Data transmission method, wireless network monitoring system and shared data frame structure

Abstract

Disclosed are a data transmission method, a wireless network monitoring system and a shared data frame structure. The data transmission method is applied to a wireless network supporting multiple levels of wireless terminals, the wireless network comprising a wireless access gateway connected by a low-power wide-area wireless network (LPWAN) technology of a non-cellular network and at least one level of wireless terminals. The method comprises: when a first starting terminal joins the wireless network, determining a first connection between the first starting terminal and the wireless access gateway according to topology information of the first starting terminal in the wireless network; establishing a transmission set and a transmission timing set of the first connection; determining a time length of a superframe of the wireless network as a maximum value of data generation periods of all connections in the wireless network; and assigning a time slot and a channel to each transmission in the transmission set of the first connection for each connection in the wireless network sorted in ascending order of the data generation periods. The above scheme improves the coverage range of the wireless access gateway.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to data transmission technology, in particular to a data transmission method, a wireless network monitoring system and a shared data frame structure. BACKGROUND

[0002] Low-Power Wide-Area Network (LPWAN) is one of the main hotspots of Internet of Things access network technology today. Compared with traditional mobile cellular technology and short distance communication technology, it has the characteristics of low cost, low power consumption, wide coverage and multi-connection. LoRa technology, as an emerging long-distance low-power wireless communication technology, works in the unlicensed frequency band and has flexible characteristics. Users can use LoRa technology to independently network, deploy and operate their own LoRa network, and quickly land wide-area wireless monitoring applications.

[0003] LoRa TM (Long Range) is a modulation technology that provides longer communication distances compared to similar technologies. With the development of LoRa low-power wireless communication technology, LoRa-based wireless monitoring networks are becoming increasingly diverse. LoRa Wide-Area Network (LoRaWAN) is an open network protocol, and its simple network management function and medium access protocol based on random collision are very suitable for meter reading, lighting monitoring and other ultra-low frequency periodic uplink transmission scenarios. However, it is not suitable for complex scenarios in terms of network management and transmission reliability. This mainly includes: in the case of limited field environment, it is necessary to ensure the stringent requirements of the application on the network performance and the quality of service of the network; due to the different scales, topologies and resource requirements of wireless networks in different applications, the network has diversity. For example, in monitoring applications in environments such as highways, tunnels and mountain railways, the deployment of monitoring terminals must form a multi-level network under severe shielding conditions. In a multi-level network structure, a single-path transmission strategy is difficult to ensure the reliability and efficiency of data transmission under the conditions of limited wireless environment and limited resources. Therefore, a redundant path transmission strategy can effectively improve the fault tolerance of the network. At the same time, the allocation of redundant path resources needs to consider the end-to-end data transmission relay problem in the network and the case that different application data has different generation cycles. How to ensure the reliability of monitoring data transmission in a multi-level network is a hot research topic at present.

[0004] Time division multiplexing-based wireless channel access mode is a basic mechanism to ensure transmission reliability. In a LoRa wireless network, a time slot is used as a basic transmission unit, and a terminal completes a transmission in a time slot using a fixed channel. At present, most monitoring applications are periodic tasks, so a superframe composed of several time slots is repeatedly run. Since the time slot and channel resource scheduling are allocated according to the data cycle, the transmission of data must strictly meet the cycle and delay limit conditions, so whether the current superframe can be successfully transmitted depends on a reliable time slot and channel data transmission method. SUMMARY

[0005] The present application provides a data transmission method, a wireless network monitoring system and a shared data frame structure.

[0006] In one aspect, the embodiments of the present application provide a data transmission method applied to a wireless network supporting multi-level wireless terminals, the wireless network including a wireless access gateway connected by a low-power wide-area wireless network (LPWAN) technology of a non-cellular network and at least one wireless terminal, the data transmission method including:

[0007] When a first starting terminal joins the wireless network, a first connection between the first starting terminal and the wireless access gateway is determined according to the topology information of the first starting terminal in the wireless network; wherein the first starting terminal is a wireless terminal initiating data transmission of the first connection; each starting terminal in the wireless network has a connection with the wireless access gateway, and each connection includes a main path and at least one redundant path, and the relay terminal in each path between each starting terminal and the wireless access gateway is temporarily stored in a corresponding first-in-first-out queue;

[0008] establishing a transmission set and a transmission timing set of the first connection;

[0009] The length of a superframe of the wireless network is determined as the maximum value of the data generation cycle of all connections in the wireless network; wherein the length of the superframe is used to: the wireless network runs according to the time slot and channel cycle of the superframe with the length of the superframe as the cycle, and carries the data transmission of all connections in the wireless network;

[0010] For each connection in the wireless network sorted in ascending order according to the data generation cycle, each transmission in the transmission set of the first connection is allocated a time slot and a channel.

[0011] In one exemplary embodiment, the step of establishing a transmission set and a transmission timing set of the first connection includes:

[0012] Step one, when establishing the transmission set and the transmission timing set of the first connection, put the first starting terminal in the first connection into an initialized first-in-first-out queue; wherein the first-in-first-out queue includes: for the first connection, the relay terminal and the first starting terminal in each path starting from the first starting terminal;

[0013] Step two, judge whether the first-in-first-out queue includes other wireless terminals except the first starting terminal: if the first-in-first-out queue does not include other wireless terminals, then do not generate the transmission set and the transmission timing set of the first connection; if the first-in-first-out queue includes other wireless terminals, then take the first terminal among the other wireless terminals from the first-in-first-out queue as a sending terminal of a transmission in the first connection, and proceed to step three;

[0014] Step three, according to the topology information of the wireless network, judge whether the transmission in the main path or the redundant path when the first terminal is used as the sending terminal has been allocated to the transmission resource: if there is still a transmission that has not been allocated to the transmission resource, then proceed to step four for the transmission that has not been allocated to the transmission resource; if the transmission in the main path or the redundant path when the first terminal is used as the sending terminal has all been allocated to the transmission resource, then delete the first terminal from the first-in-first-out queue, and return to step two;

[0015] Step four, judge whether the transmission path between the second terminal as the receiving terminal and the first terminal is in the main path or the redundant path of the transmission with the first terminal as the sending terminal: if the transmission path between the second terminal and the first terminal is in the main path of the transmission with the first terminal as the sending terminal, then allocate the transmission resource for the transmission between the first terminal and the second terminal according to the maximum transmission number of the main path, and add the transmission timing between each data transmission of the transmission between the first terminal and the second terminal to the transmission timing set of the first connection according to the maximum transmission number of the main path, and then proceed to step five; if the transmission path between the second terminal and the first terminal is in the redundant path of the transmission with the first terminal as the sending terminal, then proceed to step seven;

[0016] Step five, if there is still other transmission in the second transmission set with the second terminal as the receiving terminal, then add the transmission timing between each transmission in the second transmission set to the second transmission timing set corresponding to the second transmission set, and add the transmission between the first terminal and the second terminal to the second transmission set according to the transmission timing between each transmission in the second transmission set, and then proceed to step six;

[0017] Step six, increment the timing number value of the transmission according to the maximum transmission number of the main path, and then proceed to step eight;

[0018] Step seven, add the transmission timing corresponding to the transmission of the redundant path to the second transmission timing set, add the transmission between the second terminal and the first terminal to the second transmission set, which is in the redundant path of the transmission taking the first terminal as the sending terminal, and then proceed to step eight, increment the timing number value according to the maximum number of transmissions of the redundant path;

[0019] Step eight, if the number of transmissions in the transmission set taking the second terminal as the receiving terminal has been generated is equal to the in-degree of the second terminal, add the second terminal as the sending terminal to the first first-in-first-out queue.

