An emergency lighting wireless system concurrent power-on logic sequencing networking method

Abstract

The application relates to an emergency lighting wireless system concurrent power-on logic sequencing networking method, which comprises the following steps: under the triggering condition of monitoring the main power failure and switching to the backup battery power supply, all emergency lighting nodes are concurrently started and preset floor numbers and network roles are read; a logical delay time is calculated according to the floor numbers and the network roles, the time being a silent waiting duration of the nodes before executing a networking action; the nodes remain in a silent receiving state in the logical delay time period, and after the delay time ends, a network networking action corresponding to the role is executed. The application converts the physical concurrent power-on into the ordered access on the time axis, effectively avoids channel congestion and signal collision, and guarantees the rapidity and reliability of network construction in an emergency scene.

Description

Technical Field

[0001] This application relates to the field of fire safety, and in particular to a method for concurrent power-on logic sequencing networking of an emergency lighting wireless system. Background Technology

[0002] With the continuous advancement of smart city and intelligent building technologies, fire emergency lighting systems inside large public buildings are gradually evolving towards digitalization and networking. These systems typically deploy a large number of emergency lighting nodes, interconnected through wireless ad hoc network technology to ensure unified dispatch in emergencies. Under steady-state conditions such as routine inspections or single-point maintenance, existing wireless network protocols can effectively guarantee uninterrupted communication links.

[0003] However, emergency lighting systems have a significant unique characteristic: when the main power supply fails and switches to backup battery power, all nodes within the system exhibit a collective, concurrent startup. Since power switching is a physical event that occurs synchronously across the entire system, hundreds or even thousands of nodes distributed throughout the building will initialize at almost the same time and simultaneously send network access requests to the wireless channel.

[0004] This concentrated surge in communication demand can saturate wireless spectrum resources instantaneously. Although common wireless communication standards generally employ collision avoidance mechanisms based on random backoff, attempting to alleviate congestion by having nodes wait a random period after a collision before retrying, the intensity of channel contention often exceeds the processing capacity of random backoff algorithms in high-density concurrent power-on scenarios. A large number of nodes competing for limited communication resources within the same narrow time window significantly increases the probability of signal collisions. Frequent collisions and retransmissions not only consume the limited battery power of nodes but also drastically extend network initialization time; some nodes may even fail to join the network in time due to multiple failed attempts. Summary of the Invention

[0005] In order to transform simultaneous physical startup into logically ordered access without increasing hardware costs, thereby ensuring the rapid construction and stable operation of emergency communication networks, this application provides a method for logically ordered networking of concurrent power-on of an emergency lighting wireless system.

[0006] This application provides a concurrent power-on logic-sequential networking method for an emergency lighting wireless system, which adopts the following technical solution:

[0007] A method for concurrent power-on logically sequenced networking of an emergency lighting wireless system includes the following steps:

[0008] S1. Under the trigger condition of detecting a main power failure and switching to backup battery power, all emergency lighting nodes in the emergency lighting wireless system start up concurrently and complete the initialization self-test process of the emergency lighting nodes.

[0009] S2. The emergency lighting node reads inherent attribute parameters pre-configured in the internal memory of the emergency lighting node, wherein the inherent attribute parameters include the floor number of the emergency lighting node and the network role of the emergency lighting node;

[0010] S3. The emergency lighting node calculates its own logical delay time based on the floor number and the network role using a preset logical sequencing algorithm, wherein the logical delay time is the silent waiting time before performing network networking actions;

[0011] S4. The emergency lighting node maintains a silent wireless reception state during each time period of the logical delay time, and at the end of the logical delay time, the emergency lighting node is triggered to perform a network networking action corresponding to the network role. The network networking action includes a network establishment action initiated by the network coordinator or a network access request action initiated by a non-coordinator node, thereby realizing the orderly access of all emergency lighting nodes on the time axis.

[0012] Optionally, step S3 includes the following sub-steps:

[0013] S31. The emergency lighting node calls the random number generator of the emergency lighting node to generate a non-negative random disturbance time value within a preset time window, which is used to eliminate the temporal overlap between emergency lighting nodes with the same floor number and the same network role.

[0014] S32. The emergency lighting node performs a weighted superposition operation, linearly superimposing the preset system base delay, various spatial domain delay components that are positively correlated with the floor number, the functional domain delay components corresponding to the network role, and the random disturbance time value, thereby calculating the logical delay time. The spatial domain delay components are used to achieve time separation of nodes on different floors, and the functional domain delay components are used to achieve time separation of nodes with different roles on the same floor.

[0015] Optionally, the logic for determining the functional domain delay component of the network role in S32 is as follows:

[0016] When the network role of the emergency lighting node is a network coordinator, the emergency lighting node is given the highest time priority with the corresponding minimum functional domain delay component; when the network role is a routing node, the emergency lighting node is given a secondary time priority with the corresponding medium functional domain delay component; when the network role is an end-user device, the emergency lighting node is given the lowest time priority with the corresponding maximum functional domain delay component, thereby ensuring that the network coordinator and the routing node complete the network formation before the end-user device.

[0017] Optionally, S4 includes the following sub-steps:

[0018] S41. The emergency lighting node starts an internal timer with a duration equal to the logical delay time, and immediately locks the wireless transmission module of the emergency lighting node, so that the wireless transmission module is in a state of prohibiting the transmission of signals, and at the same time, the wireless receiving module of the emergency lighting node is turned on to enter a continuous listening state.

