Patent Publication Number: US-2023143727-A1

Title: On facilitating mpe indication in layer 2 phr reporting

Description:
TECHNICAL FIELD 
     The teachings in accordance with the exemplary embodiments of this invention relate generally to providing at least that a network device is configured to determine whether to transmit a power headroom report using a different beam pair link than for which the power headroom report is calculated and, more specifically, relate to a network device being configured to determine whether to transmit a power headroom report using a different beam pair link than for which the power headroom report is calculated when certain conditions are fulfilled. 
     BACKGROUND 
     This section is intended to provide a background or context to the invention that is recited in the claims. The description herein may include concepts that could be pursued, but are not necessarily ones that have been previously conceived or pursued. Therefore, unless otherwise indicated herein, what is described in this section is not prior art to the description and claims in this application and is not admitted to be prior art by inclusion in this section. 
     Certain abbreviations that may be found in the description and/or in the Figures are herewith defined as follows:
     ACK acknowledgement   DL Downlink   FR2 frequency range  2     gNB 5G Node B   MPE Maximum Permissible Exposure   MPR Maximum Power Reduction   P-MPR Power Management MPR   PHR Power Headroom   PUCCH Physical Uplink Control Channel   PUSCH Physical Uplink Shared Channel   RAN Radio Access Network   RS Reference Signal   RSRP Reference Signal Received Power   TRP Transmission and Reception Point   TX Transmit   UE User Equipment   UL Uplink   

     At the time of this application discussions are occurring regarding adapting multiple access technologies for various telecommunication standards to provide common protocols enabling different user equipment to communicate on a global level. 
     In some these discussions there is proposed adaptations to operations associated with Maximum Permissible Exposure (MPE) limits imposed on some communications devices. Such exposure limits are imposed to limit Radio Frequency (RF) radiation from wireless devices. 
     Example embodiments of the invention work to at least provide improved operations associated with at least these types of MPE limits. 
     SUMMARY SECTION 
     In an example aspect of the invention, there is an apparatus, such as a network side apparatus, comprising: at least one processor; and at least one memory including computer program code, where the at least one memory and the computer program code are configured, with the at least one processor, to cause the apparatus to at least: determine a power limiting state for a candidate uplink beam pair of at least one candidate uplink beam pair configured for a user equipment of a communication network; and based at least on the determining, cause configuration of a different candidate uplink beam pair of the at least one candidate uplink beam pair for communicating towards the communication network; and communicating at least one power headroom report for the candidate uplink beam pair based on the power limiting state. 
     In another example aspect of the invention, there is a method comprising: determining a power limiting state for a candidate uplink beam pair of at least one candidate uplink beam pair configured for a user equipment of a communication network; and based at least on the determining, causing configuration of a different candidate uplink beam pair of the at least one candidate uplink beam pair for communicating towards the communication network; and communicating at least one power headroom report for the candidate uplink beam pair based on the power limiting state. 
     A further example embodiment is an apparatus and a method comprising the apparatus and the method of the previous paragraphs, wherein the power limiting state is based on at least one of a maximum power reduction operation caused by a maximum permissible exposure constraint for the candidate uplink beam pair exceeding a threshold, wherein the power limiting state is based on a negative power headroom determination for the candidate uplink beam pair, wherein causing the configuration of the different candidate uplink beam pair for communicating the at least one power headroom report is based on at least one of: determining the at least one power headroom report is negative due to the maximum permissible exposure constraint, determining that a power level reduction of the maximum power reduction operation caused by a maximum permissible exposure constraint exceeds a predetermined threshold, or determining that a measured metric of spatial relation reference signal of the candidate uplink beam pair is below a predetermined threshold, wherein the spatial source reference signal (RS) can be one of an uplink or downlink reference signal, and wherein the spatial source reference signal is used by the user equipment to determine a candidate uplink beam pair, wherein for a case the spatial source reference signal is a downlink reference signal the user equipment uses a beam for reception of the downlink reference signal as the transmit beam for a candidate uplink beam pair, wherein the measured metric comprises at least one of channel state information (CSI), reference signal received power (RSRP), Reference Signal Received Quality (RSRPQ), or Reference signal to noise and interference ratio (RS-SINR) metrics, wherein the communicating comprises the user equipment indicating the different candidate uplink beam pair of the at least one candidate uplink beam pair over which the at least one power headroom report is communicated, wherein the communicating over the different candidate uplink beam pair is based on at least one of: spatial relation information of the different candidate uplink beam pair, a PUCCH group index associated with the different candidate uplink beam pair, a pathloss reference signal associated with the different candidate uplink beam pair, or a logical index of at least one current active candidate uplink beam pair, wherein the communicating comprises: multiplexing over the different candidate uplink beam pair the at least one power headroom report using a medium access control element, wherein the communicating comprises: implementing at least one extension field for the medium access control element, wherein the at least one extension field comprises indications of at least one of: a power headroom report for the different candidate uplink beam pair, a power headroom report for a given cell, or a virtual power headroom report for a candidate uplink beam pair not used to communicate the power headroom report, wherein the given cell is identified based on at least one of a spatial relation reference signal or uplink beam pair link identification, wherein the at least one candidate uplink beam pair comprises multiple candidate uplink beam pairs, wherein the implementing comprises implementing two bits for the medium access control element, wherein the two bits comprises: a first bit for indicating an additional maximum permissible exposure indication for another candidate uplink beam pair, and a second bit for indicating there is no additional maximum permissible exposure indication for another candidate uplink beam pair, wherein the at least one power headroom report comprises more than one power headroom report, wherein each of the more than one headroom report is for a different one of the more than one power headroom report, and/or, wherein there is for a case that a power level reduction level of any of the at least one candidate uplink beam pair is under the predetermined threshold, the communicating is using the at least one candidate uplink beam under the predetermined threshold. 
     A non-transitory computer-readable medium storing program code, the program code executed by at least one processor to perform at least the method as described in the paragraphs above. 
     In another example aspect of the invention, there is an apparatus comprising: means for determining a power limiting state for a candidate uplink beam pair of at least one candidate uplink beam pair configured for a user equipment of a communication network; based at least on the determining, causing configuration of a different candidate uplink beam pair of the at least one candidate uplink beam pair for communicating towards the communication network; and means for communicating at least one power headroom report for the candidate uplink beam pair based on the power limiting state. 
     In accordance with the example embodiments as described in the paragraph above, at least the means for determining and causing comprises a network interface, and computer program code stored on a non-transitory computer-readable medium and executed by at least one processor. 
     A communication system comprising the apparatus performing operations as described above. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above and other aspects, features, and benefits of various embodiments of the present disclosure will become more fully apparent from the following detailed description with reference to the accompanying drawings, in which like reference signs are used to designate like or equivalent elements. The drawings are illustrated for facilitating better understanding of the embodiments of the disclosure and are not necessarily drawn to scale, in which: 
         FIG.  1    shows a high level block diagram of various devices used in carrying out various aspects of the invention; 
         FIG.  2    shows a MAC CE configuration in accordance with an example embodiment of the invention; 
         FIG.  3    shows a MAC CE configuration for multiple beam pair links in accordance with an example embodiment of the invention; 
         FIG.  4    shows a workflow associated with a workflow description document in accordance with example embodiments of the invention; 
         FIG.  5    shows a method which may be performed by a user equipment in accordance with example embodiments of the invention; and 
         FIG.  6    shows a method which may be performed by an apparatus in accordance with example embodiments of the invention. 
     
