Anti-collision communication method for wireless temperature measurement sensor based on dynamic time slot contention and cluster scheduling cooperation

Abstract

The present application relates to wireless sensing communication technical field, specifically relates to wireless temperature sensing sensor anti-collision communication method based on dynamic time slot competition and clustering scheduling cooperation, including the following steps: the master station broadcasts beacon frame, for synchronizing time, the time slot allocation diagram of current superframe is issued; ACK confirmation and key monitoring are carried out to alarm node, and the alarm node that completes alarm report is removed from the clustering scheduling queue; special scheduling time slot is allocated for each cluster in the clustering scheduling period, and each cluster node is guided to complete data reporting in the time slot; the alarm node is automatically migrated to the normal node after the alarm is removed, and participates in cluster division and clustering scheduling again.The present application improves the overall channel utilization, effectively reduces the energy consumption and communication burden of low active nodes without sacrificing the communication success rate, and enhances the network life.

Description

Technical Field

[0001] This invention relates to the field of wireless sensor communication technology, and in particular to a collision avoidance communication method for wireless temperature sensors based on dynamic time slot contention and cluster scheduling coordination. Background Technology

[0002] Wireless temperature sensor systems are widely used in power equipment, industrial equipment, and warehousing facilities to achieve real-time monitoring and early warning of anomalies at critical nodes. In these systems, multiple sensor nodes wirelessly upload temperature data to the main control terminal periodically or in event-triggered manner. However, with the expansion of the monitoring area and the increase in the number of nodes, traditional communication protocols face many challenges in actual deployment, especially in issues such as channel congestion caused by simultaneous reporting by nodes, frequent data conflicts, and severe alarm reporting delays. These problems seriously affect the timeliness of response to abnormal temperature events and the overall energy efficiency of the system.

[0003] Most existing anti-collision communication methods rely on fixed polling scheduling or static clustering mechanisms. Their advantages are clear structure and ease of implementation, but they are difficult to adapt to the actual situation of sudden surges in alarm nodes or dynamic changes in the communication environment in large-scale networks. On the one hand, emergency reporting nodes cannot obtain scheduling priority, and there is a risk of delay or loss of temperature anomaly information; on the other hand, static clusters lack the ability to perceive communication stability, resulting in a serious disconnect between scheduling resource allocation and actual network conditions, further causing scheduling conflicts and high energy consumption. To this end, some studies have attempted to introduce competition mechanisms and cluster-level scheduling models, but key problems still remain unresolved: (1) lack of fine design of alarm node priority and master station feedback mechanism, which easily leads to repeated reporting and redundant congestion; (2) nodes cannot achieve adaptive reallocation of scheduling resources after state transition, affecting communication efficiency; (3) failure to consider the dynamic perception of node communication stability and the differentiated configuration of clustering scheduling parameters, resulting in low resource utilization and weak energy consumption control. Summary of the Invention

[0004] This invention provides a collision prevention communication method for wireless temperature sensors based on dynamic time slot contention and cluster scheduling collaboration. It can simultaneously support dynamic contention access, high-priority alarm reporting, adaptive cluster scheduling for communication stability, and closed-loop control of state transition to improve reliability, real-time performance, and energy efficiency in real-world complex environments.

[0005] A collision avoidance communication method for wireless temperature sensors based on dynamic time slot contention and cluster scheduling collaboration includes a master station and multiple wireless temperature sensor nodes. The wireless temperature sensor nodes are divided into regular nodes that report data at fixed intervals and alarm nodes that report immediately when the temperature exceeds a threshold. The method includes the following steps: S1, the master station broadcasts a beacon frame, used to synchronize time and send the time slot allocation diagram of the current superframe. The superframe includes at least a contention access period for communication between alarm nodes and newly joined nodes, and a clustering scheduling period for communication between regular nodes. S2, the alarm node and the newly joined node report data using the dynamic frame slot ALOHA protocol during the contention access period. The master station performs ACK confirmation and key monitoring on the alarm node based on whether it receives the alarm reporting frame, and removes the alarm node that has completed the alarm reporting from the cluster scheduling queue. S3, the master station divides the regular nodes into multiple clusters based on the historical communication records and communication frequency of the regular nodes, and allocates a dedicated scheduling time slot for each cluster during the cluster scheduling period, guiding each cluster node to complete data reporting within its assigned time slot; wherein, the master station dynamically adjusts the length ratio of the contention access period and the cluster scheduling period in the superframe based on the proportion of alarm nodes. S4, after the alarm is cleared, the alarm node automatically migrates to a regular node and re-participates in cluster partitioning and cluster scheduling; for regular nodes with slow communication data changes, the master station extends their scheduling cycle to reduce time slot occupation and energy consumption.

[0006] Optionally, the master station broadcasts the beacon frame at a fixed period, and the beacon frame includes at least: The start timestamp of the current superframe is used for all nodes to synchronize their time with the master station; The current superframe structure definition includes the start position and length of the contention access period and the start position and length of the cluster scheduling period; The current superframe time slot allocation diagram specifically defines the start and end times of the dedicated scheduling time slots allocated to each cluster during the cluster scheduling period.

[0007] Optionally, after receiving the beacon frame, all nodes calibrate their local clocks according to the start timestamp and determine their communication behavior in subsequent time periods based on the structure definition and time slot allocation diagram. Specifically, alarm nodes and newly joined nodes compete for access according to the protocol during the contention access period, while regular nodes report when their dedicated scheduling time slot for their own cluster arrives during the cluster scheduling period.

[0008] Optionally, in S2, during the contention access period, the alarm node and the new network node, based on the timing of the beacon frame synchronization, randomly select one time slot within a contention window consisting of multiple equal-length time slots to send a data frame; wherein, the alarm node sends an alarm reporting frame including temperature exceeding the threshold information, and the new network node sends a network access request frame. The master station monitors each time slot within the contention window and determines the reception status of each time slot: if a unique data frame is correctly received and decoded in a certain time slot, the time slot contention is determined to be successful, and the master station then broadcasts confirmation information including a successful node identifier in the subsequent feedback period; if no signal is detected in a certain time slot or decoding failure caused by a collision is detected, the time slot contention is determined to be unsuccessful.