[0019] S42. During the operation of the internal timer, if the wireless receiving module receives at least one network beacon frame broadcast from a network-connected node in the emergency lighting wireless system, the emergency lighting node parses the network beacon frame to extract network synchronization information and stores the network synchronization information in the cache of the emergency lighting node; wherein, the network beacon frame is a link layer management frame periodically broadcast by the network-connected node, and the data structure of the network beacon frame includes at least a personal area network identifier for uniquely identifying the emergency lighting wireless system, a status flag indicating that the current network allows new nodes to access, and time synchronization parameters for achieving time slot alignment;

[0020] S43. When the count value of the internal timer reaches the logical delay time, the emergency lighting node unlocks the wireless transmission module and controls the wireless transmission module to send a network access request according to the network synchronization information.

[0021] Optionally, the calculation logic for the spatial domain delay component of the floor number in S32 includes the following sub-steps:

[0022] S321. The emergency lighting node obtains a preset floor delay step coefficient, wherein the floor delay step coefficient defines the minimum time protection interval between adjacent floors;

[0023] S322. The emergency lighting node uses a multiplication operation to multiply the floor number by the floor delay step coefficient to generate the spatial domain delay component, thereby establishing a logical access timing wavefront that increases layer by layer from the bottom to the top in the emergency lighting wireless system, preventing cross-floor channel contention between emergency lighting nodes on adjacent floors.

[0024] Optionally, S42 includes the following sub-steps:

[0025] S421. The emergency lighting node monitors and calculates the signal strength indication value of the received network beacon frames in real time;

[0026] S422. The emergency lighting node compares the signal strength indication value with a preset signal strength threshold, and determines that the network beacon frame is a valid beacon only when the signal strength indication value is greater than the signal strength threshold;

[0027] S423. The emergency lighting node selects the optimal network beacon frame with the largest signal strength indication value from all network beacon frames that are determined to be valid, and extracts the network synchronization information from the optimal network beacon frame, thereby locking the parent node with the best network link quality as the access target.

[0028] Optionally, S43 includes the following sub-steps:

[0029] S431. When the count value of the internal timer reaches the logical delay time, the emergency lighting node starts the physical channel idle detection mechanism to listen to the signal energy value of the current wireless channel;

[0030] S432. The emergency lighting node determines whether the signal energy value is lower than the preset channel busy threshold. If the determination result is yes, it confirms that the current channel is idle and immediately controls the wireless transmission module to send the network access request.

[0031] S433. If the determination result is negative, the emergency lighting node confirms that the current channel is busy and suspends the transmission action, enters a microsecond-level contention backoff process, and continues to perform the transmission operation of the network access request after the channel is detected to be idle again, thereby eliminating residual signal collisions.

[0032] In summary, this application includes at least one of the following beneficial technical effects:

[0033] 1. This application introduces a logical sequencing algorithm based on the inherent attributes of nodes to transform the physical concurrent power-up behavior of all nodes in an emergency scenario into discrete ordered actions on the time axis. This mechanism effectively eliminates the congestion caused by a large number of nodes simultaneously competing for the wireless channel, significantly reduces the probability of signal collisions, and thus ensures the rapid construction and stable operation of the network after power switching;

[0034] 2. This application employs a multi-dimensional delay calculation strategy that combines spatial and functional domains. By using floor parameters, the timing of nodes in different areas is separated to prevent cross-floor interference; simultaneously, the network coordinator and routing nodes are given high time priority to ensure that the network backbone architecture is established before the edge terminals. This hierarchical networking strategy not only optimizes the network topology but also further improves the determinism and success rate of the networking process.

[0035] 3. This application utilizes a silent monitoring mechanism to achieve passive synchronization and link optimization before network access. During the waiting period, nodes can capture network beacons and extract synchronization information. This ensures that nodes have a clear access target and clock reference when sending requests, avoiding resource waste caused by blind transmission. Furthermore, this solution does not require changes to the existing hardware power supply architecture; it can be adapted to various emergency lighting systems solely through software logic, offering excellent compatibility and cost advantages. Attached Figure Description

[0036] Figure 1 This paper illustrates a system architecture diagram of a concurrent power-on logic-sequential networking method for an emergency lighting wireless system according to an embodiment of this application.

[0037] Figure 2 The flowchart illustrates a method for concurrent power-on logic sequencing networking of an emergency lighting wireless system according to an embodiment of this application. Detailed Implementation

[0038] The present application will be further described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are merely illustrative of the application and are not intended to limit the scope of the application.

[0039] like Figure 1 and Figure 2 As shown, this application embodiment provides a method for concurrent power-on logic sequencing networking of an emergency lighting wireless system, including the following steps S1-S4.

[0040] S1. Under the trigger condition of detecting a main power failure and switching to backup battery power, all emergency lighting nodes in the emergency lighting wireless system start up concurrently and complete the initialization self-test process of the emergency lighting nodes.

[0041] Specifically, the detection of mains power failure relies on the real-time monitoring of the mains voltage by the power management module inside the node. When the mains AC voltage amplitude is detected to drop below a preset threshold, or a strong cut-off signal is received from the fire control center via a hard-wired interface, the relay or solid-state switch in the power management circuit immediately performs a switching action, connecting the backup battery to the power supply circuit. Due to the electrical characteristics of the power supply circuit, this switching action is synchronous in the circuit, causing all emergency lighting nodes in the same distribution circuit or the same control area to simultaneously receive power input within a very short time window (usually on the order of milliseconds or even microseconds).

