WO2020187392A1

WO2020187392A1 - Client device and network access node for measurement reporting based on differential values relative to a reference measurement

Info

Publication number: WO2020187392A1
Application number: PCT/EP2019/056604
Authority: WO
Inventors: Wenquan HU; Sha HU; Bengt Lindoff; Taimoor ABBAS
Original assignee: Huawei Technologies Co., Ltd.
Priority date: 2019-03-15
Filing date: 2019-03-15
Publication date: 2020-09-24

Abstract

The invention relates to measurement reporting for simultaneous multi beam transmission. A client device (100) is configured to obtain a set of measurements associated with a set of group-reference signal resources and determine a measurement in the set of measurements as a reference measurement. The client device (100) is further configured to provide a measurement report (510) for the set of group-reference signal resources to a network access node (300). In the measurement report (510), the measurements in the set of measurements except the reference measurement are indicated with two or more different types of differential values relative to a value of the reference measurement. Furthermore, the invention also relates to corresponding methods and a computer program.

Description

CLIENT DEVICE AND NETWORK ACCESS NODE FOR MEASUREMENT REPORTING BASED ON DIFFERENTIAL VALUES RELATIVE TO A REFERENCE MEASUREMENT

Technical Field

The invention relates to a client device and a network access node for measurement reporting in multi beam transmission. Furthermore, the invention also relates to corresponding methods and a computer program.

Background

In new radio (NR) release 15 a client device changing its beam link with the network in one cell does not require explicit radio resource control (RRC) signaling to be triggered. The network access node provides the client device with measurement configuration via RRC signaling that contains configurations of synchronization signal block (SSB) and/or channel state information (CSI) resources and resource sets, reports and trigger states for triggering channel and interference measurements and reports. Beam level mobility is then dealt with at lower layers by means of physical layer and medium access control (MAC) layer control signaling. Thus, RRC signaling is not required to know which beam is being used at a given point in time. For transmission configuration indicator (TCI) indication of physical downlink shared channel (PDSCH) in release 15, a single TCI state can be indicated to the client device. The client device can be configured with a list of up to M TCI state configurations within the higher layer parameter PDSCH-Config to decode PDSCH according to a detected PDCCH with downlink control information (DCI) intended for the client device and the given serving cell, where M depends on the capability of the client device. The client device receives an activation command used to map up to 8 TCI states to the codepoints (000,1 1 1 examples of code points) of the DCI field Transmission Configuration Indication'.

In NR release 15, the following multiple input multiple output (MIMO) features are included: limited support for multi transmission reception point (TRP) and/or panel operation, flexible CSI acquisition and beam management, Type I (low-resolution) and II (high-resolution) codebooks supporting up to 32 ports, and flexible reference signals (RSs) for MIMO transmission, especially CSI-RS, demodulation reference signals (DMRS), and sounding reference signals (SRS). One aspect that can be enhanced is to support multi TRP and/or panel transmission including improved reliability and robustness with both ideal and non-ideal backhaul. A design target is to specify in the downlink for an efficient support of a non-coherent joint transmission in multi TRP, panel, and/or beam scenario. Summary

An objective of embodiments of the invention is to provide a solution which mitigates or solves the drawbacks and problems of conventional solutions.

The above and further objectives are solved by the subject matter of the independent claims. Further advantageous embodiments of the invention can be found in the dependent claims.

According to a first aspect of the invention, the above mentioned and other objectives are achieved with a client device for a wireless communication system, the client device being configured to

obtain a set of measurements associated with a set of group-reference signal resources; determine a measurement in the set of measurements as a reference measurement; provide a measurement report for the set of group-reference signal resources, wherein the measurements in the set of measurements except the reference measurement are indicated with two or more different types of differential values relative to a value of the reference measurement in the measurement report.

The set of group-reference signal resources relates to a set of paired or grouped reference signals. Reference signals in each paired or grouped reference signals are transmitted from the network side simultaneously.

An advantage of the client device according to the first aspect is that with the use of two or more different types of differential values less control information overhead is needed and hence frequency resource utilization is improved in the system.

In an implementation form of a client device according to the first aspect, a measurement in each group-reference signal resources is indicated with a first type of differential value relative to the value of the reference measurement, and wherein any other measurement in each group-reference signal resources is indicated with a second type of differential value relative to a value indicated by a first type of differential value.

An advantage with this implementation form is that different measurement ranges and indication granularities can be applied on the two different types of differential values, respectively, which reduces control information overhead in the system. In an implementation form of a client device according to the first aspect, the first type of differential value is given by a first number of bits in a first step size, and wherein the second type of differential value is given by a second number of bits in a second step size.

An advantage with this implementation form is that different measurement ranges, i.e. step sizes, and indication granularities, i.e. number of bits, can be applied to reduce control information overhead.

In an implementation form of a client device according to the first aspect, the first number of bits is larger than the second number of bits.

An advantage with this implementation form is that a larger measurement range can be covered by the first type of differential value given the same indication granularity of the two different types of differential values.

In an implementation form of a client device according to the first aspect, the first step size is larger than the second step size.

An advantage with this implementation form is that a finer granularity can be covered by the second type of differential value thereby provide more accurate measurements.

