A method for random delay based multi-access point contention response

Abstract

The application discloses a method for multi-access point contention response based on random time delay. The application relates to the technical field of wireless communication, and solves the problems of wireless node retransmission, increased delay, and even connection interruption caused by high conflict probability due to the fact that multiple wireless access points simultaneously receive signals. The method comprises the following steps: after a wireless node terminal is online, an access point contention inquiry instruction is sent, and all wireless access points in a channel receive the instruction; the wireless access points reply response information carrying signal strength information to the wireless node terminal by using random time delay response; and the wireless node terminal selects a wireless access point with the highest received signal strength as a main access point. The application can improve the communication reliability of equipment, avoid problems such as data loss and time delay, and improve transmission efficiency. For low-power wireless nodes, the radio frequency retransmission power consumption of the wireless node equipment can be further reduced, and the effective use time is prolonged.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of wireless communication technology, and in particular to a method for multiple access point contention response based on random delay. BACKGROUND

[0002] In a wireless local area network, a cellular network or other wireless communication system, a wireless node terminal, i.e. a field device (FD) such as a mobile device, an Internet of Things device, transmits data to the network. Due to the broadcast nature and multipath propagation of wireless signals, the transmission signal of a wireless node terminal can be received by multiple wireless access points, i.e. access devices (AD) at the same time. According to the protocol requirements, these wireless access points can all need to send response information, such as an acknowledge character (ACK), to the wireless node terminal. When multiple wireless access points send responses almost at the same time, these response signals will collide with each other in the air, causing the wireless node terminal to fail to correctly receive any response, thereby causing retransmission, increasing delay, and even causing connection interruption, which seriously affects communication efficiency and user experience. In the prior art, random backoff mechanisms are usually relied on to reduce collisions, such as the carrier sense multiple access with collision avoidance (CSMA / CA) protocol. However, in the scenario where multiple wireless access points receive signals at the same time, the collision probability is still high, and there is a lack of effective targeted solutions. SUMMARY

[0003] The present application aims to provide a method for multiple access point contention response based on random delay, to solve the problem of wireless node retransmission, increased delay, and even connection interruption caused by high collision probability in the wireless scenario where multiple access points receive signals at the same time.

[0004] The present application provides a method for multiple access point contention response based on random delay, comprising:

[0005] Step one, after the wireless node terminal is online, an access point contention inquiry instruction is sent, and all wireless access points in the channel receive the instruction;

[0006] Step two, the wireless access points reply the response information carrying signal strength information to the wireless node terminal using random delay response; after the wireless node terminal receives the response information of all wireless access points within the response valid time period, the signal strength information carried by the response information is compared, the wireless access point with the highest received signal strength is selected as the main access point, and data is transmitted to the wireless access point; the wireless access point sends the data to the gateway;

[0007] Step three, the gateway filters the data by data serial number to avoid data duplication.

[0008] Further, in step two, the data is transmitted according to the following frame format: frame header, primary access point destination address, contention response, data packet, serial number, check bit and frame tail.

[0009] Further, the method further comprises:

[0010] After the wireless access point listens to the primary access point destination address and compares it with its own address, if the primary access point destination address is the same as its own address, the data is received and the wireless node terminal is responded to, and the data is forwarded to the gateway;

[0011] If the primary access point destination address is not the same as its own address, no response is made.

[0012] If the wireless node terminal sends data and the primary access point does not respond in time, the data is retransmitted for a preset number of times to trigger the contention response flag to be set.

[0013] Further, after the contention response flag is set in the wireless access point in the channel, the data content is received and forwarded to the gateway, and a random delay response is adopted to resend the response information with the received signal strength to compete for the primary access point, and the wireless node terminal re-determines the primary access point address for subsequent data transmission.

[0014] Further, the random delay response comprises:

[0015] The wireless access point sets a minimum time delay t min ; sets a maximum delay t max ; random_t is a random time increment to add random jitter to the delay so that the delay time of each request is slightly different; the wireless access point has a unique address as a constant parameter C, and adopts a sending response delay formula:

[0016] t_delay =(t min ·C)%t max + random_t

[0017] In the formula, t_delay represents the response delay, t min represents the minimum time delay, C represents the constant parameter, t max represents the maximum delay, and random_t represents a random time increment to add random jitter to the delay so that the delay time of each request is slightly different.

[0018] The application has the following beneficial effects: the method for multi-access point contention response based on random time delay can improve the communication reliability of equipment, avoid data loss, time delay and other problems, and improve transmission efficiency. BRIEF DESCRIPTION OF DRAWINGS

[0019] In order to more clearly illustrate the technical solutions of the present application, the drawings needed to be used in the embodiments will be briefly introduced as follows. Obviously, for those skilled in the art, other drawings can also be obtained from these drawings without any creative labor.

[0020] Figure 1 The system structure principle diagram of the present application. DETAILED DESCRIPTION

[0021] In order to make the purpose, technical solutions and advantages of the present application more clear, the technical solutions of the present application will be described clearly and completely in combination with the specific embodiments of the present application and corresponding drawings. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without any creative labor are within the protection scope of the present application. The technical solutions provided by each embodiment of the present application will be described in detail below in combination with the drawings.

[0022] The present application is based on Figure 1 The device transmission system shown in the figure includes a management system, a gateway, wireless access points (AD) and wireless node terminals (FD). Each wireless access point in the figure is represented as AD1, AD2,..., ADn. Each wireless node terminal is represented as FD1, FD2,..., FDn.

[0023] The method for multi-access point contention response based on random time delay provided by the embodiment of the present application includes:

[0024] Step one: after the wireless node terminal is online, an access point contention inquiry instruction is sent, and all wireless access points in the channel receive the instruction.

