WO2012157967A2 - Method for controlling uplink transmission power by a terminal that adopts a time division duplex (tdd) scheme in a wireless communication system, and terminal device thereof - Google Patents

Abstract

Disclosed are a method for controlling uplink transmission power by a terminal that adopts a time division duplex (TDD) scheme in a wireless communication system, and a terminal device thereof. The method for controlling uplink transmission power by a terminal that adopts a TDD scheme in a wireless communication system comprises the steps of: determining, when the ratio of the number of downlink subframes to the number of uplink subframes changes in said TDD scheme, uplink transmission power to be transmitted from at least one uplink subframe within a changed first frame; and transmitting an uplink signal in said at least one uplink subframe according to said determined uplink transmission power.

Description

Method for controlling uplink transmission power by a terminal using a time division duplex (TDD) scheme in a wireless communication system and the terminal apparatus

The present invention relates to wireless communication, and more particularly, to a method and a terminal apparatus for controlling a uplink transmission power by a terminal using a time division duplex (TDD) scheme in a wireless communication system.

As an example of a mobile communication system to which the present invention can be applied, a 3GPP LTE (3rd Generation Partnership Project Long Term Evolution, hereinafter referred to as 'LTE'), and an LTE-Advanced (hereinafter referred to as 'LTE-A') communication system are outlined. Explain.

1 is a diagram schematically illustrating an E-UMTS network structure as an example of a mobile communication system.

The Evolved Universal Mobile Telecommunications System (E-UMTS) system is an evolution from the existing Universal Mobile Telecommunications System (UMTS), and is currently being standardized in 3GPP. In general, the E-UMTS may be referred to as a Long Term Evolution (LTE) system. For details of technical specifications of UMTS and E-UMTS, refer to Release 8 and Release 9 of the "3rd Generation Partnership Project; Technical Specification Group Radio Access Network", respectively.

Referring to FIG. 1, an E-UMTS is located at an end of a user equipment (UE), a base station (eNode B, eNB), and a network (E-UTRAN) and connected to an external network (Access Gateway, AG). It includes. The base station may transmit multiple data streams simultaneously for broadcast service, multicast service and / or unicast service.

One or more cells exist in one base station. The cell is set to one of bandwidths such as 1.25, 2.5, 5, 10, 15, and 20 MHz to provide downlink or uplink transmission services to multiple terminals. Different cells may be configured to provide different bandwidths. The base station controls data transmission and reception for a plurality of terminals. For downlink (DL) data, the base station transmits downlink scheduling information, which is related to time / frequency domain, encoding, data size, and hybrid automatic repeat and reQuest (HARQ) request for data to be transmitted to the corresponding UE. Give information and more. In addition, the base station transmits uplink scheduling information to the corresponding terminal for uplink (UL) data and informs the user of the time / frequency domain, encoding, data size, and hybrid automatic retransmission request related information. An interface for transmitting user traffic or control traffic may be used between base stations. The core network (Core Network, CN) may be composed of a network node for the user registration of the AG and the terminal. The AG manages the mobility of the UE in units of a tracking area (TA) composed of a plurality of cells.

Wireless communication technology has been developed up to LTE based on Wideband Code Division Multiple Access (WCDMA), but the needs and expectations of users and operators continue to increase. In addition, as other radio access technologies continue to be developed, new technological evolution is required to be competitive in the future. Reduced cost per bit, increased service availability, the use of flexible frequency bands, simple structure and open interface, and adequate power consumption of the terminal are required.

Recently, 3GPP is working on standardization of subsequent technologies for LTE. In the present specification, the above technique is referred to as 'LTE-A'. One of the major differences between LTE and LTE-A systems is the difference in system bandwidth and the introduction of repeaters.

The LTE-A system aims to support broadband of up to 100 MHz, and to this end, carrier aggregation or bandwidth aggregation technology is used to achieve broadband using multiple frequency blocks. Doing.

Carrier aggregation (or carrier aggregation) allows the use of multiple frequency blocks as one large logical frequency band to use a wider frequency band. The bandwidth of each frequency block may be defined based on the bandwidth of the system block used in the LTE system. Each frequency block is transmitted using a component carrier.

An object of the present invention is to provide a method for controlling uplink transmission power by a terminal using a time division duplex (TDD) scheme in a wireless communication system.

Another object of the present invention is to provide a terminal apparatus for controlling uplink transmission power using a time division duplex (TDD) scheme in a wireless communication system.

Technical problems to be achieved in the present invention are not limited to the above technical problems, and other technical problems that are not mentioned will be clearly understood by those skilled in the art from the following description.

In order to achieve the above technical problem, a method of controlling uplink transmission power by a terminal using a time division duplex (TDD) scheme in a wireless communication system according to the present invention includes the number of downlink to uplink subframes in the TDD scheme. Determining an uplink transmission power to be transmitted in at least one uplink subframe in the changed first frame when the ratio of the s is changed; And transmitting an uplink signal in the at least one uplink subframe according to the determined uplink transmission power. The determined uplink transmit power is a transmit power control command (TPC command) used in a frame before the ratio of the number of downlink to uplink subframes is changed, the most recently used TPC command, and most recently. It may be determined based on the TPC command indicated by the received control information or the default TPC command. The at least one uplink subframe may include a first uplink subframe in the first frame. The number or position of the at least one uplink subframe may be changed according to the ratio of the number of downlink to uplink subframes before the change and the ratio of the changed number of downlink to uplink subframes. The value of the default TPC command may be a value previously promised between the terminal and the base station.

In order to achieve the above technical problem, a terminal device for controlling uplink transmission power using a time division duplex (TDD) scheme in a wireless communication system includes a change in the ratio of downlink to uplink subframes in the TDD scheme. A processor that determines uplink transmit power to be transmitted in at least one uplink subframe in the first frame; And a transmitter for transmitting an uplink signal in the at least one uplink subframe according to the determined uplink transmission power. The determined uplink transmit power is a transmit power control command (TPC command) used in a frame before the ratio of the number of downlink to uplink subframes is changed, the most recently used TPC command, and most recently. It is determined based on the TPC command or the default TPC command indicated from the received control information. The at least one uplink subframe may include a first uplink subframe in the first frame. The number or position of the at least one uplink subframe may be changed according to the ratio of the number of downlink to uplink subframes before the change and the ratio of the changed number of downlink to uplink subframes. The value of the default TPC command is a value previously promised between the terminal and the base station.