In an implementation form of a client device according to the first aspect, determine the reference measurement comprises

determine a measurement representing the highest quality among the set of measurements as the reference measurement.

The highest quality can e.g. relate to a strongest received signal power strength, the largest SINR measurement, or any other suitable signal quality metric.

An advantage with this implementation form is that the with the use of the highest quality as the reference measurement more robust measurement reports can be provided since the reference measurement is independent.

In an implementation form of a client device according to the first aspect, the reference measurement is indicated with an absolute value. An advantage with this implementation form is that the absolute value can be derived independently of any other values.

In an implementation form of a client device according to the first aspect, the group-reference signal resources are paired reference signal resources.

This implementation form therefore relates to the case when the measurements relates to beam pairs.

An advantage with this implementation form is that the measurement report according to this implementation form suits multi-beam data transmission with paired beams.

In an implementation form of a client device according to the first aspect, the set of measurements comprises signal to interference and noise ratio, SINR measurements or received signal received power, RSRP, measurements.

An advantage with this implementation form is that these measurement quantities are easy to obtain in the physical layer of the client device by reusing existing measurement quantities hence to reduce specification complexity.

In an implementation form of a client device according to the first aspect, the set of measurements is a set of channel state information, CSI, measurements and the measurement report is a CSI report.

An advantage with this implementation form is that these CSI reports can be applied for matched data scheduling.

In an implementation form of a client device according to the first aspect, the client device is further configured to

use the CSI report in L1 -SINR or in L1 -RSRP reporting.

An advantage with this implementation form is that less changes in the current NR specifications is needed by extending the existing reporting procedure in NR.

transmit the measurement report to a network access node. An advantage with this implementation form is that the network can configure a set of matched scheduling parameters for data transmission to the client device with measurement reports according to embodiments of the invention.

According to a second aspect of the invention, the above mentioned and other objectives are achieved with a network access node for a wireless communication system, the network access node being configured to

receive a measurement report for set of measurements associated with a set of group- reference signal resources from a client device, wherein the measurements in the set of measurements except a reference measurement are indicated with two or more different types of differential values relative to a value of the reference measurement in the measurement report;

obtain the measurements in the set of measurements except the reference measurement based on the two or more different types of differential values and the reference measurement.

An advantage of the network access node according to the second aspect is that the network can obtain downlink channel information in a more resource efficient way compared to conventional solutions by receiving a measurement report according to embodiments of the invention.

In an implementation form of a network access node according to the second aspect, the network access node is further configured to

configure a set of group-reference signal resources for the client device based on a previous measurement report received previously to the reception of the measurement report, wherein the previous measurement report indicates measurements associated with a set of reference signal resources or a set of group-reference signal resources for the client device; transmit a set of group-reference signals to the client device according to the configured set of group-reference signal resources.

An advantage with this implementation form is that a multi-level CSI measurement can be performed to reduce measurement load at the client device and at the same time reduce needed reference signal resources used by the network.

According to a third aspect of the invention, the above mentioned and other objectives are achieved with a method for a client device, the method comprises obtaining a set of measurements associated with a set of group-reference signal resources;

determining a measurement in the set of measurements as a reference measurement; provide a measurement report for the set of group-reference signal resources, wherein the measurements in the set of measurements except the reference measurement are indicated with two or more different types of differential values relative to a value of the reference measurement in the measurement report.

The method according to the third aspect can be extended into implementation forms corresponding to the implementation forms of the client device according to the first aspect. Hence, an implementation form of the method comprises the feature(s) of the corresponding implementation form of the client device.

The advantages of the methods according to the third aspect are the same as those for the corresponding implementation forms of the client device according to the first aspect.

According to a fourth aspect of the invention, the above mentioned and other objectives are achieved with a method for a network access node, the method comprises

receiving a measurement report for set of measurements associated with a set of group- reference signal resources from a client device, wherein the measurements in the set of measurements except a reference measurement are indicated with two or more different types of differential values relative to a value of the reference measurement in the measurement report;

obtaining the measurements in the set of measurements except the reference measurement based on the two or more different types of differential values and the reference measurement.

The method according to the fourth aspect can be extended into implementation forms corresponding to the implementation forms of the network access node according to the second aspect. Hence, an implementation form of the method comprises the feature(s) of the corresponding implementation form of the network access node.

The advantages of the methods according to the fourth aspect are the same as those for the corresponding implementation forms of the network access node according to the second aspect. The invention also relates to a computer program, characterized in program code, which when run by at least one processor causes said at least one processor to execute any method according to embodiments of the invention. Further, the invention also relates to a computer program product comprising a computer readable medium and said mentioned computer program, wherein said computer program is included in the computer readable medium, and comprises of one or more from the group: ROM (Read-Only Memory), PROM (Programmable ROM), EPROM (Erasable PROM), Flash memory, EEPROM (Electrically EPROM) and hard disk drive.

Further applications and advantages of the embodiments of the invention will be apparent from the following detailed description.

