WO2023096546A1 - Dci design for csi-rs enhancements for nr ue - Google Patents

Dci design for csi-rs enhancements for nr ue Download PDF

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Publication number
WO2023096546A1
WO2023096546A1 PCT/SE2022/050990 SE2022050990W WO2023096546A1 WO 2023096546 A1 WO2023096546 A1 WO 2023096546A1 SE 2022050990 W SE2022050990 W SE 2022050990W WO 2023096546 A1 WO2023096546 A1 WO 2023096546A1
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WIPO (PCT)
Prior art keywords
csi
configuration
dci
bit field
transition
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PCT/SE2022/050990
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French (fr)
Inventor
Niklas Andgart
Ilmiawan SHUBHI
Sina MALEKI
Ryan PADERNA
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Telefonaktiebolaget Lm Ericsson (Publ)
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Publication of WO2023096546A1 publication Critical patent/WO2023096546A1/en

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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L5/00—Arrangements affording multiple use of the transmission path
    • H04L5/003—Arrangements for allocating sub-channels of the transmission path
    • H04L5/0048—Allocation of pilot signals, i.e. of signals known to the receiver
    • H04L5/005—Allocation of pilot signals, i.e. of signals known to the receiver of common pilots, i.e. pilots destined for multiple users or terminals
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L5/00—Arrangements affording multiple use of the transmission path
    • H04L5/003—Arrangements for allocating sub-channels of the transmission path
    • H04L5/0053—Allocation of signaling, i.e. of overhead other than pilot signals
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L5/00—Arrangements affording multiple use of the transmission path
    • H04L5/0091—Signaling for the administration of the divided path
    • H04L5/0094—Indication of how sub-channels of the path are allocated

Definitions

  • the present disclosure generally relates to the technical field of telecommunication, and particularly to methods and the apparatus for switching channel state information (CSI)- reference signal (RS) configurations.
  • CSI channel state information
  • RS reference signal
  • NR New Radio
  • LTE Long- Term Evolution
  • NR will most likely consume more power than LTE (e.g., due to the higher bandwidth and/or due to introduction of additional elements such as 64 transmit (TX)/receive (RX) ports with several digital radio frequency (RF) chains.
  • TX transmit
  • RX receiver
  • RF digital radio frequency
  • the network is expected to be able to support user equipment (UE) with its maximum capability (e.g., throughput, coverage, etc.), the network may need to use full configuration even when the maximum network support is actually rarely needed by the UEs.
  • UE user equipment
  • maximum capability e.g., throughput, coverage, etc.
  • an increased number of TX/RX ports also leads to an increase to the number of reference signals (e.g., channel state information (CSI)-reference signal (RS)) needed to be transmitted by the network (and to be measured by the UE) for proper signal detection.
  • the additional TX/RX ports may result in additional power consumption (e.g., to transmit a larger number of CSLRS to the UEs).
  • the larger number of CSLRS transmissions may also consume the valuable network resources.
  • the CSI-RS generation procedures are defined in the 3rd Generation Partnership Project (3GPP) Technical Specification (TS) 38.211 Section 7.5.1.5.
  • the CSLRS is used for time/frequency tracking, CSI computation, Layer 1 (Ll)-Reference Signal Received Power (RSRP) computation, Ll-Signal to Interference & Noise Ratio (SINR) computation, and mobility.
  • Ll Layer 1
  • RSRP Reference Signal Received Power
  • SINR Interference & Noise Ratio
  • the UE shall not expect to be configured with CSI-RS over the symbols during which the UE is also configured to monitor the Control Resource Set (CORESET).
  • CORESET Control Resource Set
  • the UE may assume that the CSI-RS and a physical downlink control channel (PDCCH) demodulation reference signal (DM-RS) transmitted in all the search space sets associated with CORESET are quasi co-located with 'typeD', if 'typeD' is applicable.
  • PDCCH physical downlink control channel
  • DM-RS demodulation reference signal
  • the UE is not expected to receive CSI-RS and System Information Block #1 (SIB J) message in the overlapping PRBs in the OFDM symbols where SIB1 is transmitted.
  • SIB J System Information Block #1
  • DRX Discontinuous Reception
  • the UE is configured with Discontinuous Reception (DRX): if the UE is configured to monitor downlink control information (DCI) format 2 6 and configured by higher layer parameter ps-TransmitOtherPeriodicCSI to report CSI with the higher layer parameter reportConfigType set to 'periodic' and reportQuantity set to quantities other than CSI-RS Resources Indicator (CRI)-RSRP (‘cri-RSRP’) and Synchronization Signal Block (SSB) Index RSRP ('ssb-Index-RSRP') when drx-onDurationTimer in DRX-Config is not started, the most recent CSI measurement occasion occurs in DRX active time or during the time duration indicated by drx-onDurationTimer in DRX-Config also outside DRX active time for CSI to be reported; if the UE is configured to monitor DCI format 2 6 and configured by higher layer parameter ps-TransmitPeriodicLl
  • a UE can be configured with one or more non-zero power (NZP) CSI-RS resource set configuration(s) as indicated by the higher layer parameters CSI-ResourceConfig, and NZP-CSI-RS-ResourceSet.
  • NZP CSI-RS resource set consists of K>1 NZP CSI-RS resource(s).
  • TS 38.331 states the following regarding CSI-ResourceConfig'.
  • CSI-ResourceConfig SEQUENCE ⁇ csi-ResourceConfigld CSI-ResourceConfigld.
  • csi-RS-ResourceSetList CHOICE ⁇ nzp-CSI-RS-SSB SEQUENCE ⁇ nzp-CSI-RS-ResourceSetList SEQUENCE (SIZE (1..maxNrotNZP-CSI-RS-
  • TS 38.331 states the following regarding the NZP-CSI-RS-ResourceSe .
  • NZP-CSI-RS-ResourceSet SEQUENCE ⁇ nzp-CSI-ResourceSetld NZP-CSI-RS-ResourceSetld, nzp-CSI-RS-Resources SEQUENCE (SIZE ( I ..maxNrofNZP-CSI-RS-
  • TS 38.331 states the following:
  • NZP-CSI-RS-Resource SEQUENCE ⁇ nzp-CSI-RS-Resourceld NZP-CSI-RS-Resourceld, resourceMapping CSI-RS-ResourceMapping, powerControlOffset INTEGER (-8 .15), powerControlOffsetSS ENUMERATED ⁇ db-3, dbO, db3, db6 ⁇ OPTIONAL, -
  • the CSI-RS is mapped according to the configured CSI-RS- Re sour c eMapping.
  • the network could set the configuration of the cdm-Type, frequencyDomainAllocation, nrofPorts, etc.
  • CSI-RS-ResourceMapping SEQUENCE ⁇ frequencyDomainAllocation CHOICE ⁇ rowl BIT STRING (SIZE (4)), row2 BIT STRING (SIZE (12)), row4 BIT STRING (SIZE (3)), other BIT STRING (SIZE (6)) nrofPorts ENUMERATED ⁇ pl,p2,p4,p8,pl2,pl6,p24,p32 ⁇ , firstOFDMSymbolInTimeDomain INTEGER (0 .13), firstOFDMSymbolInTimeDomain2 INTEGER (2 .12)
  • OPTIONAL Need R cdm-Type ENUMERATED ⁇ noCDM, fd-CDM2, cdm4-FD2-TD2, cdm8-FD2-TD4 ⁇ , density CHOICE ⁇ dot5 ENUMERATED ⁇ evenPRBs, oddPRBs ⁇ , one NULL, three NULL, spare NULL freqBand CSI-FrequencyOccupation,
  • TS. 38.214 section 5.2.2.3.1 provides the following explanation of the CSI-RS parameters: nzp-CSI-RS-Resourceld determines CSI-RS resource configuration identity.
  • - periodicityAndOjfset defines the CSI-RS periodicity and slot offset for periodic/semi- persi stent CSI-RS . All the CSI-RS resources within one set are configured with the same periodicity, while the slot offset can be same or different for different CSI-RS resources.
  • resourceMapping defines the number of ports, CDM-type, and OFDM symbol and subcarrier occupancy of the CSI-RS resource within a slot that are given in Clause 7.4.1.5 of [4, TS 38.211], nrofPorts in resourceMapping defines the number of CSI-RS ports, where the allowable values are given in Clause 7.4.1.5 of [4, TS 38.211], density in resourceMapping defines CSI-RS frequency density of each CSI-RS port per PRB, and CSI-RS PRB offset in case of the density value of 1/2, where the allowable values are given in Clause 7.4.1.5 of [4, TS 38.211], For density 1/2, the odd/even PRB allocation indicated in density is with respect to the common resource block grid.
  • cdm-Type in resourceMapping defines CDM values and pattern, where the allowable values are given in Clause 7.4.1.5 of [4, TS 38.211],
  • scramblingID defines scrambling ID of CSI-RS with length of 10 bits.
  • qcl-InfoPeriodicCSI-RS contains a reference to a TCI-State indicating QCL source RS(s) and QCL type(s). If the TCI-State is configured with a reference to an RS configured with qcl-Type set to 'typeD' association, that RS may be an SS/PBCH block located in the same or different CC/DL BWP or a CSI-RS resource configured as periodic located in the same or different CC/DL BWP.
  • the CSI-RS resource (or the CSI-RS resource-set) that the UE needs to measure is configured in radio resource control (RRC) configuration (e.g., in the CSI-MeasConfig information element (IE)).
  • RRC radio resource control
  • the network based on its certain consideration, may add, or remove (release) the CSI-RS or the (CSI-RS resource-set) that UE needs to measure.
  • 3GPP TS 38.331 states the following:
  • CSI-MeasConfig :: SEQUENCE ⁇ nzp-CSLRS-ResourceToAddModList SEQUENCE (SIZE (L.maxNrofNZP-CSI-RS-
  • NZP-CSLRS-Resource OPTIONAL - Need N nzp-CSLRS-ResourceToReleaseList SEQUENCE (SIZE ( I ..maxNrofNZP-CSI-RS-
  • NZP-CSI-RS-ResourceSet OPTIONAL OF NZP-CSI-RS-ResourceSet OPTIONAL, - Need N nzp-CSLRS-ResourceSetToReleaseList SEQUENCE (SIZE (1..maxNrotNZP-CSI-RS-
  • FIG. 1 shows an overview of the CSLRS parameters that were discussed above.
  • Each parameter is composed of several configurations (e.g., CSI-RS-ResourceMapping is composed of nofPorts. or NZP-CSI-RS-Resource is composed of ResourceMapping and powerControlOffsetsSS parameters).
  • FIG. 1 does not include all the configurations for each parameter.
  • parameters are simply a mapping with each other using its different configurations. Most of the parameters are mapped to CSI- MeasConfig.
  • the UE After receiving the CSI-RS, the UE then reports its measurement back to the network.
  • the reporting configuration for CSI can be aperiodic (e.g., using the Physical Uplink Shared Channel (PUSCH)), periodic (e.g., using the Physical Uplink Control Channel (PUCCH)), or semi-persistent (e.g., using PUCCH, and DCI activated PUSCH).
  • the CSI-RS Resources can be periodic, semi-persistent, or aperiodic.
  • Table 5.2.1.4-1 in TS 38.214 (rewritten below as Table 1) shows the supported combinations of CSI Reporting configurations and CSI-RS Resource configurations and how the CSI Reporting is triggered for each CSI-RS Resource configuration.
  • aspects of the invention may relate to downlink control information (DCI) commands to change between channel state information (CSI)-reference signal (RS) configurations.
  • DCI downlink control information
  • CSI channel state information
  • RS reference signal
  • UE user equipment
  • Some aspects of the invention may provide the advantage of efficient utilization of DCI contents for switching between the different CSI-RS configurations.
  • aspects of the invention may relate to a UE configured with multiple CSI-RS configurations.
  • a network node may transmit an indication to change from a first CSI-RS configuration to a second CSI-RS configuration, and the UE may receive the indication.
  • the indication may be transmitted using downlink control information (DCI) or medium access control (MAC) control element (CE).
  • DCI downlink control information
  • MAC medium access control
  • CE medium access control control element
  • the UE may switch from the first CSI-RS configuration to the second CSI-RS configuration (e.g., immediately or after an application delay).
  • the multiple CSI-RS configurations may be achieved by (i) setting multiple configurations for a parameter in the CSI-RS resource, (ii) setting multiple CSI-RS resources where each of the CSI-RS resource differs in at least one parameter, and (iv) setting multiple CSI-RS resource sets where each of the CSI resource set differs in at least one CSI-RS resource parameter.
  • one of the first and second CSI-RS configurations may be a default configuration.
  • a higher layer configuration of a DCI format may be used for CSI-RS configurations.
  • the DCI may include a bit field (indicating, for example, CSI configuration index, timing of configuration change, or change back to previous configuration).
  • different transitions may use different types of indications (e.g., using DCI to quickly enable support for higher number of layers, where the transition back is using slower indication, such as via a MAC-CE).
  • One aspect of the invention may provide a method performed by a user equipment (UE) configured with at least a first channel state information (CSI)-reference signal (RS) configuration and a second CSI-RS configuration.
  • the method may include receiving downlink control information (DCI) including an indication to transition to the second CSI-RS configuration.
  • DCI downlink control information
  • the method may include, if the DCI including the indication to transition to the second CSI-RS configuration is received, switching from the first CSI-RS configuration to the second CSI-RS configuration.
  • Another aspect of the invention may provide a user equipment (UE) configured with at least a first channel state information (CSI)-reference signal (RS) configuration and a second CSI-RS configuration.
  • the UE may be adapted to receive downlink control information (DCI) including an indication to transition to the second CSI-RS configuration.
  • DCI downlink control information
  • the UE may be adapted to, if the DCI including the indication to transition to the second CSI-RS configuration is received, switch from the first CSI-RS configuration to the second CSI-RS configuration.
  • Still another aspect of the invention may provide a method performed by a network node.
  • the method may include transmitting downlink control information (DCI) to a user equipment (UE) configured with at least a first channel state information (CSI)-reference signal (RS) configuration and a second CSI-RS configuration.
  • DCI downlink control information
  • UE user equipment
  • CSI channel state information
  • RS reference signal
  • the DCI may include an indication to transition to the second CSI-RS configuration.
  • the method may include transmitting one or more CSI-RS s to the UE.
  • the network node may be adapted to transmit downlink control information (DCI) to a user equipment (UE) configured with at least a first channel state information (CSI)-reference signal (RS) configuration and a second CSI-RS configuration, and the DCI may include an indication to transition to the second CSI-RS configuration.
  • DCI downlink control information
  • UE user equipment
  • CSI channel state information
  • RS reference signal
  • the network node may be adapted to transmit one or more CSI-RSs to the UE.
  • Still another aspect of the invention may provide a computer program including instructions for adapting an apparatus to perform any of the methods set forth above.
  • FIG. 1 provides an overview of the channel state information (CSI)-reference signal (RS) parameter and its configurations.
  • CSI channel state information
  • RS reference signal
  • FIG. 2 illustrates a UE according to some aspects.
  • FIG. 3 illustrates a network node according to some aspects.
  • FIG. 4 is a flowchart illustrating a process according to some aspects.
  • FIG. 5 is a flowchart illustrating a process according to some aspects.
  • node can be a network node or a user equipment (UE).
  • network nodes include, but are not limited to, a NodeB, a base station (BS), a multistandard radio (MSR) radio node such as a MSR BS, an eNodeB, a gNodeB, a Master eNB (MeNB), a Secondary eNB (SeNB), integrated access backhaul (IAB) node, network controller, radio network controller (RNC), base station controller (BSC), relay, donor node controlling relay, base transceiver station (BTS), Central Unit (e.g. in a gNB), Distributed Unit (e.g.
  • MSR multistandard radio
  • gNB Baseband Unit
  • Centralized Baseband C-RAN
  • AP access point
  • RRU remote radio unit
  • RRH remote radio head
  • DAS distributed antenna system
  • core network node e.g. MSC, MME, etc.
  • O&M core network node
  • OSS e.g. SON
  • positioning node e.g. E-SMLC
  • the term “user equipment” or “UE” is a non-limiting term that refers to any type of wireless device communicating with a network node and/or with another UE in a cellular or mobile communication system.
  • UEs include, but are not limited to, a target device, a device to device (D2D) UE, a vehicular to vehicular (V2V), a machine type UE, an machine type communication (MTC) UE, a UE capable of machine to machine (M2M) communication, a PDA, a Tablet, a mobile terminal(s), a smart phone, laptop embedded equipment (LEE), laptop mounted equipment (LME), and USB dongles.
