Patent Description:
In Long Term Evolution (LTE), until Release <NUM>, all Reference Signals (RSs) that a User Equipment (UE) uses for Channel State Information (CSI) calculation, such as Cell specific Reference Signal (CRS) and CSI Reference Signal (CSI-RS), were non-precoded such that UE is able to measure the raw channel and calculate CSI feedback including preferred precoding matrix based on that the RS. As the number of Transmit (Tx) antenna ports increases, the amount of feedback becomes larger. In LTE Release-<NUM>, when closed loop precoding with 8Tx was introduced, a two-stage precoder approach was introduced where UE first selects a wideband coarse precoder and then selects a second precoder per subband. Another possible approach is that network beamforms the CSI-RS and UE calculates CSI feedback using the beamformed CSI-RS. This approach was adopted in LTE Release <NUM> as one option for the Full Dimension Multi-Input Multi-Output (FD-MIMO) operation as described in the next section. Improvements in reference signals are needed.

Document "<NPL>, refers to remaining details of CSI measurement. The following observations were made. Observation <NUM>: Option <NUM> provides a simple port indication for non-PMI feedback but limits the gNB to perform rank-nested precoding. Observation <NUM>: Option <NUM> is more flexible and allows the gNB to use non-rank nested precoding, at the cost of slightly increased RRC signalling overhead. Observation <NUM>: gNB can turn off UE rank adaptation in CSI report so as to only receive a CQI for the pre-scheduled rank by configuring rank restriction. Observation <NUM>: It is natural that the DCI indication for the subset of NZP CSI-RS resource(s) for channel or interference measurement is the same as the aperiodic CSI triggering. Observation <NUM>: CSI-IM with (<NUM>,<NUM>) pattern could provide better interference averaging than (<NUM>,<NUM>) pattern. The following proposals were made. Proposal <NUM>: Support defining a separate bitmap for port index indication per rank for non-PMI feedback. Proposal <NUM>: Use the same mechanism of aperiodic CSI triggering for indicating the subset of NZP CSI-RS resource(s) for channel and the subset of NZP CSI-RS resource(s) for interference measurement. Clarify that "subsets" in previous agreement refers to "sets" in the CSI framework. Proposal <NUM>: Clarify that a codepoint of the CSI request field can trigger one or more CSI report setting, where for each CSI report setting there can be one or more of (i) an aperiodic NZP-CSI RS set for channel measurement, (ii) an aperiodic NZP CSI-RS set for interference measurement, (iii) an aperiodic CSI-IM. Proposal <NUM>: Support joint activation of SP CSI-IM in the same message that activates a SP NZP CSI-RS resource set. Proposal <NUM>: Support (<NUM>,<NUM>) for ZP CSI-RS as IMR for better interference averaging. Proposal <NUM>: UE shall assume for CQI calculation that interferences measured on each linked CSI-IM and NZP CSI-RS are accumulated, where UE shall account for Pc of NZP CSI-RS resource in the accumulation. Proposal <NUM>: The bit width N of the CSI request field in non-fallback DCI is RRC configurable in the range {<NUM>,<NUM>,<NUM>,. Nmax } where Nmax = <NUM> bits.

Document "<NPL>, refers to remaining details for CSI acquisition in NR. The following proposals were made. Proposal <NUM>: NZP-CSI-RS is supported as IMR for interference emulation but strive to reduce the interference emulation complexity. Proposal <NUM>: Rate-match around a downlink channel if it collides with a CSI-RS irrespective of the CSI-RS types. Proposal <NUM>: A common DCI is used to indicate activated CSI-RSs for PDSCH rate-matching in a slot.

Document "<NPL>, refers to the need for new MAC CEs for UL and DL beam management. The following observation was made. Observation <NUM>: From RAN2 perspective, it seems no impact on RAN2 except RRC signaled configuration and DRX operation. The following proposals were made. Proposal <NUM>: Introduce an activation/deactivation MAC CE for DL beam management indicating map the code points of the CSI request field to a set of A CSI-RS resource configured by RRC signalling. Proposal <NUM>: Introduce a MAC CE for DL beam management indicating activation/deactivation of SP CSI-RS resources sets configured by RRC signalling. Proposal 2bis: The MAC CE for SP CSI-RS resources activation/deactivation includes <NUM> bit per RRC configured SP CSI-RS resource set a semi-persistent CSI resource set (<NUM> means active, <NUM> means inactive). Proposal <NUM>: Introduce a MAC CE for DL beam management indicating activation/deactivation of SP CSI measurements (i.e. identified with a csi-MeasId) configured by RRC signalling. Proposal 3bis: The MAC CE for activation/deactivation SP CSI measurements includes <NUM> bit per csi-MeasId (<NUM> means active, <NUM> means inactive). Proposal <NUM>: Introduce a MAC CE to indicate QCL of DMRS ports of UE-specific PDCCH and SS block or P/SP CSI-RS resources (see the proposed format above). Proposal <NUM>: Introduce a MAC CE for activation/deactivation SP SRS resources set MAC CE for UL beam management. Proposal 5bis: RAN2 is suggested to adopt a certain MAC CE format with a new LCID for activation/deactivation SP SRS resource set. Proposal <NUM>: Introduce a certain MAC CE for UL serving beam indication.

