Multi-access-point competition response method based on random time delay

Abstract

The invention discloses a multi-access point competition response method based on random time delay. The invention relates to the technical field of wireless communication, and solves the problems of wireless node retransmission, delay increase and even connection interruption caused by high conflict probability when a plurality of wireless access points receive signals at the same time. The method comprises the following steps: a wireless node terminal sends an access point competition inquiry instruction after being online, and all wireless access points in a channel receive the instruction; the wireless access point replies response information carrying the signal strength information to the wireless node terminal by adopting random time delay response; and the wireless node terminal selects the wireless access point with the highest received signal strength as the main access point. The communication reliability of the equipment can be improved, the problems of data loss, time delay and the like are avoided, and the transmission efficiency is improved. And for a low-power-consumption wireless node, the radio frequency retransmission power consumption of wireless node equipment can be further reduced, and the effective use time is prolonged.

Description

Technical Field

[0001] The present invention relates to the field of wireless communication technology, and in particular to a method for multi-access point contention response based on random time delay. Background Art

[0002] In wireless local area networks, cellular networks, and other wireless communication systems, wireless node terminals, or field devices (FDs), such as mobile devices and IoT devices, transmit data to the network. Due to the broadcast nature and multipath propagation of wireless signals, a signal transmitted by a wireless node terminal may be received simultaneously by multiple wireless access points, or access devices (ADs). Protocol requirements require each of these APs to send a response, such as an acknowledgment character (ACK), to the wireless node terminal. When multiple APs send acknowledgments almost simultaneously, these acknowledgment signals collide over the air, preventing the wireless node terminal from correctly receiving any of the acknowledgments. This can lead to retransmissions, increased latency, and even connection loss, severely impacting communication efficiency and user experience. Existing technologies typically rely on random backoff mechanisms, such as the Carrier Sense Multiple Access with Collision Avoidance (CSMA / CA) protocol, to reduce collisions. However, when multiple APs receive signals simultaneously, the probability of collision remains high, and effective, targeted solutions are lacking. Summary of the Invention

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

[0004] The present invention provides a method for multi-access point contention response based on random delay, comprising: 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; 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 then sends the data to the gateway. Step 3: The gateway filters the data by data sequence number to avoid repeated data transmission.

[0005] Furthermore, 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.

[0006] Furthermore, 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.

[0007] Furthermore, after receiving the contention response flag in the channel, the wireless access point receives the data content and forwards it to the gateway, and uses a random delay response to resend 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.

[0008] Furthermore, 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 slightly different. The wireless access point has a unique address as the constant parameter C, and the send 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 so that the delay time of each request is slightly different.

[0009] The present invention has the following beneficial effects: A multi-access point contention response method based on random delays can improve device communication reliability, avoid data loss and latency issues, and enhance transmission efficiency. For low-power wireless nodes, it can further reduce the RF retransmission power consumption of wireless node devices, extending their effective usage time. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] In order to more clearly illustrate the technical solution of the present invention, the following briefly introduces the drawings required for use in the embodiments. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0011] Figure 1 This is a schematic diagram of the system structure of the present invention. DETAILED DESCRIPTION

[0012] To make the objectives, technical solutions, and advantages of the present invention more clear, the technical solutions of the present invention will be clearly and completely described below in conjunction with specific embodiments of the present invention and corresponding drawings. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention. The technical solutions provided by each embodiment of the present invention are described in detail below in conjunction with the drawings.

[0013] The present invention is based on Figure 1 The device transmission system shown includes a management system, a gateway, wireless access points (ADs), and wireless node terminals (FDs). In the figure, the wireless access points are represented by AD1, AD2, ..., ADn. The wireless node terminals are represented by FD1, FD2, ..., FDn.

[0014] An embodiment of the present invention provides a method for multi-access point contention response based on random delay, including: Step 1: After the wireless node terminal goes online, it sends an access point contention query instruction, and all wireless access points in the channel receive the instruction.

[0015] Specifically, the instruction may be that the address of the primary access point is empty and the contention bit is set to 1, or may be another specified instruction frame.

[0016] In this embodiment, data is transmitted according to the frame format shown in Table 1.

[0017]

[0018] In step 2, the wireless access point uses a random delay response to reply the response information carrying the signal strength information to the wireless node terminal; after the wireless node terminal receives the response information of all wireless access points within the response validity period, it compares the signal strength information carried in the response information, selects the wireless access point with the highest received signal strength as the main access point, and transmits the data to the wireless access point; the wireless access point sends the data to the gateway;

[0019] Specifically, the data is transmitted in the following frame format: a frame header, a destination address of a primary access point, a contention response, a data packet, a sequence number, a check bit, and a frame trailer. The contention response in the frame format is a flag bit. When this bit is 1, the frame can be determined to be a contention query instruction, which can trigger multiple wireless access points to respond to the contention for the primary access point.

[0020] Specifically, the random delay response includes: The wireless access point sets a minimum time delay t min For example, 1ms; set the maximum delay to t max For example, 50ms; random_t is a random time increment. Random jitter is added to the delay to make the delay time of each request slightly 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 Denotes the maximum delay, and random_t represents a random time increment. Random jitter is added to the delay, making each request's delay slightly different. After receiving the contention command, the access point delays for t_delay before responding. The minimum delay is multiplied by a constant parameter, and the remainder is calculated based on the maximum delay. A small time increment is then added to prevent collisions caused by simultaneous responses.

[0021] Step 3: The gateway filters the data by data sequence number to avoid repeated data transmission.

[0022] In this embodiment, the method further includes: after the wireless access point monitors the destination address of the main access point, comparing it with its own address; if the destination address of the main access point is the same as its own address, receiving the data and responding to the wireless node terminal, and forwarding the data to the gateway; if the destination address of the main access point is different from its own address, not responding; if the main access point does not respond in time after the wireless node terminal sends data, retransmitting the data a preset number of times and triggering the contention response flag to be set.

[0023] In this embodiment, the contention response flag is triggered to be set after the data is retransmitted 10 times, as shown in Table 2.

[0024]

[0025] 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.

[0026] As can be seen from the above embodiments, the present invention provides a multi-access point competition response method based on random delay. In a wireless communication system, when a signal sent by a wireless node terminal may be received by multiple wireless access points, the method avoids the response signals from colliding with each other in the air and being lost, causing retransmission, increasing delay, and even causing connection interruption, thereby affecting communication efficiency and user experience. Through the access point competition inquiry function, multiple access points adopt a random delay response strategy and carry wireless signal strength information at the same time, so that the wireless node terminal can determine the response access point with the highest signal strength as the main access point for subsequent data transmission; at the same time, other access points use the monitoring data competition response flag bit to actively compete for the main access point function in the first time when the environment changes, ensuring the communication reliability and flexibility of the wireless node terminal.

[0027] The above-described embodiments of the present invention do not limit the protection scope of the present invention.

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.

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.

5. The method for multi-access point contention response based on random delay according to claim 1, wherein: 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)% tmax + 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.

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