EP4616564A1

EP4616564A1 - Methods and apparatuses for coherent joint transmission

Info

Publication number: EP4616564A1
Application number: EP23874216.7A
Authority: EP
Inventors: Yi Zhang; Chenxi Zhu; Wei Ling; Bingchao LIU; Lingling Xiao
Original assignee: Lenovo Beijing Ltd
Current assignee: Lenovo Beijing Ltd
Priority date: 2023-04-03
Filing date: 2023-04-03
Publication date: 2025-09-17
Also published as: CN120435839A; WO2024074021A1; GB2639813A; WO2024074021A9; GB202509268D0

Abstract

The present application relates to methods and apparatuses for coherent joint transmission (CJT). An embodiment of the present disclosure provides a user equipment (UE), including: a transceiver that reports UE capability information indicating one or multiple numbers of channel state information (CSI) processing units (CPUs) for CJT, and a processor that is coupled with the transceiver and performs CSI updating by using unoccupied CPU (s).

Description

METHODS AND APPARATUSES FOR COHERENT JOINT TRANSMISSION

TECHNICAL FIELD

The present disclosure relates to wireless communications, and particularly relates to methods and apparatuses for coherent joint transmission (CJT) .

BACKGROUND OF THE INVENTION

The continuing evolution of multiple inputs multiple outputs (MIMO) may be the most important part of 3^rd generation partnership project (3GPP) physical layer. It is important to identify and specify necessary enhancements for both downlink and uplink MIMO for facilitating the use of large antenna array, not only for frequency range 1 (FR1) but also for FR2 to fulfil the request for evolution of new radio (NR) deployments in 3GPP Release 18.
As coherent joint transmission (CJT) improves coverage and average throughput in commercial deployments with high-performance backhaul and synchronization, enhancements on channel state information (CSI) acquisition for frequency division duplex (FDD) and time division duplex (TDD) , targeting FR1, can be beneficial in expanding the utility of multiple transmission or reception points (TRPs) deployments.
CSI processing for CJT may be more complicated than that for non-CJT (NCJT) . Therefore, it is advantageous to provide solutions for reporting CSI processing unit (CPU) number and CSI updating in CJT scenarios.
SUMMARY
An embodiment of the present disclosure provides a user equipment (UE) . The UE may include: a transceiver that reports UE capability information indicating one or multiple numbers of CPUs for CJT; and a processor that is coupled with the transceiver and performs CSI updating by using unoccupied CPU (s) .
In some embodiments, each of the one or multiple numbers of CPUs corresponds to a respective number of TRPs.
In some embodiments, a number of CPUs within the one or multiple numbers of CPUs which corresponds to N_TRP TRPs is equal to: N_TRP or N_TRP plus an additional number of CPUs.
In some embodiments, the additional number is one or two.
In some embodiments, the one or multiple numbers of CPUs include: a first number of CPUs which corresponds to 2 TRPs and is selected from a group including 2, 3, and 4; a second number of CPUs which corresponds to 3 TRPs and is selected from a group including 3, 4, and 5; or a third number of CPUs which corresponds to 4 TRPs and is selected from a group including 4, 5, and 6.
In some embodiments, each of the one or multiple numbers of CPUs corresponds to a respective number of TRPs and/or is related with a number of TRP selections from the respective number of TRPs.
In some embodiments, a number of CPUs within the one or multiple numbers of CPUs which corresponds to N_TRP TRPs is equal to: N_TRP; N_TRP plus an additional number of CPUs; a sum of a first set of CPU numbers for TRP selection, each CPU number for TRP selection within the first set corresponding to a TRP selection consisting of a respective number of TRPs selected from N_TRP TRPs; or a sum of a second set of CPU numbers for TRP selection, each CPU number for TRP selection within the second set corresponding to all TRP selections consisting of a respective number of TRPs from the N_TRP TRPs.
In some embodiments, the one or multiple numbers of CPUs include: a first number of CPUs which corresponds to 2 TRPs and is selected from a group including 2, 3, 4, and 5; a second number of CPUs which corresponds to 3 TRPs and is selected from a group including 3, 4, 5, 6, and 12; or a third number of CPUs which corresponds to 4 TRPs and is selected from a group including 4, 5, 6, 10, and 32.
In some embodiments, each of the one or multiple numbers of CPUs corresponds to a respective number of TRPs and/or a respective number of beam number combinations.
In some embodiments, a number of CPUs within the one or multiple numbers of CPUs which corresponds N_TRP TRPs and N_L beam number combinations is equal to: a base number in the case of N_L = 1, wherein the base number is equal to N_TRP or N_TRP plus a first additional number of CPUs; the base number plus a second additional number of CPUs or a first multiple of the base number in the case of N_L = 2; or the base number plus the second additional number of CPUs, the base number plus a third additional number of CPUs, or a second multiple of the base number in the case of N_L = 4, wherein the third additional number is greater than the second additional number, and the second multiple is greater than the first multiple.
In some embodiments, the third additional number is twice the second additional number, or the second multiple is twice the first multiple.
In some embodiments, the one or multiple numbers of CPUs include: a first number of CPUs which corresponds to 2 TRPs and 2 beam number combinations and is selected from a group including 3 and 4; a second number of CPUs which corresponds to 2 TRPs and 4 beam number combinations and is selected from a group including 3, 4, and 8; a third number of CPUs which corresponds to 3 TRPs and 2 beam number combinations and is selected from a group including 4 and 6; a fourth number of CPUs which corresponds to 3 TRPs and 4 beam number combinations and is selected from a group including 4, 5, and 12; a fifth number of CPUs which corresponds to 4 TRPs and 2 beam number combinations and is selected from a group including 5 and 8; or a sixth number of CPUs which corresponds to 4 TRPs and 4 beam number combinations and is selected from a group including 5, 6, and 16.
