WO2014017792A1 - Device and method for performing uplink synchronization in multi-carrier system - Google Patents

Description

Apparatus and method for performing uplink synchronization in a multi-component carrier system

The present invention relates to an apparatus and method for performing uplink synchronization in wireless communication, and more particularly, to an apparatus and method for determining the validity of a time alignment value in a carrier aggregation system supporting multiple component carriers. It is about.

In a typical wireless communication system, only one carrier is mainly considered even if the bandwidth between uplink and downlink is set differently. In the 3rd Generation Partnership Project (3GPP) long term evolution (LTE), the number of carriers constituting uplink and downlink is one based on a single carrier, and the bandwidth of the uplink and the downlink are common. Are symmetrical to each other.

A multiple component carrier system refers to a wireless communication system capable of supporting carrier aggregation. Carrier aggregation is a technique for efficiently using fragmented small bands in order to combine physically non-continuous bands in the frequency domain and to have the same effect as using logically large bands.

The terminal goes through a random access procedure to access the network. In a single carrier system, random access is performed using one carrier. However, as a multi-component carrier system is introduced, random access can be implemented through a plurality of component carriers.

The random access procedure may be divided into a contention based random access procedure and a non-contention based random access procedure. The biggest difference between the contention-based random access procedure and the non- contention-based random access procedure is whether a random access preamble is designated as dedicated to one UE. In the non-contention based random access procedure, since the terminal uses a dedicated random access preamble designated only for itself, contention (or collision) with other terminals does not occur. Here, contention refers to two or more terminals attempting a random access procedure using the same random access preamble through the same resource. In the contention-based random access procedure, there is a possibility of contention because the terminal uses a random access preamble selected by the UE.

According to the related art, when a validity of a timing alignment value is lost in a specific secondary serving cell, a criterion for determining this has not yet been presented. Therefore, an accurate criterion for determining the loss of validity and, in the case of the loss of validity, a procedure for recovering the inconsistency of the uplink time synchronization should be defined.

An object of the present invention is to provide an apparatus and method for performing uplink synchronization in a multi-component carrier system.

Another object of the present invention is to provide an apparatus and method for checking the validity of a time alignment value in a multi-component carrier system.

Another object of the present invention is to provide an apparatus and method for determining the validity of a time alignment value using a downlink timing value.

Another technical problem of the present invention is to provide an apparatus and method for transmitting a problem report on a main serving cell when the validity of a time alignment value is lost.

Another technical problem of the present invention is to provide a message structure of a problem report and an apparatus and method for transmitting and receiving a message.

Another technical problem of the present invention is to provide an apparatus and method for performing an operation of correcting a time alignment value.

Another technical problem of the present invention is to provide an apparatus and method for correcting a time alignment value in consideration of time and a correction range.

According to an aspect of the present invention, there is provided a method of performing uplink synchronization by a terminal supporting a plurality of CCs. The method includes determining that a condition for losing validity of a time alignment value used for adjusting an uplink time of a secondary serving cell is satisfied, and an uplink grant for the terminal is currently transmitted by a TTI. confirming that it is not indicated for a time interval, transmitting a random access preamble to a base station on a primary serving cell configured in the terminal, random including an uplink grant for the terminal Receiving an access response message from the base station, and using the uplink resources indicated by the uplink grant, a problem report indicating an index of a timing alignment group (TAG) to which the secondary serving cell belongs; and transmitting a problem report to the base station.

The validity loss condition may be a difference between a downlink timing value T1 measured by the terminal at a first time point and a downlink timing value T2 measured at a second time point or more.

The T1 is measured within a period during which all serving cells in the TAG are changed to inactive state after it is determined to be inactivated, and the T2 is measured within a period during which at least one serving cell of the TAG is changed to an activated state after it is determined to be activated. Can be.

The effective threshold value may be calculated using a maximum range Tq in which the terminal can correct the error of the uplink time by itself as a variable.

The Tq = k * Ts, k is determined by any one of 2, 4, 8, 16 according to the downlink bandwidth, Ts is a sampling period.

The valid threshold may be information set by the base station and informed to the terminal.

The problem report is a medium access control (MAC) control element, the MAC control element is included in a MAC protocol data unit (PDU), and the MAC PDU is a logical channel identifier: And a MAC subheader including an LCID) field, wherein the LCID field may indicate that the MAC control element is for the problem report.

According to another aspect of the present invention, in a wireless communication system supporting a plurality of CCs, a terminal for performing uplink synchronization is provided. The terminal confirms that the validity loss condition of the time alignment value used for adjusting the uplink time of the secondary serving cell, confirms that the uplink grant for the terminal is not indicated for the current TTI, Random access response message including a random access processor for randomly selecting one preamble sequence from a random access preamble sequence set, a transmitter for transmitting a random access preamble according to the selected preamble sequence to the base station, and an uplink grant for the terminal It includes a receiving unit for receiving from the base station.

The transmitter transmits a problem report indicating an index of a time alignment group (TAG) to which the secondary serving cell belongs by using an uplink resource indicated by the uplink grant, to the base station.

The validity confirming unit may confirm that the difference between the downlink timing value T1 measured at the first time point and the downlink timing value T2 measured at the second time point is equal to or greater than an effective threshold value.

The validity confirming unit measures the T1 within a period during which all serving cells in the TAG are deactivated after being determined to be deactivated, and a period during which at least one serving cell of the TAG is changed to be activated after being determined to be activated. The T2 can be measured within.

The validity confirming unit may calculate the validity threshold using a maximum range Tq that the terminal can correct for the error of the uplink time by itself as a variable.

The Tq = k * Ts, k is determined by any one of 2, 4, 8, 16 according to the downlink bandwidth, Ts is a sampling period.

The receiving unit may receive the valid threshold value from the base station.

The transmitting unit transmits the problem report in the form of a MAC control element, wherein the MAC control element is included in a MAC PDU, and the MAC PDU includes a MAC subheader including a logical channel identifier (LCID) field. The LCID field may indicate that the MAC control element is for the problem report.

By ensuring the time alignment value and checking the validity, it is possible to block uplink interference that may occur due to inconsistency of uplink time synchronization, and to solve a performance degradation problem due to uplink interference.

1 shows a wireless communication system to which the present invention is applied.

2 shows an example of a protocol structure for supporting multiple carriers to which the present invention is applied.

3 shows an example of a frame structure for multi-carrier operation to which the present invention is applied.

4 is a diagram briefly illustrating a concept of a multi-carrier system to which the present invention is applied.

5 shows an example of a cell deployment scenario to which the present invention is applied.

6 is a view for explaining the condition of the loss of validity according to an embodiment of the present invention.

7 is a view for explaining the condition of the loss of validity according to another embodiment of the present invention.

8 is a view for explaining the condition of the loss of validity according to another embodiment of the present invention.

9 is a view for explaining the condition of the loss of validity according to another embodiment of the present invention.

10 is a view for explaining the condition of loss of validity according to still another embodiment of the present invention.

11 is a block diagram illustrating a MAC PDU including a problem report according to an embodiment of the present invention.

12 is a structure of a subheader including an LCID field indicating a problem report according to an embodiment of the present invention.

13 illustrates a MAC control element for problem reporting according to an embodiment of the present invention.

14 illustrates a MAC control element for problem reporting according to another example of the present invention.

15 is a structure of a subheader including an LCID field indicating a problem report according to another embodiment of the present invention.

16 is a flowchart illustrating a method of determining the validity of a time alignment value according to an embodiment of the present invention.

17 is a flowchart illustrating a method of determining the validity of a time alignment value according to another embodiment of the present invention.

18 is a flowchart illustrating a method for providing validity of a time alignment value by a base station according to an embodiment of the present invention.

19 is a flowchart illustrating an operation between a terminal and a base station for determining validity of a time alignment value according to an embodiment of the present invention.

20 is a block diagram illustrating a terminal and a base station according to an embodiment of the present invention.

Hereinafter, some embodiments will be described in detail with reference to the accompanying drawings. 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 though they are shown in different drawings. In addition, in describing the embodiments of the present specification, when it is determined that a detailed description of a related well-known configuration or function may obscure the gist of the present specification, the detailed description thereof will be omitted.

In addition, the present specification describes a wireless communication network, the operation performed in the wireless communication network is performed in the process of controlling the network and transmitting data in the system (for example, the base station) that is in charge of the wireless communication network, or the corresponding wireless Work may be done at the terminal coupled to the network.

1 shows a wireless communication system to which the present invention is applied.

Referring to FIG. 1, the wireless communication system 10 is widely deployed to provide various communication services such as voice and packet data. The wireless communication system 10 includes at least one base station (BS) 11 and a repeater (not shown in the figure). Each base station 11 provides a communication service for specific cells 15a, 15b, and 15c. The cell can in turn be divided into a number of regions (called sectors).

In general, service providers install wireless base stations to support a desired service area by installing multiple base stations. However, in some regions, there are regions where wireless service is not properly performed due to terrain conditions. This is called a shadow area, and a repeater is used to remove the shadow area.

Repeaters can be divided into two types: analog repeaters and digital repeaters. In the case of the downlink of the analog repeater, the base station converts all the processed digital signals to analog and transmits them to the analog repeater by wire or wirelessly. The analog repeater, which receives the signal transmitted by the base station, amplifies the received signal and transmits the signal to the service area where the terminal to be serviced by the analog repeater exists. At this time, the noise generated in the base station and the interference and noise generated in the base station-relay period wired / wireless channel are amplified together with the signal to be transmitted.

Therefore, there is a disadvantage that the signal quality is always deteriorated compared to the state transmitted by the first base station. The same disadvantage occurs in the case of uplink. In addition, in the uplink, signals transmitted from a plurality of terminals in a service area of an analog repeater are received by the analog repeater, and the analog repeater simply amplifies the plurality of signals and transmits the signals to the base station via wired / wireless. Also, the base station cannot distinguish each terminal from the analog signal. Accordingly, the base station cannot distinguish which of the signals received in the uplink is a signal received through an analog repeater and which signal is a signal directly received from the terminal.

In the case of a digital repeater, in order to compensate for the disadvantages of the analog repeater, the base station transmits all the processed digital signals as they are to the digital repeater by wire (usually optical cable). Digital repeaters are also called Remote Radio Heads (RRHs) to distinguish them from analog repeaters. Since the base station transmits data from the digital state to the digital repeater, the base station can remove the effects of interference and noise generated from the analog base station, and the base station can distinguish the signal from the digital repeater and the signal received from the base station directly. In the present invention, the analog repeater is referred to as a repeater or repeater.

The network (or operator) has the right to install a repeater. Therefore, the network must know the location of the repeater. However, many wireless operators may leave information on the network after installing a plurality of repeaters in order to disconnect a service in a shaded area of a cell or to expand a cell service area, but this may not be the case. That is, depending on the type of network or wireless service provider, there may be a case where network equipment uses location information of a repeater and a case where it is not. In order for network devices to obtain the location information of repeaters, information must be obtained manually or managed through protocols such as Operations & Maintenance (O & M) or OAM (Operations, Administration and Maintenance). In addition, repeater-related information may be stored in a specific network maintenance server installed for each wireless service provider, and location information may be transmitted to network equipment including a base station using a network protocol specialized for each wireless service provider.

