CN115315007A

CN115315007A - TDMA (time division multiple Access) bidirectional communication method based on WiFi (Wireless Fidelity) platform

Info

Publication number: CN115315007A
Application number: CN202210946200.0A
Authority: CN
Inventors: 陈世伟; 张凌; 郝章辉
Original assignee: Shenzhen Forward Industrial Co Ltd
Current assignee: Shenzhen Forward Industrial Co Ltd
Priority date: 2022-08-08
Filing date: 2022-08-08
Publication date: 2022-11-08

Abstract

The invention discloses a TDMA (time division multiple access) bidirectional communication method based on a WiFi (Wireless Fidelity) platform, which comprises the following steps of: s1: time division is carried out to obtain a plurality of superframe periods, and the superframe periods are divided into a plurality of time slots; s2: and according to the plurality of time slots, performing wireless packet sending and wireless packet receiving by using the access point equipment and the client equipment to complete the TDMA two-way communication. The invention provides a two-way data communication protocol method based on a TDMA mode, which adopts a contention-free wireless medium service and solves the problems of wireless channel signal interference, high channel acquisition failure rate caused by channel contention, unstable data transmission throughput rate, uncertain data message delay time and the like.

Description

TDMA (time division multiple Access) bidirectional communication method based on WiFi (Wireless Fidelity) platform

Technical Field

The invention belongs to the technical field of TDMA communication, and particularly relates to a TDMA two-way communication method based on a WiFi platform.

Background

WiFi is the most common wireless local area network connection technology in people's life, and the WiFi mainly adopts 802.11 series wireless communication protocol standards, so people gradually get used to refer to the 802.11 protocol by WiFi. Since the first WiFi standard was developed to WiFi 7 technology in the 90 s of the 20 th century, wiFi is still the mainstream technology of personal wireless local area network standard, and the development trend of WiFi technology towards high speed and high bandwidth is more and more obvious, and WiFi technology is more and more sensitive to interference of wireless signals.

WiFi uses a carrier sense multiple access with collision avoidance (CSMA/CA) mechanism as a wireless medium access technology, which is a technology for obtaining the usage right of a wireless channel in a contention manner. The technology adopts 802.11 protocol to define a distributed coordination function, before data is transmitted, wireless equipment firstly checks whether a wireless link is in an idle state, and if the wireless link is in the idle state, the wireless equipment can occupy a wireless channel to transmit data. To avoid collision, when a transmitter occupies a frequency channel, a station that is to transmit data randomly selects a delay time and then detects whether the wireless channel is idle. In some cases, the distributed coordination function may also probe or clear the wireless channel with CTS/RTS frames, further reducing the likelihood of collisions.

With the rapid development of wireless technology, a large number of wireless devices and WiFi devices work in the ISM frequency band, so that access to wireless channels is more congested, mutual interference and collision between wireless signals are aggravated, the WiFi devices are not only subjected to channel competition of similar WiFi devices but also subjected to wireless channel interference of non-WiFi devices when working, under the condition of serious interference, wiFi hardly competes to acquire channels in time to transmit data by means of a channel competition mechanism, and the problems of unstable wireless data transmission rate, overlarge message delay, wrong transmission messages and the like are increasingly prominent, so that wireless transmission services cannot be stably provided, and the problems of service interruption and the like are caused.

Disclosure of Invention

The invention aims to solve the problem of uncertain time delay caused by channel competition due to the fact that a CSMA/CA mechanism is adopted in a WiFi standard, and provides a TDMA (time division multiple access) bidirectional communication method based on a WiFi platform.

The technical scheme of the invention is as follows: a TDMA two-way communication method based on a WiFi platform comprises the following steps:

s1: time division is carried out to obtain a plurality of superframe periods, and the superframe periods are divided into a plurality of time slots;

s2: and according to the plurality of time slots, performing wireless packet sending and wireless packet receiving by using the access point equipment and the client equipment to complete the TDMA two-way communication.

Further, each superframe period comprises a beacon channel, an access channel, a trigger channel, a resource channel, a data channel and a protection channel.