  • D2D device to device
  • V2V vehicular to vehicular
  • MTC machine type communication
  • M2M machine to machine
  • PDA tablet
  • Tablet a mobile terminal(s)
  • smart phone laptop embedded equipment
  • LME laptop mounted equipment
  • USB dongles USB dongles.
  • radio network node is generic terminology that refers to any kind of network node including but not limited to a base station, a radio base station, a base transceiver station, a base station controller, a network controller, an evolved Node B (eNB), a Node B, a gNodeB (gNB), a relay node, an access point (AP), a radio access point, a Remote Radio Unit (RRU), a Remote Radio Head (RRH), a Central Unit (e.g., in a gNB), a Distributed Unit (e.g., in a gNB), a Baseband Unit, a Centralized Baseband, a C-RAN, a Mobile Management Entity (MME), and a PDN Gateway (PGW).
  • eNB evolved Node B
  • gNB gNodeB
  • AP access point
  • RRU Remote Radio Unit
  • RRH Remote Radio Head
  • Central Unit e.g., in a gNB
  • Distributed Unit e.g
  • radio access technology may refer to any RAT including, for example and without limitation, UTRA, E-UTRA, narrow band internet of things (NB-IoT), WiFi, Bluetooth, next generation RAT, New Radio (NR), 4G, and 5G.
  • RAT radio access technology
  • Any of the equipment denoted by the terms “node,” “network node,” or “radio network node” may be capable of supporting a single or multiple RATs.
  • FIG. 2 is a block diagram of a UE 102 according to some aspects.
  • the UE 102 may include: processing circuitry (PC) 202, which may include one or more processors (P) 255 (e.g., one or more general purpose microprocessors and/or one or more other processors, such as an application specific integrated circuit (ASIC), field-programmable gate arrays (FPGAs), and the like); communication circuitry 248, which is coupled to an antenna arrangement 249 comprising one or more antennas and which comprises a transmitter (Tx) 245 and a receiver (Rx) 247 for enabling UE 102 to transmit data and receive data (e.g., wirelessly transmit/receive data); and a local storage unit (a.k.a., “data storage system”) 208, which may include one or more non-volatile storage devices and/or one or more volatile storage devices.
  • PC processing circuitry
  • P processors
  • ASIC application specific integrated circuit
  • FPGAs field-programmable gate arrays
  • a computer program product (CPP) 241 may be provided.
  • the CPP 241 may include a computer readable medium (CRM) 242 storing a computer program (CP) 243 comprising computer readable instructions (CRI) 244.
  • CRM 242 may be a non-transitory computer readable medium, such as, magnetic media (e.g., a hard disk), optical media, memory devices (e.g., random access memory, flash memory), and the like.
  • the CRI 244 of computer program 243 is configured such that when executed by PC 202, the CRI causes UE 102 to perform steps described herein (e.g., steps described herein with reference to the process 400 shown in FIG. 4).
  • the UE 102 may be configured to perform steps described herein without the need for code. That is, for example, the PC 202 may consist merely of one or more ASICs. Hence, the features of the aspects described herein may be implemented in hardware and/or software.
  • FIG. 3 is a block diagram of a network node 104, according to some aspects.
  • the network node 104 may comprise: processing circuitry (PC) 302, which may include one or more processors (P) 355 (e.g., one or more general purpose microprocessors and/or one or more other processors, such as an application specific integrated circuit (ASIC), field-programmable gate arrays (FPGAs), and the like), which processors may be co-located in a single housing or in a single data center or may be geographically distributed (i.e., the network node 104 may be a distributed computing apparatus); a network interface 368 comprising a transmitter (Tx) 365 and a receiver (Rx) 367 for enabling the network node 104 to transmit data to and receive data from other nodes connected to a network 110 (e.g., an Internet Protocol (IP) network) to which network interface 368 is connected; communication circuitry 348, which is coupled to an antenna arrangement 349 comprising one
  • IP Internet Protocol
  • CPP 341 includes a computer readable medium (CRM) 342 storing a computer program (CP) 343 comprising computer readable instructions (CRI) 344.
  • CRM 342 may be a non-transitory computer readable medium, such as, magnetic media (e.g., a hard disk), optical media, memory devices (e.g., random access memory, flash memory), and the like.
  • the CRI 344 of computer program 343 may be configured such that when executed by PC 302, the CRI causes the network node 104 to perform steps described herein (e.g., steps described herein with reference to the process 500 shown in FIG. 5).
  • the network node 104 may be configured to perform steps described herein without the need for code. That is, for example, PC 302 may consist merely of one or more ASICs. Hence, the features of the aspects described herein may be implemented in hardware and/or software.
  • aspects of the present invention may enable a fast and/or resource efficient dynamic CSI-RS configuration adaption.
  • the dynamic CSI-RS configuration adaption may be enabled by:
  • CSI-reference signal RS
  • MAC medium access control
  • DCI downlink control information
  • CSI-RS parameters included in CSI-Measconfig can have multiple CSI-RS configurations and using MAC CE or DCI to activate or deactivate one or more configured CSI-RS resource set (and/or to switch between CSI-RS resource sets).
  • the UE 102 may be configured with more than one CSI-RS configuration. Aspects of the invention may provide a fast dynamic adaptation mechanism in which the UE 102 is capable of being caused (e.g., indicated) to switch between different CSI- RS configurations. In some aspects, the switching may be, for example, done by the network node 104 during the port adaptation (e.g., port adaptation in which the network node 104 determines to change the number of ports that will be used to serve the UE 102).
  • the term “multiple CSI-RS configurations” may refer to multiple CSI-RS configurations that can be activated or deactivated or switched through MAC-CE or DCI signaling. That is, the multiple CSI-RS confirmations are different than existing CSI-RS configurations in which multiple CSI-RS configurations are added or released through RRC (re)configuration.
  • the bit field in the DCI may indicate whether the default configuration or another configuration is activated.
  • the UE 102 may be configured with a first CSI-RS configuration and a second CSI-RS configuration with the first configuration being the default.
  • an additional bit in the DCI e.g., DCI 1-1/2
  • the UE 102 may consider the second CSI-RS configuration as activated and may consider the first (e.g., default) CSI-RS configuration as deactivated.
  • the UE 102 may consider the first (e.g., default) CSI-RS configuration as the active configuration.
  • the DCI may include two or more additional bits, and the number of additional bits in the DCI may depend on the number of CSI-RS configurations (e.g., the DCI may include two additional bits to specify one of up to four CSI-RS configurations, and 00 may indicate the default CSI-RS configuration).
  • a legacy behavior may apply. For example, in some aspects, if multiple CSI-RS configurations are not set for the UE 102, the UE 102 may need to monitor all of the CSI-RS, which may be included in, for example, CSI-MeasConfig. In another example, in some aspects, the additional bit field in the DCI used for the adaptation indication may not be included in the DCI transmitted to the UE 102.
  • the network node 104 may have flexibility on which CSI-RS should be used at one time instance.
  • the network node 104 may select the active CSI-RS configurations based on, for example, the state of the port adaptation. For example, in some aspects, the network node 104 may use the following process to exploit the multiple CSI-RS configurations.
  • the process may include a first step in which the network node 104 configures the UE 102 with multiple CSI-RS configurations (e.g., including at least first and second CSI-RS configurations).
  • the network node 104 configures the UE 102 with multiple CSI-RS configurations by, for example, configuring the UE 102 to have more than one parameter configuration (e.g., parameters inside the CSI-RS- ResourceMapping IE).
  • the process may include a second step in which the network node 104 causes (e.g., indicates) the UE 102 to switch from the first CSI-RS configuration to the second CSI-RS configuration.
  • the network node 104 may decide to change the CSI-RS configuration, for example, when there are no more UEs 102 active in the cell, or when no UEs 102 are active that require or can take advantage of transmission with a large number of ports (e.g., sustained transmission with multiple layers and narrow beams).
  • the network node 104 may decide to switch from the first CSI-RS configuration suitable for a larger number of ports transmission to the second CSI-RS configuration suitable for a smaller number of ports transmission.
  • the network node 104 may cause (e.g., indicate) the UE 102 to switch CSI-RS configurations, for example, via DCI or MAC-CE.
  • the process may include a third step in which, after sending the switching indication, the network node 104 transmits the CSI-RS according to the second CSI- RS configuration.
  • the network node 104 may configure the UE 102 through higher layer signaling (e.g., radio resource control (RRC) signaling) if the activation/deactivation mechanism is DCI based, MAC CE based, and also the underlying configuration (e.g., additional bit field and its interpretation in the DCI).
  • RRC radio resource control
  • the UE 102 may be preconfigured (e.g., as in standardization documentations). For example, in some aspects, if there are two fields configured for a parameter (e.g., number of ports), then the UE 102 may automatically expect a MAC CE or DCI to be able to activate or deactivate the configurations (e.g., as determined in the standards).
  • the UE 102 may receive multiple CSI-RS configurations (e.g., including at least first and second CSI-RS configurations). In some aspects, the UE 102 may receive the multiple CSI-RS configurations, for example, through RRC signaling. In some aspects, the UE 102 may measure or report based on the first configuration as the default configuration. In some aspects, the UE 102 may, in one time instant, receive a MAC CE command or a DCI indicating that the UE 102 should perform measurements or reporting based on the second configuration. In some aspects, the UE 102 may measure the CSI-RS based on the second CSI-RS configuration or report CSI based on measuring the second CSI-RS configuration.
  • the UE 102 may measure the CSI-RS based on the second CSI-RS configuration or report CSI based on measuring the second CSI-RS configuration.
  • a group of UEs 102 may receive command to switch to a second CSI-RS configuration. In some aspects, this may be implemented, for example, as a group MAC or a DCI using group common search space. In some aspects, a group of UEs 102 can be configured to, using low signaling overhead and low latency, switch CSI-RS configurations. In some aspects, the individual CSI-RS configurations may still be configured per-UE.
  • the group switching command may be, for example, formulated as: (a) all UEs 102 in group switch to specific configuration index (e.g., switch to nzp-CSI-RS-ResourcesDefault or nzp-CSI-RS-ResourcesB), or (b) all UEs 102 in group switch to an implicitly indicated configuration (e.g., switch to CSI-RS configuration with shortest periodicity, densest allocation in time/frequency, largest number of ports, etc.).
  • specific configuration index e.g., switch to nzp-CSI-RS-ResourcesDefault or nzp-CSI-RS-ResourcesB
  • an implicitly indicated configuration e.g., switch to CSI-RS configuration with shortest periodicity, densest allocation in time/frequency, largest number of ports, etc.
  • the UE 102 may be given a bit field in DCI.
  • the bit field in DCI may indicate whether the default CSI-RS configuration or another CSI-RS configuration is activated.
  • the UE 102 may be configured with a first CSI-RS configuration and a second CSI-RS configuration with the first one as the default.
  • an additional bit in the DCI e.g., DCI 1-1/2 may be configured.
  • the UE 102 may consider the second CSI-RS configuration as activated and may consider the first (e.g., default) CSI-RS configuration as deactivated. In some aspects, if the UE 102 receives the additional bit in the DCI, and the additional bit has a second bit status (e.g., a bit status of “0”), which may be considered reserved, the UE 102 may consider the first (e.g., default) CSI-RS configuration as the active configuration.
  • a first bit status e.g., a bit status of “1”
  • the UE 102 may consider the second CSI-RS configuration as activated and may consider the first (e.g., default) CSI-RS configuration as deactivated.
  • the UE 102 may consider the first (e.g., default) CSI-RS configuration as the active configuration.
  • each bit of a bit field in DCI may be mapped to different CSI-RS parameters.
  • a bit of the bit field having a second bit status (e.g., a bit status of “0”) may indicate a default configuration for the CSI-RS parameter (e.g., nrofPortsDefault, densityDefault, powerControlOffsetSSDefault, qcl-InfoPeriodicCSI- RSDefault, or nzp-CSI-RS-ResourcesDefaulf) to which the bit is mapped.
  • a default configuration for the CSI-RS parameter e.g., nrofPortsDefault, densityDefault, powerControlOffsetSSDefault, qcl-InfoPeriodicCSI- RSDefault, or nzp-CSI-RS-ResourcesDefaulf
  • a bit of the bit field having a first bit status may indicate a different configuration for the CSI-RS parameter (e.g., nrofPortsB, densityB. powerControlOffsetSS B , qcl-InfoPeriodicCSI-RS B, and/or nzp-CSI-RS-ResourcesB') to which the bit is mapped.
  • the CSI-RS parameter e.g., nrofPortsB, densityB. powerControlOffsetSS B , qcl-InfoPeriodicCSI-RS B, and/or nzp-CSI-RS-ResourcesB'
  • one bit in DCI may be used to indicate the default configuration for the CSI-RS parameters or the second configuration with all its underlying second configuration parameters.
  • one additional bit in the DCI bit field is enough to choose between the two different CSI-RS configurations.
  • a larger bit field in the DCI may be used.
  • the number of bits of the DCI bit field used for choosing between different CSI-RS configurations may be higher layer configured.
  • the number of bits of the DCI bit field used for choosing between different CSI-RS configurations may be defined in the standard with a certain number of bits for different scenarios.
  • the standard may also define the limit of the maximum number of bits that can be configured.
  • the higher layer may configure the bit field with the size of 1, . . ., X number of bits, where X is defined in the standard.
  • the maximum CSI-RS configurations may depend on the maximum number of ports that a system can support.
  • higher layer signaling e.g., RRC signaling
  • the start of the bit field may be an explicit location in the DCI.
  • the start of the bit field may be a relative location (e.g., after time or frequency resource allocation bit field) in case a scheduling DCI is used.
  • a codepoint or bitmap-based indication when more than 1 bit in the bit field is supported, a codepoint or bitmap-based indication may be used.
  • the first, second, third, and fourth configuration can be indicated by a bit combination of 00, 01, 10, and 11, respectively.
  • X log 2 K]
  • Y is the total number of different CSI-RS configurations.
  • the CSI-RS enhancement bit field may be an additional bit field on top of the existing bit field in DCI(s).
  • the CSI-RS enhancement bit field may reuse the existing bit field.
  • the UE 102 may determine whether the bit field is used as the existing bit field or as the CSI-RS enhancement bit field based on whether a certain parameter is configured in the higher layer configuration. For example, in some aspects, if at least one second configuration parameter (e.g., at least one of nrofPortsB, densityB , powerControlOffsetSS B , etc.) is configured, the UE 102 may interpret the bit field as a CSI-RS enhancement bit field. Otherwise, if none of the second configuration parameter is configured, the UE 102 may interpret the bit field as the existing bit field.
  • at least one second configuration parameter e.g., at least one of nrofPortsB, densityB , powerControlOffsetSS B , etc.
  • a new parameter may be configured in the higher layer to determine the interpretation of the bit field. For example, if the new parameter (e.g., adaptiveCSI- RS enabled) is set to true, then the UE 102 may interpret the bit field as a CSI-RS enhancement bit field, and, if the new parameter is set to false (or if it is not configured), then the UE 102 may interpret the bit field as the existing bit field.
  • the new parameter e.g., adaptiveCSI- RS enabled
  • an indication to an invalid index within the current DCIs may also be used for the above purposes (e.g., referring to an invalid modulation coding scheme (MCS) index in a scheduling DCI can be used to indicate the change to a new configuration or going back to default, etc.).
  • MCS modulation coding scheme
  • the UE 102 may instantaneously switch to another CSI-RS configuration after having received the instruction.
  • the switch may take effect after a certain pre-defined time or application delay.
  • the UE 102 may switch at the first symbol of the first slot after the predefined time.
  • the time until the configuration change takes effect may additionally or alternatively be configured by the higher layers or included by adding additional bit fields in the DCI and then indicated through the DCI.
  • higher layers may configure multiple application delays, and the additional bits in the bit field in the DCI may be used to indicate one of the application delays.
  • the application delay may be pre-configured (e.g., as part of the standardization documentations), or (b) the UE 102 may apply the configuration change immediately.
  • the standard may define the maximum or minimum time that is allowed for the switching between CSI-RS configurations.
  • the predefined time may be different (e.g., based on the capability of the UE 102 and/or subcarrier spacing (SCS)).
  • SCS subcarrier spacing
  • the CSI-RS enhancement bit field may be included in an existing DCI format.