In addition, in a wireless communication system such as LTE, the following methods are used to determine the location information of the terminal.

1) A method for identifying a base station that is currently communicating with a terminal to determine whether the base station exists within the service area of the base station. This method has the advantage that the network can determine the location of the terminal without additional signaling, but can only know the approximate location of the terminal.

2) A method of determining the distance based on the channel state. According to this method, the base station checks the channel state information transmitted from the terminal, and if the channel state is good, the terminal is determined to be close to the base station, and if the channel state information is not good, the base station is determined to be far from the base station. This method can estimate the distance from the base station at the location identified in method 1), but can only determine the approximate location since the direction is unknown.

3) A method of estimating the position of a terminal in a two-dimensional plane using triangulation. According to this method, the terminal receives a georeferenced signal transmitted in cells existing at three or more physically separated points, and estimates the distance between the terminal and each cell using the signal strength of the received signals. The terminal obtains a point where three concentric circles having the estimated distance as a radius meet based on triangulation, and measures the point as the position of the terminal. This method has the advantage of identifying the exact one position of the x-y coordinate, but the additional reference signal for position estimation must be defined in the downlink. In addition, since the terminal can determine the location information, the terminal should transmit the location information to the base station to obtain the location information in the network.

4) A method of estimating the position of the terminal using higher layer signaling. The network collects information for estimating the location of the terminal using information for establishing a connection between the terminal and the network, information provided by the terminal, or strength of a reference signal transmitted by the terminal. And using this, the network estimates the location. This method can obtain the position of the terminal in real time in the network without additional reference signal for downlink position estimation.

5) A method for transmitting location information acquired using a location estimation device (for example, GPS) embedded in a terminal to a network. This method has the advantage of not only the x-y coordinates but also the altitude of method 3), but it requires additional equipment for location estimation such as satellite and GPS receiver. In addition, as in method 3), the terminal should transmit the location information to the base station to obtain the location information in the network.

Methods of determining the location information of the terminal as described above are merely exemplary and are not necessarily limited to the above methods.

A user equipment (UE) 12 may be fixed or mobile, and may have a mobile station (MS), a mobile terminal (MT), a user terminal (UT), a subscriber station (SS), a wireless device, or a PDA. (personal digital assistant), wireless modem (wireless modem), a handheld device (handheld device) may be called other terms. The base station 11 may be called in other terms such as an evolved-NodeB (eNB), a base transceiver system (BTS), an access point, an femto base station, a home nodeB, a relay, and the like. . 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 and femtocells.

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 downlink, the transmitter may be part of the base station 11 and the receiver may be part of the terminal 12. In uplink, the transmitter may be part of the terminal 12 and the receiver may be part of the base station 11. There is no limitation on the multiple access scheme applied to the wireless communication system. Code Division Multiple Access (CDMA), Time Division Multiple Access (TDMA), Frequency Division Multiple Access (FDMA), Orthogonal Frequency Division Multiple Access (OFDMA), Single Carrier-FDMA (SC-FDMA), OFDM-FDMA, OFDM-TDMA For example, various multiple access schemes such as OFDM-CDMA may be used. 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.

Carrier aggregation (CA) supports a plurality of carriers, also referred to as spectrum aggregation or bandwidth aggregation. Individual unit carriers bound by carrier aggregation are called component carriers (CCs). 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 component carriers are allocated as granularity in a carrier unit having a 20 MHz bandwidth, a bandwidth of up to 100 MHz may be supported.

Carrier aggregation may be divided into contiguous carrier aggregation between continuous component carriers in the frequency domain and non-contiguous carrier aggregation between discontinuous component carriers. 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.

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

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

2 shows an example of a protocol structure for supporting multiple carriers to which the present invention is applied.

Referring to FIG. 2, a medium access control (MAC) entity 210 manages a physical layer 220 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 220 may operate in a time division duplex (TDD) and / or a frequency division duplex (FDD).

There are several physical control channels used in the physical layer 220. The physical downlink control channel (PDCCH) informs the UE of resource allocation of a paging channel (PCH) and downlink shared channel (DL-SCH) and hybrid automatic repeat request (HARQ) information related to the DL-SCH. 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 PDCCHs and is transmitted every subframe. PHICH (physical Hybrid ARQ Indicator Channel) carries a HARQ ACK / NAK signal 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. The physical uplink shared channel (PUSCH) carries an uplink shared channel (UL-SCH). A physical random access channel (PRACH) carries a random access preamble.

3 shows an example of a frame structure for multi-carrier operation to which the present invention is applied.

Referring to FIG. 3, a radio frame consists of 10 subframes. The subframe includes a plurality of OFDM symbols. Each carrier may have its own control channel (eg, PDCCH). The multicarriers may or may not be adjacent to each other. The terminal may support one or more carriers according to its capability.

The component carrier may be divided into a primary component carrier (PCC) and a secondary component carrier (SCC) according to activation. The major carriers are always active carriers, and the subcarrier carriers are carriers that are activated / deactivated according to specific conditions. Activation refers to the transmission or reception of traffic data being made or in a ready state. Deactivation means that transmission or reception of traffic data is impossible, and measurement or transmission of minimum information is possible. The terminal may use only one major carrier, or may use one or more subcomponent carriers together with the major carrier. The terminal may be assigned a major carrier and / or sub-carrier carrier from the base station.

4 is a diagram briefly illustrating a concept of a multi-carrier system to which the present invention is applied.

Referring to FIG. 4, in downlink, downlink component carriers D1, D2, and D3 are aggregated as an example, and uplink component carriers U1, U2, and U3 are aggregated. Di is an index of a downlink component carrier, and Ui is an index of an uplink component carrier (i = 1, 2, 3). Each index does not coincide with the order of the component carriers or the position of the frequency band of the component carriers.

On the other hand, at least one downlink component carrier may be configured as a major carrier and the rest of the sub-carrier. In addition, at least one uplink component carrier may be configured as a major carrier wave, and the rest may be configured as a secondary component carrier. For example, D1 and U1 are major carrier waves, and D2, U2, D3 and U3 are subcomponent carriers.

In this case, the index of the major carrier may be set to 0, and one of the other natural numbers may be the index of the subcarrier. In addition, the index of the downlink / uplink component carrier may be set to be the same as the index of the component carrier (or serving cell) including the corresponding downlink / uplink component carrier. As another example, only the component carrier index or the subcarrier index may be set, and the uplink / uplink component carrier index included in the component carrier may not exist.

In the FDD system, the downlink component carrier and the uplink component carrier may be configured to be 1: 1. For example, D1 is connected to U1, D2 is U2, and D3 is U1 1: 1. The terminal establishes a connection between the downlink component carriers and the uplink component carriers through system information transmitted by a logical channel BCCH or a terminal-specific RRC message transmitted by a DCCH. This connection is called a system information block 1 (SIB1) connection or a system information block 2 (SIB2) connection. Each connection configuration may be set cell specific or UE specific. As an example, the major carrier may be cell-specific and the sub-carrier may be terminal-specific.

Here, the downlink component carrier and the uplink component carrier, as well as 1: 1 connection configuration, it is also possible to establish a connection configuration of 1: n or n: 1.

The downlink component carrier corresponding to the primary serving cell is referred to as DL PCC, and the uplink component carrier corresponding to the primary serving cell is called UL PCC. In the downlink, a component carrier corresponding to a secondary serving cell is called a downlink sub-component carrier (DL SCC), and in the uplink, a component carrier corresponding to a secondary serving cell is an uplink sub-component carrier. It is called (UL SCC). Only one DL CC may correspond to one serving cell, and a DL CC and a UL CC may correspond together.

The primary serving cell refers to one serving cell that provides security input and NAS mobility information in an RRC connection or re-establishment state. 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, wherein the at least one cell is called a secondary serving cell. The set of serving cells configured for one terminal may consist of only one main serving cell or one main serving cell and at least one secondary serving cell.

In the carrier system, communication between the terminal and the base station is performed through the DL CC or the UL CC, which is equivalent to the communication between the terminal and the base station through the serving cell. For example, in the method of performing random access according to the present invention, transmitting a preamble by using a UL CC may be regarded as a concept equivalent to transmitting a preamble using a main serving cell or a secondary serving cell. In addition, the UE receiving the downlink information by using the DL CC, can be seen as a concept equivalent to receiving the downlink information by using the primary serving cell or secondary serving cell.

The main serving cell and the secondary serving cell have the following characteristics.

First, the primary serving cell is used for transmission of the PUCCH. On the other hand, the secondary serving cell may not transmit the PUCCH, but may transmit some control information of the information in the PUCCH through the PUSCH.

Second, the main serving cell is always activated, while the secondary serving cell is a carrier that is activated / deactivated according to a specific condition. The specific condition may be a case where the activation / deactivation MAC control element message of the base station is received or the deactivation timer in the terminal expires.

Third, when the primary serving cell experiences RLF, RRC reconnection is triggered, but when the secondary serving cell experiences RLF, RRC reconnection is not triggered. Radio link failure occurs when downlink performance is maintained below a threshold for more than a predetermined time, or when the RACH has failed a number of times above the threshold.

Fourth, the main serving cell may be changed by a security key change or a handover procedure accompanying the RACH procedure. However, in the case of a content resolution message, only the PDCCH indicating the CR should be transmitted through the main serving cell, and the CR information may be transmitted through the main serving cell or the secondary serving cell.

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

Sixth, the main serving cell always consists of a pair of DL PCC and UL PCC.

Seventh, a different CC may be set as a primary serving cell for each terminal.

Eighth, procedures such as reconfiguration, adding, and removal of the secondary serving cell may be performed by the radio resource control (RRC) layer. In addition of a new secondary serving cell, RRC signaling may be used to transmit system information of a dedicated secondary serving cell.

Ninth, the main serving cell is a PDCCH (for example, downlink allocation information allocated to a UE-specific search space) configured to transmit control information only to a specific terminal in an area for transmitting control information. Or uplink grant information) and a PDCCH (for example, system information (for example, system information) allocated to a common search space configured for transmitting control information to all terminals in a cell or a plurality of terminals meeting specific conditions). SI), random access response (RAR), and transmit power control (TPC). On the other hand, the secondary serving cell may be set only a terminal-specific search space. That is, since the terminal cannot identify the common search space through the secondary serving cell, the terminal cannot receive control information transmitted only through the common search space and data information indicated by the control information.

Among the secondary serving cells, a secondary serving cell in which a common search space (CSS) can be defined may be defined. Such a secondary serving cell is referred to as a special secondary serving cell (special SCell). The special secondary serving cell is always configured as a scheduling cell during cross carrier scheduling. In addition, the PUCCH configured in the main serving cell may be defined for the special secondary serving cell.

