KR20120034521A - Method for transmitting srs in multiple component carrier system and apparatus thereof - Google Patents

Abstract

PURPOSE: A method for transmitting a SRS(Sounding Reference Signal) in a multiple component carrier system and a device thereof are provided to control transmission of a UL reference signal, thereby preventing unnecessary power consumption of a terminal. CONSTITUTION: A terminal receives an SRS setup message for a UL component carrier from a base station(S1510). The terminal starts counting of an SRS stop timer(S1520). When a counting restart condition and a counting stop condition are not generated, the terminal determines that the counting of the SRS stop timer is terminated(S1530~S1550). When the counting of the SRS stop timer is terminated, the terminal adjusts an SRS transmission cycle(S1560).

Description

METHOD FOR TRANSMITTING SRS IN MULTIPLE COMPONENT CARRIER SYSTEM AND APPARATUS THEREOF}

The present invention relates to a wireless communication technology, and more particularly, to a method for transmitting a sounding reference signal and a transmission apparatus using the same in a multi-component carrier system.

Similar to the downlink, in order to perform coherent demodulation on different uplink physical channels at the receiving end, the uplink also needs a reference signal for channel estimation, and the uplink demodulation reference signal ( Demodulation Reference Signal: DRS, hereinafter referred to as 'DRS'. This uplink reference signal is necessary for synchronous demodulation of a PUSCH to which a UL-SCH is mapped, and also for synchronous demodulation of a PUCCH for transmitting various types of control signals.

In addition, there is a sounding reference signal (SRS, hereinafter referred to as SRS) as another uplink reference signal. SDR is a signal transmitted in uplink so that a base station (Evolved Node B) can estimate uplink channel quality at another frequency.

Since the DRS is used for channel estimation for data demodulation, the SRS does not need to be transmitted together with the physical channel but is used for user scheduling, while always being transmitted with the physical channel and always in the same frequency band. The terminal sends an SRS signal to the uplink channel, and the base station determines the channel state from the sounding reference signal and then performs scheduling for uplink transmission.

Meanwhile, data or various uplink control information as well as a sounding reference signal are transmitted through the uplink control channel. As an uplink control signal, an ACK (ACKnowledgement) / NACK (Not-ACKnowledgement) signal for performing a hybrid automatic repeat request (HARQ), a channel quality indicator (CQI) indicating downlink channel quality, a precoding matrix index (PMI), There are various types such as RI (Rank Indicator).

An object of the present invention is to provide a method for controlling transmission of an uplink reference signal.

An object of the present invention is to provide a method for reducing power consumption by controlling transmission of an uplink reference signal.

An object of the present invention is to provide a method of controlling a transmission of an uplink reference signal to reduce a communication obstacle caused by interference with other users.

An aspect of the present invention is a method of transmitting a sounding reference signal (SRS) in a multi-component carrier system, receiving an SRS configuration message for an uplink component carrier, and transmitting an SRS for an uplink component carrier based on the SRS configuration message. Starting the stop counting of the SRS and rescheduling the period of the SRS transmission when the stop counting of the SRS transmission expires.

The readjustment of the SRS transmission period includes stopping the SRS transmission.

The transmission method of the SRS, after starting the stop counting of the SRS transmission, further comprising the step of determining whether the requirement for restarting the stop counting of the SRS transmission is satisfied, and if the restart requirement corresponds to restart count stop counting of the SRS transmission can do.

The transmission method of the SRS further includes determining whether a requirement for stopping stop counting of the SRS transmission is satisfied after starting stop counting of the SRS transmission and before the stop counting of the SRS transmission is expired. In this case, stop counting of the SRS transmission can be stopped.

Another aspect of the present invention is a wireless terminal apparatus for transmitting a Sounding Reference Signal (SRS) in a multi-component carrier system, comprising: an RF unit for receiving a signal through a downlink channel and transmitting a signal through an uplink channel; And a memory for storing operation information including system information and / or control information necessary for a system operation and a processor for processing a signal received and a signal to be transmitted, and the processor including a timer for controlling transmission of the SRS. can do.

The processor may readjust the transmission period of the SRS when the counting of the timer expires.

After the timer starts counting, the processor determines whether a requirement for restarting the counting is satisfied, and when the restarting requirement is satisfied, the processor may restart the timer.

After starting the counting of the timer, the processor determines whether the requirement to stop counting is satisfied, and if the stop requirement is satisfied, the processor may stop the timer.

Another aspect of the present invention is a method of receiving a sounding reference signal (SRS) in a multi-component carrier system, transmitting an SRS configuration message for an uplink component carrier, and an SRS configuration message based on the SRS configuration message for an uplink component carrier And receiving a change message for setting contents of the setting message, wherein the SRS setting message includes a setting value for stop counting of the SRS transmission, and the change message restarts for stop counting of the SRS transmission. Or an implicit or explicit message for suspension.

The SRS configuration message may include changing the SRS transmission period by a predetermined time after transmitting a SRS configuration message and a predetermined time elapses.

The method of receiving the SRS may include changing a transmission period of the SRS by a predetermined time after the predetermined time has passed after the SRS setting message is transmitted.

Another aspect of the present invention is a receiving apparatus for receiving an SRS of a multi-component carrier system, comprising: an RF unit for receiving a signal through an uplink channel and transmitting a signal through a downlink channel; And a memory for storing operation information including system information and / or control information necessary for a system operation and a processor for processing a signal to be transmitted, wherein the processor transmits SRS configuration information for controlling transmission of an SRS through the RF unit. Send.

According to the present invention, transmission of an uplink reference signal can be controlled.

According to the present invention, it is possible to control the transmission of the uplink reference signal to prevent unnecessary power consumption from the terminal.

According to the present invention, by controlling the transmission of the uplink reference signal, it is possible to reduce unnecessary interference between the other terminal.

1 is a diagram schematically illustrating an example of an LTE uplink subframe structure for transmitting SRS.
2 is a diagram schematically illustrating a wireless communication system.
3 is a diagram schematically illustrating a structure of a radio frame in 3GPP LTE.
4 schematically illustrates a structure of a downlink subframe.
5 is a diagram illustrating an example of carrier aggregation.
6 is a view for explaining another example of carrier aggregation.
7 is a view for explaining another example of carrier aggregation.
FIG. 8 is a diagram schematically illustrating an example of a protocol structure for supporting multiple carriers.
9 is a diagram schematically showing an example of a frame structure for a multi-carrier operation.
FIG. 10 is a diagram schematically illustrating linkage between a downlink component carrier and an uplink component carrier in a multi-carrier system.
11 is an explanatory diagram for explaining the concept of a serving cell and a neighbor cell.
12 is an explanatory diagram illustrating the concept of a primary serving cell and a secondary serving cell.
13 schematically illustrates an example of signaling occurring between a base station and a terminal.
14 is a diagram schematically illustrating a signal flow between a terminal and a base station in relation to RRC reconfiguration.
15 is a flowchart schematically illustrating a method of operating an SRS stop timer in a terminal.
16 is a conceptual diagram schematically illustrating expiration conditions of an inactivity timer and an SRS timer of a DRX.
FIG. 17 is a diagram schematically illustrating a relationship between an on duration time T _on and an SRS timer operation.
18 is a flowchart schematically illustrating operation at a base station in relation to the present invention.
19 is a block diagram schematically illustrating the concept of a base station and a terminal device according to the present invention.