  • the CSI-RS enhancement bit field may be included in existing 0- x uplink formats, 1-x downlink formats, or 2-x non-scheduling DCI formats, such as 0-1, 0-2, 1-1, 1-2, and 2-6.
  • the fallback DCI formats 0-0 and 1-0 which have a tighter size requirement, may not be suitable for addition of extra bits.
  • the DCI may be sent to a group of UEs 102 scrambled by a group Radio Network Temporary Identifier (RNTI).
  • RNTI Radio Network Temporary Identifier
  • the scrambling by a group RNTI may be applied for group of UEs 102 that uses common quasi-colocation ports in the network-side and can be configured using a common CSI-RS (e.g., UEs 102 that are closer together resulting to QCL-TypeD (spatial Rx parameters)).
  • Some aspects may use DCI format 2-6 using a power saving RNTI (PS-RNTI).
  • PS-RNTI power saving RNTI
  • the DCI may be sent using another existing group common RNTIs or with a new DCI format with a new RNTI.
  • the transitions between the CSI-RS configurations may be triggered by DCI commands and/or MAC CE commands.
  • the DCI triggering may lead to a lower latency (relative to MAC CE commands) but may also consume more system resources, as there are not as many bits at disposal in DCI. Also, in case the information is not included in an existing DCI, this would lead to transmission of an extra physical downlink control channel (PDCCH), which increases the overhead.
  • PDCCH physical downlink control channel
  • the transmission of the indication of a transition from a first state to a second state may be done using DCI, and the transmission of the indication of a transition from the second state to the first state may be done with a higher-latency command (e.g., a MAC CE or an RRC configuration).
  • a higher-latency command e.g., a MAC CE or an RRC configuration.
  • the fast transmission may be used when the CSI-RS configuration should be increased, because the network node 104 (e.g., gNb) may quickly enable support for transmission using higher number of layers without affecting the transmission latency.
  • the transmission back to a lower-density CSI-RS configuration may be done with more slack latency requirements, as this will not harm the transmission latency (but may harm only the transmission power during a short period).
  • a misalignment can happen between the network node 104 and the UE 102.
  • the network node 104 may indicate to the UE 102 that the UE 102 should use a second CSI-RS configuration after an application delay, while the UE was measuring over the first one. If the UE 102 misses this indication, the UE 102 may keep performing measurements on the first configuration, which is not valid anymore, and this can impact the performance of the UE 102.
  • the network node 104 may understand that the UE 102 has missed the DCI (e.g., if the UE 102 does not send an ACK/NACK message, or if the UE 102 does not report the CSI if requested). In some aspects, if the network node 104 determines that the UE 102 has missed a DCI indicating a CSI-RS configuration transition, the network node 104 may send the DCI again to make sure the UE 102 measures the correct CSI-RS configuration. In some aspects, a number of attempts may be defined to avoid the network node 104 over signaling to the UE 102. In some aspects, the network node 104 may indicate the number of attempts in the DCI until it is successful so that UE 102 can adjust the misalignment for the next CSI-RS configuration.
  • the UE 102 may not show any immediate feedback, and, as a result, it may be more complicated for the network node 104 to detect whether the UE 102 has missed the DCI.
  • a new DCI format may indicate the change to a second configuration, and, if the UE 102 misses the DCI, the UE 102 may keep performing measurements on the first configuration.
  • a configured or pre-configured acknowledgement (ACK) mechanism for one or more specific DCI formats may be used, which may prevent or reduce misalignments between the UE 102 and the network node 104.
  • ACK acknowledgement
  • FIG. 4 illustrates a process 400 performed by the user equipment (UE) 102 according to some aspects.
  • the UE 102 may be configured with at least a first channel state information (CSI)-reference signal (RS) configuration and a second CSI-RS configuration.
  • CSI channel state information
  • RS reference signal
  • the first CSI-RS configuration may include a configuration (e.g., value) for a parameter in a CSI-RS resource, and the second CSI-RS configuration may include a different configuration for the parameter in the CSI-RS resource;
  • the first CSI-RS configuration may include a CSI-RS resource, and the second CSI-RS configuration may include a different CSI-RS resource; and/or (c) the first CSI-RS configuration may include a CSI-RS resource set, and the second CSI-RS configuration may include a different CSI-RS resource set.
  • the first CSI-RS configuration may be a default CSI-RS configuration
  • the second CSI-RS configuration may be a non-default CSI-RS configuration.
  • the process 400 may include an optional step 402 in which the UE 102 receives the first and second CSI-RS configurations.
  • the first and second CSI-RS configurations may be transmitted by the network node 104.
  • the process 400 may include a step 404 in which the UE 102 receives downlink control information (DCI) including an indication to transition to the second CSI-RS configuration.
  • DCI downlink control information
  • the DCI may include a CSI-RS configuration bit field, and a status of one or more bits of the CSI-RS configuration bit field may provide the indication to transition to the second CSI-RS configuration.
  • the CSI-RS configuration bit field in the DCI may include only one bit.
  • the UE 102 may be further configured with at least third and fourth CSI-RS configurations, and the CSI-RS configuration bit field in the DCI may include at least two bits.
  • the CSI-RS configuration bit field in the DCI may include X bits, the UE 102 may be configured with Y or fewer CSI-RS configuration, X may be greater than or equal to 1, and X may equal to log2 Y.
  • the CSI-RS configuration bit field in the DCI may include X bits, the UE 102 may be configured with Y or fewer CSI-RS configuration, X may be greater than or equal to 1, and X may equal log2 (Y-l).
  • the number of bits in CSI-RS configuration bit field may be configured by higher layer signaling (e.g., radio resource control (RRC) signaling).
  • RRC radio resource control
  • a start of the CSI-RS configuration bit field may be configured by higher layer signaling (e.g., radio resource control (RRC) signaling).
  • RRC radio resource control
  • the start of the CSI-RS configuration bit field may be an explicit location in the DCI.
  • the start of the CSI-RS configuration bit field may be a relative location in the DCI (e.g., after time or frequency resource allocation bit field).
  • the CSI-RS configuration bit field may be a new bit field in addition to existing DCI bit fields. In some alternative aspects, the CSI-RS configuration bit field may reuse an existing DCI bit field. In some aspects, the UE 102 may interpret the existing DCI bit field as the CSI-RS configuration bit field if a parameter is configured. In some aspects, the parameter may be an existing parameter (e.g., at least one of nrofPortsB, densityB, powerControlOffsetSS B). In some aspects, the parameter may be a new parameter (e.g., adaptiveCSI-RS enabled). In some aspects, the indication to transition to the second CSI-RS configuration may be an invalid index within the existing DCI bit field.
  • the parameter may be an existing parameter (e.g., at least one of nrofPortsB, densityB, powerControlOffsetSS B). In some aspects, the parameter may be a new parameter (e.g., adaptiveCSI-RS enabled). In some aspects, the indication to transition to the second CSI-RS configuration may be an invalid index
  • the CSI-RS configuration bit field may be included in one or more existing DCI formats.
  • the one or more existing DCI formats may include 0-x uplink formats, 1-x downlink formats, and/or 2-x non-scheduling DCI formats (e.g., a 0-1 uplink format, a 0-2 uplink format, a 1-1 downlink format, a 1-2 downlink format, and/or a 2-6 nonscheduling DCI format).
  • the DCI is scrambled by a group Radio Network Temporary Identifier (RNTI).
  • RNTI Radio Network Temporary Identifier
  • the process 400 may include a step 406 in which the UE 102, if the DCI including the indication to transition to the second CSI-RS configuration is received in step 404, switches from the first CSI-RS configuration to the second CSI-RS configuration.
  • switching from the first CSI-RS configuration to the second CSI-RS configuration in step 406 may include switching from the first CSI-RS configuration to the second CSI-RS configuration without delay after the DCI including the indication to transition to the second CSI-RS configuration is received.
  • switching from the first CSI-RS configuration to the second CSI-RS configuration in step 406 may include switching from the first CSI-RS configuration to the second CSI-RS configuration after a delay following receiving the DCI including the indication to transition to the second CSI-RS configuration.
  • switching from the first CSI-RS configuration to the second CSI-RS configuration in step 406 may include switching from the first CSI-RS configuration to the second CSI-RS configuration at a quantized timing.
  • the quantized timing may be a first symbol of a first slot after a delay following receiving the DCI including the indication to transition to the second CSI-RS configuration.
  • the delay and/or the quantized timing may be configured by higher layers (e.g., radio resource control (RRC) signaling).
  • the DCI may include a timing of CSI-RS configuration transition bit field that indicates the delay and/or the quantized timing.
  • the process 400 may include an optional step 408 in which the UE 102, if the DCI is received in step 404, sends an acknowledgement message (e.g., an ACK/NACK message).
  • the DCI may be a scheduling DCI.
  • the DCI may be a non-scheduling DCI.
  • the process 400 may include an optional step 410 in which the UE 102 performs CSI-RS measurements and/or reporting based on the second CSI-RS configuration.
  • the process 400 may include an optional step 412 in which the UE 102 receives an indication to transition to the first CSI-RS configuration.
  • the indication to transition to the first CSI-RS configuration may be received via DCI.
  • the indication to transition to the first CSI-RS configuration may be a command having a higher latency than a DCI command.
  • the indication to transition to the first CSI-RS configuration may be received via a medium access control (MAC) control element (CE).
  • the indication to transition to the first CSI-RS configuration may be received via a radio resource control (RRC) configuration.
  • RRC radio resource control
  • the process 400 may include an optional step 414 in which the UE 102, if the indication to transition to the first CSI-RS configuration is received in step 414, switches from the second CSI-RS configuration to the first CSI-RS configuration. [0084] In some aspects, the process 400 may further include an optional step 416 in which the UE 102 performs CSI-RS measurements and/or reporting based on the first CSI-RS configuration.
  • FIG. 5 illustrates a process 500 performed by the network node 104 according to some aspects.
  • the process 500 may include an optional step 502 in which the network node 104 transmits first and second CSI-RS configurations to a UE 102.
  • the process 500 may include a step 504 in which the network node 104 transmits DCI to the UE 102.
  • the UE 102 may be configured with at least first and second CSI-RS configurations.
  • the DCI may include an indication to transition to the second CSI-RS configuration.
  • the first CSI-RS configuration may include a configuration (e.g., value) for a parameter in a CSI-RS resource, and the second CSI-RS configuration may include a different configuration for the parameter in the CSI-RS resource;
  • the first CSI-RS configuration may include a CSI-RS resource, and the second CSI-RS configuration may include a different CSI-RS resource; and/or (c) the first CSI-RS configuration may include a CSI-RS resource set, and the second CSI-RS configuration may include a different CSI-RS resource set.
  • the first CSI-RS configuration may be a default CSI-RS configuration
  • the second CSI-RS configuration may be a non-default CSI-RS configuration.
  • the DCI may include a CSI-RS configuration bit field, and a status of one or more bits of the CSI-RS configuration bit field may provide the indication to transition to the second CSI-RS configuration.
  • the CSI-RS configuration bit field in the DCI may include only one bit.
  • the UE 102 may be further configured with at least third and fourth CSI-RS configurations, and the CSI-RS configuration bit field in the DCI may include at least two bits.
  • the CSI-RS configuration bit field in the DCI may include X bits, the UE 102 may be configured with Y or fewer CSI-RS configuration, X may be greater than or equal to 1, and X may equal log2 Y.
  • the CSI-RS configuration bit field in the DCI may include X bits, the UE may be configured with Y or fewer CSI-RS configuration, X may be greater than or equal to 1, and X may be log2 (Y-l).
  • the number of bits in CSI-RS configuration bit field may be configured by higher layer signaling (e.g., RRC signaling).
  • a start of the CSI-RS configuration bit field may be configured by higher layer signaling (e.g., RRC signaling).
  • the start of the CSI-RS configuration bit field is an explicit location.
  • the start of the CSI-RS configuration bit field may be a relative location.
  • the CSI-RS configuration bit field may be a new bit field in addition to existing DCI bit fields. In some alternative aspects, the CSI-RS configuration bit field may reuse an existing DCI bit field. In some aspects, the UE 102 may interpret the existing DCI bit field as the CSI-RS configuration bit field if a parameter is configured. In some aspects, the parameter may be an existing parameter (e.g., at least one of nrofPortsB, densityB, powerControlOffsetSS B). In some aspects, the parameter may be a new parameter (e.g., adaptiveCSI-RS enabled). In some aspects, the indication to transition to the second CSI-RS configuration may be an invalid index within an existing DCI bit field.
  • the parameter may be an existing parameter (e.g., at least one of nrofPortsB, densityB, powerControlOffsetSS B). In some aspects, the parameter may be a new parameter (e.g., adaptiveCSI-RS enabled). In some aspects, the indication to transition to the second CSI-RS configuration may be an invalid index
  • the CSI-RS configuration bit field may be included in one or more existing DCI formats.
  • the one or more existing DCI formats may include 0-x uplink formats, 1-x downlink formats, and/or 2-x non-scheduling DCI formats (e.g., a 0-1 uplink format, a 0-2 uplink format, a 1-1 downlink format, a 1-2 downlink format, and/or a 2-6 nonscheduling DCI format).
  • the DCI may be scrambled by a group Radio Network Temporary Identifier (RNTI).
  • RNTI Radio Network Temporary Identifier
  • the DCI may include a timing of CSI-RS configuration transition bit field that indicates a delay and/or a quantized timing for the UE 102 to switch to the second CSI- RS configuration.
  • the quantized timing may be a first symbol of a first slot after the delay following the UE 102 receiving the DCI including the indication to transition to the second CSI-RS configuration.
  • the process 500 may include an optional step 506 in which the network node 104 receives an acknowledgement message (e.g., an ACK/NACK message) transmitted by the UE 102.
  • the DCI may be a scheduling DCI.
  • the DCI may be a non-scheduling DCI.
  • the process 500 may include an optional step in which the network node 104 determines that an acknowledgement message has not been received and re-transmitting DCI including the indication to transition to the second CSI-RS configuration.
  • the process 500 may include a step 508 in which the network node 104 transmits one or more CSI-RSs to the UE 102.
  • the one or more CSI-RSs transmitted in step 508 may correspond to the second CSI-RS configuration.
  • the process 500 may include an optional step 510 in which the network node 104 receives a measurement report conveyed by the UE 102.
  • the measurement report may be based on the second CSI-RS configuration.
  • the process 500 may include an optional step 512 in which the network node 104 transmits an indication for the UE 102 to transition to the first CSI-RS configuration.
  • the network node 104 may transmit the indication to transition to the first CSI-RS configuration via DCI.
  • the indication to transition to the first CSI-RS configuration may be a command having a higher latency than a DCI command.
  • the network node 104 may transmit the indication to transition to the first CSI-RS configuration via a medium access control (MAC) control element (CE).
  • the network node 104 may transmit the indication to transition to the first CSI-RS configuration via a radio resource control (RRC) configuration.
  • RRC radio resource control
  • the process 500 may include an optional step 514 in which the network node 104 transmits one or more CSI-RSs to the UE 102.
  • the one or more CSI-RSs transmitted in step 514 may correspond to the first CSI-RS configuration
  • the process 500 may include an optional step 516 in which the network node 104 receives a measurement report conveyed by the UE 102, and the measurement report may be based on the first CSI-RS configuration.
  • DCI downlink control information
  • the first CSI-RS configuration includes a configuration (e.g., value) for a parameter in a CSI-RS resource
  • the second CSI-RS configuration includes a different configuration for the parameter in the CSI-RS resource
  • the first CSI-RS configuration includes a CSI-RS resource
  • the second CSI-RS configuration includes a different CSI-RS resource
  • the first CSI-RS configuration includes a CSI-RS resource set
  • the second CSI-RS configuration includes a different CSI-RS resource set
  • A3 The method of example Al or A2, wherein the first CSI-RS configuration is a default CSI-RS configuration, and the second CSI-RS configuration is a non-default CSI-RS configuration.
  • A5 The method of any one of examples A1-A4, wherein the DCI includes a CSI-RS configuration bit field, and a status of one or more bits of the CSI-RS configuration bit field provides the indication to transition to the second CSI-RS configuration.
  • A7 The method of example A5, wherein the UE is further configured with at least third and fourth CSI-RS configurations, and the CSI-RS configuration bit field in the DCI comprises at least two bits.
  • A9 The method of any one of examples A5-A8b, wherein the number of bits in CSI-RS configuration bit field is configured by higher layer signaling (e.g., radio resource control (RRC) signaling).
