Abstract:
The present invention relates to a method and apparatus for setting the transmission power of a terminal in a wireless communication system. Particularly, the initial transmission power by means of which the terminal transmits a signal via an uplink non-anchor carrier is determined by reflecting the transmission power by means of which the terminal has most recently transmitted a signal via an uplink anchor carrier and by reflecting the difference between channel environments of the uplink anchor carrier and the uplink non-anchor carrier, in a wireless communication system using a broadband formed by carrier aggregation. Consequently, the initial transmission power of the terminal is set as accurately as possible in the uplink non-anchor carrier, thereby preventing signal transmission delay and improving the reliability of received signals.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates to a cellular radio communication system and, in particular, to a method and apparatus for configuring initial transmission power of uplink non-anchor carrier of a terminal in a system supporting carrier aggregation. 
         [0003]    2. Description of the Related Art 
         [0004]    Recently, many researches are being conducted on the Orthogonal Frequency Division Multiple Access (OFDMA) and Single Carrier Frequency Division Multiple Access (SC-FDMA) as useful schemes for high speed data transmission over a radio channel. In such multiple access schemes, the user-specific data and/or control information are mapped to time-frequency resources without overlapped from each other, i.e. maintaining orthogonality, to identify the user-specific data and/or control information. 
         [0005]    In a cellular communication system, one of the significant factors to provide high-speed wireless data service is bandwidth scalability for dynamic resource allocation. For example, Long Term Evolution (LTE) system can support the bandwidths of 20/15/10/5/3/1.4 MHz. 
         [0006]    The carriers can provide services with at least one of the bandwidths, and the user equipments can have different capabilities such that some supports only 1.4 MHz bandwidth and others up to 20 MHz bandwidth. The LTE-Advanced (LTE-A) system, aiming at achieving the requirements of the IMT-Advanced service, can provide broadband service by aggregating carries up to 100 MHz. 
         [0007]    The LTE-A system needs the bandwidth wider than that of LTE system for high-speed data transmission. Simultaneously, the LTE-A system needs to be backward compatible with the LTE system such that the LTE UEs can access the services of the LTE-Advanced system. For this purpose, the entire system bandwidth of the LTE-A system is divided into sub-bands or component carriers that have a bandwidth supporting transmission or reception of the LTE UE and can be aggregated for supporting the high speed data transmission of the LTE-A system in the transmission/reception process of the legacy LTE system per component carrier. 
         [0008]      FIG. 1  is a diagram illustrating an example of carrier aggregation according to a convention technology. 
         [0009]      FIG. 1  shows an example for configuring an LTE-A system with component carriers  113 ,  115 ,  117 ,  123 ,  125 , and  127  that are aggregated by  3  for uplink (UL)  110  and downlink (DL)  120 . One of the aggregated component carriers is referred to as anchor carrier or anchor component carrier or primary carrier. The other carriers that are not anchor carrier are referred to as non-anchor carrier or non-anchor component carrier or non-primary carrier. 
         [0010]    In uplink  110 , the component carrier on which the UE performs random access after initial system attachment can be the uplink anchor carrier. In downlink  120 , the component carrier configured as the anchor carrier can be used for transmitting initial system information and uplink signaling, and the anchor carrier can be a reference component carrier for controlling UE mobility. 
         [0011]      FIG. 1  shows an example where the uplink component carrier # 0  (uplink CC # 0 )  113  and the downlink component carrier # 0  (downlink CC# 0 )  123  are configured as anchor carriers in uplink  110  and downlink  120  respectively. Although  FIG. 1  is directed to the case where uplink component carriers and downlink component carriers are symmetrical and equal to each other in numbers, it is possible to aggregate the uplink/downlink carriers in asymmetrical manner. 
         [0012]    When a UE attempts initial attachment to an LTE system, the UE acquires downlink timing and frequency region synchronization through cell search and then cell ID. Afterward, the UE receives system information from the eNB to acquire basic parameter values related to transmission/reception such as system bandwidth. Next, the UE performs random access to transition to the connected state on the link with the eNB. A description is made of the random access procedure with reference to  FIG. 2  hereinafter. 
         [0013]      FIG. 2  is a signaling diagram illustrating the random access procedure of the UE according to a conventional technology. 
         [0014]    Referring to  FIG. 2 , the UE performs random access to the eNB by transmitting a random access preamble at step  201  such that the eNB measures transmission delay between the UE and eNB and acquires uplink synchronization. At this time, the initial transmission power of the random access preamble is determined based on the pathloss between the UE and eNB which is measured by the UE. 
         [0015]    The eNB transmits a Random Access Response at step  202 . The random access response includes a timing adjustment command and scheduling grant. In more detail, the eNB checks the transmission delay measured at step  201  and transmits the timing adjustment command to the UE. The eNB also transmit the uplink resource information and power control command as scheduling grant. 
         [0016]    At step  203 , the UE transmits a Radio Resource Control (RRC) signal to the eNB on the uplink resource allocated at step  202 . Here, the RRC signal includes uplink data having UE ID. At this time, the transmission timing and transmission power are changed according to the timing adjustment command and scheduling grant received at step  202  from the eNB. 
