Channel measurement for uplink transmission

A method performed by a base station for measuring a channel state information reference signal (CSI-RS) for non-codebook based uplink (UL) transmission. The method includes transmitting information relating to a sounding reference signal (SRS) resource set for the non-codebook based UL transmission, information relating to a CSI-RS resource, a CSI-RS over the CSI-RS resource, and information relating to CSI-RS measurement restriction for measurement of the CSI-RS according to the CSI-RS measurement restriction. The measurement is for determining precoding information for the SRS resource set. The method includes receiving the SRS resource set, measuring the SRS resource set, and determining one or more SRS resources within the SRS resource set to be used for precoding the UL transmission. The method further includes transmitting a downlink control information (DCI) that indicates the SRS resources within the SRS resource set to be used for precoding the UL transmission, and receiving the UL transmission.

TECHNICAL FIELD

Embodiments of the present disclosure relate to the field of network communications, and in particular, to a method and an apparatus for measuring channel state information reference signal (CSI-RS).

BACKGROUND

In wireless communications, channel state information (CSI) refers to known channel properties of a communication link. This information describes how a signal propagates from the transmitter to the receiver and represents the combined effect of, for example, scattering, fading, and power decay with distance. CSI-RS is used by the user equipment (UE) to estimate the channel and report channel quality information (CQI) to the base station.

SUMMARY

A first aspect relates to a method performed by a base station for measuring a channel state information reference signal (CSI-RS) for non-codebook based uplink (UL) transmission. The method includes transmitting information relating to a sounding reference signal (SRS) resource set for the non-codebook based UL transmission, information relating to a CSI-RS resource, a CSI-RS over the CSI-RS resource, and information relating to CSI-RS measurement restriction for measurement of the CSI-RS according to the CSI-RS measurement restriction. The measurement is for determining precoding information for the SRS resource set. The method also includes receiving the SRS resource set, measuring the SRS resource set, and determining one or more SRS resources within the SRS resource set to be used for precoding the non-codebook based UL transmission. The method further includes transmitting a downlink control information (DCI) that indicates the SRS resources within the SRS resource set to be used for precoding the non-codebook based UL transmission, and receiving the non-codebook based UL transmission.

A second aspect relates to a method performed by a user equipment (UE) for measuring a channel state information reference signal (CSI-RS) for non-codebook based uplink (UL) transmission. The method includes receiving information relating to a sounding reference signal (SRS) resource set for the non-codebook based UL transmission, information relating to a CSI-RS resource, and information relating to CSI-RS measurement restriction. The method also includes measuring the CSI-RS resource based on the information relating to the CSI-RS measurement restriction, and determining precoding information for the SRS resource set based on the measurement of the CSI-RS resource. The method further includes transmitting the SRS resource set precoded based on the precoding information for the SRS resource set, receiving a downlink control information (DCI) that indicates the SRS resources within the SRS resource set to be used for the non-codebook based UL transmission, and transmitting the non-codebook based UL transmission.

In a first implementation form of the method according to either the first aspect or the second aspect as such, the CSI-RS measurement restriction specifies that the CSI-RS resource associated with the SRS resource set for the non-codebook based UL transmission that is to be measured occurs at least a first time before scheduling a transmission of the SRS resource set.

In a second implementation form of the method according to either the first aspect or the second aspect as such, the CSI-RS measurement restriction specifies that the CSI-RS resource associated with the SRS resource set for the non-codebook based UL transmission that is to be measured occurs at a first instance after the message that triggers a transmission of the SRS resource set.

In a third implementation form of the method according to either the first aspect or the second aspect as such, the CSI-RS measurement restriction specifies that the CSI-RS resource associated with the SRS resource set for the non-codebook based UL transmission that is to be measured occurs at a latest instance before the message that triggers a transmission of the SRS resource set.

In a fourth implementation form of the method according to either the first aspect or the second aspect as such, the CSI-RS measurement restriction specifies that the CSI-RS resource associated with the SRS resource set for the non-codebook based UL transmission that is measured is one or more CSI-RS resources associated with the SRS resource set for the non-codebook based UL transmission that occurs between a latest instance before the message that triggers a transmission of the SRS resource set and a first time before scheduling a transmission of the SRS resource set.

