KR101911211B1 - Apparatus and method for performing random access in wireless communication system - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus and method for performing random access in a wireless communication system
The present invention relates to a mobile communication system including a receiver for receiving time alignment group configuration information for classifying at least one serving cell configured in a terminal into a time alignment group and a random access preamble to a base station on one representative serving cell in the time alignment group A terminal including a transmitting unit to transmit is started.
According to the present invention, a procedure for acquiring a time alignment value for a serving cell that performs a random access procedure for ensuring and maintaining uplink time synchronization becomes clear, and time for acquiring uplink synchronization for a serving cell can be reduced And it is possible to reduce overhead due to excessive random access attempts by acquiring a time alignment value for a plurality of serving cells with a single random access procedure.

Description

[0001] APPARATUS AND METHOD FOR PERFORMING RANDOM ACCESS IN WIRELESS COMMUNICATION SYSTEM [0002]

The present invention relates to wireless communication, and more particularly, to an apparatus and method for performing random access in a wireless communication system.

In a typical wireless communication system, although a bandwidth between an uplink and a downlink is set to be different from each other, only one carrier is mainly considered. In the 3GPP (3rd Generation Partnership Project) LTE (Long Term Evolution), the number of carriers constituting the uplink and the downlink is 1 based on a single carrier, and the bandwidths of the UL and the DL are generally symmetrical to be. In this single carrier system, random access is performed using one carrier. However, as a multi-carrier system has been recently introduced, random access can be implemented through a plurality of component carriers.

A multi-carrier system refers to a wireless communication system capable of supporting carrier aggregation. Carrier aggregation is a technique for efficiently using a fragmented small band so as to achieve the same effect as using a logically large band by bundling a plurality of physically non-continuous bands in the frequency domain.

In order for a terminal to access a network, a random access process is performed. The random access procedure may be divided into a contention based random access procedure and a non-contention based random access procedure. The major difference between the contention based random access procedure and the non-contention based random access procedure is whether the random access preamble is dedicated to one UE. In the non-contention-based random access procedure, since the UE uses a dedicated random access preamble assigned only to itself, contention (or collision) with other UEs does not occur. Here, the contention means that two or more UEs attempt 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 UE uses randomly selected random access preamble.

The purpose of the terminal performing the random access procedure to the network may be initial access, handover, scheduling request, timing alignment, and the like.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an apparatus and method for performing random access in a wireless communication system.

It is another object of the present invention to provide an apparatus and method for performing random access in which a time alignment value commonly applied to a plurality of secondary serving cells is obtained in a single random access procedure.

Another aspect of the present invention is to provide an apparatus and method for classifying secondary serving cells to which the same time alignment value is applied into a plurality of groups.

Another aspect of the present invention is to provide an apparatus and a method for transmitting a random access response message including a time alignment value for each secondary serving cell group.

According to an aspect of the present invention, there is provided a terminal for performing random access in a wireless communication system. Wherein the UE comprises: a receiver for receiving time alignment group configuration information for classifying at least one serving cell configured in the UE into a timing alignment group (TAG) from a base station; And a transmitter for transmitting an access preamble to the base station.

Wherein the receiving unit receives from the base station a random access response message including a time advance command field in response to the random access preamble, and the time advance command field indicates the same uplink time of all serving cells in the time alignment group The time alignment value to be adjusted.

According to another aspect of the present invention, there is provided a method of performing random access by a terminal in a wireless communication system. The random access method includes: receiving time alignment group configuration information for classifying at least one serving cell configured in a UE into a time alignment group; receiving a random access preamble on one representative serving cell in the time alignment group; To the base station, and in response to the random access preamble, receiving from the base station a random access response message comprising a time advance command field.

The time advance command field indicates a time alignment value that equally adjusts the uplink time of all serving cells in the time alignment group.

According to another aspect of the present invention, there is provided a base station that performs random access in a wireless communication system. Wherein the base station comprises: an RRC processor for generating time alignment group configuration information for classifying at least one serving cell configured in the UE into a time alignment group; a transmitter for transmitting the time alignment group configuration information to the terminal; A time advance indicating a time alignment value that adjusts the uplink time of all serving cells in the time alignment group equally in response to the random access preamble, A random access processing section for generating a random access response message including an instruction field, and a transmission section for transmitting the random access response message to the terminal.

According to another aspect of the present invention, there is provided a method of performing random access by a base station in a wireless communication system. The random access method includes: transmitting time alignment group configuration information for classifying at least one serving cell configured in a UE into a time alignment group; transmitting a random access preamble on one representative serving cell in the time alignment group; And a time advance command field for indicating a time alignment value for adjusting the uplink time of all serving cells in the time alignment group equally in response to the random access preamble, And transmitting the message to the terminal.

According to the present invention, a procedure for acquiring a time alignment value for a serving cell that performs a random access procedure for ensuring and maintaining uplink time synchronization becomes clear, and time for acquiring uplink synchronization for a serving cell can be reduced And it is possible to reduce overhead due to excessive random access attempts by acquiring a time alignment value for a plurality of serving cells with a single random access procedure.

1 shows a wireless communication system to which the present invention is applied.
2 shows an example of a protocol structure for supporting multicarrier to which the present invention is applied.
FIG. 3 shows an example of a frame structure for a multi-carrier operation according to the present invention.
FIG. 4 shows a linkage between a downlink component carrier and an uplink component carrier in a multicarrier system to which the present invention is applied.
5 is a flowchart illustrating a random access method according to an exemplary embodiment of the present invention.
6 is a flowchart illustrating a random access procedure according to an exemplary embodiment of the present invention. This is a non-contention-based random access procedure.
FIG. 7 shows a MAC PDU structure for a random access response message to which the present invention is applied.
8 is a block diagram illustrating a structure of a MAC control element for a time advance command according to an exemplary embodiment of the present invention.
9A is a block diagram illustrating a structure of a MAC control element for a time advance command according to another example of the present invention.
9B is a block diagram illustrating a structure of a MAC control element for a time advance command according to another example of the present invention.
FIG. 10 is a flowchart illustrating a non-contention-based random access procedure according to another example of the present invention.
11 is an explanatory diagram illustrating a method of configuring a time alignment group and a method of determining time alignment values in a multi-carrier system according to the present invention.
12 is a flowchart illustrating a random access performing method according to another example of the present invention.
13 is a flowchart illustrating a random access performing method according to another example of the present invention.
14 is a flowchart illustrating a random access performing method according to another example of the present invention.
15 is an operation flowchart of a terminal performing random access according to an exemplary embodiment of the present invention.
16 is an operation flowchart of a base station performing random access according to an example of the present invention.
17 is a block diagram illustrating a base station and a terminal for performing random access according to an exemplary embodiment of the present invention.
18 is an example of a MAC subheader according to an example of the present invention.
19 is a diagram illustrating a MAC control element for a TAG according to an exemplary embodiment of the present invention.
20 is a diagram illustrating a MAC control element for a TAG according to another example of the present invention.
FIG. 21 shows an example in which the DCI according to the present invention is mapped to an extended physical downlink control channel.
22 shows another example in which the DCI according to the present invention is mapped to the extended physical downlink control channel.
23 shows another example in which the DCI according to the present invention is mapped to the extended physical downlink control channel.
24A and 24B are further block diagrams showing the structure of a MAC control element for a time advance command according to an example of the present invention.

Hereinafter, some embodiments will be described in detail with reference to exemplary drawings. It should be noted that, in adding reference numerals to the constituent elements of the drawings, the same constituent elements are denoted by the same reference symbols as possible even if they are shown in different drawings. In the following description of the embodiments of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present disclosure rather unclear.

In describing the components of the present specification, terms such as first, second, A, B, (a), and (b) may be used. These terms are intended to distinguish the constituent elements from other constituent elements, and the terms do not limit the nature, order or order of the constituent elements. When a component is described as being "connected", "coupled", or "connected" to another component, the component may be directly connected or connected to the other component, Quot; may be "connected," "coupled," or "connected. &Quot;

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

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

Referring to FIG. 1, a wireless communication system 10 is widely deployed to provide various communication services such as voice, packet data, and the like. The wireless communication system 10 includes at least one base station 11 (BS). Each base station 11 provides communication services to specific cells (15a, 15b, 15c). The cell may again be divided into multiple regions (referred to as sectors).

A mobile station (MS) 12 may be fixed or mobile and may be a user equipment (UE), a mobile terminal (MT), a user terminal (UT), a subscriber station (SS), a wireless device, (personal digital assistant), a wireless modem, a handheld device, and the like. The base station 11 may be called by other terms such as an evolved-NodeB (eNB), a base transceiver system (BTS), an access point, a femto base station, a home node B, . The cell should be interpreted in a generic sense to indicate a partial area covered by the base station 11 and is meant to cover various coverage areas such as a megacell, a macro cell, a microcell, a picocell, and a femtocell.

Hereinafter, downlink refers to communication from the base station 11 to the terminal 12, and uplink refers to communication from the terminal 12 to the base station 11. In the downlink, the transmitter may be part of the base station 11, and the receiver may be part of the terminal 12. In the uplink, the transmitter may be part of the terminal 12, and the receiver may be part of the base station 11. There are no restrictions on multiple access schemes applied to wireless communication systems. (CDMA), Time Division Multiple Access (TDMA), Frequency Division Multiple Access (FDMA), Orthogonal Frequency Division Multiple Access (OFDMA), Single Carrier-FDMA , OFDM-CDMA, and the like. A TDD (Time Division Duplex) scheme in which uplink and downlink transmissions are transmitted using different time periods, or an FDD (Frequency Division Duplex) scheme in which they are transmitted using different frequencies can be used.