         [0017]    At step  204 , if it is determined that the UE has performed the random access without collision with other UEs, the eNB transmits an RRC signal including UE ID which has been received at step  203 . If the RRC signal transmitted by the eNB is received, the UE determines that the random access has been completed successfully. 
         [0018]    If it fails to receive the random access signal from the UE due to the collision with the random access signal of another UE, the eNB does not transmit data any more. If there is no data from the eNB (corresponding to step  204 ) for a predetermined duration, it is determined that the radon access has failed. In this case, the UE repeats the procedure from step  201 . If the random access is successful, the UE configures the initial transmission power of the uplink data channel or control channel by referencing the UE transmission power controlled through the random access process. 
         [0019]    In the LTE-A system supporting carrier aggregation, however, if the UE attempts initial transmission of uplink signal on an uplink non-anchor carrier after performing the above random access process on the uplink anchor carrier, there is a need of a solution for how to configure the UE&#39;s initial transmission power. That is, there is a need of a method for configuring transmission power of data or control channel for the UE which has performed the random access only on the uplink anchor carrier but not on the uplink non-anchor carriers. 
       SUMMARY OF THE INVENTION 
     Problem to be Solved 
       [0020]    In order to solve the above problems, the present invention provides a method and apparatus for configuring initial transmission power of uplink transmission channel of the UE in a wireless communication system supporting broadband transmission through carrier aggregation. 
       Means for Solving the Problem 
       [0021]    In order to achieve the above object, the initial transmission power configuration method according to an embodiment of the present invention includes configuring, when a random access process is completed on the anchor carrier, initial transmission power of the non-anchor carrier using most recent transmission power of the anchor carrier and transmitting data at the initial transmission power of the non-anchor carrier. 
         [0022]    In order to achieve the above object, the initial transmission power configuration apparatus according to an embodiment of the present invention includes a receiver which receives a scheduling grant transmitted by a base station; a carrier aggregation controller which determines a component carrier for transmitting data based on the scheduling grant; a power control controller which configures, when the component carrier is a non-anchor carrier, initial transmission power of the non-anchor carrier using most recent transmission power of an anchor carrier; and a transmitter which transmits the data at the configured initial transmission power on the non-anchor carrier. 
       Advantageous effects 
       [0023]    The present invention configures the initial transmission power of the UE on the uplink non-anchor carrier accurately so as to avoid transmission delay and radio resource waste caused by the so lowly configured transmission power and mitigate interference caused by so highly configured transmission power. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0024]      FIG. 1  is a diagram illustrating an example of carrier aggregation according to a convention technology. 
           [0025]      FIG. 2  is a signaling diagram illustrating the random access procedure of the UE according to a conventional technology. 
           [0026]      FIG. 3  is a flowchart illustrating a UE procedure for transmitting initial signal on the non-anchor carrier according to the present invention. 
           [0027]      FIG. 4  is a diagram illustrating a method for the UE to determine transmission power of the signal transmitted initially on the non-anchor carrier according to the present invention. 
           [0028]      FIG. 5  is a flowchart illustrating a UE procedure for receiving initial signal on the non-anchor carrier according to the present invention. 
           [0029]      FIG. 6  is diagram illustrating a UE apparatus according to the first embodiment. 
           [0030]      FIG. 7  is a diagram illustrating an eNB apparatus according to the first embodiment. 
           [0031]      FIG. 8  is a diagram illustrating a UE apparatus according to the second embodiment. 
           [0032]      FIG. 9  is a diagram illustrating a UE apparatus according to the third embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS 
       [0033]    Exemplary embodiments of the present invention are described with reference to the accompanying drawings in detail. Detailed description of well-known functions and structures incorporated herein may be omitted to avoid obscuring the subject matter of the present invention. In addition, terms used in the following description of the present invention are prepared in view of functions thereof, so they will be changed depending on the intention of users, operators, or custom. Thus, definition of the terms must be determined based on the whole content of the specification. 
         [0034]    Although the description is directed to the Advanced E-UTRA (or LTE-A) supporting carrier aggregation in the following embodiments of the present invention, it will be understood by those skilled in the art that the present invention can be applied to other communication systems supporting the similar technical background and channel format with a slight modification without departing from the spirit and scope of the invention. For example, the subject matter of the present invention can be applied to multicarrier HSPA supporting carrier aggregation. 
         [0035]    The subject matter of the present invention is to provide a method and apparatus for configuring initial transmission power of uplink transmission channels of a UE in a radio communication system supporting broadband service with carrier aggregation. Particularly, according to the present invention, the UE can configure the initial transmission power of the data or control channel by reflecting the current channel state as far as possible on the uplink non-carrier carrier for which no random access is performed. For this, the UE determines the initial transmission power of the non-anchor carrier by reflecting the transmission power of the signal transmitted by the UE most recently on the uplink anchor carrier and difference between channel environments of the uplink anchor and non-anchor carriers. 
         [0036]    In the present invention, the uplink anchor carrier means at least one uplink component carrier on which the UE has performed random access for initial attachment among the aggregated uplink component carriers. The uplink non-anchor carrier means the other aggregated uplink component carriers with the exception of the uplink anchor carrier. 
