KR20130018051A - Apparatus and method for controling uplink transmission power in wireless communication system - Google Patents

Abstract

PURPOSE: A device for controlling up-link transmission power in a wireless communication system, and a method thereof are provided to find a path attenuation estimate between transmitting/receiving points when a terminal performs an up-link transmission for the transmitting/receiving points. CONSTITUTION: A radio resource control(RRC) message processing unit(1011) analyzes a physical downlink shared channel(PDSCH) setting information elements. The RRC message processing unit obtains transmission power for a reference signal. The RRC message processing unit induces energy per resource elements of the reference signal from the transmission power. The RRC message processing unit calculates reference signal received power(RSRP). A path attenuation calculation unit(1012) calculates a path attenuation estimate for transmitting/receiving points from the energy and the RSRP. [Reference numerals] (1005) Terminal RF unit; (1010) Terminal processor; (1011,1071) RRC message processing unit; (1012) Path attenuation calculation unit; (1060) Transceiving point RF unit; (1070) Transceiving point processor; (1072) Path attenuation difference calculation unit; (AA) PDSCH setting information element, setting information about CIS-RS

Description

Apparatus and method for controlling uplink transmission power in a wireless communication system {APPARATUS AND METHOD FOR CONTROLING UPLINK TRANSMISSION POWER IN WIRELESS COMMUNICATION SYSTEM}

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

Multi-cell cooperation has been introduced to increase the performance and communication capacity of wireless communication systems. Multi-cell cooperation is also known as cooperative multiple point transmission and reception (CoMP).

CoMP includes a beam avoidance technique in which neighboring cells cooperate to mitigate interference to a user at a cell boundary, and a joint transmission technique in which neighboring cells cooperate to transmit the same data.

Next-generation wireless communication systems, such as Institute of Electrical and Electronics Engineers (IEEE) 802.16m or 3rd Generation Partnership Project (3GPP) long term evolution (LTE) -Advanced, are located at cell boundaries and are subject to severe interference from adjacent cells. In order to solve this problem, CoMP can be considered.

Various scenarios are possible with this CoMP.

There is an intra-site CoMP with multiple cells around one base station, and a plurality of high-power remote radio heads (RRHs) around one macro cell. There are high-power RRH CoMPs that exist, and low-power RRHs exist around one macro cell, but the cell IDs of the RRHs and the cell IDs of the macro cells are not the same. There is a low power RRH CoMP.

When the terminal performs uplink transmission by selecting one transmission point among a plurality of transmission and reception points operating in CoMP, a criterion for determining the uplink transmission power has not yet been determined.

An object of the present invention is to provide an apparatus and method for controlling uplink transmission power in a wireless communication system.

Another object of the present invention is to provide an apparatus and method for controlling uplink transmission power in a wireless communication system including a terminal capable of receiving signals from a plurality of transmission and reception points.

Another technical problem of the present invention is to provide an apparatus and method for calculating a path attenuation difference between a transmitting and receiving point and a terminal using a sounding reference signal transmitted to a plurality of transmitting and receiving points.

Another technical problem of the present invention is to provide an apparatus and method for calculating a reference signal to a received signal, a path loss estimate, and an uplink transmission power using a reference signal transmitted for feedback of channel state information.

According to an aspect of the present invention, there is provided a control method of uplink transmission power for a terminal performed by a terminal. The control method may further include receiving a physical downlink shared channel (PDSCH) configuration information element indicating a transmission power with respect to a reference signal used for estimation of channel state information, and receiving the reference signal. Receiving from the transmission / reception point, calculating energy per resource element of the reference signal from the transmission power of the reference signal indicated by the PDSCH configuration information element, and filtering at the physical layer level and higher layer level for the reference signal Calculating a reference signal received power (RSRP) by applying a filtering function, and calculating a path loss estimate for the transmission / reception point from the energy per resource element of the reference signal and the reference signal to received power. And an uplink to the transceiver point based on the path loss estimate. And a step of calculating the transmission power is greater.

According to another aspect of the present invention, there is provided a method of controlling uplink transmission power for a terminal performed by a first transmission / reception point. The control method may further include receiving a sounding reference signal (SRS) from a terminal, a first path loss estimate between the terminal and the first transmission / reception point obtained from a result of receiving the SRS by a first transmission / reception point, Calculating a path attenuation difference, which is a difference between a second path attenuation expected value between the terminal and the second transmission / reception point obtained from a result of receiving the SRS by a second transmission / reception point, and a physical downlink shared channel indicating the path attenuation difference Sending a PDSCH configuration information element to the terminal.

According to another aspect of the present invention, a terminal for controlling uplink transmission power for a terminal is provided. The terminal is a physical downlink shared channel (PDSCH) configuration information element indicating a transmission power for a reference signal used for estimation of channel state information, a terminal RF unit for receiving the reference signal from the transmission and reception point, the PDSCH configuration Analyze information elements to obtain transmit power for the reference signal, derive energy per resource element of the reference signal from transmit power for the reference signal, and physical layer level filtering and higher layer level for the reference signal RRC message processing unit for calculating the RSRP by applying the filtering, and path loss calculation unit for calculating the energy loss per resource element of the reference signal and the path loss estimate for the transmission and reception point from the RSRP.

When the terminal performs uplink transmission on a plurality of transmission / reception points using the same physical cell ID, it is possible to know the path loss estimate between each transmission / reception point, thereby enabling efficient uplink power control.

1 is a block diagram showing a wireless communication system to which the present invention is applied.
2 and 3 schematically show the structure of a radio frame to which the present invention is applied.
4 is a flowchart illustrating a method of controlling uplink transmission power according to an embodiment of the present invention.
5 schematically illustrates an example in which a CSI-RS is mapped to a resource element in the case of a normal CP.
6 schematically illustrates an example in which a CSI-RS is mapped to a resource element in the case of an extended CP.
7 is an explanatory diagram illustrating a scenario in which a plurality of transmission and reception points and a terminal communicate with the present invention.
8 is a flowchart illustrating a method of controlling uplink transmission power according to another example of the present invention.
9 is an explanatory diagram illustrating another scenario in which a plurality of transmission and reception points and a terminal communicate with the present invention.
10 is a block diagram illustrating a terminal and a transmission and reception point according to an embodiment of the present invention.

Hereinafter, some embodiments will be described in detail with reference to the accompanying drawings. It should be noted that, in adding reference numerals to the constituent elements of the drawings, the same constituent elements are denoted by the same reference symbols as possible even if they are shown in different drawings. In addition, in describing the embodiments of the present specification, when it is determined that the detailed description of the related well-known configuration or function may obscure the subject matter of the present specification, the detailed description thereof will be omitted.

The present specification describes a communication network, and the work performed in the communication network is performed in the process of controlling the network and transmitting data in a system (for example, a base station) that manages the communication network, or a terminal linked to the network. Work can be done in

1 is a block diagram showing a wireless communication system to which the present invention is applied.

Referring to FIG. 1, a wireless communication system 10 is widely deployed to provide various communication services such as voice, packet data, and the like. The wireless communication system 10 includes at least one base station 11 (BS). Each base station 11 provides a communication service for a particular geographic area or frequency area (generally called a cell) 15a, 15b, 15c. Cells 15a, 15b, and 15c may in turn be divided into a number of regions (called sectors).

