Abstract:
The present disclosure relates to a communication method and system for converging a 5 th -Generation (5G) communication system for supporting higher data rates beyond a 4 th -Generation (4G) system with a technology for Internet of Things (IoT). The present disclosure may be applied to intelligent services based on the 5G communication technology and the IoT-related technology, such as smart home, smart building, smart city, smart car, connected car, health care, digital education, smart retail, security and safety services. An information format and apparatus used by a base station to make a scheduling decision when the base station allocates resources to a terminal in a mobile communication system are provided. Operations of a terminal to report a maximum transmission power accurately to the base station in a scheduling process are also provided. A method for calculating a maximum transmit power in a constant manner regardless of a channel status is also provided.

Description:
PRIORITY 
       [0001]    This application is a continuation application of prior application Ser. No. 14/823,435, filed on Aug. 11, 2015 which is a continuation application of prior application Ser. No. 13/169,507, filed on Jun. 27, 2011, which issued as U.S. Pat. No. 9,113,422 on Aug. 18, 2015 and claimed the benefit under 35 U.S.C. §119(a) of Korean patent applications filed on Jun. 28, 2010 and Oct. 22, 2010 in the Korean Intellectual Property Office and assigned Serial Nos. 10-2010-0061166 and 10-2010-0103549, respectively, the entire disclosure of each of which are hereby incorporated by reference. 
     
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
       [0002]    The present invention relates to a mobile communication system. More particularly, the present invention relates to a method and apparatus of a mobile terminal for reporting a maximum transmission power to assist scheduling decision making of a base station in the wireless communication system. 
       2. Description of the Related Art 
       [0003]    To meet the demand for wireless data traffic having increased since deployment of 4G communication systems, efforts have been made to develop an improved 5G or pre-5G communication system. Therefore, the 5G or pre-5G communication system is also called a ‘Beyond 4G Network’ or a ‘Post LTE System’. The 5G communication system is considered to be implemented in higher frequency (mmWave) bands, e.g., 60 GHz bands, so as to accomplish higher data rates. To decrease propagation loss of the radio waves and increase the transmission distance, the beamforming, massive multiple-input multiple-output (MIMO), Full Dimensional MIMO (FD-MIMO), array antenna, an analog beam forming, large scale antenna techniques are discussed in 5G communication systems. In addition, in 5G communication systems, development for system network improvement is under way based on advanced small cells, cloud Radio Access Networks (RANs), ultra-dense networks, device-to-device (D2D) communication, wireless backhaul, moving network, cooperative communication, Coordinated Multi-Points (CoMP), reception-end interference cancellation and the like. In the 5G system, Hybrid FSK and QAM Modulation (FQAM) and sliding window superposition coding (SWSC) as an advanced coding modulation (ACM), and filter bank multi carrier (FBMC), non-orthogonal multiple access (NOMA), and sparse code multiple access (SCMA) as an advanced access technology have been developed. 
         [0004]    The Internet, which is a human centered connectivity network where humans generate and consume information, is now evolving to the Internet of Things (IoT) where distributed entities, such as things, exchange and process information without human intervention. The Internet of Everything (IoE), which is a combination of the IoT technology and the Big Data processing technology through connection with a cloud server, has emerged. As technology elements, such as “sensing technology”, “wired/wireless communication and network infrastructure”, “service interface technology”, and “Security technology” have been demanded for IoT implementation, a sensor network, a Machine-to-Machine (M2M) communication, Machine Type Communication (MTC), and so forth have been recently researched. Such an IoT environment may provide intelligent Internet technology services that create a new value to human life by collecting and analyzing data generated among connected things. IoT may be applied to a variety of fields including smart home, smart building, smart city, smart car or connected cars, smart grid, health care, smart appliances and advanced medical services through convergence and combination between existing Information Technology (IT) and various industrial applications. 
         [0005]    In line with this, various attempts have been made to apply 5G communication systems to IoT networks. For example, technologies such as a sensor network, Machine Type Communication (MTC), and Machine-to-Machine (M2M) communication may be implemented by beamforming, MIMO, and array antennas. Application of a cloud Radio Access Network (RAN) as the above-described Big Data processing technology may also be considered to be as an example of convergence between the 5G technology and the IoT technology. 
         [0006]    Mobile communication systems were developed to provide subscribers with voice communication services on the move. With the advance of technologies, the mobile communications have been evolved to support high speed data communication services as well as the standard voice communication services. 
         [0007]    Recently, as a next generation mobile communication system, Long Term Evolution (LTE) is being standardized by the 3rd Generation Partnership Project (3GPP). LTE is designed to provide for a downlink speed of up to 100 Mbps. In order to fulfill the requirements of the LTE systems, studies have been done of various aspects including minimization of the number of involved nodes in the connections and placing the radio protocol as close as possible to the radio channels. 
         [0008]    In the meantime, unlike the standard voice service, most data services are allocated resources according to the amount of data to be transmitted and channel conditions. Accordingly, in the wireless communication system such as a cellular communication system, it is important to manage resource allocation based on the resource scheduled for data transmission, channel condition, and a data amount to be transmitted. This is true even in the LTE system, and the base station scheduler manages and assigns radio resources. 
         [0009]    In the LTE system, the User Equipment (UE) provides the evolved Node B (eNB) with scheduling information to assist uplink scheduling. The scheduling information includes a Buffer Status Report (BSR) and a Power Headroom Report (PHR). Particularly, PHR is used to prevent the total transmit power from exceeding the maximum transmit power limit when the eNB assigns the resources of uplink transmission of the UE. Since inaccurate PHR information causes scheduling errors or interference to other transmissions, it is very important for the eNB to interpret the PHR reported by the UE correctly. 
       SUMMARY OF THE INVENTION 
       [0010]    Aspects of the present invention are to address at least the above-mentioned problems and/or disadvantages and to provide at least the advantages described below. Accordingly, an aspect of the present invention is to provide a method, apparatus, and system for processing scheduling information effectively in a mobile communication system. 
         [0011]    Another aspect of the present invention is to provide a method, apparatus, and system for processing scheduling information efficiently between a User Equipment (UE) and an evolved Node B (eNB) in a mobile communication system. 