In some embodiments, each of the one or multiple numbers of CPUs corresponds to a respective number of TRPs and a respective number of beam number combinations and/or is related with a number of TRP selections from the respective number of TRPs.
In some embodiments, a number of CPUs within the one or multiple numbers of CPUs which corresponds to N_TRP TRPs and N_L beam number combinations is equal to: a base number in the case of N_L = 1, wherein the base number is equal to: N_TRP; N_TRP plus a first additional number of CPUs; a sum of a first set of CPU numbers for TRP selection, each CPU number for TRP selection within the first set corresponding to a TRP selection consisting of a respective number of TRPs selected from N_TRP TRPs; or a sum of a second set of CPU numbers for TRP selection, each CPU number for TRP selection within the second set corresponding to all TRP selections consisting of a respective number of TRPs from the N_TRP TRPs; the base number plus a second additional number of CPUs or a first multiple of the base number in the case of N_L = 2; or the base number plus the second additional number of CPUs, the base number plus a third additional number of CPUs, or a second multiple of the base number in the case of N_L = 4, wherein the third additional number is greater than the second additional number, and the second multiple is greater than the first multiple.
In some embodiments, the third additional number is twice the second additional number, or the second multiple is twice the first multiple.
In some embodiments, the one or multiple numbers of CPUs include: a first number of CPUs which corresponds to 3 TRPs and 2 beam number combinations and is selected from a group including 4, 6, 7, 12, 13, and 24; a second number of CPUs which corresponds to 3 TRPs and 4 beam number combinations and is selected from a group including 4, 5, 6, 7, 8, 12, 13, and 24; a third number of CPUs which corresponds to 4 TRPs and 2 beam number combinations and is selected from a group including 5, 8, 11, and 20; or a fourth number of CPUs which corresponds to 4 TRPs and 4 beam number combinations and is selected from a group including 5, 6, 11, 12, and 16.
In some embodiments, a maximum number of CPUs across TRPs per carrier is 8, 16, or 32; or a maximum number of CPUs across TRPs across carriers is 32, 64, or 128.
In some embodiments, in response to determining that a number of the unoccupied CPU (s) is no smaller than a CPU number required for updating CSI corresponding to at least one of (1) part but not all of candidate TRP selections or (2) part but not all of candidate beam number combinations, the processor performs CSI updating based on at least one of (1) a TRP selection selected from the part of candidate TRP selections or (2) a beam number combination selected from the part of candidate beam number combinations.
In some embodiments, in response to determining that a number of the unoccupied CPU (s) is no smaller than a CPU number required for updating CSI corresponding to at least one of (1) a default TRP selection but not all of candidate TRP selections or (2) a default beam number combination but not all of candidate beam number combinations, the processor performs CSI updating based on at least one of the default TRP selection or the default beam number combination.
In some embodiments, the default TRP selection includes: all configured TRPs for TRP selection; or a number of TRPs with larger reference signal received power (RSRP) values than others among all the TRPs.
In some embodiments, the default beam number combination has a lowest index among the candidate beam number combinations.
In some embodiments, each of the one or multiple numbers of CPUs corresponds to at least one of a respective TRP selection or a respective beam number combination, and the processor performs CSI updating according to a priority of each CSI report which is determined based at least in part on at least one of: an index of a TRP selection corresponding to the CSI report; a total number of candidate TRP selections; an index of a beam number combination corresponding to the CSI report; or a total number of candidate beam number combinations.
Another embodiment of the present disclosure provides a base station (BS) . The BS may include: a transceiver that receives, from a UE, UE capability information indicating one or multiple numbers of CPUs for CJT, and receives at least one CSI report from the UE; and a processor that is coupled with the transceiver.
Yet another embodiment of the present disclosure provides a method performed by a UE. The method may include: reporting UE capability information indicating one or multiple numbers of CPUs for CJT; and performing CSI updating by using unoccupied CPU (s) .
Still another embodiment of the present disclosure provides a method performed by a BS. The method may include: receiving, from a UE, UE capability information indicating one or multiple numbers of CPUs for CJT; and receiving at least one CSI report from the UE.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to describe the manner in which advantages and features of the application can be obtained, a description of the application is rendered by reference to specific embodiments thereof, which are illustrated in the appended drawings. These drawings depict only example embodiments of the application and are not therefore to be considered limiting of its scope.
Fig. 1 illustrates a schematic diagram of an exemplary wireless communication system according to some embodiments of the present disclosure.
Fig. 2 illustrates a flowchart of an exemplary method for CJT according to some embodiments of the present disclosure.
Fig. 3 illustrates a flowchart of an exemplary method for CJT according to some other embodiments of the present disclosure.
Fig. 4 illustrates a simplified block diagram of an exemplary apparatus for CJT according to some embodiments of the present disclosure.

