A TDMA two-way communication method based on WiFi platform

Abstract

The present invention discloses a TDMA bidirectional communication method based on a WiFi platform, comprising the following steps: S1: performing time division to obtain a plurality of superframe periods, and dividing the superframe periods into a plurality of time slots; S2: utilizing an access point device and a client device to wirelessly transmit and receive packets based on the plurality of time slots, thereby completing TDMA bidirectional communication. The present invention proposes a bidirectional data communication protocol method based on TDMA, which utilizes a contention-free wireless medium service to address issues such as wireless channel signal interference, high channel acquisition failure rates caused by channel contention, unstable data transmission throughput, and uncertain data message delays.

Description

Technical Field

[0001] The present invention belongs to the technical field of TDMA communication, and in particular relates to a TDMA two-way communication method based on a WiFi platform. Background Art

[0002] WiFi is the most common wireless LAN connection technology in our daily lives. WiFi primarily utilizes the 802.11 series of wireless communication protocols, leading people to refer to the 802.11 protocol as WiFi. From the first generation of WiFi standards in the 1990s to the current WiFi 7 technology, WiFi remains the mainstream standard for personal wireless LANs. WiFi technology is increasingly trending towards higher speeds and higher bandwidths, and is also becoming increasingly sensitive to wireless signal interference.

[0003] WiFi uses the Carrier Sense Multiple Access with Collision Avoidance (CSMA / CA) mechanism as its wireless medium access technology, a technique that obtains wireless channel usage rights through competition. This technology utilizes the distributed coordination function defined in the 802.11 protocol. Before transmitting data, wireless devices first check whether the wireless link is idle. Only if it is idle can they occupy the wireless channel to send data. To avoid conflicts, when a transmitter occupies the channel, the workstation that wants to send data will randomly select a delay time before checking whether the wireless channel is idle. In some cases, the distributed coordination function can also use CTS / RTS frames to detect or clean the wireless channel, further reducing the possibility of collisions.

[0004] With the rapid development of wireless technology, a large number of wireless devices and WiFi devices operate in the ISM frequency band, making wireless channel access more congested and exacerbating interference and collision between wireless signals. WiFi devices are not only subject to channel competition from similar WiFi devices, but also to wireless channel interference from non-WiFi devices. In the case of severe interference, WiFi relies on the channel competition mechanism and finds it difficult to obtain channels for data transmission in a timely manner. This leads to increasingly prominent problems such as unstable wireless data transmission rates, excessive message delays, and message transmission errors, making it impossible to provide stable wireless transmission services, resulting in service interruptions. Summary of the Invention

[0005] The purpose of the present invention is to solve the problem of time delay uncertainty caused by channel competition in the CSMA / CA mechanism adopted by the WiFi standard, and propose a TDMA two-way communication method based on the WiFi platform.

[0006] The technical solution of the present invention is: a TDMA two-way communication method based on a WiFi platform comprises the following steps:

[0007] S1: Perform time division to obtain several superframe periods, and then divide the superframe period into several time slots;

[0008] S2: Based on several time slots, the access point device and the client device are used to send and receive wireless packets to complete TDMA two-way communication.

[0009] Furthermore, each superframe period includes a beacon channel, an access channel, a trigger channel, a resource channel, a data channel and a protection channel.

[0010] The aforementioned further solution has the following beneficial effects: Multiple channels are divided within the superframe to implement protocol control and data transmission channels, and the width of each channel can be dynamically adjusted, enabling centralized management of client devices by the access point device and implementing precise time slot scheduling and allocation strategies. The access point device dynamically adjusts the superframe cycle based on system parameters such as buffered data frames, the number of devices, and transmission latency requirements, achieving a dynamic balance between data transmission efficiency and latency in the system, and meeting performance requirements for message latency and throughput in different scenarios.

[0011] Furthermore, the beacon channel is used for time synchronization management, specifically by using the access point device to send a beacon frame to the client device by broadcasting, using the client device to receive the beacon frame, and using the reference time of the beacon frame as the TDMA reference time of the client device to complete the time synchronization management.

[0012] Furthermore, the access channel is used to manage client device access, including the following sub-steps:

[0013] A21: Within the access channel width, the client device sends an association authentication request frame to the access point device using a random number algorithm.