         [0012]    Furthermore, an aspect of the present invention provides a method, apparatus, and system for improving an accuracy of an available transmit power report of a UE in a mobile communication system. 
         [0013]    According to an aspect of the present invention, a method for improving an accuracy of a power headroom report used in scheduling of the base station in a mobile communication system is provided. The method includes determining a maximum transmit power of a cell (P CMAX ) for use in calculation of the power headroom, and transmitting the P CMAX  to the base station. 
         [0014]    In the mobile communication system according to an aspect of the present invention, when a terminal determines a P CMAX , the same P CMAX  is selected in both cases where the power reduction is not necessary due to the required Physical Uplink Shared CHannel (PUSCH) power being significantly lower than P CMAX  and where the power reduction probability is very high due to the required PUSCH power being similar to the P CMAX . 
         [0015]    In the mobile communication system according to an aspect of the present invention, the P CMAX  is indicated with two bits in order to reduce the overhead for reporting P CMAX  to the base station, and the P CMAX  is carried by two reserved bits of power headroom Medium Access Control (MAC) Control Element (CE). 
         [0016]    In the mobile communication system according to an aspect of the present invention, the MAC CE format for transmitting accurate P CMAX  value to the base station and P CMAX  report trigger conditions are included. 
         [0017]    In the mobile communication system according to an aspect of the present invention, the base station manages the P CMAX  values reported by the terminal in the form of a database, requests, when a scheduling situation is omitted, the terminal to report P CMAX , and transmits an uplink grant reflecting the scheduling situation. 
         [0018]    In more detail, the scheduling information report method of a terminal in a mobile communication system according to an aspect of the present invention includes selecting, when uplink transmission is triggered, a maximum transmit power (P CMAX ) between a highest value and a lowest value for the maximum transmit power; determining, when Power Headroom Report (PHR) is triggered, a Power Headroom (PH) of the terminal using the selected maximum transmit power; and transmitting a PHR message including the maximum transmit power and the PH to a base station. 
         [0019]    The terminal for reporting scheduling information in a mobile communication system according to an aspect of the present invention includes a transceiver for transmitting the scheduling information to a base station and for receiving a control message transmitted by the base station and a controller for controlling to select, when uplink transmission is triggered, a maximum transmit power (P CMAX ) between a highest value and a lowest value for the maximum transmit power, to determine, when a PHR is triggered, a PH of the terminal using the selected maximum transmit power, and to transmit a power headroom report message, including the maximum transmit power and the power headroom, to a base station. 
         [0020]    The scheduling information processing method of a base station in a mobile communication system according to an aspect of the present invention includes receiving scheduling information transmitted by a terminal, the scheduling information including a maximum transmit power and a power headroom, storing the scheduling information, and assigning resources to the terminal based on the stored scheduling information. 
         [0021]    The base station for processing scheduling information in a mobile communication system according to an aspect of the present invention includes a transceiver for receiving scheduling information transmitted by a terminal, the scheduling information including a maximum transmit power and a power headroom, a storage for storing the scheduling information, and a controller for assigning resources to the terminal based on the scheduling information. 
         [0022]    Other aspects, advantages, and salient features of the invention will become apparent to those skilled in the art from the following detailed description, which, taken in conjunction with the annexed drawings, discloses exemplary embodiments of the invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0023]    The above and other aspects, features, and advantages of certain exemplary embodiments of the present invention will be more apparent from the following description taken in conjunction with the accompanying drawings, in which: 
           [0024]      FIG. 1  is a schematic diagram illustrating an exemplary architecture of a Long Term Evolution (LTE) mobile communication system according to the related art; 
           [0025]      FIG. 2  is a diagram illustrating a protocol stack for a User Equipment (UE) and an evolved Node B (eNB) in the LTE mobile communication system of  FIG. 1  according to the related art; 
           [0026]      FIG. 3  is a signaling diagram illustrating operations of a UE and a network for scheduling based on a Power Headroom Report (PHR) in an LTE system according to an exemplary embodiment of the present invention; 
           [0027]      FIG. 4  is a diagram illustrating an exemplary situation of a transmit power control based on a PHR in the mobile communication system operating as shown in  FIG. 3  according to an exemplary embodiment of the present invention; 
           [0028]      FIG. 5  is a diagram illustrating another exemplary situation of a transmit power control based on a PHR in the mobile communication system operating as shown in  FIG. 3  when an eNB knows an incorrect maximum transmit power of a cell (P CMAX ) according to an exemplary embodiment of the present invention; 
           [0029]      FIG. 6  is a signaling diagram illustrating operations of a UE and a network for scheduling of an eNB based on a Power Headroom (PH) value and P CMAX  reported by the UE according to an exemplary embodiment of the present invention; 
           [0030]      FIG. 7  is a diagram illustrating a format of a Power Headroom (PH) Medium Access Control (MAC) Control Element (CE) defined in the LTE standard according to a first exemplary embodiment of the present invention; 
           [0031]      FIG. 8  is a flowchart illustrating a procedure for a UE to report P CMAX  according to a second exemplary embodiment of the present invention; 
           [0032]      FIG. 9  is a diagram illustrating a format of a MAC CE (maximum transmit power report message) for a UE to report P CMAX  to an eNB according to the second exemplary embodiment of the present invention; 
           [0033]      FIG. 10  is a flowchart illustrating a procedure for an eNB to manage P CMAX  or power reduction of a UE in a form of a database according to a third exemplary embodiment of the present invention; 
           [0034]      FIG. 11  is a block diagram illustrating a configuration of a UE according to an exemplary embodiment of the present invention; 
           [0035]      FIG. 12  is a block diagram illustrating a configuration of an eNB according to an exemplary embodiment of the present invention; 
           [0036]      FIG. 13  is a signaling diagram illustrating operations of a UE and an eNB for a method according to a fourth exemplary embodiment of the present invention; 
           [0037]      FIG. 14  is a flowchart illustrating a procedure of a UE in a method according to the fourth exemplary embodiment of the present invention; and 
           [0038]      FIG. 15  is a flowchart illustrating a procedure of a UE in a method according to a modified case of the fourth exemplary embodiment of the present invention. 
       