[0009] Optionally, in S2, for alarm nodes that have successfully reported, in addition to sending ACK confirmation, the master station will also conduct key monitoring on them by carrying a specific identifier in the beacon frames they broadcast in the subsequent superframe cycles. At the same time, the main station will temporarily remove the identifier of the alarm node that was successfully reported from its regular node cluster scheduling queue, so that it will no longer occupy the dedicated scheduling time slot of the cluster scheduling period during the duration of the alarm status.

[0010] Optionally, in S3: The clustering of regular nodes specifically includes: the main station statistically analyzes the average data reporting interval, historical communication success rate and data packet size of each regular node in the past preset period, and clusters nodes with similar reporting intervals and similar communication characteristics into the same cluster; The allocation of scheduling time slots specifically includes: calculating and allocating one or more continuous or non-contiguous logical time slot blocks for each cluster based on the length of the current superframe, the available duration of the cluster scheduling period, and the number of nodes included in each cluster, and notifying all nodes through the time slot allocation diagram in the beacon frame.

[0011] Optionally, the dynamic adjustment of the length ratio of the contention access period to the cluster scheduling period in the superframe specifically includes: The main station calculates the ratio of the total number of nodes in alarm state to the total number of nodes in the network as the alarm ratio. According to the preset mapping relationship, when the alarm ratio increases, the length of the contention access period in the current and several subsequent superframes is increased, and the length of the cluster scheduling period is reduced accordingly to ensure the timeliness of alarm reporting. When the alarm ratio decreases, the adjustment is reversed.

[0012] Optionally, during the process of the main station performing cluster division on regular nodes, it also includes constructing a corresponding node communication stability evaluation result based on the temperature change amplitude, temperature change trend stability, and historical reporting success rate of each regular node over multiple consecutive superframe cycles. The construction of the node communication stability evaluation result includes: the master station records the temperature values ​​reported by each regular node in multiple consecutive superframe periods, and calculates the variance of its temperature change amplitude as the first evaluation factor; the temperature change trend is analyzed by linear regression, and the standard deviation of the regression residual is used as the second evaluation factor for trend stability; the number of successful reports by the node in multiple historical scheduling reports is counted, and the reporting success rate is calculated as the third evaluation factor; the first evaluation factor, the second evaluation factor, and the third evaluation factor are weighted and summed to obtain the node communication stability evaluation value; Based on the node communication stability assessment results, the master station sets differentiated cluster-level scheduling parameters for different clusters. The cluster-level scheduling parameters include at least the cluster-level scheduling cycle length, cluster-level time slot allocation density, or cluster-level scheduling priority. This allows clusters with high communication stability to use low-frequency or extended-cycle scheduling methods, while clusters with low communication stability use high-frequency or compact time slot scheduling methods. The updated cluster-level scheduling parameters are then sent out via subsequent beacon frames.

[0013] Optionally, the master station sets differentiated cluster-level scheduling parameters for different clusters based on the node communication stability assessment results. Specifically, this includes: the master station calculating the average communication stability assessment value of all nodes in each cluster as the cluster-level stability; pre-setting at least three stability levels and corresponding scheduling parameter templates for the master station; classifying each cluster into different levels according to its cluster-level stability and applying the corresponding level's scheduling parameter template to the cluster. For clusters with high cluster-level stability, the applied template is configured with a longer cluster-level scheduling cycle and / or a lower cluster-level time slot allocation density; for clusters with low cluster-level stability, the applied template is configured with a shorter cluster-level scheduling cycle and / or a higher cluster-level time slot allocation density, and its cluster-level scheduling priority is set to higher; the updated cluster-level scheduling parameters are distributed to all nodes in the corresponding cluster through the beacon frames broadcast in the next one or several cycles.

[0014] Optionally, the automatic migration to a regular node specifically includes: when a node detects that its temperature value has recovered to below the alarm temperature threshold for several consecutive sampling periods, it determines that the alarm has been cleared, and in the next contention access period, it sends a status update frame containing its identifier and status migration declaration to the master station; after receiving the status update frame, the master station confirms that its alarm status has been cleared, updates its status mark to a regular node, and re-includes it in the management queue of regular nodes; based on the regular node's past communication records, current temperature change characteristics, and the latest node communication stability assessment results, the master station reassigns it to a matching cluster, and allocates a dedicated scheduling time slot for the new cluster to which it belongs through the time slot allocation map in subsequent beacon frames; The master station continuously monitors the data reported by each regular node. When it is determined that the temperature data change of a certain regular node is lower than the preset slow change threshold in multiple consecutive scheduling cycles, and its node communication stability assessment result is consistently excellent, the master station initiates a scheduling cycle extension strategy for the regular node. The strategy is implemented by adjusting the cluster-level scheduling parameters of its cluster. That is, according to the cycle extension strategy, the length of the cluster-level scheduling cycle of its cluster is gradually increased, and the scheduling time slot density allocated to the corresponding cluster in a macro scheduling cycle is reduced accordingly, thereby reducing the average active time and energy consumption of all regular nodes in the cluster. The updated cluster-level scheduling parameters are also delivered through broadcast beacon frames.

[0015] The beneficial effects of this invention are: This invention clearly defines the contention access period in the superframe structure, adopts a dynamic ALOHA mechanism to realize random access of alarm nodes and newly joined nodes, and introduces a unique frame identification and ACK confirmation mechanism to effectively improve the success rate of emergency temperature information reporting and low-latency response capability. In particular, by using specific identifiers in the broadcast beacon frame to perform multi-cycle key monitoring of alarm nodes, it improves the timeliness processing capability of high temperature warning nodes, overcomes the problem of excessive alarm delay under traditional polling scheduling, and is suitable for power field or high-density deployment environments with limited redundant communication resources.

[0016] This invention proposes a node communication stability assessment mechanism based on historical communication records and temperature change characteristics. It constructs a set of stability levels and executes a differentiated cluster-level scheduling parameter template allocation strategy accordingly. This enables dynamic adaptive adjustment of parameters such as scheduling cycle and time slot density for different clusters. Compared with traditional static clustering methods, this mechanism can sense changes in actual network quality, flexibly adjust resource allocation, improve overall channel utilization, and effectively reduce the energy consumption and communication burden of inactive nodes without sacrificing communication success rate, thereby enhancing network lifetime.

