JP5302417B2 - Method for controlling transmission power and apparatus for controlling transmission power - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method and device for efficiently controlling transmission power when transmitting a plurality of signals in a wireless communication system. <P>SOLUTION: The present invention relates to a wireless communication system. Specifically, the present invention relates to a signal transmission method in which a terminal transmits a signal in a wireless communication system, the method comprising the steps of: checking maximum transmission power (P_CC_MAX) for each component carrier wave of a plurality of component carrier waves, and maximum transmission power (P_UE_MAX) of the terminal; calculating transmission power for each of a plurality of channels to be simultaneously transmitted to a base station through one or more component carrier waves; independently adjusting the transmission power for each of the plurality of channels so as not to exceed the maximum transmission power (P_CC_MAX) and the maximum transmission power (P_UE_MAX); and transmitting a signal to the base station through the plurality of channels for which the transmission power is adjusted. <P>COPYRIGHT: (C)2013,JPO&amp;INPIT

Description

  The present invention relates to a wireless communication system, and more particularly, to a method for controlling uplink transmission power and an apparatus for controlling uplink transmission power.

  Wireless communication systems are widely deployed to provide a wide variety of communication services such as voice and data. Generally, a wireless communication system is a multiple access system that can support communication with multiple users by sharing available system resources (bandwidth, transmission power, etc.). Examples of multiple access systems include code division multiple access (CDMA) systems, frequency division multiple access (FDMA) systems, time division multiple access (TDMA) systems, Orthogonal Frequency Division Multiple Access (OFDMA) system, Single Carrier Frequency Division Multiple Access (SC-FDMA) system, Multi Carrier Frequency Division Multiple Access (Multi Carrier Frequency Division Multiple Access) MC-FDMA) system.

  An object of the present invention is to provide a method and apparatus for efficiently controlling transmission power when transmitting a plurality of signals in a wireless communication system.

  Another object of the present invention is to provide a method and apparatus for efficiently controlling transmission power when the sum of transmission power of signals exceeds the maximum transmission power when transmitting a plurality of signals. .

  The technical problems to be solved by the present invention are not limited to the technical problems mentioned above, and other technical problems that are not mentioned are based on the following description and are based on ordinary knowledge in the technical field to which the present invention belongs. It will be clearly understood by those who have

  According to one aspect of the present invention, there is provided a method for transmitting a signal in a wireless communication system, wherein each transmission power for a first channel and a second channel is determined independently, and the first channel and the second channel When the sum of the transmission power of the channels exceeds the maximum transmission power, considering the channel priority, reducing at least one of the transmission power of the first channel or the second channel; Transmitting a signal simultaneously through the first channel and the second channel.

  As another aspect of the present invention, a radio frequency (RF) unit configured to transmit / receive a radio signal to / from a base station, information transmitted / received to / from the base station, and parameters necessary for operation of the terminal are stored. And a processor connected to the RF unit and the memory and configured to control the RF unit and the memory for operation of the terminal, wherein the processor Independently determining each transmission power for the first channel and the second channel, and when the sum of the transmission power of the first channel and the second channel exceeds the maximum transmission power, considering the channel priority, Reducing at least one of the transmission power of the first channel or the second channel, and causing the base station to transmit the first channel and the second channel. Configured terminal is provided to perform the signal transmission method having the steps of simultaneously transmitting signals through channel.

  Here, each of the first channel and the second channel may have one or a plurality of single carrier frequency division multiple access (SC-FDMA) symbols. Meanwhile, the channel priority may be determined in consideration of at least one of a channel type and information on the channel. The first channel and the second channel are each a physical uplink shared channel (PUSCH), a physical uplink control channel (PUCCH), or a sounding reference signal (SRS). Can have any of the following.

  Here, when both the first channel and the second channel are PUSCH, the channel priority is determined in consideration of at least one of the transmission format, whether or not the retransmission is performed, and the number of retransmissions. May be. Further, when the transmission power of the PUSCH decreases, the modulation / coding scheme (MCS) applied to the PUSCH can be adjusted to be low in consideration of the reduced power amount. Also, when the first channel is a PUCCH carrying ACK and the second channel is a PUSCH, the channel priority of the PUSCH may be set higher.

  According to still another aspect of the present invention, there is provided a method for transmitting a signal in a wireless communication system, in which a terminal transmits a component carrier maximum transmission power (P_CC_MAX) and a maximum transmission power of the terminal (P_UE_MAX). ), Calculating respective transmission power for a plurality of channels scheduled to be simultaneously transmitted to the base station through one or more component carriers, and determining the P_CC_MAX and the P_UE_MAX A signal transmission method comprising: independently adjusting transmission power for the plurality of channels so as not to exceed; and transmitting a signal to the base station through the plurality of channels in which the transmission power is adjusted. Is provided.

  As still another aspect of the present invention, a radio frequency (RF) unit configured to transmit and receive a radio signal to and from a base station, information to be transmitted to and received from the base station, and parameters necessary for the operation of the terminal are provided. A storage memory; and a processor connected to the RF unit and the memory and configured to control the RF unit and the memory for operation of the terminal, wherein the processor comprises: Checking the maximum transmission power per component carrier (P_CC_MAX) and the maximum transmission power of the terminal (P_UE_MAX) for a plurality of component carriers, and simultaneously transmitting to the base station through one or more component carriers Calculate each transmit power for multiple scheduled channels A step of independently adjusting transmission power for the plurality of channels so as not to exceed the P_CC_MAX and the P_UE_MAX; and a signal to the base station through the plurality of channels for which the transmission power is adjusted. And a terminal configured to perform a signal transmission method.

  Here, the information for setting the P_CC_MAX or the information for setting the P_UE_MAX may be signaled through a broadcast message or a radio resource control (RRC) message.

  Here, the step of adjusting the transmission power for the plurality of channels independently reduces the transmission power of each channel so that the sum of the transmission powers of the plurality of channels does not exceed the P_UE_MAX. After reducing the transmission power of each channel, for each component carrier, independently reducing the transmission power of the corresponding channel so that the sum of the transmission power of the corresponding channels does not exceed the corresponding P_CC_MAX be able to. In this case, at least part of the power reduced from the corresponding channel so as not to exceed the corresponding P_CC_MAX may be used to increase the transmission power of other component carriers.

  Here, in the step of adjusting the transmission power for the plurality of channels, for each component carrier wave, the transmission power of the corresponding channel is made independent so that the sum of the transmission power of the corresponding channel does not exceed the corresponding P_CC_MAX. And reducing the transmission power of each channel independently after reducing the transmission power of each channel so that the sum of the transmission power of the plurality of channels does not exceed the P_UE_MAX. be able to.

  Here, the step of adjusting the transmission power for the plurality of channels may be performed by applying an attenuation coefficient to each channel independently.

  Here, each channel may have one or more single carrier frequency division multiple access (SC-FDMA) symbols. In this case, each channel receives either a physical uplink shared channel (PUSCH), a physical uplink control channel (PUCCH), or a sounding reference signal (SRS). Can have.

  According to still another aspect of the present invention, there is provided a method for transmitting a signal by a terminal in a wireless communication system, calculating each transmission power for a plurality of antennas, and calculating the calculation for each antenna. Calculating the transmission power attenuation ratio when the transmission power exceeds the maximum transmission power of the corresponding antenna, and applying the maximum attenuation ratio to the plurality of antennas in the one or more transmission power attenuation ratios; And a method of transmitting a signal to a base station through the plurality of antennas.

  According to the embodiment of the present invention, transmission power can be efficiently controlled when a plurality of signals are transmitted in a wireless communication system. Further, when the sum of the transmission power of signals exceeds the maximum transmission power, the transmission power can be controlled efficiently.

1 is a diagram illustrating a network structure of an Evolved Universal Mobile Telecommunications System (E-UMTS). FIG. It is a figure which shows the radio | wireless interface protocol structure between the terminal and E-UTRAN based on 3GPP radio | wireless access network specification. FIG. 2 is a block diagram illustrating a transmitter and receiver for OFDMA and SC-FDMA. It is a figure which shows the structure of the radio | wireless frame used by LTE. It is a figure which shows the example which communicates under a single component carrier wave environment. It is a figure which shows the structure of the uplink sub-frame used by LTE. It is a figure which shows the structure of the uplink control channel used by LTE. It is a figure which shows the example which communicates under a multi-component carrier environment. It is a figure which shows the example which adjusts transmission power by the Example of this invention. It is a figure which shows the example which transmits several signals by the Example of this invention. It is a figure which shows the example which adjusts transmission power by the Example of this invention, when the maximum transmission power is restrict | limited to the unit of one or several component carrier waves. FIG. 6 is a diagram illustrating another example of adjusting transmission power according to an embodiment of the present invention when maximum transmission power is limited to one or a plurality of component carrier units. 1 is a diagram illustrating a base station and a terminal that can be applied to an embodiment of the present invention.

  The accompanying drawings are included as part of the detailed description to facilitate understanding of the invention, and provide examples of the invention and together with the detailed description, explain the technical idea of the invention.

