Method, apparatus and computer program for a communication network

Abstract

There is provided a method performed by a user equipment, UE, the method comprising receiving, from a network entity, channel state information-reference signals, CSI-RS, and determining, based on the CSI-RS, a first value of a parameter associated with CSI. The method further comprises selecting, based on the first value of the parameter associated with CSI, a first configuration related to at least one reference signal, RS, for demodulating at least one physical channel from a plurality of configurations related to at least one RS for demodulating at least one physical channel, wherein each of the plurality configurations is associated with information that is related to the parameter associated with CSI, and transmitting, the network entity, a CSI report comprising an indication of the first configuration.

Description

METHOD, APPARATUS AND COMPUTER PROGRAM FOR A COMMUNICATION NETWORKTECHNICAL FIELD

[0001] Various examples of this disclosure relate to methods, apparatuses, and computer programs. In particular, methods, apparatuses, and computer programs for a communication network.BACKGROUND

[0002] A communication network can be seen as a facility that enables communications between two or more communication devices, or provides communication devices access to a data network. A mobile or wireless communication network is one example of a communication network. A communication device may be provided with a service by an application server.

[0003] Such communication networks operate in accordance with standards such as those provided by 3GPP (Third Generation Partnership Project) or ETSI (European Telecommunications Standards Institute). Examples of standards are the so-called 5G (5th Generation) standards provided by 3GPP.SUMMARY

[0004] Some examples of this disclosure will be described with respect to certain aspects. These aspects are not intended to indicate key or essential features of the embodiments of this disclosure, nor are they intended to be used to limit the scope thereof. Other features, aspects, and elements will be readily apparent to a person skilled in the art in view of this disclosure. For example, it should be appreciated that further aspects may be provided by the combination of any two or more of the various aspects described below.

[0005] According to a first aspect, there is provided a method performed by a user equipment, UE, the method comprising: receiving, from a network entity, channel state information-reference signals, CSI-RS; determining, based on the CSI-RS, a first value of a parameter associated with CSI; selecting, based on the first value of the parameter associated with CSI, a first configuration related to at least one reference signal, RS, for demodulating at least one physical channel from a plurality of configurations related to at least one RS for demodulating at least one physical channel, wherein each of the plurality configurations is associated with information that is related to the parameter associated with CSI; and transmitting, the network entity, a CSI report comprising an indication of the first configuration.

[0006] According to a second aspect, there is provided a user equipment comprising means for: receiving, from a network entity, channel state information-reference signals, CSI-RS; determining, based on the CSI-RS, a first value of a parameter associated with CSI; selecting, based on the first value of the parameter associated with CSI, a first configuration related to at least one reference signal, RS, for demodulating at least one physical channel from a plurality ofconfigurations related to at least one RS for demodulating at least one physical channel, wherein each of the plurality configurations is associated with information that is related to the parameter associated with CSI; and transmitting, the network entity, a CSI report comprising an indication of the first configuration.

[0007] According to a third aspect, there is provided a user equipment comprising: at least one processor, and at least one memory storing instructions that, when executed by the at least one processor, cause the user equipment to perform: receiving, from a network entity, channel state information-reference signals, CSI-RS; determining, based on the CSI-RS, a first value of a parameter associated with CSI; selecting, based on the first value of the parameter associated with CSI, a first configuration related to at least one reference signal, RS, for demodulating at least one physical channel from a plurality of configurations related to at least one RS for demodulating at least one physical channel, wherein each of the plurality configurations is associated with information that is related to the parameter associated with CSI; and transmitting, the network entity, a CSI report comprising an indication of the first configuration.

[0008] According to a fourth aspect, there is provided a user equipment comprising: circuitry configured to perform: receiving, from a network entity, channel state information-reference signals, CSI-RS; determining, based on the CSI-RS, a first value of a parameter associated with CSI; selecting, based on the first value of the parameter associated with CSI, a first configuration related to at least one reference signal, RS, for demodulating at least one physical channel from a plurality of configurations related to at least one RS for demodulating at least one physical channel, wherein each of the plurality configurations is associated with information that is related to the parameter associated with CSI; and transmitting, the network entity, a CSI report comprising an indication of the first configuration.

[0009] According to a fifth aspect, there is provided a computer program comprising instructions, which when executed by a user equipment, cause the user equipment to perform: receiving, from a network entity, channel state information-reference signals, CSI-RS; determining, based on the CSI-RS, a first value of a parameter associated with CSI; selecting, based on the first value of the parameter associated with CSI, a first configuration related to at least one reference signal, RS, for demodulating at least one physical channel from a plurality of configurations related to at least one RS for demodulating at least one physical channel, wherein each of the plurality configurations is associated with information that is related to the parameter associated with CSI; and transmitting, the network entity, a CSI report comprising an indication of the first configuration.

[0010] The following are applicable to each (e.g., one or more, including all) of the above first to fifth aspects.

[0011] In some examples, the first configuration related to at least one RS is for the UE to receive and process at least one RS transmitted by the network entity to the UE in at least one physical channel.

[0012] In some examples, the parameter associated with CSI comprises one of: a signal to noise ratio, a signal to noise plus interference ratio, a channel quality indicator, or a modulation and coding scheme.

[0013] In some examples, the user equipment is further caused to perform: receiving, from the network entity, a configuration for CSI, wherein the configuration for CSI indicates that the UE is to report at least one RS configuration.

[0014] In some examples, the configuration for CSI indicates that the UE is to report at least two configurations related to at least one RS, each of the at least two configurations being associated with different types of RS.

[0015] In some examples, the user equipment is further caused to perform: receiving, from the network entity, at least one criterion for selection of the RS configuration, wherein the selecting of the first configuration is further based on the at least one criterion for selection.

[0016] In some examples, the user equipment is further caused to perform: receiving, from the network entity, an indication of the plurality of configurations, wherein each configuration of the plurality of configurations is associated with the information that is related to the parameter associated with CSI.

[0017] In some examples, each of the plurality of configurations is associated with an index, wherein the indication of the first configuration comprised in the CSI report comprises an index of the first configuration.

[0018] In some examples, for each of the configurations, the information that is related to the parameter associated with CSI comprises a mapping between a throughput and a signal to noise ratio.

[0019] In some examples, for each of the configurations, the information that is related to the parameter associated with CSI comprises a mapping between a throughput and a signal to noise ratio for each of a plurality of different modulation and coding schemes.

[0020] In some examples, the at least one criterion for selection indicates that the throughput is to be utilised by the UE when selecting the configuration related to at least one RS.

[0021] In some examples, the user equipment is further caused to perform: receiving, from the network entity, a second indication of a second configuration of the plurality of configurations; and demodulating a physical channel transmission from the network entity based on the second configuration.

[0022] In some examples, the first configuration and the second configuration are the same. In some examples, the first configuration and the second configuration are different configurations.

[0023] In some examples, the second indication is received in scheduling downlink control information; or the second indication comprises an indication of a first transmission configuration indication, TCI, state from a plurality of TCI states to be utilised for receiving the physical channel transmission from the network entity, wherein each of the plurality of TCI states is associated withone of the plurality of configurations related to at least one RS, wherein the first TCI state is associated with the second configuration.

[0024] In some examples, at least one of the plurality of RS configurations comprises at least two different types of RS.

[0025] In some examples, one of the types of RS comprises one of: a demodulation reference signal, DMRS, a phase tracking reference signal, PTRS, a front loaded DMRS, a reference signal associated with DMRS, or a reference signal associated with PTRS.

[0026] According to a sixth aspect, there is provided a method performed by a network entity, the method comprising: transmitting, to a user equipment, UE, channel state information-reference signals, CSI-RS; receiving, from the UE, a CSI report comprising an indication of a first configuration related to at least one reference signal, RSs, for demodulating at least one physical channel from among a plurality of configurations related to at least one RS for demodulating at least one physical channel; and based on the indication of the first configuration, selecting a second configuration from the plurality of configurations, for the UE to utilise to demodulate a physical channel transmission from the network entity to the UE.

[0027] According to a seventh aspect, there is provided a network entity comprising means for: transmitting, to a user equipment, UE, channel state information-reference signals, CSI-RS; receiving, from the UE, a CSI report comprising an indication of a first configuration related to at least one reference signal, RSs, for demodulating at least one physical channel from among a plurality of configurations related to at least one RS for demodulating at least one physical channel; and based on the indication of the first configuration, selecting a second configuration from the plurality of configurations, for the UE to utilise to demodulate a physical channel transmission from the network entity to the UE.

[0028] According to an eighth aspect, there is provided a network entity comprising: at least one processor, and at least one memory storing instructions that, when executed by the at least one processor, cause the network entity to perform: transmitting, to a user equipment, UE, channel state information-reference signals, CSI-RS; receiving, from the UE, a CSI report comprising an indication of a first configuration related to at least one reference signal, RSs, for demodulating at least one physical channel from among a plurality of configurations related to at least one RS for demodulating at least one physical channel; and based on the indication of the first configuration, selecting a second configuration from the plurality of configurations, for the UE to utilise to demodulate a physical channel transmission from the network entity to the UE.

[0029] According to a ninth aspect, there is provided a network entity comprising: circuitry configured to perform: transmitting, to a user equipment, UE, channel state information-reference signals, CSI-RS; receiving, from the UE, a CSI report comprising an indication of a first configuration related to at least one reference signal, RSs, for demodulating at least one physical channel from among a plurality of configurations related to at least one RS for demodulating atleast one physical channel; and based on the indication of the first configuration, selecting a second configuration from the plurality of configurations, for the UE to utilise to demodulate a physical channel transmission from the network entity to the UE.

[0030] According to a tenth aspect, there is provided a computer program comprising instructions, which when executed by a network entity, cause the network entity to perform: transmitting, to a user equipment, UE, channel state information-reference signals, CSI-RS; receiving, from the UE, a CSI report comprising an indication of a first configuration related to at least one reference signal, RSs, for demodulating at least one physical channel from among a plurality of configurations related to at least one RS for demodulating at least one physical channel; and based on the indication of the first configuration, selecting a second configuration from the plurality of configurations, for the UE to utilise to demodulate a physical channel transmission from the network entity to the UE.

[0031] The following are applicable to each (e.g., one or more, including all) of the above sixth to tenth aspects.

[0032] In some examples, the network entity is further caused to perform: transmitting, to the UE, a second indication of the second configuration of the plurality of configurations, to be utilised by the UE for demodulating a downlink physical channel transmission.

[0033] In some examples, the first configuration and the second configuration are the same. In some examples, the first configuration and the second configuration are different configurations.

[0034] In some examples, the second indication is transmitted in scheduling downlink control information; or the second indication comprises an indication of a first transmission configuration indication, TCI, state from a plurality of TCI states to be utilised for receiving the physical layer channel transmission from the network entity, wherein each of the plurality of TCI states is associated with one of the plurality of configurations related to at least one RS, wherein the first TCI state is associated with the second configuration.

[0035] In some examples, the network entity is further caused to perform: transmitting, to the UE, a configuration for CSI, wherein the configuration for CSI indicates that the UE is to report at least one RS configuration.

[0036] In some examples, the configuration for CSI indicates that the UE is to report at least two configurations related to at least one RS, each of the at least two configurations being associated with different types of RS.

[0037] In some examples, the network entity is further caused to perform: transmitting, to the UE, at least one criterion for selection of the RS configuration.

[0038] In some examples, the at least one criterion for selection indicates that throughput is to be utilised by the UE when selecting the configuration related to at least one RS.

