports used for PDSCH are indicated in DCI scheduling the PDSCH.

Several signals can be transmitted from different co-located antenna ports. These signals can have the same large-scale properties, for instance in terms of Doppler shift/spread, average delay spread, average delay, or direction of arrival when measured at the receiver. These antenna ports are then said to be Quasi Co-Located (QCL). The network can then signal to the UE that two antenna ports are QCL. If the UE knows that two antenna ports are QCL with respect to a certain parameter (e.g., Doppler spread), the UE can estimate that parameter based on a reference signal transmitted on one of the antenna ports and use that estimate when receiving another reference signal or physical channel on the other antenna port. Typically, the first antenna port is represented by a measurement reference signal (known as a source RS) such as channel state information reference signal (CSI-RS) and the second antenna port is a DMRS (known as a target RS) for PDSCH reception.

In NR, a QCL relationship between a demodulation reference signal (DMRS) in PDSCH and other reference signals is described by a Transmission Configuration Indicator (TCI) state. A UE can be configured through radio resource control (RRC) signaling with up to <NUM> TCI states in NR Frequency Range <NUM> (FR2) and up to eight TCI states in NR Frequency Range (FR1), depending on UE capability. Each TCI state contains QCL information, for the purpose of PDSCH reception. A UE can be dynamically signaled one or two TCI states in the TCI field in a DCI scheduling a PDSCH.

A QCL relationship between a DMRS in PDCCH and other reference signals is described by a TCI state of a Control Resource Set (CORESET) over which the PDCCH is transmitted. For each CORESET configured to a UE, a list of TCI states is RRC configured; one of them is activated by a MAC CE. In NR Rel-<NUM>, up to three CORESETs per Bandwidth Part (BWP) can be configured for a UE. In NR Rel-<NUM>, up to five CORESETs per BWP may be configured to a UE, depending on capability.

There currently exist certain challenges. The existing NR standard defines the UE behavior when Aperiodic CSI-RS collides with PDSCH when the PDSCH is indicated with a single TCI state. However, UE behavior in other situations when Aperiodic CSI-RS collides with PDSCH are not defined. Therefore, improvements for handling collisions are needed.

<CIT> describes QCL assumptions for AP CSI-RS in NR communications systems. A UE determines a QCL relationship of an AP CSI-RS to a physical channel and processes the AP CSI-RS according to the determined QCL relationship.

<CIT> describes a technique for beam indication in next generation wireless systems. A method of a UE for a beam indication in a wireless communication system includes receiving, from a BS, DCI including scheduling information for a data transmission on a downlink data channel, wherein the DCI includes an index of a spatial QCL configuration, comparing a time offset between the data transmission and the DCI with a threshold that is pre-configured at the UE, and calculating a receive beam based on the index of the spatial QCL configuration or a pre-configured spatial QCL assumption, receiving the data transmission based on the time offset.

<CIT> describes a technique for beam management in a wireless network. A wireless transmit/receive unit (WTRU) may monitor CORESETs to receive a PDCCH having DCI that includes a scheduling offset and an indicated beam for a scheduled PDSCH reception. When the scheduling offset of the scheduled PDSCH is less than a threshold, a default beam of a TCI state may be utilized to receive the scheduled PDSCH. When the scheduling offset of the scheduled PDSCH is more than a threshold, the indicated beam is utilized to receive the scheduled PDSCH on a condition that a measured quality is above a measurement threshold or the default beam may be utilized when the measured quality is below the measurement threshold.

<NPL>, discusses a QCL Type D conflict between PDSCH and CSI-RS in FR2. An expected UE behavior when a UE is configured or aperiodically assigned a CSI-RS for CSI or TRS in the same OFDM symbol as a potential or actual PDSCH allocation is not specified. This places limitations on CSI-RS scheduling in Rel-<NUM> e.g. such a UE cannot be scheduled with CSI-RS for CSI with a non-active TCI state or a TRS without a QCL Type-D assumption in Rel-<NUM>.

The invention is defined and limited by the appended set of independent claims. Further embodiments are provided by the appended set of dependent claims.

Certain embodiments may provide one or more of the following technical advantage(s). The proposed solution defines the UE behavior (i.e., what QCL assumptions the UE makes) to receive Aperiodic CSI-RS when Aperiodic CSI-RS collides with PDSCH when the PDSCH is indicated with two TCI states. One benefit is that the proposed solution defines with which QCL properties the colliding Aperiodic CSI-RS should be received which is previously not defined in NR. With the proposed solution Aperiodic CSI-RS can be flexibly triggered in overlapping symbols with PDSCH scheduled according to one of single-PDCCH based NC-JT scheme "FDMSchemeA", "FDMSchemeB", and "TDMSchemeA".

Core Network Node: As used herein, a "core network node" is any type of node in a core network or any node that implements a core network function. Some examples of a core network node include, e.g., a Mobility Management Entity (MME), a Packet Data Network Gateway (P-GW), a Service Capability Exposure Function (SCEF), a Home Subscriber Server (HSS), or the like. Some other examples of a core network node include a node implementing an Access and Mobility Management Function (AMF), a User Plane Function (UPF), a Session Management Function (SMF), an Authentication Server Function (AUSF), a Network Slice Selection Function (NSSF), a Network Exposure Function (NEF), a Network Function (NF) Repository Function (NRF), a Policy Control Function (PCF), a Unified Data Management (UDM), or the like.

