KR102034105B1 - Methods for controlling packet retransmission of end device for wireless network using Pure ALOHA and Apparatuses thereof - Google Patents

Abstract

를 측정하는 채널 유휴 시간 측정 단계, k번째 에포크의 백오프 계수

를 계산하기 위한 랜덤 샘플 집합

를 갱신하는 랜덤 샘플 집합 갱신 단계,

,

및 (k-1)번째 에포크에 대한 백오프 계수

을 기초로 k번째 에포크의 백오프 계수

를 계산하는 백오프 계수 계산 단계 및

값을 복수의 단말에 브로드캐스팅하는 브로드캐스트 단계를 포함하는 것을 특징으로 하는 방법을 제공한다.The present embodiment relates to a method and an apparatus for controlling packet retransmission of a terminal in a wireless network using Pure ALOHA, and an embodiment is a method for controlling packet retransmission of a terminal in a wireless network using Pure ALOHA protocol. The channel idle time for the k th epoch

Channel idle time measurement step to measure the backoff coefficient of the k-th epoch

Set of random samples to compute

Random sample set updating step of updating,

,

And the backoff coefficient for the (k-1) th epoch

The backoff coefficient of the k-th epoch based on

Calculating a backoff coefficient and calculating

It provides a method comprising the step of broadcasting a value to a plurality of terminals.

Description

Method for controlling packet retransmission of end device for wireless network using Pure ALOHA and Apparatuses about

Embodiments of the present invention set an optimal backoff coefficient used by an access point (AP) for packet retransmission of a terminal in a wireless network using pure ALOHA, thereby increasing throughput and backlog size of the wireless network. A method and apparatus for reducing the

In the next generation of wireless communication, the importance of the Internet of Things (IoT), which connects the Internet by embedding sensors and communication functions in various objects, is emphasized. The IoT-related technologies include LoRaWAN along with 3GPP's narrow-band (NB) IoT.

LoRaWAN is a technology related to Low Power Wide Area Network (LPWAN) for battery-powered wireless devices (eg sensors, terminals, etc.) connected to a network and uses the Pure ALOHA protocol.

Pure ALOHA is a multiple access control protocol in which each device on the network does not synchronize with each other and does not listen to the communication channel before sending packets. Therefore, collision or transmission failure may occur while each device sends a packet through the same channel.

As a method of retransmitting a packet by a UE using a pure ALOHA protocol, there are largely an intermediate first transmission (IFT) and a delayed first transmission (DFT) scheme. In the case of using the IFT method, the UE transmits the packet immediately when there is a packet to be retransmitted, whereas in the case of using the DFT method, the UE recognizes a collision or transmission failure and then, after the random backoff time interval, Will be resent. Accordingly, in the Pure ALOHA protocol using the DFT scheme, throughput and backlog size of a wireless network may vary greatly depending on a method of controlling a backoff time interval for packet retransmission for a terminal on a wireless network. .

An object of the present embodiments is to set an optimal backoff coefficient used for packet retransmission of a terminal in a wireless network using Pure ALOHA, thereby increasing the throughput of the wireless network and backlog size, i.e. backlog. The present invention relates to a method and an apparatus for reducing the number of terminals.

를 측정하는 채널 유휴 시간 측정 단계, k번째 에포크의 백오프 계수

를 계산하기 위한 랜덤 샘플 집합

를 갱신하는 랜덤 샘플 집합 갱신 단계,

,

및 (k-1)번째 에포크에 대한 백오프 계수

을 기초로 k번째 에포크의 백오프 계수

를 계산하는 백오프 계수 계산 단계 및

값을 복수의 단말에 브로드캐스팅하는 브로드캐스트 단계를 포함하는 것을 특징으로 하는 방법을 제공한다.In order to solve the above problems, an embodiment of the present invention provides a method for controlling an access point of a terminal in a wireless network using a pure ALOHA protocol, in which a channel is idle for a k-th epoch. (idle time)

Channel idle time measurement step to measure the backoff coefficient of the k-th epoch

Set of random samples to compute

Random sample set updating step of updating,

,

And the backoff coefficient for the (k-1) th epoch

The backoff coefficient of the k-th epoch based on

Calculating a backoff coefficient and calculating

It provides a method comprising the step of broadcasting a value to a plurality of terminals.

