Automatic pairing method for elevator coverage system based on RSSI spatial features

Abstract

The invention provides an automatic pairing method for an elevator coverage system based on RSSI spatial characteristics, and relates to the technical field of wireless communication. The slave machine continuously reports RSSI in the vertical movement of the lift car, the host machine calculates and updates a historical maximum RSSI value, a historical minimum RSSI value and a difference value dynamic range to form a hoistway space fingerprint, only one slave machine is allowed to be connected at the same time, and recognition, pairing and abnormal self-error correction are completed based on absolute strength judgment, extreme value judgment and dynamic range judgment; through cooperation of distributed non-cooperative frequency point self-distribution, host-dominated anti-interference frequency hopping, slave uplink power self-adaptive control and 4G / 5G TDD frame-based synchronization, the method is suitable for a multi-hoistway complex scene, connection reliability and interference resistance are improved, energy is saved, and cost is reduced.

Description

Technical Field

[0001] This invention relates to the field of wireless communication technology, and in particular to an automatic pairing method for elevator coverage systems based on RSSI spatial characteristics. Background Technology

[0002] Inside elevator shafts, 4G / 5G cellular signals suffer from multipath fading due to walls and space, making it difficult to naturally reach the elevator car. To improve the mobile communication experience for terminals inside elevators, the industry generally adopts a "master-slave cascaded network" elevator coverage system: the master unit is installed in the elevator machine room (on one side of the top of the shaft), which first amplifies and processes the operator's base station signal, and then transmits the signal to the slave unit installed on the top of the car via a wireless link. The slave unit then receives and amplifies the signal a second time, and transmits the enhanced 4G / 5G signal into the car through a coverage antenna.

[0003] In scenarios with multiple hoists operating in parallel, traditional master-slave systems often rely on pre-configuration or manual pairing. Because FSK wireless links overlap between adjacent hoists, and adjacent masters often operate on the same or similar frequencies, "mismatch" issues can easily occur, with slaves mistakenly connecting to masters in neighboring hoists. Existing deployments rely on manual on-site debugging and troubleshooting, and lack unified timing synchronization and dynamic power management, resulting in poor anti-interference capabilities and energy efficiency in complex environments.

[0004] Existing solutions suffer from several drawbacks: 1) signal cross-over in multi-shaft environments leads to erroneous slave connection; 2) interference occurs between adjacent master units operating on the same or adjacent frequencies; 3) the pairing process relies on manual intervention and cannot be automated; and 4) the lack of dynamic power control and timing synchronization results in increased energy consumption and interference. These shortcomings lead to high deployment / maintenance costs and low reliability. Therefore, there is an urgent need for a system and method that can utilize the spatial dynamic characteristics of RSSI during elevator movement to automatically complete master-slave identification, pairing, and self-correction, and is equipped with distributed frequency self-allocation, frequency hopping, TDD synchronization, and power adaptive control to achieve reliable connection and interference resistance without manual intervention. Summary of the Invention

[0005] To overcome the shortcomings of existing technologies, the purpose of this invention is to provide an automatic pairing method for elevator coverage systems based on RSSI spatial characteristics. Based on the spatial fingerprint of RSSI during elevator movement, it realizes automatic pairing and self-correction of master and slave with zero configuration. Through collaborative mechanisms such as distributed non-cooperative frequency self-allocation, master-led anti-interference frequency hopping, slave uplink power adaptive control, and synchronization based on 4G / 5G TDD frames, it significantly reduces deployment and maintenance costs, improves connection reliability, and enhances anti-interference and energy-saving effects in complex multi-shaft scenarios.

