Self-adaptive unmanned cluster MAC layer hybrid networking method

Abstract

The invention discloses a self-adaptive unmanned cluster MAC layer hybrid networking method, and belongs to the technical field of wireless communication. The problems that an existing method is difficult to adapt to dynamic changes of the number of nodes, time slot allocation is difficult when the number of the nodes is large, and congestion conflicts and channel resources are prone to being frequently generated when the communication service volume of part of the nodes is large are solved. According to the method, a protocol frame structure is designed, a part of time slots in the protocol frame structure are designed to be dynamic contention windows, and the other part of time slots are set to be fixed time slots. In an initialization stage, nodes access a network through a contention window and distribute priorities for the accessed nodes, the priorities are dynamically adjusted according to network congestion degrees of the nodes in a network operation process, and the nodes with high priorities can be distributed to fixed time slots and enjoy higher contention priorities in the contention window; and the low-priority node participates in time slot competition in the competition window, and after the competition succeeds, the service data is received and transmitted. The method can be applied to the technical field of wireless communication.

Description

Technical Field

[0001] The present invention belongs to the technical field of wireless communication, and particularly relates to an adaptive hybrid networking method for unmanned cluster MAC (Medium Access Control) layer. Background Art

[0002] In a large-scale unmanned cluster network, the number of nodes is huge and dynamically changing. The traditional TDMA (Time Division Multiple Access) protocol is difficult to adapt to the dynamic change of the number of nodes, and it is difficult to allocate time slots when the number of nodes increases greatly; while the CSMA (Carrier Sense Multiple Access) protocol is prone to frequent congestion conflicts and channel resource waste under high load conditions where the traffic volume of some nodes is large; therefore, a single TDMA or CSMA protocol cannot simultaneously meet the requirements of high efficiency and self-adaptability of channel resource utilization in large-scale unmanned cluster networking.

[0003] In summary, in order to solve the problems that it is difficult to allocate time slots by existing methods when the number of nodes is large, and it is easy to frequently generate congestion conflicts and channel resource waste when the communication traffic volume of some nodes is large, it is an urgent problem to be solved at present to propose a new hybrid networking method for unmanned cluster MAC layer. Summary of the Invention

[0004] The purpose of the present invention is to solve the problems that existing methods are difficult to adapt to the dynamic change of the number of nodes, it is difficult to allocate time slots by existing methods when the number of nodes is large, and it is easy to frequently generate congestion conflicts and channel resource waste when the communication traffic volume of some nodes is large, and an adaptive hybrid networking method for unmanned cluster MAC layer is proposed.

[0005] The technical solution adopted by the present invention to solve the above technical problems is: an adaptive hybrid networking method for unmanned cluster MAC layer, and the method specifically includes the following steps:

[0006] Step 1, initialize the protocol frame length of the MAC layer to M service time slots;

[0007] Step 2, initialize the protocol frame count t = 1;

[0008] Step 3, determine whether the t-th protocol frame reaches the node priority update period, and the node priority update period is set to 10M;

[0009] If the t-th protocol frame reaches the node priority update period, then before the start of the t-th protocol frame, collect the network congestion metrics of historical access nodes, and update the priorities of historical access nodes according to the collected network congestion metrics; then execute Step 4;

[0010] If the t-th protocol frame does not reach the node priority update period, then directly execute Step 5;

[0011] Step 4: Determine the window positions of the fixed time slots and the contention time slots according to the updated historical access node priorities and the priorities of the new nodes accessed within the (t - 1)-th protocol frame. All nodes participate in the time slot contention within the contention time slot according to the assigned contention probabilities. After successful contention, they then send and receive service data;

[0012] After all time slots of the t-th protocol frame end, set t = t + 1, and return to execute Step 3;

[0013] Step 5: Determine the window positions of the fixed time slots and the contention time slots according to the historical access node priorities and the priorities of the new nodes accessed within the (t - 1)-th protocol frame. All nodes participate in the time slot contention within the contention time slot according to the assigned contention probabilities. After successful contention, they then send and receive service data;

[0014] After all time slots of the t-th protocol frame end, set t = t + 1, and return to execute Step 3.

[0015] Further, the method broadcasts, in real time by the network controller, the window position information of the fixed time slots and the contention time slots within the current protocol frame at the MAC layer.

[0016] Further, the new node obtains the contention time slot window position according to the information broadcast by the network controller, and then randomly selects a contention time slot from within the contention time slot window to send an access request message;

[0017] The access request message includes the node ID, the estimated value of the buffer queue length, the estimated value of the packet delay, and the estimated value of the packet loss rate.

[0018] Further, the calculation method for the priority of the node is:

[0019]

[0020] where BL represents the buffer queue length of the node, PD represents the packet delay of the node, PLR represents the packet loss rate of the node, ω1, ω2, and ω3 are all weights, P represents the priority of the node, α represents the buffer queue length threshold, β represents the packet delay threshold, and γ represents the packet loss rate threshold;

[0021] If the priority P of the node ≥ 0.7, then the node is a high-priority node; if the priority P of the node < 0.7, then the node is a low-priority node.

