Patent Description:
The present disclosure relates to non-codebook based uplink transmission in a cellular communications system.

Third Generation Partnership Project (3GPP) New Radio (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). Discrete Fourier Transform (DFT) spread Orthogonal Frequency Division Multiplexing (OFDM) is also supported in the uplink. In the time domain, NR downlink and uplink are organized into equally sized subframes of <NUM> millisecond (ms) 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> kilohertz (kHz), there is only one slot per subframe, and each slot consists of fourteen (<NUM>) Orthogonal Frequency Division Multiplexing (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, i.e., 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, which are also referred to as different numerologies, are given by Δf = (<NUM> × <NUM>µ) kHz where e {<NUM>,<NUM>,<NUM>,<NUM>,<NUM>}. Δf = <NUM>kHz is the basic subcarrier spacing. The slot durations at different subcarrier spacings is given by <MAT>.

In the frequency domain, a system bandwidth is divided into Resource Blocks (RBs), each corresponds to twelve (<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 RB within a <NUM>-symbol slot is shown. One OFDM subcarrier during one OFDM symbol interval forms one Resource Element (RE).

In NR Release <NUM>, uplink data transmission can be dynamically scheduled using PDCCH. A UE first decodes uplink grants in PDCCH and then transmits data over PUSCH based the decoded control information in the uplink grant such as modulation order, coding rate, uplink resource allocation, etc. In dynamic scheduling of PUSCH, there is also a possibility to configure semi-persistent transmission of PUSCH using configured grants (CGs). There are two types of CG based PUSCH defined in NR Release <NUM>, namely, CG type <NUM> and CG type <NUM>. In CG type <NUM>, a periodicity of PUSCH transmission as well as the time domain offset are configured by Radio Resource Control (RRC). In CG type <NUM>, a periodicity of PUSCH transmission is configured by RRC, and then the activation and release of such transmission is controlled by Downlink Control Information (DCI), i.e. with a PDCCH.

In NR, it is possible to schedule a PUSCH with time repetition by the RRC parameter pusch-AggregationFactor for dynamically scheduled PUSCH and repK for PUSCH with UL configured grant. In this case, the PUSCH is scheduled but transmitted in multiple adjacent slots if the slot is available for UL transmission, up until the number of repetitions as determined by the configured RRC parameter.

In the case of PUSCH with UL configured grant, the redundancy version (RV) sequence to be used is configured by the repK-RV field when repetitions are used. If repetitions are not used for PUSCH with UL configured grant, then the repK-RV field is absent.

In NR Release-<NUM>, there are two mapping types supported, Type A and Type B, that are applicable to PDSCH and PUSCH transmissions. Type A transmissions are usually referred to as slot-based transmissions, while Type B transmissions may be referred to as non-slot-based or mini-slot-based transmissions.

Mini-slot transmissions can be dynamically scheduled and, for NR Release <NUM>:.

Note that mini-slot transmissions in NR Release <NUM> may not cross the slot-border.

One of the two frequency hopping modes, inter-slot and intra-slot frequency hopping, can be configured via higher layer for PUSCH transmission in NR Release <NUM>, in the Information Element (IE) PUSCH-Config for dynamic transmission or IE configuredGrantConfig for CG Type <NUM> and CG Type <NUM>.

Spatial relation is used in NR to refer to a relationship between an UL Reference Signal (RS) to be transmitted such as Physical Uplink Control Channel (PUCCH) / PUSCH Demodulation Reference Signal (DMRS) and another previously transmitted or received RS, which can be either a DL RS (Channel State Information Reference Signal (CSI-RS) or Synchronization Signal Block (SSB)) or an UL RS (Sounding Reference Signal (SRS)). This is defined from a UE perspective.