         [0037]    A description is made of the data or control channel transmission procedure of the UE on a uplink non-anchor carrier with reference to  FIG. 3 .  FIG. 3  is a flowchart illustrating a UE procedure for transmitting initial signal on the non-anchor carrier according to the present invention. 
         [0038]    Referring to  FIG. 3 , the UE first performs cell search and acquires system information at step  301 . That is, the UE acquires downlink timing and frequency synchronization through cell search and obtains cell ID. The UE receives system information from the eNB to acquire basic parameter values related to transmission/reception such as system bandwidth. 
         [0039]    Afterward, the UE performs random access at step  303 . That is, the UE establishes a link with the eNB through the random access on the anchor carrier to transition to a connected state. In the connected state, the eNB can the UE with unique UE parameters. The UE acquires the parameter information from the eNB and uses the parameters in transmission/reception procedure. In the random access process, the UE adjusts the transmission power to an appropriate value according to the power control of the eNB. 
         [0040]    Afterward, the UE acquires scheduling grant for uplink anchor carrier (or primary UL CC) from the eNB at step  305 . The UE prepares uplink data transmission on the anchor carrier with the scheduling grant. Next, the UE transmits uplink data on the anchor carrier according to the scheduling grant at step  307 . At this time, the transmission power of the uplink data which is transmitted initially by the UE is calculated based on the power level controlled in the random access process of step  303 . As the data or control information transmission/reception is repeated, the UE adjusts the transmission power of the uplink anchor carrier to an appropriate value based on the uplink power control command transmitted by the eNB. 
         [0041]    The eNB determines the uplink power control based on the channel environment between UE and eNB on the anchor carrier and scheduling grant for the UE as follows.
       channel environment: Pathloss, interference amount   scheduling grant: MCS (modulation and coding scheme), scheduled resource amount       
 
         [0044]    If it is determined that the UE supports carrier aggregation, the eNB transmits the detailed configuration information on the component carriers to the UE. The UE acquires the control information per component carrier (i.e., control information of multiple CCs) from the signaled information at step  309 . The control information per component carrier includes number of component carriers, frequencies of the component carriers, interference amount per component carrier, and transmission power of Reference Signal (RS) per component carrier which is used for the UE to measure pathloss. If the UE transitions to the connected state, the eNB can check whether the UE supports carrier aggregation based on the signaling information of UE capability. Accordingly, step  309  can be performed at a certain time point after the UE has completed the random access process at step  303 . 
         [0045]    Afterward, the eNB requests the UE to transmit Sounding Reference Signal (SRS) and channel state measurement report necessary for scheduling the UE on non-anchor carriers. The UE transmits the SRS or channel state measurement report on the non-anchor carrier at step  311 . At this time, the UE transmits to the eNB the SRS to the eNB or transmits the channel state measurement report on data channel through higher layer signaling or control channel through physical layer signaling. 
         [0046]    The data channel or control channel for SRS or channel state measurement report is the signal for the UE to transmit signals first on the non-anchor carrier such that no reference for configuring initial transmission power level. Accordingly, the UE calculates the initial transmission power of the non-anchor carrier using the most recent transmission power of the anchor carrier. In case of anchor carrier, the transmission power level is in stable state through the power control in the random access and data channel/control channel transmission/reception process such that the UE transmission power on the anchor carrier can be referenced to configure the UE&#39;s initial transmission power level on the non-anchor carrier. In the present invention, once the random access process has completed, the initial transmission power of the non-anchor carrier is configured based on the most recent transmission power of the anchor carrier. Since the pathloss, interference amount, and scheduling grant may vary depending on the carrier, it is necessary to compensate for these additionally. The UE can compensate the initial transmission power of the non-anchor carrier using equation 1. 
         [0000]      P( k )=P(0)+P_offset(1)+P_offset(2)   Equation 1
 
         [0047]    Here, P(k) denotes initial transmission power level of UE&#39;s non-anchor carrier, P( 0 ) denotes the most recent transmission power level of UE&#39;s anchor carrier, P_offset( 1 ) denotes channel environment offset, and P_offset( 2 ) denotes scheduling information offset. 
         [0048]    The channel environment offset includes pathloss difference and interference difference between the anchor carrier and non-anchor carrier. The scheduling information offset includes MCS difference and scheduled resource amount difference between the anchor and non-anchor carriers. The recent transmission power level of the anchor carrier and the calculated initial transmission power level of the non-anchor carrier are described with reference to  FIG. 4 . 
         [0049]      FIG. 4  is a diagram illustrating a method for the UE to determine transmission power of the signal transmitted initially on the non-anchor carrier according to the present invention. 
         [0050]    Referring to  FIG. 4 , it is shown that the most recent transmission power level of the UE for the anchor carrier P( 0 )  410  has a difference as much as the sum of the channel environment offset P_offset( 1 )  423  and the scheduling information offset P_offset( 2 ) as compared to the initial transmission power of the UE for non-anchor carrier P(k)  420 . 
         [0051]    The UE performs initial transmission on the non-anchor carrier at the transmission power calculated according to equation 1. Next, the UE performs power control process according to the power control command from the eNB based on the transmission power level used for initial transmission on the non-anchor carrier. 