Parts of document <CIT> constitute prior art under Article <NUM>(<NUM>) EPC and disclose a user equipment (UE) including a receiver that receives, from a base station (BS), Zero Power (ZP) Channel State Information-Reference Signal (CSI-RS) resource configuration information and a ZP CSI-RS. The ZP CSI-RS is transmitted as a periodic ZP CSI-RS, a semi-persistent ZP CSI-RS, or an aperiodic ZP CSI-RS. When the ZP-CSI-RS is transmitted as the periodic ZP CSI-RS or the semi-persistent ZP CSI-RS, the ZP CSI-RS resource configuration information designates periodicity and a timing offset for the periodic ZP CSI RS or the semi-persistent ZP-CSI-RS. The receiver receives the ZP CSI-RS based on a ZP CSI RS resource specified using the periodicity and the timing offset. When the ZP CSI-RS is transmitted as the aperiodic ZP CSI-RS, the receiver receives DCI that triggers the aperiodic ZP CSI-RS. The receiver receives the ZP CSI-RS based on a ZP CSI- RS resource specified using the DCI.

Systems and methods for activating a Semi-Persistent (SP) Zero Power (ZP) Channel State Information Reference Signal (CSI-RS) are provided.

According to the present disclosure, methods, a wireless device and a base station according to the independent claims are provided. Developments are set forth in the dependent claims.

In LTE, until Release <NUM>, all reference signals (RSs) that UE uses for Channel State Information (CSI) calculation, such as Cell specific Reference Signal (CRS) and CSI Reference Signal (CSI-RS), were non-precoded such that UE is able to measure the raw channel and calculate CSI feedback including preferred precoding matrix based on that the RS. As the number of Transmit (Tx) antenna ports increases, the amount of feedback becomes larger. In LTE Release-<NUM>, when closed loop precoding with 8Tx was introduced, a two-stage precoder approach was introduced where UE first selects a wideband coarse precoder and then selects a second precoder per subband. Another possible approach is that network beamforms the CSI-RS and UE calculates CSI feedback using the beamformed CSI-RS. This approach was adopted in LTE Release <NUM> as one option for the
Full Dimension Multi-Input Multi-Output (FD-MIMO) operation as described in the next section.

Release <NUM> FD-MIMO specification in LTE supports an enhanced CSI reporting called Class B CSI for beamformed CSI-RS. Therein, an LTE RRC_CONNECTED UE, i.e. a UE connected to an LTE network, can be configured with K CSI-RS resources, where each resource may correspond to a beam (where <NUM> < K ≤ <NUM>) where each CSI-RS resource can consist of <NUM>, <NUM>, <NUM> or <NUM> CSI-RS ports. For CSI feedback purposes, a CSI-RS Resource Indicator (CRI) was introduced in addition to Precoding Matrix Indicator (PMI), Rank Indicator (RI) and Channel Quality Indicator (CQI). As part of the CSI, the UE reports the CSI-RS index (CRI) to indicate the preferred beam, where the CRI is wideband. Other CSI components such as RI/CQI/PMI are based on legacy codebook (i.e. Release <NUM>) and CRI reporting periodicity is an integer multiple of the RI reporting periodicity. An illustration of beamformed CSI-RS is given in <FIG>. In the figure, the UE reports CRI=<NUM> which corresponds to RI/CQI/PMI being computed using `Beamformed CSI-RS <NUM>'.

For Release <NUM> eFD-MIMO, non-periodic beamformed CSI-RS with two different sub-flavors was introduced. The two sub-flavors are aperiodic CSI-RS and semi-persistent CSI-RS. In both these sub-flavors, the CSI-RS resources are configured for the UE as in Release <NUM> with K CSI-RS resources, and a Medium Access Control (MAC) Control Element (CE) activation of N out of the K CSI-RS resources (N ≤ K) is specified. Alternatively stated, after the K CSI-RS resources are configured to be aperiodic CSI-RS or semi-persistent CSI-RS, the UE waits for MAC CE activation of N out of the K CSI-RS resources. In the case of aperiodic CSI-RS, in addition to MAC CE activation, a Downlink Control Information (DCI) trigger is sent to the UE so that one of the activated CSI-RS resources is selected by the UE for CSI computation and subsequent reporting. In the case of semi-persistent CSI-RS, once the CSI-RS resources are activated by MAC CE, the UE can use the activated CSI-RS resources for CSI computation and reporting.

The MAC CE activation/deactivation command is specified in Section <NUM> of TS36. <NUM> where the specification text is reproduced below.

