KR20150051303A - Methods for random access in wireless communication systems and Apparatuses Thereof - Google Patents

Abstract

The present invention relates to a method for random access in wireless communication systems. More specifically, a method for performing, by a base station, a random access process comprises the steps of: receiving a random access preamble; configuring a random access response relative to the random access preamble or configuring a random access response EPDCCH set on the basis of a random access response message format; and transmitting a random access response.

Description

Technical Field [0001] The present invention relates to a method and a device for random access in a wireless communication system,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a random access method in a wireless communication system, and more particularly, to a method and apparatus for transmitting a random access response in a random access procedure of a terminal requiring enhanced coverage compared to coverage for a general terminal.

Machine type communication (hereinafter referred to as "MTC" communication) is a type of data communication in which one or more entities represent a machine to machine communication that does not necessarily require human interaction . MTC communication that does not require human interaction refers to all communication methods in which communication is performed without human intervention in the communication process.

The MTC terminal can be installed in a place where the radio wave environment is worse than that of a general terminal. It may be necessary to repeatedly transmit control information and / or data of each physical channel transmitted only in one subframe in a plurality of subframes in order for the MTC terminal to operate in a place where the radio wave environment is worse than that of a general terminal.

Meanwhile, the terminal can perform a random access procedure with an initial access procedure with the base station. In the random access procedure, a random access response message is repeatedly transmitted for the MTC terminal, and the MTC terminal also receives and combines the repeated random access response. However, this procedure has a problem of causing an excessive load on the control area or the data area.

It is an object of the present invention to provide a method and apparatus for reducing an excessive load due to repetitive transmission even when transmitting a random access response for a coverage limited MTC terminal.

It is another object of the present invention to provide a method and apparatus for providing an appropriate amount of radio resources according to a size of a random access response even when transmitting a random access response through a fixed PDSCH resource.

An embodiment of the present invention is a method for a base station to perform a random access procedure, the method comprising: receiving a random access preamble; configuring a random access response associated with the random access preamble based on the random access response message format; Configuring the EPDCCH set, and transmitting a random access response.

According to another embodiment of the present invention, there is provided a method for a UE to perform a random access procedure, comprising: transmitting a random access preamble; monitoring one or more search spaces set for each random access response message format; Monitoring a random access response EPDCCH set based on the random access response preamble, and receiving a random access response associated with the random access preamble according to the monitoring result.

According to another embodiment of the present invention, there is provided a base station that performs a random access procedure, the base station configured to configure a random access response related to a random access preamble based on a random access response message format and a receiver that receives a random access preamble, And a transmitter for transmitting a random access response.

In another embodiment of the present invention, in a UE performing a random access procedure, at least one search space set for each of a transmitter for transmitting a random access preamble and a random access response message format is monitored or a random access response EPDCH set configuration information And a receiver for receiving a random access response related to a random access preamble according to the monitoring result.

According to the present invention described above, even when transmitting the random access response for the coverage limited MTC terminal, the effect of reducing excessive load due to repetitive transmission is provided.

The present invention also provides the effect of providing an appropriate amount of radio resources according to the size of the random access response even when transmitting the random access response through the fixed PDSCH resource.

1 is a signal diagram showing a conventional random access procedure.
FIG. 2 is a diagram exemplarily showing a repeated transmission / reception operation of a random access preamble and a random access response of a coverage extended MTC terminal of the present invention.
3 is a signal diagram illustrating operations of a terminal and a base station according to an embodiment of the present invention.
4 is a flowchart illustrating an operation of a base station according to another embodiment of the present invention.
5 is an exemplary diagram illustrating a random access response message format of the present invention.
6 is a flowchart illustrating an operation of a terminal according to another embodiment of the present invention.
7 is a signal diagram illustrating operations of a terminal and a base station according to another embodiment of the present invention.
8 is a flowchart illustrating an operation of a base station according to another embodiment of the present invention.
9 is a flowchart illustrating an operation of a base station according to another embodiment of the present invention.
10 is a diagram showing an example of information elements that can be included in the EPDCCH configuration information.
11 is a flowchart illustrating an operation of a terminal according to another embodiment of the present invention.
FIG. 12 is an exemplary diagram illustrating the number of EREGs per ECCE.
13 is a diagram exemplarily showing an EPDCCH format.
14 is a block diagram showing the configuration of a base station according to another embodiment of the present invention.
15 is a block diagram showing the configuration of a terminal according to another embodiment of the present invention.

Hereinafter, some embodiments of the present invention 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 numerals even though they are shown in different drawings. In the following description 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 invention rather unclear.

The wireless communication system in the present invention is widely deployed to provide various communication services such as voice, packet data and the like. A wireless communication system includes a user equipment (UE) and a base station (BS, or eNB). The user terminal in this specification is a comprehensive concept of a terminal in wireless communication. It is a comprehensive concept which means a mobile station (MS), a user terminal (UT), an SS (User Equipment) (Subscriber Station), a wireless device, and the like.

A base station or a cell generally refers to a station that communicates with a user terminal and includes a Node-B, an evolved Node-B (eNB), a sector, a Site, a BTS A base transceiver system, an access point, a relay node, a remote radio head (RRH), a radio unit (RU), and a small cell.

That is, in the present specification, a base station or a cell has a comprehensive meaning indicating a part or function covered by BSC (Base Station Controller) in CDMA, Node-B in WCDMA, eNB in LTE or sector (site) And covers various coverage areas such as megacell, macrocell, microcell, picocell, femtocell and relay node, RRH, RU, and small cell communication range.