  • RRC radio resource control
  • A10 The method of any one of examples A5-A9, wherein a start of the CSI-RS configuration bit field is configured by higher layer signaling (e.g., radio resource control (RRC) signaling).
  • RRC radio resource control
  • Al 8 The method of example A14, wherein the indication to transition to the second CSI-RS configuration is an invalid index within the existing DCI bit field.
  • the one or more existing DCI formats include 0-x uplink formats, 1-x downlink formats, and/or 2-x non-scheduling DCI formats (e.g., a 0-1 uplink format, a 0-2 uplink format, a 1-1 downlink format, a 1-2 downlink format, and/or a 2-6 nonscheduling DCI format).
  • the one or more existing DCI formats include 0-x uplink formats, 1-x downlink formats, and/or 2-x non-scheduling DCI formats (e.g., a 0-1 uplink format, a 0-2 uplink format, a 1-1 downlink format, a 1-2 downlink format, and/or a 2-6 nonscheduling DCI format).
  • A21 The method of any one of examples A1-A20, wherein the DCI is scrambled by a group Radio Network Temporary Identifier (RNTI).
  • RNTI Radio Network Temporary Identifier
  • A22 The method of any one of examples A1-A21, further comprising: receiving an indication to transition to the first CSI-RS configuration; and if the indication to transition to the first CSI-RS configuration is received, switching from the second CSI-RS configuration to the first CSI-RS configuration.
  • A25 The method of example A22 or A24, wherein the indication to transition to the first CSI- RS configuration is received via a medium access control (MAC) control element (CE).
  • MAC medium access control
  • A26 The method of example A22 or A24, wherein the indication to transition to the first CSI- RS configuration is received via a radio resource control (RRC) configuration.
  • RRC radio resource control
  • A27 The method of any one of examples A22-A26, further comprising performing CSI-RS measurements and/or reporting based on the first CSI-RS configuration.
  • A28 The method of any one of examples A1-A27, further comprising, if the DCI is received, sending an acknowledgement message (e.g., an ACK/NACK message).
  • an acknowledgement message e.g., an ACK/NACK message
  • switching from the first CSI-RS configuration to the second CSI-RS configuration comprises switching from the first CSI-RS configuration to the second CSI-RS configuration without delay after the DCI including the indication to transition to the second CSI-RS configuration is received.
  • switching from the first CSI-RS configuration to the second CSI-RS configuration comprises switching from the first CSI-RS configuration to the second CSI-RS configuration after a delay following receiving the DCI including the indication to transition to the second CSI-RS configuration.
  • switching from the first CSI-RS configuration to the second CSI-RS configuration comprises switching from the first CSI-RS configuration to the second CSI-RS configuration at a quantized timing.
  • A35 The method of example A33, wherein the quantized timing is a first symbol of a first slot after a delay following receiving the DCI including the indication to transition to the second CSI- RS configuration.
  • A36 The method of any one of examples A32-A35, wherein the delay and/or the quantized timing is configured by higher layers (e.g., radio resource control (RRC) signaling).
  • RRC radio resource control
  • A37 The method of any one of examples A32-A35, wherein the DCI includes a timing of CSI- RS configuration transition bit field that indicates the delay and/or the quantized timing.
  • a user equipment (UE) (102) configured with at least a first channel state information (CSI)-reference signal (RS) configuration and a second CSI-RS configuration and adapted to: receive downlink control information (DCI) including an indication to transition to the second CSI-RS configuration; and if the DCI including the indication to transition to the second CSI-RS configuration is received, switch from the first CSI-RS configuration to the second CSI-RS configuration.
  • CSI channel state information
  • RS channel state information-reference signal
  • DCI downlink control information
  • UE user equipment
  • RS channel state information-reference signal
  • the first CSI-RS configuration includes a configuration (e.g., value) for a parameter in a CSI-RS resource, and the second CSI-RS configuration includes a different configuration for the parameter in the CSI-RS resource;
  • the first CSI-RS configuration includes a CSI-RS resource, and the second CSI-RS configuration includes a different CSI-RS resource;
  • the first CSI-RS configuration includes a CSI-RS resource set
  • the second CSI-RS configuration includes a different CSI-RS resource set
  • the one or more existing DCI formats include 0-x uplink formats, 1-x downlink formats, and/or 2-x non-scheduling DCI formats (e.g., a 0-1 uplink format, a 0-2 uplink format, a 1-1 downlink format, a 1-2 downlink format, and/or a 2-6 nonscheduling DCI format).
  • the one or more existing DCI formats include 0-x uplink formats, 1-x downlink formats, and/or 2-x non-scheduling DCI formats (e.g., a 0-1 uplink format, a 0-2 uplink format, a 1-1 downlink format, a 1-2 downlink format, and/or a 2-6 nonscheduling DCI format).
  • C26 The method of example C22 or C24, wherein the indication to transition to the first CSI- RS configuration is transmitted via a radio resource control (RRC) configuration.
  • RRC radio resource control
  • C27 The method of any one of examples C22-C26, further comprising receiving a measurement report conveyed by the UE, the measurement report being based on the first CSI- RS configuration.
  • a network node ( 104) adapted to : transmit downlink control information (DCI) to a user equipment (UE) (102) configured with at least a first channel state information (CSI)-reference signal (RS) configuration and a second CSI-RS configuration, wherein the DCI includes an indication to transition to the second CSI-RS configuration; and transmit one or more CSI-RSs to the UE.
  • DCI downlink control information
  • UE user equipment
  • RS channel state information-reference signal
  • FIG. 1 A carrier containing the computer program of example El, wherein the carrier is one of an electronic signal, optical signal, radio signal, or compute readable storage medium.
  • Gl An apparatus (102 or 104), the apparatus comprising: processing circuitry (202 or 302); and a memory (242 or 342), said memory containing instructions (244 or 344) executable by said processing circuitry, whereby said apparatus is operative to perform the method of any one of the examples A1-A37 and C1-C35.

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Abstract

Methods, systems, and apparatuses for providing indications to transition between channel state information (CSI)-reference signal (RS) configurations. A user equipment (UE) may be configured with at least first and second CSI-RS configurations. The UE may receive downlink control information (DCI) including an indication to transition to the second CSI-RS configuration and, if the DCI including the indication to transition to the second CSI-RS configuration is received, switch from the first CSI-RS configuration to the second CSI-RS configuration.

Description

DCI DESIGN FOR CSI-RS ENHANCEMENTS FOR NR UE
TECHNICAL FIELD
[001] The present disclosure generally relates to the technical field of telecommunication, and particularly to methods and the apparatus for switching channel state information (CSI)- reference signal (RS) configurations.
BACKGROUND
[002] 1.1 Network energy consumption
[003] The network power consumption for New Radio (NR) is said to be less than Long- Term Evolution (LTE) because of NR’s lean design. In the current implementation, however, NR will most likely consume more power than LTE (e.g., due to the higher bandwidth and/or due to introduction of additional elements such as 64 transmit (TX)/receive (RX) ports with several digital radio frequency (RF) chains. As the network is expected to be able to support user equipment (UE) with its maximum capability (e.g., throughput, coverage, etc.), the network may need to use full configuration even when the maximum network support is actually rarely needed by the UEs.
[004] In addition, an increased number of TX/RX ports also leads to an increase to the number of reference signals (e.g., channel state information (CSI)-reference signal (RS)) needed to be transmitted by the network (and to be measured by the UE) for proper signal detection. Thus, the additional TX/RX ports may result in additional power consumption (e.g., to transmit a larger number of CSLRS to the UEs). Furthermore, the larger number of CSLRS transmissions may also consume the valuable network resources.
[005] 1.2 CSLRS configuration
[006] In NR, the CSI-RS generation procedures are defined in the 3rd Generation Partnership Project (3GPP) Technical Specification (TS) 38.211 Section 7.5.1.5. The CSLRS is used for time/frequency tracking, CSI computation, Layer 1 (Ll)-Reference Signal Received Power (RSRP) computation, Ll-Signal to Interference & Noise Ratio (SINR) computation, and mobility. Configured with CSI-RS, the UE then needs to follow the procedures described in 3GPP TS 38.214 Section 5.1.6.1.
[007] For a CSI-RS resource associated with an NZP-CSI-RS-ResourceSet with the higher layer parameter repetition set to 'on', the UE shall not expect to be configured with CSI-RS over the symbols during which the UE is also configured to monitor the Control Resource Set (CORESET). For other NZP-CSI-RS-ResourceSet configurations, if the UE is configured with a CSI-RS resource and a search space set associated with a CORESET in the same orthogonal frequency-division multiplexing (OFDM) symbol(s), the UE may assume that the CSI-RS and a physical downlink control channel (PDCCH) demodulation reference signal (DM-RS) transmitted in all the search space sets associated with CORESET are quasi co-located with 'typeD', if 'typeD' is applicable. This also applies to the case when CSI-RS and the CORESET are in different intra-band component carriers, if 'typeD' is applicable. Furthermore, the UE shall not expect to be configured with the CSI-RS in physical resource blocks (PRBs) that overlap those of the CORESET in the OFDM symbols occupied by the search space set(s).
[008] The UE is not expected to receive CSI-RS and System Information Block #1 (SIB J) message in the overlapping PRBs in the OFDM symbols where SIB1 is transmitted.
[009] If the UE is configured with Discontinuous Reception (DRX): if the UE is configured to monitor downlink control information (DCI) format 2 6 and configured by higher layer parameter ps-TransmitOtherPeriodicCSI to report CSI with the higher layer parameter reportConfigType set to 'periodic' and reportQuantity set to quantities other than CSI-RS Resources Indicator (CRI)-RSRP (‘cri-RSRP’) and Synchronization Signal Block (SSB) Index RSRP ('ssb-Index-RSRP') when drx-onDurationTimer in DRX-Config is not started, the most recent CSI measurement occasion occurs in DRX active time or during the time duration indicated by drx-onDurationTimer in DRX-Config also outside DRX active time for CSI to be reported; if the UE is configured to monitor DCI format 2 6 and configured by higher layer parameter ps-TransmitPeriodicLl-RSRP to report LI -RSRP with the higher layer parameter reportConfigType set to 'periodic' and reportQuantity set to cri-RSRP when drx- onDurationTimer in DRX-Config is not started, the most recent CSI measurement occasion occurs in DRX active time or during the time duration indicated by drx-onDurationTimer in DRX-Config also outside DRX active time for CSI to be reported; otherwise, the most recent CSI measurement occasion occurs in DRX active time for CSI to be reported.
[0010] According to the specification ofNR (i.e., 3GPP TS 38.214 Section 5.2.2.3.1), a UE can be configured with one or more non-zero power (NZP) CSI-RS resource set configuration(s) as indicated by the higher layer parameters CSI-ResourceConfig, and NZP-CSI-RS-ResourceSet. Each NZP CSI-RS resource set consists of K>1 NZP CSI-RS resource(s). TS 38.331 states the following regarding CSI-ResourceConfig'.
- ASN1 START
- TAG-CSI-RESOURCECONFIG-START
CSI-ResourceConfig ::= SEQUENCE { csi-ResourceConfigld CSI-ResourceConfigld. csi-RS-ResourceSetList CHOICE { nzp-CSI-RS-SSB SEQUENCE { nzp-CSI-RS-ResourceSetList SEQUENCE (SIZE (1..maxNrotNZP-CSI-RS-
ResourceSetsPerConfig)) OF NZP-CSI-RS-ResourceSetld OPTIONAL, — Need R csi-SSB-ResourceSetList SEQUENCE (SIZE (1..maxNrofCSLSSB-
ResourceSetsPerConfig)) OF C SI- S SB -Resources etld OPTIONAL — Need R
}, csi-IM-ResourceSetList SEQUENCE (SIZE (L.maxNrofCSI-IM-
ResourceSetsPerConfig)) OF CSLIM-ResourceSetld
}, bwp-Id BWP-Id, resourceType ENUMERATED { aperiodic, semiPersistent, periodic },
- TAG-CSI-RESOURCECONFIG-STOP
- ASN1STOP
[0011] TS 38.331 states the following regarding the NZP-CSI-RS-ResourceSe .
- ASN1 START
- TAG-NZP-CSI-RS-RESOURCESET-START
NZP-CSI-RS-ResourceSet ::= SEQUENCE { nzp-CSI-ResourceSetld NZP-CSI-RS-ResourceSetld, nzp-CSI-RS-Resources SEQUENCE (SIZE ( I ..maxNrofNZP-CSI-RS-
ResourcesPerSet)) OF NZP-CSI-RS-Resourceld, repetition ENUMERATED { on, off }
OPTIONAL, - Need S aperiodicTriggeringOffset INTEGER(0..6)
OPTIONAL, - Need S trs-Info ENUMERATED {true}
OPTIONAL, — Need R
[[ aperiodicTriggeringOffset-r 16 INTEGER(0..31)
OPTIONAL - Need S
]]
}
- TAG-NZP-CSI-RS-RESOURCESET-STOP
- ASN1STOP
[0012] In each of the NZP CSI-RS resources, the network can set the CSI-RS resource with different powerControlOffset, scramblingID, etc. TS 38.331 states the following:
- ASN1 START
- TAG-NZP-CSI-RS-RESOURCE-START
NZP-CSI-RS-Resource ::= SEQUENCE { nzp-CSI-RS-Resourceld NZP-CSI-RS-Resourceld, resourceMapping CSI-RS-ResourceMapping, powerControlOffset INTEGER (-8 .15), powerControlOffsetSS ENUMERATED{db-3, dbO, db3, db6} OPTIONAL, -
Need R scramblingID Scramblingld, periodicityAndOffset CSI-ResourcePeriodicityAndOffset OPTIONAL, —
Cond PeriodicOrSemiPersistent qcl-InfoPeriodicCSI-RS TCI-Stateld OPTIONAL, -
Cond Periodic
}
- TAG-NZP-CSI-RS-RESOURCE-STOP
- ASN1STOP
[0013] Before transmitting, the CSI-RS is mapped according to the configured CSI-RS- Re sour c eMapping. There, the network could set the configuration of the cdm-Type, frequencyDomainAllocation, nrofPorts, etc.
- ASN1 START
- TAG-CSI-RS-RESOURCEMAPPING-START CSI-RS-ResourceMapping ::= SEQUENCE { frequencyDomainAllocation CHOICE { rowl BIT STRING (SIZE (4)), row2 BIT STRING (SIZE (12)), row4 BIT STRING (SIZE (3)), other BIT STRING (SIZE (6)) nrofPorts ENUMERATED {pl,p2,p4,p8,pl2,pl6,p24,p32}, firstOFDMSymbolInTimeDomain INTEGER (0 .13), firstOFDMSymbolInTimeDomain2 INTEGER (2 .12)
OPTIONAL, — Need R cdm-Type ENUMERATED {noCDM, fd-CDM2, cdm4-FD2-TD2, cdm8-FD2-TD4}, density CHOICE { dot5 ENUMERATED {evenPRBs, oddPRBs}, one NULL, three NULL, spare NULL freqBand CSI-FrequencyOccupation,
- TAG-CSI-RS-RESOURCEMAPPING-STOP
- ASN1STOP
[0014] TS. 38.214 section 5.2.2.3.1 provides the following explanation of the CSI-RS parameters: nzp-CSI-RS-Resourceld determines CSI-RS resource configuration identity.
- periodicityAndOjfset defines the CSI-RS periodicity and slot offset for periodic/semi- persi stent CSI-RS . All the CSI-RS resources within one set are configured with the same periodicity, while the slot offset can be same or different for different CSI-RS resources. resourceMapping defines the number of ports, CDM-type, and OFDM symbol and subcarrier occupancy of the CSI-RS resource within a slot that are given in Clause 7.4.1.5 of [4, TS 38.211], nrofPorts in resourceMapping defines the number of CSI-RS ports, where the allowable values are given in Clause 7.4.1.5 of [4, TS 38.211], density in resourceMapping defines CSI-RS frequency density of each CSI-RS port per PRB, and CSI-RS PRB offset in case of the density value of 1/2, where the allowable values are given in Clause 7.4.1.5 of [4, TS 38.211], For density 1/2, the odd/even PRB allocation indicated in density is with respect to the common resource block grid. cdm-Type in resourceMapping defines CDM values and pattern, where the allowable values are given in Clause 7.4.1.5 of [4, TS 38.211],
- powerControlOffset. which is the assumed ratio of PDSCH EPRE to NZP CSI-RS EPRE when UE derives CSI feedback and takes values in the range of [-8, 15] dB with 1 dB step size.