According to embodiments of the present invention, the UE enables continuous uplink transmission before and after a reconfiguration boundary of system information.

Effects obtained in the present invention are not limited to the above-mentioned effects, and other effects not mentioned above may be clearly understood by those skilled in the art from the following description. will be.

BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are included as part of the detailed description in order to provide a thorough understanding of the present invention, provide examples of the present invention and together with the description, describe the technical idea of the present invention.

1 is a diagram schematically illustrating an E-UMTS network structure as an example of a mobile communication system.

2 is a block diagram showing the configuration of the base station 205 and the terminal 210 in the wireless communication system 200.

3 illustrates a structure of a radio frame used in a 3GPP LTE / LTE-A system which is one of the wireless communication systems.

FIG. 4 is a diagram illustrating a resource grid of a downlink slot of a 3GPP LTE / LTE-A system as an example of a wireless communication system.

5 illustrates a structure of a downlink subframe of a 3GPP LTE / LTE-A system as an example of a wireless communication system.

6 illustrates a structure of an uplink subframe used in a 3GPP LTE / LTE-A system as an example of a wireless communication system.

7 is a diagram illustrating a carrier aggregation (CA) communication system.

8 is an exemplary diagram for explaining a system change in an LTE system.

9 is a diagram for describing reference timing for a TPC command.

FIG. 10 is an exemplary diagram for solving a problem occurring according to a reference timing relationship for a TPC command when a TDD DL / UL configuration is changed.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. The detailed description, which will be given below with reference to the accompanying drawings, is intended to explain exemplary embodiments of the present invention and is not intended to represent the only embodiments in which the present invention may be practiced. The following detailed description includes specific details in order to provide a thorough understanding of the present invention. However, one of ordinary skill in the art appreciates that the present invention may be practiced without these specific details. For example, the following detailed description will be described in detail assuming that the mobile communication system is a 3GPP LTE, LTE-A system, but is also applied to any other mobile communication system except for the specific matters of the 3GPP LTE, LTE-A. Applicable

In some instances, well-known structures and devices may be omitted or shown in block diagram form centering on the core functions of the structures and devices in order to avoid obscuring the concepts of the present invention. In addition, the same components will be described with the same reference numerals throughout the present specification.

In addition, in the following description, it is assumed that a terminal collectively refers to a mobile or fixed user terminal device such as a user equipment (UE), a mobile station (MS), an advanced mobile station (AMS), and the like. In addition, it is assumed that the base station collectively refers to any node of the network side that communicates with the terminal such as a Node B, an eNode B, a Base Station, and an Access Point (AP).

In a mobile communication system, a user equipment may receive information from a base station through downlink, and the terminal may also transmit information through uplink. Information transmitted or received by the terminal includes data and various control information, and various physical channels exist according to the type and purpose of information transmitted or received by the terminal.

2 is a block diagram showing the configuration of the base station 205 and the terminal 210 in the wireless communication system 200.

Although one base station 205 and one terminal 210 are shown to simplify the wireless communication system 200, the wireless communication system 200 may include one or more base stations and / or one or more terminals. .

Referring to FIG. 2, the base station 205 includes a transmit (Tx) data processor 215, a symbol modulator 220, a transmitter 225, a transmit / receive antenna 230, a processor 280, a memory 285, and a receiver ( 290, symbol demodulator 295, and receive data processor 297. The terminal 210 transmits (Tx) the data processor 265, the symbol modulator 270, the transmitter 275, the transmit / receive antenna 235, the processor 255, the memory 260, the receiver 240, and the symbol. Demodulator 255, receive data processor 250. Although antennas 230 and 235 are shown as one at the base station 205 and the terminal 210, respectively, the base station 205 and the terminal 210 are provided with a plurality of antennas. Accordingly, the base station 205 and the terminal 210 according to the present invention support a multiple input multiple output (MIMO) system. In addition, the base station 205 according to the present invention may support both a single user-MIMO (SU-MIMO) and a multi-user-MIMO (MU-MIMO) scheme.

On the downlink, the transmit data processor 215 receives the traffic data, formats the received traffic data, codes it, interleaves and modulates (or symbol maps) the coded traffic data, and modulates the symbols ("data"). Symbols "). The symbol modulator 220 receives and processes these data symbols and pilot symbols to provide a stream of symbols.

The symbol modulator 220 multiplexes the data and pilot symbols and sends it to the transmitter 225. In this case, each transmission symbol may be a data symbol, a pilot symbol, or a signal value of zero. In each symbol period, pilot symbols may be sent continuously. The pilot symbols may be frequency division multiplexed (FDM), orthogonal frequency division multiplexed (OFDM), time division multiplexed (TDM), or code division multiplexed (CDM) symbols.

Transmitter 225 receives the stream of symbols and converts it into one or more analog signals, and further adjusts (eg, amplifies, filters, and frequency upconverts) the analog signals to provide a wireless channel. Generates a downlink signal suitable for transmission through the antenna, and then, the antenna 230 transmits the generated downlink signal to the terminal.

In the configuration of the terminal 210, the antenna 235 receives the downlink signal from the base station and provides the received signal to the receiver 240. Receiver 240 adjusts the received signal (eg, filtering, amplifying, and frequency downconverting), and digitizes the adjusted signal to obtain samples. The symbol demodulator 245 demodulates the received pilot symbols and provides them to the processor 255 for channel estimation.

The symbol demodulator 245 also receives a frequency response estimate for the downlink from the processor 255 and performs data demodulation on the received data symbols to obtain a data symbol estimate (which is an estimate of the transmitted data symbols). Obtain and provide data symbol estimates to a receive (Rx) data processor 250. The receive data processor 250 demodulates (ie, symbol de-maps), deinterleaves, and decodes the data symbol estimates to recover the transmitted traffic data.

 The processing by the symbol demodulator 245 and the receiving data processor 250 are complementary to the processing by the symbol modulator 220 and the transmitting data processor 215 at the base station 205, respectively.

The terminal 210 is on the uplink, and the transmit data processor 265 processes the traffic data to provide data symbols. The symbol modulator 270 may receive and multiplex data symbols, perform modulation, and provide a stream of symbols to the transmitter 275. Transmitter 275 receives and processes the stream of symbols to generate an uplink signal. The antenna 235 transmits the generated uplink signal to the base station 205.