A carrier aggregation (CA) supports a plurality of carriers and is also referred to as spectrum aggregation or bandwidth aggregation. The individual unit carriers tied by carrier aggregation are called component carriers (CCs). Each element carrier is defined as the bandwidth and center frequency. Carrier aggregation is introduced to support increased throughput, prevent cost increases due to the introduction of wideband radio frequency (RF) devices, and ensure compatibility with existing systems. For example, if five elementary carriers are allocated as the granularity of a carrier unit having a bandwidth of 20 MHz, it can support a bandwidth of up to 100 MHz.

Carrier aggregation can be divided into contiguous carrier aggregation between successive element carriers in the frequency domain and non-contiguous carrier aggregation between discontinuous element carriers. The number of carriers aggregated between the downlink and the uplink may be set differently. The case where the number of downlink element carriers is equal to the number of uplink element carriers is referred to as symmetric aggregation and the case where the number of downlink element carriers is different is referred to as asymmetric aggregation.

The size (i.e. bandwidth) of the element carriers may be different. For example, if five element carriers are used for a 70 MHz band configuration, then 5 MHz element carrier (carrier # 0) + 20 MHz element carrier (carrier # 1) + 20 MHz element carrier (carrier # 2) + 20 MHz element carrier (carrier # 3) + 5 MHz element carrier (carrier # 4).

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

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

Referring to FIG. 2, a common 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 as 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), a 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 the resource allocation of the uplink transmission. A 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 HARQ ACK / NAK signal in response to uplink transmission. A physical uplink control channel (PUCCH) carries uplink control information such as HARQ ACK / NAK, scheduling request and CQI for downlink transmission. Physical uplink shared channel (PUSCH) carries an uplink shared channel (UL-SCH). A physical random access channel (PRACH) carries a random access preamble.

FIG. 3 shows an example of a frame structure for a multi-carrier operation according to the present invention.

Referring to FIG. 3, a frame is composed of 10 subframes. The subframe includes a plurality of OFDM symbols. Each carrier may have its own control channel (e.g. PDCCH). The multi-carriers may or may not be adjacent to each other. The terminal may support one or more carriers according to its capabilities.

Element carriers can be divided into Primary Component Carrier (PCC) and Secondary Component Carrier (SCC) depending on whether they are active or not. The primary carrier is always the active carrier, and the sub-carrier is the carrier that is activated / deactivated according to certain conditions. Activation means that the transmission or reception of traffic data is performed or is in a ready state. Deactivation means that transmission or reception of traffic data is impossible and measurement or transmission / reception of minimum information is possible. The terminal may use only one major carrier or use one or more sub-carrier with carrier. A terminal may be allocated a primary carrier and / or secondary carrier from a base station.

FIG. 4 shows a linkage between a downlink component carrier and an uplink component carrier in a multicarrier system to which the present invention is applied.

Referring to FIG. 4, the downlink component carriers D1, D2, and D3 are aggregated in the downlink, and the uplink component carriers U1, U2, and U3 are aggregated in the uplink. Where Di is the index of the downlink component carrier and Ui is the index of the uplink component carrier (i = 1, 2, 3). At least one downlink element carrier is a dominant carrier and the remainder is a subordinate element carrier. Similarly, at least one uplink component carrier is a dominant carrier and the remainder is a subindent carrier. For example, D1, U1 are the dominant carriers, and D2, U2, D3, U3 are the subelement carriers.

In the FDD system, the downlink component carrier and the uplink component carrier are set to be 1: 1. For example, D1 is connected to U1, D2 to U2, and D3 to 1: 1 respectively. The UE establishes a connection between the downlink component carriers and the uplink component carriers through the system information transmitted by the logical channel BCCH or the terminal dedicated RRC message transmitted by the DCCH. Each connection setting may be cell specific or UE specific.

4 illustrates only a 1: 1 connection setup between the downlink component carrier and the uplink component carrier, but it is needless to say that a 1: n or n: 1 connection setup can also be established. The index of the element carrier does not match the order of the element carriers or the position of the frequency band of the corresponding element carrier.

A primary serving cell is a serving cell that provides security input and NAS mobility information in an RRC establishment or re-establishment state. Depending on the capabilities of the terminal, at least one cell may be configured to form a set of serving cells together with a main serving cell, said at least one cell being referred to as a secondary serving cell.

Therefore, the set of serving cells set for one UE may consist of only one main serving cell, or may consist of one main serving cell and at least one secondary serving cell.

The downlink component carrier corresponding to the main serving cell is referred to as a downlink principal carrier (DL PCC), and the uplink component carrier corresponding to the main serving cell is referred to as an uplink principal carrier (UL PCC). In the downlink, the element carrier corresponding to the secondary serving cell is referred to as a downlink sub-element carrier (DL SCC), and in the uplink, an elementary carrier corresponding to the secondary serving cell is referred to as an uplink sub-element carrier (UL SCC) do. Only one DL serving carrier may correspond to one serving cell, and DL CC and UL CC may correspond to each other.

Therefore, the communication between the terminal and the base station in the carrier system 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, a UE transmits a preamble using UL CC is equivalent to transmitting a preamble using a main serving cell or a secondary serving cell. In addition, receiving a downlink information using a DL CC by a UE can be regarded as equivalent to receiving downlink information using a main serving cell or a secondary serving cell.

On the other hand, the main serving cell and the secondary serving cell have the following characteristics.

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

Second, the main serving cell is always active, while the secondary serving cell is a carrier that is activated / deactivated according to certain conditions. The specific condition may be when the UE has received the activation / deactivation MAC CE message or the deactivation timer in the UE has expired.

Third, when the main serving cell experiences a radio link failure (RLF), the RRC reconnection is triggered, but when the secondary serving cell experiences RLF, the RRC reconnection is not triggered. The radio link failure occurs when the downlink performance is maintained below the threshold for a certain time or when the RACH fails more than the threshold number of times.

Fourth, the main serving cell may be changed by a security key change or a handover procedure accompanied by the RACH procedure. However, in the case of a contention resolution message, only a Physical Downlink Control Channel (PDCCH) indicating a CR should be transmitted through the main serving cell, and CR information may be transmitted through the main serving cell or the serving cell. Lt; / RTI >

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

Sixth, the main serving cell always consists of DL PCC and UL PCC in pairs.

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

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

Ninth, the main serving cell transmits PDCCH (e.g., downlink allocation information) assigned to a UE-specific search space set for transmitting control information for a specific UE in a region for transmitting control information Or PDCCH (e.g., system information (e.g., uplink information) allocated to a common search space set for transmitting control information to all terminals in the cell or to a plurality of terminals conforming to a specific condition, SI), a random access response (RAR), and transmit power control (TPC). On the other hand, only the UE-specific search space can be set as the serving cell. That is, since the UE can not confirm the common search space through the secondary serving cell, it can not receive the control information transmitted only through the common search space and the data information indicated by the control information.

The technical idea of the present invention regarding the characteristics of the main serving cell and the secondary serving cell is not necessarily limited to the above description, but is merely an example and may include more examples.

In a wireless communication environment, a propagation delay is propagated while a transmitter propagates and propagates in a receiver. Therefore, even if the transmitter and the receiver both know the time at which the radio wave is propagated correctly, the arrival time of the signal to the receiver is influenced by the transmission / reception period distance and the surrounding propagation environment. If the receiver does not know exactly when the signal transmitted by the transmitter is received, it will receive the distorted signal even if it fails to receive or receive the signal.

Therefore, in the wireless communication system, synchronization between the base station and the terminal must be predetermined in order to receive the information signal regardless of the downlink / uplink. Types of synchronization include frame synchronization, information symbol synchronization, and sampling period synchronization. Sampling period synchronization is the most basic motivation to distinguish physical signals.

The downlink synchronization acquisition is performed in the UE based on the signal of the base station. The base station transmits a mutually agreed specific signal for facilitating downlink synchronization acquisition at the terminal. The terminal must be able to accurately identify the time at which a particular signal sent from the base station is transmitted. In case of downlink, since one base station simultaneously transmits the same synchronization signal to a plurality of terminals, each of the terminals can acquire synchronization independently of each other.

In case of uplink, the base station receives signals transmitted from a plurality of terminals. When the distance between each terminal and the base station is different, signals received by each base station have different transmission delay times. When uplink information is transmitted on the basis of the acquired downlink synchronization, Is received at the corresponding base station. In this case, the base station can not acquire synchronization based on any one of the terminals. Therefore, uplink synchronization acquisition requires a procedure different from downlink.

On the other hand, the need for uplink synchronization acquisition may vary for each multiple access scheme. For example, in the case of a CDMA system, the BS can separate the uplink signals even if the BS receives the uplink signals of the other terminals at different times. However, in a wireless communication system based on OFDMA or FDMA, a base station simultaneously receives uplink signals of all terminals and demodulates them at a time. Therefore, as the uplink signals of a plurality of terminals are received at the correct time, the reception performance is improved. As the difference of the reception time of each terminal signal becomes larger, the reception performance drastically deteriorates. Therefore, uplink synchronization acquisition may be essential.

A random access procedure is performed for uplink synchronization acquisition. During the random access procedure, the UE acquires uplink synchronization based on a timing alignment value transmitted from the base station. Once the uplink synchronization is obtained, the terminal starts a time alignment timer. When the time alignment timer is in operation, the terminal and the base station are in a state in which uplink synchronization is performed. If the time alignment timer expires or does not operate, the terminal and the base station are not synchronized with each other, and the UE does not perform uplink transmission other than the transmission of the random access preamble.

Meanwhile, in a multi-carrier system, one terminal communicates with a base station via a plurality of element carriers or a plurality of serving cells. If all the signals of the plurality of serving cells set in the UE have the same time delay, the UE can acquire uplink synchronization for all the serving cells with only one time alignment value. On the other hand, if the signals of the plurality of serving cells have different time delays, a different time alignment value is required for each serving cell. That is, multiple timing alignment values are required. If the UE performs random access to each serving cell in order to obtain multi-time alignment values, overhead occurs in the limited uplink resources, and the complexity of the random access may increase. There is a need for a method of performing random access in a multi-carrier system that reduces such overhead and complexity.