Hereinafter, the present disclosure will be described in detail with reference to the accompanying drawings and examples in connection with the present disclosure. In adding reference numerals to the components of each drawing, it should be noted that the same reference numerals are assigned to the same components as much as possible, even if displayed on 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.

In addition, in describing the components of the present specification, terms such as first, second, A, B, (a), and (b) may be used. These terms are only for distinguishing the components from other components, and the nature, order or order of the components are not limited by the terms. If a component is listed as being “connected”, “coupled” or “connected” to another component, that component may be directly connected or connected to that other component, but there is another component between each component. It is to be understood that can be "connected", "coupled" or "connected".

In addition, the present invention will be described with respect to a wireless communication network. The work performed in the wireless communication network may be performed in a process of controlling a network and transmitting data by a system (e.g., a base station) Work can be done at a terminal connected to the network.

1 schematically illustrates an example of a Long Term Evolutiion (LTE) uplink subframe structure for transmitting SRS.

Referring to FIG. 1, an uplink subframe includes two slots on a time axis, and each slot includes seven Single Carrier-Frequency Division Multiple Access (SC-FDMA) symbols. The uplink subframe includes a PUCCH (Phisycal Uplink Control Channel) and a PUSCH (Phisycal Uplink Shared Channel) on the frequency axis.

PUCCH in the SC-FDMA symbol period in which the SRS is transmitted is punctured. In this case, the UE transmits data using 13 SC-FDMA symbols and performs preprocessing such as rate matching for the last one SC-FDMA symbol and transmits SRS. The 14th SC-FDMA symbol is determined to transmit the SRS, but this is only an example, and the position and number of SF-FDMA symbols may be determined differently. The SRS may be transmitted in the whole of the PUSCH or may be transmitted in only part of the PUSCH.

In general, the terminal may be configured to transmit the SRS with a certain period, but one of the new schemes considered in LTE-A (Advanced) is an aperiodic ARS (Aperiodic Sounding Reference Signal, hereinafter referred to as 'A-SRS'). . In the case of A-SRS, since the UE can transmit the SRS aperiodically, resources can be used more efficiently than when the SRS is periodically transmitted. Since the transmission of the A-SRS is aperiodic, the terminal may transmit the A-SRS only when the base station instructs the transmission of the A-SRS to the terminal. In addition, the base station should inform the terminal of the information on the time / frequency resources for the terminal to transmit the A-SRS. Information on the time / frequency resource for transmitting the A-SRS may be transmitted to the terminal at the same time as the message indicating the transmission of the A-SRS, or may be transmitted to the terminal before.

2 illustrates a wireless communication system.

2, the 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 (BS) 11. Each base station 11 provides a communication service for a specific geographic area (generally called a cell) 15a, 15b, 15c. The cell may again be divided into multiple regions (referred to as sectors).

The terminal 12 (mobile station (MS)) may be fixed or mobile, and may include a user equipment (UE), a mobile terminal (MT), a user terminal (UT), a subscriber station (SS), a wireless device, a PDA, and the like. (Personal Digital Assistant), wireless modem (Wireless Modem), handheld device (handheld device) may be called in other terms. The base station 11 generally refers to a fixed station communicating with the terminal 12, and may be referred to as other terms such as an evolved-NodeB (eNB), a base transceiver system (BTS), an access point, and the like. have. The cell should be interpreted in a comprehensive sense of a part of the area covered by the base station 11 and encompasses various coverage areas such as megacells, macrocells, microcells, picocells, femtocells, and relays.

In the following, downlink means communication from the base station 11 to the terminal 12, and uplink means communication from the terminal 12 to the base station 11. In this case, in 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. Alternatively, in some cases, downlink means communication from the terminal 12 to the base station 11, and uplink may mean communication from the base station 11 to the terminal 12. In this case, in downlink, the transmitter may be part of the terminal 12 and the receiver may be part of the base station 11. In the uplink, the transmitter may be part of the base station 11, and the receiver may be part of the terminal 12.

There is no limitation on the multiple access scheme applied to the wireless communication system. (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. The uplink transmission and the downlink transmission may use a time division duplex (TDD) scheme that is transmitted using different times, or may use a frequency division duplex (FDD) scheme that is transmitted using different frequencies.

3 shows a structure of a radio frame in 3GPP Long Term Evolution (LTE).

Referring to FIG. 3, a radio frame consists of 10 subframes and one subframe consists of two slots. The time it takes 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 Orthogonal Frequency Division Multiplexing (OFDM) symbols in the time domain and includes a plurality of RBs in the frequency domain. The OFDM symbol is used to represent one symbol period since 3GPP LTE uses OFDMA in downlink, and may be referred to as an SC-FDMA symbol or a symbol period according to a multiple access scheme. The RB includes a plurality of consecutive subcarriers in one slot in resource allocation units.

The structure of the radio frame introduced herein is merely 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 OFDM symbols included in the slot may be variously changed.

4 shows a structure of a downlink subframe.

Referring to FIG. 4, a subframe includes two slots. Up to three OFDM symbols in the first slot in the subframe are control regions to which control channels are allocated, and the remaining OFDM symbols are data regions to which a Physical Downlink Shared Channel (PDSCH) is allocated.

Downlink control channels used in 3GPP LTE include a Physical Control Format Indicator Channel (PCFICH), a Physical Downlink Control Channel (PDCCH), and a Physical Hybrid-ARQ Indicator Channel (PHICH). The PCFICH transmitted in the first OFDM symbol of the subframe carries information about the number of OFDM symbols (that is, the size of the control region) used for transmission of control channels in the subframe. The PHICH carries an ACK / NACK signal for uplink HARQ. That is, the ACK / NACK signal for the uplink data transmitted by the UE is transmitted on the PHICH.

Now, a downlink physical channel, PDCCH, will be described.

PDCCH is a resource allocation and transmission format of downlink shared channel (DL-SCH), resource allocation information of uplink shared channel (UL-SCH), paging information on PCH, system information on DL-SCH, random access response transmitted on PDSCH Resource allocation of a higher layer control message, a set of transmit power control commands for individual UEs in a certain UE group, activation of a Voice over Internet Protocol (VoIP), and the like. A plurality of PDCCHs may be transmitted in the control region, and the terminal may monitor the plurality of PDCCHs. The PDCCH is transmitted on an aggregation of one or several consecutive CCEs. CCE is a logical allocation unit used to provide a PDCCH with a coding rate according to the state of a radio channel. The CCE corresponds to a plurality of resource element groups. The format of the PDCCH and the number of bits of the PDCCH are determined according to the correlation between the number of CCEs and the coding rate provided by the CCEs.

Control information transmitted through the PDCCH is called downlink control information (DCI). DCI has a different purpose of use according to its format, and a field defined in DCI is also different. Table 1 shows DCI according to DCI format.