The network may activate and deactivate the configured CSI-RS resources of a serving cell by sending the Activation/Deactivation of CSI-RS resources MAC control element described below. The configured CSI-RS resources are initially deactivated upon configuration and after a handover.

The Activation/Deactivation of CSI-RS resources MAC control element is identified by a MAC PDU subheader with a Logical Channel IDentifier (LCID) as specified in table <NUM>. <NUM>-<NUM>. It has variable size as the number of configured CSI process (N) and is defined in <FIG>. Activation/Deactivation CSI-RS command is defined in <FIG> and activates or deactivates CSI-RS resources for a CSI process. Each CSI process is associated with one or more CSI-RS resource and one or more CSI-Interference Measurement (CSI-IM) resources. Activation/Deactivation of CSI-RS resources MAC control element applies to the serving cell on which the UE receives the Activation/Deactivation of CSI-RS resources MAC control element.

The Activation/Deactivation of CSI-RS resources MAC control elements is defined as follows:.

For NR, all reference signals may be beamformed. In NR, the synchronization sequences (SS), both primary (NR-PSS) and the secondary (NR-SSS), and Physical Broadcast Channel (PBCH), which includes Demodulated Reference Signals (DMRSs), constitute a so called SS Block. An RRC_CONNECTED UE trying to access a target cell should assume that the SS Block may be transmitted in the form of repetitive bursts of SS Block transmissions (denoted as "SS Burst"), wherein such a burst consists of a number of SS Block transmissions following close after each other in time. Furthermore, a set of SS Bursts may be grouped together (denoted "SS Burst Set"), where the SS Bursts in the SS Burst Sets are assumed to have some relation to each other. Both SS Bursts and SS Burst Sets have their respective given periodicity. As shown in <FIG>, in single beam scenarios, the network could configure time-repetition within one SS Burst in a wide beam. In multi-beam scenarios, at least some of these signals and physical channels (e.g. SS Block) would be transmitted in multiple beams, which could be done in different manners depending on network implementation, as shown in <FIG>.

Which of these three alternatives to implement is a network vendor choice. That choice depends on the tradeoff between i) the overhead caused by transmitting periodic and always on narrow beam sweepings vs. ii) the delays and signaling needed to configure the UE to find a narrow beam for Physical Downlink Shared Channel (PDSCH) and Physical Downlink Control Channel (PDCCH). The implementation shown in the upper figure within <FIG> prioritizes i), while the implementation shown in the bottom figure within <FIG> prioritizes ii). The figure in the middle case is an intermediate case, where a sweeping of wide beams is used. In that case, the number of beams to cover the cell is reduced, but in some cases an additional refinement is needed for narrow gain beamforming of PDSCH.

In NR, the following types of CSI reporting are supported:.

Generally, a CSI report setting contains the parameters associated with CSI reporting including the type of CSI reporting.

In NR, the following three types of CSI-RS transmissions are supported:.

In the case of aperiodic CSI-RS and/or aperiodic CSI reporting, the gNB RRC configures the UE with Sc CSI triggering states. Each triggering state contains the aperiodic CSI report setting to be triggered along with the associated aperiodic CSI-RS resource sets.

When the DCI contains a CSI request field with N bits, aperiodic CSI-RS and/or aperiodic CSI reporting can be triggered according to the following conditions:.

In NR, the size of the CSI request field is configurable and can take on values of N={<NUM>, <NUM>, <NUM>,.

In the case of semi-persistent CSI-RS, the gNB first RRC configures the UE with the semi-persistent CSI-RS resources. The semi-persistent CSI-RS resource or semi-persistent CSI-RS resource set is then activated via MAC CE.

Quasi co-location (QCL) is a natural way to describe the relation between two different signals originating from the same Transmission Reception Point (TRP) and that can be received using the same spatial receiver parameters. As an example, the UE should be able to assume it can use the same receive beam when receiving the two difference signals that have spatial QCL. The spatial QCL relations between different types of reference RS and target RS are shown in the table below. Also, shown in the table are the associated signaling methods. The last column of the table simply indicates that the target and reference RSs can belong to different component carriers (CCs) and different bandwidth parts (BWPs).

For measurements on channel and interference, two types of resources are defined, non-zero power (NZP) CSI-RS and CSI-IM. NZP CSI-RS is transmitted by a network node (or gNB) for UEs to estimate the downlink channels to the network node. While for CSI-IM, a resource, as given by a set of REs, is indicated by the network for the UE to perform interference measurements upon.