Since the various cells listed above exist in the base station controlling each cell, the base station can be interpreted into two meanings. i) the device itself providing a megacell, macrocell, microcell, picocell, femtocell, small cell in relation to the wireless region, or ii) indicating the wireless region itself. i indicate to the base station all devices that are controlled by the same entity or that interact to configure the wireless region as a collaboration. An eNB, an RRH, an antenna, an RU, an LPN, a point, a transmission / reception point, a transmission point, a reception point, and the like are exemplary embodiments of a base station according to a configuration method of a radio area. ii) may indicate to the base station the wireless region itself that is to receive or transmit signals from the perspective of the user terminal or from a neighboring base station.

Therefore, a base station is collectively referred to as a base station, collectively referred to as a megacell, macrocell, microcell, picocell, femtocell, small cell, RRH, antenna, RU, low power node do.

Herein, the user terminal and the base station are used in a broad sense as the two transmitting and receiving subjects used to implement the technical or technical idea described in this specification, and are not limited by a specific term or word. The user terminal and the base station are used in a broad sense as two (uplink or downlink) transmitting and receiving subjects used to implement the technology or technical idea described in the present invention, and are not limited by a specific term or word. Here, an uplink (UL, or uplink) means a method of transmitting / receiving data to / from a base station by a user terminal, and a downlink (DL or downlink) .

There are no restrictions on multiple access schemes applied to wireless communication systems. Various multiple access schemes such as Code Division Multiple Access (CDMA), Time Division Multiple Access (TDMA), Frequency Division Multiple Access (FDMA), Orthogonal Frequency Division Multiple Access (OFDMA), OFDM-FDMA, OFDM- Can be used. An embodiment of the present invention can be applied to asynchronous wireless communication that evolves into LTE and LTE-Advanced via GSM, WCDMA, and HSPA, and synchronous wireless communication that evolves into CDMA, CDMA-2000, and UMB. The present invention should not be construed as limited to or limited to a specific wireless communication field and should be construed as including all technical fields to which the idea of the present invention can be applied.

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.

In systems such as LTE and LTE-Advanced, the uplink and downlink are configured on the basis of one carrier or carrier pair to form a standard. The uplink and the downlink are divided into a Physical Downlink Control Channel (PDCCH), a Physical Control Format Indicator CHannel (PCFICH), a Physical Hybrid ARQ Indicator CHannel, a Physical Uplink Control CHannel (PUCCH), an Enhanced Physical Downlink Control Channel (EPDCCH) Transmits control information through the same control channel, and is configured with data channels such as PDSCH (Physical Downlink Shared CHannel) and PUSCH (Physical Uplink Shared CHannel), and transmits data.

On the other hand, control information can also be transmitted using EPDCCH (enhanced PDCCH or extended PDCCH).

In this specification, a cell refers to a component carrier having a coverage of a signal transmitted from a transmission point or a transmission point or transmission / reception point of a signal transmitted from a transmission / reception point, and a transmission / reception point itself .

The wireless communication system to which the embodiments are applied may be a coordinated multi-point transmission / reception system (CoMP system) or a coordinated multi-point transmission / reception system in which two or more transmission / reception points cooperatively transmit signals. antenna transmission system, or a cooperative multi-cell communication system. A CoMP system may include at least two multipoint transmit and receive points and terminals.

The multi-point transmission / reception point includes a base station or a macro cell (hereinafter referred to as 'eNB'), and at least one mobile station having a high transmission power or a low transmission power in a macro cell area, Lt; / RTI >

Hereinafter, a downlink refers to a communication or communication path from a multiplex transmission / reception point to a terminal, and an uplink refers to a communication or communication path from a terminal to a multiplex transmission / reception point. In the downlink, a transmitter may be a part of a multipoint transmission / reception point, and a receiver may be a part of a terminal. In the uplink, the transmitter may be a part of the terminal, and the receiver may be a part of multiple transmission / reception points.

Hereinafter, a situation in which a signal is transmitted / received through a channel such as PUCCH, PUSCH, PDCCH, EPDCCH, and PDSCH is expressed as 'PUCCH, PUSCH, PDCCH, EPDCCH and PDSCH are transmitted and received'.

In the following description, an indication that a PDCCH is transmitted or received or a signal is transmitted or received via a PDCCH may be used to mean transmitting or receiving an EPDCCH or transmitting or receiving a signal through an EPDCCH.

That is, the physical downlink control channel described below may mean a PDCCH, an EPDCCH, or a PDCCH and an EPDCCH.

Also, for convenience of description, EPDCCH, which is an embodiment of the present invention, may be applied to the portion described with PDCCH, and EPDCCH may be applied to the portion described with EPDCCH according to an embodiment of the present invention.

Meanwhile, the High Layer Signaling described below includes RRC signaling for transmitting RRC information including RRC parameters.

The eNB performs downlink transmission to the UEs. The eNB includes a physical downlink shared channel (PDSCH) as a main physical channel for unicast transmission, downlink control information such as scheduling required for reception of a PDSCH, A physical downlink control channel (PDCCH) for transmitting scheduling grant information for transmission in a Physical Uplink Shared Channel (PUSCH). Hereinafter, the transmission / reception of a signal through each channel will be described in a form in which the corresponding channel is transmitted / received.

1 is a signal diagram showing a conventional random access procedure.

According to a random access procedure defined in a conventional LTE or LTE-Advanced system, a random access response (Random Access Response) for random access preamble transmission of any LTE or LTE- A dynamic scheduling method can be applied to RAR message transmission.