  Hereinafter, the structure, operation, and other features of the present invention will be easily understood from the embodiments of the present invention described with reference to the accompanying drawings. Embodiments of the present invention may be used for various wireless access technologies such as CDMA, FDMA, TDMA, OFDMA, SC-FDMA, MC-FDMA. CDMA can be implemented with a radio technology such as Universal Terrestrial Radio Access (UTRA) or CDMA2000. TDMA is like Global System for Mobile Communications (GSM) / General Packet Radio Service (GPRS) / Enhanced Data Rates for GSM Evolution (EDGE) It can be implemented with simple wireless technology. OFDMA includes IEEE 802.11 (Wi-Fi (Wi-Fi, Wireless LAN Interconnection Authentication)), IEEE 802.16 (WiMAX (Wimax, World Interoperability for Microwave Access)), IEEE 802.20, It can be implemented with a wireless technology such as Evolved UTRA (E-UTRA). UTRA is part of the Universal Mobile Telecommunications System (UMTS). 3rd Generation Partnership Project (3GPP) Long Term Evolution (LTE) is part of Evolved UMTS (E-UMTS) using E-UTRA . LTE-Advanced (LTE-A) is an evolved version of 3GPP LTE.

  The following examples will be described with a focus on the case where the technical features of the present invention are applied to a 3GPP system, but this is illustrative and the present invention is not limited thereto.

  FIG. 1 is a diagram illustrating a network structure of E-UMTS. E-UMTS is also called an LTE system. The detailed contents of the UMTS and E-UMTS technical specifications are each released in the “3rd Generation Partnership Project (Technical Specification Group Radio Access Network)” release. ) Refer to 7 and Release 8.

  Referring to FIG. 1, the E-UMTS is connected to an external network at a terminal (User Equipment; UE) 120, a base station (eNode B; eNB) 110a and 110b, and a network (E-UTRAN). Access gateway (AG). The base station can simultaneously transmit multiple data streams for broadcast service, multicast service and / or unicast service. One base station has jurisdiction over one or more cells. Any one of bandwidths such as 1.25, 2.5, 5, 10, 15, and 20 MHz is set in the cell. Different bandwidths may be set for different cells. The base station controls data transmission / reception with respect to a large number of terminals. For downlink (DL) data, the base station transmits downlink scheduling information to transmit data to a corresponding terminal in time / frequency domain, encoding, data size, hybrid automatic repeat request (Hybrid Automatic Repeat). and reQuest; HARQ) related information. Also, for uplink (UL) data, the base station transmits uplink scheduling information to the corresponding terminal, and the time / frequency domain, encoding, data size, HARQ related information, etc. that can be used by the corresponding terminal. Inform. The core network (CN) may be configured by an AG and a network node for user registration of a terminal. AG manages the mobility of a terminal in a tracking area (TA) unit composed of a plurality of cells.

  FIG. 2 is a diagram illustrating a structure of a control plane (Control Plane) and a user plane (User Plane) of a radio interface protocol between the terminal and the E-UTRAN based on the 3GPP radio access network standard. The control plane means a path through which control messages used by the terminal and the network to manage calls are transmitted. The user plane means a path through which data generated in the application layer, for example, voice data or Internet packet data is transmitted.

  The physical layer, which is the first layer, provides an information transfer service to an upper layer using a physical channel (PHY). The physical layer is connected to the upper medium access control (MAC) layer through a transport channel. Data moves between the MAC layer and the PHY layer through the transmission channel. Between the PHY layer on the transmission side and the PHY layer on the reception side, data moves through the physical channel. The physical channel uses time and frequency as radio resources. Specifically, the physical channel is modulated by the OFDMA scheme in the downlink and by the SC-FDMA scheme in the uplink.

  The media access control layer in the second layer provides services to a radio link control (RLC) layer, which is an upper layer, through a logical channel. The RLC layer in the second layer supports reliable data transmission. The function of the RLC layer may be implemented by a functional block inside the MAC. The Packet Data Convergence Protocol (PDCP) layer in the second layer is a header compression that reduces unnecessary control information to efficiently transmit IP packets such as IPv4 and IPv6 over a low-bandwidth wireless interface. (Header compression) function is executed.

  A radio resource control (RRC) layer located at the bottom of the third layer is defined only in the control plane. The RRC layer is responsible for controlling logical channels, transmission channels, and physical channels in connection with configuration, re-configuration, and release of radio bearers (RBs). RB means a service provided by the second layer for data transmission between the terminal and the network. For this, the RRC layer of the terminal and the network exchange RRC messages with each other. If there is an RRC connection between the terminal and the RRC layer of the network (RRC connected), the terminal is in an RRC connected mode (connected mode), and otherwise, it is in an RRC idle mode. A non-access stratum (NAS) layer above the RRC layer performs functions such as session management and mobility management.

  The downlink transmission channel for transmitting data from the network to the terminal transmits a broadcast channel (BCH) for transmitting system information, a paging channel (PCH) for transmitting a paging message, user traffic and a control message. There is a downlink shared channel (DL-SCH). On the other hand, the uplink transmission channel for transmitting data from the terminal to the network includes an initial control message for transmission Random Access CHannel (RACH), and an uplink shared channel for transmission of user traffic and control messages (Uplink-Shared CHannel). ; UL-SCH).

  FIG. 3 is a block diagram illustrating a transmitter and receiver for OFDMA and SC-FDMA. In the uplink, transmitters 402-414 are part of the terminal and receivers 416-430 are part of the base station. In the downlink, the transmitter is part of the base station and the receiver is part of the terminal.

  Referring to FIG. 3, an OFDMA transmitter includes a serial to parallel converter 402, a sub-carrier mapping module 406, an M-point inverse discrete Fourier transform (Inverse Discrete Fourier Transform). Transform (IDFT) module 408, Cyclic Prefix (CP) addition module 410, parallel to serial converter 412 and Radio Frequency (RF) / Digital to Analog Converter (Digital to Analog Converter) DAC) module 414.

  The signal processing process in the OFDMA transmitter is as follows. First, a bit stream is modulated into a data symbol sequence. The bit stream is obtained by performing various signal processing such as channel encoding, interleaving, scrambling on the data block transmitted from the MAC layer. The bitstream is also called a codeword and is equivalent to a data block received from the MAC layer. Data blocks received from the MAC layer are also called transmission blocks. The modulation method is not limited to this, but two-phase phase modulation (BPSK), four-phase phase modulation (QPSK), n quadrature amplitude modulation (Quadrature Amplitude Modulation); QAM). Thereafter, N serial data symbol sequences are converted in parallel by N (402). The N data symbols are mapped to the allocated N subcarriers among all the M subcarriers, and the remaining MN carriers are zero-padded (406). The data symbols mapped in the frequency domain are converted to a time domain sequence by M-point IDFT processing (408). Thereafter, in order to reduce inter-symbol interference (ISI) and inter-carrier interference (ICI), an CP is added to the time domain sequence to generate an OFDMA symbol (410). The generated OFDMA symbol is converted from parallel to serial (412). Thereafter, the OFDMA symbol is transmitted to the receiver through a process such as digital to analog conversion and frequency up conversion (414). Other users are assigned available subcarriers among the remaining MN subcarriers. Meanwhile, the OFDMA receiver includes an RF / Analog to Digital Converter (ADC) module 416, a serial / parallel converter 418, a CP removal module 420, an M-point discrete Fourier transform (Discrete Fourier Transform). A DFT module 422, a subcarrier demapping / equalization module 424, a parallel / serial converter 428 and a detection module 430. The signal processing process of the OFDMA receiver is the reverse process of the OFDMA transmitter.

  On the other hand, the SC-FDMA transmitter further includes an N-point DFT module 404 before the subcarrier mapping module 406 compared to the OFDMA transmitter. The SC-FDMA transmitter uses a DFT to spread a plurality of data in the frequency domain before the IDFT process, thereby obtaining a peak-to-average power ratio (PAPR) of the transmission signal. As compared with the OFDMA system, it can be greatly reduced. The SC-FDMA receiver further includes an N-point IDFT module 426 after the subcarrier demapping module 424 compared to the OFDMA receiver. The signal processing process of the SC-FDMA receiver is the reverse process of the SC-FDMA transmitter.

  FIG. 4 is a diagram illustrating a structure of a radio frame used in LTE.

Referring to FIG. 4, a radio frame has a length of 10 ms (327200 · T _s ) and is composed of ten subframes having the same size. Each subframe has a length of 1 ms and is composed of two slots. Each slot has a length of 0.5 ms (15360 · T _s ). T _s represents a sampling time, and is expressed as T _s = 1 / (15 kHz × 2048) = 3.2552 × 10 ⁻⁸ (about 33 ns). A slot includes a plurality of OFDM symbols in the time domain, and includes a plurality of resource blocks (RBs) in the frequency domain. In the LTE system, one resource block includes 12 subcarriers × 7 (or 6) OFDM symbols. A transmission time interval (TTI), which is a unit time in which data is transmitted, may be determined in units of one or a plurality of subframes. The structure of the radio frame described above is merely an example, and the number of subframes, the number of slots, and the number of OFDM symbols included in the radio frame can be variously changed.