Zero-power (ZP) CSI-RS resources can also be configured to the UEs. As its name implies, the gNB does not transmit anything on the Resource Elements (REs) occupied by the ZP CSI-RS configured to the UE. ZP CSI-RS resources are configured to the UEs for three purposes. Firstly, ZP CSI-RS can be configured to a UE in order to protect NZP CSI-RS transmissions from one or more neighboring cells. Secondly, ZP CSI-RS can be used for the purposes of indicating whether or not PDSCH is mapped to CSI-IM. Thirdly, (aperiodic) ZP CSI-RS can be used to indicate that the UE shall rate match, e. PDSCH resource mapping, its PDSCH around a (beamformed) NZP CSI-RS intended for another UE to measure upon. It is mainly for this third purpose the aperiodic ZP CSI-RS field in the Downlink (DL) DCI is comprised.

In a typical use case, the network will not transmit anything on the REs occupied by the CSI-IM, so the UE can measure the inter-cell interference thereon. To indicate that the PDSCH is not mapped to the REs occupied by the CSI-IM, ZP CSI-RS is typically configured to overlap with the CSI-IM. As the CSI-IM and ZP CSI-RS resources typically overlap, the CSI-IM is colloquially referred to as a ZP CSI-RS based interference measurement resource (IMR). The IMR can be aperiodic (AP IMR), semi-persistent (SP IMR) or periodic IMR (P IMR). Note that in NR, an NZP CSI-RS can also be configured as an IMR.

It should be noted that ZP CSI-RS used for the purposes of indicating whether or not PDSCH is mapped to CSI-IM is configured independently. To illustrate the reasoning for this, consider the multiple TRP example in <FIG>. In this example, the UE is currently being served by TRP1 and receives PDSCH from TRP1. TRP2 is a potential future serving cell. For CSI measurements corresponding to TRP1, the UE is configured with NZP CSI-RS1 and CSI-IM1 to measure the desired channel from TRP1 and the interference from TRP2, respectively. For CSI measurements corresponding to TRP2, the UE is configured with NZP CSI-RS2 and CSI-IM2 to measure the desired channel from TRP2 and the interference from TRP1, respectively. When the UE measures CSI corresponding to TRP2, the PDSCH from TRP1 that is currently received by the UE serves as the interference. Hence, in this case, PDSCH mapping should be allowed on REs corresponding to CSI-IM2 and a ZP CSI-RS does not need to be independently configured to overlap with CSI-IM2. For this reason, ZP CSI-RS and CSI-IM is configured independently. Currently, NR supports aperiodic ZP CSI-RS (AP ZP CSI-RS) and periodic ZP CSI-RS (P ZP CSI-RS).

In the rest of this document, a SP CSI-RS used for channel measurement purposes (also known as channel measurement resource or CMR) is also referred to as SP CMR.

In NR, the following was agreed to be supported for pairing a channel measurement resource (CMR) and an IMR:.

For ZP CSI-RS based IMR (i.e., CSI-IM), following combinations of P/SP/AP CMR and IMR are supported.

As indicated by the agreement above, for CSI acquisition, semi-persistent channel measurement resource (CMR) must be used together with semi-persistent interference measurement resource (IMR). That is, a SP CMR cannot be used with a P IMR or an AP IMR and can only be used with a SP IMR.

There currently exist certain challenge(s). It is still open on how to indicate whether or not PDSCH is mapped to resources of SP IMR.

One option is to use different MAC CEs for the following:.

However, this can result in large signaling overhead. In <CIT>, MEDIUM ACCESS CONTROL (MAC) SIGNALING FOR REFERENCE SIGNAL ACTIVATION AND CONTROL IN WIRELESS COMMUNICATION NETWORKS, a MAC CE signaling mechanism is presented where the same message can be used to activate at least one of SP CSI-RS for channel measurement, SP IMR for interference measurement, and SP CSI reporting on PUCCH. However, <CIT>, MEDIUM ACCESS CONTROL (MAC) SIGNALING FOR REFERENCE SIGNAL ACTIVATION AND CONTROL IN WIRELESS COMMUNICATION NETWORKS, does not address the open problem of how to signal whether or not PDSCH is mapped to the SP IMR above while keeping the signaling overhead down.

Another issue is that only aperiodic and periodic ZP CSI-RS is supported for NR, this implies that semi-persistent CSI-RS of other UEs and/or cells must either be protected by periodic ZP CSI-RS, in which the PDSCH will be rate matched around even when the SP NZP CSI-RS is deactivated, or, using aperiodic ZP CSI-RS, which removes the possibility to indicate rate matching around aperiodic ZP CSI-RS. Neither of these options is attractive.

Certain aspects of the present disclosure and their embodiments may provide solutions to the aforementioned or other challenges. For rate matching around a UE's own SP CSI-IM, A solution where semi-persistent ZP CSI-RS resources are used to indicate whether or not PDSCH is mapped to semi-persistent IMR (or SP CSI-IM). Since both SP CSI-RS and SP CSI-IM are activated via MAC CE in NR, it would be appropriate to use the same MAC CE that activates a SP CSI-RS and SP CSI-IM to also activate SP ZP CSI-RS. Optionally, the same MAC CE can also be used to activate an SP CSI.