[0022] Further, the specific process of Step 4 is:

[0023] Step 4.1: Determine whether there are any nodes that have not communicated within the (t - 3)-th protocol frame, the (t - 2)-th protocol frame, and the (t - 1)-th protocol frame;

[0024] If there is a node that has not communicated within the (t - 3)-th, (t - 2)-th, and (t - 1)-th protocol frames, the node exits the network from the contention window, and then continues to execute Step 4.2 for the remaining nodes;

[0025] If there is no node that has not communicated within the (t - 3)-th, (t - 2)-th, and (t - 1)-th protocol frames, directly execute Step 4.2;

[0026] Step 4.2: For node a that was a high-priority node in the previous cycle and whose updated priority is low:

[0027] If node a occupied a fixed time slot in the previous protocol frame, after releasing the fixed time slot resource of node a, allocate the transceiver service of node a to the contention time slot window, and set the contention probability of node a to 20%;

[0028] If node a did not occupy a fixed time slot in the previous protocol frame, still allocate the transceiver service of node a to the contention time slot window, and adjust the contention probability of node a to 20%;

[0029] Then execute Step 4.3;

[0030] Step 4.3: Count the number N of high-priority nodes in the t-th protocol frame. Among them, the high-priority nodes in the t-th protocol frame include nodes that were high-priority nodes in the previous cycle and whose updated priority is still high, nodes that were low-priority nodes in the previous cycle and whose updated priority is high, and high-priority nodes newly accessed in the (t - 1)-th protocol frame;

[0031] If the number N of high-priority nodes in the t-th protocol frame is less than or equal to 0.9M, allocate a fixed time slot to each high-priority node, and set the contention probability of each high-priority node in the contention time slot to 80%; then execute Step 4.8;

[0032] If the number N of high-priority nodes in the t-th protocol frame is greater than 0.9M, execute Step 4.4;

[0033] Step 4.4: Determine whether there is a high-priority node that satisfies condition (1) among the high-priority nodes in the t-th protocol frame. Condition (1) is specifically: a high-priority node that was allocated a fixed time slot in the previous protocol frame and did not perform service transceiver;

[0034] If there is a high-priority node that satisfies condition (1), when the number of high-priority nodes that satisfy condition (1) is less than or equal to N - 0.9M, execute Step 4.5; when the number of high-priority nodes that satisfy condition (1) is greater than N - 0.9M, execute Step 4.6;

[0035] If there is no high-priority node that satisfies condition (1), directly execute step 47;

[0036] Step 45: Release the fixed time slot resources of all high-priority nodes that satisfy condition (1), transfer all high-priority nodes that satisfy condition (1) to the contention time slot and set the contention probability to 80%, and then remove all high-priority nodes that satisfy condition (1) from the N high-priority nodes in the t-th protocol frame;

[0037] Then randomly select 0.9M nodes from the remaining high-priority nodes, allocate a fixed time slot to each selected high-priority node, and set the contention probability of each selected high-priority node in the contention time slot to 80%; transfer each unselected high-priority node to the contention time slot and set the contention probability of each unselected high-priority node in the contention time slot to 80%;

[0038] Then execute step 48;

[0039] Step 46: Randomly select N - 0.9M from all high-priority nodes that satisfy condition (1), release the fixed time slot resources of the selected high-priority nodes, transfer the selected high-priority nodes to the contention time slot and set the contention probability to 80%, and then allocate a fixed time slot to each of the remaining high-priority nodes and set the contention probability of the remaining high-priority nodes in the contention time slot to 80%;

[0040] Then execute step 48;

[0041] Step 47: Randomly select 0.9M from all high-priority nodes, allocate a fixed time slot to each selected high-priority node, and set the contention probability of each selected high-priority node in the contention time slot to 80%; transfer each unselected high-priority node to the contention time slot and set the contention probability of each unselected high-priority node in the contention time slot to 80%;

[0042] Then execute step 48;

[0043] Step 48: Allocate the low-priority nodes in the t-th protocol frame to the contention time slot, and set the contention probability of each low-priority node in the contention time slot to 20%.

[0044] Furthermore, the specific process of step 5 is as follows:

[0045] Step 51: Determine whether there are nodes that have not communicated in the (t - 3)-th, (t - 2)-th, and (t - 1)-th protocol frames;

[0046] If there is a node that has not communicated within the (t-3)th protocol frame, the (t-2)th protocol frame, and the (t-1)th protocol frame, the node exits the network from the contention window, and then continues to execute Step 5.2 for the remaining nodes;

[0047] If there is no node that has not communicated within the (t-3)th protocol frame, the (t-2)th protocol frame, and the (t-1)th protocol frame, directly execute Step 5.2;

[0048] Step 5.2: Count the number N of high-priority nodes within the tth protocol frame. Among them, the high-priority nodes within the tth protocol frame include the historically accessed high-priority nodes and the newly accessed high-priority nodes within the (t-1)th protocol frame;

[0049] If the number N of high-priority nodes within the tth protocol frame is less than or equal to 0.9M, allocate a fixed time slot to each high-priority node, and set the contention probability of each high-priority node within the contention time slot to 80%; then execute Step 5.7;

[0050] If the number N of high-priority nodes within the tth protocol frame is greater than 0.9M, execute Step 5.3;

[0051] Step 5.3: Determine whether there is a high-priority node among the high-priority nodes within the tth protocol frame that satisfies Condition (1). Condition (1) is specifically: a high-priority node that was allocated a fixed time slot within the previous protocol frame and did not perform service transmission or reception;

[0052] If there is a high-priority node that satisfies Condition (1), when the number of high-priority nodes that satisfy Condition (1) is less than or equal to N - 0.9M, execute Step 5.4; when the number of high-priority nodes that satisfy Condition (1) is greater than N - 0.9M, then execute Step 5.5;