<FIG> illustrates one example of a cellular communications system <NUM> in which embodiments of the present disclosure may be implemented. In the embodiments described herein, the cellular communications system <NUM> is a <NUM> System (5GS) including a NR RAN or LTE RAN (i.e., Evolved Universal Terrestrial Radio Access (E-UTRA) RAN). In this example, the RAN includes base stations <NUM>-<NUM> and <NUM>-<NUM>, which in <NUM> NR are referred to as gNBs (e.g., LTE RAN nodes connected to <NUM> Core (5GC), which are referred to as gn-eNBs), controlling corresponding (macro) cells <NUM>-<NUM> and <NUM>-<NUM>. The base stations <NUM>-<NUM> and <NUM>-<NUM> are generally referred to herein collectively as base stations <NUM> and individually as base station <NUM>. Likewise, the (macro) cells <NUM>-<NUM> and <NUM>-<NUM> are generally referred to herein collectively as (macro) cells <NUM> and individually as (macro) cell <NUM>. The RAN may also include a number of low power nodes <NUM>-<NUM> through <NUM>-<NUM> controlling corresponding small cells <NUM>-<NUM> through <NUM>-<NUM>. The low power nodes <NUM>-<NUM> through <NUM>-<NUM> can be small base stations (such as pico or femto base stations) or Remote Radio Heads (RRHs), or the like. Notably, while not illustrated, one or more of the small cells <NUM>-<NUM> through <NUM>-<NUM> may alternatively be provided by the base stations <NUM>. The low power nodes <NUM>-<NUM> through <NUM>-<NUM> are generally referred to herein collectively as low power nodes <NUM> and individually as low power node <NUM>. Likewise, the small cells <NUM>-<NUM> through <NUM>-<NUM> are generally referred to herein collectively as small cells <NUM> and individually as small cell <NUM>. The cellular communications system <NUM> also includes a core network <NUM>, which in the 5GS is referred to as the <NUM> Core (5GC). The base stations <NUM> (and optionally the low power nodes <NUM>) are connected to the core network <NUM>.

Downlink transmissions can be dynamically scheduled, i.e., in each slot the gNB transmits Downlink Control Information (DCI) over PDCCH about which UE data is to be transmitted to and which RBs and OFDM symbols in the current downlink slot the data is transmitted on. PDCCH is typically transmitted in the first few OFDM symbols in each slot in NR. The UE data are carried on PDSCH.

There are three DCI formats defined for scheduling PDSCH in NR, i.e., DCI format 1_0, DCI format 1_1, and DCI format 1_2. DCI format 1_0 has a smaller size than DCI 1_1 and can be used when a UE is not connected to the network while DCI format 1_1 can be used for scheduling MIMO (Multiple-Input-Multiple-Output) transmissions with up to <NUM> transport blocks (TBs). DCI format 1_2 is introduced in NR Release <NUM> (Rel-<NUM>) to support configurable size for certain bit fields in the DCI.

A UE first detects and decodes PDCCH and if the decoding is successful, it then decodes the corresponding PDSCH based on the decoded DCI carried in the PDCCH. The PDSCH decoding status is sent back to the gNB in the form of HARQ Acknowledgment in a PUCCH resource indicated by PRI. An example is illustrated in <FIG>. The time offset, T1, between the reception of the DL DCI and the corresponding PDSCH determined by a slot offset and starting symbol of the PDSCH indicated in TDRA in the DCI. The time offset, T2, between the reception of the DL DCI and the corresponding HARQ ACK is provided by the PDSCH-to-HARQ_feedback timing indicator in the DCI.

When the UE is scheduled to receive PDSCH by a DCI, the Time domain resource (TDRA) assignment field value m of the DCI provides a row index m + <NUM> to a time domain resource allocation table. When a DCI is detected, the PDSCH time domain resource allocation is according to an RRC configured TDRA list by an RRC parameter pdsch-TimeDomainAllocationList provided in a UE specific PDSCH configuration, pdsch-Config. Each TDRA entry in the TDRA list defines a slot offset K<NUM> between the PDSCH and the PDCCH scheduling the PDSCH, a start and length indicator SLIV, the PDSCH mapping type (either Type A or Type B) to be assumed in the PDSCH reception, and optionally a repetition number RepNumR16.

Several signals can be transmitted from different antenna ports in a same location. These signals can have the same large-scale properties, for instance in terms of Doppler shift/spread, average delay spread, or average delay, when measured at the receiver. These antenna ports are then said to be Quasi Co-Located (QCL). The network can then signal to the UE that two antenna ports are QCL. If the UE knows that two antenna ports are QCL with respect to a certain parameter (e.g., Doppler spread), the UE can estimate that parameter based on a reference signal transmitted one of the antenna ports and use that estimate when receiving another reference signal or physical channel the other antenna port. Typically, the first antenna port is represented by a measurement reference signal such as channel state information reference signal (CSI-RS) (known as a source RS) and the second antenna port is a DMRS (known as a target RS) for PDSCH reception.

In NR, a QCL relationship between a demodulation reference signal (DMRS) in PDSCH and other reference signals is described by a TCI state. A UE can be configured through RRC signaling with up to <NUM> TCI states in Frequency Range <NUM> (FR2) and up to eight TCI states in FR1, depending on UE capability. Each TCI state contains QCL information, for the purpose of PDSCH reception. A UE can be dynamically signaled one or two TCI states in the TCI field in a DCI scheduling a PDSCH.

In one scenario, downlink data are transmitted over multiple TRPs in which different MIMO layers are transmitted over different TRPs. This is referred to a Non-coherent Joint Transmission (NC-JT). In another scenario, different time/frequency resources may be allocated to different TRPs and one or multiple PDSCH is transmitted over different TRPs. Two ways of scheduling multi-TRP transmission are specified in NR Rel-<NUM>: multi-PDCCH based multi-TRP transmission and single-PDCCH based multi-TRP transmission. The multi-PDCCH based multi-TRP transmission and single-PDCCH based multi-TRP transmission can be used to serve downlink eMBB traffic as well as downlink URLLC traffic to the UE.

An example is shown in <FIG>, where data are sent to a UE over two TRPs, each TRP carrying one TB mapped to one code word. When the UE has four receive antennas while each of the TRPs has only two transmit antennas, the UE can support up to four MIMO layers, but each TRP can maximally transmit two MIMO layers. In this case, by transmitting data over two TRPs to the UE, the peak data rate to the UE can be increased as up to four aggregated layers from the two TRPs can be used. This is beneficial when the traffic load and thus the resource utilization, is low in each TRP. In this example, a single scheduler is used to schedule data over the two TRPs. One PDCCH is transmitted from each of the two TRPs in a slot, each schedule one PDSCH. This is referred to as a multi-PDCCH or multi-DCI scheme in which a UE receives two PDCCHs and the associated two PDSCHs in a slot from two TRPs.

In NR specification 3GPP TS <NUM>, there is a restriction stating:
"The UE may assume that the PDSCH DM-RS within the same CDM group are quasi co-located with respect to Doppler shift, Doppler spread, average delay, delay spread, and spatial Rx.