DETAILED DESCRIPTION

The detailed description of the appended drawings is intended as a description of the currently preferred embodiments of the present invention, and is not intended to represent the only form in which the present invention may be practiced. It should be understood that the same or equivalent functions may be accomplished by different embodiments that are intended to be encompassed within the spirit and scope of the present invention.
While operations are depicted in the drawings in a particular order, persons skilled in the art will readily recognize that such operations need not be performed in the particular order as shown or in a sequential order, or that all illustrated operations need be performed, to achieve desirable results; sometimes one or more operations can be skipped. Further, the drawings can schematically depict one or more example processes in the form of a flow diagram. However, other operations that are not depicted can be incorporated in the example processes that are schematically illustrated. For example, one or more additional operations can be performed before, after, simultaneously, or between any of the illustrated operations. In certain circumstances, multitasking and parallel processing can be advantageous.
Reference will now be made in detail to some embodiments of the present disclosure, examples of which are illustrated in the accompanying drawings. To facilitate understanding, embodiments are provided under specific network architecture and new service scenarios, such as 3GPP long term evolution (LTE) , LTE-Advanced (LTE-A) , 3GPP 4G, 3GPP 5G NR, 3GPP Release 16 and onwards, and so on. It is contemplated that along with the developments of network architectures and new service scenarios, all embodiments in the present disclosure are also applicable to similar technical problems; and moreover, the terminologies recited in the present disclosure may change, which should not affect the principle of the present disclosure.
Fig. 1 is a schematic diagram illustrating an exemplary wireless communication system 100 according to some embodiments of the present application.
Referring to Fig. 1, the wireless communication system 100 may include a BS 101, a number of TRPs (e.g., TRP 103-1, TRP 103-2, ..., TRP 103-N) , and a UE 105. Although only one BS 101, three TRPs and one UE 105 are shown for simplicity, it should be contemplated that the wireless communication system 100 may include any number of BS, TRPs or UEs in accordance with some other embodiments of the present application.
The wireless communication system 100 is compatible with any type of network that is capable of sending and receiving wireless communication signals. For example, the wireless communication system 100 is compatible with a wireless communication network, a cellular telephone network, a time division multiple access (TDMA) based network, a code division multiple access (CDMA) based network, an orthogonal frequency division multiple access (OFDMA) based network, an LTE network, a 3GPP-based network, a 3GPP 5G network, a satellite communications network, a high-altitude platform network, and/or other communications networks.
The BS 101 may also be referred to as an access point, an access terminal, a base, a macro cell, a node-B, an enhanced node B (eNB) , a gNB, a home node-B, a relay node, or a device, or described using other terminology used in the art. The BS 101 is generally part of a radio access network that may include a controller communicably coupled to the BS 101.
The TRPs can communicate with the BS 101 via, for example, a backhaul link. Each of the TRPs can serve one or more UEs. As shown in Fig. 1, the TRP 103-1 can serve some mobile stations (which include the UE 105) within a serving area or region (e.g., a cell or a cell sector) , the TRP 103-2 can serve some mobile stations (which include the UE 105) within a serving area or region (e.g., a cell or a cell sector) , and the TRP 103-N can serve some mobile stations (which include the UE 105) within a serving area or region (e.g., a cell or a cell sector) . In some embodiments, the TRP 103-1, the TRP 103-2, and the TRP 103-N may serve different UEs. The TRPs can communicate with each other via, for example, a backhaul link (not shown in Fig. 1) .
The UE 105 may include computing devices, such as desktop computers, laptop computers, personal digital assistants (PDAs) , tablet computers, smart televisions (e.g., televisions connected to the Internet) , set-top boxes, game consoles, security systems (including security cameras) , vehicle on-board computers, network devices (e.g., routers, switches, and modems) , or the like. According to some embodiments of the present disclosure, the UE 105 may include a portable wireless communication device, a smart phone, a cellular telephone, a flip phone, a device having a subscriber identity module, a personal computer, a selective call receiver, or any other device that is capable of sending and receiving communication signals on a wireless network. In some embodiments of the present disclosure, the UE 105 may include wearable devices, such as smart watches, fitness bands, optical head-mounted displays, or the like. Moreover, the UE 105 may be referred to as a subscriber unit, a mobile, a mobile station, a user, a terminal, a mobile terminal, a wireless terminal, a fixed terminal, a subscriber station, a user terminal, or a device, or described using other terminology used in the art.
In some embodiments of the present application, the TRPs may perform CJT with the UE 105. All the TRPs involved in the CJT may have the same antenna configuration but are at different locations. In the CJT, each TRP may transmit the same data to the UE 105. Each TRP may be configured and transmit with a CSI reference signal (CSI-RS) resource for channel measurement with the same number of antenna ports. In other words, one TRP may correspond to one CSI-RS resource. Therefore, in the present disclosure, the expressions "per TRP" and "per CSI-RS resource" may be used interchangeable, the expressions "across TRPs" and "across CSI-RS resources" may be used interchangeable, or the like.
With continuing evolution of MIMO, currently, it is agreed to specify enhancements of CSI acquisition for CJT targeting FR1 and up to 4 TRPs, assuming ideal backhaul and synchronization as well as the same number of antenna ports across TRPs. The maximum number of CSI-RS ports per CSI-RS resource may be 32. As the TRP number configured for CJT may be 2, 3, and 4, the maximum number of CSI-RS ports across CSI-RS resources may be 128. On the Type-II codebook refinement for multiple TRPs for CJT, regarding the spatial domain basis (i.e., beam) selection, in the case that N_TRP candidate TRPs (or candidate CSI-RS resources) are configured by a BS, the BS may configure N_L combinations of values from a beam number set, i.e., {L₁, ..., L_NTRP} , via higher-layer (e.g., radio link control (RRC) ) signaling, wherein L_i is a beam number for TRP_i, i = 1, …, N_TRP.
In some embodiments, the selection of N CSI-RS resources from N_TRP candidate CSI-RS resources can be performed by a UE for CJT. That is, the UE may support TRP selection and indicate the selected TRP (s) (or TRP selection) in a CSI report. In some embodiments, the selection of a beam number combination from N_L (N_L>1) configured combinations can be performed by a UE for CJT. That is, the UE may support beam number combination selection and indicate the selected beam number combination in a CSI report. With increasing CSI-RS resources for CJT, TRP selection, and beam number combination selection, the UE processing complexity for CSI in CJT scenarios is increased remarkably. Thus, the CPU number for CJT is increased and may need to be redefined. This issue is related with UE capability discussion, which may happen after the enhanced codebook design is finalized. Until now, there is no such discussion on reporting of CPU number for CJT. Furthermore, as the UE processing complexity for CSI in CJT scenarios is increased remarkably, the solution for CSI updating by using unoccupied CPU (s) is also needed to be taken into consider in CJT scenarios.
