WO2015056924A1

WO2015056924A1 - Method for transmitting and receiving random access preamble and device therefor

Info

Publication number: WO2015056924A1
Application number: PCT/KR2014/009472
Authority: WO
Inventors: 박규진; 최우진
Original assignee: 주식회사 케이티
Priority date: 2013-10-14
Filing date: 2014-10-08
Publication date: 2015-04-23

Abstract

The present invention provides a method and a device for setting a repetition level of a random access preamble and determining transmission power for each random access preamble, when a random access preamble for an MTC terminal is repetitively transmitted and received to increase the transmission and reception performance of a random access preamble for a coverage-restricted MTC terminal. In addition, the present invention provides a method and a device for controlling transmission power for a random access preamble when a terminal, located in improved coverage compared to the coverage for a general terminal, repetitively transmits the random access preamble. When the terminal repetitively transmits a PRACH through a plurality of uplink subframes, the terminal can determine the number of repetitive transmissions of the PRACH, determine transmission power for the PRACH on the basis of the number of repetitive transmissions of the PRACH, and transmit the PRACH at the transmission power determined for the PRACH.

Description

Random access preamble transmission and reception method and apparatus therefor

The present invention relates to a method and apparatus for transmitting and receiving a random preamble in a wireless communication system, and more particularly, when repeatedly transmitting and receiving a random access preamble to improve the coverage to a terminal located in the improved coverage compared to the coverage for a general terminal. The present invention relates to a method and apparatus for setting a repetition level of a random access preamble and controlling a transmission power.

The present invention also relates to a method and apparatus for controlling a random access preamble transmission power in a wireless communication system, and more particularly, a terminal located in enhanced coverage compared to coverage for a general terminal may repeatedly transmit a random access preamble. And a method and apparatus for controlling the transmit power of a random access preamble.

Machine type communication (hereinafter referred to as "MTC" communication) is a form of data communication, in which one or more entities represent machine or 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 may be installed in a place where the radio environment is worse than that of the general terminal. In order for an MTC terminal to operate in a place where a radio 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 in one subframe unit in a plurality of subframes.

Meanwhile, since the random access preamble for a general terminal is not repeatedly transmitted in a plurality of subframes, various studies such as a procedure for repeatedly transmitting and receiving a random access preamble for an MTC terminal are necessary.

In addition, since the general terminal does not repeatedly transmit a random access preamble in a plurality of subframes, the transmission power of the random access preamble may be determined without considering that the random access preamble is repeatedly transmitted.

The present invention is to set the repetition level of the random access preamble and to determine the transmission power of each random access preamble when repeatedly transmitting and receiving the random access preamble for the MTC terminal to improve the transmission and reception performance of the random access preamble of the coverage limited MTC terminal It is an object to provide a method and apparatus.

In addition, an object of the present invention is to provide a method for controlling the transmit power of the random access preamble when the MTC terminal repeatedly transmits the random access preamble in a plurality of subframes in order to overcome the above-described problem.

According to an embodiment of the present invention, a method for performing random access by a terminal, the method comprising: determining a preamble repetition level based on at least one variable or coverage level among variables that determine a random access preamble transmission power of the random access preamble; ; Transmitting the random access preamble repeatedly to a base station through a specific number of subframes corresponding to the determined preamble repetition level; And receiving a random access response related to the random access preamble from the base station, and if the random access response is not received from the base station, repeating transmitting the random access preamble to the base station. Provide a method. In addition, the preamble repetition level is a downlink path loss value (

It provides a method characterized in that it is determined by). In addition, the preamble repetition level is the maximum transmit power of the terminal (

), Downlink path loss value (

), which is determined by a function of preambleInitialReceivedTargetPower and DELTA_PREAMBLE. In addition, the coverage level provides a method characterized in that it is determined by the number of repetitions of the downlink physical channel or set by the terminal-specific higher layer signaling. Further, when the random access response is not received from the base station and the step of transmitting the random access preamble to the base station is repeated, the random access preamble is repeatedly transmitted to the base station by changing the preamble repetition level. It provides a way to. In addition, when the random access response is not received from the base station and the step of transmitting the random access preamble to the base station is repeated, the preamble repetition level is increased by 1 to repeatedly transmit the random access preamble to the base station. It provides a method characterized in that. Further, when the random access response is not received from the base station, and the step of transmitting the random access preamble to the base station is repeated, M _n random access corresponding to the preamble repetition level n (n is a natural number greater than 1). When the preamble is repeatedly transmitted to the base station, the transmission power is ramped, and when a predetermined condition is achieved, the random access preamble is repeatedly transmitted to the base station by increasing the preamble repetition level. In addition, the specific condition may increase the PREAMBLE_TRANSMISSION_COUNTER used to determine the transmit power of the random access preamble by 1 so that the PREAMBLE_TRANSMISSION_COUNTER reaches a threshold value, or the transmit power for each random access preamble transmission is increased.

The method is characterized in that the case is reached. The present invention also provides a method of increasing the preamble repetition level by 1 and repeatedly transmitting the random access preamble to the base station. Another embodiment of the present invention is a terminal for performing a random access, the random access preamble is a specific corresponding to the preamble repetition level determined according to at least one variable or coverage level of the variables for determining the transmission power of the random access preamble A transmitter for repeatedly transmitting to the base station through the number of subframes; And a receiving unit for receiving a random access response related to the random access preamble from the base station, and when the receiving unit does not receive the random access response from the base station, the transmitting unit transmits the random access preamble to the base station. It provides a terminal characterized in that it is repeated. In addition, the preamble repetition level is a downlink path loss value (

It provides a terminal characterized in that determined by). In addition, the preamble repetition level is the maximum transmit power of the terminal (

), Downlink path loss value (

), it provides a terminal, characterized in that determined by the function of preambleInitialReceivedTargetPower , DELTA_PREAMBLE. In addition, the coverage level provides a terminal, characterized in that determined by the number of repetitions of the downlink physical channel or set by the terminal-specific higher layer signaling. In the case where the random access response is not received from the base station and the process of transmitting the random access preamble to the base station is repeated, the random access preamble is repeatedly transmitted to the base station by changing the preamble repetition level. Provided is a terminal. In addition, when the random access response is not received from the base station and the process of transmitting the random access preamble to the base station is repeated, the preamble repetition level is increased by 1 to repeat the random access preamble to the base station. It provides a terminal characterized in that. Further, when the random access response is not received from the base station and the process of transmitting the random access preamble to the base station is repeated, M _n random access corresponding to the preamble repetition level n (n is a natural number greater than 1) Each time the preamble is repeatedly transmitted to the base station, the transmission power is ramped, and when a specific condition is achieved, the preamble repetition level is increased to repeatedly transmit the random access preamble to the base station. In addition, the specific condition may increase the PREAMBLE_TRANSMISSION_COUNTER used to determine the transmit power of the random access preamble by 1 so that the PREAMBLE_TRANSMISSION_COUNTER reaches a certain number, or the transmit power for each random access preamble transmission is increased.

It provides a terminal characterized in that the case of reaching. The present invention also provides a terminal that increases the preamble repetition level by 1 and repeatedly transmits the random access preamble to the base station.

Meanwhile, an embodiment of the present invention provides a method for a UE to transmit a random access preamble through a physical random access channel (PRACH). The PRACH is transmitted through a plurality of uplink subframes. When repeatedly transmitting, determining the number of times the PRACH is repeatedly transmitted and determining the transmission power of the PRACH based on the number of times the PRACH is repeatedly transmitted; And repeatedly transmitting the PRACH at the determined transmit power of the PRACH. In addition, the present invention is to increase the transmission power of the PRACH when the repeated transmission of the PRACH fails, and if the transmission power of the increased PRACH is less than the maximum transmission power, the PRACH with the increased transmission power of the PRACH Transmitting repeatedly and transmitting the PRACH repeatedly by increasing the number of times the PRACH is repeatedly transmitted if the transmission power of the increased PRACH is greater than the maximum transmission power. In addition, the present invention is to increase the number of times the PRACH is repeatedly transmitted when the transmission of the PRACH fails, and if the number of times the increased PRACH is repeatedly transmitted is less than the maximum value, the increased PRACH is repeated Repeatedly transmitting the PRACH with the number of transmissions; and if the number of times the increased PRACH is repeatedly transmitted is greater than the maximum value, increasing the transmission power of the PRACH and repeatedly transmitting the PRACH. To provide. In the determining of the transmit power of the PRACH, the transmit power of the PRACH is determined using Equation (1) below.

(1) P _PRACH = min {

, PREAMBLE_RECEIVED_TARGET_POWER +

10 logM _n } _ [dBm]

In Equation (1), P _PRACH is the transmit power of the PRACH,

Is the maximum transmit power, PREAMBLE_RECEIVED_TARGET_POWER is the target preamble receive power,

Is a downlink path loss, and M _n is a number of times the PRACH is repeatedly transmitted. In the determining of the transmit power of the PRACH, the transmit power of the PRACH is determined using Equation (2) below.

(2) P _PRACH = min {

, PREAMBLE_RECEIVED_TARGET_POWER +

} _ [dBm]

In Equation (2), P _PRACH is the transmit power of the PRACH,

Is the maximum transmit power,

Is a downlink path loss, PREAMBLE_RECEIVED_TARGET_POWER is determined using Equation (3) below,

(3) PREAMBLE_RECEIVED_TARGET_POWER = preambleInitialReceivedTargetPower + DELTA_PREAMBLE + DELTA_PREAMBLE_REPETITION + (PREAMBLE_TRANSMISSION_COUNTER-1) * powerRampingStep

In Equation (3), preambleInitialReceivedTargetPower and powerRampingStep are values received by higher layer signaling, DELTA_PREAMBLE is a value determined according to a format of a random access preamble, and DELTA_PREAMBLE_REPETITION is determined based on the number of times the PRACH is repeatedly transmitted. Value, and PREAMBLE_TRANSMISSION_COUNTER is a number of attempts to transmit the PRACH. In the determining of the transmit power of the PRACH, the transmit power of the PRACH is determined using Equation (4) below.

(4) P _PRACH = min {

, PREAMBLE_RECEIVED_TARGET_POWER +

} _ [dBm]

In Equation (4), P _PRACH is the transmit power of the PRACH,

Is the maximum transmit power,

Is a downlink path loss, PREAMBLE_RECEIVED_TARGET_POWER is determined using Equation (5) below,

(5) PREAMBLE_RECEIVED_TARGET_POWER = preambleInitialReceivedTargetPower + DELTA_PREAMBLE + (PREAMBLE_TRANSMISSION_COUNTER-1) * powerRampingStep

In Equation (5), preambleInitialReceivedTargetPower and powerRampingStep are values received by higher layer signaling, DELTA_PREAMBLE is a value determined according to a format of a random access preamble, PREAMBLE_TRANSMISSION_COUNTER is the number of times the PRACH is attempted to be transmitted, and the preambleInitialReceivedTargetTargetTar In the PRACH is determined based on the number of times iteratively transmitted. In addition, the step of determining the transmission power of the PRACH is to determine the transmission power of the PRACH using the following equation (6),

(6) P _PRACH = min {

, PREAMBLE_RECEIVED_TARGET_POWER +

} _ [dBm]

In Equation (6), P _PRACH is the transmit power of the PRACH,

Is the maximum transmit power,

Is a downlink path loss, PREAMBLE_RECEIVED_TARGET_POWER is determined using Equation (7) below,

(7) PREAMBLE_RECEIVED_TARGET_POWER = preambleInitialReceivedTargetPower + DELTA_PREAMBLE + (PREAMBLE_TRANSMISSION_COUNTER-1) * powerRampingStep

In Equation (5), preambleInitialReceivedTargetPower and powerRampingStep are values received by higher layer signaling, DELTA_PREAMBLE is a value determined according to a format of a random access preamble, PREAMBLE_TRANSMISSION_COUNTER is the number of times the PRACH is attempted to be transmitted, and the powerRampingStep is the value Provided is a method characterized in that it is adjusted based on the number of times the PRACH is repeatedly transmitted at the terminal or determined based on the number of times the PRACH is repeatedly transmitted at the base station.