5 is a flowchart illustrating a random access method according to an exemplary embodiment of the present invention.

Referring to FIG. 5, the terminal transmits classifying assistant information to a base station (S500). The classification support information provides information or criteria necessary to classify at least one serving cell configured in the terminal into a timing alignment group (TAG). For example, the classification support information may include at least one of geographical location information of the terminal, neighbor cell measurement information of the terminal, network deployment information, and serving cell configuration information. The geographical location information of the terminal indicates a location that can be expressed by latitude, longitude, height, etc. of the terminal. The neighbor cell measurement information of the UE includes a reference signal received power (RSRP) of a reference signal transmitted in a neighboring cell or a reference signal received quality (RSRQ). The network location information is information indicating the location of a base station, a frequency selective repeater (FSR), or a remote radio head (RRH). The serving cell configuration information is information about a serving cell configured in the UE. Step S500 shows that the terminal transmits the classification support information to the base station, but the base station may separately know or may hold the classification support information. In this case, the random access according to the present embodiment may be performed with step S500 omitted.

The base station classifies the serving cells into a time alignment group (S505). The serving cells may be classified or organized into time aligned groups according to the classification support information. The time alignment group is a group containing at least one serving cell, and the same time alignment value is applied to the serving cells in the time alignment group. For example, if the first serving cell and the second serving cell belong to the same time alignment group TAG1, the same time alignment value TA ₁ is applied to the first serving cell and the second serving cell. On the other hand if in the first serving cell and a second serving cell is another time alignment group (TAG1, TAG2), first, the serving cell and a second serving cell, it is applied to each of the TA ₁ and TA ₂ different time alignment values. The time alignment group may include a main serving cell, may include at least one secondary serving cell, and may include a primary serving cell and at least one secondary serving cell.

As an example, the base station may configure a time alignment group specifically for the terminal. Since the serving cell configuration information is individually and independently configured for each UE, if it is used as the classification support information, the time alignment group can also be configured independently for each UE. For example, let the time alignment groups for the first terminal be TAG1_UE1 and TAG2_UE1, and the time alignment groups for the second terminal be TAG1_UE2 and TAG2_UE2. TAG1_UE1 = {first serving cell}, TAG2_UE1 = {second serving cell}, if the first and second serving cells are configured in the first terminal, and TAG1_UE2 = {First serving cell, second serving cell}, TAG2_UE2 = {third serving cell, fourth serving cell}.

As another example, a base station may configure a time alignment group specifically for a cell. Since the network allocation information is determined irrespective of the terminal, if it is used as the classification support information, the time alignment group can be configured cell-centric regardless of the terminal. For example, assume that a first serving cell in a particular frequency band is always served in a frequency selective repeater or a remote radio head, and a second serving cell is served through a base station. In this case, the first serving cell and the second serving cell are classified into different time alignment groups for all terminals in the service area of the base station.

The base station transmits time alignment group configuration information (TAG configuration) to the terminal (S510). And classifies at least one serving cell configured in the UE into a time alignment group. That is, the time alignment group configuration information describes a state in which the time alignment group is configured. As an example, the time alignment group setting information may include an index field of a time alignment group, an index field of each time alignment group, and an index field of a serving cell included in each time alignment group, Describe the configured state.

As another example, the time alignment group configuration information may further include representative serving cell information within each time alignment group. The representative serving cell is a serving cell capable of performing a random access procedure for uplink synchronization maintenance and setting in each time alignment group. The representative serving cell may be referred to as a special serving cell or a reference serving cell. If the time alignment group configuration information does not include a representative serving cell, the UE can select a representative serving cell in each time alignment group, unlike the above embodiment.

The terminal performs a random access procedure for the base station (S515). The random access procedure may be performed on a non-contention-based or contention-based basis. Since the procedure differs depending on whether the random access procedure is non-contention-based or contention-based, the following description will be given with reference to the drawings. Step S515 follows the procedure of FIG. 6 for a non-contention based case and follows the procedure of FIG. 10 for a contention based case.

6 is a flowchart illustrating a random access procedure according to an exemplary embodiment of the present invention. This is a non-contention-based random access procedure.

Referring to FIG. 6, the BS selects one of dedicated random access preambles reserved for a non-contention-based random access procedure among all available random access preambles, selects an index of the selected random access preamble, And transmits preamble allocation information (RA Preamble assignment) including frequency resource information to the terminal (S600). For a random access procedure based on a non-contention, the UE needs to be allocated a dedicated random access preamble from the base station that has no possibility of collision.

As an example, if the random access procedure is performed during the handover procedure, the UE may obtain a dedicated random access preamble from the handover command message. As another example, if the random access procedure is performed at the request of the base station, the UE can acquire a dedicated random access preamble through the PDCCH, physical layer signaling. In this case, the physical layer signaling may include the fields shown in Table 1 as the downlink control information (DCI) format 1A.

bits. 모든 비트들이 1로 설정됨
- 프리앰블 인덱스(Preamble Index) - 6 bits
- PRACH 마스크 인덱스(Mask Index) - 4 bits
- 하나의 PDSCH 부호어의 간이 스케줄링 할당을 위한 포맷 1A의 모든 남은 비트들이 0으로 설정됨Carrier indicator field (CIF) - 0 or 3 bits.
- Flag for format 0 / 1A identification - 1 bit (0 indicates format 0, 1 indicates format 1A)
If the Format 1A CRC is scrambled by the C-RNTI and the remaining fields are set as follows, Format 1A is used for the random access procedure initiated by the PDCCH command (order).
-bottom-
- Localized / Distributed VRB allocation flag - 1 bit. Set to 0
- Resource block allocation -

bits. All bits set to 1
- Preamble Index - 6 bits
- PRACH mask index (Mask Index) - 4 bits
All remaining bits of format 1A for simple scheduling assignment of one PDSCH codeword are set to zero

Referring to Table 1, the preamble index is an index indicating a preamble of a selected one of dedicated random access preambles reserved for a non-contention based random access procedure, and the PRACH mask index is usable time / frequency resource information. The available time / frequency resource information is again indicated by the frequency division duplex (FDD) system and the time division duplex (TDD) system as shown in Table 2.

PRACH
Mask index Allowed PRACH (FDD) Allowed PRACH (TDD) 0 all all One PRACH resource index 0 PRACH resource index 0 2 PRACH resource index 1 PRACH resource index 1 3 PRACH Resource Index 2 PRACH Resource Index 2 4 PRACH Resource Index 3 PRACH Resource Index 3 5 PRACH Resource Index 4 PRACH Resource Index 4 6 PRACH Resource Index 5 PRACH Resource Index 5 7 PRACH Resource Index 6 Reserved 8 PRACH Resource Index 7 Reserved 9 PRACH Resource Index 8 Reserved 10 PRACH Resource Index 9 Reserved 11 All even PRACH opportunities in the time domain,
The first PRACH resource index in the subframe All even PRACH opportunities in the time domain,
The first PRACH resource index in the subframe 12 All odd PRACH opportunities in the time domain,
The first PRACH resource index in the subframe All odd PRACH opportunities in the time domain,
The first PRACH resource index in the subframe 13 Reserved The first PRACH resource index in the subframe 14 Reserved The second PRACH resource index in the subframe 15 Reserved The third PRACH resource index in the subframe

The MS transmits the allocated dedicated random access preamble to the BS via the representative serving cell (S605). The representative serving cell is a serving cell selected to transmit a random access preamble in a time alignment group configured in the UE. Representative serving cells may be selected per time alignment group. The UE may also transmit a random access preamble on a representative serving cell in any one of the plurality of time alignment groups and a random access preamble on each representative serving cell in two or more time alignment groups . For example, assume that the time alignment groups configured in the UE are TAG1 and TAG2, and TAG1 = {first serving cell, second serving cell, third serving cell}, TAG2 = {fourth serving cell, fifth serving cell} . If the representative serving cell of TAG1 is the second serving cell and the representative serving cell of TAG2 is the fifth serving cell, the terminal transmits the allocated dedicated random access preamble to the base station through the second serving cell or the fifth serving cell. In other words, the random access preamble is not transmitted in the serving cell other than the representative serving cell in each time alignment group.

The random access preamble may proceed after the representative serving cell is activated. In addition, the random access procedure for the secondary serving cell may be initiated by a PDCCH indication (order) transmitted by the base station. Although the non-contention-based random access procedure is described in the present embodiment, it may be applied to a contention based random access procedure according to the intention of the base station.

If only a time alignment value (hereinafter referred to as a representative time alignment value) for the representative serving cell is acquired, the terminal can use the representative time alignment value as the time alignment value of another serving cell. This is because the same time alignment values are applied to the serving cells belonging to the same time alignment group. The redundancy, complexity and overhead of the random access procedure can be reduced by blocking unnecessary random access procedures in a particular serving cell.

The base station transmits a random access response message to the terminal (S610). As an example, the random access response message includes a timing advance command (TAC) field. Time advance command field may be an integral multiple, for example, 16T _s current indicates a relative change in the uplink time of the uplink time and the sampling time (T _s). The time advance command field indicates a time alignment value that equally adjusts the uplink time of all serving cells in the time alignment group. The time alignment value can be given as a specific index. An example of a method for determining a time alignment value is described in FIG. As another example, the random access response message includes an index of a time alignment group that includes a time advance command and a representative serving cell. The data structure for the time advance command is described in Figs.

The UE checks the time advance command and / or the time alignment group index in the random access response message and adjusts the uplink time of all the serving cells in the identified time alignment group by the time alignment value according to the time advance command. An example of the uplink time adjusted by the time alignment value is shown in Equations (1) to (4). If there is a time advance instruction and / or a time alignment group index for a plurality of time alignment groups in the random access response message, the UE transmits the uplink time for the serving cell (s) As shown in FIG.