In a fifth implementation form of the method according to either the first aspect or the second aspect as such or any preceding implementation form of either the first aspect or the second aspect, the information relating to CSI-RS measurement restriction is transmitted in a first radio resource control (RRC) message, and an indication for measurement restriction for the UE's channel quality indicator (CQI) and channel state information (CSI) measurements is transmitted in a second RRC message.

In a sixth implementation form of the method according to either the first aspect or the second aspect as such or any preceding implementation form of either the first aspect or the second aspect, the information relating to CSI-RS measurement restriction is applied to a periodic channel state information reference signal (P-CSI-RS) resource that is associated with the SRS resource set.

In a seventh implementation form of the method according to either the first aspect or the second aspect as such or any preceding implementation form of either the first aspect or the second aspect, the information relating to CSI-RS measurement restriction is applied to a semi-periodic channel state information reference signal (SP-CSI-RS) resource that is associated with the SRS resource set.

In an eighth implementation form of the method according to either the first aspect or the second aspect as such or any preceding implementation form of either the first aspect or the second aspect, the information relating to CSI-RS measurement restriction is transmitted in a radio resource control (RRC) message.

In an eighth implementation form of the method according to the eighth implementation form of either the first aspect or the second aspect, the RRC message further comprises an indication for measurement restriction for the UE's CQI/CSI measurement.

A third aspect relates to a method performed by a UE for measuring a CSI-RS for non-codebook based UL transmission. The method receives information relating to a SRS resource set for the non-codebook based UL transmission and a CSI-RS resource associated with the SRS resource set, a request for a transmission of the SRS resource set, and the CSI-RS resource. The method determines precoding information for the SRS resource set based on a measurement of the CSI-RS resource in accordance with a specific instance of a CSI-RS resource specified for a downlink channel measurement. The method transmits the SRS resource set precoded based on the precoding information for the SRS resource set. The method receives a DCI that indicates the SRS resources within the SRS resource set to be used for the non-codebook based UL transmission. The method transmits an uplink frame using the precoding information applied to the indicated SRS resources within the SRS resource set.

In a first implementation form of the method according to the third aspect as such, the method further determines whether the UE is configured with a higher layer parameter used by the gNB for specifying the measurement restriction for CQI measurement. If the UE is not configured with the higher layer parameter, the method derives channel measurements for computing a CQI value reported in uplink slot n based on only a non-zero power (NZP) CSI-RS, no later than a CSI reference resource, associated with a CSI resource setting; and derives channel measurements for computing precoder for the SRS resource set scheduled in uplink slot n based on only the CSI-RS associated with the SRS resource set. If the UE is configured with the higher layer parameter, the method derives the channel measurements for computing the CQI value reported in the uplink slot n based on only a most recent, no later than the CSI reference resource, occasion of the NZP CSI-RS associated with the CSI resource setting; and derives the channel measurements for computing precoder for the SRS resource set scheduled in the uplink slot n based on only a latest CSI-RS resource associated with the SRS resource set that ends prior to 42 symbols before the SRS resource set is transmitted.

In a second implementation form of the method according to the third aspect as such, the method further determines whether the UE is configured with a higher layer parameter used by the gNB for specifying the measurement restriction for CQI measurement. If the UE is not configured with the higher layer parameter, the method derives channel measurements for computing a channel quality indicator (CQI) value reported in uplink slot n based on only a non-zero power (NZP) CSI-RS, no later than a CSI reference resource, associated with a CSI resource setting; and derives channel measurements for computing precoder for the SRS resource set scheduled in uplink slot n based on only the CSI-RS associated with the SRS resource set. If the UE is configured with the higher layer parameter, the method derives the channel measurements for computing the CQI value reported in the uplink slot n based on only a most recent, no later than the CSI reference resource, occasion of the NZP CSI-RS associated with the CSI resource setting; and derives the channel measurements for computing precoder for the SRS resource set scheduled in the uplink slot n based on only a first CSI-RS resource associated with the SRS resource set after an indication of dynamic SRS transmission request.