[0053] If there is no high-priority node that satisfies Condition (1), directly execute Step 5.6;

[0054] Step 5.4: Release the fixed time slot resources of all high-priority nodes that satisfy Condition (1), transfer all high-priority nodes that satisfy Condition (1) to the contention time slot and set the contention probability to 80% for all of them, and then remove all high-priority nodes that satisfy Condition (1) from the N high-priority nodes within the tth protocol frame;

[0055] Then randomly select 0.9M nodes from the remaining high-priority nodes, allocate a fixed time slot to each selected high-priority node, and set the contention probability of each selected high-priority node within the contention time slot to 80%; transfer each unselected high-priority node to the contention time slot, and set the contention probability of each unselected high-priority node within the contention time slot to 80%;

[0056] Execute step 57 again;

[0057] Step 55: Randomly select N - 0.9M from all high-priority nodes that meet condition (1), release the fixed time slot resources of the selected high-priority nodes, transfer the selected high-priority nodes to the contention time slot and set the contention probability to 80%, then allocate a fixed time slot to each of the remaining high-priority nodes respectively, and set the contention probability of the remaining high-priority nodes in the contention time slot to 80%;

[0058] Execute step 57 again;

[0059] Step 56: Randomly select 0.9M from all high-priority nodes, allocate a fixed time slot to each of the selected high-priority nodes respectively, and set the contention probability of each of the selected high-priority nodes in the contention time slot to 80%; transfer each of the unselected high-priority nodes to the contention time slot, and set the contention probability of each of the unselected high-priority nodes in the contention time slot to 80%;

[0060] Execute step 57 again;

[0061] Step 57: Allocate the low-priority nodes in the t-th protocol frame to the contention time slot, and set the contention probability of each low-priority node in the contention time slot to 20%.

[0062] Furthermore, when a node conflict occurs in the contention time slot, the high-priority nodes continue to participate in the time slot contention in the next contention time slot, and the low-priority nodes continue to participate in the time slot contention after retreating 5 contention time slots.

[0063] The beneficial effects of the present invention are as follows:

[0064] By designing the protocol frame structure, the present invention designs some time slots in the protocol frame structure as dynamic CSMA contention windows, and sets the remaining time slots in the protocol frame structure as fixed time slots. In the initialization stage, nodes access the network through the contention window, allocate priorities to the accessed nodes, and dynamically adjust the priorities according to the network congestion degree of the nodes during the network operation. High-priority nodes can be allocated fixed time slots and have a higher contention priority in the contention window, while low-priority nodes participate in the time slot contention in the contention window and perform the transceiver of service data after successful contention. The present invention can dynamically adjust the priorities of nodes, the allocation of fixed time slots, and the contention priorities in the contention window to adapt to the real-time changes of the communication traffic and the number of nodes in the network, effectively avoid congestion conflicts and waste of channel resources, and ensure the maximum utilization of network channel resources. Description of the Drawings

[0065] Figure 1 Schematic diagram of the frame structure of the MAC layer hybrid networking method of the present invention;

[0066] Figure 2 Flowchart of the node dynamic priority update mechanism and time slot allocation of the present invention;

[0067] Figure 3 Schematic diagram of the frame structure when a small number of initial nodes access in the present invention;

[0068] Figure 4 Schematic diagram of the frame structure of time slot reallocation in the unsaturated state when the node priority period update is reached in the present invention;

[0069] Figure 5 Schematic diagram of the hybrid MAC protocol frame structure reaching the saturated state in the present invention;

[0070] Figure 6 Schematic diagram of the frame structure of time slot reallocation after node priority update when the hybrid MAC protocol frame structure of the present invention reaches the saturated state.

[0071] Figure 7 Schematic diagram of the hybrid MAC protocol frame structure of the present invention transitioning from the saturated state to the unsaturated state;

[0072] Figure 8 Schematic diagram of a failed node exiting the network in the present invention. Detailed implementation manners

[0073] Detailed implementation manner one: Combining Figure 2 This embodiment is described. An adaptive unmanned cluster MAC layer hybrid networking method described in this embodiment specifically includes the following steps:

[0074] Step 1, initialize the protocol frame length of the MAC layer to M service time slots (in the present invention, the value of M is 100, and the length of each time slot is 1 ms, that is, the period of the protocol frame is 100 ms);

[0075] Step 2, initialize the protocol frame count t = 1;

[0076] Step 3: Determine whether the t-th protocol frame reaches the node priority update period (when t = 1, it is defaulted to reach the node priority update period. The network congestion metrics of each node in the MAC layer are statistically collected before the start of the first protocol frame, and the priorities of each node are calculated). The node priority update period is set to 10M (that is, in the present invention, the network congestion metrics of the nodes need to be collected and the node priorities need to be updated respectively after the 10th protocol frame, after the 20th protocol frame, and after the 30th protocol frame, and so on. After every 10 protocol frames, the node priorities are updated once. Within the 10 protocol frames of one update period, the node priorities remain unchanged).

[0077] The priority of the newly added node in the previous protocol frame is calculated according to the initialization parameters, and then the node priority is updated by collecting the network congestion metrics every time the priority update period arrives.

[0078] If the t-th protocol frame reaches the node priority update period, then before the start of the t-th protocol frame, collect the network congestion metrics of the historical access nodes, and update the priorities of the historical access nodes according to the collected network congestion metrics; then execute Step 4.

[0079] If the t-th protocol frame does not reach the node priority update period, then directly execute Step 5.