Referring to FIG. 1, in performing a random access procedure with the base station 109, the UE 101 may receive PRACH setting information from the base station 109 (S110). PRACH configuration information (PRACH configuration information) can be transmitted through a system information block (SIB). For example, via system information block 2.

The terminal 101 may transmit the random access preamble to the base station 109 (S120). The random access preamble may inform the base station 109 that there is a random access attempt and perform a function that allows the base station 109 to estimate the delay between the terminal 101 and the base station 109. [ The random access preamble may be transmitted via the PRACH.

The base station 109 receives the random access preamble and detects a random access attempt of the terminal 101. The base station 109 transmits a random access response in response to the random access attempt of the terminal 101 (S140). In this case, the random access response may be scheduled on a DL-SCH (Downlink Shared Channel) specified by the PDCCH. That is, the base station 109 transmits scheduling information for a random access response (S130), and may transmit a random access response (S140). The scheduling information for the random access response may be transmitted on the PDCCH.

Hereinafter, the term "random access response message transmission" and "random access response transmission" may be used interchangeably in the sense of transmitting random access response information transmitted by the base station.

Specifically, the random access procedure will be described again.

The random access response to the UE's random access preamble transmission is transmitted on the downlink data channel, i.e. PDSCH. For example, the scheduling information for the random access response is composed of DCI format 1A or DCI format 1C and is scrambled by CRC (Cyclic Redundancy Check) by RA-RNTI (Random Access RNTI) (Common Search Space). ≪ / RTI > That is, in order for the UE to receive the random access response, which is a response message to the random access preamble transmission, the decoding of the PDCCH including the scheduling information for the random access response in the CSS must be preceded by decoding. In addition, in any base station, it is possible to freely schedule the random access response within a certain time window after receiving the random access preamble.

LTE  For the terminal PDCCH search space Set formula

이 구성된다. 이때, 해당

을 구성하는 어그리게이션 레벨(aggregation level), L(where,

)을 갖는 임의의 PDCCH 후보자(candidate) m은 아래의 수학식 1에 의해 결정된다. In the case of a UE set to receive a DCI through a PDCCH in an existing 3GPP LTE / LTE-Advanced system, a set of PDCCH candidates defined to monitor for reception of downlink control information in an arbitrary DL sub- A search space for the corresponding terminal,

. At this time,

The aggregation level L (where,

) Is determined by the following equation (1). ≪ EMI ID = 1.0 >

의 값을 가지며, 크로스 캐리어 스케줄링(cross-carrier scheduling이) 설정된 경우,

을 가진다. 크로스 캐리어 스케줄링이 설정되지 않은 경우,

의 값을 갖는다. (단,

는 해당 DCI에 포함된 CIF(Carrier Indicator Field)값을 의미한다) 또한,

의 값을 가지고,

은 어그리게이션 레벨(aggregation level), L에 대해 단말이 모니터링하도록 정의된 PDCCH 후보자(candidates)의 수를 나타내며,

는 해당 DL 서브프레임(subframe) k에서의 PDCCH 제어영역(control region)을 구성하는 CCE(Control Channel Element)의 개수를 나타낸다. here

, And when cross-carrier scheduling is set,

. If cross-carrier scheduling is not set,

Lt; / RTI > (only,

Means a Carrier Indicator Field (CIF) value included in the corresponding DCI). Also,

Lt; / RTI >

Represents the aggregation level, L, the number of PDCCH candidates defined for the terminal to monitor for L,

Represents the number of CCEs (Control Channel Elements) constituting the PDCCH control region in the corresponding DL subframe k.

값은 아래의 수학식 2에 의해 결정된다. Additionally, in Equation 1,

The value is determined by the following equation (2).

(

는 slot number)의 값을 가진다.
Here,

(

Is the slot number.

LTE  Low-cost based MTC

As the LTE network spreads, mobile operators want to minimize the number of Radio Access Terminals (RATs) to reduce network maintenance costs. However, conventional MTC products based on a GSM / GPRS network are increasing, and MTC using a low data rate can be provided at low cost. Therefore, there is a problem in that two RATs must be operated respectively, since LTE network is used for general data transmission and GSM / GPRS network is used for MTC. Therefore, Of the total revenue.

In order to solve this problem, it is necessary to replace a cheap MTC terminal using a GSM / EGPRS network with an MTC terminal using an LTE network, and various requirements for lowering the price of the LTE MTC terminal are required for the 3GPP RAN WG1 standard conference . In addition, in the standard meeting, a document describing various functions that can be provided to satisfy the requirements is being created.

The main items related to the physical layer specification change, which are currently being discussed in the 3GPP, include technologies such as narrow band support, single RF chain, Half duplex FDD and long DRX (Discontinued Reception) to support the low-cost LTE MTC terminal. However, the above methods, which are considered for lowering the price, can reduce the performance of the MTC terminal as compared with the conventional LTE terminal.

In addition, about 20% of MTC terminals supporting MTC services such as smart metering are installed in a 'Deep indoor' environment such as a basement, so that for successful MTC data transmission, Compared with the coverage of the first embodiment. In addition, considering the performance reduction due to the above-mentioned specification change, the coverage of the LTE MTC terminal should be improved by 20 dB or more.

In order to improve the coverage while lowering the price of the LTE MTC terminal, a power spectral density (PSD) boosting, a low coding rate, a time domain repetition, Various methods for one transmission are considered for each physical channel.

The requirements of low-cost MTC terminal based on LTE are as follows.

The data transmission rate should satisfy the data transmission rate provided by the minimum EGPRS-based MTC terminal, that is, downlink 118.4 kbps and uplink 59.2 kbps.