[0039] In some examples, the network entity is further caused to perform: transmitting, to the UE, an indication of the plurality of configurations, wherein each configuration of the plurality ofconfigurations is associated with the information that is related to the parameter associated with CSI.

[0040] In some examples, each of the plurality of configurations is associated with an index, wherein the indication of the first configuration comprised in the CSI report comprises an index of the first configuration.

[0041] In some examples, at least one of the plurality of RS configurations comprises at least two different types of RS.

[0042] In some examples, one of the types of RS comprises one of: a demodulation reference signal, DMRS, a phase tracking reference signal, PTRS, a front loaded DMRS, a reference signal associated with DMRS, or a reference signal associated with PTRS.

[0043] In some examples, the selecting of the second configuration is further based on at least one of the following: a traffic load, or at least one service requirement.

[0044] According to an eleventh aspect, there is provided a method performed by a user equipment, UE, the method comprising: receiving, from a network entity, at least one channel state information-reference signal, CSI-RS; determining a first value of a signal to noise ratio, SNR, based on the CSI-RS; obtaining estimated values of a first metric at each of a plurality of different SNR values for each of a plurality of configurations, each of the plurality of configurations being related to at least one RS for demodulating at least one physical channel; based on the first value of the SNR, selecting a first configuration from the plurality of configurations, wherein the selecting comprises comparing the first value of the SNR with the estimated values of the first metric at each of the plurality of different SNR values that are associated with each of the plurality of configurations; and transmitting, the network entity, a CSI report comprising an indication of the first configuration.

[0045] According to a twelfth aspect, there is provided a user equipment comprising means for: receiving, from a network entity, at least one channel state information-reference signal, CSI-RS; determining a first value of a signal to noise ratio, SNR, based on the CSI-RS; obtaining estimated values of a first metric at each of a plurality of different SNR values for each of a plurality of configurations, each of the plurality of configurations being related to at least one RS for demodulating at least one physical channel; based on the first value of the SNR, selecting a first configuration from the plurality of configurations, wherein the selecting comprises comparing the first value of the SNR with the estimated values of the first metric at each of the plurality of different SNR values that are associated with each of the plurality of configurations; and transmitting, the network entity, a CSI report comprising an indication of the first configuration.

[0046] According to a thirteenth aspect, there is provided a user equipment comprising: at least one processor, and at least one memory storing instructions that, when executed by the at least one processor, cause the user equipment to perform: receiving, from a network entity, at least one channel state information-reference signal, CSI-RS; determining a first value of a signal tonoise ratio, SNR, based on the CSI-RS; obtaining estimated values of a first metric at each of a plurality of different SNR values for each of a plurality of configurations, each of the plurality of configurations being related to at least one RS for demodulating at least one physical channel; based on the first value of the SNR, selecting a first configuration from the plurality of configurations, wherein the selecting comprises comparing the first value of the SNR with the estimated values of the first metric at each of the plurality of different SNR values that are associated with each of the plurality of configurations; and transmitting, the network entity, a CSI report comprising an indication of the first configuration.

[0047] According to a fourteenth aspect, there is provided a user equipment comprising: circuitry configured to perform: receiving, from a network entity, at least one channel state informationreference signal, CSI-RS; determining a first value of a signal to noise ratio, SNR, based on the CSI-RS; obtaining estimated values of a first metric at each of a plurality of different SNR values for each of a plurality of configurations, each of the plurality of configurations being related to at least one RS for demodulating at least one physical channel; based on the first value of the SNR, selecting a first configuration from the plurality of configurations, wherein the selecting comprises comparing the first value of the SNR with the estimated values of the first metric at each of the plurality of different SNR values that are associated with each of the plurality of configurations; and transmitting, the network entity, a CSI report comprising an indication of the first configuration.

[0048] According to a fifteenth aspect, there is provided a computer program comprising instructions, which when executed by a user equipment, cause the user equipment to perform: receiving, from a network entity, at least one channel state information-reference signal, CSI-RS; determining a first value of a signal to noise ratio, SNR, based on the CSI-RS; obtaining estimated values of a first metric at each of a plurality of different SNR values for each of a plurality of configurations, each of the plurality of configurations being related to at least one RS for demodulating at least one physical channel; based on the first value of the SNR, selecting a first configuration from the plurality of configurations, wherein the selecting comprises comparing the first value of the SNR with the estimated values of the first metric at each of the plurality of different SNR values that are associated with each of the plurality of configurations; and transmitting, the network entity, a CSI report comprising an indication of the first configuration.

[0049] The following are applicable to each (e.g., one or more, including all) of the above eleventh to fifteenth aspects.

[0050] In some examples, the selecting of the first configuration from the plurality of configurations is based on determining an optimum performance indicated by the estimated value of the first metric at the first value of SNR.

[0051] In some examples, the first metric is throughput, and wherein the selecting of the first configuration from the plurality of configurations is based on determining, from each of the pluralityof configuration, which configuration has an estimated value of the throughput, for the first value of the SNR, that is the highest.

[0052] In some examples, the first metric is throughput, and wherein the first configuration has an estimated value of throughput at the first value of SNR that is highest, compared to the other configurations of the plurality of configurations.

[0053] In some examples, the determining of the first value of the SNR comprises: performing a channel estimation of a radio channel between the UE and the network entity based on the CSI-RS, such that the first value of the SNR is determined based on the channel estimation.

[0054] In some examples, the SNR associated with the first value is an effective SNR, wherein the effective SNR is based on: an SNR for the radio channel between the UE and the network entity, and an SNR for a receiver filter of the UE.

[0055] In some examples, the obtaining of the estimate values comprises one of: determining the estimated values of the first metric at each of the plurality of different SNR values for each of the plurality of configurations based on: mapping tables accessible to the UE, and predefined parameters; or determining the estimated values of the first metric at each of the plurality of different SNR values for each of the plurality of configurations based on a fitting function.

[0056] In some examples, the fitting function is one of: a second order, or a higher order, polynomial fitting.

[0057] In some examples, the fitting function is implemented in a linear way, or polynomial way.

[0058] In some examples, wherein the predefined parameters comprise at least one of the following: carrier frequency range, frequency band, sub-carrier spacing, numerology value, rank, number of layers value for downlink physical channel, modulation and coding scheme, Doppler frequency, spread, time correlation of value of a channel, or allocation bandwidth.

[0059] In some examples, the first configuration related to at least one RS is for the UE to receive and process at least one RS transmitted by the network entity to the UE in at least one physical channel.

[0060] In some examples, the user equipment is further caused to perform: receiving, from the network entity, a configuration for CSI, wherein the configuration for CSI indicates that the UE is to report at least one RS configuration.

[0061] In some examples, the configuration for CSI indicates that the UE is to report at least two configurations related to at least one RS, each of the at least two configurations being associated with different types of RS.

[0062] In some examples, the user equipment is further caused to perform: receiving, from the network entity, at least one criterion for selection of the RS configuration, wherein the selecting of the first configuration is further based on the at least one criterion for selection.

[0063] In some examples, the user equipment is further caused to perform: receiving, from the network entity, an indication of the plurality of configurations, wherein each configuration of theplurality of configurations is associated with the information that is related to the parameter associated with CSI.

[0064] In some examples, each of the plurality of configurations is associated with an index, wherein the indication of the first configuration comprised in the CSI report comprises an index of the first configuration.

[0065] In some examples, for each of the configurations, the information that is related to the parameter associated with CSI comprises a mapping between a throughput and a signal to noise ratio.

[0066] In some examples, for each of the configurations, the information that is related to the parameter associated with CSI comprises a mapping between a throughput and a signal to noise ratio for each of a plurality of different modulation and coding schemes.

[0067] In some examples, the at least one criterion for selection indicates that the throughput is to be utilised by the UE when selecting the configuration related to at least one RS.

[0068] In some examples, the user equipment is further caused to perform: receiving, from the network entity, a second indication of a second configuration of the plurality of configurations; and demodulating a physical channel transmission from the network entity based on the second configuration.

[0069] In some examples, the first configuration and the second configuration are the same. In some examples, the first configuration and the second configuration are different configurations.

[0070] In some examples, one of: the second indication is received in scheduling downlink control information; or the second indication comprises an indication of a first transmission configuration indication, TCI, state from a plurality of TCI states to be utilised for receiving the physical channel transmission from the network entity, wherein each of the plurality of TCI states is associated with one of the plurality of configurations related to at least one RS, wherein the first TCI state is associated with the second configuration.

[0071] In some examples, at least one of the plurality of RS configurations comprises at least two different types of RS.

[0072] In some examples, one of the types of RS comprises one of: a demodulation reference signal, DMRS, a phase tracking reference signal, PTRS, a front loaded DMRS, a reference signal associated with DMRS, or a reference signal associated with PTRS.

[0073] A computer product stored on a medium may cause an apparatus to perform the methods as described herein.

[0074] A non-transitory computer readable medium comprising program instructions, that, when executed by an apparatus, cause the apparatus to perform the methods as described herein.

[0075] An electronic device may comprise apparatus as described herein.

[0076] Various other aspects and further embodiments are also described in the following detailed description and in the attached claims.

[0077] According to some aspects, there is provided the subject matter of the independent claims. Some further aspects are defined in the dependent claims. The embodiments that do not fall under the scope of the claims are to be interpreted as examples useful for understanding the disclosure.

[0078] List of Abbreviations:AN: Access NetworkBS: Base StationON: Core NetworkDL: DownlinkDMRS: Demodulation reference signaleNB: eNodeBFL: Front loadedgNB: gNodeBLTE: Long Term EvolutionNG-RAN: Next Generation Radio Access NetworkNF: Network FunctionNR: New RadioNW: NetworkOFDM: Orthogonal frequency division multiplexPLMN: Public Land Mobile NetworkPTRS: Phase tracking reference signalPUSCH: Physical uplink shared channelRAN: Radio Access NetworkRE: Resource elementRF: Radio FrequencyRS: Reference signalUE: User EquipmentUL: Uplink3GPP: 3rdGeneration Partnership Project5G: 5thGeneration5GC: 5G Core network5G-AN: 5G Radio Access Network5GS: 5G SystemBRIEF DESCRIPTION OF DRAWINGS

[0079] Some examples will now be described, by way of illustrative and non-limiting example only, with reference to the accompanying drawings in which:

[0080] FIG. 1 shows a schematic representation of a 5G communication system;

[0081] FIG. 2 shows a schematic representation of an apparatus for the 5G communication system of FIG. 1;

[0082] FIG. 3 shows a schematic representation of a communication device;

[0083] FIG. 4 shows a schematic representation of channel state information acquisition and channel state information reporting in a 5G communication system;

[0084] FIG. 5 shows an example signalling diagram between a user equipment and a base station for channel state information acquisition and channel state information reporting;

[0085] FIG. 6 shows an example method flow performed by a user equipment for channel state information acquisition and channel state information reporting;

[0086] FIG. 7 shows another example method flow performed by a user equipment for channel state information acquisition and channel state information reporting;

[0087] FIG. 8 shows an example graphical representation of information related to channel state information parameters for a first reference signal configuration;

[0088] FIG. 9 shows an example graphical representation of information related to channel state information parameters for a second reference signal configuration;

[0089] FIG. 10 shows an example graphical representation of information related to channel state information parameters for a third reference signal configuration;

[0090] FIG. 11 shows an example method flow diagram performed by an apparatus;

[0091] FIG. 12 shows another example method flow diagram performed by an apparatus;

[0092] FIG. 13 shows another example method flow diagram performed by an apparatus; and

[0093] FIG. 14 shows a schematic representation of an apparatus.DETAILED DESCRIPTION

[0094] Reference signals (RSs) play an important role in many communication systems, such as in 4G and 5G systems, and are expected to be equally important in 6G systems. RSs are predefined signals that may occupy specific resource elements (REs) within a time-frequency grid. RSs may be used for a number of different reasons, such as for channel estimation, or for tracking time / frequency. In 5G systems, in order to increase protocol efficiency, and to keep transmissions contained within a slot / beam there are defined a plurality of different types of RSs, including a demodulation reference signal (DMRS), a phase tracking reference signal (PTRS), a sounding reference signal (SRS), and a non-zero power channel state information reference signal (NZP-CSI-RS, or simply ‘CSI-RS’).