         [0052]    Returning to  FIG. 3 , the eNB performs scheduling the UE on the data or control channel for SRS or channel state measurement report of the UE. Next, the UE acquires the scheduling grant from the eNB at step  313 . Next, the UE transmits data on the non-anchor carrier according to the acquired scheduling information. 
         [0053]    A description is made of the eNB procedure for data transmission on the non-anchor carrier with reference to  FIG. 5 .  FIG. 5  is a flowchart illustrating a UE procedure for receiving initial signal on the non-anchor carrier according to the present invention. 
         [0054]    Referring to  FIG. 5 , the eNB first performs the random access process triggered by a UE at step  501 . Once the random access process has completed, the link between the eNB and the UE transitions from idle state to connected state. In connected state, the eNB can configures the UE with unique parameters necessary for transmission/reception of the UE. In the random process, the eNB adjusts the transmission power of the UE to an appropriate value through power control. 
         [0055]    The eNB transmits a scheduling grant for uplink anchor carrier (or primary UL CC) to the UE at step  503 . Next, the eNB receives the uplink data which the UE transmits on the anchor carrier according to the scheduling grant at step  505 . As the data or control information transmission/reception continues, the eNB adjusts the uplink transmission power of the UE to an appropriate value with uplink power control. 
         [0056]    If it is determined that the UE supports a plurality of component carriers, the eNB signals detailed configuration information on the individual component carriers to the UE at step  507 . At this time, the eNB requests the UE to transmit SRS (sounding reference signal) or channel state measurement report for scheduling the UE. Step  507  can be performed at a certain time point after the UE completes the random access procedure at step  501 . 
         [0057]    Next, the eNB receives the SRS/channel state measurement report transmitted by the UE at step  509 . The eNB generates scheduling grant for the UE on the non-anchor carrier based on the information acquired at step  509  and transmits the scheduling grant to the UE at step  511 . Next, the eNB receives the data which the UE transmits on the non-anchor carrier at step  513 . 
         [0058]    The present invention can be applied to a plurality component carriers aggregated for broadband without restriction. 
         [0059]    A description is made of the initial transmission power configuration of uplink transmission channel of the UE on the non-anchor carrier. 
       First Embodiment 
       [0060]    The first embodiment describes a method for configuring initial transmission power of Physical Uplink Shared Channel (PUSCH) when the signal which the UE transmits first on the non-anchor carrier is PUSCH in the LTE-A system. The signal transmitted on the PUSCH can be data or higher layer signaling information. 
         [0061]    The PUSCH transmission power in i th  frame on k th  component carrier is determined by equation 2. 
         [0000]      P PUSCH ( i, k )=min{P CMAX , 10 log 10 ( M   PUSCH ( i,k ))+P O     —     PUSCH ( j,k )+αα( j,k )· PL ( k )+Δ TF ( i,k )+ f ( i,k )}  Equation 2
       P CMAX : maximum allowed UE transmission power which is determined depending on the UE class and higher layer signaling configuration.   M PUSCH (i,k): a number of Physical Resource Blocks (PRB) as resource amount scheduled by the eNB in i th  subframe on k th  component carrier.   P O     —     PUSCH (j,k): interference amount which is measured by the eNB on the k th  component carrier and signaled to the UE, where index j is set to a value according to the type of data to be scheduled, i.e. j=1 for the semi-persistent scheduling data for which the scheduling grant is valid for a predetermined duration, j=2 for the dynamic scheduling data, and j=3 for the uplink data in the random access process.   α(j,k): value for partially compensating pathloss between eNB and UE on k th  component carrier. 0≦α(j,k)≦1   PL(k): pathloss between eNB and UE on k th  component carrier, the UE calculates pathloss based on the difference between the transmission power of the RS signaled by the eNB and received signal level of the RS.   Δ TF (i,k): power offset according to the transport format (TF) of the data scheduled by the eNB in i th  subframe on k th  component carrier.   f(i,k): calculated based on the power control command included in the eNB scheduling information in i th  subframe on k th  component carrier.       
 
         [0069]    That is, equation 2 shows that the transmission power of the UE is determined based on the channel environment compensation parameter (P O     —     PUSCH (j,k), α(j,k), PL(k)), α(j,k), (M PUSCH (i,k), Δ TF (i,k)) according to PL(k) and scheduling information, and additional compensation f(i,k). The parameter for compensating the channel environment is configured in semi-static manner and signaled to the UE. The parameter according to scheduling information and the additional compensation are relatively dynamic variables calculated from the eNB scheduling information in i th  subframe. 
         [0070]    If the uplink anchor carrier index of k=0, the initial PUSCH transmission power on the uplink anchor carrier (k≠0) is obtained by applying the initial value of f(i,k) defined as equation 3 to equation 2. 