The present disclosure provides solutions for reporting CPU number (s) for CJT in the case of different UE processing capabilities. Furthermore, the present disclosure provides methods for enhanced CSI updating with finer granularity of occupied CPUs for CJT based on transmission assumption including selected TRPs and/or selected beam number combination. According to the various embodiments of the present application, the UE may report capability information on CPU number (s) based on different numbers of TRPs and/or different numbers of beam number combinations configured for CJT so as for the BS to better configure the UE, and may update CJT CSI report based on finer granularity corresponding candidate (s) of TRP selection and/or beam number combination selection on unoccupied CPUs so as to better use the resources.
Fig. 2 illustrates a flowchart of an exemplary method 200 for CJT according to some embodiments of the present disclosure. The method 200 may be performed by a UE or other device with similar functions.
According to Fig. 2, in operation 210, the UE may report (e.g., to a BS) UE capability information indicating one or multiple numbers of CPUs for CJT. In operation 220, the UE may perform CSI updating by using unoccupied CPU (s) . Moreover, the UE may transmit at least one CSI report to the BS based on the CSI updating.
A maximum number of CPUs for CJT supported by the UE may be defined. In single TRP or NCJT scenarios, the maximum number of CPUs may be 8 per carrier and 32 across carriers. For CJT, the maximum number of CPUs supported by the UE may be increased on account of multiple TRPs (e.g., 2 or 4 TRPs) . For example, a maximum number of CPUs across TRPs per carrier may be 8, 16, or 32; or a maximum number of CPUs across TRPs across carriers may be 32, 64, or 128.
Depending on different UE capabilities, solutions for reporting CPU number (s) may be classified in the following four cases.
Case 1
In case 1, the UE may not support TRP selection and beam number combination selection. In such case, each of the one or multiple numbers of CPUs indicated in the UE capability information reported in operation 210 may correspond to a respective number of TRPs. For example, as each of the CSI-RS resources has a same number of CSI-RS ports, the one or multiple numbers of CPUs for CJT may be increased (e.g., linearly increased) with the configured TRP number (denoted as N_TRP) .
In some embodiments, N_TRP configured for CJT may be 2, 3, or 4. To better match the UE hardware, the UE may report 3 numbers of CPUs for CJT corresponding to 2 TRPs, 3 TRPs, and 4 TRPs, respectively. In some embodiments, the UE may report only one or two of these 3 numbers of CPUs for CJT based on one or two UE processing capabilities irrespective to actual TRP number for CJT transmission.
In some embodiments, a number of CPUs corresponding to N_TRP TRPs within the one or multiple numbers indicated in the UE capability information reported in operation 210 may be equal to N_TRP. That is, one CPU is required for CSI processing for one TRP. This may apply to a UE with a high hardware processing capability.
In some embodiments, for a UE with a medium or low hardware processing capability, the CPU number required for CSI processing may be increased. For example, the number of CPUs corresponding to N_TRP TRPs within the one or multiple numbers indicated in the UE capability information reported in operation 210 may be equal to N_TRP plus an additional number of CPUs. In some embodiments, the additional number may be 1 or 2.
For example, for N_TRP = 2, the corresponding number of CPUs for CJT may be 2 (for high hardware processing capability) , or 3 (for medium hardware processing capability) , or 4 (for low hardware processing capability) ; for N_TRP = 3, the corresponding number of CPUs for CJT may be 3 (for high hardware processing capability) , or 4 (for medium hardware processing capability) , or 5 (for low hardware processing capability) ; for N_TRP = 4, the corresponding number of CPUs for CJT may be 4 (for high hardware processing capability) , or 5 (for medium hardware processing capability) , or 6 (for low hardware processing capability) .
Case 2
In case 2, the UE may support TRP selection but not support beam number combination selection. The UE may select N CSI-RS resources from N_TRP CSI-RS resources configured by the BS (i.e., select N TRPs from N_TRP TRPs) and report the TRP selection as a part of a CSI report. In such case, each of the one or multiple numbers of CPUs indicated in the UE capability information reported in operation 210 may correspond to a respective number of TRPs. Additionally or alternatively, each of the one or multiple numbers of CPUs may be related with a number of TRP selections from the respective number of TRPs. The number of TRP selections may depend on a TRP selection scheme used by the UE.
In some embodiments, N_TRP configured for CJT may be 2, 3, or 4. To better match the UE hardware, the UE may report 3 numbers of CPUs for CJT corresponding to 2 TRPs, 3 TRPs, and 4 TRPs, respectively. In some embodiments, the UE may report only one or two of these 3 numbers of CPUs for CJT based on one or two UE processing capabilities irrespective to actual TRP number for CJT transmission.
In a first TRP selection scheme, the UE may select N TRPs for CJT from N_TRP TRPs based on RSRPs of the N_TRP TRPs. For example, the UE may select N TRPs with highest RSRPs among the N_TRP TRPs. According to the first TRP selection scheme, the UE may not need any additional CPU for TRP selection, and thus the designs for CPU number reporting described in case 1 may also apply here. For example, a number of CPUs corresponding to N_TRP TRPs within the one or multiple numbers indicated in the UE capability information reported in operation 210 may be equal to N_TRP (for high hardware processing capability) or N_TRP plus an additional number of CPUs (for medium or low hardware processing capability) . In some embodiments, the additional number may be 1 or 2.
In a second TRP selection scheme, to select TRP (s) for CJT from N_TRP TRPs, for each possible value of N (i.e., 1, …, N_TRP) , the UE may select N TRPs (i.e., a candidate TRP selection consisting of N TRPs) with highest RSRPs among the N_TRP TRPs. Then, the UE may perform selection among N_TRP candidate TRP selections. According to the second TRP selection scheme, for a configured N_TRP, the corresponding number of CPUs may be equal to a sum of a first set of CPU numbers for TRP selection, wherein each CPU number for TRP selection within the first set may correspond to a TRP selection consisting of a respective number of TRPs selected from N_TRP TRPs.
For example, for N_TRP = 2, the corresponding number of CPUs may be equal to a sum of a first CPU number for TRP selection corresponding to a TRP selection consisting of one TRP and a second CPU number for TRP selection corresponding to a TRP selection consisting of 2 TRPs. In an example, assuming that one CPU is required for processing with respect to one TRP, i.e., the first CPU number is 1 and the second CPU number is 2, the corresponding number of CPUs is equal to 1 + 2 = 3.
For N_TRP = 3, the corresponding number of CPUs may be equal to a sum of a first CPU number for TRP selection corresponding to a TRP selection consisting of one TRP, a second CPU number for TRP selection corresponding to a TRP selection consisting of 2 TRPs, and a third CPU number for TRP selection corresponding to a TRP selection consisting of 3 TRPs. In an example, assuming that one CPU is required for processing with respect to one TRP, i.e., the first CPU number is 1, the second CPU number is 2, and the third CPU number is 3, then the corresponding number of CPUs is equal to 1 + 2 + 3 = 6.
For N_TRP = 4, the corresponding number of CPUs may be equal to a sum of a first CPU number for TRP selection corresponding to a TRP selection consisting of one TRP, a second CPU number for TRP selection corresponding to a TRP selection consisting of 2 TRPs, a third CPU number for TRP selection corresponding to a TRP selection consisting of 3 TRPs, and a fourth CPU number for TRP selection corresponding to a TRP selection consisting of 4 TRPs. In an example, assuming that one CPU is required for processing with respect to one TRP, i.e., the first CPU number is 1, the second CPU number is 2, the third CPU number is 3, and the fourth CPU number is 4, then the corresponding number of CPUs is equal to 1 + 2 + 3 + 4 = 10.
