A channel access method for wireless self-organizing networks based on node ranking

Abstract

The present invention relates to the field of mobile communication technology, and specifically discloses a wireless self-organizing network channel access method based on node classification. In combination with the network classification results of network terminal nodes, the maximum multiplexing structure of access (beacon), priority reservation, reservation, reply and hierarchical cyclic data time slots is adopted in the TDMA frame structure, so that the self-organizing network is vertically conflict-avoided by network classification and horizontally by reservation application to solve the hidden terminal problem; in terms of control overhead, a reservation is adopted to occupy multiple time slots, and the data time slot is divided by data subframes and network levels to effectively improve the utilization rate of time slot resources; in the channel access algorithm, the influence of node service level on channel access probability is considered, and priority reservation time slots are divided to meet the differentiated service quality requirements of different terminal services. The method can effectively improve the utilization rate of wireless self-organizing network channel resources, avoid frequent conflicts of data of each terminal node, and meet the low latency requirements of the network.

Description

Technical Field

[0001] The present invention relates to the field of mobile communication technology, and in particular to a wireless self-organizing network channel access method based on node classification. Background Art

[0002] Wireless self-organizing networks have the characteristics of high scalability, rapid networking, support for dynamic topology changes and multi-hop transmission. They are a special peer-to-peer network that requires each node to operate in a distributed peer-to-peer manner, that is, network nodes are required to negotiate link resources in a distributed manner to avoid transmission conflicts. There is no centralized control center in wireless self-organizing networks, so each node can only negotiate and regulate channel resources based on the local information mastered by nodes in the neighborhood. Therefore, designing an efficient MAC access mechanism to independently allocate and manage limited channel resources is a key link to ensure network performance. Moreover, for large-scale distributed networks, multi-hop transmission must rely on relay nodes for forwarding, and the exposed terminals, hidden terminals, isolated node deadlocks, and channel resource reuse caused by multi-hop transmission often become one of the difficulties of single-channel MAC access mechanisms. In addition, wireless self-organizing network nodes can join, leave, or move at any time, which can easily lead to highly dynamic changes in network topology. How to make the MAC access mechanism quickly adapt to such changes, ensure that resource occupancy relationships do not conflict, and maintain excellent network performance is also a key issue in designing a MAC access mechanism.

[0003] At present, the MAC access protocol of wireless self-organizing networks is divided into contention-based and scheduling-based MAC protocols according to different channel resource reservation methods. Among them, the classic contention-based MAC access protocol in wireless networks is CSMA / CA used by IEEE802.11, which uses random contention to access the channel. With the increase of network nodes and transmission load, the delay caused by data conflicts will increase exponentially, resulting in a significant reduction in data transmission efficiency; while the typical distributed MAC access protocol based on scheduling is FPRP. FPRP is based on TDMA and divides the channel into two parts: reservation channel and service channel. It completes the allocation of low-conflict probability TDMA service time slots within two hops through 5 handshakes on the reservation channel. However, once a conflict occurs in the reservation cycle, all nodes will simultaneously exit the reservation of the service time slot, which to some extent reduces the success rate of node reservation and the convergence speed of the reservation process. In addition, the reservation probability setting of FPRP is relatively monotonous, and does not consider the different requirements of multiple types of service nodes for time slot resources and service quality.

[0004] Therefore, studying an efficient, reliable and on-demand MAC access mechanism can realize the distributed control and management of limited channel resources by terminal nodes, meet the differentiated service quality requirements of different terminal services, and solve the problems of hidden terminals and channel resource reuse associated with multi-hop transmission, effectively improve the utilization rate of wireless self-organizing network channel resources, avoid frequent conflicts in data among terminal nodes, meet the low latency requirements of the network, and greatly optimize the overall performance of the network. Summary of the invention

[0005] The present invention provides a wireless self-organizing network channel access method based on node classification, and solves the technical problem of how to achieve distributed control and management of limited channel resources by terminal nodes, meet differentiated service quality requirements of different terminal services, and solve the hidden terminal and channel resource multiplexing problems associated with multi-hop transmission.