    
    
       [0039]    Throughout the drawings, it should be noted that like reference numbers are used to depict the same or similar elements, features, and structures. 
       DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS 
       [0040]    The following description with reference to the accompanying drawings is provided to assist in a comprehensive understanding of exemplary embodiments of the invention as defined by the claims and their equivalents. It includes various specific details to assist in that understanding but these are to be regarded as merely exemplary. Accordingly, those of ordinary skill in the art will recognize that various changes and modifications of the exemplary embodiments described herein can be made without departing from the scope and spirit of the invention. In addition, descriptions of well-known functions and constructions may be omitted for clarity and conciseness. 
         [0041]    The terms and words used in the following description and claims are not limited to the bibliographical meanings, but, are merely used by the inventor to enable a clear and consistent understanding of the invention. Accordingly, it should be apparent to those skilled in the art that the following description of exemplary embodiments of the present invention is provided for illustration purpose only and not for the purpose of limiting the invention as defined by the appended claims and their equivalents. 
         [0042]    It is to be understood that the singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to “a component surface” includes reference to one or more of such surfaces. 
         [0043]    Exemplary embodiments of the present invention relate to a method and apparatus of a User Equipment (UE) for reporting a maximum transmit power to assist scheduling decision making of an evolved Node B (eNB) in a mobile communication system. Prior to the explanation of the exemplary embodiments of the present invention, a description is made of a Long Term Evolution (LTE) mobile communication system with reference to  FIGS. 1 and 2 . 
         [0044]      FIG. 1  is a schematic diagram illustrating an exemplary architecture of an LTE mobile communication system according to the related art. 
         [0045]    Referring to  FIG. 1 , the radio access network of the LTE mobile communication system includes a plurality of eNBs  105 ,  110 ,  115 , and  120 , a Mobility Management Entity (MME)  125 , and a Serving-Gateway (S-GW)  130 . The UE  135  connects to an external network via an eNB and S-GW  130 . 
         [0046]    Each of the eNBs  105 ,  110 ,  115 , and  120  corresponds to the legacy Node B of the Universal Mobile Telecommunications System (UMTS). The eNB is coupled with the UE  135  and is responsible for more complicated functions as compared to a legacy Node B. 
         [0047]    In LTE, all types of user traffic, including real time services such as Voice over Internet Protocol (VoIP), are transmitted over a shared channel, and thus there is a need for a device (such as eNBs  105 ,  110 ,  115 , and  120 ) for scheduling data transmission based on status information collected from the UEs. Typically, an eNB controls a plurality of cells. LTE adopts Orthogonal Frequency Division Multiplexing (OFDM) to support up to 20 MHz bandwidth. LTE also employs Adaptive Modulation and Coding (AMC) to determine a modulation scheme and a channel coding rate adaptive to a channel condition of the UE. 
         [0048]    The S-GW  130  is responsible for providing data bearers so as to establish or release a data bearer under the control of the MME  125 . The MME  125  is responsible for various control functions and is coupled to a plurality of eNBs. 
         [0049]      FIG. 2  is a diagram illustrating a protocol stack for a UE and an eNB in the LTE mobile communication system of  FIG. 1  according to the related art. 
         [0050]    Referring to  FIG. 2 , the LTE protocol stack includes Packet Data Convergence Protocol (PDPC) layer  205  and  240 , Radio Link Control (RLC) layer  210  and  235 , Medium Access Control (MAC) layer  215  and  230 , and physical layer (PHY)  220  and  225 . 
         [0051]    The PDCP layer  205  and  240  is responsible for Internet Protocol (IP) header compression/decompression, and the RLC layer  210  and  235  is responsible for packing the PDCP Packet Data Units (PDUs) into a size appropriate for transmission and for performing an Automatic Repeat Request (ARQ) function. The MAC layer  215  and  230  serves multiple RLC layer entities and multiplexes the RLC PDUs into a MAC PDU and de-multiplexes a MAC PDU into the RLC PDUs. The physical layer PHY  220  and  225  is responsible for encoding and modulation of the upper layer data to transmit through a radio channel, and demodulation and decoding of an OFDM symbol received through radio channel to deliver to upper layers. From the viewpoint of a transmitter, the data unit input to a protocol entity is called Service Data Unit (SDU) and the data unit output from the protocol entity is called Protocol Data Unit (PDU). 
         [0052]    In the LTE mobile communication system, since the uplink transmission causes interference to transmissions on other bandwidths, it is necessary to limit the uplink transmit power below a predetermined level. That is, spurious emission limitations should be met. For this purpose, the UE calculates uplink transmit power using a predetermined function, and performs uplink transmission at the calculated uplink transmit power level. For example, the UE calculates the required uplink transmit power value by applying the scheduling information such as an allocated resource amount and Modulation and Coding Scheme (MCS) to be adopted, and input values for estimating channel status such as path-loss value, and performs uplink transmission with the calculated required uplink transmit power value. The uplink transmit power value available for the UE is limited by the maximum transmit power value of the UE and, if the calculated required uplink transmit power value is greater than the maximum transmit power value, the UE performs the uplink transmission with the maximum transmit power value. In this case, since the uplink transmit power is less than the calculated required power, the uplink transmission quality is likely degraded. Accordingly, it is preferable for the eNB to perform scheduling such that the required transmit power does not exceed the maximum transmit power. However, since some parameters such as path-loss cannot be checked by the eNB, the UE reports its power headroom by transmitting the Power Headroom Report (PHR) if necessary. 
         [0053]      FIG. 3  is a signaling diagram illustrating operations of a UE and network for scheduling based on PHR in an LTE mobile communication system according to an exemplary embodiment of the present invention. 
         [0054]    Referring to  FIG. 3 , in the LTE system, the UE  310  calculates the power headroom by Equation (1): 
         [0000]      Power Headroom= P   CMAX −Required PUSCH Power  Equation (1)
 
         [0055]    In Equation (1), P CMAX  denotes the maximum transmit power of the UE, and Required PUSCH Power denotes the transmit power assigned for the uplink transmission of the UE. Here, PUSCH means Physical Uplink Shared Channel. The UE calculates the Power Headroom using Equation (1) at step  320  and reports the Power Headroom to the eNB Network (N/W) interface  315  at step  325 , and the eNB  315  determines a number of Resource Blocks (RBs) and MCS per transmission resource with which the transmit power does not exceed the maximum transmit power at scheduling step  330 . 
         [0056]      FIG. 4  is a diagram illustrating an exemplary situation of a transmit power control based on PHR in the LTE mobile communication system operating as shown in  FIG. 3  according to an exemplary embodiment of the present invention. 
         [0057]    As aforementioned, the Power Headroom  410  is a value obtained by subtracting the required PUSCH power from P CMAX    435 , and the required PUSCH power is a value determined depending on the transmit power  415  under the given modulation scheme and number of RBs, path-loss degree  420 , transmit power adjustment value to be applied to PUSCH  425 , and transmit power offset of PUSCH  430 . The calculated power headroom  410  is reported to the eNB by means of PHR, and the eNB makes scheduling decisions based on the PHR as denoted by reference number  440 . 
         [0058]    The operation depicted in  FIG. 4  is carried out normally when the power headroom value reported to the eNB through PHR is accurate. In Equation (1), the required PUSCH power can be maintained without additional signaling between the eNB and UE. Meanwhile, P CMAX    435  is a parameter can be set to a certain value by the UE. According to the LTE standard, P CMAX  is selected by the UE between the lowest value and the highest value according to Equation (2): 
         [0000]        P   CMAX   _   L   ≦P   CMAX   ≦P   CMAX   _   H   Equation (2)
 
         [0000]    In Equation (2), P CMAX  Low (P CMAX   _   L ) and P CMAX  High (P CMAX   _   H ) are calculated by Equation (3) and Equation (4), respectively. 
         [0000]        P   CMAX   _   L =MIN{ P   EMAX   −ΔT   C   ,P   PowerClass −MPR−A-MPR−Δ T   C }  Equation (3)
 
         [0000]        P   CMAX   _   H =MIN{ P   EMAX   ,P   PowerClass }  Equation (4)
 