[0095] DMRS is used by a receiver for radio channel estimation and for demodulation of an associated physical channel. DMRS design and mapping is specific to each downlink and uplink channel in 5G, such as physical downlink control channel (PDCCH), physical downlink shared channel (PDSCH), physical uplink shared channel (PLISCH), and physical uplink control channel (PLICCH). DMRS is UE-specific and is transmitted on demand. DMRS may be beamformed / precoded and kept within a scheduled resource. Multiple orthogonal DMRS antenna ports can be allocated in frequency and time domains to support multiple input multiple output (MIMO) transmission.

[0096] The phase noise of a transmitter and / or receiver increases as the carrier frequency of a system increases. PTRSs can be utilised, particularly at high frequencies, to minimize the effect of the oscillator phase noise on system performance. One of the problems that phase noise introduces into an orthogonal frequency division multiplex (OFDM) signal appears as a common phase rotation of all the sub-carriers, known as common phase error (CPE). In larger carrier frequencies, sub-carrier specific phase rotation may also be a problem, which is known as intercarrier interference (ICI). However, may be addressed with a selection of larger subcarrier spacing. A PTRS may be used to track the phase of a local oscillator (LO) at the transmitter and / or the receiver. PTRS can be present in uplink (e.g., PLISCH) and / or downlink (e.g., PDSCH) channels subject to a capability of UE. Due to phase noise properties, PTRS may be configured with different physical resource block (PRB) densities in frequency domain, e.g., every 2nd or 4th PRB, and different symbol densities in time domain. PTRS may be associated with one DMRS (antenna) port during transmission.

[0097] Phase noise may be less prevalent at lower carrier frequencies. Typically, the PTRS has been configured to enable estimation and compensation of phase noise introduced by a non-ideal frequency oscillator at the UE and / or gNodeB (gNB) sides, especially, at high carrier frequencies, e.g., FR2. Furthermore, the PTRS may also be configured to estimate and compensate frequency offset introduced by non-ideal oscillators at the UE and / or the gNB sides or Doppler frequency offset generated by the mobility of the UE. The time density of NR PTRS may be configured to appear in in every symbol or every 2nd or every 4th symbol of a slot (e.g., 14 OFDM symbols), subject to a scheduled modulation and coding scheme (MCS) for PUSCH or PDSCH. Regarding to frequency domain density, the NR PTRS may be configured to be in every 2nd or 4th PRB or not all, subject to scheduled PUSCH / PDSCH bandwidth.

[0098] As depicted in FIG. 4, in 5G systems, in order to determine channel state information, a gNodeB (gNB) transmits downlink (DL) RSs such as CSI-RS I NZP-CSI-RS to a UE, for the UE to measure the radio channel and signal to interference plus noise ratio (SINR) I signal to noise ratio (SNR). In some instances, noise variance in a channel is determined for channel estimation, based on received CSI-RS, which is termed SNR. In other instances, CSI-IM is also used. CSI-IM resources are a set of specific resource elements that are reserved for interference measurement. When CSI-IM resources are utilised, then interference is also measured, such that SINR is determined. The UE uses the measurements for CSI acquisition of parameters such as rank index (Rl), a precoding matrix indicator (PMI), and channel quality indicator (CQI). These parameters may be reported back to the gNB as the UE’s recommendation on the number of layers to transmit, precoder, and modulation and coding scheme (MCS) to maximize link capacity. The gNB may use this information to adapt the PDSCH transmission configuration, ensuring that the connection is maintained despite changes in the instantaneous link conditions.

[0099] At S401 of FIG.4, the gNB transmits CSI-RS to the UE. At S402, based on the received CSI-RS, the UE determines values for CSI parameters (i.e., CSI acquisition). At S403, the UE transmits a CSI report to the gNB, wherein the CSI report comprises one or more CSI parameters. At S404, based on the CSI report, the gNB performs link adaptation according to the CSI parameters. At S405, the gNB performs a physical downlink shared channel (PDSCH) transmission to the UE.

[0100] The gNB may request reporting on different combinations of CSI parameters (which are often referred to as ‘CSI reporting quantities’) to the UE. A request is communicated to the UE through higher layer radio resource control (RRC) signalling (CSI-ReportConfig), where one of the most common reporting quantities is “cri-RI-LI-PMI-CQI”. With this reporting quantity the UE is expected to report on CRI (CSI Resource Indicator), Rl, LI (Layer Indicator), PMI and CQI. While there are dependencies between these parameters, the exact implementation to select them may vary for each UE vendor.

[0101] If there are multiple CSI-RS resources, the UE will select, as CRI, the best resource, which is typically based on the received signal strength of all the CSI-RS resources. The UE obtains the channel estimation and SINR levels in that (NZP) CSI-RS resource to select the best number of layers v that maximize link capacity, given by Rl. Based on v , the UE will select the best precoder matrix, indicated by PMI, Pe CWpxv, where Np is the total number of CSI-RS antenna ports and v is the number of layers indicated by Rl. Forthat combination of CRI, Rl and PMI, the UE calculates the SINR level per MIMO layer and chooses one CQI value to maximize capacity throughout the layers for a target block error rate (BLER), such as 0.1 (10%). This information is used to select the column (or layer) in the precoding matrix belonging to the strongest layer of the codeword, indicated by LI (Layer Indicator).

[0102] For CQI calculation, the SINR levels may be, as an example, mapped to tabled CQI index values, associated with a modulation scheme, code rate and efficiency. For example, there are 16 different CQI indexes per CQI table, and there are 4 distinct CQI tables defined in 3GPP TS 38.214 to support different scenarios of channel conditions and system configurations. Each CQI table has a corresponding MCS table and the gNodeB may use the CQI index to choose theappropriate MCS value for a codeword. MCS selection by the gNB is also based on MCS tables, like the CQI selection procedure.

[0103] If the channel conditions are favourable, a higher CQI index will be selected by the UE and fed back by the UE to the gNB. This will likely lead to a higher MCS index being selected for the codeword by the gNB for the PDSCH transmission. Conversely, if the channel conditions deteriorate and the SINR levels drop, the reported CQI index will be lower, and the gNB will opt for a lower MCS index for that codeword. However, the gNB is free to choose an MCS index that differs from the recommended by the UE due to other factors such as traffic load, service requirements or any other aspect that requires optimization in the network.

[0104] As described above, an information element (IE) CSI-ReportConfig is used to configure a periodic or semi-persistent CSI report sent on physical uplink control channel (PUCCH) on the cell in which the CSI-ReportConfig is included, or to configure a semi-persistent or aperiodic report sent on PUSCH triggered by downlink control information DCI received on the cell in which the CSI-ReportConfig is included (3GPP TS 38.214, clause 5.2.1).

[0105] For example, the CSI-ReportConfig information element may comprise (in part):reportQuantity CHOICE {none NULL,cri-RI-PMI-CQI NULL,cri-RI-i1 NULL,cri-RI-i1 -CQI SEQUENCE {pdsch-BundleSizeForCSI ENUMERATED{n2,n4} OPTIONAL - Need Scri-RI-CQI NULL,cri-RSRP NULL,ssb-lndex-RSRP NULL,cri-RI-LI-PMI-CQI NULL

[0106] 3GPP Rel-18 TS 38.214 (sec 5.2.1.4) defines reporting configurations. The UE shall calculate CSI parameters assuming the following dependencies between CSI parameters: LI shall be calculated conditioned on the reported CQI, PMI, Rl and CRI; CQI shall be calculated conditioned on the reported PMI, Rl and CRI; PMI shall be calculated conditioned on the reported Rl and CRI; Rl shall be calculated conditioned on the reported CRI. The reporting configuration for CSI can be aperiodic (using PUSCH), periodic (using PUCCH) or semi-persistent (usingPLICCH, and DCI activated PLISCH). The CSI-RS resources may be periodic, semi-persistent, or aperiodic.

[0107] For a UE that has high mobility in a cell (e.g., on a moving train), compared to another UE with low mobility (e.g., a UE that is not moving), it is often beneficial for the high mobility UE to receive additional RS for the demodulating of downlink signals from the gNB (e.g., receiving a PDSCH transmission from the gNB). Reference signals, such as DMRS, may be utilised by UEs when trying to demodulate the PDSCH. However, the low mobility UE may not require as many RS in order to demodulate the PDSCH. If the same number of RS are transmitted to the high mobility UE and the low mobility UE, then RS overhead may be wasted for the low mobility UE.

[0108] One or more the problems identified above are addressed in one or more of the examples described below.

[0109] In examples, there is provided a method performed by a user equipment, UE. The method comprises receiving, from a network entity, channel state information-reference signals, CSI-RS, and determining, based on the CSI-RS, a first value of a parameter associated with CSI. The method further comprises selecting, based on the first value of the parameter associated with CSI, a first configuration related to at least one reference signal, RS, for demodulating at least one physical channel from a plurality of configurations related to at least one RS for demodulating at least one physical channel, wherein each of the plurality configurations is associated with information that is related to the parameter associated with CSI, and transmitting, the network entity, a CSI report comprising an indication of the first configuration.

[0110] In examples, there is provided a method performed by a user equipment, UE. The method comprises receiving, from a network entity, at least one channel state information-reference signal, CSI-RS, and determining a first value of a signal to noise ratio, SNR, based on the CSI-RS. The method further comprises obtaining estimated values of a first metric at each of a plurality of different SNR values for each of a plurality of configurations, each of the plurality of configurations being related to at least one RS for demodulating at least one physical channel, and based on the first value of the SNR, selecting a first configuration from the plurality of configurations, wherein the selecting comprises comparing the first value of the SNR with the estimated values of the first metric at each of the plurality of different SNR values that are associated with each of the plurality of configurations. The method further comprises transmitting, the network entity, a CSI report comprising an indication of the first configuration.

[0111] These examples will be described in more detail below, alongside FIGS. 4 to 14.

[0112] Before explaining the examples above in greater detail, an example communication device (as shown in FIG. 3) that is capable of acquiring CSI and transmitting CSI reports will be described. The communication device is part of a communication system (as shown in FIG. 1). The communication device is able to communicate with one or more of the entities of thecommunication system (as shown in FIG. 1) via an apparatus (as shown in FIG. 2), which may be (or comprised within) a base station. As described above, a base station and communication device may communicate with each other, such that the communication device is able to provide CSI reports to the network.

[0113] Certain general aspects of the communication system and the communication device are briefly explained with reference to FIGS. 1 to 3 to assist in understanding the technology underlying the described examples.

[0114] FIG. 1 shows a schematic representation of a 5G communication system 100. In this manner, FIG. 1 illustrates an example of a communication network to which examples disclosed herein may be applied. The communication network or a cellular communication network may comprise a network node 110 providing one or more cells, such as cell 100, and a network node 112 providing one or more other cells, such as cell 102. Each cell may be, e.g., a macro cell, a micro cell, femto, or a pico cell, for example. The cell may define a coverage area or a service area of the corresponding access node.