■ Frequency efficiency should be improved dramatically compared to GSM / EGPRS MTC terminal.

The service area provided should not be less than that provided by the GSM / EGPRS MTC terminal.

■ Power consumption should not be larger than GSM / EGPRS MTC terminal.

■ Legacy LTE terminals and LTE MTC terminals should be available at the same frequency.

■ Reuse existing LTE / SAE networks.

Optimization is performed not only in the FDD mode but also in the TDD mode.

Low-cost LTE MTC terminals should support limited mobility and low power consumption modules.

In the present invention, a low-priced MTC terminal that requires less coverage and improvement in radio channel transmission / reception performance than a general LTE / LTE-Advanced terminal will be referred to as a coverage limited MTC terminal or an MTC terminal.

Coverage Restriction In order to support extended coverage for the MTC terminal, the PDCCH or EPDCCH and PDSCH transmissions, which were performed on a downlink subframe basis, should be repetitively transmitted through a plurality of downlink subframes. In addition, the corresponding MTC terminal also needs to perform decoding by combining the PDCCH or EPDCCH and PDSCH received through the plurality of downlink subframes.

Accordingly, in addition to the random access response for any MTC terminal performing the random access procedure, the PDCCH including the scheduling information for the random access response is also repetitively transmitted through a plurality of downlink subframes. This can lead to excessive overhead for the PDCCH CSS. Therefore, in the case of a random access response message, semi-static scheduling (hereinafter, referred to as " semi-static scheduling ") is defined in which a random access response is transmitted through an arbitrary fixed PDSCH resource without applying a dynamic scheduling method over an existing PDCCH ). However, when semi-static scheduling is applied to the random access response, it may become difficult to allocate an appropriate amount of PRB (Physical Resource Block) according to the size of the random access response message.

In order to solve such problems, the present invention proposes a PDSCH resource allocation method and apparatus for transmitting a random access response message for an MTC terminal. Particularly, when a semi-static scheduling method is applied without transmitting scheduling information on a PDCCH as a resource allocation method for a random access response transmission, the number of PRBs to be allocated according to the size of a random access response message (dynamic).

That is, the present invention proposes a PDSCH resource allocation method and apparatus for transmitting a random access response for a MTC terminal. Specifically, a method of applying semi-static scheduling for fixing arbitrary fixed PDSCH resources for a random access response without transmitting PDSCH resource allocation information for transmitting a random access response message through a PDCCH is proposed do. A method and apparatus for varying the number of allocated PRBs or the amount of resources according to the message size of the random access response will be proposed. To this end, the present invention proposes a blind detection based random access response message reception method as a first embodiment and a random access response transmission / reception method using an EPDCCH as a second embodiment.

FIG. 2 is a diagram exemplarily showing a repeated transmission / reception operation of a random access preamble and a random access response of a coverage extended MTC terminal of the present invention.

2, in order to improve the performance of receiving a random access preamble of a coverage-limited MTC terminal in a base station, it is considered to newly define a random access preamble format for the MTC terminal or to transmit an existing random access preamble repeatedly .

For example, in the case of a coverage limited MTC terminal, a preamble generated based on a random access preamble format for an existing general LTE / LTE-Advanced terminal can be repeated M times.

In other words, in the case of the coverage limited MTC terminal, the length of the preamble format defined in M uplink subframes (the sum of the CP length and the sequence length of the preamble format, i.e., the value of T _CP + T _SEQ , , The length of T _SEQ ) is increased, a scheme of transmitting the generated preamble based on the new random access preamble format may be considered.

In addition, application of a semi-static scheduling method instead of an existing dynamic scheduling method may be considered for resource allocation of a RAR message for a coverage-limited MTC terminal in a base station.

In order to apply the semi-static scheduling to the random access response, a PRB (random access response) in which a corresponding random access response is transmitted in a DL subframe (s) (s) is required.

The terminal of the present invention described below means an MTC terminal or a coverage-restricted terminal.

A base station according to an embodiment of the present invention receives a random access preamble from a mobile station. The base station may configure a random access response associated with the random access preamble based on the random access response message format, or may configure a random access response EPDCCH set. Thereafter, the base station transmits a random access response to the terminal. In one example, the random access response transmitted by the base station may be transmitted through a search space determined according to the random access response message format, and a search space may be formed in the data region. As another example, the random access response transmitted by the base station may be transmitted through the random access response EPDCCH set, and the EPDCCH set may be formed in the data area.

More specifically, in the present invention, the following two embodiments will be described as a method for variably allocating a PRB according to the size of a random access response message without transmitting scheduling information via a PDCCH.

1st Example . blind Detection  Based random access response reception ( Blind  detection based RAR message reception for MTC UEs )

3 is a signal diagram illustrating operations of a terminal and a base station according to an embodiment of the present invention.

A base station according to an embodiment of the present invention is a method for performing a random access procedure, comprising: receiving a random access preamble; configuring a random access response related to a random access preamble based on a random access response message format; And sending an access response.

Referring to FIG. 3, a UE 301 for a random access attempt transmits a random access preamble to a Node B 309 (S310).

The base station 309 receives the random access preamble and may configure a random access response associated with the received random access preamble based on the random access format (S320).

Thereafter, the base station 309 may transmit a random access response configured according to the specific random access format (S330). For example, the random access response may be transmitted through a search space set for each random access response message format.

As described above, in the first embodiment of the present invention, the random access response can be transmitted to the data area without scheduling the random access response through the PDCCH. In this case, the terminal can receive the random access response by decoding the search space that can be set according to the random access format using the blind decoding method.