         [0000]    where P EMAX , ΔT C , P PowerClass , Maximum Power Reduction (MPR), and Additional MPR (A-MPR) are as specified in TS36.101 and can be simply explained as follows. P EMAX  is a maximum uplink transmit power of the cell in which the UE is located and notified to the UE by the eNB. P PowerClass  means a maximum transmit power derived from physical characteristics of the UE. The power class is determined at the manufacturing stage, and the UE notifies the eNB of the power class by means of a Radio Resource Control (RRC) message. MPR, A-MPR, and ΔT C  are parameters for defining a limit value for the UE to adjust the maximum transmit power in order to meet the spurious emission to a certain requirement. MPR is the value determined by the amount of the allocated transmission resource (i.e., bandwidth) and modulation scheme, and the values of MPR for individual cases are defined in table 6.2.3.-1 of TS36.101. A-MPR is the value defined by the frequency band for uplink transmission, local characteristic, and uplink transmission bandwidth and defined in tables 6.2.4-1, 6.2.4-2, and 6.2.4-3 of TS36.101. A-MPR is used for the case where there is a frequency band sensitive to the spurious emission around according to the local characteristics and frequency band characteristics. ΔT C  is used for additional transmit power adjustment in a case where the uplink transmission is performed around the edges of the frequency band. If the uplink transmission is performed in the lowest 4 MHz bandwidth or the highest 4 MHz bandwidth of a certain frequency band, the UE sets ΔT C  to 1.5 dB, and otherwise to 0. 
         [0059]    As shown in Equation (2), since P CMAX  is selected by the UE from the highest value and the lowest value, it is necessary for the UE to report the P CMAX  as well as the power headroom value for accurate scheduling decision making of the eNB base on PHR. 
         [0060]    Table 1 shows the variation of P CMAX   _   L  according to the UE&#39;s situation and the variation of range in which P CMAX  is selected. In Table 1, it is noted that the range in which P CMAX  is selectable is 8 dBm in case 3 and this means that the maximum value of P CMAX  is about 6 times greater than its minimum value. 
         [0000]    
       
         
               
               
               
             
               
               
               
               
             
           
               
                 TABLE 1 
               
               
                   
               
               
                 Case 
                 P CMAX     —     L   
                 Note 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 1. 
                 UE is scheduled with 20 RBs/16QAM 
                 MIN [P CMAX  − ΔT c , P           − MPR − 
                 UE choose its P CMAX  in [21~23 dBm] 
               
               
                   
                 in 20 MHz cell: MPR = 2 dB. 
                 A-MPR − ΔT c ] = MIN [23 − 0, 23 − 2 − 
               
               
                   
                   
                 0 − 0] = 21 dBm 
               
               
                 2. 
                 UE is scheduled with 19 RBs/QPSK in 
                 MIN [23 − 1.5, 23 − 1 − 1 − 1.5] = 19.5 dBm 
                 UE choose its P CMAX  in 
               
               
                   
                 20 MHz cell: MPR = 1 dB 
                   
                 [19.5~23 dBm] 
               
               
                   
                 UE is signalled with NS_03 and is 
               
               
                   
                 operating in band 2: A-MPR = 1 dB 
               
               
                   
                 The scheduled resource is at the 
               
               
                   
                 edge of band 2: ΔT c  = 1.5 dB 
               
               
                 3. 
                 UE is signaled with NS_07 and in 
                 MIN [23 − 0, 23 − 0 − 8 − 0] = 15 dBm 
                 UE choose its P CMAX  in [15~23 dBm] 
               
               
                   
                 region A. It is scheduled with 8 RBs 
               
               
                   
                 whose RB indexes are 0~7: A-MPR = 
               
               
                   
                 8 dB 
               
               
                   
               
               
                             indicates data missing or illegible when filed 
               
             
          
         
       
     
         [0061]      FIG. 5  is a diagram illustrating another exemplary situation of a transmit power control based on PHR in the LTE mobile communication system operating as shown in  FIG. 3  when an eNB knows an incorrect P CMAX  according to an exemplary embodiment of the present invention. 
         [0062]    Referring to  FIG. 5 , in the case where the eNB has performed scheduling under the assumption of P CMAX    535  being equal to P CMAX   _   H  but the P CMAX  set by the UE is actually less than the P CMAX   _   H , in order to use the entire allocated resource, it is require to use a transmit power greater than P CMAX , resulting in failure to meet the Spurious Emission Requirement as denoted by reference number  540 . RPH  510 , Transmit Power  515 , Path-Loss Degree  520 , Transmit Power Adjustment Value  525 , and PUSCH power offset  530  are determined the same as the corresponding elements of  FIG. 4 . 
         [0063]    In order for the eNB to calculate the required PUSCH power from the power headroom reported by the UE, an exemplary embodiment of the present invention allows the UE to send to the eNB a P CMAX  determined appropriately. 
         [0064]      FIG. 6  is a signaling diagram illustrating operations of a UE and network for scheduling of an eNB based on a Power Headroom (PH) value and P CMAX  reported by the UE according to an exemplary embodiment of the present invention. 
         [0065]    Referring to  FIG. 6 , the UE  610  determines the P CMAX  according to the situation at step  620 , calculates the power headroom based on the P CMAX  at step  625 , and reports the power headroom and P CMAX  to the eNB Network (N/W) interface  615  at step  630 . The eNB  615  makes scheduling decisions accurately based on this information at step  635 . 
         [0066]    In an exemplary embodiment of the present invention, the UE is configured to select a same P CMAX  value always, regardless of the required PUSCH power in calculation of the power headroom. That is, for both the cases where the required PUSCH power is significantly less than P CMAX  such that P CMAX , regardless of its value, does not influence to the current transmission of the UE and where the required PUSCH power is similar to P CMAX  such that P CMAX  influences a current transmission of the UE significantly, P CMAX  is set to the same value. 
         [0067]    A description is made with reference to the relationship between the above-described required PUSCH power and P CMAX . Suppose that the required PUSCH power is high due to a bad channel condition between the UE and the eNB. In this case, the required PUSCH power may be similar to P CMAX  or, in some bad channel conditions, greater than P CMAX . If the required PUSCH power is greater than P CMAX , the UE adjusts the transmit power to match P CMAX  (power reduction) to meet the spurious emission requirement, and in this case the value set for P CMAX  influences the system performance significantly. If P CMAX  is set to a value too small, the UE lowers the transmit value unnecessarily in spite of the availability of higher transmit power, resulting in frequent transmit errors. In contrast, if P CMAX  is set to a value too large, it does not meet the spurious emission requirement, resulting in interference to adjacent frequency bands. Accordingly, in order to improve the system performance, it is advantageous for the UE to select a value greatest among the values meeting the spurious emission requirement in the range between P CMAX   _   L  and P CMAX   _   H . 
         [0068]    Suppose that the required PUSCH power is very low, due to very good channel quality between the UE and eNB. In this case, since the required PUSCH power is low, it is possible to meet the spurious emission requirement regardless of the value of the P CMAX . The simplest method for determining P CMAX  appropriately for such case is to set P CMAX  to the value of P CMAX   _   H . In this case, however, when it is required to adjust P CMAX  afterward, i.e., when the required PUSCH power increases due to channel status degradation, the UE cannot provide the eNB with the information on the P CMAX  to be used. As aforementioned, even when the P CMAX  does not influence the current transmission due to the very low required PUSCH power, it is necessary to determine the P CMAX  equally as in the situation in which the P CMAX  is adjusted appropriately due to the high required PUSCH power. 
         [0069]    For this purpose, when the required PUSCH power is very low, the UE determines P CMAX  in consideration of a predetermined high required PUSCH power, e.g., a virtual required PUSCH power equal to P CMAX   _   H , rather than the actual required PUSCH power. It is noted that the virtual required PUSCH power is used only for determining P CMAX  but the power headroom value is calculated using the actual required PUSCH power. 
         [0070]    After determining P CMAX , the UE should report the P CMAX  to the eNB. Although P CMAX  can be reported in various ways, the method using the power headroom MAC Control Element (CE) message as defined in the LTE standard is adopted in the first exemplary embodiment of the present invention. 
       First Exemplary Embodiment 
       [0071]      FIG. 7  is a diagram illustrating a format of the power headroom MAC CE defined in the LTE standard according to a first exemplary embodiment of the present invention. 
         [0072]    Referring to  FIG. 7 , the power headroom MAC CE has a length of 1 octet with 6 bits  715  indicating a power headroom level. With 6 bits, it is possible to express 64 power headroom levels, and the index representing a power headroom level is transmitted on behalf of the value of the power headroom level itself. 
         [0073]    Except for the 6 bits designated for the indication of the power headroom level, the remaining 2 bits  710  are reserved for future use. In the first exemplary embodiment of the present invention, a method for reporting the P CMAX  value used for calculating PH value with the 2 reserved bits of the power headroom MAC CE is provided to avoid additional overhead. The UE can report one of four values of P CMAX  with two bits. In the first exemplary embodiment of the present invention, three methods for reporting the PCMAX value to the eNB effectively are provided. 
         [0074]    1) Method A 
         [0000]    
       