Brief Description of the Drawings

The appended drawings are intended to clarify and explain different embodiments of the invention, in which:

- Fig. 1 shows a client device according to an embodiment of the invention;

- Fig. 2 shows a method for a client device according to an embodiment of the invention;

- Fig. 3 shows a network access node according to an embodiment of the invention;

- Fig. 4 shows a method for a network access node according to an embodiment of the invention;

- Fig. 5 shows a wireless communication system according to an embodiment of the invention;

- Fig. 6a shows multi beam transmission from a single TRP;

- Fig. 6b shows multi beam transmission from two TRPs;

- Fig. 7 shows a flow chart of a two-stage beam selection method according to an embodiment of the invention;

- Fig. 8 shows a first stage and a second stage of a two-stage beam selection method according to an embodiment of the invention;

- Fig. 9 shows a flow chart of a two-stage beam selection method according to an embodiment of the invention; and

- Fig. 10 shows a first stage and a second stage of a two-stage beam selection method according to an embodiment of the invention.

Detailed Description

For simultaneous multi beam transmission in NR, one task is to configure compatible beam pairs for a client device in which each beam pair at least satisfies simultaneous reception at the client device and yields acceptable inter-beam interference. From system performance point of view, overhead in CSI resources transmission and CSI reporting should be taken into account and hence there is a need for efficient CSI-RS/SSB transmission and CSI reporting for simultaneous multi beam transmissions. Therefore, embodiments of the invention introduce an efficient solution for CSI reporting to support simultaneous multi beam transmission not limited to but applicable in NR systems. For example, embodiments of the invention can be introduced in L1 -RSRP and/or L1 -SINR reporting for multi-TRP/panel transmission in NR.

Fig. 1 shows a client device 100 according to an embodiment of the invention. In the embodiment shown in Fig. 1 , the client device 100 comprises a processor 102, a transceiver 104 and a memory 106. The processor 102 is coupled to the transceiver 104 and the memory 106 by communication means 108 known in the art. The client device 100 further comprises an antenna or antenna array 1 10 coupled to the transceiver 104, which means that the client device 100 is configured for wireless communications in a wireless communication system.

That the client device 100 is configured to perform certain actions can in this disclosure be understood to mean that the client device 100 comprises suitable means, such as e.g. the processor 102 and the transceiver 104, configured to perform said actions.

According to embodiments of the invention the client device 100 is configured to obtain a set of measurements associated with a set of group-reference signal resources and to determine a measurement in the set of measurements as a reference measurement. The client device 100 is further configured to provide a measurement report 510 for the set of group-reference signal resources. The measurements in the set of measurements except the reference measurement are indicated with two or more different types of differential values relative to a value of the reference measurement in the measurement report 510.

Fig. 2 shows a flow chart of a corresponding method 200 which may be executed in a client device 100, such as the one shown in Fig. 1 . The method 200 comprises obtaining 202 a set of measurements associated with a set of group-reference signal resources and determining 204 a measurement in the set of measurements as a reference measurement. The method 200 further comprises providing 206 a measurement report 510 for the set of group-reference signal resources. The measurements in the set of measurements except the reference measurement are indicated with two or more different types of differential values relative to a value of the reference measurement in the measurement report 510.

Fig. 3 shows a network access node 300 according to an embodiment of the invention. In the embodiment shown in Fig. 3, the network access node 300 comprises a processor 302, a transceiver 304 and a memory 306. The processor 302 is coupled to the transceiver 304 and the memory 306 by communication means 308 known in the art. The network access node 300 may be configured for both wireless and wired communications in wireless and wired communication systems, respectively. The wireless communication capability is provided with an antenna or antenna array 310 coupled to the transceiver 304, while the wired communication capability is provided with a wired communication interface 312 coupled to the transceiver 304.

That the network access node 300 is configured to perform certain actions can in this disclosure be understood to mean that the network access node 300 comprises suitable means, such as e.g. the processor 302 and the transceiver 304, configured to perform said actions.

According to embodiments of the invention the network access node 300 is configured to receive a measurement report 510 for set of measurements associated with a set of group- reference signal resources from a client device 100. The measurements in the set of measurements except a reference measurement are indicated with two or more different types of differential values relative to a value of the reference measurement in the measurement report 510. The network access node 300 is further configured to obtain the measurements in the set of measurements except the reference measurement based on the two or more different types of differential values and the reference measurement.

Fig. 4 shows a flow chart of a corresponding method 400 which may be executed in a network access node 300, such as the one shown in Fig. 3. The method 400 comprises receiving 402 a measurement report 510 for set of measurements associated with a set of group-reference signal resources from a client device 100. The measurements in the set of measurements except a reference measurement are indicated with two or more different types of differential values relative to a value of the reference measurement in the measurement report 510. The method 400 further comprises obtaining 404 the measurements in the set of measurements except the reference measurement based on the two or more different types of differential values and the reference measurement.

Fig. 5 shows a wireless communication system 500 according to an embodiment of the invention. The wireless communication system 500 comprises a client device 100 and a network access node 300 configured to operate in the wireless communication system 500. For simplicity, the wireless communication system 500 shown in Fig. 5 only comprises one client device 100 and one network access node 300. However, the wireless communication system 500 may comprise any number of client devices 100 and any number of network access nodes 300 without deviating from the scope of the invention.