[0017] This invention designs a node self-migration mechanism based on a temperature threshold recovery criterion. This mechanism allows alarmed nodes to proactively initiate state update requests after autonomously determining their state has recovered locally. Upon response from the master station, the alarmed node is reintegrated into the regular cluster and its scheduling slots are reallocated. Simultaneously, by continuously monitoring data change amplitude and stability assessment values, a strategy of gradually extending the scheduling cycle is introduced to progressively reduce the scheduling density of low-variable nodes, forming a regular-stable-energy-saving adaptation loop. This enhances the system's adaptability to environmental fluctuations and network load changes. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only for this invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a schematic diagram of the communication method according to an embodiment of the present invention; Figure 2 This is a schematic diagram of cluster scheduling time period communication and dynamic adjustment in an embodiment of the present invention. Detailed Implementation

[0020] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. For some well-known technologies, those skilled in the art may also use other alternative methods to implement the invention. Moreover, the accompanying drawings are only for more specific description of the embodiments and are not intended to specifically limit the present invention.

[0021] like Figures 1-2 As shown, a collision avoidance communication method for wireless temperature sensors based on dynamic time slot contention and clustered scheduling collaboration includes a master station and multiple wireless temperature sensor nodes. The wireless temperature sensor nodes are divided into regular nodes with normal temperature that report data at fixed intervals and alarm nodes that need to report immediately when the temperature exceeds a threshold. The method includes the following steps: S1, Beacon Frame Broadcast and Node Grouping: The master station broadcasts beacon frames to synchronize time and distribute the time slot allocation diagram of the current superframe. The superframe includes at least a contention access period for communication between alarm nodes and newly joined nodes, and a clustering scheduling period for communication between regular nodes. In a wireless temperature measurement system, multiple temperature sensor nodes wirelessly upload temperature data to the master station (concentrator). To avoid conflicts and improve communication efficiency, a superframe structure is adopted: within a fixed communication cycle, data upload time periods for different types of nodes are uniformly planned, and scheduling information is broadcast via beacon frames. This section describes how the master station sends the current communication cycle's structure and resource allocation plan to all nodes via beacon frames, and how nodes determine when and how to conduct data communication based on this information.

[0022] The main station uses a fixed superframe period. The beacon frame being broadcast includes at least the following information: S11, the start timestamp of the current superframe. This is used for all nodes to synchronize their time with the master station. S12, the structure definition information of the current superframe, including: Starting position of the competitive access period With duration ; The start position of the cluster scheduling period With duration ; S13, Slot allocation diagram within the current superframe ,in, Indicates the first A cluster, , These represent the start and end times of the dedicated scheduling slot for the cluster within the clustering scheduling period; after receiving the beacon frame, the wireless temperature sensor node performs the following operations: Based on timestamp Calibrate the local clock to ensure communication time synchronization; Parse the structure definition information and identify the boundaries of different communication periods in the current superframe; Based on time slot allocation map Find the cluster to which you belong. Then, based on the allocation graph, the scheduling window within the cluster scheduling period is found. Make sure you know when you can send data.

[0023] The parsing process of the structure definition information is as follows: After receiving the beacon frame, the node extracts the structure definition information from it, including the start position and duration of the contention access period and the cluster scheduling period in the current superframe. Using the superframe start time carried in the beacon frame as a time reference point, the node performs relative conversions on the various time parameters in the structure definition to obtain the specific position of each communication period on the local time axis. This allows the node to convert the abstract period definition into an executable time interval and establish a complete time structure framework for the current superframe. After completing the time conversion, the node calculates the start and end boundaries of each communication period sequentially according to the order given in the structure definition. For example, the node first determines the start and end times of the contention access period, and then uses this end time as a reference to continue calculating the start and end positions of the cluster scheduling period, thus forming a continuous and non-overlapping time interval division locally. Through this segment-by-segment parsing and accumulation method, the node can clearly identify the boundaries of different communication periods in the current superframe and determine whether to perform contention access or send data according to the scheduled time slot in different time periods, achieving precise timing control.

[0024] It's important to note that the time slot allocation diagram is essentially a time scheduling table, generated by the master station and broadcast to all nodes via beacon frames. It clearly defines the time periods within the current superframe during which each cluster can send data. Its core function is to further subdivide the cluster scheduling period into several specific communication time windows, mapping these windows one-to-one with different clusters. Each node only needs to look up its own cluster's time interval in the diagram to know when it can send data, thus avoiding conflicts caused by multiple nodes sending simultaneously. The master station schedules in advance, and each cluster communicates sequentially within the designated time.

[0025] When constructing the time slot allocation map, the master station determines how many scheduling time slots can be divided based on the total available time of the cluster scheduling period in the current superframe. Combining the clustering results from the previous step, it calculates the number of nodes, communication frequency requirements, and stability level of each cluster to determine how many time slots each cluster needs to be allocated and how the time slots are distributed. The time slots can be a continuous period of time or distributed across multiple time slices. Then, the master station maps the time slots to each cluster in order of a certain stability level, forming a complete cluster-time interval correspondence table. Finally, the allocation result is encapsulated into a time slot allocation map and written into a beacon frame for broadcast. All nodes then execute their respective timed communication behaviors accordingly.

[0026] S14, based on its own state, the node in the superframe period The internal communication behavior rules are as follows: If the node's current status is an alarm node or a newly joined node, then during the contention access period... The channel is preempted using the dynamic frame slot ALOHA protocol, which randomly selects an idle time slot to attempt transmission. If a conflict occurs, it will retry in the next round to ensure the real-time performance of emergency alarms or the addition of new nodes. If a node is currently a regular node and has already been assigned to a cluster by the master station, then it belongs to its respective cluster. Corresponding scheduling window Internally, timed reporting is performed using TDMA, meaning each cluster has a defined, conflict-free dedicated time window.