In cases where a UE is not scheduled with all DMRS ports within a CDM group, there may be another UE simultaneously scheduled, using the remaining ports of that CDM group. The UE can then estimate the channel for that other UE (thus an interfering signal) in order to perform coherent interference suppression. Hence, this is useful in MU-MIMO scheduling and UE interference suppression.

In case of a multi-TRP scenario, in which the UE receives PDSCHs via multiple PDCCHs transmitted from different TRPs, the signals transmitted from different TRPs will most likely not be quasi-collocated as the TRPs may be spatially separated. In this case, the PDSCHs transmitted from different TRPs will have different TCI states associated with them. Furthermore, according to the above restriction from 3GPP TS <NUM>, two PDSCH DM-RSs associated with two TRPs will have to belong to different DM-RS CDM groups (as the two PDSCH DM-RSs are not QCL, they cannot belong to the same DM-RS CDM group). <FIG> illustrates an example relationship between TCI states and DM-RS CDM groups for a multiple-PDCCH multi-TRP scenario. In the example, PDSCH1 is associated with TCI State p, and PDSCH <NUM> is associated with TCI state q. The PDSCH DM-RSs from the different TRPs also belong to different DM-RS CDM groups as they are not quasi-collocated. In the example, the DMRS for PDSCH1 belongs to CDM group u while the DMRS for PDSCH2 belongs to CDM group v.

A PDSCH may be transmitted to a UE from multiple TRPs. Since different TRPs may be located in different physical locations and/or have different beams, the propagation channels can be different. To facilitate receiving PDSCH data from different TRPs or beams, a UE may be indicated with two TCI states, each associated with a TRP or a beam, by a single codepoint of a TCI field in a DCI.

One example of PDSCH transmission over two TRPs using a single DCI is shown in <FIG>, where different layers of a PDSCH with a single codeword (e.g., CW0) are sent over two TRPs, each associated with a different TCI state. In this case, two DMRS ports, one for each layer, in two CDM groups are also signaled to the UE. A first TCI state is associated with the DMRS port in a first CDM group, and a second TCI state is associated with the DMRS port in a second CDM group. This approach is often referred to as NC-JT (Non-coherent joint transmission) or scheme 1a in NR Rel-<NUM>3GPP discussions.

Transmitting PDSCH over multiple TRPs can also be used to improve PDSCH transmission reliability for URLLC applications. A number of approaches are introduced in NR Rel-<NUM> including "FDMSchemeA", "FDMSchemeB", "TDMSchemeA" and Slot based TDM scheme. Note that the terminology Scheme <NUM> is used in the discussions involving Slot based TDM scheme in NR Rel-<NUM>3GPP discussions.

An example of multi-TRP PDSCH transmission with FDMSchemeA is shown in <FIG>, where a PDSCH is sent over TRP1 in PRGs (precoding RB group) {<NUM>,<NUM>,<NUM>} and over TRP2 in PRGs {<NUM>,<NUM>,<NUM>}. The transmission from TRP1 is associated with TCI state <NUM>, while the transmission from TRP2 is associated with TCI state <NUM>. Since the transmissions from TRP1 and TRP2 are non-overlapping in the case of FDMSchemeA, the DMRS ports can be the same (i.e., DMRS port <NUM> used for both transmissions). The PDSCH is scheduled by a PDCCH which is sent over TRP1.

<FIG> shows an example data transmission with FDMSchemeB in which PDSCH#<NUM> is transmitted in PRGs {<NUM>, <NUM>, <NUM>} from TRP1 and PDSCH#<NUM> with the same TB is transmitted in PRGs {<NUM>, <NUM>, <NUM>} from TRP2. The transmission from TRP1 is associated with TCI state <NUM>, while the transmission from TRP2 is associated with TCI state <NUM>. Since the transmissions from TRP1 and TRP2 are non-overlapping in the case of FDMSchemeB, the DMRS ports can be the same (i.e., DMRS port <NUM> used for both transmissions). The two PDSCHs carry the same encoded data payload but with a same or different redundancy version so that the UE can do soft combining of the two PDSCHs to achieve more reliable reception.

<FIG> shows an example data transmission with TDMSchemeA in which PDSCH repetition occurs in mini-slots of four OFDM symbols within a slot. Each PDSCH can be associated with a same or different RV. The transmission of PDSCH#<NUM> from TRP1 is associated with a first TCI state, while the transmission of PDSCH#<NUM> from TRP2 is associated with a second TCI state.

An example Multi-TRP data transmission with Slot based TDM scheme is shown in <FIG>, where four PDSCHs for a same TB are transmitted over two TRPs and in four consecutive slots. Each PDSCH is associated with a different RV. The transmission of odd numbered PDSCHs from TRP1 are associated with a first TCI state, while the transmission of even numbered PDSCHs from TRP2 is associated with a second TCI state.

For all the single-PDCCH based DL multi-TRP PDSCH schemes, a single DCI transmitted from one TRP is used to schedule multiple PDSCH transmissions over two TRPs. The network configures the UE with multiple TCI states via RRC, and a new MAC CE was introduced in NR Rel-<NUM>. This MAC CE can be used to map a codepoint in the TCI field to one or two TCI states.

If no TCI codepoints are mapped to two different TCI states and the time offset between the reception of a DL DCI and the corresponding PDSCH is less than a threshold timeDurationForQCL configured by higher layers, instead of using the TCI state indicated in the TCI field in DCI scheduling a PDSCH, the UE may assume that the TCI state for the PDSCH is given by the TCI state activated for a CORESET with the lowest ControlResourceSetId among one or more CORESETs in the latest slot in an active BWP of a serving cell monitored by the UE. The TCI state is referred here as the default TCI state. If none of configured TCI states for the serving cell of scheduled PDSCH contains 'QCL-TypeD', the UE shall obtain the other QCL assumptions from the TCI states indicated by DCI for its scheduled PDSCH irrespective of the time offset between the reception of the DL DCI and the corresponding PDSCH.

If the offset between the reception of the DL DCI and the corresponding PDSCH is less than the threshold timeDurationForQCL and at least one configured TCI states for the serving cell of scheduled PDSCH contains the 'QCL-TypeD', and at least one TCI codepoint is configured with two TCI states, the UE may assume that the TCI states for the PDSCH are given by the TCI states corresponding to the lowest codepoint among the TCI codepoints containing two different TCI states. In this case, the two TCI states are the default TCI states.