In the embodiment shown in Fig. 5, a client device 100 transmits a measurement report 510 to a network access node 300. The measurement report 510 comprises a set of measurements associated with a set of group-reference signal resources. In embodiments, the group- reference signal resources are paired reference signal resources. However, in alternative embodiments, the group-reference signal resources may instead comprise reference signal resources grouped in other ways than in pairs, e.g. in triples or quadruples of beams or corresponding reference signal resources. The client device 100 may be configured by the network access node 300 with the set of group-reference signal resources and hence obtain the set of measurements associated with the set of group-reference signal resources based on the set of group-reference signal resources configured and transmitted by the network access node 300.

The set of measurements may comprise signal to interference and noise ratio (SINR) measurements, received signal received power (RSRP) measurements, or any other suitable quality metric. Thus, the set of measurements may be a set of channel state information (CSI) measurements and the measurement report 510 may a CSI report. In embodiments, the client device 100 may use the CSI report in L1 -SINR or in L1 -RSRP reporting to the network access node 300.

From the set of measurements, the client device 100 determines a reference measurement. In embodiments, the client device 100 may determine one measurement representing the highest quality among the set of measurements as the reference measurement. In the measurement report 510, the reference measurement may be indicated with an absolute value. The measurements in the set of measurements except the reference measurement on the other hand are indicated with two or more different types of differential values relative to the value of the reference measurement. In other words, the measurement report 510 is based on a dual differential indication structure, leading to a matrix-like measurement report in embodiments.

According to embodiments of the invention, a measurement in each group-reference signal resources is indicated with a first type of differential value relative to the value of the reference measurement, and any other measurement in each group-reference signal resources is indicated with a second type of differential value relative to a value indicated by a first type of differential value. The first type of differential value may be given by a first number of bits in a first step size, and the second type of differential value may be given by a second number of bits in a second step size. The first number of bits may be larger than the second number of bits. Furthermore, the first step size may be larger than the second step size. In this way, the measurement report 510 can comprise different value range and accuracy in the horizontal direction compared to vertical direction in matrix form.

When the network access node 300 receives the measurement report 510 for the set of measurements associated with the set of group-reference signal resources from the client device 100, the network access node 300 can obtain the measurements in the set of measurements except the reference measurement based on the two or more different types of differential values and the reference measurement. In embodiments where the reference measurement is indicated with an absolute value and the other measurements are indicated with the first type of differential value or the second type of differential value, the network access node 300 uses the first type of differential values and the absolute value of the reference measurement to derive the first type of absolute values. Furthermore, the network access node 300 uses the second type of differential values and the absolute value of the reference measurement together with the first type of differential values to derive the second type of absolute values. The measurement report 510 can be in bit form and hence the network access node 300 can use a defined mapping table for deriving the measurement values indicated by the measurement report 510.

In embodiments, the network access node 300 configures a set of group-reference signal resources for the client device 100 based on a previous measurement report 510^' received previously to the reception of the measurement report 510. The previous measurement report 510^' indicates measurements associated with a set of reference signal resources or a set of group-reference signal resources for the client device 100, as will be described below with reference to Figs. 7-10. The network access node 300 further transmits a set of group- reference signals to the client device 100 according to the configured set of group-reference signal resources.

Further details related to the measurement report 510 will now be described in an embodiment where the client device 100 receives two physical downlink shared channels (PDSCHs) through two different beams, i.e. PDSCH 1 and PDSCH2. The two PDSCHs may be transmitted to the client device 100 from a single TRP with multi panels, as shown in Fig. 6a. Alternatively, the two PDSCHs may be transmitted to the client device 100 from two different TRPs, as shown in Fig. 6b. In a first column of a measurement report 510 candidate beams can be reported, which would have larger value range and coarser accuracy compared with measurement values in the horizontal direction. Table 1 shows the information structure of the measurement report 510 according to an embodiment where the reporting quantity is L1-RSRP or L1-SINR and where the group-reference signal resources are paired reference signal resources. Values in the first column in table 1 are based on the first type of differential value, i.e. are relative to the value of the reference measurement. Values in each row are based on the second type of differential value, i.e. are relative to the value indicated by the first type of differential value. Furthermore, the first number of bits is Y and the first step size is P, while the second number of bits is Y and the second step size Q in T able 1.

Table 1 : Paired reference signal (RS) L1 reports, e.g. L1-RSRP or L1-SINR in NR. The measurement report 510 can be used in a two-stage beam selection procedure to select suitable paired beams for the client device 100. The two-stage beam selection procedure can achieve a balance between CSI-RS overhead and corresponding measurement load on the client device 100. A basic requirement for paired multi beams is that each beam link should have strong enough RSRP for transmission on its own. Among the beams that have strong enough RSRPs, compatible paired beams can be selected for which there are not strong interferences from other paired beams. In a first stage of the two-stage beam selection procedure, CSI measurements are performed and candidate paired beams are reported, considering that in a multi beam transmission, all the activated beams for simultaneous multi beam transmission should be received at the client device 100 in a single spatial domain receive filter, or with multiple simultaneous spatial domain receive filters. In a second stage of the two-stage beam selection procedure, advanced CSI measurements are performed to check the interference condition for the candidate paired beams and further select suitable paired beams among the candidate paired beams for multi beam transmission.