DCI Format Description 0 used for the scheduling of PUSCH (Uplink grant) One used for the scheduling of one PDSCH codeword 1A used for the compact scheduling of one PDSCH codeword and random access procedure initiated by a PDCCH order 1B used for the compact scheduling of one PDSCH codeword with precoding information 1C used for very compact scheduling of one PDSCH codeword and notifying MCCH change 1D used for the compact scheduling of one PDSCH codeword with precoding and power offset information 2 used for scheduling PDSCH to UEs configured in spatial multiplexing mode 2A used for scheduling PDSCH to UEs configured in large delay CDD mode 3 used for the transmission of TPC commands for PUCCH and PUSCH with 2-bit power adjustments 3A used for the transmission of TPC commands for PUCCH and PUSCH with single bit power adjustments

DCI format 0 indicates uplink resource allocation information, DCI formats 1 to 2 indicate downlink resource allocation information, and DCI formats 3 and 3A indicate an uplink TPC command for arbitrary UE groups. . Each field of the DCI is sequentially mapped to an information bit. For example, if the DCI is mapped to information bits having a total length of 44 bits, the resource allocation field may be mapped to the 10th to 23rd bits of the information bits.

DCI includes uplink resource allocation information and downlink resource allocation information. The uplink resource allocation information may be referred to as an uplink grant, and the downlink resource allocation information may be referred to as a downlink grant.

Meanwhile, carrier aggregation (CA) supports a plurality of carriers and is also referred to as spectrum aggregation or bandwidth aggregation. Individual unit carriers bound by carrier aggregation are called component carriers (CC). Each component carrier is defined by a bandwidth and a center frequency. Carrier aggregation is introduced to support increased throughput, to prevent cost increase due to the introduction of wideband radio frequency (RF) devices, and to ensure compatibility with existing systems.

For example, if five carriers having a bandwidth of 5 MHz are allocated, it can support a bandwidth of 25 MHz.

Carrier aggregation includes intra-band contiguous carrier aggregation as shown in FIG. 5, non-contiguous carrier aggregation as shown in FIG. 6, and inter-band as shown in FIG. 7. band) can be divided into carrier aggregation.

First, referring to FIG. 5, in-band adjacent carrier aggregation is achieved between successive component carriers in the same operating band. For example, CC # 1, CC # 2, CC # 3, ..., CC #N which are the aggregated component carriers are all adjacent.

Referring to FIG. 6, in-band non-adjacent carrier aggregation is achieved between discrete component carriers. For example, CC # 1 and CC # 2, which are aggregated component carriers, are spaced apart from each other by a specific frequency.

Referring to FIG. 7, when a plurality of component carriers exist, one or more component carriers are aggregated on different frequency bands. For example, CC # 1, which are aggregated component carriers, exist in operating band # 1, and CC # 2 exists in operating band # 2.

The number of carriers aggregated between the downlink and the uplink may be set differently. The case where the number of downlink component carriers and the number of uplink component carriers are the same is called symmetric aggregation, and when the number is different, it is called asymmetric aggregation.

In addition, the size (ie, bandwidth) of the component carriers may be different from each other. For example, assuming that five component carriers are used for the configuration of the 70 MHz band, 5 MHz CC (carrier # 0) + 20 MHz CC (carrier # 1) + 20 MHz CC (carrier # 2) + 20 MHz CC (carrier # 3 ) + 5MHz CC (carrier # 4) may be configured.

Hereinafter, a multiple carrier system refers to a system supporting carrier aggregation. In a multi-carrier system, adjacent carrier aggregation and / or non-adjacent carrier aggregation may be used, and either symmetric aggregation or asymmetric aggregation may be used.

8 shows an example of a protocol structure for supporting multiple carriers.

Referring to FIG. 8, the common medium access control (MAC) entity 810 manages a physical layer 820 using a plurality of carriers. The MAC management message transmitted on a specific carrier may be applied to other carriers. That is, the MAC management message is a message capable of controlling other carriers including the specific carrier. The physical layer 820 may operate in a time division duplex (TDD) and / or a frequency division duplex (FDD).

Physical control channels are also used in the physical layer 820. A physical downlink control channel (PDCCH) for transmitting physical control information is a HARQ (Hybrid Automatic Repeat) related to resource allocation and DL-SCH associated with a paging channel (PCH) and a downlink shared channel (DL-SCH) to a terminal. reQuest) information. The PDCCH may carry an uplink grant informing the UE of resource allocation of uplink transmission.

The Physical Control Format Indicator CHannel (PCFICH) informs the UE of the number of OFDM symbols used for the PDCCHs and is transmitted every subframe.

The Physical Hybrid ARQ Indicator Channel (PHICH) carries HARQ ACK / NAK signals in response to uplink transmission.

Physical Uplink Control CHannel (PUCCH) carries uplink control information such as HARQ ACK / NAK, scheduling request, and CQI for downlink transmission.

 PUSCH (Physical Uplink Shared CHannel) carries UL-SCH (UpLink Shared CHannel).

9 shows an example of a frame structure for multi-carrier operation.

Referring to FIG. 9, a radio frame consists of 10 subframes. The subframe includes a plurality of OFDM symbols. Each component carrier may have its own control channel (eg, PDCCH). The component carriers may or may not be adjacent to each other. The terminal may support one or more component carriers according to its capability.

The component carrier may be divided into a fully configured component carrier and a partially configured component carrier according to directionality. The preconfigured component carrier refers to a carrier capable of transmitting and / or receiving all control signals and data on a bi-directional carrier, and the partial configuration component carrier transmits only downlink data on a unidirectional carrier. Indicates a possible carrier. The partial configuration component carrier may be mainly used for a multicast and broadcast service (MBS) and / or a single frequency network (SFN).

FIG. 10 illustrates linkage between a downlink component carrier and an uplink component carrier in a multi-carrier system.

Referring to FIG. 10, downlink component carriers D1, D2, and D2 are aggregated in downlink, and uplink component carriers U1, U2, and U3 are aggregated in uplink. Di is an index of a downlink component carrier, and Ui is an index of an uplink component carrier (i = 1, 2, 3).

In the FDD system, the downlink component carrier and the uplink component carrier are configured to be connected 1: 1, and D1 is configured to be connected to U1, D2 to U2, and D3 to U3. The terminal communicates between the downlink component carriers and the uplink component carriers through system information transmitted by a logical channel BCCH (Broadcast Control CHannel) or a dedicated RRC (Radio Resource Control) message transmitted by a dedicated control channel (DCCH). Set up the connection. Each connection setting may be set to be cell specific or UE specific.

An example of an uplink component carrier connected to a downlink component carrier is as follows.

1) an uplink component carrier for transmitting ACK / NACK information by a user equipment to data transmitted by a base station through a downlink component carrier,

2) a downlink component carrier to which the base station transmits ACK / NACK information on data transmitted through the uplink component carrier by the terminal;

3) when a base station starts a random access procedure when a terminal receives a random access preamble (RAP) transmitted through an uplink component carrier, a downlink component carrier to transmit a response thereto;

4) When the base station transmits uplink control information through a downlink component carrier, it is an uplink component carrier to which the uplink control information is applied.

10 illustrates only a 1: 1 connection setting between a downlink component carrier and an uplink component carrier, the connection configuration of 1: n or n: 1 may also be established. In addition, the index of the component carrier does not correspond to the order of the component carrier or the position of the frequency band of the component carrier.

11 is an explanatory diagram for explaining the concept of a serving cell and a neighbor cell.

Referring to FIG. 11, a system frequency band is divided into a plurality of carrier frequencies. Here, the carrier frequency means a center frequency of a cell. A cell may mean a downlink frequency resource and an uplink frequency resource. Alternatively, the cell may mean a combination of a downlink frequency resource and an optional uplink frequency resource. In addition, in general, when a CA is not considered, one cell always includes a pair of uplink frequency resources and downlink frequency resources.