A mobile station (MS) 12 may be fixed or mobile and may be a user equipment (UE), a mobile terminal (MT), a user terminal (UT), a subscriber station (SS), a wireless device, (personal digital assistant), a wireless modem, a handheld device, and the like. The base station 11 generally refers to a fixed station communicating with the terminal 12, and includes an evolved-NodeB (eNB), a base transceiver system (BTS), an access point, and a femto eNB. ), A home eNB (HeNB), a relay, a remote radio head (RRH), etc. may be referred to as other terms. Cells 15a, 15b, and 15c should be interpreted in a comprehensive sense indicating some areas covered by the base station 11, and encompass all of the various coverage areas such as megacells, macrocells, microcells, picocells, and femtocells. to be.

Hereinafter, downlink refers to a communication or communication path from the base station 11 to the terminal 12, and uplink refers to a communication or communication path from the terminal 12 to the base station 11. . In the downlink, the transmitter may be part of the base station 11, and the receiver may be part of the terminal 12. In the uplink, the transmitter may be part of the terminal 12, and the receiver may be part of the base station 11. There is no limitation on the multiple access scheme applied to the wireless communication system 10. (CDMA), Time Division Multiple Access (TDMA), Frequency Division Multiple Access (FDMA), Orthogonal Frequency Division Multiple Access (OFDMA), Single Carrier-FDMA , OFDM-CDMA, and the like. These modulation techniques demodulate signals received from multiple users of a communication system to increase the capacity of the communication system. The uplink transmission and the downlink transmission may use a time division duplex (TDD) scheme transmitted using different times or a frequency division duplex (FDD) scheme transmitted using different frequencies.

The wireless communication system 10 may be a Coordinated Multi Point (CoMP) system. The CoMP system refers to a communication system supporting CoMP or a communication system to which CoMP is applied. CoMP is a technique for adjusting or combining signals transmitted or received by multi transmission / reception (Tx / Rx) points. CoMP can increase data rates and provide high quality and high throughput.

The transmission / reception point may be defined as a component carrier or a cell or a base station (macro base station, pico base station, femto base station, etc.), or a remote radio head (RRH). Alternatively, the transmission / reception point may be defined as a set of antenna ports. The transceiver may transmit information about the set of antenna ports to the terminal through radio resource control (RRC) signaling. Therefore, a plurality of transmission points in one cell can be defined as a set of antenna ports. The intersection between the set of antenna ports is always empty.

The base station 11 of the cell 15a, the base station 11 of the cell 15b and the base station 11 of the cell 15c may configure multiple transmission / reception points. For example, the multiple transmit / receive points may be base stations of a macro cell forming a homogeneous network. Further, the multiple transmit / receive points may be base stations of macro cells and base stations of pico cells within macro cells, forming a heterogeneous network. In addition, the multiple transmission / reception points may be a base station of the macro cell and a remote radio unit (RRU) in the macro cell. In addition, the multiple transmission / reception points may be RRHs belonging to the base station of the macro cell and RRHs belonging to the base station of the heterogeneous cell (e.g. pico cell) in the macro cell.

The CoMP system may selectively apply CoMP. A mode in which a CoMP system performs communication using CoMP is called a CoMP mode, and a mode other than the CoMP system is called a normal mode. For example, if CoMP is determined to be advantageous, the CoMP system may operate in CoMP mode. On the other hand, if CoMP is determined to be disadvantageous, the CoMP system may operate in a normal mode.

The terminal 12 may be a CoMP terminal. The CoMP terminal is a component of the CoMP system and performs communication with a CoMP cooperating set. Like the CoMP system, the CoMP terminal may operate in the CoMP mode or in the normal mode. The CoMP cooperative set is a set of transmit / receive points that directly or indirectly participate in data transmission on a time-frequency resource for a CoMP terminal. For example, the base station 11 of the cell 15a, the base station 11 of the cell 15b, and the base station 11 of the cell 15c may form a CoMP cooperative set. Also, the transmit and receive points do not necessarily have to provide the same coverage. For example, base station 11 of cell 15a may be a base station providing a macro cell, and base station 11 of cell 15b may be an RRH.

Participating directly in data transmission or reception means that the transmitting and receiving points actually transmit data to or receive data from the CoMP terminal in the corresponding time-frequency resource. Indirect participation in data transmission or reception means that the transmit / receive points do not actually transmit or receive data to or from the CoMP terminal in the corresponding time-frequency resource, but contribute to making decisions about user scheduling / beamforming. .

The CoMP terminal may simultaneously receive signals from the CoMP cooperative set or transmit signals simultaneously to the CoMP cooperative set. At this time, the CoMP system minimizes the interference effect between the CoMP cooperation sets in consideration of the channel environment of each cell constituting the CoMP cooperation set.

When the CoMP terminal performs uplink transmission, a channel environment is formed between the reception point and the CoMP terminal. For example, the channel environment is a set of parameters that affect scheduling for a CoMP terminal, such as a frequency bandwidth allocated to the CoMP terminal and a downlink pathloss (PL). The channel environment is formed individually for each receiving point. This means that the channel environment may be different for each receiving point. If the channel environment is different for each receiving point, the CoMP terminal should set uplink transmission power differently for each receiving point. Therefore, the CoMP terminal needs to know how the channel environment is different for each receiving point.

When operating a CoMP system, various scenarios are possible. The first scenario is an intra-site CoMP scenario in which a plurality of cells exist around one base station. The second scenario is a high-power CoMP scenario in which a plurality of high-power RRHs exist around one macro cell. The third scenario is a CoMP scenario in which a low-power RRH exists around one macro cell but the physical cell ID of the RRH and the physical cell ID of the macro cell are not the same. The fourth scenario is a CoMP scenario in which a low-power RRH exists around one macro cell, but the physical cell ID of the RRH and the physical cell ID of the macro cell are the same.

If the plurality of receiving points all have different physical cell IDs as in the third scenario, the CoMP terminal may distinguish each receiving point and may distinguish different channel environments for each receiving point. However, when the physical cell IDs of the transmission and reception points are the same as in the fourth scenario, the CoMP terminal should distinguish a plurality of reception points and accordingly different channel environments.

CoMP's category includes Joint Processing (JP) and Coordinated Scheduling / Beamforming (CS / CB). It is also possible to mix CSCB with.

In the case of JP, data for the terminal is available at at least one transmit / receive point of the CoMP cooperative set in some time-frequency resource. JP includes Joint Transmission (JT, hereinafter referred to as 'JT') and Dynamic Point Selection (DPS, hereinafter referred to as 'DPS').

JT refers to data transmission being performed together from multiple transmission / reception points belonging to a CoMP cooperative set to one terminal or a plurality of terminals in time-frequency resources. In the case of JT, multiple cells (multi-transmitting / receiving points) transmitting data to one terminal perform transmission using the same time / frequency resource.

In the case of DPS, data transmission is performed from one transmission / reception point of a CoMP cooperative set in time-frequency resources. The transmission and reception point may be changed for each subframe in consideration of interference, and includes a change over a resource block pair within a subframe. The data to be transmitted is simultaneously available at multiple transmit and receive points. DPS includes Dynamic Cell Selection (DCS).

In the case of CS, data is transmitted from one transmit / receive point in a CoMP cooperation set for time-frequency resources, and user scheduling is determined by coordination between the points of that CoMP cooperation set. At this time, the transmission / reception point used is dynamically or semi-statically selected. In the case of dynamically selecting a transmit / receive point, transmission is performed only at one transmit / receive point at a time, which may change from subframe to subframe, and includes changing across resource block pairs within a subframe. In the case of semi-statically selecting points, only one transmission / reception point is transmitted at a time, and the transmission / reception point can be changed only in a semi-static manner.

In the case of CB, it is also determined by cooperation between the transmitting and receiving points of the CoMP cooperation set. By the CB (Coordinated Beamforming) it is possible to avoid the interference occurring between the terminals of the neighbor cell.