[0014] A22: Within the access channel width, the access point device receives and processes the association authentication request frame and adds the access point device allowed to access to the authentication list;

[0015] A23: Within the superframe period, the authentication request response is made to the access point device scheduled in the data channel according to the authentication list, thereby completing the client device access management.

[0016] The beneficial effects of the above further scheme are: an access channel is designed in the superframe period, and the access channel can be dynamically inserted into different superframe periods as needed and the channel width of the access channel can be dynamically adjusted. When there are fewer access devices, the frequency of inserting the access channel and the channel width of the access channel can be reduced to maximize the utilization of channel resources; when there are more access devices, the frequency of inserting the access channel and the channel width of the access channel can be increased to achieve rapid online request processing of client devices and improve the access speed of client devices.

[0017] Furthermore, the trigger channel is used for upload management, specifically by using the access point device to send device resource data to the client device, obtain a trigger frame, and complete the resource acquisition trigger operation;

[0018] The trigger frame includes a client device identifier, a resource channel coding method and an uploading method for the client device to upload device resource data to a resource channel.

[0019] The beneficial effect of the above further scheme is: in the present invention, the access point device can send a trigger frame through the trigger channel to initiate cache data detection requests to the client device in batches and centrally, and can obtain the client device data cache size in a timely manner, thereby realizing accurate scheduling and management of uplink and downlink data transmission of the client device in the data channel.

[0020] Furthermore, in the trigger channel, the uploading method of uploading the device resource data to the resource channel by using the client device includes a time slot method and an OFDMA method;

[0021] The time slot method specifically includes: uploading device resource data in different allocated time slots by the client device;

[0022] The OFDMA method is specifically as follows: the client device performs OFDMA uplink coding on the device resource data using the OFDMA uplink coding method assigned by the access point device, and sends the OFDMA uplink coded data to the access point device.

[0023] Furthermore, the resource channel is used for cache management; the specific method is: if the trigger frame of the trigger channel indicates that a time slot method is used, the client device is used to upload the device cache information to the access point device in the corresponding time slot; if the trigger frame of the trigger channel indicates that an OFDMA method is used, the client device is used to encode the device cache information in the corresponding OFDMA resource block and upload it to the access point device.

[0024] The beneficial effect of the above further scheme is: the resource channel uses OFDMA uplink technology to enable multiple devices to use OFDMA resource blocks for encoding at the same time, and report data at the same time to realize the resource channel transmission of data of different device cache sizes, thereby maximizing the utilization of resource channel spectrum resources.

[0025] Furthermore, the data channel is used to manage the sending and receiving of uplink and downlink channel data. The specific method is: using the access point device to send downlink messages to the client device, and using the client device to send uplink messages to the access point device.

[0026] The beneficial effect of the above further solution is that the data channel is scheduled by the access point device, which can realize single or multiple continuous transmission of downlink messages and uplink messages, realize burst transmission of uplink and downlink data to the client device, and achieve flexible and variable priority scheduling effect.

[0027] Furthermore, the downlink message includes a downlink message management frame, a downlink data frame, and a downlink composite frame. The specific method for sending the downlink message is: performing policy scheduling based on the amount, time, and priority of data cached by the access point device for all client devices and the amount of downlink channel resources, generating a downlink scheduling rule, and the access point device sending the downlink message to the client device according to the downlink scheduling rule;

[0028] The uplink message includes an uplink data frame and an uplink composite frame. The specific method for sending the uplink message is as follows: the access point device performs policy scheduling based on the amount, time, and priority of uplink buffered data of all client devices, as well as the amount of uplink channel resources, to generate an uplink scheduling rule; the access point device sends an uplink data request control frame to the client device according to the uplink scheduling rule; and the client device sends the uplink message to the access point device based on the physical layer parameters and data amount contained in the uplink request control frame.

[0029] Furthermore, the protection channel is used for time slot scheduling management, and the specific method is: on the protection channel, an idle time slot is set between the end of the previous superframe period and the beginning of the next superframe period.