Systems and methods for activating a Semi-Persistent (SP) Zero Power (ZP) Channel State Information Reference Signal (CSI-RS) are provided. In some embodiments, a method performed by a wireless device includes for activating SP ZP CSI-RS includes receiving, from a network node, a control message that indicates the activation of one or more SP ZP CSI-RS resources; and activating, based on the control message, the one or more SP ZP CSI-RS resources. In this way, ZP CSI-RS may be used for rate matching around other wireless devices and a SP ZP CSI-RS resource may be activated without activating any Non-Zero Power (NZP) CSI-RS, CSI-Interference Measurement (CSI-IM), or CSI reporting for the wireless device.

For rate matching around other UEs' SP CSI-IM, a separate MAC CE message other than the one for SP CSI-RS, SP CSI-IM, or SP CSI reporting is used to activate/deactivate SP ZP CSI-RS resources.

Alternatively, a common SP CSI-IM may be configured for all UEs and a periodic ZP CSI-RS may be configured with the same resource as the SP CSI-IM without any additional dynamic signaling for rate matching around SP CSI-IM. In another option, a common SP ZP CSI-RS may be configured which is enable when at least one SP CSI reporting is activated and disabled when all SP CSI reporting are deactivated. The enabling and disabling can be done through MAC control messages.

Certain embodiments may provide one or more of the following technical advantage(s). For rate matching around a UE's own SP CSI-IM, an advantage of both embodiments may be that a signaling overhead is reduced when compared to using different MAC CE messages for activating SP CMR, SP IMR, SP ZP CSI-RS, and SP CSI reporting on PUCCH.

For rate matching around other UEs' SP CSI-IM, the embodiments allow either flexible rate matching with low resource overhead or simple signaling.

Additional information may also be found in the document(s) provided in the Appendix.

Note that, in the description herein, reference may be made to the term "cell;" however, particularly with respect to <NUM> NR concepts, beams may be used instead of cells and, as such, it is important to note that the concepts described herein are equally applicable to both cells and beams.

<FIG> illustrates one example of a cellular communications network <NUM> according to some embodiments of the present disclosure. In the embodiments described herein, the cellular communications network <NUM> is a Fifth Generation (<NUM>) New Radio (NR) network. In this example, the cellular communications network <NUM> includes base stations <NUM>-<NUM> and <NUM>-<NUM>, which in LTE are referred to as eNBs and 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 cellular communications network <NUM> also includes 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 base stations <NUM> (and optionally the low power nodes <NUM>) are connected to a core network <NUM>.

Various embodiments for activation and deactivation of SP-CSI reporting on PUSCH are described below. In this regard, <FIG> illustrates one example of the operation of a network node (e.g., a base station <NUM>) and a wireless device <NUM> for activating a PDSCH mapping rule in accordance with some embodiments of the present disclosure. As illustrated, the network node sends, to the wireless device <NUM>, a control message (e.g., a MAC CE) to activate a PDSCH mapping rule (step <NUM>). Then, the wireless device <NUM>, determines whether or not the PDSCH is mapped to resources of a SP IMR (step <NUM>). There are various embodiments discussed below.

<FIG> illustrates one example of the operation of a network node (e.g., a base station <NUM>) and a wireless device <NUM> for activating a Semi-Persistent, SP, Zero Power, ZP, Channel State Information Reference Signal, CSI-RS in accordance with some embodiments of the present disclosure. As illustrated, the network node sends, to the wireless device <NUM>, a control message (e.g., a MAC CE) that indicates activation of one or more a SP ZP CSI-RS resources (e.g., a bitmap) (step <NUM>). Then, the wireless device <NUM> activates the one or more SP ZP CSI-RS resources (step <NUM>). Similarly, the network node may optionally send, to the wireless device <NUM>, a control message (e.g., a MAC CE) that indicates deactivation of one or more a SP ZP CSI-RS resources (e.g., a bitmap) (step <NUM>). Then, the wireless device <NUM> deactivates the one or more SP ZP CSI-RS resources (step <NUM>). There are various embodiments discussed below.

<FIG> illustrates one example of the operation of a network node (e.g., a base station <NUM>) and a wireless device <NUM> for activating a Semi-Persistent, SP, Zero Power, ZP, Channel State Information Reference Signal, CSI-RS in accordance with some embodiments of the present disclosure. As illustrated, the network node sends, to the wireless device <NUM>, a configuration for SP CSI-IM resources where all other wireless devices (<NUM>) in a cell comprising the wireless device (<NUM>) receive the same configuration (step <NUM>). The wireless device <NUM> then determines whether to rate match, e.g., PDSCH resource map, around the SP CSI-IM resources (step <NUM>).