[0115] The network node 110 may provide a user equipment (UE) 120 (one or more UEs) with wireless access to the communication network. The wireless access may comprise downlink (DL) communication from the network node to the UE 120 and uplink (UL) communication from the UE 120 to the network node. Examples of uplink channels comprise physical uplink control channel (PUCCH) for transmitting control information and physical uplink shared channel (PUSCH) for transmitting data towards the network. Examples of downlink channels comprise physical downlink control channel (PDCCH) for transmitting control information and physical downlink shared channel (PDSCH) for transmitting data towards the user equipment.

[0116] There may be a plurality of UEs 120, 122 in the system. Each of them may be served by the same or by different network nodes 110, 112. UE may be configured with dual connectivity (DC), wherein the UE, e.g. UE 120, may be connected to multiple network nodes 110, 112. The UEs 120, 122 may communicate with each other, in case device-to-device (D2D) communication interface is established between them via a so-called sidelink (SL). Such D2D communications may be referred to as machine-to-machine, peer-to-peer (P2P) communications, or vehicle-to-vehicle (V2V), for example.

[0117] In the case of multiple network nodes in the communication network, the network nodes may be connected to each other via an interface. LTE specifications call such an interface as X2 interface. An interface between an LTE node and a 5G node, or between two 5G nodes may be called Xn interface.

[0118] The network nodes 110 and 112 may be further connected via another interface to a core network 116 of the communication network. The LTE specifications specify the core network asan evolved packet core (EPC), and the core network may comprise e.g. a mobility management entity (MME) and a gateway node. The MME may handle mobility of terminal devices in a tracking area encompassing a plurality of cells and handle signalling connections between the terminal devices and the core network. The gateway node may handle data routing in the core network and to / from the terminal devices. The 5G specifications specify the core network as a 5G core (5GC). The 5G core may comprise e.g. an access and mobility management function (AMF) and a user plane function / gateway (UPF) and other functions. The AMF may handle termination of non-access stratum (NAS) signalling, NAS ciphering & integrity protection, registration management, connection management, mobility management, access authentication and authorization, security context management. The UPF node may support packet routing and forwarding, packet inspection and quality of service (QoS) handling, for example.

[0119] FIG. 2 illustrates an example of an apparatus 200. The apparatus 200 may be for the 5G communication system of FIG. 1. The apparatus 200 may be for controlling a function of one or more network entities and / or network functions, such as the entities of the 5G-RAN or the 5GC as illustrated on FIG. 1. The apparatus 200 comprises at least one random access memory (RAM) 211a, at least one read only memory (ROM) 211b, at least one processor 212, 213 and an input / output interface 214. The at least one processor 212, 213 is coupled to the RAM 211a and the ROM 211b. The at least one processor 212, 213 may be configured to execute an appropriate software code 215. The software code 215 may for example allow to perform one or more steps to perform one or more of the present aspects or examples. The software code 215 may be stored in the ROM 211b. The apparatus 200 may be interconnected with another apparatus 200 controlling another entity / function of the 5G-AN or the 5GC. . In some examples, apparatus 200 may be configured to provide one or more functions of the 5G-AN or the 5GC. For example, apparatus 200 may be configured to perform at least some functionality of a particular function of the 5G-AN or the 5GC. For example, apparatus 200 may be configured to operate as a particular function of the 5G-AN or the 5GC. In alternative examples, apparatus 200 may be configured to perform at least some functionality of two or more functions of the 5G-AN and / or the 5GC. For example, apparatus 200 may be configured to operate as two or more functions of the 5G-AN and / or the 5GC. The apparatus 200 may comprise one or more circuits, or circuitry (not shown) which may be configured to perform one or more of the present aspects or examples.

[0120] FIG. 3 illustrates an example of a communication device 300. The communication device 300 may be similar to the communication device 102 illustrated in FIG. 1. The communication device 300 may be provided by any device capable of sending and receiving radio signals. Nonlimiting examples of a communication device 300 are a user equipment, a terminal, a mobile station (MS) or mobile device such as a mobile phone or what is known as a ’smart phone’, a computer provided with a wireless interface card or other wireless interface facility (e.g., USBdongle), a personal data assistant (PDA) or a tablet provided with wireless communication capabilities, a machine-type communications (MTC) device, a Cellular Internet of things (CloT) device, or a terrestrial / maritime / aerial vehicle such as a car, a truck, a boat, an air plane, or a drone, or any combinations of these or the like. The communication device 300 may provide, for example, communication of data for carrying communications. The communications may be one or more of voice, electronic mail (email), text message, multimedia, data, machine data and so on.

[0121] The communication device 300 may receive signals over an air or radio interface 307 via appropriate apparatus for receiving and may transmit signals via appropriate apparatus for transmitting radio signals. In FIG. 3, a transceiver apparatus is designated schematically by block 306. The transceiver apparatus 306 may be provided for example by means of a radio part and associated antenna arrangement. The antenna arrangement may be arranged internally or externally to the mobile device.

[0122] The communication device 300 may be provided with at least one processor 301, at least one memory ROM 302a, at least one RAM 302b and other possible components 303 for use in software and hardware aided execution of tasks it is designed to perform, including control of access to and communications with access systems and other communication devices. The at least one processor 301 is coupled to the RAM 302b and the ROM 302a. The at least one processor 301 may be configured to execute an appropriate software code 308. The software code 308 may for example allow to perform one or more of the present aspects. The software code 308 may be stored in the ROM 302a. The communication device 300 may comprise one or more circuits, or circuitry (not shown) which may be configured to perform one or more of the present aspects or examples.

[0123] The processor, storage and other relevant control apparatus may be provided on an appropriate circuit board and / or in chipsets. This feature is denoted by reference 304. The communication device may optionally have a user interface such as keypad 305, touch sensitive screen or pad, combinations thereof or the like. Optionally one or more of a display, a speaker and a microphone may be provided depending on the type of the device.

[0124] A communication device (e.g., a UE) receives physical channels from a network (e.g., a gNB), wherein the UE demodulates the physical channel based on received RSs within the physical channel. For example, DMRS may be transmitted by the gNB to the UE. The UE is aware of a configuration related to at least one RS (which may be termed an ‘RS configuration’) to be able to receive and process the RSs. In this manner, the UE is able to demodulate the physical channel. Stated differently, the UE utilizes the RS configuration in order to demodulate the physical channel (e.g., PDSCH) transmission from the gNB.

[0125] In order to reduce RS overhead, improving the configurability of RS within physical channels (e.g., PLISCH or PDSCH) by distributing different RS resources in a flexible manner in both frequency and time may achieve said reduction in overhead. For example, this may achieve a reduced overhead with respect to NR DM RS configurations. In the DL, when transmitting a PDSCH, an RS configuration is utilized by the gNB. The configuration related to RSs is known by the UE, to allow the UE to receive the PDSCH. Based on the RS configuration, a PDSCH is configured with at least one type of RS. There are a number of different types of RS, and configuration of RS, that may be utilized for this demodulation.

[0126] For example, an antenna port for a first type of RS is configured with a pattern for REs (herein referred to as an ‘RE pattern’). For the RE pattern, at least one RE is associated with a resource block (RB) (or physical RB (PRB)) of resources within the physical channel. A number of RBs associated with the RE pattern across an allocation for the physical channel is configurable (e.g., such that a density between RBs may be flexibly reduced), e.g., every 2nd PRB (0.5 density level), 3rd PRB (0.33 density level), 4th PRB (0.25 density level), 5th PRB (0.2 density level), etc., may be configured with RSs. In this manner, the density level of RSs between RBs may be reduced with respect to full density, i.e. every RB is allocated with RSs. The first type of RS may have a configurable density level in time (herein referred to as a ‘symbol density). The first type of RS has a configurable RE usage. The first type of RS may be associated with (or related to) phase tracking reference signal (PTRS). The first type of RS (that is associated with PTRS) is herein referred to as enhanced PTRS (E-PTRS). In other examples, any other suitable name is used for E-PTRS. An antenna port of E-PTRS may be associated with an RE pattern wherein at least one RE is associated with an RB, of the physical channel resources. For NR PTRS, only one RE per PRB is allowed. For E-PTRS, the number of PRBs associated with an RE pattern for E-PTRS across an allocation for the physical channel may be flexibly configured, e.g. every RB, every 2nd RB, 3rd RB, 4th RB, 5th RB, etc., are configured with E-PTRS. Moreover, the E-PTRS may also have a configurable symbol density in time.

[0127] As another example, a second type of RS has a configurable RE usage. The second type of RS may be associated with (or related to) DM RS. The second type of RS (that is associated with DMRS) is referred to as light DMRS (L-DMRS). In other examples, any other suitable name is used for L-DMRS. L-DMRS may use a reduced number of REs in the frequency domain compared to 5G DMRS. L-DMRS may have RE patterns with reduced RB (PRB) density in frequency. L-DMRS has flexibility to configure multiple symbols in time (e.g., more than 4 symbols).

[0128] It should be understood that the terms “first” type of RS and “second” type of RS are used as labels only. In other examples, a first type of RS may be L-DMRS, and a second type of RSmay be E-PTRS. Furthermore, one or more of the following examples are applicable to other types of RS, such as, for example DMRS, front-loaded (FL) DMRS, and PTRS.

[0129] In some examples, a physical channel comprises more than one different type of RS (e.g., within a single slot, in time). For example, RE patterns of antenna port(s) associated with L-DMRS and E-PTRS are configured for a set of RBs of physical channel resources across different time symbols in a slot. A slot may comprise other combinations of different types of RS, e.g., FL DMRS and E-PTRS, or FL DMRS and L-DMRS.

[0130] In examples, CSI reporting is modified such that a UE provides a recommendation of an RS configuration from a plurality of RS configurations to the gNB, wherein the gNB may utilize the recommendation to select an RS configuration for a subsequent physical channel transmission. For example, the RS configuration may be associated with E-PTRS, or L-DMRS. In other examples, the RS configuration may be associated with PTRS, DMRS, or any other type of RS. The gNB may provide a configuration for CSI-ReportConfig that indicates that the UE should be reporting an RS configuration in the CSI report.

[0131] The UE determines which RS configuration to indicate in the CSI report based on CSI-RS that are sent by the gNB to the UE. The UE performs measurements on the CSI-RS in order to determine information related to CSI. In some examples, the UE further determines the RS configuration based on a criteria for selection (herein referred to as ‘selection criteria’) that is provided by the gNB to the UE. Stated differently, a CSI report is transmitted by the UE to the gNB, wherein the UE reports one or more (recommended / preferred) RS configuration candidates based on network configured (e.g., via RRC) selection criteria from of set of RS configuration candidates. Both the UE and the gNB are aware of (or are configured with) the set of RS configurations that are being selected from. This is discussed in more detail below.

[0132] An example of a selection criteria may be, the RS configuration with the ‘best’ demodulation performance according to a configured threshold (e.g., a block error rate (BLER) target of 0.1). Another example of a selection criteria may be, the RS configuration with a minimized RS resource overhead (in terms of RE usage for an intended PDSCH transmission). It should be understood that these are examples only, and that any suitable selection criteria may be provided from the gNB to the UE.

[0133] As described above, both the gNB and the UE are configured with a plurality of RS configurations (that the UE then selects from). For example, the plurality of RS configurations may be arranged in an ordered, or indexed, table. An example of this is depicted in Table 1, which shows a plurality of different RS configurations. Table 1 may be configured at the gNB, wherein the gNB then transmits an indication of Table 1 to the UE.

