Patent Publication Number: US-2021184750-A1

Title: Beam management

Description:
TECHNICAL FIELD 
     Embodiments of the present disclosure generally relate to the field of telecommunication, and in particular, to methods and apparatuses for beam management. 
     BACKGROUND 
     Due to increased free space path loss in higher frequency band supported in new radio access (NR), channel/signal transmission relies on highly directional links. In other words, directional beam based communication is needed rather than the omni-directional communication in traditional communication system. Directional links, however, require fine alignment of the transmitter and receiver beams, achieved through a set of operations knowns as beam management. 
     In NR, beam management generally includes the following four different procedures: beam sweeping, beam measurement, beam determination and beam reporting. 
     In beam sweeping procedure, a spatial area can be covered with a set of beams transmitted and received according to pre-specified intervals and directions. In beam measurement procedure, the quality of received reference signals may be evaluated at a network device (such as, a gNB) or at a terminal device (such as, a UE) according to pre-specified metrics (such as, Reference Signal Received Power, RSRP). In beam determination procedure, suitable beam(s) may be selected either at the network device or at the terminal device, according to the measurements obtained with the beam measurement procedure. The terminal device can use the beam reporting procedure to send beam quality and beam decision information to a Radio Access Network (RAN). There procedures are periodically repeated to update the optimal transmitter and receiver beam pair over time. 
     In 3GPP specifications, it has been agreed that layer 1 (L1) RSRP reporting for beam management can be based on the following reference signals: synchronization signal blocks (SSBs), Channel State Information-Reference Signals (CSI-RSs) or a combination thereof. For SSB based beam management, the current specifications only support single-TRP/panel beam reporting. However, in multi-TRP transmission, suitable beam(s) may be selected from different TRPs, while the current specifications do not support multi-TRP/panel beam reporting. 
     SUMMARY 
     In general, example embodiments of the present disclosure provide methods, devices and computer readable mediums for beam management. 
     In a first aspect, there is provided a method implemented at a first network device. 
     According to the method, a first group of resources are determined to be used by a terminal device for determining a first group of beams from the first network device. The first group of resources are different from a second group of resources configured by a second network device to the terminal device for determining a second group of beams from the second network device. The first group of resources are configured to the terminal device. 
     A plurality of synchronization and/or reference signals are transmitted, using the first group of beams, on the first group of resources to the terminal device. 
     In a second aspect, there is provided a method implemented at a terminal device. According to the method, in response to being configured with a first group of resources for determining a first group of beams from a first network device, a first group of RSRPs associated with the first group of beams are determined by detecting a plurality of synchronization and/or reference signals transmitted on the first group of resources. The first group of resources are different from a second group of resources configured by a second network device to the terminal device for determining a second group of beams from the second network device. A result of the determination is indicated to the first network device. 
     In a third aspect, there is provided a device. The device comprises a processor and a memory coupled to the processor. The memory stores instructions that when executed by the processor, cause the device to perform actions. The actions comprise: determining a first group of resources to be used by a terminal device for determining a first group of beams from a first network device; configuring the first group of resources to the terminal device; and transmitting, using the first group of beams, a plurality of synchronization and/or reference signals on the first group of resources to the terminal device, wherein the first group of resources are different from a second group of resources configured by a second network device to the terminal device for determining a second group of beams from the second network device. 
     In a fourth aspect, there is provided a device. The device comprises a processor and a memory coupled to the processor. The memory stores instructions that when executed by the processor, cause the device to perform actions. The actions comprise: in response to being configured with a first group of resources for determining a first group of beams from a first network device, determining a first group of RSRPs associated with the first group of beams by detecting a plurality of synchronization and/or reference signals transmitted on the first group of resources; and indicating a result of the determination to the first network device, indicating a result of the determination to the first network device. 
     In a fifth aspect, there is provided a computer readable medium having instructions stored thereon. The instructions, when executed on at least one processor, cause the at least one processor to carry out the method according to the first aspect of the present disclosure. 
     In a sixth aspect, there is provided a computer readable medium having instructions stored thereon. The instructions, when executed on at least one processor, cause the at least one processor to carry out the method according to the second aspect of the present disclosure. 
     In a seventh aspect, there is provided a computer program product that is tangibly stored on a computer readable storage medium. The computer program product includes instructions which, when executed on at least one processor, cause the at least one processor to carry out the method according to the first aspect or the second aspect of the present disclosure. 
     Other features of the present disclosure will become easily comprehensible through the following description. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Through the more detailed description of some embodiments of the present disclosure in the accompanying drawings, the above and other objects, features and advantages of the present disclosure will become more apparent, wherein: 
         FIG. 1  shows an example communication network in which multi-TRP transmission can be supported; 
         FIG. 2  shows an example communication network in which embodiments of the present disclosure can be implemented; 
         FIG. 3  shows an example process for multi-TRP beam management according to some embodiments of the present disclosure; 
         FIG. 4  shows an example of some embodiments of the present disclosure; 
         FIG. 5  shows an example of some embodiments of the present disclosure; 
         FIG. 6  shows an example of some embodiments of the present disclosure; 
         FIG. 7  shows an example beam report according to some embodiments of the present disclosure; 
         FIG. 8  shows an example beam report according to some embodiments of the present disclosure; 
         FIG. 9  shows an example beam report according to some embodiments of the present disclosure; 
         FIG. 10  shows an example beam report according to some embodiments of the present disclosure; 
         FIG. 11  shows an example beam report according to some embodiments of the present disclosure; 
         FIG. 12  shows a flowchart of an example method in accordance with some embodiments of the present disclosure; 
         FIG. 13  shows a flowchart of an example method in accordance with some embodiments of the present disclosure; and 
         FIG. 14  is a simplified block diagram of a device that is suitable for implementing embodiments of the present disclosure. 
     
    
    
     Throughout the drawings, the same or similar reference numerals represent the same or similar element. 
     DETAILED DESCRIPTION 
     Principle of the present disclosure will now be described with reference to some example embodiments. It is to be understood that these embodiments are described only for the purpose of illustration and help those skilled in the art to understand and implement the present disclosure, without suggesting any limitations as to the scope of the disclosure. The disclosure described herein can be implemented in various manners other than the ones described below. 
     In the following description and claims, unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skills in the art to which this disclosure belongs. 
     As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. The term “includes” and its variants are to be read as open terms that mean “includes, but is not limited to.” The term “based on” is to be read as “at least in part based on.” The term “one embodiment” and “an embodiment” are to be read as “at least one embodiment.” The term “another embodiment” is to be read as “at least one other embodiment.” The terms “first,” “second,” and the like may refer to different or same objects. Other definitions, explicit and implicit, may be included below. 
     In some examples, values, procedures, or apparatus are referred to as “best,” “lowest,” “highest,” “minimum,” “maximum,” or the like. It will be appreciated that such descriptions are intended to indicate that a selection among many used functional alternatives can be made, and such selections need not be better, smaller, higher, or otherwise preferable to other selections. 
     As described above, in NR, beam management generally includes the following four different procedures: beam sweeping, beam measurement, beam determination and beam reporting. In beam sweeping procedure, a spatial area can be covered with a set of beams transmitted and received according to pre-specified intervals and directions. In beam measurement procedure, the quality of received reference signals may be evaluated at a network device (such as, a gNB) or at a terminal device (such as, a UE) according to pre-specified metrics (such as, Reference Signal Received Power, RSRP). In beam determination procedure, suitable beam(s) may be selected either at the network device or at the terminal device, according to the measurements obtained with the beam measurement procedure. The terminal device can use the beam reporting procedure to send beam quality and beam decision information to a Radio Access Network (RAN). There procedures are periodically repeated to update the optimal transmitter and receiver beam pair over time. 