- powerControlOffsetSS'. which is the assumed ratio of NZP CSI-RS EPRE to SS/PBCH block EPRE. scramblingID defines scrambling ID of CSI-RS with length of 10 bits.
BWP -Id in CSI-ResourceConfig defines which bandwidth part the configured CSI-RS is located in. qcl-InfoPeriodicCSI-RS contains a reference to a TCI-State indicating QCL source RS(s) and QCL type(s). If the TCI-State is configured with a reference to an RS configured with qcl-Type set to 'typeD' association, that RS may be an SS/PBCH block located in the same or different CC/DL BWP or a CSI-RS resource configured as periodic located in the same or different CC/DL BWP.
[0015] The CSI-RS resource (or the CSI-RS resource-set) that the UE needs to measure is configured in radio resource control (RRC) configuration (e.g., in the CSI-MeasConfig information element (IE)). In the CSI-MeasConfig IE, the network, based on its certain consideration, may add, or remove (release) the CSI-RS or the (CSI-RS resource-set) that UE needs to measure. 3GPP TS 38.331 states the following:
- ASN1 START
- TAG-CSI-MEASCONFIG-START
CSI-MeasConfig ::= SEQUENCE { nzp-CSLRS-ResourceToAddModList SEQUENCE (SIZE (L.maxNrofNZP-CSI-RS-
Resources)) OF NZP-CSLRS-Resource OPTIONAL, - Need N nzp-CSLRS-ResourceToReleaseList SEQUENCE (SIZE ( I ..maxNrofNZP-CSI-RS-
Resources)) OF NZP-CSLRS-Resourceld OPTIONAL, - Need N nzp-CSLRS-ResourceSetToAddModList SEQUENCE (SIZE (1..maxNrotNZP-CSI-RS-
ResourceSets)) OF NZP-CSI-RS-ResourceSet OPTIONAL, - Need N nzp-CSLRS-ResourceSetToReleaseList SEQUENCE (SIZE (1..maxNrotNZP-CSI-RS-
ResourceSets)) OF NZP-CSI-RS-ResourceSetld csi-IM-ResourceT o AddModLi st SEQUENCE (SIZE (L.maxNrofC SLIM- Resources)) OF CSI-IM-Resource OPTIONAL, - Need N c si -IM-ResourceT oRel easeLi st SEQUENCE (SIZE (L.maxNrofCSI-IM-
Resources)) OF CSI-IM-Resourceld OPTIONAL, - Need N csi-IM-ResourceSetToAddModList SEQUENCE (SIZE (L.maxNrofCSI-IM-
ResourceSets)) OF CSI-IM-ResourceSet OPTIONAL, - Need N csi-IM-ResourceSetToReleaseList SEQUENCE (SIZE (L.maxNrofCSI-IM-
ResourceSets)) OF CSI-IM-ResourceSetld OPTIONAL, — Need N csi-SSB-ResourceSetToAddModList SEQUENCE (SIZE (1..maxNrofCSI-SSB-
ResourceSets)) OF CSI-SSB-ResourceSet OPTIONAL, — Need N csi-SSB-ResourceSetToReleaseList SEQUENCE (SIZE (1. maxNrofCSI-SSB-
ResourceSets)) OF CSI-SSB-ResourceSetld OPTIONAL, — Need N csi-ResourceConfigToAddModList SEQUENCE (SIZE (1..maxNrofCSL
ResourceConfigurations)) OF CSI-ResourceConfig
OPTIONAL, - Need N csi-ResourceConfigToReleaseList SEQUENCE (SIZE (1..maxNrofCSI-
ResourceConfigurations)) OF CSI-ResourceConfigld
OPTIONAL, - Need N csi-ReportConfigToAddModList SEQUENCE (SIZE (1..maxNrofCSI-
ReportConfigurations)) OF CSI-ReportConfig OPTIONAL, — Need N csi-ReportConfigToReleaseList SEQUENCE (SIZE (L.maxNrofCSI-
ReportConfigurations)) OF CSI-ReportConfigld
OPTIONAL, - Need N reportTriggerSize INTEGER (0..6)
OPTIONAL, - Need M aperiodicTriggerStateList SetupRelease { CSLAperiodicTriggerStateList }
OPTIONAL, - Need M semiPersistentOnPUSCH-TriggerStateList SetupRelease { CSI-SemiPersistentOnPUSCH- TriggerStateList } OPTIONAL, — Need M
[[ reportTriggerSizeDCI-0-2-rl6 INTEGER (0..6)
OPTIONAL - Need R
]]
}
- TAG-CSI-MEASCONFIG-STOP
- ASN1STOP
[0016] FIG. 1 shows an overview of the CSLRS parameters that were discussed above. Each parameter is composed of several configurations (e.g., CSI-RS-ResourceMapping is composed of nofPorts. or NZP-CSI-RS-Resource is composed of ResourceMapping and powerControlOffsetsSS parameters). For simplicity, FIG. 1 does not include all the configurations for each parameter. As shown in FIG. 1, parameters are simply a mapping with each other using its different configurations. Most of the parameters are mapped to CSI- MeasConfig. [0017] After receiving the CSI-RS, the UE then reports its measurement back to the network. The reporting configuration for CSI can be aperiodic (e.g., using the Physical Uplink Shared Channel (PUSCH)), periodic (e.g., using the Physical Uplink Control Channel (PUCCH)), or semi-persistent (e.g., using PUCCH, and DCI activated PUSCH). The CSI-RS Resources can be periodic, semi-persistent, or aperiodic. Table 5.2.1.4-1 in TS 38.214 (rewritten below as Table 1) shows the supported combinations of CSI Reporting configurations and CSI-RS Resource configurations and how the CSI Reporting is triggered for each CSI-RS Resource configuration.
Figure imgf000009_0001
Table 1. Triggering/ Activation of CSI Reporting for the Possible CSI-RS Configurations SUMMARY
[0018] Aspects of the invention may relate to downlink control information (DCI) commands to change between channel state information (CSI)-reference signal (RS) configurations. In some aspects, after an application delay, a user equipment (UE) may interpret the DCI bit fields and take action.
[0019] Some aspects of the invention may provide the advantage of efficient utilization of DCI contents for switching between the different CSI-RS configurations.
[0020] Aspects of the invention may relate to a UE configured with multiple CSI-RS configurations. In some aspects, a network node may transmit an indication to change from a first CSI-RS configuration to a second CSI-RS configuration, and the UE may receive the indication. In some aspects, the indication may be transmitted using downlink control information (DCI) or medium access control (MAC) control element (CE). In some aspects, the UE may switch from the first CSI-RS configuration to the second CSI-RS configuration (e.g., immediately or after an application delay). In some aspects, the multiple CSI-RS configurations may be achieved by (i) setting multiple configurations for a parameter in the CSI-RS resource, (ii) setting multiple CSI-RS resources where each of the CSI-RS resource differs in at least one parameter, and (iv) setting multiple CSI-RS resource sets where each of the CSI resource set differs in at least one CSI-RS resource parameter. In some aspects, one of the first and second CSI-RS configurations may be a default configuration. In some aspects, a higher layer configuration of a DCI format may be used for CSI-RS configurations. In some aspects, the DCI may include a bit field (indicating, for example, CSI configuration index, timing of configuration change, or change back to previous configuration). In some aspects, different transitions may use different types of indications (e.g., using DCI to quickly enable support for higher number of layers, where the transition back is using slower indication, such as via a MAC-CE).
[0021] One aspect of the invention may provide a method performed by a user equipment (UE) configured with at least a first channel state information (CSI)-reference signal (RS) configuration and a second CSI-RS configuration. The method may include receiving downlink control information (DCI) including an indication to transition to the second CSI-RS configuration. The method may include, if the DCI including the indication to transition to the second CSI-RS configuration is received, switching from the first CSI-RS configuration to the second CSI-RS configuration.
[0022] Another aspect of the invention may provide a user equipment (UE) configured with at least a first channel state information (CSI)-reference signal (RS) configuration and a second CSI-RS configuration. The UE may be adapted to receive downlink control information (DCI) including an indication to transition to the second CSI-RS configuration. The UE may be adapted to, if the DCI including the indication to transition to the second CSI-RS configuration is received, switch from the first CSI-RS configuration to the second CSI-RS configuration.
[0023] Still another aspect of the invention may provide a method performed by a network node. The method may include transmitting downlink control information (DCI) to a user equipment (UE) configured with at least a first channel state information (CSI)-reference signal (RS) configuration and a second CSI-RS configuration. The DCI may include an indication to transition to the second CSI-RS configuration. The method may include transmitting one or more CSI-RS s to the UE.
[0024] Yet another aspect of the invention may provide a network node. The network node may be adapted to transmit downlink control information (DCI) to a user equipment (UE) configured with at least a first channel state information (CSI)-reference signal (RS) configuration and a second CSI-RS configuration, and the DCI may include an indication to transition to the second CSI-RS configuration. The network node may be adapted to transmit one or more CSI-RSs to the UE.
[0025] Still another aspect of the invention may provide a computer program including instructions for adapting an apparatus to perform any of the methods set forth above.
BRIEF DESCRIPTION OF THE DRAWINGS
[0026] The accompanying drawings, which are incorporated herein and form part of the specification, illustrate various embodiments.
[0027] FIG. 1 provides an overview of the channel state information (CSI)-reference signal (RS) parameter and its configurations.
[0028] FIG. 2 illustrates a UE according to some aspects. [0029] FIG. 3 illustrates a network node according to some aspects.
[0030] FIG. 4 is a flowchart illustrating a process according to some aspects.
[0031] FIG. 5 is a flowchart illustrating a process according to some aspects.
DETAILED DESCRIPTION
[0032] In this application, the term “node” can be a network node or a user equipment (UE). Examples of network nodes include, but are not limited to, a NodeB, a base station (BS), a multistandard radio (MSR) radio node such as a MSR BS, an eNodeB, a gNodeB, a Master eNB (MeNB), a Secondary eNB (SeNB), integrated access backhaul (IAB) node, network controller, radio network controller (RNC), base station controller (BSC), relay, donor node controlling relay, base transceiver station (BTS), Central Unit (e.g. in a gNB), Distributed Unit (e.g. in a gNB), Baseband Unit, Centralized Baseband, C-RAN, access point (AP), transmission points, transmission nodes, remote radio unit (RRU), remote radio head (RRH), nodes in distributed antenna system (DAS), core network node (e.g. MSC, MME, etc.), O&M, OSS, SON, positioning node (e.g. E-SMLC).
[0033] In this application, the term “user equipment” or “UE” is a non-limiting term that refers to any type of wireless device communicating with a network node and/or with another UE in a cellular or mobile communication system. Examples of UEs include, but are not limited to, a target device, a device to device (D2D) UE, a vehicular to vehicular (V2V), a machine type UE, an machine type communication (MTC) UE, a UE capable of machine to machine (M2M) communication, a PDA, a Tablet, a mobile terminal(s), a smart phone, laptop embedded equipment (LEE), laptop mounted equipment (LME), and USB dongles.
[0034] In this application, the terms “radio network node,” “network node,” and “NW node” is generic terminology that refers to any kind of network node including but not limited to a base station, a radio base station, a base transceiver station, a base station controller, a network controller, an evolved Node B (eNB), a Node B, a gNodeB (gNB), a relay node, an access point (AP), a radio access point, a Remote Radio Unit (RRU), a Remote Radio Head (RRH), a Central Unit (e.g., in a gNB), a Distributed Unit (e.g., in a gNB), a Baseband Unit, a Centralized Baseband, a C-RAN, a Mobile Management Entity (MME), and a PDN Gateway (PGW). [0035] In this application, the term “radio access technology” or “RAT” may refer to any RAT including, for example and without limitation, UTRA, E-UTRA, narrow band internet of things (NB-IoT), WiFi, Bluetooth, next generation RAT, New Radio (NR), 4G, and 5G. Any of the equipment denoted by the terms “node,” “network node,” or “radio network node” may be capable of supporting a single or multiple RATs.
[0036] FIG. 2 is a block diagram of a UE 102 according to some aspects. As shown in FIG. 2, the UE 102 may include: processing circuitry (PC) 202, which may include one or more processors (P) 255 (e.g., one or more general purpose microprocessors and/or one or more other processors, such as an application specific integrated circuit (ASIC), field-programmable gate arrays (FPGAs), and the like); communication circuitry 248, which is coupled to an antenna arrangement 249 comprising one or more antennas and which comprises a transmitter (Tx) 245 and a receiver (Rx) 247 for enabling UE 102 to transmit data and receive data (e.g., wirelessly transmit/receive data); and a local storage unit (a.k.a., “data storage system”) 208, which may include one or more non-volatile storage devices and/or one or more volatile storage devices. In some aspects where PC 202 includes a programmable processor, a computer program product (CPP) 241 may be provided. In some aspects, the CPP 241 may include a computer readable medium (CRM) 242 storing a computer program (CP) 243 comprising computer readable instructions (CRI) 244. CRM 242 may be a non-transitory computer readable medium, such as, magnetic media (e.g., a hard disk), optical media, memory devices (e.g., random access memory, flash memory), and the like. In some aspects, the CRI 244 of computer program 243 is configured such that when executed by PC 202, the CRI causes UE 102 to perform steps described herein (e.g., steps described herein with reference to the process 400 shown in FIG. 4). In other aspects, the UE 102 may be configured to perform steps described herein without the need for code. That is, for example, the PC 202 may consist merely of one or more ASICs. Hence, the features of the aspects described herein may be implemented in hardware and/or software.
[0037] FIG. 3 is a block diagram of a network node 104, according to some aspects. As shown in FIG. 3, the network node 104 may comprise: processing circuitry (PC) 302, which may include one or more processors (P) 355 (e.g., one or more general purpose microprocessors and/or one or more other processors, such as an application specific integrated circuit (ASIC), field-programmable gate arrays (FPGAs), and the like), which processors may be co-located in a single housing or in a single data center or may be geographically distributed (i.e., the network node 104 may be a distributed computing apparatus); a network interface 368 comprising a transmitter (Tx) 365 and a receiver (Rx) 367 for enabling the network node 104 to transmit data to and receive data from other nodes connected to a network 110 (e.g., an Internet Protocol (IP) network) to which network interface 368 is connected; communication circuitry 348, which is coupled to an antenna arrangement 349 comprising one or more antennas and which comprises a transmitter (Tx) 345 and a receiver (Rx) 347 for enabling the network node 104 to transmit data and receive data (e.g., wirelessly transmit/receive data); and a local storage unit (a.k.a., “data storage system”) 308, which may include one or more non-volatile storage devices and/or one or more volatile storage devices. In aspects where PC 302 includes a programmable processor, a computer program product (CPP) 341 may be provided. CPP 341 includes a computer readable medium (CRM) 342 storing a computer program (CP) 343 comprising computer readable instructions (CRI) 344. CRM 342 may be a non-transitory computer readable medium, such as, magnetic media (e.g., a hard disk), optical media, memory devices (e.g., random access memory, flash memory), and the like. In some aspects, the CRI 344 of computer program 343 may be configured such that when executed by PC 302, the CRI causes the network node 104 to perform steps described herein (e.g., steps described herein with reference to the process 500 shown in FIG. 5). In other aspects, the network node 104 may be configured to perform steps described herein without the need for code. That is, for example, PC 302 may consist merely of one or more ASICs. Hence, the features of the aspects described herein may be implemented in hardware and/or software.
[0038] Aspects of the present invention may enable a fast and/or resource efficient dynamic CSI-RS configuration adaption. In some aspects, the dynamic CSI-RS configuration adaption may be enabled by:
(a) configuring multiple resource mappings, or multiple configurations per parameter within a channel state information (CSI)-reference signal (RS) resource (e.g., different number of ports, power control offset, and/or quasi-colocation (QCL) information, etc.) and using medium access control (MAC) control element (CE) or downlink control information (DCI) to activate or deactivate a certain configuration (and/or to switch between those configurations); (b) configuring multiple CSI-RS resources within one CSI-RS resource set and using MAC CE or DCI to activate or deactivate the configured CSI-RS resources (and/or to switch between CSI-RS resources);
(c) configuring multiple CSI-RS resource sets and using MAC CE or DCI to activate or deactivate one or more configured CSI-RS resource set (or switch between CSI-RS resource sets); and/or
(d) other CSI-RS parameters included in CSI-Measconfig can have multiple CSI-RS configurations and using MAC CE or DCI to activate or deactivate one or more configured CSI-RS resource set (and/or to switch between CSI-RS resource sets).