A default TCI state corresponds to a Rx beam used by the UE to receive (and buffer) a PDSCH before the corresponding DCI is decoded (because before DCI decoding, UE doesn't know what TCI state(s) is needed for receive the PDSCH. Otherwise, a wrong Rx beam could be used and the PDSCH could be lost if the time offset between the DCI and the PDSCH, which is unknown before the DCI is decoded, is below the threshold.

For CSI measurement and feedback, CSI-RSs are defined. A CSI-RS is transmitted on each transmit antenna (or antenna port) and is used by a UE to measure downlink channel between each of the transmit antenna ports and each receive antenna. The antenna ports are also referred to as CSI-RS ports. The supported numbers of antenna ports in NR are {<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>}. By measuring the received CSI-RS, a UE can estimate the channel that the CSI-RS is traversing, including the radio propagation channel and antenna gains. The CSI-RS for the above purpose is also referred to as Non-Zero Power (NZP) CSI-RS.

NZP CSI-RS can be configured to be transmitted in certain REs in a slot and certain slots. <FIG> shows an example of CSI-RS REs for <NUM> antenna ports, where 1RE per RB per port is shown.

In addition, CSI Interference Measurement resource (CSI-IM) is also defined in NR for a UE to measure interference. A CSI-IM resource contains four REs, either four adjacent RE in frequency in the same OFDM symbol or two by two adjacent REs in both time and frequency in a slot. By measuring both the channel based on NZP CSI-RS and the interference based on CSI-IM, a UE can estimate the effective channel and noise plus interference to determine the CSI, i.e., rank, precoding matrix, and the channel quality.

In NR, the CSI-RS can be aperiodic CSI-RS, semi-persistent CSI-RS, and periodic CSI-RS. Aperiodic CSI-RS transmission is typically triggered by a UL DCI (i.e., DCI format 0_1 and DCI format 0_2).

In NR, a UE can be configured with multiple CSI reporting settings (each represented by a higher layer parameter CSI-ReportConfig with an associated identity ReportConfigID) and multiple CSI resource settings (each represented by a higher layer parameter CSI-ResourceConfig with an associated identity CSI-ResourceConfigId). Each CSI resource setting can contain multiple CSI resource sets (each represented by a higher layer parameter NZP-CSI-RS-ResourceSet with an associated identity NZP-CSI-RS-ResourceSetld for channel measurement or by a higher layer parameter CSI-IM-ResourceSet with an associated identity CSI-IM-ResourceSetld for interference measurement), and each NZP CSI-RS resource set for channel measurement can contain up to eight NZP CSI-RS resources. For each CSI reporting setting, a UE feeds back a set of CSI, which may include one or more of a CSI-RS Resource Indicator (CRI), a RI, a PMI, and a CQI per CW, depending on the configured report quantity.

In each CSI reporting setting, it contains one or more of the following information:.

For periodic and semi-static CSI reporting, only one NZP CSI-RS resource set can be configured for channel measurement and one CSI-IM resource set for interference measurement. For aperiodic CSI reporting, a CSI resource setting for channel measurement can contain more than one NZP CSI-RS resource set for channel measurement. If the CSI resource setting for channel measurement contains multiple NZP CSI-RS resource sets for aperiodic CSI report, only one NZP CSI-RS resource set can be selected and indicated to a UE. For aperiodic CSI reporting, a list of trigger states (given by the higher layer parameters CSI-AperiodicTriggerStateList). Each trigger state in CSI-AperiodicTriggerStateList contains a list of associated CSI-ReportConfigs indicating the Resource Set IDs for channel and optionally for interference. For a UE configured with the higher layer parameter CSI-AperiodicTriggerStateList, if a Resource Setting linked to a CSI-ReportConfig has multiple aperiodic resource sets, only one of the aperiodic CSI-RS resource sets from the Resource Setting is associated with the trigger state, and the UE is higher layer configured per trigger state per Resource Setting to select the one NZP CSI-RS resource set from the Resource Setting.

When more than one NZP CSI-RS resources are contained in the selected NZP CSI-RS resource set for channel measurement, a CSI-RS Resource Indicator (CRI) is reported by the UE to indicate to the gNB about the one selected NZP CSI-RS resource in the resource set, together with RI, PMI and CQI associated with the selected NZP CSI-RS resource. This type of CSI assumes that a PDSCH is transmitted from a single Transmission Reception Point (TRP) and the CSI is also referred to as single TRP CSI.

The following UE behavior is specified in existing NR specifications in TS <NUM> when it comes to Aperiodic CSI-RS colliding with PDSCH:
If the scheduling offset between the last symbol of the PDCCH carrying the triggering DCI and the first symbol of the aperiodic CSI-RS resources is smaller than the UE reported threshold beamSwitchTiming as defined in [TS <NUM>]:.

There currently exist certain challenges. The existing NR standard defines the UE behavior when Aperiodic CSI-RS collides with PDSCH when the PDSCH is indicated with a single TCI state. How the UE behaves (i.e., what QCL assumptions the UE makes) to receive Aperiodic CSI-RS when Aperiodic CSI-RS collides with PDSCH(s) that are indicated with two TCI states in DCI is not defined in current NR specification, which is an open problem that needs to be solved. Specifically, this UE behavior when PDSCH uses one of the following schemes is not defined: single-PDCCH based NC-JT scheme; "FDMSchemeA"; " FDMSchemeB"; "TDMSchemeA".

Systems and methods for determining Transmission Configuration Indication (TCI) states for Aperiodic (AP) Channel State Information Reference Signals (CSI-RSs) overlapping with Physical Downlink Shared Channel (PDSCH) transmission are provided. In some embodiments, a method performed by a wireless device for determining TCI states for receiving one or more AP CSI-RSs includes one or more of: receiving one or more AP CSI-RSs in the same symbol(s) as downlink transmission(s) scheduled by a DCI with two TCI states indicated in DCI; receiving triggering of the one or more AP CSI-RS with scheduling offset between the last symbol of the PDCCH carrying the triggering DCI and the first symbol of the AP CSI-RS resources, where the scheduling offset is smaller than a wireless device reported threshold; and determining that the downlink transmission is scheduled according to one of the group consisting of: "TDMSchemeA"; "FDMSchemeA"; "FDMSchemeB"; and a scheme where different sets of layers of the downlink transmission are received with different TCI states. In some embodiments, depending on circumstances, the wireless device applies a QCL assumption for a PDSCH transmission occasion when receiving the AP CSI-RS.