     In 3GPP specifications, it has been agreed that L1-RSRP reporting for beam management can be based on the following reference signals: synchronization signal blocks (SSBs), Channel State Information-Reference Signals (CSI-RSs) or a combination thereof. For SSB based beam management, the current specifications only support single-TRP/panel beam reporting. However, in multi-TRP transmission, suitable beam(s) may be selected from different TRPs, while the current specifications do not support multi-TRP/panel beam reporting. 
       FIG. 1  illustrates an example communication network  100  in which multi-TRP transmission can be supported. As shown in  FIG. 1 , the network  100  includes a gNB  110 , which is coupled with two TRPs  120 - 1  and  120 - 2  (collectively referred to as TRPs  120  or individually referred to as TRP  120 ). The network  100  also includes a UE  130  served by the gNB  110 . Each of the TRPs  120  may include a plurality of beams. For example, as shown in  FIG. 1 , the TRP  120 - 1  may include four beams  121 - 1 ,  121 - 2 ,  121 - 3 , and  121 - 4 , while the TRP  120 - 2  may also include four beams  122 - 1 ,  122 - 2 ,  122 - 3  and  122 - 4 . 
     In the network  100  as shown in  FIG. 1 , suppose that L1-RSRP reporting for beam management is based on SSBs only. As used herein, a “SSB” refers to a transmission unit composed of a primary synchronization signal (PSS), a secondary synchronization signal (SSS) and associated Physical Broadcast Channel (PBCH) signals. For example, one SS block may contain K Orthogonal Frequency Division Multiplexing (OFDM) symbols (K is an integer and K≥4) in which one symbol is used for PSS (also referred to as “PSS symbol”), one symbol is used for SSS (also referred to as “SSS symbol”) and the remaining K−2 symbols are used for PBCH (also referred to as “PBCH symbols”). A SSB burst set may include a number of SSBs, and the SSB burst set may be repeated with a certain periodicity. For example, the periodicity may be one of {5 ms, 10 ms, 20 ms, 40 ms, 80 ms, 160 ms}. Index information associated with the SSBs may be predefined or configured to the UE  130 , so as to facilitate the detection of the SSBs by the UE  130 . 
     The transmission of SSBs within the SS burst set may be confined to a 5 ms window, regardless of the periodicity of the SS block burst set. For different frequency ranges, the maximum number of SSBs within the SSB burst set, L, may be different. For example, for frequency range up to 3 GHz, L can be 4; for frequency range from 3 GHz to 6 GHz, L can be 8; and for frequency range from 6 GHz to 52.6 GHz, L can be 64. 
     In the example as shown in  FIG. 1 , suppose that the maximum number of SSBs within the SSB burst set is 4, and 4 SSBs can be transmitted using different beams from the TRP  120 . Suppose that the cell identities of the TRPs  120 - 1  and  120 - 2  are the same. In this case, for example, the SSB indices associated with the beams  121  may be the same as those associated with the beams  122 , respectively. That is, the SSB index associated with the beam  121 - 1  may be the same as that associated with the beam  122 - 1 ; the SSB index associated with the beam  121 - 2  may be the same as that associated with the beam  122 - 2 ; the SSB index associated with the beam  121 - 3  may be the same as that associated with the beam  122 - 3 ; and the SSB index associated with the beam  121 - 4  may be the same as that associated with the beam  122 - 4 . If the UE  130  detects that the best beam from the TRP  120 - 1  is the beam  121 - 2  and the best beam from the TRP  120 - 2  is the beam  122 - 3  (for example, in beam determination procedure as described above) and reports the SSB indices associated with the beams  121 - 2  and  122 - 3  to the gNB  110  (for example, in beam reporting procedure as described above), the gNB  110  may not know which TRP each of the two beams  121 - 2  and  122 - 3  comes from. 
     Embodiments of the present disclosure provide a solution for beam management, so as to solve the problems above and one or more of other potential problems. With the solution, beam reporting for multi-TRP/panel transmission can be supported. Principle and implementations of the present disclosure will be described in detail below with reference to  FIGS. 2-14 . 
       FIG. 2  shows an example communication network  200  in which embodiments of the present disclosure can be implemented. The network  200  includes two network device  210 - 1  and  210 - 2  (collectively referred to as network devices  210  or individually referred to as network device  210 ) and one terminal device  220  served by the network devices  210 . It is to be understood that the number of network devices and terminal devices is only for the purpose of illustration without suggesting any limitations. The network  200  may include any suitable number of network devices and the terminal devices adapted for implementing embodiments of the present disclosure. 
     As used herein, the term “terminal device” refers to any device having wireless or wired communication capabilities. Examples of the terminal device include, but not limited to, user equipment (UE), personal computers, desktops, mobile phones, cellular phones, smart phones, personal digital assistants (PDAs), portable computers, image capture devices such as digital cameras, gaming devices, music storage and playback appliances, or Internet appliances enabling wireless or wired Internet access and browsing and the like. For the purpose of discussion, in the following, some embodiments will be described with reference to UE as an example of the terminal device  220 . 
     As used herein, the term “network device” or “base station” (BS) refers to a device which is capable of providing or hosting a cell or coverage where terminal devices can communicate. Examples of a network device include, but not limited to, a Node B (NodeB or NB), an Evolved NodeB (eNodeB or eNB), a next generation NodeB (gNB), a Transmission Reception Point (TRP), a Remote Radio Unit (RRU), a radio head (RH), a remote radio head (RRH), a low power node such as a femto node, a pico node, and the like. 
     In some embodiments, for example, the network devices  210 - 1  and  210 - 2  are two TRPs coupled to a same gNB. For example, the network device  210 - 1  may be the TRP  120 - 2  and the network device  210 - 2  may be the TRP  120 - 1 , as shown in  FIG. 1 . 
     Alternatively, in some other embodiments, the network devices  210 - 1  and  210 - 2  may be two separate gNBs in communication with each other. Only for the purpose of discussion without suggesting any limitations to the scope of the present disclosure, in the following, some embodiments will be described with reference to TRPs as examples of the network devices  210 . 
     In the following discussion, only for ease of description, the network device  210 - 1  may also be referred to as “first network device” and the network device  210 - 2  may also be referred to as “second network device”. The coverage of the first network device  210 - 1  (not shown in  FIG. 2 ) may be referred to as a “first cell”, and the coverage of the second network device  210 - 2  (not shown in  FIG. 2 ) may be referred to as a “second cell”. For example, the first cell may be the same as or different from the second cell. 
     The network devices  210  may communicate with the terminal device  220 . The communications in the network  200  may conform to any suitable standards including, but not limited to, Long Term Evolution (LTE), LTE-Evolution, LTE-Advanced (LTE-A), Wideband Code Division Multiple Access (WCDMA), Code Division Multiple Access (CDMA) and Global System for Mobile Communications (GSM) and the like. Furthermore, the communications may be performed according to any generation communication protocols either currently known or to be developed in the future. Examples of the communication protocols include, but not limited to, the first generation (1G), the second generation (2G), 2.5G, 2.75G, the third generation (3G), the fourth generation (4G), 4.5G, the fifth generation (5G) communication protocols. 