         
               
               
             
           
               
                   
               
               
                 Bit 
                 Meaning 
               
               
                   
               
             
             
               
                 00 
                 P CMAX  = P CMAX     —     L   
               
               
                 01 
                 P CMAX     —     L  &lt; P CMAX  ≦ P CMAX     —     L  + (P CMAX     —     H  − P CMAX     —     L )/2 
               
               
                 10 
                 P CMAX     —     L  + (P CMAX     —     H  − P CMAX     —     L )/2 &lt; P CMAX  ≦ P CMAX     —     H   
               
               
                 11 
                 P CMAX  = P CMAX     —     H   
               
               
                   
               
             
          
         
       
     
         [0075]    2) Method B 
         [0000]                                Bit   Meaning                   00   P CMAX     —     L  ≦ P CMAX  ≦ P CMAX     —     L  + (P CMAX     —     H  − P CMAX     —     L )/4       01   P CMAX     —     L  + (P CMAX     —     H  − P CMAX     —     L )/4 &lt; P CMAX  ≦ P CMAX     —     L  + 2 *           (P CMAX     —     H  − P CMAX     —     L )/4       10   P CMAX     —     L  + 2 * (P CMAX     —     H  − P CMAX     —     L  )/4 &lt; P CMAX  ≦ P CMAX     —     L  +           3 * (P CMAX     —     H  − P CMAX     —     L )/4       11   P CMAX     —     L  + 3 * (P CMAX     —     H  − P CMAX     —     L )/4 &lt; P CMAX  ≦ P CMAX     —     H                      
In the third method, the power reduction is reported on behalf of the PCMAX value.
 
         [0076]    3) Method C 
         [0000]    
       
         
               
               
             
           
               
                   
               
               
                 Bit 
                 Meaning 
               
               
                   
               
             
             
               
                 00 
                 0 &lt; Power Reduction &lt; K/4 
               
               
                 01 
                 K/4 &lt; Power Reduction &lt; 2K/4 
               
               
                 10 
                 2K/4 &lt; Power Reduction &lt; 3K/4 
               
               
                 11 
                 3K/4 &lt; Power Reduction &lt; K 
               
               
                   
               
             
          
         
       
     
         [0077]    In the third method, K is equal to P CMAX   _   H −P CMAX   _   L . The aspects of the present invention can be addressed with any of the three provided methods. 
       Second Exemplary Embodiment 
       [0078]    In the first exemplary embodiment, the two reserved bits of the power headroom MAC CE are used to notify the eNB of P CMAX . This is advantageous to notify the eNB of P CMAX  without increase of overhead, but disadvantageous because two bits are often not enough to report P CMAX  accurately. In order to report more accurately P CMAX , the UE can use a new MAC CE. That is, the UE can use a MAC CE newly defined to indicate the P CMAX  value more accurately, such that when a predetermined condition is fulfilled, the UE reports the P CMAX  to the eNB. 
         [0079]      FIG. 8  is a flowchart illustrating a procedure for a UE to report P CMAX  according to a second exemplary embodiment of the present invention. 
         [0080]    Referring to  FIG. 8 , a P CMAX  Management Function is invoked at step  810 . The UE determines whether a predetermined condition is fulfilled at step  815  and, if the condition is fulfilled, generates the MAC CE (maximum transmit power report message) to report P CMAX  to the eNB at step  820 . 
         [0081]      FIG. 9  is a diagram illustrating a format of a MAC CE (maximum transmit power report message) for a UE to report P CMAX  to an eNB according to the second exemplary embodiment of the present invention. 
         [0082]    The conditions to determine a P CMAX  report can be as follows: 
         [0083]    Power reduction is performed as much as or greater than a predetermined amount; 
         [0084]    Selected P CMAX  differs from P CMAX   _   L ; 
         [0085]    Selected P CMAX  differs from P CMAX   _   H ; and 
         [0086]    Power reduction is performed in a different way from a recently reported power reduction, i.e., (P CMAX −P CMAX   _   L )/(P CMAX   _   H −P CMAX ) 
         [0087]    If the power is reduced as much as or greater than a predetermined amount, this may indicate that the difference between a most recently reported maximum transmit power and a currently reported maximum transmit power is greater than a predetermined reference value. 
         [0088]    In a case where one of the above conditions is fulfilled, the UE generates the MAC CE to report P CMAX  to the eNB. With the MAC CE received from the UE, the eNB can check the P CMAX  determined by the UE accurately. At this time, the UE can also trigger the PHR. 
       Third Exemplary Embodiment 
       [0089]    In a case where the UE reports the P CMAX  value to the eNB whenever the P CMAX  is reset, as in the first and second exemplary embodiments, it is necessary to allocate resources for a P CMAX  report repeatedly. However, if the eNB manages the information on the P CMAX  per UE&#39;s situation and/or power reduction occurred at the UE accumulatively in the form of a database, it is possible to determine the P CMAX  to be used and/or power reduction amount per UE&#39;s situation without periodic report after the collection of enough information. 
         [0090]      FIG. 10  is a flowchart illustrating a procedure for an eNB to manage P CMAX  or power reduction of a UE in the form of a database according to a third exemplary embodiment of the present invention. 
         [0091]    Referring to  FIG. 10 , a P CMAX  management function is invoked at step  1010 . Then an eNB collects the P CMAX  value (or power reduction amount) according to scheduling situation and, when database update is determined to be required at step  1015 , determines which scheduling condition is needed at step  1020 . The eNB sends the UE a P CMAX  reporting request message at step  1025  and then transmits an uplink grant reflecting the scheduling condition to the UE at step  1030 . The UE reports P CMAX  using the resource indicated by the uplink grant. In order to help understand this, a description is made with an exemplary case where the eNB records the power reduction information on UE1 as shown in Table 2: 
         [0000]    
       