    
    
     DETAILED DESCRIPTION 
     In this invention, there is proposed at least a novel method for determining by a network device whether to transmit a power headroom report using a different beam pair link than for which the power headroom report is calculated when certain conditions are fulfilled. 
     In certain situations, a certain type or percentage of a wave beam from a handheld device directed toward a person&#39;s body may violate an MPE limit. Solutions include a back-off of signalling of such devices in order to be compliant with the MPE limit. It is noted that these limits can impose clear restrictions on a link capacity and impact a communication range of a device as well. To improve safety, some governing bodies have placed restrictions on a peak signal level that can be directed toward the human body. These restrictions are sometimes referred to as maximum permissible exposure (MPE) limitations, MPE constraints, and/or the like. 
     Example embodiments of the invention relate to 3GPP NR design that can use similar MPE limits. More specifically, certain example embodiments of the invention focus on solving problem regarding UE&#39;s indication about MPE situation at the UE using the L2 based signalling. In a previous release RAN4 has provided an LS to RAN2 to indicate need for the signalling support as follows: 
     
       
         
           
               
             
               
                   
               
             
            
               
                 RAN4 has agreed further details on Rel-16 FR2 MPE enhancement 
               
               
                 solutions to mitigate RLF due to sudden and unpredictable large back off 
               
               
                 caused UE&#39;s actions to ensure compliance with exposure regulation. 
               
               
                 RAN4 would like to ask RAN2 to develop the following Rel-16 FR2 MPE 
               
               
                 signalling based on MAC-CE to ensure sufficiently short signalling delays: 
               
               
                 at least UE&#39;s P-MPR based event-triggered reporting including also 
               
               
                 reporting of the actual P-MPR level that UE needs for FR2 MPE reasons. 
               
               
                 Network configurable P-MPR reporting threshold 
               
               
                 A prohibit timer is enabled to be configured by network to trigger the P- 
               
               
                 MPR reporting 
               
               
                 P-MPR reporting range and reporting granularity are still under discussion 
               
               
                 in RAN4. 
               
               
                   
               
            
           
         
       
     