  FIG. 5 is a diagram illustrating an example in which communication is performed in a single component carrier environment. FIG. 5 may correspond to a communication example in the LTE system.

Referring to FIG. 5, in general, in the FDD scheme, communication is performed through one downlink band and one uplink band corresponding thereto. In the TDD scheme, communication is performed through a downlink section and an uplink section corresponding thereto. In the FDD or TDD scheme, transmission and reception of data and / or control information may be performed in units of subframes. When the channel environment is not good, the terminal uses the power control method to transmit with higher power, and when the channel environment is good, the terminal lowers the power and transmits the adjacent cell due to excessive transmission power. Reduce power interference and optimize power usage. If the channel environment is not good, the base station commands to increase the power of the terminal, but ignores the command to exceed the maximum transmission power of the terminal (ie, transmission power limit; P ^UE _Max or P _Max ). Is done.

  FIG. 6A is a diagram illustrating a structure of an uplink subframe used in LTE.

  Referring to FIG. 6A, the uplink subframe includes a plurality of (eg, two) slots. A slot may include a different number of SC-FDMA symbols depending on the CP length. As an example, for a normal CP, a slot can include 7 SC-FDMA symbols. The uplink subframe is classified into a data area and a control area. The data area includes a physical uplink shared channel (PUSCH) and is used to transmit data signals such as voice and video. The power of the data signal is determined based on the power of the reference signal included in the same area. As an example, the power of the data signal may be determined based on the power of a demodulation reference signal (DeModulation Reference Signal; DMRS).

  The control area includes a physical uplink control channel (PUCCH) and transmits various control information on the uplink. The PUCCH includes RB pairs (Resource Block pairs) located at both ends of the data area on the frequency axis, and hops with the slot as a boundary. The transmission power of the control information is determined based on the transmission power of the control channel reference signal located in the PUCCH. Details of the PUCCH structure will be described later with reference to FIG. 6B. A sounding reference signal (SRS) for uplink channel measurement is located in the last SC-FDMA symbol of the subframe and is transmitted through all or part of the band of the data region.

  In the LTE system, the uplink transmission is characterized by a single carrier characteristic using SC-FDMA, which is a physical uplink shared channel (PUSCH), a physical uplink control channel (Physical Uplink Control CHannel; PUCCH) and sounding reference signal (SRS) cannot be transmitted simultaneously. SC-FDMA enables efficient use of power amplifiers by maintaining a low PAPR compared to multi-carrier systems (eg, OFDM). Therefore, when data and a control signal are to be transmitted at the same time, information to be transmitted on the PUCCH is multiplexed with data in the PUSCH region by a piggyback method. Also, PUSCH and PUCCH are not transmitted in SC-FDMA symbols in which SRS is transmitted. The power control of PUSCH and PUCCH is performed independently.

  FIG. 6B illustrates a PUCCH structure used in LTE.

  Referring to FIG. 6B, in the case of a general CP, a reference signal (UL RS) is carried on three consecutive symbols located in the middle of the slot, and control information (ie, control information (ie, RS) is placed on the remaining four symbols). ACK / NACK). In the case of the extended CP, the slot includes six symbols, and a reference signal is placed on the third and fourth symbols. The control information further includes a channel quality indicator (CQI), a scheduling request (SR), a precoding matrix indicator (PMI), a rank indicator (Rank Indicator; RI), and the like. The transmission power of the control information is determined based on the transmission power of the reference signal (UL RS). In the PUCCH structure, the number and position of UL RSs vary depending on the type of control information. The resources for the control information are different cyclic shifts (CS) (frequency spreading) and / or different from each other of a Computer Generated Constant Amplitude and Zero Auto Correlation (CG-CAZAC) sequence Partitioned using Walsh / DFT orthogonal code (time spread). Even if w0, w1, w2, and w3 multiplied after IFFT are multiplied before IFFT, the result is the same. The reference signal may be multiplied by a corresponding length Orthogonal Cover (OC) sequence.

  FIG. 7 shows an example in which communication is performed under a multi-component carrier environment. Recently, wireless communication systems (eg, LTE-A systems) are carriers that use a larger uplink / downlink bandwidth by bundling multiple uplink / downlink frequency blocks to use a wider frequency band. Use aggregation (carrier aggregation or bandwidth aggregation) techniques. Each frequency block is transmitted using a component carrier (CC). In this specification, a component carrier may refer to a frequency block for carrier aggregation or a center carrier of a frequency block according to a context, and these are mixed with each other.

Referring to FIG. 7, five 20 MHz CCs are bundled in each uplink / downlink to support 100 MHz bandwidth. Each CC is adjacent or non-adjacent to each other in the frequency domain. FIG. 7 shows a case where the bandwidth of the uplink component carrier and the bandwidth of the downlink component carrier are both the same and symmetrical for convenience. However, the bandwidth of each component carrier may be determined independently. As an example, the bandwidth of the uplink component carrier may be configured as 5 MHz (A _UL ) +20 MHz (B _UL ) +20 MHz (C _UL ) +20 MHz (D _UL ) +5 MHz (E _UL ). Also, asymmetric carrier aggregation in which the number of uplink component carriers and the number of downlink component carriers are different is possible. Asymmetric carrier aggregation may occur due to a limitation of usable frequency bands, or may be intentionally performed depending on network settings. As an example, even if the entire system band is composed of N CCs, the frequency band that can be received by a specific terminal may be limited to M (<N) CCs. Various parameters for carrier aggregation may be set in a cell-specific, terminal group-specific (UE group-specific) or terminal-specific (UE-specific) scheme.

  In the LTE-A system, the transmitting end can transmit a plurality of signals / (physical) channels simultaneously through a single or multiple CCs. As an example, two or more same or different channels selected from PUSCH, PUCCH or SRS can be transmitted simultaneously. Therefore, when transmitting a plurality of (physical) channels without maintaining the single carrier transmission characteristic, the operation of the terminal when the sum of the transmission powers calculated for the plurality of (physical) channels reaches the maximum transmission power limit Need to be considered. Unless otherwise specified herein, a plurality of signal / (physical) channels means a signal / (physical) channel whose transmission power is independently determined. As an example, the plurality of signal / (physical) channels includes signal / (physical) channels associated with separate reference signals. In this specification, transmitting a (physical) channel means transmitting a signal through a (physical) channel. In this specification, signals and (physical) channels are mixed.

  Hereinafter, a method for controlling transmission power will be described in detail with reference to FIGS. For convenience, FIGS. 8 to 11 are described from the standpoint of a terminal. However, this is merely an example, and the base station may be easily modified and applied when transmitting a plurality of signals. In the embodiment according to the present invention, the transmission power can be expressed in a linear scale or a dB scale. In addition, the operation according to the embodiment of the present invention may be performed in a power domain or an amplitude domain.

Embodiment 1: Power Control Considering (Channel) Priority Order FIG. 8 is a diagram showing an example of adjusting transmission power according to an embodiment of the present invention. The present embodiment proposes to adjust the transmission power of a physical channel in consideration of (channel) priority when the sum of the transmission powers of a plurality of physical channels exceeds the maximum transmission power.

  Referring to FIG. 8, the terminal may receive one or more Transmit Power Control (TPC) commands from the base station (S810). The TPC command may be included in a response message to a preamble for random access or may be transmitted through a physical downlink control channel (PDCCH). The PDCCH has various formats depending on downlink control information (DCI), and a transmitted TPC command may differ depending on the format. For example, the UE can use various formats such as a format for downlink scheduling, a format for uplink scheduling, a TPC dedicated format for the uplink data channel (PUSCH), and a TPC dedicated format for the uplink control channel (PUCCH). Can be received. Also, the TPC command can be used to determine the transmission power for each component carrier, the transmission power for the component carrier group, or the transmission power for all component carriers. Also, the TPC command can be used to determine the transmission power for each signal (eg, PUSCH, PUCCH, etc.). The TPC command includes a format for downlink scheduling, a format for uplink scheduling, a TPC dedicated format for an uplink data channel (eg, PUSCH), a TPC dedicated format for an uplink control channel (eg, PUCCH), etc. May be received through PDCCH of various formats.

When there are a plurality of physical channels scheduled to be simultaneously transmitted to the base station, the terminal individually determines transmission power (P1, P2,..., P _N ; N ≧ 2) for the plurality of uplink physical channels. (S820). Each uplink physical channel includes one or more consecutive OFDMA symbols or SC-FDMA symbols. An example in which the terminal transmits a plurality of signals on the uplink is shown in FIG. 9, but the present invention is not limited to this. Referring to FIG. 9, multiple physical channels can be transmitted simultaneously using single or multiple component carriers. For example, a plurality of PUCCHs, a plurality of PUSCHs, or a plurality of SRSs may be transmitted simultaneously (cases 1 to 3), or a combination of PUCCH, PUSCH and / or SRS may be transmitted simultaneously (cases 4 to 7). In the case of PUCCH, detailed classification is possible as in the case of transmitting ACK / NACK, CQI, and SR.

