Patent Description:
LG Electronics, R1-<NUM> relates to rate matching for NR from MIMO perspective. Qualcomm Incorporated, R1-<NUM> relates to PDSCH and PUSCH RE mapping and rate matching. InterDigital, Inc. , R1-<NUM> relates to CSI acquisition in NR.

Aspects of the present invention are provided in the independent claims. Preferred embodiments are provided in the dependent claims.

Certain aspects provide a method for wireless communication by a user equipment (UE), according to claim <NUM>.

Certain aspects provide a method for wireless communication by a network entity, according to claim <NUM>.

Certain aspects of the present disclosure also provide various apparatus, according to claims <NUM> and <NUM>, performing the operations described above.

Aspects of the present disclosure present disclosure provide apparatus, methods, processing systems, and computer readable mediums for rate matching of non-zero power (NZP) channel state information reference signal (CSI-RS) resources for channel or interference measurement in multiple transmit receive point (multi-TRP) scenarios.

For example, the wireless communication network <NUM> may be a New Radio (NR) or <NUM> network. For example, BSs <NUM> may perform operation of <FIG> to configure a UE <NUM> to perform rate matching in accordance with the operations of FIG.

As illustrated in <FIG>, the wireless network <NUM> may include a number of base stations (BSs) <NUM> and other network entities. A BS may be a station that communicates with user equipments (UEs). Each BS <NUM> may provide communication coverage for a particular geographic area. In 3GPP, the term "cell" can refer to a coverage area of a Node B (NB) and/or a Node B subsystem serving this coverage area, depending on the context in which the term is used. In NR systems, the term "cell" and next generation NodeB (gNB), new radio base station (NR BS), 5GNB, access point (AP), or transmission reception point (TRP) may be interchangeable. In some examples, the base stations may be interconnected to one another and/or to one or more other base stations or network nodes (not shown) in wireless communication network <NUM> through various types of backhaul interfaces, such as a direct physical connection, a wireless connection, a virtual network, or the like using any suitable transport network.

Some UEs may be considered Internet-of-Things devices, which may be narrowband Internet-of Things devices.

In some examples, access to the air interface may be scheduled, wherein a. A scheduling entity (e.g., a base station) allocates resources for communication among some or all devices and equipment within its service area or cell.

<FIG> illustrates example components of BS <NUM> and UE <NUM> (as depicted in <FIG>), which may be used to implement aspects of the present disclosure. For example, antennas <NUM>, processors <NUM>, <NUM>, <NUM>, and/or controller/processor <NUM> of the UE <NUM> and/or antennas <NUM>, processors <NUM>, <NUM>, <NUM>, and/or controller/processor <NUM> of the BS <NUM> may be used to perform the various techniques and methods described herein.

In NR, a synchronization signal/physical broadcast channel (SS/PBCH) block is transmitted (also referred to as a synchronization signal block (SSB)). The SS/PBCH block includes a PSS, a SSS, and a two symbol PBCH. The SS/PBCH block can be transmitted in a fixed slot location, such as the symbols <NUM>-<NUM> as shown in <FIG>. The PBCH carries some basic system information, such as downlink system bandwidth, timing information within radio frame, SS burst set periodicity, system frame number, etc. The SS/PBCH blocks may be organized into SS bursts to support beam sweeping.

Real-world applications of such sidelink communications may include public safety, proximity services, UE-to-network relaying, vehicle-to-vehicle (V2V) communications, Internet of Everything (IoE) communications, Internet-of-Things communications, mission-critical mesh, and/or various other suitable applications.

Advanced systems support multiple input multiple output (MIMO) communications via deployments with enhanced multiple transmit-receiver points (TRPs) and/or TRPs with multiple antenna panels.

Some enhancements on multi-TRP/multi-panel transmission include improved reliability and robustness with both ideal and non-ideal backhaul via various mechanisms, such as specifying downlink control signaling enhancement(s) for efficient support of non-coherent joint transmission (NCJT). Enhancements on uplink control signaling and reference signal(s) for non-coherent joint transmission may also be specified.