     In some embodiments, for example, during an initial access procedure, the terminal device  220  may access to the second network device  210 - 2  and a set of resources for transmitting synchronization and/or reference signals may be configured by the second network device  210 - 2  to the terminal device  220 . After initial access, the first network device  210 - 1  may configure some additional resources for multi-TRP beam management.  FIG. 3  shows an example process  300  for multi-TRP beam management according to some embodiments of the present disclosure. For the purpose of discussion, the process  300  will be described with reference to  FIG. 2 . The process  300  may involve the terminal device  220  and one or more network devices  210  serving the terminal device  220 . 
     As shown in  FIG. 2 , the first network device  210 - 1  determines ( 310 ) a first group of resources to be used by the terminal device  210  for determining a first group of beams from the first network device  210 - 1 . In some embodiments, the first group of resources may be different from a second group of resources configured by the second network device  210 - 2  to the terminal device  220 . The first network device  210 - 1  then configures ( 320 ) the first group of resources to the terminal device  220 . 
     In some embodiments, the first and second group of resources may be SSB resources. As used herein, a “SSB resource” refers to one or more resource elements in time, frequency, and/or code domain allocated for transmission of SSBs. In some other embodiments, the first and second group of resources may be CSI-RS resources. As used herein, a “CSI-RS resource” refers to one or more resource elements in time, frequency, and/or code domain allocated for transmission of CSI-RS. Only for the purpose of illustration, in the following, some embodiments will be described with SSB resources as examples of the first or second group of resources. For example, the first group of resources may also be referred to as a “first group of SSB resources”, and the second group of resources may also be referred to as a “second group of SSB resources”. However, it is to be understood that embodiments of the present disclosure are also applicable to resources for transmitting reference signals (such as, CSI-RS), and the present disclosure will not be limited in this aspect. 
     In some embodiments, the first and second groups of SSB resources may be associated with different resource allocation in time, frequency and/or code domain. For example, in some embodiments, the first and second groups of SSB resources may be associated with different periodicities and/or offsets in time domain. Alternatively, or in addition, in some embodiments, the first and second groups of SSB resources may be associated with different cell identities. Alternatively, or in addition, in some embodiments, the first and second groups of SSB resources may be associated with different locations and/or offsets in frequency domain. 
     In some embodiments, the first groups of SSB resources may include M SSB resources, while the second groups of SSB resources may include N SSB resources, where M and N are both integers and M may be same as or different from N. In this case, the terminal device  220  can measure RSRPs and/or beams based on M+N SSB resources. 
     In some embodiments, the first and second groups of SSB resources may be included in a same SSB resource set. Alternatively, in some other embodiments, the first and second groups of SSB resources may be included in different SSB resource sets or different subsets of a SSB resource set. 
     In some embodiments, for different sets or subsets of SSB resources, the cell identities (IDs) for generating SSB sequences may be different. That is, the first and second groups of SSB resources may be associated with different IDs for generating SSB sequences. For example, the ID may be used to generate the sequence for PSS and/or SSS to be transmitted on the SSB resource. As another example, the ID may be used to generate the sequence for Demodulation Reference Signal (DMRS) of PBCH and/or scrambling sequence for PBCH to be transmitted on the SSB resource. In some embodiments, the first groups of SSB resources may include M SSB resources, while the second groups of SSB resources may include N SSB resources, where M and N are both integers and M may be same as or different from N. For example, for the first cell or the first network device  210 - 1  (such as, TRP or panel), the ID for generating SSB sequences may be represented as ID 1 . For the second cell or the second network device  210 - 2 , the ID for generating SSB sequences may be represented as ID 2 . For example, ID 1  may be different from ID 2 . Additionally, in some embodiments, resource allocation in time, frequency and/or code domain for the first group of SSB resources may be same as that for the second group of SSB resources. In this case, indices of the SSB resources for different network devices can be distinguished implicitly. For example, the indices for the first groups of SSB resources may be interpreted as 0, 1, 2 . . . M−1, while the indices for the second group of SSB resources may be interpreted as M, M+1 . . . N+M−1. 
       FIG. 4  shows an example of such embodiments. Specifically, for example,  FIG. 4  shows the TRPs  120  and the UE  130  as shown in  FIG. 1 . In the example as shown in  FIG. 4 , suppose that the maximum number of SSBs within the SSB burst set is 4, and the indices for the 4 SSBs are 0, 1, 2 and 3 originally. As shown in  FIG. 4 , SSB resources for the TRP  120 - 1  and SSB resources for the TRP  120 - 2  share the same resource allocation pattern in time, frequency and/or code domain. However, for the TRP  120 - 1 , the ID for generating SSB sequences may be N_ID 1 ; while for the TRP  120 - 2 , the ID for generating SSB sequences may be N_ID 2 , where N_ID 1  is different from N_ID 2 . For initial access, the UE  130  may access to the TRP  120 - 1  and obtain the cell ID N_ID 1 . For N_ID 1 , the indices for the 4 SSBs may be interpreted as 0, 1, 2 and 3 by both of the gNB  110  and the UE  130 . After initial access, another cell ID N_ID 2  may be configured by the TRP  120 - 2  to the UE  130 . For N_ID 2 , the indices for the 4 SSBs may be interpreted as 4, 5, 6 and 7 by both of the gNB  110  and the UE  130 , rather than the original indices 0, 1, 2 and 3. 
     In some embodiments, the terminal device  220  may be configured with two sets/subsets of SSB resources. For the first set/subset of SSB resources, a first ID may be used for sequence generation. For the second set/subset of SSB resources, a second ID may be used for sequence generation. In some embodiments, the first ID for sequence generation may be same as the cell ID of the serving cell. For example, the first ID for sequence generation may be obtained from the initial access procedure. In some embodiments, the terminal device  220  may be configured with a second ID for generating SSB sequences for the second set/subset of SSB resources. In some embodiments, the value of the second ID may be different from the value of the first ID. 
     In some embodiments, for different sets or subsets of SSB resources, the resource allocation in time domain may be different. For example, the first and second groups of SSB resources may be associated with different periodicities and/or offsets in time domain. In some embodiments, the first groups of SSB resources may include M SSB resources, while the second groups of SSB resources may include N SSB resources, where M and N are both integers and M may be same as or different from N. For example, for the first cell or the first network device  210 - 1  (such as, TRP or panel), the offset in time domain may be represented as T_O 1 . For the second cell or the second network device  210 - 2 , the offset in time domain may be represented as T_O 2 , which may be different from T_O 1 . As another example, for the first group of SSB resources, there may be no offset in time domain, or alternatively, the offset in time domain may be represented as 0. For the second group of SSB resources, the offset in time domain may be represented as T_O 2 , where the offset in time domain is the time interval between the first group of SSB resources and the second group of SSB resources. 
     In some embodiments, the terminal device  220  may be configured with two sets or subsets of SSB resources, and the terminal device  220  may be configured with an offset value only for the second set or subset of SSB resources, where the offset value indicates the time offset between the first set or subset of SSB resources and the second set or subset of SSB resources. 