[0020] In an exemplary embodiment, the step of determining the length of the superframe of the wireless network as the maximum value of the data generation periods of all connections in the wireless network comprises:

[0021] According to the task period information of each terminal, the data generation period is regularly processed;

[0022] The length of the superframe is determined as the longest regularized period among the regularized periods.

[0023] In an exemplary embodiment, for each connection in the wireless network sorted in ascending order according to the data generation period, the step of allocating a time slot and a channel for each transmission in the transmission set of the first connection comprises:

[0024] Determine whether the number value of the time slot allocated to the first transmission in the first connection is within the period time slot range of the first connection:

[0025] If the number value of the time slot allocated to the first transmission is not within the period time slot range of the first connection, return a scheduling failure message; wherein the returned scheduling failure message indicates that the current time slot resource is insufficient to allocate to the connection in which the first transmission is located;

[0026] If the number value of the time slot allocated to the first transmission is within the period time slot range of the first connection, the first transmission is allocated a time slot in accordance with the transmission timing set of the first connection; wherein the number value of the time slot allocated to the first transmission is greater than the number value of the time slot allocated to all transmissions before the first transmission in the transmission timing set of the first connection;

[0027] When allocating a time slot for the first transmission, determine whether a second transmission already allocated in the first time slot interferes with the first transmission to be allocated: if the second transmission does not interfere with the first transmission, allocate the transmission resource corresponding to the first time slot to the first transmission; if the second transmission interferes with the first transmission, or the number of channels allocated in the first time slot is equal to the maximum number of available channels in the first time slot, do not allocate the transmission resource corresponding to the first time slot to the first transmission.

[0028] In an exemplary embodiment, the step of judging whether the second transmission allocated in the first time slot interferes with the first transmission to be allocated comprises:

[0029] If the transmitting terminal of one of the second transmission allocated in the first time slot and the first transmission to be allocated is the same as the transmitting terminal or the receiving terminal of the other transmission, it is determined that the second transmission allocated in the first time slot will interfere with the first transmission allocated in the first time slot, and thus the transmission resource corresponding to the first time slot is not allocated to the first transmission to be allocated; wherein the transmission resource corresponding to the first time slot comprises the first time slot and the channel resource available in the first time slot;

[0030] If the receiving terminal of the second transmission allocated in the first time slot is the same as that of the first transmission to be allocated, the second transmission and the first transmission belong to the same connection, and there is no transmission timing relationship between the second transmission and the first transmission, the same time slot and channel as the second transmission are allocated to the first transmission, and the time slot type of the time slot is modified to be a high-efficiency shared time slot;

[0031] If the receiving terminal of the second transmission allocated in the first time slot is the same as that of the first transmission to be allocated and is not a wireless access gateway, and the second transmission and the first transmission do not belong to the same connection, it is determined that the second transmission will interfere with the first transmission allocated in the first time slot, and thus the transmission resource corresponding to the first time slot is not allocated to the first transmission;

[0032] If the receiving terminal of the second transmission allocated in the first time slot is the same as that of the first transmission to be allocated and is a wireless access gateway, and the first transmission and the second transmission do not belong to the same connection, the first time slot and a channel different from that occupied by the second transmission are allocated to the first transmission.

[0033] In an exemplary embodiment, the process of the first starting terminal joining the wireless network comprises:

[0034] The wireless access gateway and the wireless terminal that has joined the wireless network periodically send a broadcast in operation, and listen to the entry request sent by other wireless terminals that have not joined the wireless network when receiving the broadcast;

[0035] The first starting terminal among the other wireless terminals that have not joined the wireless network listens to the preset broadcast frequency band of the wireless network in a period of time in an over-the-air wake-up manner in operation, and adds the sender of the broadcast listened to into the neighbor list of the first starting terminal; wherein the sender is a wireless access gateway in the wireless network or a wireless terminal that has joined the wireless network;

[0036] The wireless access gateway or the wireless terminal in the neighbor list is selected as the entry relay terminal of the first starting terminal accessing the wireless network;

[0037] setting a level of the first starting terminal in the wireless network, and joining the wireless network.

[0038] In one exemplary embodiment, the step of setting the level of the first starting terminal in the wireless network comprises:

[0039] If the first starting terminal selects the wireless access gateway as the access relay terminal, the level of the first starting terminal is set to level 1,

[0040] If the first starting terminal selects the wireless terminal as the access relay terminal, the level of the first starting terminal is set to be one level lower than the level of the selected access relay terminal;

[0041] The first starting terminal sends an access request to the access relay terminal according to the resource information in the broadcast packet of the access relay terminal, and the access relay terminal forwards the access request to the network controller. The network controller replies an access confirmation to the first starting terminal according to the original path after receiving the access request. The access confirmation contains the time slot and channel resource information allocated to the first starting terminal.

[0042] The first starting terminal operates according to the allocated time slot and channel resource information after receiving the access confirmation.

[0043] In one exemplary embodiment, the step of selecting the wireless access gateway or the wireless terminal in the neighbor list as the access relay terminal of the first starting terminal to access the wireless network comprises:

[0044] determining whether the wireless access gateway exists in the neighbor list:

[0045] If the wireless access gateway exists in the neighbor list and the broadcast signal strength of the wireless access gateway is within a preset threshold range, the wireless access gateway is selected as the access relay terminal.

[0046] If the wireless access gateway does not exist in the neighbor list, the wireless terminal with a high level and a strong broadcast signal strength is selected as the access relay terminal.

[0047] If the wireless access gateway does not exist in the neighbor list and there are more than two wireless terminals at the highest level, the wireless terminal with the highest broadcast signal strength among the more than two wireless terminals at the highest level is selected as the access relay terminal.