4 is a flowchart illustrating an operation of a base station according to another embodiment of the present invention.

Referring to FIG. 4, the BS receives the random access preamble transmitted from the UE (S410).

For example, as described above, the UE may transmit the random access preamble repeatedly a predetermined number of times, or may transmit the generated preamble based on the new random access preamble format. The base station may receive the generated preamble based on a repeated or new random access preamble format.

The base station may configure a random access response associated with the random access preamble based on the random access response message format (S420).

For example, the base station may configure the random access response according to the random access response message format set differently according to the message size of the random access response to be transmitted. The base station may configure a corresponding random access response message through a suitable random access response message format among a plurality of random access response message formats.

Meanwhile, the BS may scramble the RA-RNTI when constructing the CRC for the random access response message for the MTC terminal, or may construct a corresponding CRC by scrambling a part of the MSB or LSB of the RA-RNTI.

At this time, the RA-RNTI value of the random access response can be determined by at least one of the number of repetitions of the random access preamble and the random access response message format.

For example, the RA-RNTI may be defined by a higher layer in the same manner as the conventional RA-RNTI regardless of the random access response message format. I.e., based on the subframe number or slot number associated with the reception of the random access preamble.

As another example, the RA-RNTI may have different values depending on the number of repetitions of the random access preamble or the format of the random access response message.

In addition, turbo coding, which is a channel coding scheme for a conventional DL-SCH, can be applied as a channel coding scheme for a random access response message of the MTC terminal. Alternatively, the random access response message of the MTC terminal may be subjected to a tail biting convolutional coding method, which is a conventional DCI channel coding method.

The base station may transmit the random access response configured in the above-described manner through the data area (S430). That is, a random access response can be transmitted on the PDSCH and not on the PDCCH, but on a search space that can be set based on the random access response message format.

5 is an exemplary diagram illustrating a random access response message format of the present invention.

Referring to FIG. 5, in the first embodiment of the present invention, a plurality of random access response message formats may be defined for transmitting a random access response message for the MTC terminal.

For example, each random access response message format may include a different number of PRB allocation information, as shown in the table of FIG. Specifically, the random access response message format 0 can allocate N ₀ number of PRBs, and the MCS and the number of random access response candidates can be set correspondingly.

However, FIG. 5 exemplarily shows the format of the random access response message, but does not limit the number of specific random access response message formats and the number of PRBs per random access response message (number of PRBs) . Further, a fixed MCS may be used regardless of the format of each random access response message, or a different MCS may be defined for each random access response message format.

The base station may transmit and transmit a random access response message through a suitable random access response message format among the plurality of random access response message formats defined above when transmitting the random access response message for the MTC terminal.

Hereinafter, the operation of the terminal in performing the random access procedure according to the first embodiment will be described with reference to the drawings.

6 is a flowchart illustrating an operation of a terminal according to another embodiment of the present invention.

The method for performing a random access procedure according to another embodiment of the present invention includes the steps of transmitting a random access preamble and monitoring one or more search spaces set according to a random access response message format or configuring a random access response EPDCH set Monitoring a random access response EPDCCH set based on the information and receiving a random access response associated with the random access preamble according to the monitoring result.

Referring to FIG. 6, a UE may transmit a random access preamble to perform a random access procedure (S610). The terminal may repeatedly transmit a random access preamble or transmit a random access preamble over a plurality of subframes in order to satisfy the requirements of the MTC terminal described above.

The UE can monitor one or more search spaces set for each random access response message format (S620).

For example, the UEs that have transmitted the random access preamble can receive a random access response message in a search space composed of random access response message candidates (RAR message candidates) based on each random access response message format in the PDSCH region, And perform blind decoding on the access response message.

The UE can receive the random access response for the random access preamble transmitted through the above-described blind decoding (S630).

In order to receive the random access response for the random access preamble transmission, the UE transmits each random access response message (PDSCH) in the PDSCH region of one or a plurality of DL subframes (s) It is possible to receive a random access response by performing blind decoding on a search space defined for each format.

), 해당 랜덤 액세스 응답 메시지 포맷(RAR message format, v)를 구성하는 PRBs의 수(number of PRBs, N_v) 및 RA-RNTI 등의 함수로서 결정될 수 있다. 즉, 본 발명의 또 다른 실시예에 따른 랜덤 액세스 응답 메시지 포맷 별로 설정되는 서치 스페이스의 PRB 또는 VRB는, 하향링크 시스템 밴드폭을 구성하는 전체 PRB의 개수, 슬롯 넘버, 해당 랜덤 액세스 응답 메시지 포맷의 PRB의 개수 및 RA-RNTI의 함수에 의해서 결정될 수 있다.For example, a physical resource block (PRB) or a virtual resource block (VRB) index (or indices (VRB)) constituting a search space for each random access response message format (RAR message format, ( _PRBs , N _PRB ), the slot number (slot number), and the number of total PRBs constituting the downlink system bandwidth,

), The number of PRBs (number of PRBs, N _v ) constituting the Random Access Response message format (RAR message format, v), and RA-RNTI. That is, the PRB or the VRB of the search space set according to the random access response message format according to another embodiment of the present invention is determined by the number of all PRBs constituting the downlink system bandwidth, the slot number, The number of PRBs and the function of RA-RNTI.