[0039] In some aspects, the UE 102 may be configured with more than one CSI-RS configuration. Aspects of the invention may provide a fast dynamic adaptation mechanism in which the UE 102 is capable of being caused (e.g., indicated) to switch between different CSI- RS configurations. In some aspects, the switching may be, for example, done by the network node 104 during the port adaptation (e.g., port adaptation in which the network node 104 determines to change the number of ports that will be used to serve the UE 102).
[0040] In some aspects, the term “multiple CSI-RS configurations” may refer to multiple CSI-RS configurations that can be activated or deactivated or switched through MAC-CE or DCI signaling. That is, the multiple CSI-RS confirmations are different than existing CSI-RS configurations in which multiple CSI-RS configurations are added or released through RRC (re)configuration.
[0041] In some aspects, the bit field in the DCI may indicate whether the default configuration or another configuration is activated. In some aspects, the UE 102 may be configured with a first CSI-RS configuration and a second CSI-RS configuration with the first configuration being the default. In some aspects, an additional bit in the DCI (e.g., DCI 1-1/2) may be configured. In some aspects, if the UE 102 receives the additional bit in the DCI, and the additional bit has a first bit status (e.g., a bit status of “1”), the UE 102 may consider the second CSI-RS configuration as activated and may consider the first (e.g., default) CSI-RS configuration as deactivated. In some aspects, if the UE 102 receives the additional bit in the DCI, and the additional bit has a second bit status (e.g., a bit status of “0”), which may be considered reserved, the UE 102 may consider the first (e.g., default) CSI-RS configuration as the active configuration. In some alternative aspects, the DCI may include two or more additional bits, and the number of additional bits in the DCI may depend on the number of CSI-RS configurations (e.g., the DCI may include two additional bits to specify one of up to four CSI-RS configurations, and 00 may indicate the default CSI-RS configuration).
[0042] In some aspects, when multiple configurations are not set for the UE 102, a legacy behavior may apply. For example, in some aspects, if multiple CSI-RS configurations are not set for the UE 102, the UE 102 may need to monitor all of the CSI-RS, which may be included in, for example, CSI-MeasConfig. In another example, in some aspects, the additional bit field in the DCI used for the adaptation indication may not be included in the DCI transmitted to the UE 102.
[0043] In some aspects, by configuring the UE 102 with multiple CSI-RS configurations that can be activated/deactivated or switched (e.g., through MAC-CE or DCI), the network node 104 may have flexibility on which CSI-RS should be used at one time instance. In some aspects, the network node 104 may select the active CSI-RS configurations based on, for example, the state of the port adaptation. For example, in some aspects, the network node 104 may use the following process to exploit the multiple CSI-RS configurations.
[0044] In some aspects, the process may include a first step in which the network node 104 configures the UE 102 with multiple CSI-RS configurations (e.g., including at least first and second CSI-RS configurations). In some aspects, in the first step, the network node 104 configures the UE 102 with multiple CSI-RS configurations by, for example, configuring the UE 102 to have more than one parameter configuration (e.g., parameters inside the CSI-RS- ResourceMapping IE).
[0045] In some aspects, the process may include a second step in which the network node 104 causes (e.g., indicates) the UE 102 to switch from the first CSI-RS configuration to the second CSI-RS configuration. In some aspects, the network node 104 may decide to change the CSI-RS configuration, for example, when there are no more UEs 102 active in the cell, or when no UEs 102 are active that require or can take advantage of transmission with a large number of ports (e.g., sustained transmission with multiple layers and narrow beams). In some aspects, in this situation, the network node 104 may decide to switch from the first CSI-RS configuration suitable for a larger number of ports transmission to the second CSI-RS configuration suitable for a smaller number of ports transmission. In some aspects, as described above, the network node 104 may cause (e.g., indicate) the UE 102 to switch CSI-RS configurations, for example, via DCI or MAC-CE.
[0046] In some aspects, the process may include a third step in which, after sending the switching indication, the network node 104 transmits the CSI-RS according to the second CSI- RS configuration.
[0047] In some aspects, the network node 104 may configure the UE 102 through higher layer signaling (e.g., radio resource control (RRC) signaling) if the activation/deactivation mechanism is DCI based, MAC CE based, and also the underlying configuration (e.g., additional bit field and its interpretation in the DCI). In some alternative aspects, the UE 102 may be preconfigured (e.g., as in standardization documentations). For example, in some aspects, if there are two fields configured for a parameter (e.g., number of ports), then the UE 102 may automatically expect a MAC CE or DCI to be able to activate or deactivate the configurations (e.g., as determined in the standards).
[0048] In some aspects, on the UE 102 side, the UE 102 may receive multiple CSI-RS configurations (e.g., including at least first and second CSI-RS configurations). In some aspects, the UE 102 may receive the multiple CSI-RS configurations, for example, through RRC signaling. In some aspects, the UE 102 may measure or report based on the first configuration as the default configuration. In some aspects, the UE 102 may, in one time instant, receive a MAC CE command or a DCI indicating that the UE 102 should perform measurements or reporting based on the second configuration. In some aspects, the UE 102 may measure the CSI-RS based on the second CSI-RS configuration or report CSI based on measuring the second CSI-RS configuration.
[0049] In some aspects, a group of UEs 102 may receive command to switch to a second CSI-RS configuration. In some aspects, this may be implemented, for example, as a group MAC or a DCI using group common search space. In some aspects, a group of UEs 102 can be configured to, using low signaling overhead and low latency, switch CSI-RS configurations. In some aspects, the individual CSI-RS configurations may still be configured per-UE. In some aspects, the group switching command may be, for example, formulated as: (a) all UEs 102 in group switch to specific configuration index (e.g., switch to nzp-CSI-RS-ResourcesDefault or nzp-CSI-RS-ResourcesB), or (b) all UEs 102 in group switch to an implicitly indicated configuration (e.g., switch to CSI-RS configuration with shortest periodicity, densest allocation in time/frequency, largest number of ports, etc.).
[0050] In some aspects, to choose between a number of different CSI-RS configurations, the UE 102 may be given a bit field in DCI. In some aspects, the bit field in DCI may indicate whether the default CSI-RS configuration or another CSI-RS configuration is activated. In some aspects, the UE 102 may be configured with a first CSI-RS configuration and a second CSI-RS configuration with the first one as the default. In some aspects, an additional bit in the DCI (e.g., DCI 1-1/2) may be configured. In some aspects, if the UE 102 receives the additional bit in the DCI, and the additional bit has a first bit status (e.g., a bit status of “1”), the UE 102 may consider the second CSI-RS configuration as activated and may consider the first (e.g., default) CSI-RS configuration as deactivated. In some aspects, if the UE 102 receives the additional bit in the DCI, and the additional bit has a second bit status (e.g., a bit status of “0”), which may be considered reserved, the UE 102 may consider the first (e.g., default) CSI-RS configuration as the active configuration.
[0051] In some aspects, each bit of a bit field in DCI may be mapped to different CSI-RS parameters. For example, in some embodiments, a bit of the bit field having a second bit status (e.g., a bit status of “0”) may indicate a default configuration for the CSI-RS parameter (e.g., nrofPortsDefault, densityDefault, powerControlOffsetSSDefault, qcl-InfoPeriodicCSI- RSDefault, or nzp-CSI-RS-ResourcesDefaulf) to which the bit is mapped. In some embodiments, a bit of the bit field having a first bit status (e.g., a bit status of “1”) may indicate a different configuration for the CSI-RS parameter (e.g., nrofPortsB, densityB. powerControlOffsetSS B , qcl-InfoPeriodicCSI-RS B, and/or nzp-CSI-RS-ResourcesB') to which the bit is mapped. In some alternative aspects, one bit in DCI may be used to indicate the default configuration for the CSI-RS parameters or the second configuration with all its underlying second configuration parameters.
[0052] For some aspects in which there are only two different CSI-RS configurations, one additional bit in the DCI bit field is enough to choose between the two different CSI-RS configurations. However, for aspects in which there are three or more CSI-RS configurations, a larger bit field in the DCI may be used. In some aspects, the number of bits of the DCI bit field used for choosing between different CSI-RS configurations may be higher layer configured. In some alternative aspects, the number of bits of the DCI bit field used for choosing between different CSI-RS configurations may be defined in the standard with a certain number of bits for different scenarios.
[0053] In some aspects in which the number of DCI bits is configured by a higher layer (e.g., either explicitly or derived from the number of configured CSI-RS configurations), the standard may also define the limit of the maximum number of bits that can be configured. For example, the higher layer may configure the bit field with the size of 1, . . ., X number of bits, where X is defined in the standard. In some aspects, the maximum CSI-RS configurations may depend on the maximum number of ports that a system can support. In some aspects, in addition to the number of bits, higher layer signaling (e.g., RRC signaling) may be used in order to configure the start and length of the bit field. In some aspects, the start of the bit field may be an explicit location in the DCI. In some alternative aspects, the start of the bit field may be a relative location (e.g., after time or frequency resource allocation bit field) in case a scheduling DCI is used.
[0054] In some aspects, when more than 1 bit in the bit field is supported, a codepoint or bitmap-based indication may be used. For example, in some aspects, for the case of a codepoint based indication with the size of 2 bits, the first, second, third, and fourth configuration can be indicated by a bit combination of 00, 01, 10, and 11, respectively. As such, in some of these aspects, X = log2 K], where Y is the total number of different CSI-RS configurations.
[0055] In some aspects, the CSI-RS enhancement bit field may be an additional bit field on top of the existing bit field in DCI(s).
[0056] In some alternative aspects, the CSI-RS enhancement bit field may reuse the existing bit field. In some existing bit field reuse aspects, the UE 102 may determine whether the bit field is used as the existing bit field or as the CSI-RS enhancement bit field based on whether a certain parameter is configured in the higher layer configuration. For example, in some aspects, if at least one second configuration parameter (e.g., at least one of nrofPortsB, densityB , powerControlOffsetSS B , etc.) is configured, the UE 102 may interpret the bit field as a CSI-RS enhancement bit field. Otherwise, if none of the second configuration parameter is configured, the UE 102 may interpret the bit field as the existing bit field. For another example, in some aspects, a new parameter may be configured in the higher layer to determine the interpretation of the bit field. For example, if the new parameter (e.g., adaptiveCSI- RS enabled) is set to true, then the UE 102 may interpret the bit field as a CSI-RS enhancement bit field, and, if the new parameter is set to false (or if it is not configured), then the UE 102 may interpret the bit field as the existing bit field.
[0057] In some other alternative aspects, an indication to an invalid index within the current DCIs may also be used for the above purposes (e.g., referring to an invalid modulation coding scheme (MCS) index in a scheduling DCI can be used to indicate the change to a new configuration or going back to default, etc.).
[0058] In some aspects, the UE 102 may instantaneously switch to another CSI-RS configuration after having received the instruction. In some alternative aspects, the switch may take effect after a certain pre-defined time or application delay. In some aspects, the predefined time may be quantized to certain possible timings (e.g., the configuration can take effect the next slot fulfilling the condition slot number mod M = 0, where mod is the modulo operation). In some other aspects, if the predefined time is specified in a symbol basis, the UE 102 may switch at the first symbol of the first slot after the predefined time. In some aspects, the time until the configuration change takes effect may additionally or alternatively be configured by the higher layers or included by adding additional bit fields in the DCI and then indicated through the DCI. For example, in some aspects, higher layers may configure multiple application delays, and the additional bits in the bit field in the DCI may be used to indicate one of the application delays. In some aspects, if higher layers do not configure the application delay, (a) the application delay may be pre-configured (e.g., as part of the standardization documentations), or (b) the UE 102 may apply the configuration change immediately. In some aspects, the standard may define the maximum or minimum time that is allowed for the switching between CSI-RS configurations. In some aspects, the predefined time may be different (e.g., based on the capability of the UE 102 and/or subcarrier spacing (SCS)). [0059] PCI formats
[0060] In some aspects, the CSI-RS enhancement bit field may be included in an existing DCI format. In some aspects, the CSI-RS enhancement bit field may be included in existing 0- x uplink formats, 1-x downlink formats, or 2-x non-scheduling DCI formats, such as 0-1, 0-2, 1-1, 1-2, and 2-6. In some aspects, the fallback DCI formats 0-0 and 1-0, which have a tighter size requirement, may not be suitable for addition of extra bits.
[0061] In some aspects, the DCI may be sent to a group of UEs 102 scrambled by a group Radio Network Temporary Identifier (RNTI). For example, in some aspects, the scrambling by a group RNTI may be applied for group of UEs 102 that uses common quasi-colocation ports in the network-side and can be configured using a common CSI-RS (e.g., UEs 102 that are closer together resulting to QCL-TypeD (spatial Rx parameters)). Some aspects may use DCI format 2-6 using a power saving RNTI (PS-RNTI). In some alternative aspects, the DCI may be sent using another existing group common RNTIs or with a new DCI format with a new RNTI.
[0062] Different message types for different transitions
[0063] In some aspects, the transitions between the CSI-RS configurations may be triggered by DCI commands and/or MAC CE commands. In some aspects, the DCI triggering may lead to a lower latency (relative to MAC CE commands) but may also consume more system resources, as there are not as many bits at disposal in DCI. Also, in case the information is not included in an existing DCI, this would lead to transmission of an extra physical downlink control channel (PDCCH), which increases the overhead.
[0064] In some aspects, the transmission of the indication of a transition from a first state to a second state may be done using DCI, and the transmission of the indication of a transition from the second state to the first state may be done with a higher-latency command (e.g., a MAC CE or an RRC configuration). In some aspects, the fast transmission may be used when the CSI-RS configuration should be increased, because the network node 104 (e.g., gNb) may quickly enable support for transmission using higher number of layers without affecting the transmission latency. In some aspects, the transmission back to a lower-density CSI-RS configuration may be done with more slack latency requirements, as this will not harm the transmission latency (but may harm only the transmission power during a short period). In some aspects, the number of bits configured in the DCI bit field may also be determined as X = log2(Y — 1)], where Y is the total number of different CSI-RS configurations, and the higher latency command may be used to indicate the transition to the default CSI-RS configuration.
[0065] Misalignment handling
[0066] In some aspects, if the UE 102 missed a DCI indicating a CSI-RS configuration transition or if a false alarm occurs in which the UE 102 misinterprets a DCI as indicating a CSI-RS configuration transition (the chance of false alarm is very low considering a DCI is CRC coded), a misalignment can happen between the network node 104 and the UE 102. For example, the network node 104 may indicate to the UE 102 that the UE 102 should use a second CSI-RS configuration after an application delay, while the UE was measuring over the first one. If the UE 102 misses this indication, the UE 102 may keep performing measurements on the first configuration, which is not valid anymore, and this can impact the performance of the UE 102.
[0067] In some aspects (e.g., if the existing DCI is a scheduling DCI), the network node 104 may understand that the UE 102 has missed the DCI (e.g., if the UE 102 does not send an ACK/NACK message, or if the UE 102 does not report the CSI if requested). In some aspects, if the network node 104 determines that the UE 102 has missed a DCI indicating a CSI-RS configuration transition, the network node 104 may send the DCI again to make sure the UE 102 measures the correct CSI-RS configuration. In some aspects, a number of attempts may be defined to avoid the network node 104 over signaling to the UE 102. In some aspects, the network node 104 may indicate the number of attempts in the DCI until it is successful so that UE 102 can adjust the misalignment for the next CSI-RS configuration.
[0068] In some aspects (e.g., if a non-scheduling DCI is used to indicate a CSI-RS configuration transition), the UE 102 may not show any immediate feedback, and, as a result, it may be more complicated for the network node 104 to detect whether the UE 102 has missed the DCI. For example, in some aspects, a new DCI format may indicate the change to a second configuration, and, if the UE 102 misses the DCI, the UE 102 may keep performing measurements on the first configuration. In some aspects, a configured or pre-configured acknowledgement (ACK) mechanism for one or more specific DCI formats may be used, which may prevent or reduce misalignments between the UE 102 and the network node 104.
[0069] FIG. 4 illustrates a process 400 performed by the user equipment (UE) 102 according to some aspects. The UE 102 may be configured with at least a first channel state information (CSI)-reference signal (RS) configuration and a second CSI-RS configuration.