     In some embodiments, the offset in time domain may refer to a time offset in a SS burst set within the 5 ms window. In some embodiments, the offset in time domain may refer to a time offset for the whole SS burst set. For example, the offset may be a multiple of 5 ms. In some embodiments, the available offset may be based on the periodicity of the SS burst set in the first and/or second group of SSB resources. For example, if the periodicity is 5 ms, there may be no available offset values. As another example, if the periodicity is 10 ms, the available offset value may be 5 ms. As another example, if the periodicity is 20 ms, the available offset value may be any of {5 ms, 10 ms, 15 ms}. As another example, if the periodicity is 40 ms, the available offset value may be any of {5 ms, 10 ms, 15 ms, 20ms, 25 ms, 3 0ms, 35 ms}. As another example, if the periodicity is 80 ms, the available offset value may be any of X*5 ms, where X∈{1, 2, 3, . . . 14, 15}. As another example, if the periodicity is 160 ms, the available offset value may be any of X*5 ms, where X∈{1, 2, 3, . . . 30, 31}. In this case, indices of the SSB resources for different network devices can be distinguished implicitly. For example, the indices for the first groups of SSB resources may be interpreted as 0, 1, 2 . . . M−1, while the indices for the second group of SSB resources may be interpreted as M, M+1 . . . N+M−1. 
       FIG. 5  shows an example of such embodiments. Specifically, for example,  FIG. 5  shows SSB resources for the TRP  120 - 1  and SSB resources for the TRP  120 - 2 . In the example as shown in  FIG. 5 , suppose that the maximum number of SSBs within the SSB burst set is 4, and the indices for the 4 SSBs are 0, 1, 2 and 3 originally. As shown in  FIG. 5 , the SSB resources for the TRP  120 - 1  and the SSB resources for the TRP  120 - 2  are associated with different offsets in time domain. For example, for the TRP  120 - 1 , the time offset for SSB resources may be T_O 1 ; while for the TRP  120 - 2 , the time offset for SSB resources may be T_O 2 , which is different from T_O 1 . As shown in  FIG. 5 , the difference between the time offsets T_O 1  and T_O 2  is represented as  510 . 
     For initial access, the UE  130  may access to the TRP  120 - 1  and obtain the time offset T_O 1 . The UE  130  can determine the locations of the SSB resources associated with the TRP  120 - 1  based on the time offset T_O 1 . For the time offset T_O 1 , the indices for the 4 SSBs may be interpreted as 0, 1, 2 and 3 by both of the gNB  110  and the UE  130 . After initial access, another time offset T_O 2  may be configured by the TRP  120 - 2  to the UE  130 . The UE  130  can determine the locations of the SSB resources associated with the TRP  120 - 2  based on the time offset T_O 2 . For the time offset T_O 2 , the indices for the 4 SSBs may be interpreted as 4, 5, 6 and 7 by both of the gNB  110  and the UE  130 , rather than the original indices 0, 1, 2 and 3. 
     In some embodiments, for example, there may be no time offset for SSB resources for the TRP  120 - 1 , or alternatively, the time offset T_O 1  may be 0; while for the TRP  120 - 2 , the time offset for SSB resources may be T_O 2 , which indicates the interval between the first group of SSB resources and the second group of SSB resources. 
     For initial access, the UE  130  may access to the TRP  120 - 1  and obtain the time locations of SSB resources associated with the TRP  120 - 1 . For the SSB resources associated with the TRP  120 - 1 , the indices for the 4 SSBs may be interpreted as 0, 1, 2 and 3 by both of the gNB  110  and the UE  130 . After initial access, a time offset T_O 2  may be configured to the UE  130 . The UE  130  can determine the locations of SSB resources associated with the TRP  120 - 2  based on the time offset T_O 2 . For the SSB resources associated with the TRP  120 - 2 , the indices for the 4 SSBs may be interpreted as 4, 5, 6 and 7 by both of the gNB  110  and the UE  130 , rather than the original indices 0, 1, 2 and 3. 
     In some embodiments, for different sets or subsets of SSB resources, the resource allocation in frequency domain may be different. For example, the first and second groups of SSB resources may be associated with different offsets in frequency domain. In some embodiments, the first groups of SSB resources may include M SSB resources, while the second groups of SSB resources may include N SSB resources, where M and N are both integers and M may be same as or different from N. For example, for the first cell or the first network device  210 - 1  (such as, TRP or panel), locations of the first group of SSB resources in frequency domain may be represented as F1. For the second cell or the second network device  210 - 2 , locations of the second group of SSB resources in frequency domain may be represented as F2, which may be different from F1. For example, there may be an offset between the locations of the second group of SSB resources and the locations of the first group of SSB resources. For example, the frequency offset between the second group of SSB resources and the first group of SSB resources may be represented as a number of physical resource blocks (PRBs). As another example, the frequency offset between the second group of SSB resources and the first group of SSB resources may be represented as a number of resource elements (REs). 
     In some embodiments, the terminal device  220  may be configured with two sets or subsets of SSB resources, and the terminal device  220  may be configured with an offset value only for the second set or subset of SSB resources, where the offset value indicates the frequency offset between the first set or subset of SSB resources and the second set or subset of SSB resources. In some embodiments, the terminal device  220  may be configured with two sets or subsets of SSB resources, and the terminal device  220  may be configured with a frequency domain location only for the second set or subset of SSB resources, where the frequency domain location may indicate a common resource block (RB) index relative to the common RB #0 or a common resource element (RE) index relative to the RE #0 in the common RB #0. 
     As such, indices of the SSB resources for different network devices can be distinguished implicitly. For example, the indices for the first groups of SSB resources may be interpreted as 0, 1, 2 . . . M−1, while the indices for the second group of SSB resources may be interpreted as M, M+1 . . . N+M−1. 
       FIG. 6  shows an example of such embodiments. Specifically, for example,  FIG. 6  shows SSB resources for the TRP  120 - 1  and SSB resources for the TRP  120 - 2 . In the example as shown in  FIG. 6 , suppose that the maximum number of SSBs within the SSB burst set is 4, and the indices for the 4 SSBs are 0, 1, 2 and 3 originally. As shown in  FIG. 6 , the SSB resources for the TRP  120 - 1  and the SSB resources for the TRP  120 - 2  are associated with different offsets in frequency domain. For example, for the TRP  120 - 1 , the frequency offset for SSB resources may be F_O 1 ; while for the TRP  120 - 2 , the time offset for SSB resources may be F_O 2 , which is different from F_O 1 . As shown in  FIG. 6 , the difference between the frequency offsets F_O 1  and F_O 2  is represented as  610 . 
     For initial access, the UE  130  may access to the TRP  120 - 1  and obtain the frequency offset F_O 1 . The UE  130  can determine the locations of the SSB resources associated with the TRP  120 - 1  based on the frequency offset F_O 1 . For the frequency offset F_O 1 , the indices for the 4 SSBs may be interpreted as 0, 1, 2 and 3 by both of the gNB  110  and the UE  130 . After initial access, another frequency offset F_O 2  may be configured by the TRP  120 - 2  to the UE  130 . The UE  130  can determine the locations of the SSB resources associated with the TRP  120 - 2  based on the frequency offset F_O 2 . For the frequency offset F_O 2 , the indices for the 4 SSBs may be interpreted as 4, 5, 6 and 7 by both of the gNB  110  and the UE  130 , rather than the original indices 0, 1, 2 and 3. 
     With reference back to  FIG. 2 , the first network device  210 - 1  then transmits ( 330 ), using the first group of beams, a plurality of synchronization and/or reference signals (such as SSBs and/or CSI-RS) on the first group of resources to the terminal device  220 . At the terminal device  220 , in response to being configured with the first group of resources for determining the first group of beams from the first network device  210 - 1 , the terminal device  220  determines ( 340 ) a first group of RSRPs associated with the first group of beams by detecting the plurality of synchronization and/or reference signals transmitted on the first group of resources. The terminal device  220  then indicates ( 350 ) a result of the determination to the first network device  210 - 1 . 