The beneficial effects of the further scheme are as follows: a plurality of channels are divided in the superframe to realize protocol control and data transmission channels, and the width of each channel can be dynamically adjusted, thereby realizing centralized management of the access point equipment to the client equipment and realizing an accurate time slot scheduling allocation strategy. The access point device dynamically adjusts the superframe period time according to index parameters of the system, such as the cache data frame, the device quantity, the transmission delay requirement and the like, so that the dynamic consideration of the data transmission efficiency and the data transmission delay in the system is achieved, and the requirements of performance indexes, such as message delay, message throughput rate and the like, on different occasions are realized.

Further, the beacon channel is used for time synchronization management, and the specific method includes: and sending a beacon frame to the client equipment by using the access point equipment in a broadcasting mode, receiving the beacon frame by using the client equipment, and finishing time synchronization management by taking the reference time of the beacon frame as the TDMA reference time of the client equipment.

Further, the access channel is used for client device access management, and comprises the following sub-steps:

a21: in the range of the access channel width, the client equipment sends an association authentication request frame to the access point equipment by using a random number algorithm;

a22: in the range of the access channel width, receiving and processing an association authentication request frame by the access point equipment, and adding the access point equipment which is allowed to be accessed into an authentication list;

a23: and in a superframe period, according to the authentication list, performing authentication request response on the scheduling of the access point equipment in the data channel, and completing the access management of the client equipment.

The beneficial effects of the above further scheme are: an access channel is designed in a superframe period, the access channel can be dynamically inserted into different superframe periods as required and the channel width of the access channel can be dynamically adjusted, and when fewer access devices are arranged, the frequency of inserting the access channel and the channel width of the access channel can be reduced, so that the maximum utilization of channel resources is achieved; when the number of the access devices is large, the frequency of inserting the access channel and the channel width of the access channel can be increased, the rapid online request processing of the client device is realized, and the access speed of the client device is improved.

Further, the triggering channel is used for uploading management, and the specific method is as follows: sending equipment resource data to client equipment by using access point equipment, acquiring a trigger frame, and finishing resource acquisition trigger operation;

the trigger frame comprises a client device identifier, a resource channel coding method and an uploading method for uploading device resource data to a resource channel by the client device.

The beneficial effects of the above further scheme are: in the invention, the access point equipment sends the trigger frame through the trigger channel to initiate the cache data detection request to the client equipment in batches and in a centralized manner, so that the data cache size of the client equipment can be acquired in time, and the accurate scheduling management of the uplink and downlink data transmission of the client equipment in the data channel is realized.

Further, in the trigger channel, an uploading method for uploading the device resource data to the resource channel by using the client device includes a time slot mode and an OFDMA mode;

the time slot mode specifically includes: uploading, by the client device, the device resource data in the allocated different time slots;

the OFDMA scheme is specifically: the client device performs OFDMA uplink coding on the device resource data by using the OFDMA uplink coding method allocated to the access point device, and transmits the OFDMA uplink coded data to the access point device.

Further, the resource channel is used for cache management; the specific method comprises the following steps: and if the trigger frame of the trigger channel indicates that a time slot mode is adopted, uploading the device cache information to the access point device by using the client device in the corresponding time slot, and if the trigger frame of the trigger channel indicates that an OFDMA mode is adopted, encoding the device cache information in the corresponding OFDMA resource block by using the client device and uploading the encoded device cache information to the access point device.

The beneficial effects of the further scheme are as follows: the resource channel utilizes an OFDMA uplink technology to realize that a plurality of devices use OFDMA resource blocks to code at the same time, and reports data to realize that the resource channel transmits data with different buffer sizes of the devices, thereby achieving the maximum utilization of the frequency spectrum resources of the resource channel.

Further, the data channel is used for performing uplink and downlink channel data transceiving management, and the specific method is as follows: and sending a downlink message to the client equipment by using the access point equipment, and sending an uplink message to the access point equipment by using the client equipment.