Another embodiment of the present invention provides a method for a base station to transmit configuration information on transmission power of a physical random access channel (PRACH) to a terminal, based on the number of times the PRACH is repeatedly transmitted from the terminal. Determining configuration information about the transmit power of the PRACH; And transmitting configuration information on the transmit power of the PRACH to the terminal through higher layer signaling. In addition, the present invention is the transmission power of the PRACH in the terminal is determined using the following equation (8),

(8) P _PRACH = min {

, PREAMBLE_RECEIVED_TARGET_POWER +

} _ [dBm]

In Equation (8), P _PRACH is the transmit power of the PRACH,

Is the maximum transmit power,

Is a downlink path loss, PREAMBLE_RECEIVED_TARGET_POWER is determined using Equation (9) below,

(9) PREAMBLE_RECEIVED_TARGET_POWER = preambleInitialReceivedTargetPower + DELTA_PREAMBLE + (PREAMBLE_TRANSMISSION_COUNTER-1) * powerRampingStep

In Equation (9), preambleInitialReceivedTargetPower and powerRampingStep are values transmitted by higher layer signaling, DELTA_PREAMBLE is a value determined according to a format of a random access preamble, and PREAMBLE_TRANSMISSION_COUNTER is the number of times the UE attempts to transmit the PRACH. The configuration information on the transmit power of the PRACH, which is determined based on the number of times the PRACH is repeatedly transmitted, provides a method characterized in that the preambleInitialReceivedTargetPower . In addition, the transmission power of the PRACH in the terminal is determined using the following equation (10),

(10) P _PRACH = min {

, PREAMBLE_RECEIVED_TARGET_POWER +

} _ [dBm]

In Equation (10), P _PRACH is the transmit power of the PRACH,

Is the maximum transmit power,

Is a downlink path loss, PREAMBLE_RECEIVED_TARGET_POWER is determined using Equation (11) below,

(11) PREAMBLE_RECEIVED_TARGET_POWER = preambleInitialReceivedTargetPower + DELTA_PREAMBLE + (PREAMBLE_TRANSMISSION_COUNTER-1) * powerRampingStep

In Equation (11), preambleInitialReceivedTargetPower and powerRampingStep are values transmitted by higher layer signaling, DELTA_PREAMBLE is a value determined according to a format of a random access preamble, and PREAMBLE_TRANSMISSION_COUNTER is the number of times the UE attempts to transmit the PRACH. The configuration information on the transmit power of the PRACH, which is determined based on the number of times the PRACH is repeatedly transmitted, provides a method characterized in that the powerRampingStep .

Another embodiment of the present invention is a terminal for transmitting a random access preamble through a physical random access channel (PRACH), and when repeatedly transmitting the PRACH through a plurality of uplink subframes A control unit determining a number of times the PRACH is repeatedly transmitted and determining transmission power of the PRACH based on the number of times the PRACH is repeatedly transmitted; And a transmitter for repeatedly transmitting the PRACH at the determined transmission power of the PRACH. The control unit may increase the transmit power of the PRACH when repetitive transmission of the PRACH fails. Repeated transmission, if the increased transmission power of the PRACH is greater than the maximum transmission power, the terminal is characterized in that the PRACH is repeatedly transmitted by increasing the number of times the PRACH is repeatedly transmitted. The controller may increase the number of times the PRACH is repeatedly transmitted when the transmission of the PRACH fails, and if the number of times the increased PRACH is repeatedly transmitted is less than or equal to the maximum value, the increased PRACH is repeated. Repeatedly transmit the PRACH as the number of transmissions, and if the number of times the increased PRACH is repeatedly transmitted is greater than the maximum value, increasing the transmission power of the PRACH to repeatedly transmit the PRACH to provide a terminal do. In addition, the controller determines transmission power of the PRACH using Equation (12) below.

(12) P _PRACH = min {

, PREAMBLE_RECEIVED_TARGET_POWER +

10 logM _n } _ [dBm]

In Equation (12), P _PRACH is the transmit power of the PRACH,

Is a downlink path loss, and M _n is a number of times the PRACH is repeatedly transmitted. In addition, the controller determines transmission power of the PRACH using Equation (13) below.

(13) P _PRACH = min {

, PREAMBLE_RECEIVED_TARGET_POWER +

} _ [dBm]

In Equation (13), P _PRACH is the transmit power of the PRACH,

Is the maximum transmit power,

Is a downlink path loss, PREAMBLE_RECEIVED_TARGET_POWER is determined using Equation (14) below,

(14) PREAMBLE_RECEIVED_TARGET_POWER = preambleInitialReceivedTargetPower + DELTA_PREAMBLE + DELTA_PREAMBLE_REPETITION + (PREAMBLE_TRANSMISSION_COUNTER-1) * powerRampingStep

In Equation (14), preambleInitialReceivedTargetPower and powerRampingStep are values received by higher layer signaling, DELTA_PREAMBLE is a value determined according to a format of a random access preamble, and DELTA_PREAMBLE_REPETITION is determined based on the number of times the PRACH is repeatedly transmitted. Value, and PREAMBLE_TRANSMISSION_COUNTER provides a terminal characterized in that the number of attempts to transmit the PRACH. In addition, the controller determines transmission power of the PRACH using Equation (15) below.

(15) P _PRACH = min {

, PREAMBLE_RECEIVED_TARGET_POWER +

} _ [dBm]

In Equation (15), P _PRACH is the transmit power of the PRACH,

Is the maximum transmit power,

Is a downlink path loss, PREAMBLE_RECEIVED_TARGET_POWER is determined using Equation (16) below,

(16) PREAMBLE_RECEIVED_TARGET_POWER = preambleInitialReceivedTargetPower + DELTA_PREAMBLE + (PREAMBLE_TRANSMISSION_COUNTER-1) * powerRampingStep

In Equation (16), preambleInitialReceivedTargetPower and powerRampingStep are values received by higher layer signaling, DELTA_PREAMBLE is a value determined according to a format of a random access preamble, PREAMBLE_TRANSMISSION_COUNTER is the number of times the PRACH is attempted to be transmitted, and the preambleInitialReceivedTargetTargetTar In the UE provides a terminal characterized in that it is determined based on the number of times the PRACH is repeatedly transmitted. In addition, the controller determines transmission power of the PRACH using Equation (17) below.

(17) P _PRACH = min {

, PREAMBLE_RECEIVED_TARGET_POWER +

} _ [dBm]

In Equation (17), P _PRACH is the transmit power of the PRACH,

Is the maximum transmit power,

Is a downlink path loss, PREAMBLE_RECEIVED_TARGET_POWER is determined using Equation (18) below,

(18) PREAMBLE_RECEIVED_TARGET_POWER = preambleInitialReceivedTargetPower + DELTA_PREAMBLE + (PREAMBLE_TRANSMISSION_COUNTER-1) * powerRampingStep

In Equation (18), preambleInitialReceivedTargetPower and powerRampingStep are values received by higher layer signaling, DELTA_PREAMBLE is a value determined according to a format of a random access preamble, PREAMBLE_TRANSMISSION_COUNTER is the number of times the PRACH is attempted to be transmitted, and the powerRampingStep is the value A terminal is adjusted based on the number of times the PRACH is repeatedly transmitted from the terminal or is determined based on the number of times the PRACH is repeatedly transmitted from the base station.

Another embodiment of the present invention is a base station for transmitting configuration information on a transmission power of a physical random access channel (PRACH) to a terminal, the PRACH based on the number of times the PRACH is repeatedly transmitted from the terminal A control unit for determining setting information on a transmission power of the control unit; And a transmitter for transmitting configuration information on the transmit power of the PRACH to the terminal through higher layer signaling. In addition, the transmission power of the PRACH in the terminal is determined using the following equation (19),

(19) P _PRACH = min {

, PREAMBLE_RECEIVED_TARGET_POWER +

} _ [dBm]

In Equation (19), P _PRACH is the transmit power of the PRACH,

Is the maximum transmit power,

Is a downlink path loss, PREAMBLE_RECEIVED_TARGET_POWER is determined using Equation (20) below,

(20) PREAMBLE_RECEIVED_TARGET_POWER = preambleInitialReceivedTargetPower + DELTA_PREAMBLE + (PREAMBLE_TRANSMISSION_COUNTER-1) * powerRampingStep

In Equation (20), preambleInitialReceivedTargetPower and powerRampingStep are values transmitted by higher layer signaling, DELTA_PREAMBLE is a value determined according to a format of a random access preamble, and PREAMBLE_TRANSMISSION_COUNTER is a number of times the UE attempts to transmit the PRACH,

Configuration information on the transmission power of the PRACH determined based on the number of times the PRACH is repeatedly transmitted provides a base station characterized in that the preambleInitialReceivedTargetPower . In addition, the transmission power of the PRACH in the terminal is determined using the following equation (21),

(21) P _PRACH = min {

, PREAMBLE_RECEIVED_TARGET_POWER +

} _ [dBm]

In Equation (21), P _PRACH is the transmit power of the PRACH,

Is the maximum transmit power,

Is a downlink path loss, PREAMBLE_RECEIVED_TARGET_POWER is determined using Equation (22) below,

(22) PREAMBLE_RECEIVED_TARGET_POWER = preambleInitialReceivedTargetPower + DELTA_PREAMBLE + (PREAMBLE_TRANSMISSION_COUNTER-1) * powerRampingStep

In Equation (22), preambleInitialReceivedTargetPower and powerRampingStep are values transmitted by higher layer signaling, DELTA_PREAMBLE is a value determined according to a format of a random access preamble, and PREAMBLE_TRANSMISSION_COUNTER is a number of times the UE attempts to transmit the PRACH. The configuration information on the transmit power of the PRACH determined based on the number of times the PRACH is repeatedly transmitted provides a base station characterized in that the powerRampingStep .

According to the present invention described above, by repeatedly transmitting and receiving the random access preamble of the coverage restriction terminal, it is possible to improve the transmission and reception performance of the random access preamble of the coverage restriction terminal.

According to the present invention, when the MTC terminal repeatedly transmits the random access preamble in a plurality of subframes, a method of controlling the transmit power of the random access preamble can be provided.

1 is a diagram illustrating an initial cell access procedure of a terminal.

FIG. 2 is a diagram illustrating a random access procedure in FIG. 1.

3 is a diagram illustrating a process of transmitting a random access preamble and a random access response in the case of a general terminal.

4 is a table illustrating a value of a parameter DELTA_PREAMBLE used when determining a transmission power of a random access preamble in the case of a general terminal.

FIG. 5 is a diagram illustrating a process in which a random access preamble and a random access response are repeatedly transmitted in the case of an MTC terminal.

6 is a flowchart illustrating a method of performing random access according to embodiments of the present invention.

7 is a flowchart illustrating a random access preamble transmission method according to an embodiment of the present invention.

8 is a table illustrating an example of a relationship between the preamble repetition level and the number of repetitions of the random access preamble.