     It is noted that a RAN4 described solution to signal P-MPR reflecting MPE issue at the UE to the gNB is assumed to be provided together with/alongside existing Power Head Room (PHR) reporting. In FR2, which is the targeted frequency range for MPE indication, the UE may be configured more than one active beam pair link, e.g. to different TRPs, in order to provide robustness against sudden blockages and beam pair misalignment between gNB and UE due to mobility and rotation of the UE. The MPE can be considered directional, or in other words, can be considered beam and/or panel specific in FR2 where the UE operates using narrow beams for downlink and uplink. 
     Power Headroom (PH) reporting provides information for the link (in this context for the beam pair link) used to transmit the PHR. The problem now arises that when the MPE becomes an issue for the link (beam pair link in this context) the required power backoff that high that available transmission power would be too low for the PUSCH transmission (especially in cell edge conditions). 
     Furthermore, gNB determines and configures UL TX beams for the UE based on DL RS measurements and reported RSRP values. However, RSRP value does not reveal anything about possible MPE issue if the UE used that DL RS to determine UL TX beam. Thus, enhanced PHR reporting would be the way to provide, though reactively, information to the gNB that UE has faced MPE issue when using the certain beam pair link. However, as said above, that link in question may require such high power backoff that PUSCH transmission carrying PHR may not be receivable at the gNB. 
     It&#39;s also to be noted that while UE notices that one beam pair link has faced MPE issue and would be subject to significant power backoff there are no means for the UE to indicate gNB about it. E.g. there is no UL based beam failure recovery where upon detection of deteriorated quality of the spatial relation RS for the UL resource would trigger beam failure recovery. 
     Current PHR reporting is designed for the system where UE is having “one radio link” per serving cell. However, problems to be addressed can be seen to be that in FR2 and in general in beam based system, the UE may have multiple (candidate) beam pair links for the serving cell in uplink. 
     For at least this reason example embodiments of the invention provide at least that the UE is configured to determine whether to transmit PHR report using a different beam pair link than for which the PHR is calculated, e.g. when certain conditions are fulfilled. 
     However, before describing the example embodiments of the invention in detail, reference is made to  FIG.  1    for illustrating a simplified block diagram of various electronic devices that are suitable for use in practicing the example embodiments of this invention. 
       FIG.  1    shows a block diagram of one possible and non-limiting exemplary system in which the example embodiments of the invention may be practiced. In  FIG.  1   , a user equipment (UE)  10  is in wireless communication with a wireless network  1 . A UE is a wireless, typically mobile device that can access a wireless network. The UE, for example, may be a mobile phone (or called a “cellular” phone) and/or a computer with a mobile terminal function. For example, the UE or mobile terminal may also be a portable, pocket, handheld, computer-embedded or vehicle-mounted mobile device and performs a language signaling and/or data exchange with the RAN. 
     The UE  10  includes one or more processors DP 10A, one or more memories MEM  10 B, and one or more transceivers TRANS  10 D interconnected through one or more buses. Each of the one or more transceivers TRANS  10 D includes a receiver and a transmitter. The one or more buses may be address, data, or control buses, and may include any interconnection mechanism, such as a series of lines on a motherboard or integrated circuit, fiber optics or other optical communication equipment, and the like. The one or more transceivers TRANS  10 D are connected to one or more antennas for communication  11  and  18  to NN  12  and NN  13 , respectively. The one or more memories MEM  10 B include computer program code PROG  10 C. The UE  10  communicates with NN  12  and/or NN  13  via a wireless link  111 . 
     The NN  12  (NR/5G Node B, an evolved NB, eNB, gNB, or LTE device) is a network node such as a master or secondary node base station (e.g., for NR or LTE long term evolution) that communicates with devices such as NN  13  and UE  10  of  FIG.  1   . The NN  12  provides access to wireless devices such as the UE  10  to the wireless network  1 . The NN  12  includes one or more processors DP 12A, one or more memories MEM  12 C, and one or more transceivers TRANS  12 D interconnected through one or more buses. In accordance with the example embodiments these TRANS  12 D can include X2 and/or Xn interfaces for use to perform the example embodiments of the invention. Each of the one or more transceivers TRANS  12 D includes a receiver and a transmitter. The one or more transceivers TRANS  12 D are connected to one or more antennas for communication over at least link  11  with the UE  10 . The one or more memories MEM  12 B and the computer program code PROG  12 C are configured to cause, with the one or more processors DP 12A, the NN  12  to perform one or more of the operations as described herein. The NN  12  may communicate with another gNB or eNB, or a device such as the NN  13 . Further, the link  11  and or any other link may be wired or wireless or both and may implement, e.g., an X2 or Xn interface. Further the link  11  may be through other network devices such as, but not limited to an NCE/SGW//AMF/UPF device such as the NCE/MME/SGW/UDM/PCF/AMM/SMF  14  of  FIG.  1   . The NN  12  may perform functionalities of an MME (Mobility Management Entity) or SGW (Serving Gateway), such as a User Plane Functionality, and/or an Access Management functionality for LTE and similar functionality for 5G 