At the base station 205, an uplink signal is received from the terminal 210 through the antenna 230, and the receiver 290 processes the received uplink signal to obtain samples. The symbol demodulator 295 then processes these samples to provide received pilot symbols and data symbol estimates for the uplink. The received data processor 297 processes the data symbol estimates to recover the traffic data sent from the terminal 210.

Processors 255 and 280 of each of the terminal 210 and the base station 205 instruct (eg, control, coordinate, manage, etc.) operations at the terminal 210 and the base station 205, respectively. Respective processors 255 and 280 may be connected to memory units 260 and 285 that store program codes and data. The memory 260, 285 is coupled to the processor 280 to store the operating system, applications, and general files.

The processors 255 and 280 may also be referred to as a controller, a microcontroller, a microprocessor, a microcomputer, or the like. The processors 255 and 280 may be implemented by hardware or firmware, software, or a combination thereof. When implementing embodiments of the present invention using hardware, application specific integrated circuits (ASICs) or digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs) configured to perform the present invention. Field programmable gate arrays (FPGAs) may be provided in the processors 255 and 280.

Meanwhile, when implementing embodiments of the present invention using firmware or software, the firmware or software may be configured to include a module, a procedure, or a function for performing the functions or operations of the present invention, and to perform the present invention. The firmware or software configured to be may be provided in the processors 255 and 280 or may be stored in the memory 260 and 285 and driven by the processors 255 and 280.

The layers of the air interface protocol between the terminal and the base station between the wireless communication system (network) are based on the lower three layers of the open system interconnection (OSI) model, which is well known in the communication system. ), And the third layer L3. The physical layer belongs to the first layer and provides an information transmission service through a physical channel. A Radio Resource Control (RRC) layer belongs to the third layer and provides control radio resources between the UE and the network. The terminal and the base station may exchange RRC messages through the wireless communication network and the RRC layer.

3 illustrates a structure of a radio frame used in a 3GPP LTE / LTE-A system which is one of the wireless communication systems.

In a cellular OFDM wireless packet communication system, uplink / downlink data packet transmission is performed in subframe units, and one subframe is defined as a predetermined time interval including a plurality of OFDM symbols. The 3GPP LTE standard supports a type 1 radio frame structure applicable to frequency division duplex (FDD) and a type 2 radio frame structure applicable to time division duplex (TDD).

3 (a) illustrates the structure of a type 1 radio frame. The downlink radio frame consists of 10 subframes, and one subframe consists of two slots in the time domain. The time taken for one subframe to be transmitted is called a transmission time interval (TTI). For example, one subframe may have a length of 1 ms, and one slot may have a length of 0.5 ms. One slot includes a plurality of OFDM symbols in the time domain and a plurality of resource blocks (RBs) in the frequency domain. In the 3GPP LTE system, since OFDMA is used in downlink, an OFDM symbol represents one symbol period. An OFDM symbol may also be referred to as an SC-FDMA symbol or symbol period. A resource block (RB) as a resource allocation unit may include a plurality of consecutive subcarriers in one slot.

The number of OFDM symbols included in one slot may vary depending on the configuration of a cyclic prefix (CP). CPs include extended CPs and normal CPs. For example, when an OFDM symbol is configured by a standard CP, the number of OFDM symbols included in one slot may be seven. When the OFDM symbol is configured by the extended CP, since the length of one OFDM symbol is increased, the number of OFDM symbols included in one slot is smaller than that of the standard CP. In the case of an extended CP, for example, the number of OFDM symbols included in one slot may be six. If the channel state is unstable, such as when the terminal moves at a high speed, an extended CP may be used to further reduce intersymbol interference.

When a standard CP is used, since one slot includes 7 OFDM symbols, one subframe includes 14 OFDM symbols. In this case, the first up to three OFDM symbols of each subframe may be allocated to a physical downlink control channel (PDCCH), and the remaining OFDM symbols may be allocated to a physical downlink shared channel (PDSCH).

3 (b) illustrates the structure of a type 2 radio frame. Type 2 radio frames consist of two half frames, each of which has five subframes, a downlink pilot time slot (DwPTS), a guard period (GP), and an uplink pilot time slot (UpPTS). One subframe consists of two slots. DwPTS is used for initial cell search, synchronization or channel estimation at the terminal. UpPTS is used for channel estimation at the base station and synchronization of uplink transmission of the terminal. The guard period is a period for removing interference generated in the uplink due to the multipath delay of the downlink signal between the uplink and the downlink.

Each half frame includes five subframes, and a subframe labeled "D" is a subframe for downlink transmission, a subframe labeled "U" is a subframe for uplink transmission, and "S" The indicated subframe is a special subframe including a downlink pilot time slot (DwPTS), a guard period (GP), and an uplink pilot time slot (UpPTS). DwPTS is used for initial cell search, synchronization or channel estimation at the terminal. UpPTS is used for channel estimation at the base station and synchronization of uplink transmission of the terminal. The guard period is a period for removing interference generated in the uplink due to the multipath delay of the downlink signal between the uplink and the downlink.

In the case of 5ms downlink-uplink switch-point period, the special subframe S exists every half-frame, and in the case of 5ms downlink-uplink switch-point period, only the first half-frame exists. Subframe indexes 0 and 5 and DwPTS are sections for downlink transmission only. The subframe immediately following the UpPTS and the special subframe is always an interval for uplink transmission. When multi-cells are aggregated, the UE may assume the same uplink-downlink configuration across all cells, and guard intervals of special subframes in different cells overlap at least 1456 Ts. The structure of the radio frame is only an example, and the number of subframes included in the radio frame or the number of slots included in the subframe and the number of symbols included in the slot may be variously changed.

Table 1 below shows the composition of special frames (length of DwPTS / GP / UpPTS).

Table 1

Special subframe configuration	Normal cyclic prefix in downlink			Extended cyclic prefix in downlink
	DwPTS	UpPTS		DwPTS	UpPTS
		Normal cyclic prefixin uplink	Extended cyclic prefix in uplink		Normal cyclic prefix in uplink	Extended cyclic prefix in uplink
0	6592T S	2192T S	2560T S	7680T S	2192T S	2560T S
One	19760T S			20480T S
2	21952T S			23040T S
3	24144T S			25600T S
4	26336T S			7680T S	4384T S	5120T S
5	6592T S	4384T S	5120T S	20480T S
6	19760T S			23040T S
7	21952T S
8	24144T S

Table 2 below shows an uplink-downlink configuration.