It is contemplated that the first, second, third, and fourth CPU numbers may have other values in other examples.
In the examples of the first and second TRP selection schemes described above, TRP selection is made based on RSRP. It is contemplated that similar selection schemes based on other parameters may be applied.
In a third TRP selection scheme, the UE may select TRP (s) by considering all possible TRP selections. According to the third TRP selection scheme, for a configured N_TRP, the corresponding number of CPUs may be equal to a sum of a second set of CPU numbers for TRP selection, wherein each CPU number for TRP selection within the second set may correspond to all TRP selections consisting of a respective number of TRPs from N_TRP TRPs.
For example, for N_TRP = 2, the corresponding number of CPUs may be equal to a sum of a first CPU number for TRP selection corresponding to all TRP selections consisting of one TRP and a second CPU number for TRP selection corresponding to all TRP selections consisting of 2 TRPs. The number of TRP selections consisting of one TRP isand the number of TRP selections consisting of two TRPs is In an example, assuming that one CPU is required for processing with respect to one TRP, then the first CPU number corresponding to 2 TRP selections consisting of one TRP is equal to 2*1=2, the second CPU number corresponding to 1 TRP selection consisting of two TRPs is 1*2=2, and the corresponding number of CPUs is equal to 2 + 2 = 4.
For N_TRP = 3, the corresponding number of CPUs may be equal to a sum of a first CPU number for TRP selection corresponding to all TRP selections consisting of one TRP, a second CPU number for TRP selection corresponding to all TRP selections consisting of 2 TRPs, and a third CPU number for TRP selection corresponding to all TRP selections consisting of 3 TRPs. The number of TRP selections consisting of one TRP isthe number of TRP selections consisting of two TRPs isand the number of TRP selections consisting of three TRPs isIn an example, assuming that one CPU is required for processing with respect to one TRP, then the first CPU number corresponding to 3 TRP selections consisting of one TRP is equal to 3*1=3, the second CPU number corresponding to 3 TRP selections consisting of two TRPs is 3*2=6, the third CPU number corresponding to 1 TRP selection consisting of three TRPs is 1*3=3, and the corresponding number of CPUs is equal to 3 + 6 + 3 = 12.
For N_TRP = 4, the corresponding number of CPUs may be equal to a sum of a first CPU number for TRP selection corresponding to all TRP selections consisting of one TRP, a second CPU number for TRP selection corresponding to all TRP selections consisting of 2 TRPs, a third CPU number for TRP selection corresponding to all TRP selections consisting of 3 TRPs, and a fourth CPU number for TRP selection corresponding to all TRP selections consisting of 4 TRPs. The number of TRP selections consisting of one TRP isthe number of TRP selections consisting of two TRPs isthe number of TRP selections consisting of three TRPs is and the number of TRP selections consisting of three TRPs isIn an example, assuming that one CPU is required for processing with respect to one TRP, then the first CPU number corresponding to 4 TRP selections consisting of one TRP is equal to 4*1=4, the second CPU number corresponding to 6 TRP selections consisting of two TRPs is 6*2=12, the third CPU number corresponding to 4 TRP selections consisting of three TRPs is 4*3=12, the fourth CPU number corresponding to 1 TRP selection consisting of four TRPs is 1*4=4, and the corresponding number of CPUs is equal to 4 + 12 + 12 + 4 = 32.
It is contemplated that the first, second, third, and fourth CPU numbers may have other values in other examples.
According to the above examples, for N_TRP = 2, the corresponding number of CPUs for CJT may be one of 2, 3, 4, or 5; for N_TRP = 3, the corresponding number of CPUs for CJT may be one of 3, 4, 5, 6, or 12; for N_TRP = 4, the corresponding number of CPUs for CJT may be one of 4, 5, 6, 10, or 32.
In some embodiments, the one or multiple numbers of CPUs for CJT reported in case 2 may be backward compatible with case 1.
In some embodiments, the UE may be considered to have a high hardware processing capability in the case of supporting TRP selection.
Case 3
In case 3, the UE may support beam number combination selection but not support TRP selection. For a configured value of N_TRP, a set of N_L combinations of values for {L₁, ..., L_NTRP} is configured by the BS via higher-layer (RRC) signaling. When the beam number combination number N_L > 1, the selected combination of values for {L₁, ..., L_NTRP} is reported by an indicator in a CSI report. In such case, additional UE realization complexity is related with beam selection algorithm. Each of the one or multiple numbers of CPUs for CJT indicated in the UE capability information reported in operation 210 may correspond to a respective number of TRPs. Additionally or alternatively, each of the one or multiple numbers of CPUs may be related with a respective number of beam number combinations.
In some embodiments, N_TRP configured for CJT may be 2, 3, or 4, and the configured N_L may be 1, 2, or 4. To better match the UE hardware, the UE may report 9 numbers of CPUs for CJT respectively corresponding to a value for N_TRP from {2, 3, 4} and a value for N_L from {1, 2, 4} . In some embodiments, the UE may report part of the 9 numbers of CPUs for CJT, e.g. one or two or three numbers based on assumed UE capability. The assumed UE capability may correspond to specific TRP number and specific beam number combination. In some embodiments, the UE may report part of the 9 numbers of CPUs for CJT; and other CPU number (s) for specific TRP number (s) and specific beam number combination (s) can be implicitly derived based on the reported value (s) and the introduced schemes of the present disclosure.
In case 3, according to some embodiments, a number of CPUs within the one or multiple numbers of CPUs which corresponds to N_TRP TRPs and N_L beam number combinations may be equal to:
- a base number in the case of N_L = 1: for N_L = 1, the UE may not need any additional CPU for beam number combination selection, so the designs for CPU number reporting described in case 1 may also apply here, for example, the base number may be equal to N_TRP (for high hardware processing capability) or N_TRP plus a first additional number of CPUs (for medium or low hardware processing capability) ;
- the base number plus a second additional number of CPUs or a first multiple of the base number in the case of N_L = 2: additional CPU (s) may be needed for beam number combination selection in the case of N_L = 2 relative to the case of N_L = 1; or
- the base number plus the second additional number of CPUs, the base number plus a third additional number of CPUs, or a second multiple of the base number in the case of N_L = 4: additional CPU (s) may be needed for beam number combination selection in the case of N_L = 4 relative to the case of N_L = 2, so the third additional number may be greater than the second additional number (e.g., the third additional number is twice the second additional number) , or the second multiple may be greater than the first multiple (e.g., the second multiple is twice the first multiple) .
In some embodiments, the first additional number may be 1 or 2. In some embodiments, the second additional number may be 1. In some embodiments, the third additional number may be 2. In some embodiments, the first multiple may be 2, and the second multiple may be 4. It is contemplated that other values may be applied to these numbers or multiples.
For example, for N_TRP = 2, a corresponding number of CPUs for N_L = 1 may be 2, 3, or 4, a corresponding number of CPUs for N_L = 2 may be 2+1, 3+1, 4+1, 2*2, 3*2, or 4*2, and a corresponding number of CPUs for N_L = 4 may be 2+1, 3+1, 4+1, 2+2, 3+2, 4+2, 2*4, 3*4, or 4*4.