The PUCCH for the special secondary serving cell may be fixedly configured when the special secondary serving cell is configured, or the base station may be allocated (configured) or released by RRC signaling (RRC reconfiguration message) when the base station is reconfigured for the secondary secondary cell. have.

In addition, the base station may configure one special secondary serving cell of the plurality of secondary serving cells, or may not configure a special secondary serving cell. The reason for not configuring the special secondary serving cell is because it is determined that CSS and PUCCH need not be set. For example, if it is determined that the contention-based random access procedure does not need to be performed in any secondary serving cell, or it is determined that the current capacity of the PUCCH of the primary serving cell is sufficient, it is not necessary to set the PUCCH for the additional secondary serving cell. Corresponding.

In a wireless communication environment, a propagation delay occurs while a radio wave propagates at a transmitter and is transmitted from a receiver. Therefore, even if both transmitters and receivers know exactly the time when radio waves propagate in the transmitter, the time that a signal arrives at the receiver is affected by the transmission / reception period distance, the surrounding radio wave environment, and changes with time when the receiver moves. If the receiver does not know exactly when the signal transmitted by the transmitter is received, even if the signal reception fails or is received, the receiver receives the distorted signal and communication is impossible.

Therefore, in a wireless communication system, synchronization between a base station and a terminal must be made in advance in order to receive an information signal regardless of downlink and uplink. There are various types of synchronization, such as frame synchronization, information symbol synchronization, and sampling period synchronization. Sampling period synchronization is the most basic synchronization to be obtained in order to distinguish physical signals.

Downlink synchronization acquisition is performed in the terminal based on the signal of the base station. The base station transmits a specific signal mutually promised to facilitate downlink synchronization acquisition in the terminal. The terminal should be able to accurately discern the time when the specific signal transmitted from the base station is transmitted. In the case of downlink, since one base station simultaneously transmits the same synchronization signal to a plurality of terminals, the terminals can independently acquire synchronization.

In the case of uplink, the base station receives signals from a plurality of terminals. When the distance between each terminal and the base station is different, the signals received by the base station have a different transmission delay time. When transmitting uplink information based on downlink synchronization acquired by each terminal, the base station receives information of each terminal at different times. In this case, the base station cannot obtain synchronization based on any one terminal. Therefore, uplink sync acquisition requires a different procedure from downlink.

A random access procedure is an embodiment performed for uplink synchronization acquisition. During the random access procedure, the terminal acquires uplink synchronization by adjusting the uplink time based on a time alignment value provided by the base station. The time alignment value may be called a timing advance value. After a predetermined time has elapsed after acquiring the uplink synchronization based on the time alignment value, it is determined whether the obtained uplink synchronization is valid. To this end, the terminal defines a time alignment timer (TAT) that is configurable by the base station and must start an uplink synchronization acquisition procedure upon expiration. If the time alignment timer is in operation, the terminal and the base station determine that the uplink synchronization with each other. If the time alignment timer expires or does not operate, the UE and the base station report that they are not synchronized with each other, and the UE does not perform uplink transmission other than the transmission of the random access preamble. The time alignment timer specifically operates as follows.

i) When the terminal receives a timing advance command (TAC) from the base station through the MAC control element, the terminal applies a time alignment value indicated by the received time advance command to uplink synchronization. The terminal then starts or restarts the time alignment timer.

ii) When the terminal receives the time advance command through the random access response message from the base station and does not select the random access response message in the MAC layer of the terminal (a), the terminal receives the time alignment value indicated by the time advance command. Applies to uplink synchronization and starts or restarts the time alignment timer. Or, if the terminal receives the time advance command through the random access response message from the base station, if the random access response message is selected in the MAC layer of the terminal and the time alignment timer is not running (b), the terminal is time advance The time alignment value indicated by the command is applied to the uplink synchronization, the time alignment timer is started, and the time alignment timer is stopped if it fails later in the contention resolution, which is a random access step. Or, in cases other than (a) and (b), the terminal ignores the time advance command.

iii) When the time alignment timer expires, the terminal flushes data stored in all HARQ buffers. The terminal informs release of PUCCH / SRS to the RRC layer. At this time, the type 0 SRS (periodic SRS) is released and the type 1 SRS (aperiodic SRS) is not released. The terminal clears all configured downlink and uplink resource allocation.

In order for the UE to transmit an uplink signal excluding the random access preamble, the UE must obtain a valid time alignment value for the UL CC corresponding to the corresponding serving cell. If a valid time alignment value for the UL CC is secured, the terminal may transmit an uplink signal such as a sounding reference signal (SRS) on a UL CC periodically or aperiodically. SRS is the basis for the determination by the base station to update the time alignment value. The base station can check in real time whether the time alignment value obtained for the UL CC from the uplink signal is valid or needs to be updated. If the time alignment value needs to be updated, the base station may inform the terminal of the updated time alignment value through a MAC control element (CE).

However, such an uplink signal may be transmitted only when the UL CC is activated. In other words, in the state in which the secondary serving cell is inactivated, the terminal cannot transmit an uplink signal through the UL SCC corresponding to the secondary serving cell. Therefore, the base station or the terminal cannot determine the validity of the existing time alignment value. That is, inability to transmit an uplink signal due to deactivation of the secondary serving cell causes uncertainty regarding the validity of the time alignment value. Therefore, when the validity of the previously set time alignment value is not confirmed for a predetermined time, when the deactivated secondary serving cell is activated by an activation indicator, the terminal checks whether the existing time alignment value is valid. Is needed. This is because subsequent procedures, for example, whether the uplink signal can be transmitted depend on whether the time alignment value is valid.

5 shows an example of a cell deployment scenario to which the present invention is applied.

Referring to FIG. 5, the terminal 500 includes a main serving cell 510 having a frequency of F2 and a secondary serving cell 520 having a frequency of F1, and the terminal 500 passes from position ⓐ to position ⓑ through position ⓑ. Is moving to. The vicinity of the location ⓒ is an area serviced by the repeater 530, and the terminal 500 performs communication through the repeater 530 at the location ⓒ.

In the position ⓐ, both the main serving cell 510 and the secondary serving cell 520 configured in the terminal 500 are in an activated state. The primary serving cell 510 and the secondary serving cell 520 may be provided by the same base station or may be provided by different base stations. The primary serving cell 510 belongs to a first timing alignment group (TAG) having a time alignment value TA1 or TA3, and the secondary serving cell 520 is assigned to a second time alignment group having a time alignment value TA1. Belongs.

A time alignment group is a set of serving cells using the same timing reference and the same time alignment value (that is, the same amount of uplink time adjustment is required). A time alignment group including the primary serving cell is called a pTAG (primary TAG), and a time alignment group not including the primary serving cell is called a sTAG (secondary TAG). The time alignment group is a parameter that is UE-specifically formed by the RRC. That is, even the same serving cell may belong to the time alignment group 1 (TAG1) for the terminal 1 and to the time alignment group 2 (TAG2) for the terminal 2. For each terminal, the time alignment group may change dynamically. The time alignment group may be called a timing advance group.

In position ⓐ, since the secondary serving cell 520 is activated, the terminal 500 may periodically transmit a sounding reference signal (SRS) for the F1 frequency band. At this time, the base station may continuously monitor the change in the time alignment value TA1 by receiving the SRS. The base station may change the time alignment value to be used by the terminal 500 in the F1 band by using an update procedure if necessary by checking the validity of the time alignment value. The update procedure includes a random access procedure or a procedure of transmitting a MAC control element (CE) message.

The terminal 500 deactivates the secondary serving cell 520 at the position ⓑ. If all secondary serving cells of TAG2 are deactivated, the terminal 500 cannot perform sounding reference signals and other uplink transmissions through any serving cell in TAG2. Therefore, the base station cannot confirm the validity of TA1 with respect to TAG2. At this time, the time alignment timer for TAG2 continues. The time alignment timer is introduced to determine the validity of the time alignment value, and the terminal 500 receives the expiration time of the time alignment timer from the base station. The expiration time of the time alignment timer is determined by the base station based on the movement speed of the terminal 500 estimated by the base station.

The terminal 500 activates the secondary serving cell 520 at the location ⓒ. At this time, the secondary serving cell 520 communicates with the terminal 500 through the repeater 530. The uplink synchronization for the repeater 530 is time alignment value TA2 is applied. However, since the time alignment timer for TAG2 is still in progress, uplink synchronization with respect to the terminal 500 is still in a TA1 state. Therefore, a sudden change in the time alignment value, such as a change in the installation environment of the repeater 530, can not be guaranteed validity by the time alignment timer. For example, when the terminal 500 verifies the validity of the time alignment value using only the time alignment timer, the terminal 500 performs uplink transmission according to uplink synchronization according to the invalid TA1, thereby repeating the relay 530. ) Can interfere with the uplink signals of all terminals communicating directly with the base station using the F1 frequency band, as well as other terminals communicating with each other. In order to solve this problem, when the secondary serving cell 520 is activated, the terminal 500 should first check whether the previously set time alignment value is valid in consideration of the time alignment value due to the influence of the surrounding repeaters. When the validity of the time alignment value is verified, the terminal 500 may maintain uplink synchronization according to the existing time alignment value and transmit an uplink control signal or a data signal.

To this end, an embodiment discloses a method for the terminal to determine the validity of the time alignment value. In addition, another embodiment discloses a procedure for acquiring a valid time alignment value when the existing time alignment value is found to be invalid. Another embodiment discloses the structure and content of a message used in a procedure for obtaining a valid time alignment value.

(Part 1) How to determine the validity of time alignment values

The terminal determines the validity of the time alignment value based on a validity loss condition. If the loss of validity condition is satisfied, the previous time alignment value is no longer valid. That is, the terminal checks whether the validity loss condition is satisfied, and if the validity loss condition is satisfied, the terminal cannot transmit an uplink signal using a previous time alignment value. This is described with the main view that the time alignment value is invalid. On the contrary, even in the same phenomenon, a validity hold condition defined in view of whether the validity of the time alignment value is maintained may be used. If the validity condition is met, the previous time alignment is valid. That is, the terminal may check whether the validity maintaining condition is satisfied, and if the validity maintaining condition is satisfied, the terminal may proceed to transmit an uplink signal using a previous time alignment value.

For example, one example of a parameter used to determine the validity of a time alignment value is a time alignment timer. When the time alignment timer defined in the TAG expires, the terminal determines that the time alignment value for the TAG is no longer valid. That is, the terminal determines that the condition for validity loss is satisfied. On the other hand, when interpreting this from the viewpoint of validity maintenance, the terminal determines that the validity maintenance condition is not satisfied. The validity condition is satisfied, the validity condition is not satisfied, and the validity condition is not satisfied, the validity condition is satisfied. As such, the conditions of validity and conditions of validity are the same scenarios interpreted from opposite points of view, and the difference between them is only the term and is substantially the same. Hereinafter, the term 'loss of validity condition' will be used. However, the satisfaction and dissatisfaction of the validity loss condition may be reinterpreted as the dissatisfaction and satisfaction of the validity retention condition, and the present invention includes the scope of the right when all embodiments of the present specification are reinterpreted in terms of the validity retention condition. do.

