KR102031433B1 - Method for performing random access in wireless communication network, terminal and base station for performing random access - Google Patents

Abstract

The present invention relates to a method for performing random access, which can reduce performance reduction of a random access channel due to congestion when terminals establish connection with a base station for data transmission in a wireless mobile communication network.
According to an aspect of the present invention, there is provided a method of performing random access, comprising: transmitting, by a terminal, a first message including a preamble to a base station; Receiving, by the terminal, a second message including a random access response corresponding to the first message from the base station, wherein the second message includes a temporary identifier; Transmitting, by the terminal, a third message including a connection request to the base station; And receiving, by the terminal, a fourth message including a connection resolution corresponding to the third message from the base station, wherein the transmitting of the third message comprises: retransmitting the third message by the terminal. Determining a transmit power based on the method.

Description

Method of performing random access of wireless mobile communication network, terminal and base station performing the random access TECHNICAL FIELD

The present invention relates to a method for performing random access of a wireless mobile communication network, a terminal and a base station. More particularly, the present invention relates to congestion when terminals are connected to a base station for data transmission in a wireless mobile communication network. The present invention relates to a method for performing random access, a terminal, and a base station that can reduce a performance reduction of a random access channel.

As the demand for Internet of Things (IoT) services has increased, it has become important to support them in wireless mobile networks. IoT communication has different characteristics from existing human-to-human communication. Random access channel in that the number of IoT terminals in the cell is very large, the terminals mainly perform small data transmission, mainly the Uplink-oriented communication, and connect only when there is data to be sent to reduce energy consumption. The congestion problem in (RACH) became an urgent problem to solve. Related patents are disclosed in Korean Patent Publication No. 10-2017-0049273.

Therefore, there is a need for a technique for reducing a performance reduction of a random access channel due to congestion when establishing a connection between a terminal and a base station.

Disclosure of Invention An object of the present invention is a method of performing random access in a wireless mobile communication network capable of reducing the performance reduction of a random access channel due to congestion when establishing a connection of a base station in a wireless mobile communication network, a terminal and a base station performing the random access To provide.

According to an embodiment of the present invention to achieve the above object, a method for performing a random access of a wireless mobile communication network, the method comprising the steps of: transmitting a first message including a preamble (preamble) by the terminal to the base station; Receiving, by the terminal, a second message including a random access response corresponding to the first message from the base station, wherein the second message includes a temporary identifier; Transmitting, by the terminal, a third message including a connection request to the base station; And receiving, by the terminal, a fourth message including a connection resolution corresponding to the third message from the base station, wherein the transmitting of the third message comprises: retransmitting the third message by the terminal. Disclosed is a method of performing random access, the method comprising determining transmission power based on.

According to an embodiment of the present invention to achieve the above object, a method for performing a random access of a wireless mobile communication network, the base station receiving a first message including a preamble (preamble) from the terminal; Transmitting, by the base station, a second message including a random access response corresponding to the first message to the terminal, wherein the second message includes a temporary identifier; Receiving, by the base station, a third message including a connection request from the terminal; And transmitting, by the base station, a fourth message including a connection resolution corresponding to the third message to the terminal, wherein the transmitting of the fourth message comprises: transmitting the fourth message to the terminal; Selecting a terminal to transmit the fourth message based on a capture probability from the random message, wherein the capture probability is calculated using a transmission power of the terminal at the time of transmitting the third message. A method of performing access is disclosed.

According to an embodiment of the present invention to achieve the above object, in a terminal performing random access of a wireless mobile communication network, a base station preamble (preamble) and connection request (connection request) message for performing the random access to a base station A transmission unit for transmitting; A receiver configured to receive a random access response corresponding to the preamble message and a connection resolution message for the connection request from the base station, wherein the random access response message includes a temporary identifier; A transmission power determination unit to determine a transmission power based on the number of times of reconnection of the connection request message; And a control unit for controlling the transmission unit, the reception unit, and the transmission power determination unit.