[0030] The beneficial effect of the above further solution is that the protection channel width can be dynamically adjusted, thereby achieving maximum utilization of channel resources within the superframe while protecting the superframe beacon channel.

[0031] The beneficial effects of the present invention are as follows: the patent of the present invention proposes a method based on the TDMA two-way communication protocol, which adopts a non-competitive wireless service to solve the problem of non-fixed delay caused by competitive access to wireless channels. The method adopts the TDMA two-way communication protocol to realize unified time slot allocation and scheduling of devices in the system through access point devices, thereby achieving non-competitive channel resource access and realizing a fixed delay time for two-way data communication messages, thereby meeting the requirements of applications with high delay requirements in specific occasions. Running the TDMA two-way communication protocol on the existing WiFi hardware platform enables WiFi device channel access to work under a non-competitive mechanism, ensuring the wireless transmission service delay, while taking into account the high-speed wireless hardware characteristics of the WiFi platform, and is suitable for wireless application scenarios with high requirements for wireless transmission delay and high transmission rate requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a flow chart of the TDMA two-way communication method based on the WiFi platform;

[0033] Figure 2 Wireless network topology diagram of wireless system using TDMA two-way communication protocol;

[0034] Figure 3 Schematic diagram of OFDMA resource block;

[0035] Figure 4 This is a schematic diagram of uploading cache information using a time slot method;

[0036] Figure 5 Schematic diagram of uploading cache information using OFDMA uplink mode;

[0037] Figure 6 Schematic diagram of sending uplink and downlink messages;

[0038] Figure 7 A schematic diagram of a composite message. DETAILED DESCRIPTION

[0039] The embodiments of the present invention will be further described below with reference to the accompanying drawings.

[0040] Superframes: In a PAN network, the coordinator uses a superframe structure to limit device access to the channel. This is achieved by sending beacon frames. Superframes are divided into two time periods: active and inactive. During the inactive period, the coordinator enters a low-power mode (i.e., sleep mode).

[0041] Random number algorithm: The advantages of using mathematical methods to generate random numbers are fast speed, the ability to perform recalculation checks on simulation problems, and good statistical properties.

[0042] like Figure 1As shown, the present invention provides a TDMA two-way communication method based on a WiFi platform, comprising the following steps:

[0043] S1: Perform time division to obtain several superframe periods, and then divide the superframe period into several time slots;

[0044] S2: Based on several time slots, the access point device and the client device are used to send and receive wireless packets to complete TDMA two-way communication.

[0045] The TDMA two-way data communication protocol designed based on the existing WiFi hardware platform takes advantage of the high speed and multiple hardware encoding characteristics of the hardware to implement a channel contention-free access mechanism and a high-speed, contention-free data transmission system. The wireless system of the TDMA two-way communication protocol based on the WiFi platform consists of a TDMA wireless access point device (referred to as the access point) and a TDMA client device (referred to as the client). The access point is responsible for all client access authentication requests, and runs the TDMA two-way communication protocol to implement the channel access scheduling function, and runs the client device uplink and downlink transmission channel allocation strategy. All client devices work in a unified manner according to the scheduling protocol, thereby achieving contention-free use of wireless channels and meeting the requirement of relatively fixed wireless transmission delay. The wireless network topology of the wireless system of the TDMA two-way communication protocol is as follows: Figure 2 shown.

[0046] To implement a contention-free access mechanism based on the WiFi platform, the TDMA two-way communication protocol uses a time division multiple access (TDMA) mechanism to divide time into periodic frames for management. These periodic frames are called superframes. Each superframe is further divided into several time slots based on parameters such as the actual message transmission size and wireless rate. Access point devices and client devices use these time slots for wireless packet transmission and reception, implementing functions such as system time synchronization management, time slot scheduling management, downlink channel data transmission and reception management, uplink channel data transmission and reception management, and client device access management.

[0047] In the embodiment of the present invention, each superframe period includes a beacon channel, an access channel, a trigger channel, a resource channel, a data channel and a protection channel.