9 is a table illustrating an example of a relationship between a preamble repetition level, a repetition number of a random access preamble, and a path loss value.

10 is a flowchart illustrating a random access preamble transmission method according to another embodiment of the present invention.

11 is a flowchart illustrating a random access preamble transmission method according to another embodiment of the present invention.

12 is a table illustrating an example of a relationship between a preamble repetition level, a repetition number of a random access preamble, and a coverage level.

FIG. 13 is a table showing another example of the relationship between the repetition level of the preamble repetition level, the number of repetitions of the random access preamble, and the coverage level. FIG.

14 is a flowchart illustrating an embodiment of first attempting power ramping and then attempting preamble repetition level ramping.

FIG. 15 is a diagram illustrating an example of a change in transmission power and the number of transmissions of a random access preamble transmission over time in the example of FIG. 14.

16 is a flowchart illustrating another embodiment of attempting power ramping first and then preamble repetition level ramping.

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

18 is a block diagram illustrating a configuration of a terminal according to another embodiment of the present invention.

19 is a table illustrating an example of the table of FIG. 8.

20 is a flowchart illustrating a method of controlling random access preamble transmission power according to an embodiment of the present invention.

21 is a flowchart illustrating a method of controlling random access preamble transmission power according to another embodiment of the present invention.

FIG. 22 is a table illustrating an example of parameters delivered through higher layer signaling in FIG. 21.

FIG. 23 is a table illustrating another example of parameters transmitted through higher layer signaling in FIG. 21.

FIG. 24 is a table illustrating still another example of parameters transmitted through higher layer signaling in FIG. 21.

FIG. 25 is a flowchart illustrating an example of a method of controlling random access preamble transmission power when a random access preamble transmission fails.

FIG. 26 is a diagram illustrating an example of a change in transmit power and the number of times of transmission of a random access preamble transmission in the example of FIG.

27 is a flowchart illustrating another example of a method of controlling random access preamble transmission power for a case where random access preamble transmission fails.

FIG. 28 is a diagram illustrating an example of a change in transmit power and the number of times of transmission of a random access preamble transmission over time in the example of FIG. 27.

29 is a block diagram illustrating a configuration of a terminal according to an embodiment of the present invention.

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

Hereinafter, some embodiments of the present invention will be described in detail through exemplary drawings. In adding reference numerals to the components of each drawing, it should be noted that the same reference numerals are assigned to the same components as much as possible even though they are shown in different drawings. In addition, in describing the present invention, when it is determined that the detailed description of the related well-known configuration or function may obscure the gist of the present invention, the detailed description thereof will be omitted.

In the present specification, the MTC terminal may mean a terminal supporting low cost (or low complexity) or a terminal supporting coverage enhancement. In the present specification, the MTC terminal may mean a terminal supporting low cost (or low complexity) and coverage enhancement. Alternatively, in the present specification, the MTC terminal may mean a terminal defined in a specific category for supporting low cost (or low complexity) and / or coverage enhancement.

In other words, in the present specification, the MTC terminal may mean a newly defined 3GPP Release-13 low cost (or low complexity) UE category / type for performing LTE-based MTC related operations. Alternatively, in the present specification, the MTC terminal supports enhanced coverage compared to the existing LTE coverage, or supports UE category / type defined in the existing 3GPP Release-12 or lower, or newly defined Release-13 low cost (or lower power consumption). low complexity) can mean UE category / type.

The wireless communication system in the present invention is widely deployed to provide various communication services such as voice, packet data, and the like. The wireless communication system includes a user equipment (UE) and a base station (base station, BS, or eNB). In the present specification, a user terminal is a generic concept meaning a terminal in wireless communication. In addition, user equipment (UE) in WCDMA, LTE, and HSPA, as well as mobile station (MS) in GSM, user terminal (UT), and SS It should be interpreted as a concept that includes a 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, an Sector, a Site, and a BTS. Other terms such as a base transceiver system, an access point, a relay node, a remote radio head (RRH), a radio unit (RU), and a small cell may be called.

In other words, in the present specification, a base station or a cell is a generic meaning indicating some areas or functions covered by a base station controller (BSC) in CDMA, a Node-B in WCDMA, an eNB or a sector (site) in LTE, and the like. It should be interpreted as, and it is meant to cover all the various coverage areas such as megacell, macrocell, microcell, picocell, femtocell and relay node, RRH, RU, small cell communication range.

Since the various cells listed above have a base station for controlling each cell, the base station may be interpreted in two senses. i) the device providing the megacell, the macrocell, the microcell, the picocell, the femtocell, the small cell in relation to the wireless area, or ii) the wireless area itself. In i) all devices which provide a given wireless area are controlled by the same entity or interact with each other to cooperatively configure the wireless area to direct the base station. The eNB, RRH, antenna, RU, LPN, point, transmit / receive point, transmit point, receive point, and the like, according to the configuration of the radio region, become an embodiment of the base station. In ii), the base station may indicate the radio area itself to receive or transmit a signal from a viewpoint of a user terminal or a neighboring base station.

Therefore, megacells, macrocells, microcells, picocells, femtocells, small cells, RRHs, antennas, RUs, low power nodes (LPNs), points, eNBs, transmit / receive points, transmit points, and receive points are collectively referred to as base stations. do.

In the present specification, the user terminal and the base station are two transmitting and receiving entities used to implement the technology or technical idea described in this specification in a comprehensive sense and are not limited by the terms or words specifically referred to. The user terminal and the base station are two types of uplink or downlink transmitting / receiving subjects used to implement the technology or the technical idea described in the present invention, and are used in a generic sense and are not limited by the terms or words specifically referred to. Here, the uplink (Uplink, UL, or uplink) refers to a method for transmitting and receiving data to the base station by the user terminal, the downlink (Downlink, DL, or downlink) means to transmit and receive data to the user terminal by the base station It means the way.

There is no limitation on the multiple access scheme applied to the wireless communication system. Various multiple access techniques 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-TDMA, OFDM-CDMA Can be used. One embodiment of the present invention can be applied to resource allocation in the fields of asynchronous wireless communication evolving to LTE and LTE-Advanced through GSM, WCDMA, HSPA, and synchronous wireless communication evolving to CDMA, CDMA-2000 and UMB. The present invention should not be construed as being limited or limited to a specific wireless communication field, but should be construed as including all technical fields to which the spirit of the present invention can be applied.

The uplink transmission and the downlink transmission may use a time division duplex (TDD) scheme that is transmitted using different times, or may use a frequency division duplex (FDD) scheme that is transmitted using different frequencies.

In addition, in systems such as LTE and LTE-Advanced, a standard is configured by configuring uplink and downlink based on one carrier or a pair of carriers. The uplink and the downlink include a Physical Downlink Control CHannel (PDCCH), a Physical Control Format Indicator CHannel (PCFICH), a Physical Hybrid ARQ Indicator CHannel (PHICH), a Physical Uplink Control CHannel (PUCCH), an Enhanced Physical Downlink Control CHannel (EPDCCH), and the like. Control information is transmitted through the same control channel, and data is configured by a data channel such as a physical downlink shared channel (PDSCH) and a physical uplink shared channel (PUSCH).

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

In the present specification, a cell means a component carrier having a coverage of a signal transmitted from a transmission / reception point or a signal transmitted from a transmission point or a transmission / reception point, and the transmission / reception point itself. Can be.

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

The multiple transmit / receive point is at least one having a base station or a macro cell (hereinafter referred to as an eNB) and a high transmission power or a low transmission power in a macro cell region, which is wired controlled by an optical cable or an optical fiber to the eNB. May be RRH.

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

Hereinafter, a situation in which a signal is transmitted and received through a channel such as a PUCCH, a PUSCH, a PDCCH, an EPDCCH, and a PDSCH may be expressed in the form of 'sending and receiving a PUCCH, a PUSCH, a PDCCH, an EPDCCH, and a PDSCH.'

In addition, hereinafter, a description of transmitting or receiving a PDCCH or transmitting or receiving a signal through the PDCCH may be used as a meaning including transmitting or receiving an EPDCCH or transmitting or receiving a signal through the EPDCCH.

That is, the physical downlink control channel described below may mean PDCCH or EPDCCH, and may also be used to include both PDCCH and EPDCCH.

In addition, for convenience of description, the EPDCCH, which is an embodiment of the present invention, may be applied to the portion described as the PDCCH, and the EPDCCH may be applied to the portion described as the EPDCCH as an embodiment of the present invention.

Meanwhile, high layer signaling described below includes RRC signaling for transmitting RRC information including an RRC parameter.

The base station performs downlink transmission to the terminals. The base station includes downlink control information such as a physical downlink shared channel (PDSCH), which is a main physical channel for unicast transmission, and scheduling required for reception of the PDSCH and an uplink data channel (eg, For example, a physical downlink control channel (PDCCH) for transmitting scheduling grant information for transmission on a physical uplink shared channel (PUSCH) may be transmitted. Hereinafter, the transmission and reception of signals through each channel will be described in the form of transmission and reception of the corresponding channel.

1 is a diagram illustrating an initial cell access procedure of a terminal.

Referring to FIG. 1, in an initial cell access process of a terminal, the terminal 10 receives a primary synchronization signal (PSS) and a secondary synchronization signal (SSS), which are synchronization signals transmitted from the base station 20 (S102). In the LTE Frequency Division Duplex (FDD), the PSS may be transmitted in the last symbol (#n) of the first slot of subframe # 0 and subframe # 5 in one radio frame (eg, 10 ms), The SSS may be transmitted in the previous symbol (# n-1) of the last symbol (#n) of the first slot of # 0 and subframe # 5. In LTE TDD, PSS / SSS may be transmitted to a location different from FDD. When the terminal 10 detects the PSS and the SSS, the terminal 10 may acquire cell ID and downlink synchronization information, and a cell-specific reference signal (CRS) based on the information obtained based on the PSS / SSS. ) Can perform additional synchronization and existing control channel decoding.

The terminal 10 receives a signal from the base station 20 through the PBCH based on the CRS (S104), and extracts a MIB (Master Information Block) transmitted through the PBCH (S106). The MIB may include information indicating a cell bandwidth, information indicating a PHICH configuration, and information indicating a system frame number. The terminal 10 can know the resource to which the PDCCH is allocated based on the information included in the MIB.

The terminal 10 receives a signal from the base station 20 through the PDCCH based on the CRS (S108), and extracts downlink control information (DCI) transmitted through the PDCCH (S110). DCI may be control information for a PDSCH through which a System Information Block (SIB) is transmitted, and may be delivered through a common search space.

The terminal 10 receives a signal from the base station through the PDSCH based on the DM-RS (Demodulation Reference) based on the DCI (S112), and extracts the SIB transmitted through the PDSCH (S114).

Thereafter, the terminal 10 and the base station 20 perform a random access procedure (S116), and the terminal 10 may be in an RRC connected state in an RRC idle state. .

FIG. 2 illustrates an operation S116 for performing the random access procedure of FIG. 1 in more detail.

Referring to FIG. 2, the base station 20 transmits PRACH configuration information to the terminal 10 (S202). PRACH configuration information may be included in SIB2. The PRACH configuration information may include parameters preambleInitialReceivedTargetPower and powerRampingStep used when determining the transmit power of the PRACH. Detailed description of the parameters preambleInitialReceivedTargetPower and powerRampingStep will be described later.

The terminal 10 determines the transmission power of the PRACH and transmits a random access preamble to the base station 20 through the PRACH (S204).