<FIG> illustrates a method performed by a wireless device for determining TCI states for receiving one or more AP CSI-RSs. In some embodiments, the wireless device performs one or more of: receiving one or more AP CSI-RSs in the same symbol(s) as downlink transmission(s) scheduled by a DCI with two TCI states indicated in DCI (step <NUM>); receiving triggering of the one or more AP CSI-RS with scheduling offset between the last symbol of the PDCCH carrying the triggering DCI and the first symbol of the AP CSI-RS resources, where the scheduling offset is smaller than a wireless device reported threshold (step <NUM>); and determining that the downlink transmission is scheduled according to one of the group consisting of: "TDMSchemeA"; "FDMSchemeA"; "FDMSchemeB"; and a scheme where different sets of layers of the downlink transmission are received with different TCI states (step <NUM>). In some embodiments, depending on circumstances, the wireless device applies a QCL assumption for a PDSCH transmission occasion when receiving the AP CSI-RS (step <NUM>). In some embodiments, this defines the UE behavior (i.e., what QCL assumptions the UE makes) to receive Aperiodic CSI-RS when Aperiodic CSI-RS collides with PDSCH when the PDSCH is indicated with two TCI states. One benefit is that the proposed solution defines with which QCL properties the colliding Aperiodic CSI-RS should be received which is previously not defined in NR. With the proposed solution Aperiodic CSI-RS can be flexibly triggered in overlapping symbols with PDSCH scheduled according to one of single-PDCCH based NC-JT scheme "FDMSchemeA", "FDMSchemeB", and "TDMSchemeA".

<FIG> illustrates a method performed by a base station for indicating TCI states for receiving one or more AP CSI-RSs. In some embodiments, the base station performs one or more of: transmitting, to a wireless device, one or more AP CSI-RSs in the same symbol(s) as downlink transmission(s) scheduled by a DCI with two TCI states indicated in DCI (step <NUM>); triggering one or more AP CSI-RS with scheduling offset between the last symbol of the PDCCH carrying the triggering DCI and the first symbol of the AP CSI-RS resources, where the scheduling offset is smaller than a wireless device reported threshold (step <NUM>); and scheduling the downlink transmission according to one of the group consisting of: "TDMSchemeA"; "FDMSchemeA"; "FDMSchemeB"; and a scheme where different sets of layers of the downlink transmission are received with different TCI states (step <NUM>). In some embodiments, depending on circumstances, the base station assumes the wireless device applies a QCL assumption for a PDSCH transmission occasion when receiving the AP CSI-RS (step <NUM>). In some embodiments, this defines the UE behavior (i.e., what QCL assumptions the UE makes) to receive Aperiodic CSI-RS when Aperiodic CSI-RS collides with PDSCH when the PDSCH is indicated with two TCI states. One benefit is that the proposed solution defines with which QCL properties the colliding Aperiodic CSI-RS should be received which is previously not defined in NR. With the proposed solution Aperiodic CSI-RS can be flexibly triggered in overlapping symbols with PDSCH scheduled according to one of single-PDCCH based NC-JT scheme "FDMSchemeA", "FDMSchemeB", and "TDMSchemeA".

Embodiment <NUM> for scenario when AP CSI-RS collides with PDSCH scheduled according to "TDMSchemeA" and scheduling offset above a threshold.

In this embodiment, a UE is configured to receive PDSCH according to "TDMSchemeA"and is indicated with two TCI states in a DCI where the <NUM>st indicated TCI state is applied to PDSCH transmission occasion <NUM> (denoted as PDSCH1) and the <NUM>nd indicated TCI state is applied to PDSCH transmission occasion <NUM> (denoted as PDSCH2). This corresponds to the case where the scheduling offset from the last symbol of the PDCCH carrying the DCI to the first symbol of PDSCH1 is larger than or equal to the threshold timeDurationForQCL.

Furthermore, in this embodiment, an aperiodic CSI-RS (AP CSI-RS) is triggered to the UE by another DCI with scheduling offset between the last symbol of the PDCCH carrying the triggering DCI (i.e., the DCI that triggers the AP CSI-RS) and the first symbol of the aperiodic CSI-RS resources is smaller than the UE reported threshold beamSwitchTiming. In this case, there are two possibilities as shown in <FIG> which illustrates a first example of Embodiment <NUM> considering AP CSI-RS collision with PDSCH scheduled according to "TDMSchemeA".

As shown in <FIG>, when AP CSI-RS is in the same symbols as PDSCH1, the UE applies the QCL assumption of PDSCH1 (given by the <NUM>st indicated TCI state in DCI) when receiving the AP CSI-RS. Stated in other words, the UE receives the AP CSI-RS using the same receive beam as the one used to receive PDSCH1 whose spatial QCL properties are given by the <NUM>st indicated TCI state in DCI.

As shown in <FIG>, when AP CSI-RS is in the same symbols as PDSCH2, the UE applies the QCL assumption of PDSCH2 (given by the <NUM>nd indicated TCI state in DCI) when receiving the AP CSI-RS. Stated in other words, the UE receives the AP CSI-RS using the same receive beam as the one used to receive PDSCH2 whose spatial QCL properties are given by the <NUM>nd indicated TCI state in DCI.

There is also a third possibility as shown in <FIG> which illustrates a second example of Embodiment <NUM> considering AP CSI-RS collision with PDSCH scheduled according to "TDMSchemeA". As shown in the figure, in this third possibility, AP CSI-RS overlaps with the symbols of both PDSCH1 and PDSCH2. In this case, as CSI-RS of a single AP CSI-RS resource is transmitted from one TRP, it is not possible to receive CSI-RS of a single AP CSI-RS resource using two different QCL assumptions, the UE considers this as an error case and drops the AP CSI-RS (i.e., does not receive the AP CSI-RS).

Embodiment <NUM> for scenario when AP CSI-RS collides with PDSCH scheduled according to "TDMSchemeA" and one scheduling offset below a threshold.