[0006] In order to solve the above technical problems, the present invention provides a wireless self-organizing network channel access method based on node classification, comprising the steps of:

[0007] S1, dividing the TDMA time slot resources into a plurality of equally spaced TDMA time frame periods, and dividing each of the TDMA time frame periods into a beacon subframe and a plurality of identical data subframes in chronological order according to network functions;

[0008] S2. In a distributed network, a terminal node is arbitrarily designated as the network initial reference station, and other terminal nodes are network graded according to the maximum transmission distance of the network initial reference station; the step S2 specifically includes the following steps:

[0009] S21, randomly select a terminal node in the entire distributed network as the network initial reference station, and its network level is 0;

[0010] S22, after the network initial reference station is connected to the network, it broadcasts a beacon frame with a frame level of 0 in the reference beacon subframe of the TDMA time frame period, and the frame level corresponds to the network level of the source node of the beacon frame;

[0011] S23. Within the maximum transmission distance of the network initial reference station, the terminal node that receives the level 0 beacon frame first performs network synchronization, obtains the network initial time slot division, and then broadcasts the frame level of the beacon frame +1 downward in the node beacon subframe of the level corresponding to the network level of its own node, which means that the network level of the terminal node is 1;

[0012] S24, the unrated terminal node receives a beacon frame with a frame level greater than or equal to 1, and starts the timer after network synchronization. 0The network level of the unrated terminal node is the smaller frame level received + 1, and the frame level of the beacon frame sent by the logical superior node is increased by 1, and then it continues to broadcast downward in the node beacon subframe of the level corresponding to the network level of its own node;

[0013] S3, the rated terminal node calculates the reservation probability p of the current data subframe according to the service priority;

[0014] S4. The rated terminal node initiates reservation occupation of the current data subframe with reservation probability p. If the reservation is successful, the data time slot corresponding to the node network level is occupied for service transmission. If the reservation fails, the reservation probability p' of the next data subframe is calculated and the reservation occupation is initiated again.

[0015] S5. Count the services sent within a TDMA time frame period. If the number of services sent in the previous TDMA time frame period is less than the number of messages cached in the current queue, the priority of all services in the current queue is increased by 1; if the number of services sent in the previous TDMA time frame period is greater than the number of services cached in the queue, the priority of all services in the current queue is reduced by 1, and return to step S3.

[0016] Furthermore, the step S2 further includes:

[0017] After receiving the beacon frame from the logical superior node, the rated terminal node forwards the beacon frame downward in the node beacon subframe of the level corresponding to the network level of its own node;

[0018] If the rated terminal node is at time T c If the node fails to receive the beacon frame of the logical superior node, it means that the node has been disconnected from the logical superior node and forwards the received beacon frame of the same-level node in the node beacon subframe corresponding to the network level of its own node;

[0019] If the rated terminal node is at time T c If the node cannot receive any beacon frame from the same or logically superior node, it means that the node is isolated by the same or superior node and continues to wait for T c ' time, if the situation is the same, abandon the node network level and wait for the beacon frame of the lower node to re-level;

[0020] If a rated terminal node receives a beacon frame that is more than 1 level lower than its own node network level, the node network level is modified to the frame level of the received beacon frame + 1, and the beacon frame corresponding to its own node network level is forwarded downward.

[0021] Furthermore, in step S2, the timing time T of the timer 0 is the duration of a TDMA frame period; in step S26, T cis the duration of 4 TDMA frame periods, T c ' is the duration of 2 TDMA time frame periods.

[0022] Further, in step S1, the beacon subframe is divided into a reference beacon subframe and multiple node beacon subframes in chronological order, each of the node beacon subframes includes a (1+3*N)-level node beacon subframe, a (2+3*N)-level node beacon subframe, and a (3+3*N)-level node beacon subframe, N∈{0,1,2...}; wherein the network initial reference station occupies the reference beacon subframe to send downward beacon frames, and the graded terminal node occupies the node beacon subframe of the level corresponding to its network grade to send downward beacon frames.