[0080] Step 4: Determine the fixed time slot (in the fixed time slot, only the node allocated to this time slot can perform the transceiver of service data, that is, only the node allocated to this time slot can communicate) and the window position of the contention time slot according to the updated priorities of the historical access nodes and the priorities of the new nodes accessed in the (t - 1)-th protocol frame. All nodes participate in the time slot contention according to the allocated contention probability in the contention time slot, and then perform the transceiver of service data after successfully contending.

[0081] After all the time slots of the t-th protocol frame end, let t = t + 1, and return to execute Step 3.

[0082] Step 5: Determine the fixed time slot and the window position of the contention time slot according to the priorities of the historical access nodes (which do not need to be updated currently) and the priorities of the new nodes accessed in the (t - 1)-th protocol frame. All nodes participate in the time slot contention according to the allocated contention probability in the contention time slot, and then perform the transceiver of service data after successfully contending.

[0083] After all the time slots of the t-th protocol frame end, let t = t + 1, and return to execute Step 3.

[0084] It should be noted that the unmanned cluster in the present invention refers to a cluster including unmanned aerial vehicles and unmanned vehicles. Each unmanned system is regarded as a node, and the communication process between nodes can be realized by the method of the present invention.

[0085] Embodiment 2: The difference between this embodiment and Embodiment 1 is that the method broadcasts the window position information of the fixed time slots and contention time slots in the current protocol frame of the MAC layer in real time through a network controller.

[0086] Other steps and parameters are the same as those in Embodiment 1.

[0087] Embodiment 3: The difference between this embodiment and Embodiment 1 or 2 is that the new node obtains the contention time slot window position according to the information broadcast by the network controller, and then randomly selects a contention time slot from within the contention time slot window to send an access request message;

[0088] The access request message includes the node ID, an estimated value of the buffer queue length, an estimated value of the packet delay, and an estimated value of the packet loss rate.

[0089] Other steps and parameters are the same as those in Embodiment 1 or 2.

[0090] As Figure 3 shown is a schematic diagram of the frame structure during the initial access of a small number of nodes in the present invention. When a new node joins the network, it first listens to the hybrid MAC protocol frame structure information broadcast by the network controller to obtain the position and length of the contention window. The node randomly selects a time slot within the contention window to send an access request message, and the message content includes the node ID, buffer queue length, packet delay, and estimated value of the packet loss rate. After initiating the access request message, the node can compete for access to the network from the contention window.

[0091] Embodiment 4: The difference between this embodiment and any one of Embodiments 1 to 3 is that the calculation method of the priority of the node is:

[0092]

[0093] where BL represents the buffer queue length of the node, PD represents the packet delay of the node, PLR represents the packet loss rate of the node, ω1, ω2, and ω3 are all weights (set to 0.5, 0.3, and 0.2 respectively), P represents the priority of the node, α represents the buffer queue length threshold, β represents the packet delay threshold, and γ represents the packet loss rate threshold;

[0094] If the priority P of the node ≥ 0.7, then the node is a high-priority node and the priority flag is set to 1; if the priority P of the node < 0.7, then the node is a low-priority node and the priority flag is set to 0.

[0095] Other steps and parameters are the same as any one of Embodiments 1 to 3.

[0096] In the present invention, the values of the thresholds α, β, and γ can be obtained based on historical data (in the present invention, the value of the threshold α is 100, the value of the threshold β is 500 ms, and the value of the threshold γ is 10%). Generally, the length of the buffer queue of a node does not exceed the threshold α, the packet delay does not exceed the threshold β, and the packet loss rate does not exceed γ. Based on the thresholds α, β, and γ, the network congestion metrics of the node can be normalized, and then the node priority can be calculated based on the normalized network congestion metrics. The priority update of the historical access nodes and the priority of the newly accessed nodes are both calculated using the method of this embodiment.

[0097] Specific Embodiment 5: The difference between this embodiment and one of Embodiments 1 to 4 is that the specific process of Step 4 is as follows:

[0098] Step 4-1: Determine whether there is a node that has not communicated (i.e., has not performed service transmission and reception) in the (t-3)th protocol frame, the (t-2)th protocol frame, and the (t-1)th protocol frame.

[0099] If there is a node that has not communicated in the (t-3)th protocol frame, the (t-2)th protocol frame, and the (t-1)th protocol frame, such a node exits the network from the contention window. As Figure 8 shown in the schematic diagram of the failed node exiting the network of the present invention, when a node has not communicated for 3 consecutive frames, if the node is a high-priority node, the node automatically releases its fixed time slot resources and exits the network from the contention window; if the node is a low-priority node, it directly exits the network from the contention window, and then continues to execute Step 4-2 for the remaining nodes.

[0100] If there is no node that has not communicated in the (t-3)th protocol frame, the (t-2)th protocol frame, and the (t-1)th protocol frame, directly execute Step 4-2.

[0101] Step 4-2: For a node a that was a high-priority node in the previous cycle (referring to the node priority update cycle) and whose updated priority is a low priority:

[0102] If node a occupied a fixed time slot in the previous protocol frame, after releasing the fixed time slot resources of node a, the transmission and reception services of node a are allocated to the contention time slot window, and the contention probability of node a is set to 20%.