[0027] The Dynamic Frame Slotted ALOHA protocol is an access mechanism that divides a fixed-length contention access period into several equal-length communication slots, allowing nodes to send data to randomly select the transmission time within these slots. In this invention, the master station sends the length of the current contention access period and the number of slots it contains in the beacon frame of each superframe. After completing time synchronization, all nodes in the alarm state and newly joined nodes select a slot to send a data frame within the contention access period according to a local random algorithm. Since multiple nodes may choose the same slot to send, resulting in a conflict, this protocol is essentially a probabilistic access mechanism used to achieve fast access without centralized scheduling. The master station continuously monitors the signals in each time slot throughout the entire contention access period and judges the reception results of each time slot: if only one node sends data in a time slot and it can be correctly decoded, the node is judged to have sent successfully, and an acknowledgment message containing the node's identifier is sent via broadcast in the subsequent feedback phase; if multiple nodes send data simultaneously in a time slot, causing signal overlap, or no valid signal is detected, it is judged as a conflict or idle time slot, and the corresponding node needs to randomly select a time slot for retransmission in the contention access period of the subsequent superframe. In order to improve efficiency, the dynamic frame in this invention is reflected in the fact that the master station can dynamically adjust the number of time slots in the contention access period of the next superframe according to the number of alarm nodes in the current network or the historical conflict situation, providing more contention opportunities under high load and reducing idle waste under low load, thereby achieving an adaptive balance between conflict probability and channel utilization.

[0028] S2, Communication and Alarm Node Preemption During Contention Access Period: During the contention period, alarm nodes and newly joined nodes report data using the dynamic frame slot ALOHA protocol. The master station confirms the alarm node and focuses on monitoring it based on whether it receives the alarm reporting frame, and removes the alarm node that has completed the alarm reporting from the cluster scheduling queue. In this invention, ACK represents an acknowledgment. In wireless communication, an ACK frame is a short data packet, typically sent by the receiver; in this invention, it is sent by the master station after successfully receiving data from a node.

[0029] In this invention, when the master station successfully receives a node's unique valid frame within a contention time slot, it broadcasts an ACK confirmation frame during the subsequent feedback period. The ACK confirmation frame contains the node's identifier ID. Upon receiving the ACK, all nodes will determine whether their own ID is present in the confirmation. If so, the transmission was successful; otherwise, it may have failed or the node may not have sent anything in this round. The ACK is the only way for a node to determine its success; without an ACK, a node will not know whether retransmission is necessary.

[0030] S21. In a wireless temperature measurement system, a large number of wireless temperature sensor nodes need to upload data to the main station. These nodes may experience emergencies (temperature exceeding limits) or new devices joining the network at any time, requiring immediate communication with the main station. To ensure a rapid response to these sudden reports, a time window for contention-based access is designed, specifically reserved for two types of nodes: Alarm point: If the measured temperature exceeds the threshold, it needs to be reported immediately; New nodes joining the network: These nodes have not yet joined the scheduling system and require an initial communication request.

[0031] This competitive access period is divided into multiple equal-length hourly slots, and all alarm / new nodes must queue up to compete for one of the hourly slots to complete communication.

[0032] Specifically, at the beginning of each superframe, the master station broadcasts a beacon frame containing the time information and structure description of the current frame. Alarm nodes and newly joined nodes, upon receiving the beacon frame, use the timestamp contained within it to... Starting position of competing access time Synchronize the local clock and identify the competing windows within the competing access period. This window is created by It consists of several time slots of equal length, denoted as: Each time slot The duration is .

[0033] S22, within the contention window, the alarm node and the newly joined node randomly select an unoccupied time slot based on the locally synchronized system timing. Send data frames. ,in: Alarm nodes send alarm reporting frames It carries its own node identifier and temperature exceeding the threshold information; Newly joined nodes send network access request frames. It is used to request the master station to allocate node identifiers and initialization information, and carries its own hardware information, identity code and other content.

[0034] It is important to note that all nodes decide which time slot to use locally; the master station does not tell which node should send the message in advance, and the nodes must make their own judgments.

[0035] S23, the main station throughout the entire competitive window Continuous internal monitoring, and monitoring of each time slot. The receiving status is determined by the following logic: If in a certain time slot If a unique data frame is successfully received and decoded within the time slot, the contention for that time slot is considered successful, denoted as: The master station will broadcast an ACK confirmation frame during the feedback period set in the subsequent frame structure. ,in This serves as the identifier for the successful node; a unique data frame refers to a data frame that was sent by only one node within a certain contention time slot, and which was successfully received and correctly decoded by the master station. If no data frame is detected in a certain time slot, or if decoding failure is detected due to a collision (such as simultaneous transmission by multiple nodes, resulting in signal superposition interference), then the contention for that time slot is determined to have failed. .

[0036] S24, the master station will broadcast a confirmation message with the node ID to all nodes during a dedicated feedback period after the contention access, indicating successful reporting. For alarm nodes that have successfully competed and completed reporting, the master station will perform the following two processes after confirmation: Key monitoring: During the subsequent M superframe periods, the master station continuously carries the identification information of the alarm node in its broadcast beacon frames. This indicates that the node is a critical node in an alarm state, which facilitates subsequent tracking and dynamic intervention by the system or backend. Temporary scheduling removal: The master station removes the node's identifier from the regular node scheduling queue of its cluster, so that it no longer occupies the dedicated scheduling slot during the cluster scheduling period when it is in alarm state, thus avoiding resource waste and duplicate reporting.

[0037] S3, Clustered Scheduling Period Communication and Dynamic Adjustment: Based on the historical communication records and frequency of regular nodes, the master station divides regular nodes into multiple clusters and allocates dedicated scheduling slots to each cluster during the cluster scheduling period, guiding each cluster node to complete data reporting within its assigned slot. The master station dynamically adjusts the length ratio of the contention access period and the cluster scheduling period within a superframe based on the proportion of alarm nodes. During the cluster division process, the master station also constructs corresponding node communication stability assessment results based on the temperature change amplitude, temperature change trend stability, and historical reporting success rate of each regular node over multiple consecutive superframe cycles. Based on the node communication stability assessment results, the master station sets differentiated cluster-level scheduling parameters for different clusters. These parameters include at least the cluster-level scheduling cycle length, cluster-level slot allocation density, or cluster-level scheduling priority. This allows clusters with high communication stability to use low-frequency or extended-cycle scheduling methods, while clusters with low communication stability use high-frequency or compact-slot scheduling methods. Updated cluster-level scheduling parameters are then distributed via subsequent beacon frames.

[0038] S31, Node Clustering: The goal is for the main station to rationally group all regular nodes according to their communication behavior characteristics, i.e., cluster them, to facilitate the subsequent allocation of dedicated scheduling slots to each cluster. Since different nodes may have different data reporting habits, communication stability, and data volume, unified scheduling without grouping can lead to wasted slots or frequent conflicts. Therefore, a feature-driven clustering method is needed.