When the uplink transmission power is determined, the terminal checks whether the total transmission power (ΣP _n ; 1 ≦ n ≦ N) of the uplink physical channel is larger than the maximum power value (P _Max ) (S830). . The maximum power value may be given in CC, CC group, or all CC units. The maximum power value basically depends on the physical capability of the terminal, but may be determined in advance for each communication system. The maximum power value can be changed in consideration of allowable power in the cell, load balancing, and the like. Therefore, in this specification, the maximum power value is mixed with the maximum usable power value and can be substituted for each other. Information regarding the maximum power value may be broadcast in the cell through a broadcast message (eg, system information) or may be signaled through an RRC message. Also, information on the maximum power value can be transmitted to the terminal through a downlink control channel (eg, PDCCH). The maximum power value may be set permanently, semi-permanently or dynamically depending on the channel environment. If the maximum power value is limited by base station signaling, the maximum power value may have the same meaning as the allowed power value in the cell. For example, the maximum power value may be determined in advance, cell-specific method, terminal group-specific method, UE-specific method, CC group-specific component It may be specified by a carrier group-specific method or a CC-specific (component carrier-specific) method.

If the sum (ΣP _n ; 1 ≦ n ≦ N) of the transmission power of the uplink physical channel is equal to or less than the maximum power value (P _Max ), the transmission power for the corresponding uplink physical channel is maintained as it is. On the other hand, if the sum of the transmission power of the uplink physical channel is larger than the maximum transmission power value, the priority is taken into consideration so that the sum of the transmission power of the uplink physical channel does not exceed the maximum power value. The transmission power of a plurality of uplink physical channels is adjusted (S840). The priority may be determined considering the type of uplink physical channel and information on the uplink physical channel. Details of the priority order will be described later. The transmission power may be adjusted for the entire band, or may be adjusted in CC group units or CC units.

  When the transmission power for the uplink physical channel is adjusted, the terminal generates a plurality of uplink physical channels having corresponding transmission power (S850). Control of transmission power for the uplink physical channel can be performed in the frequency domain before IFFT (408 in FIG. 3), but is not limited thereto. In this case, transmission power can be controlled in units of subcarriers, for example, by multiplying a modulation value mapped to a subcarrier by a weight value. The weight value can be multiplied by using a diagonal matrix (power diagonal matrix) in which each element represents a value related to transmission power. In the case of a multiple input multiple output (MIMO) system, the transmission power is controlled by using a precoding matrix in which weight values are reflected, or the precoded modulation value is multiplied by a power diagonal matrix. Can be controlled by. Therefore, even when a plurality of physical channels are included in a frequency band to which the same IFFT is applied, the transmission power of each physical channel can be easily controlled. In addition to / in addition to power control in the frequency domain, transmission power control for the uplink physical channel may be performed in the time domain after IFFT. Specifically, transmission power control in the time domain can be performed with various functional blocks. As an example, transmission power control may be performed in a DAC block and / or an RF block (414 in FIG. 3). Thereafter, the UE transmits the generated uplink physical channels to the base station through one or more CCs (S860). In this specification, the same or the same time interval includes the same TTI or subframe.

  A method for adjusting the transmission power of the uplink channel in consideration of the priority order in step S840 of FIG. 8 will be specifically described. For convenience, the description will be given by giving the same rank or priority when only two channels exist. However, the invention is also applicable to more than two homogeneous, heterogeneous, or combinations of homogeneous and heterogeneous channels.

  For convenience of explanation, symbols are defined as follows.

P _PUSCH : represents the power calculated to be allocated to PUSCH. Due to power limitations, the actual power allocated may be less. When there is no dB display, it means a linear scale.

P _PUCCH : represents the power calculated to be allocated to PUCCH. Due to power limitations, the actual power allocated may be less. If there is no dB indication, it means a linear scale.

P _SRS : represents the power calculated to be allocated to the SRS. Due to power limitations, the actual power allocated may be less. If there is no dB indication, it means a linear scale.

Case 1-1: P _PUSCH + P _PUSCH > P _Max
Case 1-1 is a case where the maximum power limit is reached when a large number of PUSCHs are transmitted simultaneously in a large number of different CCs. The transmission power of each PUSCH can be reduced or dropped. Specifically, the following options can be considered.

  Option 1: Each PUSCH can have the same priority. When the priorities are the same, the power of all PUSCHs can be reduced at the same rate or the same amount can be reduced. That is, the same attenuation ratio can be applied or the same value can be subtracted.

Option 2: Each PUSCH can be prioritized taking into account the transmission format on the PUSCH. For example, priorities are assigned according to a transmission block size (Transport Block Size; TBS) and a modulation / coding scheme (MCS), and transmission power is sequentially reduced or dropped from a PUSCH having a lower priority. Preferably, the priority is set low for PUSCH with small TBS (data amount) or low MCS (small code rate, low modulation order). In this case, a higher attenuation ratio can be applied to a PUSCH having a lower priority. However, even if only one PUSCH remains due to the PUSCH drop, when the transmission power is exceeded, the power of the PUSCH is reduced to P _Max and transmitted.

Case 1-2: P _PUCCH (ACK / NACK) + P _PUSCH > P _Max
Case 1-2 is a case where the sum of the transmission powers of PUCCH and PUSCH transmitting ACK / NACK reaches the maximum power limit in different CCs or one CC. The following options can be considered:

Option 1: ACK / NACK can be prioritized. UL ACK / NACK reports whether or not the DL data has been successfully received. If this report is not appropriate, DL resources are wasted. For this reason, high priority is given to transmission of ACK / NACK, and transmission power of PUSCH is reduced or transmitted or dropped. When reducing the transmission power of PUSCH, first, transmission power may be allocated to PUCCH and the remaining power may be allocated to PUSCH. This can be expressed as: P _PUSCH = P _max −P _PUCCH (ACK / NACK). In this case, the following method can be further applied.

  Option 1.1: Since only the remaining power allocated to PUCCH is used for PUSCH, the error rate of PUSCH increases. Therefore, the MSCH of data transmitted to the PUSCH is reduced and transmitted so that the PUSCH can be received with the same error rate as before the power reduction. For this purpose, the reduced MCS information may be signaled to the base station.

  Option 2: The PUSCH can be prioritized. When the power of PUCCH transmitting ACK / NACK is reduced, DL resource wasted due to reception error of UL ACK / NACK. In particular, recognizing NACK as ACK leads to higher layer retransmission and increases DL data transmission delay. On the other hand, when ACK is recognized as NACK, there is only a waste of performing retransmission in the physical layer. Therefore, when urgent data is transmitted, power is first allocated to PUSCH and the remaining power (reduced power) is allocated to PUCCH transmission in case data delay occurs due to sustained low power PUSCH transmission. Can be considered. In this case, the power reduction of PUCCH is preferably limited to the case of ACK.

Case 1-3: P _SRS + P _PUSCH > P _Max
Case 1-3 is a case where the sum of the transmission power of SRS and PUSCH reaches the maximum power limit in different CCs or one CC. The following options can be considered:

Option 1: SRS transmission can be prioritized. The SRS is used by the base station to measure the UL channel state and perform optimal UL scheduling. Emphasizing the efficiency of subsequent scheduling, a higher priority is set on the SRS, and the transmission power of the PUSCH is reduced and transmitted or dropped. When reducing the transmission power of the PUSCH, first, the transmission power can be allocated to the SRS and the remaining power can be allocated to the PUSCH. This can be expressed by the following formula. P _PUSCH = P _Max -P _SRS . In this case, the following method can be further applied.

  Option 1.1: Since only the remaining power allocated to the SRS is used for the PUSCH, the PUSCH error rate increases. Therefore, the MSCH of data transmitted to the PUSCH is reduced and transmitted so that the PUSCH can be received with the same error rate as before the power reduction. For this purpose, the reduced MCS information may be signaled to the base station.

  Option 2: PUSCH transmission can be prioritized. When transmitting by reducing the transmission power of SRS, the base station misunderstands the channel information without knowing whether the reception power has dropped due to bad UL radio channel environmental conditions, or whether the terminal has transmitted with reduced power. There is. Therefore, when the transmission power is insufficient, the SRS may be dropped.

Case 1-4: P _{PUCCH (ACK / NACK)} + P _{PUCCH (ACK / NACK)} > P _Max
Case 1-4 is a case where the sum of transmission powers of a large number of PUCCHs transmitting ACK / NACK reaches the maximum power limit. The transmission power of each PUCCH is reduced or dropped. Specifically, the following options can be considered.

  Option 1: PUCCH carrying ACK / NACK can have the same priority. When the priorities are the same, the power of all PUCCHs is reduced at the same rate or the same amount is reduced. That is, the same attenuation ratio may be applied or the same value may be subtracted.

  Option 2: Prioritize and reduce or drop some PUCCH power.

  Option 2.1: Misidentifying NACK as ACK increases resource waste and delay compared to misidentifying ACK as NACK. For this reason, the transmission power of PUCCH which transmits ACK is first reduced or dropped. It is also possible to consider setting a specific threshold and reducing it to the threshold.