[0042] Upon receiving power, the microcontroller unit inside the emergency lighting node immediately executes the startup boot program and enters the initialization self-test process. The self-test process includes verifying the read / write integrity of the on-chip memory, querying and resetting the register status of the wireless radio frequency communication module, and detecting the analog-to-digital conversion of the backup battery's current voltage level to ensure the node has normal communication and lighting functions. However, in existing technologies, nodes often attempt to send network access requests or beacons immediately after completing the self-test. In the aforementioned concurrent startup scenario, without effective control, a large number of nodes sending radio frequency signals to the shared wireless channel at almost the same time can cause the channel's instantaneous load to exceed its capacity, leading to severe co-channel interference and signal collisions (i.e., broadcast storms), thus causing communication link blockage. For example, in an office building with 500 wireless emergency lights, at the moment a fire occurs and non-fire-fighting power is cut off, these 500 devices will power on and complete initialization as a whole, resulting in concentrated channel contention and creating difficulties for subsequent network deployment.

[0043] S2. The emergency lighting node reads the inherent attribute parameters pre-configured in the internal memory of the emergency lighting node, wherein the inherent attribute parameters include the floor number of the emergency lighting node and the network role of the emergency lighting node.

[0044] Specifically, internal memory typically uses non-volatile storage media, such as electrically erasable programmable read-only memory or flash memory. The characteristic of this type of memory is that even in the event of a complete power outage from both the main power supply and the backup battery, the data stored within it remains intact, ensuring that the node can accurately retrieve its configuration information after any abnormal power failure and restart.

[0045] Pre-configuration refers to the data writing operation completed during the equipment manufacturing or on-site installation and commissioning phase. During project implementation, installers typically use handheld infrared encoders or dedicated configuration tools to write specific parameters into the storage address of each node via wired interface or near-field wireless communication.

[0046] The "Floor Number" parameter (denoted as F) is an integer value that physically corresponds to the building floor where the node is located. In a hierarchical network architecture, the floor number serves as a spatial identifier, used to divide the three-dimensional building space into different vertical levels, providing a data foundation for subsequent algorithms to achieve spatial isolation across floors. The "Network Role" parameter (denoted as R) defines the functional attributes of a node in a wireless ad hoc network (such as a Zigbee or Mesh network). This parameter typically classifies devices into three categories: a network coordinator responsible for establishing the network, allocating network addresses, and maintaining routing tables, which acts as the logical center of the network; a router responsible for multi-hop relay forwarding of data to extend network coverage; and terminal devices that are only responsible for sending and receiving their own data and do not have routing forwarding functions, typically acting as leaf nodes in the network.

[0047] Reading these inherent attribute parameters provides differentiated input variables for subsequent logical sequencing algorithms. In their factory state, the hardware circuitry and firmware of all nodes are typically identical, i.e., they are in a homogeneous state. By reading these specific parameters, the algorithm can assign unique characteristics to each node, thereby breaking this homogeneity and allowing different nodes to exhibit differentiated behavior on the subsequent timeline.

[0048] For example, for an emergency lighting fixture installed in a corridor on the third floor of a building and planned for signal relay purposes, the data structure read from a specific address (e.g., 0x00A0) of the EEPROM by its microcontroller unit when executing step S2 may contain two key values: floor number F=3, and an enumeration value representing the router (e.g., R=0x02).

[0049] S3. The emergency lighting node calculates its own logical delay time based on the floor number and the network role using a preset logical sequencing algorithm, wherein the logical delay time is the silent waiting time before performing network networking actions.

[0050] Because a unified backup power supply is used, the power-on actions of all nodes overlap in time (i.e., concurrent). The algorithm uses software calculations to force this single physical concurrent event to be mapped onto a series of discrete coordinate points on the timeline. This is essentially a software-defined timing reconstruction, artificially creating the order in which nodes start up without changing the hardware power supply circuitry.

[0051] Logical delay time (denoted by T) is typically measured in milliseconds and is a time offset calculated from the moment power-on is complete. In traditional carrier sense multiple access (CSM) mechanisms, all nodes often attempt to compete for the channel simultaneously. Logical delay time, however, mandates a specific duration for which nodes must wait before activating their transmit circuitry.

[0052] From the perspective of communication flow control, introducing a logical delay time enables flow shaping of channel access requests. Without sequential control, concurrent power-ups result in a momentary spike in communication requests on the channel, often exceeding the instantaneous throughput capacity of the wireless channel. By introducing a differentiated logical delay, the system smooths this high spike across the time axis, distributing it over a wider time window. This ensures that the number of nodes attempting to access the channel at any given time is controlled within the linear range that the channel bandwidth can handle, effectively mitigating concurrent peaks and maintaining channel stability by delaying the transmission actions of some nodes.

[0053] Optionally, S3 includes the following sub-steps S31-S32.

[0054] S31. The emergency lighting node calls its random number generator to generate a non-negative random disturbance time value within a preset time window, which is used to eliminate the temporal overlap between emergency lighting nodes with the same floor number and the same network role.

[0055] Under the overall sorting strategy, although floor and role parameters can already stagger the timelines of most nodes, in actual deployments, there are often cases where nodes on the same floor and with the same role exist. For example, multiple router nodes may be installed in the same corridor. Without random perturbation, the inherent attribute parameters of these nodes are completely identical, and the calculated logical delay times will also be exactly the same, causing them to collide precisely at the moment of unsilencing. The purpose of introducing random perturbation time values ​​is to add tiny jitter to the established rules, breaking this deadlock. Random number generators typically use the analog-to-digital conversion noise floor of the floating pins inside the microcontroller or the count value of the free-running timer as a seed to generate pseudo-random numbers. The preset time window is usually set within a small range, such as 0 to 5 milliseconds. This range is sufficient to stagger similar nodes at the microsecond-level signal transmission level, and because the value is extremely small, it will not disrupt the overall macroscopic sorting structure determined by the floor and role.