[0048] In one exemplary embodiment, the step of allocating the time slot and the channel for each transmission in the first connected transmission set comprises: traversing each time slot in the superframe and the available channels in the time slot in ascending order of the number value of the time slot, and determining whether the transmission can be allocated to the time slot and the available channels in the time slot.

[0049] In another aspect, the embodiments of the present application provide a wireless network monitoring system, comprising a wireless access gateway connected by a low-power wide-area wireless network (LPWAN) technology of a non-cellular network and at least one wireless terminal, and the at least one wireless access gateway and the at least one wireless terminal perform the data transmission method described in any of the above embodiments.

[0050] In another aspect, the embodiments of the present application provide a shared data frame structure, which is applied to the data transmission method described in the above embodiments, when the second transmission allocated in the first time slot is the same as the receiving terminal of the first transmission to be allocated, the second transmission and the first transmission belong to the same connection, and there is no transmission timing relationship between the second transmission and the first transmission,

[0051] The shared data frame structure has a time slot preparation unit, one or more channel activity detection (CAD) units with the same length, a preamble transmission function unit, and a data frame preparation unit in the transmission preparation phase.

[0052] The sending terminal of the first transmission randomly selects a CAD unit for idle channel assessment:

[0053] If the channel is determined to be idle according to the selected CAD unit, a channel occupation signal is sent in the remaining time of the transmission preparation phase to occupy the channel for the first transmission in the first time slot.

[0054] If the channel is determined to be busy according to the selected CAD unit, it is determined that there is another terminal in addition to the sending terminal occupying the channel in the first time slot, and the first transmission is returned to a dormant state.

[0055] In the embodiments of the present application, since the length of the superframe of the wireless network is determined as the maximum value of the data generation periods of all connections in the wireless network, and for each connection in the wireless network sorted in ascending order of data generation period, each transmission in the transmission set of the connection is allocated a time slot and a channel, the problem of long-distance LoRa relay communication under the condition of existing shielding is solved, the coverage range of the wireless access gateway is improved, and the problem of being unable to deploy a wireless access gateway for long-distance LoRa relay communication under harsh conditions (for example, under the condition of existing shielding) is effectively solved by saving the number of wireless access gateway deployments.

[0056] Other features and advantages of the present application will be set forth in the following description, and in part will become apparent to those skilled in the art from the description, or can be learned by practice of the present application. Other advantages of the present application can be realized and obtained by the schemes described in the specification and drawings. BRIEF DESCRIPTION OF DRAWINGS

[0057] The accompanying drawings are included to provide a further understanding of the technical solutions of the present application, constitute a part of the specification and are used to explain the technical solutions of the present application together with the embodiments of the present application, and do not constitute a limitation on the technical solutions of the present application.

[0058] Figure 1 An example of a low power wide area wireless network monitoring system supporting a multi-level wireless network is shown;

[0059] Figure 2 The network topology of the connection of the wireless terminal n1 as a starting terminal is generated according to Figure 1 The schematic diagram of the transmission set and the transmission timing set generated according to the network topology of the connection of the wireless terminal n1 as a starting terminal in the embodiment of the present application;

[0060] Figure 3 The flowchart of the data transmission method provided in the embodiment of the present application;

[0061] Figure 4 The schematic diagram of the shared data frame structure provided in the embodiment of the present application. DETAILED DESCRIPTION

[0062] The present application describes a plurality of embodiments, but the description is exemplary rather than limiting, and it is obvious to those skilled in the art that there can be more embodiments and implementation schemes within the scope of the embodiments described in the present application. Although many possible combinations of features are shown in the drawings and discussed in the specific embodiments, many other combinations of the disclosed features are also possible. Unless specifically limited, any feature or element of any embodiment can be used in combination with any other feature or element of any other embodiment, or can replace any other feature or element of any other embodiment.

[0063] The present application includes and contemplates combinations of features and elements known to those skilled in the art. The embodiments, features and elements disclosed in the present application can also be combined with any conventional features or elements to form a unique inventive scheme defined by the claims. Any feature or element of any embodiment can also be combined with features or elements from other inventive schemes to form another unique inventive scheme defined by the claims. Therefore, it should be understood that any feature shown and / or discussed in the present application can be implemented alone or in any appropriate combination. Therefore, the embodiments are not limited other than as set forth in the claims and their equivalents. In addition, various modifications and changes can be made within the scope of protection of the appended claims.

[0064] Furthermore, in describing representative embodiments, the specification can have presented the method and / or process as a particular sequence of steps. However, to the extent that the method or process depends on the particular order of steps, this description should not be construe to imply that the steps are necessarily order dependent. Other steps could be performed in other sequences or omitted without departing from the scope of the method or process. As will be understood by those skilled in the art, the particular sequence of steps described is illustrative. Thus, although specific implementation of this method and / or process have been disclosed, other implementations will become apparent to those skilled in the art upon reading this disclosure. The scope of the method and / or process described is not to be limited by the specific sequences of steps described.

[0065] To achieve the above object, the embodiments of the present application provide a data transmission method, which is applied to a low-power wide-area wireless network monitoring system supporting multi-level wireless networks. The monitoring system comprises a user client, an application server, a network controller, a wireless access gateway and at least one wireless terminal connected in sequence. The connection between the user client, the application server, the network controller and the wireless access gateway can be wired connection according to RS232 protocol, IEEE1934 protocol or using optical fiber and the like, can be wireless connection according to IEEE802.11a / b / g / n / ac protocol and the like, or wired connection combined with wireless connection is applied to the connection between the user client, the application server, the network controller and the wireless access gateway. The wireless access gateway and the at least one wireless terminal are connected by using low-power wide-area wireless network (LPWAN) technology of non-cellular network.

[0066] LPWAN is a classification of low-power long-distance communication technology in wireless network technology, and various network communication technologies are included in the classification, including LoRa (Long Range), UNB (Ultra Narrow Band), NB-IoT (Narrow Band Internet of Things), eMTC (enhanced Machine-Type Communication) and the like. Among them, NB-IoT and eMTC belong to cellular network communication technology and work in licensed frequency bands. LoRa and UNB belong to non-cellular network communication technology and work in unlicensed frequency bands. Further, LoRa can work in unlicensed frequency bands in China. LoRaWAN is an open network protocol based on LoRa technology, and Sigfox and the like are private network protocols based on UNB technology.

[0067] Based on the above, in the present application, the wireless connection between the wireless access gateway and the at least one level of wireless terminal can use any non-cellular network LPWAN technology (including LoRa, UNB, etc.).

[0068] The application server is connected with the network controller, and is configured to generate task information according to the monitoring task configuration. The monitoring task is configured by a user and stored in the application server. The application server generates the task information according to the configuration, and transmits the task information to the network controller. The task information mainly includes all the wireless terminal data acquisition interface types, data acquisition periods and data upload periods.