[0039] Within each superframe period, the master station performs clustering processing on each regular node based on its historical communication behavior characteristics. The details are as follows: S311. Main site statistics for each regular node. in the past The following communication characteristics are present within the time window: Average data reporting interval: This is the average time between two successful data reports from a node within the statistical period. The purpose is to understand the communication frequency of the nodes. More frequent reporting and shorter intervals help group nodes with similar reporting periods together. It is expressed as: ;in, For nodes No. The timestamp of the first successful report. For nodes No. The timestamp of the first successful report. This indicates the number of times a node successfully reported data within the statistical period; Historical communication success rate: This refers to the percentage of times a node successfully reports when scheduled for communication. If a node consistently fails to report, it indicates poor communication quality. Nodes with similar communication stability can be grouped together and share a scheduling strategy, as shown below: ;in, Represents a node Number of successful reports This indicates the total number of times the system has attempted to report the data. Average packet size (bytes): The size of each data upload may vary. This value measures the average amount of data sent by the node. Nodes with similar data volumes can have their time slot lengths allocated uniformly during scheduling, facilitating time-domain resource optimization. It is represented as: ;in, For the first The length of data reported each time.

[0040] S312. After the main station performs feature normalization processing on all regular nodes, it executes a clustering algorithm based on the above features to divide nodes with similar communication characteristics and similar reporting cycles into multiple clusters. .

[0041] The process of executing a clustering algorithm is as follows: The main station extracts three statistical features for each regular node: average reporting interval, success rate, and data packet size, and performs normalization processing. The main station selects standard clustering methods such as K-means (fixed number of clusters) or hierarchical clustering (automatic hierarchical merging).

[0042] For all nodes, calculate the Euclidean distance between each pair to measure the similarity of their communication behaviors.

[0043] Node clustering: Grouping nodes that are close to each other into the same cluster to form a cluster set. The main station assigns a unique number to each cluster for subsequent scheduling, distribution, and feedback.

[0044] S32, Cluster scheduling time slot allocation: After completing node clustering, the master station already knows which regular nodes belong to which cluster. Then, it needs to arrange the communication time window, i.e., time slot, for these clusters during the clustering scheduling period. Since the length of a superframe is limited, and the number of clusters and the number of nodes in each cluster may be different, the master station must make reasonable allocations according to the system resource situation to avoid conflicts, congestion, or idle waste.

[0045] Specifically, after completing the cluster partitioning, the main station determines the current superframe length based on the data. Cluster scheduling period duration and the number of nodes in each cluster , for each cluster Allocate corresponding time slot blocks. Each cluster is allocated one or more consecutive or non-consecutive logical time slot segments: ;in, For clusters The number of time slots allocated. These time slots may be continuous, for example, a cluster may be allocated the time slot from 10:00 to 10:10; or they may be non-continuous, for example, a cluster may use 10:00 to 10:05 first, and then 10:30 to 10:35, making scheduling more flexible and adaptable to situations such as uneven distribution of the number of nodes and fluctuations in network load.

[0046] The main station aggregates the time slot mapping results of all clusters into a time slot allocation diagram: This information is broadcast via beacon frames sent to all nodes, letting them know: The cluster number to which you belong; The specific time period during which this cluster can be used in the current superframe; This allows it to decide when to wake up and send data.

[0047] S33, Dynamic adjustment of contention access and cluster scheduling time period length: When the number of alarm nodes increases, it means more nodes need to immediately report temperature exceeding limits, requiring more contention channel resources to be freed up; otherwise, latency will increase, affecting safety response. Conversely, if a large number of contention slots are still reserved for alarm nodes when the number decreases, resources will be wasted because those slots may be unused while regular nodes are queued, reducing system throughput. Therefore, the ratio of contention access periods to clustering scheduling periods cannot be fixed; it must be dynamically adjusted according to changes in network conditions. The goal is to adjust the ratio of contention access periods to clustering scheduling periods in real time based on the proportion of nodes currently in an alarm state, dynamically balancing alarm response priority and regular data transmission efficiency within a limited total superframe duration. Internally, it is a dynamic regulation strategy for the redistribution of resources.

[0048] The main station counts the number of nodes currently in an alarm state in the network. The total number of nodes is The proportion of alarm nodes for: The main site uses a preset mapping function. Length of competing access periods With cluster scheduling time period length Perform dynamic adjustments to satisfy: ; when When the proportion of alarm nodes increases, that is, when the proportion of alarm nodes increases, To ensure emergency alarm response; when When the bandwidth is reduced, the reverse adjustment is made to improve the total bandwidth utilization reported by regular nodes.

[0049] Choose a linear piecewise mapping function: ; in, To minimize the contention access period, even when the load is very low and there are almost no alarm nodes, the basic alarm access channel still needs to be maintained. Typically, one ALOHA contention time slot can accommodate one node sending one frame. At least 1 to 2 nodes must be supported to successfully report. It can be set to 10 time slots to accommodate occasional alarms under light load conditions and new nodes joining the network, while avoiding excessive resource idle time. To determine the maximum length of the competitive access period, in the case of dense alarm nodes, it is necessary to quickly respond to the simultaneous reporting requests of multiple nodes. ALOHA is a probabilistic access method, and the conflict rate increases significantly with the number of nodes. Therefore, it is necessary to increase the number of available time slots to dilute the conflict probability. It can be set to 50 time slots, which can support a relatively high success rate of competition in a single round for approximately 15 to 25 nodes. The threshold for indicating a low alarm rate is set at 5%. Under normal operating conditions, the number of alarm nodes is generally very small. Empirically, when the alarm node rate is less than 5%, it is considered that the communication urgency is low, and the contention for resources can be kept to a minimum. This threshold serves as the lower limit trigger point to maintain the efficiency of communication resources under low load. The threshold for a high alarm rate is set at 30%. When the alarm node ratio exceeds 30%, it indicates that there may be a concentrated anomaly, fault propagation, or concentrated exposure of equipment aging. In this scenario, it is necessary to significantly increase the proportion of alarm channel resources to ensure low-latency response. This threshold is set as the upper limit of the adjustment function. Above this value, the competition period will not be expanded further to prevent the squeezing and loss of control of regular scheduling. The slope is a linear growth rate, used in... and Smooth growth between the two.