Here, the serving cell 1105 refers to a cell in which a terminal is currently receiving a service. The neighbor cell refers to a cell that is geographically adjacent to the serving cell 1105 or on a frequency band. Adjacent cells using the same carrier frequency with respect to the serving cell 1105 are called intra-frequency neighbor cells 1100 and 1110. In addition, adjacent cells using different carrier frequencies based on the serving cell 1105 are referred to as inter-frequency neighbor cells 1115, 1120, and 1125. That is, as a cell using a different frequency as well as a cell using the same frequency as the serving cell, all of the cells adjacent to the serving cell may be referred to as adjacent cells.

The UE handing over from a serving cell to adjacent cells 1100 and 1110 in frequency is called an intra-frequency handover. On the other hand, the UE handover from the serving cell to the inter-frequency neighbor cells (1115, 1120. 1125) is called inter-frequency handover.

In order to transmit and receive packet data through a specific cell, the terminal must first complete configuration of a specific cell or component carrier. Herein, the configuration refers to a state in which reception of system information necessary for data transmission and reception for a corresponding cell or component carrier is completed.

For example, the configuration may include an overall process of receiving common physical layer parameters required for data transmission and reception, MAC layer parameters, or parameters required for a specific operation in the RRC layer. Accordingly, the cell or component carrier which has been set up is in a state in which packets can be immediately transmitted and received when only signaling information indicating that packet data can be transmitted is received.

Meanwhile, the cell in the setting complete state may exist in an activation or deactivation state. The reason for dividing the configuration completion state into an active state and an inactive state is to minimize the battery consumption of the UE by allowing the UE to monitor or receive the control channel (PDCCH) and the data channel (PDSCH) only when the active state is active. For sake.

Activation refers to the transmission or reception of traffic data being made or in a ready state. The UE may monitor or receive a control channel (PDCCH) and a data channel (PDSCH) of an activated cell in order to identify resources (which may be frequency, time, etc.) allocated thereto.

Deactivation means that transmission or reception of traffic data is impossible, and measurement or transmission of minimum information is possible. The terminal may not receive traffic data from the deactivated cell, but may receive system information (SI) necessary for packet reception. On the other hand, the terminal does not monitor or receive the control channel (PDCCH) and the data channel (PDSCH) of the deactivated cell in order to check the resources (which may be frequency, time, etc.) allocated thereto.

12 is an explanatory diagram illustrating the concept of a primary serving cell and a secondary serving cell.

Referring to FIG. 12, the main serving cell 1205 may transmit a security input and a non-access stratum (NAS) mobility information in an RRC connection or re-establishment state. Means one serving cell to provide. According to the capabilities of the terminal, at least one cell may be configured to form a set of serving cells together with the main serving cell 1205, and the at least one cell is called a secondary serving cell 1220.

Accordingly, the set of serving cells configured for one terminal may be configured of only one main serving cell 1205 or may consist of one main serving cell 1205 and at least one secondary serving cell 1220.

Adjacent cells 1200 and 1210 in frequency of primary serving cell 1205 and / or neighbor cells 1215 and 1225 in frequency of secondary serving 1220 each belong to the same carrier frequency. In addition, adjacent cells 1230, 1235, and 1240 between frequencies of the main serving cell 1205 and the secondary serving cell 1220 belong to different carrier frequencies.

A component carrier constituting the main serving cell 1205 is called a primary CC. Accordingly, the downlink component carrier is referred to as a downlink component carrier (DL PCC), and the uplink component carrier constituting the main serving cell 1205 is referred to as an uplink component carrier (UL PCC).

In addition, the component carrier constituting the secondary serving cell is referred to as a secondary CC (secondary CC). Therefore, in the downlink, the component carrier constituting the secondary serving cell 1220 is called a downlink sub-component carrier (DL SCC), and in the uplink, the component carrier constituting the secondary serving cell 1220 is an uplink secondary component carrier. It is called (UL SCC).

The major carrier is a component carrier in which the terminal initially establishes a connection (connection or RRC connection) with the terminal among various component carriers. The major carrier is a special component carrier that is in charge of a connection (connection or RRC connection) for signaling on a plurality of component carriers and manages UE context, which is connection information related to the terminal. In addition, the main carrier is always in the active state when the connection is made to the terminal in the RRC connected mode (RRC Connected Mode).

The subcarrier is a component carrier allocated to the terminal in addition to the major carrier, and the subcarrier is an extended carrier for the additional resource allocation in addition to the major carrier and may be divided into an active or inactive state. The main serving cell 1205 and the secondary serving cell 1220 have the following characteristics.

First, the PUCCH (Physical Uplink Control Channel) is transmitted only through the uplink of the primary serving cell 1205.

Second, the main serving cell 1205 is always active. On the other hand, the secondary serving cell 1220 is activated / deactivated according to a specific condition.

Third, RRC re-establishment only when a radio link failure (RLF, hereinafter referred to as 'RLF') is detected in the main serving cell 1205, or when the maximum number of retries of random access is exceeded. ) Is triggered. When the RLF is detected in the secondary serving 1220, the RRC reconnection is not triggered.

Fourth, the main serving cell 1205 may transmit and receive security key information.

Fifth, a random access channel (RACH) procedure is performed only through the downlink component carrier and the uplink component carrier of the main serving cell 1205. However, in the case of MSG4 (contention resolution), only the PDCCH indicating the MSG4 should be transmitted through the main serving cell 1205 and the MSG4 information may be transmitted through the main serving cell 1205 or the secondary serving cell 1220.

Sixth, non-access stratum (NAS) information is received through the main serving cell 1205.

Seventh, the main serving cell 905 always consists of a pair of a downlink major carrier and an uplink major carrier.

Eighth, a different component carrier may be configured as the main serving cell 1205 for each terminal.

Ninth, procedures such as reconfiguration, adding, and removal of the secondary serving cell 1220 may be performed by the RRC layer. In addition to the new secondary serving cell 1220, RRC signaling may be used to transmit system information of the dedicated secondary serving cell.

The technical spirit of the present invention with respect to the features of the primary serving cell 1205 and the secondary serving cell 1220 is not necessarily limited to the above description, which is merely an example and may include more examples.

The downlink component carrier may configure one serving cell, or the downlink component carrier and the uplink component carrier may be configured to configure one serving cell. However, the serving cell is not configured with only one uplink component carrier.

As described above, carrier aggregation (CA) is a method of performing wireless communication using a frequency band including a plurality of downlink component carriers and uplink component carriers between a single terminal and a base station. Looking at the contents of the carrier aggregation and the cell described above, the cell has the following characteristics for carrier aggregation.

First, a cell is defined based on a single component carrier. The cell may be configured with a pair of downlink component carriers and uplink component carriers, and may be configured only with a downlink component carrier. However, a cell cannot be configured by only an uplink component carrier.

As described above, component carriers that transmit and receive between a base station and a terminal are referred to as a serving cell. Therefore, a plurality of serving cells may exist between the base station and the terminal. Among the serving cells, the main serving cell 1205 provides security input and non-access stratum (NAS) mobility information in an RRC connection or re-establishment state. It means one serving cell. According to the capabilities of the terminal, at least one cell may be configured to form a set of serving cells together with the main serving cell 1205, and the at least one cell is called a secondary serving cell 1220. The relationship between the main serving cell and the secondary serving cell is as described above.