In some cases, for multi-TRP scenarios, different configurations exist for NR downlink channel reception. For example, a single NR-PDCCH may schedule a single NR-PDSCH, where separate layers are transmitted from separate TRPs. As another example, multiple NR-PDCCHs may each schedule a respective NR-PDSCH, where each NR-PDSCH is transmitted from a separate TRP. In the case of a single NR-PDCCH scheduling a single NR-PDSCH, each layer may be transmitted from all TRPs jointly, in a manner that is transparent to a standard specification. Various CSI feedback details for the above cases may be considered separately, for each case.

The use of non-zero power (NZP) CSI-RS resources is defined in NR, as a set of NZP CSI-RS port(s) mapped to a set of REs within a frequency span (time duration) which can be measured at least to derive a CSI. Multiple NZP CSI-RS resources can be configured for a UE, for example, for supporting multi-TRP and multiple beamformed CSI-RS based operations. Each NZP CSI-RS resource, at least for multi-TRP, can have a different number of CSI-RS ports.

In current systems, however, configurations may be limited, for example, such that all CSI-RS resources across all CSI-RS resource sets of a specific CSI resource configuration have the same number of ports. This limitation may arise in cases where only one codebook can be configured in each report configuration.

<FIG> illustrates a high level view of a current CSI framework. For Periodic and semi-persistent report configurations, each resource configuration contains only one CSI-RS resource set. For aperiodic report triggering, each code point in the DCI can be associated with multiple report configurations, each report configuration associated with a resource configuration which may contain multiple CSI-RS resource sets (one of which is triggered).

In current systems, a UE is expected to rate match PDSCH around NZP CSI-RS resources for channel estimation or interference not used for mobility (RRM), as well as ZP CSI-RS resources. As used herein, the term rate matching generally refers to the basic function of matching the number of bits in a transport block (TB) to the number of bits that can be transmitted in the given resource allocation. In current systems, a UE is not expected to rate match PDSCH when the PDSCH transmission collides with an NZP CSI-RS resource for radio resource management (RRM) or CSI interference measurement (CSI-IM) resources.

One challenge for scenarios of multi-TRP deployments with a non-ideal backhaul (NIB), is that the TRPs have relaxed requirements for backhaul exchange of scheduling information and synchronization. This may result in the following problem. When a first TRP triggers an Aperiodic NZP-CSI RS resource for channel or interference measurement (IM) estimation to a UE, another TRP may schedule a PDSCH to this same UE on colliding time/frequency resources. This situation may result from the NIB not allowing enough time for the TRPs to collaborate (share information) in order to perform rate matching correctly. Unfortunately, the UE may assume that rate-matching has happened when, in fact, it has not, leading effectively to "PDSCH puncturing" due to the collision.

Aspects of the present disclosure, however, may address this scenario by providing for configurable PDSCH rate matching behavior, for example, for NZP CSI-RS resources for channel or interference measurement purposes in multi-TRP scenarios. In some cases, a network may be allowed to configure NZP CSI RS resources for channel or interference measurement for which the UE is not expected to perform rate matching around PDSCH.

<FIG> illustrates example operations <NUM> for wireless communications by a user equipment (UE) to perform rate matching based on a signaled behavior, in accordance with aspects of the present disclosure. For example, operations <NUM> may be performed by a UE <NUM> shown in <FIG> and <FIG>.

Operations <NUM> begin, at <NUM>, by receiving signaling indicating rate matching behavior for processing a physical downlink shared channel (PDSCH) configured with a first quasi co-location association and transmitted from a first transmission reception point (TRP) that potentially collides with NZP RS configured with a second quasi co-location association and transmitted from a second TRP using one of the resource sets. At <NUM>, the UE processes the PDSCH transmission, wherein the processing comprises deciding whether or how to perform rate matching around the NZP RS based on the rate matching behavior.

<FIG> illustrates example operations <NUM> for wireless communications by a network to signal a UE to perform rate matching according to a particular rate matching behavior, in accordance with aspects of the present disclosure. For example, operations <NUM> may be performed by a BS/gNB <NUM> shown in <FIG> and <FIG> to configure a UE to perform rate matching according the operations of <FIG> described above.