[0134] As shown in the example of Table 1, both the gNB and UE may be aware of four different RS configurations that may be utilized for a DL physical layer transmission from the gNB to UE. It should be understood that, in other examples, there may be more than four, or less than four, RS configurations that are configured. For example, one or more of RS config 1 to RS config 4 may be associated with E-PTRS and / or L-DMRS (as described above). Alternatively or additionally, one or more of RS config 1 to RS config 4 may be associated with PTRS and / or DMRS.

[0135] As described above, E-PTRS and L-DMRS may be flexibly configured in order to allow a reduction in RS overhead. When E-PTRS and / or L-DMRS is configured in an RS configuration, there may be an associated RE pattern for reference signals. For example, an RE pattern may comprise E-PTRS. In the following, the notation (x,y,z) (e.g., for E-PTRS) defines thatx = number of REs per antenna port per RB, y = density level between RBs, z = number of symbols (that carry RS). For example, an RE pattern for E-PTRS is defined as (4,2,1). The x-value of ‘4’ means that there are 4 REs per antenna port configured with an E-PTRS in an RB. The y-value of ‘2’ means that each / every 2nd RB across the BW of the physical channel is configured with RSs (i.e., some RBs do not carry RSs). The z-value of T means that 1 symbol in the RB is configured to carry E-PTRS. Stated differently, one E-PTRS antenna port is configured with four REs into every second RB across a scheduled / configured physical channel bandwidth. Other examples of RE patterns may be (2,2,2), (2,2,3), and (2,2,4). The above example has been described in relation to E-PTRS. This example is equally applicable to L-DMRS.

[0136] In some examples, both the gNB and the UE are configured with further RS configuration information. The further RS configuration information may be associated with the RS configurations of Table 1 (for example). Table 2 shows example RS x,y,z (x= number of REs per antenna port per RB, y= density level between RBs, z= number of symbols (that carry RS) for E-PTRS. This Table 2 may be different for each RS type (i.e. E-PTRS or L-DMRS). Stated differently, a separate table may be configured at the gNB and UE for each of E-PTRS and L-DMRS.

[0137] In examples whereby the gNB and UE are configured with the information of Table 1 and Table 2, the UE may report an index from Table 1 and Table 2 to indicate the recommended (or preferred) RS configuration in a CSI report. For example, a CSI report that comprises an indication of index 2, index 3. This would indicate that RS config 2 (which may be E-PTRS), that is configured according to RE pattern (2,2,4) is recommended for the demodulation of a subsequent PDSCH transmission.

[0138] In the examples described above, the RS configurations have been formatted in a table (e.g., Table 1 , Table 2). It should be understood that this is an example only, and that any suitable format may be used, e.g., list, database, etc.

[0139] When the UE has determined at least one RS configuration (e.g., as a recommendation), the UE includes an indication of the at least one RS configuration in a CSI report, to be sent to the gNB.

[0140] Based on the UE report the network configures or indicates the RS configuration for the PDSCH transmission(s). In one embodiment, the RS configuration may be associated to the TCI state that carries UE with reference signal(s) for example doppler spread, doppler shift, delay spread and average delay estimations. By having an RS configuration associated with each TCI state that is configured at the UE, it is possible to have an optimized RS configuration per beam pair link between network and UE, with one example being a TRP-specific RS configuration between the network and UE.

[0141] The above described determination of an RS configuration at the UE is also applicable for precoded CSI-RS. In such examples, the UE may assume that emulated DM RS is precoded with the same precoder.

[0142] FIG. 5 shows an example signalling diagram between a UE and a base station (e.g., gNB) for CSI acquisition and CSI reporting.

[0143] At S501, the gNB transmits, to the UE, an indication of a plurality of RS configurations. Each of the RS configurations may be considered to be associated with the demodulating of a physical channel (e.g., a PDSCH). The plurality of RS configurations may be considered to be different options of RS configurations related to subsequent physical channel (e.g., PDSCH)transmissions from the gNB. The demodulating of a DL physical channel based on the RS configuration is discussed in more detail below.

[0144] As an example, in S501, the gNB may transmit an indication of ‘RS config T, ‘RS config 2’, ‘RS config 3’ and ‘RS config 4’ to the UE, as shown in Table 1. It should be understood that the transmitting of 4 RS configurations is an example only. In other examples, more or less than 4 RS configurations may be provided to the UE.

[0145] Each of the RS configurations may be associated with an index. In other examples, the order in which the RS configurations are indicated to the UE are interpreted as an implicit index for that RS configuration (e.g., the second RS configuration in a list is considered to have an index of ‘2’).

[0146] The gNB may also transmit, to the UE, a selection criteria associated with the RS configurations.

[0147] At S502, the gNB transmits CSI-RS (e.g., NZP-CSI-RS) to the UE.

[0148] At S503, the UE receives the CSI-RS from the gNB. Based on the CSI-RS that have been received, determine a value of a parameter associated with CSI.

[0149] For example, the UE may determine a value for SNR (or SINR) based on the CSI-RS. Alternatively or additionally, the UE may determine a value for another parameter associated with CSI. In some examples, the UE determines a value for each of a plurality of parameters associated with CSI. The plurality of parameters associated with CSI may be the same, or may be different.

[0150] Stated differently, in S503, the UE estimates a radio channel between the UE and the gNB, wherein the estimation of the radio channel is based on the UE receiving CSI-RS.

[0151] At S504, the UE obtains information that is related to the parameter associated with CSI for each of the plurality of RS configurations. The information that is related to the parameter associated with CSI is associated with each of the RS configurations. For example, the (obtained) information may be received at the UE, or may be determined by the UE itself.

[0152] The UE selects a first RS configuration from the plurality of RS configurations based on the value of the parameter associated with CSI. For example, the selecting may comprise comparing the value of the parameter associated with CSI with the information that is associated with each of the RS configurations.

[0153] In some examples, the selecting of the first RS configuration is further based on the selection criteria (received from the gNB). For example, if the selection criteria that is configured at the UE is to determine the best demodulation performance according to a configured threshold(e.g., a block error rate (BLER) target of 0.1), then the RS selection is performed in order to determine at least one RS configuration that adheres to the configured threshold.

[0154] At S505, the UE transmits, to the gNB, a CSI report comprising an indication of the first RS configuration. For example, the indication may comprise an index related to the first RS configuration. With the example of Table 1 and Table 2 described above, the CSI report may comprise “1, 2” (to indicate that ‘RS config T with RE pattern 2,2,3 is recommended), or simply “4” (to indicate that ‘RS config 4’ is recommended). The CSI report is generated by the UE.

[0155] At S506, the gNB receives the CSI report. Based on the indication of the first RS configuration, the gNB determines which RS configuration from the plurality of RS configurations to utilize for a subsequent DL physical channel transmission to the UE.

[0156] The gNB may select the first RS configuration (based on the recommendation of the UE). However, the gNB is not bound by the recommendation of the UE. The gNB may be free to choose an RS configuration that differs from the recommendation of the UE due to other factors such as traffic load, service requirements or any other aspect that requires optimization in the network.

[0157] In this example, it is assumed that the gNB selects the first RS configuration for a first physical channel (e.g., PDSCH) transmission to the UE. In another example, the gNB selects a second RS configuration of the plurality of RS configurations, wherein the first RS configuration is different to the second RS configuration.

[0158] The indication of the first RS configuration within the CSI report may be considered to be assistance information for the network.

[0159] At S507, the gNB transmits an indication that the first RS configuration will be utilized for the first PDSCH transmission to the UE. The indication of the first RS configuration is transmitted to the UE before the first PDSCH transmission.

[0160] The indication that the first RS configuration will be utilized may be provided to the UE in RRC signalling. In other examples, the indication that the first RS configuration will be utilized is included in scheduling DCI.

[0161] When the UE subsequently receives the first PDSCH transmission, from the gNB, the UE demodulates the PDSCH based on the first RS configuration.

[0162] In some examples, the gNB associates the RS configuration (e.g., the first RS configuration) to be applied for the PDSCH transmission with a transmission configuration indicator (TCI) state.

[0163] The network (e.g., gNB) configures the UE with a plurality of different TCI states in RRC. The network may configure each TCI state with a DM RS configuration. The configuring of the UE with the TCI states may utilise RRC or medium access control (MAC) layer signalling. Then, thenetwork activates (e.g., using in MAC, or indicates in L1 signalling (DCI)) in the UE one of the (configured) TCI states to be the currently activated, or currently indicated, TCI state. The UE applies the activated / indicated TCI state for the reception of PDSCH, wherein the TCI state comprises UE information about the DM RS configuration.

[0164] In this manner, in some examples, each of a plurality of TCI states that are configured at the UE has an associated RS configuration. When the network (e.g., gNB) transmits an indication of a TCI state (e.g., to activate), then the UE applies the RS configuration that is associated with the indicated TCI state associated with the PDSCH transmission. This allows the network to optimize RS configuration per TCI state (or per beam-pair link) between the network and the UE. Furthermore, there will be no increase in the amount of signalling needed from the gNB to the UE in order for the gNB to inform the UE of the RS configuration for an upcoming physical layer transmission to the UE.

[0165] It should be understood that, in other examples, one or more of the steps of FIG. 5 may not be performed or may be performed in a different order.

[0166] In examples, (e.g., in relation to a 6G variant of 3GPP TS 38.331), a ‘new’ CSI reportQuantity for an RS configuration is defined. The reportQuantity may be defined as shown in the example below, in an IE:reportQuantity-6G-RS CHOICE {K-best RS configurations ENNUMERATED (K1..KX))T-best RS types ENNUMERATED (T0..TX)) Non-configured report INTEGER (0,1))}}OPTIONAL - Need R

[0167] When a UE is configured with a CSI-ReportConfig with the parameter reportQuantity-6G-RS, the UE reports information related to the requested RS configurations.

[0168] In the example IE extract of CSI-ReportConfig above, the reportQuantity may include “K-best RS configurations” and “T-best RS types”. “K-best RS configurations” is RS type specific. For example, when K=2, then the UE reports two the best 2 RS configurations for each RS type in a CSI report. “T-best RS types” indicates the number of RS types. For example, when T=3, then this indicates that the 3 best RS types should be reported by the UE. As described above, examples of RS types include, DM RS, PTRS, FL-DMRS, L-DMRS, E-PTRS. There may also bea combination of two or more different RS types within a symbol (which may be written as L-DMRS + E-PTRS, or FL-DMRS + L-DMRS).

[0169] For example, a gNB may indicate in ‘reportQuantity-6G-RS’ K=1 and T=2, which means that UE would report one (K=1) RS configuration for two (T=2) RS types. A CSI report format may be that first, the best index for an RS type is included, and K options in best order, followed by the second best RS type with K options, e.g., 4, 2, 3, 3, this would indicate that RS config 4 is the best (from Table 1) with 2-2-3 configuration (from Table 2, when assuming that Table 2 is also applicable for RS config 4), and the second best is L-RS config 3 with a 2-2-4 configuration (from Table 2, when assuming that Table 2 is also applicable for RS config 3). It should be understood that this is simply an example only, to aid in the understanding of the disclosure.

[0170] As described above, alongside FIG. 5, a UE selects at least one RS configuration to indicate in a CSI report to a gNB (as a recommendation for the network) based on received CSI-RS at the UE. The selection may further be based on at least one selection criteria. An example of this selection is detailed below, alongside FIG. 6.