[0025] Specifically, the instruction can be that the primary access point address is empty and the contention response is 1, or it can also be other specified instruction frames.

[0026] In the embodiment, data is transmitted according to the frame format shown in Table 1.

[0027]

[0028] Step two, the wireless access point replies the reply information carrying signal strength information to the wireless node terminal by using random time delay; after the wireless node terminal receives the reply information of all wireless access points within the reply valid time period, it compares the signal strength information carried by the reply information, selects the wireless access point with the highest received signal strength as the main access point, and transmits data to the wireless access point; the wireless access point sends the data to the gateway.

[0029] Specifically, the data is transmitted according to the following frame format: frame header, main access point destination address, contention reply, data packet, sequence number, check bit and frame tail. The contention reply in the frame format is a flag bit, when the bit is 1, the frame can be judged as belonging to the contention inquiry instruction, and the multiple wireless access points can be triggered to reply and compete for the main access point.

[0030] Specifically, the random time delay reply includes:

[0031] The wireless access point sets a minimum time delay t min For example, 1ms; the maximum delay is set as t max For example, 50ms; random_t is a random time increment to add random jitter to the delay, so that the delay time of each request is slightly different; the wireless access point has a unique address as a constant parameter C, and uses the reply time delay formula:

[0032] t_delay =(t min ·C)%t max + random_t

[0033] In the formula, t_delay represents the reply time delay, t min represents the minimum time delay, C represents the constant parameter, t max represents the maximum delay, and random_t represents a random time increment to add random jitter to the delay, so that the delay time of each request is slightly different. After the wireless access point receives the contention instruction, it replies after the time delay t_delay, the minimum time delay is multiplied by the constant parameter, and the remainder is taken based on the maximum delay, and a small time increment is added, so as to avoid collision caused by reply at the same time.

[0034] Step three, the gateway filters the data by data sequence number to avoid repeated data transmission.

[0035] In the embodiment, the method further comprises: after the wireless access point listens to the master access point destination address, comparing the master access point destination address with the self address, if the master access point destination address is same as the self address, receiving data and answering the wireless node terminal, and forwarding the data to the gateway; if the master access point destination address is not same as the self address, not answering; if the wireless node terminal sends data, the master access point does not answer in time, and after retransmitting the data for a preset number of times, triggering the contention answer flag to be set to 1.

[0036] In the embodiment, the contention answer flag is set to 1 after the data is retransmitted for 10 times, as shown in Table 2.

[0037]

[0038] After the wireless access point in the channel receives the contention answer flag set to 1, the data content is received and forwarded to the gateway, and a random delay answer is adopted, the answer information with the received signal strength is retransmitted to compete for the master access point, and the wireless node terminal re-determines the master access point address for subsequent data transmission.

[0039] From the above embodiment, it can be seen that the application provides a multi-access point contention answer method based on random delay, in the case that one wireless node terminal sends a signal which can be received by multiple wireless access points in a wireless communication system, the application avoids that the answer signals collide and lose in the air, causes retransmission, increases delay, and even causes connection interruption, thereby affecting the communication efficiency and user experience. Through the access point contention inquiry function, the multiple access points adopt a random delay answer strategy, and carry the wireless signal strength information at the same time, so that the wireless node terminal can determine the answer access point with the highest signal strength as the master access point for subsequent data transmission; at the same time, other access points adopt the listening data contention answer flag, and can actively compete for the master access point function at the first time when the environment changes, to ensure the communication reliability and flexibility of the wireless node terminal.

[0040] The above-mentioned embodiments of the application do not constitute a limitation on the protection scope of the application.

Claims

1. A method for multi-access point contention response based on random delay, characterized in that: include: Step 1: After the wireless node terminal goes online, it sends an access point contention query command, and all wireless access points in the channel receive the command; In step 2, the wireless access point uses a random delay response to reply a response message carrying signal strength information to the wireless node terminal. After receiving the response messages from all wireless access points within the response validity period, the wireless node terminal compares the signal strength information carried in the response messages, selects the wireless access point with the highest received signal strength as the primary access point, and transmits data to the wireless access point. The wireless access point sends the data to the gateway; Step 3: The gateway filters the data by data sequence number to avoid repeated data transmission; The random delay response includes: The wireless access point sets a minimum time delay t min ; Set the maximum delay to t max ; random_t is a random time increment. Random jitter is added to the delay to make the delay time of each request different. The wireless access point has a unique address as the constant parameter C, and the sending response delay formula is: t_delay =(t min ·C)%t max + random_t Where, t_delay represents the response delay, t min represents the minimum time delay, C represents the constant parameter, t max Indicates the maximum delay, random_t indicates a random time increment. Random jitter is added to the delay to make the delay time of each request different.

2. The method for multi-access point contention response based on random delay according to claim 1, wherein: In step 2, the data is transmitted in the following frame format: frame header, primary access point destination address, contention response, data packet, sequence number, check bit and frame trailer.

3. The method for multi-access point contention response based on random delay according to claim 2, wherein: The method further comprises: The wireless access point monitors the destination address of the main access point and compares it with its own address. If the destination address of the main access point is the same as its own address, it receives the data and responds to the wireless node terminal, and forwards the data to the gateway at the same time. If the destination address of the primary access point is different from its own address, no response is made; If the wireless node terminal sends data and the master access point does not respond in time, the data will be retransmitted a preset number of times and then the contention response flag will be set.

4. The method for multi-access point contention response based on random delay according to claim 1, wherein: After receiving the contention response flag, the wireless access point in the channel receives the data content and forwards it to the gateway. It uses a random delay response and resends the response information with the received signal strength to compete for the main access point. The wireless node terminal re-determines the main access point address for subsequent data transmission.

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