Option 2.2: Prioritize PUCCH based on PDSCH TBS and MCS corresponding to PUCCH ACK / NACK, and first reduce or drop the transmission power of PUCCH with lower priority. Preferably, the low TBS or low MCS PDSCH priority is set low. However, when dropping the PUCCH, if only one PUCCH remains, but exceeds the transmission power, the PUCCH power is reduced to P _max and transmitted.

Case 1-5: P _{PUCCH (CQI)} + P _{PUCCH (CQI)} > P _Max
Case 1-5 is a case where the sum of the transmission powers of a large number of PUCCHs that transmit CQI reaches the maximum power limit in different CCs. The CQI value makes it possible to grasp the state of the DL radio channel and perform efficient DL scheduling. The following options can be considered:

  Option 1: PUCCH carrying CQI can be given the same priority. When the priorities are the same, the power of all PUCCHs can be reduced at the same rate or the same amount can be reduced. That is, the same attenuation ratio may be applied or the same value may be subtracted.

  Option 2: Prioritize and reduce or drop some PUCCH power. The base station selects a radio channel with a high CQI and schedules the terminal. When the CQI is low, the possibility of selection is low, so that accurate reception is relatively not required. Therefore, in the case of PUCCH that transmits a low CQI value, transmission power is reduced with priority, and transmission or dropping is performed. A specific threshold value can be set and reduced to the threshold value.

Case 1-6: P _{PUCCH (ACK / NACK)} + P _{PUCCH (CQI)} > P _Max
Case 1-6 is a case where the sum of transmission powers of a large number of PUCCHs that transmit CQI and ACK / NACK reaches the maximum power limit. As described above, ACK / NACK has a high priority. On the other hand, CQI is information for transmitting the DL channel state to the base station and is used for effective DL scheduling. Even if a better channel is allocated to the terminal, if the normal reception of data cannot be accurately confirmed, unnecessary retransmission will be induced, and the priority of CQI will be lowered. For this reason, power is preferentially allocated to the PUCCH that transmits ACK / NACK, and the remaining power is allocated to the PUCCH that transmits CQI, or the PUCCH that transmits CQI is dropped. On the other hand, PUSCH that transmits both CQI and ACK / NACK is handled in the same way as PUCCH that transmits ACK / NACK.

Case 1-7: P _{PUCCH (SR)} + P _{PUCCH (ACK / NACK)} > P _Max
Case 1-7 is a case where the sum of transmission powers of a large number of PUCCHs that transmit SR and ACK / NACK reaches the maximum power limit. The following options can be considered:

  Option 1: High priority can be given to ACK / NACK transmission. Therefore, power is first allocated to the PUCCH in which ACK / NACK is transmitted, and the remaining power is allocated to the PUCCH in which SR is transmitted, or the PUCCH in which SR is transmitted is dropped. On the other hand, if the ACK / NACK continues to exist for a long time and the SR is dropped, UL scheduling cannot be received. To complement this, ACK / NACK can be dropped when SR is delayed for a specific time.

Option 2: High priority can be given to SR transmission. Since the ACK / NACK error is resolved by retransmission, the SR is prioritized with priority on scheduling, and the transmission power of the PUCCH in which the ACK / NACK is transmitted is reduced or transmitted. When reducing the transmission power of the PUCCH, the power remaining after the transmission power is first allocated to the SR can be allocated to the PUCCH. This can be expressed by the following equation. P _{PUCCH (ACK / NACK)} = P _Max −P _SR .

  Option 3: The terminal transmits ACK / NACK on the PUCCH in which SR is transmitted. In this case, the base station can detect on / off keying SR from the PUCCH by energy detection and determine ACK / NACK through symbol decoding. At this time, when there are a large number of PUCCHs that transmit ACK / NACK, ACK / NACK bundling or PUCCH selection transmission can be used. In ACK / NACK bundling, a plurality of DL PDSCHs are received without error, and if an ACK is sent for all, one ACK is sent. If there is an error in any one, one NACK is sent. Send. The PUCCH selective transmission represents a plurality of ACK / NACK results by transmitting a modulation value through one PUCCH resource selected from a plurality of occupied PUCCH resources when a plurality of DL PDSCHs are received.

Case 1-8: P _{PUSCH (UCI)} + P _PUSCH > P _Max
Case 1-8 is a case where the sum of transmission powers of PUSCH that transmits uplink control information (UCI) and PUCCH that transmits only data reaches a maximum power limit in different CCs. You can consider the following options:

  Option 1: The UCI is not considered, and the priority order determination method exemplified in Case 1-1 is followed. For example, the same priority can be given to each PUSCH. In this case, the power of all PUSCHs can be reduced at the same rate. Also, the priority of each PUSCH can be made different in consideration of the transmission format on the PUSCH.

Option 2: Since control information is contained in a PUCI piggybacked by UCI, it is possible to give a higher priority to a UCI piggybacked channel. For this reason, the transmission power of PUSCH carrying only data is reduced or transmitted or dropped. When reducing the transmission power of a PUSCH carrying only data, first the transmission power can be assigned to the PUSCH piggybacked by UCI, and the remaining power can be assigned to the PUSCH carrying only data. This can be expressed by the following mathematical formula. P _PUSCH = P _Max -P _{PUCCH (UCI)} . In addition, when the transmission power of the PUSCH carrying only data is reduced, a larger attenuation ratio may be applied to the PUSCH carrying only data. However, even if only one PUSCH remains due to the PUCCH drop, when the transmission power is exceeded, the PUSCH power is reduced to P _Max and transmitted.

Case 1-9: P _{PUSCH (Retransmission)} + P _PUSCH > P _Max
Case 1-9 is a case where the sum of transmission powers of PUSCH carrying retransmission data and PUSCH carrying new data reaches the maximum power limit.

  Option 1: Follow the priority determination method exemplified in Case 1-1 without considering retransmission. For example, the same priority can be given to each PUSCH. In this case, the power of all PUSCHs can be reduced at the same rate. Also, the priority of each PUSCH can be made different from each other in consideration of the transmission format on the PUSCH.

  Option 2: Since retransmission may be caused by attenuation of transmission power at the time of previous transmission, it is possible to improve the PUSCH reception rate by increasing the priority of the PUSCH to be retransmitted.

Case 1-10: P _{PUSCH (Retransmission)} + P _{PUSCH (Retransmission)} > P _Max
Case 1-10 is a case where the sum of the transmission powers of the PUSCH carrying retransmission data reaches the maximum power limit. You can consider the following options:

  Option 1: Follow the priority determination method exemplified in Case 1-1 without considering retransmission. For example, the same priority can be given to PUSCH. In this case, the power of all PUSCHs can be reduced at the same rate. In addition, considering the transmission format on the PUSCH, the priorities of the PUSCH can be made different from each other.

  Option 2: Since retransmission may be due to transmission power attenuation during previous transmissions, a higher priority is given to the PUSCH with a higher number of retransmissions, and the reception rate of the PUSCH with more retransmissions is increased. Improve more.

Case 1-11: P _{PUSCH (Retransmission)} + P _PUCCH / P _SRS > P _Max
Case 1-11 is a case where the sum of transmission powers of PUSCH and PUCCH / SRS carrying retransmission data reaches the maximum power limit. You can consider the following options:

  Option 1: It is possible to follow the priority determination method exemplified in cases 1-2 and 1-3 without considering retransmission.

  Option 2: Since retransmission may be caused by attenuation of transmission power at the time of previous transmission, a higher priority can be given to the PUSCH to be retransmitted to improve the reception rate of the PUSCH.

Embodiment 2: Power Control by CC (Group) The terminal transmission power control method mentioned above is suitable for a power control method when the terminal has one power amplifier. However, in LTE-A, a large number of CCs may be allocated to a terminal, and these allocated CCs may be bands that are continuous or separated on the frequency axis. If the allocated CC exists as a separated band, a terminal may require a large number of power amplifiers because it is difficult to amplify power in a wide frequency region with only one power amplifier. In this case, each power amplifier can be responsible for power amplification of only a CC group composed of one CC or a part of CCs. Therefore, by extending the scheme proposed above to a power control scheme for each CC or CC group, it can be naturally applied to an environment where a terminal has a large number of power amplifiers.

  In the following description, when the terminal reaches the transmission power limit for a specific CC (group) in an environment where both the transmission power limit for each CC (group) and the total transmission power limit for the terminal exist, the terminal total transmission power limit is reached. The terminal operation according to an embodiment of the present invention will be described in the case where both power limitations are reached simultaneously.

  In general, the uplink transmission power of the terminal can be limited as shown in Equation [1].

  If the quantization level of the transmission amplifier of the terminal is sufficiently high, the equal sign in the above inequality can be established as shown in Equation [2].

  The symbols used in the above formula are defined as follows:

：端末のアップリンク伝送電力を表す。

: Represents the uplink transmission power of the terminal.