In a third implementation form of the method according to the third aspect as such, the method further determines whether the UE is configured with a higher layer parameter used by the gNB for specifying the measurement restriction for CQI measurement. If the UE is not configured with the higher layer parameter, the method derives channel measurements for computing a channel quality indicator (CQI) value reported in uplink slot n based on only a non-zero power (NZP) CSI-RS, no later than a CSI reference resource, associated with a CSI resource setting; and derives channel measurements for computing precoder for the SRS resource set scheduled in uplink slot n based on only the CSI-RS, no later than the CSI reference resource, associated with the SRS resource set. If the UE is configured with the higher layer parameter, the method derives the channel measurements for computing the CQI value reported in the uplink slot n based on only a most recent, no later than the CSI reference resource, occasion of the NZP CSI-RS associated with the CSI resource setting; and derives the channel measurements for computing precoder for the SRS resource set scheduled in the uplink slot n based on only a most recent, no later than the CSI reference resource, occasion of the CSI-RS resource associated with the SRS resource set.

In a fourth implementation form of the method according to the third aspect as such or any preceding implementation form of the third aspect, the higher layer parameter is a MeasRestrictionConfig-time-channel parameter.

A fourth aspect relates to a method performed by a UE for measuring a CSI-RS for non-codebook based UL transmission. The method receives information relating to a SRS resource set for the non-codebook based UL transmission and a CSI-RS resource associated with the SRS resource set. The method determines that information relating to CSI-RS measurement restriction is not received from a base station. The method receives a message that indicates a request for a SRS resource set transmission. The method determines precoding information for the SRS resource set based on a measurement of the CSI-RS resource based on unrestricted observation interval in time. The method transmits the SRS resource set precoded based on the precoding information for the SRS resource set. The method receives a downlink control information (DCI) that indicates the SRS resources within the SRS resource set to be used for uplink transmission. The method transmits an uplink frame based on the precoding information applied to the indicated SRS resources within the SRS resource set.

A fifth aspect relates to an apparatus comprising at least a processor and memory specially configured to perform any of the preceding aspects as such or any preceding implementation form of any of the preceding aspects.

Advantages of the preceding aspects and corresponding implementations include enabling a more accurate measurement of CSI-RS by a UE for calculating precoder of a SRS resource set for non-codebook based UL transmission. Another advantage is that a base station can adjust beams for CSI-RS adaptively and indicate to a UE to measure the CSI-RS properly for the non-codebook based UL transmission.

Details of the above aspects and other aspects, and additional advantages thereof, are further described in the detailed description.

The illustrated figures are only exemplary and are not intended to assert or imply any limitation with regard to the environment, architecture, design, or process in which different embodiments may be implemented. Any optional component or steps are indicated using dash lines in the illustrated figures.

DETAILED DESCRIPTION

The present disclosure provides various embodiments for measuring CSI-RS for calculating precoder of a SRS resource set for non-codebook based UL transmission. Advantages of the disclosed embodiments include a more accurate measurement of CSI-RS by a UE for calculating precoder of a SRS resource set for non-codebook based UL transmission. Another advantage is that a base station such as a fifth generation (5G) nodeB (gNB) can adjust beams for CSI-RS adaptively and indicate UE to measure the CSI-RS properly for non-codebook based UL transmission.

FIG. 1is a sequence diagram illustrating a generic operation procedure between a UE100and base station130for non-codebook based UL transmission. In an embodiment, the base station130is a gNB. UE100is any type of UE that is capable of communicating with the base station130. In an embodiment, the base station130is a fifth generation (5G) base station. However, it is foreseeable that the disclosed embodiments can apply to other generations of a base station.

In the depicted embodiment, the base station130, at step102, transmits information relating to a SRS resource set for non-codebook based UL transmission to the UE100. At step104, the base station130transmits information relating to a CSI-RS resource associated with the SRS resource set to the UE100. In some embodiments, the information relating to a SRS resource set for non-codebook based UL transmission (step102) and the information relating to a CSI-RS resource associated with the SRS resource set (step104) can be transmitted in one message or information element. At step106, the base station130transmits a message that indicates a request for a transmission of the SRS resource set to the UE100. At step108, the base station130transmits the CSI-RS resource. In some embodiments, the CSI-RS (step108) can be transmitted before, after, or both before and after, the transmission of the message that indicates a request for a transmission of the SRS resource set (step106).