As mentioned above, it is also possible to mix JP and CS / CB. For example, some transmit / receive points in the CoMP cooperative set may transmit data to the target terminal according to JP, and other transmit / receive points in the CoMP cooperative set may perform CS / CB.

On the other hand, for the DCS, the channel quality indicator (CQI) value may be derived by a zero power CSI-RS configuration.

The transmission and reception point to which the present invention is applied may include a base station, a cell, or an RRH. That is, the base station or the RRH may be a transmission / reception point. Meanwhile, the plurality of base stations may be multiple transmission / reception points, and the plurality of RRHs may be multiple transmission / reception points. Of course, the operation of all base stations or RRH described in the present invention can be equally applied to other types of transmission and reception points.

The layers of the radio interface protocol between the terminal and the base station are based on the lower three layers of the Open System Interconnection (OSI) model, which is well known in the communication system. It may be divided into a second layer L2 and a third layer L3. Among them, the physical layer belonging to the first layer provides an information transfer service using a physical channel.

There are several physical channels used in the physical layer. The physical downlink control channel (PDCCH) includes a resource allocation and transmission format of a downlink shared channel (DL-SCH), a resource of an uplink shared channel (UL-SCH) Resource allocation of an upper layer control message such as allocation information, a random access response transmitted on a physical downlink shared channel (PDSCH), transmission power control for individual terminals in an arbitrary terminal group : TPC) commands, and so on. A plurality of PDCCHs can be transmitted in the control domain, and the UE can monitor a plurality of PDCCHs.

The control information of the physical layer mapped to the PDCCH is referred to as downlink control information (DCI). That is, the DCI is transmitted on the PDCCH. The DCI may include an uplink or downlink resource allocation field, an uplink transmission power control command field, a control field for paging, a control field for indicating a random access response (RA response), and the like.

DCI has different uses according to its format, and fields defined in DCI are also different. Table 1 shows DCIs according to various formats.

DCI format Explanation 0 Used for scheduling of PUSCH (Uplink Grant) One Used for scheduling one PDSCH codeword in one cell 1A Used for simple scheduling of one PDSCH codeword in one cell and in a random access procedure initiated by a PDCCH command. 1B Used for simple scheduling of one PDSCH codeword in one cell using precoding information 1C Used for brief scheduling of one PDSCH codeword and notification of MCCH changes 1D Used for simple scheduling of one PDSCH codeword in one cell, including precoding and power offset information. 2 Used for PDSCH scheduling for terminals configured in spatial multiplexing mode. 2A Used for PDSCH scheduling of UEs configured in CDD mode with large delay. 2B Used in transmission mode 8 (dual layer transmission) 2C Used in transmission mode 9 (multi-layer transmission) 3 Used to transmit TPC commands for PUCCH and PUSCH with power adjustment of 2 bits 3A Used for transmission of TPC commands for PUCCH and PUSCH with single bit power adjustment. 4 Used for scheduling of PUSCH (uplink grant). In particular, it is used for PUSCH scheduling for terminals configured in the spatial multiplexing mode.

Referring to Table 1, DCI format 0 is uplink scheduling information, format 1 for scheduling one PDSCH codeword, format 1A for compact scheduling of one PDSCH codeword, and very simple A format 2 for scheduling, a format 2 for PDSCH scheduling in a closed-loop spatial multiplexing mode, a format 2A for PDSCH scheduling in an open-loop spatial multiplexing mode, an uplink channel And formats 3 and 3A for the transmission of TPC (Transmission Power Control) commands.

Each field of the DCI is sequentially mapped to _n information bits a ₀ through a _{n -1} . For example, if the DCI is mapped to a total of 44 bits of information bits, each DCI field is sequentially mapped to a ₀ to a ₄₃ . DCI formats 0, 1A, 3, and 3A may all have the same payload size. DCI format 0 may be called an uplink grant.

2 and 3 schematically show the structure of a radio frame to which the present invention is applied.

2 and 3, a radio frame includes 10 subframes. One subframe includes two slots. The time (length) of transmitting one subframe is called a transmission time interval (TTI). Referring to FIG. 1, for example, one subframe may have a length of 1 ms, and one slot may have a length of 0.5 ms.

One slot may include a plurality of symbols in the time domain. For example, in a wireless system using orthogonal frequency division multiple access (OFDMA) in downlink (DL), the symbol may be an orthogonal frequency division multiplexing (OFDM) symbol. Meanwhile, the representation of the symbol period in the time domain is not limited by the multiple access scheme or the name. For example, the plurality of symbols in the time domain may be a Single Carrier-Frequency Division Multiple Access (SC-FDMA) symbol, a symbol interval, or the like in addition to the OFDM symbol.

The number of OFDM symbols included in one slot may vary depending on the length of a cyclic prefix (CP). For example, in case of a normal CP, one slot may include 7 OFDM symbols, and in case of an extended CP, one slot may include 6 OFDM symbols.

One slot includes a plurality of subcarriers in the frequency domain and seven OFDM symbols in the time domain. A resource block (RB) is a resource allocation unit. If a resource block includes 12 subcarriers in the frequency domain, one resource block may include 7 × 12 resource elements (REs).

The resource element represents the smallest frequency-time unit to which the modulation symbol of the data channel or the modulation symbol of the control channel is mapped. If there are M subcarriers on one OFDM symbol, and one slot includes N OFDM symbols, one slot includes MxN resource elements.

In a wireless communication system, it is necessary to estimate an uplink channel or a downlink channel for data transmission / reception, system synchronization acquisition, channel information feedback, and the like. A process of compensating for a distortion of a signal caused by a sudden change in channel environment and restoring a transmission signal is called channel estimation. It is also necessary to measure the channel state of the cell or other cell to which the terminal belongs. In general, a reference signal (RS) that is known to a terminal and a transceiver is mutually used for channel estimation or channel state measurement.

)를 추정할 수 있다.Since the UE knows the information of the reference signal, the terminal can estimate the channel based on the received reference signal and compensate the channel value to accurately obtain the data sent from the transmitting and receiving point. If p is the reference signal transmitted from the transmitter / receiver, h is channel information experienced by the reference signal during transmission, n is thermal noise generated at the terminal, and y is the signal received at the terminal, it can be expressed as y = h · p + n. have. In this case, since the reference signal p is already known by the terminal, when the LS (Least Square) method is used, channel information (

) Can be estimated.

는

값에 의존하게 되므로, 정확한 h값의 추정을 위해서는

이 0에 수렴시킬 필요가 있다. 많은 개수의 참조 신호를 이용함으로써

의 영향을 최소화하여 채널을 추정할 수 있다. Here, the channel estimation value estimated using the reference signal p

The

Value, so for accurate estimation of the h value

It is necessary to converge to zero. By using a large number of reference signals

It is possible to estimate the channel by minimizing the influence of the channel.

The reference signal may be allocated to all subcarriers or between data subcarriers transmitting data. In a scheme in which a reference signal is allocated to all subcarriers, a signal of a specific transmission timing is made only of a reference signal such as a preamble in order to obtain a gain of channel estimation performance. According to a method in which a reference signal is allocated between data subcarriers, the amount of data to be transmitted can be increased.