Fig. 7 shows a flow chart of a two-stage beam selection method 700 according to an embodiment of the invention. The two-stage beam selection method 700 can be performed in a client device 100 such as the one in Fig. 1 . Step 702 and 704 corresponds to the first stage of the two-stage beam selection method 700. In step 702, the client device 100 is configured with a set of CSI resources from multiple panels or TRPs and with a CSI measurement report configuration by the network access node 300 or by a network schedular (not shown) of the network. Based on the configuration in step 702, the client device 100 measures the set of CSI resources and provides a first stage measurement report S1 -510 in step 704 to the network access node 300. The first stage measurement report S1 -510 provided in step 704 may comprise the paired beams which are strong enough for transmission and may e.g. report L1 - RSRP values of the paired beams as differential values. The first stage measurement report S1 -510 may correspond to the above-mentioned previous measurement report 510^', when the previous measurement report 510^' indicates measurements associated with a set of group- reference signal resources for the client device 100.

Step 706 and 708 corresponds to the second stage of the two-stage beam selection method 700. In step 706, the client device 100 is configured with another set of CSI resources from multiple panels or TRPs and with another measurement report configuration by the network access node 300. Based on the configuration in step 706, the client device 100 measures and provides a second stage measurement report S2-510 in step 708 to the network access node 300. The second stage measurement report S2-510 provided in step 708 may comprise the paired beam for which there are not strong interferences from other paired beams and may e.g. report L1 -SINR values of the paired beams as differential values.

Fig. 8 shows the first stage S1 and the second stage S2 of the two-stage beam selection method 700 according to an embodiment. In the embodiment shown in Fig. 8, the client device 100 is in the first stage S1 configured to measure the L1 -RSRP of three beams numbered #1 , #2, #3 from a first TRP (i.e. TRP1 ) and three beams numbered #4, #5, #6 from a second TRP (i.e. TRP2). In the first stage reporting of the two-stage beam selection method 700, the client device 100 provides the first stage measurement report S1 -510 comprising the strong enough paired beams to the network access node 300. In Fig. 8 it is assumed that the paired beams in vectors (#2, #3), (#2, #5) and (#3, #5) which together form a report matrix are strong enough for data transmission. Hence, the first stage measurement report S1 -510 comprises the L1 - RSRP values of the (#2, #3), (#2, #5) and (#3, #5) beam pairs, as shown in Fig. 8. The L1 - RSRP values are reported as differential values, as previously described.

Based on the first stage measurement report S1 -510, the network access node 300 can in the second stage S2 configure a set of group-reference signal resources for the client device 100 upon which the client device 100 can perform and report advanced CSI measurements. Thereby, suitable paired beams can be selected from the list of paired beams reported in the first stage S1. The network access node 300 may e.g. configure the client device 100 to measure and report L1 -SINR of the paired beams reported in the first stage S1 . The network access node 300 transmits group-reference signals to the client device 100 according to the configured set of group-reference signal resources in the second stage S2, as shown in Fig. 8. In the second stage reporting, the client device 100 provides the second stage measurement report S2-510 to the network access node 300. The second stage measurement report S2- 510 comprises the L1 -SINR values of suitable paired beams, e.g. paired beams forwhich there are not strong interferences from other paired beams. In Fig. 8 it is assumed that the paired beams (#2, #3) and (#3, #5) does not experience strong interferences from other paired beams. Hence, the second stage measurement report S2-510 comprises the L1 -SINR values of the paired beams (#2, #3) and (#3, #5), as shown in Fig. 8. The L1 -SINR values are reported as differential values, as previously described.

The values in the first stage measurement report S1 -510 and the second stage measurement report S2-510 shown in Fig. 8 are based on the following assumptions: firstly, that the L1 - RSRP value for beam #2 is -70 dBm, for beam #3 -72 dBm, and for beam #5 -69 dBm, and that the measurement of beam #2 is determined to be the reference measurement in this example. Secondly, that the L1 -SINR values for the paired beams (#2, #3) are (10 dB, 9 dB), and the L1 -SINR values for the paired beams (#3, #5) are (8 dB, 9 dB).

Furthermore, it is assumed that RSRP values are quantized into codepoints according to the bit width and the quantization step size shown in Table 2 and 3. In Table 2, the reporting range of SS-RSRP and CSI-RSRP for L1 reporting is defined from -140 to -40dBm with 1 dB resolution. In Table 3, the reporting range of differential SS-RSRP and CSI-RSRP for L1 reporting is defined from 0 dBm to -30 dB with 2 dB resolution.

Table 2: SS-RSRP and CSI-RSRP measurement report mapping.

Table 3: Differential SS-RSRP and CSI-RSRP measurement report mapping.

In embodiments another two-stage multilevel beam selection procedure is provided, where a transmission beam sweeping procedure is carried out for the client device 100 to select the candidate beams for paired beams and to report a set of single beams to the network access node 300. The 3GPP release 15 CSI measurement and report procedure can e.g. be reused for this purpose. Among the identified candidate single beams, the network access node 300 configures simultaneous multi beams to the client device 100 for paired beams selection, which will be applied in multi TRP, panel, and/or beam transmission. In this procedure, coordinated CSI resource configurations among beams from multi TRPs and/or panels and CSI reporting configuration associated with the CSI resource configuration are configured for the client device 100. Advanced CSI reports can be introduced in the simultaneous multi beams measurement, e.g. L1-SINR. Fig. 9 shows a flow chart of a two-stage beam selection method 900 based on the measurement report 510 according to such an embodiment of the invention. The two-stage beam selection method 900 can be performed in the client device 100. Step 902 and 904 corresponds to the first stage of the two-stage beam selection method 900. In step 902, the client device 100 is configured with a set of CSI resources from multiple TRPs and/or panels and a CSI measurement report configuration by the network access node 300. Based on the configuration in step 902, the client device 100 measures and provides a first stage measurement report S1 -512 to the network access node 300 in step 904. The first stage measurement report S1 -512 may comprise a list of single beams according to known measurement report structures. The first stage measurement report S1 -512 may correspond to the above-mentioned previous measurement report 510^', when the previous measurement report 510^' indicates measurements associated with a set of reference signal resources for the client device 100.