The beneficial effects of the further scheme are as follows: the data channel is initiated by the access point equipment to dispatch the request, can realize the single or multiple continuous transmission of the downlink message and the uplink message, realize the burst transmission of the uplink and downlink data of the client equipment, and achieve the flexible and variable priority dispatching effect.

Further, the downlink message comprises a downlink message management frame, a downlink data frame and a downlink composite frame; the specific method for sending the downlink message comprises the following steps: performing strategy scheduling according to the data quantity, time and priority levels cached by the access point equipment for all the client equipment and the quantity of downlink channel resources to generate a downlink scheduling rule, and sending a downlink message to the client equipment by the access point equipment according to the downlink scheduling rule;

the uplink message comprises an uplink data frame and an uplink composite frame; the specific method for sending the uplink message comprises the following steps: the access point device carries out strategy scheduling according to the obtained uplink cache data quantity, time and priority of all the client devices and the uplink channel resource quantity to generate an uplink scheduling rule, the access point device sends an uplink data request control frame to the client devices according to the uplink scheduling rule, and the client devices send uplink messages to the access point device according to the physical layer parameters and the data quantity contained in the uplink request control frame.

Further, the protection channel is used for performing time slot scheduling management, and the specific method is as follows: on the protection channel, an idle slot is set between the end of the last superframe period and the beginning of the next superframe period.

The beneficial effects of the above further scheme are: the width of the protection channel can be dynamically adjusted, and the maximum utilization rate of channel resources in the superframe is realized while the superframe beacon channel is protected.

The invention has the beneficial effects that: the invention provides a TDMA-based two-way communication protocol method, which adopts a competition-free wireless service to solve the problem of unfixed time delay caused by competition access of a wireless channel, adopts a TDMA two-way communication protocol to realize uniform time slot allocation and scheduling of equipment in a system through access point equipment, achieves the competition-free channel resource access, realizes the fixed delay time of a two-way data communication message, and meets the application with higher requirement on the time delay in a specific occasion. A TDMA two-way communication protocol is operated on the existing WiFi hardware platform, so that the channel access of WiFi equipment works under a non-competitive mechanism, the wireless transmission service delay is ensured, the wireless high-speed hardware characteristic of the WiFi platform is considered, and the wireless application platform is suitable for wireless application scenes with high requirements on wireless transmission delay and high transmission speed.

Drawings

FIG. 1 is a flow chart of a WiFi platform-based TDMA two-way communication method;

FIG. 2 is a wireless networking topology of a wireless system for a TDMA two-way communication protocol;

FIG. 3 is a diagram of an OFDMA resource block;

fig. 4 is a schematic diagram illustrating uploading of cache information in a time slot manner;

fig. 5 is a schematic diagram of uploading cache information in an OFDMA uplink manner;

fig. 6 is a schematic diagram of sending uplink and downlink messages;

fig. 7 is a diagram of a composite message.

Detailed Description

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

Superframe: in a PAN network, a coordinator may use a superframe structure to define access times of devices to a channel. Superframe definition can be achieved by transmitting beacon frames. The superframe is divided into two time segments: an active period and an inactive period. During the inactive period, the coordinator enters a low power consumption mode (i.e., a sleep mode).

Random number algorithm: the advantage of using mathematical method to generate random number is that it has fast speed, can carry out recalculation check to analog problem, and has better statistical property.

As shown in fig. 1, the present invention provides a TDMA two-way communication method based on a WiFi platform, comprising the following steps:

s2: and according to a plurality of time slots, carrying out wireless packet sending and wireless packet receiving by utilizing the access point equipment and the client equipment to complete the TDMA two-way communication.

A TDMA two-way data communication protocol designed based on the existing WiFi hardware platform utilizes the characteristics of high speed and various hardware codes of hardware to realize a channel contention-free access mechanism and realize a high-speed contention-free data transmission system. The wireless system of the TDMA two-way communication protocol based on the WiFi platform is composed of TDMA wireless access point equipment (access point for short) and TDMA client side equipment (client side for short), wherein the access point is responsible for accessing an authentication request to all the client sides, the TDMA two-way communication protocol is operated to realize a channel access scheduling function, an uplink and downlink transmission channel allocation strategy of the client side equipment is operated, and all the client side equipment uniformly works according to the scheduling protocol, so that the competition-free use of a wireless channel is realized, and the requirement that the wireless transmission time delay is relatively fixed is met. The wireless networking topology of a wireless system for a TDMA bi-directional communication protocol is shown in fig. 2.