TABLE 2

Referring to Table 2, there are seven uplink-downlink configurations in a type 2 frame structure in the 3GPP LTE system. Each configuration may have a different position or number of downlink subframes, special frames, and uplink subframes. Hereinafter, various embodiments of the present invention will be described based on uplink-downlink configurations of the type 2 frame structure shown in Table 2.

The structure of the radio frame is only an example, and the number of subframes included in the radio frame or the number of slots included in the subframe and the number of symbols included in the slot may be variously changed.

FIG. 4 is a diagram illustrating a resource grid of a downlink slot of a 3GPP LTE / LTE-A system as an example of a wireless communication system.

Referring to FIG. 4, the downlink slot includes a plurality of OFDM symbols in the time domain. One downlink slot may include 7 (or 6) OFDM symbols and the resource block may include 12 subcarriers in the frequency domain. Each element on the resource grid is referred to as a resource element (RE). One RB contains 12x7 (6) REs. The number of RBs included in the downlink slot NRB depends on the downlink transmission band. The structure of an uplink slot is the same as that of a downlink slot, but an OFDM symbol is replaced with an SC-FDMA symbol.

5 illustrates a structure of a downlink subframe of a 3GPP LTE / LTE-A system as an example of a wireless communication system.

Referring to FIG. 5, up to three (4) OFDM symbols located at the front of the first slot of a subframe correspond to a control region to which a control channel is allocated. The remaining OFDM symbols correspond to data regions to which the Physical Downlink Shared CHance (PDSCH) is allocated. Examples of a downlink control channel used in LTE include a Physical Control Format Indicator Channel (PCFICH), a Physical Downlink Control Channel (PDCCH), a Physical Hybrid ARQ Indicator Channel (PHICH), and the like. The PCFICH is transmitted in the first OFDM symbol of a subframe and carries information about the number of OFDM symbols used for transmission of a control channel within the subframe. The PHICH carries a HARQ ACK / NACK (Hybrid Automatic Repeat request acknowledgment / negative-acknowledgment) signal in response to uplink transmission.

Control information transmitted through the PDCCH is referred to as downlink control information (DCI). The DCI format is defined as format 0 for uplink, formats 1, 1A, 1B, 1C, 1D, 2, 2A, 3, 3A, and so on for downlink. The DCI format includes a hopping flag, RB assignment, modulation coding scheme (MCS), redundancy version (RV), new data indicator (NDI), transmit power control (TPC), and cyclic shift DM RS, depending on the application. Information including a reference signal (CQI), a channel quality information (CQI) request, a HARQ process number, a transmitted precoding matrix indicator (TPMI), and a precoding matrix indicator (PMI) confirmation are optionally included.

The PDCCH includes a transmission format and resource allocation information of a downlink shared channel (DL-SCH), a transmission format and resource allocation information of an uplink shared channel (UL-SCH), a paging channel, Resource allocation information of upper-layer control messages such as paging information on PCH), system information on DL-SCH, random access response transmitted on PDSCH, Tx power control command set for individual terminals in terminal group, Tx power control command , The activation instruction information of the Voice over IP (VoIP). A plurality of PDCCHs may be transmitted in the control region. The terminal may monitor the plurality of PDCCHs. The PDCCH is transmitted on an aggregation of one or a plurality of consecutive control channel elements (CCEs). CCE is a logical allocation unit used to provide a PDCCH with a coding rate based on radio channel conditions. The CCE corresponds to a plurality of resource element groups (REGs). The format of the PDCCH and the number of PDCCH bits are determined according to the number of CCEs. The base station determines the PDCCH format according to the DCI to be transmitted to the terminal, and adds a cyclic redundancy check (CRC) to the control information. The CRC is masked with an identifier (eg, a radio network temporary identifier (RNTI)) according to the owner or purpose of use of the PDCCH. For example, when the PDCCH is for a specific terminal, an identifier (eg, cell-RNTI (C-RNTI)) of the corresponding terminal may be masked on the CRC. If the PDCCH is for a paging message, a paging identifier (eg, paging-RNTI (P-RNTI)) may be masked to the CRC. When the PDCCH is for system information (more specifically, a system information block (SIC)), a system information RNTI (SI-RNTI) may be masked to the CRC. If the PDCCH is for a random access response, a random access-RNTI (RA-RNTI) may be masked to the CRC.

6 illustrates a structure of an uplink subframe used in a 3GPP LTE / LTE-A system as an example of a wireless communication system.

Referring to FIG. 6, an uplink subframe includes a plurality of slots (eg, two). The slot may include different numbers of SC-FDMA symbols according to the CP length. The uplink subframe is divided into a data region and a control region in the frequency domain. The data area includes a PUSCH and is used to transmit a data signal such as voice. The control region includes a PUCCH and is used to transmit uplink control information (UCI). The PUCCH includes RB pairs located at both ends of the data region on the frequency axis and hops to a slot boundary.

PUCCH may be used to transmit the following control information.

SR (Scheduling Request): Information used for requesting an uplink UL-SCH resource. It is transmitted using OOK (On-Off Keying) method.

HARQ ACK / NACK: This is a response signal for a downlink data packet on a PDSCH. Indicates whether the downlink data packet was successfully received. One bit of ACK / NACK is transmitted in response to a single downlink codeword (CodeWord, CW), and two bits of ACK / NACK are transmitted in response to two downlink codewords.

Channel Quality Indicator (CQI): Feedback information for the downlink channel. Multiple input multiple output (MIMO) related feedback information includes a rank indicator (RI), a precoding matrix indicator (PMI), a precoding type indicator (PTI), and the like. 20 bits are used per subframe.

The amount of control information (UCI) that a UE can transmit in a subframe depends on the number of SC-FDMA available for control information transmission. SC-FDMA available for transmission of control information means the remaining SC-FDMA symbol except for the SC-FDMA symbol for transmitting the reference signal in the subframe, and in the case of the subframe in which the Sounding Reference Signal (SRS) is set, the last of the subframe SC-FDMA symbols are also excluded. The reference signal is used for coherent detection of the PUCCH. PUCCH supports seven formats according to the transmitted information.