For example, for N_TRP = 3, a corresponding number of CPUs for N_L = 1 may be 3, 4, or 5, a corresponding number of CPUs for N_L = 2 may be 3+1, 4+1, 5+1, 3*2, 4*2, or 5*2, and a corresponding number of CPUs for N_L = 4 may be 3+1, 4+1, 5+1, 3+2, 4+2, 5+2, 3*4, 4*4, or 5*4.
For example, for N_TRP = 4, a corresponding number of CPUs for N_L = 1 may be 4, 5, or 6, a corresponding number of CPUs for N_L = 2 may be 4+1, 5+1, 6+1, 4*2, 5*2, or 6*2, and a corresponding number of CPUs for N_L = 4 may be 4+1, 5+1, 6+1, 4+2, 5+2, 6+2, 4*4, 5*4, or 6*4.
In some embodiments, the one or more numbers of CPUs for CJT reported in case 3 may be backward compatible with case 1.
In some embodiments, the UE may be considered to have a high hardware processing capability in the case of supporting beam number combination selection.
Case 4
In case 4, the UE may support both TRP selection and beam number combination selection. In such case, the designs for CPU number reporting described in case 2 and case 3 may be combined. For example, each of the one or multiple numbers of CPUs for CJT indicated in the UE capability information reported in operation 210 may correspond to a respective number of TRPs and a respective number of bean number combinations. Additionally or alternatively, each of the one or multiple numbers of CPUs may be related with a number of TRP selections from the respective number of TRPs.
In some embodiments, the configured TRP number N_TRP may be 2, 3, or 4, and the configured beam number combination number N_L may be 1, 2, or 4. To better match the UE hardware, the UE may report 9 numbers of CPUs for CJT respectively corresponding to a value for N_TRP from {2, 3, 4} and a value for N_L from {1, 2, 4} . In some embodiments, the UE may report part of the 9 numbers of CPUs for CJT, e.g. one or two or three numbers based on assumed UE capability. The assumed UE capability may correspond to specific TRP number and specific beam number combination. In some embodiments, the UE may report part of the 9 numbers of CPUs for CJT; and other CPU number (s) for specific TRP number (s) and specific beam number combination (s) can be implicitly derived based on the reported value (s) and the introduced schemes of the present disclosure.
In case 4, according to some embodiments, a number of CPUs within the one or multiple numbers of CPUs which corresponds to N_TRP TRPs and N_L beam number combinations may be equal to:
- a base number in the case of N_L = 1: for N_L = 1, the UE may not need any additional CPU for beam number combination selection, so the designs for CPU number reporting described in case 2 may also apply here, for example, the base number may be equal to:
· N_TRP;
· N_TRP plus a first additional number of CPUs;
· a sum of a first set of CPU numbers for TRP selection, each CPU number for TRP selection within the first set corresponding to a TRP selection consisting of a respective number of TRPs selected from N_TRP TRPs (e.g., based on RSRP values) ; or
· a sum of a second set of CPU numbers for TRP selection, each CPU number for TRP selection within the second set corresponding to all TRP selections consisting of a respective number of TRPs from the N_TRP TRPs;
- the base number plus a second additional number of CPUs or a first multiple of the base number in the case of N_L = 2: additional CPU (s) may be needed for beam number combination selection in the case of N_L = 2 relative to the case of N_L = 1; or
- the base number plus the second additional number of CPUs, the base number plus a third additional number of CPUs, or a second multiple of the base number in the case of N_L = 4: additional CPU (s) may be needed for beam number combination selection in the case of N_L = 4 relative to the case of N_L = 2, so the third additional number may be greater than the second additional number (e.g., the third additional number is twice the second additional number) , or the second multiple may be greater than the first multiple (e.g., the second multiple is twice the first multiple) .
In some embodiments, the first additional number may be 1 or 2. In some embodiments, the second additional number may be 1. In some embodiments, the third additional number may be 2. In some embodiments, the first multiple may be 2, and the second multiple may be 4. It is contemplated that other values may be applied to these numbers or multiples.
The following Table 1 illustrates exemplary candidate numbers of CPUs respectively corresponding to a value for N_TRP from {2, 3, 4} and a value for N_L from {1, 2, 4} .
Table 1
In some embodiments, the one or more numbers of CPUs for CJT reported in case 4 may be backward compatible with any of cases 1-3.
In some embodiments, the UE may be considered to have a high hardware processing capability in the case of supporting both TRP selection and beam number combination selection.
According to the present disclosure, for a UE supporting TRP selection and/or beam number combination selection, the required CPU number (or the number of CPUs to be occupied) for CSI updating is larger than that for a UE not supporting TRP selection or beam number combination selection. Therefore, if the number of unoccupied CPUs for CSI updating is smaller than the required CPU number for CSI updating in the case of supporting TRP selection and/or beam number combination selection, it is not efficient that CSI is not updated; this is because it is possible that CSI based on some transmission assumptions including specific TRP selection and/or specific beam number combination can be updated by using the unoccupied CPU.
The present application provides several solutions for updating CSI for CJT in the case that unoccupied CPUs can support CSI updating based on at least one of part of candidate TRP selections or part of candidate beam number combinations.
In some embodiments, for a UE supporting at least one of TRP selection or beam number combination selection, if the number of unoccupied CPUs is smaller than the required CPU number for CSI updating based on all the candidate TRP selections or all the candidate beam number combinations, but the number of unoccupied CPUs is enough to update CSI based on at least one of part of candidate TRP selections or part of candidate beam number combinations, the UE may update CSI based on at least one of a selected candidate TRP selection or a selected beam number combination selection. The selected candidate TRP selection or selected beam number combination selection may correspond to a CPU number smaller than the number of unoccupied CPUs. In other words, in response to determining that a number of the unoccupied CPU (s) is no smaller than a CPU number required for updating CSI corresponding to at least one of (1) part but not all of candidate TRP selections or (2) part but not all of candidate beam number combinations, the UE may perform CSI updating based on at least one of (1) a TRP selection selected from the part of candidate TRP selections or (2) a beam number combination selected from the part of candidate beam number combinations. Then, the UE may transmit a CSI report based on the updating. In some embodiments, the UE may further report information indicating at least one of the selected TRP selection or the selected beam number combination to the BS, e.g., via uplink control information (UCI) .
In some embodiments, if the number of unoccupied CPUs is smaller than the required CPU number for CSI updating based on all the candidate TRP selections or all the candidate beam number combinations, but the number of unoccupied CPUs is enough to update CSI based on at least one of a default candidate TRP selection or a default candidate beam number combination, the UE may update CSI based on the at least one of the default candidate TRP selection or default candidate beam number combination. In other words, in response to determining that a number of the unoccupied CPU (s) is no smaller than a CPU number required for updating CSI corresponding to at least one of (1) a default TRP selection but not all of candidate TRP selections or (2) a default beam number combination but not all of candidate beam number combinations, the UE may perform CSI updating based on at least one of the default TRP selection or the default beam number combination. Then, the UE may transmit a CSI report based on the updating. In some embodiments, the UE may further report information indicating at least one of the default TRP selection or the default beam number combination to the BS, e.g., via UCI. In some embodiments, the default TRP selection may include all configured TRPs for TRP selection. In some embodiments, the default TRP selection may include a number (e.g., 2) of TRPs with larger RSRP values than others among all the TRPs. In some embodiments, the default beam number combination may have a lowest index among the candidate beam number combinations.