In order to realize a competition-free access mechanism based on a WiFi platform, a TDMA (time division multiple access) bidirectional communication protocol adopts a time division multiple access mechanism, time is divided into periodic frames for management, the periodic frames are called superframes, each superframe is divided into a plurality of time slots according to parameters such as the actual message transmission size and wireless rate, and the like, and access point equipment and client equipment use the time slots for wireless packet sending and receiving, so that the functions of system time synchronization management, time slot scheduling management, downlink channel data receiving and sending management, uplink channel data receiving and sending management, client equipment access management and the like are realized.

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.

The superframe period reflects the speed of polling all channels by the access point equipment, the longer the period time is, the longer the polling time interval is, the larger the data transmission time delay is, the more the data frame ratio is, and the higher the overall data transmission efficiency of the system is; the shorter the cycle time, the faster the polling, the shorter the scheduling interval time, the less the data frame fraction, and the lower the overall data transmission efficiency of the system. The superframe period time can be freely set according to the performance of a system hardware platform and application requirements, the recommended minimum unit is 1ms, and the superframe period time can be manually configured fixed time or set to an automatic mode. When the superframe period is in an automatic mode, the access point device dynamically calculates the superframe period according to the data cache size of the current client device, and the TDMA scheduling algorithm of the whole system at any time is ensured to work in the optimal state.

In the embodiment of the present invention, the beacon channel is used for performing time synchronization management, and the specific method is as follows: and sending a beacon frame to the client equipment by using the access point equipment in a broadcasting mode, receiving the beacon frame by using the client equipment, and finishing time synchronization management by taking the reference time of the beacon frame as the TDMA reference time of the client equipment.

The beacon channel is used to send beacon frames that identify the beginning of a new superframe, which are sent by the access point device to the client devices in a broadcast manner, all client devices will receive and parse the content of the beacon frames. The content of the beacon frame is determined by the access point device according to specific needs, and generally includes TDMA protocol scheduling information and other information, mainly including reference time setting information, radio frequency device transceiving parameters, superframe period time, access channel start and end time slots, trigger channel start and end time slots, and other parameters. After receiving the beacon frame, the client device sets the TDMA reference time of the client device as the reference time of the beacon frame, so that the time synchronization of all devices in the TDMA system is realized, and the accurate time slot allocation and use are realized.

In the embodiment of the present invention, an access channel is used for performing access management on a client device, and includes the following sub-steps:

The access channel is used for the client device which is not on-line to send an association authentication request frame to the access point device, the client device adopts a random number algorithm in the width range of the access channel to obtain a certain time slot sending message in the channel in a competition mode, after the access point device receives the access request, the access point device adds the device which is allowed to be accessed into an authentication list, carries out time slot scheduling according to a TDMA protocol in the subsequent superframe period, preferentially distributes scheduling time slots in the data channel of the period, and makes an access authentication request response to the device in the authentication. The access channel is selectable in the superframe period, whether the superframe contains the access channel or not and the width of the access channel are allocated by the access point device, and the access channel can be available in each superframe or only one access channel in several superframe periods. The access channel interval period and the channel time width may be manually configured to fixed values, or may be set to an automatic mode, and are dynamically allocated by the access point device according to the current system busy level.