[0050] S34, Node Communication Stability Assessment Value Calculation: The master station calculates a comprehensive communication stability assessment value by analyzing the temperature data change trend and historical communication performance of each regular node. This value is used to guide the hierarchical and differentiated configuration of subsequent cluster scheduling strategies. Nodes with higher communication stability usually indicate that their temperature is relatively stable, their behavior is regular, and their communication is relatively reliable. Nodes with low stability are more likely to experience frequent changes and large communication fluctuations, and should be given more frequent and higher priority scheduling support.

[0051] Specifically, the main station continuously... Temperature data collected within one superframe period Calculate the communication stability assessment value according to the following indicators. : S341. Variance of temperature variation (first factor): The smaller this index, the more stable the node temperature change; the larger it is, the more unstable the temperature. Represents a node In the Temperature values ​​reported in each cycle, Represents a node The average value of the temperature series; S342. Stability of Temperature Change Trend (Second Factor): Temperature itself may exhibit a trend, such as gradually increasing or decreasing. Therefore, the main station performs a linear regression on the temperature series. ;in, For regression coefficients, For the deviation at each point, take the standard deviation of the residuals: This indicator reflects the predictability of temperature trends; the smaller the value, the more stable the trend, while the larger the value, the more chaotic or unclear the trend. S343. Historical Scheduling Success Rate (Third Factor): ; After normalizing the three factors and combining them by weight, the communication stability assessment value is: ;in, It is the normalized result of the temperature variance. This is the normalized result of the standard deviation of the regression residuals. The normalized result of the success rate, For adjustable weighting coefficients, satisfying . The larger the value, the more unstable the node is. In the subsequent cluster-level scheduling strategy, the master station will arrange nodes with low stability into higher frequency and higher priority scheduling clusters to ensure timely data upload, while nodes with high stability can have their scheduling cycle extended or their scheduling density reduced to achieve energy saving and resource balance.

[0052] S35, Differentiated cluster-level scheduling parameter allocation: The master station assigns scheduling parameters to each cluster. Communication stability assessment value of all nodes The average value is defined as the cluster-level stability: ;According to their Divided into three preset stability level sets L1 = [0.0, 0.3) represents a highly stable cluster, with smaller values ​​indicating greater stability; L2 = [0.3, 0.7) represents a moderately stable cluster; L3 = [0.7, 1.0] represents a low-stability cluster; all clusters are classified according to their stability. The value can be directly mapped to a certain range.

[0053] And configure corresponding scheduling parameter templates for each level. ,include: Cluster-level scheduling cycle ; Time slot allocation density ; Scheduling priority .

[0054] The specific matching logic is as follows: like (High stability): Long period, low time slot density, low priority; like (Low stability): short period, high time slot density, high priority.

[0055] L2 is the default scheduling level and requires no special intervention. Clusters at the L2 level are in an intermediate state that is neither very stable nor very unstable. Therefore, there is no need to adjust scheduling parameters such as period and priority. The system's default scheduling strategy can be used.

[0056] The final cluster-level scheduling parameters will be distributed through beacon frames in the next one or more cycles, so that each node in the cluster follows the communication strategy corresponding to its level in subsequent scheduling.

[0057] Cluster-level scheduling parameter templates are a set of communication scheduling control parameter configuration combinations preset by the master station for clusters with different stability levels. Each template defines the scheduling behavior characteristics of the cluster at that level, including the following key parameters: 1. Scheduling cycle length: This refers to the time interval within which the master station repeatedly allocates a reporting opportunity to this cluster. The shorter the cycle, the higher the scheduling frequency.

[0058] Stable cluster (L1): The scheduling period can be set to a relatively long 10 superframe cycles; Unstable cluster (L3): The scheduling cycle is short, 2 to 3 superframe cycles, which facilitates timely collection of fluctuation data.

[0059] 2. Scheduling slot allocation density: refers to the number or proportion of slots allocated to the cluster in each scheduling cycle, reflecting the strength of bandwidth resource allocation.

[0060] L1: Can be allocated fewer time slots, for example, only 1 to 2 consecutive or intermittent time slots per cycle; L3: More time slots can be allocated, for example, 3 to 5 consecutive time slots per cycle, or a higher proportion of the scheduling window can be occupied.

[0061] 3. Scheduling priority: refers to the order in which the master station processes each cluster when there are scheduling conflicts or insufficient resources.

[0062] L3 clusters are set to high priority; L1 clusters are set to low priority; L2 clusters can be used as a neutral level, using the default priority.

[0063] 4. Retransmission Redundancy Configuration: For clusters with unstable communication, repeated transmission opportunities can be added to the scheduling template to improve the data success rate.

[0064] The L3 template can be set to automatically allow one resend; The L1 template can disable redundancy mechanisms to reduce energy consumption.

[0065] The template creation process can be divided into the following steps: Step 1: Define the cluster level classification: The master station first classifies each cluster into the corresponding level set (L1, L2, L3) based on the communication stability of each cluster.

[0066] Step 2: Predefine parameter combination templates for each level: Based on the communication resources, sensor data value, power consumption requirements, etc. of the actual deployment scenario, set the scheduling strategy template corresponding to each level offline. Each template should include at least: the corresponding scheduling cycle length, the corresponding time slot density, the corresponding priority level, and whether to enable the retransmission mechanism and its configuration.

[0067] Step 3: During operation, the master station dynamically binds the corresponding parameter template to the cluster based on the cluster's current level, and sends the updated time slot allocation map and related control information in the beacon frame. The template can also be dynamically optimized as the system operates.

[0068] S4, State transition and scheduling cycle optimization: After the alarm is cleared, the alarm node automatically migrates to a regular node and re-participates in cluster partitioning and cluster scheduling. For regular nodes with slow changes in communication data, the master station extends their scheduling cycle to reduce time slot occupation and energy consumption.

[0069] S41, Alarm Clearance State Transition: During operation, when a node enters an alarm node state due to temperature rise, its temperature change needs to be continuously evaluated. Once the node's temperature value remains below the safe threshold for several consecutive sampling periods, its abnormal state can be determined to have been cleared.

[0070] In other words, the alarm node triggers a state transition after the following conditions are met: In continuous Within each sampling period, its temperature value satisfy: ; This indicates the alarm temperature threshold. The value range depends on the actual material or equipment safety temperature limit of the object being monitored by the sensor. For common power or industrial temperature monitoring equipment, a range of [55°C, 70°C] is recommended. Represents a node At any moment Temperature value, This indicates the number of consecutive normal cycles required for alarm clearance, used to avoid false alarms; the formula indicates that the node has consecutive normal cycles. State transition can only be triggered if the temperature value in each sampling period is less than the safety threshold.