     In some embodiments, for multi-TRP beam management, a plurality of SSB/CSI-RS resources may be configured to the terminal device  220 . For example, as described above, the first group of SSB/CSI-RS resources may be configured for transmission of SSBs/CSI-RS from the first network device  210 - 1  to the terminal device  220 . The second group of SSB/CSI-RS resources may be configured for transmission of SSBs/CSI-RS from the second network device  210 - 2  to the terminal device  220 . In some embodiments, the first and second groups of SSB/CSI-RS resources may be included in a same SSB/CSI-RS resource set. Alternatively, in some other embodiments, the first and second groups of SSB/CSI-RS resources may be included in different SSB/CSI-RS resource sets or different subsets of a SSB/CSI-RS resource set. 
     In some embodiments, the terminal device  220  may determine a first group of RSRPs associated with the first group of beams from the first network device  210 - 1  by detecting the plurality of SSBs/CSI-RS transmitted on the first group of SSB/CSI-RS resources. Additionally, the terminal device  220  may further determine a second group of RSRPs associated with the second group of beams from the second network device  210 - 2  by detecting a plurality of SSBs/CSI-RS transmitted on the second group of SSB/CSI-RS resources. 
     In some embodiments, the terminal device  220  may be configured with two sets/subsets of SSB/CSI-RS resources. The first set/subset of SSB/CSI-RS resources may include M SSB/CSI-RS resources, while the second set/subset of SSB/CSI-RS resources may include N SSB/CSI-RS resources, where M and N are both integers and M may be same as or different from N. 
     In some embodiments, the terminal device  220  may be configured with two sets/subsets of SSB resources. The first set/subset of SSB resources may include M SSB resources, while the second set/subset of SSB resources may include N SSB resources, where M and N are both integers and M may be same as or different from N. In some embodiments, the number of bits for reporting SS/PBCH Block Resource Indicator (SSBRI) may be ceil(log 2 (M+N)). 
     In some embodiments, the terminal device  220  may be configured with two sets/subsets of CSI-RS resources. The first set/subset of CSI-RS resources may include M CSI-RS resources, while the second set/subset of CSI-RS resources may include N CSI-RS resources, where M and N are both integers and M may be same as or different from N. In some embodiments, the number of bits for reporting CSI-RS Resource Indicator (CRI) may be ceil(log 2 (M+N)) bits. 
     In some embodiments, the terminal device  220  may be configured to report a certain number of RSRPs as well as their associated SSB/CSI-RS resource indices (for example, SSBRI or CRI) to the network device for beam management. For example, the number can be represented as X. In some embodiments, the X SSB/CSI-RS resources (corresponding to the X RSRPs) to be reported may come from different sets of SSB/CSI-RS resources. For example, X1 resources out of the X SSB/CSI-RS resources may come from the first group of SSB/CSI-RS resources, while X2 resources out of the X SSB/CSI-RS resources may come from the second group of SSB/CSI-RS resources, where X1+X2=X. The first and second groups of SSB/CSI-RS resources may be included in two different SSB/CSI-RS resource sets. The terminal device  220  may need to report X1 RSRPs from the first group of RSRPs as well as respective indices of the X1 resources from the first group of SSB/CSI-RS resources to the network device. In addition, the terminal device  220  may also report X2 RSRPs from the second group of RSRPs as well as respective indices of the X2 resources from the second group of SSB/CSI-RS resources to the network device. 
     In some embodiments, an absolute value of RSRP may be reported by the terminal device  220  for a SSB/CSI-RS resource associated with the maximum RSRP among the first and second groups of RSRPs. For the rest of SSB/CSI-RS resources among the first and second groups of SSB/CSI-RS resources, differential values of RSRPs relative to the maximum RSRP may be reported by the terminal device  220 . In addition, one additional bit may be used to indicate whether the maximum RSRP is from the first group of RSRPs or the second group of RSRPs. In this way, the overhead for beam reporting can be reduced. For example, the number of bits for reporting the absolute value of RSRP may be 7, and the number of bits for reporting each of the differential values of RSRPs may be 4. As another example, the number of bits for SS/PBCH block or CSI-RS resource indicator (SSBRI/CRI) may be ceil(log 2 M) if the SSB/CSI-RS resource is from the first groups of SSB/CSI-RS resources, and the number of bits for SS/PBCH block or CSI-RS resource indicator (SSBRI/CRI) may be ceil(log 2 N) if the SSB/CSI-RS resource is from the second groups of SSB/CSI-RS resources. 
       FIG. 7  shows an example beam report  700  according to some embodiments of the present disclosure. As shown in  FIG. 7 , a field  710  may be used to indicate whether the maximum RSRP is from the first group of RSRPs or the second group of RSRPs. The size of the field  710  may be 1 bit. For example, if the value of the field  710  is ‘0’, it may indicate that the maximum RSRP is from the first group of RSRPs; while if the value of the field  710  is ‘1’, it may indicate that the maximum RSRP is from the second group of RSRPs. In the example as shown in  FIG. 7 , suppose that the value of the field  710  is ‘0’. That is, the maximum RSRP is from the first group of RSRPs. Fields  720 - 1 ˜ 720 -X1 may be used to indicate respective indices of the X1 resources from the first group of SSB/CSI-RS resources to be reported, each of which may have a size of ceil(log 2 M) bits. Fields  730 - 1 ˜ 730 -X2 may be used to indicate respective indices of the X2 resources from the second group of SSB/CSI-RS resources to be reported, each of which may have a size of ceil(log 2 N) bits. Fields  740 - 1 ˜ 740 -X1 may be used to indicate X1 RSRPs from the first group of RSRPs to be reported, and fields  750 - 1 ˜ 750 -X2 may be used to indicate X2 RSRPs from the second group of RSRPs to be reported. For example, the field  740 - 1  may be used to indicate an absolute value of the maximum RSRP, which may have a size of 7 bits. The fields  740 - 2 ˜ 740 -X1 and  750 - 1 ˜ 750 -X2 may be used to indicate differential values of RSRPs relative to the maximum RSRP, each of which may have a size of 4 bits. 
     Alternatively, in some embodiments, an absolute value of RSRP may be reported by the terminal device  220  for a SSB/CSI-RS resource associated with a first RSRP from the first group of RSRPs, where the first RSRP may be the maximum one among the first group of RSRPs. For the rest of SSB/CSI-RS resources among the first and second groups of SSB/CSI-RS resources, differential values of RSRPs may be reported by the terminal device  220 . For example, the terminal device  220  may indicate a differential value of a second RSRP from the second group of RSRPs relative to the first RSRP, where the second RSRP may be the maximum one among the second group of RSRPs. The terminal device  220  may also indicate a differential value of a third RSRP from the first group of RSRPs relative to the first RSRP and a differential value of a fourth RSRP from the second group of RSRPs relative to the first or second RSRP. Since the maximum RSRP among the second group of RSRPs (that is, the second RSRSP) may greater or less than the first RSRP, the differential value of the second RSRP may be negative or positive. In some embodiments, at least for the second RSRP from the second group of RSRPs, the number of bits used to indicate the differential value for the second RSRP may be different from other differential values. In this way, the overhead for beam reporting can be reduced. 