[0069] The network controller is connected with the application server, and is configured to generate task configuration for the terminal according to the task information. At the same time, the network controller generates a terminal transmission resource allocation table through a multi-level network reliable transmission method according to the multi-level network topology information configured by the user. The network controller is also connected with the wireless access gateway, and is configured to communicate with the terminal.

[0070] The wireless access gateway is wiredly connected with the network controller, and is wirelessly connected with the wireless terminal, and is configured to convert the protocol when the wireless terminal communicates with the network controller, i.e. to convert the wireless communication protocol (including the low-power wide-area wireless network LPWAN technology using non-cellular network) into the wired communication protocol. The wireless access gateway includes a gateway system and a radio frequency module. The radio frequency module can include an SX1302 LoRa gateway chip, and can work in the 470-510 MHz frequency band, and has parallel 8-channel uplink communication and single-channel downlink communication.

[0071] The wireless terminal is a field data acquisition terminal, and communicates with the wireless access gateway using the low-power wide-area wireless network LPWAN technology of non-cellular network, and is configured to upload the collected device information or sensor information to the application server through the wireless network, the wireless access gateway and the network controller. The wireless terminal joins the wireless network according to the network joining method, and then enters the periodic data transmission state according to the allocated transmission resource.

[0072] Figure 1 An example of the monitoring system is shown. Figure 1The monitoring system in the application comprises a user client, an application server, a network controller, a wireless access gateway and wireless terminals connected in sequence. The wireless access gateway and at least one level of wireless terminals are connected by using the LPWAN technology of the non-cellular network. The wireless access gateway can be directly connected with multiple wireless terminals by using the LPWAN technology of the non-cellular network, and the wireless terminals directly connected with the wireless access gateway can also be directly connected with other wireless terminals by using the LPWAN technology of the non-cellular network. By analogy, in a monitoring system, there can be multiple levels of wireless terminals connected by using the LPWAN technology of the non-cellular network. And in a monitoring system, there is a wireless network supported by the LPWAN technology of the non-cellular network, and the wireless network comprises the wireless terminals and the wireless access gateway. In the wireless network, the data transmission from a terminal to the wireless access gateway is called a "connection", and a terminal has only one connection to the wireless access gateway. A connection comprises multiple paths, and there can be multiple transmissions on the same path. Therefore, the data transmission method provided by the embodiments of the application allocates time slots and channel resources for each transmission of each connection.

[0073] As described above, in the wireless network, a connection comprises a starting terminal, and can also comprise one or more relay terminals. In addition, in the wireless network, a wireless terminal can serve as a starting terminal in a connection, and at the same time, can also serve as a relay terminal in another connection. In combination with the above description, Figure 1 As described above, in the wireless network, a connection comprises a starting terminal, and can also comprise one or more relay terminals. In addition, in the wireless network, a wireless terminal can serve as a starting terminal in a connection, and at the same time, can also serve as a relay terminal in another connection. In combination with the above description, Figure 1 As shown in the figure, the user configures the multi-level network topology information. The connection from the wireless terminal n1 to the wireless access gateway needs to be transmitted through the multi-level network relay, so as to perform data transmission. In the transmission path, each relay terminal has a main path and a redundant path. For the connection with the wireless terminal n1 as the starting terminal, Figure 1 In the figure, the main path of the connection is shown by a solid line, and the redundant path of the connection is shown by a dashed line. For example, the main path of the wireless terminal n1 is the terminal n2 as shown by the solid line in the figure, and the redundant path of the wireless terminal n1 is the wireless terminal n3 as shown by the dashed line in the figure. When it is determined that the data transmission of the wireless terminal n1 to the wireless terminal n2 through the main path fails, the wireless terminal n1 performs data transmission to the wireless terminal n3 through the redundant path.

[0074] In addition, according to the rule of the embodiments of the application, in a connection, the wireless terminal directly connected with the wireless access gateway is called a first-level wireless terminal, and since the starting terminal has a main path and a redundant path (except for the case that the starting terminal is directly connected with the wireless access gateway), multiple first-level wireless terminals are involved in a connection. For the connection with the wireless terminal n1 as the starting terminal, as shown in the figure, Figure 1The wireless terminals n6, n7, n8 and n9 directly connected with the wireless access gateway are the first-level wireless terminals; the wireless terminal n4 directly connected with the first-level wireless terminals n6 and n7 is the second-level wireless terminal, and the wireless terminal n5 directly connected with the first-level wireless terminals n8 and n9 is also the second-level wireless terminal, in addition, the wireless terminal n2 directly connected with the first-level wireless terminal n6 is also the second-level wireless terminal; the wireless terminals n2 and n3 directly connected with the second-level wireless terminal n4 are the third-level wireless terminals, and the wireless terminal n3 directly connected with the second-level wireless terminal n5 is the third-level wireless terminal. As can be seen, the wireless terminal n2 can be the second-level wireless terminal in one path and the third-level wireless terminal in another path in this connection. Finally, for the connection with the wireless terminal n1 as the starting terminal, the wireless terminal n2 connects the starting terminal n1 through the main path, at this time the starting terminal n1 is the fourth-level wireless terminal or the third-level wireless terminal; and the wireless terminal n3 connects the starting terminal n1 through the redundant path, at this time the starting terminal n1 is the fourth-level wireless terminal. There can be many wireless terminals in the wireless network monitoring system, however, not all the wireless terminals are applied in one connection, for example, in the connection with the wireless terminal n1 as the starting terminal, the wireless terminal n1 is the idle terminal, that is, the wireless terminal n1 is not involved in the data transmission in this connection. However, the idle terminal (for example, the wireless terminal n1) in this connection can be the starting terminal or the relay terminal in other connections, in addition, the relay terminal (for example, the wireless terminal n2) in the connection with the wireless terminal n1 as the starting terminal can be the starting terminal or the relay terminal in other connections. Taking the wireless terminal n2 as an example, when being the starting terminal or the relay terminal in other connections, the wireless terminal n2 can follow, however, is not necessarily to follow the path in the connection with the wireless terminal n1 as the starting terminal; for example, the wireless terminal n2 can perform data transmission with the wireless terminals n4 and / or n6 when being the starting terminal or the relay terminal in other connections, however, can also perform data transmission with the wireless terminal n5.

[0075] In summary, in a low-power wide-area wireless network monitoring system supporting multi-level wireless networks, the wireless network can include multiple connections, each connection can include multiple paths, and each path can include multiple transmissions. Each wireless terminal in the wireless network can be involved in multiple transmissions. The data transmission method provided by the embodiments of the present application involves the allocation of time slot resources and the allocation of channel resources of each wireless terminal in the wireless network, that is, the allocation of the transmission set and the transmission timing set of the wireless network of the low-power wide-area wireless network monitoring system as a whole.