[0103] If node a did not occupy a fixed time slot in the previous protocol frame (i.e., the fixed time slot was saturated in the previous protocol frame, and node a was not allocated a fixed time slot in the previous protocol frame. As Figure 5The figure shows a schematic diagram of the hybrid MAC protocol frame structure reaching the saturation state. There are 90 fixed time slots in the frame structure. Correspondingly, the number of contention window time slots in the frame structure is reduced to the minimum limit of 10. Then, the transceiver services of node a are still allocated to the contention time slot window, and the contention probability of node a is adjusted to 20%;

[0104] Then execute step 43;

[0105] Step 43: Count the number N of high-priority nodes in the t-th protocol frame. Among them, the high-priority nodes in the t-th protocol frame include nodes that were high-priority in the previous cycle and whose updated priority is still high-priority, nodes that were low-priority in the previous cycle and whose updated priority is high-priority, and high-priority nodes newly accessed in the (t - 1)-th protocol frame;

[0106] If the number N of high-priority nodes in the t-th protocol frame is less than or equal to 0.9M (that is, set the length of the fixed time slot not to exceed 90% of the protocol frame length. When the ratio of the fixed time slot reaches 90%, it reaches the saturation state), then allocate a fixed time slot to each high-priority node, and set the contention probability of each high-priority node in the contention time slot to 80%; Then execute step 48;

[0107] If the number N of high-priority nodes in the t-th protocol frame is greater than 0.9M, then execute step 44;

[0108] Step 44: Judge whether there are high-priority nodes that meet condition (1) among the high-priority nodes in the t-th protocol frame. Condition (1) is specifically: high-priority nodes that were allocated fixed time slots and did not perform service transceiver in the previous protocol frame;

[0109] If there are high-priority nodes that meet condition (1), then when the number of high-priority nodes that meet condition (1) is less than or equal to N - 0.9M, execute step 45; when the number of high-priority nodes that meet condition (1) is greater than N - 0.9M, then execute step 46;

[0110] If there are no high-priority nodes that meet condition (1), then directly execute step 47;

[0111] Step 45: Release the fixed time slot resources of all high-priority nodes that meet condition (1), transfer all high-priority nodes that meet condition (1) to the contention time slot and set the contention probability to 80%, and then remove all high-priority nodes that meet condition (1) from the N high-priority nodes in the t-th protocol frame;

[0112] Randomly select 0.9M nodes from the remaining high-priority nodes (i.e., high-priority nodes that do not meet condition (1)), and assign a fixed time slot to each selected high-priority node. The competition probability of each selected high-priority node within the contention time slot is set to 80%; transfer each unselected high-priority node to the contention time slot, and set the competition probability of each unselected high-priority node within the contention time slot to 80%;

[0113] Then execute step 48;

[0114] Step 46: Randomly select N - 0.9M from all high-priority nodes that meet condition (1), release the fixed time slot resources of the selected high-priority nodes, transfer the selected high-priority nodes to the contention time slot and set the competition probability to 80%, then assign a fixed time slot to each of the remaining high-priority nodes, and set the competition probability of the remaining high-priority nodes within the contention time slot to 80%;

[0115] Then execute step 48;

[0116] Step 47: Randomly select 0.9M from all high-priority nodes, assign a fixed time slot to each selected high-priority node, and set the competition probability of each selected high-priority node within the contention time slot to 80%; transfer each unselected high-priority node to the contention time slot, and set the competition probability of each unselected high-priority node within the contention time slot to 80%;

[0117] Then execute step 48;

[0118] Step 48: Assign the low-priority nodes within the t-th protocol frame to the contention time slot, and set the competition probability of each low-priority node within the contention time slot to 20%.

[0119] Other steps and parameters are the same as those in any one of the specific embodiments 1 to 4.

[0120] After determining the number of fixed time slots and contention time slots according to the node priority situation, within the protocol frame, the previous time slots are fixed time slots, and the subsequent time slots are contention time slots, that is, the window positions of the fixed time slots and contention time slots are determined. As Figure 1 shown in the frame structure diagram of the MAC layer hybrid networking method of the present invention, nodes marked as high-priority are assigned 1 fixed time slot resource, and it is set that they participate in the contention time slot with an 80% probability within the contention window; nodes marked as low-priority are not assigned fixed time slot resources, and it is set that they participate in the contention time slot with a 20% probability within the contention window; if there are k high-priority nodes, then the number of contention window time slots is 100 - k (the number of contention window time slots is not less than 10).

[0121] Embodiment Six: The difference between this embodiment and any one of Embodiments One to Five is that the specific process of Step Five is as follows:

[0122] Step Five One: Determine whether there are nodes that have not communicated (i.e., have not performed service transmission and reception) within the (t - 3)th protocol frame, the (t - 2)th protocol frame, and the (t - 1)th protocol frame;

[0123] If there are nodes that have not communicated within the (t - 3)th protocol frame, the (t - 2)th protocol frame, and the (t - 1)th protocol frame, the nodes will exit the network from the contention window (i.e., perform node failure handling), and then continue to execute Step Five Two for the remaining nodes;

[0124] If there are no nodes that have not communicated within the (t - 3)th protocol frame, the (t - 2)th protocol frame, and the (t - 1)th protocol frame, directly execute Step Five Two;

[0125] Step Five Two: Count the number N of high - priority nodes within the t - th protocol frame. Among them, the high - priority nodes within the t - th protocol frame include the historically - accessed high - priority nodes and the newly - accessed high - priority nodes within the (t - 1)th protocol frame;

[0126] If the number N of high - priority nodes within the t - th protocol frame is less than or equal to 0.9M (i.e., set the length of the fixed time slot not to exceed 90% of the protocol - frame length. When the proportion of the fixed time slot reaches 90%, it reaches the saturation state), assign a fixed time slot to each high - priority node, and set the contention probability of each high - priority node within the contention time slot to 80%; then execute Step Five Seven;