Table 3 shows mapping relationship between PUCCH format and UCI in LTE.

TABLE 3

PUCCH format	Uplink Control Information (UCI)
Format 1	Scheduling Request (SR) (Unmodulated Waveform)
Format 1a	1-bit HARQ ACK / NACK (with or without SR)
Format 1b	2-bit HARQ ACK / NACK (with or without SR)
Format 2	CQI (20 coded bits)
Format 2	CQI and 1- or 2-bit HARQ ACK / NACK (20 bit) (Extended CP only)
Format 2a	CQI and 1-Bit HARQ ACK / NACK (20 + 1 Coded Bits)
Format 2b	CQI and 2-bit HARQ ACK / NACK (20 + 2 coded bits)

7 is a diagram illustrating a carrier aggregation (CA) communication system.

The LTE-A system uses a carrier aggregation or bandwidth aggregation technique that combines a plurality of uplink / downlink frequency bandwidths for a wider frequency bandwidth and uses a larger uplink / downlink bandwidth. Each small frequency bandwidth is transmitted using a component carrier (CC). The component carrier may be understood as the carrier frequency (or center carrier, center frequency) for the corresponding frequency block.

Each of the CCs may be adjacent or non-adjacent to each other in the frequency domain. The bandwidth of the CC may be limited to the bandwidth of the existing system for backward compatibility with the existing system. For example, the existing 3GPP LTE system supports {1.4, 3, 5, 10, 15, 20} MHz bandwidth, LTE_A can support a bandwidth greater than 20MHz using only the bandwidths supported by LTE. . The bandwidth of each CC can be determined independently. It is also possible to merge asymmetric carriers in which the number of UL CCs and the number of DL CCs differ. The DL CC / UL CC link may be fixed in the system or configured semi-statically. For example, as shown in FIG. 6 (a), when there are four DL CCs and two UL CCs, DL-UL linkages can be configured to correspond to DL CC: UL CC = 2: 1. Similarly, as shown in FIG. 6 (b), DL-UL linkage can be configured to correspond to DL CC: UL CC = 1: 2 when two DL CCs are four UL CCs. Unlike illustrated, symmetric carrier merging is possible, where the number of DL CCs and the number of UL CCs are the same. In this case, a DL-UL linkage configuration of DL CC: UL CC = 1: 1 is also possible.

In addition, even if the system overall bandwidth is composed of N CCs, the frequency band that a specific UE can monitor / receive may be limited to M (<N) CCs. Various parameters for carrier aggregation may be set in a cell-specific, UE group-specific or UE-specific manner. Meanwhile, the control information may be set to be transmitted and received only through a specific CC. A specific CC may be referred to as a primary CC (PCC) and the remaining CC may be referred to as a secondary CC (SCC).

LTE-A uses the concept of a cell to manage radio resources. A cell is defined as a combination of downlink resources and uplink resources, and uplink resources are not required. Accordingly, the cell may be configured with only downlink resources or with downlink resources and uplink resources. If carrier aggregation is supported, the linkage between the carrier frequency (or DL CC) of the downlink resource and the carrier frequency (or UL CC) of the uplink resource may be indicated by system information. A cell operating on the primary frequency (or PCC) may be referred to as a primary cell (PCell), and a cell operating on the secondary frequency (or SCC) may be referred to as a secondary cell (SCell).

The PCell is used by the terminal to perform an initial connection establishment process or to perform a connection re-establishment process. PCell may refer to a cell indicated in the handover process. The SCell is configurable after a Radio Resource Control (RRC) connection is established and can be used to provide additional radio resources. PCell and SCell may be collectively referred to as a serving cell. Therefore, in the case of the UE that is in the RRC_CONNECTED state, but carrier aggregation is not configured or does not support carrier aggregation, there is only one serving cell configured only with the PCell. On the other hand, in the case of the UE in the RRC_CONNECTED state and the carrier aggregation is configured, one or more serving cells exist, and the entire serving cell includes the PCell and the entire SCell. For carrier aggregation, after the initial security activation process is initiated, the network may configure one or more SCells for the UE supporting carrier aggregation in addition to the PCell initially configured in the connection establishment process.

Unlike conventional LTE systems using one carrier, a carrier aggregation using a plurality of component carriers (CCs) requires a method of effectively managing component carriers. In order to efficiently manage component carriers, component carriers can be classified according to their roles and characteristics. In carrier aggregation, a multicarrier may be divided into a primary component carrier (PCC) and a secondary component carrier (SCC), which may be UE-specific parameters.

A primary component carrier (PCC) is a component carrier which is the center of management of a component carrier when using multiple component carriers, and is defined one for each terminal. The primary component carrier may play a role of a core carrier managing all the aggregated component carriers, and the remaining secondary component carriers may play a role of providing additional frequency resources to provide a high data rate. For example, the base station may be connected through the primary component carrier (RRC) for signaling with the terminal. Provision of information for security and higher layers may also be accomplished through the main component carrier. In fact, when only one component carrier exists, the corresponding component carrier will be the main component carrier, and may play the same role as the carrier of the existing LTE system.

The base station may be assigned an activated component carrier (ACC) for the terminal among the plurality of component carriers. The terminal knows the active component carrier (ACC) allocated to it in advance through signaling or the like. The UE may collect responses to a plurality of PDCCHs received from the downlink PCell and the downlink SCells and transmit the responses to the PUCCH through the uplink Pcell.

System information changes in the LTE system (excluding the Earthquake and Tsunami Warning System (ETWS) and the Commercial Moboil Alert System (CMAS)) occur only in specific radio frames (ie, the concept of a modification period is used). System information may be sent several times with the same content within a modification period. The modification period boundary is defined by the SFN value for SFN mod m = 0, where m is the number of radio frames containing the modification period. The modification period is set by the system information. When the network changes (some) system information, it first informs the terminal about this change, that is, it can be performed through a modification cycle. In the next modification note, the network sends updated system information. These general theories are described below with reference to FIG. 8.

8 is an exemplary diagram for explaining a system change in an LTE system.