[0023] Further, in step S1, each of the data subframes is divided into data reservation subframes and data transmission subframes in chronological order; the data reservation subframes are divided into priority reservation slots, reservation application slots, reservation forwarding slots and reservation reply slots in chronological order, and the data transmission subframes are divided into cyclic high-level data slots, middle-level data slots and low-level data slots in chronological order.

[0024] Further, in step S3, the data subframe reservation probability p is calculated by the following formula:

[0025]

[0026] Among them, n c is the number of failed data subframe competitions in this TDMA frame period, P ri |index represents all service levels under the classification mark of the service, max{P ri |index} represents the maximum service level under the classification mark of the service, min{} represents the minimum value of all values, α represents the reservation probability parameter and α<1, p max represents the maximum probability of data subframe reservation, p max =1.

[0027] Further, in step S4, the rated terminal node initiates reservation occupation of the current data subframe with a reservation probability p, which specifically includes the steps of:

[0028] S41, if the service of the terminal node is of emergency type, it is at the highest priority, and broadcasts the data reservation frame to the neighboring nodes with a reservation probability p in the priority reservation time slot of the data reservation subframe;

[0029] S42, if the service of the terminal node is delay-sensitive or best-effort, broadcasting a data reservation frame to neighboring nodes with a reservation probability p in the reservation application time slot of the data reservation subframe;

[0030] S43, if the terminal node receives the data reservation frame only in the priority reservation time slot, broadcast the reservation reply frame in the reservation reply time slot;

[0031] S44. If the terminal node receives a data reservation frame in the reservation application time slot and does not receive a data reservation frame in the priority reservation time slot, it broadcasts a reservation reply frame in the reservation reply time slot;

[0032] S45. If the terminal node receives a data reservation frame in the reserved forwarding time slot, no processing is performed;

[0033] S46. After receiving the reservation reply frame, the terminal node first determines whether the reply node of the reservation reply frame is the current node. If so, it occupies the data time slot corresponding to the node level in the corresponding data transmission subframe to send a message.

[0034] Further, in step S4, reservation success means that a reservation reply frame corresponding to the data reservation frame is received in the reservation reply time slot of the data reservation subframe, and reservation failure means that a reservation reply frame of the current node is not received in the reservation reply time slot of the data reservation subframe.

[0035] Further, in step S5, if the node service is already at the highest priority or the lowest priority, the service level remains unchanged when the priority is updated.

[0036] Furthermore, the network service level P ri Divided into 1, 2, 3, 4, 5, 6, among which P ri ≥5 is a best-effort task, P ri The corresponding mark is: index = Low; P ri ≤2 is an emergency task, P ri The corresponding mark is: index = High; 2 < P ri When <5, it is a delay-sensitive task. ri The corresponding mark is index=Middle.

[0037] The wireless self-organizing network channel access method based on node classification provided by the present invention combines the network classification results of the network terminal nodes, and adopts the maximum reuse structure of access (beacon), priority reservation, reservation, reply and hierarchical cyclic data time slots in the TDMA frame structure, so that the wireless self-organizing network can avoid conflicts vertically by network classification and solve the hidden terminal problem horizontally by reservation application; in terms of control overhead, a reservation can occupy multiple time slots, and the data time slots are divided by data subframes and network levels to effectively improve the utilization rate of time slot resources; in the channel access algorithm, the influence of node service level on channel access probability is considered, and priority reservation time slots are divided to meet the differentiated service quality requirements of different terminal services. Compared with previous technologies, this method is more intelligent, can effectively improve the utilization rate of wireless self-organizing network channel resources, avoid frequent conflicts of data of each terminal node, meet the low latency requirements of the network, and greatly optimize the overall performance of the network. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 It is a flow chart of a wireless self-organizing network channel access method based on node classification provided by an embodiment of the present invention;

[0039] Figure 2 It is a time frame structure for maximum multiplexing division of time slot resources provided by an embodiment of the present invention;

[0040] Figure 3 This is a schematic diagram of the non-collision principle analysis provided by an embodiment of the present invention;