         [0000]        f ( i,k )=P PUSCH ( i,  0)−10 log 10 ( M   PUSCH ( i, 0))−P O     —     PUSCH ( j, 0)−α( j, 0)· PL (0)−Δ TF ( i, 0)   Equation 3
 
         [0071]    In equation 3, P PUSCH (i, 0) denotes PUSCH transmission power of the UE in i th  subframe on the anchor carrier and, if there is no PUSCH transmitted in the i th  subframe on the anchor carrier, the transmission power of PUSCH transmitted most recently on the anchor carrier is referenced. 
         [0072]    The initial value of f(i,k) on the non-anchor carrier expressed by equation 3 is the initially applied value which is calculated with the power control command from the eNB after PUSCH is transmitted once when the signal transmitted by the UE first on the non-anchor carrier is PUSCH. 
         [0073]    Equation 4 is of the value calculated by applying equation 3 to equation 2 as the initial PUSCH transmission power when the first signal transmitted by the UE on the non-anchor carrier is PUSCH. 
         [0000]        P   PUSCH ( i, k )=min{ P   CMAX   , P   PUSCH ( i,  0   )+10 log 10 ( M   PUSCH ( i,k )/ M   PUSCH ( i, 0))+ P   O     —     PUSCH ( j,k )− P   O     —     PUSCH ( j, 0)+α( j,k )· PL ( k )−α( j, 0)· PL (0)+Δ TF ( i,k )−Δ TF ( i, 0)}  Equation 4
 
         [0074]    As a result, equation 4 shows that the UE&#39;s initial transmission power on the non-anchor carrier is calculated with the UE&#39;s most recent transmission power level on the anchor carrier, channel environment difference between anchor and non-anchor carriers, and scheduling information difference between the anchor and non-anchor carriers, as described with reference to equation 1. 
         [0075]    As a modification from the first embodiment, it can be considered to perform random access process on the non-anchor carrier when the UE is transmitting a signal on the non-anchor carrier first. That is, the transmission power of the UE is adjusted to a certain level appropriate for the channel environment through power control in random access on the non-anchor carrier. The adjusted transmission power can be used as reference power level for signals to be transmitted after the random access process. If the initial transmission power of uplink signal in the UE&#39;s random access on the non-anchor carrier is determined by equation 1, it is possible to perform relatively accurate power control. 
         [0076]      FIG. 6  is diagram illustrating a UE apparatus according to the first embodiment.  FIG. 6  shows an exemplary UE apparatus operating with two aggregated component carriers in uplink. 
         [0077]    For uplink transmission, the transmitter of the UE includes a data buffer  600  for buffering data, channel coders  602  and  604  for providing error correction capability to the data transmitted on the respective component carriers, modulation mappers  606  and  608  generating modulation symbols, Discrete Fourier Transform (DFT) units  610  and  612  for performing Discrete Fourier Transform, and Resource Element (RE) mappers  614  and  616  for mapping the DFT outputs to REs. The signals output from the RE mappers  614  and  616  for the respective component carriers are transmitted through Inverse Fast Fourier Transform (IFFT) unit  618  and Intermediate Frequency (IF)/Radio Frequency (RF) processor  620 . Although the IFFT unit  618  and IF/RF unit  620  are depicted common functional blocks in  FIG. 6 , they can be implemented as individual function blocks responsible for respective component carriers. 
         [0078]    The transmitter of the UE includes an RF/IF unit  622  for processing received RF/IF signals, FFT unit  624  for performing FFT, RE demappers  626  and  628  for demapping REs, demodulators  630  and  632 , and channel decoders  634  and  636 . The RF/IF unit  622  and FFT unit  624  can be implemented per component carrier. 
         [0079]    The carrier aggregation controller  640  determines the component carriers to perform data transmission in uplink based on the scheduling grant received from the eNB through the UE receiver. The carrier aggregation controller  640  controls the data buffer  600  to transfer the data to the uplink component carrier processor to be used according to the determination result. The carrier aggregation controller  640  controls the power control controller  650  to perform power control on the component carriers. 
         [0080]    The power control controller  650  performs power control on the corresponding component carrier based on the control command of the carrier aggregation controller  640  and the Transmit Power Control (TPC) command received through the UE receiver. Although the power control performed by the power control controller  650  is applied to the RE mappers  614  and  616  for the respective component carriers, it can be implemented to apply the power control to other function blocks such as modulators  606  and  608 . In case that the signal transmitted first on the non-anchor carrier of the UE is PUSCH, the power control controller  650  can perform the power control such that the initial transmission power of PUSCH is configured by equation 4. Once PUSCH has been transmitted on the non-anchor carrier, the power control controller  650  performs power control according to the power control command from the eNB. 
         [0081]      FIG. 7  is a diagram illustrating an eNB apparatus according to the first embodiment. The eNB includes an RF/IF unit  722  for processing the signal received from the UE, a Fast Fourier Transform (FFT) unit  724  for performing FFT, Resource Element (RE) demappers  726  and  728  for RE demapping on the respective component carriers, and data processors (Physical Uplink Shared Channel (PUSCH)/Physical Uplink Control Channel (PUCCH)/Sounding Reference Signal (SRS) processors)  730  and  732 . The RF/IF unit  722  and FFT unit  724  can be implemented per component carrier. The data processor  730  includes a decoder and demodulator for processing signal according to the type of the signal transmitted by the UE. 