If an UL transmitted RS is spatially related to a DL RS, this means that the UE should transmit the UL RS in the opposite (reciprocal) direction from which it received the DL RS previously. More precisely, the UE should apply the "same" Transmit (Tx) spatial filtering configuration for the transmission of the UL RS as the Rx spatial filtering configuration it used to receive the spatially related DL RS previously. Here, the terminology 'spatial filtering configuration' may refer to the antenna weights that are applied at either the transmitter or the receiver for data/control transmission/reception. Another way to describe this is that the same "beam" should be used to transmit the signal from the UE as was used to receive the previous DL RS signal. The DL RS is also referred as the spatial filter reference signal.

On the other hand, if a first UL RS is spatially related to a second UL RS, then the UE should apply the same Tx spatial filtering configuration for the transmission for the first UL RS as the Tx spatial filtering configuration it used to transmit the second UL RS previously. In other words, same beam is used to transmit the first and second UL RSs, respectively.

Since the UL RS is associated with a layer of PUSCH or PUCCH transmission, it is understood that the PUSCH/PUCCH is also transmitted with the same TX spatial filter as the associated UL RS.

In NR, there are two transmission schemes specified for PUSCH, namely, a codebook based PUSCH transmission scheme and a non-codebook based PUSCH transmission scheme.

The codebook based PUSCH transmission scheme is used on both NR and LTE and was motivated to be used for non-calibrated UEs and/or UL Frequency Division Duplex (FDD). Codebook based PUSCH in NR is enabled if higher layer parameter txConfig = codebook. For dynamically scheduled PUSCH and configured grant PUSCH type <NUM>, the codebook based PUSCH transmission scheme can be summarized as follows:.

The TPMI is used to indicate the precoder to be applied over the layers {<NUM>. v-<NUM>} and that corresponds to the SRS resource selected by the SRI when multiple SRS resources are configured, or if a single SRS resource is configured TPMI is used to indicate the precoder to be applied over the layers {<NUM>. v-<NUM>} and that corresponds to the SRS resource. The transmission precoder is selected from the uplink codebook that has a number of antenna ports equal to higher layer parameter nrofSRS-Ports in SRS-Config.

Non-Codebook based PUSCH transmission is available in NR, enabling reciprocity-based UL transmission. Non-Codebook based PUSCH in NR is enabled if higher layer parameter txConfig = noncodebook. Note that in NR Release <NUM>/<NUM>, the number of SRS resource sets with higher layer parameter usage set to 'nonCodeBook' is limited to one (i.e., only one SRS resource set is allowed to be configured for the purposes of non-Codebook based PUSCH transmission). The maximum number of SRS resources that can be configured for non-codebook based uplink transmission is four (<NUM>).

With regards to non-codebook based PUSCH, the following is specified in 3GPP TS <NUM> V16. <NUM>:
"For non-codebook based transmission, the UE can calculate the precoder used for the transmission of SRS based on measurement of an associated NZP CSI-RS resource. A UE can be configured with only one NZP CSI-RS resource for the SRS resource set with higher layer parameter usage in SRS-ResourceSet set to 'nonCodebook' if configured.

Hence, for non-codebook based PUSCH transmission, only one Non-Zero Power (NZP) CSI-RS resource is configured in the SRS resource set, and the UE can calculate the precoder used for the transmission of SRS using this associated NZP CSI-RS resource. The single NZP CSI-RS resource configured per SRS resource set is part of the SRS-Config information element and is shown in <FIG>. The condition 'NonCodebook' means that the associated NZP CSI-RS is optionally present in case of the SRS resource set configured with usage set to 'nonCodeBook', otherwise the field is absent.

It is further specified in 3GPP TS <NUM> that if the UE is configured with an SRS resource set with an associated NZP CSI-RS resource, then the UE is not expected to be configured with spatial relation information in any of the SRS resources in the SRS resource set.

In NR, for non-codebook based PUSCH, the UE performs a one-to-one mapping from the indicated SRI(s) to the indicated DM-RS port(s) and their corresponding PUSCH layers {<NUM>. v-<NUM>} in increasing order. The UE shall transmit PUSCH using the same antenna ports as the SRS port(s) in the SRS resource(s) indicated by SRI(s), where the SRS port in (i+<NUM>)-th SRS resource in the SRS resource set is indexed as pi = <NUM> + i.