대신 N_PRB를, L 대신 N_v를 적용하고, 또한 m’=m=0, … ,M(v)-1을 적용하여 정의할 수 있다. 단, 이때 해당 Y_k를 정의하는 수학식 2에서

에 적용할

값에 해당 RA-RNTI를 적용하도록 할 수 있다.
As an example of this, the existing PDCCH search space setting expression described above can be reused. In this case, the PRB or the VRB index (indices) of the PDSCH region constituting the search space for an arbitrary random access message response format (RAR message format, v)

Instead of applying N _PRB and L _v instead of L, and m '= m = 0, ... , And M (v) -1, respectively. In this case, in Equation 2 defining the corresponding Y _k

To apply to

Value to apply the corresponding RA-RNTI.

As described above, according to the first embodiment of the present invention, in performing the random access procedure according to the first embodiment of the present invention, the base station can transmit a random access response through a search space defined for each random access response message format . The UE can receive the random access response by monitoring the corresponding PRB or VRB according to the PRB or VRB index of the search space that can be set based on the random access response message format.

According to the present invention, waste of PDCCH resources due to repetitive transmission can be prevented. Further, the random access response is not scheduled by the PDCCH but is transmitted through the data area set according to the random access response message format, thereby reducing the consumption of radio resources due to repetitive transmission.

Second Embodiment: A method for transmitting / receiving a random access response via an EPDCCH.

The base station according to another embodiment of the present invention can transmit the random access response through the EPDCCH.

7 is a signal diagram illustrating operations of a terminal and a base station according to another embodiment of the present invention.

A method for a base station to perform a random access procedure according to another embodiment of the present invention includes receiving a random access preamble, configuring a random access response EPDCCH set, and transmitting a random access response have.

Referring to FIG. 7, the MS 701 may transmit a random access preamble to the BS 709 (S710). The UE 701 may transmit the random access preamble repeatedly or may transmit the random access preamble by adjusting the length of the random access preamble.

The base station 709 may configure a random access response EPDCCH set to transmit a random access response (S720). That is, the base station 709 may configure an arbitrary random access response EPDCCH set (RAR EPDCCH set) for transmitting a random access response message to the terminal 701. [

The base station 709 may transmit the random access response using the configured random access EPDCCH set (S730).

A specific operation of the base station will be described with reference to FIG.

8 is a flowchart illustrating an operation of a base station according to another embodiment of the present invention.

Referring to FIG. 8, a base station can receive a random access preamble from a terminal (S810). The base station may receive the random access preamble repeatedly transmitted by the mobile station or may receive the random access preamble transmitted through a plurality of subframes.

The base station may configure a random access response EPDCCH set associated with the received random access preamble (S820). In one example, the base station may configure any EPDCCH set with a random access response EPDCCH set. The configured random access response EPDCCH set is configured for random access response transmission. The base station may configure the random access response EPDCCH set based on the configuration information for configuring the random access response EPDCCH set.

The base station may transmit the random access response (S830). As an example, the random access response may be sent over a configured random access response EPDCCH set.

9 is a flowchart illustrating an operation of a base station according to another embodiment of the present invention.

Referring to FIG. 9, when the base station configures the random access response EPDCCH set, it may further include transmitting the random access response EPDCCH set configuration information (S930). For example, the base station may receive a random access preamble from the terminal (S910) and configure a random access response EPDCCH set for the received random access preamble (S920).

The base station may transmit the configuration information used to configure the random access response EPDCCH set to the terminal (S930).

For example, the configuration information can be transmitted to the UE through cell-specific upper layer signaling. Specifically, it can be transmitted via cell-specific RRC signaling.

Alternatively, the base station may implicitly configure a random access response EPDCCH set (RAR EPDCCH set).

When the cell-specific RRC signaling for the Random Access Response EPDCCH set configuration is applied, the corresponding cell-specific RRC signaling may include unnecessary setting information (e.g., one of the existing EPDCCH set RRC parameters for the LTE / LTE- , pucch-ResourceStartOffset-r11, etc.). Alternatively, some of the settings (e.g., transmissionType, dmrs-ScramblingSequenceInt, resourceBlockAssignment, etc.) may be fixed and only some of the information may be included.

The parameters included in the configuration information will be described in detail with reference to FIG.

The base station may transmit the random access response via the configured EPDCCH set (S940).

10 is a diagram showing an example of information elements that can be included in the EPDCCH configuration information.

The base station may transmit the configuration information used to configure the random access response EPDCCH set to the terminal. The base station may transmit the configuration information to the mobile station through cell-specific upper layer signaling. Specifically, it can be transmitted via cell-specific RRC signaling.

For example, the cell-specific RRC signaling includes only some information except for unnecessary setting information (for example, pucch-ResourceStartOffset-r11, etc.) among the existing EPDCCH set RRC parameters for LTE / LTE- can do. Alternatively, some of the settings (e.g., transmissionType, dmrs-ScramblingSequenceInt, resourceBlockAssignment, etc.) may be fixed and only some of the information may be included.

As shown in FIG. 10, the EPDCCH set-up RRC parameter may include an information element associated with the EPDCCH configuration.

In transmitting the random access response EPDCCH set configuration information to the UE, the base station transmits some information of the information of FIG. 10, or some information of FIG. 10, and transmits only the information excluding the fixed information .

The information element for the EPDCCH configuration of FIG. 10 includes information on a subframe and a resource block for EPDCCH monitoring that a base station configures for a serving cell.

Each information element in FIG. 10 includes the information in Table 1.

In another example, the base station may implicitly configure a random access response EPDCCH set. That is, the configuration information for configuring the corresponding random access response EPDCCH set may have a fixed value or may be determined as a function using a slot number and an RA-RNTI.

The operation of the terminal according to the second embodiment will be described with reference to FIG.