         
               
               
               
             
               
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
               
             
           
               
                   
                 TABLE 2 
               
             
             
               
                   
                   
               
               
                   
                 Channel bandwidth/Transmission 
                 Power 
               
               
                   
                 bandwidth configuration (RB) 
                 reduction 
               
             
          
           
               
                   
                 1.4 
                 3.0 
                 5 
                 10 
                 15 
                 20 
                 of UE 1 
               
               
                 Modulation 
                 MHz 
                 MHz 
                 MHz 
                 MHz 
                 MHz 
                 MHz 
                 (dB) 
               
               
                   
               
             
          
           
               
                 QPSK 
                 &gt;5 
                 &gt;4 
                 &gt;8 
                 &gt;12 
                 &gt;16 
                 &gt;18 
                 1 
               
               
                 16 QAM 
                 ≦5 
                 ≦4 
                 ≦8 
                 ≦12 
                 ≦16 
                 ≦18 
                 1 
               
               
                 16 QAM 
                 &gt;5 
                 &gt;4 
                 &gt;8 
                 &gt;12 
                 &gt;16 
                 &gt;18 
                 ? 
               
               
                   
               
             
          
         
       
     
         [0092]    Referring to Table 2, in a case where the UE1 is configured with a Quadrature Phase Shift Keying (QPSK) modulation scheme and 8 or more Resource Blocks (RBs) in bandwidth of 5 MHz, the transmit power is reduced by 1 dB. In another case where the UE1 is configured with a 16 Quadrature Amplitude Modulation (QAM) modulation scheme and 8 or fewer RBs in the same bandwidth, the transmit power is reduced by 1 dB. In this manner, the eNB creates a database for storing information on the transmit power reduction according to the resource usage conditions and uses the database for resource allocation afterward. 
         [0093]    Referring to Table 2, the eNB has no information on power reduction for the case where the 16QAM modulation scheme is used and the number of RBs for each bandwidth is equal to or greater than a predetermined number. In such a situation where the eNB has not been updated yet, the eNB requests the UE to report power reduction information. In the above example, the eNB transmits the MAC CE requesting the UE1 for the power reduction report and instructs, with the first uplink grant, the UE1 to configure the transmission with 16QAM modulation scheme and 18 RBs. If an uplink grant is received after the receipt of the MAC control message requesting the power reduction report, the UE1 transmits the MAC CE containing the power reduction value in a next uplink transmission. 
         [0094]    The eNB receives the MAC CE containing the power reduction value and updates the database with the power reduction value. In the next resource allocation process, the eNB can estimate the power reduction amount according to UE&#39;s condition by referencing the database. 
         [0095]    In  FIG. 10 , the power reduction report is identical with the P CMAX  report. That is, the eNB can request from the UE a P CMAX  report, and the UE can report the selected P CMAX  to the eNB. At this time, the UE can transmit the PHR along with the P CMAX . 
         [0096]      FIG. 11  is a block diagram illustrating a configuration of a UE according to an exemplary embodiment of the present invention. 
         [0097]    Referring to  FIG. 11 , the UE includes a transceiver  1105 , a controller  1110 , a multiplexer/demultiplexer  1120 , a control message processor  1135 , and higher layer processors  1125  and  1130 . 
         [0098]    The transceiver  1105  is responsible for receiving data and control signals on a downlink carrier and for transmitting data and control signals on an uplink carrier. In a case where multiple carriers are aggregated, the transceiver  1105  can transmit/receive data and control signals on multiple carriers. Particularly in an exemplary embodiment of the present invention, the transceiver  1105  can send to the UE the scheduling information including a maximum transmit power information of the UE, a power headroom MAC CE, and a maximum transmit power report message which is newly defined herein. 
         [0099]    The multiplexer/demultiplexer  1120  is responsible for multiplexing the data generated by the higher layer processors  1125  and  1130  and the control message processor  1135  and demultiplexing the data received by the transceiver  1135 , and delivers the demultiplexed data to the higher layer processors  1125  and  1130 , the control message processor  1135 , and/or the controller  1110 . 
         [0100]    The control message processor  1135  is responsible for processing control messages received from the network. The control message processor  1135  extracts parameters related to the determination of P CMAX , e.g., P EMAX , among the parameters carried in the control message, and delivers the extracted parameters to the controller  1110 . 
         [0101]    The higher layer processors  1125  and  1130  can be differentiated according to services, and process and deliver data generated in association with user services such as File Transfer Protocol (FTP) and VoIP to the multiplexer/demultiplexer  1120 , or process and deliver data processed by the multiplexer/demultiplexer  1120  to the higher layer service applications. 
         [0102]    The controller  1110  interprets a scheduling command, e.g., an uplink grant, received by means of the transceiver  1105 , and controls the transceiver  1105  and the multiplexer/demultiplexer  1120  to perform an uplink transmission at a timing and with resources indicated by the scheduling command. 
         [0103]    Particularly in an exemplary embodiment of the present invention, the controller  1110  controls overall processes for determining a maximum transmit power (P CMAX ) of the UE and a power headroom of the UE based on the maximum transmit power, and transmitting the scheduling information containing the maximum transmit power and power headroom to the eNB. Here, the maximum transmit power is determined separately from the transmit power of the uplink transmission of the UE. 
         [0104]    According to the first exemplary embodiment of the present invention, the controller  1110  controls such that the maximum transmit power is reported to the eNB using 2 bits of the power headroom MAC CE message. 
         [0105]    According to the second exemplary embodiment of the present invention, the controller  1110  controls such that the maximum transmit power is transmitted to the eNB in the maximum transmit power report message only when a predetermined condition is fulfilled. In this case, the maximum transmit power report message is delivered to the multiplexer/demultiplexer  1120 . 
         [0106]    According to the third exemplary embodiment of the present invention, maximum transmit powers corresponding to the UE&#39;s conditions are stored and managed by the eNB in the form of a database, and the controller  1110  controls such that a maximum transmit power is transmitted to the eNB in response to the maximum transmit power report request generated when a predetermined condition is fulfilled. 