Referring to FIG. 8, different hatching shapes represent different system information. When the terminal receives the system information change notification, new system information can be obtained immediately from the start of the next modification period (n + 1). Then, the terminal may apply the previously obtained system information until the new system information is obtained. In FIG. 8, the system information change is semi-statically changed during the modification period n, but may also occur when the system information is changed dynamically.

Hereinafter, a case in which the base station dynamically / semi-static changes system information such as TDD DL / UL ratio setting will be described. Particularly, in the present invention, when a TDD DL / UL ratio is dynamically changed according to a traffic load situation for each cell, a method for notifying the UE and uplink of changed system information (that is, TDD DL / UL ratio setting) The method to be applied to the transmission power determination will be described.

First, the transmission power of the UE for PUSCH transmission in the 3GPP LTE, LTE-A system will be described below. Equation 1 is a formula for determining a transmission power of a terminal when only PUSCH is transmitted without simultaneously transmitting a PUCCH in a subframe index i of a serving cell c in a system supporting CA.

Equation 1

Equation 2

Equation 2 is a formula for determining PUSCH transmission power when a PUCCH and a PUSCH are simultaneously transmitted in a subframe index i of a serving cell c in a CA-supported system.

Parameters required for determining the uplink transmission power of the UE described in Equations 1 and 2 are for the serving cell c.

Here, the equation 1

Denotes the maximum transmittable power of the terminal at subframe index i,

Is

Denotes a linear value of. Of Equation 2

Is

Represents the linear value of (where

Denotes a PUCCH transmit power at subframe index i.

In Equation 1 again,

Is a parameter indicating the bandwidth of the PUSCH resource allocation expressed by the number of effective resource blocks for the subframe index i, and is a value allocated by the base station.

Is a cell-specific nominal component provided from a higher layer

-Specific components provided by the layer and the upper layer

A parameter configured by the sum of a value, which the base station informs the terminal.

Is a pathloss compensation factor, which is a cell-specific parameter provided by the upper layer and transmitted by the base station in 3 bits, and when j = 0 or 1, α∈ {0, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1} and when j = 2,

= 1. Is a value that the base station informs the terminal.

pathloss (

) Is an estimate of the downlink path loss (or signal loss) calculated by the terminal in dB, and is represented by PLc = referenceSignalPower-higher layer filteredRSRP, where referenceSignalPower may inform the terminal to the terminal by a higher layer.

Is a value representing the current PUSCH power control adjustment state for the subframe index i, and may be expressed as a current absolute value or an accumulated value. Parameters where accumulation is provided from higher layers

Enabled or based on TPC command

Is included in the PDCCH with DCI format 0 for serving cell c scrambled with Temporary C-RNTI

To satisfy.

Is signaled to the PDCCH with DCI format 0/4 or 3 / 3A in the subframe iK _PUSCH , where f _c (0) is the first value after a reset of the accumulated value.

The value of K _PUSCH is defined as follows in the LTE standard.

For FDD (Frequency Division Duplex), the value of K _PUSCH is four. The values of K _PUSCH for TDD UL / DL configuration 1-6 are shown in Table 4 below. For TDD UL / DL configuration 0, LSB (Least Significant Bit) of UL index is set to 1 and K _PUSCH = 7 if PUSCH transmission is scheduled with PDCCH of DCI format 0/4 in subframe 2 or 7. For other PUSCH transmissions, the values of K _PUSCH are shown in Table 4 below.

Table 4

Except in DRX, in every subframe, the UE has a PDCCH of DCI format 0/4 with the C-RNTI of the UE or a PDCCH and SPS C-RNTI of DCI format 3 / 3A with the TPC-PUSCH-RNTI of the UE. Attempt to decode the DCI format. If the DCI format 0/4 and the DCI format 3 / 3A for the serving cell c are detected in the same subframe, the UE is provided in the DCI format 0/4.

Should be used. For a subframe where there is no TPC command decoded for serving cell c, a DRX occurs, or i is not an uplink subframe in TDD

= 0 dB.

Signaled on PDCCH with DCI Format 0/4

Accumulated values are shown in Table 5 below. When a PDCCH with DCI format 0 is validated with SPS activation or when the PDCCH is released,

= 0 dB. Signaled on PDCCH with DCI Format 3 / 3A

The accumulated value is either one of SET1 in Table 5 below or one of SET2 in Table 6 determined by the TPC-index parameter provided in the upper layer.

Table 5

Table 6

When the terminal reaches P _{CMAX, c} for the serving cell c, a positive TPC command is not accumulated for the serving cell c. When the terminal reaches the lowest power, negative TPC commands do not accumulate.

For serving cell c,

When the value changes in the upper layer, and in the primary cell, when the terminal receives the random access response message, the terminal resets the accumulation in the following cases.

Parameters where accumulation is provided from higher layers

If not enabled based on

To satisfy. here,

Is signaled on the PDCCH with DCI format 0/4 in the subframe iK _PUSCH .

The value of K _PUSCH is as follows. For FDD (Frequency Division Duplex), the value of K _PUSCH is four. The values of K _PUSCH for TDD UL / DL configuration 1-6 are shown in Table 4 above. For TDD UL / DL configuration 0, LSB (Least Significant Bit) of UL index is set to 1 and K _PUSCH = 7 if PUSCH transmission is scheduled with PDCCH of DCI format 0/4 in subframe 2 or 7. For other PUSCH transmissions, the values of K _PUSCH are shown in Table 4 above.

Signaled on PDCCH with DCI Format 0/4

Accumulated values are shown in Table 5 above. When a PDCCH with DCI format 0 is validated with SPS activation or when the PDCCH is released,

= 0 dB.

For a subframe where there is no PDCCH with a DCI format decoded for serving cell c, a Discontinued Reception (DRX) occurs, or i is not an uplink subframe in TDD

to be.

For the two types (accumulation or current absolute value), the first value is set as follows.

For serving cell c,

When the value changes in a higher layer, or

If the value is received by the higher layer and the serving cell c is the secondary cell,

to be.

In contrast, if the serving cell is the primary cell,

to be.

Is the TPC command indicated in the random access response,

Is the total power ramp-up from the first to the last preamble and is provided at the upper layer.