Upon receiving the random access preamble, the base station 20 transmits scheduling information on a random access response (RAR) to the terminal 10 through the PDCCH or the EPDCCH (S206). Downlink control information (DCI) including scheduling information about the RAR may be scrambled to the RA-RNTI and transmitted through a PDCCH or an EPDCCH common search space (CSS).

The base station 20 transmits the RAR to the terminal 10 through the PDSCH, and the terminal 10 receiving the scheduling information for the RAR receives the RAR by using the same (S208).

Referring to FIG. 3, the terminal 10 transmits a random access preamble on a PRACH in uplink subframe #n. Upon receiving the random access preamble, the base station 20 transmits the RAR through the PDSCH in downlink subframe # (n + k). In this case, the UE 10 transmits a random access preamble in one uplink subframe (subframe #n), and the base station 20 performs RAR in one downlink subframe (subframe # (n + k)). Send it. When the UE 10 fails to transmit the random access preamble (or when the UE 10 fails to receive the RAR), the UE 10 transmits the random access preamble through the PRACH in the next PRACH transmission subframe.

In step S204 of FIG. 2, the random access preamble transmit power P _PRACH of the terminal 10 may be determined by Equation 1 below.

Equation 1 P _PRACH = min {

, PREAMBLE_RECEIVED_TARGET_POWER +

} _ [dBm]

In Equation 1,

Is the maximum transmit power in subframe i of the serving cell c in which the UE transmits the random access preamble, PREAMBLE_RECEIVED_TARGET_POWER is the target preamble receive power generated in the MAC layer,

Is a value of downlink path loss measured by the terminal 10. PREAMBLE_RECEIVED_TARGET_POWER may be determined by Equation 2 below.

[Equation 2]

PREAMBLE_RECEIVED_TARGET_POWER = preambleInitialReceivedTargetPower + DELTA_PREAMBLE + (PREAMBLE_TRANSMISSION_COUNTER-1) * powerRampingStep

In Equation 2, preambleInitialReceivedTargetPower and powerRampingStep are RRC parameters, which are values received through higher layer signaling in step S202 of FIG. 2, and DELTA_PREAMBLE is a value determined according to a preamble format as shown in the table of FIG. The number of attempts to transmit the preamble.

Referring to

Equations

1 and 2, when the UE 10 transmits the random access preamble for the first time and the preamble format is 0 or 1, the random access preamble transmit power P _PRACH is min {

, preambleInitialReceivedTargetPower +

} In case of failing to transmit the random access preamble and retransmitting the random access preamble, the random access preamble transmit power P _PRACH increases by powerRampingStep.

[LTE-based low-cost MTC]

As LTE networks proliferate, mobile operators want to minimize the number of Radio Access Terminals (RATs) to reduce network maintenance costs. However, MTC products based on conventional GSM / GPRS networks are increasing, and MTCs using low data rates can be provided at low cost. Therefore, since the mobile operators use the LTE network for general data transmission and the GSM / GPRS network for the MTC, there is a problem of operating two RATs, which are inefficient use of the frequency band. It becomes burden on profit.

In order to solve this problem, cheap MTC terminal using GSM / EGPRS network should be replaced with MTC terminal using LTE network. To this end, various requirements for lowering the price of LTE MTC terminal are required for the 3GPP RAN WG1 standard meeting. Is discussed. In addition, the standard meeting is preparing a document describing various functions that can be provided to satisfy the requirements.

In order to support the low-cost LTE MTC terminal, the main items related to the physical layer specification change currently being discussed in 3GPP may include technologies such as narrowband support / single RF chain / half duplex FDD / Long DRX (Discontinued Reception). However, the above methods, which are considered to lower the price, may reduce the performance of the MTC terminal compared to the conventional LTE terminal.

In addition, since about 20% of MTC terminals supporting MTC services such as smart metering are installed in a 'deep indoor' environment such as a basement, for successful MTC data transmission, the coverage of the LTE MTC terminal is conventional LTE terminal. It should be improved by about 20dB compared to the coverage of. In addition, if the performance reduction due to the specification change is further considered, the coverage of the LTE MTC terminal should be improved by 20 dB or more.

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

The requirements of the LTE-based low-cost MTC terminal is as follows.

-The data transmission rate must satisfy the data transmission rate provided by the MGP terminal based on the enhanced GPRS (EGPRS) minimum, that is, downlink 118.4kbps, uplink 59.2kbps.

-Frequency efficiency must be significantly improved compared to GSM / EGPRS MTC terminal.

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

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

-General LTE terminal and LTE MTC terminal should be available in 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 terminal should support limited mobility and low power consumption module.

In the present invention, a low-cost MTC terminal requiring coverage improvement due to poor radio channel transmission / reception performance compared to a general LTE / LTE-Advanced terminal will be referred to as a coverage limited MTC terminal.

[Random Access Preamble Repetition for Coverage Limited MTC Terminal]

In order to improve the random access preamble reception performance of the coverage limited MTC terminal in an arbitrary LTE / LTE-Advanced base station, a new random access preamble format for the MTC terminal is newly defined or an existing random access preamble format is repetitively transmitted. May be considered.

For example, in the case of a coverage limited MTC terminal, M uplink subframes (UL) are repeated by repeating M preambles generated based on a random access preamble format for a conventional LTE / LTE-Advanced terminal as shown in FIG. 4 times. A scheme of transmitting in subframe # (n-M + 1) to UL subframe #n may be considered. In this case, the base station may repeat the RAR to the coverage limited MTC terminal L times and transmit in L downlink subframes (DL subframe # (n + k) to DL subframe # (n + k + L-1)). .

For another example, in the case of the coverage limited MTC terminal, the length of the preamble format defined in M uplink subframes, that is, the sum of the CP length and the sequence length of the preamble format,

The value of, or the sequence length,

A method of transmitting a preamble generated based on a new random access preamble format having an increased length) may be considered.

In addition, the application of the semi-static scheduling method, rather than the existing dynamic scheduling method, for the allocation of the RAR message transmission resource for the corresponding coverage limited MTC terminal is considered.

As described above, in order to apply semi-static scheduling to a corresponding RAR, a definition of one or more downlink subframes in which the corresponding RAR is transmitted and a method of allocating PRBs for RAR transmission in the corresponding downlink subframe are required. In the conventional LTE / LTE-Advanced system, according to the method of transmitting a random access preamble of a terminal, a terminal to transmit a random access preamble is a random access preamble format configured in a corresponding cell according to Equation 1 and Equation 2 above. Set to send. However, when the PRACH repetition scheme is applied as a method for improving the preamble reception performance of the coverage limited MTC terminal, a definition of a number of repetition (M value) configuration method for the corresponding MTC terminal is required.

Embodiments of the present invention propose a method for configuring a random access preamble repetition level (M value) for an MTC terminal.

Embodiments of the present invention propose a random access preamble transmission scheme of an arbitrary coverage restricted MTC terminal. In particular, when a random access preamble transmission is repeatedly transmitted through a plurality of uplink subframes as a method for improving transmission / reception performance of a random access preamble of a coverage limited MTC terminal, a corresponding repetition level (or number of repetitions) and respective random accesses A method for determining preamble transmission power is proposed.

Referring to FIG. 6, in the embodiments of the present invention, the terminal 10 performs random access, and the random access preamble is determined by at least one variable or coverage level among variables that determine the transmit power of the random access preamble. Determining a preamble repetition level (S602), repeatedly transmitting a random access preamble through a specific number of subframes corresponding to the determined preamble repetition level (S604), and random access associated with the random access preamble (S604) Receiving a response from the base station 20 (S606).

In this case, the terminal 10 may perform the step S602 of determining the preamble repetition level based on at least one variable or coverage level among the variables that determine the transmission power of the random access preamble before step S604. In step S604, a specific number of subframes corresponding to a preamble repetition level determined by at least one variable or a coverage level of the random access preamble is determined without performing step S602. It may be repeatedly transmitted to the base station 20 through.

In this case, when the terminal 10 does not receive a random access response related to the random access preamble from the base station, the terminal 10 may repeat the step of transmitting the random access preamble to the base station 20 (S604). In other words, upon receiving the random access response related to the random access preamble, the terminal 10 ends the random access procedure without having to repeat the step of transmitting the random access preamble to the base station 20.

Meanwhile, the preamble repetition level is a downlink path loss value (

The maximum transmit power of the UE, which is a variable that determines the transmit power of the random access preamble,

), Downlink path loss value (

), may be determined by a function of preambleInitialReceivedTargetPower, DELTA_PREAMBLE.

The coverage level may be determined by the number of repetitions of the downlink physical channel or may be set by UE-specific higher layer signaling.

In addition, when the terminal 10 does not receive the random access response from the base station 20, and repeats the step S604 of transmitting the random access preamble to the base station 20, the preamble repetition level n (n is greater than 1). The random power preambles corresponding to M numbers (where M is a natural number greater than 1) are repeatedly transmitted to the base station 20, ramping the transmission power, and increasing the preamble repetition level when a specific condition is achieved. Can be repeatedly transmitted to the base station 20.

실시예1Example 1

Referring to FIG. 7, an embodiment of the present invention is a method for transmitting a random access preamble (700). The random access preamble is a downlink path loss value (

Determining a preamble repetition level (S702), transmitting the random access preamble repeatedly through a specific number of subframes corresponding to the determined preamble repetition level to the base station 20 (S704), and the random access preamble. Receiving an associated random access response from the base station 20 (S706).

In this case, when the terminal 10 does not receive a random access response related to the random access preamble from the base station, the terminal 10 may repeat the step of transmitting the random access preamble to the base station 20. In other words, upon receiving the random access response related to the random access preamble, the terminal 10 ends the random access procedure without having to repeat the step S704 of transmitting the random access preamble to the base station 20.

To this end, an embodiment of the present invention will be described based on the case in which five random access preamble formats defined in the existing LTE / LTE-Advanced system shown in FIG. 4 are repeatedly transmitted. A case where the number of random access preamble repetition levels is N as shown in the table of FIG. 8 will be described.

In FIG. 8, the corresponding n and Mn (n = 1, 2, ..., N) values have a natural value greater than any zero, and it is clear that the proposal of the present invention can be applied without limiting the specific values.

As described above, in step S802, the first random access preamble repetition level n or the number of repetitions Mn for the coverage limited MTC terminal 10 entering the random access procedure is a downlink path loss value.

Can be determined by.

As a specific example for this, as shown in FIG. 9 below, a random base station 20 sets a path loss value or a threshold value of a path loss for preamble repetition level selection for the MTC terminal 10 in a corresponding cell. The terminal may be transmitted to the terminal through UE-specific higher layer signaling or may be defined to be applied to the MTC terminal by defining a fixed path loss threshold value for each repetition level.

At this time, the path loss threshold for setting the repetition level is a lower limit, which is measured by an arbitrary MTC terminal.

Value is

If it is satisfied, it can be defined to select the repetition level n (where n = 1, 2, ..., N). but,

Can be defined as Alternatively, the threshold for setting the repetition level is an upper limit.

If it is satisfied, the repetition level n (where n = 1, 2, ..., N) is selected, and in other cases, the repetition level, N can be defined. but,

Can be defined as

실시예2Example 2

Referring to FIG. 10, another embodiment of the present invention is a random access preamble transmission method 1000. The random access preamble includes a maximum transmit power of a terminal.

), Downlink path loss value (

), determining a preamble repetition level by a function of preambleInitialReceivedTargetPower, DELTA_PREAMBLE (S1002), and repeatedly transmitting a random access preamble through a specific number of subframes corresponding to the determined preamble repetition level to the base station 20 (S1004). And receiving a random access response related to the random access preamble from the base station 20 (S1006).