를 측정하는 채널 유휴 시간 측정부, k번째 에포크의 백오프(backoff) 계수

를 계산하기 위한 랜덤 샘플 집합

를 갱신하는 랜덤 샘플 집합 갱신부,

,

및 (k-1)번째 에포크에 대한 백오프 계수

을 기초로 k번째 에포크의 백오프 계수

를 계산하는 백오프 계수 계산부 및

값을 복수의 단말에 브로드캐스팅하는 브로드캐스트부를 포함하는 것을 특징으로 하는 AP를 제공한다.In addition, an embodiment is a channel idle time for a k-th epoch in an access point (AP) for controlling packet retransmission of a terminal in a wireless network using the Pure ALOHA protocol.

Channel idle time measurement unit for measuring the backoff coefficient of the k-th epoch

Set of random samples to compute

A random sample set updating unit for updating

,

And the backoff coefficient for the (k-1) th epoch

The backoff coefficient of the k-th epoch based on

A backoff coefficient calculator for calculating

It provides an AP comprising a broadcast unit for broadcasting a value to a plurality of terminals.

In this embodiment, by setting an optimal backoff coefficient used for packet retransmission of a terminal in a wireless network using Pure ALOHA, the throughput of the wireless network is increased and the backlog size, i.e. A method and apparatus for reducing the number of terminals may be supported.

1 is a diagram showing the overall configuration of a wireless network using the Pure ALOHA protocol.
2 is a diagram illustrating a configuration of an AP controlling packet retransmission of a terminal in this embodiment.
3 is a flowchart illustrating a method in which an AP controls packet retransmission of a terminal in this embodiment.
4 is a graph comparing a change in the number of backlogged terminals expected when the present embodiment is executed with a change in the number of backlogged terminals when the existing Pure ALOHA system is executed.
Figure 5 shows the values of throughput, delay, backlog size when the present embodiment is executed, throughput, delay, and the like when the existing Pure ALOHA system is executed. This table compares the backlog size.

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

1 is a diagram showing the overall configuration of a wireless network using the Pure ALOHA protocol.

In a wireless network using the Pure ALOHA protocol, an access point (AP) 110 exists first. The AP 110 may be connected to a plurality of terminals. The terminals 120, 130, 140, and 150 may transmit a packet to the AP 110. In this case, when two or more terminals attempt to transmit the packet to the AP 110 at the same time, the terminal 120, 130, 140, and 150 may transmit a packet to the AP 110. Collision may occur while overlapping frames of packets transmitted from other terminals.

In this case, as described above, a delayed first transmission (DFT) scheme may be used as a method of retransmitting a packet when a collision occurs in the process of transmitting a packet to the AP 110. In the case of using the DFT scheme, a backlogged terminal, that is, a terminal having a packet to be retransmitted, attempts to retransmit the packet after a random backoff time interval when a collision or transmission failure is recognized.

)로 표현된다. 지수 분포는 창구의 평균 대기 시간, 도착 시간, 고장율 등을 모형화하는데 적합한 확률 분포이다.As an example of the method of selecting the aforementioned backoff time interval, each terminal receives a backoff coefficient β broadcast by the AP 110 and randomly from an exponential distribution function that averages 1 / β. You can select the backoff time interval. An exponential distribution is used to represent a continuous probability distribution of the wait time for an event to occur, that is, the probability distribution over the 'elapsed time' between events.

) The exponential distribution is a probability distribution suitable for modeling the mean waiting time, arrival time, failure rate, and the like of a window.

The backoff coefficient β that the AP broadcasts to the terminal may be updated over time. In particular, it may be updated based on a state of a channel where communication between the terminal and the AP occurs and a previous backoff coefficient value.

In this case, an epoch may be set to determine a time point at which the aforementioned backoff coefficient value is updated. For example, a time interval between a specific terminal succeeding in packet transmission or a collision between terminals can be set to one epoch after a channel in which communication between the terminal and the AP enters an idle state.

A new epoch is generated whenever a packet transmission or collision occurs after wireless communication between the terminal and the AP is started. In this case, the index k of the epoch may be set to distinguish the epochs. The first k = 0 when wireless communication between the terminal and the AP is started, and then each time a packet transmission or collision occurs, the k value is increased by 1 and each epoch is set to 0th epoch, 1st epoch, 2nd epoch ... Can be.

This embodiment describes the content of the AP controlling the packet retransmission of the terminal by updating the backoff coefficient β that the AP broadcasts to the terminal in the k-th epoch, which is an epoch.