Reference signals are generally transmitted in sequence. The reference signal sequence may be any sequence without any particular limitation. The reference signal sequence may use a PSK-based computer generated sequence (PSK) -based computer. Examples of PSKs include Binary Phase Shift Keying (BPSK) and Quadrature Phase Shift Keying (QPSK). Alternatively, the reference signal sequence may use a Constant Amplitude Zero Auto-Correlation (CAZAC) sequence. Examples of the CAZAC sequence include a ZC-based sequence, a ZC sequence with a cyclic extension, a truncation ZC sequence (ZC sequence with truncation), and the like . Alternatively, the reference signal sequence may use a PN (pseudo-random) sequence. Examples of PN sequences include m-sequences, computer generated sequences, Gold sequences, and Kasami sequences. Also, the reference signal sequence may use a cyclically shifted sequence.

The downlink reference signal includes a cell-specific RS (CRS), an MBSFN reference signal, a UE-specific RS, a positioning reference signal (PRS), and channel state information (CSI). And a reference signal (CSI-RS).

In a multi-antenna system, resource elements used for reference signals of one antenna are not used for reference signals of other antennas. To avoid interference between antennas. For example, only one reference signal may be transmitted per antenna.

The CRS is a reference signal transmitted to all terminals in a cell and used for channel estimation. The CRS may be transmitted in all downlink subframes in a cell supporting PDSCH transmission.

The UE-specific reference signal is a reference signal received by a specific terminal or a specific terminal group in a cell, and is mainly used for data demodulation of a specific terminal or a specific terminal group and may be called a demodulation reference signal (DMRS).

The MBSFN reference signal is a reference signal for providing a multimedia broadcast multicast service (MBMS) and may be transmitted in a subframe allocated for MBSFN transmission. The MBSFN reference signal may be defined only in the extended CP structure.

The PRS may be used for location measurement of the terminal. The PRS may be transmitted only through resource blocks in a downlink subframe allocated for PRS transmission.

CSI-RS may be used for estimation of channel state information. The CSI-RS is arranged in the frequency domain or the time domain. Channel quality indicator (CQI), precoding matrix indicator (PMI) and rank indicator (RI) rank information such as channel quality indicator (CQI), if necessary through the estimation of the channel state using the CSI-RS As reported from the terminal. The CSI-RS may be transmitted on one or more antenna ports.

4 is a flowchart illustrating a method of controlling uplink transmission power according to an embodiment of the present invention.

Referring to FIG. 4, the terminal receives configuration information about a PDSCH configuration information element and / or CSI-RS from a transmission / reception point (S400). The PDSCH configuration information element may be information included in an RRC message, for example, a system information block (SIB) 2 used to specify a common or terminal specific PDSCH configuration, and an example thereof is shown in the following table.

- ASN1START

PDSCH-ConfigCommon :: = SEQUENCE {
referenceSignalPower INTEGER (-60..50),
pb INTEGER (0..3)
}

PDSCH-ConfigDedicated :: = SEQUENCE {
pa ENUMERATED {
dB-6, dB-4dot77, dB-3, dB-1dot77,
dB0, dB1, dB2, dB3}
}

-ASN1STOP

Referring to Table 2, the PDSCH configuration information element includes a PDSCH-ConfigCommon field and a PDSCH-ConfigDedicated field. p-a is a terminal specific parameter and p-b is a cell specific parameter. referenceSignalPower indicates a downlink reference signal transmission power and is provided in units of dBm. From this, energy per resource element (EPRE) of the downlink reference signal may be derived.

The downlink reference signal transmit power is defined as a linear average of power contributions of all resource elements carrying a CRS or CSI-RS within an operating system bandwidth. In the case of CoMP mode, it is assumed that the EPREs for all transmission and reception points are the same.

Meanwhile, in the case of CoMP mode, EPREs related to the base station and the RRH may be set differently. This is shown in the following table as another example of the PDSCH configuration information element.

- ASN1START

PDSCH-ConfigCommon :: = SEQUENCE {
referenceSignalPower _eNB INTEGER (-60..50),
referenceSignalPower _RRH INTEGER (-60..50),
pb INTEGER (0..3)
}

PDSCH-ConfigDedicated :: = SEQUENCE {
pa ENUMERATED {
dB-6, dB-4dot77, dB-3, dB-1dot77,
dB0, dB1, dB2, dB3}
}

-ASN1STOP

Referring to Table 3, an energy per resource element (EPRE) value different from a base station eNB and an RRH is set in the PDSCH-ConfigCommon field. Here, the EPRE values between the eNB and the RRH are different, but the EPRE values are the same between the RRHs.

Alternatively, EPREs for each transmission and reception point may be set differently. This is shown in the following table as another example of the PDSCH configuration information element.

- ASN1START

PDSCH-ConfigCommon :: = SEQUENCE {
referenceSignalPower _eNB INTEGER (-60..50),
referenceSignalPower _RRH1 INTEGER (-60..50),
referenceSignalPower _RRH2 INTEGER (-60..50),
pb INTEGER (0..3)
}

PDSCH-ConfigDedicated :: = SEQUENCE {
pa ENUMERATED {
dB-6, dB-4dot77, dB-3, dB-1dot77,
dB0, dB1, dB2, dB3}
}

-ASN1STOP

Referring to Table 4, an energy per resource element (EPRE) value different from a base station eNB, RRH1, and RRH2 is set in the PDSCH-ConfigCommon field.

The configuration information (CSI-RS-Config) related to the CSI-RS is an information element used to specify the CSI-RS configuration and is individually transmitted to each terminal using the CSI-RS. Setting information about the CSI-RS may be defined as shown in the table below.

- ASN1START

CSI-RS-Config :: = SEQUENCE {
csi-RS CHOICE {
release NULL,
setup SEQUENCE {
antennaPortsCount ENUMERATED {an1, an2, an4, an8},
resourceConfig INTEGER (0..31),
subframeConfig INTEGER (0..154),
pC-eNB INTEGER (-8..15)
pC-RRH INTEGER (-8..15)
}
} OPTIONAL, - Need ON
zeroTxPowerCSI-RS CHOICE {
release NULL,
setup SEQUENCE {
zeroTxPowerResourceConfigList BIT STRING (SIZE (16)),
zeroTxPowerSubframeConfig INTEGER (0..154)
}
} OPTIONAL-Need ON
}

-ASN1STOP

Referring to Table 5, the number of antenna ports (antennaPortsCount) represents the number of antenna ports used for CSI-RS transmission, and an1 corresponds to one antenna port, an2 corresponds to two antenna ports, and so on. p-C is an estimated ratio of energy per PDSCH (EPRE) to energy per CSI-RS resource element (EPRE) when the UE induces CSI feedback. p-C has a value in the range of [-8, 15] dB and increases and decreases in 1 dB increments. p-C-eNB is a case where the transceiver point is a base station, and is a p-C for the CSI-RS transmitted by the base station. p-C-RRH is a case where the transmission / reception point is RRH, and is p-C for CSI-RS transmitted by RRH. The energy per PDSCH resource element is equal to the energy per resource element (EPRE) of the downlink reference signal derived by referenceSignalPower in Table 2 or 3 above.

The terminal receives the CSI-RS mapped to the resource element for any serving cell C from the transmission and reception point (S405). 5 schematically illustrates an example in which a CSI-RS is mapped to a resource element in the case of a normal CP. The mapping of CSI-RS illustrated in FIG. 5 is an example of CSI configuration 0 for a normal CP, where R _p represents a resource element used for CSI-RS transmission at an antenna port P. FIG. 6 schematically illustrates an example in which a CSI-RS is mapped to a resource element in the case of an extended CP. The mapping of CSI-RS shown in FIG. 6 relates to CSI configuration 0 for extended CP. 5 and 6, the CSI-RS may be mapped to resource elements in a predetermined pattern according to the antenna port transmitted.