In the following, the conditions of loss of effectiveness are described in detail.

(1) As an example, as shown in FIG. 6, when the time alignment timer defined in the TAG expires, a loss of validity condition is satisfied. Since the time alignment timer may be individually defined for each TAG, the UE determines whether each of the validity loss conditions is satisfied for each TAG. The terminal monitors whether the time alignment timer of each TAG expires. When the first time alignment timer expires, the terminal may determine that the time alignment value of the TAG according to the first time alignment timer is invalid. In contrast, if the second time alignment timer has not expired, the terminal may determine that the time alignment value of the TAG according to the second time alignment timer is still valid.

If the validity loss condition is satisfied, the UE proceeds when the time alignment timer expires. For example, the terminal releases TAG related configuration information. The TAG related configuration information may be serving cell information and time alignment timer value included in the corresponding TAG, and may additionally include a currently valid TA value. The terminal must update the released TAG related configuration information and the time alignment value for the corresponding TAG. In this case, the base station can also recognize the expiration of the time alignment timer. In order to update the TAG related configuration information and the time alignment value for the corresponding TAG, the terminal may perform a random access procedure. If the main serving cell is included in the corresponding TAG, the UE may initiate a random access procedure by itself. The terminal may receive an updated time alignment value from the base station by the random access procedure. On the other hand, if the main serving cell is not included in the corresponding TAG, the UE may initiate a random access procedure according to an indication of the base station (ex, PDCCH order), the time alignment value updated from the base station by the random access procedure Can be received.

As another example, if the loss of validity condition is satisfied, the terminal may set a TA value, which is valid among the TAG-related configuration information when the time alignment timer expires, to an initial value set when the first TAG is generated. At this time, the initial value of the TA value may be zero. As another example, some of the HARQ buffer and SRS operation related parameters for uplink data transmission may be released without releasing TAG related configuration information, and uplink transmission may be stopped only in the TAG.

The terminal adjusts the uplink time based on the updated time alignment value and resumes uplink transmission based on the adjusted uplink time.

(2) As another example, if a difference between two downlink timing values T1 and T2 measured by different terminals at different time points is equal to or greater than a validity threshold Tth, an invalidity condition is satisfied. The timing reference cell caused the difference in the downlink timing value is included in a specific TAG, the terminal determines that the time alignment value for the TAG is not valid. On the contrary, if the difference between the two downlink timing values T1 and T2 measured at different times by the UE is not greater than or equal to the effective threshold Tth, the condition for loss of validity is not satisfied. Here, the change of the downlink timing value may be detected in the sTAG.

(2-1) In one aspect, as shown in FIG. 7, T1 is a downlink timing value measured within a period in which all of the serving cells in the TAG are determined to be deactivated or changed from the time when the deactivation indicator is received from the base station to the deactivated state. Can be. T2 may be a downlink timing value measured at the earliest time since at least one serving cell of the TAG is activated. In this case, the timing at which downlink timing can be measured is activated, and is an active time by DRX (Discontinous Reception) operation, or a timing of transmitting PUCCH / PUSCH / SRS through uplink ( Subframe) or a time point (subframe) for transmitting the PRACH.

The difference between T1 and T2 includes the absolute value | T1-T2 | of the difference between T1 and T2.

(2-2) In another aspect, the downlink timing value measured when the UE receives a time advance command (TAC) indicating a time alignment value for the TAG from the base station with reference to FIG. 8 may be T1. T2 may be a downlink timing value measured at the earliest time since at least one serving cell of the TAG is activated. The difference between T1 and T2 includes the absolute value | T1-T2 | of the difference between T1 and T2. Here, the TAC is transmitted from a base station in a random access response (RAR) message or a TAC MAC control element (CE).

(2-3) In another aspect, as shown in FIG. 8, the terminal receives a time advance command (TAC) indicating a time alignment value for the TAG from the base station, and finally updates the time alignment value based on the time advance command. The downlink timing value measured at one time point may be T1. T2 may be a downlink timing value measured at the earliest time since at least one serving cell of the TAG is activated. The difference between T1 and T2 includes the absolute value | T1-T2 | of the difference between T1 and T2.

Here, the TAC is transmitted from a base station in a random access response (RAR) message or a TAC MAC control element (CE).

(3) As another example, FIG. 9 illustrates determining that a time alignment value for a previously received TAG is not valid when deactivation of a TAG secondary serving cell continues. More specifically, when the time alignment timer for the TAG expires while the deactivation of the secondary serving cell of the TAG is maintained, a loss of validity condition is satisfied. The terminal drives a time alignment timer for the TAG immediately after the TAG secondary serving cell is deactivated, and monitors whether the time alignment timer expires. When the time alignment timer expires, the terminal may determine that the time alignment value of the TAG according to the time alignment timer is invalid.

If the validity loss condition is satisfied, the UE proceeds when the time alignment timer expires. For example, the terminal releases TAG related configuration information. The terminal must update the released TAG related configuration information and the time alignment value for the corresponding TAG. In this case, the base station can also recognize the expiration of the time alignment timer. In order to update the TAG related configuration information and the time alignment value for the corresponding TAG, the terminal may perform a random access procedure. If the main serving cell is included in the corresponding TAG, the UE may initiate a random access procedure by itself. The terminal may receive an updated time alignment value from the base station by the random access procedure. On the other hand, if the main serving cell is not included in the corresponding TAG, the UE may initiate a random access procedure according to an indication of the base station (ex, PDCCH order), the time alignment value updated from the base station by the random access procedure Can be received.

As another example, if the loss of validity condition is satisfied, the UE may set the TA value among the TAG related parameters when the time alignment timer expires to an initial value set when the first TAG is generated. At this time, the initial value of the TA value may be zero. As another example, some of the parameters related to the HARQ operation and the SRS operation may be released without releasing TAG-related configuration information, and uplink transmission may be stopped only in the TAG.

The terminal adjusts the uplink time based on the updated time alignment value and resumes uplink transmission based on the adjusted uplink time.

(4) As another example, as shown in FIG. 10, when the downlink timing value is T1 while the secondary serving cell of the TAG is activated, the downlink timing value jumps to T2 rapidly, a loss of validity condition Is satisfied. That is, if | T1-T2 | is equal to or greater than the validity threshold, the validity loss condition is satisfied. When the UE measures the downlink timing value T1 for the activated secondary serving cell, continuously monitors the downlink timing value, and confirms that the downlink timing value is rapidly jumped to T2, the loss of validity condition is considered to be satisfied. . As another example, the UE measures the downlink timing value T1 for the activated secondary serving cell, continuously monitors the downlink timing value, and confirms that the downlink timing value is jumped to T2 for a predetermined time or more. In the case where the T2 value is continuously confirmed, that is, when the period of time maintained after the rapid change from T1 to T2 lasts for a specific time or more, the condition for loss of effectiveness is considered to be satisfied. In this case, the specific time may be a parameter determined by the terminal without an indication of the base station or may be set to a parameter indicated by the base station.

The timing reference cell caused the difference in the downlink timing value is included in a specific TAG, the terminal determines that the time alignment value for the TAG is not valid. In the case where the loss of validity condition is satisfied in (4), if the TAG is a pTAG including the main serving cell, the UE may initiate a random access procedure by itself. The terminal may receive an updated time alignment value from the base station by the random access procedure. On the other hand, if the TAG is an sTAG including only secondary serving cells, the terminal cannot initiate a random access procedure by itself. In this case, in order to acquire the uplink synchronization of the secondary serving cell, the UE must voluntarily initiate a random access procedure by using the primary serving cell, and a clear procedure for this should be defined.

According to the embodiments of (2-1), (2-2), (2-3), and (4), the terminal determines the validity of the time alignment value based on the downlink timing value and the effective threshold value. do. In principle, it is most accurate to judge the validity of the time alignment value with the time alignment value itself. In order to do so, the UE transmits an uplink signal, receives a new time alignment value from the base station, and compares it with a previous time alignment value. It is contradictory to take such an operation when the uplink synchronization is not correct. Accordingly, the terminal preferably determines the validity of the time alignment value in view of the downlink timing value, which is a numerical value that can be obtained by the terminal. However, in order to increase the accuracy of determining the validity of the time alignment value, it is preferable to design the effective threshold value to be related to the time alignment value.

To this end, the effective threshold value may be linked to the error correction range of the time alignment value. In other words, the effective threshold value should be defined within a range in which the time alignment value can be effectively modified. For example, when Tq is an automatic error correction range in terms of a time alignment value, the automatic error correction range is converted to a dimension of a downlink timing value so that an effective threshold value corresponds to the Tq. A functional relationship, such as the following equation, may be established between the effective threshold and the time alignment value.

Equation 1

Referring to Equation 1, f (x) is a function of converting the time alignment value x into the dimension of the effective threshold regarding downlink timing. Tq is the maximum range that the terminal can autonomously correct the error of the uplink time (autonomously). Tq = k * Ts, k = 2, 4, 8, 16, and Ts is a sampling period. Tq may be defined as shown in the following table according to the downlink bandwidth of the serving cell given to the terminal.

Here, the Tq may include a value corrected by a single correction operation or a plurality of correction operations.

Table 1 Downlink Bandwidth (MHz) T _q 1.4 16 * T _S 3 8 * T _S 5 4 * T _S ≥10 2 * T _S

For example, let f (x) = 0.5x, Ts = 0.0325 μs, and downlink bandwidth of 5 MHz. Then Tq = 4 * Ts = 4 * 0.0325 = 0.13μs and Tth = f (0.13) = 0.5 * 0.13 = 0.065μs. According to this, if the absolute value of the difference between the T1 and T2 is 0.065μs or more, it can be seen that the validity loss condition is satisfied.

As another example, the terminal may correct the time alignment value according to the following rule. In the following, Ts is a sampling period and Tq is a basic adjustment unit for self-correction.

i) The maximum time alignment correction value that can be changed in a single correction operation is Tq.

ii) The minimum aggregated correction rate per second shall be 7 * TS.

iii) The maximum aggregated correction rate per 200 ms shall be Tq.

Here, the aggregated meaning may be defined as an added value after taking an absolute value for each of the correction values for the time alignment value generated by the self-correction operation of the terminal. Alternatively, it may be defined as a value that takes an absolute value after adding correction values for a time alignment value generated by the self-correction operation of the terminal.

The terminal may be configured based on a reference timing (ie, downlink timing) when the time alignment value TA of the specific TAG is obtained and a reference timing (ie, downlink timing) of the specific TAG of the current terminal. When the error (difference) of the generated time alignment value exceeds the Te value in Table 2 below, the time alignment value may be corrected based on the Tq value and the time alignment value correction operation rule of the terminal within the following Te value.

TABLE 2 Downlink Bandwidth (MHz) T _e 1.4 24 * T _S ≥3 12 * T _S

Therefore, the effective threshold value may be defined as a maximum aggregated correction ratio value + Te value or a corresponding downlink timing difference value per unit time (2 seconds, 1 second or 200 ms, etc.).