[0127] If the number N of high - priority nodes within the t - th protocol frame is greater than 0.9M, execute Step Five Three;

[0128] Step Five Three: Determine whether there are high - priority nodes that meet Condition (1) among the high - priority nodes within the t - th protocol frame. Condition (1) is specifically: high - priority nodes that were assigned a fixed time slot in the previous protocol frame and did not perform service transmission and reception;

[0129] If there are high - priority nodes that meet Condition (1), when the number of high - priority nodes that meet Condition (1) is less than or equal to N - 0.9M, execute Step Five Four; when the number of high - priority nodes that meet Condition (1) is greater than N - 0.9M, execute Step Five Five;

[0130] If there are no high - priority nodes that meet Condition (1), directly execute Step Five Six;

[0131] Step Five Four: Release the fixed time slot resources of all high-priority nodes that meet condition (1), transfer all high-priority nodes that meet condition (1) to the contention time slot and set their contention probabilities to 80%, and then remove all high-priority nodes that meet condition (1) from the N high-priority nodes in the t-th protocol frame;

[0132] Then randomly select 0.9M nodes from the remaining high-priority nodes, allocate a fixed time slot to each selected high-priority node respectively, and set the contention probability of each selected high-priority node in the contention time slot to 80%; transfer each unselected high-priority node to the contention time slot and set the contention probability of each unselected high-priority node in the contention time slot to 80%;

[0133] Then execute Step Five Seven;

[0134] Step Five Five: Randomly select N - 0.9M from all high-priority nodes that meet condition (1), release the fixed time slot resources of the selected high-priority nodes, transfer the selected high-priority nodes to the contention time slot and set the contention probability to 80%, then allocate a fixed time slot to each of the remaining high-priority nodes respectively, and set the contention probability of the remaining high-priority nodes in the contention time slot to 80%;

[0135] Then execute Step Five Seven;

[0136] Step Five Six: Randomly select 0.9M from all high-priority nodes, allocate a fixed time slot to each selected high-priority node respectively, and set the contention probability of each selected high-priority node in the contention time slot to 80%; transfer each unselected high-priority node to the contention time slot and set the contention probability of each unselected high-priority node in the contention time slot to 80%;

[0137] Then execute Step Five Seven;

[0138] Step Five Seven: Allocate the low-priority nodes in the t-th protocol frame to the contention time slot, and set the contention probability of each low-priority node in the contention time slot to 20%.

[0139] Other steps and parameters are the same as those in any one of the specific embodiments one to five.

[0140] Such as Figure 4The figure shows the schematic diagram of the frame structure for time slot reallocation when the node priority update period of the present invention is reached. When there are too many high-priority nodes in the network, the network controller will release the fixed time slot resources of the nodes that were high-priority in the previous period but are adjusted to low-priority in the current period, allocate their service transceiver to the contention window, and reduce their contention probability to 20%. For the nodes that were low-priority in the previous period but are adjusted to high-priority in the current period, when the fixed time slots of the network are not saturated, the network controller will directly allocate new fixed time slot resources for them and increase their contention probability in the contention window to 80%. When the fixed time slots of the network are saturated, the network controller will handle them randomly, that is, allocate fixed time slots for them or transfer them to the contention time slots. However, in any case, their contention probability in the contention time slots is 80%. Assuming that after the adjustment in the above monitoring period, the ratio of the fixed time slots to the contention time slots has not reached the saturation value (that is, the proportion of the fixed time slots is less than 90% and the proportion of the contention time slots is greater than 10%), if there are m high-priority nodes adjusted to low-priority and n low-priority nodes adjusted to high-priority, then the number of fixed time slot resources in the frame structure of the adjusted period becomes k - m + n, and correspondingly, the number of contention window time slots becomes 100 - k + m - n. Each node in the network will perform service transceiver according to the adjusted time slot allocation in the new period.

[0141] As Figure 6 The figure shows the schematic diagram of the frame structure for time slot reallocation after cycle update when the hybrid MAC protocol frame structure of the present invention reaches the saturation state. The network controller monitors that the hybrid MAC protocol frame structure reaches the saturation state in a certain period. If there are no newly upgraded high-priority nodes in the current period, the nodes that need to be downgraded to low-priority will release the fixed time slot resources and be downgraded to low-priority nodes. If there are still newly upgraded high-priority nodes in the current period, the network controller will randomly select some or all of the nodes that have been allocated fixed time slots in the previous protocol frame and have not performed service transceiver in the previous protocol frame (the number of selected nodes needs to be determined according to the saturation degree of the network), release the fixed time slot resources of the selected nodes, and the services of the nodes whose fixed time slots are released will be transferred to the contention window, and their contention probability remains 80% unchanged in this protocol frame. After releasing some fixed time slot resources, they are used for time slot allocation for other high-priority nodes. If a node's priority is updated to high-priority when the next priority update period arrives, the fixed time slot allocation step for high-priority nodes will be performed normally. If a node's priority is updated to low-priority when the next priority update period arrives, the network controller will also lower its contention probability in the contention window to 20%, that is, it is officially adjusted to a low-priority node.

[0142] As Figure 7The figure shows a schematic diagram of the hybrid MAC protocol frame structure of the present invention transitioning from a saturated state to an unsaturated state. The network controller monitors in a certain period that the hybrid MAC protocol frame structure transitions from a saturated state to an unsaturated state, that is, when entering the current period, the number of fixed time slots in the frame structure is less than 90, and the number of contention window time slots is greater than 10.