     The NN  13  can comprise a mobility function device such as an AMF or SMF, further the NN  13  may comprise a NR/5G Node B or possibly an evolved NB a base station such as a master or secondary node base station (e.g., for NR or LTE long term evolution) that communicates with devices such as the NN  12  and/or UE  10  and/or the wireless network  1 . The NN  13  includes one or more processors DP 13A, one or more memories MEM  13 B, one or more network interfaces, and one or more transceivers TRANS  12 D interconnected through one or more buses. In accordance with the example embodiments these network interfaces of NN  13  can include X2 and/or Xn interfaces for use to perform the example embodiments of the invention. Each of the one or more transceivers TRANS  13 D includes a receiver and a transmitter connected to one or more antennas. The one or more memories MEM  13 B include computer program code PROG  13 C. For instance, the one or more memories MEM  13 B and the computer program code PROG  13 C are configured to cause, with the one or more processors DP 13A, the NN  13  to perform one or more of the operations as described herein. The NN  13  may communicate with another mobility function device and/or eNB such as the NN  12  and the UE  10  or any other device using, e.g., link  11  or another link. These links may be wired or wireless or both and may implement, e.g., an X2 or Xn interface. Further, as stated above the link  11  may be through other network devices such as, but not limited to an NCE/MME/SGW device such as the NCE/MME/SGW/UDM/PCF/AMM/SMF  14  of  FIG.  1   . 
     The one or more buses of the device of  FIG.  1    may be address, data, or control buses, and may include any interconnection mechanism, such as a series of lines on a motherboard or integrated circuit, fiber optics or other optical communication equipment, wireless channels, and the like. For example, the one or more transceivers TRANS  12 D, TRANS  13 D and/or TRANS  10 D may be implemented as a remote radio head (RRH), with the other elements of the NN  12  being physically in a different location from the RRH, and the one or more buses  157  could be implemented in part as fiber optic cable to connect the other elements of the NN  12  to a RRH. 
     It is noted that although  FIG.  1    shows a network nodes Such as NN  12  and NN  13 . Any of these nodes may can incorporate or be incorporated into an eNodeB or eNB or gNB such as for LTE and NR, and would still be configurable to perform example embodiments of the invention. Also it is noted that description herein indicates that “cells” perform functions, but it should be clear that the gNB that forms the cell and/or a user equipment and/or mobility management function device that will perform the functions. In addition, the cell makes up part of a gNB, and there can be multiple cells per gNB. 
     The wireless network  1  may include a NCE/MME/SGW/UDM/PCF/AMM/SMF  14  that may include (NCE) network control element functionality, MME (Mobility Management Entity)/SGW (Serving Gateway) functionality, and/or serving gateway (SGW)  190 , and/or MME (Mobility Management Entity) and/or SGW (Serving Gateway) functionality, and/or user data management functionality (UDM), and/or PCF (Policy Control) functionality, and/or Access and Mobility Management (AMM) functionality, and/or Session Management (SMF) functionality, and/or Authentication Server (AUSF) functionality and which provides connectivity with a further network, such as a telephone network and/or a data communications network (e.g., the Internet), and which is configured to perform any 5G and/or NR operations in addition to or instead of other standards operations at the time of this application. The NCE/MME/SGW/UDM/PCF/AMM/SMF  190  is configurable to perform operations in accordance with example embodiments of the invention in any of an LTE, NR, 5G and/or any standards based communication technologies being performed or discussed at the time of this application. In addition, it is noted that the operations in accordance with example embodiments of the invention, as performed by the NN  12  and/or NN  13 , may also be performed at the NCE/MME/SGW/UDM/PCF/AMM/SMF  14 . 
     The NCE/MME/SGW/UDM/PCF/AMM/SMF  14  includes one or more processors DP 14A, one or more memories MEM  14 B, and one or more network interfaces (N/W I/F(s)), interconnected through one or more buses coupled with the link  13  and/or  14 . In accordance with the example embodiments these network interfaces can include X2 and/or Xn interfaces for use to perform the example embodiments of the invention. The one or more memories MEM  14 B include computer program code PROG  14 C. The one or more memories MEM  14 B and the computer program code PROG  14 C are configured to, with the one or more processors DP 14A, cause the NCE/MME/SGW/UDM/PCF/AMM/SMF  14  to perform one or more operations which may be needed to support the operations in accordance with the example embodiments of the invention. 
     The wireless Network  1  may implement network virtualization, which is the process of combining hardware and software network resources and network functionality into a single, software-based administrative entity, a virtual network. Network virtualization involves platform virtualization, often combined with resource virtualization. Network virtualization is categorized as either external, combining many networks, or parts of networks, into a virtual unit, or internal, providing network-like functionality to software containers on a single system. Note that the virtualized entities that result from the network virtualization are still implemented, at some level, using hardware such as processors DP10, DP12A, DP13A, and/or DP14A and memories MEM  10 B, MEM  12 B, MEM  13 B, and/or MEM  14 B, and also such virtualized entities create technical effects. 
     The computer readable memories MEM  12 B, MEM  13 B, and MEM  14 B may be of any type suitable to the local technical environment and may be implemented using any suitable data storage technology, such as semiconductor based memory devices, flash memory, magnetic memory devices and systems, optical memory devices and systems, fixed memory and removable memory. The computer readable memories MEM  12 B, MEM  13 B, and MEM  14 B may be means for performing storage functions. The processors DP10, DP12A, DP13A, and DP14A may be of any type suitable to the local technical environment, and may include one or more of general purpose computers, special purpose computers, microprocessors, digital signal processors (DSPs) and processors based on a multi-core processor architecture, as non-limiting examples. The processors DP10, DP12A, DP13A, and DP14A may be means for performing functions, such as controlling the UE  10 , NN  12 , NN  13 , and other functions as described herein. 
     As similarly stated above, in accordance with example embodiments of the invention a UE can be configured to determine whether to transmit PHR report using a different beam pair link than for which the PHR is calculated, e.g. when certain conditions are fulfilled. 
     Such conditions for the determining could be based on, for example:
         Power headroom would be negative and/or P-MPR (e.g. due to MPE or other reasons) is greater than predefined or configured value; and/or   Measured metric (e.g. CSI/RSRP/RSRQ/RS-SINR) of the spatial relation RS that is utilized (e.g. configured, activated or indicated) for the uplink for which the PHR is calculated goes below the certain (pre-defined or configured) threshold       