[0041] Figure 4 It is a schematic diagram of the network classification principle provided by an embodiment of the present invention;

[0042] Figure 5 This is an analysis diagram of a situation in which a node receives a data reservation frame provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0043] The following specifically illustrates the implementation mode of the present invention in conjunction with the accompanying drawings. The embodiments are provided for illustrative purposes only and cannot be understood as limiting the present invention. The accompanying drawings are provided for reference and illustration only and do not constitute a limitation on the scope of patent protection of the present invention, because many changes can be made to the present invention without departing from the spirit and scope of the present invention.

[0044] The embodiment of the present invention provides a wireless self-organizing network channel access method based on node classification, such as Figure 1 As shown, in this embodiment, the method specifically includes steps S1 to S5.

[0045] S1. Divide the TDMA time slot resources into a plurality of equally spaced TDMA time frame periods, and divide each TDMA time frame period into a beacon subframe and a plurality of identical data subframes in chronological order according to network functions.

[0046] In step S1, if Figure 2 As shown, the beacon subframe is divided into a reference beacon subframe and multiple node beacon subframes in time sequence, and each node beacon subframe includes a (1+3*N)-level node beacon subframe, a (2+3*N)-level node beacon subframe, and a (3+3*N)-level node beacon subframe, N∈{0,1,2...}; wherein, the network initial reference station occupies the reference beacon subframe to send beacon frames downward. The rated terminal node occupies the node beacon subframe of the level corresponding to its network rating to send beacon frames downward. For example, if the network node rating is 1 or 4, it can be classified as a (1+3*N)-level node, and the node sends beacon frames in the (1+3*N)-level node beacon subframe; if the network node rating is 2 or 5, it can be classified as a (2+3*N)-level node, and the node sends beacon frames in the (2+3*N)-level node beacon subframe. Figure 2 K is the number of time slots in a beacon subframe of a certain level of node, which can be adjusted according to the actual situation of the network. The function of the beacon subframe is for nodes to send beacon frames. The function of the beacon frame is network synchronization and network classification. The beacon subframe is a time slot structure concept, and the beacon frame is a message.

[0047] like Figure 2 As shown, each data subframe is divided into a priority reservation slot (FirstReservation, FR), a reservation application slot (Reservation Request, RR), a reservation forwarding slot (ReservationForward, RF), and a reservation reply slot (Reservation Answer, RA) in chronological order. The data transmission time frame is divided into multiple identical data transmission subframes in chronological order, and each data transmission subframe is divided into cyclic high-level data slots (Data High, DH), middle-level data (Data Middle, DM), and low-level data slots (Data Low, DL) in chronological order. The high-level data slot refers to the (1+3*N) layer, the middle-level data slot refers to the (2+3*N) layer, and the low-level data slot refers to the (3+3*N) layer, where N∈{0,1,2...}.

[0048] This embodiment divides the time frame period according to the non-collision principle and the network layer. The non-collision principle specifically means that the terminal node will not receive messages from multiple nodes in a certain time slot, such as Figure 3As shown in the figure, when one-hop interval nodes send data at the same time, the middle layer nodes receive errors due to data collision, while when two-hop distance nodes send data at the same time, the middle nodes have limited receiving range due to distance restrictions, so that the data can be received correctly. Therefore, in order to ensure that time slots can be reused to the greatest extent without conflicts, the distance between nodes using the same time slot must be two hops away. Combined with the network level, layer N and layer (N+3) can use the same time slot. The network level of the node corresponds to the level of the time slot structure one by one, and only the nodes corresponding to the corresponding network level can use the time slots of the corresponding level.

[0049] S2. In a distributed network, any terminal node is designated as the network initial reference station, and the network classification of other terminal nodes is performed according to the maximum transmission distance of the network initial reference station.