The base station can check which serving cell transmitted the random access preamble based on the received random access preamble and time / frequency resources. Accordingly, the random access response message is transmitted to the UE through a physical downlink control channel (PDSCH) indicated by a PDCCH scrambled with a Cell-Radio Network Temporary Identifier (C-RNTI) of the UE.

The C-RNTI is an identifier allocated to each mobile station by the base station in order to confirm the RRC connection established with the base station and the scheduling information transmitted by the base station. The base station must allocate different C-RNTI values for each user in each base station. Each C-RNTI is assigned a temporary C-RNTI through a random access response in a contention-based random access procedure performed by the UE for an RRC connection. When the random access procedure is finally succeeded, the UE transmits the temporary C- -RNTI. The PDCCH indicating the random access response message may be transmitted through the scheduling cell for the representative serving cell or for the representative serving cell. In addition, when a random access response message is transmitted to a MAC control element for a time advance command, that is, to a MAC control element composed of contents including only a TA value (6 bits or 11 bits) and TAG ID information, The PDCCH indicating the response message and the random access response message can be received through the serving cell other than the serving cell in which the random access preamble is transmitted. That is, the random access response transmission can be transmitted without being restricted to the scheduling for a specific serving cell.

(PDCCH order) indicating the random access procedure and a physical layer (L1) indicating which radio resource (RB) is allocated a random access response message, which is a MAC layer message, The downlink control information (DCI) information may be transmitted through a lower layer control channel defined by EPDCCH (Extended PDCCH). The EPDCCH consists of a resource block (RB) pair. Herein, the RB pair is defined as RB for each of two slots constituting one subframe, and may be defined as a pair when each of the RBs is configured as one pair. Here, each RB constituting the RB pair can not be composed of slots having the same time. The RBs may be composed of RBs existing in the same frequency band or may be composed of RBs existing in different frequency bands. This is illustrated in FIGS.

FIG. 21 shows an example in which the DCI according to the present invention is mapped to an extended physical downlink control channel.

Referring to FIG. 21, a downlink subframe includes a control region 2100 and a data region 2105. The PDCCH 2110 is mapped to the control region 2100 and has a length of 2 to 4 OFDM symbols in the time domain. In the data area 2105, an EPDCCH (Extended PDCCH) 2115 and a PDSCH 2120 are mapped. The PDCCH 2110 indicates an area in which the EPDCCH 2115 is transmitted and the EPDCCH 2115 indicates a PDSCH 2120 including the actually transmitted user information. At this time, the EPDCCH 2115 is mapped to the resource indicated by the PDCCH 2110. Also, the EPDCCH 2115 and the PDCCH 2110 may be mapped to different DL CCs, and the PDCCH 2110 may perform cross carrier scheduling. However, in the EPDCCH 2115, the PDSCH 2120 must always exist in the same DL CC.

The EPDCCH transmits the PDCCH indication (order) and the DCI for the physical layer (L1) information of the random access response message.

22 shows another example in which the DCI according to the present invention is mapped to the extended physical downlink control channel.

Referring to FIG. 22, the PDCCH 2210 mapped to the control area 2200 indicates the search space 2215 of the EPDCCH to which the data area 2205 is mapped. The UE transmits the EPDCCH 2210 in the search space 2215 of the EPDCCH using a blind decoding method used for receiving the PDCCH 2210, i.e., a data detection method based on a cyclic redundancy check (CRC) . Also, the EPDCCH and the PDCCH 2210 may be mapped to different DL CCs and may be inter-carrier scheduling by the PDCCH 2210. The EPDCCH includes a PDCCH indication (order) and physical layer (L1) information of a random access response message.

23 shows another example in which the DCI according to the present invention is mapped to the extended physical downlink control channel.

Referring to FIG. 23, the EPDCCH 2305 exists in the PDSCH region 2310 regardless of the PDCCH. The information on the search space 2310 of the EPDCCH may be provided in the upper layer (RRC) by providing information (e.g., search space bandwidth information) about different search spaces for each terminal or a search space shared by a plurality of terminals Information is provided by the RRC signaling or broadcasting scheme. Here, the control area 2300 may not exist. That is, it may be removed.

In this case, the terminal must blind-decode the search space 2310 of the EPDCCH in order to acquire the EPDCCH 2305. [ If the search space 2310 of the EPDCCH is 1, i.e., the search space 2310 of the EPDCCH is defined as a space where only one EPDCCH can be mapped, a data detection method using the C-RNTI allocated to each terminal It is possible to use a method of determining whether or not to receive its own EPDCCH. Also, the EPDCCH 2305 and the PDSCH 2315 must always exist in the same DL CC.

The BS determines whether the UE receives the EPDCCH 2305 or the PDCCH in the serving cell, and it can be configured for each serving cell through RRC signaling. Therefore, if the UE is set to receive EPDCCHs 2115, 2223, and 2305 in any serving cell, the UE does not receive the UE-specific PDCCH. Therefore, the UE can receive the random access start indicator including the preamble allocation information only through the EPDCCHs 2115, 2223, and 2305 in the random access process performed in any serving cell. Also, the UE can receive random access response information in the PDSCHs 2120, 2205, and 2315 indicated by the EPDCCHs 2115, 2223, and 2305.

Referring again to FIG. 6, in the non-contention-based random access procedure, the random access response message is received as compared to the contention-based random access procedure, and it is determined that the random access procedure has been normally performed and the random access procedure is terminated. If the preamble index in the preamble allocation information received by the UE is '000000', the UE randomly selects one of the contention-based random access preambles and sets the PRACH mask index value to '0' do. In addition, the preamble allocation information may be transmitted to a terminal through a higher layer message such as RRC (e.g., mobility control information (MCI) in a handover command).

FIG. 7 shows a MAC PDU structure for a random access response message to which the present invention is applied.

7, the MAC PDU 700 includes a MAC header 710, at least one MAC control element 720, ..., 725, at least one MAC SDU (Service Data Unit) 730-1, ..., 730-m, and padding 740.

The MAC header 710 includes at least one sub-header 710-1, 710-2, ..., 710-k, and each of the subheaders 710-1, 710-2, ..., ., 710-k correspond to one MAC SDU or one MAC control element 720, ..., 725 or padding 740, respectively. The order of the subheaders 710-1, 710-2, ..., 710-k corresponds to the corresponding MAC SDU, MAC control element 720, ..., 725 or padding 740 ).

Each of the subheaders 710-1, 710-2, ..., and 710-k includes four fields of R, R, E, and LCID. Field. A subheader including four fields is a subheader corresponding to the MAC control element 720, ..., 725 or a padding 740, and a subheader including six fields is a subheader corresponding to a MAC SDU .

The Logical Channel ID (LCID) field is an identification field that identifies a logical channel corresponding to a MAC SDU or identifies a MAC control element 720, ..., 725 or a type of padding, When each subheader 710-1, 710-2, ..., 710-k has an octet structure, the LCID field may be 5 bits.

For example, the LCID field indicates whether the MAC control element 720, ..., 725 is a MAC control element for instructing activation / deactivation of a serving cell, a contention resolution identifier Resolution Identity) Identifies whether it is a MAC control element or a MAC control element for a time advance command. The MAC control element for the time advance command is a MAC control element used for time alignment in random access.

LCID Index LCID value 00000 CCCH 00001-01010 Identifier of the logical channel 01011-11010 Reserved 11011 Enable / Disable 11100 The terminal contention resolution identifier 11101 TAC 11110 DRX command 11111 padding

Referring to Table 3, if the value of the LCID field is 11101, the corresponding MAC control element is the MAC control element for the time advance command.

On the other hand, when a time advance command is given for a plurality of serving cells because a plurality of serving cells are configured in the UE, an LCID field may be given as shown in Table 4. [

LCID Index LCID value 00000 CCCH 00001-01010 Identifier of the logical channel 01011-11001 Reserved 11010 Extended TAC (Extened Timing Advance Command) 11011 Enable / Disable 11100 The terminal contention resolution identifier 11101 TAC 11110 DRX command 11111 padding

Referring to Table 4, if the value of the LCID field is 11010, the corresponding MAC control element is a MAC control element for time advance commands for a plurality of serving cells.

Next, the MAC control elements 720, ..., and 725 are control messages generated by the MAC layer. A padding 740 is a predetermined number of bits added to make the size of the MAC PDU constant. MAC control elements 720 ... 725, MAC SDUs 730-1 through 730-m, and padding 740 are collectively referred to as a MAC payload.

When a UE transmits a random access preamble to a base station on a representative serving cell of a specific time alignment group, the base station transmits an index of a specific time alignment group and a time advance command commonly applied to the specific time alignment group to the UE, A MAC control element for time advance command may be used. Examples of MAC control elements for time advance commands are shown in FIG. 8 or FIGS. 9a, 9b.

8 is a block diagram illustrating a structure of a MAC control element for a time advance command according to an exemplary embodiment of the present invention.

Referring to FIG. 8, a MAC control element for a time advance command includes an index field (G ₁ , G ₀ ) and a timing advance command (TAC) field of a time alignment group (TAG). When the MAC control element for the time advance command is an octet structure, the index field of the time alignment group is 2 bits and the time advance command field is 6 bits. The time alignment group index is defined in the time alignment group configuration information. For example, if there are four time alignment groups and the time alignment group index is 1, 2, 3, 4, then G ₁ , G ₀ = {00, 01, 10, 11}. If the maximum number of time alignment groups is two, any one of the 2-bit time alignment group index fields, for example G _1, may be set to a reserved bit R, or if the time alignment group index field is defined to be only one bit And the time advance command field may be defined as 7 bits. The number of bits in the time alignment group index field and the number of bits in the time advance command field are only illustrative, and are not necessarily limited to two and six, respectively. In addition, the index value of the time alignment group including the main serving cell may be fixed to '00' or '0'.

24A and 24B are further block diagrams showing the structure of a MAC control element for a time advance command according to an example of the present invention.