     This could be achieved by restricting the UE not to multiplex PHR MAC CE on a beam pair link for which the conditions are fulfilled above. Additionally or alternatively, a scheduling request procedure could be used to request resources on the beam pair link in which the PHR MAC CE could be multiplexed. 
     The PHR could report PH for the beam pair link used to transmit the PHR as well. The real PH could be calculated for the beam pair link used to transmit the PHR while virtual PH could be calculated for the beam pair link that the UE additionally reports in the PHR. 
     In the PHR report the UE indicates for which beam pair link this certain PHR would be addressed. Identification could be based on, for example:
         Spatial relation info of the considered beam pair link, i.e. DL or UL RS index;   PUCCH group index (in case PUCCH resources are grouped for configured spatial relations e.g. TRP wise);   Pathloss reference RS associated to the considered beam pair link, i.e. certain DL RS; and/or   Logical index of current active UL beam pair links       

     The indication can also be sent to indicate that there is no anymore MPE issue on certain beam pair link. 
     Example embodiments of the invention provide at least a new functionality the PHR that can be provided for another beam pair link than using which it&#39;s transmitted per serving cell. Especially in multi-TRP scenario the UE may be provided multiple candidate beam pair links e.g. for connection robustness. 
     In these novel operations, the P-MPR reporting due to MPE may also be transmitted separately from PHR, for example, in a separate MAC CE defined for MPE/P-MPR reporting. 
     The following steps could be considered for the UE to implement the invention:
         1. PHR and/or MPE/P-MPR reporting is triggered for the beam pair link for which the P-MPR or similar due to MPE has become larger than configured threshold;   2. UE determines that due to MPE the beam pair link through which the PHR would be transmitted is having too low quality where determination is based on the measurement on the spatial relation RS or pathloss reference RS of the beam pair link in question; and/or   3. UE prepares PHR for the impacted beam pair link and transmits PHR on the other uplink beam pair link which does not suffer too high MPR. The PH value calculated for the impacted beam pair link may be a virtual PH value or a PH value based on a reference format.       

       FIG.  2    shows operations in accordance with example embodiments of the invention where an MPE indication, i.e. P-MPR indication can be embedded in principle into MAC-CE providing PH but it may be also a separate MAC CE as well, e.g. in case the PH or MPE reporting is not configured for the UE. 
     As shown in  FIG.  2   , single entry PHR MAC CE such as in standards at the time of this application could be updated as follows (the italic text of  FIG.  2    illustrates a configured field of an MAC CE in accordance with example embodiments of the invention). Here, for example when P-MPR indication due to MPE is provided to some certain beam pair link the MAC CE uses a configured field to indicate a spatial relation or uplink beam pair ID. 
     Additionally, one of the R bits could be used to implement an “extension field” which is used by the UE to indicate that more PH reports follow for the given cell. For instance, the “PH (type  1 , PCell)” field would be encoded based on the real PH of the beam pair link of the PCell used to transmit the PHR while the “extension field” would indicate that there will be another PH reported for the given cell (which can be identified, e.g., by the “Spatial relation RS or uplink beam pair link ID” above). In that case there would be another PH field in the above figure which would indicate a “virtual PH” for the beam link pair not used to transmit the PHR but for which the certain conditions are fulfilled to report the PH. 
     For a case of multiple beam pair links per serving cell the indication in accordance with example embodiments of the invention can be seen in  FIG.  3   . Here,  FIG.  3    shows a MAC CE configuration for multiple beam pair links in accordance with an example embodiment of the invention. 
     As shown in  FIG.  3    there is a MAC CE configured with a field including a bit-1. As shown in  FIG.  3    the configured field with the bit-1 indicates that there is additional MPE indication for another beam pair link. Further, as shown in  FIG.  3    the configured field with the bit-0 indicates that there is no additional MPE indication for another beam pair link. 
     In accordance with another example embodiment of the invention a multi-entry MAC CE PHR could be updated to indicate MPE indication for multiple beam pair links per serving cell. That is to support carrier aggregation as well with MPE indication per UL beam pair link. 
     According to proposed scheme, at least the following operations are also supported:
         UE measures multiple PHR where each value is calculated from different beam pair,
           UE may select beam pair to calculate PHR or be configured beam pairs to calculate PHR;   
           UE is allowed to select PHR to be reported. For example:
           When none of the PHR has value under the threshold, UE selects PHR calculated from the beam currently in use for UL transmission,   When any of the PHR has value under the threshold, UE may report PHR which is lower than the threshold, or multiple of PHRs lower than threshold, and/or   For PHR reporting, UE may report PHR with largest value together with the PHR selected above; and/or   
           Based on the reception of PHR, gNB determines which beam to be used for UL transmission, or reconfigures beam pair to be used for PHR calculation.       