For example, when the unit time is 200ms, the terminal may correct by Tq based on the maximum aggregated correction ratio. At this time, the reference timing (ie, downlink timing) at the time when the time alignment value (TA) of the specific TAG is acquired and the reference time point (ie, downlink) of the specific TAG of the current UE It is determined that there is still a problem in uplink synchronization when the error (generally generated by timing) occurs more than Te + Tq. That is, the time alignment value can be corrected by Tq for 200 ms, which is a unit time, but there is an error in the time alignment value for Te. Therefore, the terminal can identify a problem with the uplink synchronization. In this case, the effective threshold value is a time alignment value error Te + Tq per unit time (200 ms) or a downlink timing difference value corresponding to the time alignment value error.

Although the above described effective threshold value is obtained based on the time alignment value, this is only an example, and there are various ways for the terminal to know the effective threshold value. For example, the effective threshold value may be set by the base station and transmitted to the terminal through PDCCH (L1 signaling), MAC CE (L2 message), and RRC (L3 message). Alternatively, an effective threshold value of a fixed value already experimentally proved may be stored in a memory of the terminal, and the terminal may load and use the valid threshold value from the corresponding memory.

(Part 2) Triggering on Random Access Procedures for Problem Reporting

Unlike the main serving cell, if the condition for loss of validity for the secondary serving cell is satisfied, an inconsistency in uplink time synchronization may occur, thereby causing an uplink interference problem.

In this case, the terminal may determine the validity of the time alignment value for the corresponding sTAG in consideration of the valid threshold value described above, and control the operation of the time alignment timer (TAT) in relation to the validity of the time alignment value. That is, when it is determined that the time alignment value is invalid, the time alignment timer in the corresponding sTAG may be stopped only if the uplink transmission in the corresponding sTAG is stopped or the sTAG in which the validity condition is satisfied. .

On the other hand, the base station does not transmit the new TA value of the sTAG itself until it is confirmed that the loss of validity of the sTAG. Accordingly, the terminal or the base station can eliminate the uplink interference problem.

The terminal needs to inform the base station that the time alignment value in a specific sTAG or secondary serving cell is invalid. This is called a problem report.

More specifically, if the problem occurs only in the sTAG, the terminal can not initiate the random access procedure by itself. This is because the random access procedure in the secondary serving cell should be initiated by the indication of the base station. However, only the terminal can recognize the problem, and furthermore, the secondary serving cell can not expect anything because the uplink synchronization is already inconsistent. In this case, in order to acquire uplink synchronization of the secondary serving cell in the sTAG, the UE inevitably needs to inform the base station of the problem by using a serving cell in a TAG in which uplink synchronization is valid in addition to the sTAG. In this regard, the present invention is to disclose a method for notifying a problem report (problem report) by the terminal.

Hereinafter, the problem report refers to an operation in which the terminal transmits a problem indication to the base station. Problem reports can be replaced by a variety of expressions. For example, a problem report may include various terms, such as a validation loss report, a new TA request, a UL sync resolution request, and a PDCCH order request. Can be replaced with

The terminal may transmit a problem report on the main serving cell. Or, in some cases, the terminal may transmit a problem report on another secondary serving cell in which uplink synchronization is secured. In order for the terminal to report a problem, there must be an uplink resource for transmitting a problem report. There is no problem when an uplink grant is secured in the primary serving cell, but otherwise, an uplink resource for transmitting a problem report should be secured. The random access procedure of the main serving cell initiated by the terminal may be used to secure uplink resources for transmission of the problem report. That is, the problem report is one event in which the random access procedure is performed. This random access procedure is called a random access procedure for problem reporting.

In the following, the conditions under which the random access procedure is triggered are described in detail.

(1) As an example, the triggering condition of the random access procedure may be i) a loss of validity condition. That is, the terminal checks whether the loss of validity condition is satisfied, and if the loss of validity condition is satisfied, the terminal starts a random access procedure in the main serving cell. The random access procedure may be a contention based random access procedure. Accordingly, the UE randomly selects one preamble sequence from a random access preamble sequence set, and uses a random access preamble according to the selected preamble sequence using a PRACH resource of a secondary serving cell. Transmit to base station.

(2) As another example, the triggering condition of the random access procedure requires that i) an invalidity condition is satisfied, and ii) an uplink grant is not indicated in the current transmission time interval (TTI). ii) The reason is that when the uplink grant is indicated (that is, if uplink resources are secured), the UE can transmit a problem report by using the reserved uplink resources without using a random access procedure. .

According to this, it is checked whether the terminal validity loss condition is satisfied. If the validity loss condition is satisfied, the UE checks whether an uplink grant is indicated to the current TTI (uplink grant is indicated for this TTI). That is, the terminal monitors reception of an uplink grant during the current TTI. As another example, the terminal may monitor reception of an uplink grant for a plurality of TTIs after the validity loss condition is satisfied. Here, the number of TTIs for determining during the plurality of TTIs may be a parameter determined by the terminal without an indication of the base station or may be set to a parameter indicated by the base station.

In one aspect, the serving cell that the terminal monitors the reception of the uplink grant may be the main serving cell. This corresponds to the case where the problem report is a MAC message and an RRC message. This is because the MAC message and the RRC message are both messages of a nature that can be transmitted on the primary serving cell. Accordingly, the terminal monitors the reception of the uplink grant in the main serving cell during the current TTI. In another aspect, the serving cell in which the terminal monitors the reception of the uplink grant may be a secondary serving cell in which uplink synchronization is secured. This is an example of when a problem report is a MAC message, not an RRC message. This is because the MAC message may be transmitted on the secondary serving cell or the RRC message may be transmitted only on the primary serving cell. Accordingly, the UE monitors the reception of the uplink grant in the secondary serving cell in which uplink synchronization is secured during the current TTI. In another aspect, the serving cell in which the terminal monitors the reception of the uplink grant may be a main serving cell and a secondary serving cell in which uplink synchronization is secured.

As a result of monitoring by the terminal, if the uplink grant is not indicated to the current TTI, the terminal initiates a random access procedure in the main serving cell. On the other hand, if it is confirmed that the uplink grant is indicated to the current TTI, whether the primary serving cell or the uplink synchronization secured secondary serving cell, the terminal serves a problem report by using the uplink resources allocated by the uplink grant Send on cell.

(Part 3) Content and structure of problem reporting

(1) As an example, the problem report may be included in a MAC protocol data unit (PDU). The MAC PDU corresponds to MSG3 transmitted by the UE to a base station after receiving a random access response message including an uplink grant during a random access procedure for problem reporting.

11 is a block diagram illustrating a MAC PDU including a problem report according to an embodiment of the present invention.

Referring to FIG. 11, the MAC PDU 1100 includes a MAC header 1110, at least one MAC control element 1120-1,..., 1120-n, and at least one MAC Service Data Unit (SDU). 1130-1, ..., 1130-m) and padding 1140.

The MAC header 1110 includes at least one subheader 1110-1, 1110-2,..., 1110-k, and each subheader 1110-1, 1110-2 ... (1110-k) corresponds to one MAC SDU or one MAC control element or padding 1140. The order of subheaders 1110-1, 1110-2,..., 1120-k is the corresponding MAC SDU and MAC control elements 1120-1,..., 1120-n in MAC PDU 1100. Or in the same order as the padding 1140.

Each subheader 1110-1, 1110-2, ..., 1110-k contains four fields R, R, E, LCID or R, R, E, LCID, F, L 6 Field may be included. Subheaders containing four fields are subheaders corresponding to MAC control elements 1120-1, ..., 1120-n or padding 1140, and subheaders containing six fields correspond to MAC SDUs. Subheader.

The Logical Channel ID (LCID) field may identify a logical channel corresponding to a MAC SDU, or may identify a MAC control element 1120-1, ..., 1120-n or a type of padding. This is an identification field. When each subheader 1110-1, 1110-2,..., 1110-k has an octet structure, the LCID field may be 5 bits.

For example, as shown in Table 3, the LCID field identifies whether the MAC control elements 1120-1, ..., 1120-n are MAC CE for Problem Report. The MAC control element for problem reporting is a MAC control element including a problem report field.

TABLE 3 index LCID value 00000 CCCH 00001-01010 Logical Channel Identification 01011-10111 Reserved 11000 Problem report 11001 Extended Power Headroom Report 11010 Power Headroom Report 11011 C-RNTI 11100 Truncated BSR 11101 Short bsr 11110 Long bsr 11111 padding

Referring to Table 3, if the index of the LCID is 11000, the value of the LCID indicates that the MAC control element corresponding to the LCID is for problem reporting. Therefore, when the UE determines that the index of the LCID is 11000, it can be seen that the MAC control element corresponding to the LCID is for problem reporting. The structure of the subheader including the LCID is shown in FIG. 12. Referring to FIG. 12, the subheader 1200 includes two R fields, one E field, and an LCID. Here, if the index of the LCID is 11000, it indicates that the MAC control element for problem reporting is transmitted.

Referring back to FIG. 11, MAC control elements 1120-1,..., 1120-n are control messages generated by the MAC layer. Padding 1140 is a predetermined number of bits added to make the size of the MAC PDU constant. The MAC control elements 1120-1,... 1210-n, the MAC SDUs 1130-1,... 1110-m, and the padding 1140 together are also referred to as MAC payloads.

13 illustrates a MAC control element for problem reporting according to an embodiment of the present invention.

Referring to FIG. 13, the MAC control element 1300 corresponds to the subheader 1200 as shown in FIG. 12. As such, it is identified that the MAC control element 1300 is for problem reporting. MAC control element 1300 includes one octet. The octet contains 8 bits of information. Octet 1 includes six reserved R (R) fields and a TAG ID field. The TAG ID is an index of the TAG that has lost the validity of the time alignment value. In other words, the TAG ID is an index of a TAG including a secondary serving cell whose uplink time synchronization does not match. In another aspect, the TAG ID is an index of the TAG when the UE needs a new time alignment value for the TAG due to an uplink time mismatch of the TAG.

14 illustrates a MAC control element for problem reporting according to another example of the present invention.

Referring to FIG. 14, the MAC control element 1400 corresponds to the subheader 1200 as shown in FIG. 12. As such, it is identified that the MAC control element 1400 is for problem reporting. The MAC control element 1400 includes one octet. The octet contains 8 bits of information. Octet 1 includes two reserved R (R) fields, a DL timing change field, and a TAG ID field. The downlink timing change field indicates a difference between T1 and T2. For example, the downlink timing change field is 4 bits and may represent 16 quantized downlink timing values.

15 is a structure of a subheader including an LCID field indicating a problem report according to another embodiment of the present invention.

Referring to FIG. 15, the subheader 1500 includes a TAG ID field, one E field, and an LCID. Here, if the index of the LCID is 11000, the subheader 1500 indicates that the subheader itself is a subheader for problem reporting. In this case, there may or may not be a MAC control element or MAC SDU corresponding to the subheader 1500. The TAG ID is an index of the TAG that has lost the validity of the time alignment value. In other words, the TAG ID is an index of a TAG including a secondary serving cell whose uplink time synchronization does not match. In another aspect, the TAG ID is an index of the TAG when the UE needs a new time alignment value for the TAG due to an uplink time mismatch of the TAG.