2 is a diagram illustrating a configuration of an AP controlling packet retransmission of a terminal in this embodiment.

Referring to FIG. 2, the AP 200 may include a channel idle time measurement unit 210, a random sample set updater 220, a backoff calculator 230, and a broadcaster 240.

를 측정할 수 있다.The channel idle time measuring unit 210 is a channel idle time for the kth epoch.

Can be measured.

이라 하고, 각 단말이 AP로부터 수신한 백오프 계수 β에 대해 1/β을 평균으로 하는 지수 분포(exponential distribution) 함수로부터 랜덤하게 패킷 재전송 시간 간격을 선택한다고 가정하면, 이 때

값은 평균이

인 지수 분포(exponential distribution)을 따르게 된다.If the number of terminals to transmit a packet from the previous (k-1) epoch to the AP

Suppose that each terminal randomly selects a packet retransmission time interval from an exponential distribution function that averages 1 / β with respect to the backoff coefficient β received from the AP.

The value is average

It follows the exponential distribution.

를 계산하기 위한 랜덤 샘플 집합

를 갱신할 수 있다.The random sample set updater 220 is a backoff coefficient for the k-th epoch.

Set of random samples to compute

Can be updated.

는 k번째 에포크에서 무선 네트워크 시스템의 상태를 나타내기 위한 랜덤한 샘플값의 집합을 나타낸다.

는 길이가

인

의 열 벡터(column vector)로서 다음 수학식 1과 같이 표현될 수 있다.

Denotes a set of random sample values for representing the state of the wireless network system at the kth epoch.

Has a length

sign

It may be expressed as a column vector of Equation 1 below.

는

의 개수, 즉 샘플값의 개수를 나타내며, AP에 의해 임의로 설정될 수 있다.

의 값이 클 수록 많은 샘플을 사용한다는 의미이므로 백로그 사이즈 추정의 정확도를 높일 수 있다. 일 예로

는 50으로 설정될 수 있다.here

Is

It indicates the number of, i.e., the number of sample values, and may be arbitrarily set by the AP.

A larger value means that more samples are used, which increases the accuracy of backlog size estimation. As an example

May be set to 50.

의 구성 요소인

내지

는 각각 별도의 랜덤한 샘플값을 나타낸다. In Equation 1

Is a component of

To

Each represents a separate random sample value.

(i는 1에서

사이의 정수)를 정하기 위해 정규 분포(normal distribution) 함수를 이용할 수 있다. 일 예로

은 평균이 100이고 표준 편차가 1인 정규 분포 함수에서 값을 선택하되, 단 샘플값이 음수가 되는 것을 방지하기 위해서 선택된 값이 0보다 작을 경우에는 0으로 설정한다.First step, k = 0

(i is from 1

Normal distribution function) can be used. As an example

Selects a value from a normal distribution function with a mean of 100 and a standard deviation of 1, but sets it to zero if the selected value is less than zero to avoid negative sample values.

는 (k-1)번째 에포크에서 사용한 랜덤 샘플 집합

을 기초로 갱신될 수 있다.Random sample set used by the kth epoch with repeated epochs

Is a random sample set used at the (k-1) th epoch

Can be updated based on.

는 전술한

을 인자로 하는 리샘플링 함수의 결과값에 각 요소마다 추가 계수값을 더하여 갱신될 수 있다. Specifically random sample set

Mentioned above

It can be updated by adding an additional coefficient value for each element to the result value of the resampling function taking as a factor.

의 각 요소의 확률값을 시드(seed)로 하여 새로운 랜덤 샘플 집합을 추출하기 위한 함수로서, 이 때, 리샘플링 함수는 후술할

를 추가 인자로 사용할 수 있다. The resampling function

A function for extracting a new random sample set by using a seed value of each element of as a seed, wherein the resampling function will be described later.

Can be used as an additional argument.

The reason for adding an additional coefficient value for each element to the result of the resampling function is to prevent the degeneracy problem of overlapping values of each element of the random sample set during the resampling process.

일 수 있다.In this case, as an example of a method of obtaining the additional coefficient value, the additional coefficient value may be randomly selected from a normal distribution function having a mean of zero. The standard deviation of the normal distribution function for selecting additional coefficient values can be selected according to the simulation. For example, the standard deviation value is

Can be.