[0050] The step S2 specifically includes the following steps:

[0051] S21, randomly select a terminal node in the entire distributed network as the network initial reference station, and its network level is 0;

[0052] S22, after the network initial reference station is connected to the network, it broadcasts a beacon frame with a frame level of 0 in the reference beacon subframe of the TDMA time frame period, and the frame level corresponds to the network level of the source node of the beacon frame;

[0053] S23. Within the maximum transmission distance of the network initial reference station, the terminal node that receives the level 0 beacon frame first performs network synchronization, obtains the network initial time slot division, and then broadcasts the frame level of the beacon frame +1 downward in the node beacon subframe of the level corresponding to the network level of its own node, which means that the network level of the terminal node is 1;

[0054] S24, the unrated terminal node receives a beacon frame with a frame level greater than or equal to 1, and starts the timer after network synchronization. 0 The network level of the unrated terminal node is the smaller frame level received + 1, and the frame level of the beacon frame sent by the logical superior node is increased by 1, and then it continues to broadcast downward in the node beacon subframe of the level corresponding to the network level of its own node;

[0055] like Figure 4 As shown, step S2 also includes:

[0056] like Figure 4 -(1) As shown, after receiving the beacon frame of the logical superior node, the rated terminal node forwards the beacon frame downward in the node beacon subframe of the level corresponding to the network level of its own node;

[0057] like Figure 4 -(2) As shown in Figure 2, if the rated terminal node is at time T cIf the node fails to receive the beacon frame of the logical superior node, it means that the node has been disconnected from the logical superior node and forwards the received beacon frame of the same-level node in the node beacon subframe corresponding to the network level of its own node;

[0058] like Figure 4 -(3) As shown in Figure 3, if the rated terminal node is at time T c If the node cannot receive any beacon frame from the same or logically superior node, it means that the node is isolated by the same or superior node and continues to wait for T c ' time, if the situation is the same, abandon the node network level and wait for the beacon frame of the lower node to re-level;

[0059] like Figure 4 -(4), if a rated terminal node receives a beacon frame that is more than 1 level lower than its own node network level, the node network level is modified to the frame level of the received beacon frame + 1, and the beacon frame corresponding to its own node network level is forwarded downward.

[0060] The beacon frame mainly contains the maximum multiplexing division result of the time slot resource and the beacon frame level. The timing time of the timer T 0 is the duration of a TDMA frame period; in step S26, T c is the duration of 4 TDMA frame periods, T c ' is the duration of 2 TDMA time frame periods.

[0061] In this example, the time slot structure is first divided. A TDMA time frame period is divided into beacon subframes and data subframes. The beacon subframes that can be used by nodes at different levels are divided. The data transmission time slots that can be used by nodes at different levels are divided within the data subframe, namely the high-level data time slots, middle-level data time slots, and low-level data time slots mentioned.

[0062] The network structure division is completed in the process of node classification. Simply put, in the initial stage of the network, all nodes are waiting to receive messages. The reference node (network classification is 0) first sends a beacon frame. The node that can receive the message is called a level 1 node, that is, the network node classification is 1. After receiving the beacon frame, the level 1 node continues to forward it downward. The node that receives the beacon frame is classified as level 2, and so on. After each network node receives the beacon frame, it will automatically synchronize with the network and obtain the following information: Figure 2 The initial time slot division of the network is shown.

[0063] S3. The rated terminal node calculates the reservation probability p of the current data time frame according to the service priority.

[0064] As an example, the terminal node services include monitoring warning messages, session messages, and regular log file reporting messages, where monitoring warning messages are urgent tasks, session messages are delay-sensitive tasks, and regular log file reporting is a best-effort task. ri Divided into 1, 2, 3, 4, 5, 6, among which P ri ≥5 is a best-effort task, P ri The corresponding mark is: index = Low; P ri ≤2 is an emergency task, P ri The corresponding mark is: index = High; 2 < P ri When <5, it is a delay-sensitive task. ri The corresponding mark is index=Middle.