       FIG. 8  shows an example beam report  800  according to some embodiments of the present disclosure. As shown in  FIG. 8 , Fields  810 - 1 ˜ 810 -X1 may be used to indicate respective indices of the X1 resources from the first group of SSB/CSI-RS resources to be reported, each of which may have a size of ceil(log 2 M) bits. Fields  820 - 1 ˜ 820 -X2 may be used to indicate respective indices of the X2 resources from the second group of SSB/CSI-RS resources to be reported, each of which may have a size of ceil(log 2 N) bits. Fields  830 - 1 ˜ 830 -X1 may be used to indicate X1 RSRPs from the first group of RSRPs to be reported, and fields  840 - 1 ˜ 840 -X2 may be used to indicate X2 RSRPs from the second group of RSRPs to be reported. For example, the field  830 - 1  may be used to indicate an absolute value of the maximum RSRP among the first group of RSRPs (that is, the first RSRP), which may have a size of 7 bits. The field  840 - 1  may be used to indicate a differential value of the maximum RSRP among the second group of RSRPs (that is, the second RSRP) relative to the first RSRP, which may have a size of P bits. For example, P&gt;4 and P≤7. That is, P can be 5, 6 or 7. The fields  830 - 2 ˜ 830 -X1 may be used to indicate differential values of RSRPs from the first group of RSRPs relative to the first RSRP, each of which may have a size of 4 bits. The fields  840 - 2 ˜ 840 -X2 may be used to indicate differential values of RSRPs relative to the first or second RSRP, each of which may have a size of 4 bits. 
     In some embodiments, the differential values of RSRPs from the second group of RSRPs relative to the first RSRP and the differential values of RSRPs from the first group of RSRPs relative to the first RSRP may be associated with different parameters. For example, such parameters may include at least one of the following: positive or negative of a differential value, a step size for determining the differential value and the maximum value among the differential values. In some embodiments, the step size for determining the differential values of RSRPs from the first group of RSRPs relative to the first RSRP may be 2 dB, while the step size for determining the differential values of RSRPs from the second group of RSRPs relative to the first RSRP may be Y dB, where Y&gt;2. For example, Y may be 3, 4 or 5. In some embodiments, all of the differential values of RSRPs from the first group of RSRPs relative to the first RSRP may be non-negative or non-positive. However, the differential values of RSRPs from the second group of RSRPs relative to the first RSRP may include positive values, negative values and 0. In some embodiments, the maximum value among the differential values of RSRPs from the first group of RSRPs relative to the first RSRP may be Z1, while the maximum value among the differential values of RSRPs from the second group of RSRPs relative to the first RSRP may be Z2. In some embodiments, Z1 may be different from Z2. For example, Z1&gt;Z2. 
     Alternatively, in some embodiments, an absolute value of RSRP may be reported by the terminal device  220  for a SSB/CSI-RS resource associated with a first RSRP from the first group of RSRPs, where the first RSRP may be the maximum one among the first group of RSRPs. For the rest of SSB/CSI-RS resources among the first and second groups of SSB/CSI-RS resources, differential values of RSRPs may be reported by the terminal device  220 . For example, the terminal device  220  may indicate a differential value of a second RSRP from the second group of RSRPs relative to the first RSRP, where the second RSRP may be the maximum one among the second group of RSRPs. The terminal device  220  may also indicate a differential value of a third RSRP from the first group of RSRPs relative to the first RSRP and a differential value of a fourth RSRP from the second group of RSRPs relative to the first RSRP. Since the maximum RSRP among the second group of RSRPs (that is, the second RSRSP) may greater or less than the first RSRP, the differential value of the second RSRP may be negative or positive. In some embodiments, at least for the second RSRP from the second group of RSRPs, one additional bit may be used to indicate whether the first RSRP is greater than the second RSRP or not. In this way, the overhead for beam reporting can be reduced. 
       FIG. 9  shows an example beam report  900  according to some embodiments of the present disclosure. As shown in  FIG. 9 , Fields  910 - 1 ˜ 910 -X1 may be used to indicate respective indices of the X1 resources from the first group of SSB/CSI-RS resources to be reported, each of which may have a size of ceil(log 2 M) bits. Fields  920 - 1 ˜ 920 -X2 may be used to indicate respective indices of the X2 resources from the second group of SSB/CSI-RS resources to be reported, each of which may have a size of ceil(log 2 N) bits. Fields  930 - 1 ˜ 930 -X1 may be used to indicate X1 RSRPs from the first group of RSRPs to be reported, and fields  940 - 1 ˜ 940 -X2 may be used to indicate X2 RSRPs from the second group of RSRPs to be reported. In addition, a field  950  may be used to indicate whether the maximum RSRP among the first group of RSRPs is greater than the maximum RSRP among the second group of RSRPs or not. For example, the field  930 - 1  may be used to indicate an absolute value of the maximum RSRP among the first group of RSRPs (that is, the first RSRP), which may have a size of 7 bits. The field  940 - 1  may be used to indicate a differential value of the maximum RSRP among the second group of RSRPs (that is, the second RSRP) relative to the first RSRP, which may have a size of 4 bits. The fields  930 - 2 ˜ 930 -X1 and  840 - 2 ˜ 840 -X2 may be used to indicate differential values of RSRPs from the first and second groups of RSRPs relative to the first RSRP, each of which may have a size of 4 bits. 
     Alternatively, in some embodiments, an absolute value of RSRP may be reported by the terminal device  220  for a SSB/CSI-RS resource associated with a first RSRP from the first group of RSRPs, where the first RSRP may be the maximum one among the first group of RSRPs. An absolute value of RSRP may be reported by the terminal device  220  for a SSB/CSI-RS resource associated with a second RSRP from the second group of RSRPs, where the second RSRP may be the maximum one among the second group of RSRPs. For the rest of SSB/CSI-RS resources among the first group of SSB/CSI-RS resources, differential values of RSRPs relative to the first RSRP may be reported by the terminal device  220 . For the rest of SSB/CSI-RS resources among the second group of SSB/CSI-RS resources, differential values of RSRPs relative to the second RSRP may be reported by the terminal device  220 . In this way, the overhead for beam reporting can be reduced. 
       FIG. 10  shows an example beam report  1000  according to some embodiments of the present disclosure. As shown in  FIG. 10 , Fields  1010 - 1 ˜ 1010 -X1 may be used to indicate respective indices of the X1 resources from the first group of SSB/CSI-RS resources to be reported, each of which may have a size of ceil(log 2 M) bits. Fields  1020 - 1 ˜ 1020 -X2 may be used to indicate respective indices of the X2 resources from the second group of SSB/CSI-RS resources to be reported, each of which may have a size of ceil(log 2 N) bits. Fields  1030 - 1 ˜ 1030 -X1 may be used to indicate X1 RSRPs from the first group of RSRPs to be reported, and fields  1040 - 1 ˜ 1040 -X2 may be used to indicate X2 RSRPs from the second group of RSRPs to be reported. For example, the field  1030 - 1  may be used to indicate an absolute value of the maximum RSRP among the first group of RSRPs (that is, the first RSRP), which may have a size of 7 bits. The field  1040 - 1  may be used to indicate an absolute value of the maximum RSRP among the second group of RSRPs (that is, the second RSRP), which may have a size of 7 bits. The fields  1030 - 2 ˜ 1030 -X1 may be used to indicate differential values of RSRPs from the first group of RSRPs relative to the first RSRP, each of which may have a size of 4 bits. The fields  1040 - 2 ˜ 1040 -X2 may be used to indicate differential values of RSRPs from the second group of RSRPs relative to the second RSRP, each of which may have a size of 4 bits. 