In addition, the number of uplink component carriers constituting the cell is less than or equal to the number of downlink component carriers. In addition, one uplink component carrier may belong to only one cell, and the uplink subcomponent carrier and the downlink subcomponent carrier constituting the secondary serving cell may be different for each terminal.

The activation / deactivation of the component carrier is equivalent to the concept of activation / deactivation of the serving cell. For example, assuming that serving cell 1 is configured with downlink component carrier 1, activation of serving cell 1 means activation of downlink component carrier 1. If the serving cell 2 assumes that the downlink component carrier 2 and the uplink component carrier 2 are configured to be configured, the activation of the serving cell 2 means the activation of the downlink component carrier 2 and the uplink component carrier 2. . The main serving cell corresponds to the major carrier and the secondary serving cell corresponds to the subcarrier.

The UE may perform an operation as shown in Table 1 according to whether the state of the uplink component carrier is activated or deactivated. In this case, since the main serving cell is always activated, the component carrier for which activation / deactivation of downlink or uplink is defined is limited to the secondary serving cell.

State of the Uplink Component Carrier  Disabled Activation



Terminal operation If the periodic sounding reference signal is configured, the terminal stops transmitting the SRS. If the periodic SRS is configured, the terminal periodically transmits the SRS. (If activated in the inactive state, restart the transmission of the SRS.) The terminal ignores all uplink grants for the uplink component carrier. The terminal receives an uplink grant for an uplink component carrier. The terminal does not consider the UE-specific search space for the uplink component carrier The terminal receives the PDCCH for the UE-specific search space for the uplink component carrier. The terminal does not transmit the PUSCH on the uplink component carrier. The UE may transmit the PUSCH on the uplink component carrier.

In general, activation / deactivation of an uplink component carrier is equally set according to whether activation or deactivation of a downlink component carrier connected to an uplink is established. Therefore, in connection with activation / deactivation, it is necessary to look at the connection configuration form of the downlink component carrier and the uplink component carrier.

Linking between an uplink component carrier and a downlink component carrier associated with activation / deactivation may be at least one of a System Information Block2 (SIB2) connection, a scheduling (sheduling) connection, and a pathloss reference connection.

In the SIB2 connection, SIB2 is information broadcast throughout the cell, and SIB2 includes a center frequency position, bandwidth information, etc. for an uplink component carrier. In the main serving cell, since the terminal receives information broadcast from the cell, all the terminals configured as the main serving cell may connect the same downlink component carrier and the uplink component carrier to configure the main serving cell. In the case of the secondary serving cell, since the base station transmits the SIB2 information exclusively through the primary serving cell, the secondary serving cell is connected by connecting a different downlink component carrier and an uplink component carrier for each UE configured as the secondary serving cell. Can be configured.

In a scheduling connection, when there is a downlink component carrier for transmitting a PDCCH for an uplink component carrier, it is considered to be connected between the uplink component carrier and the downlink component carrier.

In the path loss reference connection, when there is a downlink component carrier referenced for pathloss estimation for an uplink component carrier, it is considered to be connected between the uplink component carrier and the downlink component carrier.

In addition, the connection between the uplink component carrier and the downlink component carrier associated with the activation / deactivation can be defined in various ways, the technical idea of the present invention is not limited to the above description.

The downlink component carrier and the uplink component carrier corresponding to the main serving cell are always activated from the viewpoint of compatibility with the existing system (for example, LTE) and transmission of system information. However, the downlink sub-carrier and uplink sub-carrier corresponding to the secondary cell need not always be activated, but can be adaptively activated or deactivated according to efficient distribution and scheduling conditions of the spectrum.

As described in Table 1 above, when the secondary serving cell is activated or activated in a deactivated state, the SRS is transmitted. As described above, in general, the uplink may be connected to the downlink by any one of various connection settings such as SIB2 connection.

In the uplink, the primary serving cell is always activated, but the secondary serving cell is inactivated and activated. When the uplink secondary serving cell configured to be connected with the downlink is activated according to the activation state of the downlink cell, the uplink SRS is transmitted.

In this case, it does not matter if an uplink component carrier is used. However, even when the uplink component carrier is not used, unnecessary power consumption is consumed when an uplink cell is activated and an SRS is transmitted according to the activation of the downlink. Will bring. The uplink main serving cell is always activated, but periodically transmitting the SRS even when not in use can increase power consumption of the terminal. In this case, when the uplink component carrier is not used, the power consumption may be reduced by changing the setting of uplink SRS transmission after a predetermined time has elapsed. By adjusting the transmission of the SRS, when not using the uplink component carrier, interference with other terminals transmitting the SRS with the same resource may be reduced.

In order to change the configuration of the uplink SRS transmission after a predetermined time has elapsed, a timer (hereinafter referred to as an "SRS stop timer") for uplink SRS transmission is operated. The SRS stop timer resets the setup of the uplink SRS transmission, for example, a transmission period after a predetermined time has passed after the transmission of the uplink SRS is started.

By reducing the number of transmissions of the uplink SRS by increasing the transmission period of the uplink SRS by a predetermined time, unnecessary power consumption may be prevented. At this time, if the transmission period is set to infinity, the transmission of the uplink SRS is like stopping. In addition to simply stopping transmission, SRS is not only a reference for frequency-selective channel estimation but also used as a tracking data for uplink sync, and a basis for measuring and controlling uplink power. Therefore, in the present invention, after the SRS stop timer expires, the SRS transmission may be stopped according to the needs of the system, and the transmission period may be adjusted so that a small number of SRS transmissions are made in a long transmission period.

13 schematically illustrates an example of signaling between a base station and a terminal. An operation of a timer (hereinafter, referred to as an 'SRS stop timer') for controlling uplink SRS transmission will be described with reference to FIG. 13.

If the UE requests a radio resource control (RRC) configuration from the base station eNB (S1310), the base station configures a configuration for periodic SRS transmission for an uplink component carrier (primary component carrier or subcomponent carrier) in a downlink component. The SRC is transmitted to the UE through an RRC configuration message together with a message about the configuration of the component carrier / uplink subcomponent carrier (S1310). The setting related to the SRS transmission includes contents such as a period of the SRS transmission and a counting value of the SRS stop timer.

When the terminal completes the RRC configuration based on the received RRC configuration message, it reports this to the base station through the RRC configuration complete message (S1315). At this time, the UE starts the periodic SRS transmission based on the RRC configuration and starts the SRS stop timer.

If it is determined that the base station needs to reconfigure the RRC, the base station transmits an RRC reconfiguration message (S1320). The RRC reconfiguration message may include a message regarding configuration of a downlink subcarrier / uplink subcarrier and a reconfiguration message regarding SRS transmission.

The terminal reconfigures the RRC based on the RRC reconfiguration message and transmits an RRC reconfiguration complete message to the base station (S1320). If the RRC is reconfigured to change the setting for SRS transmission, the SRS stop timer is restarted.

14 is a diagram schematically illustrating a signal flow between a terminal and a base station in relation to RRC reconfiguration. Here, it is assumed that component carrier configuration information is included in an RRC connection reconfiguration message.