[0065] The data subframe reservation probability p is calculated by the following formula:

[0066]

[0067] Among them, n c is the number of failed data subframe competitions in this TDMA frame period, P ri |index indicates all the service levels under the classification mark of the service, P ri Indicates the level of network services, max{P ri |index} represents the maximum service level under the classification mark of the service, min{} represents the minimum value of all values, α represents the reservation probability parameter and α<1, p max represents the maximum probability of data subframe reservation, p max =1. There are multiple data subframes in a time frame period, and each data subframe can be applied for by nodes. Competition failure means that the node fails to reserve a certain data subframe. The number of competition failures refers to the cumulative number of reservation failures in a time frame. The more competition failures, the more nodes need to reserve time slots in the time frame period. In order to avoid congestion, the reservation application probability of this node is reduced.

[0068] S4. The rated terminal node initiates reservation occupation of the current data subframe with reservation probability p. If the reservation is successful, the data time slot corresponding to the node level is occupied for service transmission. If the reservation fails, the reservation probability p' of the next data subframe is calculated and the reservation occupation is re-initiated.

[0069] In step S4, the rated terminal node initiates reservation occupation of the current data subframe with reservation probability p, which specifically includes the following steps:

[0070] S41, if the service of the terminal node is of emergency type, it is at the highest priority, and broadcasts the data reservation frame to the neighboring nodes with a reservation probability p in the priority reservation time slot of the data reservation subframe;

[0071] S42, if the service of the terminal node is delay-sensitive or best-effort, broadcasting a data reservation frame to neighboring nodes with a reservation probability p in the reservation application time slot of the data reservation subframe;

[0072] S43, if the terminal node receives a data reservation frame in the priority reservation time slot, it broadcasts a reservation reply frame in the reservation reply time slot;

[0073] S44. If the terminal node receives a data reservation frame in the reservation application time slot and does not receive a data reservation frame in the priority reservation time slot, it broadcasts a reservation reply frame in the reservation reply time slot;

[0074] S45. If the terminal node receives a data reservation frame in the reserved forwarding time slot, no processing is performed;

[0075] S46. After receiving the reservation reply frame, the terminal node first determines whether the reply node of the reservation reply frame is the current node. If so, it occupies the data time slot corresponding to the node level in the corresponding data transmission subframe to send the message. A successful reservation means that the reservation reply frame corresponding to the data reservation frame is received in the reservation reply time slot of the data reservation subframe. A failed reservation means that the reservation reply frame of the current node is not received in the reservation reply time slot of the data reservation subframe, which specifically includes two situations: one is that no reservation reply frame is received in the reservation reply time slot; the other is that the reservation reply frame of other nodes is received in the reservation reply time slot.

[0076] like Figure 5 As shown, the terminal node may receive two data reservation frames after experiencing the reservation application time slot, and will not receive three data reservation frames under normal circumstances. This is because as long as the node receives a data reservation frame in the priority reservation time slot or the reservation application time slot, the node will broadcast one of the above data reservation frames in the reservation forwarding time slot, which will collide with the data reservation frames forwarded by other nodes; and in order to respond to the service requirements of the node business priority, the node will choose to forward the data reservation frame received in the priority reservation time slot.

[0077] S5. Count the services sent within a TDMA time frame period. If the number of services sent in the previous TDMA time frame period is less than the number of messages cached in the current queue, the priority of all services in the current queue is increased by 1; if the number of services sent in the previous TDMA time frame period is greater than the number of services cached in the queue, the priority of all services in the current queue is reduced by 1, and return to step S3.

[0078] In step S5, if the node task is already at the highest priority or the lowest priority, the service level remains unchanged when the priority is updated. That is, when the service level is 7, the number of messages sent in the previous TDMA frame period is less than the number of queue buffer messages, and the service level should be +1, but the service has reached the highest level, so it remains unchanged. The same is true when the service level is 1. In addition, in the entire service queue, the service order is determined by the service level and the time when the service is generated. As an example, for example, the generation time of service A with a level of 5 is t 1 , and the generation time of service B of level 7 is t 2 , the generation time of service C of level 5 is t 3 , where t 1 <t 2 <t 3 , so the services in the entire service queue are sorted as B, A, and C.