Existing time division duplex (TDD) multi-cell systems have used a fixed DL / UL ratio. Since all cells use the same TDD DL / UL ratio, the downlink transmission interval is the same and the uplink transmission interval also starts and ends at the same time. This has the advantage of minimizing the amount of interference generated from adjacent cells by using the same TDD DL / UL ratio. However, the fixed TDD DL / UL ratio has a problem that it is difficult to fully support the traffic load situation by cell. For this reason, it is necessary to configure the TDD DL / UL ratio dynamically / semi-static according to the traffic load per cell, and the proposed system design is needed.

In the TDD system, in support of system reconfiguration of the DL / UL ratio in a dynamic / semi-static manner, the system informs the terminals in the system of the system reconfiguration for a certain period and the changed setting (or configuration) information is At the time of application, the changed system information may be informed to the terminal through a broadcast / unicast method. In this case, support is needed to allow the terminal to continuously transmit data in the old system configuration and the new system configuration.

In the TDD system, transmission timing of feedback information (eg, HARQ feedback, channel quality information (CQI), MIMO-related feedback, etc.) may be set differently according to the DL / UL ratio. The TDD DL / UL ratio may be configured in various forms, and there may be a difference in detailed methods for each TDD DL / UL ratio to support the TDD DL / UL ratio.

The TDD DL / UL ratio supported by each TDD system is composed of several, and the UE can continuously transmit even when the TDD DL / UL ratio is changed by using the TDD DL / UL ratio. Uplink power control is based on a system receiving a TPC (Transmit Power Control) command from the base station. The TPC command may be transmitted UE-specifically in a resource allocation grant or may be transmitted to the UE through a group type message. Such information may have different message timings reflecting a TPC command according to a TDD DL / UL ratio configuration in consideration of a process delay.

For example, the 3GPP LTE / LTE-A system supports seven TDD DL / UL ratios as shown in Table 2 above. In addition, the content of DCI format 0/4 and K _PUSCH timing have been described above. The TPC command to be applied in the i th subframe may refer to the content of DCI format 0/4 received in the iK _PUSCH as shown in Table 4 above.

).

Accordingly, a TPC command is required for the UE, which has been transmitted in the existing configuration or configuration, to continuously transmit even in the new configuration, and DCI format 0/4 in i-K _PUSCH is required. Or we need a way to replace it.

In this manner, the base station independently instructs the TPC command to the UE through L1 / L2 control signaling or higher layer, or information indicated from another DCI format or the like using other scheduling information, downlink DCI formats, There may be considered a method of instructing the terminal with the corresponding TPC command by using implicit or explicit signaling in another uplink DCI format.

9 is a diagram for describing reference timing for a TPC command.

The existing system configuration uses the TDD DL / UL configuration 0, and the new configuration describes the TPC command reference timing that occurs when any one of the TDD DL / UL configurations except for the TDD DL / UL configuration 0 is changed. In FIG. 9, a numeric value in each subframe means K _PUSCH .

The right part of FIG. 9 shows a new TDD DL / UL configuration. When the new TDD DL / UL configuration is configured in this way, the dotted lines are problematic in view of the reception of the TPC command required for uplink subframe transmission. That is, even in the newly changed TDD DL / UL configuration, the UE needs a TPC command for signal transmission in an uplink subframe, and the TPC command must be received from the downlink subframe. However, as shown in FIG. 9, when the TDD DL / UL configuration is changed, the TPC command for the uplink subframe in the newly changed TDD DL / UL configuration is seen in the relationship between the TPC command transmission connected by the dotted line and the uplink signal transmission. The problem is that the subframe to be transmitted is changed to an uplink subframe instead of a downlink subframe.

To solve this problem, the following methods can be considered.

 FIG. 10 is an exemplary diagram for solving a problem occurring according to a reference timing relationship for a TPC command when a TDD DL / UL configuration is changed.

FIG. 10 illustrates a case where a TDD DL / UL configuration is dynamically changed from TDD DL / UL configuration 2 to TDD DL / UL configuration 3 as an example. As described above, a method for solving a problem related to uplink power control of a terminal generated when a system configuration such as a TDD DL / UL configuration is changed will be described. This solution can be applied not only to the case of changing from DL / UL configuration 2 to TDD DL / UL configuration 3 but also to various DL / UL configuration changes. As in the case of FIG. 10, only some radio frames (or subframes) may cause problems according to the TDD DL / UL configuration.

In the first method, in the first time unit (radio frame) 1020 of the changed DL / UL configuration, the uplink subframe (the interval indicated by the number 4) in the first half frame is left to be partially or entirely empty. do. Alternatively, in a system supporting synchronous HARQ, a method of applying a certain radio frame (or subframe) delay is applied. When retransmission is performed at a configuration boundary, the UE implies a delay factor to imply a retransmission time. It can be applied implicitly to perform retransmission. The constant radio frame (or subframe) delay information may be transmitted to the terminal by the base station through L1 / L2 (Layer 1 / Layer 2) signaling and higher layers.

As a second method, in the first radio frame 1020 of the changed DL / UL configuration, it is proposed to configure the terminal to reuse the TPC command used in the previous uplink transmission or most recently used. Alternatively, the UE reuses the TPC command indicated by the most recently received DCI format (the most recently received DCI format may be an uplink DCI format or may be considered to be indicated by a downlink DCI format). Or a base station using L1 / L2 signaling or transmission information indicating a TPC command using signaling information predefined by a higher layer may be considered.

As a third method, a method of pre-sharing by a terminal and a base station by setting a default TPC command (default TPC command) used for DL / UL ratio reconfiguration is proposed. For example, the default TPC command value may be set to 0 so that the UE does not refer to the TPC command in the first radio frame 1020 of the DL / UL configuration structure changed upon resetting.

As a fourth method, a method for the base station to send to the terminal in advance in the downlink (reconfiguration) downlink subframe 1015 is proposed.

The base station transmits the TPC command value in the first radio frame of the DL / UL configuration structure changed to the existing uplink DCI format (for example, DCI format 0/4, DCI format 3 / 3A) (or other downlink DCI format). It can be transmitted by designating and adding, or by configuring a difference value with the TPC command value in the radio frame 1010 of the previous DL / UL configuration structure, or by configuring the same value. Alternatively, a method of instructing whether to use the same TPC command as before or to use a default setting or a newly instructed TPC command may be considered.