11 is a flowchart illustrating an operation of a terminal according to another embodiment of the present invention.

The UE may transmit a random access preamble to perform the random access procedure (S1110). As described above, the UE can repeatedly transmit a random access preamble or construct and transmit a random access preamble through a plurality of subframes.

The UE may monitor the corresponding random access response EPDCCH set to receive the random access response for the random access preamble transmission (S1120). The UE may receive configuration information for the random access response EPDCCH set through higher layer signaling from the base station to monitor the random access response EPDCCH set.

The UE can receive the random access response through the random access response EPDCCH set monitoring (S1130).

A specific method related to monitoring the EPDCCH set for the UE to receive a random access response will be described with reference to Figs. 12 and 13. Fig.

The UE can monitor a specific random access response EPDCCH set for receiving a random access response. A set of random access response EPDCCHs monitored by the UE can be confirmed based on the above-described configuration information or implicitly given information.

For example, the terminal may monitor and receive a random access response based on the random access response EPDCCH format and the number of random access response EPDCCH candidates according to each random access response EPDCCH format.

FIG. 12 is an exemplary diagram illustrating the number of EREGs per ECCE, and FIG. 13 is a diagram illustrating an exemplary EPDCCH format.

12 and 13, the number of random access response EPDCCH candidates (RAR EPDCCH candidates) to be monitored for each random access response EPDCCH format transmitted through the random access response EPDCCH set and the number of random access response EPDCCH candidates The EPDCCH format defined for the LTE / LTE-Advanced terminal and the number of EPDCCH candidates that the terminal should monitor for the corresponding EPDCCH format.

For example, FIG. 13 shows the number of ECCEs for one EPDCCH set per EPDCCH format. That is, when the EPDCCH format is 0, the number of ECCEs for one EPDCCH can be set to 2 regardless of localized or distributed transmission in the case of case A. Also, in Case B, the number of ECCEs for one EPDCCH can be set to one regardless of localized or distributed transmission.

12 is an exemplary diagram illustrating the number of EREGs per ECCE. Therefore, the number of EREGs per ECCE can be determined according to the type of the subframe and the cyclic prefix as shown in the table of FIG.

Thus, the UE can monitor the random access response EPDCCH set based on the number of candidates per EPDCCH format and EPDCCH format.

Although the case where the number of candidates is equal to the EPDCCH format and the format of the existing LET / LTE-Advanced terminal has been exemplified above, the random access response EPDCCH format for the terminal of the present invention and the number of candidates for each format may be separately set .

Therefore, the present invention does not limit the number of random access response EPDCCH formats (RAR EPDCCH format) and random access response EPDCCH candidates (RAR EPDCCH candidates).

Unlike the method of receiving the configuration information of the random access response EPDCCH set and performing monitoring as described above, the UE may set a random access response EPDCCH set to be monitored using an implicit method.

For example, the UE may implicitly acquire and monitor the configuration information of the random access response EPDCCH set to be monitored. That is, monitoring may be performed using preset or fixed random access response EPDCCH set configuration information, or monitoring may be performed based on a function using a slot number and a RA-RNTI that transmitted a random access preamble have.

As described above, in the random access procedure of the present invention, the UE and the base station can configure the random access response using the EPDCCH set and transmit / receive the random access response through the configured EPDCCH set.

Accordingly, it is possible to prevent radio resource waste in the control area due to repetitive transmission of the random access response of the base station, and efficient radio resources can be used.

In addition, the two random access response transmission / reception methods proposed by the present invention are not limited to the number of times of RAR repetition for the UE and the timing relation between RAR reception and random access preamble transmission Can be applied. That is, the present invention can be applied regardless of the definition of downlink subframe for random access response transmission.

The configuration of a base station and a terminal in which all of the above-described present invention can be performed will be exemplarily described below.

14 is a block diagram showing the configuration of a base station according to another embodiment of the present invention.

14, a base station 1400 that performs a random access procedure according to another embodiment of the present invention includes a random access preamble receiving unit 1430 that receives a random access preamble and a random access response preamble A controller 1410 configured to configure an associated random access response or to configure a random access response EPDCCH set, and a transmitter 1420 to transmit a random access response.

When the random access response is configured based on the random access response message format, which is the case of the first embodiment described above, the transmitter 1420 can transmit the random access response through the search space set for each random access response message format.

The controller 1400 sets the PRB or VRB of the search space set for each random access response message format to the total number of PRBs constituting the downlink system bandwidth, the slot number, the number of PRBs of the random access response message format, and the RA-RNTI As shown in FIG.

Also, when a random access response is configured based on the random access response message format, the RA-RNTI value of the random access response may be determined by at least one of the number of repetitions of the random access preamble and the random access response message format.

On the other hand, when configuring the random access response EPDCCH set according to the second embodiment, the transmitter 1420 can transmit the random access response through the random access response EPDCCH set.

In addition, when configuring the random access response EPDCCH set, the transmitter 1420 can further transmit the random access response EPDCCH set configuration information. The random access response EPDCCH set configuration information may be transmitted through cell-specific upper layer signaling. Or may be implicitly identified to the terminal.

In addition, the controller 1410 controls the overall operation of the BS according to the PDSCH resource allocation for transmitting the random access response for the MTC terminal, which is necessary for performing the above-described present invention.

The transmitting unit 1420 and the receiving unit 1430 are used to transmit and receive signals, messages, and data necessary for carrying out the present invention to and from the terminal.

15 is a block diagram showing the configuration of a terminal according to another embodiment of the present invention.