In this embodiment, a UE is configured to receive PDSCH according to "TDMSchemeA"and is indicated with <NUM> TCI states in the DCI. In this case, the scheduling offset from the last symbol of the PDCCH to the first symbol of PDSCH1 is smaller than the threshold timeDurationForQCL but the scheduling offset from the last symbol of the PDCCH to the first symbol of PDSCH2 is larger than or equal to the threshold. In this case, the <NUM>st default TCI state is applied to PDSCH1 and the <NUM>nd indicated TCI state is applied to PDSCH2. The default TCI states for the PDSCH are given by the TCI states corresponding to the lowest codepoint among the TCI codepoints containing two different TCI states, according to the NR Rel-<NUM> specification. Hence, <NUM>st default TCI state is defined as the first of the two different TCI states corresponding to the lowest such codepoint.

Furthermore, in this embodiment, an aperiodic CSI-RS (AP CSI-RS) is triggered to the UE by another DCI with scheduling offset between the last symbol of the PDCCH carrying the triggering DCI and the first symbol of the aperiodic CSI-RS resources is smaller than a threshold such as the UE reported threshold beamSwitchTiming. In this case, there are two possibilities as shown in <FIG> which illustrates a first example of Embodiment <NUM> considering AP CSI-RS collision with PDSCH scheduled according to "TDMSchemeA".

As shown in <FIG>, when AP CSI-RS is in the same symbols as PDSCH1, the UE applies the QCL assumption of PDSCH1 (given by the <NUM>st default TCI state) when receiving the AP CSI-RS. Stated in other words, the UE receives the AP CSI-RS using the same receive beam as the one used to receive PDSCH1 whose spatial QCL properties are given by the <NUM>st default TCI state.

There is also a third possibility as shown in <FIG> which illustrates a second example of Embodiment <NUM> considering AP CSI-RS collision with PDSCH scheduled according to "TDMSchemeA". As shown in the figure, in this third possibility, AP CSI-RS overlaps between the symbols of both PDSCH1 and PDSCH2. In this case, as it is not possible to receive different CSI-RS of a single AP CSI-RS resource using two different QCL assumptions, the UE drops the AP CSI-RS (i.e., does not receive the AP CSI-RS).

Embodiment <NUM> for scenario when AP CSI-RS collides with PDSCH scheduled according to "TDMSchemeA" and both scheduling offsets below a threshold.

In this embodiment, a UE is configured to receive PDSCH according to "TDMSchemeA"and is indicated with two TCI states in the DCI. In this case, the scheduling offset from the last symbol of the PDCCH to the first symbol of PDSCH1 is smaller than the threshold timeDurationForQCL, and/or the scheduling offset from the last symbol of the PDCCH to the first symbol of PDSCH2 is smaller than the threshold timeDurationForQCL.

In this case, the <NUM>st default TCI state is applied to PDSCH1 and the <NUM>nd default TCI state is applied to PDSCH2. The default TCI states for the PDSCH are given by the TCI states corresponding to the lowest codepoint among the TCI codepoints containing two different TCI states, according to the NR Rel-<NUM> specification. Hence, the <NUM>st and <NUM>nd default TCI states respectively correspond to the first and the second of the two different TCI states corresponding to the lowest such codepoint.

Furthermore, in this embodiment, an aperiodic CSI-RS (AP CSI-RS) is triggered to the UE with scheduling offset between the last symbol of the PDCCH carrying the triggering DCI and the first symbol of the aperiodic CSI-RS resources is smaller than the UE reported threshold beamSwitchTiming. In this case, there are two possibilities as shown in <FIG> which illustrates a first example of Embodiment <NUM> considering AP CSI-RS collision with PDSCH scheduled according to "TDMSchemeA".

As shown in <FIG>, when AP CSI-RS is in the same symbols as PDSCH2, the UE applies the QCL assumption of PDSCH2 (given by the <NUM>nd default TCI state) when receiving the AP CSI-RS. Stated in other words, the UE receives the AP CSI-RS using the same receive beam as the one used to receive PDSCH2 whose spatial QCL properties are given by the <NUM>nd default TCI state.

Embodiment <NUM> for scenario when AP CSI-RS collides with PDSCH scheduled according to single-PDCCH based NC-JT scheme and scheduling offset above a threshold.

In this embodiment, a UE is configured to receive PDSCH according to single-PDCCH based NC-JT scheme and is indicated with two TCI states in the DCI where the two indicated TCI states are used to receive different sets of layers corresponding to the PDSCH (i.e., first set of layers correspond to <NUM>st TCI state and second set of layers correspond to <NUM>nd TCI state). This corresponds to the case where the scheduling offset from the last symbol of the PDCCH to the first symbol of the PDSCH is larger than or equal to the threshold timeDurationForQCL.

Furthermore, in one case, an aperiodic CSI-RS (AP CSI-RS) is triggered to the UE by another DCI with scheduling offset between the last symbol of the PDCCH carrying the triggering DCI and the first symbol of the aperiodic CSI-RS resources is smaller than the UE reported threshold beamSwitchTiming. <FIG> illustrates a first example of Embodiment <NUM> considering AP CSI-RS collision with PDSCH scheduled according to single-PDCCH based NC-JT scheme, where the <NUM>st TCI state is assumed for the AP CSI-RS. The aperiodic CSI-RS overlaps with the PDSCH symbols as shown in <FIG>.

In this case, when AP CSI-RS is in the same symbols as PDSCH as shown in <FIG>, the UE applies the QCL assumption given by the 1st indicated TCI state in DCI for the PDSCH when receiving the AP CSI-RS. Stated in other words, the UE receives the AP CSI-RS using the same receive beam as the one used to receive PDSCH whose spatial QCL properties are given by the 1st indicated TCI state in DCI.

In a second case, two AP CSI-RSs (e.g., each AP CSI-RS transmitted from a different TRP) are triggered to the UE with scheduling offset between the last symbol of the PDCCH carrying the triggering DCI and the first symbol(s) of the aperiodic CSI-RS resources is smaller than the UE reported threshold beamSwitchTiming. <FIG> illustrates a second example of Embodiment <NUM> considering AP CSI-RS collision with PDSCH scheduled according to single-PDCCH based NC-JT scheme, where the <NUM>st and <NUM>nd TCI states are assumed for the <NUM>st and <NUM>nd AP CSI-RS, respectively. The two aperiodic CSI-RSs overlap with the PDSCH symbols as shown in <FIG>.