In NR, it is agreed that for CSI acquisition, semi-persistent channel measurement resource (CMR) must be used together with semi-persistent CSI-IM. However, it is still not decided how to indicate to the UE whether or not PDSCH is mapped to the REs occupied by the semi-persistent CSI-IM. One solution is to introduce semi-persistent ZP CSI-RS (SP ZP CSI-RS) resources which are configured to the UE independently from semi-persistent CSI-IM. Since both SP CSI-RS and SP CSI-IM are activated via MAC CE, it would be appropriate to use the same MAC CE that activates a SP CSI-RS and SP CSI-IM to also activate SP ZP CSI-RS. Optionally, the same MAC CE can also be used to activate a SP CSI report on PUCCH. One further benefit of introducing a SP ZP CSI-RS is that it allows the gNB to indicate rate matching around another UEs SP NZP CSI-RS, or, to protect a SP NZP CSI-RS of another cell.

As per 3GPP RAN1 agreements, a periodic reporting configuration can be linked to only a periodic RS configuration and semipersistent reporting can be linked to either a periodic or a semipersistent (P/SP) RS configuration. Some embodiments describe an RRC configuration which gives rate matching assumption for periodic and semipersistent reference signal configuration.

In the subsequent embodiments, two different ways of signaling for MAC CE activation of SP ZP CSI-RS for PDSCH resource mapping are provided. In these embodiments, the same MAC CE that is used to activate SP CMR and SP CSI-IM is used to activate SP ZP CSI-RS for resource mapping. This MAC CE message can also indicate whether or not PDSCH is mapped to semi-persistent CSI-IM. In some embodiments, this MAC CE can also activate SP CSI reporting on PUCCH.

An advantage of both embodiments may be that a signaling overhead is reduced when compared to using different MAC CE messages for activating SP CMR, SP CSI-IM, SP ZP CSI-RS, and SP CSI reporting on PUCCH.

In this Embodiment <NUM>, the linkage between SP CMR, SP CSI-IM, and SP ZP CSI-RS can be given in either MeasLinkConfig or ReportConfig for CSI reporting. Here, MeasLinkConfig and ReportConfig are RRC information elements (IE) representing measurement link configurations and reporting configurations, respectively. To indicate to the UE that PDSCH is not mapped to the resources of SP CSI-IM, all three entities (i.e., SP CMR, SP CSI-IM, and SP ZP CSI-RS) are present in either MeasLinkConfig or ReportConfig. To indicate to the UE that PDSCH is mapped to the resources of SP CSI-IM, only SP CMR and SP CSI-IM are present in either MeasLinkConfig or ReportConfig. Then, in the field description of either of these lEs, depending where the linkage ends up to be in final specification, it will be described that if SP ZP-CSI-RS is present, UE assumes SP ZP-CSI-RS for rate matching instead of CSI-IM. Each such linkage can be associated with an Identifier (ID) (henceforth referred to as measlD or reportID). Then, the activation of SP CMR, SP CSI-IM and/or SP ZP CSI-RS can be done by pointing only to either measlD or reportlD in a MAC CE.

In another variant of this embodiment, in addition to SP CMR, SP CSI-IM, and SP ZP CSI-RS, a joint activation of a SP CSI reporting on PUCCH is performed using the same MAC CE. In this variant, the SP CSI-RS used for CMR can be defined in an RRC configured parameter SP-CSI-RS Config. SP-CSI-RS Config can include the corresponding SP CSI-IM and a report ID corresponding to a ReportConfig. The ReportConfig contains the details of the SP CSI reporting on PUCCH to be activated. Depending on whether or not PDSCH is mapped to the corresponding SP CSI-IM, SP-CSI-RS config can also include SP ZP CSI-RS. To indicate to the UE that PDSCH is not mapped to the resources of SP CSI-IM, the SP ZP CSI-RS corresponding to the SP CSI-IM is included in the SP-CSI-RS config. To indicate to the UE that PDSCH is mapped to the resources of SP CSI-IM, the SP ZP CSI-RS corresponding to the SP CSI-IM is not included in the SP-CSI-RS config.

In yet another variant embodiment, the SP CMR, SP CSI-IM and the SP CSI reporting on PUCCH are defined in a MeasLinkConfig with a measlD. Depending on whether or not PDSCH is mapped to the corresponding SP CSI-IM, the MeasLinkConfig can also include SP ZP CSI-RS. To indicate to the UE that PDSCH is not mapped to the resources of SP CSI-IM, the SP ZP CSI-RS corresponding to the SP CSI-IM is included in MeasLinkConfig. To indicate to the UE that PDSCH is mapped to the resources of SP CSI-IM, the SP ZP CSI-RS corresponding to the SP CSI-IM is not included in MeasLinkConfig. In this variant of the embodiment, a MAC CE indicates the measID to jointly activate a given combination of SP CMR, SP CSI-IM, SP CSI reporting, and/or SP ZP CSI-RS.