[0171] FIG. 6 shows an example method flow performed by a user equipment for CSI acquisition and CSI reporting.

[0172] At S601, the UE receives a configuration related to CSI (e.g., CSI-ReportConfig). Upon reception of the configuration related to CSI, the UE estimates an emulated DM RS performance based on received CSI-RS (from a gNB). The estimation of the emulated DMRS performance may comprise estimating an emulated precoded DMRS using (received) CSI-RS, PMI, and Rl (wherein the PMI and Rl are determined by the UE based on the received CSI-RS). The estimation of the emulated DMRS performance may be based on at least one parameter related to CSI, wherein values for the at least one parameter related to CSI are determined based on the received CSI-RS. For example, the at least one parameter related to CSI may be an effective SNR. An effective SNR captures an impact of the radio channel and a reception filterof a receiver. The reception filter may be, e.g., a maximum ration combining (MRC) filter, or a minimum mean squared error (MMSE) filter. Stated differently, an effective SNR comprises information about a signal to noise ratio for a (radio) channel (e.g., between transmitter and receiver) and a filter of a receiver (e.g., a reception filter). The estimation of the emulated DMRS performance will be described in more detail below alongside FIG. 7.

[0173] At S602, the UE may be configured with a selection criterion or selection criteria. In the example of FIG. 6, the UE is configured with two selection criteria, which includes: Criteria A = the RS configuration with the ‘best’ demodulation performance according to a configured threshold of a BLER target of 0.1, and Criteria B = the RS configuration with a minimized RS resource overhead (in terms of RE usage for an intended PDSCH transmission). In this manner,1the UE is configured to provide CSI reporting such that the RS overhead for the current channel conditions is minimized while maintaining a BLER target of 0.1. The selection criteria (or selection criterion) may be provided with the configuration related to CSI. In other examples, the selection criteria / selection criterion is already configured at the UE (e.g., a default, or from previous CSI reporting). In other examples, the UE is not configured with selection criteria / selection criterion.

[0174] The UE selects at least one RS configuration from a plurality of RS configurations based on at least one of: the emulated DMRS performance (e.g., the effective SNR determined in S601), the configuration related to CSI, the selection criteria, and other estimated (or configured) parameters such as: carrier frequency range / frequency band, sub-carrier spacing / numerology value, rank / number of layers value for PDSCH, modulation and coding scheme (MCS), Doppler frequency / spread, time correlation of value of a channel, or allocation bandwidth. For example, there may be a subcarrier spacing (SCS) of one of: 15kHz, 30kHz, or 60kHz. Based on the SCS information, there may be specific information (e.g., mapping curves) for different numerologies that the UE may use to select the at least one RS configuration.

[0175] At S603, the UE transmits CSI report to the network, the CSI report comprising an indication of at least one RS configuration.

[0176] Based on the CSI report and scheduling status, gNB selects an RS configuration for a downlink transmission

[0177] At S604, the UE receives, from the gNB, an indication of an applied RS configuration for a PDSCH transmission. The indication may be received in scheduling DCI. In other examples, the UE may determine the applied RS configuration from a current indicated TCI state, wherein each of the TCI states that are configured at the UE are associated with a TCI state. For example, a UE is configured with: TCI #1 which is associated with a first RS configuration, TCI #2 which is associated with a second RS configuration, and TCI #3 which is associated with a third RS configuration. If the network is to activate, or indicate, TCI#1 to be utilized for an upcoming physical channel transmission to the UE, then the UE knows also to select the first RS configuration (as it is associated with the activated TCI #1).

[0178] It should be understood that, in other examples, one or more of the steps of FIG. 6 may not be performed or may be performed in a different order.

[0179] FIG. 7 shows another example method flow performed by a user equipment for CSI acquisition and CSI reporting.

[0180] In the example of FIG.7, the UE receives CSI-RS and is configured with K-best RS configurations and T-best RS types to be reported.

[0181] At S701, the UE performs a channel estimation for a radio channel between the UE and the network based on received CSI-RS. The UE may calculate channel estimates for each antenna port that is configured, based on CSI-RS that are received.

[0182] The calculation of the channel estimates may comprise determining raw channel estimates associated with antenna ports of CSI-RS, e.g. by using least square (LS) based channel estimator between received CSI-RS samples and a known sequence of CSI-RS, according to specified time and frequency locations.

[0183] The UE may perform stacking of raw channel estimates for each antenna port symbol. Frequency domain interpolation is then performed using (e.g., Wiener) filtering for estimates associated with each antenna port (or layer), receive antenna, and symbol separately. Time domain interpolation using (e.g., Wiener) filtering is performed between time domain symbols for each antenna ports (or layer), and receive antenna. Joint channel estimation is then completed using 2-dimensional (2D) Wiener filtering. In other examples, any suitable method of determining channel estimates based on the CSI-RS is performed at the UE.

[0184] At S702, the UE determines a (joint) rank and PMI hypothesis associated with a configured number of antenna ports and one or more resources. Depending on the number of (NZP) CSI-RS ports there may be a different number of resources. For example, in the case of 64 CSI-RS ports, there would be two sets of 32 CSI-RS ports. In this context, the hypothesis may be considered to be a ‘candidate’ option / configuration. Stated differently, there may be a plurality of different rank and PMI options that the UE could compute. The UE is to estimate the performance for each of the hypothesis (candidates) in order to report the ‘best’ configuration.

[0185] At S703, the UE determines an effective SNR for each layer (i.e. , each antenna port). This is repeated for each hypothesis.

[0186] At S704, the UE applies the effective SNR to calculate capacity. Stated differently, the UE determines a capacity based on the effective SNR (for each hypothesis). For example, the capacity that is calculated may be the Shannon’s capacity. Shannon’s capacity is an indicator of spectral efficiency. The Shannon capacity theorem defines the maximum amount of information, or data capacity, which can be sent over any channel or medium. The theorem indicates that the higher the SNR and the greater the channel bandwidth, then this leads to a higher possible data rate. As a consequence of this, the minimum SNR required for data transmission may be calculated. This is known as the Shannon limit, and it occurs as the available bandwidth goes to infinity.

[0187] As an example related to S704, if the rank is 6, then the capacity is calculated for each layer. When the number of layers is increased, performance does not linearly increase because, depending on the channel conditions, the number of spatial channels may vary (i.e., the channels cannot be separated). This means that, at a certain rank, the performance increment is not enough that it would be sufficient to use that higher rank, and so the lower rank is selected.

[0188] At S705, the UE selects a (joint) rank and PMI that has an associated capacity that is maximized. Stated differently, the rank and PMI associated with the largest capacity is selected (determined in S704).

[0189] The capacity may be determined with the following equation, or any other suitable equation. Capacity =wherein T is the layer (or antenna port), and ‘ effSNRi ‘ the effective SNR per layer.

[0190] When the UE selects the (joint) rank, the UE may only select a higher rank if it increases the total capacity over summed layers. For example, the UE may determine that: rank 1 throughput (tput) = 110 Mbit / s, rank 2 tput = 200 Mbit / s, and rank 3 tput = 190 Mbit / s. Rank 2 would be selected by the UE as choosing a higher rank does not increase the throughput.

[0191] Based on the selected rank and PMI, the UE selects a CQI. For example, the selected rank and PMI is mapped to a largest CQI (or MCS) value. The UE then selects the CQI that, e.g., 10% BLER is achieved. Stated differently, based on SNR, UE has pre-calculated CQI curves. The effective SNR value is then mapped to a corresponding CQI curve, in order to determine the best performance so that 10% BLER is achieved. Alternatively, for CQI calculation, the effective SNR value may be mapped to tabled CQI index values, associated with a MCS, code rate and efficiency. It should be understood that 10% / 0.1 BLER is an example only. In other examples, the UE is configured with a value higher or lower than 10% / 0.1 BLER, or with a different metric.

[0192] At S706, the UE selects an RS configuration from the plurality of RS configurations based on the effective SNR. In some examples, the UE selects the RS configuration with one of two different methods, dependent on the rank that has been determined in S705. A first method when the rank is above 4, and a second method when the rank lower than or equal to 4. The two different methods are used, based on the rank, because when the rank is greater than 4, then there would be two code words (rather than one code word).

[0193] When the rank < 4 : The UE selects the effSNR (wherein effSNR is the average SNR over the layers), which maximized the capacity. The UE maps the effSNR, to corresponding performance curves that are associated with each of the plurality of RS configurations.

[0194] Example performance curves are shown in FIGS. 8 to 10. The example performance curves comprise information related to parameters associated with CSI. The UE obtains the information related to parameters associated with CSI for each of the plurality of RS configurations (e.g., the UE obtains the performance curves for each RS configuration). In some examples, the UE receives the information related to parameters associated with CSI for each of the plurality of RS configurations. In other examples, the UE determines the information related to parameters associated with CSI for each of the plurality of RS configurations. In the examples of FIGS. 8 to 10 the information is presented in graphical form, but it should be understood that the information may be obtained in any suitable format.

[0195] For example, the obtaining of the information related to parameters (which may also be referred to as ‘estimate values’) comprises determining the estimated values of the first metric at each of the plurality of different SNR values for each of the plurality of configurations based on: mapping tables accessible to the UE, and predefined parameters. The predefined parameters may comprise at least one of the following: carrier frequency range, frequency band, sub-carrier spacing, numerology value, rank, number of layers value for downlink physical channel, modulation and coding scheme, Doppler frequency, spread, time correlation of value of a channel, or allocation bandwidth. In other examples, the obtaining of the information related to parameters (which may also be referred to as ‘estimate values’) comprises determining the estimated values of the first metric at each of the plurality of different SNR values for each of the plurality of configurations based on a fitting function. In some examples, the fitting function is one of: a second order, or a higher order, polynomial fitting. In some examples, the fitting function is implemented in a linear way, or polynomial way.

[0196] Each of FIGS. 8 to 10 is associated with one RS configuration of the plurality of RS configurations. Each of FIGS. 8 to 10 show reference lines for comparison (i.e., to a reference RS configuration). FIG. 8 is associated with L-DMRS with RE pattern 2,2,3, which is shown with label 801 (dashed lines). There is also shown a reference RS configuration which is shown with label 803 (solid lines). The reference RS configuration is the same in FIGS. 8 to 10. FIG. 9 is associated with L-DMRS with RE pattern 2,2,4, which is shown with label 901. There is also shown a reference RS configuration which is shown with label 903. FIG. 10 is associated with L-DMRS with RE pattern 2,2,5, which is shown with label 1001. There is also shown a reference RS configuration which is shown with label 1003. The lines / curves of each performance curve represents estimated values / estimated performance associated with the respective configuration. Based on channel conditions (and potentially other information), the UE estimates which RS configuration would be most suitable, in order to give the ‘optimum’ or ‘best’ performance. The ‘optimum’ or ‘best’ performance may be based on a selection criterion, such that the ‘optimum’ or ‘best’ performance is the RS configuration that is estimated to match the selection criterion.

[0197] Each line / curve in each of FIGS. 8 to 10 corresponds to an MCS value. Based on the effective SNR and MCS that has already been determined, the UE compares the determined SNR and MCS to the curves in FIG. 8 to 10 in order to determine which RS configuration maximizes the throughput. It is assumed that each RS configuration has associated information related to parameters associated with CSI (e.g., an associated set of curves, see FIGS. 8 to 10).

[0198] In the examples of FIGS. 8 to 10, the information related to parameters associated with CSI comprises SNR and throughput information. In other examples, the RS configurations may comprise other information related to parameters associated with CSI (e.g., CQI, PMI, etc).