Step 906 and 908 corresponds to the second stage of the two-stage beam selection method 900. In step 906, the client device 100 is configured with another set of CSI resources from multiple TRPs and/or panels and with another CSI measurement report configuration by the network access node 300. Based on the configuration in step 906, the client device 100 measures and provides a second stage measurement report S2- 510 in step 908. In the second stage, advanced CSI measurement quantity can be performed, e.g. L1 -SINR measurements. The second stage measurement report S2-510 provided in step 908 may comprise the paired beam pairs for which there are not strong interferences from other paired beams. The dual differential measurement values according to the invention are used in the second stage measurement report S2-510.

Fig. 10 shows the first stage S1 and the second stage S2 of the two-stage beam selection method 900 according to an embodiment. In the embodiment shown in Fig. 10, the client device 100 is in the first stage S1 configured to measure the L1 -RSRPs of reference signals corresponding to three beams numbered #1 , #2, #3, respectively, from a first TRP (i.e. TRP1 ) and reference signals corresponding to three beams numbered #4, #5, #6, respectively, from a second TRP (i.e. TRP2). In the first stage reporting of the two-stage beam selection method 900, the client device 100 provides the first stage measurement report S1 -512 to the network access node 300. The first stage measurement report S1 -512 comprises information about the single beams which are strong enough for transmission. In Fig. 10 it is assumed that the beams #2, #3, #5 are strong enough for transmission. Hence, the first stage measurement report S1 - 512 comprises the L1 -RSRP values of the beams #2, #3, #5, as shown in Fig. 10. The L1 - RSRP values are reported as an absolute value for the strongest beam, in this case beam #2 (-70dBm), and as differential values relative to the strongest beam for the rest of the beams #3 (-72dBm, i.e. -2dB in relation to #2) and #5 (-76dBm, i.e. -6dB in relation to #2).

Based on the first stage measurement report S1 -512, the network access node 300 can in the second stage S2 configure a set of group-reference signal resources for the client device 100 upon which the client device 100 can perform and report advanced CSI measurements. Thereby, suitable paired beams can be selected from the list of single beams reported in the first stage S1. The network access node 300 may e.g. configure the client device 100 to measure and report L1 -SINR of the single beams reported in the first stage S1 . The network access node 300 transmits group-reference signals to the client device 100 according to the configured set of group-reference signal resources in the second stage S2, as shown in Fig. 10. In the second stage reporting, the client device 100 provides the second stage measurement report S2-510 to the network access node 300. The second stage measurement report S2-510 comprises the L1 -SINR values of suitable paired beams, e.g. paired beams for which there are not strong interferences from other paired beams. In Fig. 10 it is assumed that the paired beams (#2, #3) and (#3, #5) does not experience strong interferences from other paired beams. Hence, the second stage measurement report S2-510 comprises the L1 -SINR values of the paired beams (#2, #3) and (#3, #5), as shown in Fig. 10.

Specification Impact

Embodiments of the invention can be implemented in various communication standards. One such standard relates to 3GPP NR also known as 5G. In the following disclosure different non limiting examples are given which have standard impact. The following text is based on the 3GPP specification 38.214 f40 modified to describe possible explicative implementations of embodiments of the invention (see text in square brackets).

In respect specification 38.214 f40 5.2.1 .4.“Report Quantity Configurations” is considered:

If the UE is configured with a CSI-ReportConfig with the higher layer parameter reportQuantity set to 'cri-RSRP' or 'ssb-lndex-RSRP',

- if the UE is configured with the higher layer parameter groupBasedBeamReporting set to 'disabled', the UE is not required to update measurements for more than 64 CSI-RS and/or SSB resources, and the UE shall report in a single report nrof Reported RS (higher layer configured) different CRI or SSBRI for each report setting.

- if the UE is configured with the higher layer parameter groupBasedBeamReporting set to 'enabled', the UE is not required to update measurements for more than 64 CSI-RS and/or SSB resources, and the UE shall report in a single reporting instance two different CRI or SSBRI for each report setting, where CSI-RS and/or SSB resources can be received simultaneously by the UE either with a single spatial domain receive filter, or with multiple simultaneous spatial domain receive filters.

[If the UE is configured with a CSI-ReportConfig with the higher layer parameter reportQuantity set to 'cri-SINR' or 'ssb-lndex-SINR',]

- if the UE is configured with the higher layer parameter groupBasedBeamReporting set to 'enabled' [and at the same time is configured with the higher layer parameter multipleBeamTransmissionMode to 'enabled'], the UE is not required to update measurements for more than 64 CSI-RS and/or SSB resources, and the [UE shall report in a single report nrofReportedRSpairs pairs of two different CRI or SSBRI for each report setting, where in each pair] CSI-RS and/or SSB resources can be received simultaneously by the UE either with a single spatial domain receive filter, or with multiple simultaneous spatial domain receive filters.