[0070] In some aspects: (a) the first CSI-RS configuration may include a configuration (e.g., value) for a parameter in a CSI-RS resource, and the second CSI-RS configuration may include a different configuration for the parameter in the CSI-RS resource; (b) the first CSI-RS configuration may include a CSI-RS resource, and the second CSI-RS configuration may include a different CSI-RS resource; and/or (c) the first CSI-RS configuration may include a CSI-RS resource set, and the second CSI-RS configuration may include a different CSI-RS resource set. In some aspects, the first CSI-RS configuration may be a default CSI-RS configuration, and the second CSI-RS configuration may be a non-default CSI-RS configuration.
[0071] In some aspects, the process 400 may include an optional step 402 in which the UE 102 receives the first and second CSI-RS configurations. In some aspects, the first and second CSI-RS configurations may be transmitted by the network node 104.
[0072] In some aspects, the process 400 may include a step 404 in which the UE 102 receives downlink control information (DCI) including an indication to transition to the second CSI-RS configuration.
[0073] In some aspects, the DCI may include a CSI-RS configuration bit field, and a status of one or more bits of the CSI-RS configuration bit field may provide the indication to transition to the second CSI-RS configuration. In some aspects, the CSI-RS configuration bit field in the DCI may include only one bit. In some alternative aspects, the UE 102 may be further configured with at least third and fourth CSI-RS configurations, and the CSI-RS configuration bit field in the DCI may include at least two bits. In some aspects, the CSI-RS configuration bit field in the DCI may include X bits, the UE 102 may be configured with Y or fewer CSI-RS configuration, X may be greater than or equal to 1, and X may equal to log2 Y. In some aspects, the CSI-RS configuration bit field in the DCI may include X bits, the UE 102 may be configured with Y or fewer CSI-RS configuration, X may be greater than or equal to 1, and X may equal log2 (Y-l). In some aspects, the number of bits in CSI-RS configuration bit field may be configured by higher layer signaling (e.g., radio resource control (RRC) signaling).
[0074] In some aspects, a start of the CSI-RS configuration bit field may be configured by higher layer signaling (e.g., radio resource control (RRC) signaling). In some aspects, the start of the CSI-RS configuration bit field may be an explicit location in the DCI. In some aspects, the start of the CSI-RS configuration bit field may be a relative location in the DCI (e.g., after time or frequency resource allocation bit field).
[0075] In some aspects, the CSI-RS configuration bit field may be a new bit field in addition to existing DCI bit fields. In some alternative aspects, the CSI-RS configuration bit field may reuse an existing DCI bit field. In some aspects, the UE 102 may interpret the existing DCI bit field as the CSI-RS configuration bit field if a parameter is configured. In some aspects, the parameter may be an existing parameter (e.g., at least one of nrofPortsB, densityB, powerControlOffsetSS B). In some aspects, the parameter may be a new parameter (e.g., adaptiveCSI-RS enabled). In some aspects, the indication to transition to the second CSI-RS configuration may be an invalid index within the existing DCI bit field.
[0076] In some aspects, the CSI-RS configuration bit field may be included in one or more existing DCI formats. In some aspects, the one or more existing DCI formats may include 0-x uplink formats, 1-x downlink formats, and/or 2-x non-scheduling DCI formats (e.g., a 0-1 uplink format, a 0-2 uplink format, a 1-1 downlink format, a 1-2 downlink format, and/or a 2-6 nonscheduling DCI format).
[0077] In some aspects, the DCI is scrambled by a group Radio Network Temporary Identifier (RNTI).
[0078] In some aspects, the process 400 may include a step 406 in which the UE 102, if the DCI including the indication to transition to the second CSI-RS configuration is received in step 404, switches from the first CSI-RS configuration to the second CSI-RS configuration.
[0079] In some aspects, switching from the first CSI-RS configuration to the second CSI-RS configuration in step 406 may include switching from the first CSI-RS configuration to the second CSI-RS configuration without delay after the DCI including the indication to transition to the second CSI-RS configuration is received. In some alternative aspects, switching from the first CSI-RS configuration to the second CSI-RS configuration in step 406 may include switching from the first CSI-RS configuration to the second CSI-RS configuration after a delay following receiving the DCI including the indication to transition to the second CSI-RS configuration. In some other alternative aspects, switching from the first CSI-RS configuration to the second CSI-RS configuration in step 406 may include switching from the first CSI-RS configuration to the second CSI-RS configuration at a quantized timing. In some aspects, the quantized timing may be a slot having a slot number (slot no), and slot no mod M may equal zero (i.e., slot no mod M = 0). In some aspects, the quantized timing may be a first symbol of a first slot after a delay following receiving the DCI including the indication to transition to the second CSI-RS configuration. In some aspects, the delay and/or the quantized timing may be configured by higher layers (e.g., radio resource control (RRC) signaling). In some aspects, the DCI may include a timing of CSI-RS configuration transition bit field that indicates the delay and/or the quantized timing.
[0080] In some aspects, the process 400 may include an optional step 408 in which the UE 102, if the DCI is received in step 404, sends an acknowledgement message (e.g., an ACK/NACK message). In some aspects, the DCI may be a scheduling DCI. In some aspects, the DCI may be a non-scheduling DCI.
[0081] In some aspects, the process 400 may include an optional step 410 in which the UE 102 performs CSI-RS measurements and/or reporting based on the second CSI-RS configuration.
[0082] In some aspects, the process 400 may include an optional step 412 in which the UE 102 receives an indication to transition to the first CSI-RS configuration. In some aspects, the indication to transition to the first CSI-RS configuration may be received via DCI. In some alternative aspects, the indication to transition to the first CSI-RS configuration may be a command having a higher latency than a DCI command. In some aspects, the indication to transition to the first CSI-RS configuration may be received via a medium access control (MAC) control element (CE). In some aspects, the indication to transition to the first CSI-RS configuration may be received via a radio resource control (RRC) configuration.
[0083] In some aspects, the process 400 may include an optional step 414 in which the UE 102, if the indication to transition to the first CSI-RS configuration is received in step 414, switches from the second CSI-RS configuration to the first CSI-RS configuration. [0084] In some aspects, the process 400 may further include an optional step 416 in which the UE 102 performs CSI-RS measurements and/or reporting based on the first CSI-RS configuration.
[0085] FIG. 5 illustrates a process 500 performed by the network node 104 according to some aspects.
[0086] In some aspects, the process 500 may include an optional step 502 in which the network node 104 transmits first and second CSI-RS configurations to a UE 102.
[0087] In some aspects, the process 500 may include a step 504 in which the network node 104 transmits DCI to the UE 102. The UE 102 may be configured with at least first and second CSI-RS configurations. The DCI may include an indication to transition to the second CSI-RS configuration.
[0088] In some aspects: (a) the first CSI-RS configuration may include a configuration (e.g., value) for a parameter in a CSI-RS resource, and the second CSI-RS configuration may include a different configuration for the parameter in the CSI-RS resource; (b) the first CSI-RS configuration may include a CSI-RS resource, and the second CSI-RS configuration may include a different CSI-RS resource; and/or (c) the first CSI-RS configuration may include a CSI-RS resource set, and the second CSI-RS configuration may include a different CSI-RS resource set. In some aspects, the first CSI-RS configuration may be a default CSI-RS configuration, and the second CSI-RS configuration may be a non-default CSI-RS configuration.
[0089] In some aspects, the DCI may include a CSI-RS configuration bit field, and a status of one or more bits of the CSI-RS configuration bit field may provide the indication to transition to the second CSI-RS configuration. In some aspects, the CSI-RS configuration bit field in the DCI may include only one bit. In some alternative aspects, the UE 102 may be further configured with at least third and fourth CSI-RS configurations, and the CSI-RS configuration bit field in the DCI may include at least two bits. In some aspects, the CSI-RS configuration bit field in the DCI may include X bits, the UE 102 may be configured with Y or fewer CSI-RS configuration, X may be greater than or equal to 1, and X may equal log2 Y. In some aspects, the CSI-RS configuration bit field in the DCI may include X bits, the UE may be configured with Y or fewer CSI-RS configuration, X may be greater than or equal to 1, and X may be log2 (Y-l). In some aspects, the number of bits in CSI-RS configuration bit field may be configured by higher layer signaling (e.g., RRC signaling).
[0090] In some aspects, a start of the CSI-RS configuration bit field may be configured by higher layer signaling (e.g., RRC signaling). In some aspects, the start of the CSI-RS configuration bit field is an explicit location. In some aspects, the start of the CSI-RS configuration bit field may be a relative location.
[0091] In some aspects, the CSI-RS configuration bit field may be a new bit field in addition to existing DCI bit fields. In some alternative aspects, the CSI-RS configuration bit field may reuse an existing DCI bit field. In some aspects, the UE 102 may interpret the existing DCI bit field as the CSI-RS configuration bit field if a parameter is configured. In some aspects, the parameter may be an existing parameter (e.g., at least one of nrofPortsB, densityB, powerControlOffsetSS B). In some aspects, the parameter may be a new parameter (e.g., adaptiveCSI-RS enabled). In some aspects, the indication to transition to the second CSI-RS configuration may be an invalid index within an existing DCI bit field.
[0092] In some aspects, the CSI-RS configuration bit field may be included in one or more existing DCI formats. In some aspects, the one or more existing DCI formats may include 0-x uplink formats, 1-x downlink formats, and/or 2-x non-scheduling DCI formats (e.g., a 0-1 uplink format, a 0-2 uplink format, a 1-1 downlink format, a 1-2 downlink format, and/or a 2-6 nonscheduling DCI format).
[0093] In some aspects, the DCI may be scrambled by a group Radio Network Temporary Identifier (RNTI).
[0094] In some aspects, the DCI may include a timing of CSI-RS configuration transition bit field that indicates a delay and/or a quantized timing for the UE 102 to switch to the second CSI- RS configuration. In some aspects, the quantized timing may be a slot having a slot number (slot no), and slot no mod M may equal zero (i.e., slot no mod M = 0). In some aspects, the quantized timing may be a first symbol of a first slot after the delay following the UE 102 receiving the DCI including the indication to transition to the second CSI-RS configuration.
[0095] In some aspects, the process 500 may include an optional step 506 in which the network node 104 receives an acknowledgement message (e.g., an ACK/NACK message) transmitted by the UE 102. In some aspects, the DCI may be a scheduling DCI. In some aspects, the DCI may be a non-scheduling DCI. In some aspects, the process 500 may include an optional step in which the network node 104 determines that an acknowledgement message has not been received and re-transmitting DCI including the indication to transition to the second CSI-RS configuration.
[0096] In some aspects, the process 500 may include a step 508 in which the network node 104 transmits one or more CSI-RSs to the UE 102. In some aspects, the one or more CSI-RSs transmitted in step 508 may correspond to the second CSI-RS configuration.
[0097] In some aspects, the process 500 may include an optional step 510 in which the network node 104 receives a measurement report conveyed by the UE 102. In some aspects, the measurement report may be based on the second CSI-RS configuration.
[0098] In some aspects, the process 500 may include an optional step 512 in which the network node 104 transmits an indication for the UE 102 to transition to the first CSI-RS configuration. In some aspects, the network node 104 may transmit the indication to transition to the first CSI-RS configuration via DCI. In some aspects, the indication to transition to the first CSI-RS configuration may be a command having a higher latency than a DCI command. In some aspects, the network node 104 may transmit the indication to transition to the first CSI-RS configuration via a medium access control (MAC) control element (CE). In some aspects, the network node 104 may transmit the indication to transition to the first CSI-RS configuration via a radio resource control (RRC) configuration.
[0099] In some aspects, the process 500 may include an optional step 514 in which the network node 104 transmits one or more CSI-RSs to the UE 102. In some aspects, the one or more CSI-RSs transmitted in step 514 may correspond to the first CSI-RS configuration
[00100] In some aspects, the process 500 may include an optional step 516 in which the network node 104 receives a measurement report conveyed by the UE 102, and the measurement report may be based on the first CSI-RS configuration. [00101] Examples
Al . A method (400) performed by a user equipment (UE) (102) configured with at least a first channel state information (CSI)-reference signal (RS) configuration and a second CSI-RS configuration, the method comprising: receiving downlink control information (DCI) including an indication to transition to the second CSI-RS configuration; and if the DCI including the indication to transition to the second CSI-RS configuration is received, switching from the first CSI-RS configuration to the second CSI-RS configuration. A2. The method of example Al, wherein:
(a) the first CSI-RS configuration includes a configuration (e.g., value) for a parameter in a CSI-RS resource, and the second CSI-RS configuration includes a different configuration for the parameter in the CSI-RS resource;
(b) the first CSI-RS configuration includes a CSI-RS resource, and the second CSI-RS configuration includes a different CSI-RS resource; and/or
(c) the first CSI-RS configuration includes a CSI-RS resource set, and the second CSI-RS configuration includes a different CSI-RS resource set.
A3. The method of example Al or A2, wherein the first CSI-RS configuration is a default CSI-RS configuration, and the second CSI-RS configuration is a non-default CSI-RS configuration.
A4. The method of any one of examples Al -A3, further comprising performing CSI-RS measurements and/or reporting based on the second CSI-RS configuration.
A5. The method of any one of examples A1-A4, wherein the DCI includes a CSI-RS configuration bit field, and a status of one or more bits of the CSI-RS configuration bit field provides the indication to transition to the second CSI-RS configuration.
A6. The method of example A5, wherein the CSI-RS configuration bit field in the DCI comprises only one bit.
A7. The method of example A5, wherein the UE is further configured with at least third and fourth CSI-RS configurations, and the CSI-RS configuration bit field in the DCI comprises at least two bits. A8a. The method of any one of examples A5-A7, wherein the CSI-RS configuration bit field in the DCI comprises X bits, the UE is configured with Y or fewer CSI-RS configuration, X is greater than or equal to 1, and X = log2 Y.
A8b. The method of any one of examples A5-A7, wherein the CSI-RS configuration bit field in the DCI comprises X bits, the UE is configured with Y or fewer CSI-RS configuration, X is greater than or equal to 1, and X = log2 (Y-l).
A9. The method of any one of examples A5-A8b, wherein the number of bits in CSI-RS configuration bit field is configured by higher layer signaling (e.g., radio resource control (RRC) signaling).
A10. The method of any one of examples A5-A9, wherein a start of the CSI-RS configuration bit field is configured by higher layer signaling (e.g., radio resource control (RRC) signaling). Al 1. The method of example A10, wherein the start of the CSI-RS configuration bit field is an explicit location.
A12. The method of example A10, wherein the start of the CSI-RS configuration bit field is a relative location.
A13. The method of any one of examples A5-A12, wherein the CSI-RS configuration bit field is a new bit field in addition to existing DCI bit fields.
A14. The method of any one of examples A5-A12, wherein the CSI-RS configuration bit field reuses an existing DCI bit field.
A15. The method of example A14, wherein the UE interprets the existing DCI bit field as the CSI-RS configuration bit field if a parameter is configured.
Al 6. The method of example Al 5, wherein the parameter is an existing parameter (e.g., at least one of nrofPortsB, densityB. powerControlOffsetSS B).
Al 7. The method of example Al 5, wherein the parameter is a new parameter (e.g., adaptiveCSI-RS enabled).
Al 8. The method of example A14, wherein the indication to transition to the second CSI-RS configuration is an invalid index within the existing DCI bit field.
A19. The method of any one of examples A5-A18, wherein the CSI-RS configuration bit field is included in one or more existing DCI formats.
A20. The method of example Al 9, wherein the one or more existing DCI formats include 0-x uplink formats, 1-x downlink formats, and/or 2-x non-scheduling DCI formats (e.g., a 0-1 uplink format, a 0-2 uplink format, a 1-1 downlink format, a 1-2 downlink format, and/or a 2-6 nonscheduling DCI format).
A21. The method of any one of examples A1-A20, wherein the DCI is scrambled by a group Radio Network Temporary Identifier (RNTI).
A22. The method of any one of examples A1-A21, further comprising: receiving an indication to transition to the first CSI-RS configuration; and if the indication to transition to the first CSI-RS configuration is received, switching from the second CSI-RS configuration to the first CSI-RS configuration.
A23. The method of example A22, wherein the indication to transition to the first CSI-RS configuration is received via DCI.
A24. The method of example A22, wherein the indication to transition to the first CSI-RS configuration is a command having a higher latency than a DCI command.
A25. The method of example A22 or A24, wherein the indication to transition to the first CSI- RS configuration is received via a medium access control (MAC) control element (CE).
A26. The method of example A22 or A24, wherein the indication to transition to the first CSI- RS configuration is received via a radio resource control (RRC) configuration.