[0076] Figure 2 The data transmission method provided by the embodiments of the present application is based on Figure 1Fig. 1 is a schematic diagram of a transmission set and a transmission timing set generated according to a network topology of a connection with wireless terminal n1 as a starting terminal in the wireless network. Figure 2 In Fig. 1, for example, the transmission with serial number ② is x(n1, n2), which indicates that the sending terminal of the transmission is wireless terminal n1 and the receiving terminal is wireless terminal n2; there is a transmission timing e(2, 4) between the transmission with serial number ② x(n1, n2) and the transmission with serial number ④ x(n2, n6), which indicates that the fourth transmission x(n2, n6) in the connection must be performed after the second transmission x(n1, n2).

[0077] As shown in Fig. 1, the embodiment of the present application provides a data transmission method. Figure 3 The data transmission method includes steps S103-S109.

[0078] Step S103, when a first starting terminal joins a wireless network, determining a first connection between the first starting terminal and a wireless access gateway according to topology information of the first starting terminal in the wireless network.

[0079] The first starting terminal is a wireless terminal initiating data transmission of the first connection; each starting terminal in the wireless network has a connection with the wireless access gateway, and each connection includes a main path and at least one redundant path, and a relay terminal in each path between each starting terminal and the wireless access gateway is temporarily stored in a corresponding first-in-first-out queue;

[0080] Step S105, establishing a transmission set and a transmission timing set of the first connection.

[0081] For a connection, the relay terminals of each path are temporarily stored through a first-in-first-out queue starting from a starting terminal, then each relay terminal in the queue is traversed to generate a main path and a redundant path transmission with each relay terminal as a sending terminal, thereby constituting the transmission set of the connection, and a timing to be followed by each transmission is generated to constitute the transmission timing set.

[0082] In an exemplary embodiment, step S105 includes:

[0083] Step one, when establishing the transmission set and the transmission timing set of the first connection, placing the first starting terminal in the first connection into an initialized first first-in-first-out queue.

[0084] The first first-in-first-out queue includes the relay terminals in each path starting from the first starting terminal and the first starting terminal for the first connection.

[0085] Step two, judging whether the first first-in-first-out queue includes other wireless terminals except the first starting terminal: if the first first-in-first-out queue does not include other wireless terminals, the transmission set and the transmission timing set of the first connection are not generated any more; if the first first-in-first-out queue includes other wireless terminals, a first terminal among the other wireless terminals is taken out from the first first-in-first-out queue as a sending terminal of a transmission among the first connection, and step three is performed.

[0086] Wherein, the first-in-first-out queue being empty indicates that the starting terminal is directly connected to the wireless access gateway.

[0087] Step three, judging whether the transmission in the main path or the redundant path when the first terminal is taken as the sending terminal has been allocated to the transmission resource according to the topology information of the wireless network: if there is still transmission not allocated to the transmission resource, step four is performed for the transmission not allocated to the transmission resource; if the transmission in the main path or the redundant path when the first terminal is taken as the sending terminal has all been allocated to the transmission resource, the first terminal is deleted from the first first-in-first-out queue, and returns to step two.

[0088] Step four, judging whether the transmission path between the second terminal as the receiving terminal and the first terminal is in the main path or the redundant path of the transmission with the first terminal as the sending terminal: if the transmission path between the second terminal and the first terminal is in the main path of the transmission with the first terminal as the sending terminal, the transmission resource is allocated to the transmission between the first terminal and the second terminal according to the maximum transmission number of the main path, and the transmission timing set of the second connection is added to the transmission timing set of the first connection according to the maximum transmission number of the main path, and then step five is performed; if the transmission path between the second terminal and the first terminal is in the redundant path of the transmission with the first terminal as the sending terminal, step seven is performed.

[0089] Step six, the timing number value of the transmission is incremented according to the maximum transmission number of the main path, and then step eight is entered;

[0090] Step seven, the transmission timing corresponding to the transmission of the redundant path is added to the second transmission timing set, the transmission between the second terminal and the first terminal in the redundant path of the transmission with the first terminal as the sending terminal is added to the second transmission set, and the timing number value is incremented according to the maximum transmission number of the redundant path, and then step eight is performed.

[0091] Step eight, if the number of the transmission in the transmission set with the second terminal as the receiving terminal that has been generated is equal to the in-degree of the second terminal, the second terminal is added to the first first-in-first-out queue as the sending terminal.

[0092] The number of elements in the transmission set is equal to the in-degree, which means that the terminal cannot be a receiving terminal of more new transmissions. Adding the terminal to the first-in-first-out queue means that the terminal is no longer considered as a receiving terminal of other transmissions that have not been allocated channel resources and timing resources. From this moment, the terminal is added to the first-in-first-out queue as a sending terminal in addition to being a receiving terminal of the transmission that has been allocated to the terminal.

[0093] In step S107, the length of the superframe of the wireless network is determined as the maximum of the data generation periods of all connections in the wireless network.

[0094] The length of the superframe is used to: periodically, with the length of the superframe, the wireless network operates according to the time slots and channel periods of the superframe, and carries the data transmission of all connections in the wireless network.

[0095] In step S109, for each connection in the wireless network sorted according to the data generation period from small to large, a time slot and a channel are allocated for each transmission in the transmission set of the first connection.

[0096] In an exemplary embodiment, step S107 includes:

[0097] According to the task period information of each terminal, the data generation period is regularized; and

[0098] The length of the superframe is determined as the longest regularized period among the regularized periods.

[0099] All data generation periods are defined as 2a·pm, where a is an integer in [0, b] and pm is the minimum period among all periods. For example, there are N connections in the wireless network, and the transmission period of the kth connection is pk. The data generation period cannot be completely matched with the specified value, so all data periods are regularized. pk represents the regularized period, and the period of each connection is processed as follows:

[0100]

[0101] In the wide-area Internet of Things communication protocol, the LR-WPAN network can be organized with a superframe as a period. Each superframe starts with a beacon frame sent by the network coordinator, which is used for time synchronization of wireless terminals in the superframe. The resource allocation in the superframe is performed after the wireless terminal completes the network entry. The network controller has issued the allocated resources to each wireless terminal. Each wireless terminal performs data transmission according to the allocated time slot and channel, and performs tasks or sleeps during the remaining time.

[0102] The time length of one super frame is represented by T, which should be equal to the longest period in the data stream, i.e. T = max{p(k), k = 0, 1,..., N}. By determining the time length of the super frame as the time length of the longest period among the regularized periods, all connections involved in the wireless network can complete data transmission once during one super frame.