을 인자로 하는 리샘플링 함수의 결과값에 각 요소 별로 추가 계수값을 더한 후, 각 요소 중 음수인 값을 가지는 요소에 대해서는 0으로 설정하여 음수의 값이 되지 않도록 할 수 있다.only,

After adding an additional coefficient value for each element to the result value of the resampling function having the factor as, the negative value may be set to 0 for each element having a negative value.

와 랜덤 샘플 집합 갱신부(220)에서 갱신된

, 그리고 이전 에포크인 (k-1)번째 에포크에 대한 백오프 계수인

을 기초로 하여 k번째 에포크에 대한 백오프 계수인

를 계산할 수 있다.The backoff coefficient calculator 230 may measure the idle time measured by the channel idle time measurer 210.

And updated by the random sample set updater 220

And the backoff coefficient for the previous epoch (k-1) epoch

Based on the backoff coefficient for the kth epoch,

Can be calculated.

를 구하기 위해서 우선 확률 집합

를 구할 수 있다.

는 측정된 유휴 시간

일 때 가능한 확률의 집합을 의미하며 각 요소는 지수 분포(exponential distributed) 함수로 표현될 수 있다.

는

와 마찬가지로 길이가

인 열 벡터(column vector)로서 다음 수학식 2와 같이 표현될 수 있다.At this time,

First, the probability set

Can be obtained.

Measured idle time

In this case, it means a set of possible probabilities, and each element can be expressed as an exponential distributed function.

Is

As long as

As a column vector, it may be expressed as Equation 2 below.

의 구성 요소인

내지

는 각각 별도의 확률값을 나타낸다. In equation (2)

Is a component of

To

Each represents a separate probability value.

는

,

,

에 의해 다음의 수학식 3과 같이 결정될 수 있다.At this time,

Is

,

,

It can be determined by the following equation (3).

를 기초로

는 다음과 같이 구할 수 있다.determined

Based on

Can be obtained as

를 기초로 다음의 수학식 4와 같이

를 구할 수 있다.priority,

Based on Equation 4

Can be obtained.

는

를 전치(transpose)한 행렬을 의미하며,

는

와 마찬가지로 길이가

인

의 열 벡터(column vector)로서 모든 요소의 값이 1인 행렬, 즉 [1,1,1, ... ,1]을 의미한다. 즉,

는

의 각 요소값을

와

의 곱, 즉

의 모든 요소의 값의 합인 (

)으로 나눈 열 벡터를 의미한다.In equation (4)

Is

Means a matrix transposed of

Is

As long as

sign

Is a column vector of, meaning a matrix with all elements having a value of 1, that is, [1,1,1, ..., 1]. In other words,

Is

For each element of

Wow

Product of

Is the sum of the values of all elements of (

Column vector divided by).

와

를 이용하여

는 다음의 수학식 5와 같이 구할 수 있다.Above

Wow

Using

Can be obtained as in Equation 5 below.

를 복수의 단말에 브로드캐스팅할 수 있다.The broadcast unit 240 calculates the backoff coefficient calculated by the backoff coefficient calculator 230.

Can be broadcast to a plurality of terminals.

를 수신하고,

을 평균으로 하는 지수 분포(exponential distribution) 함수에서 랜덤하게 백오프 시간 간격을 선택할 수 있다.As described above, each terminal has a backoff coefficient broadcast by the AP at the k-th epoch.

Receive

The backoff time interval can be selected at random from an exponential distribution function that is taken as an average.

3 is a flowchart illustrating a method in which an AP controls packet retransmission of a terminal in this embodiment.

Hereinafter, the method performed by the AP 200 described with reference to FIG. 2 will be described as an example.

를 측정할 수 있다(S310).Referring to FIG. 3, the channel idle time measurement unit 210 of the AP 200 is a channel idle time for a k-th epoch.

It may be measured (S310).

를 계산하기 위해 랜덤 샘플 집합

를 갱신할 수 있다(S320).The random sample set updater 220 of the AP 200 is a backoff coefficient of the k-th epoch.

Random sample set to calculate

It may be updated (S320).

는 (k-1)번째 에포크에서 사용한 랜덤 샘플 집합

을 기초로 갱신될 수 있다.At this time, as described above, a random sample set used in the k-th epoch

Is a random sample set used at the (k-1) th epoch

Can be updated based on.