Referring to FIG. 24A, a MAC control element for a time advance command includes an index field (G ₁ , G ₀ ) and a timing advance command (TAC) field of a time alignment group (TAG). When the MAC control element for the time advance command is a structure composed of two octets, the reserved bits are 3 bits, the index field of the time alignment group is 2 bits, and the time advance command field is 11 bits . If the index field of the time alignment group is 1 bit or 3 bits, the reserved bits may be 4 bits or 2 bits, respectively. As shown in FIG. 24B, one bit of the reserved bits may be set to a bit X that does not use the most significant bit, similar to the format in the random access response message used in the existing LTE system.

When a plurality of time alignment groups are configured in the UE, the UE transmits a random access preamble onto representative serving cells of each time alignment group. That is, when the UE transmits a plurality of random access preambles on the plurality of serving cells to the base station in the same subframe, the base station must send time alignment values (or time reduction commands) for each time alignment group to the UE. Thus, a MAC control element is also required to indicate a time alignment value for a plurality of time alignment groups.

9A is a block diagram illustrating a structure of a MAC control element for a time advance command according to another example of the present invention.

Referring to FIG. 9A, the MAC control element for the time advance command includes octet 1 (Oct 1), ..., octet N (Oct N). Each octet includes an index field (G ₁ , G ₀ ) and a timing advance command (TAC) field of the time alignment group (TAG).

For example, let the UE transmit the random access preamble to the base station in the first representative serving cell designated in TAG1 and in the second representative serving cell specified in TAG2, respectively. The base station generates a random access response (RAR) message in response to the random access preamble, and the random access response message includes a MAC control element for a time advance instruction of two octets. Here, the first octet includes an index field of a first time alignment group indicating an index of TAG1 and a first time advance command field indicating a time alignment value of TAG1. The second octet includes an index field of a second time alignment group indicating an index of TAG2 and a second time advance command field indicating a time alignment value of TAG2.

The UE applies time alignment values of TAG1 to all serving cells belonging to TAG1 to perform time alignment and applies time alignment values of TAG2 to all serving cells belonging to TAG2 to perform time alignment.

9B is a block diagram illustrating a structure of a MAC control element for a time advance command according to another example of the present invention.

Referring to FIG. 9B, the MAC control element for the time advance command includes octet 1 (Oct 1), ..., octet N (Oct N). Octet 1 contains an indicator for each serving cell (or CC). This indicator may indicate the presence or absence of a time advance command field for the serving cell. For example, G0 indicates whether there is a time advance command field for TAG0, i.e., a TAG including a main serving cell, G1 indicates whether a time advance command field for TAG1 exists, G7 indicates time advance command for TAG7 This is an indicator that indicates whether or not an instruction field exists. Therefore, G0, G1, and G3 indicating TAG0, TAG1, and TAG3 are set to 1, and other G2 and G4 to G7 are set to 0. The TAC values for TAG0, TAG1, and TAG3 are mapped in order. 9B, the TAC value can be set for the corresponding TAG that needs to be updated for the specific TAG. The remaining octets 2, ..., octet N include the reserved field R and the TAC field.

10 is a flowchart illustrating a random access procedure according to another example of the present invention. This is a contention based random access procedure. The mobile station needs uplink synchronization to transmit and receive data to and from the base station. The MS may proceed to receive information required for synchronization from the BS for uplink synchronization. The random access procedure may be applied to a case where the UE newly joins the network by handover or the like, and may be performed in various situations such as the state of synchronization or RRC changing from RRC_IDLE to RRC_CONNECTED after coupling to the network.

10, the UE randomly selects one preamble signature from a random access preamble signature set, and transmits a random access preamble according to the selected preamble signature to a base station (BS) using a PRACH resource (PRACH resource) (S1000). The representative serving cell is a serving cell selected to transmit a random access preamble in a time alignment group configured in the UE.

The meaning of selecting to transmit the random access preamble may mean that it has received configuration information for transmitting a preamble from among all the serving cells in the time alignment group, It may mean that a random access procedure is instructed through a PDCCH indication (order) among the serving cells of the serving cell. The representative serving cell is a serving cell including a timing reference downlink CC serving as a reference for applying a TA value received through a random access response in the future.

Representative serving cells may be selected per time alignment group. The UE may also transmit a random access preamble on a representative serving cell in any one of the plurality of time alignment groups and a random access preamble on each representative serving cell in two or more time alignment groups .

The random access preamble may proceed after the representative serving cell is activated. In addition, the random access procedure for the secondary serving cell may be initiated by a PDCCH indication (order) transmitted by the base station.

The information on the configuration of the random access preamble set can be obtained from the base station through a part of system information or a handover command message. Here, the UE may recognize a RA-RNTI (Random Access-Radio Network Temporary Identifier) in consideration of a frequency resource and a transmission time point temporarily selected for preamble selection or RACH transmission.

The base station transmits a random access response message to the terminal as a response to the random access preamble of the received terminal (S1005). The channel used at this time is the PDSCH. The random access response message is transmitted in the form of a MAC PDU according to FIGS. The random access response message includes a time advance command for uplink synchronization of the UE, uplink radio resource allocation information, a random access preamble identifier (RAPID) for identifying UEs performing random access, Information about the time slot in which the preamble was received, and a temporary identifier of the UE such as a temporary C-RNTI. The random access preamble identifier is used to identify the received random access preamble.

In step S1010, the MS transmits uplink data including a random access identifier to the BS through a PUSCH at a scheduling time determined based on a time alignment value according to a time advance command. The uplink data may include an RRC connection request, a tracking area update, a scheduling request, or buffer status reporting for data to be transmitted on the uplink by the UE. have. The random access identifier may include a temporary C-RNTI, a C-RNTI (state included in the UE), or a UE contention resolution identifier. As the time alignment value is applied, the terminal starts or restarts a time alignment timer. If the time alignment timer was previously running, restart the time alignment timer, and start the time alignment timer if the time alignment timer was not previously running.

In steps S1000 to S1010, the random access preamble transmission of the plurality of UEs may collide with each other, so the base station transmits a contention resolution message to the UE indicating that the random access is successfully completed (S1015). The contention resolution message may include a random access identifier. Contention in the contention-based random access procedure occurs because the number of possible random access preambles is finite. Since a unique random access preamble can not be assigned to all UEs in a cell, the UE selects and transmits random access preamble randomly among the random access preamble sets. Accordingly, two or more UEs can select and transmit the same random access preamble through the same PRACH resource.

At this time, all of the uplink data transmission fails, or the base station successfully receives only the uplink data of the specific terminal according to the location or transmission power of the terminals. If the base station successfully receives the uplink data, the base station transmits the contention resolution message using the random access identifier included in the uplink data. The UE receiving the random access identifier of its own can know that the contention resolution is successful. In a contention-based random access procedure, it is called contention resolution in order for the UE to know whether a contention has failed or succeeded.

Upon receiving the contention resolution message, the UE determines whether the contention resolution message is its own. As a result of confirmation, the terminal sends an ACK to the base station if it is correct, and does not send response data if it is the terminal of another terminal. Of course, no response data is sent even if the downlink assignment is missed or the message can not be decoded. Also, the contention resolution message may include a C-RNTI or terminal identifier information.

11 is an explanatory diagram illustrating a method of configuring a time alignment group and a method of determining time alignment values in a multi-carrier system according to the present invention.

Referring to FIG. 11, a reference time refers to a time that is a reference of synchronization of the downlink or uplink. Herein, it is assumed that the reference time is set to a time point at which the downlink frame is received by the UE and confirmed after synchronization. The serving cell 1 (SCell 1), the serving cell 2 (SCell 2), the serving cell 3 (SCell 3), the serving cell 4 (SCell 4), and the serving cell 5 (SCell 5) are configured in the terminal.

Based on the classification support information, the base station configures the serving cell 1, the serving cell 3, and the serving cell 4 as one time alignment group 1 (TAG1), and the serving cell 2 and the serving cell 5 as another time alignment group 2 TAG2). Since the current uplink time of serving cells of TAG1 is behind the reference time by TA1 time, the base station sets a first time alignment value (N _TA1 ) so that the uplink time of serving cells of TAG1 precedes the current time by TA1 time , It is displayed in the first time advancing command field and transmitted to the terminal.

Then, the uplink time of the serving cell in the TAG2 is because behind by TA2 time than the current base station sets up a second time alignment value (N _TA2) to advance by TA2 time an uplink time of the serving cell in the TAG2 the current, and this And displays it in the second time advance command field and transmits it to the terminal. The MAC control element including the first and second time advance command fields may have the structure as shown in FIG.

The UE calculates the times TA1 and TA2 to be adjusted using N _TA1 and N _TA2 provided by the base station and adjusts the uplink time. The adjusted time TA can be obtained by the following equation (1).

Here, N _TA is a time alignment value, which is variably controlled by a time advance command of the base station, and N _{TA offset} is a value fixed by the frame structure. T _s is the sampling period. Here, if the time alignment value N _TA is positive, the uplink time is instructed to be advanced, and if negative, the uplink time is delayed.

On the other hand, the time alignment value (N _TA) are is adjusted from N _TA value (N _TA-old) are set to the new N _TA value (N _TA-new) by an index value, the new N _TA value is obtained as equation (2) .

Referring to Equation (2), T _i is an index value of 0, 1, 2, ..., 63.

Alternatively, the time alignment value N _TA may be determined as a difference relative to the time alignment value of the TAG included in the main serving cell as shown in Equation (3).

Referring to Equation _{3, N TA-TAG (Sn} ) but does not contain a primary serving cell (PCell) and the time alignment value for time alignment group with an index value of n is, N _{TA-TAG (p)} is a primary serving Is a time alignment value for a time alignment group including a cell (PCell). T _in is the T _i value for the time alignment group with index value n.

In the case where the UE initially receives the time alignment value for the serving cell, since there is no target value to be compared, the time alignment value (N _TA ) can be determined as shown in Equation (4).