In NR Release <NUM>, PUSCH repetition enhancements were made for both PUSCH type A and type B for the purposes of further latency reduction (i.e., for Release <NUM> Ultra-Reliable Low-Latency Communication (URLLC)).

In regard to PUSCH repetition type A (slot based) enhancement, in NR Release <NUM>, the number of aggregated slots for both dynamic grant and configured grant Type <NUM> are RRC configured. In NR Release <NUM>, this was enhanced so that the number of repetitions can be dynamically indicated, i.e. change from one PUSCH scheduling occasion to the next. That is, in addition to the starting symbol S and the length of the PUSCH L, a number of nominal repetitions K is signaled as part of time-domain resource allocation (TDRA). Furthermore, the maximum number of aggregated slots was increased to K=<NUM> to account for DL heavy Time Division Duplexing (TDD) patterns. Inter-slot and intra-slot hopping can be applied for Type A repetition. The number of repetitions K is nominal since some slots may be DL slots and are then skipped for PUSCH transmissions. So, K is the maximal number of repetitions possible.

In regard to PUSCH repetition type B (mini-slot based) enhancements, PUSCH repetition Type B applies both to dynamic and configured grants. Type B PUSCH repetition can cross the slot boundary in Rel-<NUM>. When scheduling a transmission with PUSCH repetition Type B, in addition to the starting symbol S and the length of the PUSCH L, a number of nominal repetitions K is signaled as part of TDRA in NR Release <NUM>. Inter-slot frequency hopping and inter-repetition frequency hopping can be configured for Type B repetition. To determine the actual time domain allocation of Type B PUSCH repetitions, a two-step process is used:.

Although the term 'PUSCH repetition' is used in this document, it can be interchangeably used with other terms such as 'PUSCH transmission occasion'.

In NR Rel-<NUM>/<NUM>, when PUSCH is repeated according to PUSCH repetition Type A or Type B, the PUSCH is limited to a single transmission layer.

Another NR Release <NUM> PUSCH enhancement relates to redundancy version (RV). The channel encoder can be controlled by the RV. In NR, an information payload can be encoded with four different RVs to allow for incremental redundancy decoding. The redundancy version to be applied on the nth transmission occasion of the Transport Block (TB), where n = <NUM>, <NUM>,. K -<NUM>, is determined according to Table <NUM> below.

<NPL>, relates to enhancements of Rel. <NUM> UL beam management.

Document <CIT> describes a signaling information transmission technique. A method of the technique comprises receiving signaling information and determining channel state information of M physical uplink channels based on the signaling information, wherein M is a positive integer greater than <NUM>.

<NPL>, discusses replacement of NZP-CSI-RS-ResourceConfigId with NZP-CSI-RS-ResourceId in TS <NUM>.

<NPL>, studies non-codebook enhancements for multibeam operation with multiple panel.

The invention is defined and limited by the appended set of independent claims.

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 Function (AMF), a 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.

In some embodiments, a TRP may be either a network node, a radio head, a spatial relation, or a Transmission Configuration Indicator (TCI) state. A TRP may be represented by a spatial relation, a SRS resource set or a TCI state in some embodiments. In some embodiments, a TRP may a part of the gNB transmitting and receiving radio signals to/from UE according to physical layer properties and parameters inherent to that element.

There currently exist certain challenge(s). NR support only one Sounding Reference Signal (SRS) resource set for non-codebook based Physical Uplink Shared Channel (PUSCH) transmission and only one associated Non-Zero Power (NZP) Channel State Information Reference Signal (CSI-RS) which the UE uses to calculate the precoder used for the transmission of SRS. The solution in NR only supports PUSCH transmission towards a single Transmission/Reception Point (TRP) or single Receive (RX) beam at the network side.