In this case, when the terminal 10 does not receive a random access response related to the random access preamble from the base station, the terminal 10 may repeat the step of transmitting the random access preamble to the base station 20 (S1004).

Meanwhile, the terminal 10 may receive PRACH configuration information from the base station 20 through higher layer signaling (S1001). The PRACH configuration information may include parameters preambleInitialReceivedTargetPower and powerRampingStep. Or, the PRACH configuration information may further include a new parameter.

The terminal 10 may determine the random access preamble transmission power. In this case, the terminal 10 calculates a random access preamble transmission power using Equation 1 described above, and PREAMBLE_RECEIVED_TARGET_POWER may be calculated using an equation different from Equation 2.

As described above, in step S1002, as another example of determining the repetition level of the preamble according to the downlink path loss, the maximum transmit power of the corresponding MTC terminal 10 is determined.

It can be defined to determine the repetition level as a function of preambleInitialReceivedTargetPower which is a parameter set by path loss and higher layer signaling. In this case, a DELTA_PREAMBLE value, which is an offset value according to the preamble format, may also be used as a parameter for determining a corresponding repetition level.

As an example, when an arbitrary MTC terminal 10 transmits a preamble at the maximum transmission power, random access preamble transmission to transmit a minimum repetition level that satisfies a target reception power preambleInitialReceivedTargetPower at the base station is transmitted from the terminal. It can be defined to set to the first preamble repetition level of.

For example, the preamble repetition level n, for random access preamble transmission, can be any i = 1,... When

N

3 and 4 below N-1 are satisfied, n = i may be determined.

[Equation 3]

[Equation 4]

In addition, the preamble repetition level n for random access preamble transmission may be defined to be determined as n = 1 when satisfying Equation 5 and n = N when otherwise satisfying Equation (6).

[Equation 5]

[Equation 6]

실시예3Example 3

Referring to FIG. 11, according to another embodiment of the present invention, in the method 1100 for transmitting a random access preamble, determining a preamble repetition level based on a coverage level of a random access preamble (S1102), and preamble repetition for determining a random access preamble is determined. And transmitting to the base station 20 repeatedly through a specific number of subframes corresponding to the level (S1104) and receiving a random access response related to the random access preamble from the base station 20 (S1106).

In this case, when the terminal 10 does not receive a random access response related to the random access preamble from the base station, the terminal 10 may repeat the step of transmitting the random access preamble to the base station 20. In other words, upon receiving the random access response related to the random access preamble, the terminal 10 ends the random access procedure without having to repeat the step S1104 of transmitting the random access preamble to the base station 20.

In step S1102, another example of determining the first random access preamble repetition level, n or the number of repetitions, and the Mn value for the coverage limited MTC terminal 10 entering the random access procedure, random access preamble repetition for the coverage limited MTC terminal The level, n or the number of repetitions, and the Mn value may be determined by the coverage level of the corresponding coverage limit MTC terminal. In this specification, a coverage level may mean a topology.

Coverage Restriction To support extended coverage for MTC UE, the base station 20 transmits a plurality of downlinks through downlink physical channels, for example, PBCH, PDCCH or EPDCCH, and PDSCH transmissions, which are performed in units of one downlink subframe. It is necessary to repeatedly transmit through a subframe, and the corresponding MTC terminal also needs to perform decoding by combining PBCH, PDCCH or EPDCCH and PDSCH received through the plurality of downlink subframes.

In this case, the coverage level is the number of repetitions for the PBCH or PDSCH, which is a physical channel through which the corresponding information required for successful decoding of the MIB or SIB information is transmitted (decoding of the corresponding information from the terminal's reception point of view). May be determined by the number of combinations of the corresponding repeated physical channels) or may be set by UE-specific higher layer signaling.

Accordingly, when the coverage level of the corresponding MTC terminal is determined, the coverage level and the first preamble repetition level for random access preamble transmission set in the terminal may be defined to have a 1: 1 correspondence as shown in FIG. 12. However, it is not limited thereto.

On the other hand, if the total number of coverage levels and the total number of preamble repetition levels are different, the coverage level and the first preamble repetition level correspond to x: y (where x and y are natural numbers greater than 0 and x and y are not the same). Can be defined to have. For example, if the total number of coverage levels is smaller than the total number of preamble repetition levels, the preamble repetition levels may be different even if they are the same coverage level. In this case, different preamble repetition level settings for the same coverage level may use at least one of the variables for determining the transmission power of the random access preamble described above, or may use a higher layer signaled parameter.

For example, as shown in FIG. 13, when the total number of preamble repetition levels is 5 and the total number of coverage levels is 3, the same coverage level, for example, the coverage level.

The

preamble level

1 or 2 may be set by using at least one of the variables for determining the transmission power of the random access preamble described above, or by using a higher layer signaled parameter.

실시예4Example 4

In the above-described embodiments of the present invention, the present invention relates to a method for determining an initial preamble repetition level, n, of a terminal determined to perform an arbitrary random access procedure by an upper layer of an MTC terminal.

Another embodiment of the present invention corresponds to a preamble repetition level n (n is a natural number greater than 1) when the random access response is not received from a base station and the step of transmitting the random access preamble to the base station is repeated. Whenever the Mn random access preambles are repeatedly transmitted to the base station, the power is ramped to transmit power, and when a specific condition is achieved, the preamble repetition level is increased to repeatedly transmit the random access preamble to the base station.

For example, each time a random access preamble transmission is performed based on the first repetition level n determined by the above-described embodiments of the present invention, the corresponding PREAMBLE_TRANSMISSION_COUNTER is increased by 1, and the corresponding PREAMBLE_TRANSMISSION_COUNTER is a certain number, that is, a threshold value. Or transmit power for each random access preamble transmission

If reaches, the preamble repetition level may be increased by 1 to define random access preamble transmission. However, when the random access preamble repetition level is the maximum value, the repetition level may be maintained.

In addition, when the preamble repetition level is increased by 1 and the random access procedure is continued, the PREAMBLE_TRANSMISSION_COUNTER of the corresponding UE may be defined to be reset to an initial value of 1 again.

실시예4aExample 4a

Referring to FIG. 14, the terminal 10 transmits a random access preamble at a transmission power determined based on a preamble repetition level or a preamble repetition number (S1402). In this case, the initial preamble repetition level may be determined by the above-described embodiments.

The terminal 10 determines whether a random access response (RAR) has been received for the transmitted random access preamble (S1404).

When the random access response to the transmitted random access preamble is not received, that is, when the random access preamble transmission has failed (NO in S1404), the terminal 10 uses the setting formula of PREAMBLE_RECEIVED_TARGET_POWER (for example, Equation 2). Power ramping is performed by increasing the value of PREAMBLE_TRANSMISSION_COUNTER by 1 (S1406). At this time, the value of PREAMBLE_RECEIVED_TARGET_POWER is increased by the value of powerRampingStep or normalized powerRampingStep, and the random access preamble transmission power P _PRACH is increased by the value of powerRampingStep or normalized powerRampingStep.

The terminal 10 determines that the random access preamble transmit power P _PRACH determined in step S1406 is a maximum transmit power (

(S1408). The determined random access preamble transmit power (P _PRACH ) is _equal to the maximum transmit power (

) Or less (YES in S1408), the terminal 10 retransmits the random access preamble using the random access preamble transmit power P _PRACH determined in step S1406 (S1402).

The determined random access preamble transmit power (P _PRACH ) is _equal to the maximum transmit power (

Greater than (NO in S1408), the UE 10 performs repetition level ramping by increasing the preamble repetition level to the next level (S1410), and transmits a random access preamble based on the increased preamble repetition level or the number of preamble repetitions. The power P _PRACH is determined (S1412). The terminal 10 retransmits the random access preamble using the random access preamble transmit power P _PRACH determined in step S1412 (S1402).

When the terminal 10 performs the preamble repetition level ramping, the terminal 10 may reset the value of the PREAMBLE_TRANSMISSION_COUNTER to an initial value of 1, thereby determining the random access preamble transmission power. Alternatively, the terminal 10 may determine the random access preamble transmission power while maintaining the value of PREAMBLE_TRANSMISSION_COUNTER. Alternatively, the terminal 10 may use the random access preamble transmission power as the current transmission power, that is, the maximum transmission power (

You can increase the repetition level only while

Referring to FIG. 15, the terminal 10 initially transmits a random access preamble with a preamble repetition number of 4 (1510). When the random access preamble transmission fails, the terminal 10 performs power ramping to increase the transmission power of the random access preamble in

steps

1520 and 1530. The transmit power of the random access preamble is equal to the maximum transmit power (

When the random access preamble transmission fails even though the RxHxHxHDHDHDHDH arrives, the UE 10 transmits the random access preamble by increasing the number of preamble repetitions by performing repetition level ramping (1540).

Although the preamble transmit power is shown as constant when repetitive level ramping is performed in FIG. 15, the present invention is not limited thereto. As another example, the terminal 10 may newly determine the transmission power of the random access preamble based on the changed number of preamble repetitions when performing repetition level ramping.

실시예4bExample 4b

Referring to FIG. 16, in another embodiment in which power ramping is attempted first and then preamble repetition level ramping is performed, steps S1602, S1604, S1606, S1610, and S1612 first attempt the power ramping described with reference to FIG. 14. In an embodiment in which preamble repetition level ramping is attempted, steps S1402, S1404, S1406, S1410, and S1412 are substantially the same.

In step S1608, the terminal 10 determines whether the PREAMBLE_TRANSMISSION_COUNTER (counter value in FIG. 16) is less than or equal to the threshold in step S1606.

If PREAMBLE_TRANSMISSION_COUNTER is less than or equal to the threshold (YES in S1608), the terminal 10 retransmits the random access preamble using the random access preamble transmit power P _PRACH determined in step S1606 (S1602).

If the PREAMBLE_TRANSMISSION_COUNTER is greater than the threshold (NO in S1608), the UE 10 performs repetition level ramping by increasing the preamble repetition level to the next level (S1610).

17 is a diagram illustrating a configuration of a base station according to another embodiment.

Referring to FIG. 17, a base station 1700 according to another embodiment includes a controller 1710, a transmitter 1720, and a receiver 1730.

The control unit 1710 is a method for improving the transmission / reception performance of the random access preamble of the coverage limited MTC terminal required for carrying out the above-described present invention, and the random access preamble transmission is repeatedly transmitted through a plurality of uplink subframes. In this case, the operation of the overall base station in determining the corresponding preamble level (or the number of repetitions) and the respective preamble transmission powers is controlled.

The transmitter 1720 and the receiver 1730 are used to transmit and receive signals, messages, and data necessary for carrying out the present invention.

The receiver 1730 may repeatedly receive the random access preamble from the base station through a specific number of subframes corresponding to the preamble repetition level determined according to at least one variable or the coverage level of the variable determining the transmission power of the random access preamble. Can be.

In addition, the transmitter 1720 may transmit a random access response related to the random access preamble from the base station. In this case, when the transmitter 1730 does not transmit the random access response from the base station, the receiver 1730 may repeat the process of transmitting the random access preamble to the base station 1700.

18 is a diagram illustrating a configuration of a user terminal according to another embodiment.

Referring to FIG. 18, a user terminal 1800 according to another embodiment includes a receiver 1830, a controller 1810, and a transmitter 1820.

The receiver 1830 receives downlink control information, data, and a message from a base station through a corresponding channel.