According to an embodiment of the present invention to achieve the above object, a base station for performing a random access of a wireless mobile communication network, comprising: a receiving unit for receiving a preamble and a connection request message from the terminal; A transmitter configured to transmit a random access response message corresponding to the preamble message and a connection resolution message corresponding to the connection request message to the terminal, wherein the random access response message includes a temporary identifier; A terminal capturing unit for selecting a terminal to transmit the connection resolution message based on the capture probability among a plurality of terminals staying in the network-The capture probability is calculated by using the reception power of the base station when the connection request message is received. -; And a control unit for controlling the receiving unit, the transmitting unit, and the terminal capturing unit.

Random access of a wireless mobile communication network according to an embodiment of the present invention, the terminal and the base station performing the random access performance of the random access channel (random access channel) due to congestion when establishing a connection of the base station in the wireless mobile communication network The reduction can be reduced.

1 is a flowchart illustrating a method of performing random access of a wireless mobile communication network according to an embodiment of the present invention.
2 is a block diagram of a terminal shown in FIG. 1.
3 is a block diagram of a base station shown in FIG. 1.
FIG. 4 is a diagram illustrating a process of selecting a terminal by using a power capture effect by a base station performing random access of a wireless mobile communication network according to an embodiment of the present invention.
5 is a graph comparing performance of a method of performing random access of a wireless mobile communication network and another method according to an embodiment of the present invention.

Hereinafter, a method for performing random access of a wireless mobile communication network according to an embodiment of the present invention, a terminal and a base station performing the random access will be described with reference to the drawings.

As used herein, the singular forms "a", "an" and "the" include plural forms unless the context clearly indicates otherwise. In this specification, terms such as “consisting of” or “comprising” should not be construed as necessarily including all of the various components or steps described in the specification, and some of the components or some steps It should be construed that it may not be included or may further include additional components or steps.

In a wireless mobile communication network, a terminal must establish a connection with a network in order to transmit data. In order to establish a connection to the network, the terminal transmits a random access signal to the base station, and the base station transmits a random access response message to the terminal.

In the following embodiment, a method of performing random access for IoT terminals to establish a connection with an eNB for data transmission will be described.

1 is a flowchart illustrating a method of performing random access of a wireless mobile communication network according to an embodiment of the present invention, FIG. 2 is a block diagram of a terminal shown in FIG. 1, and FIG. 3 is a diagram of a base station shown in FIG. It is a block diagram.

As shown, the wireless mobile communication system may include a terminal 100 and a base station 200.

The terminal 100 may include a transmitter 110, a receiver 220, a transmit power determiner 130, and a controller 140.

In addition, the base station 200 may include a receiver 210, a transmitter 220, a terminal capture unit 230, and a controller 240.

The terminal 100 to establish a connection transmits a first message Msg1 including a preamble to the base station 200 through a predetermined random access channel (RACH channel) (S110). That is, the transmitter 110 transmits the first message through a randomly selected random access channel. In this case, since the first message Msg1 is randomly selected and transmitted in a preamble pool, when a large number of terminals try to access at the same time, a plurality of terminals may select and transmit the same preamble. This may be defined as a first message (Msg1) congestion (collision). The base station 200 does not detect this congestion phenomenon when receiving Msg1 due to the nature of the preamble. That is, when the reception unit 210 receives the first message, even if congestion occurs in the first message, the congestion phenomenon of the first message of the base station cannot be found.

Meanwhile, the terminal 100 may determine the transmission power by a power control technique when transmitting the first message. The transmission power determiner 130 may determine the transmission power at the time of transmitting the first message according to Equation 1 below.

는 단말(100)이 RACH를 통하여 제1메시지를 전송할 때의 전송 파워이며,

[dBm]는 단말의 최대 전송 파워; PL　[dB]는 path-loss 값, 그리고 PRTP　[dBm] 는 preamble received target power로 타겟파워이다. PRTP의 경우는 하기 수학식 2와 같이 표현될 수 있다.