는 전술한

을 인자로 하는 리샘플링 함수의 결과값에 각 요소 별로 추가 계수값을 더한 값으로 갱신될 수 있다. 이 때, 각 요소 별로 추가 계수값을 더 하는 이유는 리샘플링 과정에서 랜덤 샘플 집합의 각 요소의 값이 겹치는 문제를 방지하기 위함이다.Specifically random sample set

Mentioned above

The result of the resampling function of which may be updated to a value obtained by adding an additional coefficient value for each element. In this case, the reason for adding an additional coefficient value for each element is to prevent the problem of overlapping values of the elements of the random sample set during the resampling process.

In this case, as an example of a method of obtaining the additional coefficient value, the additional coefficient value may be randomly selected from a normal distribution function having a mean of zero. The standard deviation of the normal distribution function for selecting additional coefficient values may vary depending on a preset value.

을 인자로 하는 리샘플링 함수의 결과값에 추가 계수값을 더한 값이 음수일 경우에는 0으로 설정하여 음수의 값이 되지 않도록 할 수 있다.only,

If the result of the resampling function whose value is a plus the additional coefficient value is negative, it can be set to 0 so as not to be negative.

, 랜덤 샘플 집합 갱신부(220)에서 갱신된

와 이전 (k-1)번째 에포크에서의 백오프 계수인

을 기초로 하여 k번째 에포크의 백오프 계수

를 계산할 수 있다(S330).In addition, the backoff coefficient calculator 230 of the AP 200 is measured by the channel idle time measurement unit 210.

Updated by the random sample set updater 220

And the backoff coefficient at the (k-1) th epoch

The backoff coefficient of the k-th epoch based on

It can be calculated (S330).

를 구하기 위해서 우선 확률 집합

를 구할 수 있으며,

는 전술한 수학식 3과 같이 결정될 수 있다.At this time, as described above

First, the probability set

Is available,

May be determined as in Equation 3 described above.

를 기초로

를 전술한 수학식 4와 같이 계산할 수 있으며, S330 단계에서 갱신된

와

를 기초로

를 전술한 수학식 5와 같이 계산할 수 있다.And

Based on

May be calculated as in Equation 4 described above, and updated in step S330.

Wow

Based on

May be calculated as in Equation 5 described above.

값을 복수의 단말에 브로드캐스팅할 수 있다(S340).The broadcast unit 240 of the AP 200 is calculated by the backoff coefficient calculator 230.

The value may be broadcast to a plurality of terminals (S340).

를 수신한 각 단말은

를 평균으로 하는 지수 분포(exponential distribution) 함수로부터 랜덤하게 패킷 재전송 간격을 선택할 수 있다.As described above, broadcast from the AP 200

Each terminal receiving the

The packet retransmission interval may be randomly selected from an exponential distribution function of averaging.

4 is a graph comparing the change in the number of backlogged terminals expected when the present embodiment is executed with the change in the number of backlogged terminals when the existing Pure ALOHA system is executed.

는 k번째 에포크에서의 백로그된 단말의 수를 의미한다. 도 4에서 패킷 도착 비율(package arrival rate)인 G 값은 0.19이다.Referring to FIG. 4, FIG. 4 (a) is a graph showing the number of backlogged terminals according to the IFT and DFT schemes when executing the existing Pure ALOHA system. The x-axis of the graph is the k-value representing the index of the epoch and the y-axis

Denotes the number of backlog terminals in the k-th epoch. In FIG. 4, the G value, which is a package arrival rate, is 0.19.

는 k번째 에포크에서의 백로그된 단말의 수를 의미한다.FIG. 4B is a graph illustrating the number of backlogged terminals when the present embodiment is executed, divided into a system backlog size and an estimated backlog size of an actual system. As in FIG. 4A, the x-axis of the graph is a k-value representing the index of the epoch and is the y-axis.

Denotes the number of backlog terminals in the k-th epoch.

가 20 이하로 유지되고, 도 4의 (b)에서 IFT 방식 및 DFT 방식이

가 20 이상인 것을 확인할 수 있다. 따라서 본 실시예가 기존의 Pure ALOHA 시스템에 비해 보다 더 효율적인 시스템이라는 것을 확인할 수 있다.Comparing (a) and (b) of FIG. 4, as k increases in FIG.

Is maintained below 20, and the IFT scheme and the DFT scheme in FIG.