Hence, it is a problem in NR that the PUSCH transmission cannot be received with multiple TRPs if the UE use beamforming for transmission, i.e. the beam width is narrow and can only point toward a single TRP when transmitting. This problem implies that peak throughput for PUSCH is limited and/or the reliability is limited. It is not possible to transmit to more than one TRP at a time.

Certain aspects of the present disclosure and their embodiments may provide solutions to the aforementioned or other challenges. The proposed solutions introduce N NZP CSI-RS to be associated with either N SRS resource groups or N SRS resource sets, thus enabling each NZP CSI-RS resource to be used to calculate precoders corresponding to N TRPs. The value of N is preferably greater than <NUM> (e.g., <NUM>, <NUM>, etc.). The calculated precoder layers can be used to transmit PUSCH layers targeting these N TRPs. This enables the non-codebook based PUSCH transmission to be used for multi-TRP which is not supported in NR.

Certain embodiments may provide one or more of the following technical advantage(s). The advantage of the solution is that PUSCH can be transmitted with improved reception at multiple TRPs simultaneously or repetitively using non-codebook based PUSCH. This improves the peak throughput and/or the reliability of the transmissions.

<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. In this example, the RAN includes base stations <NUM>-<NUM> and <NUM>-<NUM>, which in <NUM> NR are referred to as gNBs, 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>.

In the following description, the wireless communication devices <NUM> are oftentimes UEs and as such the wireless communication devices <NUM> are sometimes referred to herein as UEs <NUM>, but the present disclosure is not limited thereto.

Some example embodiments of the present disclosure will now be provided. While sometimes described separately, these embodiments may be used in any desired combination unless otherwise stated or required.

In this embodiment, the SRS resources in an SRS resource set are grouped into two or more different SRS resource groups, and there are two or more NZP CSI-RS resources associated with the SRS resource set. A first NZP CSI-RS resource is associated with the first SRS resource group, a second NZP CSI-RS resource is associated with the second SRS resource group, and so on.

In one embodiment, an SRS resource group is identified by an NZP CSI-RS resource as part of spatial relation information configuration (i.e., higher layer parameter SRS-SpatialRelationInfo) for each SRS resource in the SRS resource set. For example, one of two NZP CSI-RS resources may be configured as the reference signal for each SRS resource SRS-SpatialRelationInfo. The first SRS resource group may include SRS resources configured with a NZP CSI-RS resource having a smaller value of NZP CSI-RS resource ID and the second SRS resource group may include SRS resources configured with a NZP CSI-RS resource having a larger value of NZP CSI-RS resource ID. An example is shown in <FIG>. In particular, <FIG> illustrates an example in which there are two SRS resource groups in an SRS resource set, and SRS resources in each group are configured with a same NZP CSI-RS resource (i.e., resource ID). More generally, the nth SRS resource group is associated with the nth NZP CSI-RS resource ID ordered, e.g. in increasing order.

In some embodiments, K different NZP CSI-RS resource IDs are configured. Then, to associate an SRS resource in the SRS resource set with a NZP CSI-RS resource, an indication of one of the NZP CSI-RS resources is included as part of SRS resource configuration. This indication may be the ID of the NZP CSI-RS resource or an index k (k=<NUM>,<NUM>,. ,K) representing the kth associated NZP CSI-RS resource configured as part the SRS Resource Set.

In the following, the description assumes two TRPs and hence two SRS resource groups, but it can without loss of generality be extended to more than two such groups to support reception by more than two TRPs.

An NZP CSI-RS is received by the UE in the corresponding NZP CSI-RS resource, and the NZP CSI-RS resource configuration contains detailed parameters associated with the NZP CSI-RS (e.g., number of ports, Code Division Multiplexing (CDM) groups, density, etc.). An SRS is transmitted by the UE in the corresponding SRS resource, and the SRS resource configuration contains detailed parameters associated with the SRS (e.g., number of ports, occupied symbols in a slot, etc.). The parameters can be conveyed for example via RRC.