(2) As another example, the problem report may be included in the RRC message. The RRC message corresponds to MSG3 transmitted to the base station after the terminal receives a random access response message including an uplink grant during a random access procedure for problem reporting.

(2-1) In one aspect, the problem report is included in UE assistant information transmitted by the terminal. The terminal assistance information is an RRC message provided by the terminal to the base station for assistance information supported by the terminal. The terminal assistance information may be transmitted through a dedicated control channel (DCCH), which is a logical channel provided separately for transmitting the terminal assistance information.

The terminal assistance information may include, for example, assistance information for interference avoidance for in-device coexistence (IDC), assistance information related to heterogeneous networks, assistance information related to MBMS, and various data applications. In addition to information used to improve system performance, such as supplemental information for enhancements of Diverse Data Application (eDDA), it may further include supplemental information for problem reporting. Alternatively, the terminal assistance information may include only assistance information for problem reporting according to an embodiment of the present invention. The terminal assistance information may be transmitted through an RRC connection request message or an RRC connection setup complete message.

The terminal assistance information may be composed of the syntax shown in the following table.

Table 4 UEAssistInformation-IEs :: = SEQUENCE { ProblemReport_sTAG Boolean OPTIONAL, sTAG-ID INTEGER (1..3) OPTIONAL, }

Referring to Table 4, the UE assistance information (UEAssistInformation-IEs) includes a sTAG problem report (ProblemReport_sTAG) field indicating that a problem occurs in the validity of the time alignment value of the sTAG. And a sTAG-ID field indicating the index of the corresponding sTAG. The value of the sTAG-ID field may be any one of 1, 2, and 3. The sTAG problem report field is a boolean value, which indicates a problem report if 'TRUE' and a problem report if 'FALSE'.

(2-2) In another aspect, when the terminal cannot transmit a problem report through the random access procedure of the main serving cell, the terminal may transmit a problem report at the request of the base station. In this case, when a problem occurs, the terminal stores at least one information on the time, location, and cause of the problem (inconsistency of uplink time synchronization due to a change in downlink timing) when the problem occurs. It can be provided as information.

In this case, the terminal assistance information may be configured as shown in Table 5 below.

Table 5 OtherAssistInfo :: = SEQUENCE { locationInfo LocationInfo-r10 OPTIONAL, relativeTimeStamp INTEGER (0..7200), servCellIdentity CellGlobalIdEUTRA, ProblemReport_sTAG Boolean OPTIONAL, … } OPTIONAL,

Referring to Table 5, other assistance information (OtherAssistInfo) is a terminal assistance information transmitted by the terminal at the request of the base station, the location information field (locationInfo), the relative time stamp (relativeTImeStamp) field, the serving cell identification (servCellIdentity) field and It includes a sTAG problem report (ProblemReport_sTAG) field indicating that a problem occurs in the validity of the time alignment value of the sTAG. The sTAG problem report field is a boolean value, which indicates a problem report if 'TRUE' and a problem report if 'FALSE'.

On the other hand, the base station is also possible to collect the corresponding information through the UE capability information (UE capability information) procedure used to collect the Minimization of Drive Test (MDT) information.

If the network (wireless carrier) is unable to determine the location of the terminal, the location of the repeater, or the system is unable to determine both the location of the terminal and the location of the repeater, the terminal for the sTAG consisting of only secondary serving cell When the validity loss condition (a difference between T1 and T2 is equal to or greater than a validity threshold Tth) is met, a problem report for the sTAG is transmitted through a random access procedure of the main serving cell. Or, the terminal waits until the time alignment timer expires.

(Part 4) Procedure for Reporting Problems

According to an exemplary embodiment, a problem reporting procedure may include: checking whether a terminal loses validity condition, checking whether a triggering condition of a random access procedure is satisfied, and reporting a problem when the triggering condition of a random access procedure is satisfied. Transmitting to the base station. This will be described in detail as follows.

16 is a flowchart illustrating a method of determining the validity of a time alignment value according to an embodiment of the present invention.

Referring to FIG. 16, the terminal checks whether a validity loss condition is satisfied in order to determine the validity of the time alignment value for the sTAG (S1600). That is, the determination of the validity of the time alignment value includes the step of the terminal confirming the condition for loss of validity. Here, the condition for loss of validity may be defined as any one of (1), (2), (3), and (4) of (Part 1), and may be defined as two or three or four combinations thereof. It may be.

According to (1) of (Part 1), the loss of validity condition is the expiration of the time alignment timer of the sTAG. Accordingly, the determination of the validity of the time alignment value includes the terminal checking whether the time alignment timer of each TAG expires. When the time alignment timer expires, the terminal determines that the time alignment value of the TAG according to the time alignment timer is invalid. In contrast, if the time alignment timer has not expired, the terminal determines that the time alignment value of the TAG according to the time alignment timer is still valid. The terminal proceeds when the time alignment timer expires.

Meanwhile, according to (2) of (Part 1), the condition for loss of validity is that a difference between two downlink timing values T1 and T2 measured at different times by the UE is greater than or equal to the effective threshold value Tth. The method of securing the effective threshold value Tth is as described above. As an example, the determination of the validity of the time alignment value may include: measuring, by the UE, a downlink timing value T1 within a period of changing from the deactivation state after determining that all serving cells in the TAG are deactivated, as shown in FIG. 7, at least one of the TAG And measuring a downlink timing value T2 within a period of changing from the serving cell to the activated state after the serving cell is determined to be activated, and determining whether a difference between T1 and T2 is equal to or greater than an effective threshold value.

As another example, the determination of the validity of the time alignment value may include receiving a time advance command (TAC) from the base station indicating a time alignment value for the TAG from the base station, as shown in FIG. 8. Measuring a downlink timing value T1 at a last updated time, measuring a downlink timing value T2 within a period in which the at least one serving cell of the TAG is changed to an activated state after being determined to be activated, and T1 and Determining whether the difference in T2 is greater than or equal to the effective threshold.

On the other hand, according to (3) of (Part 1), the invalidity condition is that the time alignment timer for the TAG configured immediately after the secondary serving cell of the TAG is expired. Accordingly, the determination of the validity of the time alignment value includes the step of driving, by the UE, a time alignment timer for the TAG immediately after the TAG secondary serving cell is deactivated, and monitoring whether the time alignment timer expires as shown in FIG. 9. When the time alignment timer expires, the terminal may determine that the time alignment value of the TAG according to the time alignment timer is invalid.

Meanwhile, according to (4) of (Part 1), the validity loss condition is a case where the downlink timing value is T1 while the secondary serving cell of the TAG is activated, but the downlink timing value jumps rapidly to T2. Accordingly, the determination of the validity of the time alignment value includes measuring the downlink timing value T1 for the secondary serving cell in which the terminal is activated, and confirming that the downlink timing value is rapidly jumped to T2 as shown in FIG. 10. do.

In step S1600, if the loss of validity condition is not satisfied, it means that the time alignment value is still valid, and thus the UE performs uplink transmission based on the uplink time according to the previous time alignment value (S1605). Here, the uplink transmission includes periodic SRS (type-0 SRS) transmission, aperiodic SRS, random access preamble, periodic CQI transmission (periodic CSI reporting), and the like.

On the other hand, if the loss of validity condition is satisfied in step S1600, the terminal checks whether the triggering condition of the random access procedure (RA) is satisfied (S1610). The triggering condition of the random access procedure may be defined as one of (1) and (2) of (Part 2).

According to (1) of (Part 2), the triggering condition of the random access procedure is i) the loss of validity condition will be satisfied. Therefore, the satisfaction of the loss of validity condition at step S1600 is that the triggering condition of the random access procedure is satisfied.

On the other hand, according to (2) of (Part 2), the triggering condition of the random access procedure is i) the loss condition is satisfied, ii) the uplink grant is not indicated to the current transmission time interval (TTI) It does not cost. Therefore, the step of confirming whether the triggering condition of the random access procedure is satisfied includes the step of the terminal confirming whether an uplink grant is indicated in the current TTI. That is, the terminal monitors reception of an uplink grant during the current TTI.

As a result of monitoring by the UE, if the uplink grant is indicated to the current TTI, whether the primary serving cell or the secondary serving cell with uplink synchronization, i) is satisfied but ii) is not satisfied. Accordingly, the terminal transmits a problem report on the corresponding serving cell by using the uplink resource allocated by the uplink grant (S1625).

On the other hand, as a result of monitoring by the terminal, if the uplink grant is not indicated to the current TTI, conditions i) and ii) are satisfied. That is, in step S1610 if the random access triggering condition is satisfied. Accordingly, the terminal initiates a random access procedure in the main serving cell. To this end, the terminal transmits a random access preamble to the base station (S1615). In the transmitting of the random access preamble, the UE randomly selects one preamble sequence from the random access preamble sequence set, and transmitting the random access preamble according to the selected preamble sequence to the base station using the PRACH resource of the secondary serving cell. It includes. As an example, the terminal may transmit the random access preamble on the main serving cell. In this case, the terminal initiates a random access procedure by itself. As another example, the UE may transmit the random access preamble on another secondary serving cell having uplink time synchronization. In this case, the terminal initiates a random access procedure by a PDCCH order by the base station.

The terminal receives a random access response message including an uplink grant from the base station (S1620). The uplink grant indicates a resource for transmitting the uplink signal, MSG3. MSG3 includes problem reporting.

The terminal transmits a problem report to the base station using the resource indicated by the uplink grant (S1625). The content and structure of the problem report is as described in (Part 3).

When the base station receives a problem report, the base station recognizes that there is a problem in uplink time synchronization with respect to a specific TAG of the terminal, and may transmit a MAC PDU including a time forward command to the terminal to solve the problem. Thereafter, the terminal may adjust the uplink time based on the time alignment value indicated by the time advance command, and may resume uplink transmission based on the adjusted uplink time.

On the other hand, in the state where the validity loss condition is satisfied in step S1600, if the time alignment timer is still in progress, it may be a question whether to allow the uplink transmission of the terminal. As an example, in general, when a time alignment timer is in progress irrespective of determining the validity of a time alignment value of a TAG, uplink transmission of active serving cells in the TAG is not limited. This is regarded as an invalidity condition only as a transmission requirement of a problem report (or a triggering condition of a random access procedure for a problem report) and is irrelevant to uplink transmission. As another example, when it is determined that the validity of the time alignment value of the TAG is lost, all uplink transmission except for the aperiodic SRS and the random access preamble is restricted for the serving cells in the active state within the TAG. The limited uplink transmission includes periodic SRS transmission (type-0 SRS) and periodic CQI transmission.

17 is a flowchart illustrating a method of determining the validity of a time alignment value according to another embodiment of the present invention.