Is the transmission power when the terminal 100 transmits the first message through the RACH,

[dBm] is the maximum transmit power of the terminal; PL [dB] is the path-loss value, and PRTP [dBm] is the target power with preamble received target power. In the case of PRTP, it may be expressed as Equation 2 below.

는 power initial received target 으로 일종의 타겟 파워,

는 오프셋 값, 그리고 PRS는 power ramping step이며, r은 단말의 ramping number이다.

Is power initial received target, which is a kind of target power,

Is an offset value, and PRS is a power ramping step, and r is a ramping number of the terminal.

에 도달할 때까지 power ramping을 하게 된다.The use of the power control technique for the first message Msg1 is to prevent the base station 200 from detecting it due to too low power. The power control technique increases the transmit power by PRS as the number of retransmissions increases. In other words, the value of r basically follows the number of retransmissions and the total value is

Power ramping is achieved until

When the receiver 210 of the base station 200 receives the first message Msg1, the transmitter 220 of the base station 200 includes a second including a random access response with respect to the corresponding preamble. The message Msg2 is transmitted to the terminal 100 (S120). The second message is transmitted through a physical down control channel (PDCCH). The second message may include a temporary identifier of the wireless network and an uplink grant for the next message.

When transmitting the first message, the mobile station sets a RAR window and receives a second message for the corresponding preamble within the window, and transmits a third message (Msg3) including a connection request according to a predetermined uplink grant. S200 is transmitted to (S130).

The third message Msg3 is transmitted through a physical uplink shared channel (PUSCH). In the past, since the IoT terminals selecting the same preamble transmit the same uplink grant, in the case of the third message Msg3, congestion occurs again in the PUSCH. Due to such congestion, the base station cannot decode the Msg3, and all of the terminals selected for the preamble fail in the random access process.

However, according to an embodiment of the present invention, even when transmitting the third message, the terminal 100 determines the transmission power according to a power control strategy (power ramping technique). The transmission power determiner 130 may determine the transmission power at the time of transmitting the third message according to Equation 3 below.

Where P _msg3 is the transmission power when transmitting a third message, P _cmax is the maximum transmission power, and, P _target is the target power and, PL is a path-loss value at the time to transmit a third message of the terminal, r is ramping number, and PRS is the power ramping step.

In the case of a wireless signal, even if a collision occurs, the base station 200 may interpret one signal when there is a difference in reception power. This is called a power capture effect.

FIG. 4 is a diagram illustrating a process of selecting a terminal by using a power capture effect by a base station performing random access of a wireless mobile communication network according to an embodiment of the present invention.

As shown, when there is a difference in reception power when receiving a third message from the plurality of terminals 100, T2, and T3, the base station 200 selects any one terminal 100 and the corresponding terminal 100. ) Can be interpreted.

The selected terminal 100 may be a terminal having a high capture probability. The capture probability may be expressed as Equation 4 below.

는 단말 i가 capture될 확률이며, P_i는 단말 i의 기지국에서의 수신 파워, β는 capture threshold이다.At this time,

Is the probability that terminal i is captured, P _i is the reception power at the base station of terminal i, and β is the capture threshold.

The terminal capture unit 230 of the base station may select the terminal having the largest capture probability calculated according to Equation 4 below. That is, the probability of selecting a terminal that has stayed in the network for a long time (a lot of retransmissions) becomes higher. By selecting one of the terminals using the power capture effect, the reception rate of the third message can be increased despite the first message (Msg1) congestion, thereby increasing the efficiency of the PUSCH. In addition, in the case of the terminal also increases the connection setup probability.

The transmitter 220 of the base station 200 may transmit a fourth message Msg4 including a connection resolution corresponding to the connection request to the selected terminal 100 (S140). When the steps S110 to S140 are completed, the random access process ends, and in this case, the terminal 100 succeeds in establishing a connection with the base station 200.