Referring back to FIG. 4, the terminal derives a downlink reference signal, that is, energy per resource element (EPRE) of the CSI-RS from referenceSignalPower in the PDSCH-ConfigCommon field, or energy per resource element of the CSI-RS from the pC value ( EPRE) is derived and a reference signal received power (RSRP) is calculated (S410). The terminal may select whether to use the CRS or the CSI-RS as the basis for the RSRP measurement or the calculation of the path loss estimate. For example, the terminal may select one of the CRS and the CSI-RS as a criterion for the RSRP measurement or the calculation of the path loss estimate based on the priority. For example, if the DPS is applied, the CSI-RS may have a priority over the CRS, and if the DPS is not applied, the CRS may have a priority over the CSI-RS.

RSRP is defined as the linear average of the power contributions of all resource elements carrying CRS or CSI-RS within the considered measurement frequency bandwidth. Here, CRS is defined for antenna ports 0, 1, 2, and 3 and CSI-RS is defined for antenna ports 15 to 22. Therefore, R ₀ means CRS present in antenna port 0 and R ₁₅ means CSI-RS present in antenna port 15 (see FIGS. 5 and 6).

RSRP may be specifically obtained by the following procedure. The terminal acquires measurement samples by filtering at the physical layer level, and filters the measurement samples at a higher layer level as in the following equation.

In Equation 2, M _n is the most recent measurement sample, F _n is the measurement to be reported by the measurement report, F _{n -1} is the measurement reported by the previous measurement report, and a is 1/2 ^{where (k / 4)} k is the filter coefficient used for filtering.

The measurement sample is a measurement value in units of subframes and is a variable required to derive RSRP or RSRQ (Reference Signal Received Quality). Alternatively, the measurement sample means a measurement value for the subframe selected by the measurement rule defined in the wireless system among the measurement values for all the subframes received by the terminal. The measurement sample may be obtained at the physical layer of the terminal, and filtering may be performed at an upper layer of the terminal, for example, a radio resource control (RRC) layer.

The measurement sample may be acquired continuously every subframe, but may be obtained discontinuously as long as the capacity of the terminal or a condition defined by the system is satisfied. That is, another measurement sample may be obtained after a predetermined interval of time after one measurement sample is obtained. In this case, measurement samples are not obtained for some subframes. The spacing section may be periodic or aperiodic.

Meanwhile, RSRQ may be defined as a ratio between RSRP and Received Signal Strength Indicator (RSSI) as shown in Equation (3).

Here, N is the number of resource elements of the carrier RSSI measurement bandwidth of the radio access network. In Equation 3, the numerator and denominator are measured for the same set of resource blocks. RSSI includes a linear average of the total received power. The total received power is observed only within an OFDM symbol containing reference symbols within the measurement bandwidth and is a value obtained over N resource blocks. If the UE receives signaling indicating RSRQ measurement at a higher layer, RSSI measurement is performed for all OFDM symbols in the subframe in which the RSRQ measurement is indicated.

The terminal calculates a pathloss (PL) estimate between the transmitting and receiving point and the terminal from the EPRE value of the CSI-RS and the RSRP (S415). The path loss estimate can be obtained by the following equation.

Referring to Equation 4, PL _C is an estimated downlink path loss for the serving cell C calculated by the UE in dB units. referenceSignalPower is a value provided from the upper layer and is the EPRE value of the downlink reference signal in dBm. The link determination between referenceSignalPower and RSRP used for calculating the serving cell C and PL _C selected as the reference serving cell is configured by pathlossReferenceLinking, which is a higher layer parameter. The reference serving cell configured by the path loss reference link information includes a primary serving cell (PCell) or an uplink component carrier (UL CC) and a secondary serving cell (corresponding) in which SIB2 is established. It may be a downlink SCC of a serving cell (SCell).

As in the fourth scenario, when a plurality of transmission / reception points transmit CRS using the same physical cell ID in the CoMP cooperative set, the CRS, which is a reference for RSRP measurement, is the same at the plurality of transmission / reception points. Therefore, the terminal cannot distinguish the path loss estimate for each transmission / reception point based on the CRS. However, according to the definition of the path loss prediction value, RSRP should be measured separately for each transmission / reception point. In particular, since the DPS is supported in the CoMP mode, the UE can accurately control the uplink transmission power by knowing the path loss estimate for each transmission / reception point. For example, in the CoMP system as shown in FIG. 7, it is assumed that the path loss estimate is PL1 at the transmission / reception point 1 and the path reduction estimate is PL2 at the transmission / reception point 2. The CoMP terminal may dynamically perform uplink transmission for either or both of the transmission point 1 and the transmission point 2 or both based on the DPS. In this case, if PL1 and PL2 are not distinguished, the terminal may incorrectly recognize the path loss estimate for the transceiver point 2 as PL1, and assign an PL1 to Equation 5 or Equation 6 to calculate an uplink transmission power. have.

On the other hand, when using the CSI-RS as a reference for RSRP measurement as in steps S410 and S415, since the path attenuation value is distinguished for each transmission / reception point, the terminal may calculate the accurate uplink transmission power for each transmission / reception point.

As described above, in the situation where the UE can derive the path loss prediction values separated from each other at each transmission / reception point, it is necessary to determine which path reduction prediction value is used to derive the uplink transmission power. As an example, the terminal may select one transmission / reception point among multiple transmission / reception points as a target for uplink transmission according to the DPS operation. In this case, the terminal applies the path loss estimate calculated based on the signal received from the selected transmission and reception point to derive uplink transmission power. That is, the terminal calculates a path loss estimate for the transmission and reception point for selecting the uplink radio link on the basis of the determination of the terminal itself, without additional signaling from the transmission and reception point, especially the base station and applies it to derivation of the uplink transmission power.

As another example, the terminal uses the path loss estimate for the transceiver point set as the first serving cell to derive uplink transmit power for the transceiver point selected according to the DPS operation. This corresponds to a case in which the UE cannot select one transmission / reception point as a target for uplink transmission according to the DPS operation in the CoMP mode. Therefore, the terminal adjusts the path loss estimate of the transceiver point selected by the DPS operation from the base station through TPC signaling. The TPC signaling may be performed through a DCI format 3 / 3A signal.

The terminal calculates uplink transmission power from the path loss estimate for the serving cell C (S420). The uplink physical channel includes a physical uplink shared channel (PUSCH) and a physical uplink control channel (PUCCH). The uplink transmission power may be controlled differently according to the uplink physical channel to transmit.

In the case of the PUSCH, the uplink transmission power P _{PUSCH , C} (i) is scaled by the number of antennas for which at least one PUSCH transmission is performed and the number of antennas configured according to a transmission scheme. C is a serving cell to perform uplink transmission, and i is a number of a subframe in which uplink transmission is performed with power P _{PUSCH , C} (i). The adjusted total uplink transmission power is equally divided and allocated to the antennas performing at least one PUSCH transmission.

PUSCH transmission power is further divided into i) a case in which PUSCH and PUCCH are not transmitted simultaneously for any serving cell C and ii) a case in which both PUSCH and PUCCH are simultaneously transmitted.

In case of i), the UE calculates uplink transmit power P _{PUSCH , C} (i) defined by the following equation in subframe i for serving cell C.

In case of ii), the UE calculates uplink transmit power P _{PUSCH , C} (i) defined by the following equation in subframe i for serving cell C.