Also, section 5.2.1.4.3 L1-RSRP[/L1-SINR] Reporting is considered:

For L1-RSRP computation

- the UE may be configured with CSI-RS resources, SS/PBCH Block resources or both CSI-RS and SS/PBCH block resources, when resource-wise quasi co-located with 'QCL-Type C and 'QCL-TypeD' when applicable.

- the UE may be configured with CSI-RS resource setting up to 16 CSI-RS resource sets having up to 64 resources within each set. The total number of different CSI-RS resources over all resource sets is no more than 128.

For L1-RSRP reporting, if the higher layer parameter nrof Reported RS in CSI-ReportConfig is configured to be one, the reported L1-RSRP value is defined by a 7-bit value in the range [-140, -44] dBm with 1dB step size, if the higher layer parameter nrof Reported RS is configured to be larger than one, or if the higher layer parameter groupBasedBeamReporting is configured as 'enabled', the UE shall use differential L1- RSRP based reporting, where the largest measured value of L1-RSRP is quantized to a 7- bit value in the range [-140, -44] dBm with 1 dB step size, and the differential L1-RSRP is quantized to a 4-bit value. The differential L1 -RSRP value is computed with 2 dB step size with a reference to the largest measured L1-RSRP value which is part of the same L1- RSRP reporting instance. The mapping between the reported L1-RSRP value and the measured quantity is described in [1 1 , TS 38.133].

[For L1-SINR computation.]

If the UE is configured with the higher layer parameter groupBasedBeamReporting set to 'enabled' [and at the same time is configured with the higher layer parameter multipleBeamTransmissionMode to 'enabled', and the high layer parameter nrofReportedRSpairs is configured to be one,] the UE shall use differential L1 -SINR based reporting [in a pair, where the first value in the pair is quantized to a 7-bit value in the range [-140, -44] dBm] with 1 dB step size, and the differential L1 -SINR is quantized to a [2-bit value]. The differential L1 -SINR value is computed with [1 dB step size with a reference to the first value in the pair] which is part of the same L1 -SINR reporting instance.

If the UE is configured with the higher layer parameter groupBasedBeamReporting set to 'enabled' [and at the same time is configured with the higher layer parameter multipleBeamTransmissionMode to 'enabled'], and the high layer parameter

[nrofReportedRSpairs is configured to be larger than one,] the UE shall use differential L1 - SINR based reporting [both in the pair and among the first values in the pairs, where the largest measured value of L1 -SINR among the first values in the pairs] is quantized to a 7- bit value in the range [-140, -44] dBm with 1 dB step size, and the differential L1 -SINR [in a pair] is quantized to a [2-bit value]. The differential L1 -SINR value [in the paired RS report] is computed with [1 dB step size] with a reference to the [first measured value of L1 -SINR in its pair] which is part of the same L1 -SINR reporting instance. And the differential L1 - SINR [of the first values in the pairs is quantized to a 4-bit value.] The differential L1 -SINR value [among the first values in the pairs] is computed with 2 dB step size with a reference to [the largest measured value of L1 -SINR among the first values in the pairs] which is part of the same L1 -SINR reporting instance. The mapping between the reported L1 -SINR value and the measured quantity is described in [1 1 , TS 38.133].

The client device 100 herein, may be denoted as a user device, a User Equipment (UE), a mobile station, an internet of things (loT) device, a sensor device, a wireless terminal and/or a mobile terminal, is enabled to communicate wirelessly in a wireless communication system, sometimes also referred to as a cellular radio system. The UEs may further be referred to as mobile telephones, cellular telephones, computer tablets or laptops with wireless capability. The UEs in this context may be, for example, portable, pocket-storable, hand-held, computer- comprised, or vehicle-mounted mobile devices, enabled to communicate voice and/or data, via the radio access network, with another entity, such as another receiver or a server. The UE can be a Station (STA), which is any device that contains an IEEE 802.1 1 -conformant Media Access Control (MAC) and Physical Layer (PHY) interface to the Wireless Medium (WM). The UE may also be configured for communication in 3GPP related LTE and LTE-Advanced, in WiMAX and its evolution, and in fifth generation wireless technologies, such as New Radio.

The network access node 300 herein may also be denoted as a radio network access node, an access network access node, an access point, or a base station, e.g. a Radio Base Station (RBS), which in some networks may be referred to as transmitter,“gNB”,“gNodeB”,“eNB”, “eNodeB”,“NodeB” or“B node”, depending on the technology and terminology used. The radio network access nodes may be of different classes such as e.g. macro eNodeB, home eNodeB or pico base station, based on transmission power and thereby also cell size. The radio network access node can be a Station (STA), which is any device that contains an IEEE 802.1 1 -conformant Media Access Control (MAC) and Physical Layer (PHY) interface to the Wireless Medium (WM). The radio network access node may also be a base station corresponding to the fifth generation (5G) wireless systems.