A27. The method of any one of examples A22-A26, further comprising performing CSI-RS measurements and/or reporting based on the first CSI-RS configuration.
A28. The method of any one of examples A1-A27, further comprising, if the DCI is received, sending an acknowledgement message (e.g., an ACK/NACK message).
A29. The method of example A28, wherein the DCI is a scheduling DCI.
A30. The method of example A28, wherein the DCI is a non-scheduling DCI.
A31. The method of any one of examples Al -A30, switching from the first CSI-RS configuration to the second CSI-RS configuration comprises switching from the first CSI-RS configuration to the second CSI-RS configuration without delay after the DCI including the indication to transition to the second CSI-RS configuration is received.
A32. The method of any one of examples A1-A30, switching from the first CSI-RS configuration to the second CSI-RS configuration comprises switching from the first CSI-RS configuration to the second CSI-RS configuration after a delay following receiving the DCI including the indication to transition to the second CSI-RS configuration. A33. The method of any one of examples A1-A30, switching from the first CSI-RS configuration to the second CSI-RS configuration comprises switching from the first CSI-RS configuration to the second CSI-RS configuration at a quantized timing.
A34. The method of example A33, wherein the quantized timing is a slot having a slot number (slot no), wherein slot no mod M equals zero (i.e., slot no mod M = 0).
A35. The method of example A33, wherein the quantized timing is a first symbol of a first slot after a delay following receiving the DCI including the indication to transition to the second CSI- RS configuration.
A36. The method of any one of examples A32-A35, wherein the delay and/or the quantized timing is configured by higher layers (e.g., radio resource control (RRC) signaling).
A37. The method of any one of examples A32-A35, wherein the DCI includes a timing of CSI- RS configuration transition bit field that indicates the delay and/or the quantized timing.
Bl. A user equipment (UE) (102) configured with at least a first channel state information (CSI)-reference signal (RS) configuration and a second CSI-RS configuration and adapted to: receive downlink control information (DCI) including an indication to transition to the second CSI-RS configuration; and if the DCI including the indication to transition to the second CSI-RS configuration is received, switch from the first CSI-RS configuration to the second CSI-RS configuration.
Cl . A method (500) performed by a network node (104), the method comprising: transmitting downlink control information (DCI) to a user equipment (UE) (102) configured with at least a first channel state information (CSI)-reference signal (RS) configuration and a second CSI-RS configuration, wherein the DCI includes an indication to transition to the second CSI-RS configuration; and transmitting one or more CSI-RSs to the UE.
C2. The method of example Cl, further comprising receiving a measurement report conveyed by the UE, the measurement report being based on the second CSI-RS configuration.
C3. The method of example Cl or C2, wherein:
(a) the first CSI-RS configuration includes a configuration (e.g., value) for a parameter in a CSI-RS resource, and the second CSI-RS configuration includes a different configuration for the parameter in the CSI-RS resource; (b) the first CSI-RS configuration includes a CSI-RS resource, and the second CSI-RS configuration includes a different CSI-RS resource; and/or
(c) the first CSI-RS configuration includes a CSI-RS resource set, and the second CSI-RS configuration includes a different CSI-RS resource set.
C4. The method of any one of examples C1-C3, wherein the first CSI-RS configuration is a default CSI-RS configuration, and the second CSI-RS configuration is a non-default CSI-RS configuration.
C5. The method of any one of examples C1-C4, wherein the DCI includes a CSI-RS configuration bit field, and a status of one or more bits of the CSI-RS configuration bit field provides the indication to transition to the second CSI-RS configuration.
C6. The method of example C5, wherein the CSI-RS configuration bit field in the DCI comprises only one bit.
C7. The method of example C5, wherein the UE is further configured with at least third and fourth CSI-RS configurations, and the CSI-RS configuration bit field in the DCI comprises at least two bits.
C8a. The method of any one of examples C5-C7, wherein the CSI-RS configuration bit field in the DCI comprises X bits, the UE is configured with Y or fewer CSI-RS configuration, X is greater than or equal to 1, and X = log2 Y.
C8b. The method of any one of examples C5-C7, wherein the CSI-RS configuration bit field in the DCI comprises X bits, the UE is configured with Y or fewer CSI-RS configuration, X is greater than or equal to 1, and X = log2 (Y-l).
C9. The method of any one of examples C5-C8b, wherein the number of bits in CSI-RS configuration bit field is configured by higher layer signaling (e.g., radio resource control (RRC) signaling).
CIO. The method of any one of examples C5-C9, wherein a start of the CSI-RS configuration bit field is configured by higher layer signaling (e.g., radio resource control (RRC) signaling). Cl 1. The method of example CIO, wherein the start of the CSI-RS configuration bit field is an explicit location.
C12. The method of example CIO, wherein the start of the CSI-RS configuration bit field is a relative location. C13. The method of any one of examples C5-C12, wherein the CSI-RS configuration bit field is a new bit field in addition to existing DCI bit fields.
C14. The method of any one of examples C5-C12, wherein the CSI-RS configuration bit field reuses an existing DCI bit field.
C15. The method of example C14, wherein the UE interprets the existing DCI bit field as the CSI-RS configuration bit field if a parameter is configured.
C16. The method of example C15, wherein the parameter is an existing parameter (e.g., at least one of nrofPortsB, densityB. powerControlOffsetSS B).
C17. The method of example C15, wherein the parameter is a new parameter (e.g., adaptiveCSI-RS enabled).
C18. The method of example C14, wherein the indication to transition to the second CSI-RS configuration is an invalid index within the existing DCI bit field.
C19. The method of any one of examples C5-C18, wherein the CSI-RS configuration bit field is included in one or more existing DCI formats.
C20. The method of example Cl 9, wherein the one or more existing DCI formats include 0-x uplink formats, 1-x downlink formats, and/or 2-x non-scheduling DCI formats (e.g., a 0-1 uplink format, a 0-2 uplink format, a 1-1 downlink format, a 1-2 downlink format, and/or a 2-6 nonscheduling DCI format).
C21. The method of any one of examples C1-C20, wherein the DCI is scrambled by a group Radio Network Temporary Identifier (RNTI).
C22. The method of any one of examples C1-C21, further comprising transmitting an indication for the UE to transition to the first CSI-RS configuration.
C23. The method of example C22, wherein the indication to transition to the first CSI-RS configuration is transmitted via DCI.
C24. The method of example C22, wherein the indication to transition to the first CSI-RS configuration is a command having a higher latency than a DCI command.
C25. The method of example C22 or C24, wherein the indication to transition to the first CSI- RS configuration is transmitted via a medium access control (MAC) control element (CE).
C26. The method of example C22 or C24, wherein the indication to transition to the first CSI- RS configuration is transmitted via a radio resource control (RRC) configuration. C27. The method of any one of examples C22-C26, further comprising receiving a measurement report conveyed by the UE, the measurement report being based on the first CSI- RS configuration.
C28. The method of any one of examples C1-C27, further comprising receiving an acknowledgement message (e.g., an ACK/NACK message) sent by the UE.
C29. The method of example C28, wherein the DCI is a scheduling DCI.
C30. The method of example C28, wherein the DCI is a non-scheduling DCI.
C31. The method of any one of examples C1-C27, further comprising: determining that an acknowledgement message has not been received; and re-transmitting DCI including the indication to transition to the second CSI-RS configuration.
C32. The method of any one of examples C1-C31, wherein the DCI includes a timing of CSI- RS configuration transition bit field that indicates a delay and/or a quantized timing for the UE to switch to the second CSI-RS configuration.
C33. The method of example C32, wherein the quantized timing is a slot having a slot number (slot no), wherein slot no mod M equals zero (i.e., slot no mod M = 0).
C34. The method of example C32, wherein the quantized timing is a first symbol of a first slot after the delay following the UE receiving the DCI including the indication to transition to the second CSI-RS configuration.
C35. The method of any one of examples C1-C34, further comprising transmitting the first and second CSI-RS configurations to the UE.
DI. A network node ( 104) adapted to : transmit downlink control information (DCI) to a user equipment (UE) (102) configured with at least a first channel state information (CSI)-reference signal (RS) configuration and a second CSI-RS configuration, wherein the DCI includes an indication to transition to the second CSI-RS configuration; and transmit one or more CSI-RSs to the UE.
El . A computer program comprising instructions for adapting an apparatus to perform the method of any one of examples A1-A37 and C1-C35.
Fl . A carrier containing the computer program of example El, wherein the carrier is one of an electronic signal, optical signal, radio signal, or compute readable storage medium. Gl. An apparatus (102 or 104), the apparatus comprising: processing circuitry (202 or 302); and a memory (242 or 342), said memory containing instructions (244 or 344) executable by said processing circuitry, whereby said apparatus is operative to perform the method of any one of the examples A1-A37 and C1-C35.
Hl. An apparatus (102 or 104) adapted to perform the method of any one of examples Al- A37 and C1-C35.
Il . Any combination of the examples set forth above.
[00102] While various examples are described herein, it should be understood that they have been presented by way of example only, and not limitation. Thus, the breadth and scope of this disclosure should not be limited by any of the above-described exemplary examples. Moreover, any combination of the above-described elements in all possible variations thereof is encompassed by the disclosure unless otherwise indicated herein or otherwise clearly contradicted by context.
[00103] Additionally, while the processes described above and illustrated in the drawings are shown as a sequence of steps, this was done solely for the sake of illustration. Accordingly, it is contemplated that some steps may be added, some steps may be omitted, the order of the steps may be re-arranged, and some steps may be performed in parallel.

Claims

1. A method (400) performed by a user equipment, UE, (102) configured with at least a first channel state information-reference signal, CSI-RS, configuration and a second CSI-RS configuration, the method comprising: receiving downlink control information, DCI, including an indication to transition to the second CSI-RS configuration; and if the DCI including the indication to transition to the second CSI-RS configuration is received, switching from the first CSI-RS configuration to the second CSI-RS configuration.
2. The method of claim 1, wherein the DCI includes a CSI-RS configuration bit field, and a status of one or more bits of the CSI-RS configuration bit field provides the indication to transition to the second CSI-RS configuration.
3. The method of claim 2, wherein the UE is further configured with at least a third and fourth CSI-RS configuration, and the CSI-RS configuration bit field in the DCI comprises at least two bits.
4. The method of any one of claims 2-3, wherein the CSI-RS configuration bit field in the DCI comprises X bits, and the UE is configured with Y or fewer CSI-RS configuration, wherein X is greater than or equal to 1, and X = log2 Y.
5. The method of any one of claims 2-4, wherein the number of bits in CSI-RS configuration bit field is configured by higher layer signaling.
6. The method of any one of claims 2-5, wherein a start of the CSI-RS configuration bit field is configured by higher layer signaling.
7. The method of claim 6, wherein the start of the CSI-RS configuration bit field is an explicit location or a relative location.
36
8. The method of any of claims 2-7, wherein the UE interprets an existing DCI bit field as the CSI-RS configuration bit field if a parameter is configured.
9. The method of claim any of claims 2-7, wherein the indication to transition to the second CSI-RS configuration is an invalid index within an existing DCI bit field.
10. The method of any one of claims 2-9, wherein the CSI-RS configuration bit field is included in one or more DCI formats, wherein the one or more DCI formats include 0-x uplink formats, 1-x downlink formats, and/or 2-x non-scheduling DCI formats.
11. The method of any one of claims 1-10, wherein the DCI is scrambled by a group Radio Network Temporary Identifier, RNTI.
12. The method of any one of claims 1-11, further comprising: receiving an indication to transition to the first CSI-RS configuration; and if the indication to transition to the first CSI-RS configuration is received, switching from the second CSI-RS configuration to the first CSI-RS configuration.
13. The method of claim 12, wherein the indication to transition to the first CSI-RS configuration is received via DCI.
14. The method of claim 13, wherein the indication to transition to the first CSI-RS configuration is a command having a higher latency than a DCI command.
15. The method of any one of claims 1-14, wherein switching from the first CSI-RS configuration to the second CSI-RS configuration comprises switching from the first CSI-RS configuration to the second CSI-RS configuration without a configured delay after the DCI including the indication to transition to the second CSI-RS configuration is received.
16. The method of any one of claims 1-14, wherein switching from the first CSI-RS configuration to the second CSI-RS configuration comprises switching from the first CSI-RS
37 configuration to the second CSI-RS configuration after a configured delay following receiving the DCI including the indication to transition to the second CSI-RS configuration.
17. The method of any one of claims 1-16, wherein the first CSI-RS configuration is a default CSI-RS configuration, and the second CSI-RS configuration is a non-default CSI-RS configuration.
18. The method of any one of claims 1-17, further comprising performing CSI-RS measurements and/or reporting based on the second CSI-RS configuration.
19. A user equipment, UE, (102) configured with at least a first channel state informationreference signal, CSI-RS configuration and a second CSI-RS configuration and adapted to: receive downlink control information, DCI, including an indication to transition to the second CSI-RS configuration; and if the DCI including the indication to transition to the second CSI-RS configuration is received, switch from the first CSI-RS configuration to the second CSI-RS configuration.
20. The UE of claim 19, wherein the UE is further adapted to perform the method of any one of claims 2-18.
21. A method (500) performed by a network node (104), the method comprising: transmitting downlink control information, DCI, to a user equipment, UE, (102) configured with at least a first channel state information-reference signal, CSI-RS, configuration and a second CSI-RS configuration, wherein the DCI includes an indication to transition to the second CSI-RS configuration; and transmitting one or more CSI-RSs to the UE.
22. The method of claim 21, wherein the DCI includes a CSI-RS configuration bit field, and a status of one or more bits of the CSI-RS configuration bit field provides the indication to transition to the second CSI-RS configuration.
23. The method of claim 22, wherein the UE is further configured with at least a third and fourth CSI-RS configuration, and the CSI-RS configuration bit field in the DCI comprises at least two bits.
24. The method of any one of claims 22-23, wherein the CSI-RS configuration bit field in the DCI comprises X bits, and the UE is configured with Y or fewer CSI-RS configuration, wherein X is greater than or equal to 1, and X = log2 Y.
25. The method of any one of claims 22-24, wherein the number of bits in CSI-RS configuration bit field is configured by higher layer signaling.
26. The method of any one of claims 22-25, wherein a start of the CSI-RS configuration bit field is configured by higher layer signaling.
27. The method of claim 26, wherein the start of the CSI-RS configuration bit field is an explicit location or a relative location.
28. The method of any one of claims 22-27, wherein the UE interprets an existing DCI bit field as the CSI-RS configuration bit field if a parameter is configured.
29. The method of any one of claims 22-27, wherein the indication to transition to the second CSI-RS configuration is an invalid index within an existing DCI bit field.
30. The method of any one of claims 22-29, wherein the CSI-RS configuration bit field is included in one or more DCI formats, wherein the one or more existing DCI formats include 0-x uplink formats, 1-x downlink formats, and/or 2-x non-scheduling DCI formats.
31. The method of any one of claims 21-30, wherein the DCI is scrambled by a group Radio Network Temporary Identifier, RNTI.
32. The method of any one of claims 21-31, further comprising transmitting an indication for the UE to transition to the first CSI-RS configuration.
33. The method of claim 32, wherein the indication to transition to the first CSI-RS configuration is transmitted via DCI.
34. The method of claim 32, wherein the indication to transition to the first CSI-RS configuration is a command having a higher latency than a DCI command.
35. The method of any one of claims 21-34, wherein the DCI includes a timing of CSI-RS configuration transition bit field that indicates a delay for the UE to switch to the second CSI-RS configuration.
36. The method of any one of claims 21-35, further comprising transmitting the first and second CSI-RS configurations to the UE.
37. The method of any one of claims 21-36, further comprising receiving a measurement report conveyed by the UE, the measurement report being based on the second CSI-RS configuration.
38. The method of any one of claims 21-37, wherein the first CSI-RS configuration is a default CSI-RS configuration, and the second CSI-RS configuration is a non-default CSI-RS configuration.
39. A network node (104) adapted to : transmit downlink control information, DCI, to a user equipment, UE, (102) configured with at least a first channel state information-reference signal, CSI-RS, configuration and a second CSI-RS configuration, wherein the DCI includes an indication to transition to the second CSI-RS configuration; and transmit one or more CSI-RSs to the UE.
40. The network node of claim 39, wherein the network node is further adapted to perform the method of any of claims 22-38.
41. A computer program comprising instructions for adapting an apparatus to perform the method of any one of claims 1-20 and 21-38.
41
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