In this case, for the <NUM>st AP CSI-RS, the UE applies the QCL assumption given by the 1st indicated TCI state in DCI for the PDSCH when receiving the <NUM>st AP CSI-RS. Stated in other words, the UE receives the <NUM>st AP CSI-RS using the same receive beam as the one used to receive PDSCH whose spatial QCL properties are given by the 1st indicated TCI state in DCI.

For the <NUM>nd AP CSI-RS, the UE applies the QCL assumption given by the 2nd indicated TCI state in DCI for the PDSCH when receiving the <NUM>nd AP CSI-RS. Stated in other words, the UE receives the <NUM>nd AP CSI-RS using the same receive beam as the one used to receive PDSCH whose spatial QCL properties are given by the 2nd indicated TCI state in DCI.

The <NUM>st and <NUM>nd AP CSI-RS resources are defined using either the CSI-RS resource IDs or CSI-RS resource set IDs (i.e., NZP-CSI-RS-ResourceSetId) to which the AP CSI-RS resources belong to. For instance, if the two AP CSI-RS resources are in different CSI-RS resource set IDs, then the AP CSI-RS resource with the smallest NZP-CSI-RS-ResourceSetId is the <NUM>st AP CSI-RS resource and the AP CSI-RS resource with the largest NZP-CSI-RS-ResourceSetId is the <NUM>nd AP CSI-RS resource. Similar definition of <NUM>st and <NUM>nd AP CSI-RS resource can be achieved by using CSI-RS resource IDs in place of CSI-RS resource set IDs.

Although this embodiment is written from the perspective of PDSCH scheduled according to single-PDCCH based NC-JT scheme it can be easily extended to PDSCH scheduled via either "FDMSchemeA" or "FDMSchemeB".

Embodiment <NUM> for scenario when AP CSI-RS collides with PDSCH scheduled according to single-PDCCH based NC-JT scheme and scheduling offset below a threshold.

In this embodiment, a UE is configured to receive PDSCH according to single-PDCCH based NC-JT scheme and is indicated with <NUM> TCI states in the DCI where the <NUM> default TCI states are used to receive different layers corresponding to the PDSCH. This corresponds to the case where the scheduling offset from the last symbol of the PDCCH to the first symbol of the PDSCH is smaller than the threshold timeDurationForQCL. The default TCI states for the PDSCH are given by the TCI states corresponding to the lowest codepoint among the TCI codepoints containing two different TCI states, according to the NR Rel-<NUM> specification.

Furthermore, in one case, an Aperiodic CSI-RS (AP CSI-RS) is triggered to the UE with scheduling offset between the last symbol of the PDCCH carrying the triggering DCI and the first symbol of the aperiodic CSI-RS resources is smaller than the UE reported threshold beamSwitchTiming. <FIG> illustrates a first example of Embodiment <NUM> considering AP CSI-RS collision with PDSCH scheduled according to single-PDCCH based NC-JT scheme, where the <NUM>st default TCI state is assumed for the AP CSI-RS. The aperiodic CSI-RS overlaps with the PDSCH symbols as shown in <FIG>.

In this case, when AP CSI-RS is in the same symbols as PDSCH as shown in <FIG>, the UE applies the QCL assumption given by the 1st default TCI state in DCI for the PDSCH when receiving the AP CSI-RS. Stated in other words, the UE receives the AP CSI-RS using the same receive beam as the one used to receive PDSCH whose spatial QCL properties are given by the 1st default TCI state.

In a second case, two AP CSI-RSs (e.g., each AP CSI-RS transmitted from a different TRP) are triggered to the UE with scheduling offset between the last symbol of the PDCCH carrying the triggering DCI and the first symbol(s) of the aperiodic CSI-RS resources is smaller than the UE reported threshold beamSwitchTiming. <FIG> illustrates a second example of Embodiment <NUM> considering AP CSI-RS collision with PDSCH scheduled according to single-PDCCH based NC-JT scheme, where the <NUM>st and <NUM>nd default TCI states are assumed for the <NUM>st and <NUM>nd AP CSI-RS, respectively. The two aperiodic CSI-RSs overlap with the PDSCH symbols as shown in <FIG>.

In this case, for the <NUM>st AP CSI-RS, the UE applies the QCL assumption given by the 1st default TCI state for the PDSCH when receiving the <NUM>st AP CSI-RS. Stated in other words, the UE receives the <NUM>st AP CSI-RS using the same receive beam as the one used to receive PDSCH whose spatial QCL properties are given by the 1st default TCI state in DCI.

For the <NUM>nd AP CSI-RS, the UE applies the QCL assumption given by the 2nd default TCI state for the PDSCH when receiving the <NUM>nd AP CSI-RS. Stated in other words, the UE receives the <NUM>nd AP CSI-RS using the same receive beam as the one used to receive PDSCH whose spatial QCL properties are given by the 2nd indicated TCI state in DCI.

Although this embodiment is written from the perspective of PDSCH scheduled according to single-PDCCH based NC-JT scheme it can be easily extended to PDSCH scheduled via either "FDMSchemeA" or "FDMSchemes".

<FIG> is a schematic block diagram of a radio access node <NUM> according to some embodiments of the present disclosure. Optional features are represented by dashed boxes. The radio access node <NUM> may be, for example, a base station <NUM> or <NUM> or a network node that implements all or part of the functionality of the base station <NUM> or gNB described herein. As illustrated, the radio access node <NUM> includes a control system <NUM> that includes one or more processors <NUM> (e.g., Central Processing Units (CPUs), Application Specific Integrated Circuits (ASICs), Field Programmable Gate Arrays (FPGAs), and/or the like), memory <NUM>, and a network interface <NUM>. The one or more processors <NUM> are also referred to herein as processing circuitry. In addition, the radio access node <NUM> may include one or more radio units <NUM> that each includes one or more transmitters <NUM> and one or more receivers <NUM> coupled to one or more antennas <NUM>. The radio units <NUM> may be referred to or be part of radio interface circuitry. In some embodiments, the radio unit(s) <NUM> is external to the control system <NUM> and connected to the control system <NUM> via, e.g., a wired connection (e.g., an optical cable). However, in some other embodiments, the radio unit(s) <NUM> and potentially the antenna(s) <NUM> are integrated together with the control system <NUM>. The one or more processors <NUM> operate to provide one or more functions of a radio access node <NUM> as described herein. In some embodiments, the function(s) are implemented in software that is stored, e.g., in the memory <NUM> and executed by the one or more processors <NUM>.