In addition, the control unit 1810 is a method for improving the transmission and reception performance of the random access preamble of the coverage-restricted MTC terminal required for carrying out the above-described present invention, and the random access preamble transmission is repeated through a plurality of uplink subframes. When transmitted, it controls the overall operation of the UE according to determining the corresponding preamble level (or the number of repetitions) and the respective preamble transmission powers.

The transmitter 1820 transmits uplink control information, data, and a message to a base station through a corresponding channel.

The transmitter 1820 repeatedly transmits a random access preamble to a base station through a specific number of subframes corresponding to a preamble repetition level determined according to at least one variable or a coverage level among variables that determine the transmission power of the random access preamble. can do.

In addition, the receiver 1830 may receive a random access response related to a random access preamble from the base station. In this case, when the receiver 1830 does not receive a random access response from the base station, the transmitter 1820 may repeat the process of transmitting the random access preamble to the base station 1700.

On the other hand, the preamble repetition level is a downlink path loss value (

) Or the maximum transmit power of the terminal, as shown in FIG.

), Downlink path loss value (

), can be determined by a function of preambleInitialReceivedTargetPower, DELTA_PREAMBLE.

In addition, as shown in FIG. 11, the coverage level may be determined by the number of repetitions of the downlink physical channel or may be set by UE-specific higher layer signaling.

14 to 16, when the random access response is not received from the base station and the step of transmitting the random access preamble to the base station is repeated, the preamble repetition level n (n is a natural number greater than 1) is corresponded. Whenever the Mn random access preambles are repeatedly transmitted to the base station, the power is ramped to transmit power, and when a specific condition is achieved, the preamble repetition level is increased to repeatedly transmit the random access preambles to the base station 1700.

In this case, the specific condition is to increase the PREAMBLE_TRANSMISSION_COUNTER used to determine the transmit power of the random access preamble by 1, so that the PREAMBLE_TRANSMISSION_COUNTER reaches a certain number, or transmit power for each random access preamble transmission is increased.

May be reached. Meanwhile, by increasing the preamble repetition level by 1, the random access preamble may be repeatedly transmitted to the base station 1700.

According to the embodiments of the present invention described above, by repeatedly transmitting and receiving the random access preamble of the coverage restriction terminal, it is possible to improve the transmission and reception performance of the random access preamble of the coverage restriction terminal.

Although the present invention has been described above with reference to the drawings, the present invention is not limited thereto. For example, the above-described embodiments may be variously combined.

In the above, the random access preamble transmission / reception method and transmission power according to an embodiment of the present invention have been described according to each embodiment.

Hereinafter, a method of setting a random access preamble transmission power according to another embodiment of the present invention will be described. Each of the above-described embodiments and embodiments to be described below may be performed as separate embodiments, or may be performed in combination.

According to the conventional method of transmitting a random access preamble of a terminal in an LTE / LTE-Advanced system, a terminal to transmit a random access preamble is represented by Equations (1) and (2) in the random access preamble format set in a corresponding cell. Accordingly, the preamble transmission power was set and transmitted. However, when the above-described PRACH repetitive transmission scheme is applied as a method for improving the preamble reception performance of the coverage limited MTC terminal, it is necessary to newly define a method for setting the random access preamble transmission power accordingly.

The present invention proposes a random access preamble transmission power setting method for an MTC terminal. In particular, when a random access preamble of an arbitrary MTC terminal is defined to be repeatedly transmitted, a proposal for setting each random access preamble transmission power according to the number of repetition times M is proposed.

Embodiments of the present invention propose a random access preamble transmission scheme of an arbitrary coverage restricted MTC terminal. In particular, when a random access preamble transmission is repeatedly transmitted through a plurality of uplink subframes as a method for improving transmission / reception performance of a random access preamble of a coverage limited MTC terminal, a corresponding repetition level (or number of repetitions) and A method for determining each random access preamble transmission power is proposed.

To this end, the present invention will be described based on the case where five random access preamble formats defined in the existing LTE / LTE-Advanced system are repeatedly transmitted, and the number of random access preamble repetition levels supported by any cell is illustrated in FIG. 8. Based on N cases, as in the table below.

In Fig. 8, the corresponding n and M _n (n = 1, 2, ..., N) values have arbitrary natural number values, and it is clear that the proposal of the present invention can be applied without limiting the specific values.

As an example, referring to FIG. 19, the repetition level n and the repetition number M _{n of the} repetition level n may be defined in the form of 2 ^(n-1) .

As described above, when a plurality of repetition levels are defined for an arbitrary coverage limited MTC terminal, the transmission power for each random access preamble transmission of the corresponding MTC terminal according to the number of repetitions M _n according to the corresponding repetition level n value. Settings may vary.

According to the present invention, the corresponding MTC in Equation 1 used to determine the random access preamble transmission power in the physical layer of the existing LTE / LTE-Advanced terminal or the equation 2 used in determining the PREAMBLE_RECEIVED_TARGET_POWER in the MAC layer. A method of controlling the random access preamble transmission power for the coverage limited MTC terminal is added by adding the number of repetitions and the M _n value according to the random access preamble repetition level selected for the UE as parameters.

실시예 5. 물리 계층을 통한 랜덤 액세스 프리앰블 전송 전력 제어 Embodiment 5. Random Access Preamble Transmit Power Control Through the Physical Layer

In the present embodiment, among

Equations

1 and 2 used to set the random access preamble transmission power of the general terminal, Equation 1 is changed in consideration of the case where the random access preamble is repeatedly transmitted, and Equation 2 is Can be used unchanged.

Referring to FIG. 20, when the transmission of the random access preamble is set to be transmitted through M _n uplink subframes by repeating M _n times, the terminal 10 sets the transmission power of the random access preamble to repeat the number of random access preambles M _n. Determine as a function of (S2002). For example, the transmit power of the random access preamble may be determined as shown in Equation 7 below.

[Equation 7]

P _PRACH = min {

, PREAMBLE_RECEIVED_TARGET_POWER +

10 logM _n } _ [dBm]

In Equation 7,

Is the maximum transmit power in subframe i of the serving cell c to which the UE transmits the random access preamble,

Is the value of the downlink path loss measured by the terminal 10, and M _n is the number of random access preamble repetitions. PREAMBLE_RECEIVED_TARGET_POWER may be determined as in Equation 2 described above. When calculating PREAMBLE_RECEIVED_TARGET_POWER using Equation 2, the parameter PREAMBLE_TRANSMISSION_COUNTER indicating the number of times the UE attempts to transmit the random access preamble may repeat the random access preamble by repeating the random access preamble repetition number M _n times in one attempt. .

When the M _n value is defined in the form of 2 ^(n-1) as shown in the table of FIG. 19, Equation 7 may be expressed as Equation 8.

[Equation 8]

P _PRACH = min {

, PREAMBLE_RECEIVED_TARGET_POWER +

3 * (n-1)} _ [dBm]

The terminal 10 transmits the random access preamble to the base station 20 through the PRACH using the determined transmission power of the random access preamble (S2004).

Equation 7 is provided as an example, and various equations including a repetition level n or a random access preamble repetition number M _n of the random access preamble as a parameter may be used.

실시예 6. 상위 계층을 통한 랜덤 액세스 프리앰블 전송 전력 제어Embodiment 6. Random Access Preamble Transmit Power Control Through Higher Layer

In the present embodiment, among

Equations

1 and 2 used to set the random access preamble transmission power of the general terminal, Equation 1 is used unchanged, and Equation 2 considers a case where the random access preamble is repeatedly transmitted. It can be changed and used.

Referring to FIG. 21, the terminal 10 receives PRACH configuration information from the base station 20 through higher layer signaling (S2102). The PRACH configuration information may include parameters preambleInitialReceivedTargetPower and powerRampingStep . Or, the PRACH configuration information may further include a new parameter.

The terminal 10 determines the random access preamble transmit power based on the number of random access preamble repetitions (S2104). In this case, the terminal 10 calculates a random access preamble transmission power using Equation 1 described above, and PREAMBLE_RECEIVED_TARGET_POWER may be calculated using an equation different from Equation 2.

For example, PREAMBLE_RECEIVED_TARGET_POWER may be determined as in Equation 9 below.

[Equation 9]

PREAMBLE_RECEIVED_TARGET_POWER = preambleInitialReceivedTargetPower + DELTA_PREAMBLE + DELTA_PREAMBLE_REPETITION + (PREAMBLE_TRANSMISSION_COUNTER-1) * powerRampingStep

In Equation 9, preambleInitialReceivedTargetPower and powerRampingStep are RRC parameters, which are values received through higher layer signaling in step S2102, DELTA_PREAMBLE is a value determined according to a preamble format as shown in the table of FIG. 4, and PREAMBLE_TRANSMISSION_COUNTER is a UE transmission of a random access preamble. The number of attempts made. PREAMBLE_TRANSMISSION_COUNTER may attempt to transmit the random access preamble by repeating the random access preamble repetition number M _n times in one attempt.

Meanwhile, DELTA_PREAMBLE_REPETITION may be determined by the table of FIG. 22. Referring to FIG. 22, DELTA_PREAMBLE_REPETITION may be determined according to a random access preamble repetition level. Alternatively, DELTA_PREAMBLE_REPETITION may be determined according to the number of random access preamble repetitions.

According to this example, PREAMBLE_RECEIVED_TARGET_POWER may be determined based on the random access preamble repetition level or the number of random access preamble repetitions, and thus the preamble transmit power P _{PRACH may} also be determined based on the random access preamble repetition level or the number of random access preamble repetitions.

For another example, PREAMBLE_RECEIVED_TARGET_POWER may be determined as in Equation 10 below.

[Equation 10]

PREAMBLE_RECEIVED_TARGET_POWER = preambleInitialReceivedTargetPower + DELTA_PREAMBLE + a * M _n + (PREAMBLE_TRANSMISSION_COUNTER-1) * powerRampingStep

In Equation 10, preambleInitialReceivedTargetPower and powerRampingStep are RRC parameters, which are values received through higher layer signaling in step S2102, DELTA_PREAMBLE is a value determined according to a preamble format as shown in the table of FIG. 4, and PREAMBLE_TRANSMISSION_COUNTER is a UE transmission of a random access preamble. The number of attempts made. PREAMBLE_TRANSMISSION_COUNTER may attempt to transmit the random access preamble by repeating the random access preamble repetition number M _n times in one attempt. In addition, M _n is the number of random access preamble repetitions, a may be previously set as a proportional constant, or may be a value indicated by the base station through, for example, higher layer signaling. For example, it may be set to a = -3, or may be set to another real number.

In Equation 10, instead of the random access preamble transmission repetition M _n , the random access preamble repetition level n may be used.

As another example, PREAMBLE_RECEIVED_TARGET_POWER may be determined as shown in Equation 2 above.

In this case, preambleInitialReceivedTargetPower , a parameter used in Equation 2, may be defined as a separate value according to the random access preamble repetition level or the number of random access preamble repetitions. For example, the parameter preambleInitialReceivedTargetPower may be defined as shown in the table of FIG. 23. The base station 20 defines a separate value for the preambleInitialReceivedTargetPower for each random access preamble repetition level or the number of random access preamble repetitions using the table of FIG. 23, and uses the cell-specific or terminal-specific RRC signaling for the terminal 10. Can be sent to. The terminal 10 may receive the parameter preambleInitialReceivedTargetPower defined by the base station 20 in step S902, and calculate the PREAMBLE_RECEIVED_TARGET_POWER using this in step S2104.