：端末の最大伝送電力値（または伝送電力制限値）を表す。すなわち、全てのＣＣに対する端末の最大伝送電力（または伝送電力制限値）を表す。端末の最大伝送電力値は、端末の総伝送可能電力で決定されたり、ネットワーク（例えば、基地局）で設定した値との組み合わせで決定されたりしてもよい。また、端末の最大伝送電力値に関する情報は、上位層のシグナリングにより指示することができる。例えば、端末の最大伝送電力値に関する情報は、放送（broadcasting）メッセージを通じてセル−特定（cell-specific）方式でシグナリングされたり、ＲＲＣメッセージを通じて端末−特定（ＵＥ-specific）、端末グループ−特定（ＵＥ group-specific）方式でシグナリングされたりする。

: Indicates the maximum transmission power value (or transmission power limit value) of the terminal. That is, it represents the maximum transmission power (or transmission power limit value) of the terminal for all CCs. The maximum transmission power value of the terminal may be determined by the total transmittable power of the terminal or may be determined by a combination with a value set in the network (for example, a base station). Also, information on the maximum transmission power value of the terminal can be indicated by higher layer signaling. For example, information on the maximum transmission power value of the terminal is signaled in a cell-specific manner through a broadcasting message, or terminal-specific (UE-specific), terminal group-specific (UE) through an RRC message. group-specific).

：ｉ−番目のＣＣ（グループ）における最大伝送電力値（または、伝送電力制限値）を表す。ＣＣ（グループ）別最大伝送電力値は、端末の総伝送可能電力または各ＣＣ（グループ）別伝送可能電力で決定されたり、ネットワーク（例えば、基地局）でＣＣ（グループ）別に設定した値との組み合わせで決定されたりしてもよい。また、ＣＣ（グループ）別最大伝送電力値に関する情報は、上位層のシグナリングによって指示してもよい。例えば、ＣＣ（グループ）別最大伝送電力値に関する情報は、放送メッセージを通じてセル−特定（cell-specific）方式でシグナリングされたり、ＲＲＣメッセージを通じて端末−特定（ＵＥ-specific）、端末グループ−特定（ＵＥ group-specific）方式でシグナリングされたりしてもよい。一方、ＣＣ（グループ）別最大伝送電力値は、他の端末（またはＣＣ（グループ））との干渉情報（またはカバレッジ）を考慮してシグナリングされてもよい。この場合、ＣＣ（グループ）別最大伝送電力値に関する情報は、他の端末（またはＣＣ（グループ））との干渉（またはカバレッジ）に関する情報を含むことができる。ＣＣ（グループ）別最大伝送電力は、いずれのＣＣ（グループ）においても同一の値を有することができる。

: Represents the maximum transmission power value (or transmission power limit value) in the i-th CC (group). The maximum transmission power value for each CC (group) is determined by the total transmission power of the terminal or the transmission power for each CC (group), or the value set for each CC (group) in the network (for example, base station). It may be determined in combination. Further, information on the maximum transmission power value for each CC (group) may be indicated by higher layer signaling. For example, information on the maximum transmission power value for each CC (group) is signaled in a cell-specific manner through a broadcast message, or terminal-specific (UE-specific), terminal group-specific (UE) through an RRC message. It may be signaled in a group-specific manner. On the other hand, the maximum transmission power value for each CC (group) may be signaled in consideration of interference information (or coverage) with other terminals (or CC (group)). In this case, the information regarding the maximum transmission power value for each CC (group) can include information regarding interference (or coverage) with other terminals (or CC (group)). The maximum transmission power by CC (group) can have the same value in any CC (group).

：ｉ−番目のＣＣ（グループ）のｊ−番目のチャネルの伝送電力を表す。

: Represents the transmission power of the j-th channel of the i-th CC (group).

ケース２−１は、いかなるＣＣ（グループ）においてもＣＣ（グループ）の最大伝送電力の和が端末の最大伝送電力よりも小さく、同時に全てのＣＣ（グループ）におけるチャネルの伝送電力の和が、端末の最大伝送電力よりも小さいケースである。端末の伝送電力は総伝送電力値に制限されないので、数式［３］のように簡略化できる。 Case 2-1

Case 2-1 is that the sum of the maximum transmission power of CCs (groups) in any CC (group) is smaller than the maximum transmission power of the terminals, and at the same time, the sum of the channel transmission powers in all CCs (groups) This is a case that is smaller than the maximum transmission power. Since the transmission power of the terminal is not limited to the total transmission power value, it can be simplified as Equation [3].

  If the quantization level of the transmission amplifier of the terminal is sufficiently high, the equal sign in the above inequality can be established as in equation [4].

ＣＣ（グループ）の集合を意味する。この場合、集合Ｓ内においてのみ、チャネル伝送電力の和がＣＣ（グループ）最大伝送電力値を越えないように調節してもよい。電力制御は、減衰係数を導入することによって行うことができる。例えば、電力制御を、数式［５］のように、各チャネルの伝送電力に対する減衰係数

を探し求める方法に簡略化できる。 In Equations [3] and [4], in the set S, in the CC (group), the sum of the transmission power of the channels exceeds the maximum transmission power value of the CC (group).

It means a set of CC (group). In this case, adjustment may be made so that the sum of the channel transmission power does not exceed the CC (group) maximum transmission power value only in the set S. Power control can be performed by introducing an attenuation coefficient. For example, the attenuation coefficient for the transmission power of each channel is set as shown in Formula [5].

Can be simplified.

ケース２−２は、端末の最大伝送電力がＣＣ（グループ）の最大伝送電力の和よりも小さく、同時に全てのチャネルの伝送電力の和よりも小さいケースである。端末の伝送電力は、最大伝送電力値に制限されるので、数式［６］のように表現される。 Case 2-2:

Case 2-2 is a case where the maximum transmission power of the terminal is smaller than the sum of the maximum transmission powers of the CC (group) and at the same time smaller than the sum of the transmission powers of all the channels. Since the transmission power of the terminal is limited to the maximum transmission power value, it is expressed as Equation [6].

  If the quantization level of the terminal transmission amplifier is sufficiently high, the equal sign can be established in the above inequality as shown in Equation [7].

を探し求める方法に簡略化できる。 In this case, similarly to Case 2-1, the transmission power of the terminal can be reduced to the maximum transmission power value of the terminal. In this case, the sum of the transmission power of each channel within each CC (group) must be smaller than the maximum transmission power value of the CC (group), and the sum of the transmission power of all CC (groups). Must be smaller than the maximum transmission power value of the terminal. In the power control, the attenuation coefficient with respect to the transmission power of each channel is expressed by Equation [8].

Can be simplified.

  In the method illustrated in cases 2-1 and 2-2, the attenuation coefficient is obtained through optimization with respect to two kinds of restrictions (total transmission power restriction, CC (group) transmission power restriction), so that the optimization is slightly complicated. There may be a problem. Accordingly, a method for efficiently calculating the attenuation coefficient will be illustrated with reference to FIGS.

  10 and 11, the horizontal axis represents CC (group), and the vertical axis represents power intensity. A hatched box in each CC (group) represents a channel in the corresponding CC (group). Hatching is applied for convenience to represent a channel, and each hatching may mean a different channel or the same channel. 10 and 11, the sum of CC (group) transmission power is larger than the maximum transmission power value (P_UE_MAX) of the terminal, and the sum of the transmission power of channels in CC (group) 1 and 3 is Assume that the maximum transmission power (P_CC1_MAX and P_CC3_MAX) of CC (group) is exceeded ((a) in FIG. 10 and (a) in FIG. 11). CCs (groups) 1 and 3 constitute the set S described in the equations [3] and [4].

は、数式［９］の条件に合わせて独立して決定することができる。 FIG. 10 illustrates a method for determining an attenuation coefficient for power control according to an embodiment of the present invention. Referring to FIG. 10, the attenuation coefficient for power control is obtained in two stages. In the first stage, the transmission power of the channels in the set S can be attenuated in order to satisfy the transmission power limit criterion of CC (group). In the first stage, the damping coefficient

Can be determined independently according to the condition of Equation [9].

  Referring to (b) of FIG. 10, it can be seen that the sum of the transmission powers of the channels in CC (groups) 1 and 3 has decreased to the maximum transmission power value of the corresponding CC (group).

は、数式［１０］の条件に合わせて独立して決定することができる。 However, in FIG. 10B, the sum of CC (group) transmission power is still larger than the maximum transmission power value (P_UE_MAX) of the terminal. As described above, if the transmission power of the channels belonging to the set S is attenuated but still does not satisfy the total transmission power limit of the terminal, as a second stage, all CCs (groups) The total transmission power limit of the terminal can be satisfied by attenuating the transmission power of each channel. In the second stage, the damping coefficient

Can be determined independently according to the condition of Equation [10].

を１に設定し、Ｓの補集合に関してのみ

を決定したり、Ｓの補集合に在るチャネルの

を１に設定し、Ｓに関してのみ

を決定したりする方法も考慮することができる。 Referring to (c) of FIG. 10, it can be seen that the sum of transmission powers of all channels is reduced to the total transmission power limit value (P_UE_MAX) of the terminal. For the sake of simplicity, the channels in the set S

Is set to 1 and only for the complement of S

Or for channels in the complement of S

Set to 1 and only for S

It is also possible to consider how to determine the value.