After receiving the CSI-RS resource, the UE100, at step110, measures the CSI-RS resource. At step112, the UE100determines precoding information for the SRS resource set based on the measurement of the CSI-RS resource. The UE100, at step114, transmits the SRS resource set precoded based on the precoding information.

After receiving the SRS resource set precoded based on the precoding information from the UE100, the base station130, at step116, measures the SRS resource set. The base station130, at step118, determines SRS resources within the SRS resource set to be used for uplink transmission. The base station130, at step120, transmits a DCI that indicates the SRS resources to be used for UL transmission. The UE100, at step122, transmits an uplink frame using the precoding information applied to the indicated SRS resources within the SRS resource set.

As described inFIG. 1, for a UE100to determine precoding information for the SRS resource set (step112), the UE100measures an associated CSI-RS resource (step110). If a gNB triggers a transmission of an aperiodic CSI-RS (AP-CSI-RS) resource for non-codebook based UL transmission via a DCI field that triggers the SRS transmission, the AP-CSI-RS resource to be used for measurement can be clearly identified. A UE may receive the dynamic SRS transmission request for aperiodic SRS transmission in the same slot as the reception of the downlink (DL) CSI-RS resource (as illustrated inFIG. 2). As shown inFIG. 2, a DCI is sent in slot S0, and this DCI is the dynamic SRS transmission request for aperiodic SRS transmission. This DCI also indicates the AP-CSI-RS that is to be measured by the UE for estimating the channel. As shown, the AP-CSI-RS is transmitted in the same slot as the dynamic SRS transmission request (both are in slot S0). After measuring the AP-CSI-RS, the UE transmits the SRS at a designated slot (S4). In the depicted example, because the DCI specifically indicates the time for the AP-CSI-RS transmission, it is clear for the UE to figure out when and which resource to measure. In some embodiments, a UE is not expected to update the SRS precoding information if the gap from the last symbol of the reception of the AP-CSI-RS resource and the first symbol of the AP-SRS transmission is less than42orthogonal frequency-division multiplexing (OFDM) symbols.

However, if a periodic or semi-persistent CSI-RS (P/SP-CSI-RS) resource is associated for non-codebook based UL transmission, a UE does not know which CSI-RS resource to measure for calculating precoding information for the SRS resource set because there is a series of CSI-RS resource scheduled and transmitted, and the CSI-RS transmission can happen in a different slot from the slot that the DCI is transmitted (as illustrated inFIG. 3). As shown inFIG. 3, the DCI sent in slot S0that is the dynamic SRS transmission request for aperiodic SRS transmission is associated with P-CSI-RS. Each instance of P-CSI-RS resource happens periodically and it has been predefined even before the transmission of the DCI. In this particular example, the P-CSI-RS happens in every other slot. Thus, in this case, after receiving the DCI, there are multiple P-CSI-RS instances (S0/S2/S4), and therefore, the UE does not know which instance(s) of the P-CSI-RS that the UE needs to measure to determine the SRS transmission. Moreover, it is possible that the gNB may use different beam at different instance of P/SP-CSI-RS transmission, in which case, measurement on different instance of P/SP-CSI-RS may result in different precoding for SRS resource set.

Accordingly, the disclosed embodiments seek to provide solutions to one or more of the above described problems. In one embodiment, if there is more than one instance of CSI-RS resource associated with a SRS resource set for non-codebook based UL transmission, indicates whether a UE needs to measure a specific instance(s) of the CSI-RS resource (or not) for calculating precoding information of the SRS resource set. In some embodiments, if the gNB indicates that the UE needs to measure a specific instance(s) of the CSI-RS resource, the UE measures the specific CSI-RS for calculating precoding information of the SRS resource set. If the gNB indicates that the UE does not need to measure a specific instance(s) of the CSI-RS resource, the UE can determine how to utilize the measurement results of multiple instances of the CSI-RS resource for calculating precoding information of the SRS resource set.