[0056] S32. The emergency lighting node performs a weighted superposition operation, linearly superimposing the preset system base delay, various spatial domain delay components that are positively correlated with the floor number, the functional domain delay components corresponding to the network role, and the random disturbance time value, thereby calculating the logical delay time. The spatial domain delay components are used to achieve time separation of nodes on different floors, and the functional domain delay components are used to achieve time separation of nodes with different roles on the same floor.

[0057] The weighted superposition formula employs a linear structure, summing each influencing factor as an independent addend. The system base delay represents the minimum physical preparation time required for the system to stabilize and receive signals after power-on, or a safety quiet period reserved to avoid power fluctuations at power-on. This linear superposition algorithm does not involve complex floating-point or exponential operations, making it highly efficient for embedded MCUs with limited computing resources, consuming almost no additional processing time.

[0058] Continuing with the example of the router node located on the 3rd floor, assume the system's default base latency is 100 milliseconds. Based on subsequent calculation logic (assuming a 200ms interval between floors and a 50ms router role latency), the node calculates the following components: system base latency 100ms, spatial domain latency component 600ms (3rd floor × 200ms), and functional domain latency component 50ms. At this point, the random number generator generates a 3ms random perturbation value. The node linearly adds these values: 100 + 600 + 50 + 3 = 753ms. Ultimately, the router node on the 3rd floor determines its logical latency to be 753 milliseconds, meaning it attempts to access the network at the 753rd millisecond after power-on.

[0059] Optionally, the logic for determining the functional domain delay component of the network role in S32 is as follows:

[0060] When the network role of the emergency lighting node is a network coordinator, the emergency lighting node is given the highest time priority with the corresponding minimum functional domain delay component; when the network role is a routing node, the emergency lighting node is given a secondary time priority with the corresponding medium functional domain delay component; when the network role is an end-user device, the emergency lighting node is given the lowest time priority with the corresponding maximum functional domain delay component, thereby ensuring that the network coordinator and the routing node complete the network formation before the end-user device.

[0061] The underlying logic of this allocation strategy stems from the dependency of wireless ad hoc networks on the network hierarchy. In a Mesh or Zigbee network, the network coordinator is the creator and maintainer of the network and must be the first to start up, establishing a network identity and broadcasting the initial beacon. Router nodes follow suit, responsible for extending signal coverage and providing relay paths for subsequent nodes. End devices, typically leaf nodes, must wait for their parent node (coordinator or router) to be in place before they can perform association operations. If end devices attempt to connect before routers, due to the lack of available parent nodes, they will be trapped in ineffective channel scanning, wasting energy and consuming channel resources.

[0062] Therefore, there is an inverse relationship between time priority and latency component weight. Higher priority means a more fundamental role for the node in network construction, thus requiring a shorter silent waiting time to allow it to preempt channels earlier. In practical engineering parameter configurations, it is recommended to set the latency component of the network coordinator's functional domain to 0 milliseconds, so that it has no additional role burden when calculating total latency; set this component for router nodes to 50 milliseconds, leaving a time window for coordinator initialization; and set this component for end-device devices to 100 milliseconds, ensuring they enter the network only after the backbone is basically formed.

[0063] By implementing this differentiated delay setting based on role, the entire network topology unfolds in a highly ordered manner, similar to the growth of a tree's root system: first, the network coordinator (main root) establishes the network baseline; then, router nodes (lateral roots) connect sequentially and extend their coverage outwards; finally, a large number of terminal devices (root hairs) attach and connect to the nearest parent node. This orderly expansion from the center to the edge, from the backbone to the tip, fundamentally avoids invalid channel contention caused by a reversal of the order.

[0064] Optionally, the calculation logic for the spatial domain delay component of the floor number in S32 includes the following sub-steps S321-S322.

[0065] S321. The emergency lighting node obtains a preset floor delay step coefficient, wherein the floor delay step coefficient defines the minimum time protection interval between adjacent floors.

[0066] S322. The emergency lighting node uses a multiplication operation to multiply the floor number by the floor delay step coefficient to generate the spatial domain delay component, thereby establishing a logical access timing wavefront that increases layer by layer from the bottom to the top in the emergency lighting wireless system, preventing cross-floor channel contention between emergency lighting nodes on adjacent floors.

[0067] A closer analysis of the physical parameters reveals that the floor delay step size coefficient (often denoted as K1 in engineering) is not an arbitrarily set value, but rather an average safe time window calculated based on the throughput and node density of a single-layer network. Physically, it represents the estimated time required to complete the initial contention for access by most nodes within a single floor. The purpose of setting this coefficient is to ensure that when the network access activity window moves to the next floor, the channel load on the current floor has already fallen back to a stable level and is no longer consuming major spectrum resources.

[0068] The calculation principle of the spatial domain delay component adopts a simple linear multiplication model. By multiplying discrete integer floor numbers by a fixed step size coefficient, the algorithm directly maps the vertical spatial coordinates of the building into linear increments on the time axis. This approach ensures that the start-up time difference between any two adjacent floors is constant and predictable, and will not cause nonlinear timing disorder due to changes in floor height.

[0069] This layered, incremental delay setting constructs a logical access timing wavefront throughout the entire building space. Access permissions are not activated synchronously across the entire building, but rather spread upwards layer by layer, like ripples spreading across water or a scan line. At time T1, only the first-floor nodes are deactivated; at time T2, the wavefront advances to the second floor. This visually represented wave-like progression transforms the originally chaotic concurrent events in the three-dimensional space into a strictly layered, linear sequence.

[0070] This design stems from the physical scenario of cross-floor channel contention. While modern building floors are reinforced with concrete, they cannot completely shield radio signals, especially in stairwells, atriums, or near windows, where signal coverage areas often overlap. If nodes on the second and third floors simultaneously initiate high-intensity access requests, the signal from the third-floor node can easily cause co-channel interference to the second-floor node's reception, a problem known as the "near-far effect" or "hidden terminal" problem. Through the aforementioned spatial isolation strategy, the system forcibly staggers the active periods of upper and lower floors, fundamentally reducing the probability of channel conflicts caused by physical proximity.