In the embodiment of the present invention, the trigger channel is used for performing upload management, and the specific method is as follows: sending equipment resource data to client equipment by using access point equipment, acquiring a trigger frame, and finishing resource acquisition trigger operation;

In the embodiment of the invention, in the trigger channel, the uploading method for uploading the device resource data to the resource channel by using the client device comprises a time slot mode and an OFDMA mode;

The trigger channel is used for the access point device to send device resources to all the client devices, to obtain a trigger frame, where the buffer resource trigger frame includes an identifier of the client device to be queried, and a channel resource allocation algorithm for the client device to upload data buffer information frames on the resource channel, where each device may monopolize a part of time slots, that is, each device uploads resource data using different time slots in the resource channel. For a system in which hardware supports OFDMA uplink technology, an uplink OFDMA technology may also be used to allow all devices to use different OFDMA resource blocks to perform OFDMA uplink coding and then transmit OFDMA coded data to an access node device at the same time, which requires defining parameters such as the position and number of resource blocks used by each device in OFDMA spectrum resources, transmission rate, and transmission power. OFDMA is an OFDM-based physical layer technique that partitions spectrum resources into multiple spectrum resource blocks, which are allocated to multiple nodes for simultaneous use. The resources in OFDMA are time-frequency resources, the abscissa is a time axis representing OFDM symbols, and the ordinate is a frequency spectrum axis representing OFDM subcarriers, and then divided into a plurality of resource blocks RU according to a grid, the resource blocks are allocated to different users according to requirements, and the OFDMA resource blocks are shown in fig. 3.

In the embodiment of the invention, the resource channel is used for cache management; the specific method comprises the following steps: and if the trigger frame of the trigger channel indicates that a time slot mode is adopted, uploading the device cache information to the access point device by using the client device in the corresponding time slot, and if the trigger frame of the trigger channel indicates that an OFDMA mode is adopted, encoding the device cache information in the corresponding OFDMA resource block by using the client device and uploading the encoded device cache information to the access point device.

The resource channel is used for the client device to upload the cache information to the access point device, and according to the resource channel coding and using method indicated by the trigger channel trigger frame, if a time slot mode is adopted, each client device uploads the cache information in the own time slot; if the OFDMA scheme is adopted, each client device encodes and transmits buffer information in its own resource block. Fig. 4 shows how to upload buffer information in a time slot manner, and fig. 5 shows how to upload buffer information in an OFDMA uplink manner.

In the embodiment of the present invention, the data channel is used for performing uplink and downlink channel data transceiving management, and the specific method is as follows: and sending a downlink message to the client equipment by using the access point equipment, and sending an uplink message to the access point equipment by using the client equipment.

The data channel is used for bidirectional data transmission between the access point device and the client device, and comprises a downlink message for transmitting data to the client device by the access point device and an uplink message for transmitting data to the access point device by the client device. There are multiple combination modes for the uplink message or the downlink message according to the indication of the ap device to the control message of time slot allocation, which may be single or multiple, for example: a single downlink and a single uplink, a plurality of downlinks and a single uplink, a single downlink and a plurality of uplinks, a plurality of downlinks and a plurality of uplinks, and the like, as shown in fig. 6. The data content transmitted by the uplink packet or the downlink packet may be a single-function packet or a multi-function packet, that is, a composite packet composed of multiple types of packets, so as to realize the most efficient use of the slot resource, the composite packet may be freely combined according to the data transmission requirement of the current system, and the type, sequence, and number of packets contained in the composite packet are not limited under the condition that the system can carry the packet, as shown in fig. 7.

In the embodiment of the invention, the downlink message comprises a downlink message management frame, a downlink data frame and a downlink composite frame; the specific method for sending the downlink message comprises the following steps: performing strategy scheduling according to the data quantity, time and priority levels cached by the access point equipment for all the client equipment and the quantity of downlink channel resources to generate a downlink scheduling rule, and sending a downlink message to the client equipment by the access point equipment according to the downlink scheduling rule;

In the embodiment of the present invention, the protection channel is used for performing time slot scheduling management, and the specific method is as follows: on the protection channel, an idle slot is set between the end of the last superframe period and the beginning of the next superframe period. The slot width is automatically controlled by the access point device based on the system superframe error rate.

The protection channel is optional, the width of the protection channel can be properly reduced for a high-precision system, the width of the protection channel can be properly increased for a system with lower timing precision, and if the width is 0, no protection channel exists in the current period.