While receiving the first NZP CSI-RS (i.e., while receiving a NZP CSI-RS on the first NZP CSI-RS resource), the UE measures and calculates a first SRS precoder based on the first NZP CSI-RS associated with the first SRS resource group. In other words, the UE performs measurements on the first NZP CSI-RS associated with the first SRS resource group and calculates the first SRS precoder based on the measurements performed on the first NZP CSI-RS. Similarly, while receiving the second NZP CSI-RS, the UE measures and calculates a second SRS precoder based on the second NZP CSI-RS associated with the second SRS resource group. The first/second NZP CSI-RS may be periodic (e.g., configured by gNB to UE via RRC), or may be semi-persistent (e.g., configured by gNB to UE via RRC and activated by MAC CE), or may be aperiodic (e.g., configured by gNB to UE via RRC and triggered by DCI). In some embodiments, the two associated NZP CSI-RS resources have the same time-domain behavior (i.e., both of them are periodic, semi-persistent, or aperiodic).

In some embodiments, the UE then transmits a first PUSCH or a first set of layers of a PUSCH on antenna ports corresponding to SRS resources in the first SRS group and transmits a second PUSCH or a second set of layers of a PUSCH on antenna ports corresponding to SRS resources in the second SRS group. In some other embodiments, UE transmits layers of the first precoder on SRS resources from the first SRS group and transmits layers of the second precoder on SRS resources from the second SRS group. In another scenario, the UE may transmit a first set of layers of a PUSCH using antenna ports corresponding to SRS resources in the first SRS group and transmit a second set of layers of the PUSCH using antenna ports corresponding to SRS resources in the second SRS group. A single layer is transmitted using an antenna port corresponding to each SRS resource. In some embodiments, the number of antenna ports or layers transmitted from each SRS group has to be the same (e.g., <NUM> layer on one SRS resource from the <NUM>st SRS group and <NUM> layer on a second SRS resource from the <NUM>nd SRS group).

The UE may also choose to transmit PUSCH using layers of a single SRS group only, if it decides that the path loss to the TRP associated with the second SRS group is too weak. Hence, the UE can autonomously switch between PUSCH transmission toward the first TRP, the second TRP, or both TRPs, depending on how it selects resources from different groups correspondingly.

In another embodiment, one Phase Tracking Reference Signal (PTRS) port is associated with each SRS resource group. If the UE selects layers of PUSCH on SRS resources in the first SRS group and transmits a second PUSCH or a second set of layers of a PUSCH on SRS resources in the second SRS group, it will transmit two PTRS ports, one per SRS group. If it selects only layers from a single SRS group, it transmits only a single PTRS port.

The gNB measures the SRS transmitted by the UE in each SRS resource group and determines the desired SRS resources for non-codebook based PUSCH transmission over SRS ports in the corresponding SRS resource group. The determined SRS resources are then indicated to the UE via an SRI field as part of a DCI scheduling a non-codebook based PUSCH transmission. The SRI field may also indicate the SRS resource group or groups in addition to the SRS resource(s) in each group. The non-codebook based PUSCH transmission may consist of a plurality of repetitions where each repetition may be over a slot (i.e., type A PUSCH) or a subset of symbols within a slot (i.e., type B PUSCH).

If the SRI field in DCI indicates SRS resources from both the <NUM>st SRS group and the <NUM>nd SRS group, then the PUSCH transmission over the plurality of repetitions is as follows:.

An example is shown in <FIG>. In this example, SRS resources <NUM> and <NUM> in SRS resource group <NUM> that are indicated via the SRI field and the precoder layers calculated on the <NUM>st NZP CSI-RS associated with SRS group <NUM> are used for transmitting up to L=<NUM> layers in the <NUM>st PUSCH transmission occasion. Similarly, the SRS resources <NUM> and <NUM> in SRS group <NUM> that are indicated via the SRI field and the precoder layers calculated on the <NUM>nd NZP CSI-RS associated with SRS group <NUM> are used for transmitting up to L=<NUM> layers in the <NUM>nd PUSCH transmission occasion.