[0071] Continuing with the example of the router node on the third floor, let's assume the preset floor delay step size is 200 milliseconds (ms). For this third-floor node, its MCU performs a multiplication operation: 3 × 200ms = 600ms, thus obtaining a spatial domain delay component of 600ms. Comparing this to the second-floor node below, the calculation result is 2 × 200ms = 400ms. A strict 200ms start-up time difference is formed between the two. This 200ms time protection window is sufficient to accommodate dozens of standard short-frame handshake interactions, thus verifying that when the third-floor node begins to attempt access, the communication peak of the second-floor node has already passed, and the two do not interfere with each other.

[0072] S4. The emergency lighting node maintains a silent wireless reception state during each time period of the logical delay time, and at the end of the logical delay time, the emergency lighting node is triggered to perform a network networking action corresponding to the network role. The network networking action includes a network establishment action initiated by the network coordinator or a network access request action initiated by a non-coordinator node, thereby realizing the orderly access of all emergency lighting nodes on the time axis.

[0073] In the previous steps, the node only performed numerical calculations of the delay time. This step, however, transforms this abstract value into state constraints during actual operation. It ensures that the node strictly adheres to the silence rule within the specified time window and does not perform any active radio frequency transmission operations.

[0074] This step defines two distinct behavior patterns based on the node's role. For a node configured as a network coordinator, its networking action is network establishment, which involves initializing network parameters and periodically broadcasting beacon frames to announce the network's existence and wait for other nodes to join. For a non-coordinator node configured as a router or end device, its networking action is a network access request, which involves switching from a passive receiving state to an active sending state after the silent period ends, sending an association request frame to the discovered parent node to request joining the network.

[0075] This mechanism constructs a dynamic picture on the timeline of multiple nodes activating and sequentially connecting at different points in time. As the system runs, nodes from different floors and with different roles are awakened and trigger communication actions in a pre-calculated order, like dominoes. This strict orderliness replaces the physically chaotic concurrent startup, ensuring that the number of active nodes in the channel is within a controllable range at any given moment.

[0076] Continuing with the example of the router node on the third floor, this node, after calculating the logical delay time of 753 milliseconds, will not immediately send data. Instead, it will remain in a silent receiving state until the 753rd millisecond after power-on. At this point, since its role is that of a router (not a coordinator), its action is to send a network access request to the parent node already established in the network (e.g., the network coordinator that started broadcasting beacons at 0 milliseconds, or the router on the second floor that started at 400 milliseconds), rather than establishing a new network as a coordinator would.

[0077] Optionally, S4 includes the following sub-steps S41-S43.

[0078] S41. The emergency lighting node starts an internal timer with a duration equal to the logical delay time, and immediately locks the wireless transmission module of the emergency lighting node, making the wireless transmission module prohibited from sending signals, while simultaneously activating the wireless receiving module of the emergency lighting node to enter a continuous listening state.

[0079] In the implementation of embedded systems, the use of hardware timer resources is essential. Unlike delays implemented solely through software loop instructions (such as for loops), which are easily interrupted by system interrupts or other high-priority tasks, leading to timing instability and failing to meet the stringent microsecond-level timing requirements of communication protocols, hardware timers are directly driven by the clock source of the microcontroller unit and operate independently of the central processing unit. Once set, they can countdown with extremely high precision and accurately notify the CPU of the time's arrival by generating interrupt signals, thus ensuring a high degree of determinism in the silent duration.

[0080] Regarding the low-level control logic of the RF module, locking the transmit and enabling the receive operations is typically achieved by modifying the control registers of the RF transceiver chip. Specifically, the MCU sends a command to the RF chip through the serial peripheral interface to set the enable position of the power amplifier to a low level, physically cutting off the power supply to the transmit path and ensuring that no RF energy is radiated out; at the same time, it sets the enable position of the low-noise amplifier to a high level, activating the receive link. This hardware-level locking physically eliminates the possibility of mis-transmissions caused by program malfunctions.

[0081] This period of silence is not simply a passive waiting period, but a crucial window for assessing the channel environment and capturing network information. While transmission is prohibited, the receiving circuitry continues to operate, performing idle channel assessments and monitoring the background noise level of the current frequency band. More importantly, it can capture network beacon frames present in the air. This "listen before you speak" mechanism allows nodes to be aware of the surrounding network topology before formally requesting access, rather than blindly initiating connections.

[0082] For example, suppose the logical delay time calculated in the aforementioned steps is 100 milliseconds. When the MCU executes S41, it first calculates the count value required by the timer (assuming a clock frequency of 1MHz, the count value is 100,000), writes it to the timer's load register, and starts counting. Next, the MCU writes a configuration word (e.g., 0x02) to the wireless chip. This instruction forcibly shuts down the transmit circuit and enters a low-power receive mode (RX_ON). During this period, the MCU can enter a sleep state to reduce power consumption, retaining only receive interrupt and timer interrupt responses until the timer overflows after 100ms and wakes up the CPU.

[0083] S42. During the operation of the internal timer, if the wireless receiving module receives at least one network beacon frame broadcast from a network-connected node in the emergency lighting wireless system, the emergency lighting node parses the network beacon frame to extract network synchronization information and stores the network synchronization information in the cache of the emergency lighting node; wherein, the network beacon frame is a link layer management frame periodically broadcast by the network-connected node, and the data structure of the network beacon frame includes at least a personal area network identifier for uniquely identifying the emergency lighting wireless system, a status flag indicating that the current network allows new nodes to access, and time synchronization parameters for achieving time slot alignment.