In some embodiments, CPU number reporting may be performed with finer granularity. For example, each of the one or multiple numbers of CPUs for CJT indicated in the UE capability information reported in operation 210 may correspond to at least one of a respective TRP selection or a respective beam number combination. Then, the UE may performs CSI updating according to a priority of each CSI report which is determined based at least in part on at least one of:
- an index of a TRP selection corresponding to the CSI report (e.g., denoted by I_k) ;
- a total number of candidate TRP selections (e.g., denoted by I_TRP) ;
- an index of a beam number combination corresponding to the CSI report (e.g., denoted by N_l) ; or
- a total number of candidate beam number combinations (e.g., denoted by N_L) .
For example, the priority of a CSI report may be determined based on the following Formula 1 or Formula 2:
Pri_iCSI (y, k, c, s) =2·N_cells·M_s·I_TRP·N_L·y+N_cells·M_s·I_TRP·N_L·k+M_s·
I_TRP·N_L·c+I_TRP·N_L·s+N_L·I_k+ N_l (Formula 1) ; or
Pri_iCSI (y, k, c, s) =2·N_cells·M_s·I_TRP·N_L·y+N_cells·M_s·I_TRP·N_L·k+M_s·
I_TRP·N_L·c+I_TRP·N_L·s+I_TRP·N_l+ I_k (Formula 2) ;
wherein:
- y indicates a type of the CSI report: y=0 for aperiodic CSI reports to be carried on physical uplink shared channel (PUSCH) ; y=1 for semi-persistent CSI reports to be carried on PUSCH; y=2 for semi-persistent CSI reports to be carried on physical uplink control channel (PUCCH) ; and y=3 for periodic CSI reports to be carried on PUCCH;
- k indicates whether the CSI report carries L1 RSRP or L1 signal to interference plus noise ratio (SINR) : k=0 for CSI reports carrying L1-RSRP or L1-SINR; and k=1 for CSI reports not carrying L1-RSRP or L1-SINR;
- c is the serving cell index;
- N_cells is the value of the maximum number of the serving cells (e.g., the higher layer parameter maxNrofServingCells)
- s is a serving cell index; and
- M_s is the value of the higher layer parameter maxNrofCSI-ReportConfigurations.
Based on the aforementioned priorities, CSI updating may be performed more efficiently.
Fig. 3 illustrates a flowchart of an exemplary method 300 for CJT according to some embodiments of the present disclosure. The method 300 may be performed by a BS or other devices with similar functions.
According to Fig. 3, in operation 310, the BS may receive, from a UE, UE capability information indicating one or multiple numbers of CPUs for CJT. The designs for CPU number reporting described with respect to Fig. 2 may also apply here. The BS may configure CSI for the UE based at least in part on the CPU number (s) reported by the UE. In operation 320, the BS may receive at least one CSI report from the UE.
Fig. 4 illustrates a simplified block diagram of an exemplary apparatus 400 according to some embodiments of the present disclosure.
As shown in Fig. 4, an example of the apparatus 400 may include at least one processor 404 and at least one transceiver 402 coupled to the processor 404. The apparatus 400 may be a UE, a BS or any other device with similar functions.
Although in this figure, elements such as the at least one transceiver 402 and processor 404 are described in the singular, the plural is contemplated unless a limitation to the singular is explicitly stated. In some embodiments of the present disclosure, the transceiver 402 may be divided into two devices, such as a receiving circuitry and a transmitting circuitry. In some embodiments of the present disclosure, the apparatus 400 may further include an input device, a memory, and/or other components.
In some embodiments of the present disclosure, the apparatus 400 may be a UE. The transceiver 402 and the processor 404 may interact with each other so as to perform the operations of a UE as described with respect to Fig. 2. For example, the transceiver 402 may report UE capability information indicating one or multiple numbers of CPUs for CJT, and perform CSI updating by using unoccupied CPU (s) .
In some embodiments of the present disclosure, the apparatus 400 may be a BS. The transceiver 402 and the processor 404 may interact with each other so as to perform the operations of a BS as described with respect to Fig. 3. For example, the transceiver 402 may receive, from a UE, UE capability information indicating one or multiple numbers of CPUs for CJT, and receive at least one CSI report from the UE.
In some embodiments of the present disclosure, the apparatus 400 may further include at least one non-transitory computer-readable medium.
For example, in some embodiments of the present disclosure, the non-transitory computer-readable medium may have stored thereon computer-executable instructions to cause the processor 404 to implement any method described above with respect to a UE. For example, the computer-executable instructions, when executed, may cause the processor 404 interacting with the transceiver 402 to perform the operations of a UE as described with respect to Fig. 2.
In some embodiments of the present disclosure, the non-transitory computer-readable medium may have stored thereon computer-executable instructions to cause the processor 404 to implement any method described above with respect to a BS. For example, the computer-executable instructions, when executed, may cause the processor 404 interacting with the transceiver 402 to perform the operations of a BS as described with respect to Fig. 3.
The method of the present disclosure can be implemented on a programmed processor. However, controllers, flowcharts, and modules may also be implemented on a general purpose or special purpose computer, a programmed microprocessor or microcontroller and peripheral integrated circuit elements, an integrated circuit, a hardware electronic or logic circuit such as a discrete element circuit, a programmable logic device, or the like. In general, any device that has a finite state machine capable of implementing the flowcharts shown in the figures may be used to implement the processing functions of the present disclosure.
While the present disclosure has been described with specific embodiments thereof, it is evident that many alternatives, modifications, and variations will be apparent to those skilled in the art. For example, various components of the embodiments may be interchanged, added, or substituted in other embodiments. Also, all of the elements shown in each figure are not necessary for operation of the disclosed embodiments. For example, one skilled in the art of the disclosed embodiments would be capable of making and using the teachings of the present disclosure by simply employing the elements of the independent claims. Accordingly, the embodiments of the present disclosure as set forth herein are intended to be illustrative, not limiting. Various changes may be made without departing from the spirit and scope of the present disclosure.
In this disclosure, relational terms such as "first, " "second, " and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. The terms "comprises, " "comprising, " or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. An element proceeded by "a, " "an, " or the like does not, without more constraints, preclude the existence of additional identical elements in the process, method, article, or apparatus that comprises the element. Also, the term "another" is defined as at least a second or more. The terms "including, " "having, " and the like, as used herein, are defined as "comprising. "