In another variant of the embodiment, the SP CMR, SP CSI-IM, and the SP CSI reporting on PUCCH are defined in a ReportConfig with reportID. Depending on whether or not PDSCH is mapped to the corresponding SP CSI-IM, the ReportConfig can also include SP ZP CSI-RS. To indicate to the UE that PDSCH is not mapped to the resources of SP CSI-IM, the SP ZP CSI-RS corresponding to the SP CSI-IM is included in ReportConfig. To indicate to the UE that PDSCH is mapped to the resources of SP CSI-IM, the SP ZP CSI-RS corresponding to the SP CSI-IM is not included in ReportConfig. In this variant of the embodiment, a MAC CE then indicates the reportlD to jointly activate a given combination of SP CMR, SP CSI-IM, SP ZP CSI-RS, and SP CSI reporting.

In Embodiment <NUM>, a bit R1 in the MAC CE activating the SP CSI-IM indicates whether or not PDSCH is mapped to the SP CSI-IM.

In one detailed variant of this embodiment, the linkage between SP CMR, SP CSI-IM, and SP ZP CSI-RS can be given in either MeasLinkConfig or ReportConfig. In this embodiment, all three entities (i.e., SP CMR, SP CSI-IM, and SP ZP CSI-RS) are present in either MeasLinkConfig or ReportConfig. If the bit R1 is set to "<NUM>", then PDSCH is not mapped to the resources of SP CSI-IM and PDSCH is mapped around the resources in SP ZP CSI-RS. If R1 is set to "<NUM>", PDSCH is mapped to the resources of SP CSI-IM and the SP ZP CSI-RS defined in either MeasLinkConfig or ReportConfig is ignored. In this embodiment, the activation of SP CMR, SP CSI-IM and/or SP ZP CSI-RS can be done by pointing only to either measlD or reportlD in a MAC CE which also contains the dedicated bit R1.

In another detailed variant of this embodiment, in addition to SP CMR, SP CSI-IM, and SP ZP CSI-RS, a joint activation of a SP CSI reporting on PUCCH is performed using the same MAC CE. In this variant, the SP CSI-RS used for CMR can be defined in an RRC configured parameter SP-CSI-RS Config. SP-CSI-RS config can include the corresponding SP CSI-IM, SP ZP CSI-RS and a report ID corresponding to a ReportConfig. The report config contains the details of the SP CSI reporting on PUCCH to be activated. If the bit R1 is set to "<NUM>", then PDSCH is not mapped to the resources of SP CSI-IM and PDSCH is mapped around the resources in SP ZP CSI-RS. If R1 is set to "<NUM>", PDSCH is mapped to the resources of SP CSI-IM and the SP ZP CSI-RS defined in SP-CSI-RS config is ignored.

In yet another detailed variant of this embodiment, the SP CMR, SP CSI-IM, SP ZP CSI-RS and the SP CSI reporting on PUCCH are defined in a MeasLinkConfig with a measlD. If the bit R1 is set to "<NUM>", then PDSCH is not mapped to the resources of SP CSI-IM and PDSCH is mapped around the resources in SP ZP CSI-RS. If R1 is set to "<NUM>", PDSCH is mapped to the resources of SP CSI-IM and the SP ZP CSI-RS defined in MeasLinkConfig is ignored. In this variant of the embodiment, a MAC CE indicates the measlD along with dedicated bit R1 to jointly activate a given combination of SP CMR, SP CSI-IM, SP CSI reporting, and/or SP ZP CSI-RS.

In another detailed variant of the embodiment, the SP CMR, SP CSI-IM, and the SP CSI reporting on PUCCH are defined in a ReportConfig with reportID. If the bit R1 is set to "<NUM>", then PDSCH is not mapped to the resources of SP CSI-IM and PDSCH is mapped around the resources in SP ZP CSI-RS. If R1 is set to "<NUM>", PDSCH is mapped to the resources of SP CSI-IM and the SP ZP CSI-RS defined in ReportConfig is ignored. In this variant of the embodiment, a MAC CE indicates the reportlD along with dedicated bit R1 to jointly activate a given combination of SP CMR, SP CSI-IM, SP ZP CSI-RS, and SP CSI reporting.

In yet another variant of this embodiment, no configuration of SP ZP CSI-RS resource in MeasLinkConfig or ReportConfig is required as the rate matching of PDSCH around the SP CSI-IM can be controlled directly by the bit R1. If R1 is set to <NUM> then PDSCH is not mapped to the resource elements of the SP CSI-IM while the opposite occurs if R1 is set to <NUM>.

With regard to embodiment <NUM>, since ZP CSI-RS may be used for rate matching, e.g., PDSCH resource mapping, around other UEs NZP CSI-RS it may be beneficial to activate a SP ZP CSI-RS resource without activating any NZP CSI-RS, CSI-IM, or CSI reporting for the UE. Therefore, in some embodiments, a separate MAC CE message is used to activate/deactivate SP ZP CSI-RS resources. In some embodiments, the activation/deactivation message comprises a bitmap of N bits, where each bit in the bitmap indicates if one SP ZP CSI-RS resource is activate or not. The SP ZP CSI-RS resources which the bitmap refers to may be an RRC configured list of SP ZP CSI-RS resources.