[0048] The superframe period reflects how quickly the access point device polls all channels. A longer cycle time results in a longer polling interval, greater data transmission delays, a higher proportion of data frames, and higher overall system data transmission efficiency. A shorter cycle time results in faster polling, shorter scheduling intervals, a lower proportion of data frames, and lower overall system data transmission efficiency. The superframe period can be freely set based on system hardware platform performance and application requirements, with a recommended minimum unit of 1ms. It can be a manually configured fixed time or set to automatic mode. In automatic mode, the access point dynamically calculates the superframe period based on the current client device data cache size, ensuring that the TDMA scheduling algorithm for the entire system is operating optimally at all times.

[0049] In an embodiment of the present invention, the beacon channel is used to perform time synchronization management. The specific method is: using the access point device to send a beacon frame to the client device by broadcasting, using the client device to receive the beacon frame, and using the reference time of the beacon frame as the TDMA reference time of the client device to complete the time synchronization management.

[0050] The beacon channel is used to transmit beacon frames, which mark the beginning of a new superframe. These frames are broadcast by access point devices to client devices, and all client devices receive and interpret the beacon frame's contents. The access point device determines the contents of the beacon frame based on specific needs and typically includes TDMA protocol scheduling information and other information, primarily reference timing information, RF device transceiver parameters, superframe cycle time, access channel start and end slots, and trigger channel start and end slots. Upon receiving the beacon frame, the client device sets its own TDMA reference time to that of the beacon frame, achieving time synchronization among all devices in the TDMA system and enabling precise time slot allocation and usage.

[0051] In an embodiment of the present invention, the access channel is used to manage client device access, including the following sub-steps:

[0052] A21: Within the access channel width, the client device sends an association authentication request frame to the access point device using a random number algorithm.

[0053] A22: Within the access channel width, the access point device receives and processes the association authentication request frame and adds the access point device allowed to access to the authentication list;

[0054] A23: Within the superframe period, the authentication request response is made to the access point device scheduled in the data channel according to the authentication list, thereby completing the client device access management.

[0055] The access channel is used by offline client devices to send association authentication request frames to the access point. Client devices, using a random number algorithm within the access channel width, compete to obtain a time slot within the channel to transmit messages. Upon receiving the access request, the access point adds the device to its list of authorized devices. In subsequent superframes, it schedules time slots according to the TDMA protocol and prioritizes scheduling time slots within the data channel of the current cycle. It then responds to the access authentication request from the authenticating device. The access channel is optional within a superframe. The access channel's inclusion and width are determined by the access point. It can be present in every superframe or only in a single superframe. The access channel interval and channel time width can be manually configured as fixed values ​​or set to automatic mode, where the access point dynamically allocates them based on the current system traffic level.

[0056] In the embodiment of the present invention, the trigger channel is used to perform upload management, and the specific method is: using the access point device to send device resource data to the client device, obtain a trigger frame, and complete the resource acquisition trigger operation;

[0057] The trigger frame includes a client device identifier, a resource channel coding method and an uploading method for the client device to upload device resource data to a resource channel.

[0058] In the embodiment of the present invention, in the trigger channel, the uploading method of uploading the device resource data to the resource channel by using the client device includes a time slot method and an OFDMA method;

[0059] The time slot method specifically includes: uploading device resource data in different allocated time slots by the client device;

[0060] The OFDMA method is specifically as follows: the client device performs OFDMA uplink coding on the device resource data using the OFDMA uplink coding method assigned by the access point device, and sends the OFDMA uplink coded data to the access point device.

[0061] The trigger channel is used by the access point device to send device resources to all client devices, obtain trigger frames, and cache resources. The trigger frame contains the client device identifier to be queried, as well as the client device's data upload cache information frame in the resource channel. The channel resource allocation algorithm can be that each device exclusively occupies a part of the time slot, that is, each device uses a different time slot in the resource channel to upload resource data. For systems with hardware support for OFDMA uplink technology, uplink OFDMA technology can also be used to allow all devices to use different OFDMA resource blocks for OFDMA uplink encoding, and then send OFDMA encoded data to the access node device at the same time. This method requires defining the location and number of resource blocks used by each device in the OFDMA spectrum resources, the transmission rate, the transmission power and other parameters. OFDMA is a physical layer technology based on OFDM, which divides spectrum resources into multiple spectrum resource blocks and allocates them to multiple nodes for simultaneous use. The resources in OFDMA are time-frequency resources. The horizontal axis is the time axis, which represents the OFDM symbol, and the vertical axis is the spectrum axis, which represents the OFDM subcarrier. Then it is divided into multiple resource blocks RU according to the grid. The resource blocks are allocated to different users according to demand. OFDMA resource blocks are such as Figure 3 shown.