Alternatively, the value of preambleInitialReceivedTargetPower according to the random access preamble repetition level or the number of random access preamble repetitions may be defined to be implicitly determined.

In this case, powerRampingStep, which is a parameter used in Equation 2, may be defined as a separate value according to the random access preamble repetition level or the number of random access preamble repetitions. For example, the parameter powerRampingStep may be defined as shown in the table of FIG. 24. The base station 20 defines a separate value for the powerRampingStep for each random access preamble repetition level or the number of random access preamble repetitions using the table of FIG. 24, and the terminal 10 uses cell-specific or terminal-specific RRC signaling. Can be sent to. The terminal 10 may receive the parameter powerRampingStep defined by the base station 20 in step S2102, and calculate the PREAMBLE_RECEIVED_TARGET_POWER using this in step S2104.

Alternatively, the value of powerRampingStep received through higher layer signaling is determined without considering the random access preamble repetition level or the number of random access preamble repetitions, and when the parameter powerRampingStep is applied in Equation 2, the random access preamble repetition level or random access A normalized value may be applied as a function of the number of preamble repetitions. For example, the value of powerRampingStep received through higher layer signaling may be adjusted in inverse proportion to the random access preamble repetition level or the number of random access preamble repetitions.

As described above, in step S2104, PREAMBLE_RECEIVED_TARGET_POWER may be determined based on the random access preamble repetition level or the number of random access preamble repetitions, and thus the preamble transmit power P _{PRACH is} also based on the random access preamble repetition level or the random access preamble repetition number. Can be determined.

The terminal 10 transmits the random access preamble using the preamble transmit power P _PRACH determined in step S2104 (S2106).

Meanwhile, when the terminal 10 fails to transmit the preamble repetition level n-based random access preamble, that is, when the terminal 10 fails to receive the RAR after transmitting the preamble repetition level n-based random access preamble, the terminal 10 Repetition level ramping may be attempted first after power ramping, or power ramping may be attempted first after repetition level ramping. Here, power ramping means increasing power to the next level, and repetition level ramping means increasing the repetition level from n to n + 1.

25 is a flowchart illustrating an embodiment in which power ramping is attempted first and then repetitive level ramping is attempted.

Referring to FIG. 25 again, the terminal 10 transmits a random access preamble at a transmission power determined based on a preamble repetition level or a preamble repetition number (S2502).

The terminal 10 determines whether a RAR for the transmitted random access preamble is received (S2504).

When the RAR for the transmitted random access preamble is not received, that is, when the random access preamble transmission fails (NO in S2504), the terminal 10 sets a formula of PREAMBLE_RECEIVED_TARGET_POWER (for example, Equations 2, 9, or In step 10), power ramping is performed by increasing the value of PREAMBLE_TRANSMISSION_COUNTER by 1 (S2506). At this time, the value of PREAMBLE_RECEIVED_TARGET_POWER is increased as to increase by the value or values of the normalized (normalized) of powerRampingStep powerRampingStep, the random access preamble transmission power (P _PRACH) is a value or values of the normalized powerRampingStep of powerRampingStep.

The terminal 10 determines that the random access preamble transmit power P _PRACH determined in step S2506 is the maximum transmit power (

It is determined whether or not) (S2508). The determined random access preamble transmit power (P _PRACH ) is _equal to the maximum transmit power (

) Or less (YES in S2508), the terminal 10 retransmits the random access preamble using the random access preamble transmit power P _PRACH determined in step S2506 (S2502).

Greater than (NO in S2508), the UE 10 performs repetition level ramping by increasing the preamble repetition level to the next level (S2510), and transmits a random access preamble based on the increased preamble repetition level or the number of preamble repetitions. The power P _PRACH is determined (S2512). The terminal 10 retransmits the random access preamble using the random access preamble transmit power P _PRACH determined in step S2512 (S2502).

When the terminal 10 performs repetition level ramping, the terminal 10 may reset the value of the PREAMBLE_TRANSMISSION_COUNTER to an initial value of 1, thereby determining the random access preamble transmission power. Alternatively, the terminal 10 may determine the random access preamble transmission power while maintaining the value of PREAMBLE_TRANSMISSION_COUNTER. Alternatively, the terminal 10 may use the random access preamble transmission power as the current transmission power, that is, the maximum transmission power (

You can increase the repetition level only while

FIG. 26 is a diagram illustrating an example of a change in transmit power and the number of times of transmission of a random access preamble transmission in the example of FIG. 25.

Referring to FIG. 26, the terminal 10 initially transmits a random access preamble with a preamble repetition number of 4 at operation 2610. When the random access preamble transmission fails, the terminal 10 ramps up the transmission power of the random access preamble by performing power ramping (2620 and 2630). The transmit power of the random access preamble is equal to the maximum transmit power (

When the random access preamble transmission fails even though the RxHxHxHDHDHDHDH arrives, the UE 10 transmits the random access preamble by increasing the number of preamble repetitions by performing repetition level ramping (2640).

Although the preamble transmit power is shown as constant when repetitive level ramping is performed in FIG. 26, the present invention is not limited thereto. As another example, the terminal 10 may newly determine the transmission power of the random access preamble based on the changed number of preamble repetitions when performing repetition level ramping.

FIG. 27 is a flowchart illustrating an embodiment of attempting repetition level ramping first and then power ramping.

Referring to FIG. 27, the terminal 10 transmits a random access preamble at a transmission power determined based on a preamble repetition level or a preamble repetition number (S2702).

The terminal 10 determines whether a RAR for the transmitted random access preamble is received (S2704).

When the RAR for the transmitted random access preamble is not received, that is, when the random access preamble transmission fails (NO in S2704), the terminal 10 increases the preamble repetition level to the next level to perform repetition level ramping ( S2706).

When the terminal 10 performs repetition level ramping, the terminal 10 may maintain the random access preamble transmission power before the repetition level ramping is performed.

Alternatively, the terminal 10 may newly determine the random access preamble transmission power based on the preamble repetition level or the number of preamble repetitions changed through repetition level ramping. In this case, the terminal 10 may determine the random access preamble transmission power by resetting the value of PREAMBLE_TRANSMISSION_COUNTER to an initial value of 1, or determine the random access preamble transmission power while maintaining the value of PREAMBLE_TRANSMISSION_COUNTER.

The terminal 10 determines whether the preamble repetition level is equal to or less than the maximum repetition level N (S2708). If the preamble repetition level is less than or equal to the maximum repetition level N (YES in S2708), the terminal 10 transmits the random access preamble again (S2702).

If the preamble repetition level is greater than the maximum repetition level N (NO in S2708), the terminal 10 ramps the power by increasing the value of PREAMBLE_TRANSMISSION_COUNTER by 1 in the setting formula of PREAMBLE_RECEIVED_TARGET_POWER (for example, Equation 2, 9, or 10). It performs (S2710). The terminal 10 transmits the random access preamble again at the changed preamble transmission power (S2702).

When the terminal 10 performs power ramping, the terminal 10 may maintain the preamble repetition level at a current value, that is, the maximum repetition level N. FIG. At this time, the value of PREAMBLE_RECEIVED_TARGET_POWER is increased by the value or values of the normalized powerRampingStep of powerRampingStep, the random access preamble transmission power (P _PRACH) can be increased by a value or values of the normalized powerRampingStep of powerRampingStep.

Alternatively, the terminal 10 may reset the preamble repetition level to an initial value. In this case, the terminal 10 may determine the preamble transmission power based on the reset preamble repetition level and the increased value of PREAMBLE_TRANSMISSION_COUNTER.

In the example of FIG. 28, when the repetition level of the random access preamble is n, the repetition number M _n = 2 ⁽ⁿ⁻¹⁾ of the random access preamble is determined, and the maximum repetition level is assumed to be 4. The terminal 10 initially transmits the random access preamble with the preamble repetition level of 1 (the number of preamble repetitions 1) (2810). When the random access preamble transmission fails, the terminal 10 performs repetition level ramping to incrementally increase the preamble repetition level (2820, 2830, and 2840). When the random access preamble transmission fails even when the preamble repetition level reaches the maximum repetition level 4 (the number of preamble repetitions 8), the terminal 10 performs power ramping to increase the transmit power of the random access preamble to transmit the random access preamble. (2850).

Although the preamble transmit power is shown as constant when repetitive level ramping is performed in FIG. 28, the present invention is not limited thereto. As another example, the terminal 10 may newly determine the transmission power of the random access preamble based on the changed number of preamble repetitions when performing repetition level ramping.

Referring to FIG. 29, the terminal 2900 includes a controller 2910, a transmitter 2920, and a receiver 2930.

The controller 2910 controls the overall operation of the terminal 2900. The controller 2910 may control overall operations for performing the embodiments of the present invention.

The transmitter 2920 and the receiver 2930 may transmit and receive signals, messages, or data necessary for carrying out the embodiments of the present invention.

The receiver 2930 may receive PRACH configuration information from the base station through higher layer signaling. The PRACH configuration information may include parameters preambleInitialReceivedTargetPower and powerRampingStep .

The controller 2910 may determine the repetitive transmission level or the number of random access preambles. In addition, the controller 2910 may determine the transmit power of the random access preamble based on the determined repetitive transmission level or the number of random access preambles.

For example, the formula for calculating the transmission power of the random access preamble includes the repetitive transmission level or number of random access preambles as one parameter, or a value determined based on the repetitive transmission level or number of random access preambles as one parameter. It may include.

Alternatively, the PRACH configuration information includes a parameter determined by the base station based on the repetitive transmission level or number of random access preambles, and the controller 2910 uses the parameter determined based on the repetitive transmission level or number of random access preambles. The transmit power of the random access preamble may be determined. Parameters determined by the base station based on the repetitive transmission level or the number of random access preambles may be parameters preambleInitialReceivedTargetPower and powerRampingStep or may be new parameters (eg, DELTA_PREAMBLE_REPETITION).

Alternatively, the parameter included in the PRACH configuration information is normalized according to the repetitive transmission level or the number of times, and the controller 2910 may determine the transmission power of the random access preamble using the normalized parameter.

Meanwhile, when the random access preamble transmission fails, that is, when the RAR reception fails after the random access preamble transmission, the control unit 2910 first attempts power ramping and then attempts repetitive level ramping or power ramping after repetitive level ramping. You can try

In the case of preferentially attempting power ramping, the controller 2910 first obtains the maximum transmit power (

Attempts random access preamble transmission by gradually increasing the random access preamble transmission power until), and attempts random access preamble transmission by gradually increasing the preamble repetition level when the random access preamble transmission fails even at the maximum transmission power. Can be.

In the case of preferentially attempting repetition level ramping, the control unit 2910 first attempts to transmit a random access preamble by gradually increasing the preamble repetition level until the maximum repetition level N is reached, and when the preamble transmission fails even at the maximum repetition level, Random access preamble transmission may be attempted while increasing the random access preamble transmission power step by step.

The transmitter 2920 may transmit the random access preamble with the random access preamble transmission power determined by the controller 2910, and the receiver 2930 may receive a random access response (RAR) for the random access preamble from the base station.

Referring to FIG. 30, the base station 3000 includes a controller 3010, a transmitter 3020, and a receiver 3030.

The controller 3010 controls the overall operation of the base station 3000. The controller 3010 may control the overall operation for performing the embodiments of the present invention.

The transmitter 3020 and the receiver 3030 may transmit and receive signals, messages, or data necessary for carrying out the embodiments of the present invention.