FIG. 4is a sequence diagram illustrating a procedure between a UE100and base station130for non-codebook based UL transmission in accordance with an embodiment of the present disclosure. In the depicted embodiment, the base station130, at step402, transmits information relating to a SRS resource set for non-codebook based UL transmission to the UE100. At step404, the base station130transmits information relating to a CSI-RS resource associated with the SRS resource set to the UE100. In accordance with the disclosed embodiments, at step406, the base station130transmits information relating to CSI-RS measurement restriction. In some embodiments, the information relating to a SRS resource set for non-codebook based UL transmission (step402), the information relating to a CSI-RS resource associated with the SRS resource set (step404), and the information relating to CSI-RS measurement restriction (step406) can be transmitted in one message or information element. As stated above, this information indicates whether a UE needs to measure a specific instance or instance(s) of the CSI-RS resource for calculating precoding information of the SRS resource set, and if so, which instance or instances of the CSI-RS resource are to be measured. In one embodiment, if the base station130indicates that the UE does not need to measure a specific instance(s) of the CSI-RS resource, the UE can decide how to utilize the measurement results of multiple instances of the CSI-RS resource for calculating precoding information of the SRS resource set.

At step408, the base station130transmits a message that indicates a request for a transmission of the SRS resource set. In some embodiments, the message that indicates a request for a transmission of the SRS resource set can be a DCI, a radio resource control (RRC), and/or a medium access control with a control element (MAC CE) message. At step410, the UE100measures the CSI-RS resource(s) based on the information relating to CSI-RS measurement restriction. In some embodiments, the measurement of the CSI-RS resource(s) (step410) can be performed multiple times. The measurement of the CSI-RS resource(s) (step410) can also occur before the base station130transmits a message that indicates a request for a transmission of the SRS resource set (step408). In cases where the measurement of the CSI-RS resource(s) is performed multiple times, the measurement of the CSI-RS resource(s) (step410) can be performed both before and after the base station130transmits a message that indicates a request for a transmission of the SRS resource set (step408).

At step412, the UE100determines precoding information for the SRS resource set based on the measurement of the CSI-RS resource. At step414, the UE100transmits the SRS resource set precoded based on the precoding information. At step416, the base station130measures the SRS resource set. At step418, the base station130determines SRS resources within the SRS resource set to be used for UL transmission. At step420, the base station130transmits a DCI that indicates the SRS resources to be used for UL transmission. The UE100, at step422, transmits an uplink frame using the precoding information applied to the indicated SRS resources within the SRS resource set.

FIG. 5is a flowchart illustrating a method500for non-codebook based UL transmission performed by a gNB in accordance with an embodiment of the present disclosure. In the depicted embodiment, at step502, the method500transmits information relating to a SRS resource set for non-codebook based UL transmission and a CSI-RS resource associated with the SRS resource set to a UE. At step504, the method500transmits information relating to CSI-RS measurement restriction to the UE. At step506, the method500transmits a message that indicates a request for a transmission of the SRS resource set to the UE. As stated above, in some embodiments, the message can be a DCI, a RRC, and/or a MAC CE message.

At step508, the method500receives the SRS resource set precoded based on the precoding information from the UE. The method500, at step510, measures the SRS resource set, and determines SRS resources within the SRS resource set to be used for UL transmission. The method500, at step512, transmits a DCI that indicates the SRS resources to be used for UL transmission to the UE. At step514, the method500receives, from the UE, an uplink frame using the precoding information applied to the indicated SRS resources within the SRS resource set.

FIG. 6is a flowchart illustrating a method600for non-codebook based UL transmission performed by a UE in accordance with an embodiment of the present disclosure. In the depicted embodiment, at step602, the method600receives information relating to a SRS resource set for non-codebook based UL transmission and a CSI-RS resource associated with the SRS resource set from a gNB. At step604, the method600receives information relating to CSI-RS measurement restriction. The method600, at step606, receives a message, such as, but not limited to, a DCI, a RRC, and/or a MAC CE message that indicates a request for a transmission of the SRS resource set. At step608, the method600measures the CSI-RS resource based on the information relating to CSI-RS measurement restriction, and determines precoding information for the SRS. At step610, the method600transmits the SRS resource set precoded based on the precoding information. The method600, at step612, receives a DCI that indicates the SRS resources to be used for UL transmission. The method600, at step614, transmits an uplink frame using the precoding information applied to the indicated SRS resources within the SRS resource set.