Referring to FIG. 14, when the terminal receives an RRC connection reconfiguration message for configuring an uplink component carrier from the base station (S1400), after a predetermined time, the terminal completes internal reconfiguration of the terminal according to the RRC connection reconfiguration message (S1405). .

Thereafter, a time difference may occur until the UE transmits the RRC connection reconfiguration complete message to the base station (S1410). In this case, the UE may start periodic SRS transmission upon completion of UE internal reconfiguration, that is, completion of SRS configuration, and at the same time, restart the SRS stop timer for the UL component carrier, and simultaneously transmit the reconfiguration completion message and the UL component carrier. It is also possible to restart the SRS stop timer for.

 Referring back to FIG. 13, when the terminal transmits a reconfiguration complete message to the base station (S1325), the base station transmits an uplink grant message, for example, an uplink grant for subcarrier 1 (S1330). The base station may transmit the PUSCH on the assigned subcarrier 1 (S1335).

In FIG. 13, the portion 1350 illustrated as a dotted line is a period in which a periodic SRS is transmitted, for example, the periodic SRS through the uplink subcomponent carrier 1 in FIG. 13. Therefore, the SRS stop timer is operating in this section. The SRS stop timer started 1360 together with the transmission of the RRC reconfiguration complete message is restarted 1365 after receiving an uplink grant message from the base station (S1330). If the timer expires 1370, SRS transmission is stopped. When receiving an uplink grant message from the base station (S1330), the SRS stop timer of the terminal may be started first without counting being restarted. The start of the counting or SRS stop timer indicates the start of the counting of the SRS stop timer when receiving the settings for the SRS transmission and / or the SRS stop timer from the base station for the first time. The counting or restart of the SRS stop timer indicates that the existing settings for the SRS Change and start counting the SRS stop timer based thereon.

The stopped SRS transmission may be restarted by receiving an uplink grant from the base station (S1340). In this case, the SRS stop timer is also restarted (1375). The UE receiving the uplink grant may transmit the PUDCH through the allocated subcarrier (S1345). In this case, the portion 1355 shown by a dotted line indicates a period in which the periodic SRS transmission is restarted and the SRS stop timer is also restarted.

The operation of the terminal transmitting the SRS and the SRS stop timer is further described with reference to FIG. 15. 15 is a flowchart schematically illustrating a method of operating an SRS stop timer in a terminal.

The terminal receives an SRS configuration message for the uplink component carrier from the base station (S1510). As described above, the SRS configuration message may be included in the RRC configuration message and transmitted from the base station.

The terminal completes the SRS configuration according to the SRS configuration message and periodically transmits the SRS. The UE starts counting the SRS stop timer (S1520).

In this case, as described above, the UE may start the SRS stop timer at the same time as starting the SRS transmission, or may start the SRS stop timer at the same time as transmitting a message indicating that the RRC reconfiguration procedure is completed. This is a problem regarding the setting of the SRS stop timer, for example, may be determined according to the SRS setting indicated by the base station.

The terminal determines whether a condition for restarting counting of the SRS stop timer has occurred (S1530). The restart condition of the counting varies as described below. When the condition to restart the count occurs, the counting of the SRS stop timer is restarted (S1520). If the requirement for restarting the counting of the SRS stop timer does not occur, it is determined whether a condition for stopping counting of the SRS stop timer has occurred (S1540). The stop condition of the SRS timer is various as described later. If the counting stop condition of the SRS timer occurs, readjust the SRS transmission period. In general, when the counting of the SRS timer stops, the SRS transmission also stops. If the transmission period is set to infinity, the effect corresponding to the stop of the SRS transmission can be obtained. In addition, when the counting of the SRS timer is finished, when a clear instruction from the base station or a predetermined rule is determined about how to process the SRS transmission, the setting of the SRS transmission may be adjusted accordingly.

Here, although the step of determining whether the counting restart condition of the SRS timer and the counting stop condition occurs is described as being performed as a separate step, the present invention is not limited to this, the SRS timer in the terminal If the count restart condition and the count stop condition occur, the SRS timer may immediately react to restart or stop accordingly. In addition, it was first determined whether the counting restart condition of the SRS timer occurred, and it was explained as if the counting stop condition of the SRS timer occurred. However, the present invention is not limited thereto, and it is determined whether the condition for restarting the counting of the SRS timer occurs. Before doing so, it may be determined whether a condition occurs in which the SRS timer stops counting. In addition, it may not consider the temporal precedence between determining whether the counting restart condition of the SRS timer has occurred and determining whether the counting stop condition of the SRS timer has occurred.

If the counting stop condition of the SRS stop timer does not occur, it is determined whether the counting of the SRS stop timer has expired (S1550). If the counting of the SRS stop timer expires, the SRS transmission period is adjusted.

As described above, in order to reduce unnecessary power consumption of the terminal and to reduce interference with SRS transmission of other terminals, the SRS transmission period of the terminal is increased by a predetermined time. Of course, in order to achieve only the purpose of reducing unnecessary interference between terminals, the SRS transmission period of the terminal may be reduced by a predetermined time and set to a transmission period different from that of another terminal.

In order to reduce unnecessary power consumption of the terminal and not interfere with SRS transmission of other terminals, the SRS transmission period has been described. However, the present invention is not limited thereto, and according to the purpose of system operation, the SRS is described above. It is also possible to reduce the transmission period.

The adjustment of the transmission period may be adjusted based on the absolute time, or may be adjusted in multiples of the SRS transmission period before the adjustment. For example, when the SRS stop timer expires, adjustment can be made to change the transmission period to 3ms, 5ms or the like. In addition, the transmission period may be adjusted as if the SRS is transmitted in only three cycles or only five cycles based on the transmission period before adjustment. In both cases, it is of course possible to set the transmission period to infinity or to an infinite multiple of the reference transmission period.

In the configuration of the SRS, the transmission period is generally a cell-specific parameter, but the transmission period adjusted after the expiration of the SRS stop timer may be a cell-specific parameter or a UE-specific parameter. have. In the case of adjusting the UE-specific transmission period, the SRS is transmitted according to the transmission period changed differently for each UE.

In this case, the adjusted value of the transmission period may be transmitted from the base station through RRC signaling, or may be in accordance with a predetermined protocol or rule between the base station and the terminal.

In the case of stopping the SRS transmission, instead of setting the SRS transmission period to infinity depending on whether the system supports, instead of obtaining the same effect, the SRS transmission may be immediately stopped according to a clear instruction from the base station or a predetermined protocol.

If the counting of the SRS stop timer has not expired, it is determined whether the counting restart condition or the stop condition of the SRS stop timer occurs while transmitting the SRS according to the existing transmission period until the count of the SRS stop timer expires (S1530). S1540).

After the SRS transmission period is adjusted according to the counting expiration of the SRS stop timer, the UE transmits the SRS according to the adjusted SRS transmission period (as described above, including the SRS transmission stop), and there is a reason that the SRS transmission period is readjusted. It is determined whether it has occurred (S1570). The reason why the SRS transmission period is to be re-adjusted, for example, may be considered a case in which a condition for transmitting the SRS more frequently occurs due to the reuse of the uplink component carrier. In this case, an RRC configuration message or an RRC reconfiguration message including an uplink grant message for the uplink component carrier may be received from the base station, and the SRS stop timer for the uplink SRS may be restarted (S1510). Alternatively, it may be considered that the counting of the SRS stop timer is started 1520 while the SRS is transmitted according to the rescheduled SRS transmission period or the rescheduled SRS configuration without explicit reception of the uplink grant.