       FIG.  4    illustrated operations in accordance with example embodiments of the invention which may be performed by a device such as, but not limited to, a device associated with the UE  10 , NN  12 , NN  13 , and/or NCE/MME/SGW/UDM/PCF/AMM/SMF  14  as in  FIG.  1   . 
     As shown in step  410  of  FIG.  4    a UE determines that power headroom report (PHR) is to be provided in at least one uplink transmit beam and/or beam pair link. As shown in step  420  of  FIG.  4    the UE determines that uplink transmit beam and/or beam pair for which PHR is to be reported cannot be used to transmit a PHR. As shown in step  430  of  FIG.  4    the UE transits triggered PHR corresponding to a certain uplink transmit beam and/or beam pair link using some other uplink transmit beam and/or beam pair link. Then as shown in step  440  of  FIG.  4    the UE provides in the reported PHR the indication of the uplink transmit beam and/or beam pair link for which the report containing the PHR is associated to. 
       FIG.  5    shows a method which may be performed by a device such as, but not limited to, a device associated with the UE  10 , NN  12 , NN  13 , and/or NCE/MME/SGW/UDM/PCF/AMM/SMF  14  as in  FIG.  1    in accordance with example embodiments of the invention. 
     As shown in step  510  of  FIG.  5    there is communicated between the eNB/gNB  170  and the UE  110  a configuration and/or activation of uplink beam pair link (characterized by a spatial source RS). As shown in step  520  of  FIG.  5    there is communicated between the eNB/gNB  170  and the UE  110  configuration and/or activation of uplink beam pair link (characterized by a spatial source RS). As shown in step  530  of  FIG.  5    there is configuration of PHR reporting and/or possible thresholds related to MPE. Such thresholds for example can be P-MPR or similar). As shown in step  535  of  FIG.  5    the UE  110  determines the power headroom report (PHR) is t be provided for at least one uplink transmit beam and/or beam pair. As shown in step  540  of  FIG.  5    the UE  110  determines that uplink transmit beam and/or beam pair link for which PHR is to be reported cannot be used to transmit the PHR. Then as shown in step  545  of  FIG.  5    PHR corresponding to a certain uplink transmit beam and/or beam pair link is using some other uplink transmit beam and/or beam pair link for which the report is associated to. 
       FIG.  6    illustrated operations in accordance with example embodiments of the invention which may be performed by a device such as, but not limited to, a device associated with the UE  10 , NN  12 , NN  13 , and/or NCE/MME/SGW/UDM/PCF/AMM/SMF  14  as in  FIG.  1   . As shown in step  610  of  FIG.  6    there is determining a power limiting state for a candidate uplink beam pair of at least one candidate uplink beam pair configured for a user equipment of a communication network. As shown in step  620  of  FIG.  6    there is, based at least on the determining, causing configuration of a different candidate uplink beam pair of the at least one candidate uplink beam pair for communicating towards the communication network. Then as shown in step  630  of  FIG.  6    there is, communicating at least one power headroom report for the candidate uplink beam pair based on the power limiting state. 
     In accordance with example embodiments of the invention as described in the paragraph above, wherein the power limiting state is based on at least one of a maximum power reduction operation caused by a maximum permissible exposure constraint for the candidate uplink beam pair exceeding a threshold. 
     In accordance with example embodiments of the invention as described in the paragraphs above, wherein the power limiting state is based on a negative power headroom determination for the candidate uplink beam pair. 
     In accordance with example embodiments of the invention as described in the paragraphs above, wherein causing the configuration of the different candidate uplink beam pair for communicating the at least one power headroom report is based on at least one of: determining the at least one power headroom report is negative due to the maximum permissible exposure constraint, determining that a power level reduction of the maximum power reduction operation caused by a maximum permissible exposure constraint exceeds a predetermined threshold, or determining that a measured metric of spatial relation reference signal of the candidate uplink beam pair is below a predetermined threshold. 
     In accordance with example embodiments of the invention as described in the paragraphs above, wherein the spatial source reference signal (RS) can be one of an uplink or downlink reference signal, and wherein the spatial source reference signal is used by the user equipment to determine a candidate uplink beam pair. 
     In accordance with example embodiments of the invention as described in the paragraphs above, wherein for a case the spatial source reference signal is a downlink reference signal the user equipment uses a beam for reception of the downlink reference signal as the transmit beam for a candidate uplink beam pair. 
     In accordance with example embodiments of the invention as described in the paragraphs above, wherein the measured metric comprises at least one of channel state information (CSI), reference signal received power (RSRP), Reference Signal Received Quality (RSRPQ), or Reference signal to noise and interference ratio (RS-SINR) metrics. 
     In accordance with example embodiments of the invention as described in the paragraphs above, wherein the communicating comprises the user equipment indicating the different candidate uplink beam pair of the at least one candidate uplink beam pair over which the at least one power headroom report is communicated. 
     In accordance with example embodiments of the invention as described in the paragraphs above, wherein the communicating over the different candidate uplink beam pair is based on at least one of: spatial relation information of the different candidate uplink beam pair, a PUCCH group index associated with the different candidate uplink beam pair, a pathloss reference signal associated with the different candidate uplink beam pair, or a logical index of at least one current active candidate uplink beam pair. 
     In accordance with example embodiments of the invention as described in the paragraphs above, wherein the communicating comprises: multiplexing over the different candidate uplink beam pair the at least one power headroom report using a medium access control element. 
     In accordance with example embodiments of the invention as described in the paragraphs above, wherein the communicating comprises implementing at least one extension field for the medium access control element, wherein the at least one extension field comprises indications of at least one of: a power headroom report for the different candidate uplink beam pair, a power headroom report for a given cell, or a virtual power headroom report for a candidate uplink beam pair not used to communicate the power headroom report. 
     In accordance with example embodiments of the invention as described in the paragraphs above, wherein the given cell is identified based on at least one of a spatial relation reference signal or uplink beam pair link identification. 
     In accordance with example embodiments of the invention as described in the paragraphs above, wherein the at least one candidate uplink beam pair comprises multiple candidate uplink beam pairs, wherein the implementing comprises implementing two bits for the medium access control element. 
     In accordance with example embodiments of the invention as described in the paragraphs above, wherein the two bits comprises: a first bit for indicating an additional maximum permissible exposure indication for another candidate uplink beam pair, and a second bit for indicating there is no additional maximum permissible exposure indication for another candidate uplink beam pair 
     In accordance with example embodiments of the invention as described in the paragraphs above, wherein the at least one power headroom report comprises more than one power headroom report, wherein each of the more than one headroom report is for a different one of the more than one power headroom report. 
     In accordance with example embodiments of the invention as described in the paragraphs above, wherein for a case that a power level reduction level of any of the at least one candidate uplink beam pair is under the predetermined threshold, the communicating is using the at least one candidate uplink beam under the predetermined threshold. 
     A non-transitory computer-readable medium (MEM  10 B, MEM  12 B, MEM  13 B, and/or MEM  14 B as in  FIG.  1   ) storing program code (PROG  10 C, PROG  12 C, PROG  13 C, and/or PROG 14 C as in  FIG.  1   ), the program code executed by at least one processor (DP 10A, DP 12A, DP 13A, and/or DP 14A as in  FIG.  1   ) to perform the operations as at least described in the paragraphs above. 
     In accordance with an example embodiment of the invention as described above there is an apparatus comprising: means for determining (TRANS  10 D, TRANS  12 D, TRANS  13 D, and/or 
     TRANS  14 D; MEM  10 B, MEM  12 B, MEM  13 B, and/or MEM  14 B; PROG  10 C, PROG  12 C, PROG  13 C, and/or PROG 14 C; and DP 10A, DP 12A, DP 13A, and/or DP 14A as in  FIG.  1   ) for a candidate uplink beam pair of at least one candidate uplink beam pair configured (TRANS  10 D, TRANS  12 D, TRANS  13 D, and/or TRANS  14 D; MEM  10 B, MEM  12 B, MEM  13 B, and/or MEM  14 B; PROG  10 C, PROG  12 C, PROG  13 C, and/or PROG 14 C; and DP 10A, DP 12A, DP 13A, and/or DP 14A as in  FIG.  1   ) for a user equipment of a communication network, a maximum power reduction operation caused by a maximum permissible exposure constraint. Means, based on the determining, for causing (TRANS  10 D, TRANS  12 D, TRANS  13 D, and/or TRANS  14 D; MEM  10 B, MEM  12 B, MEM  13 B, and/or MEM  14 B; PROG  10 C, PROG  12 C, PROG  13 C, and/or PROG 14 C; and DP 10A, DP 12A, DP 13A, and/or DP 14A as in  FIG.  1   ) configuration of a different candidate uplink beam pair of the at least one candidate uplink beam pair for communicating (TRANS  10 D, TRANS  12 D, TRANS  13 D, and/or TRANS  14 D; MEM  10 B, MEM  12 B, MEM  13 B, and/or MEM  14 B; PROG  10 C, PROG  12 C, PROG  13 C, and/or PROG 14 C; and DP 10A, DP 12A, DP 13A, and/or DP 14A as in  FIG.  1   ) towards the communication network. Then means for communicating (TRANS  10 D, TRANS  12 D, TRANS  13 D, and/or TRANS  14 D; MEM  10 B, MEM  12 B, MEM  13 B, and/or MEM  14 B; PROG  10 C, PROG  12 C, PROG  13 C, and/or PROG 14 C; and DP 10A, DP 12A, DP 13A, and/or DP 14A as in  FIG.  1   ) at least one power headroom report for the candidate uplink beam pair based on the maximum permissible exposure constraint. 
     In the example aspect of the invention according to the paragraph above, wherein at least the means for determining, configuring, causing, and communicating comprises transceiver [TRANS  10 D, TRANS  12 D, TRANS  13 D, and/or TRANS  14 D as in  FIG.  1   ] a non-transitory computer readable medium [MEM  10 B, MEM  12 B, MEM  13 B, and/or MEM  14 B as in  FIG.  1   ] encoded with a computer program [PROG  10 C, PROG  12 C, PROG  13 C, and/or PROG 14 C as in  FIG.  1   ] executable by at least one processor [DP 10A, DP 12A, DP 13A, and/or DP 14A as in  FIG.  1   ]. 
     Further, it is noted that at least some of the advantages of using example embodiments of the invention as described herein include at least:
         Providing robust mechanism to signal MPE indication to the gNB in FR2 and above 52.6 GHz scenarios where UE may operate having multiple uplink beam pair links available; and   Sending the indication (beyond informing that the MPE event started) is informing that MPE event has ended on a certain beam pair link, thus enabling fast recovery to the ‘original’ link, triggered by UE.       