         [0082]    The eNB scheduler  734  acquires channel state measurement report and uplink channel state information (CSI) from the receiver and determines the component carrier for scheduling the UE thereon and the transmission format and provides the determination result to the scheduling information generators  702  and  704  for the corresponding component carriers. The UE scheduler  734  provides the eNB power control controller  736  with information on the component carrier on which the UE is scheduled. 
         [0083]    The power control controller  736  receives Signal-to-Interference (SIR) measurement values of the received signals from the receiver to generate power control commands for the individual uplink component carriers and provides the power control commands to the scheduling grant generators  702  and  740  for the respective component carriers. The control signals generated by the scheduling grant generators  702  and  704  are processed by the channel coders  706  and  708 , the modulation mapper  710  and  712 , and the RE mappers  714  and  716 , transformed by the IFFT unit  718 , and then signal-processed by the IF/RF unit  720  to be transmitted to the UE. The RF/IF unit  720  and IFFT unit  718  can be implemented per component carrier. 
       Second Embodiment 
       [0084]    The second embodiment proposes a method for configuring initial transmission power of PUCCH when the signal transmitted first by the UE on the non-anchor carrier is Physical Uplink Control Channel (PUCCH) carrying control information in uplink. The signal carried in the PUCCH can be ACK/NACK for downlink data or Channel Quality Indicator (CQI) information indicating downlink channel state. 
         [0085]    The PUCCH transmission power in i th  subframe on k th  component carrier is determined by equation 5. 
         [0000]        P   PUCCH ( i, k )=min{ P   CMAX   , P   O     —     PUCCH ( k )+ PL ( k )+ h ( n   CQI   , n   HARQ   , k )+Δ F     —     PUCCH ( F,k )+ g ( i,k )   Equation 5
       PCMAX: maximum allowed UE transmission power which is determined depending on the UE class and higher layer signaling configuration.   P O     —     PUCCH (k): interference amount which is measured by the eNB on the k th  component carrier and signaled to the UE.   PL(k): pathloss between eNB and UE on k th  component carrier, the UE calculates pathloss based on the difference between the transmission power of the RS signaled by the eNB and received signal level of the RS.   h(n CQI , n HARQ , k): offset determined according to the CQI information amount when the control information of PUCCH to be transmitted by the UE on k th  component carrier is CQI.   Δ F     —     PUCCH (F,k): offset determined depending on whether the control information of PUCCH to be transmitted by the UE on the k th  component carrier is ACK/NACK or CQI.   g(i,k): calculated according to the power control command included in the eNB&#39;s scheduling information in i th  subframe on k th  component carrier.       
 
         [0092]    That is, equation 5 shows that the transmission power of the UE is determined based on the channel environment compensation parameter (P O     —     PUCCH (k), PL(k)), (h(n CQI , n HARQ , k),  F     —     PUCCH (F,k)) according to the type of control information to be transmitted by the UE based on the eNB&#39;s scheduling, and the additional compensation (g(i,k)). The parameter for compensating the channel environment is configured in semi-static manner and signaled to the UE. 
         [0093]    If the uplink anchor carrier index of k=0, the initial PUCCH transmission power on the uplink anchor carrier (k∫0) is obtained by applying the initial value of g(i,k) defined as equation 6 to equation 5. 
         [0000]        g ( i,k )= P   PUCCH ( i,  0)− P   O     —     PUCCH ( j, 0)− PL (0)− h (n CQI   , n   HARQ , 0)−Δ F     —     PUCCH ( F, 0)   Equation 6
 
         [0094]    In equation 6, P PUCCH (i,0) denotes PUCCH transmission power in i th  subframe on the anchor carrier and, if there is no PUCCH transmitted in the i th  subframe on the anchor carrier, the transmission power of PUCCH transmitted most recently on the anchor carrier is referenced. 
         [0095]    The initial value of g(i,k) on the non-anchor carrier expressed by equation 6 is the initially applied value which is calculated with the power control command from the eNB after PUCCH is transmitted once when the signal transmitted by the UE first on the non-anchor carrier is PUCCH. 
         [0096]    Equation 7 has the value calculated by applying equation 6 to equation 5 as the initial PUCCH transmission power when the first signal transmitted by the UE on the non-anchor carrier is PUCCH. 
         [0000]        P   PUCCH ( i, k )=min{ P   CMAX   , P   PUCCH ( i,  0)+ P   O     —     PUCCH ( j,k )− P   O     —     PUCCH ( j, 0)+ PL ( k )− PL (0)+ h ( n   CQI   , n   HARQ   , k )− h ( n   CQI   , n   HARQ , 0)+Δ F     —     PUCCH ( F,k )−Δ F     —     PUCCH ( F, 0)}  Equation 7
 
         [0097]    As a result, equation 7 shows that the UE&#39;s initial transmission power on the non-anchor carrier is calculated with the UE&#39;s most recent transmission power level on the anchor carrier, channel environment difference between anchor and non-anchor carriers, and scheduling information difference between the anchor and non-anchor carriers, as described with reference to equation 1. 