FIGS. 7-11illustrate various specific instances that a gNB can indicate to a UE for calculating precoding information of the SRS resource set in accordance with the disclosed embodiments of the present disclosure. The depicted instances inFIGS. 7-11are just some examples and do not limit the scope of the disclosed embodiments. For example,FIG. 7is a schematic diagram illustrating a specific instance of a CSI-RS resource associated with a SRS resource set for non-codebook based UL transmission that happens at least a first time before the scheduled SRS resource set transmission in accordance with an embodiment of the present disclosure. As an example, the first time (T0) is set to 3 slots. In the disclosed examples, the number of OFDM symbols within a slot is 14, so 3 slots are 42 symbols. In the depicted embodiment, DCI is transmitted at slot #2(S2) and SRS transmission is scheduled at slot #5 (S5). P-CSI-RS at S2(circled) is the CSI-RS resource that occurs at least a first time before scheduled SRS resource set transmission (i.e., at least 3 slots before the SRS transmission). Therefore, in this example, P-CSI-RS at S2is used for measuring the CSI-RS resource to determine precoding information for the SRS.

FIG. 8is a schematic diagram illustrating a specific instance of a CSI-RS resource associated with a SRS resource set for non-codebook based UL transmission that happens a first instance after a DCI that triggers a transmission of the SRS resource set in accordance with an embodiment of the present disclosure. For example, in the depicted embodiment, DCI is transmitted at slot #2 (S2) and SRS transmission is scheduled at slot #5 (S5). P-CSI-RS at S2(circled) is the CSI-RS resource that occurs a first instance after a DCI that triggers a transmission of the SRS resource set. Therefore, in this example, P-CSI-RS at S2is used for measuring the CSI-RS resource to determine precoding information for the SRS.

FIG. 9is a schematic diagram illustrating a specific instance of a CSI-RS resource associated with a SRS resource set for non-codebook based UL transmission that happens the latest instance before a DCI that triggers a transmission of the SRS resource set in accordance with an embodiment of the present disclosure. In the depicted embodiment, DCI is transmitted at slot #2 (S2) and SRS transmission is scheduled at slot #5 (S5). P-CSI-RS at S1(circled) is the CSI-RS resource that occurs the latest instance before a DCI that triggers a transmission of the SRS resource set. Thus, for this specific instance, P-CSI-RS at S1is used for measuring the CSI-RS resource to determine precoding information for the SRS.

FIG. 10is a schematic diagram illustrating a specific instance of one or more CSI-RS resources associated with a SRS resource set for non-codebook based UL transmission that happen after a DCI that triggers a transmission of the SRS resource set and a first time before the scheduled SRS resource set transmission (i.e., requiring both conditions ofFIG. 7andFIG. 8) in accordance with an embodiment of the present disclosure. For example, in the depicted embodiment, the first time (T0) is set to 2 slots (28 symbols). DCI is transmitted at slot #2 (S2) and SRS transmission is scheduled at slot #5 (S5). Both P-CSI-RS at S2and at S3(circled) meet the conditions of occurring after a DCI that triggers a transmission of the SRS resource set and a first time before the scheduled SRS resource set transmission (i.e., before SRS transmission+2 slots (T0)). Therefore, for the illustrated example, both P-CSI-RS at S2and at S3are used for measuring the CSI-RS resource to determine precoding information for the SRS.

FIG. 11is a schematic diagram illustrating a specific instance of one or more CSI-RS resources associated with a SRS resource set for non-codebook based UL transmission that happen between the latest instance before a DCI that triggers a transmission of the SRS resource set and a first time before the scheduled SRS resource set transmission (i.e., combination of conditions ofFIG. 7andFIG. 9) in accordance with an embodiment of the present disclosure. For example, in the depicted embodiment, the first time (T0) is set to 3 slots (42 symbols). DCI is transmitted at slot #2 (S2) and SRS transmission is scheduled at slot #5 (S5). In this example, P-CSI-RS at S1(circled) is the latest instance before a DCI that triggers a transmission of the SRS resource set and S2(circled) occurs a first time before the scheduled SRS resource set transmission (i.e., SRS transmission+3 slots (T0)). Thus, in the illustrated example, both P-CSI-RS at S1and at S2are used for measuring the CSI-RS resource to determine precoding information for the SRS.