In other embodiments, the activation/deactivation message may comprise a list of SP ZP CSI-RS resource identifier to be activated/deactivated. The list may in some embodiments be of size one and thus only contains a single SP CSI-RS resource identifier. Furthermore, each entry in the list may be accompanied by another bit which indicates if the SP CSI-RS resource is activated or deactivated.

In this case the UE side assumption is that when ZP-CSI-RS is activated, UE rate matches, e.g., PDSCH resource map, around this ZP-CSI RS and not around possible active CSI-IM resource. When ZP-CSI RS is deactivated, UE rate matches around an active CSI-IM, and other default assumption.

In some embodiments, a corresponding RRC configuration for periodic RS is that if in RS resource configuration for periodic RS, a ZP-CSI-RS configuration is present, UE rate matches around this ZP-CSI RS and not around the configured CSI-IM resource.

Since the most typical use case of SP CSI-IM is for inter-cell interference measurement and the inter-cell interference sources for UEs in the same cell is the same, all UEs can share the same SP CSI-IM. Thus, in Embodiment <NUM>, a SP CSI-IM resource is shared by all UEs in a cell, i.e., the same SP CSI-IM resource (i.e. periodicity, slot offset, time-frequency REs in a slot) is configured for all UEs in a cell. A UE may not start interference measurement on the SP CSI-IM until after an associated SP CSI report is activated. There are a few options that can be used for rate matching indication:.

<FIG> is a schematic block diagram of a radio access node <NUM> according to some embodiments of the present disclosure. The radio access node <NUM> may be, for example, a base station <NUM> or <NUM>. 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>. In addition, the radio access node <NUM> includes 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>. 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> includes the control system <NUM> that includes the one or more processors <NUM> (e.g., CPUs, ASICs, FPGAs, and/or the like), the memory <NUM>, and the network interface <NUM> and the one or more radio units <NUM> that each includes the one or more transmitters <NUM> and the one or more receivers <NUM> coupled to the one or more antennas <NUM>, as described above. The control system <NUM> is connected to the radio unit(s) <NUM> via, for example, an optical cable or the like. The control system <NUM> is connected to one or more processing nodes <NUM> coupled to or included as part of a network(s) <NUM> via the network interface <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 control system <NUM> and the one or more processing nodes <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 UE <NUM> according to some embodiments of the present disclosure. As illustrated, the UE <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>. In some embodiments, the functionality of the UE <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>.

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 1706A, 1706B, 1706C, such as NBs, eNBs, gNBs, or other types of wireless Access Points (APs), each defining a corresponding coverage area 1708A, 1708B, 1708C. Each base station 1706A, 1706B, 1706C is connectable to the core network <NUM> over a wired or wireless connection <NUM>. A first UE <NUM> located in coverage area 1708C is configured to wirelessly connect to, or be paged by, the corresponding base station 1706C. A second UE <NUM> in coverage area 1708A is wirelessly connectable to the corresponding base station 1706A.

The communication system <NUM> further includes a base station 1818provided in a telecommunication system and comprising hardware <NUM> enabling it to communicate with the host computer <NUM> and with the UE <NUM>.

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 1706A, 1706B, 1706C, 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 downlink resource utilization efficiency and thereby provide benefits such as improved UE throughputs and network capacity.

These functional units may be implemented via processing circuitry, which may include one or more microprocessor or microcontrollers, as well as other digital hardware, which may include DSPs, special-purpose digital logic, and the like. The processing circuitry may be configured to execute program code stored in memory, which may include one or several types of memory such as ROM, RAM, cache memory, flash memory devices, optical storage devices, etc. Program code stored in memory includes program instructions for executing one or more telecommunications and/or data communications protocols as well as instructions for carrying out one or more of the techniques described herein.

While processes in the figures may show a particular order of operations performed by certain embodiments of the invention, it should be understood that such order is exemplary (e.g., alternative embodiments may perform the operations in a different order, combine certain operations, overlap certain operations, etc.).

Claim 1:
A method performed by a wireless device (<NUM>) for activating a Semi-Persistent, SP, Zero Power, ZP, Channel State Information Reference Signal, CSI-RS, the method comprising:
receiving, from a base station (<NUM>), a configuration for the SP ZP CSI-RS that is independent of a second configuration for CSI-Interference Measurement, CSI-IM;
receiving (<NUM>), from the base station (<NUM>), a first control message that indicates activation of one or more SP ZP CSI-RS resources, where the first control message is separate from a second control message indicating activation of SP Non-Zero Power, NZP, CSI-RS, CSI-IM, or CSI reporting and the first and second control messages are Medium Access Control, MAC, Control Element, CE, based; and
activating (<NUM>), based on the first control message, the one or more SP ZP CSI-RS resources.