As another example, if the propagation delay time of the downlink transmission is equal to the propagation delay time of the uplink transmission, the UE may adjust the uplink time for all serving cells using the propagation delay time of the downlink transmission.

12 is a flowchart illustrating a random access performing method according to another example of the present invention.

Referring to FIG. 12, if a terminal in an RRC (Radio Resource Control) idle mode can not aggregate an element carrier and only a terminal in an RRC connected mode can perform element carrier aggregation The UE selects a cell for RRC connection prior to the element carrier aggregation and performs an RRC connection establishment procedure for the base station through the selected cell (S1200). The RRC connection establishment procedure is performed by the UE transmitting an RRC connection request message to the BS, transmitting the RRC connection setup to the BS, and transmitting the RRC connection setup completion message to the BS. The RRC connection establishment procedure includes the setting of SRB1.

On the other hand, the cell for RRC connection is selected based on the following selection condition.

(i) the UE can select a suitable cell to attempt to establish a radio resource control connection based on the measured information. The UE measures RSRP (RSRP), which measures the received power based on a cell-specific reference symbol (CRS) of a specific cell received, and RSRQ (denominator) . Accordingly, the UE acquires RSRP and RSRQ values for each of the distinguishable cells, and selects an appropriate cell based on the acquired RSRP and RSRQ values. For example, if both the RSRP and RSRQ values have a value of 0 dB or more and the RSRP value is the maximum or the RSRQ value is the maximum, or if the RSRP and RSRQ values are set to a weight (e.g., 7: 3) So that an appropriate cell can be selected based on the average value.

(ii) information on a service provider (PLMN) fixedly set in the system stored in the terminal internal memory or radio resource (radio resource) information using downlink center frequency information or cell identification information (for example, PCI (Physical cell ID) Control connection can be attempted. The stored information may be composed of information on a plurality of service providers and cells, and priority or priority weight may be set for each information.

(iii) The UE can receive the system information transmitted through the broadcasting channel at the base station, check the information in the received system information, and try to establish the radio resource control connection. For example, the UE should check whether it is a specific cell (for example, a closed subscribe group (CSG), a non-allowed home base station, etc.) that requires membership for cell access. Accordingly, the UE receives the system information transmitted from each base station and confirms the CSG ID information indicating whether or not the CSG is present. If it is confirmed that the CSG is a CSG, it is checked whether or not the CSG is connectable. In order to confirm the accessibility, the UE can use its own membership information and unique information of the CSG cell (for example, CGI (envolved cell grove ID) or PCI information in the system information). If it is confirmed to be a non-connectable base station through the above-mentioned confirmation procedure, the wireless resource control connection is not attempted.

(iv) attempt to establish a radio resource control connection via valid element carriers (e.g., element carriers configurable within a frequency band that the terminal can support on implementation) stored in the terminal internal memory .

The conditions (ii) and (iv) of the four selection conditions are optional, but (i) and (iii) conditions must be applied mandatory.

In order to attempt a radio resource control connection through a cell selected for the RRC connection, the UE must check the uplink band to transmit the RRC connection request message. Accordingly, the UE receives the system information through a broadcasting channel transmitted through the downlink of the selected cell. SIB2 (system information block 2) includes bandwidth information and center frequency information for a band to be used as an uplink. Therefore, the UE attempts RRC connection through the uplink band established through the information in the SIB2 and the downlink and downlink of the selected cell. In this case, the UE can transmit an RRC connection request message to the BS as uplink data in the random access procedure. If the RRC connection procedure is successful, the cell in which the RRC connection is established may be called a main serving cell, and the main serving cell is composed of DL PCC and UL PCC.

The RRC connection reconfiguration (RRC) for additionally configuring one or more secondary serving cells (SCell) to the UE when the base station is to be allocated to a terminal of more radio resources by a request of the UE, (S1205). The RRC connection reconfiguration procedure is performed by the base station transmitting an RRC connection reconfiguration message to the terminal and transmitting the RRC connection reconfiguration completion message to the base station.

Steps S500, S505, S510, and S515 are equally applied to the following steps S1210, S1215, S1220, and S1225. On the other hand, the classification support information may be included in the RRC connection reconfiguration complete message in step S1205, in which case step S1210 may be omitted. In addition, step S1225 of performing the random access procedure may be performed based on a non-contention basis or a contention basis. The procedure of random access procedure is different according to whether it is non-contention-based or contention-based. In the case of non-contention based, the procedure of FIG. 6 is followed.

13 is a flowchart illustrating a random access performing method according to another example of the present invention.

Referring to FIG. 13, a terminal and a base station perform an RRC connection establishment procedure for a base station through a selected cell (S1300). The terminal transmits the classification support information to the base station (S1305). The classification support information provides information or criteria necessary to classify at least one serving cell configured in the terminal into a time alignment group. Meanwhile, the base station may know the classification support information or may already have the classification support information. In this case, the random access according to this embodiment may be performed with step S1305 omitted.

The base station classifies the serving cells into a time alignment group (S1310). The serving cells may be classified or organized into time aligned groups according to the classification support information.

When a base station is required to allocate to a terminal of more radio resources by a request of a terminal, a request of a network, or a self-determination of a base station, the base station performs an RRC connection reconfiguration procedure to further configure one or more auxiliary serving cells to the terminal (S1315 ). Within the RRC connection reconfiguration procedure, the base station may send time alignment group configuration information to the terminal in the RRC connection reconfiguration message. The time alignment group configuration information describes a state in which a time alignment group is configured. As an example, the time alignment group setting information may include an index field of a time alignment group, an index field of each time alignment group, and an index field of a serving cell included in each time alignment group, Describe the configured state.

The UE then performs a random access procedure (S1320), which may be performed on a non-contention-based or contention-based basis. The procedure of random access procedure is different according to whether it is non-contention-based or contention-based. In the case of non-contention based, the procedure of FIG. 6 is followed.

The UE checks the time advance command and / or the time alignment group index in the random access response message and adjusts the uplink time of all the serving cells in the identified time alignment group by the time alignment value according to the time advance command. An example of the uplink time adjusted by the time alignment value is shown in Equations (1) to (4). If there is a time advance instruction and / or a time alignment group index for a plurality of time alignment groups in the random access response message, the UE transmits the uplink time for the serving cell (s) As shown in FIG.

14 is a flowchart illustrating a random access performing method according to another example of the present invention.

Referring to FIG. 14, the UE and the BS perform an RRC connection establishment procedure for the BS through the selected cell (S1400). The selected cell becomes the main serving cell. When the base station is required to allocate to a terminal of more radio resources by a request of a terminal, a request of a network, or a self-determination of a base station, the base station performs an RRC connection reconfiguration procedure to further configure one or more auxiliary serving cells to the terminal (S1405 ).

The UE configures one or more secondary serving cells and performs a random access procedure (S1410). The UE transmits a random access preamble to the base station in order to secure time synchronization for the secondary serving cell in which synchronization is not secured or the newly added / changed secondary serving cell. At this time, the random access procedure can be performed only after the representative serving cell is activated. The random access procedure for the secondary serving cell may be initiated by a PDCCH indication (order) transmitted by the base station. The random access procedure may proceed on a non-contention basis or a contention based on the intent of the base station.

The base station classifies the serving cells configured in the UE based on the random access preamble received in step S1410 to configure a time alignment group (S1415). The time alignment group is a group containing at least one serving cell, and the same time alignment value is applied to the serving cells in the time alignment group. As an example, the base station may configure a time alignment group specifically for the terminal. As another example, a base station may configure a time alignment group specifically for a cell.

The base station transmits time alignment group configuration information to the terminal (S1420). The time alignment group configuration information describes a state in which a time alignment group is configured. As an example, the time alignment group setting information may include an index field of a time alignment group, an index field of each time alignment group, and an index field of a serving cell included in each time alignment group, Describe the configured state.

As another example, the time alignment group configuration information may further include representative serving cell information within each time alignment group. The representative serving cell is a serving cell capable of performing a random access procedure for uplink synchronization maintenance and setting in each time alignment group. If the time alignment group configuration information does not include a representative serving cell, the UE can select a representative serving cell in each time alignment group, unlike the above embodiment.

15 is an operation flowchart of a terminal performing random access according to an exemplary embodiment of the present invention.

Referring to FIG. 15, the terminal transmits classification support information to a base station (S1500). The classification support information provides information or criteria necessary to classify at least one serving cell configured in the terminal into a time alignment group. Meanwhile, the base station may know the classification support information or may already have the classification support information. In this case, the random access according to this embodiment may be performed with step S1500 omitted.

If the terminal in the idle mode can not aggregate the element carrier and only the terminal in the RRC connection mode can perform element carrier aggregation, the terminal in the idle mode selects a cell for RRC connection prior to the element carrier aggregation before step S1500, The RRC connection establishment procedure can be performed for the base station through the selected cell.

The UE receives the time alignment group configuration information from the base station (S1505). The time alignment group is a group containing at least one serving cell, and the same time alignment value is applied to the serving cells in the time alignment group. As an example, the base station may configure a time alignment group specifically for the terminal. As another example, a base station may configure a time alignment group specifically for a cell.

The time alignment group configuration information describes a state in which a time alignment group is configured. As an example, the time alignment group setting information may include an index field of a time alignment group, an index field of each time alignment group, and an index field of a serving cell included in each time alignment group, Describe the configured state.

As another example, the time alignment group configuration information may further include representative serving cell information within each time alignment group. The representative serving cell is a serving cell capable of performing a random access procedure for uplink synchronization maintenance and setting in each time alignment group. If the time alignment group configuration information does not include a representative serving cell, the UE can select a representative serving cell in each time alignment group, unlike the above embodiment.

In step S1510, the UE transmits a random access preamble on the representative serving cell to the base station and receives a MAC control element for the time advance command from the base station. This may be performed on a non-contention-based or contention-based basis. The procedure of random access procedure is different according to whether it is non-contention-based or contention-based. In the case of non-contention based, the procedure of FIG. 6 is followed.