     In some embodiments, the terminal device  220  may be configured to report a certain number of RSRPs as well as their associated SSB/CSI-RS resource indices to the network device for beam management. For example, the number can be represented as X. In some embodiments, the X SSB/CSI-RS resources (corresponding to the X RSRPs) to be reported may come from a same SSB/CSI-RS resource set. For example, X1 resources out of the X SSB/CSI-RS resources may come from the first group of SSB/CSI-RS resources, while X2 resources out of the X SSB/CSI-RS resources may come from the second group of SSB/CSI-RS resources, where X1+X2=X. The first and second groups of SSB/CSI-RS resources are different subsets of the same SSB/CSI-RS resource set. The terminal device  220  may need to report X1 RSRPs from the first group of RSRPs as well as respective indices of the X1 resources from the first group of SSB/CSI-RS resources to the network device. In addition, the terminal device  220  may also report X2 RSRPs from the second group of RSRPs as well as respective indices of the X2 resources from the second group of SSB/CSI-RS resources to the network device. 
     In some embodiments, an absolute value of RSRP may be reported by the terminal device  220  for a SSB/CSI-RS resource associated with the maximum RSRP among the first and second groups of RSRPs. For the rest of SSB/CSI-RS resources among the first and second groups of SSB/CSI-RS resources, differential values of RSRPs relative to the maximum RSRP may be reported by the terminal device  220 . 
       FIG. 11  shows an example beam report  1100  according to some embodiments of the present disclosure. As shown in  FIG. 11 , fields  1110 - 1 ˜ 1110 -X may be used to indicate respective indices of the X resources from the first and second groups of 
     SSB/CSI-RS resources to be reported, each of which may have a size of ceil(log 2 (N+M)) bits. Fields  1120 - 1 ˜ 1120 -X may be used to indicate X RSRPs from the first and second groups of RSRPs to be reported. For example, the field  1120 - 1  may be used to indicate an absolute value of the maximum RSRP, which may have a size of 7 bits. The fields  1120 - 2 ˜ 1120 -X may be used to indicate differential values of RSRPs relative to the maximum RSRP, each of which may have a size of 4 bits. 
     In some embodiments, for multi-TRP beam management, a plurality of SSB and/or CSI-RS resources may be configured to the terminal device  220 . For example, in the network as shown in  FIG. 2 , during the initial access procedure, the terminal device  220  may access to the second network device  210 - 2  and a set of SSB resources (also referred to as “initial access SSB resources”) may be configured by the second network device  210 - 2  to the terminal device  220 . After initial access, the first network device  210 - 1  may configure some additional SSB resources for multi-TRP beam management. In some embodiments, only a subset of the set of initial access SSB resources can be configured by the first network device  210 - 1  for multi-TRP beam management. For example, the set of initial access SSB resources may include R SSB resource in total. For example, Q SSB resources out of the R SSB resources can be configured for multi-TRP beam management, where Q≤R. 
     In some embodiments, for beam reporting, some combinations of beams from different network devices can be restricted from being reported. For example, in the example as shown in  FIG. 1 , a combination of the beam  121 - 1  from the TRP  120 - 1  and the beam  121 - 4  from the TRP  120 - 2  may be restricted from being reported. As such, the overhead for beam reporting can be further reduced. 
       FIG. 12  shows a flowchart of an example method  1200  in accordance with some embodiments of the present disclosure. The method  1200  can be implemented at the network device  210  (for example, the network device  210 - 1 ) as shown in  FIG. 2 . For the purpose of discussion, the method  1200  will be described from the perspective of the network device  210 - 1  with reference to  FIG. 2 . 
     At block  1210 , the first network device (for example, the network device  210 - 1 ) determines a first group of resources to be used by a terminal device (for example, the terminal device  220 ) for determining a first group of beams from the first network device. In some embodiments, the first group of resources may be different from a second group of resources configured by a second network device (for example, the network device  210 - 2 ) to the terminal device for determining a second group of beams from the second network device. 
     In some embodiments, the first network device determines the first group of resources such that the first and second groups of resources are associated with different resource allocation in time, frequency and/or code domain. 
     In some embodiments, the first network device determines the first group of resources such that the first and second groups of resources are associated with different cell identities. 
     In some embodiments, the first network device determines the first group of resources such that the first and second groups of resources are associated with different offsets in time domain. 
     In some embodiments, the first network device determines the first group of resources such that the first and second groups of resources are associated with different offsets in frequency domain. 
     In some embodiments, the first and second groups of resources are SSB resources, and the first and second groups of resources are included in a same SSB resource set. 
     In some embodiments, the first and second groups of resources are SSB resources, and the first and second groups of resources are included in different SSB resource sets. 
     In some embodiments, the first network device is a first Transmission Reception Point (TRP) and the second network device is a second TRP, and the first and second TRPs are coupled to a same base station. 
     At block  1220 , the first network device configures the first group of resources to the terminal device. 
     At block  1230 , the first network device transmits, using the first group of beams, a plurality of synchronization and/or reference signals on the first group of resources to the terminal device. 
       FIG. 13  shows a flowchart of an example method  1300  in accordance with some embodiments of the present disclosure. The method  1300  can be implemented at the terminal device  220  as shown in  FIG. 2 . For the purpose of discussion, the method  1300  will be described from the perspective of the terminal device  220  with reference to  FIG. 2 . 
     At block  1310 , in response to being configured with a first group of SSB/CSI-RS resources for determining a first group of beams from a first network device (for example, the network device  210 - 1 ), the terminal device determines a first group of Reference Signal 
     Received Powers (RSRPs) associated with the first group of beams by detecting a plurality of synchronization and/or reference signals transmitted on the first group of resources. In some embodiments, the first group of resources may be different from a second group of resources configured by a second network device (for example, the network device  210 - 2 ) to the terminal device for determining a second group of beams from the second network device. 
     At block  1320 , the terminal device indicates a result of the determination to the first network device. 
     In some embodiments, the first and second groups of resources are associated with different resource allocation in time, frequency and/or code domain. 
     In some embodiments, the first and second groups of resources are associated with different cell identities. 
     In some embodiments, the first and second groups of resources are associated with different offsets in time domain. 
     In some embodiments, the first and second groups of resources are associated with different offsets in frequency domain. 
     In some embodiments, the first and second groups of resources are SSB resources, and the first and second groups of resources are included in a same SSB resource set. 
     In some embodiments, the first and second groups of resources are SSB resources, and the first and second groups of resources are included in different SSB resource sets. 
     In some embodiments, the first network device is a first Transmission Reception Point (TRP) and the second network device is a second TRP, and the first and second TRPs are coupled to a same base station. 
     In some embodiments, the terminal device may further determine a second group of RSRPs associated with the second group of beams by detecting a plurality of synchronization and/or reference signals transmitted on the second group of resources. 
     In some embodiments, indicating the result of the determination to the first network device comprises: indicating, to the first network device, a first number of RSRPs from the first group of RSRPs and a second number of RSRPs from the second group of RSRPs. 
     In some embodiments, indicating the first number of RSRPs from the first group of RSRPs and the second number of RSRPs from the second group of RSRPs comprises: indicating an absolute value of the maximum RSRP among the first and second groups of RSRPs; indicating at least one differential value of at least one RSRP from the first and second groups of RSRPs relative to the maximum RSRP; and indicating whether the maximum RSRP is from the first group of RSRPs or the second group of RSRPs. 