Referring to FIG. 17, the loss of validity condition is defined as a combination of (1) and (2) of (Part 1). Accordingly, the terminal checks the deactivation of all secondary serving cells in the sTAG (S1700).

The UE measures the downlink timing value T1 (S1705). On the other hand, the terminal confirms the activation of at least one secondary serving cell in the sTAG (S1710). The terminal measures the downlink timing value T2 (S1715).

As an example, T1 is measured within a period during which all serving cells in the TAG change to inactive state after it is determined to be deactivated, and T2 is measured within a period during which at least one serving cell of the TAG is changed to active state after it is determined to be activated. do.

As another example, T1 is measured at the time of last updating the time alignment value based on the time advance command, and T2 is measured within a period of changing to an activated state after at least one serving cell of the TAG is determined to be activated. .

The terminal checks whether the time alignment timer (TAT) expires (S1720).

In step S1720, if the TAT expires, the terminal receives a PDCCH order for the secondary serving cell from the base station to perform a random access procedure for problem reporting on the secondary serving cell (S1725). The terminal receives a new time alignment value from the base station according to the random access procedure to check whether the problem of loss of validity of the time alignment value is solved (S1730). In step S1730, if the problem of the loss of validity is resolved, the UE restarts uplink transmission, such as SRS, CSI report on the corresponding secondary serving cell (S1735). In step S1730, if the problem of the loss of validity is not solved, the UE restarts uplink transmission, such as SRS, CSI report on the corresponding secondary serving cell (S1735).

In step S1720, if the TAT has not expired, the terminal determines whether the absolute value of the difference between T1 and T2 is equal to or greater than a valid threshold value (S1740). If the absolute value of the difference between T1 and T2 is equal to or greater than the valid threshold value, the UE performs a random access procedure on the main serving cell for problem report on the sTAG (S1725). In step S1740, if the absolute value of the difference between the T1 and T2 is not more than the valid threshold value, the terminal checks whether the problem of loss of validity of the time alignment value is resolved (S1730). Subsequently, the operation of S1735 is the same as above.

In operation S1700 to S1740, the terminal may transmit location information to the base station when necessary according to the location information checking method. Alternatively, when the location information is not used, when the uplink transmission restart condition is not satisfied, the terminal may proceed with a random access procedure for problem report immediately without waiting for the expiration of the time alignment timer.

18 is a flowchart illustrating a method for providing validity of a time alignment value by a base station according to an embodiment of the present invention.

Referring to FIG. 18, the base station checks the position of the repeater (S1800).

When the terminal cannot transmit a problem report to the base station through a random access procedure of the main serving cell, the terminal may transmit the problem report only when requested by the base station. Therefore, the base station transmits the terminal assistance information request message to the terminal (S1805). If the terminal can transmit a problem report to the base station through the random access procedure of the main serving cell, step S1805 can be omitted.

 Here, the terminal assistance information request message may be made of a syntax as shown in the following table.

Table 6 UEAssistInformationRequest-IEs :: = SEQUENCE { OtherAssistInfoReq ENUMERATED true OPTIONAL,-Need ON nonCriticalExtension SEQUENCE OPTIONAL-Need OP }

Referring to Table 6, the UE Assist Information Request Message (UEAssistInformationRequest-IEs) may include an Other AssistInfo request field.

In response to a request from the base station, when the problem occurs, the terminal may store at least one information on the time, location, and cause of the problem (inconsistency of uplink time synchronization due to a change in downlink timing).

As a response to the terminal assistance information request message, the base station may receive other assistance information composed of a syntax as shown in the following table from the terminal (S1810).

TABLE 7 OtherAssistInfo :: = SEQUENCE { locationInfo LocationInfo-r10 OPTIONAL, relativeTimeStamp INTEGER (0..7200), servCellIdentity CellGlobalIdEUTRA, ProblemReport_sTAG Boolean OPTIONAL, … } OPTIONAL,

Other assistance information (OtherAssistInfo) is the terminal assistance information transmitted by the terminal at the request of the base station, the location information field (locationInfo), the relative time stamp (relative TImeStamp) field, serving cell identification (servCellIdentity) field and the time alignment value of the sTAG Contains a sTAG Problem Report (ProblemReport_sTAG) field indicating a problem with validation. The sTAG problem report field is a boolean value, which indicates a problem report if 'TRUE' and a problem report if 'FALSE'. If the terminal can transmit a problem report to the base station through the random access procedure of the main serving cell, step S1810 may also be omitted.

Thereafter, the base station checks whether there is a problem in the validity of the time alignment value of the sTAG, or checks the location of the terminal based on the location information of the terminal (S1815).

The base station determines the sTAG having a validity problem (that is, the time alignment value is invalid) based on the position of the repeater and the position information of the terminal, and calculates a valid time alignment (TA) value for the sTAG ( S1820). The base station performs a random access procedure for transmitting a time advance command indicating the valid time alignment value to the terminal (S1825). In the random access procedure, the base station transmits a PDCCH command for a secondary serving cell of sTAG to the terminal, the terminal transmits a random access preamble to the base station, and the base station transmits a random access response message including a time advance command to the terminal. Process.

The base station receives an uplink signal, such as SRS or CSI report, from the terminal based on the uplink time synchronization adjusted based on the valid time alignment value (S1830).

Of course, after confirming that there is a problem in the validity of the time alignment value of the sTAG, the base station may trigger a random access procedure as in step S1825 or transmit an aperiodic SRS request to the terminal to solve the problem for the sTAG. have. However, when the base station determines that the sTAG is no longer needed or it is determined that it is not necessary for a certain period of time, the base station may release the UL CC in the sTAG and transition all serving cells in the sTAG to an inactive state.

19 is a flowchart illustrating an operation between a terminal and a base station for determining validity of a time alignment value according to an embodiment of the present invention.

Referring to FIG. 19, the terminal checks whether a validity loss condition is satisfied in order to determine validity of a time alignment value for sTAG (S1900). That is, the determination of the validity of the time alignment value includes the step of the terminal confirming the condition for loss of validity. Here, the condition for loss of validity may be defined as any one of (1), (2), (3), and (4) of (Part 1), and may be defined as two or three or four combinations thereof. It may be. This may be performed in the same manner as in step S1600.

If the validity loss condition is satisfied, the UE checks whether the triggering condition of the random access procedure RA is satisfied (S1905). The triggering condition of the random access procedure may be defined as one of (1) and (2) of (Part 2). This may be performed in the same manner as in step S1610.

When the triggering condition of the random access procedure is satisfied (that is, when the uplink grant is not indicated to the current TTI), the UE starts the random access procedure in the main serving cell. In the random access procedure, the terminal transmits a random access preamble to the base station (S1910), and the base station transmits a random access response message including an uplink grant to the terminal (S1915). The terminal transmits a problem report to the base station using the resource indicated by the uplink grant (S1920).

When the base station receives a problem report, it recognizes that there is a problem in uplink time synchronization for a specific TAG of the terminal, and to solve this problem, the base station can transmit a TAC MAC CE including a time advance command for the problem sTAG to the terminal. have. Alternatively, a PDCCH command for newly starting a random access procedure to obtain a TA value for the specific TAG and performing a contention-free random access procedure through the specific TAG to receive a random random access response when receiving a random access response message The time alignment value in the message may be received (S1925). Thereafter, the UE may adjust the uplink time based on the time alignment value indicated by the time advance command and resume uplink transmission based on the adjusted uplink time (S1930).

20 is a block diagram illustrating a terminal and a base station according to an embodiment of the present invention.

Referring to FIG. 20, the terminal 2000 includes a terminal receiver 2005, a terminal processor 2010, and a terminal transmitter 2020. The terminal processor 2010 further includes a validity determination unit 2011 and a random access processing unit 2012.

The terminal receiver 2005 receives a random access response message (RAR for UL grant) for the uplink grant, a MAC CE for TAC (MAC CE) for a time forward command, a terminal assistance information request message, and the like from the base station 2050. .

The validity confirming unit 2011 determines whether the validity loss condition is satisfied in order to determine the validity of the time alignment value for the sTAG. The determination of the validity of the time alignment value includes the step of validating unit 2011 confirming a condition for loss of validity. Here, the condition for loss of validity may be defined as any one of (1), (2), (3), and (4) of (Part 1), and may be defined as two or three or four combinations thereof. It may be.

According to (1) of (Part 1), the loss of validity condition is the expiration of the time alignment timer of the sTAG. Therefore, the validity confirming unit 2011 checks whether the time alignment timer of each TAG expires. When the time alignment timer expires, the validity confirming unit 2011 determines that the time alignment value of the TAG according to the time alignment timer is not valid. In contrast, if the time alignment timer has not expired, the validity checking unit 2011 determines that the time alignment value of the TAG according to the time alignment timer is still valid. The validity checking unit 2011 proceeds when the time alignment timer expires.

Meanwhile, according to (2) of (Part 1), the condition for loss of validity is that a difference between two downlink timing values T1 and T2 measured at different times by the UE is greater than or equal to the effective threshold value Tth. The method of securing the effective threshold value Tth is as described above. As an example, the validity checking unit 2011 measures a downlink timing value T1 within a period of changing from the deactivation state after all the serving cells in the TAG are deactivated as shown in FIG. 7, and at least one serving cell of the TAG The downlink timing value T2 is measured within a period of changing from the activated state to the activated state after it is determined to be activated.

As another example, the validity checking unit 2011 receives a time advance command (TAC) indicating a time alignment value for the TAG from the base station as shown in FIG. 8, and finally updates the time alignment value based on the time advance command. A downlink timing value T1 is measured at a point in time, and a downlink timing value T2 is measured within a period of changing from the at least one serving cell of the TAG to an activation state after the determination is made to be activated, and a difference between T1 and T2 is an effective threshold value. Check if it is abnormal.

On the other hand, according to (3) of (Part 1), the invalidity condition is that the time alignment timer for the TAG configured immediately after the secondary serving cell of the TAG is expired. Therefore, the validity confirming unit 2011 drives the time alignment timer for the TAG immediately after the TAG secondary serving cell is deactivated as shown in FIG. 9, and monitors whether the time alignment timer expires. When the time alignment timer expires, the validity confirming unit 2011 may determine that the time alignment value of the TAG according to the time alignment timer is not valid.

Meanwhile, according to (4) of (Part 1), the validity loss condition is a case where the downlink timing value is T1 while the secondary serving cell of the TAG is activated, but the downlink timing value jumps rapidly to T2. Therefore, the validity confirming unit 2011 measures the downlink timing value T1 for the activated secondary serving cell as shown in FIG. 10 and confirms that the downlink timing value is rapidly jumped to T2.

If it is confirmed that the loss of validity condition is not satisfied, it means that the time alignment value is still valid. Therefore, the validity confirming unit 2011 performs the uplink transmission based on the uplink time according to the previous time alignment value. Control 2020. Here, the uplink transmission includes periodic SRS (type-0 SRS) transmission, aperiodic SRS, random access preamble, periodic CQI transmission (periodic CSI reporting), and the like.