The UE checks the time advance command and / or the time alignment group index in the random access response message and adjusts the uplink time of all the serving cells in the identified time alignment group by the time alignment value according to the time advance command. An example of the uplink time adjusted by the time alignment value is shown in Equations (1) to (4). If there is a time advance instruction and / or a time alignment group index for a plurality of time alignment groups in the random access response message, the UE transmits the uplink time for the serving cell (s) As shown in FIG.

16 is an operation flowchart of a base station performing random access according to an example of the present invention.

Referring to FIG. 16, the base station receives classification support information from the terminal (S1600). The classification support information provides information or criteria necessary to classify at least one serving cell configured in the terminal into a time alignment group. Meanwhile, the base station may know the classification support information or may already have the classification support information. In this case, the random access according to this embodiment may be performed with step S1600 omitted.

 The base station constructs a time alignment group based on the classification support information (S1605), and transmits the time alignment group configuration information to the terminal (S1610). The time alignment group is a group containing at least one serving cell, and the same time alignment value is applied to the serving cells in the time alignment group. As an example, the base station may configure a time alignment group specifically for the terminal. As another example, a base station may configure a time alignment group specifically for a cell. The time alignment group configuration information describes a state in which a time alignment group is configured.

Thereafter, the BS performs a random access procedure with the MS. At this stage, the BS receives the random access preamble from the MS on the representative serving cell and transmits a MAC control element for the time advance command to the MS. This may be performed on a non-contention-based or contention-based basis. The procedure of random access procedure is different according to whether it is non-contention-based or contention-based. In the case of non-contention based, the procedure of FIG. 6 is followed.

17 is a block diagram illustrating a base station and a terminal for performing random access according to an exemplary embodiment of the present invention.

17, the terminal 1700 includes a terminal receiving unit 1705, a terminal processor 1710, and a terminal transmitting unit 1720. The terminal processor 1710 also includes an RRC processor 1711 and a random access processor 1712.

The UE receiver 1705 receives preamble allocation information, time alignment group configuration information, a random access response message, an RRC connection setup message, an RRC connection reconfiguration message, or a contention resolution message from the base station 1750. The time alignment group configuration information describes a state in which a time alignment group is configured.

The RRC processor 1711 generates classification support information, an RRC connection message, and an RRC connection reconfiguration completion message. The classification support information may be included in the RRC connection reconfiguration completion message. The RRC processor 1711 checks at least one of the number of time alignment groups configured in the terminal 1700, the index of each time alignment group, the index of the serving cell in each time alignment group, and the representative serving cell information from the time alignment group configuration information . The representative serving cell is a serving cell selected to transmit a random access preamble in a time alignment group configured in the UE. Representative serving cells may be selected per time alignment group.

The meaning of selecting to transmit the random access preamble may mean that it has received configuration information for transmitting a preamble from among all the serving cells in the time alignment group, It may mean that a random access procedure is instructed through the PDCCH indication among the serving cells of the serving cell. The representative serving cell is also a serving cell that includes a reference timing reference DL CC for applying a TA value received through a random access response.

The random access processing unit 1712 handles a non-contention based or contention based random access procedure. The random access processing unit 1712 generates a random access preamble in order to secure uplink time synchronization for the serving cell. The generated random access preamble may be a dedicated random access preamble assigned by the base station 1750. When a plurality of time alignment groups are configured in the UE 1700, the random access processing unit 1712 may generate random access preambles to be transmitted on the representative serving cell of each time alignment group.

On the other hand, the random access processing unit 1712 checks the time advance command and / or the time alignment group index in the random access response message and updates the uplink time of all the serving cells in the confirmed time alignment group by time alignment Value. An example of the uplink time adjusted by the time alignment value is shown in Equations (1) to (4). If there is a time advance instruction and / or a time alignment group index for a plurality of time alignment groups in the random access response message, then the random access processing unit 1712 calculates an uplink time for each time alignment group Is adjusted by the time alignment value according to the forward advancing command.

The terminal transmitter 1720 transmits the classification support information, the RRC connection message, the RRC connection reconfiguration completion message, or the random access preamble to the base station 1750. For example, assume that the time alignment groups configured in the UE are TAG1 and TAG2, and TAG1 = {first serving cell, second serving cell, third serving cell}, TAG2 = {fourth serving cell, fifth serving cell} . If the representative serving cell of TAG1 is the second serving cell and the representative serving cell of TAG2 is the fifth serving cell, the terminal transmitting unit 1720 transmits the first random access preamble on the second serving cell and the second random access preamble To the fifth serving cell.

The base station 1750 includes a base station transmitter 1755, a base station receiver 1760, and a base station processor 1770. The base station processor 1770 also includes an RRC processor 1771 and a random access processor 1772.

The base station transmitter 1755 transmits preamble allocation information, time alignment group configuration information, a random access response message, an RRC connection completion message, an RRC connection reconfiguration message or a contention resolution message to the UE 1700. The random access response message is transmitted on the PDSCH indicated by the PDCCH scrambled with the C-RNTI. The C-RNTI is an identifier allocated to the UE 1700 by the Node B 1750 in order to check the RRC connection established between the UE 1700 and the Node B 1750 and the scheduling information transmitted by the Node B 1750. The base station 1750 must allocate different C-RNTI values for each user in the base station 1750. [ Each C-RNTI is allocated a temporary C-RNTI through a random access response in a contention-based random access procedure performed by the terminal 1700 for RRC connection, and when the corresponding random access procedure is finally succeeded, And recognizes the C-RNTI as a C-RNTI. The PDCCH indicating the random access response message may be transmitted through the scheduling cell for the representative serving cell or for the representative serving cell. In addition, when a random access response message is transmitted to a MAC control element for a time advance command, that is, to a MAC control element composed of contents including only a TA value (6 bits or 11 bits) and TAG ID information, The PDCCH indicating the response message and the random access response message can be received through the serving cell other than the serving serving cell including the UL CC to which the random access preamble is transmitted. That is, the random access response transmission can be transmitted without being restricted to the scheduling for a specific serving cell.

The base station receiver 1760 receives the classification support information, the random access preamble, the RRC connection setup related message, or the RRC connection reconfiguration related message from the UE 1700.

The RRC processor 1771 generates an RRC connection completion message or an RRC connection reconfiguration message. In addition, the RRC processor 1771 configures a time alignment group and generates time alignment group configuration information. The time alignment group is a group including at least one serving cell that is configured in the UE 1700, and the same time alignment value is applied to the serving cells in the time alignment group. As an example, the RRC processor 1771 may configure a time alignment group specifically for the terminal 1770. As another example, the RRC processor 1771 may configure a time alignment group specifically for a cell.

The random access processing unit 1772 selects one of the dedicated random access preambles reserved for the non-contention-based random access procedure among all available random access preambles, and calculates the index of the selected random access preamble and the usable time / frequency And generates preamble allocation information including resource information.

In addition, the random access processing section 1772 generates a random access response message or a contention resolution message. The random access processing unit 1772 identifies the representative serving cell to which the random access preamble is transmitted, and identifies the time alignment group including the representative serving cell. In addition, the random access processing portion 1772 determines a time alignment value to be applied to the identified time alignment group, and generates a random access response message including a TAC indicating the determined time alignment value.

Time advance command may be an integer multiple, for example, 16T _s current indicates a relative change in the uplink time of the uplink time and the sampling time (T _s). The time advance command can be expressed as a time alignment value of a specific index.

Or the random access processing unit 1772 may generate a random access response message including a time advance command and an index of the identified time alignment group. The data structure for the time advance command is described in Figures 7 to 9B.

Hereinafter, the time alignment group setting information will be described in detail. As an example, the base station may transmit time alignment group configuration information to the terminal using an RRC message. For example, time alignment group setup information may be included in the RRC connection reconfiguration message used in the RRC connection reconfiguration procedure. Table 5 is an example of an RRC connection reconfiguration message including time alignment group setting information.

TAG-ConfigDedicated :: = SEQUENCE {
pTAG SCellListOfTAG,
sTAG SCellListOfTAG,
sTAG-referenceCell INTEGER (1..7)
}

SCellListOfTAG :: = SEQUENCE (SIZE (1..7)) OF Serv-index

Referring to Table 5, the RRC connection reconfiguration message includes time alignment group configuration information (TAG-ConfigDedicated). pTAG denotes a time alignment group including main serving cells, and sTAG denotes a time alignment group that does not include main serving cells. The representative serving cell index (referenceCell) in the sTAG has a value of 1 to 7, which corresponds to the serving cell index. The serving cell list information (SCellListOfTAG) of the time alignment group has a value of 1 to 7, which corresponds to the serving cell index.

Table 6 is another example of an RRC connection reconfiguration message including time alignment group setting information.

TAG-ConfigDedicated :: = SEQUENCE {
pTAG BIT STRING (SIZE (7)),
sTAG BIT STRING (SIZE (7)),
sTAG-referenceCell INTEGER (1..7)
}

Referring to Table 6, the RRC connection reconfiguration message includes time alignment group configuration information (TAG-ConfigDedicated). Unlike Table 5, Table 6 shows the serving cells included in pTAG and sTAG as a bit string. The size of the bit string is 7 bits, and one serving cell corresponds to only one bit of the bit string. Of course, the size of the 7-bit bit string is an example, and may be less or larger.

As another example, the base station may transmit time alignment group configuration information to the terminal using a MAC message. The MAC message including the time alignment group setting information may have the MAC PDU structure of FIG. In particular, the time alignment group setting information may be included in the MAC control element, and the value of the LCID field indicating this MAC control element may be defined as shown in Table 7.