In the reconfiguration (DL) UL downlink subframe 1015 of the DL / UL configuration structure, the base station sends the UE to the UE in advance, and may transmit the value in a new message format, which is configured by the terminal to the configuration boundary. Is to be used by. A method for configuring a base station in a terminal-specific message, a group message form or a serving cell specific form may be considered.

As a fifth method, in the configuration boundary, the K _PUSCH value of the i-K _PUSCH is reset according to the TDD DL / UL configuration. For example, when changing from TDD DL / UL configuration 2 to TDD DL / UL configuration 3 as shown in FIG. 10, the K _PUSCH value of the uplink subframe of the uplink subframe index 2 is 2, 3, 6, or 7. . This method can be extended to subframes in which a problem occurs due to a relationship with individual TDD configurations.

In FIG. 10, when the TDD DL / UL configuration is changed from TDD DL / UL configuration 2 to TDD DL / UL configuration 3, the first uplink sub indicated by a dotted line in the first radio frame 1020 in which the TDD DL / UL configuration is changed. Only the TPC command value for uplink signal transmission in a frame may be obtained by any one of the above five methods to determine uplink signal transmission power, and then second and third uplink subframes (indicated by solid lines). TPC command value to be applied in the (subframe) is not a problem because it is received in the downlink subframe of the radio frame 1010 before changing the TDD DL / UL configuration.

However, unlike the case of FIG. 10, when the TDD DL / UL configuration is changed in various ways, such as from TDD DL / UL configuration 0 to TDD DL / UL configuration 2, the five methods in the first radio frame is changed. The number of uplink subframes to which the TPC command obtained through this is applied may vary. In FIG. 9, the number of such uplink subframes is two when TDD DL / UL configuration 0 is changed to TDD DL / UL configuration 2, and one when TDD DL / UL configuration 0 is changed to TDD DL / UL configuration 3; 2 when changed from TDD DL / UL configuration 0 to TDD DL / UL configuration 4, 1 when changed from TDD DL / UL configuration 0 to TDD DL / UL configuration 5, TDD DL / UL configuration 0 to TDD DL / UL configuration If it is changed to 6, it is one.

As described above, according to various changes in the TDD DL / UL configuration, the number of uplink subframes to which the TPC command obtained through the five methods is applied and the position in the frame of the uplink subframe to be applied may be different. have.

In addition, when the TPC command operates in an accumulated mode in uplink power control (ULPC) in accordance with the present invention, the accumulated value is configured to operate as follows in the related art. For serving cell c,

When the value is changed in the upper layer, and in the primary cell, when the terminal receives the random access response message, the terminal should reset the accumulation in the following cases.

On the other hand, other methods can also be considered. Whenever the reconfiguration is performed, the accumulated value for PUSCH and PUCCH is reset (0 or an arbitrary value [dB / linear / encoded value]) to be applied when the system parameter systemInfoValueTag in SIBType1 is changed. You can set it.

According to the embodiments of the present invention described above, the UE is capable of continuous uplink transmission before and after the reconfiguration boundary of the system information.

The embodiments described above are the components and features of the present invention are combined in a predetermined form. Each component or feature is to be considered optional unless stated otherwise. Each component or feature may be embodied in a form that is not combined with other components or features. It is also possible to combine some of the components and / or features to form an embodiment of the invention. The order of the operations described in the embodiments of the present invention may be changed. Some components or features of one embodiment may be included in another embodiment or may be replaced with corresponding components or features of another embodiment. It is obvious that the claims may be combined to form embodiments by combining claims that do not have an explicit citation in the claims or as new claims by post-application correction.

It is apparent to those skilled in the art that the present invention can be embodied in other specific forms without departing from the spirit and essential features of the present invention. Accordingly, the above detailed description should not be construed as limiting in all aspects and should be considered as illustrative. The scope of the invention should be determined by reasonable interpretation of the appended claims, and all changes within the equivalent scope of the invention are included in the scope of the invention.

A method of controlling uplink transmission power by a terminal using a time division duplex (TDD) scheme in a wireless communication system can be industrially applied to various mobile communication systems such as 3GPP LTE and LTE-A systems.

Claims (10)

1. A method for controlling uplink transmission power by a terminal using a time division duplex (TDD) scheme in a wireless communication system,

   Determining uplink transmit power to be transmitted in at least one uplink subframe in the first frame when the ratio of downlink to uplink subframes is changed in the TDD scheme; And

   And transmitting an uplink signal in the at least one uplink subframe according to the determined uplink transmission power.
2. The method of claim 1,

   The determined uplink transmit power is a transmit power control command (TPC command) used in a frame before the ratio of the number of downlink to uplink subframes is changed, the most recently used TPC command, and most recently. The uplink transmission power control method according to the system information change, characterized in that determined based on the TPC command or the default TPC command indicated from the received control information.
3. The method of claim 1,

   The at least one uplink subframe includes a first uplink subframe in the first frame, uplink transmission power control method according to a system information change.
4. The method of claim 1,

   The number or position of the at least one uplink subframe is changed according to the ratio of the number of downlink to uplink subframes before the change and the ratio of the number of downlink to uplink subframes changed. Transmission power control method.
5. The method of claim 2,

   The value of the default TPC command is a value previously promised between the terminal and the base station, uplink transmission power control method according to the system information change.
6. A terminal apparatus for controlling uplink transmission power using a time division duplex (TDD) scheme in a wireless communication system,

   A processor for determining uplink transmit power to be transmitted in at least one uplink subframe in the first frame when the ratio of the number of downlink to uplink subframes is changed in the TDD scheme; And

   And a transmitter for transmitting an uplink signal in the at least one uplink subframe according to the determined uplink transmission power.
7. The method of claim 6,

   The determined uplink transmit power is a transmit power control command (TPC command) used in a frame before the ratio of the number of downlink to uplink subframes is changed, the most recently used TPC command, and most recently. And the terminal device is determined based on a TPC command or a default TPC command indicated from the received control information.
8. The method of claim 6,

   The at least one uplink subframe includes a first uplink subframe in the first frame.
9. The method of claim 6,

   The number or position of the at least one uplink subframe is changed according to the ratio of the number of downlink to uplink subframes before the change and the ratio of the number of downlink to uplink subframes before the change.
10. The method of claim 7, wherein

    The default TPC command value is a terminal device, characterized in that the value promised in advance between the terminal and the base station.

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