[0062] In an embodiment of the present invention, a resource channel is used for cache management; the specific method is as follows: if the trigger frame of the trigger channel indicates that a time slot method is used, the client device uploads the device cache information to the access point device in the corresponding time slot; if the trigger frame of the trigger channel indicates that an OFDMA method is used, the client device encodes the device cache information in the corresponding OFDMA resource block and uploads it to the access point device.

[0063] The resource channel is used by the client device to upload cache information to the access point device. According to the resource channel coding and usage method indicated by the trigger frame of the trigger channel, if the time slot method is used, each client device will upload the cache information in its own time slot; if the OFDMA method is used, each client device will encode the cache information in its own resource block and send it. Figure 4 As shown, OFDMA uplink mode is used to upload cache information. Figure 5 shown.

[0064] In the embodiment of the present invention, the data channel is used to manage the transmission and reception of uplink and downlink channel data. The specific method is: using the access point device to send downlink messages to the client device, and using the client device to send uplink messages to the access point device.

[0065] The data channel is used for bidirectional data transmission between the access point device and the client device, including downlink messages from the access point device to the client device, and uplink messages from the client device to the access point device. Uplink messages or downlink messages can be combined in various ways according to the control message of the access point device on the time slot allocation, which can be single or multiple, such as: single downlink and single uplink, multiple downlinks and single uplink, single downlink and multiple uplinks, multiple downlinks and multiple uplinks, etc. Figure 6 The data content transmitted by the uplink message or downlink message can be a single-function message or a multi-function message, that is, a composite message composed of multiple types of messages to achieve the most efficient use of time slot resources. Composite messages can be freely combined according to the current system's need to transmit data. The message type, sequence, and number contained in the composite message are not limited as long as the system can carry them. Figure 7 shown.

[0066] In an embodiment of the present invention, a downlink message includes a downlink message management frame, a downlink data frame, and a downlink composite frame. A specific method for sending the downlink message comprises: performing policy scheduling based on the amount, time, and priority of data cached by the access point device for all client devices, as well as the amount of downlink channel resources, generating a downlink scheduling rule, and the access point device sending the downlink message to the client device according to the downlink scheduling rule;

[0067] The uplink message includes an uplink data frame and an uplink composite frame. The specific method for sending the uplink message is as follows: the access point device performs policy scheduling based on the amount, time, and priority of uplink buffered data of all client devices, as well as the amount of uplink channel resources, to generate an uplink scheduling rule; the access point device sends an uplink data request control frame to the client device according to the uplink scheduling rule; and the client device sends the uplink message to the access point device based on the physical layer parameters and data amount contained in the uplink request control frame.

[0068] In this embodiment of the present invention, the protection channel is used for timeslot scheduling management. Specifically, an idle timeslot is set on the protection channel between the end of the previous superframe period and the beginning of the next superframe period. The width of this timeslot is automatically controlled by the access point device based on the system superframe error rate.

[0069] The protection channel is optional. For high-precision systems, the width of the protection channel can be appropriately reduced. For systems with lower timing accuracy, the width of the protection channel can be appropriately increased. If the width is 0, it means there is no protection channel in the current cycle.

[0070] The beneficial effects of the present invention are as follows: The patent of the present invention proposes a method based on the TDMA two-way communication protocol. The method adopts a non-competitive wireless service to solve the problem of non-fixed delay caused by competitive access to wireless channels. The method adopts the TDMA two-way communication protocol to realize unified time slot allocation and scheduling of devices in the system through access point devices, thereby achieving non-competitive channel resource access and realizing a fixed delay time for two-way data communication messages, which meets the requirements of applications with high delay requirements in specific occasions. Running the TDMA two-way communication protocol on the existing WiFi hardware platform enables WiFi device channel access to work under a non-competitive mechanism, ensuring the wireless transmission service delay, while taking into account the high-speed wireless hardware characteristics of the WiFi platform. It is suitable for wireless application scenarios with high requirements for wireless transmission delay and high transmission rate requirements.