は、数式［１１］の条件に合わせて独立して決定されてもよい。 FIG. 11 illustrates a method for determining an attenuation coefficient according to another embodiment of the present invention. Referring to FIG. 11, the attenuation coefficient for power control is basically obtained in two stages, and may further include one stage for power compensation. In the first step, the transmission power of channels in all CCs (groups) can be attenuated in order to satisfy the total transmission power restriction criterion of the terminal. Damping coefficient

May be determined independently according to the condition of Equation [11].

  Referring to (b) of FIG. 11, the transmission power of the channel is reduced in all the CCs (groups) so that the sum of the transmission powers of all the channels is matched with the total transmission power limit value (P_UE_MAX) of the terminal. I understand that.

は、数式［１２］の条件に合わせて独立して決定されてもよい。 However, in FIG. 11B, the sum of the transmission power of the CC (group) 3 channel is still larger than the power limit value (P_CC3_MAX) of CC (group) 3. As described above, it is assumed that there is a CC (group) (that is, a set S) that does not satisfy the transmission power limit in the CC (group) even though the transmission power of the channel is reduced in all the CC (group). For example, as the second stage, the transmission power of all CC (group) channels in the set S can be attenuated. Damping coefficient

May be determined independently according to the condition of Equation [12].

  Referring to (c) of FIG. 11, the sum of the transmission powers of the channels of CC (group) 3 (that is, set S) is decreased in accordance with the maximum transmission power value (P_CC3_MAX) of the corresponding CC (group). I understand.

を、Ｓの補集合に在るチャネルに補償することができる。ここで、各チャネルの補償後の電力は、対応するＣＣ（グループ）における最大伝送電力値を越えないようにする。図１１の（ｄ）を参照すると、第二の段階においてＣＣ（グループ）３から低減した電力が、ＣＣ（グループ）２に補償されたことがわかる。これとは違い、第二の段階において、ＣＣ（グループ）３から低減した電力は、ＣＣ（グループ）１にも補償できる。電力補償方法では下記を考慮することができる。 Then, as a third step, the amount of power reduced from the channels of set S

Can be compensated for the channels in the complement of S. Here, the compensated power of each channel is made not to exceed the maximum transmission power value in the corresponding CC (group). Referring to (d) of FIG. 11, it can be seen that the power reduced from CC (group) 3 in the second stage is compensated by CC (group) 2. On the other hand, in the second stage, the power reduced from CC (group) 3 can be compensated for CC (group) 1 as well. The following can be considered in the power compensation method.

(1) Priority criteria: Assign a priority to each channel based on the urgency or importance of messages on the channels (PUCCH, PUSCH, SRS), and compensate for more power for the channels with higher priority.
(2) Same compensation amount: Compensates with the same power for all channels in the complementary set of S.
(3) Same compensation rate: Compensate at the same rate for all channels in the complementary set of S.
(4) Compensate for power using possible combinations of (1), (2) and (3).

は、様々な方法で決定することができる。これに制限されるものではないが、減衰係数

を決定するための基準として、優先順位、同一減衰量、同一減衰率またはそれらの組み合わせを考慮できる。 Attenuation coefficient described in FIGS. 10 and 11

Can be determined in various ways. Although not limited to this, the attenuation coefficient

As a reference for determining the priority, priority, the same attenuation, the same attenuation, or a combination thereof can be considered.

  The priority criterion scheme assigns a priority to each channel based on the urgency or importance of a message in a channel (eg, PUCCH, PUSCH, SRS), and applies a larger attenuation coefficient in order of higher priority channel. In other words, this is a method of ensuring a higher reception rate as the channel has a higher priority, and probabilistically lower reception rate as the channel has a lower priority. Therefore, power is preferentially reduced from a channel with a low priority. The channel priority may be determined according to the description of cases 1-1 to 1-11, and the priority among the component carriers can be further considered. As an example, when the terminal attempts uplink transmission using multiple component carriers, some important control information or messages of the uplink transmission message may be concentrated and transmitted on a specific component carrier. In this case, a high priority can be assigned to the specific carrier wave on which the important control information is transmitted.

より簡単な方式で変形可能である。すなわち、ＣＣ（グループ）内における優先順位の低いチャネルから順次伝送電力を０にすることで、チャネルの伝送電力の和を、ＣＣ（グループ）における伝送電力制限値

よりも小さくすることができる。結果として、優先順位の低いチャネルは伝送されず、優先順位の高いチャネルは、本来の伝送電力のままで伝送される。 The priority criteria scheme is by limiting the attenuation factor to 0 or 1.

It can be deformed in a simpler manner. That is, the transmission power is set to 0 in order from the channel with the lower priority in the CC (group), so that the sum of the transmission power of the channels is determined as the transmission power limit value in the CC (group).

Can be made smaller. As a result, the low priority channel is not transmitted, and the high priority channel is transmitted with the original transmission power.

  The same attenuation reference scheme reduces the same amount from the power of all channels in each CC (group) that exceeds the transmission power limit in the CC (group). That is, all channels in the CC (group) are subject to an equivalent power attenuation penalty. This method is useful when the difference between the sum of the transmission power of the channels in the CC (group) and the maximum transmission power value of the CC (group) is small. The same attenuation ratio reference method can apply the same attenuation coefficient to all channels in each CC (group) that exceed the transmission power limit in the CC (group). The same attenuation amount reference method is a method of reducing the same amount on a linear scale, and the same attenuation ratio reference method is a method of reducing the same amount on a dB scale.

に制限できる（ｎ：アンテナインデックス）。各アンテナの最大伝送電力は、電力増幅器そのものの特性（例えば、クラス）により制限されたり、放送またはＲＲＣシグナリングにより（付加的に）制限されたりしてもよい。端末の使用可能な伝送電力の上限は、数式［１３］のように、各アンテナの最大伝送電力の和と端末の最大伝送電力のうち最小値により制限される。 Third Embodiment: Power Control Schemes Explained above for MIMO and Power Control by Antenna can be similarly applied when using transmit diversity (Tx diversity) or spatial multiplexing using MIMO. In this case, the above-described method is an operation in each layer, stream, or antenna. If the terminal has multiple transmit antennas, the maximum transmit power in the power amplifier of each antenna is

(N: antenna index). The maximum transmission power of each antenna may be limited by the characteristics (eg, class) of the power amplifier itself, or (additionally) by broadcasting or RRC signaling. The upper limit of the transmission power that can be used by the terminal is limited by the minimum value among the sum of the maximum transmission power of each antenna and the maximum transmission power of the terminal, as shown in Equation [13].

  When there is a limit on transmission power for each CC (group), the upper limit of transmission power that can be used by the terminal can be expressed as Equation [14].

  Hereinafter, the terminal operation in the case where power control is performed independently for each antenna is proposed as follows. For convenience, a case where only two antennas are present is illustrated, but the present invention can also be applied to a case where three or more antennas are used. Define the following symbols:

：ｎ番目のアンテナに割り当てられるように計算される電力を表す。電力制限によって、実際に割り当てられる電力はこれよりも小さいことがある。ｄＢ表示がない場合、線形スケール（linear scale）を意味する。Ｘ−ＣＨは、アンテナｎに伝送される全ての物理チャネル（例えば、ＰＵＳＣＨ、ＰＵＣＣＨ、ＳＲＳまたはこれらの組み合わせ）を表す。

: Represents the power calculated to be assigned to the nth antenna. Due to power limitations, the actual power allocated may be less. When there is no dB display, it means a linear scale. X-CH represents all physical channels (for example, PUSCH, PUCCH, SRS, or combinations thereof) transmitted to antenna n.

の場合は、いずれか一方のアンテナは最大電力限界に到達し、他方のアンテナは最大電力限界に到達しない場合である。この場合、下記のようにアンテナ別電力制御を行うことができる。

In this case, one of the antennas reaches the maximum power limit, and the other antenna does not reach the maximum power limit. In this case, power control for each antenna can be performed as described below.

に合わせて、各ＣＣ（グループ）に対する伝送電力を、実施例２のように調整することができる。すなわち、各ＣＣ（グループ）別に、全てのアンテナにおけるチャネルの伝送電力の和が、

を超える場合、伝送電力を調整する。段階１は、ＣＣ（グループ）別に電力制御が行われる場合にのみ含まれる。 Stage 1: Maximum transmission power limit for each CC (group)

Accordingly, the transmission power for each CC (group) can be adjusted as in the second embodiment. That is, for each CC (group), the sum of the transmission power of the channels in all antennas is

If it exceeds, adjust the transmission power. Stage 1 is included only when power control is performed for each CC (group).

  Stage 2: Considering the maximum transmit power of the antenna, the transmit power of each antenna can be adjusted as follows: The adjustment of the transmission power of the antenna may be performed by applying various methods (for example, priority) exemplified in the first and second embodiments.