5 is a graph comparing performance of a method of performing random access of a wireless mobile communication network and another method according to an embodiment of the present invention.

5 shows the superiority of the third message Msg3 power ramping according to an embodiment of the present invention. Referring to (a-c), the difference between when the power ramping technique and the power capture effect are applied when the third message is transmitted according to an embodiment of the present invention and when it is not applied. For each result, the analysis of the results when the size of PRS is changed is also included.

Looking at it, it can be seen that the performance is greatly increased in terms of channel throughput and connection failure probability of the UE when using the scheme proposed in the embodiment of the present invention. If PRS is specified as 3db, the best performance is obtained. In this case, throughput can be expected to be improved to about 105%. In the case of connection failure probability, a performance improvement of about 42% can be expected compared to when the proposed technique according to an embodiment of the present invention is not used. Although looking at (c), the average energy consumption increases by about 13%, but it can be expected that a large performance improvement in terms of channel throughput and connection failure probability in comparison to the energy used. Looking at (d), we show the performance improvement when using the existing access control method, access class barring, and the proposed method.

As described above, a method of performing random access of a wireless mobile communication network according to an embodiment of the present invention according to an embodiment of the present invention, the terminal and the base station performing the random access when setting up a connection of a base station in a wireless mobile communication network Performance reduction of a random access channel due to congestion can be reduced.

The above-described method for performing random access of a wireless mobile communication network may be implemented in the form of program instructions that can be executed by various computer means and recorded in a computer-readable recording medium. In this case, the computer-readable recording medium may include program instructions, data files, data structures, and the like, alone or in combination. Meanwhile, the program instructions recorded on the recording medium may be those specially designed and configured for the present invention, or may be known and available to those skilled in computer software.

Computer-readable recording media include magnetic media such as hard disks, floppy disks, and magnetic tape, optical media such as CD-ROMs, DVDs, and magnetic disks such as floppy disks. Magnetic-Optical Media, and hardware devices specifically configured to store and execute program instructions, such as ROM, RAM, flash memory, and the like.

The recording medium may be a transmission medium such as an optical or metal wire, a waveguide, or the like including a carrier wave for transmitting a signal specifying a program command, a data structure, or the like.

In addition, program instructions include not only machine code generated by a compiler, but also high-level language code that can be executed by a computer using an interpreter or the like. The hardware device described above may be configured to operate as one or more software modules to perform the operations of the present invention, and vice versa.

The method for performing random access of the wireless mobile communication network described above, the terminal and the base station performing the random access may not be limitedly applied to the configuration and method of the above-described embodiments, and the embodiments may be modified in various ways. All or some of the embodiments may be selectively combined in order to accomplish this.

100: terminal
110: transmission unit
120: receiver
130: transmission power determining unit
140: control unit
200: base station
210: receiver
220: transmission unit
230: terminal capture unit
240: control unit

Claims (16)

In the method for performing random access of a wireless mobile communication network,
Transmitting, by the terminal, a first message including a preamble to the base station;
Receiving, by the terminal, a second message including a random access response corresponding to the first message from the base station, wherein the second message includes a temporary identifier;
Transmitting, by the terminal, a third message including a connection request to the base station; And
Receiving, by the terminal, a fourth message including a connection resolution corresponding to the third message from the base station,
The third message transmitting step includes determining, by the terminal, transmission power based on the number of times of retransmitting the third message.
The terminal receiving the fourth message is a terminal having a high probability of capturing from the base station among a plurality of terminals staying in the network.
The capture probability is calculated using the received power at the base station for the third message.
The method of claim 1, wherein the transmission power determined in the transmission power determination step is
The random access method according to the following equation (1).
[Equation 1]

(Where P _msg3 is the transmission power when transmitting a third message, P _cmax is the maximum transmission power, and, P _target is the target power and, PL is a path-loss value at the time to transmit a third message of the terminal, r is ramping number, and PRS is the power ramping step.)
delete The method of claim 1,
The capture probability is represented by the following equation (2).
[Equation 2]