[0103] When allocating resources, the time length of one super frame is the time length of the longest period, so a connection with a short period needs to appear multiple times in the super frame. For example, if the super frame time is 10 seconds and the period of a connection is 2 seconds, the connection needs to appear 5 times in 10 seconds, and 5 transmission resources need to be allocated. The order of the periods from small to large is based on the principle of allocating resources to connections appearing multiple times in one super frame first, and then allocating resources to connections appearing fewer times, so that the number of interference times is reduced when resources are allocated, and the success rate of resource allocation is improved.

[0104] In an exemplary embodiment, step S109 comprises: judging whether the number value of the time slot to which the first transmission of the first connection is allocated is within the period time slot range of the first connection:

[0105] If the number value of the time slot to which the first transmission is allocated is not within the period time slot range of the first connection, a scheduling failure message is returned; wherein the returned scheduling failure message indicates that the current time slot resource is insufficient to allocate to the connection in which the first transmission is located;

[0106] If the number value of the time slot to which the first transmission is allocated is within the period time slot range of the first connection, the first transmission is allocated a time slot in accordance with the transmission timing set of the first connection; wherein the number value of the time slot to which the first transmission is allocated is greater than the number value of the time slot to which all transmissions before the first transmission in the transmission timing set of the first connection are allocated.

[0107] When allocating a time slot for the first transmission, it is judged whether the second transmission already allocated in the first time slot interferes with the first transmission to be allocated: if the second transmission does not interfere with the first transmission, the first transmission is allocated the transmission resource corresponding to the first time slot; if the second transmission interferes with the first transmission, or the number of channels already allocated in the first time slot is equal to the maximum number of available channels in the first time slot, the first transmission is not allocated the transmission resource corresponding to the first time slot.

[0108] In an exemplary embodiment, the step of judging whether the second transmission already allocated in the first time slot interferes with the first transmission to be allocated comprises:

[0109] If the receiving terminal of the second transmission allocated in the first time slot and the first transmission to be allocated is the same, and the second transmission and the first transmission belong to the same connection, and there is no transmission timing relationship between the second transmission and the first transmission, the same time slot and channel as the second transmission are allocated to the first transmission, and the time slot type of the time slot is modified to an efficient shared time slot.

[0110] If the receiving terminal of the second transmission allocated in the first time slot and the first transmission to be allocated is the same, and the second transmission and the first transmission belong to the same connection, and there is no transmission timing relationship between the second transmission and the first transmission, the same time slot and channel as the second transmission are allocated to the first transmission, and the time slot type of the time slot is modified to an efficient shared time slot.

[0111] If the receiving terminal of the second transmission allocated in the first time slot and the first transmission to be allocated is the same, and the second transmission and the first transmission belong to the same connection, and there is no transmission timing relationship between the second transmission and the first transmission, the same time slot and channel as the second transmission are allocated to the first transmission, and the time slot type of the time slot is modified to an efficient shared time slot.

[0112] If the receiving terminal of the second transmission allocated in the first time slot and the first transmission to be allocated is the same, and the second transmission and the first transmission belong to the same connection, and there is no transmission timing relationship between the second transmission and the first transmission, the same time slot and channel as the second transmission are allocated to the first transmission, and the time slot type of the time slot is modified to an efficient shared time slot.

[0113] In an exemplary embodiment, the process of the first starting terminal joining the wireless network in step S103 comprises:

[0114] The wireless access gateway and the wireless terminals that have joined the wireless network periodically send broadcasts in runtime, and listen to the entry requests sent by other wireless terminals that have not joined the wireless network when receiving the broadcasts;

[0115] The first starting terminal among the other wireless terminals that have not joined the wireless network listens to the preset broadcast frequency band of the wireless network in runtime in an air wake-up manner for a period of time, and adds the sender of the broadcast listened to into the neighbor list of the first starting terminal; wherein the sender is a wireless access gateway in the wireless network or a wireless terminal that has joined the wireless network;

[0116] The wireless access gateway or the wireless terminal in the neighbor list is selected as the entry relay terminal of the first starting terminal accessing the wireless network;

[0117] The level of the first starting terminal in the wireless network is set, and the first starting terminal joins the wireless network.

[0118] In one exemplary embodiment, the step of setting the level of the first originating terminal in the wireless network comprises:

[0119] If the first originating terminal selects a wireless access gateway as the access relay terminal, the level of the first originating terminal is set to level 1,

[0120] If the first originating terminal selects a wireless terminal as the access relay terminal, the level of the first originating terminal is set to be one level lower than the level of the selected access relay terminal;

[0121] The first originating terminal sends an access request to the access relay terminal according to the resource information in the broadcast packet of the access relay terminal, and the access relay terminal forwards the access request to the network controller. After receiving the access request, the network controller replies an access confirmation according to the original path. The access confirmation contains the time slot and channel resource information allocated for the first originating terminal.

[0122] After receiving the access confirmation, the first originating terminal operates according to the allocated time slot and channel resource information.

[0123] In one exemplary embodiment, the step of selecting a wireless access gateway or a wireless terminal in the neighbor list as the access relay terminal for the first originating terminal to access the wireless network comprises:

[0124] If the neighbor list contains a wireless access gateway:

[0125] If the neighbor list contains a wireless access gateway and the broadcast signal strength of the wireless access gateway is within a preset threshold range, the wireless access gateway is selected as the access relay terminal.

[0126] If the neighbor list does not contain a wireless access gateway, a wireless terminal with a high level and strong broadcast signal strength is selected as the access relay terminal.

[0127] If the neighbor list does not contain a wireless access gateway and contains more than two wireless terminals at the highest level, a wireless terminal with the highest broadcast signal strength among the more than two wireless terminals at the highest level is selected as the access relay terminal.

[0128] In one exemplary embodiment, the step S109 comprises: traversing each time slot in the superframe and the available channels in the time slot in ascending order of the number value of the time slot, judging whether the transmission can be allocated to the time slot and the available channels in the time slot, and allocating the time slot and the available channels to the transmission that is judged to be able to be allocated to the time slot and the available channels in the time slot.

[0129] On the other hand, the embodiment of the present application provides a wireless network monitoring system, which comprises: Figure 1As shown, the wireless access gateway connected by the low-power wide-area wireless network (LPWAN) technology of a non-cellular network and the at least one wireless terminal perform the data transmission method described in any of the above embodiments.

[0130] In another aspect, the embodiment of the present application provides a shared data frame structure, which is applied to the case that the receiving terminal of the second transmission allocated in the first time slot is the same as the first transmission to be allocated, the second transmission and the first transmission belong to the same connection, and there is no transmission time sequence relationship between the second transmission and the first transmission. Figure 4 As shown,

[0131] The shared data frame structure has a time slot preparation unit in the transmission preparation stage, one or more CAD (Channel Activity Detection) units with the same length, a preamble transmission function unit, and a data frame preparation unit.