On the other hand, if it is confirmed that the validity loss condition is satisfied, the validity confirming unit 2011 transmits it to the random access processing unit 2012.

The random access processor 2012 checks whether the triggering condition of the random access procedure RA is satisfied. The triggering condition of the random access procedure may be defined as one of (1) and (2) of (Part 2).

According to (1) of (Part 2), the triggering condition of the random access procedure is i) the loss of validity condition will be satisfied. That is, when it is confirmed that the condition for losing validity is satisfied, the random access processing unit 2012 may determine that the triggering condition of the random access procedure is satisfied.

On the other hand, according to (2) of (Part 2), the triggering condition of the random access procedure is i) the loss condition is satisfied, ii) the uplink grant is not indicated to the current transmission time interval (TTI) Would not, it costs. Accordingly, the step of the random access processing unit 2012 confirming whether the triggering condition of the random access procedure is satisfied includes the step of the random access processing unit 2012 confirming whether an uplink grant is indicated to the current TTI. That is, the random access processing unit 2012 monitors reception of an uplink grant during the current TTI.

As a result of monitoring, when the random access processing unit 2012 determines whether the uplink grant is indicated to the current TTI, whether the primary serving cell or the uplink synchronization is secured, the random access processing unit 2012 is allocated by the uplink grant. The problem report is transmitted on the corresponding serving cell by using the uplink resource.

On the other hand, if the monitoring results indicate that the random access processing unit 2012 does not indicate the uplink grant to the current TTI, since the conditions i) and ii) are satisfied, the random access processing unit 2012 performs the random access procedure in the main serving cell. It starts. To this end, the terminal transmitter 2020 transmits the random access preamble to the base station 2050. In the transmitting of the random access preamble, the random access processor 2012 randomly selects one preamble sequence from the random access preamble sequence set, and the terminal transmitter 2020 appends the random access preamble according to the selected preamble sequence. And transmitting to the base station 2050 using the PRACH resource of the serving cell. As an example, the terminal transmitter 2020 may transmit the random access preamble on the main serving cell. In this case, the random access processing unit 2012 initiates a random access procedure by itself. As another example, the terminal transmitter 2020 may transmit the random access preamble on another secondary serving cell having uplink time synchronization. In this case, the random access processing unit 2012 initiates a random access procedure by a PDCCH order by the base station 2050.

When the terminal receiver 2005 receives the random access response message for the uplink grant, the terminal receiver 2005 sends the random access response message to the validity confirming unit 2011. The validity confirming unit 2011 generates a problem report and sends the problem report to the terminal transmitting unit 2020. The terminal transmitter 2020 transmits a problem report to the base station 2050. The content and structure of the problem report is as described in (Part 3).

The base station 2050 includes a base station transmitter 2055, a base station receiver 2060, and a base station processor 2070. The base station processor 2070 further includes an update determining unit 2071 and a random access processing unit 2082.

The base station transmitter 2055 transmits a random access response message (RAR for UL grant) for the uplink grant, a MAC CE for TAC (MAC CE) for a time forward command, a terminal assistance information request message, and the like to the terminal 2000. do.

The base station receiver 2060 receives a problem report, a random access preamble, and other auxiliary information from the terminal 2000 as well as an uplink signal such as an SRS and a CSI report.

The update determination unit 2071 may check whether there is a problem in the validity of the time alignment value of the sTAG based on the problem report, or check the location information of the terminal based on other auxiliary information. Alternatively, the update determination unit 2071 may check the position of the repeater and the position of the terminal 2000 and determine whether the time alignment value of the TAG configured in the terminal 2000 is valid based on these positions. The update determining unit 2071 then calculates a new valid time alignment (TA) value for the TAG which has a problem of validity of the time alignment value. The update determination unit 2071 then sends the valid time alignment value to the random access processing unit 2082.

As an example, the random access processing unit 2082 performs a random access procedure for transmitting a random access response message for the uplink grant to the terminal. More specifically, when the base station receiving unit 2060 receives a random access preamble from the terminal 2000 on the main serving cell, the random access processing unit 2082 generates a random access response message for the uplink grant to transmit the base station 2055. The base station transmitter 2055 transmits a random access response message for the uplink grant to the terminal 2000. On the other hand, when the base station receiver 2060 receives a problem report from the terminal 2000 through the resource indicated by the uplink grant, the update determination unit 2071 checks the TAG ID having a problem based on the problem report. After that, the time alignment value for the corresponding TAG is calculated.

As another example, the random access processing unit 2082 performs a random access procedure for transmitting a time advance command indicating the time alignment value to the terminal. More specifically, the random access processor 2072 controls the base station transmitter 2055 to transmit a PDCCH command for the secondary serving cell of the sTAG to the terminal 2000. When the base station receiving unit 2060 receives the random access preamble from the terminal 2000, the random access processing unit 2082 generates a random access response message (RAR including TAC) or a MAC CE for the TAC including a time advance command. Send to the base station transmitter 2055.

The base station receiver 2060 receives an uplink signal such as an SRS or a CSI report from the terminal 2000 based on the uplink time synchronization adjusted based on the time alignment value.

Of course, when the update determination unit 2071 confirms that there is a problem in the validity of the time alignment value of the TAG, the random access processing unit 2082 may trigger a random access procedure to solve the problem for the TAG, the base station The transmitter 2055 may transmit the aperiodic SRS request to the terminal 2000. However, when the update determining unit 2071 determines that the TAG is no longer needed or determines that it is not necessary for a certain period of time, the update determining unit 2071 may release the UL CC in the TAG and all of the sTAG. The serving cell may be shifted to an inactive state.

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 not all possible combinations may be described to represent the various aspects, one of ordinary skill in the art will recognize that other combinations are possible. Accordingly, the invention is intended to embrace all other replacements, modifications and variations that fall within the scope of the following claims.

Claims (20)

In the method of performing uplink synchronization by a base station supporting a plurality of component carriers, Checking the position of the repeater; Checking the location of the terminal based on the location information of the terminal; Determining whether a time alignment value of a timing alignment group (TAG) configured in the terminal is valid based on the position of the repeater and the position of the terminal; Calculating a valid time alignment value for the TAG when the time alignment value of the TAG is invalid; And And receiving an uplink signal from the terminal based on the uplink time synchronization adjusted based on the valid time alignment value. The method of claim 1, And performing a random access procedure for transmitting a time advance command indicating the valid time alignment value to a terminal. The method of claim 1, And transmitting information requesting the aperiodic sounding reference signal (A-SRS) to the terminal. The method of claim 1, Determining the necessity of the TAG; If it is determined that the TAG is not necessary, the method further includes releasing an uplink component carrier in the TAG or transitioning all serving cells in the TAG to an inactive state. How to perform. A base station supporting a plurality of component carriers and performing uplink synchronization, Check the position of the repeater, determine the position of the terminal based on the position information of the terminal, and time alignment of the timing alignment group (TAG) configured in the terminal based on the position of the repeater and the position of the terminal An update determining unit that determines whether a value is valid and calculates a valid time alignment value for the TAG when the time alignment value of the TAG is not valid; And And a receiver configured to receive an uplink signal from the terminal based on the uplink time synchronization adjusted based on the valid time alignment value. The method of claim 5, And a random access processing unit which performs a random access procedure for transmitting a time advance command indicating the valid time alignment value to a terminal. The method of claim 5, The base station further comprises a transmitter for transmitting the information for requesting the aperiodic sounding reference signal (A-SRS) to the terminal. The method of claim 5, wherein the update determination unit, Determining the necessity of the TAG, and if it is determined that the TAG is not necessary, releasing an uplink component carrier in the TAG or transitioning all serving cells in the TAG to an inactive state. . In the method of performing uplink synchronization by a terminal supporting a plurality of CCs, Determining a validity of a time alignment value used for adjusting an uplink time of a secondary serving cell; And If it is determined that the time alignment value is not valid, stopping all uplink transmissions in the time alignment group (sTAG) to which the secondary serving cell belongs, or ending the time alignment timer in the sTAG. Method for performing uplink synchronization, characterized in that. In the method of performing uplink synchronization by a terminal supporting a plurality of CCs, Confirming that a condition for losing validity of a time alignment value used for adjusting an uplink time of a secondary serving cell is satisfied; Confirming that an uplink grant for the terminal is not currently indicated for a transmission time interval (TTI); Transmitting a random access preamble to a base station on a primary serving cell configured in the terminal; Receiving a random access response message including an uplink grant for the terminal from the base station; And Transmitting a problem report indicating a index of a timing alignment group (TAG) to which the secondary serving cell belongs by using an uplink resource indicated by the uplink grant to the base station; Method of performing uplink synchronization, characterized in that it comprises a. The method of claim 10, wherein the loss of validity condition, And a difference between a downlink timing value T1 measured by the terminal at a first point in time and a downlink timing value T2 measured at a second point in time is equal to or greater than an effective threshold value. The method of claim 11, wherein the T1 is measured within a period of time from which it is determined that all serving cells in the TAG are to be deactivated to a state of inactivation, and wherein T2 is in an activated state after at least one serving cell of the TAG is determined to be activated. The method of performing uplink synchronization, characterized in that measured in the period changed to. The method of claim 11, wherein the effective threshold is: And calculating the maximum range Tq that the terminal can correct for the error of the uplink time by itself as a variable. The method of claim 13, wherein Tq = k * Ts, K is determined by any one of 2, 4, 8, and 16 according to a downlink bandwidth, and Ts is a sampling period. In a wireless communication system supporting a plurality of CCs, in a terminal performing uplink synchronization, A validity confirming unit confirming that a condition for losing validity of a time alignment value used for adjusting an uplink time of a secondary serving cell is satisfied; A random access processing unit for confirming that an uplink grant for the terminal is not currently indicated for the TTI and randomly selecting one preamble sequence from a random access preamble sequence set; A transmitter for transmitting a random access preamble according to the selected preamble sequence to a base station; And Including a receiving unit for receiving a random access response message including an uplink grant for the terminal from the base station, The transmitter, characterized in that for transmitting a problem report indicating the index of the time alignment group (TAG) to which the secondary serving cell belongs by using the uplink resources indicated by the uplink grant to the base station. The method of claim 15, wherein the validity verification unit, And the terminal determines that the difference between the downlink timing value T1 measured at the first time point and the downlink timing value T2 measured at the second time point is equal to or greater than an effective threshold value. The method of claim 16, wherein the validity verification unit, The T1 is measured within a period during which all serving cells in the TAG are deactivated and changed to an inactive state, and the T2 is measured within a period during which at least one serving cell of the TAG is changed to an activated state. Terminal, characterized in that. The method of claim 16, wherein the validity verification unit, And the terminal calculates the valid threshold value using a maximum range Tq that can correct the error of the uplink time by itself as a variable. The method of claim 18, wherein Tq = k * Ts, K is determined by any one of 2, 4, 8, and 16 according to a downlink bandwidth, and Ts is a sampling period. The method of claim 16, The receiving unit, characterized in that for receiving the valid threshold value from the base station.

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