[0199] In the example of FIG. 7, the UE utilises the information related to parameters associated with CSI in order to determine the RS configuration that maximizes throughput, based on theeffective SNR that has been determined. The UE performs the determination from all of the configured RS configurations.

[0200] When the rank > 4 : The UE selects a corresponding code word (CW) effSNR where effSNR=rr\3x(e f fSNRc , ef fSNRci^Y

[0201] For example, the rank may be 6. In this example, with rank 6, there may be a split of the layers between two codewords (CWs). In examples, there may be 4 layers in CW1 and 2 layers in CW2. Each of the two CWs may have different MCS. The UE then selects either a maximum (max) or minimum (min) for (effSNRcwl, effSNRCW2f In this manner, according to UE implementation, the UE may use the ‘max’ equation or the ‘min’ equation for the selection.

[0202] In some examples, the UE selects the K-best and T-best RS types (if configured by the network).

[0203] At S707, the UE generates a CSI report. The CSI report comprises an indication of at least one RS configuration. The UE transmits the CSI report to the gNB.

[0204] As described in FIG. 7, stated differently, the UE may emulate DMRS performance by mapping an effective SNR to performance curves of different RS configurations, wherein the effective SNR is determined (or estimated) from the received CSI-RS. The performance curves may comprise obtained estimated values of a first metric (e.g., the first metric may be throughput) at each of a plurality of different SNR values for each of a plurality of RS configurations. Based on the effective SNR, the UE selects one or more RS configurations. For example, the UE compares the effective SNR to the values of the first metric at the plurality of different SNR values, for each RS configuration. The UE may select the RS configuration that has a value of the first metric (at the effective SNR) that is indicative of the best performance, or matches a selection criterion. The UE then indicates, as assistance information for the network, the selected RS configuration which has been determined to reflect the best PDSCH demodulation performance.

[0205] For example, the UE may be configured with ‘RS configuration T and ‘RS configuration 2’, the UE obtains estimates values of throughput (e.g., Mbits / s) at different SNR for ‘RS configuration T and ‘RS configuration 2’, which is shown in Table 3:Table 3: Example of obtained estimated values of a first metric (throughput, TP) at a plurality of different SNR values.

[0206] If the UE determined an effective SNR of 10 dB, then the UE compares the effective SNR with the information comprised in Table 3. As the TP is estimated to be higher for ‘RS config 2’ (compared to ‘RS config T) at an SNR of 10, then the UE selects ‘RS config 2’. In some examples, the UE will be configured with a selection criterion to select the RS configuration with a maximized throughput. The selection of ‘RS config 2’ may be further based on a selection criterion.

[0207] It should be understood that, in other examples, one or more of the steps of FIG. 7 may not be performed or may be performed in a different order.

[0208] One or more of the examples described above have the advantage of improved DL physical channel performance. The network is able to make a more informed decision about which RS configuration to apply when performing a DL physical channel transmission to a UE, which in turn leads to the improved performance. The UE is able to determine which RS configuration may be more suitable for the UE and provide this recommendation to the network (e.g., in a CSI report). For example, a high mobility UE may require more RS (i.e. , a higher RS overhead), than a low mobility UE. Due to this, RS overhead may be reduced as the network is able to select an RS configuration that has a lower RS overhead, knowing that this would still be suitable for the specific UE (e.g., which may have lower mobility). Furthermore, there may be particular performance improvement for UEs at a cell edge, by providing additional RS for UEs at cell edge. This will help the UEs at cell edge to successfully decode physical channel transmissions from the network. In this manner, one or more of the examples have the advantage that downlink transmission performance is optimised. High transmission speeds are still possible from the gNB to the UE, while allowing RS overhead to be minimised.

[0209] FIG. 11 shows an example method flow performed by an apparatus. The apparatus may be a user equipment, or other communication device. The apparatus may be comprised within a user equipment, or other communication device. The apparatus may comprise one or more means for performing the method of FIG. 11. For example, the one or more means may comprise: at least one processor, and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus to perform the method of FIG. 11. For example, the one or more means may comprise circuitry configured to perform the method of FIG. 11.

[0210] In S1101, the method comprises: receiving, from a network entity, channel state information-reference signals, CSI-RS.

[0211] In S1103, the method comprises: determining, based on the CSI-RS, a first value of a parameter associated with CSI.

[0212] In S1105, the method comprises: selecting, based on the first value of the parameter associated with CSI, a first configuration related to at least one reference signal, RS, fordemodulating at least one physical channel from a plurality of configurations related to at least one RS for demodulating at least one physical channel, wherein each of the plurality configurations is associated with information that is related to the parameter associated with CSI.

[0213] In S1107, the method comprises: transmitting, the network entity, a CSI report comprising an indication of the first configuration.

[0214] It should be understood that, in some examples, one or more additional method steps are included in the method flow of FIG. 11 and are performed by the apparatus. In some examples, one or more of the method steps of FIG. 11 detailed above may not be performed, or may be performed in a different order.

[0215] FIG. 12 shows an example method flow performed by an apparatus. The apparatus may be a network entity, such as a base station, gNB, etc. The apparatus may be comprised within a network entity. The apparatus may comprise one or more means for performing the method of FIG. 12. For example, the one or more means may comprise: at least one processor, and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus to perform the method of FIG. 12. For example, the one or more means may comprise circuitry configured to perform the method of FIG. 12.

[0216] In S1201, the method comprises: transmitting, to a user equipment, UE, channel state information-reference signals, CSI-RS.

[0217] In S1203, the method comprises: receiving, from the UE, a CSI report comprising an indication of a first configuration related to at least one reference signal, RSs, for demodulating at least one physical channel from among a plurality of configurations related to at least one RS for demodulating at least one physical channel.

[0218] In S1205, the method comprises: based on the indication of the first configuration, selecting a second configuration from the plurality of configurations, for the UE to utilise to demodulate a physical channel transmission from the network entity to the UE.

[0219] It should be understood that, in some examples, one or more additional method steps are included in the method flow of FIG. 12 and are performed by the apparatus. In some examples, one or more of the method steps of FIG. 12 detailed above may not be performed, or may be performed in a different order.

[0220] FIG. 13 shows an example method flow performed by an apparatus. The apparatus may be a user equipment, or other communication device. The apparatus may be comprised within a user equipment, or other communication device. The apparatus may comprise one or more means for performing the method of FIG. 11. For example, the one or more means may comprise: at least one processor, and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus to perform the method of FIG. 11. For example, the one or more means may comprise circuitry configured to perform the method of FIG. 11.

[0221] In S1301, the method comprises: receiving, from a network entity, at least one channel state information-reference signal, CSI-RS.

[0222] In S1303, the method comprises: determining a first value of a signal to noise ratio, SNR, based on the CSI-RS.

[0223] In S1305, the method comprises: obtaining estimated values of a first metric at each of a plurality of different SNR values for each of a plurality of configurations, each of the plurality of configurations being related to at least one RS for demodulating at least one physical channel.

[0224] In S1307, the method comprises: based on the first value of the SNR, selecting a first configuration from the plurality of configurations, wherein the selecting comprises comparing the first value of the SNR with the estimated values of the first metric at each of the plurality of different SNR values that are associated with each of the plurality of configurations.

[0225] In S1309, the method comprises: transmitting, the network entity, a CSI report comprising an indication of the first configuration

[0226] It should be understood that, in some examples, one or more additional method steps are included in the method flow of FIG. 13 and are performed by the apparatus. In some examples, one or more of the method steps of FIG. 13 detailed above may not be performed, or may be performed in a different order.

[0227] FIG. 14 shows a schematic representation of an apparatus. FIG. 14 shows, by way of example, a block diagram of an apparatus 10. The apparatus 10 comprises, for example, at least one processor 12 and at least one memory 14 storing instructions 15 that, when executed by the at least one processor, cause the apparatus 10 at least to perform the method or methods as disclosed herein, and any of the embodiments thereof. In an example, the at least one memory and the instructions (e.g. a computer program code, software), are configured, with the at least one processor, to cause the apparatus 10 to perform the method or methods as disclosed herein, and any of the embodiments thereof.

[0228] A processor 12 may comprise circuitry, or be constituted as circuitry or circuitries, the circuitry or circuitries being configured to perform phases of methods in accordance with example embodiments described herein. As used in this application, the term “circuitry” may refer to one or more or all of the following: (a) hardware-only circuit implementations, such as implementations in only analog and / or digital circuitry, and (b) combinations of hardware circuits and software, such as, as applicable: (i) a combination of analog and / or digital hardware circuit(s) with software / firmware and (ii) any portions of hardware processor(s) with software (including digital signal processor(s)), software, and memory(ies) that work together to cause an apparatus, such as a user equipment, to perform various functions) and (c) hardware circuit(s) and or processor(s), such as a microprocessor(s) or a portion of a microprocessor(s), that requires software (e.g., firmware) for operation, but the software may not be present when it is not needed for operation. This definition of circuitry applies to all uses of this term in this application, including in any claims.As a further example, as used in this application, the term circuitry also covers an implementation of merely a hardware circuit or processor (or multiple processors) or portion of a hardware circuit or processor and its (or their) accompanying software and / or firmware. The term circuitry also covers, for example and if applicable to the particular claim element, a baseband integrated circuit or processor integrated circuit for a mobile device or a similar integrated circuit in server, a cellular network device, or other computing or network device.

[0229] The memory 14 may be implemented using any suitable data storage technology. The memory may comprise a database for storing data. The memory 14 may be at least in part external to apparatus 10 but accessible to apparatus 10.

[0230] The instructions 15 may be comprised in a computer readable medium or a non-transitory computer readable medium. A term non-transitory, as used herein, is a limitation of the medium itself (i.e. tangible, not a signal) as opposed to a limitation on data storage persistency (e.g. random access memory, RAM, vs. read only memory, ROM).

[0231] For example, the apparatus 10 is a communication device, such as the UE associated with any of FIGS. 5 to 7. As another example, the apparatus is comprised in such a communication device, e.g. as a chipset configured to control the communication device. The apparatus 10 may be caused or configured to perform at least the method of FIG. 11 or 13 and / or any one or more of the examples described.

[0232] As another example, the apparatus 10 is a network node, e.g. the gNB associated with FIG. 5. In another example, the apparatus 10 is comprised in such a network node, e.g. as a chipset configured to control the network node. The apparatus 10 may be caused or configured to perform at least the method of FIG. 12 and / or any one or more of the examples described.

[0233] The apparatus 10 comprises a radio interface 16. The radio interface 16 may provide the apparatus 10 with communication capabilities. The radio interface 16 may comprise a receiver configured to receive information in accordance with at least one cellular or non-cellular standard. The radio interface 16 may comprise a transmitter configured to transmit information in accordance with at least one cellular or non-cellular standard. The receiver may comprise more than one receiver. The transmitter may comprise more than one transmitter. The radio interface 16 may comprise a transceiver configured to receive and transmit information in accordance with at least one cellular or non-cellular standard. The transceiver may comprise more than one transceiver.

[0234] The apparatus 10 may comprise a user interface 18 comprising, for example, at least one of a keypad, a microphone, a touch display, a display, a speaker, etc. The user interface 18 may be used to control the apparatus by the user. The user interface 18 may be external to the apparatus 10. For example, the apparatus 10 may be connected to another device, such as acomputer, either via wireless or wired connection, and the apparatus 10 is controlled by the user via the computer.