It can be confirmed that is 20 or more. Therefore, it can be seen that this embodiment is a more efficient system than the conventional Pure ALOHA system.

5 shows the values of throughput, delay, backlog size when the present embodiment is executed, throughput, delay, and the like when the existing Pure ALOHA system is executed. This table compares the backlog size.

In FIG. 5, the Controlled System refers to the present embodiment, and the Uncontrolled DFT refers to the existing Pure ALOHA system using the DFT method, and the Uncontrolled IFT refers to the existing Pure ALOHA system using the IFT method.

는 처리량,

은 백로그 사이즈,

는 지연을 의미하고 ana.는 실제 측정값, sim.은 시뮬레이션 결과값을 의미한다. 도 5를 참조하면 모든 경우에 대해, 본 실시예에서의 처리량, 백로그 사이즈, 지연이 기존 Pure ALOHA 시스템에서의 처리량, 백로그 사이즈, 지연에 비하여 개선된 것을 확인할 수 있다.In Figure 5, G is the packet arrival rate,

Is throughput,

Is the backlog size,

Is the delay, ana. Is the actual measurement, sim. Is the simulation result. Referring to FIG. 5, in all cases, it can be seen that the throughput, backlog size, and delay in this embodiment are improved compared to the throughput, backlog size, and delay in the existing Pure ALOHA system.

The above description is merely illustrative of the technical idea of the present embodiment, and those skilled in the art will appreciate that various modifications and variations can be made without departing from the essential characteristics of the present embodiment. Therefore, the contents disclosed in the present embodiment are not intended to limit the technical idea of the present embodiment but to explain, and the scope of the technical idea of the present embodiment is not limited by these embodiments. The scope of protection of the present embodiment should be interpreted by the following claims, and all technical ideas within the scope equivalent thereto should be construed as being included in the scope of the present embodiment.

Claims (10)

In a method of controlling the packet retransmission of the terminal in the AP (Access Point) in a wireless network using the Pure ALOHA protocol,
Channel idle time for k th epoch

Measuring channel idle time;
koff epoch backoff coefficient

Set of random samples to compute

A random sample set updating step of updating a;
remind

, remind

And the backoff coefficient for the (k-1) th epoch

The backoff coefficient of the k-th epoch based on

Calculating a backoff coefficient; And
remind

And broadcasting a value to the plurality of terminals.
The method of claim 1,
Each terminal,

And randomly selecting a packet retransmission interval from an exponential distribution function of averaging.
The method of claim 1,
The random sample set,
Random sample set of (k-1) th epoch

Wherein the result of the resampling function with a factor is updated to the value of the additional coefficient value added for each element,
The additional count value is,
And randomly selected from a normal distribution function with a mean of zero.
The method of claim 1,
The backoff coefficient calculation step,
remind

,

And

Based probability set

Obtaining
The probability set

Based on the above

Calculate the
remind

Is,

It is determined that the method.
The method of claim 4, wherein
The backoff coefficient calculation step,
remind

Is a matrix with all element values equal to 1

Based on

Obtaining
remind

Is

The method characterized in that the calculated.
In an access point (AP) controlling packet retransmission of a terminal in a wireless network using the Pure ALOHA protocol,
Channel idle time for k th epoch

Channel idle time measuring unit for measuring;
backoff coefficient of the kth epoch

Set of random samples to compute

A random sample set updating unit for updating a;
remind

, remind

And the backoff coefficient for the (k-1) th epoch

The backoff coefficient of the k-th epoch based on

A backoff coefficient calculation unit for calculating a; And
remind

And a broadcast unit that broadcasts values to the plurality of terminals.
The method of claim 6,
Each terminal,

AP randomly selects a packet retransmission interval from an exponential distribution function that averages.
The method of claim 6,
The random sample set,
Random sample set of (k-1) th epoch

Wherein the result of the resampling function with a factor is updated to the value of the additional coefficient value added for each element,
The additional count value is,
AP selected randomly from a normal distribution function with a mean of zero.
The method of claim 6,
The backoff coefficient calculation unit,
remind

,

And

Based probability set

Obtaining
The probability set

Based on the above

Calculate the
remind

Is,

AP is determined as.
The method of claim 9,
The backoff coefficient calculation unit,
remind

Is a matrix with all element values equal to 1

Based on

Obtaining
remind

Is

AP, which is calculated as.

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