If the SRS transmission is completely stopped, or the SRS configuration is removed, the terminal is turned off or stopped, or if the terminal enters the idle state, the procedure is stopped, and as described above, even for the uplink component carrier The procedure may be resumed by receiving an RRC configuration message or an RRC reconfiguration message including an SRS configuration message from the base station (S1510).

The condition of stopping and restarting the SRS timer may be caused by an indication of a base station according to a network state, or may be based on contents between an already set terminal and a base station. Interruption and restart of the SRS timer with respect to network conditions may occur in relation to other operations based on LTE. Interrupt and restart conditions of the SRS timer are described in relation to other operations on the wireless network.

<Start / restart conditions associated with uplink grants>

When the PDCCH including the uplink grant information for the uplink component carrier is received, as described in step S1330 of FIG. 13, the SRS timer starts or restarts counting.

<Start / Restart and Stop Conditions Associated with DRX>

LTE supports discontinuous reception (DRX). DRX is also based on the DRX cycle (cycle) that can vary depending on the configuration in the terminal. The UE observes downlink control signaling only in one subframe per DRX cycle, and turns off the receiving circuit and maintains a silent state in the remaining subframes. 16 is a conceptual diagram schematically illustrating a relationship between an inactivity timer and an SRS timer expiration condition of a DRX. When the inactivity timer of the DRX expires, the terminal enters a dormant state.

When the counting of the DRX inactivity timer expires, the SRS transmission is stopped even if the counting of the SRS timer does not expire. At the same time, the SRS timer is also stopped. That is, when the expiration time of the SRS timer is T1 before the expiration time of the DRX inactivity timer, the SRS timer expires normally to adjust the SRS transmission period. When the SRS timer expires at T2, the SRS transmission is stopped even if the SRS timer has not expired, and the SRS timer is also stopped or the period is adjusted to an infinite transmission cycle.

When the terminal wakes up briefly during the idle state and needs to transmit and receive necessary information, a short cycle is used in addition to the above-described cycle. This short "on duration" period is also controlled by the on duration timer.

When the counting of the on duration timer expires, the SRS timer also stops or the period is adjusted to an infinite transmission period. FIG. 17 is a diagram schematically illustrating a relationship between an on duration time T _on and an SRS timer operation. To the on-duration timer relationship is also similar to the relationship between the above-mentioned activity timer, even if it does not reach the expiration time of the SRS timer (T _exp), the beginning of the On Duration period (T _ini, i.e. counting the start of the on-duration timer) and Together, the SRS timer can be started or restarted, and the SRS timer can be stopped with the end of the on duration period (T _off , ie counting the duration of the on duration timer).

In addition, with regard to the on-duration time, it may be considered to operate the SRS stop timer in such a manner that the SRS stop timer is not operated while transmitting the SRS according to the SRS setting determined during the on duration.

<Restart and stop conditions related to enable / disable signaling>

As described above, in connection with activation / deactivation, a link between an uplink component carrier and a downlink component carrier, such as a System Information Block2 (SIB2) connection, a sheduling connection, and a pathloss reference connection, is performed. Is set. Since the subcarrier or the main serving cell configured by the subcarrier is always activated, it is the case of the subcarrier that the activation / deactivation is a problem due to the connection configuration with the downlink component carrier.

When the activation message for the downlink sub-carrier (or downlink secondary serving cell) is received, the SRS stop timer for the uplink sub-carrier connected to the same secondary serving cell as the corresponding downlink sub-carrier restarts counting. do.

When the deactivation message for the downlink sub-carrier (or downlink secondary serving cell) is received, the SRS stop timer for the uplink sub-carrier connected to the same secondary serving cell as the corresponding downlink sub-carrier stops counting. do.

<Start / Restart and Stop Conditions Related to SRS Settings>

When the periodic SRS for the uplink subcomponent carrier is initially set, the SRS stop timer of the corresponding uplink subcomponent carrier is also started. Initial configuration of the SRS may be made based on, for example, an SRS configuration message from the base station. In this case, as described above, the SRS configuration message may be included in the RRC configuration message and transmitted from the base station.

For a UL subcarrier that periodically transmits an SRS, if the configuration of the SRS is changed, the SRS stop timer for the corresponding UL subcarrier is restarted.

When the configuration of the SRS is released for an uplink sub-carrier that periodically transmits the SRS, the SRS stop timer for the uplink sub-component carrier is stopped.

<Stop conditions associated with RRC reconfiguration>

If the RRC reset message includes a component carrier remove message for the uplink subcomponent carrier, the SRS stop timer for the uplink subcomponent carrier is stopped.

Restart conditions associated with aperiodic SRS

In general, the terminal may be configured to transmit the SRS with a certain period, but as described above, there is an aperiodic SRS (Aperiodic SRS) as one of the new schemes considered in LTE-A. In the case of A-SRS, since the UE can transmit the SRS aperiodically, resources can be used more efficiently than when the SRS is periodically transmitted. Since the transmission of the A-SRS is aperiodic, the terminal may transmit the A-SRS only when the base station instructs the transmission of the SRS to the terminal. In addition, the base station should inform the terminal of the information on the time / frequency resources for the terminal to transmit the A-SRS. The information on the time / frequency resource for transmitting the A-SRS by the terminal may be transmitted to the terminal at the same time as the message indicating the transmission of the A-SRS, or may be transmitted to the terminal before.

If the SRS transmission indication received from the base station or the information on the SRS transmission includes the A-SRS triggering message for the uplink sub-carrier, the SRS stop timer for the uplink sub-carrier is restarted.

<Restart conditions related to HARQ retransmission>

When the HARQ NACK message for the PUSCH is received and HARQ retransmission is performed, the SRS timer for the uplink subcomponent carrier of the corresponding PUSCH is restarted.

If HARQ retransmission is performed because the HARQ ACK message for the PUSCH is not received, the SRS timer for the uplink sub-carrier on which the corresponding PUSCH is transmitted is restarted.

In this case, HARQ retransmission may be performed by receiving an uplink grant or may be performed without an uplink grant. When HARQ retransmission is performed without an uplink grant, the SRS stop timer is restarted simultaneously with the transmission of the PUSCH. When the UE receives an uplink grant for HARQ retransmission, the SRS stop timer may be restarted with the reception of an uplink grant with respect to an uplink sub-carrier for which the HARQ retransmission is performed, and the SRS stops with the transmission of the PUSCH. You can also restart the timer.

<Restart Conditions Associated with Semi-Persistent Scheduling>

The base station may also fix the amount and location of radio resources semi-statically through Semi-Persistent Scheduling (SPS). In this case, the base station does not transmit scheduling information every subframe, but transmits only ACK / NACK and data for data transmitted by the terminal. However, the base station transmits a message corresponding to the case where the amount and location of semi-fixed allocated resources change.

When the terminal to which the SPS is applied receives the ACK / NACK from the base station, the terminal restarts the SRS stop timer. In addition, when the terminal to which the SPS is applied receives the PDCCH including the new uplink grant, the UE transmits the PUSCH according to the changed configuration and restarts the SRS stop timer.