     In some embodiments, indicating the first number of RSRPs from the first group of RSRPs and the second number of RSRPs from the second group of RSRPs comprises: indicating an absolute value of a first RSRP from the first group of RSRPs, the first RSRP being the maximum one among the first group of RSRPs; indicating a differential value of a second RSRP from the second group of RSRPs relative to the first RSRP, the second RSRP being the maximum one among the second group of RSRPs; indicating a differential value of a third RSRP from the first group of RSRPs relative to the first RSRP; and indicating a differential value of a fourth RSRP from the second group of RSRPs relative to the first or second RSRP. 
     In some embodiments, indicating the first number of RSRPs from the first group of RSRPs and the second number of RSRPs from the second group of RSRPs comprises: indicating an absolute value of a first RSRP from the first group of RSRPs, the first RSRP being the maximum one among the first group of RSRPs; indicating a differential value of a second RSRP from the second group of RSRPs relative to the first RSRP, the second RSRP being the maximum one among the second group of RSRPs; indicating a differential value of a third RSRP from the first group of RSRPs relative to the first RSRP; indicating a differential value of a fourth RSRP from the second group of RSRPs relative to the first RSRP; and indicating whether the first RSRP is greater than the second RSRP or not. 
     In some embodiments, indicating the first number of RSRPs from the first group of RSRPs and the second number of RSRPs from the second group of RSRPs comprises: indicating an absolute value of a first RSRP from the first group of RSRPs, the first RSRP being the maximum one among the first group of RSRPs; indicating an absolute value of a second RSRP from the second group of RSRPs, the second RSRP being the maximum one among the second group of RSRPs; indicating a differential value of a third RSRP from the first group of RSRPs relative to the first RSRP; and indicating a differential value of a fourth RSRP from the second group of RSRPs relative to the second RSRP. 
     It can be seen that, embodiments of the present disclosure provide a solution for beam management. With the solution, beam reporting for multi-TRP/panel transmission can be supported. Further, the overhead for beam reporting can be reduced. 
       FIG. 14  is a simplified block diagram of a device  1400  that is suitable for implementing embodiments of the present disclosure. The device  1400  can be considered as a further example implementation of the network device  210  or the terminal device  220  as shown in  FIG. 2 . Accordingly, the device  1400  can be implemented at or as at least a part of the network device  210  or the terminal device  220 . 
     As shown, the device  1400  includes a processor  1410 , a memory  1420  coupled to the processor  1410 , a suitable transmitter (TX) and receiver (RX)  1440  coupled to the processor  1410 , and a communication interface coupled to the TX/RX  1440 . The memory  1410  stores at least a part of a program  1430 . The TX/RX  1440  is for bidirectional communications. The TX/RX  1440  has at least one antenna to facilitate communication, though in practice an Access Node mentioned in this application may have several ones. The communication interface may represent any interface that is necessary for communication with other network elements, such as X2 interface for bidirectional communications between eNBs, S1 interface for communication between a Mobility Management Entity (MME)/Serving Gateway (S-GW) and the eNB, Un interface for communication between the eNB and a relay node (RN), or Uu interface for communication between the eNB and a terminal device. 
     The program  1430  is assumed to include program instructions that, when executed by the associated processor  1410 , enable the device  1400  to operate in accordance with the embodiments of the present disclosure, as discussed herein with reference to  FIGS. 2 to 13 . The embodiments herein may be implemented by computer software executable by the processor  1410  of the device  1400 , or by hardware, or by a combination of software and hardware. The processor  1410  may be configured to implement various embodiments of the present disclosure. Furthermore, a combination of the processor  1410  and memory  1420  may form processing means  1450  adapted to implement various embodiments of the present disclosure. 
     The memory  1420  may be of any type suitable to the local technical network and may be implemented using any suitable data storage technology, such as a non-transitory computer readable storage medium, semiconductor based memory devices, magnetic memory devices and systems, optical memory devices and systems, fixed memory and removable memory, as non-limiting examples. While only one memory  1420  is shown in the device  1400 , there may be several physically distinct memory modules in the device  1400 . The processor  1410  may be of any type suitable to the local technical network, and may include one or more of general purpose computers, special purpose computers, microprocessors, digital signal processors (DSPs) and processors based on multicore processor architecture, as non-limiting examples. The device  1400  may have multiple processors, such as an application specific integrated circuit chip that is slaved in time to a clock which synchronizes the main processor. 
     Generally, various embodiments of the present disclosure may be implemented in hardware or special purpose circuits, software, logic or any combination thereof. Some aspects may be implemented in hardware, while other aspects may be implemented in firmware or software which may be executed by a controller, microprocessor or other computing device. While various aspects of embodiments of the present disclosure are illustrated and described as block diagrams, flowcharts, or using some other pictorial representation, it will be appreciated that the blocks, apparatus, systems, techniques or methods described herein may be implemented in, as non-limiting examples, hardware, software, firmware, special purpose circuits or logic, general purpose hardware or controller or other computing devices, or some combination thereof 
     The present disclosure also provides at least one computer program product tangibly stored on a non-transitory computer readable storage medium. The computer program product includes computer-executable instructions, such as those included in program modules, being executed in a device on a target real or virtual processor, to carry out the process or method as described above with reference to  FIGS. 12-13 . Generally, program modules include routines, programs, libraries, objects, classes, components, data structures, or the like that perform particular tasks or implement particular abstract data types. The functionality of the program modules may be combined or split between program modules as desired in various embodiments. Machine-executable instructions for program modules may be executed within a local or distributed device. In a distributed device, program modules may be located in both local and remote storage media. 
     Program code for carrying out methods of the present disclosure may be written in any combination of one or more programming languages. These program codes may be provided to a processor or controller of a general purpose computer, special purpose computer, or other programmable data processing apparatus, such that the program codes, when executed by the processor or controller, cause the functions/operations specified in the flowcharts and/or block diagrams to be implemented. The program code may execute entirely on a machine, partly on the machine, as a stand-alone software package, partly on the machine and partly on a remote machine or entirely on the remote machine or server. 
     The above program code may be embodied on a machine readable medium, which may be any tangible medium that may contain, or store a program for use by or in connection with an instruction execution system, apparatus, or device. The machine readable medium may be a machine readable signal medium or a machine readable storage medium. A machine readable medium may include but not limited to an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any suitable combination of the foregoing. More specific examples of the machine readable storage medium would include an electrical connection having one or more wires, a portable computer diskette, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or Flash memory), an optical fiber, a portable compact disc read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing. 
     Further, while operations are depicted in a particular order, this should not be understood as requiring that such operations be performed in the particular order shown or in sequential order, or that all illustrated operations be performed, to achieve desirable results. In certain circumstances, multitasking and parallel processing may be advantageous. Likewise, while several specific implementation details are contained in the above discussions, these should not be construed as limitations on the scope of the present disclosure, but rather as descriptions of features that may be specific to particular embodiments. Certain features that are described in the context of separate embodiments may also be implemented in combination in a single embodiment. Conversely, various features that are described in the context of a single embodiment may also be implemented in multiple embodiments separately or in any suitable sub-combination. 
     Although the present disclosure has been described in language specific to structural features and/or methodological acts, it is to be understood that the present disclosure defined in the appended claims is not necessarily limited to the specific features or acts described above. Rather, the specific features and acts described above are disclosed as example forms of implementing the claims.