[0084] From a protocol layer perspective, network beacon frames are a type of management frame belonging to the Media Access Control (MAC) layer, fundamentally different from ordinary data frames that carry specific service data. They do not contain application layer payload data; instead, they serve as a heartbeat signal for the network, broadcast at fixed time intervals by the network coordinator or nodes with routing capabilities to the surrounding space. This is used to announce the network's existence, maintain network synchronization, and announce network parameters.

[0085] Specifically, the key fields in the data structure are analyzed, and their functions are as follows:

[0086] First, a Personal Area Network (PAN) identifier is a unique 16-bit or 64-bit address code used to logically distinguish different wireless networks. In densely populated areas, adjacent buildings or different floors of the same building may have multiple physically independent emergency lighting systems deployed. The PAN identifier ensures that nodes can identify and filter signals from systems outside their own, preventing nodes from mistakenly attempting to join the networks of neighboring buildings, thus guaranteeing the security and accuracy of network configuration.

[0087] Secondly, the access permission flag acts as a logical gating mechanism. Since the number of child nodes that each parent node (coordinator or router) can manage is limited (due to memory capacity), when the number of child nodes reaches the limit, the parent node will set the flag to "prohibited". Nodes waiting to access the network that receive this flag will recognize that the parent node has no free capacity, thus abandoning their requests and instead searching for other parent nodes, avoiding unnecessary interactions.

[0088] Finally, the time synchronization parameter typically includes the local clock count of the transmitting node at the moment the frame was transmitted. The receiving node reads this parameter and, combined with the signal's transmission time in the air, calibrates its local clock to achieve clock alignment with the parent node. This is crucial for subsequent communication based on Time Division Multiple Access (TDMA) or Slotted CSMA, ensuring that both the transmitting and receiving parties operate within the correct time window.

[0089] This passive synchronization mechanism offers significant advantages over active scanning. In traditional network access procedures, nodes typically need to actively send a scan request and then wait for a scan response, involving two handshake interactions. In this embodiment, however, the node utilizes a silent waiting period to listen, acquiring network synchronization information and access permission before sending any data. This not only reduces the number of control messages on the channel and lowers the probability of collisions, but also ensures that the node has a clear target and time base when initiating subsequent connections, significantly reducing the number of handshake failures caused by clock asynchrony or unreachable target nodes.

[0090] Regarding the design of the caching strategy, since the silent period (e.g., several hundred milliseconds) may be longer than the beacon broadcast period, a node may receive beacons from multiple different parent nodes. The caching mechanism requires the node to allocate a dedicated buffer in memory to store all captured valid beacon information in the form of a list, rather than just keeping the last one.

[0091] Continuing with the example of the router node on the third floor, its receiving module remains in a continuous listening state during the 753-millisecond silent wait period. Assume that at the 200th millisecond, it captures a beacon frame broadcast from the network coordinator on the first floor; and at the 600th millisecond, it captures another beacon frame broadcast from a router already connected to the network on the second floor. The node parses these two frames, extracting the domain name identifier (e.g., 0x1234), the access permission flag (both True), and their respective timestamps. It then stores these two sets of data as candidate records in a cache list for use in subsequent decision-making processes.

[0092] Optionally, S42 includes the following sub-steps S421-S423.

[0093] S421. The emergency lighting node monitors and calculates the signal strength indication value of the received network beacon frames in real time.

[0094] Signal Strength Indicator (RSSI) is a core physical metric for measuring the quality of a wireless link. Its value directly reflects the power level of the radio frequency signal reaching the receiving antenna. In complex indoor wireless propagation environments, signals experience attenuation, reflection, and multipath effects. RSSI objectively characterizes the loss along the current communication path. Typically, RSSI is a negative value; the smaller its absolute value (i.e., the closer it is to 0), the stronger the received signal energy, the higher the signal-to-noise ratio of the link, and the lower the bit error rate during data transmission.

[0095] S422. The emergency lighting node compares the signal strength indication value with a preset signal strength threshold, and determines the network beacon frame as a valid beacon only when the signal strength indication value is greater than the signal strength threshold.

[0096] A preset signal strength threshold (often set to around -85dBm in engineering practice) acts as a quality threshold here. This threshold is set to eliminate weak signals at the edge of communication coverage. Although signals below this threshold (e.g., -90dBm) may still be physically demodulated, these links are often extremely unstable and easily disconnected due to environmental interference. Through this comparison step, the system forcibly filters out visible but unreliable potential parent nodes, ensuring that nodes only establish connections within a "safe zone" with sufficiently good signal quality, thereby guaranteeing the stability of subsequent communication.

[0097] S423. The emergency lighting node selects the optimal network beacon frame with the largest signal strength indication value from all network beacon frames that are determined to be valid, and extracts the network synchronization information from the optimal network beacon frame, thereby locking the parent node with the best network link quality as the access target.

[0098] The optimal node selection algorithm is implemented by traversing the list of valid beacons in the cache. The microcontroller unit compares the RSSI values ​​of each candidate beacon one by one, using bubble sort or maximum value search to locate the strongest signal source. This process ensures that nodes do not randomly connect to any visible parent node, but automatically attach to the strongest physical link parent node through an optimal selection mechanism, thereby optimizing the spatial topology of the entire wireless network.

[0099] Continuing with the example of the router node on the 3rd floor, during the silent listening period, assume that the node successively captures three beacon frames from different parent nodes: beacon A from the node at the 2nd floor stairwell, with an RSSI of -60dBm; beacon B from the node in the 1st floor lobby, with an RSSI of -90dBm; and beacon C from the node at the other end of the 2nd floor corridor, with an RSSI of -75dBm. The system's preset channel threshold is -85dBm.