In some embodiments, the number of SRS resources belonging to each SRS resource group indicated via SRI field should be the same in order to support the same number of layers transmitted in each repetition. For example, if an SRI indicates <NUM> SRS resources, then there must be <NUM> SRS resources belonging to each SRS resource group; and if SRI indicates <NUM> SRS resources, then there must be <NUM> SRS resource belonging to each SRS resource group. If SRI indicates only a single SRS resource, then this corresponds to a single layer PUSCH transmission using the spatial relation of indicated SRS resource in all the repetitions. In some embodiments, the SRS group is configured to an SRS resource by including an SRS group ID per SRS resource configuration.

In some embodiments, the maximum number of layers per PUSCH repetition is limited to <NUM> layer. In this embodiment, the UE maps the indicated SRI(s) to the same DM-RS port and its corresponding PUSCH layer <NUM> in all the repetitions. That is, the SRS port in the multiple SRS resources in the SRS resource set indicated via the SRI field is in indexed as pi = <NUM> irrespective of i.

In another embodiment, the maximum number of layers per PUSCH repetition is limited to L layers where the value of L may be a UE capability (e.g., whether a UE supports two PUSCH layers (i.e., L=<NUM>) per repetition is reported as part of UE capability).

In some embodiments, the number of SRS resources belonging to each SRS resource group indicated via SRI field should be the same in order to support the same number of layers transmitted in each repetition. For example, if an SRI indicates <NUM> SRS resources that belong to <NUM> different SRS groups, then there must be <NUM> SRS resources belonging to each SRS resource group; and if SRI indicates <NUM> SRS resources, then there must be <NUM> SRS resource belonging to each SRS resource group. If SRI indicates only a single SRS resource, then this corresponds to a single layer PUSCH transmission using the spatial relation of indicated SRS resource in all the repetitions. In some embodiments, the SRS group is configured to an SRS resource by including an SRS group ID per SRS resource configuration.

In this embodiment, instead of configuring groups within a single SRS Resource set as in Embodiment <NUM>, multiple SRS resource sets may be configured by RRC for a UE, each may be associated with a TRP through an associated NZP CSI-RS resource. That is, multiple SRS resource sets are configured to the UE for the purpose of non-codebook based PUSCH transmission with higher layer parameter usage being set to 'nonCodeBook', and each of the multiple SRS resource sets have an associated NZP CSI-RS resource configured. Each SRS resource set may contain one or more SRS resources each with a single SRS port. An example is shown in <FIG>, where two SRS resource sets each with four SRS resources are configured for a UE and each SRS resource set is associated with an NZP CSI-RS transmitted from a TRP. Each NZP CSI-RS may contain one or more NZP CSI-RS ports.

One or more SRS resource sets may be dynamically indicated in DCI together with one or more SRS resources in the SRS resource set to a UE where the DCI schedules a non-codebook based PUSCH transmission. For example, if two SRS resource sets are configured, either the first SRS resource set, the second SRS resource set, or both the first and the second SRS resource sets may be indicated to the UE. When both SRS resource sets are indicated, the UE would transmit the PUSCH according to the first SRS resource set in the first PUSCH transmission occasion and according to the second SRS resource set in the second PUSCH transmission occasion. If more than two transmission occasions are configured or indicated, the pattern of {<NUM>st SRS resource set, <NUM>nd SRS resource set} may be repeated for the rest of the transmission occasions.

An example is shown in <FIG> with four PUSCH transmission occasions and two SRS resource sets and with a single layer transmission in which one SRS resource is selected in each SRS resource set. The first SRS resource set is associated with TRP#<NUM> while the second SRS resource is associated with TRP#<NUM>. For each SRS resource set, one or more SRS resource may be indicated by an SRI indicator. The SRS resources may be either separately indicated, e.g., one SRI bit field for each SRS resource set in the DCI, or jointly indicated with a single SRI bit field.

In another embodiment, other patterns may be used instead. For example, the first SRS resource set may be used in the first two PUSCH transmission occasions and the second SRS resource set in the next two PUSCH transmission occasions. The same pattern may be repeated if more than four transmission occasions are configured or indicated.