[0143] Embodiment 7: The difference between this embodiment and any one of Embodiments 1 to 6 is that when a node conflict occurs within the contention time slot, the high-priority node continues to participate in the time slot contention in the next contention time slot, and the low-priority node continues to participate in the time slot contention after backing off 5 contention time slots.

[0144] Other steps and parameters are the same as any one of Embodiments 1 to 6.

[0145] The above numerical examples of the present invention are only for explaining in detail the calculation model and calculation process of the present invention, rather than limiting the embodiments of the present invention. For those of ordinary skill in the art, other different forms of changes or variations can be made based on the above description. It is impossible to list all the embodiments here. Any obvious changes or variations derived from the technical solutions of the present invention still fall within the protection scope of the present invention.

Claims

1. An adaptive MAC layer hybrid networking method for unmanned clusters, characterized in that The method specifically includes the following steps: Step 1: Initialize the protocol frame length of the MAC layer to M service time slots; Step 2: Initialize the protocol frame count t = 1; Step 3: Determine whether the t-th protocol frame reaches the node priority update period, and the node priority update period is set to 10M; If the t-th protocol frame reaches the node priority update period, then before the start of the t-th protocol frame, collect the network congestion metrics of the historical access nodes, and update the priorities of the historical access nodes according to the collected network congestion metrics; then execute Step 4; If the t-th protocol frame does not reach the node priority update period, then directly execute Step 5; Step 4: Determine the window positions of the fixed time slot and the contention time slot according to the updated priorities of the historical access nodes and the priorities of the new nodes accessed in the (t - 1)-th protocol frame. All nodes participate in the time slot contention within the contention time slot according to the allocated contention probability, and after successful contention, they send and receive service data; After all time slots of the t-th protocol frame end, let t = t + 1, and return to execute Step 3; Step 5: Determine the window positions of the fixed time slot and the contention time slot according to the priorities of the historical access nodes and the priorities of the new nodes accessed in the (t - 1)-th protocol frame. All nodes participate in the time slot contention within the contention time slot according to the allocated contention probability, and after successful contention, they send and receive service data; After all time slots of the t-th protocol frame end, let t = t + 1, and return to execute Step 3.

2. An adaptive unmanned cluster MAC layer hybrid networking method according to claim 1, characterized in that The method broadcasts the window position information of the fixed time slot and the contention time slot in the current protocol frame of the MAC layer through the network controller in real time.

3. An adaptive unmanned cluster MAC layer hybrid networking method according to claim 2, characterized in that, The new node obtains the contention time slot window position according to the information broadcast by the network controller, and then randomly selects a contention time slot from within the contention time slot window to send an access request message; The access request message includes the node ID, the estimated value of the buffer queue length, the estimated value of the packet delay, and the estimated value of the packet loss rate.

4. An adaptive unmanned cluster MAC layer hybrid networking method according to claim 1, characterized in that The calculation method of the priority of the node is as follows: Where BL represents the buffer queue length of the node, PD represents the packet delay of the node, PLR represents the packet loss rate of the node, ω1, ω2, and ω3 are all weights, P represents the priority of the node, α represents the buffer queue length threshold, β represents the packet delay threshold, and γ represents the packet loss rate threshold; If the priority P of the node ≥ 0.7, then the node is a high-priority node; if the priority P of the node < 0.7, then the node is a low-priority node.

5. An adaptive unmanned cluster MAC layer hybrid networking method according to claim 1, characterized in that, The specific process of Step 4 is as follows: Step 4-1: Determine whether there are nodes that have not communicated in the (t - 3)-th protocol frame, the (t - 2)-th protocol frame, and the (t - 1)-th protocol frame; If there are nodes that have not communicated in the (t - 3)-th protocol frame, the (t - 2)-th protocol frame, and the (t - 1)-th protocol frame, then the nodes exit the network from the contention window, and then continue to execute Step 4-2 for the remaining nodes; If there are no nodes that have not communicated in the (t - 3)-th protocol frame, the (t - 2)-th protocol frame, and the (t - 1)-th protocol frame, then directly execute Step 4-2; Step 4-2: For node a that was a high-priority node in the previous cycle and whose updated priority is a low priority: If node a occupied a fixed time slot in the previous protocol frame, after releasing the fixed time slot resource of node a, allocate the transceiver services of node a to the contention time slot window, and set the contention probability of node a to 20%; If node a did not occupy a fixed time slot in the previous protocol frame, still allocate the transceiver services of node a to the contention time slot window, and adjust the contention probability of node a to 20%; Then execute step 43; Step 43: Count the number N of high-priority nodes in the t-th protocol frame. Among them, the high-priority nodes in the t-th protocol frame include nodes that were high-priority in the previous cycle and whose updated priority is still high-priority, nodes that were low-priority in the previous cycle and whose updated priority is high-priority, and high-priority nodes newly accessed in the (t - 1)-th protocol frame; If the number N of high-priority nodes in the t-th protocol frame is less than or equal to 0.9M, allocate a fixed time slot to each high-priority node, and set the contention probability of each high-priority node in the contention time slot to 80%; Then execute step 48; If the number N of high-priority nodes in the t-th protocol frame is greater than 0.9M, execute step 44; Step 44: Determine whether there is a high-priority node that satisfies condition (1) among the high-priority nodes in the t-th protocol frame. Condition (1) is specifically: a high-priority node that was allocated a fixed time slot in the previous protocol frame and did not perform service transceiver; If there is a high-priority node that satisfies condition (1), when the number of high-priority nodes that satisfy condition (1) is less than or equal to N - 0.9M, execute step 45; when the number of high-priority nodes that satisfy condition (1) is greater than N - 0.9M, execute step 46; If there is no high-priority node that satisfies condition (1), directly execute step 47; Step 45: Release the fixed time slot resources of all high-priority nodes that satisfy condition (1), transfer all high-priority nodes that satisfy condition (1) to the contention time slot and set the contention probability to 80%, and then remove all high-priority nodes that satisfy condition (1) from the N high-priority nodes in the t-th protocol frame; Then randomly select 0.9M nodes from the remaining high-priority nodes, allocate a fixed time slot to each selected high-priority node, and set the contention probability of each selected high-priority node in the contention time slot to 80%; Transfer each unselected high-priority node to the contention time slot, and set the contention probability of each unselected high-priority node in the contention time slot to 80%; Then execute step 48; Step 46: Randomly select N - 0.9M from all high-priority nodes that satisfy condition (1), release the fixed time slot resources of the selected high-priority nodes, transfer the selected high-priority nodes to the contention time slot and set the contention probability to 80%, and then allocate a fixed time slot to each of the remaining high-priority nodes, and set the contention probability of the remaining high-priority nodes in the contention time slot to 80%; Then execute step 48; Step 47: Randomly select 0.9M from all high-priority nodes, and assign a fixed time slot to each selected high-priority node. Set the competition probability of each selected high-priority node in the contention time slot to 80%. Transfer each unselected high-priority node to the contention time slot and set the competition probability of each unselected high-priority node in the contention time slot to 80%. Then execute Step 48; Step 48: Assign the low-priority nodes in the t-th protocol frame to the contention time slot, and set the competition probability of each low-priority node in the contention time slot to 20%.