Furthermore, any method according to embodiments of the invention may be implemented in a computer program, having code means, which when run by processing means causes the processing means to execute the steps of the method. The computer program is included in a computer readable medium of a computer program product. The computer readable medium may comprise essentially any memory, such as a ROM (Read-Only Memory), a PROM (Programmable Read-Only Memory), an EPROM (Erasable PROM), a Flash memory, an EEPROM (Electrically Erasable PROM), or a hard disk drive.

Moreover, it is realized by the skilled person that embodiments of the client device 100 and the network access node 300 comprises the necessary communication capabilities in the form of e.g., functions, means, units, elements, etc., for performing the solution. Examples of other such means, units, elements and functions are: processors, memory, buffers, control logic, encoders, decoders, rate matchers, de-rate matchers, mapping units, multipliers, decision units, selecting units, switches, interleavers, de-interleavers, modulators, demodulators, inputs, outputs, antennas, amplifiers, receiver units, transmitter units, DSPs, MSDs, TCM encoder, TCM decoder, power supply units, power feeders, communication interfaces, communication protocols, etc. which are suitably arranged togetherfor performing the solution.

Especially, the processor(s) of the client device 100 and the network access node 300 may comprise, e.g., one or more instances of a Central Processing Unit (CPU), a processing unit, a processing circuit, a processor, an Application Specific Integrated Circuit (ASIC), a microprocessor, or other processing logic that may interpret and execute instructions. The expression “processor” may thus represent a processing circuitry comprising a plurality of processing circuits, such as, e.g., any, some or all of the ones mentioned above. The processing circuitry may further perform data processing functions for inputting, outputting, and processing of data comprising data buffering and device control functions, such as call processing control, user interface control, or the like. Finally, it should be understood that the invention is not limited to the embodiments described above, but also relates to and incorporates all embodiments within the scope of the appended independent claims.

Claims

1 . A client device (100) for a wireless communication system (500), the client device (100) being configured to

obtain a set of measurements associated with a set of group-reference signal resources; determine a measurement in the set of measurements as a reference measurement; provide a measurement report (510) for the set of group-reference signal resources, wherein the measurements in the set of measurements except the reference measurement are indicated with two or more different types of differential values relative to a value of the reference measurement in the measurement report (510).

2. The client device (100) according to claim 1 , wherein a measurement in each group- reference signal resources is indicated with a first type of differential value relative to the value of the reference measurement, and wherein any other measurement in each group-reference signal resources is indicated with a second type of differential value relative to a value indicated by a first type of differential value.

3. The client device (100) according to claim 2, wherein the first type of differential value is given by a first number of bits in a first step size, and wherein the second type of differential value is given by a second number of bits in a second step size.

4. The client device (100) according to claim 3, wherein the first number of bits is larger than the second number of bits.

5. The client device (100) according to claim 3 or 4, wherein the first step size is larger than the second step size.

6. The client device (100) according to anyone of the preceding claims, wherein determine the reference measurement comprises

7. The client device (100) according to anyone of the preceding claims, wherein the reference measurement is indicated with an absolute value.

8. The client device (100) according to anyone of the preceding claims, wherein the group- reference signal resources are paired reference signal resources.

9. The client device (100) according to anyone of the preceding claims, wherein the set of measurements comprises signal to interference and noise ratio, SINR measurements or received signal received power, RSRP, measurements.

10. The client device (100) according to claim 9, wherein the set of measurements is a set of channel state information, CSI, measurements and the measurement report (510) is a CSI report.

1 1. The client device (100) according to claim 10, configured to

use the CSI report in L1 -SINR or in L1 -RSRP reporting.

12. The client device (100) according to anyone of the preceding claims, configured to

transmit the measurement report (510) to a network access node (300).

13. A network access node (300) for a wireless communication system (500), the network access node (300) being configured to

receive a measurement report (510) for set of measurements associated with a set of group-reference signal resources from a client device (100), wherein the measurements in the set of measurements except a reference measurement are indicated with two or more different types of differential values relative to a value of the reference measurement in the measurement report (510);

14. The network node (300) according to claim 13, configured to

configure a set of group-reference signal resources for the client device (100) based on a previous measurement report (510^') received previously to the reception of the measurement report (510), wherein the previous measurement report (510^') indicates measurements associated with a set of reference signal resources or a set of group-reference signal resources for the client device (100);

transmit a set of group-reference signals to the client device (100) according to the configured set of group-reference signal resources.

15. A method (200) for a client device (100), the method (200) comprising

obtaining (202) a set of measurements associated with a set of group-reference signal resources; determining (204) a measurement in the set of measurements as a reference measurement;

providing (206) a measurement report (510) for the set of group-reference signal resources, wherein the measurements in the set of measurements except the reference measurement are indicated with two or more different types of differential values relative to a value of the reference measurement in the measurement report (510).

16. A method (400) for a network access node (300), the method (400) comprising

receiving (402) a measurement report (510) for set of measurements associated with a set of group-reference signal resources from a client device (100), wherein the measurements in the set of measurements except a reference measurement are indicated with two or more different types of differential values relative to a value of the reference measurement in the measurement report (510);

obtaining (404) the measurements in the set of measurements except the reference measurement based on the two or more different types of differential values and the reference measurement.

17. A computer program with a program code for performing a method according to claim 15 or 16 when the computer program runs on a computer.