[0235] In an embodiment, at least some of the processes described herein may be carried out by an apparatus comprising means for carrying out at least some of the described processes. Means for performing method steps as disclosed herein may include software and / or hardware components of the apparatus 10. For example, the at least one processor 12, the memory 14, and the computer program code form means for carrying out the method or methods as disclosed herein, and any of the embodiments thereof. As used herein the term “means” is to be construed in singular form, i.e. referring to a single element, or in plural form, i.e. referring to a combination of single elements. Therefore, terminology “means for [performing A, B, C]”, is to be interpreted to cover an apparatus in which there is only one means for performing A, B and C, or where there are separate means for performing A, B and C, or partially or fully overlapping means for performing A, B, C. Further, terminology “means for performing A, means for performing B, means for performing C” is to be interpreted to cover an apparatus in which there is only one means for performing A, B and C, or where there are separate means for performing A, B and C, or partially or fully overlapping means for performing A, B, C. It is noted that while the above describes example embodiments, there are several variations and modifications which may be made to the disclosed solution without departing from the scope of the present invention.

[0236] The examples may thus vary within the scope of the attached claims. In general, some embodiments may be implemented in hardware or special purpose circuits, software, logic or any combination thereof. For example, some aspects may be implemented in hardware, while other aspects may be implemented in firmware or software which may be executed by a controller, microprocessor or other computing device, although embodiments are not limited thereto. While various embodiments may be illustrated and described as block diagrams, flow charts, or using some other pictorial representation, it is well understood that these blocks, apparatus, systems, techniques or methods described herein may be implemented in, as non-limiting examples, hardware, software, firmware, special purpose circuits or logic, general purpose hardware or controller or other computing devices, or some combination thereof.

[0237] The examples may be implemented by computer software stored in a memory and executable by at least one data processor of the involved entities or by hardware, or by a combination of software and hardware. Further in this regard it should be noted that any procedures may represent program steps, or interconnected logic circuits, blocks and functions, or a combination of program steps and logic circuits, blocks and functions. The software may be stored on such physical media as memory chips, or memory blocks implemented within the processor, magnetic media such as hard disk or floppy disks, and optical media such as for example DVD and the data variants thereof, CD.

[0238] The term “non-transitory”, as used herein, is a limitation of the medium itself (i.e. tangible, not a signal) as opposed to a limitation on data storage persistency (e.g. RAM vs ROM).

[0239] As used herein, “at least one of the following:” and “at least one of: ” and similar wording, where the list of two or more elements are joined by “and”, or “or”, mean at least any one of the elements, or at least any two or more of the elements, or at least all of the elements.

[0240] The memory may be of any type suitable to the local technical environment and may be implemented using any suitable data storage technology, such as semiconductor-based memory devices, magnetic memory devices and systems, optical memory devices and systems, fixed memory and removable memory. The data processors may be of any type suitable to the local technical environment, and may include one or more of general purpose computers, special purpose computers, microprocessors, digital signal processors (DSPs), application specific integrated circuits (ASIC), gate level circuits and processors based on multi core processor architecture, as non-limiting examples.

[0241] As used herein, the terms “means for”, “means for performing operations including”, “means configured to perform operations including”, or “means configured to perform” (or similar) may be any means that are suitable for performing the feature(s). The “means” may be configured to perform one or more of the functions and / or method steps previously described. For example, the “means” may include one or more of: at least one processor, at least one memory, transceiver circuitry, antenna circuitry, etc. It should be understood that these are provided as non-limiting examples.

[0242] Alternatively, or additionally some examples may be implemented using circuitry. The circuitry may be configured to perform one or more of the functions and / or method steps previously described. That circuitry may be provided in the base station and / or in the communications device.

[0243] As used in this application, the term “circuitry” may refer to one or more or all of the following: (a) hardware-only circuit implementations (such as implementations in only analogue and / or digital circuitry); (b) combinations of hardware circuits and software, such as: (i) a combination of analogue and / or digital hardware circuit(s) with software / firmware and (ii) any portions of hardware processor(s) with software (including digital signal processor(s)), software, and memory(ies) that work together to cause an apparatus, such as the communications device or base station to perform the various functions previously described; and (c) hardware circuit(s) and orprocessor(s), such as a microprocessor(s) ora portion of a microprocessor(s), that requires software (e.g., firmware) for operation, but the software may not be present when it is not needed for operation.

[0244] This definition of circuitry applies to uses of the term “means” in this application, including in any claims. As a further example, as used in this application, the term circuitry also covers an implementation of merely a hardware circuit or processor (or multiple processors) or portion of a hardware circuit or processor and its (or their) accompanying software and / or firmware. The term circuitry also covers, for example integrated device. The term circuitry also covers, for example and if applicable to the particular claim element, a baseband integrated circuit or processor integrated circuit for a mobile device or a similar integrated circuit in a server, a cellular network device, or other computing or network device.

[0245] The foregoing description has provided by way of exemplary and non-limiting examples a full and informative description of some embodiments. However, various modifications and adaptations may become apparent to those skilled in the relevant arts in view of the foregoing description, when read in conjunction with the accompanying drawings and the appended claims. However, all such and similar modifications of the teachings will still fall within the scope as defined in the appended claims.

Claims

CLAIMS1. A method performed by a user equipment, UE, the method comprising:receiving, from a network entity, channel state information-reference signals, CSI-RS; determining, based on the CSI-RS, a first value of a parameter associated with CSI; selecting, based on the first value of the parameter associated with CSI, a first configuration related to at least one reference signal, RS, for demodulating at least one physical channel from a plurality of configurations related to at least one RS for demodulating at least one physical channel, wherein each of the plurality configurations is associated with information that is related to the parameter associated with CSI; andtransmitting, the network entity, a CSI report comprising an indication of the first configuration.

2. The method according to claim 1 , wherein the parameter associated with CSI comprises one of: a signal to noise ratio, a signal to noise plus interference ratio, a channel quality indicator, or a modulation and coding scheme.

3. The method according to claim 1 or claim 2, wherein the method further comprises: receiving, from the network entity, a configuration for CSI, wherein the configuration for CSI indicates that the UE is to report at least one RS configuration.

4. The method according to claim 3, wherein the configuration for CSI indicates that the UE is to report at least two configurations related to at least one RS, each of the at least two configurations being associated with different types of RS.

5. The method according to any of claims 1 to 4, where the method further comprises: receiving, from the network entity, at least one criterion for selection of the RS configuration, wherein the selecting of the first configuration is further based on the at least one criterion for selection.

6. The method according to any of claims 1 to 5, wherein the method further comprises: receiving, from the network entity, an indication of the plurality of configurations, wherein each configuration of the plurality of configurations is associated with the information that is related to the parameter associated with CSI.

407. The method according to any of claims 1 to 6, wherein each of the plurality of configurations is associated with an index, wherein the indication of the first configuration comprised in the CSI report comprises an index of the first configuration.

8. The method according to any of claims 1 to 7, wherein, for each of the configurations, the information that is related to the parameter associated with CSI comprises a mapping between a throughput and a signal to noise ratio.

9. The method according to claim 8, wherein, for each of the configurations, the information that is related to the parameter associated with CSI comprises a mapping between a throughput and a signal to noise ratio for each of a plurality of different modulation and coding schemes.

10. The method according to claim 8 or claim 9 when appended to claim 5, wherein the at least one criterion for selection indicates that the throughput is to be utilised by the UE when selecting the configuration related to at least one RS.

11. The method according to any of claims 1 to 10, wherein the method further comprises:receiving, from the network entity, a second indication of a second configuration of the plurality of configurations; anddemodulating a physical channel transmission from the network entity based on the second configuration.

12. The method according to claim 11 , wherein one of:the second indication is received in scheduling downlink control information; or the second indication comprises an indication of a first transmission configuration indication, TCI, state from a plurality of TCI states to be utilised for receiving the physical channel transmission from the network entity, wherein each of the plurality of TCI states is associated with one of the plurality of configurations related to at least one RS, wherein the first TCI state is associated with the second configuration.

13. The method according to any of claims 1 to 12, wherein at least one of the plurality of RS configurations comprises at least two different types of RS.

14. The method according to claim 13, wherein one of the types of RS comprises one of: a demodulation reference signal, DM RS, a phase tracking reference signal, PTRS, a front loaded DM RS, a reference signal associated with DM RS, or a reference signal associated with PTRS.4115. A method performed by a network entity, the method comprising:transmitting, to a user equipment, UE, channel state information-reference signals, CSI-RS;receiving, from the UE, a CSI report comprising an indication of a first configuration related to at least one reference signal, RSs, for demodulating at least one physical channel from among a plurality of configurations related to at least one RS for demodulating at least one physical channel; andbased on the indication of the first configuration, selecting a second configuration from the plurality of configurations, for the UE to utilise to demodulate a physical channel transmission from the network entity to the UE.

16. The method according to claim 15, wherein the method further comprises:transmitting, to the UE, a second indication of the second configuration of the plurality of configurations, to be utilised by the UE for demodulating a downlink physical channel transmission.

17. The method according to claim 16, wherein one of:the second indication is transmitted in scheduling downlink control information; or the second indication comprises an indication of a first transmission configuration indication, TCI, state from a plurality of TCI states to be utilised for receiving the physical layer channel transmission from the network entity, wherein each of the plurality of TCI states is associated with one of the plurality of configurations related to at least one RS, wherein the first TCI state is associated with the second configuration.

18. The method according to any of claims 15 to 17, wherein the method further comprises:transmitting, to the UE, a configuration for CSI, wherein the configuration for CSI indicates that the UE is to report at least one RS configuration.

19. The method according to claim 18, wherein the configuration for CSI indicates that the UE is to report at least two configurations related to at least one RS, each of the at least two configurations being associated with different types of RS.

20. The method according to any of claims 15 to 19, where the method further comprises: transmitting, to the UE, at least one criterion for selection of the RS configuration.

21. The method according to claim 20, wherein the at least one criterion for selection indicates that throughput is to be utilised by the UE when selecting the configuration related to at least one RS.

22. The method according to any of claims 15 to 21 , wherein the method further comprises:transmitting, to the UE, an indication of the plurality of configurations, wherein each configuration of the plurality of configurations is associated with the information that is related to the parameter associated with CSI.

23. The method according to any of claims 15 to 22, wherein each of the plurality of configurations is associated with an index, wherein the indication of the first configuration comprised in the CSI report comprises an index of the first configuration.

24. The method according to any of claims 15 to 23, wherein at least one of the plurality of RS configurations comprises at least two different types of RS.

25. The method according to claim 24, wherein one of the types of RS comprises one of: a demodulation reference signal, DM RS, a phase tracking reference signal, PTRS, a front loaded DM RS, a reference signal associated with DM RS, or a reference signal associated with PTRS.

26. The method according to any of claims 15 to 25, wherein the selecting of the second configuration is further based on at least one of the following: a traffic load, or at least one service requirement.

27. A user equipment, UE, comprising: at least one processor, and at least one memory storing instructions that, when executed by the at least one processor, cause the UE to perform the method of any of claims 1 to 14.

28. A network entity comprising: at least one processor, and at least one memory storing instructions that, when executed by the at least one processor, cause the network entity to perform the method of any of claims 15 to 26.

29. A user equipment comprising one or more means for performing the method of any of claim 1 to 14.

30. A network entity comprising one or more means for performing the method of any of claim 15 to 26.

31. A computer program comprising instructions, which when executed by a user equipment, cause the user equipment to perform the method of any of claims 1 to 14.

32. A computer program comprising instructions, which when executed by a network entity, cause the network entity to perform the method of any of claims 15 to 26.

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