Although various start / restart and stop conditions of the SRS timer according to the present invention have been described in connection with operations on LTE, the present invention is not limited thereto. The start / restart and stop conditions of the SRS timer may be variously determined for efficient transmission and system operation of the SRS, and may be changed by an instruction of the base station or a predetermined rule predetermined between the base station and the terminal.

18 is a flowchart schematically illustrating operation at a base station in relation to the present invention.

The base station transmits an SRS configuration message for the uplink component carrier (S1810). The SRS configuration message may be included in an RRC configuration message or an RRC reconfiguration message.

The terminal transmits the SRS according to the received SRS configuration message and starts the SRS stop timer. Accordingly, the base station receives the SRS periodically according to a given transmission period from the terminal. When the SRS stop timer expires, the SRS adjusts the transmission period. The SRS is transmitted to the base station according to the adjusted period (including transmission stop as described above).

When the base station determines that the uplink channel information for generating an uplink grant has not been secured for the uplink sub-carrier because the SRS stop timer expires and the SRS transmission period is adjusted or the SRS transmission is stopped, It is determined whether A-SRS (Aperiodic SRS) triggering information needs to be transmitted to the UE (S1820). Since the transmission of the A-SRS is aperiodic, the base station should indicate the transmission of the SRS to the terminal or inform the information related to the transmission of the SRS.

If it is determined that the base station needs to transmit A-SRS triggering information to the terminal for A-SRS transmission, the A-SRS triggering message is transmitted to the terminal (S1830). The terminal receives the A-SRS triggering message, and transmits the A-SRS to the base station. The base station transmits an uplink grant message to the terminal based on the uplink channel information received by the A-SRS (S1840). When the terminal receives the uplink grant message, since this corresponds to the restart condition of the above-mentioned SRS stop timer, the SRS stop timer is restarted according to the changed setting.

19 is a block diagram schematically illustrating the concept of a base station and a terminal device according to the present invention.

At the base station 1900, the RF unit 1930 receives a signal through an uplink channel and transmits a signal through a downlink channel. To support a multi-component carrier system, the base station 1900 includes a multiple antenna system 1940. The processor 1910 processes a signal to be received or transmitted through the RF unit 1930. In the present invention, the processor 1910 may include the SRS configuration message or the SRS stop timer counting value for controlling the SRS transmission, including the RRC configuration message or the RRC reconfiguration message, and transmit the same through the RF unit 1930. The memory 1920 stores system information or control information necessary for system operation, or information reported from each terminal, such as channel state information.

 In the terminal 1950, the RF unit 1970 and the antenna unit 1960 receive signals transmitted from the base station 1900 and transmit a signal to the base station 1900. The processor 1990 processes a signal received through the RF unit 1970 or a signal to be transmitted through the RF unit 1970. For example, the processor 1990 may transmit the SRS or the A-SRS every predetermined transmission period according to the SRS configuration message received from the base station 1900.

The processor 1990 may include an SRS stop timer 1995 for controlling SRS transmission. The SRS stop timer 1995 starts counting with the transmission of the SRS. When the count expires after a predetermined time, the SRS stop timer 1995 re-adjusts the SRS transmission period. In this case, the adjustment of the SRS transmission period may include increasing the SRS transmission period by a predetermined time, increasing the integer number of times by a previous period, or stopping the transmission by setting the period to infinity.

Although FIG. 19 illustrates that the processor 1990 includes an SRS stop timer 1995, the present invention is not so limited, and an expression of the present specification that the processor 1990 includes an SRS stop timer 1995 is described in the following description. The stop timer 1995 includes both the case where the processor is controlled by the processor as a separate unit from the processor 1990, and the case where the SRS stop timer 1995 processes the process of controlling the SRS transmission by itself as an independent unit.

The memory 1980 stores system information or control information, and stores various pieces of information transmitted by the base station 1900 as necessary.

In the exemplary system described above, the methods are described based on a flowchart as a series of steps or blocks, but the invention is not limited to the order of steps, and certain steps may occur in a different order or concurrently with other steps than those described above. Can be. In addition, those skilled in the art will appreciate that the steps shown in the flowcharts are not exclusive and that other steps may be included or one or more steps in the flowcharts may be deleted without affecting the scope of the present invention.

The above-described embodiments include examples of various aspects. While it is not possible to describe every possible combination for expressing various aspects, one of ordinary skill in the art will recognize that other combinations are possible. Accordingly, it is intended that the invention include all alternatives, modifications and variations that fall within the scope of the following claims.

Claims (12)

As a transmission method of SRS (Sounding Reference Signal) in a multi-component carrier system,
Starting stop counting of SRS transmission for the uplink component carrier based on the SRS configuration message for the uplink component carrier; And
And rescheduling a period of the SRS transmission when the stop counting of the SRS transmission expires. The method of claim 1, wherein the readjustment of the SRS transmission period includes stopping the SRS transmission. The method of claim 1, wherein the transmission method of the SRS,
After starting the stop counting of the SRS transmission, determining whether the requirement of restarting the stop counting of the SRS transmission is satisfied;
If the requirement is met, the SRS transmission method characterized in that the stop counting of the SRS transmission is restarted. The method of claim 1, wherein the transmission method of the SRS,
Determining whether a requirement for stopping stop counting of the SRS transmission is satisfied after initiating stop counting of the SRS transmission and before the stop counting of the SRS transmission expires;
If it meets the requirement, SRS transmission method characterized in that stop the stop counting of the SRS transmission. A wireless terminal apparatus for transmitting a sounding reference signal (SRS) in a multi-component carrier system,
An RF unit for receiving a signal through a downlink channel and transmitting a signal through an uplink channel;
A processor for processing a signal received through the RF unit and a signal to be transmitted; And
A memory storing operation information including system information and / or control information necessary for system operation;
The processor includes a timer for controlling the transmission of the SRS. The wireless terminal apparatus of claim 5, wherein the processor readjusts the transmission period of the SRS when the counting of the timer expires. The method of claim 5, wherein the processor determines whether after the start of counting the timer, a requirement of restarting the counting is satisfied.
And restarting the timer when the requirement is satisfied. The method of claim 5, wherein the processor determines whether after the start of counting the timer, a requirement to stop the counting is satisfied.
And stop the timer when the requirement is satisfied. A method of receiving SRS (Sounding Reference Signal) in a multi-component carrier system,
Receiving an SRS based on an SRS configuration message for an uplink component carrier; And
Determining whether to transmit a change message for setting contents of the SRS configuration message;
The SRS setup message includes a setup value for stop counting of SRS transmission,
And wherein the change message comprises an implicit or explicit message for restarting or stopping the stop counting of the SRS transmission. The method of claim 9, wherein the SRS configuration message,
And transmitting the SRS setting message and changing the SRS transmission period by a predetermined time after a predetermined time has elapsed. The method of claim 9, wherein the SRS receiving method is
The change message transmitted after a predetermined time elapses after transmitting the SRS configuration message includes changing the transmission period of the SRS by a predetermined time. A receiving device for receiving an SRS of a multi-component carrier system,
An RF unit for receiving a signal through an uplink channel and transmitting a signal through a downlink channel;
A processor for processing a signal received through the RF unit and a signal to be transmitted; And
A memory storing operation information including system information and / or control information necessary for system operation;
The processor is characterized in that for transmitting the SRS configuration information for controlling the transmission of the SRS through the RF unit.

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