         [0098]      FIG. 8  is a diagram illustrating a UE apparatus according to the second embodiment.  FIG. 8  shows an exemplary UE apparatus operating with two aggregated component carriers in uplink. For uplink transmission, the transmitter of the UE includes UCI generators  802  and  804  for generating uplink control information (UCI) to be transmitted on the respective component carriers, PUCCH formatters  806  and  808  for performing channel coding and modulation in match with the PUCCH transmission format, and RE mappers  810  and  812  for mapping the signal to be transmitted to Resource Elements (RE). 
         [0099]    The signals output from the RE mappers  810  and  812  for the respective component carriers are processed by the IFFT unit  814  and then transmitted through the Intermediate Frequency (IF)/Radio Frequency (RF) processor  816 . Although the IFFT unit  814  and IF/RF unit  816  are depicted common functional blocks in  FIG. 8 , they can be implemented as individual function blocks responsible for respective component carriers. 
         [0100]    The receiver of the UE includes an RF/IF unit  818  for performing RF/IF processing on the received signal, a Fast Fourier Transform (FFT) unit  820 , and RE mappers  822  and  824 , modulation demappers  826  and  828 , and decoders  830  and  832  implemented for the respective component carriers. The RF/IF unit  818  and FFT  820  also can be implemented per component carrier. 
         [0101]    The carrier aggregation controller  834  receives the ACK/NACK for downlink data or CQI transmission request information from the UE receiver to determine the uplink component carrier for ACK/NACK or CQI transmission. The carrier aggregation controller  834  controls the UCI generators  802  and  804  to generate UCI to be transmitted on the determined uplink component carrier. The carrier aggregation controller  834  also controls the power control controller  836  to determine the component carrier to be power-controlled. 
         [0102]    The power control controller  836  performs power control on the corresponding component carrier based on the control command of the carrier aggregation controller  834  and the Transmit Power Control (TPC) command received through the UE receiver. Although the power control performed by the power control controller  834  is applied to the RE mappers  810  and  812  for the respective component carriers in  FIG. 8 , it can be implemented to apply the power control to other function blocks such as modulators in the PUCCH formatters  806  and  808 . In case that the signal transmitted first on the non-anchor carrier of the UE is PUCCH, the power control controller  836  can perform the power control such that the initial transmission power of PUCCH is configured by equation 7. Once PUCCH has been transmitted on the non-anchor carrier, the power control controller  836  performs power control according to the power control command from the eNB. 
         [0103]    The eNB apparatus according to the second embodiment can be implemented in the same configuration as the eNB described with reference to  FIG. 7 . A brief description is made as follows. 
         [0104]    The eNB includes an RF/IF unit for the RF/IF signal processing on the signals received from UEs, the FFT unit for perming FFT process, the RE demappers for the respective component carriers, and the PUSCH/UCCH/SRS processor. The eNB further includes an eNB scheduler for generating scheduling grant to the UE and scheduling information generator per component carrier for generating control information. The eNB performs channel coding, modulation, and RE mapping, IFFT signal processing, and IF/RF signal processing on the control information generated by the scheduling grant generator, and transmits the processed signal to the UE. The RF/IF unit and IFFT unit can be implemented per component carrier. 
       Third Embodiment 
       [0105]    The third embodiment describes a method for configuring initial SRS transmission power when the first signal transmitted by UE on the non-anchor carrier is Sounding Reference Signal (SRS) in the LTE-A system. SRS is used for the eNB to measure uplink channel state. 
         [0106]    The SRS transmission power in i th  subframe on k th  component carrier is determined by equation 8. 
         [0000]        P   SRS ( i, k =min{ P   CMAX   ,P   SRS     —     OFFSET ( j,k )+10 log 10 ( M   SRS ( k ))+ P   O     —     PUSCH ( j,k )+α( j,k )· PL ( k )+ f ( i,k )}  Equation 8
       P CMAX : maximum allowed UE transmission power which is determined depending on the UE class and higher layer signaling configuration.   P SRS     —     OFFSET (j,k): SRS power control offset for k th  component carrier transmitted from the eNB to the UE.   (M SRS (k): bandwidth for transmitting SRS on k th  component carrier which is expressed by a number of PRBs.   P O     —     PUSCH (j,k): interference amount which is measured by the eNB on the k th  component carrier and signaled to the UE, where index j is set to a value according to the type of data to be scheduled, i.e. j=1 for the semi-persistent scheduling data for which the scheduling grant is valid for a predetermined duration, j=2 for the dynamic scheduling data, and j=3 for the uplink data in the random access process.   α(j,k): value for partially compensating pathloss between eNB and UE on k th  component carrier. 0≦α(j,k)≦1   PL(k): pathloss between eNB and UE on k th  component carrier, the UE calculates pathloss based on the difference between the transmission power of the RS signaled by the eNB and received signal level of the RS.   f(i,k): calculated based on the power control command included in the eNB scheduling information in i th  subframe on k th  component carrier.       
 
         [0114]    That is, equation 8 shows that the SRS transmission power of the UE is determined based on the channel environment compensation parameter (P O     —     PUSCH (k), α(j,k), (P SRS     —     OFFSET (j,k), M SRS (k)), SRS-related parameter (M PUSCH (i,k), Δ TF (i,k)) transmitted according to eNB scheduling, and additional compensation f(i,k). 