     Further, in accordance with example embodiments of the invention there is circuitry for performing operations in accordance with example embodiments of the invention as disclosed herein. This circuitry can include any type of circuitry including content coding circuitry, content decoding circuitry, processing circuitry, image generation circuitry, data analysis circuitry, etc.). Further, this circuitry can include discrete circuitry, application-specific integrated circuitry (ASIC), and/or field-programmable gate array circuitry (FPGA), etc. as well as a processor specifically configured by software to perform the respective function, or dual-core processors with software and corresponding digital signal processors, etc.). Additionally, there are provided necessary inputs to and outputs from the circuitry, the function performed by the circuitry and the interconnection (perhaps via the inputs and outputs) of the circuitry with other components that may include other circuitry in order to perform example embodiments of the invention as described herein. 
     In accordance with example embodiments of the invention as disclosed in this application this application, the “circuitry” provided can include at least one or more or all of the following:
         (a) hardware-only circuit implementations (such as implementations in only analog and/or digital circuitry);   (b) combinations of hardware circuits and software, such as (as applicable):
           (i) a combination of analog and/or digital hardware circuit(s) with software/firmware; and   (ii) any portions of hardware processor(s) with software (including digital signal processor(s)), software, and memory(ies) that work together to cause an apparatus, such as a mobile phone or server, to perform various functions, such as functions or operations in accordance with example embodiments of the invention as disclosed herein); and   
           (c) hardware circuit(s) and or processor(s), such as a microprocessor(s) or a portion of a microprocessor(s), that requires software (e.g., firmware) for operation, but the software may not be present when it is not needed for operation.”       