In accordance with the disclosed embodiments, the gNB can indicate the CSI-RS measurement restriction using various techniques such as, but not limited to, linking it to CQI measurement. For example, in some embodiments, the gNB can specify the CSI-RS measurement restriction by using a parameter that is used for indicating measurement restriction for CQI measurement for DL transmission. As an example, in some embodiments, the gNB can specify the CSI-RS measurement restriction by using the “MeasRestrictionConfig-time-chann” parameter that it is already being used for DL transmission. In one embodiment, if a gNB indicates that a UE needs to measure a specific instance of a CSI-RS resource for downlink channel measurement, the UE needs to measure another specific CSI-RS for calculating precoding information of a SRS resource set for non-codebook based UL transmission.

In various embodiments, the UE may or may not be configured with the higher layer parameter such as the MeasRestrictionConfig-time-channel parameter used by the gNB for specifying the measurement restriction for CQI measurement. Thus, in accordance with the some embodiments, the UE performs a determination to check whether it is configured with the higher layer parameter. The following examples provide various embodiments based on whether a UE is configured with the higher layer parameter used by the gNB for specifying the measurement restriction for CQI measurement.

In a first embodiment, if the UE determines that it is not configured with the higher layer parameter used by the gNB for specifying the measurement restriction for CQI measurement, the UE derives the channel measurements for computing CQI value reported in uplink slot n based on only the non-zero power (NZP) CSI-RS, no later than the CSI reference resource, associated with the CSI resource setting; and the UE derives the channel measurements for computing precoder for a SRS resource set scheduled in uplink slot n based on only the CSI-RS associated with the SRS resource set. However, if the UE determines that it is configured with the higher layer parameter used by the gNB for specifying the measurement restriction for CQI measurement, the UE derives the channel measurements for computing the CQI value reported in the uplink slot n based on only a most recent, no later than the CSI reference resource, occasion of the NZP CSI-RS associated with the CSI resource setting; and derives the channel measurements for computing precoder for the SRS resource set scheduled in the uplink slot n based on only a latest CSI-RS resource associated with the SRS resource set that ends prior to42symbols before the SRS resource set is transmitted.

In a second embodiment, if the UE determines that it is not configured with the higher layer parameter used by the gNB for specifying the measurement restriction for CQI measurement, the UE derives channel measurements for computing a CQI value reported in uplink slot n based on only a NZP CSI-RS, no later than a CSI reference resource, associated with a CSI resource setting; and derives channel measurements for computing precoder for the SRS resource set scheduled in uplink slot n based on only the CSI-RS associated with the SRS resource set. In the second embodiment, if the UE determines that it is configured with the higher layer parameter used by the gNB for specifying the measurement restriction for CQI measurement, the UE derives the channel measurements for computing the CQI value reported in the uplink slot n based on only a most recent, no later than the CSI reference resource, occasion of the NZP CSI-RS associated with the CSI resource setting; and derives the channel measurements for computing precoder for the SRS resource set scheduled in the uplink slot n based on only a first CSI-RS resource associated with the SRS resource set after an indication of dynamic SRS transmission request.

In a third embodiment, if the UE determines that it is not configured with the higher layer parameter used by the gNB for specifying the measurement restriction for CQI measurement, the UE derives channel measurements for computing a CQI value reported in uplink slot n based on only a NZP CSI-RS, no later than a CSI reference resource, associated with a CSI resource setting; and derives channel measurements for computing precoder for the SRS resource set scheduled in uplink slot n based on only the CSI-RS, no later than the CSI reference resource, associated with the SRS resource set. In the third embodiment, if the UE determines that it is configured with the higher layer parameter used by the gNB for specifying the measurement restriction for CQI measurement, the UE derives the channel measurements for computing CSI reported in uplink slot n based on only the most recent, no later than the CSI reference resource, occasion of NZP CSI-RS associated with the CSI resource setting; and derives the channel measurements for computing precoder for a SRS resource set scheduled in uplink slot n based on only the first CSI-RS resource associated with the SRS resource set after the indication of dynamic SRS transmission request.