6. An adaptive unmanned cluster MAC layer hybrid networking method according to claim 1, characterized in that The specific process of the said Step 5 is as follows: Step 51: Determine whether there are nodes that have not communicated in the (t - 3)-th, (t - 2)-th, and (t - 1)-th protocol frames; If there are nodes that have not communicated in the (t - 3)-th, (t - 2)-th, and (t - 1)-th protocol frames, the nodes exit the network from the contention window, and then continue to execute Step 52 for the remaining nodes; If there are no nodes that have not communicated in the (t - 3)-th, (t - 2)-th, and (t - 1)-th protocol frames, directly execute Step 52; Step 52: Count the number N of high-priority nodes in the t-th protocol frame. The high-priority nodes in the t-th protocol frame include the historically accessed high-priority nodes and the newly accessed high-priority nodes in the (t - 1)-th protocol frame; If the number N of high-priority nodes in the t-th protocol frame is less than or equal to 0.9M, assign a fixed time slot to each high-priority node and set the competition probability of each high-priority node in the contention time slot to 80%. Then execute Step 57; If the number N of high-priority nodes in the t-th protocol frame is greater than 0.9M, execute Step 53; Step 53: Determine whether there are high-priority nodes that meet Condition (1) among the high-priority nodes in the t-th protocol frame. Condition (1) is specifically: high-priority nodes that were assigned a fixed time slot in the previous protocol frame and did not perform service transmission or reception; If there are high-priority nodes that meet Condition (1), when the number of high-priority nodes that meet Condition (1) is less than or equal to N - 0.9M, execute Step 54; when the number of high-priority nodes that meet Condition (1) is greater than N - 0.9M, execute Step 55; If there are no high-priority nodes that meet Condition (1), directly execute Step 56; Step 54: Release the fixed time slot resources of all high-priority nodes that meet Condition (1), transfer all high-priority nodes that meet Condition (1) to the contention time slot and set the competition probability to 80%, and then remove all high-priority nodes that meet Condition (1) from the N high-priority nodes in the t-th protocol frame; Randomly select 0.9M nodes from the remaining high-priority nodes, and allocate a fixed time slot to each selected high-priority node. The competition probability of each selected high-priority node in the contention time slot is set to 80%; transfer each unselected high-priority node to the contention time slot, and set the competition probability of each unselected high-priority node in the contention time slot to 80%; Then execute step 57; Step 55: Randomly select N - 0.9M from all high-priority nodes that meet condition (1), release the fixed time slot resources of the selected high-priority nodes, transfer the selected high-priority nodes to the contention time slot and set the competition probability to 80%, then allocate a fixed time slot to each of the remaining high-priority nodes, and set the competition probability of the remaining high-priority nodes in the contention time slot to 80%; Then execute step 57; Step 56: Randomly select 0.9M from all high-priority nodes, allocate a fixed time slot to each selected high-priority node, and set the competition probability of each selected high-priority node in the contention time slot to 80%; transfer each unselected high-priority node to the contention time slot, and set the competition probability of each unselected high-priority node in the contention time slot to 80%; Then execute step 57; Step 57: Allocate the low-priority nodes in the t-th protocol frame to the contention time slot, and set the competition probability of each low-priority node in the contention time slot to 20%.

7. An adaptive unmanned cluster MAC layer hybrid networking method according to claim 1, characterized in that When node conflicts occur in the contention time slot, high-priority nodes continue to participate in time slot competition in the next contention time slot, and low-priority nodes continue to participate in time slot competition after avoiding 5 contention time slots.

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