         [0107]      FIG. 12  is a block diagram illustrating a configuration of an eNB according to an exemplary embodiment of the present invention. 
         [0108]    Referring to  FIG. 12 , an eNB includes a transceiver  1205 , a controller  1210 , a multiplexer/demultiplexer  1220 , a control message processor  1235 , higher layer processors  1225  and  1230 , and a scheduler  1215 . 
         [0109]    The transceiver  1205  is responsible for transmitting data and control signals on a downlink carrier and for receiving data and controls signal on an uplink carrier. In a case where multiple carriers are aggregated, the transceiver  1205  can transmit/receive data and control signals on multiple carriers. 
         [0110]    The multiplexer/demultiplexer  1220  is responsible for multiplexing the data generated by the higher layer processors  1225  and  1230  and the control message processor  1235  and demultiplexing the data received by the transceiver  1205  and delivers the demultiplexed data to the higher layer processors  1225  and  1230 , the control message processor  1235 , and/or the controller  1210 . 
         [0111]    The control message processor  1235  is responsible for processing control messages received from the UE to execute necessary operations and for generating a control message to be transmitted to the UE, and delivers the control message to the higher layer. For example, the control message processor  1235  delivers P PowerClass  information transmitted by the UE to the controller  1210 . 
         [0112]    The higher layer processors  1225  and  1230  can be differentiated according to services, and process and deliver data generated in association with user services such as FTP and VoIP to the multiplexer/demultiplexer  1220 , or process and deliver data processed by the multiplexer/demultiplexer  1220  to the higher layer service applications. 
         [0113]    The controller  1210  processes a MAC CE received from the UE and delivers scheduling-related information to the scheduler  1215 . For example, the controller  1210  interprets a PHR received from the UE and notifies the scheduler  1215  of the power headroom. The controller  1210  can predict a value of P CMAX  which is selected by the UE according to the situation based on the power headroom and P CMAX  reported by means of the PHR, i.e., the controller  1210  manages P CMAX  values appropriate for different situations in the form of a database. The controller  1210  also notifies the scheduler  1215  of a maximum transmission resource amount and coding rate available for the UE at a certain time point. The controller  1210  controls the multiplexer/demultiplexer  1220  to generate downlink data based on scheduling information provided by the scheduler  1215  to the transceiver  1205 . The controller  1210  also generates the MAC CE requesting the UE for the P CMAX  report to the multiplexer/demultiplexer  1220 . 
         [0114]    The scheduler  1215  allocates transmission resources to the UE in consideration of a buffer state, a channel state, and a power headroom state, and controls the transceiver to process a signal received from the UE and to transmit a signal to the UE. 
       Fourth Exemplary Embodiment 
       [0115]    In a fourth embodiment of the present invention, a method and apparatus for reporting P CMAX  in a system using carrier aggregation are provided. The carrier aggregation is a technique in which multiple carriers are aggregated to increase a transmission bandwidth for the UE and is defined in the 3rd Generation Partnership Project (3GPP) REL-10 standard. The UE supporting carrier aggregation includes a Primary cell (PCell) and a Secondary Cell (SCell). Here, a cell is a set of carriers and can include downlink carriers or downlink and uplink carriers. In a case where the UE is configured to operate with multiple carriers (or multiple cells), each cell is activated and deactivated alternately under the control of the eNB in order to minimize battery power consumption. The UE receives downlink data and transmits uplink data in the activated cell according to the scheduling of the eNB. The PCell is always activated, while the SCell is activated and deactivated alternately under the control of the eNB. 
         [0116]    According to the fourth exemplary embodiment of the present invention, if PHR is triggered while carrier aggregation is deactivated, the UE reports only the PH, i.e., the difference between P CMAX  and PUSCH power. Otherwise, if PHR is triggered while carrier aggregation is activated, the UE reports the PH and P CMAX . This is because when carrier aggregation is activated the uplink data can be transmitted through multiple channel and multiple carriers simultaneously, and thus the probability of a transmit power shortage caused by the uncertainty of the P CMAX  increases as compared to a single carrier transmission. 
         [0117]      FIG. 13  is a signaling diagram illustrating operations of a UE and an eNB for a method according to a fourth exemplary embodiment of the present invention. 
         [0118]    Referring to  FIG. 13 , the eNB  1310  configures PHR in a state connected to the UE  1305  at a certain time point at step  1315 . The PHR is significant information for uplink scheduling of the eNB  1310  such that, when the UE  1305  transitions to the connected state, the eNB  1310  configures the PHR of the UE  1305 . At this time, since the UE  1305  transitioning from the idle state to the connected state cannot operate on multiple carriers, the PHR is configured according to the related art at that time point. 
         [0119]    In a PHR configuration function of the related art, the UE  1305  triggers PHR when a certain condition is fulfilled. The condition can be the receipt of a first uplink grant after PHR configuration, or a variation of path-loss greater than a predetermined value at a time point when an uplink transmit resource is available. 
         [0120]    If PHR is triggered, the UE  1305  calculates a required PUSCH power using an allocated uplink transmission resource, MCS, path-loss, and accumulated transmit power control command value at step  1320 . The UE  1305  also selects a P CMAX  value that can meet the spurious emission requirement between P CMAX   _   H  and P CMAX   _   L . The UE  1305  also determines PH by calculating a difference between the selected P CMAX  and the required PUSCH transmission power. 
         [0121]    Next, the UE  1305  reports the PH to the eNB  1310  using a PHR MAC CE of the related art at step  1325 . 
         [0122]    At a certain time afterward, the eNB  1310  sends the UE  1305  a control message to configure carrier aggregation at step  1330 . That is, the eNB  1310  configures at least one SCell cell to the UE  1305 . For example, when the traffic of the UE  1305  increases, the eNB  1310  can activate carrier aggregation. In this case, while configuring the carrier aggregation for the UE  1305 , the eNB  1310  can configure a new PHR function with the same control message or a separate control message. 
         [0123]    If the PHR is triggered, the UE  1305  reports the PH for all of the activated uplink carriers (hereinafter, uplink carrier is used synonymously with SCell) and P CMAX  for the all or some of the activated uplink carriers to the eNB  1310 . For example, in a case where the uplink carriers have the same P CMAX , the P CMAX  of one of the uplink carriers is reported. 
         [0124]    The control message for configuring the carrier aggregation can contain the following information as well as information on the newly configured carriers.
       Information for indicating whether to use the new PHR function   Information for indicating whether to transmit the PUSCH and Physical Uplink Control Channel (PUCCH) in parallel.       
 