[0100] During the filtering process, the node first determines that beacon B (-90dBm) is less than the threshold (-85dBm), marks it as invalid, and discards it to avoid connecting to the weak-signal node on the first floor. Then, the node compares the remaining valid beacons A (-60dBm) and C (-75dBm). Since -60dBm is greater than -75dBm, the node ultimately determines beacon A as the optimal network beacon, extracts synchronization parameters from beacon A, and identifies the node at the second-floor stairwell as the target for sending access requests.

[0101] S43. When the count value of the internal timer reaches the logical delay time, the emergency lighting node unlocks the wireless transmission module and controls the wireless transmission module to send a network access request according to the network synchronization information.

[0102] Specifically, the end of the silent period is triggered by a timeout event of the hardware timer. When the value of the timer counter register inside the microcontroller unit reaches a preset logical delay threshold, the timer hardware module generates a high-priority interrupt signal. The MCU responds to this interrupt, suspends the current task, jumps to the interrupt service routine to toggle the status flag, officially announcing the end of the silent waiting phase and entering the network access execution phase.

[0103] Before sending a request, the node needs to construct a data packet that conforms to the communication protocol specification. The MCU retrieves the network synchronization information extracted and locked in the previous steps from the cache, including the short address of the target parent node, the Personal Area Network Identifier (PAN ID), and the time slot calibration parameters. Using this information, the MCU fills in the destination address field and network identification field in the Media Access Control (MAC) frame header, and fills in the node's own long address and device type information in the payload, assembling a complete network access request frame.

[0104] Subsequently, the system performs a state switch for the RF module. The MCU sends control commands to the RF transceiver chip via the serial interface, first shutting down the low-noise amplifier to end the receive mode; then starting the frequency synthesizer and phase-locked loop to lock the carrier frequency onto the target channel; finally, turning on the power amplifier. To prevent spectral sputtering, the power amplifier typically requires a microsecond-level warm-up and ramp-up process before the output power stabilizes and the data packets are modulated onto the carrier for transmission.

[0105] For example, suppose a terminal node located at the end of the 4th floor has a calculated logical delay of 800 milliseconds. When the 800th millisecond arrives after power-on, a timer overflow interrupt wakes up the MCU. The node immediately constructs an association request command frame containing its own device information based on the optimal parent node information recorded in its cache (e.g., a router on the 3rd floor with address 0x001A). As the radio frequency circuit completes the switch from receive to transmit mode, the node sends this request frame to the target parent node within a precise time slot, requesting to join the network.

[0106] Optionally, S43 includes the following sub-steps S431-S433.

[0107] S431. When the count value of the internal timer reaches the logical delay time, the emergency lighting node activates the physical channel idle detection mechanism to listen to the signal energy value of the current wireless channel.

[0108] Although the system has theoretically allocated non-conflicting time slots to each node through logical algorithms in the preceding steps, in the actual physical environment, the crystal oscillator frequency of each node may drift slightly, or there may be wireless interference sources outside the system (such as Wi-Fi devices or Bluetooth devices) in the environment. Therefore, adding a physical listening operation at the point where the logical delay ends and the system is ready to transmit can effectively cope with the aforementioned unforeseen minor overlaps or sudden external interference, and prevent signal damage caused by forced transmission.

[0109] The physical channel idle detection mechanism relies on the energy detection circuit inside the wireless transceiver chip. This circuit integrates the received radio frequency signal within a very short time window (usually 8 symbol periods) to quantify the average energy level in the current channel.

[0110] S432. The emergency lighting node determines whether the signal energy value is lower than the preset channel busy threshold. If the determination result is yes, it confirms that the current channel is idle and immediately controls the wireless transmission module to send the network access request.

[0111] The logic for setting the channel busy threshold is designed to distinguish between background thermal noise and effective interference signals. Typically, this threshold is set above the receiver sensitivity and below the effective demodulation level (e.g., -75 dBm). When the detected energy is below this value, the system considers the channel clean, or that the noise present is insufficient to affect the correct demodulation of data packets.

[0112] S433. If the determination result is negative, the emergency lighting node confirms that the current channel is busy and suspends the transmission action, enters a microsecond-level contention backoff process, and continues to perform the transmission operation of the network access request after the channel is detected to be idle again, thereby eliminating residual signal collisions.

[0113] The contention backoff process typically employs a binary exponential backoff algorithm or a fixed-window random backoff algorithm. It's important to emphasize that this backoff occurs on a microsecond-level timescale, fundamentally different from the millisecond-level logical delays mentioned earlier. Logical delays address macroscopic congestion by distributing hundreds of nodes across different time periods; while physical backoff addresses microscopic, instantaneous conflicts by making minute, dynamic adjustments to the launch timing.

[0114] Using the example of the terminal node on the fourth floor mentioned earlier, suppose that at the moment the timer overflows at 800 milliseconds and is about to send a request, the node suddenly detects that a microwave oven in the environment is starting up, generating strong electromagnetic radiation, or that a nearby Wi-Fi device is transmitting large amounts of data, causing the channel energy detection value to spike to -50dBm (above the busy threshold). At this point, the node will not force the data transmission but will immediately suspend the transmission task and randomly wait for a small backoff period (e.g., 320 microseconds). After this small delay ends, the node listens again. If it finds that the channel energy has dropped back to -90dBm, it will immediately transmit the associated request frame.

[0115] It should be understood that the sequence number of each step in the above embodiments does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.