         [0115]    If the uplink anchor carrier index is k=0, the initial value of the SRS transmission power on the uplink non-anchor carrier (k≠ 0 ) is obtained by applying the initial value of f(i,k) defined by equation 9 to equation 8. 
         [0000]        f ( i,k=P   SRS ( i  0)− P   SRS     —     OFFSET ( j, 0)−10 log 10 ( M   SRS (0))− P   O     —     PUSCH ( j, 0)−α( j, 0)· PL (0   Equation 9
 
         [0116]    In equation 9, P SRS (i,0) is SRS transmission power of the UE in i th  subframe on the anchor carrier and, if there is no SRS transmission in i th  subframe on the anchor carrier, the transmission power of the SRS transmitted most recently on the anchor carrier is referenced. 
         [0117]    The initial value of f(i,k) on the non-anchor carrier which is expressed by equation 9 is the value applied first when the first signal transmitted the UE on the non-anchor carrier is SRS and, once SRS is transmitted, calculated based on the power control command from the eNB. 
         [0118]    Equation 10 is of the value obtained by reflecting equation 9 to equation 8 and indicates the initial transmission power of SRS when the signal transmitted first by the UE on the non-anchor carrier is SRS. 
         [0000]        P   SRS ( i, k )=min{ P   CMAX   ,P   SRS ( i, 0)+ P   SRS     —     OFFSET ( j,k )− P   SRS     —     OFFSET ( j, 0)+10 log 10 ( M   SRS ( k )/ M   SRS (0))+ P   O     —     PUSCH ( j,k )− P   O     —     PUSCH ( j, 0)+( j,k )· PL ( k )−αα( j, 0)· PL (0)}  Equation 10
 
         [0119]    As a result, equation 10 shows that the UE&#39;s initial transmission power on the non-anchor carrier is calculated with the UE&#39;s most recent transmission power level on the anchor carrier, channel environment difference between anchor and non-anchor carriers, and scheduling information difference between the anchor and non-anchor carriers, as described with reference to equation 1. 
         [0120]      FIG. 9  is a diagram illustrating a UE apparatus according to the third embodiment of the present invention. 
         [0121]    Referring to  FIG. 9 , the UE operates on the two uplink component carriers aggregated. For uplink transmission, the transmitter of the UE includes SRS generators  902  and  904  for generating Sounding Reference Signal (SRS) to be transmitted on the respective component carriers and RE mappers  906  and  908  for mapping the SRSs to Resource Elements (REs). The signals output by the RE mappers  906  and  910  responsible for the corresponding component carriers are processed by Inverse Fast Fourier Transform  912  and IF/RF unit  914  to be transmitted. Although the IFFT unit  912  and IF/RF unit  914  are depicted as common function blocks, they can be implemented per component carrier. 
         [0122]    The receiver of the UE includes an RF/IF unit  916  for performing RF/IF signal processing on the received signal, a FFT unit  918  for performing FFT, RE demappers  920  and  922  for performing RE demapping on the corresponding component carriers, modulation mappers  914  and  926 , and channel decoders  928  and  930 . The RF/IF unit  916  and FFT unit  918  can be implemented per component carrier. 
         [0123]    The carrier aggregation controller  932  acquires SRS transmission-related information from the UE receiver to determine the uplink component carrier for SRS transmission. The carrier aggregation controller  932  controls the SRS generators  902  and  904  to generate SRS to be transmitted on the uplink component carriers according to the determination result. The carrier aggregation controller  932  controls the power control controller  934  to control transmission power on the corresponding component carriers. The power control controller  934  performs transmission power control on the corresponding component carrier based on control signal of the uplink carrier aggregation controller  932  and the power control command received through the UE receiver. 
         [0124]    Although the power control is applied to the RE mappers  906  and  910  for the respective component carriers, it can be applied to other functional devices. If the first signal transmitted by the UE on the non-anchor carrier is SRS, the power control controller  934  configures the initial SRS transmission power using equation 10. Once the SRS is transmitted on the non-anchor carrier, the power control controller  934  performs power control according to the power control command transmitted by the eNB. 
         [0125]    The eNB apparatus according to the third embodiment is implemented in the same configuration as the eNB apparatus described with reference to  FIG. 7 . A brief description is made as follows. 
         [0126]    The eNB includes an RF/IF unit for performing RF/IF processing on the received signal, an FFT unit for performing FFT processing, RE demappers responsible for RE demapping on the respective component carriers, and a PUSCH/PUCCH/SRS processor. The eNB further includes an eNB scheduler for generating scheduling grant to the UE and a scheduling information generator per component carrier for generating control information. The eNB performs channel coding, modulation, and RE mapping, IFFT signal processing, and IF/RF signal processing on the control information generated by the scheduling grant generator, and transmits the processed signal to the UE. The RF/IF unit and IFFT unit can be implemented per component carrier. The specification and drawings are to be regarded in an illustrative rather than a restrictive sense in order to help understand the present invention. It is obvious to those skilled in the art that various modifications and changes can be made thereto without departing from the broader spirit and scope of the invention.