LCID Index LCID value 00000 CCCH 00001-01010 Identifier of the logical channel 01011-11001 Reserved 11010 About sorting time groups 11011 Enable / Disable 11100 The terminal contention resolution identifier 11101 TAC 11110 DRX command 11111 padding

Referring to Table 6, the LCID field having a value of 11010 indicates that the corresponding MAC control element is a MAC Control Element (hereinafter, MAC Control Element for TAG) including time alignment group setting information. The MAC subheader corresponding to the MAC control element for the TAG includes six fields such as R / R / E / LCID / F / L, and the MAC control element for the TAG may have a variable length. The L field indicates the length of the MAC control element for the TAG in units of bytes. The length of the L field is indicated by the F field. For example, if the F field is 1 bit, '1' indicates that the MAC control element for the TAG is smaller than 128 bytes, and the MAC subheader in this case is the same as the first embodiment in FIG. Also, if the F field is '0', it indicates that the length of the MAC control element for the TAG is 128 bytes or more, and the MAC subheader in this case is the same as the second embodiment in FIG.

19 is a diagram illustrating a MAC control element for a TAG according to an exemplary embodiment of the present invention.

Referring to FIG. 19, an octet 1 (Oct 1) of 8 bits unit corresponds to a pTAG, and represents a serving cell included in a pTAG in a bitmap format or a binary format. R, C ₇ , C ₆ , C ₅ , C ₄ , C ₃ , C ₂ , and C ₁ of octet 1 are sequentially assigned to the serving cell index 1, the serving cell index 2, ... Corresponds to the serving cell index 7, and R is a reserved field. That is, C _n corresponds to the serving cell index n. For example, if C _n = 1, it indicates that a serving cell with index n is included in a pTAG, and if C _n = 0, a serving cell with index n is not included in a pTAG. In pTAG, the main serving cell is always the representative serving cell.

Octet 2 (Oct 2) corresponds to the first sTAG and represents the serving cell contained in the sTAG in bitmap or binary form. R, C ₇ , C ₆ , C ₅ , C ₄ , C ₃ , C ₂ , and C ₁ of octet 2 are sequentially assigned from the right to the serving cell index 1, the serving cell index 2, Corresponds to the serving cell index 7, and R is a reserved field. The next octet 3 (Oct 3) indicates the representative serving cell in the sTAG indicated by octet 2, the immediately preceding octet. In other words, octet 3 includes a cell index field indicating a representative serving cell of the first sTAG. Since 7 serving cells can be represented by 3 bits, the cell index field is 3 bits, and the remaining 5 bits of octet 3 Is set to a preliminary field (R field).

Likewise, octet 2 (N-1) is an area corresponding to the N-th sTAG, and octet 2N-1 is an area indicating a representative serving cell in the N-th sTAG.

The R field in each octet is shown as being located in the leftmost bit, but this is only an example and the R field may be located in the rightmost bit.

20 is a diagram illustrating a MAC control element for a TAG according to another example of the present invention.

Referring to FIG. 20, each octet 1, 2, 3, ... , n + 1 are pTAG, sTAG1, sTAG2, ... , and sTAGn, and represents a serving cell included in a time alignment group in a bitmap format or a binary format. 19 in that there is no separate cell index field indicating a representative serving cell of each time aligned group. The representative serving cell of each TAG may be predefined between the UE and the BS, or may be notified to the UE by separate signaling. The R field in each octet is shown as being located in the leftmost bit, but this is only an example and the R field may be located in the rightmost bit.

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

Claims (20)

A base station configured to request uplink synchronization from a UE on a first sub-serving cell of one or more secondary serving cells in a wireless communication system,
[0050]
Lt; / RTI >
Wherein the transmission unit comprises:
(RRC) configuration for carrier aggregation of the first sub-serving cell among the primary serving cell and the one or more secondary serving cells to the UE,
(RRC) configuration for an extended physical downlink control channel (EPDCCH) for the first sub-serving cell,
Wherein the RRC configuration comprises:
Configure to receive the EPDCCH on any serving cell, and - whether to receive the EPDCCH is configured for each serving cell,
A physical downlink control channel (PDCCH) search space is mapped to a control region at the beginning of a subframe, and an EPDCCH search space is allocated to the subframe following the control region, Wherein the configured terminal search space for EPDCCH reception is indicated in the RRC configuration,
Wherein the transmission unit comprises:
The mobile station further configured to transmit downlink control information (DCI) mapped to the intended EPDCCH in the configured terminal search space for the EPDCCH during a subframe in the first subserving cell configured for EPDCCH reception And,
When the UE is configured to receive an EPDCCH on a specific serving cell, the BS does not transmit a PDCCH transmitted in a UE-specific manner to the UE on the PDCCH on the specific serving cell,
The received DCI mapped to the EPDCCH includes an initiation indicator of a non-contention random access procedure to obtain uplink timing on the secondary serving cell, Wherein the base station in the first sub-serving cell transmits the indicator only through the EPDCCH. The method according to claim 1,
Wherein the EPDCCH is comprised of RB pairs (resource block pairs). The method according to claim 1,
A receiver configured to receive a random access preamble on an uplink component carrier for the secondary serving cell in response to the initiation indicator;
And a base station. The method according to claim 1,
Wherein the transmitter is further configured to transmit a timing advance command (TAC) for the first sub-serving cell. The method according to claim 1,
The transmitting unit transmits a timing advance command (TAC) for a timing advance group to which the first sub-serving cell belongs, thereby causing the UE to transmit the uplink sub-serving cell for at least the first sub- And further configured to adjust timing. 6. The method of claim 5,
The UE is further configured to adjust the uplink timing for a second subserving cell in the TAG according to the TAC. The method according to claim 1,
Wherein the uplink timing on the first sub-serving cell is different from the main serving cell. A method for a base station requesting uplink synchronization from a terminal (UE) on a first sub-serving cell of one or more serving cells in a wireless communication system,
Wherein,
Transmitting a resource control (RRC) configuration for carrier aggregation of the first sub-serving cell among the primary serving cell and the one or more secondary serving cells to the terminal;
Transmitting a resource control (RRC) configuration for an extended physical downlink control channel (EPDCCH) for the first serving cell to the UE, the RRC configuration comprising:
Configure to receive the EPDCCH on any serving cell,
Together with a configured terminal search space for EPDCCH reception,
Wherein the EPDCCH search space is configured for each serving cell, the physical downlink control channel (PDCCH) search space is mapped to the control region at the beginning of the subframe, and the EPDCCH search space is located within the subframe following the control region Data area, wherein the configured terminal search space for EPDCCH reception is indicated in the RRC configuration; And
Transmitting downlink control information (DCI) mapped to an intended EPDCCH in the configured terminal search space for an EPDCCH during a subframe in a first subserving cell configured for EPDCCH reception by the terminal, When the UE is configured to receive an EPDCCH on a specific serving cell, the BS does not transmit a PDCCH to be transmitted on a specific serving cell to the UE on the PDCCH,
Lt; / RTI >
Wherein the received DCI mapped to the EPDCCH includes a start indicator of a non-contention random access procedure to obtain uplink timing on the secondary serving cell, and in the first secondary serving cell, the base station transmits the indicator only to the EPDCCH Through the method. 9. The method of claim 8,
Wherein the EPDCCH is configured as an RB pair (resource block pair). 9. The method of claim 8,
Receiving a random access preamble on an uplink component carrier for the secondary serving cell in response to the initiation indicator;
≪ / RTI > 9. The method of claim 8,
Transmitting a timing advance command (TAC) for the first sub-serving cell
≪ / RTI > 9. The method of claim 8,
And transmitting a timing advance command (TAC) for a timing advance group to which the first sub-serving cell belongs, thereby adjusting the uplink timing for at least the first sub- Step
≪ / RTI > 13. The method of claim 12,
And the UE is configured to adjust the uplink timing for a second sub-serving cell in the TAG according to the TAC. 9. The method of claim 8,
Wherein the uplink timing on the first sub-serving cell is different than the main serving cell. An apparatus configured to be integrated within a base station,
One or more processors
/ RTI >
The one or more processors,
A resource control (RRC) configuration for carrier aggregation of a first sub-serving cell of a primary serving cell and one or more secondary serving cells to a UE,
(RRC) configuration for an extended physical downlink control channel (EPDCCH) for the first sub-serving cell to the UE, the RRC configuration including:
Configure to receive the EPDCCH on any serving cell,
Together with a configured terminal search space for EPDCCH reception,
Wherein the EPDCCH search space is configured for each serving cell, wherein a physical downlink control channel (PDCCH) search space is mapped to a control region at the beginning of the subframe, Wherein the configured terminal search space for EPDCCH reception is indicated in the RRC configuration,
The UE is configured to transmit downlink control information (DCI) mapped to the intended EPDCCH in the configured terminal search space for the EPDCCH during a subframe in the first subserving cell configured for EPDCCH reception ,
When the UE is configured to receive an EPDCCH on a specific serving cell, the BS does not transmit, on the PDCCH, the PDCCH to be transmitted to the UE,
Wherein the received DCI mapped to the EPDCCH includes a start indicator of a non-contention random access procedure to obtain uplink timing on the secondary serving cell, and in the first secondary serving cell, the base station transmits the indicator only to the EPDCCH Through the device. 16. The method of claim 15,
Wherein the EPDCCH is comprised of RB pairs (resource block pairs). 16. The method of claim 15,
The one or more processors,
And receive a random access preamble on an uplink component carrier for the secondary serving cell in response to the initiation indicator. 16. The method of claim 15,
The one or more processors,
And transmit a timing advance command (TAC) for the first sub-serving cell. 16. The method of claim 15,
The one or more processors,
And to receive a timing advance command (TAC) for a timing advance group (TAG) to which the first secondary serving cell belongs,
According to the TAC,
And adjust the uplink timing for at least the first secondary serving cell in the TAG and adjust the uplink timing for the second secondary serving cell in the TAG. 16. The method of claim 15,
Wherein the uplink timing on the first sub-serving cell is different than the main serving cell.

Images