The transmitter 3020 may transmit PRACH configuration information to the terminal through higher layer signaling. The PRACH configuration information may include parameters preambleInitialReceivedTargetPower and powerRampingStep .

In some embodiments of the present disclosure, the controller 3010 may determine at least one of parameters included in the PRACH configuration information based on the repetitive transmission level or the number of repetitive transmission levels of the random access preamble in the terminal. The parameter determined by the controller 3010 based on the repetitive transmission level or the number of random access preambles may be the parameters preambleInitialReceivedTargetPower and powerRampingStep or may be a new parameter (eg, DELTA_PREAMBLE_REPETITION). This parameter may be used when the terminal determines the random access preamble transmit power.

The receiver 3030 may receive a random access preamble from the terminal, and the transmitter 3020 may transmit a random access response (RAR) for the random access preamble to the terminal.

The above description is merely illustrative of the technical idea of the present invention, and those skilled in the art to which the present invention pertains may make various modifications and changes without departing from the essential characteristics of the present invention. Therefore, the embodiments disclosed in the present invention are not intended to limit the technical spirit of the present invention but to describe the present invention, and the scope of the technical idea of the present invention is not limited by these embodiments. The protection scope of the present invention should be interpreted by the following claims, and all technical ideas within the equivalent scope should be interpreted as being included in the scope of the present invention.

CROSS-REFERENCE TO RELATED APPLICATIONCROSS-REFERENCE TO RELATED APPLICATION

This patent application is filed with a patent application No. 10-2013-0122198 filed in Korea on October 14, 2013 and a patent application No. 10-2013-0122407 filed in Korea on October 15, 2013 and October 2013 Korean Patent Application No. 10-2013-0131555 filed with Korea on 31st and Korean Patent Application No. 10-2014-0068628 filed with Korea on 06.05.2014 and Korean patent application filed with Korea on July 15, 2014 Claims No. 10-2014-0088926 are issued pursuant to United States Patent Act Section 119 (a) (35 USC § 119 (a)), all of which is incorporated herein by reference. In addition, if this patent application claims priority for the same reason for countries other than the United States, all its contents are incorporated into this patent application by reference.

Claims

As a method for the terminal to perform random access,

Determining the preamble repetition level from the random access preamble by at least one variable or coverage level of the variables that determine the transmit power of the random access preamble;

Transmitting the random access preamble repeatedly to a base station through a specific number of subframes corresponding to the determined preamble repetition level; And

Receiving from the base station a random access response related to the random access preamble,

Transmitting the random access preamble to the base station when the random access response is not received from the base station.
The method of claim 1,

The preamble repetition level is a downlink path loss value (
Characterized in that it is determined by).
The method of claim 1,

The preamble repetition level is the maximum transmit power of the terminal (
), Downlink path loss value (
), preambleInitialReceivedTargetPower , DELTA_PREAMBLE.
The method of claim 1,

The coverage level is determined by the number of repetitions of the downlink physical channel or is configured by the terminal-specific higher layer signaling.
The method of claim 1,

If the random access response is not received from a base station, the step of transmitting the random access preamble to the base station is repeated.

Changing the preamble repetition level and repeatedly transmitting the random access preamble to the base station.
The method of claim 1,

If the random access response is not received from a base station, the step of transmitting the random access preamble to the base station is repeated.

Increasing the preamble repetition level by 1 and repeatedly transmitting the random access preamble to the base station.
The method of claim 1,

If the random access response is not received from a base station, the step of transmitting the random access preamble to the base station is repeated.

Achieving a certain condition while ramping the transmit power each time by repeating the M n of the random access preamble to be transmitted to the base station corresponding to the preamble repetition level n (n is a natural number larger than 1) the increasing the preamble repetition level And repeatedly transmitting a random access preamble to the base station.
The method of claim 7, wherein

The specific condition is to increase the PREAMBLE_TRANSMISSION_COUNTER used to determine the transmit power of the random access preamble by 1 so that the PREAMBLE_TRANSMISSION_COUNTER reaches a threshold or the transmit power for each random access preamble transmission is increased.
When it is reached.
A terminal for performing random access,

A transmitter for repeatedly transmitting a random access preamble to a base station through a specific number of subframes corresponding to a preamble repetition level determined according to at least one variable or a coverage level among variables that determine a transmission power of the random access preamble; And

A receiving unit which receives a random access response related to the random access preamble from the base station,

And when the receiver does not receive the random access response from the base station, the transmitter repeats the process of transmitting the random access preamble to the base station.
A method of transmitting a random access preamble by a terminal through a physical random access channel (PRACH),

Determining the number of times the PRACH is repeatedly transmitted when repeatedly transmitting the PRACH through a plurality of uplink subframes, and determining the transmission power of the PRACH based on the number of times the PRACH is repeatedly transmitted; And

And repeatedly transmitting the PRACH at the determined transmit power of the PRACH.
The method of claim 10,

When the repetitive transmission of the PRACH fails, increasing the transmit power of the PRACH;

If the transmit power of the increased PRACH is less than or equal to the maximum transmit power, repeatedly transmitting the PRACH at the transmit power of the increased PRACH; And

If the increased transmit power of the PRACH is greater than the maximum transmit power, increasing the number of times the PRACH is repeatedly transmitted and repeatedly transmitting the PRACH.
The method of claim 10,

When the transmission of the PRACH fails, increasing the number of times the PRACH is repeatedly transmitted;

If the number of times the increased PRACH is repeatedly transmitted is less than or equal to the maximum value, repeatedly transmitting the PRACH the number of times the increased PRACH is repeatedly transmitted; And

If the number of times the increased PRACH is repeatedly transmitted is greater than the maximum value, increasing the transmit power of the PRACH and repeatedly transmitting the PRACH.
The method of claim 10,

Determining the transmission power of the PRACH is to determine the transmission power of the PRACH using the following equation (1),

(1) P PRACH = min {
, PREAMBLE_RECEIVED_TARGET_POWER +
10 logM n } _ [dBm]

In Equation (1), P PRACH is the transmit power of the PRACH,
Is the maximum transmit power, PREAMBLE_RECEIVED_TARGET_POWER is the target preamble receive power,
Is a downlink path loss, and M n is a number of times the PRACH is repeatedly transmitted.
The method of claim 10,

Determining the transmission power of the PRACH is to determine the transmission power of the PRACH using the following equation (2),

(2) P PRACH = min {
, PREAMBLE_RECEIVED_TARGET_POWER +
} _ [dBm]

In Equation (2), P PRACH is the transmit power of the PRACH,
Is the maximum transmit power,
Is a downlink path loss, PREAMBLE_RECEIVED_TARGET_POWER is determined using Equation (3) below,

(3) PREAMBLE_RECEIVED_TARGET_POWER = preambleInitialReceivedTargetPower + DELTA_PREAMBLE + DELTA_PREAMBLE_REPETITION + (PREAMBLE_TRANSMISSION_COUNTER-1) * powerRampingStep

In Equation (3), preambleInitialReceivedTargetPower and powerRampingStep are values received by higher layer signaling, DELTA_PREAMBLE is a value determined according to a format of a random access preamble, and DELTA_PREAMBLE_REPETITION is determined based on the number of times the PRACH is repeatedly transmitted. Value, and PREAMBLE_TRANSMISSION_COUNTER is the number of attempts to transmit the PRACH.
The method of claim 10,

Determining the transmission power of the PRACH is to determine the transmission power of the PRACH using the following equation (4),

(4) P PRACH = min {
, PREAMBLE_RECEIVED_TARGET_POWER +
} _ [dBm]

In Equation (4), P PRACH is the transmit power of the PRACH,
Is the maximum transmit power,
Is a downlink path loss, PREAMBLE_RECEIVED_TARGET_POWER is determined using Equation (5) below,

(5) PREAMBLE_RECEIVED_TARGET_POWER = preambleInitialReceivedTargetPower + DELTA_PREAMBLE + (PREAMBLE_TRANSMISSION_COUNTER-1) * powerRampingStep

In Equation (5), preambleInitialReceivedTargetPower and powerRampingStep are values received by higher layer signaling, DELTA_PREAMBLE is a value determined according to a format of a random access preamble, PREAMBLE_TRANSMISSION_COUNTER is the number of times the PRACH is attempted to be transmitted, and the preambleInitialReceivedTargetTargetTar Is determined based on the number of times the PRACH is repeatedly transmitted.
The method of claim 10,

Determining the transmission power of the PRACH is to determine the transmission power of the PRACH using the following equation (6),

(6) P PRACH = min {
, PREAMBLE_RECEIVED_TARGET_POWER +
} _ [dBm]

In Equation (6), P PRACH is the transmit power of the PRACH,
Is the maximum transmit power,
Is a downlink path loss, PREAMBLE_RECEIVED_TARGET_POWER is determined using Equation (7) below,

(7) PREAMBLE_RECEIVED_TARGET_POWER = preambleInitialReceivedTargetPower + DELTA_PREAMBLE + (PREAMBLE_TRANSMISSION_COUNTER-1) * powerRampingStep

In Equation (5), preambleInitialReceivedTargetPower and powerRampingStep are values received by higher layer signaling, DELTA_PREAMBLE is a value determined according to a format of a random access preamble, PREAMBLE_TRANSMISSION_COUNTER is the number of times the PRACH is attempted to be transmitted, and the powerRampingStep is the value Wherein the PRACH is adjusted based on the number of times the PRACH is repeatedly transmitted at the terminal or determined based on the number of times the PRACH is repeatedly transmitted at the base station.
A method of transmitting, by a base station, configuration information on transmission power of a physical random access channel (PRACH) to a terminal,

Determining, by the terminal, configuration information on transmit power of the PRACH based on the number of times the PRACH is repeatedly transmitted; And

Transmitting configuration information on the transmit power of the PRACH to the terminal through higher layer signaling.
The method of claim 17,

The transmission power of the PRACH in the terminal is determined using Equation (8) below,

(8) P PRACH = min {
, PREAMBLE_RECEIVED_TARGET_POWER +
} _ [dBm]

In Equation (8), P PRACH is the transmit power of the PRACH,
Is the maximum transmit power,
Is a downlink path loss, PREAMBLE_RECEIVED_TARGET_POWER is determined using Equation (9) below,

(9) PREAMBLE_RECEIVED_TARGET_POWER = preambleInitialReceivedTargetPower + DELTA_PREAMBLE + (PREAMBLE_TRANSMISSION_COUNTER-1) * powerRampingStep

In Equation (9), preambleInitialReceivedTargetPower and powerRampingStep are values transmitted by higher layer signaling, DELTA_PREAMBLE is a value determined according to a format of a random access preamble, and PREAMBLE_TRANSMISSION_COUNTER is a number of times the UE attempts to transmit the PRACH,

And the setting information on the transmit power of the PRACH determined based on the number of times the PRACH is repeatedly transmitted is preambleInitialReceivedTargetPower .
A terminal for transmitting a random access preamble through a physical random access channel (PRACH),

A controller configured to determine the number of times the PRACH is repeatedly transmitted when repeatedly transmitting the PRACH through a plurality of uplink subframes, and to determine the transmission power of the PRACH based on the number of times the PRACH is repeatedly transmitted; And

And a transmitter for repeatedly transmitting the PRACH at the determined transmission power of the PRACH.
A base station for transmitting configuration information on a transmission power of a physical random access channel (PRACH) to a terminal,

A control unit which determines setting information on transmission power of the PRACH based on the number of times the PRACH is repeatedly transmitted in the terminal; And

And a transmitter for transmitting configuration information on the transmit power of the PRACH to the terminal through higher layer signaling.