[0071] During the contention access period of the next superframe, the node sends a status update frame: ; Represents a node Update the state frame content. This indicates that the status has changed from alarm to normal. This is the currently sampled temperature value, used for verification by the main station. After receiving and parsing the status update frame, the master station updates the node status label to a regular node and re-includes it in the management queue.

[0072] S42, the master station re-classifies the cluster for this node based on the following data: the node's historical average reporting interval. Variance of current temperature change and the latest communication stability assessment values The historical average reporting interval represents the average data reporting frequency of this node over a period of time. A high frequency indicates a key monitoring focus or significant status fluctuations. The current temperature variation variance represents the severity of temperature changes at this node in recent scheduling cycles. A large variance indicates significant temperature fluctuations, suggesting it still has some monitoring value. The latest communication stability assessment value measures the communication quality of the node in the current topology environment, including signal-to-noise ratio factors. Nodes with high stability can be scheduled more sparsely without affecting data integrity. The main station uses these three indicators as feature vector inputs to execute a clustering algorithm to assign the node to the most suitable cluster. The clustering partitioning is represented as follows: ;in, For the first A cluster, Let Dist be the cluster center feature vector, and Dist be the Euclidean distance function. The average reporting interval for nodes. This represents the variance of the node temperature variation. This is the evaluation value for node communication stability; the formula represents: [The value is missing from the original text]. Each node is assigned to the cluster whose behavioral characteristics are most similar to its own. To minimize the distance between it and the cluster center feature vector.

[0073] Then, scheduling time slots are allocated within the new cluster: the master station allocates time slots for nodes based on the time slot allocation map of the cluster in the current superframe. Allocate logical time slots .

[0074] S43, within each macro-scheduling cycle, the master station evaluates whether all regular nodes meet the condition of slow communication change. The master station determines the condition of slow communication change as: a certain regular node... In recent During each scheduling cycle, the temperature change amplitude satisfies: And its stability assessment value: . This represents a slowly changing threshold, ranging from 0.5℃ to 1.0℃. Based on the quantization accuracy and thermal inertia of the temperature sensor, a value below this range is considered a stable change. The threshold for determining stability is 0.85 (after normalization). Based on the distribution statistics of historical communication stability, nodes with a stability of over 90% are defined as having excellent communication.

[0075] The main station will then implement a scheduling cycle extension strategy accordingly: The cluster to which this regular node belongs Cluster-level scheduling cycle Adjusted to: ; This indicates the increment of the scheduling cycle, ranging from 10s to 30s. Extending the scheduling cycle means that the reporting frequency of all nodes in the cluster decreases, thereby reducing the number of wireless transmissions.

[0076] Simultaneously, the corresponding scheduling time slot density Reduced to: ; This represents a reduction in scheduling density, 1 to 2 time slots per macrocycle. This further compresses the channel resources occupied by the cluster and improves the overall system capacity.

[0077] Updated scheduling parameters The beacon frame is broadcast to all regular nodes within the cluster.

[0078] This invention encompasses any substitutions, modifications, equivalent methods, and solutions made within the spirit and scope of this invention. To provide the public with a thorough understanding of this invention, specific details are described in detail in the following preferred embodiments; however, those skilled in the art will fully understand the invention even without these details. Furthermore, to avoid unnecessary misunderstanding of the essence of this invention, well-known methods, processes, procedures, components, and circuits are not described in detail.

[0079] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A collision avoidance communication method for wireless temperature sensors based on dynamic time slot contention and cluster scheduling coordination, characterized in that, The method includes a master station and multiple wireless temperature sensor nodes, which are divided into regular nodes that report data at fixed intervals and nodes that report data immediately when the temperature exceeds a threshold. The method includes the following steps: S1, the master station broadcasts a beacon frame, used to synchronize time and send the time slot allocation diagram of the current superframe. The superframe includes at least a contention access period for communication between alarm nodes and newly joined nodes, and a clustering scheduling period for communication between regular nodes. S2, the alarm node and the newly joined node report data using the dynamic frame slot ALOHA protocol during the contention access period. The master station performs ACK confirmation and key monitoring on the alarm node based on whether it receives the alarm reporting frame, and removes the alarm node that has completed the alarm reporting from the cluster scheduling queue. S3, the master station divides the regular nodes into multiple clusters based on the historical communication records and communication frequency of the regular nodes, and allocates a dedicated scheduling time slot for each cluster during the cluster scheduling period, guiding each cluster node to complete data reporting within its assigned time slot; wherein, the master station dynamically adjusts the length ratio of the contention access period and the cluster scheduling period in the superframe based on the proportion of alarm nodes. S4, after the alarm is cleared, the alarm node automatically migrates to a regular node and re-participates in cluster partitioning and cluster scheduling; for regular nodes with slow communication data changes, the master station extends their scheduling cycle to reduce time slot occupation and energy consumption.

2. The anti-collision communication method for wireless temperature sensors based on dynamic time slot contention and cluster scheduling coordination as described in claim 1, characterized in that, The master station broadcasts the beacon frame at a fixed period, and the beacon frame includes at least: The start timestamp of the current superframe is used for all nodes to synchronize their time with the master station; The current superframe structure definition includes the start position and length of the contention access period and the start position and length of the cluster scheduling period; The current superframe time slot allocation diagram specifically defines the start and end times of the dedicated scheduling time slots allocated to each cluster during the cluster scheduling period.

3. The anti-collision communication method for wireless temperature sensors based on dynamic time slot contention and cluster scheduling coordination as described in claim 2, characterized in that, After receiving the beacon frame, all nodes calibrate their local clocks according to the start timestamp and determine their communication behavior in subsequent time periods based on the structure definition and time slot allocation diagram. Specifically, alarm nodes and newly joined nodes compete for access according to the protocol during the contention access period, while regular nodes report when their dedicated scheduling time slot for their own cluster arrives during the cluster scheduling period.