In one embodiment, a single SRS resource set is associated with N><NUM> NZP CSI-RS resources as well as M N-port SRS resources. For each received NZP CSI-RS, the UE determines M PUSCH layers to be sounded using SRS. The SRS resources are then utilized such that port n of SRS resource m is sounding PUSCH layer m derived from NZP CSI-RS resource n.

The gNB measures on the transmitted SRS resources and indicates one or more SRIs, each SRI corresponding to a subset of SRS resources. For each indicated SRI, an associated NZP CSI-RS resource is also indicated. The gNB can indicate a single "SRI and NZP CSI-RS resource" pair for dynamic point selection, i.e., to enable single-TRP PUSCH transmission towards the best TRP out of the N candidates. If single-TRP with NZP CSI-RS resource n is indicated, PUSCH transmission will be carried out using the PUSCH layers sounded for SRS transmission on port n on the SRS resources indicated by the SRI. Multiple repetitions, if configured, will then be directed towards the same TRP. The gNB can indicate multiple "SRI and NZP CSI-RS resource" pairs for repeated PUSCH transmission towards multiple TRPs. Each indicated "SRI and NZP CSI-RS resource" pair will correspond to a set of sounded PUSCH layers, similarly as in the single-TRP case, and these different sets of PUSCH layers can be used in different repetitions of the PUSCH transmission. This will enable different repetitions of the PUSCH transmission to be directed towards different TRPs.

<FIG> illustrates the operation of a wireless communication device <NUM> (e.g., a UE) and a network node (e.g., a base station <NUM> or gNB) in accordance with at least some aspects of at least some of the embodiments described above. Note that according to some embodiments, one or more of the steps in <FIG> can be performed, while other steps are optional. Note that this example is for two SRS resource groups/sets. However, this process is extendible to any number of SRS resource groups/sets.

As illustrated, the wireless communication device <NUM> receives, from the network node, a configuration of a first SRS resource group to be used for non-codebook based PUSCH transmission and a second SRS resource group to be used for non-codebook based PUSCH transmission (step <NUM>). In one embodiment (e.g., see Embodiment <NUM>), the first and second SRS resource groups are included in a single SRS resource set. In some embodiments, the single SRS resource set is associated with a higher layer parameter configured by the network to indicate, to the wireless communication device <NUM>, to use non-codebook based precoding for uplink transmissions associated with the single SRS resource set. In another embodiment (e.g., see Embodiment <NUM>), the first SRS resource group corresponds to a first SRS resource set, and the second SRS resource group corresponds to a second SRS resource set. In one embodiment, the first SRS resource set is associated with a first higher layer parameter configured by the network to indicate, to the wireless communication device <NUM>, to use non-codebook based precoding for uplink transmissions associated with the first SRS resource set, and the second SRS resource set is associated with a second higher layer parameter configured by the network to indicate, to the wireless communication device <NUM>, to use non-codebook based precoding for uplink transmissions associated with the second SRS resource set.

The wireless communication device <NUM> receives, from the network node, a configuration of a first NZP CSI-RS associated with the first SRS resource group and a second NZP CSI-RS associated with the second SRS resource group (step <NUM>). As described above, at least in some embodiments, the first NZP CSI-RS (and thus the first SRS resource group) is associated to a first TRP, and the second NZP CSI-RS (and thus the second SRS resource group) is associated to a second TRP.

The wireless communication device <NUM> receives a first NZP CSI-RS on the first NZP CSI-RS resource and a second NZP CSI-RS on the second NZP CSI-RS resource (step <NUM>). The wireless communication device <NUM> calculates a first precoder based on measurement of the first NZP CSI-RS and a second precoder based on measurement of the second NZP CSI-RS (step <NUM>).