Accordingly, the above written description provides various embodiments for enabling the measurement of a CSI-RS for non-codebook based UL transmission. For example, if there is more than one instance of CSI-RS resource associated with a SRS resource set for non-codebook based UL transmission, a gNB can indicate whether a UE needs to measure a specific instance(s) of the CSI-RS resource (or not) for calculating precoding information of the SRS resource set. In some embodiments, if the gNB indicates that the UE needs to measure a specific instance(s) of the CSI-RS resource, the UE measures the specific CSI-RS for calculating precoding information of a SRS resource set for non-codebook based UL transmission. If the gNB indicates that the UE does not need to measure a specific instance(s) of the CSI-RS resource, the UE determines how to utilize the measurement results of multiple instances of the CSI-RS resource for calculating precoding information of the SRS resource set as described above.

In any of the preceding embodiments, the following features/limitations may be further applied:

1. The gNB's indication of whether a UE needs to measure a specific instance(s) of the CSI-RS resource for calculating precoding information of the SRS resource set can be sent using a RRC message.

2. The gNB's indication can use the same RRC message with an indication for measurement restriction for the UE's CQI/CSI measurement.

3. The gNB's indication can be separate from the indication for measurement restriction for the UE's CQI/CSI measurement.

4. If the gNB does not deliver the indication, the UE can derive the precoding information based on unrestricted observation interval in time.

5. The gNB's indication is applied to P-CSI-RS resource.

6. The P-CSI-RS resource is associated with the SRS resource set.

7. The gNB's indication is applied to SP-CSI-RS resource.

8. The SP-CSI-RS resource is associated with the SRS resource set.

An advantage of the disclosed embodiments include being able to provide a more accurate measurement of CSI-RS by a UE for calculating precoder of a SRS resource set for non-codebook based UL transmission. Another advantage is that a gNB can adjust beams for CSI-RS adaptively and indicate to a UE to measure the CSI-RS properly for non-codebook based UL transmission.

FIG. 12is a schematic diagram of an example apparatus1200configured to implement one or more of the methods disclosed herein according to an embodiment of the disclosure. For example, the apparatus1200may represent a gNB or a UE that is configured to perform the methods described herein. The apparatus1200includes ingress ports1210and receiver units (Rx)1220for receiving data. The apparatus1200includes a processor, logic unit, or central processing unit (CPU)1230to process the data and execute various instructions. The apparatus1200includes transmitter units (Tx)1240and egress ports1250for transmitting data. The apparatus1200includes a memory1260for storing the data and executable instructions. The apparatus1200may also comprise optical-to-electrical (OE) components and electrical-to-optical (EO) components (not depicted) coupled to the ingress ports1210, the receiver units1220, the transmitter units1240, and the egress ports1250for converting optical signal to electrical signals, and vice versa.

The memory1260may include one or more disks, tape drives, or solid-state drives and may be used as an over-flow data storage device, to store programs when such programs are selected for execution, or to store instructions and data that are read during program execution. The memory1260may be volatile and/or non-volatile and may be read-only memory (ROM), random-access memory (RAM), ternary content-addressable memory (TCAM), or static random-access memory (SRAM).

The processor1230may be implemented by any suitable combination of hardware, middleware, firmware, and software. The processor1230may be implemented as one or more CPU chips, cores (e.g. as a multi-core processor), field-programmable gate arrays (FPGAs), application specific integrated circuits (ASICs), or digital signal processors (DSPs). The processor1230is in communication with the ingress ports1210, receiver units1220, transmitter units1240, egress ports1250, and memory1260.

In one embodiment, the memory1260may store a CSI-RS measurement module1270. The CSI-RS measurement module1270includes computer executable instructions for performing the steps of the various embodiments. The processor1230is configured to execute these instructions along with other instructions associated with the apparatus1200. In various embodiments, the apparatus1200can include additional or alternative components than those described inFIG. 12for implementing the various embodiments disclosed herein.