[0132] The sending terminal of the first transmission randomly selects a CAD unit for idle channel assessment:

[0133] If it is determined that the channel is idle according to the selected CAD unit, a channel occupation signal is sent in the remaining time of the transmission preparation stage to occupy the channel for the first transmission in the first time slot.

[0134] If it is determined that the channel is busy according to the selected CAD unit, it is determined that there is another terminal except the sending terminal occupying the channel in the first time slot, and the first transmission is returned to the dormant state.

[0135] The reliable transmission data transmission method based on the multi-path transmission strategy proposed in the embodiment of the present application can realize that the multi-level terminals can transmit data through multiple paths, can increase the fault tolerance of the network to the wireless link failure, and thus effectively improves the reliability of the multi-level network data transmission.

[0136] Those of ordinary skill in the art will realize and understand that all or some of the steps in the methods disclosed above and the functional modules / units in the systems and devices can be implemented as software, firmware, hardware, and appropriate combinations thereof. In hardware implementation, the division between the functional modules / units mentioned in the above description does not necessarily correspond to the division of physical components; for example, one physical component can have multiple functions, or one function or step can be performed by several physical components in cooperation. Some or all of the components can be implemented as software executed by a processor, such as a digital signal processor or a microprocessor, or as hardware, or as an integrated circuit, such as an application-specific integrated circuit. Such software can be distributed on computer-readable media, which can include computer storage media (or non-transitory media) and communication media (or transitory media). As is well known to those of ordinary skill in the art, the term computer storage media includes volatile and non-volatile, removable and non-removable media implemented in any method or technology for storage of information such as computer readable instructions, data structures, program modules or other data. Computer storage media includes, but is not limited to, RAM, ROM, EEPROM, flash memory or other memory technology, CD-ROM, digital versatile disks (DVD) or other optical disk storage, magnetic cassettes, magnetic tapes, magnetic disk storage or other magnetic storage devices, or any other medium which can be used to store the desired information and which can be accessed by a computer. Furthermore, it is common and well understood by those of ordinary skill in the art that communication media typically embodies computer readable instructions, data structures, program modules or other data in a modulated data signal such as a carrier wave or other transport mechanism and can include any information delivery media.

Claims

1. A data transmission method applied to a wireless network supporting multiple levels of wireless terminals, the wireless network comprising a wireless access gateway connected using Low Power Wide Area Network (LPWAN) technology (non-cellular network) and at least one level of wireless terminals, characterized in that, The data transmission method includes: When the first initiating terminal joins the wireless network, a first connection between the first initiating terminal and the wireless access gateway is determined based on the topology information of the first initiating terminal in the wireless network; wherein, the first initiating terminal is the wireless terminal that initiates the data transmission of the first connection; each initiating terminal in the wireless network has a connection with the wireless access gateway, and each connection includes a main path and at least one redundant path, and relay terminals in each path between each initiating terminal and the wireless access gateway are temporarily stored in the corresponding first-in-first-out queue; Establish the transmission set and transmission timing set of the first connection; The duration of the superframe of the wireless network is determined to be the maximum value of the data generation period of all connections in the wireless network; wherein, the duration of the superframe is used for: the wireless network to operate according to the time slot and channel period of the superframe with the duration of the superframe as the period, to carry the data transmission of all connections in the wireless network; For each connection in the wireless network that is sorted in ascending order of data generation period, a time slot and a channel are allocated to each transmission in the transmission set of the first connection.

2. The data transmission method according to claim 1, wherein, The steps of establishing the transmission set and transmission timing set of the first connection include: Step 1: When establishing the transmission set and transmission timing set of the first connection, the first starting terminal in the first connection is placed into the initialized first first-in-first-out queue; wherein, the first first-in-first-out queue includes: for the first connection, the relay terminal in each path starting from the first starting terminal and the first starting terminal. Step 2: Determine whether the first FIFO queue includes other wireless terminals besides the first starting terminal. If the first FIFO queue does not include other wireless terminals, then the transmission set and transmission timing set of the first connection will not be generated again. If the first FIFO queue includes other wireless terminals, then the first terminal among the other wireless terminals in the first FIFO queue will be taken as the sending terminal of the first connection, and then proceed to Step 3. Step 3: Based on the topology information of the wireless network, determine whether the transmission in the main path or redundant path has been allocated transmission resources when the first terminal is used as the sending terminal. If there are still transmissions that have not been allocated transmission resources, proceed to Step 4 for those transmissions. If the transmissions in the main path or redundant path have been allocated transmission resources when the first terminal is used as the sending terminal, remove the first terminal from the first first-in-first-out queue and return to Step 2. Step four: Determine whether the transmission path between the second terminal (as the receiving terminal) and the first terminal is a main path or a redundant path in which the first terminal is the sending terminal. If the transmission path between the second terminal and the first terminal is a main path in which the first terminal is the sending terminal, then allocate transmission resources for the transmission between the first terminal and the second terminal according to the maximum number of transmissions on the main path, and add the transmission timing sequence between each data transmission between the second terminal and the first terminal to the transmission timing set of the first connection according to the maximum number of transmissions on the main path, and then proceed to step five. If the transmission path between the second terminal and the first terminal is a redundant path in which the first terminal is the sending terminal, then proceed to step seven. Step 5: If there are other transmissions in the second transmission set with the second terminal as the receiving terminal, add the transmission timing sequence between each transmission in the second transmission set to the second transmission timing set corresponding to the second transmission set, and add the transmission between the first terminal and the second terminal to the second transmission set according to the transmission timing sequence between each transmission in the second transmission set, and then proceed to step 6. Step six: Carry over the transmission timing number value according to the maximum number of transmissions on the main path, and then proceed to step eight; Step 7: Add the transmission timing corresponding to the transmission of the redundant path to the second transmission timing set, add the transmission between the second terminal and the first terminal to the second transmission set that is a redundant path in the transmission with the first terminal as the sending terminal, and carry over the timing number value according to the maximum number of transmissions of the redundant path, and then proceed to step 8. Step 8: If the number of transmissions in the already generated transmission set with the second terminal as the receiving terminal is equal to the in-degree of the second terminal, then add the second terminal as the sending terminal to the first FIFO queue.

3. The method according to claim 1, wherein, The step of determining the duration of the superframe of the wireless network as the maximum value of the data generation period of all connections in the wireless network includes: Based on the task cycle information of each terminal, the data generation cycle is regularized; and The duration of the superframe is determined to be the longest regularization period among the regularization processing periods.