15, a terminal 1500 for performing a random access procedure according to another embodiment of the present invention includes a transmitter 1520 for transmitting a random access preamble and one or more search spaces A control unit 1510 for monitoring a random access response EPDCCH set based on the random access response EPDCH set configuration information and a receiving unit 1530 for receiving a random access response related to a random access preamble according to a monitoring result .

The PRB or VRB of the search space set for each random access response message format, which is the case of the first embodiment described above, is the number of PRBs constituting the downlink system bandwidth, the slot number, the number of PRBs in each random access response message format And a function of RA-RNTI. In addition, the RA-RNTI value of the random access response may be determined by at least one of the number of repetitions of the random access preamble and the random access response message format.

On the other hand, in the case of the second embodiment, the receiver 1530 can further receive the random access response EPDCCH set configuration information through cell-specific upper layer signaling.

In addition, the monitored random access response EPDCCH set may be set separately for each random access response EPDCCH format.

In addition, the controller 1510 controls the overall operation of the UE receiving the random access response transmitted according to the PDSCH resource allocation for the random access response transmission for the MTC terminal, which is necessary for performing the above-described present invention.

The transmitting unit 1520 and the receiving unit 1530 are used to transmit and receive signals, messages, and data necessary for carrying out the present invention to and from the base station.

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 (24)

A method for a base station to perform a random access procedure,
Receiving a random access preamble;
Configuring a random access response associated with the random access preamble or configuring a random access response EPDCCH set based on a random access response message format; And
And transmitting the random access response. The method according to claim 1,
Wherein when the random access response is configured based on the random access response message format, the random access response is transmitted through a search space set for each random access response message format. 3. The method of claim 2,
The PRB or the VRB of the search space, which is set for each random access response message format,
The number of PRBs constituting the downlink system bandwidth, the slot number, the number of PRBs of the random access response message format, and the RA-RNTI. The method according to claim 1,
Wherein the RA-RNTI value of the random access response is determined by at least one of the number of repetitions of the random access preamble and the random access response message format when the random access response is configured based on the random access response message format. . The method according to claim 1,
Wherein when configuring the random access response EPDCCH set, the random access response is transmitted on the random access response EPDCCH set. The method according to claim 1,
Further comprising transmitting the random access response EPDCCH set configuration information when configuring the random access response EPDCCH set. The method according to claim 6,
Wherein the random access response EPDCCH set configuration information comprises:
Cell-specific upper layer signaling. A method for a terminal to perform a random access procedure,
Transmitting a random access preamble;
Monitoring one or more search spaces set for each random access response message format or monitoring the random access response EPDCCH set based on random access response EPDCH set configuration information; And
And receiving a random access response associated with the random access preamble according to the monitoring result. 9. The method of claim 8,
The PRB or the VRB of the search space, which is set for each random access response message format,
The number of PRBs constituting the downlink system bandwidth, the slot number, the number of PRBs of the random access response message format, and the RA-RNTI. 9. The method of claim 8,
Wherein the RA-RNTI value of the random access response is determined by at least one of the number of repetitions of the random access preamble and the random access response message format. 9. The method of claim 8,
Wherein the random access response EPDCCH set configuration information comprises:
Lt; RTI ID = 0.0 > cell-specific < / RTI > higher layer signaling. 9. The method of claim 8,
Wherein the monitored random access response EPDCCH set comprises:
Wherein the random access response is set separately for each EPDCCH format. 1. A base station performing a random access procedure,
A receiver for receiving a random access preamble;
A controller for configuring a random access response associated with the random access preamble or configuring a random access response EPDCCH set based on a random access response message format; And
And a transmitter for transmitting the random access response. 14. The method of claim 13,
Wherein, when the random access response is configured based on the random access response message format, the transmitter transmits the random access response through a search space set for each random access response message format. 15. The method of claim 14,
The PRB or the VRB of the search space, which is set for each random access response message format,
The base station being determined by a function of the number of all PRBs constituting the downlink system bandwidth, the slot number, the number of PRBs of the random access response message format, and the RA-RNTI. 14. The method of claim 13,
Wherein the RA-RNTI value of the random access response is determined by at least one of the number of repetitions of the random access preamble and the random access response message format when the random access response is configured based on the random access response message format. . 14. The method of claim 13,
Wherein when the random access response EPDCCH set is configured, the transmitter transmits the random access response on the random access response EPDCCH set. 14. The method of claim 13,
Wherein the transmitter further transmits the random access response EPDCCH set configuration information when configuring the random access response EPDCCH set. 19. The method of claim 18,
Wherein the random access response EPDCCH set configuration information comprises:
Cell-specific upper layer signaling. In a terminal performing a random access procedure,
A transmitter for transmitting a random access preamble;
A controller for monitoring one or more search spaces set for each random access response message format or monitoring the random access response EPDCCH set based on random access response EPDCH set configuration information; And
And a receiver for receiving a random access response associated with the random access preamble according to the monitoring result. 21. The method of claim 20,
The PRB or the VRB of the search space, which is set for each random access response message format,
A terminal determined by a function of the number of all PRBs constituting the downlink system bandwidth, the slot number, the number of PRBs in each random access response message format, and the RA-RNTI. 21. The method of claim 20,
Wherein the RA-RNTI value of the random access response comprises:
The number of repetitions of the random access preamble and the random access response message format. 21. The method of claim 20,
The receiver may further comprise:
And further receiving the random access response EPDCCH set configuration information through cell-specific upper layer signaling. 21. The method of claim 20,
Wherein the monitored random access response EPDCCH set comprises:
A terminal that is distinguishably set for each random access response EPDCCH format.

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