[0116] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. A method for concurrent power-on logic sequencing networking of an emergency lighting wireless system, characterized in that, Includes the following steps: S1. Under the trigger condition of detecting a main power failure and switching to backup battery power, all emergency lighting nodes in the emergency lighting wireless system start up concurrently and complete the initialization self-test process of the emergency lighting nodes. S2. The emergency lighting node reads inherent attribute parameters pre-configured in the internal memory of the emergency lighting node, wherein the inherent attribute parameters include the floor number of the emergency lighting node and the network role of the emergency lighting node; S3. The emergency lighting node calculates its own logical delay time based on the floor number and the network role using a preset logical sequencing algorithm, wherein the logical delay time is the silent waiting time before performing network networking actions; S4. The emergency lighting node maintains a silent wireless reception state during each time period of the logical delay time, and at the end of the logical delay time, the emergency lighting node is triggered to perform a network networking action corresponding to the network role. The network networking action includes a network establishment action initiated by the network coordinator or a network access request action initiated by a non-coordinator node, thereby realizing the orderly access of all emergency lighting nodes on the time axis.

2. The concurrent power-on logic-sequential networking method for an emergency lighting wireless system according to claim 1, characterized in that, S3 includes the following sub-steps: S31. The emergency lighting node calls the random number generator of the emergency lighting node to generate a non-negative random disturbance time value within a preset time window, which is used to eliminate the temporal overlap between emergency lighting nodes with the same floor number and the same network role. S32. The emergency lighting node performs a weighted superposition operation, linearly superimposing the preset system base delay, various spatial domain delay components that are positively correlated with the floor number, the functional domain delay components corresponding to the network role, and the random disturbance time value, thereby calculating the logical delay time. The spatial domain delay components are used to achieve time separation of nodes on different floors, and the functional domain delay components are used to achieve time separation of nodes with different roles on the same floor.

3. The concurrent power-on logic-sequential networking method for an emergency lighting wireless system according to claim 2, characterized in that, The logic for determining the functional domain delay component of the network role in S32 is as follows: When the network role of the emergency lighting node is a network coordinator, the emergency lighting node is given the highest time priority with the corresponding minimum functional domain delay component; when the network role is a routing node, the emergency lighting node is given a secondary time priority with the corresponding medium functional domain delay component; when the network role is an end-user device, the emergency lighting node is given the lowest time priority with the corresponding maximum functional domain delay component, thereby ensuring that the network coordinator and the routing node complete the network formation before the end-user device.

4. The concurrent power-on logic-sequential networking method for an emergency lighting wireless system according to claim 3, characterized in that, S4 includes the following sub-steps: S41. The emergency lighting node starts an internal timer with a duration equal to the logical delay time, and immediately locks the wireless transmission module of the emergency lighting node, so that the wireless transmission module is in a state of prohibiting the transmission of signals, and at the same time, the wireless receiving module of the emergency lighting node is turned on to enter a continuous listening state. S42. During the operation of the internal timer, if the wireless receiving module receives at least one network beacon frame broadcast from a network-connected node in the emergency lighting wireless system, the emergency lighting node parses the network beacon frame to extract network synchronization information and stores the network synchronization information in the cache of the emergency lighting node; wherein, the network beacon frame is a link layer management frame periodically broadcast by the network-connected node, and the data structure of the network beacon frame includes at least a personal area network identifier for uniquely identifying the emergency lighting wireless system, a status flag indicating that the current network allows new nodes to access, and time synchronization parameters for achieving time slot alignment; S43. When the count value of the internal timer reaches the logical delay time, the emergency lighting node unlocks the wireless transmission module and controls the wireless transmission module to send a network access request according to the network synchronization information.

5. The concurrent power-on logic-sequential networking method for an emergency lighting wireless system according to claim 2, characterized in that, The calculation logic for the spatial domain delay component of the floor number in S32 includes the following sub-steps: S321. The emergency lighting node obtains a preset floor delay step coefficient, wherein the floor delay step coefficient defines the minimum time protection interval between adjacent floors; S322. The emergency lighting node uses a multiplication operation to multiply the floor number by the floor delay step coefficient to generate the spatial domain delay component, thereby establishing a logical access timing wavefront that increases layer by layer from the bottom to the top in the emergency lighting wireless system, preventing cross-floor channel contention between emergency lighting nodes on adjacent floors.

6. The concurrent power-on logic-sequential networking method for an emergency lighting wireless system according to claim 4, characterized in that, S42 includes the following sub-steps: S421. The emergency lighting node monitors and calculates the signal strength indication value of the received network beacon frames in real time; S422. The emergency lighting node compares the signal strength indication value with a preset signal strength threshold, and determines that the network beacon frame is a valid beacon only when the signal strength indication value is greater than the signal strength threshold; S423. The emergency lighting node selects the optimal network beacon frame with the largest signal strength indication value from all network beacon frames that are determined to be valid, and extracts the network synchronization information from the optimal network beacon frame, thereby locking the parent node with the best network link quality as the access target.

7. The concurrent power-on logic-sequential networking method for an emergency lighting wireless system according to claim 4, characterized in that, S43 includes the following sub-steps: S431. When the count value of the internal timer reaches the logical delay time, the emergency lighting node starts the physical channel idle detection mechanism to listen to the signal energy value of the current wireless channel; S432. The emergency lighting node determines whether the signal energy value is lower than the preset channel busy threshold. If the determination result is yes, it confirms that the current channel is idle and immediately controls the wireless transmission module to send the network access request. S433. If the determination result is negative, the emergency lighting node confirms that the current channel is busy and suspends the transmission action, enters a microsecond-level contention backoff process, and continues to perform the transmission operation of the network access request after detecting that the channel is idle again, thereby eliminating residual signal collisions.

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