4. The anti-collision communication method for wireless temperature sensors based on dynamic time slot contention and cluster scheduling coordination as described in claim 1, characterized in that, In S2, during the contention access period, the alarm node and the new network node, based on the timing of the beacon frame synchronization, randomly select one time slot within a contention window consisting of multiple equal-length time slots to send a data frame; wherein, the alarm node sends an alarm reporting frame including temperature exceeding the threshold information, and the new network node sends a network access request frame. The master station monitors each time slot within the contention window and determines the reception status of each time slot: if a unique data frame is correctly received and decoded in a certain time slot, the time slot contention is determined to be successful, and the master station then broadcasts confirmation information including a successful node identifier in the subsequent feedback period; if no signal is detected in a certain time slot or decoding failure caused by a collision is detected, the time slot contention is determined to be unsuccessful.

5. The anti-collision communication method for wireless temperature sensors based on dynamic time slot contention and cluster scheduling coordination according to claim 4, characterized in that, In S2, for alarm nodes that have successfully reported, in addition to sending ACK confirmation, the master station will also conduct key monitoring of them by carrying a specific identifier in the beacon frames they broadcast in the subsequent superframe cycles. At the same time, the main station will temporarily remove the identifier of the alarm node that was successfully reported from its regular node cluster scheduling queue, so that it will no longer occupy the dedicated scheduling time slot of the cluster scheduling period during the duration of the alarm status.

6. The anti-collision communication method for wireless temperature sensors based on dynamic time slot contention and cluster scheduling coordination according to claim 1, characterized in that, In S3: The clustering of regular nodes specifically includes: the main station statistically analyzes the average data reporting interval, historical communication success rate and data packet size of each regular node in the past preset period, and clusters nodes with similar reporting intervals and similar communication characteristics into the same cluster; The allocation of scheduling time slots specifically includes: calculating and allocating one or more continuous or non-contiguous logical time slot blocks for each cluster based on the length of the current superframe, the available duration of the cluster scheduling period, and the number of nodes included in each cluster, and notifying all nodes through the time slot allocation diagram in the beacon frame.

7. The anti-collision communication method for wireless temperature sensors based on dynamic time slot contention and cluster scheduling coordination as described in claim 6, characterized in that, The dynamic adjustment of the length ratio of the contention access period to the cluster scheduling period in the superframe specifically includes: The main station calculates the ratio of the total number of nodes in alarm state to the total number of nodes in the network as the alarm ratio. According to the preset mapping relationship, when the alarm ratio increases, the length of the contention access period in the current and several subsequent superframes is increased, and the length of the cluster scheduling period is reduced accordingly to ensure the timeliness of alarm reporting. When the alarm ratio decreases, the adjustment is reversed.

8. The anti-collision communication method for wireless temperature sensors based on dynamic time slot contention and cluster scheduling coordination according to claim 1, characterized in that, During the process of clustering regular nodes by the main station, the corresponding node communication stability evaluation results are also constructed based on the temperature change amplitude, temperature change trend stability and historical reporting success rate of each regular node in multiple consecutive superframe cycles. The construction of the node communication stability evaluation result includes: the master station records the temperature values ​​reported by each regular node in multiple consecutive superframe periods, and calculates the variance of its temperature change amplitude as the first evaluation factor; the temperature change trend is analyzed by linear regression, and the standard deviation of the regression residual is used as the second evaluation factor for trend stability; the number of successful reports by the node in multiple historical scheduling reports is counted, and the reporting success rate is calculated as the third evaluation factor; the first evaluation factor, the second evaluation factor, and the third evaluation factor are weighted and summed to obtain the node communication stability evaluation value; Based on the node communication stability assessment results, the master station sets differentiated cluster-level scheduling parameters for different clusters. The cluster-level scheduling parameters include at least the cluster-level scheduling cycle length, cluster-level time slot allocation density, or cluster-level scheduling priority. This allows clusters with high communication stability to use low-frequency or extended-cycle scheduling methods, while clusters with low communication stability use high-frequency or compact time slot scheduling methods. The updated cluster-level scheduling parameters are then sent out via subsequent beacon frames.

9. The anti-collision communication method for wireless temperature sensors based on dynamic time slot contention and cluster scheduling coordination as described in claim 8, characterized in that, The master station sets differentiated cluster-level scheduling parameters for different clusters based on the node communication stability assessment results. Specifically, this includes: the master station calculating the average communication stability assessment value of all nodes in each cluster as the cluster-level stability; pre-setting at least three stability levels and corresponding scheduling parameter templates for the master station; classifying each cluster into different levels according to its cluster-level stability and applying the corresponding level's scheduling parameter template to the cluster. For clusters with high cluster-level stability, the applied template is configured with a longer cluster-level scheduling cycle and / or a lower cluster-level time slot allocation density; for clusters with low cluster-level stability, the applied template is configured with a shorter cluster-level scheduling cycle and / or a higher cluster-level time slot allocation density, and its cluster-level scheduling priority is set to higher; the updated cluster-level scheduling parameters are distributed to all nodes in the corresponding cluster through the beacon frames broadcast in the next one or several cycles.

10. The anti-collision communication method for wireless temperature sensors based on dynamic time slot contention and cluster scheduling coordination according to claim 8, characterized in that, The automatic migration to a regular node specifically includes: when a node detects that its temperature value has recovered to below the alarm temperature threshold for several consecutive sampling periods, it determines that the alarm has been cleared, and in the next contention access period, it sends a status update frame containing its identifier and status migration declaration to the master station; after receiving the status update frame, the master station confirms that its alarm status has been cleared, updates its status mark to a regular node, and re-includes it in the management queue of regular nodes; based on the regular node's past communication records, current temperature change characteristics, and the latest node communication stability assessment results, the master station reassigns it to a matching cluster, and allocates a dedicated scheduling time slot for the new cluster to which it belongs through the time slot allocation map in subsequent beacon frames; The master station continuously monitors the data reported by each regular node. When it is determined that the temperature data change of a certain regular node is lower than the preset slow change threshold in multiple consecutive scheduling cycles, and its node communication stability assessment result is consistently excellent, the master station initiates a scheduling cycle extension strategy for the regular node. The strategy is implemented by adjusting the cluster-level scheduling parameters of its cluster. That is, according to the cycle extension strategy, the length of the cluster-level scheduling cycle of its cluster is gradually increased, and the scheduling time slot density allocated to the corresponding cluster in a macro scheduling cycle is reduced accordingly, thereby reducing the average active time and energy consumption of all regular nodes in the cluster. The updated cluster-level scheduling parameters are also delivered through broadcast beacon frames.

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