[0071] Those skilled in the art will appreciate that the embodiments described herein are intended to help readers understand the principles of the present invention, and it should be understood that the scope of protection of the present invention is not limited to such specific descriptions and embodiments. Those skilled in the art can make various other specific variations and combinations based on the technical teachings disclosed in the present invention without departing from the essence of the present invention, and such variations and combinations are still within the scope of protection of the present invention.

Claims

1. A TDMA two-way communication method based on WiFi platform, characterized in that: The following steps are involved: S1: Perform time division to obtain several superframe periods, and then divide the superframe period into several time slots; S2: Based on several time slots, the access point device and the client device are used to send and receive wireless packets to complete TDMA two-way communication; Each superframe period includes a beacon channel, an access channel, a trigger channel, a resource channel, a data channel and a protection channel; The access channel is used to manage client device access, and includes the following sub-steps: A21: Within the access channel width, the client device sends an association authentication request frame to the access point device using a random number algorithm. A22: Within the access channel width, the access point device receives and processes the association authentication request frame and adds the access point device allowed to access to the authentication list; A23: During the superframe period, the authentication request response is made to the access point device in the data channel according to the authentication list, thus completing the client device access management. The data channel is used to manage the transmission and reception of uplink and downlink channel data, specifically by: using the access point device to send downlink messages to the client device, and using the client device to send uplink messages to the access point device; The downlink message includes a downlink message management frame, a downlink data frame, and a downlink composite frame; the specific method for sending the downlink message is: performing policy scheduling based on the amount, time, and priority of data cached by the access point device for all client devices and the amount of downlink channel resources, generating a downlink scheduling rule, and the access point device sending the downlink message to the client device according to the downlink scheduling rule; The uplink message includes an uplink data frame and an uplink composite frame; The specific method for sending uplink messages is as follows: the access point device performs policy scheduling based on the amount of uplink cache data, time and priority, and the amount of uplink channel resources of all client devices obtained, generates an uplink scheduling rule, and the access point device sends an uplink data request control frame to the client device according to the uplink scheduling rule. The client device sends an uplink message to the access point device based on the physical layer parameters and data quantity contained in the uplink request control frame.

2. The TDMA two-way communication method based on WiFi platform according to claim 1, characterized in that: The beacon channel is used for time synchronization management. The specific method is: using the access point device to send a beacon frame to the client device by broadcasting, using the client device to receive the beacon frame, and using the reference time of the beacon frame as the TDMA reference time of the client device to complete the time synchronization management.

3. The TDMA two-way communication method based on WiFi platform according to claim 1, characterized in that: The trigger channel is used for upload management, specifically by: using the access point device to send device resource data to the client device, obtaining a trigger frame, and completing a resource acquisition trigger operation; The trigger frame includes a client device identifier, a resource channel coding method and an uploading method for the client device to upload device resource data to a resource channel.

4. The TDMA two-way communication method based on WiFi platform according to claim 3, characterized in that: In the trigger channel, the uploading method of uploading the device resource data to the resource channel by the client device includes a time slot method and an OFDMA method; The time slot method specifically includes: uploading device resource data in different allocated time slots by the client device; The OFDMA method is specifically as follows: the client device performs OFDMA uplink coding on the device resource data using the OFDMA uplink coding method assigned by the access point device, and sends the OFDMA uplink coded data to the access point device.

5. The TDMA two-way communication method based on WiFi platform according to claim 1, characterized in that: The resource channel is used for cache management; the specific method is: if the trigger frame of the trigger channel indicates that a time slot method is used, the client device is used to upload the device cache information to the access point device in the corresponding time slot; if the trigger frame of the trigger channel indicates that an OFDMA method is used, the client device is used to encode the device cache information in the corresponding OFDMA resource block and upload it to the access point device.

6. The TDMA two-way communication method based on WiFi platform according to claim 1, characterized in that: The protection channel is used for time slot scheduling management, and the specific method is: on the protection channel, an idle time slot is set between the end of the previous superframe period and the beginning of the next superframe period.

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