4. The data transmission method according to claim 1, wherein, The step of allocating time slots and channels for each transmission in the transmission set of the first connection, after sorting the connections in the wireless network according to their data generation periods from smallest to largest, includes: Determine whether the time slot number allocated to the first transmission in the first connection is within the periodic time slot range of the first connection: If the slot number allocated to the first transmission is not within the periodic slot range of the first connection, a scheduling failure message is returned; wherein, the returned scheduling failure message indicates that the current slot resources are insufficient to be allocated to the connection where the first transmission is located. If the slot number allocated to the first transmission is within the periodic slot range of the first connection, then the first transmission is allocated a slot according to the transmission timing set of the first connection; wherein, the slot number allocated to the first transmission is greater than the slot number allocated to all transmissions in the transmission timing set of the first connection prior to the first transmission. When allocating a time slot for the first transmission, it is determined whether the second transmission already allocated in the first time slot interferes with the first transmission to be allocated: if the second transmission does not interfere with the first transmission, then the transmission resources corresponding to the first time slot are allocated to the first transmission; if the second transmission interferes with the first transmission, or if the number of channels already allocated in the first time slot is equal to the maximum number of available channels in the first time slot, then the transmission resources corresponding to the first time slot are not allocated to the first transmission.

5. The data transmission method according to claim 4, wherein, The step of determining whether the second transmission already allocated in the first time slot interferes with the first transmission to be allocated includes: For a second transmission already allocated in a first time slot and a first transmission to be allocated, if the sending terminal of one transmission is the same as the sending terminal or receiving terminal of the other transmission, it is determined that the second transmission already allocated in the first time slot will interfere with the first transmission allocated in the first time slot. Therefore, the transmission resources corresponding to the first time slot are not allocated to the first transmission to be allocated. The transmission resources corresponding to the first time slot include the first time slot and the channel resources available in the first time slot. If the receiving terminal of the second transmission already allocated in the first time slot is the same as that of the first transmission to be allocated, the second transmission and the first transmission belong to the same connection, and there is no transmission timing relationship between the second transmission and the first transmission, then the first transmission is allocated the same time slot and channel as the second transmission, and the time slot type of the time slot is modified to efficient shared time slot. If the receiving terminal of the second transmission already allocated in the first time slot is the same as that of the first transmission to be allocated and is not a wireless access gateway, and the second transmission and the first transmission do not belong to the same connection, then it is determined that the second transmission will interfere with the first transmission allocated in the first time slot, and therefore the transmission resources corresponding to the first time slot are not allocated to the first transmission. If the receiving terminal of the second transmission already allocated in the first time slot and the first transmission to be allocated are both wireless access gateways, and the first transmission and the second transmission do not belong to the same connection, then the first transmission is allocated a first time slot and a channel different from the channel occupied by the second transmission.

6. The data transmission method according to claim 1, wherein, The process of the first initiating terminal joining the wireless network includes: The wireless access gateway periodically broadcasts to wireless terminals already in the wireless network during operation, and listens for network access requests sent by other wireless terminals not in the wireless network when they receive the broadcast. The first initiating terminal, among the other wireless terminals that have not joined the wireless network, uses an over-the-air wake-up method to listen to the preset broadcast frequency band of the wireless network for a period of time during operation, and adds the sender of the listened broadcast to the neighbor list of the first initiating terminal; wherein, the sender is the wireless access gateway in the wireless network or a wireless terminal that has already joined the wireless network. Select the wireless access gateway or wireless terminal from the neighbor list as the first initiating terminal to access the wireless network as the network relay terminal. The first initiating terminal is assigned a level in the wireless network and then joins the wireless network.

7. The data transmission method according to claim 6, characterized in that, The step of setting the level of the first initiating terminal in the wireless network includes: If the first initiating terminal selects the wireless access gateway as the network relay terminal, then the level of the first initiating terminal is set to level 1. If the first starting terminal selects a wireless terminal as the network access relay terminal, then the level of the first starting terminal is set to be one level lower than the level of the selected network access relay terminal. The first initiating terminal sends a network access request to the network access relay terminal based on the resource information in the broadcast data packet of the network access relay terminal; wherein, the network access request is forwarded by the network access relay terminal to the network controller, so that the network controller replies with a network access confirmation along the original path after receiving the network access request; wherein, the network access confirmation includes the time slot and channel resource information allocated to the first initiating terminal; After receiving the network access confirmation, the first initiating terminal operates according to the allocated time slot and channel resource information.

8. The data transmission method according to claim 6, wherein, The step of selecting the wireless access gateway or wireless terminal as the first initiating terminal to access the wireless network from the neighbor list includes: Determine that the wireless access gateway exists in the neighbor list: If the wireless access gateway is present in the neighbor list and the signal strength of the broadcast sent by the wireless access gateway is within a preset threshold range, then the wireless access gateway will be used as a network relay terminal. If the wireless access gateway is not in the neighbor list, then the wireless terminal with a high level and strong broadcast signal strength will be selected as the network relay terminal. If the wireless access gateway is not in the neighbor list, and there are two or more wireless terminals at the highest level, then the wireless terminal with the highest broadcast signal strength among the two or more wireless terminals at the highest level will be selected as the network relay terminal.

9. The method according to claim 1, wherein, The step of allocating a time slot and channel for each transmission in the transmission set of the first connection includes: traversing each time slot in the superframe and the available channel in that time slot in ascending order of the time slot number value, determining whether the transmission can be allocated to that time slot and the available channel in that time slot, and allocating a time slot and an available channel for the transmission that is determined to be able to be allocated to that time slot and the available channel in that time slot.

10. The method according to claim 5, characterized in that, When the receiving terminal of the second transmission already allocated in the first time slot is the same as that of the first transmission to be allocated, the second transmission and the first transmission belong to the same connection, and there is no transmission timing relationship between the second transmission and the first transmission, data is sent based on the shared data frame structure, including: The shared data frame structure includes a time slot preparation unit, one or more channel activity detection (CAD) units with the same duration, an occupied preamble transmission function unit, and a data frame preparation unit in the transmission preparation phase. The transmitting terminal using the first transmission randomly selects a CAD unit to perform an idle channel assessment: If the channel is determined to be idle based on the selected CAD unit, a channel occupancy signal is sent during the remaining time of the transmission preparation phase to occupy the channel for the first transmission in the first time slot. If the channel is determined to be busy based on the selected CAD unit, it is determined that a terminal other than the transmitting terminal is occupying the channel in the first time slot, and the first transmission is returned to the sleep state.

11. A wireless network monitoring system, comprising a wireless access gateway connected using Low Power Wide Area Network (LPWAN) technology (non-cellular network) and at least one level of wireless terminal, wherein the at least one level of wireless access gateway and at least one level of wireless terminal perform the data transmission method according to any one of claims 1-10.

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