[0079] In summary, the embodiment of the present invention provides a wireless self-organizing network channel access method based on node classification, which combines the network classification results of network terminal nodes, and adopts the maximum multiplexing structure of access (beacon), priority reservation, reservation, reply and hierarchical cyclic data time slots in the TDMA frame structure, so that the self-organizing network can avoid conflicts vertically by network classification and solve the hidden terminal problem horizontally by reservation application; in terms of control overhead, a reservation can occupy multiple time slots, and the data time slots are divided by data subframes and network levels to effectively improve the utilization of time slot resources; in the channel access algorithm, the influence of node service level on channel access probability is considered, and priority reservation time slots are divided to meet the differentiated service quality requirements of different terminal services. Compared with previous technologies, this method is more intelligent, can effectively improve the utilization of wireless self-organizing network channel resources, avoid frequent conflicts of data of each terminal node, meet the low latency requirements of the network, and greatly optimize the overall performance of the network.

[0080] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. A wireless self-organizing network channel access method based on node classification, characterized in that: Includes steps: S1, dividing the TDMA time slot resources into a plurality of equally spaced TDMA time frame periods, and dividing each of the TDMA time frame periods into a beacon subframe and a plurality of identical data subframes in chronological order according to network functions; S2. In a distributed network, a terminal node is arbitrarily designated as the network initial reference station, and other terminal nodes are network graded according to the maximum transmission distance of the network initial reference station; the step S2 specifically includes the following steps: S21, randomly select a terminal node in the entire distributed network as the network initial reference station, and its network level is 0; S22, after the network initial reference station is connected to the network, it broadcasts a beacon frame with a frame level of 0 in the reference beacon subframe of the TDMA time frame period, and the frame level corresponds to the network level of the source node of the beacon frame; S23. Within the maximum transmission distance of the network initial reference station, the terminal node that receives the level 0 beacon frame first performs network synchronization, obtains the network initial time slot division, and then broadcasts the frame level of the beacon frame +1 downward in the node beacon subframe of the level corresponding to the network level of its own node, which means that the network level of the terminal node is 1; S24, the unrated terminal node receives a beacon frame with a frame level greater than or equal to 1, and starts the timer after network synchronization. T 0, the network level of the unrated terminal node is the smaller frame level received + 1, and the frame level of the beacon frame sent by the logical superior node is increased by 1 and then continued to broadcast downward in the node beacon subframe of the level corresponding to the network level of its own node; S3. The rated terminal node calculates the reservation probability of the current data subframe according to the service priority p ; S4, rated terminal nodes with reservation probability p Initiate a reservation for the current data subframe. If the reservation is successful, the data time slot corresponding to the node network level is occupied for service transmission. If the reservation fails, the reservation probability of the next data subframe is calculated. p ', re-initiate reservation occupation; S5. Count the services sent within a TDMA time frame period. If the number of services sent in the previous TDMA time frame period is less than the number of messages cached in the current queue, the priority of all services in the current queue is increased by 1; if the number of services sent in the previous TDMA time frame period is greater than the number of services cached in the queue, the priority of all services in the current queue is reduced by 1, and return to step S3.

2. The wireless self-organizing network channel access method based on node classification according to claim 1, characterized in that: The step S2 further comprises: After receiving the beacon frame from the logical superior node, the rated terminal node forwards the beacon frame downward in the node beacon subframe of the level corresponding to the network level of its own node; If the rated terminal node is at time T c If the node fails to receive the beacon frame of the logical superior node, it means that the node has been disconnected from the logical superior node and forwards the received beacon frame of the same-level node in the node beacon subframe corresponding to the network level of its own node; If the rated terminal node is at time T c If the node does not receive any beacon frame from any peer or logical superior node, it means that the node is isolated by the peer and superior nodes and continues to wait. T c ' time, if the situation is the same, abandon the node network level and wait for the beacon frame of the lower node to re-level; If a rated terminal node receives a beacon frame that is more than 1 level lower than its own node network level, the node network level is modified to the frame level of the received beacon frame + 1, and the beacon frame corresponding to its own node network level is forwarded downward.