는 dB값을 선형으로 변환한 값이다. 한편,

는 P_PUCCH(i)를 선형으로 변환한 값이다. M_{PUSCH ,C}(i)는 서빙셀 C에 대한 서브프레임 i에서 PUSCH가 할당된 자원의 대역폭을 자원블록의 개수로 표현한 값이다. Referring to Equations 5 and 6, P _{CMAX , C} (i) is the maximum terminal outgoing power configured for the serving cell C,

Is the linear value of dB. Meanwhile,

Is a value obtained by linearly converting P _PUCCH (i). M _{PUSCH , C} (i) is a value representing the bandwidth of a resource allocated with a PUSCH in subframe i for the serving cell C in terms of the number of resource blocks.

P _{0 _ PUSCH , C} (i) is the sum of P _{0 _ NOMINAL _ PUSCH , C} (j) and P _{0 _ UE _ PUSCH , C} (j) for the serving cell C. For example, in case of semi-persistent grand PUSCH (re) transmission, it has a value of j = 0. On the other hand, in case of dynamic scheduled grand PUSCH (re) transmission, j = 1. If j = 0 or 1, it is signaled by a higher layer. And, in case of random access response grant PUSCH (re) transmission, j = 2. In addition, for random access response grant PUSCH (re) transmission, P _{0 _ UE _ PUSCH , C} (2) = 0 and P _{0 _ NOMINAL _ PUSCH , C} (2) = P _{0 _ PRE} + Δ _{PREAMBLE_Msg3} , where the parameter preambleInitialReceivedTargetPower (P _{0 _ PRE} ) and Δ _{PREAMBLE_Msg3} are signaled from higher layers.

If j = 0 or 1, one of the values of α _C ∈ {0, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1} may be selected by the 3-bit parameter provided in the upper layer. When j = 2, α _C (j) = 1.

이다. 여기서, C는 코드블록의 개수이며, K_r은 코드블록의 크기이며, O_CQI는 CRC 비트수를 포함한 CQI/PMI 비트 개수이며, N_RE는 결정된 자원요소들의 개수이다. 즉, NRE=M_sc ^{PUSCH - initial}·N_symb ^{PUSCH - initial}이다. Δ _{TF , C} (i) = 10log ₁₀ ((2 ^{BPRE · Ks} −1) · β ^PUSCH _offset ), which is a parameter for reflecting the influence of the modulation and coding scheme (MCS). Here, K _S is a parameter provided as deltaMCS-Enabled in the upper layer for each serving cell C. In transmission mode 2, which is a mode for transmit diversity, K _S = 0. If only control information is transmitted through the PUSCH without UL-SCH data, BPRE = O _CQI / N _RE . In all other cases, BPRE =

to be. Here, C is the number of code blocks, K _r is the size of the code block, O _CQI is the number of CQI / PMI bits including the number of CRC bits, N _RE is the number of determined resource elements. That is, NRE = M _sc ^{PUSCH - initialN} _symb ^{PUSCH - initial} .

If only control information is transmitted without UL-SCH data through the PUSCH, β ^PUSCH _offset = β ^CQI _offset is set. Otherwise, it is always set to 1.

δ _{PUSCH , C} is a correction value. In addition, it is determined by referring to a TPC command present in DCI format 0 or 4 for serving cell c or a TPC command in DCI format 3 / 3A that is encoded and transmitted jointly with other terminals. In DCI format 3 / 3A, cyclic cyclic redundancy check (CRC) parity bits are scrambled with TPC-PUSCH-RNTI, so only terminals assigned the RNTI value can be checked. In this case, when an arbitrary terminal is configured with a plurality of serving cells, a different TPC-PUSCH-RNTI value may be allocated to each serving cell to distinguish each serving cell. Alternatively, a different TPC-PUSCH-RNTI value may be assigned to each transmit / receive point to distinguish between the transmit and receive points.

f _c (i) represents a PUSCH power control adjustment state for the current serving cell C, and is defined as follows.

는 서브프레임 #i-K_PUSCH에서 서브프레임에서 전송되었었던 PDCCH 내의 DCI 포맷 0/4 또는 3/3A 내에 있는 TPC 명령이고, f_c(0)는 누적 리셋 후 첫번째 값이다. K_PUSCH 값과 관련하여, FDD인 경우 K_PUSCH는 4이고, TDD 설정이 1 내지 6인 경우 K_PUSCH 값은 다음 표와 같다.Equation (7) is the case in which accumulation is activated by a higher layer for serving cell C or when DCI format 0 scrambled by a temporary C (Cell) -RNTI is included in the PDCCH. . here,

Is a TPC command in DCI format 0/4 or 3 / 3A in the PDCCH that was transmitted in the subframe in subframe #iK _PUSCH , and f _c (0) is the first value after the cumulative reset. In relation to the K _PUSCH value, in case of FDD, K _PUSCH is 4, and when TDD is 1 to 6, K _PUSCH values are shown in the following table.

TDD UL / DL Settings Subframe number i 0 One 2 3 4 5 6 7 8 9 0 - - 6 7 4 - - 6 7 4 One - - 6 4 - - - 6 4 - 2 - - 4 - - - - 4 - - 3 - - 4 4 4 - - - - - 4 - - 4 4 - - - - - - 5 - - 4 - - - - - - - 6 - - 7 7 5 - - 7 7 -

Referring to Table 6, the portion marked with '-' is a DL subframe, and the portion indicated with a number is an UL subframe.

In case of TDD configuration # 0, if a PDCCH for scheduling PUSCH transmission exists in subframe # 2 or subframe # 7, a LSB (Least Significant Bit) value of a 2-bit UL index in DCI format 0/4 in the PDCCH If is set to '1' K _PUSCH is 7. K _PUSCH values in all other cases are shown in Table 6 above. The 2-bit UL index is used to schedule UL subframes that cannot be scheduled in Table 6.

On the other hand, the UE attempts to decode the PDCCH in all subframes except when the DRX (discontinous reception) operation. This includes the PDCCH of DCI format 0/4 for the C-RNTI of the UE or DCI format 0 for the SPS C-RNTI and DCI format 3 / 3A for the TPC-PUSCH-RNTI of the UE.

If DCI format 0/4 and DCI format 3 / 3A for the serving cell C are simultaneously received in the same subframe, the UE should use only δ _{PUSCH , C} of DCI format 0/4.

For a certain subframe _, δ _{PUSCH , C} is 0dB when there is no TPC command for the serving cell C, during DRX operation, or when the corresponding subframe is an UL subframe of TDD. When the TPC command fields in DCI format 0/3/4 are 0, 1, 2, and 3, respectively, the accumulated δ _{PUSCH and C} dB values are -1, 0, 1, 3, respectively. If the PDCCH of DCI format 0 is approved as the SPS activation or release PDCCH, δ _{PUSCH , C} is 0dB. When the TPC command fields in DCI format 3A are 0 and 1, respectively, the accumulated δ _{PUSCH and C} dB values are −1 and 1, respectively.

If the UE reaches P _{CMAX ,} C for the serving cell C, the positive TPC command will not accumulate. If the terminal reaches the minimum power, negative TPC commands will not accumulate.

If the value of P _{0 _ UE _ PUSCH ,} C for the serving cell C is changed by the higher layer or the terminal receives the random access response message for the main serving cell, the terminal will reset the accumulation.

In Equation 7, when accumulation is deactivated by the higher layer with respect to the serving cell C, f _c (i) is as follows.

는 서브프레임 #i-K_PUSCH에서 서빙셀 C에 대한 PDCCH내의 DCI 포맷 0/4을 통해 전송된다. K_PUSCH 값은 FDD의 경우 4이고, TDD UL/DL 설정 #1 내지 #6에서 상기 표 6과 같이 주어진다.here,

Is transmitted through DCI format 0/4 in PDCCH for serving cell C in subframe #iK _PUSCH . The K _PUSCH value is 4 for FDD and is given as shown in Table 6 in TDD UL / DL configuration # 1 to # 6.