     As used in this application, the term ‘ circuitry’ refers to all of the following: 
     (a) hardware-only circuit implementations (such as implementations in only analog and/or digital circuitry); and 
     (b) to combinations of circuits and software (and/or firmware), such as (as applicable): (i) to a combination of processor(s) or (ii) to portions of processor(s)/software (including digital signal processor(s)), software, and memory(ies) that work together to cause an apparatus, such as a mobile phone or server, to perform various functions); and 
     (c) to circuits, such as a microprocessor(s) or a portion of a microprocessor(s), that require software or firmware for operation, even if the software or firmware is not physically present. 
     This definition of ‘circuitry’ applies to all uses of this term in this application, including in any claims. As a further example, as used in this application, the term “circuitry” would also cover an implementation of merely a processor (or multiple processors) or portion of a processor and its (or their) accompanying software and/or firmware. The term “circuitry” would also cover, for example and if applicable to the particular claim element, a baseband integrated circuit or applications processor integrated circuit for a mobile phone or a similar integrated circuit in a server, a cellular network device, or other network device. 
     In general, the various embodiments may be implemented in hardware or special purpose circuits, software, logic or any combination thereof. For example, some aspects may be implemented in hardware, while other aspects may be implemented in firmware or software which may be executed by a controller, microprocessor or other computing device, although the invention is not limited thereto. While various aspects of the invention may be illustrated and described as block diagrams, flow charts, or using some other pictorial representation, it is well understood that these blocks, apparatus, systems, techniques or methods described herein may be implemented in, as non-limiting examples, hardware, software, firmware, special purpose circuits or logic, general purpose hardware or controller or other computing devices, or some combination thereof. 
     Embodiments of the inventions may be practiced in various components such as integrated circuit modules. The design of integrated circuits is by and large a highly automated process. Complex and powerful software tools are available for converting a logic level design into a semiconductor circuit design ready to be etched and formed on a semiconductor substrate. 
     The word “exemplary” may be used herein is intended to mean “serving as an example, instance, or illustration.” Any embodiment described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other embodiments. All of the embodiments described in this Detailed Description are exemplary embodiments provided to enable persons skilled in the art to make or use the invention and not to limit the scope of the invention which is defined by the claims. 
     The foregoing description has provided by way of exemplary and non-limiting examples a full and informative description of the best method and apparatus presently contemplated by the inventors for carrying out the invention. However, various modifications and adaptations may become apparent to those skilled in the relevant arts in view of the foregoing description, when read in conjunction with the accompanying drawings and the appended claims. However, all such and similar modifications of the teachings of this invention will still fall within the scope of this invention. 
     It should be noted that the terms “connected,” “coupled,” or any variant thereof, mean any connection or coupling, either direct or indirect, between two or more elements, and may encompass the presence of one or more intermediate elements between two elements that are “connected” or “coupled” together. The coupling or connection between the elements can be physical, logical, or a combination thereof. As employed herein two elements may be considered to be “connected” or “coupled” together by the use of one or more wires, cables and/or printed electrical connections, as well as by the use of electromagnetic energy, such as electromagnetic energy having wavelengths in the radio frequency region, the microwave region and the optical (both visible and invisible) region, as several non-limiting and non-exhaustive examples. Furthermore, some of the features of the preferred embodiments of this invention could be used to advantage without the corresponding use of other features. As such, the foregoing description should be considered as merely illustrative of the principles of the invention, and not in limitation thereof.