As used herein, a "virtualized" radio access node is an implementation of the radio access node <NUM> in which at least a portion of the functionality of the radio access node <NUM> is implemented as a virtual component(s) (e.g., via a virtual machine(s) executing on a physical processing node(s) in a network(s)). As illustrated, in this example, the radio access node <NUM> may include the control system <NUM> and/or the one or more radio units <NUM>, as described above. The control system <NUM> may be connected to the radio unit(s) <NUM> via, for example, an optical cable or the like. The radio access node <NUM> includes one or more processing nodes <NUM> coupled to or included as part of a network(s) <NUM>. If present, the control system <NUM> or the radio unit(s) is connected to the processing node(s) <NUM> via the network <NUM>. Each processing node <NUM> includes one or more processors <NUM> (e.g., CPUs, ASICs, FPGAs, and/or the like), memory <NUM>, and a network interface <NUM>.

In this example, functions <NUM> of the radio access node <NUM> described herein are implemented at the one or more processing nodes <NUM> or distributed across the one or more processing nodes <NUM> and the control system <NUM> and/or the radio unit(s) <NUM> in any desired manner. In some particular embodiments, some or all of the functions <NUM> of the radio access node <NUM> described herein are implemented as virtual components executed by one or more virtual machines implemented in a virtual environment(s) hosted by the processing node(s) <NUM>. As will be appreciated by one of ordinary skill in the art, additional signaling or communication between the processing node(s) <NUM> and the control system <NUM> is used in order to carry out at least some of the desired functions <NUM>. Notably, in some embodiments, the control system <NUM> may not be included, in which case the radio unit(s) <NUM> communicates directly with the processing node(s) <NUM> via an appropriate network interface(s).

<FIG> is a schematic block diagram of a wireless communication device <NUM> according to some embodiments of the present disclosure. As illustrated, the wireless communication device <NUM> includes one or more processors <NUM> (e.g., CPUs, ASICs, FPGAs, and/or the like), memory <NUM>, and one or more transceivers <NUM> each including one or more transmitters <NUM> and one or more receivers <NUM> coupled to one or more antennas <NUM>. The transceiver(s) <NUM> includes radio-front end circuitry connected to the antenna(s) <NUM> that is configured to condition signals communicated between the antenna(s) <NUM> and the processor(s) <NUM>, as will be appreciated by on of ordinary skill in the art. The processors <NUM> are also referred to herein as processing circuitry. The transceivers <NUM> are also referred to herein as radio circuitry. In some embodiments, the functionality of the wireless communication device <NUM> described above may be fully or partially implemented in software that is, e.g., stored in the memory <NUM> and executed by the processor(s) <NUM>. Note that the wireless communication device <NUM> may include additional components not illustrated in <FIG> such as, e.g., one or more user interface components (e.g., an input/output interface including a display, buttons, a touch screen, a microphone, a speaker(s), and/or the like and/or any other components for allowing input of information into the wireless communication device <NUM> and/or allowing output of information from the wireless communication device <NUM>), a power supply (e.g., a battery and associated power circuitry), etc..

With reference to <FIG>, in accordance with an embodiment, a communication system includes a telecommunication network <NUM>, such as a 3GPP-type cellular network, which comprises an access network <NUM>, such as a RAN, and a core network <NUM>. The access network <NUM> comprises a plurality of base stations 3006A, 3006B, 3006C, such as Node Bs, eNBs, gNBs, or other types of wireless Access Points (APs), each defining a corresponding coverage area 3008A, 3008B, 3008C. Each base station 3006A, 3006B, 3006C is connectable to the core network <NUM> over a wired or wireless connection <NUM>. A first UE <NUM> located in coverage area 3008C is configured to wirelessly connect to, or be paged by, the corresponding base station 3006C. A second UE <NUM> in coverage area 3008A is wirelessly connectable to the corresponding base station 3006A.

It is noted that the host computer <NUM>, the base station <NUM>, and the UE <NUM> illustrated in <FIG> may be similar or identical to the host computer <NUM>, one of the base stations 3006A, 3006B, 3006C, and one of the UEs <NUM>, <NUM> of <FIG>, respectively.

The wireless connection <NUM> between the UE <NUM> and the base station <NUM> is in accordance with the teachings of the embodiments described throughout this disclosure. One or more of the various embodiments improve the performance of OTT services provided to the UE <NUM> using the OTT connection <NUM>, in which the wireless connection <NUM> forms the last segment. More precisely, the teachings of these embodiments may improve the e.g., data rate, latency, power consumption, etc. and thereby provide benefits such as e.g., reduced user waiting time, relaxed restriction on file size, better responsiveness, extended battery lifetime, etc..

Claim 1:
A method performed by a wireless device for determining Transmission Configuration Indication, TCI, states for receiving one or more Aperiodic, AP, Channel State Information Reference Signals, CSI-RSs, the method comprising:
receiving (<NUM>) downlink control information, DCI, in a physical downlink control channel, PDCCH, triggering one or more AP CSI-RSs in one or more symbols with a first time offset between a last symbol of the PDCCH and the first symbol of the one or more symbols containing the AP CSI-RSs, where the time offset is smaller than a first threshold;
determining (<NUM>) a Quasi Co-Location, QCL, assumption for receiving the one or more AP CSI-RSs based on a plurality of TCI states associated with one or more downlink transmissions scheduled by the DCI in the same one or more symbols as the one or more AP CSI-RSs, wherein the plurality of TCI states are indicated in a DCI scheduling the one or more downlink transmissions, wherein, when the time offset is smaller than the first threshold, the determined QCL assumption is a QCL assumption given by a TCI state of the plurality of TCI states indicated by the DCI scheduling the one or more downlink transmissions in a symbol of the same one or more symbols that are used for receiving the one or more AP CSI-RSs; and
receiving (<NUM>) the one or more AP CSI-RSs in the one or more symbols using the determined QCL assumption.