は、下記の通りである。 Option 1: When a large number of transmission antennas are used, transmission may be performed with precoding. In order to decode the precoded signal at the receiving end, the precoding matrix used at the transmitting end must be recognized and decoded in the reverse order of the transmitting end. However, if the power ratio of each antenna is not maintained by the power limitation of the antenna, distortion occurs in the precoding matrix applied from the transmission end, and the reception error rate increases. Therefore, the distortion of the precoding matrix can be prevented by adjusting the power of the antenna not subject to the transmission power restriction at the same rate in accordance with the antenna subject to the transmission power restriction. That is, the transmission power of the antenna that has not reached the maximum power limit is reduced together with the transmission power of the antenna that has exceeded the power limit so that the transmission power ratio is kept the same. When there are three or more antennas, the transmission power of the remaining antennas can be adjusted at the same rate in accordance with the antenna transmission power reduced at the maximum rate. Power used for actual transmission in Option 1

Is as follows.

  Equation [15] represents the actual transmission power when there is no power limitation.

の割合で伝送電力が減少する。 Equation [16] represents the actual transmission power when there is power limitation. Referring to Equation [16], the actual transmission power of the antenna n is limited to the maximum transmission power because the sum of the transmission power of the channels exceeds the maximum transmission power. On the other hand, the antenna m does not exceed the maximum transmission power of the channel transmission power, but maintains the ratio of the transmission power to the antenna n.

The transmission power decreases at a rate of.

  Option 2: When the power ratio of each antenna indicated by the power control signal is not maintained due to power limitation of either one, distortion occurs in the precoding matrix applied from the transmitting end, and the degree of distortion is recognized at the receiving end If this is not possible, the reception error rate increases. However, when the precoding matrix used at the transmission end is indirectly estimated from the dedicated reference signal (DRS), distortion of the precoding matrix due to a change in the transmission power ratio of the antenna may be estimated together. it can. In this case, as in option 1, in order to match the transmission power ratio, it is not necessary to reduce the transmission power of the antenna that is not subject to power limitation. Therefore, only the transmission power of the antenna that has reached the maximum power limit can be transmitted with the maximum transmission power of the corresponding antenna lowered (clipping). The power used for actual transmission in Option 2 is as follows.

  Equation [17] represents the actual transmission power when there is no power limitation.

  Equation [18] represents the actual transmission power when there is power limitation. Referring to Equation [18], since the sum of the transmission power of the channels of the antenna n exceeds the maximum transmission power, the actual transmission power of the antenna n is limited to the maximum transmission power. On the other hand, since the sum of the transmission powers of the channels does not exceed the maximum transmission power, the antenna m is transmitted without any power adjustment.

  FIG. 12 is a diagram illustrating a base station and a terminal to which the embodiment can be applied to the present invention.

  Referring to FIG. 12, the wireless communication system includes a base station (BS) 110 and a terminal (UE) 120. In the downlink, the transmitter is part of the base station 110 and the receiver is part of the terminal 120. In the uplink, the transmitter is part of the terminal 120 and the receiver is part of the base station 110. The base station 110 includes a processor 112, a memory 114, and a radio frequency (RF) unit 116. The processor 112 may be configured to implement the procedures and / or methods proposed in the present invention. The memory 114 is connected to the processor 112 and stores various information related to the operation of the processor 112. The RF unit 116 is connected to the processor 112 to transmit and / or receive radio signals. The terminal 120 includes a processor 122, a memory 124, and an RF unit 126. The processor 122 may be configured to implement the procedures and / or methods proposed in the present invention. The memory 124 is connected to the processor 122 and stores various information related to the operation of the processor 122. The RF unit 126 is connected to the processor 122 to transmit and / or receive radio signals. Base station 110 and / or terminal 120 may have a single antenna or multiple antennas.

  In the embodiment described above, the components and features of the present invention are combined in a predetermined form. Each component or feature should be considered optional unless stated otherwise. Each component or feature may be implemented in a form that is not combined with other components or features, and some components and / or features may be combined to form an embodiment of the present invention. The order of operations described in the embodiments of the present invention can be changed. Some configurations or features of one embodiment may be included in another embodiment or may replace a corresponding configuration or feature of another embodiment. It is obvious that claims which are not explicitly cited in the claims can be combined to constitute an embodiment, or can be included as new claims by amendment after application.

  In this document, the embodiments of the present invention have been described with a focus on the data transmission / reception relationship between the terminal and the base station. Certain operations that are performed by the base station in this document may be performed by the upper node in some cases. That is, it is apparent that various operations performed for communication with a terminal in a network including a plurality of network nodes including a base station can be performed by the base station or another network node other than the base station. It is. The base station may be replaced with terms such as a fixed station, Node B, eNode B (eNB), access point, and the like. Moreover, a terminal can be substituted for terms such as user equipment (User Equipment; UE), a mobile station (Mobile Station; MS), a mobile subscriber station (Mobile Subscriber Station; MSS).

  Embodiments according to the present invention may be implemented by various means such as hardware, firmware, software, or a combination thereof. When implemented in hardware, one embodiment of the present invention includes one or more application specific integrated circuits (ASICs), digital signal processors (DSPs), and digital signal processors. (Digital Signal Processing Device; DSPD), Field Programmable Gate Array (FPGA), processor, controller, microcontroller, microprocessor, etc.

  In the case of implementation by firmware or software, an embodiment of the present invention may be implemented in the form of a module, procedure, function, or the like that performs the functions or operations described above. The software code may be stored in a memory unit and driven by a processor. The memory unit is provided inside or outside the processor, and can exchange data with the processor by various known means.

  It will be apparent to those skilled in the art that the present invention can be embodied in other specific forms without departing from the characteristics of the present invention. Therefore, the above detailed description should not be construed as limiting in any way, and should be considered exemplary. The scope of the invention should be determined by reasonable interpretation of the appended claims, and all changes that come within the equivalent scope of the invention are included in the scope of the invention.

  The present invention may be applied to a wireless communication system. Specifically, the present invention may be applied to a method for controlling uplink transmission power and an apparatus therefor.

Claims (14)

A method for transmitting a signal by a plurality of component carriers in a communication device in a wireless communication system, comprising:
For each component carrier, the transmission of the one or more channels such that the total transmission power of one or more channels in a subframe does not exceed the individual maximum transmission power configured for the corresponding component carrier Determining power, and
Checking whether the total transmission power on the plurality of component carriers exceeds the total maximum transmission power configured for the communication device, and
When the total transmission power on the plurality of component carriers exceeds the total maximum transmission power configured for the communication device, the transmission power of one or more specific channels on the plurality of component carriers is the plurality The signal transmission method, wherein the reduced total transmission power on the component carrier of the signal is reduced so as not to exceed the total maximum transmission power.   The signal transmission method according to claim 1, further comprising: transmitting a signal via one or more channels in the subframe of the corresponding component carrier based on the acquired transmission power. Information regarding the individual maximum transmission power is received via a broadcast message or a radio resource control (RRC) message;
The signal transmission method according to claim 1, wherein the information regarding the total maximum transmission power is received via the broadcast message or the RRC message.   The signal transmission method according to claim 1, wherein the transmission power of the one or more specific channels is reduced by applying an attenuation coefficient to the corresponding specific channel.   The signal transmission method according to claim 1, wherein the transmission power of the one or more specific channels is reduced by applying the same attenuation coefficient to the one or more specific channels.   The signal transmission method according to claim 1, wherein the one or more channels include at least one of a physical uplink shared channel (PUSCH) and a physical uplink control channel (PUCCH).   The signal transmission method according to claim 6, wherein the one or more specific channels include one or more PUSCHs that do not have uplink control information. A communication device configured to transmit a signal by a plurality of component carriers in a wireless communication system,
A radio frequency (RF) unit;
A processor, the processor comprising:
For each component carrier, the transmission of the one or more channels such that the total transmission power of one or more channels in a subframe does not exceed the individual maximum transmission power configured for the corresponding component carrier Determine the power,
Configured to check whether total transmission power on the plurality of component carriers exceeds a total maximum transmission power configured for the communication device;
When the total transmission power on the plurality of component carriers exceeds the total maximum transmission power configured for the communication device, the transmission power of one or more specific channels on the plurality of component carriers is the plurality The communication device, wherein the reduced total transmission power on the component carrier of the system is reduced so as not to exceed the total maximum transmission power. The processor is
9. The communication device of claim 8, further configured to transmit a signal over one or more channels in the subframe of the corresponding component carrier based on acquired transmission power. Information regarding the individual maximum transmission power is received via a broadcast message or a radio resource control (RRC) message;
The communication apparatus according to claim 8, wherein the information related to the total maximum transmission power is received via the broadcast message or the RRC message.   The communication device according to claim 8, wherein the transmission power of the one or more specific channels is reduced by applying an attenuation coefficient to the corresponding specific channel.   The communication device according to claim 8, wherein the transmission power of the one or more specific channels is reduced by applying the same attenuation coefficient to the one or more specific channels.   The communication device according to claim 8, wherein the one or more channels include at least one of a physical uplink shared channel (PUSCH) and a physical uplink control channel (PUCCH).   The communication apparatus according to claim 13, wherein the one or more specific channels include one or more PUSCHs that do not have uplink control information.

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