3. The wireless self-organizing network channel access method based on node classification according to claim 2, characterized in that: In step S2, the timer is set to T 0 is the duration of a TDMA frame period; In step S26, T c is the duration of 4 TDMA time frame periods, T c ' is the duration of 2 TDMA time frame periods.

4. The wireless self-organizing network channel access method based on node ranking according to claim 3, characterized in that: In step S1, the beacon subframe is divided into a reference beacon subframe and a plurality of node beacon subframes in chronological order, and each of the node beacon subframes includes (1+3* N )-level node beacon subframe, (2+3* N )-level node beacon subframe, (3+3* N ) level node beacon subframe, N ∈{0,1,2…}; wherein the network initial reference station occupies the reference beacon subframe to send a beacon frame downward, and the rated terminal node occupies the node beacon subframe corresponding to its network rating to send a beacon frame downward.

5. The wireless self-organizing network channel access method based on node classification according to claim 4, characterized in that: In step S1, each of the data subframes is divided into data reservation subframes and data transmission subframes in chronological order; the data reservation subframes are divided into priority reservation slots, reservation application slots, reservation forwarding slots and reservation reply slots in chronological order, and the data transmission subframes are divided into cyclic high-level data slots, middle-level data slots and low-level data slots in chronological order.

6. The wireless self-organizing network channel access method based on node classification according to claim 5, characterized in that: In step S3, the data subframe reservation probability p Calculated by the following formula: ， in, n c is the number of failed data subframe competitions within this TDMA time frame period, P ri Indicates the level of network service. Indicates all business levels under the classification mark of this business. Indicates the maximum service level under the classification mark of the service, min{} indicates the minimum value of all values. α represents the reservation probability parameter and α< 1, p max represents the maximum value of the data subframe reservation probability, p max =1.

7. The wireless self-organizing network channel access method based on node ranking according to claim 6, characterized in that: In step S4, the rated terminal nodes are assigned a reservation probability p Initiate reservation occupation of the current data subframe, specifically including the steps: S41. If the service of the terminal node is of emergency type, it is at the highest priority and is scheduled in the priority reservation time slot of the data reservation subframe with a reservation probability of p Broadcasting data reservation frames to neighboring nodes; S42: If the service of the terminal node is delay-sensitive or best-effort, the reservation application time slot of the data reservation subframe is set to the reservation probability p Broadcasting data reservation frames to neighboring nodes; S43, if the terminal node receives the data reservation frame only in the priority reservation time slot, broadcast the reservation reply frame in the reservation reply time slot; S44. If the terminal node receives a data reservation frame in the reservation application time slot and does not receive a data reservation frame in the priority reservation time slot, it broadcasts a reservation reply frame in the reservation reply time slot; S45. If the terminal node receives a data reservation frame in the reserved forwarding time slot, no processing is performed; S46. After receiving the reservation reply frame, the terminal node first determines whether the reply node of the reservation reply frame is the current node. If so, it occupies the data time slot corresponding to the node level in the corresponding data transmission subframe to send a message.

8. The wireless self-organizing network channel access method based on node classification according to claim 7, characterized in that: In step S4, reservation success means that a reservation reply frame corresponding to the data reservation frame is received in the reservation reply time slot of the data reservation subframe, and reservation failure means that a reservation reply frame of the local node is not received in the reservation reply time slot of the data reservation subframe.

9. The wireless self-organizing network channel access method based on node classification according to claim 8, characterized in that: In step S5, if the node service is already at the highest priority or the lowest priority, the service level remains unchanged when the priority is updated.

10. The wireless self-organizing network channel access method based on node ranking according to claim 9, characterized in that: Network service level P ri Divided into 1, 2, 3, 4, 5, 6, among which P ri ≥5 is a best-effort task. P ri The corresponding mark is: index =Low; P ri ≤2 is an emergency task. P ri The corresponding mark is: index =High; 2< P ri <5 hours is a delay-sensitive task. P ri The corresponding mark is index =Middle.

Images