         [0127]    If the first information indicates no use of the new PHR function, the UE  1305  deactivates the PHR function. In other words, the new PHR function can be used or not by the UE  1305 , but the PHR function of the related art is no longer used. 
         [0128]    The second information instructs the UE  1305  whether to transmit PUSCH and PUCCH in parallel in the PCell or not. PUCCH is a control channel for transmitting Hybrid Automatic Repeat Request (HARQ) feedback and downlink Channel Quality Indicator (CQI) and is used only in the PCell. The eNB  1310  instructs the UE  1305  to configure to transmit both the PUSCH and PUCCH in parallel, or one of PUSCH and PUCCH in consideration of the channel condition or capability of the UE  1305 . 
         [0129]    In a case where the PUSCH and PUCCH are not transmitted in parallel, the PUSCH is piggybacked on the PUSCH, resulting in a performance degradation of the PUSCH transmission. Accordingly, it is preferred that the PUSCH and PUCCH are configured to be transmitted in parallel as much as the UE&#39;s condition allows. If the PUSCH and PUCCH are configured to be transmitted in parallel and if PHR is triggered, the UE  1305  reports a type 2 PH and a P CMAX  used for type 2 PH calculation to the eNB  1310 . The type 2 PH is the value defined by Equation (5): 
         [0000]      Type 2 PH= P   CMAX  of  P Cell−PUSCH power−PUCCH power  Equation (5)
 
         [0130]    In a case where the UE  1305  transmits PUCCH and PUSCH in parallel in the PCell, the type 2 PH is used for providing the eNB  1310  with information on the transmit power condition for a simultaneous transmission of PUCCH and PUSCH. 
         [0131]    If PHR is triggered, the UE  1305  determines P CMAX  for the activated cells at a corresponding time point and calculates a transmit power of PUSCH at step  1335 . The UE  1305  determine a PH per cell based on the above information. The UE  1305  generates a PHR MAC CE containing the calculated PH value and P CMAX  per cell and transmits the PHR MAC CE to the eNB  1310  at step  1340 . In a case where the PUSCH and PUCCH are configured to be transmitted in parallel, the UE  1305  calculates type 2 PH using the P CMAX  and PUSCH transmit power of the PCell and PUCCH transmit power, and transmits the PHR MAC CE containing the type 2 PH and P CMAX  used for calculating the type 2 PH to the eNB  1310 . 
         [0132]      FIG. 14  is a flowchart illustrating a procedure of a UE in a method according to the fourth exemplary embodiment of the present invention. 
         [0133]    Referring to  FIG. 14 , a PHR transmission-necessary situation occurs at step  1405 . This is the state wherein there is a PHR which is not canceled yet although a new uplink transmission resource becomes available for the UE configured with a PHR function of the related art or the new PHR function. The UE determines whether the configured PHR function is the new PHR function or the PHR function of the related art at step  1410 . 
         [0134]    Here, the PHR function of the related art is a PHR function performed regardless of a carrier aggregation operation such that, when a PHR is triggered, the UE calculates and reports a PH to the eNB. Meanwhile, the new PHR function is a PHR function associated with the carrier aggregation operation such that, when the PHR is triggered, the UE calculates PHs of all the uplink carriers (or cells to which uplink transmission resources are configured) and reports the PHs and P CMAX  used for PH calculation. 
         [0135]    As described above, when the carrier aggregation operation is configured in the UE, the UE receives a command instructing whether to activate the new PHR function. If the current PHR function is the PHR function of the related art, the UE calculates the PH at step  1415 , inserts the PH into the PHR at step  1420 , and transmits the PHR to the eNB at step  1455 . 
         [0136]    If the current PHR function is the new PHR function, the procedure goes to step  1425 . At step  1425 , the UE calculates PHs of all the uplink carriers activated at a corresponding time point (or cells to which uplink transmission resources are configured). Next, the UE inserts the calculated PHs into the PHR at step  1430 . Next, the UE inserts P CMAX  used for calculating the PHs into the PHR along with the PHs at step  1435 . 
         [0137]    Next, the UE determines whether parallel PUCCH and PUSCH transmission is configured at step  1440 . If parallel PUCCH and PUSCH is configured, the procedure goes to step  1445 . Otherwise, if parallel PUCCH and PUSCH is not configured, the UE transmits the PHR to the eNB at step  1455 . 
         [0138]    At step  1445 , the UE calculates a type 2 PH by subtracting the PUSCH transmit power and required PUCCH transmit power from P CMAX  of the PCell. The calculated type 2 PH is inserted into the PHR. Next, the UE inserts the P CMAX  of the PCell used for calculating the type 2 PH into the PHR at step  1450  and transmits the PHR to the eNB at step  1455 . 
         [0139]    A description is made of another procedure for determining whether the P CMAX  is included in the PHR using other criteria according to another exemplary embodiment of the present invention. 
         [0140]      FIG. 15  is a flowchart illustrating a procedure of a UE in a method according to a modified case of the fourth exemplary embodiment of the present invention. 
         [0141]    Referring to  FIG. 15 , if a PHR transmission-necessary situation occurs at step  1505 , the UE calculates PHs of all the uplink carriers activated at the corresponding time point at step  1510 . Next, the UE inserts the calculated PHs into a PHR at step  1515 . 
         [0142]    Next, the UE checks whether parallel PUCCH and PUSCH transmission is configured at step  1520  and, if so, determines that the P CMAX  report necessity is very high and therefore the UE inserts P CMAX  into the PHR at step  1530 . 
         [0143]    Otherwise, if parallel PUCCH and PUSCH transmission is not configured, the UE determines whether a number of PHs included in the PHR is 1 or more at step  1525 . If the number of PHs included in the PHR is 1, this means that one uplink subcarrier is activated at the corresponding time point and the P CMAX  report necessity is low as compare to the multicarrier situation, and, as a consequence, the UE does not insert the P CMAX  into the PHR at step  1535 . Next, the UE transmits the PHR to the eNB at step  1540 . If parallel PUSCH and PUCCH transmission is configured, at least two PHs are included in the PHR, and thus step  1520  can be omitted. That is, if the PHR includes 1 PH, the UE does not insert the P CMAX  in the PHR and, otherwise if the PHR includes more than 1 PH, inserts the P CMAX  in the PHR. 
         [0144]    Since the configuration of the eNB according to the fourth exemplary embodiment is identical with those of the previous exemplary embodiments, a detailed description thereof is omitted herein. 
         [0145]    Since the UE according to the fourth exemplary embodiment of the present invention is identical with that of the previous exemplary embodiments except for the operations of the controller, only the operations of the controller are described herein. 
         [0146]    When PHR is triggered, the controller  1110  determines whether to insert the P CMAX  into the PHR in consideration of the UE&#39;s situation. That is, if the new PHR function is configured, the P CMAX  is included in the PHR, but if the PHR function of the related art is configured, the P CMAX  is excluded from the PHR. If only one PH is included in the PHR, the P CMAX  is excluded from the PHR, and otherwise, if more than one PH is included in the PHR, the P CMAX  is included in the PHR. 
         [0147]    As described above, exemplary embodiments of the present invention enables an eNB to interpret a PHR of a UE accurately, resulting in improvement of scheduling efficiency and mitigation of interference to other transmissions. 
         [0148]    While the invention has been shown and described with reference to certain exemplary embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims and their equivalents.