The invention has the beneficial effects that: the invention provides a TDMA-based two-way communication protocol method, which adopts a competition-free wireless service to solve the problem of unfixed time delay caused by competition access of a wireless channel, adopts a TDMA two-way communication protocol to realize uniform time slot allocation and scheduling of equipment in a system through access point equipment, achieves the competition-free channel resource access, realizes the fixed delay time of a two-way data communication message, and meets the application with higher requirement on the time delay in a specific occasion. A TDMA two-way communication protocol is operated on the existing WiFi hardware platform, so that the channel access of WiFi equipment works under a non-competitive mechanism, the wireless transmission service delay is ensured, the wireless high-speed hardware characteristic of the WiFi platform can be considered, and the wireless application platform is suitable for wireless application scenes with high requirements on wireless transmission delay and high transmission speed.

It will be appreciated by those of ordinary skill in the art that the embodiments described herein are intended to assist the reader in understanding the principles of the invention and are to be construed as being without limitation to such specifically recited embodiments and examples. Those skilled in the art can make various other specific changes and combinations based on the teachings of the present invention without departing from the spirit of the invention, and these changes and combinations are within the scope of the invention.

Claims

1. A TDMA two-way communication method based on a WiFi platform is characterized by comprising the following steps:

2. The WiFi platform based TDMA bi-directional communication method of claim 1 wherein each said superframe period comprises beacon channel, access channel, trigger channel, resource channel, data channel and protection channel.

3. The WiFi platform-based TDMA bi-directional communication method according to claim 2, wherein said beacon channel is used for time synchronization management by: and sending a beacon frame to the client equipment by using the access point equipment in a broadcasting mode, receiving the beacon frame by using the client equipment, and finishing time synchronization management by taking the reference time of the beacon frame as the TDMA reference time of the client equipment.

4. The WiFi platform based TDMA bi-directional communication method according to claim 2 wherein said access channel is used for client device access management comprising the sub-steps of:

a23: and in a superframe period, carrying out authentication request response on the scheduling of the access point equipment in the data channel according to the authentication list, and finishing the access management of the client equipment.

5. The WiFi platform-based TDMA bi-directional communication method according to claim 2, wherein said trigger channel is used for uploading management, the specific method is: sending equipment resource data to client equipment by using access point equipment, acquiring a trigger frame, and finishing resource acquisition trigger operation;

6. The WiFi platform-based TDMA bi-directional communication method according to claim 5, wherein said trigger channel wherein said method for uploading device resource data to a resource channel by a client device comprises a time slot mode and an OFDMA mode;

7. The WiFi platform based TDMA bi-directional communication method according to claim 2, wherein said resource channels are used for cache management; the specific method comprises the following steps: and if the trigger frame of the trigger channel indicates that a time slot mode is adopted, uploading the device cache information to the access point device by using the client device in the corresponding time slot, and if the trigger frame of the trigger channel indicates that an OFDMA mode is adopted, encoding the device cache information in the corresponding OFDMA resource block by using the client device and uploading the encoded device cache information to the access point device.

8. The WiFi platform-based TDMA bidirectional communication method according to claim 2, wherein said data channel is used for performing uplink and downlink channel data transceiving management, the specific method is as follows: and sending a downlink message to the client equipment by utilizing the access point equipment, and sending an uplink message to the access point equipment by utilizing the client equipment.

9. The WiFi platform based TDMA bi-directional communication method of claim 8, wherein said downlink packet comprises a downlink packet management frame, a downlink data frame and a downlink composite frame; the specific method for sending the downlink message comprises the following steps: performing strategy scheduling according to the data quantity, time and priority levels cached by the access point equipment for all the client equipment and the quantity of downlink channel resources to generate a downlink scheduling rule, and sending a downlink message to the client equipment by the access point equipment according to the downlink scheduling rule;

10. The WiFi platform-based TDMA bi-directional communication method according to claim 2, wherein said protection channel is used for time slot scheduling management, the specific method is: on the protection channel, an idle slot is set between the end of the last superframe period and the beginning of the next superframe period.