Claims

A user equipment (UE) , comprising:

a transceiver that reports UE capability information indicating one or multiple numbers of channel state information (CSI) processing units (CPUs) for coherent joint transmission (CJT) ; and

a processor that is coupled with the transceiver and performs CSI updating by using unoccupied CPU (s) .
The UE of Claim 1, wherein each of the one or multiple numbers of CPUs corresponds to a respective number of TRPs.
The UE of Claim 2, wherein a number of CPUs within the one or multiple numbers of CPUs which corresponds to N_TRP TRPs is equal to:

N_TRP; or

N_TRP plus an additional number of CPUs.
The UE of Claim 3, wherein the one or multiple numbers of CPUs include:

a first number of CPUs which corresponds to 2 TRPs and is selected from a group including 2, 3, and 4;

a second number of CPUs which corresponds to 3 TRPs and is selected from a group including 3, 4, and 5; or

a third number of CPUs which corresponds to 4 TRPs and is selected from a group including 4, 5, and 6.
The UE of Claim 1, wherein each of the one or multiple numbers of CPUs corresponds to a respective number of TRPs and/or is related with a number of TRP selections from the respective number of TRPs.
The UE of Claim 5, wherein a number of CPUs within the one or multiple numbers of CPUs which corresponds to N_TRP TRPs is equal to:

N_TRP;

N_TRP plus an additional number of CPUs;

a sum of a first set of CPU numbers for TRP selection, each CPU number for TRP selection within the first set corresponding to a TRP selection consisting of a respective number of TRPs selected from N_TRP TRPs; or

a sum of a second set of CPU numbers for TRP selection, each CPU number for TRP selection within the second set corresponding to all TRP selections consisting of a respective number of TRPs from the N_TRP TRPs.
The UE of Claim 1, wherein:

each of the one or multiple numbers of CPUs corresponds to a respective number of TRPs and/or a respective number of beam number combinations; and

a number of CPUs within the one or multiple numbers of CPUs which corresponds N_TRP TRPs and N_L beam number combinations is equal to:

a base number in the case of N_L = 1, wherein the base number is equal to N_TRP or N_TRP plus a first additional number of CPUs;

the base number plus a second additional number of CPUs or a first multiple of the base number in the case of N_L = 2; or

the base number plus the second additional number of CPUs, the base number plus a third additional number of CPUs, or a second multiple of the base number in the case of N_L = 4, wherein the third additional number is greater than the second additional number, and the second multiple is greater than the first multiple.
The UE of Claim 1, wherein each of the one or multiple numbers of CPUs corresponds to a respective number of TRPs and a respective number of beam number combinations and/or is related with a number of TRP selections from the respective number of TRPs.
The UE of Claim 8, wherein a number of CPUs within the one or multiple numbers of CPUs which corresponds to N_TRP TRPs and N_L beam number combinations is equal to:

a base number in the case of N_L = 1, wherein the base number is equal to:

N_TRP;

N_TRP plus a first additional number of CPUs;

a sum of a first set of CPU numbers for TRP selection, each CPU number for TRP selection within the first set corresponding to a TRP selection consisting of a respective number of TRPs selected from N_TRP TRPs; or

a sum of a second set of CPU numbers for TRP selection, each CPU number for TRP selection within the second set corresponding to all TRP selections consisting of a respective number of TRPs from the N_TRP TRPs;

the base number plus a second additional number of CPUs or a first multiple of the base number in the case of N_L = 2; or

the base number plus the second additional number of CPUs, the base number plus a third additional number of CPUs, or a second multiple of the base number in the case of N_L = 4, wherein the third additional number is greater than the second additional number, and the second multiple is greater than the first multiple.
The UE of Claim 1, wherein:

a maximum number of CPUs across TRPs per carrier is 8, 16, or 32; or

a maximum number of CPUs across TRPs across carriers is 32, 64, or 128.
The UE of Claim 1, wherein:

in response to determining that a number of the unoccupied CPU (s) is no smaller than a CPU number required for updating CSI corresponding to at least one of (1) part but not all of candidate TRP selections or (2) part but not all of candidate beam number combinations, the processor performs CSI updating based on at least one of (1) a TRP selection selected from the part of candidate TRP selections or (2) a beam number combination selected from the part of candidate beam number combinations.
The UE of Claim 1, wherein:

in response to determining that a number of the unoccupied CPU (s) is no smaller than a CPU number required for updating CSI corresponding to at least one of (1) a default TRP selection but not all of candidate TRP selections or (2) a default beam number combination but not all of candidate beam number combinations, the processor performs CSI updating based on at least one of the default TRP selection or the default beam number combination.
The UE of Claim 12, wherein the default TRP selection includes:

all configured TRPs for TRP selection; or

a number of TRPs with larger reference signal received power (RSRP) values than others among all the TRPs.
A base station (BS) , comprising:

a transceiver that:

receives, from a user equipment (UE) , UE capability information indicating one or multiple numbers of channel state information (CSI) processing units (CPUs) for coherent joint transmission (CJT) ; and

receives at least one CSI report from the UE; and

a processor that is coupled with the transceiver.
A method performed by a user equipment, comprising:

reporting UE capability information indicating one or multiple numbers of channel state information (CSI) processing units (CPUs) for coherent joint transmission (CJT) ; and

performing CSI updating by using unoccupied CPU (s) .