Operations <NUM> begin, at <NUM>, by determining a rate matching behavior for a UE for processing a physical downlink shared channel (PDSCH) configured with a first quasi co-location association and transmitted from a first transmission reception point (TRP) that potentially collides with one or more types of NZP RS configured with a second quasi co-location association and transmitted from a second TRP using one of the resource sets. The one or more types of NZP RS may be CSI-RS for various purposes, such as IM or RRM, or NZP RS for positioning or tracking purposes. At <NUM>, the network entity signals the rate matching behavior to the UE.

As noted above, the techniques presented herein may allow a network to configure NZP CSI RS resources for channel or interference measurement for which the UE is not currently expected to PDSCH rate match around. The signaling of a rate matching behavior may be accomplished in various manners.

For example, in a radio resource control (RRC)-based solution, each NZP CSI-RS resource for channel or interference purposes may have an RRC parameter or "flag" which controls whether the UE is supposed to rate match or not.

This flag may be allowed to be configured as 'Not-Rate-Match', for example, when this CSI RS resource is configured from a non-serving cell. This may make sense, for example, if the decision of transmitting PDSCH and transmitting a CSI RS is happening at the same scheduling unit (e.g., the serving TRP). In this case, there may be no problem (as the serving TRP may schedule accordingly).

In some cases, this flag may be optionally configured, with a UE configured to perform a default behavior if it is not signaled this flag. For example, default behavior may be the "legacy" behavior of NR rel-<NUM>, to rate match PDSCH around NZP CSI RS, otherwise if configured it would mean `Not-Rate-Match.

In some cases, this flag may only be allowed to be configured for NZP CSI RS resources configured aperiodically. In some cases, this flag may only be allowed to be configured for resources that are supposed to be used for interference measurement.

For any aperiodic NZP CSI RS resource (either channel or interference purposes) configured by a non-serving cell, the UE may not be expected to rate match PDSCH. This may be similar to treatment of NZP CSI RS resources for radio resource management (RRM). The network should be allowed to configure NZP CSI RS resources for channel or interference measurement for which the UE is not expected to PDSCH rate match around them.

In the invention as claimed, there is a semi-static configuration of a list which contains, for each cell-ID, (or quasi-colocation "QCL" association), a corresponding rate matching behavior, that indicates how a UE should perform rate matching if a CSI RS is transmitted from this cell-ID or QCL.

As an alternative to RRC-based solutions, in DCI-based solutions, each code point of the aperiodic triggering list may be associated with a list of bits of the size of the NZP CSI RS resource triggered by this code point. These bits, in effect, signal to the UE whether or not it should rate match around the corresponding CSI RS resources.

In some cases, additional bits in the scheduling DCI signal may be related to PDSCH rate matching of NZP CSI RS resources, for example, the aperiodic CSI RS resources appearing inside the same time/frequency resources as the schedule PDSCH. In some cases, for all the resource elements of indicated OFDM symbols (e.g., PDSCH may appear on symbol <NUM>-<NUM>, but another TRP transmits on symbol <NUM>, due to synchronization uncertainty of +-<NUM> symbol), the scheduling TRP may ask the UE to rate match certain symbols (e.g., <NUM>, <NUM>, and <NUM>) to avoid collision with PDSCH. On the other hand, the scheduling TRP may ask that the UE not rate match any symbol, since the scheduling TRP may not know whether this CSI RS is also triggered or not in this slot.

In a media access control (MAC) control element (MAC-CE) based solution, a UE may be configured, via a MAC-CE, with the rate matching behavior of each aperiodic NZP CSI RS resource in each triggering state. In some cases, a MAC-CE may configure a list which contains, for each cell-ID, (or QCL association), the corresponding rate matching behavior, if a CSI RS is transmitted from this cell-ID or QCL.