The first and second precoders may then be used for a subsequent non-codebook based PUSCH transmission. More specifically, in this example, the wireless communication device <NUM> transmits layers of the first precoder on SRS resources from the first group and transmits layers of the second precoder on SRS resources from the second group (step <NUM>). Note that other variations of this step are described above. For sake of clarity, these other variations include, e.g., in some embodiments, the wireless communication device <NUM> transmits a first PUSCH or a first set of layers of a PUSCH on antenna ports corresponding to SRS resources in the first SRS group and transmits a second PUSCH or a second set of layers of a PUSCH on antenna ports corresponding to SRS resources in the second SRS group. The wireless communication device <NUM> subsequently receives a DCI scheduling the non-codebook based PUSCH transmission, where the DCI contains an SRI field indicating SRS resources from at least one of the first and second SRS groups (step <NUM>). The wireless communication device <NUM> transmits each PUSCH layer of the non-codebook based PUSCH transmission using the precoder layers associated with the SRS resources indicated in the SRI field (step <NUM>).

In some embodiments, the non-codebook based PUSCH transmission is comprised of a plurality of repetitions. Further, in some embodiments, if the SRI field indicates SRS resources from the first SRS resource group, the PUSCH transmission in a first sub-set of repetitions among the plurality of repetitions uses layers of the first precoder associated with the SRS resources in the first SRS group, responsive to the SRI field indicating SRS resources from the first SRS group. If the SRI field indicates SRS resources from the second SRS resource group, the PUSCH transmission in a second sub-set of repetitions among the plurality of repetitions uses layers of the second precoder associated with the SRS resources in the second SRS group, responsive to the SRI field indicating SRS resources from the second SRS resource group. If the SRI field indicates SRS resources from only the first SRS resource group, the PUSCH transmission in all of the plurality repetitions uses layers of the first precoder associated with the SRS resources in the first SRS group, responsive to the SRI field indicating SRS resources from only the first SRS resource group. If the SRI field indicates SRS resources from only the second SRS resource group, the PUSCH transmission in all of the plurality repetitions uses layers of the second precoder associated with the SRS resources in the second SRS group, responsive to the SRI field indicating SRS resources from only the second SRS resource group.

<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) are 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> communicate 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. The wireless communication device <NUM> implements all or part of the functionality of the wireless communication device <NUM> or UE described herein. 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 1506A, 1506B, 1506C, such as Node Bs, eNBs, gNBs, or other types of wireless Access Points (APs), each defining a corresponding coverage area 1508A, 1508B, 1508C. Each base station 1506A, 1506B, 1506C is connectable to the core network <NUM> over a wired or wireless connection <NUM>. A first UE <NUM> located in coverage area 1508C is configured to wirelessly connect to, or be paged by, the corresponding base station 1506C. A second UE <NUM> in coverage area 1508A is wirelessly connectable to the corresponding base station 1506A.

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 1506A, 1506B, 1506C, 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.

Claim 1:
A method performed by a wireless communication device (<NUM>) comprising:
receiving (<NUM>), from a network node (<NUM>), a configuration of a first Sounding Reference Signal, SRS, resource set to be used for non-codebook based Physical Uplink Shared Channel, PUSCH, transmission and a second SRS resource set to be used for non-codebook based PUSCH transmission;
receiving (<NUM>), from the network node (<NUM>), a configuration of a first Non-Zero Power, NZP, Channel State Information Reference Signal, CSI-RS, associated with the first SRS resource set and a second NZP CSI-RS associated with the second SRS resource set;
receiving (<NUM>) a request for transmitting data in PUSCH in a plurality of occasions, wherein the request comprises:
an indication that data transmission in PUSCH in the plurality of occasions is based on both the first SRS resource set and the second SRS resource set;
a first SRS resource indicator, SRI, associated with the first SRS resource set; and
a second SRI associated with the second SRS resource set; and
transmitting (<NUM>) the data in a first PUSCH in a first set of occasions according to the first SRI and a second PUSCH in a second set of occasions according to the second SRI, wherein the first PUSCH comprises at least one first SRS resource according to the first SRI and the second PUSCH comprises at least one second SRS resource according to the second SRI.