In TDD UL / DL configuration # 0, if PUSCH transmission in subframe # 2 or subframe # 7 is scheduled and the LSB of the 2-bit UL index of DCI format 0/4 in the PDCCH is set to '1', K _PUSCH is 7. Otherwise, K _PUSCH is given as shown in Table 6 above.

If DCI format 0/4 in PDCCH for serving cell C is not decoded, DRX occurs, or subframe #i is not an UL subframe in TDD, f _c (i) is equal to f _c (i-1). same.

If P _{0 _ UE _ PUSCH , C} value is changed by higher layer and serving cell C is main serving cell, or P _{0 _ UE _ PUSCH , C} value is received by higher layer and serving cell C is secondary serving cell F _c (0) is zero. In other cases, if the serving cell C is the main serving cell, f _c (0) = ΔP _rampup + δ _msg2 , where δ _msg2 is a TPC command indicated by a random access response. The TPC command is present in 3 bits in the DCI in the PDCCH for indicating the location of the PDSCH including the RAR MAC CE. In addition, ΔP _rampup is provided by the upper layer and is for the total power ramp-up from the first preamble to the last preamble.

The terminal transmits the PUSCH to the reception point at the calculated uplink transmission power (S425).

8 is a flowchart illustrating a method of controlling uplink transmission power according to another example of the present invention. 8 is described based on FIG. 9 illustrating signaling of a CoMP system.

Referring to FIG. 8, the base station eNB transmits the CRS to the terminal (S800). Here, the base station is one of the transmission and reception points in the CoMP system, and is connected to the other transmission and reception point RRH. The RRH may or may not transmit CRS. If the RRH transmits the CRS, it transmits a CRS that can be identified by the same physical cell ID (PID) value as the base station.

The terminal calculates a transmission power of a sounding reference signal (SRS) by the following equation based on the CRS (S805).

Referring to Equation 9, P _{SRS , C} (i) is a transmission power of the terminal for the sounding reference signal transmitted in subframe i for the serving cell C, and is in dBm unit.

P _{CMAX , C} (i) represents the maximum transmission power configured in the terminal defined in subframe i for the serving cell C. P _{SRS _ OFFSET , C} (m) is a semi-static 4-bit parameter configured by a higher layer, where m = 0 or m = 1. For type 0 periodic SRS transmission, m = 0 and for type 1 aperiodic SRS transmission, m = 1. When K _S = 1.25, the values of P _{SRS _ OFFSET , C} (m) are given in 1 dB steps in the range of [-3,12] dB, and when K _S = 0, P _{SRS _ OFFSET , C} (m ) Are given in 1.5 dB steps in the range [-10.5,12] dB.

M _{SRS , C} is a bandwidth of SRS transmission in subframe i for serving cell C and is expressed in units of resource blocks. f _c (i) represents a PUSCH power control adjustment state for the current serving cell C, and is defined as in Equation 7 or Equation 8. P _{0 _ PUSCH , C} (j) and α _C (j) are as defined in Equations 7 and 8 above.

The terminal transmits the SRS to the transmission and reception points with the calculated SRS transmission power (S810). The SRS may be transmitted on a symbol of a designated position in a subframe. For example, the SRS may be transmitted on the last SC-FDMA symbol in an uplink subframe.

The base station and the RRH each receive the SRS from the terminal. A first radio link (RL) RL1 is formed between the terminal and the base station, and actual path attenuation occurs as much as RPL1 (Real PL1). A second radio link RL2 is formed between the terminal and the RRH, and the actual path attenuation occurs by RPL2. Even in the same SRS, the base station receives the SRS according to the path loss of RPL1, and the RRH receives the SRS according to the path loss of RPL2. That is, an SRS directly received by a base station (hereinafter referred to as a directly received SRS) and an SRS received indirectly through an RRH (hereinafter referred to as an indirectly received SRS) may be considered different.

The base station calculates the path loss estimate PL1 according to the directly received SRS, and calculates the path loss estimate PL2 according to the indirectly received SRS (S815).

The base station calculates a path attenuation difference ΔPL which is a difference between PL1 and PL2 according to Equation 10 (S820).

The path loss difference ΔPL is used by the terminal to calculate the path loss prediction PL2 in RL2. This is because, since the terminal can know PL1 using the CRS transmitted from the base station, PL2 can be obtained according to Equation 10 only by knowing ΔPL.

The base station transmits a PDSCH configuration information element including information on the path loss difference ΔPL to the terminal (S825). The PDSCH configuration information element may be defined as shown in the following table.

PDSCH-ConfigCommon :: = SEQUENCE {
point_Index_origin INTEGER (0..7),
point_Index_destination INTEGER (0..7),
delta_Pathloss INTEGER (-60..50),
}

Referring to Table 7, a reference transmission / reception point index (point_Index_origin) is an index indicating a transmission / reception point at which a reference PL value exists, that is, a base station in FIG. 9. The target transmission / reception point index (point_Index_destination) is an index indicating a transmission / reception point at which a reference PL value does not exist, that is, an RRH in FIG. 9. delta_Pathloss is a path loss difference ΔPL in dB.

The PDSCH configuration information element is transmitted on the data area as an RRC message. The data region to which the PDSCH configuration information element is mapped is indicated by the PDCCH. The DCI mapped to the PDCCH may be DCI format 3 / 3A scrambled with TPC-PUSCH-RNTI. In addition, the DCI mapped to the PDCCH may be transmitted as a TPC command in DCI format 0/4, which is scrambled with C-RNTI. Accordingly, the UE may blindly decode the PDCCH first and acquire a PDSCH configuration information element indicated by the PDCCH in a data region.

The terminal calculates PL2 by substituting PL1 and the path attenuation difference ΔPL into Equation 10, and calculates a PUSCH uplink transmission power based on PL2 (S830). PL1 can be calculated by the UE directly from the CRS, ΔPL can be known from the PDSCH configuration information element received from the base station. The values of parameters such as PL1, PL2, ΔPL and the calculation of Equation 10 may be obtained according to real values rather than dB. For example, the UE may calculate the PUSCH uplink transmission power by substituting PL2 into Equation 5 or 6 above.

The UE transmits the PUSCH to the RRH at the calculated PUSCH uplink transmission power (S835). In the case of the CoMP terminal, one of the plurality of transmission / reception points (ie, the base station or the RRH) may be dynamically selected as a target by the DPS, and the PUSCH may be transmitted to the target. When the UE selects the RRH as a target, the UE transmits the PUSCH to the RRH with the uplink transmission power reflecting the PL2 calculated by step S830.

10 is a block diagram illustrating a terminal and a transmission and reception point according to an embodiment of the present invention.

Referring to FIG. 10, the terminal 1000 and the transmission / reception point 1050 exchange signals with each other in a lower layer such as a physical layer, or a higher layer such as a medium access control (MAC) layer or an RRC layer. You can send and receive signals at the layer. Both the terminal 1000 and the transmission / reception point 1050 may configure a CoMP system. That is, the terminal 1000 may be a CoMP terminal, and the transmission / reception point 1050 may transmit a signal to the terminal 1000 or may receive a signal from the terminal 1000 in cooperation with the base station or the RRH in the CoMP mode.

The terminal 1000 includes a terminal RF unit 1005 and a terminal processor 1010. The terminal processor 1010 further includes an RRC message processor 1011 and a path loss calculator 1012.