(At this time,

Is the probability that terminal i is captured, P _i is the reception power at the base station of terminal i, and β is the capture threshold.)
In the method for performing random access of a wireless mobile communication network,
Receiving, by the base station, a first message including a preamble from the terminal;
Transmitting, by the base station, a second message including a random access response corresponding to the first message to the terminal, wherein the second message includes a temporary identifier;
Receiving, by the base station, a third message including a connection request from the terminal; And
And transmitting, by the base station, a fourth message including a connection resolution corresponding to the third message to the terminal.
The transmitting of the fourth message may include selecting a terminal to transmit the fourth message based on a capture probability from the base station among a plurality of terminals staying in the network.
The capture probability is calculated using the received power at the base station for the third message.
The method of claim 5,
The capture probability is represented by the following equation (1).
[Equation 1]

(At this time,

Is the probability that terminal i is captured, P _i is the reception power at the base station of terminal i, and β is the capture threshold.)
The method of claim 5,
The terminal determines a transmission power based on the number of times the third message retransmission.
The method of claim 7, wherein the terminal is
The method of claim 1, wherein the transmission power is determined according to Equation 2.
[Equation 2]

(Where P _msg3 is the transmission power when transmitting a third message, P _cmax is the maximum transmission power, and, P _target is the target power and, PL is a path-loss value at the time to transmit a third message of the terminal, r is ramping number, and PRS is the power ramping step.)
A terminal for performing random access of a wireless mobile communication network,
A transmitter for transmitting a preamble and a connection request message for performing the random access to a base station;
A receiving unit for receiving a random access response corresponding to the preamble message and a connection resolution message for the connection request from the base station, wherein the random access response message includes a temporary identifier;
A transmission power determination unit to determine a transmission power based on the number of times of reconnection of the connection request message; And
A control unit for controlling the transmission unit, the receiving unit and the transmission power determiner,
The terminal receiving the connection resolution message is a terminal having a high probability of capture from the base station among a plurality of terminals staying in the network.
The capturing probability is calculated using the received power at the base station for the connection request message.
The method of claim 9, wherein the transmission power determiner
The transmission power is determined according to Equation 1 below.
[Equation 1]

(Where P _msg3 is the transmission power when transmitting the connection request message, P _cmax is the maximum transmission power, and, P _target is the target power when transmitting the connection request message, PL is a path-loss value of the terminal, r Is the ramping number and PRS is the power ramping step.)
delete The method of claim 9,
The capture probability is a terminal characterized in that represented by the following equation (2).
[Equation 2]

(At this time,

Is the probability that terminal i is captured, P _i is the reception power at the base station of terminal i, and β is the capture threshold.)
A base station performing random access of a wireless mobile communication network,
A receiver configured to receive a preamble and a connection request message from the terminal;
A transmitter configured to transmit a random access response message corresponding to the preamble message and a connection resolution message corresponding to the connection request message to the terminal, wherein the random access response message includes a temporary identifier;
A terminal capture unit for selecting a terminal to transmit the connection resolution message based on a capture probability among a plurality of terminals staying in a network, wherein the capture probability is calculated by using a reception power of a base station upon receiving the connection request message; ; And
And a control unit for controlling the receiver, the transmitter, and the terminal capture unit.
The method of claim 13,
The capture probability is represented by Equation 1 below.
[Equation 1]

(At this time,

Is the probability that terminal i is captured, P _i is the reception power at the base station of terminal i, and β is the capture threshold.)
The method of claim 13,
And the terminal determines transmission power based on the number of times of reconnection of the connection request message.
The method of claim 15, wherein the terminal
The base station, characterized in that for determining the transmission power according to the following equation (2).
[Equation 2]

(Where P _msg3 is the transmission power when transmitting the connection request message, P _cmax is the target power when the maximum transmission power of the terminal and, P _target is to send the connection request message, and PL is path-loss value, r is ramping number, and PRS is the power ramping step.)

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