In some cases, due to time-domain synchronization uncertainty, the network may be allowed to configure a rate matching behavior which extends longer in time around NZP CSI RS resources for channel or interference measurement. For example, a scheduling TRP may want to avoid PDSCH collisions with CSI RS resources from another TRP in certain scenarios, for example, for users with strict reliability requirements. In such cases, a scheduling TRP may configure a time-domain window (a measurement gap) around a CSI RS resource, where this window is configured per CSI RS resource.

If such a window is not configured, a default assumption may be that the UE rate matches according to the legacy behavior. In some cases, such a window may be allowed to be configured for one type of NZP RS, but not another. For example, such a window may be allowed to be configured for NZP CSI RS resources for interference measurement, but not for CSI RS resources for channel measurement. In some cases, such a window may be configured per cell-ID, or per QCL assumption. In such cases, rate matching behavior may be inherited for any NZP CSI RS resource associated with this cell-ID or QCL.

According to one solution, bits may be added in the DCI to signal a window for which rate matching behavior applies. For example, each DCI code point may point to a different size of measurement gap. For <NUM> bits of DCI, the rate matching behavior (and window) may be applied as follows:.

As noted above, the rate matching techniques may be applied to NZP RS used for a variety of different purposes, such as NZP RS used for channel tracking purposes (TRS) or NZP RS used for positioning purposes (PRS).

The rate matching techniques described above may or may not be applied in specific multi-TRP scenarios. For example, in multi-TRP cases where it is likely that TRPs are well-synchronized on an "ideal" backhaul, it may not be as critical to allow the above solutions. Examples of these multi-TRP cases include:.

On the other hand, for multi-TRP cases where it is likely that TRPs are not well-synchronized (e.g., a "non-ideal" backhaul, it may be more important that the above solutions be allowed. Examples of these multi-TRP cases include:.

In some cases, the rate matching techniques described herein may be applied to scenarios of PDSCH slot aggregation. For example, rate matching behavior may be indicated to specify whether rate matching is done only on the first slot, or all slots in an aggregated transmission. Whether or not to apply rate matching, and on which slots, may depend on an actual configured periodicity. In general, depending on the periodicity, which instance of CSI RS is rate-matched may depend on whether there is PDSCH slot aggregation. For example, if CSI RS is configured in every slot, when there is PDSCH slot aggregation, the CSI RS may be rate matched only on a subset of the slots (e.g., first slot).

In some cases, the rate matching behavior to apply in which slots may be explicitly indicated. For example, this explicit signaling may be provided via MAC CE or RRC signaling. For example, RRC signaling may configure several sets of CSI-RS applicability for rate matching where each set covers all slots and a DCI transmission may be used to indicate which set to use. Signaling may also be provided via DCI, for example, via a bitmap used to indicate the slots for rate matching applicability. In some cases, a combination of these (MAC CE, RRC, and/or DCI) signaling approaches may be used to indicate the slots for rate matching applicability.

Generally, where there are operations illustrated in figures, those operations may have corresponding counterpart means-plus-function components. For example, various operations shown in <FIG> and <FIG> may be performed by various processors shown in <FIG>.

For example, instructions for performing the operations described herein and illustrated in <FIG> and/or <NUM>.

Claim 1:
A method of wireless communications by a user equipment, UE, (<NUM>) comprising:
receiving (<NUM>) radio resource control, RRC, signaling of at least one parameter indicating whether or how to perform rate matching for processing a physical downlink shared channel, PDSCH, associated with a first quasi co-location, QCL, association and transmitted from a first transmission reception point, TRP, that potentially collides with one or more non-zero power, NZP, reference signals, RS, associated with a second QCL association and transmitted from a second TRP, wherein each NZP RS is transmitted on one or more NZP resources within a NZP RS resource set, and wherein the signaling comprises a semi-static configuration of a list that indicates, for each of a plurality of cell-identifiers, IDs, or QCL associations, whether or how to perform rate matching for NZP RS transmitted from that cell-ID or QCL association; and
processing (<NUM>) the PDSCH transmission, wherein the processing comprises deciding whether or how to perform rate matching around the NZP RS based on the signaling.