The terminal RF unit 1005 receives the PDSCH configuration information element, the CSI-RS configuration information, which is the upper layer message, and the CSI-RS, CRS, etc., which are the lower layer signals, from the transmission / reception point 1050 to the terminal processor 1010. send. In particular, the upper layer message is sent to the RRC message processor 1011, and the lower layer signal is sent to the path loss calculator 1012. In addition, the terminal RF unit 1005 transmits a PUSCH or SRS, which is a lower layer signal, to the transceiver point 1050.

The RRC message processor 1011 analyzes the PDSCH configuration information element and configuration information about the CSI-RS to obtain parameters to be used for calculating the downlink path loss estimate between the terminal 1000 and the transmission / reception point 1050.

As an example, the RRC message processing unit 1011 calculates a downlink path loss estimate between the UE 1000 and the transceiver point 1050 from the downlink reference signal transmission power of the transceiver point 1050 included in the PDSCH configuration information element. Derivation of the EPRE to be used. In this case, the PDSCH configuration information element may be defined, for example, in any one form of Tables 2 to 4. The RRC message processing unit 1011 obtains a speculative ratio of energy per PDSCH (EPRE) to energy per CSI-RS resource element (EPRE) for deriving CSI feedback from the CSI-RS configuration information. The RRC message processor 1011 informs the path loss calculator 1012 of the EPRE of the CSI-RS to be used for calculating the downlink path loss estimate. The RRC message processing unit 1011 calculates an RSRP for the CSI-RS, for example, using Equation 2 below. At this time, the path loss calculator 1012 calculates a path loss estimate based on the EPRE and the RSRP (S1012). For example, the path loss calculator 1012 may calculate the path loss estimate according to Equation 4, for example.

As another example, the RRC message processing unit 1011 reads the path loss difference ΔPL included in the PDSCH configuration information element and informs the path loss calculation unit 1012. Here, the PDSCH configuration information element may be defined, for example, in the form shown in Table 7. In this case, the path loss calculator 1012 may calculate the path loss estimate according to Equation 10, for example.

The path loss calculator 1012 calculates the PUSCH uplink transmission power by substituting the calculated path loss estimate into, for example, Equation 5 or 6 above.

The terminal RF unit 1005 transmits the PUSCH to the transceiver point 1050 using the PUSCH uplink transmission power calculated by the path loss calculator 1012.

The transmission / reception point 1050 includes a transmission / reception point RF unit 1060 and a transmission / reception point processor 1070. The transceiver point processor 1070 again includes an RRC message processor 1071 and a path loss difference calculator 1072.

The transceiver point RF unit 1060 transmits the PDSCH configuration information element, which is an upper layer message generated by the RRC message processing unit 1071, and configuration information about the CSI-RS, to the terminal 1000. In addition, the transmitting and receiving point RF unit 1060 generates a lower layer signal CSI-RS, CRS, and transmits to the terminal 1000. Meanwhile, the transceiver RF unit 1060 receives the SRS from the terminal 1005.

The RRC message processing unit 1071 generates a higher layer message such as a PDSCH configuration information element and configuration information about the CSI-RS.

The path loss difference calculation unit 1072 obtains the result of receiving the SRS from the terminal 1005 from another transmission / reception point (not shown), such as RRH, and estimates the path loss PL2 between the terminal 1000 and the other transmission / reception point. The path loss estimate PL1 between the terminal 1000 and the transmission / reception point 1050 is calculated, and the path loss difference ΔPL is calculated based on the PL1 and PL2. At this time, the path attenuation difference calculator 1072 calculates a path attenuation difference ΔPL using, for example, Equation (7). The path loss difference calculator 1072 then transmits the information about the path loss difference ΔPL to the RRC message processor 1071. The RRC message processing unit 1071 generates a PDSCH configuration information element including a field indicating the path loss difference ΔPL.

The above description is merely illustrative of the technical idea of the present invention, and those skilled in the art to which the present invention pertains may make various modifications and changes without departing from the essential characteristics of the present invention. Therefore, the embodiments disclosed in the present invention are intended to illustrate rather than limit the scope of the present invention, and the scope of the technical idea of the present invention is not limited by these embodiments. The scope of protection of the present invention should be construed according to the following claims, and all technical ideas falling within the scope of the same shall be construed as falling within the scope of the present invention.

Claims (13)

In the control method of the uplink transmission power for the terminal performed by the terminal,
Receiving a physical downlink shared channel (PDSCH) configuration information element indicating a transmission power with respect to a reference signal used for estimation of channel state information, from a transmitting and receiving point;
Receiving the reference signal from the transmission / reception point;
The energy per resource element of the reference signal is calculated from the transmit power of the reference signal indicated by the PDSCH configuration information element, and physical layer level filtering and upper layer level filtering are applied to the reference signal. Calculating a reference signal received power (RSRP);
Calculating a path loss estimate for the transceiver point from the energy per resource element of the reference signal and the reference signal versus received power; And
And calculating uplink transmit power for the transmit / receive point based on the path loss estimate. The method of claim 1,
And the transmission / reception point is a remote radio head (RRH) connected to a base station operating in a coordinated multi point (CoMP) mode. The method of claim 1,
Wherein the transmit power with respect to the reference signal is defined as a linear average of power contributions of all resource elements carrying the reference signal within an operating system bandwidth. The method of claim 1,
Wherein the PDSCH configuration information element defines reference signal transmit power at a plurality of transmit / receive points including the transmit / receive point individually. The method of claim 1,
And receiving setting information regarding channel state information-reference signal, which is an information element used to specify the setting regarding the reference signal. The method of claim 5, wherein
The configuration information about the channel state information-reference signal indicates an estimated ratio of energy per resource element of the reference signal in energy per resource element of the PDSCH. In the control method of the uplink transmission power for the terminal performed by the first transmission and reception point,
Receiving a sounding reference signal (SRS) from the terminal;
A first path attenuation estimate between the terminal and the first transmission / reception point obtained from the result of receiving the SRS from the first transmission / reception point, and a second path between the terminal and the second transmission / reception point obtained from the result of receiving the SRS from the second transmission / reception point; Calculating a path attenuation difference that is a difference between two path attenuation estimates; And
And transmitting a physical downlink shared channel (PDSCH) configuration information element indicating the path attenuation difference to the user equipment. The method of claim 7, wherein
And the PDSCH configuration information element includes an index of the first transmit / receive point and an index of the second transmit / receive point. In the terminal for controlling the uplink transmission power for the terminal,
A physical downlink shared channel (PDSCH) configuration information element indicative of a transmission power for a reference signal used for estimation of channel state information, and a terminal RF unit for receiving the reference signal from the transmission / reception point;
Analyze the PDSCH configuration information element to obtain transmit power for the reference signal, derive energy per resource element of the reference signal from transmit power for the reference signal, and perform physical layer level filtering on the reference signal; An RRC message processing unit for calculating an RSRP by applying higher layer level filtering; And
And a path loss calculator configured to calculate a path loss estimate for the transceiver point from the energy per resource element of the reference signal and the RSRP. The method of claim 9,
The transceiver point is characterized in that the remote radio head connected to the base station operating in the cooperative multiple transmission point mode. The method of claim 9,
And wherein the transmit power with respect to the reference signal is defined as a linear average over power contributions of all resource elements carrying the reference signal within an operating system bandwidth. The method of claim 9,
And the terminal RF unit further receives setting information regarding channel state information-reference signal which is an information element used to specify the setting regarding the reference signal. 13. The method of claim 12,
And the configuration information about the channel state information-reference signal indicates an estimated ratio of energy per resource element of the reference signal in energy per resource element of the PDSCH.

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