[0006] To achieve the above objectives, the present invention provides the following solution: An automatic pairing method for elevator coverage systems based on RSSI spatial features is applied to an elevator coverage system including a master unit and a slave unit, wherein the master unit is located at the top of the elevator shaft and the slave unit is located at the top of the car. The method includes: During the vertical movement of the elevator car, the slave unit continuously detects and reports the Received Signal Strength Indication (RSSI) received from the master unit, and obtains an RSSI record. The host records and updates the historical maximum RSSI value max_RSSI, the historical minimum RSSI value min_RSSI, and the dynamic range of the difference between the two based on the RSSI to form a spatial fingerprint of the well. Under the premise that only one slave device is allowed to connect at the same time, the host performs slave device identification and pairing decision based on the spatial fingerprint; the decision is based on at least one of the following discriminations: absolute strength discrimination, extreme value discrimination, dynamic range discrimination, to distinguish slave devices in this hoistway from slave devices in adjacent hoistways; The host establishes or maintains a connection with the slave device in this hoistway, and triggers termination and re-competition for access to complete self-correction when a connection abnormality is determined based on the spatial fingerprint.

[0007] Preferably, the absolute strength determination is: at any position in this hoistway, the RSSI received by the slave device from the host device in this hoistway is higher than the RSSI received from the host device in the adjacent hoistway.

[0008] Preferably, the extreme value discrimination includes: the max_RSSI recorded when the slave device of this hoistway moves to the top is higher than the signal strength of the host device of this hoistway received by the slave device of the adjacent hoistway at its top; and the min_RSSI recorded when the slave device of this hoistway moves to the bottom is lower than the signal strength of the host device of this hoistway received by the slave device of the adjacent hoistway at its bottom.

[0009] Preferably, the ΔRSSI reported by the slave device in this hoistway is greater than the RSSI change range experienced by the slave device in the adjacent hoistway when receiving the signal from the master device in this hoistway.

[0010] Preferably, the host follows the principle of prioritizing the strongest signal to determine the access of a new slave device: when a new slave device requests access, if the max_RSSI of the currently connected slave device is higher than a preset threshold, the new slave device is rejected; otherwise, if the current RSSI of the new slave device exceeds the preset threshold relative to the most recently reported RSSI of the current slave device, the host disconnects the current connection and binds the new slave device; otherwise, the new slave device is rejected.

[0011] Preferably, when the same slave device is rejected for access a preset number of times, the master device triggers the dual-slave observation mode, allowing two slave devices to connect simultaneously and collect their respective RSSIs within the observation window, calculate their respective max_RSSI, min_RSSI, and ΔRSSI, and make a decision according to the following priority: the one with the larger max_RSSI is selected first; if they are equal, the one with the larger min_RSSI is selected; if they are still equal, the one with the larger ΔRSSI is selected; otherwise, the original slave device connection is maintained.

[0012] Preferably, the observation window adopts an adaptive setting: the host dynamically sets the observation duration according to the stability and value of ΔRSSI to match the complete motion cycle data acquisition at different well heights.

[0013] Preferably, the host executes a distributed non-cooperative frequency self-allocation mechanism to select the working frequency point, specifically including: after power-on, generating a random delay with a unique hardware ID as a random seed to stagger the frequency point scanning timing; scanning the background RSSI of available frequency points and performing adjacent frequency avoidance, marking strong interference frequency points and their adjacent frequency points as to be avoided; selecting the frequency point with the lowest background RSSI among the non-avoided frequency points; and randomly selecting one of the multiple clean frequency points when multiple clean frequency points exist.

[0014] Preferably, when the host detects that the number of consecutive communication failures with the slave device has reached a preset number, the host executes a host-led anti-interference frequency hopping mechanism: rescanning available frequency points and selecting a new working frequency point with less interference to switch transmission, so that the slave device can automatically address through the rescanning process and resume communication on the new frequency point.

[0015] Preferably, the slave device performs adaptive control of uplink transmit power based on the received downlink RSSI, dividing the downlink RSSI into multiple intervals and mapping them to corresponding transmit power levels. When the signal is strong, the power is reduced; when the signal is weak, the power is increased; and when continuous communication fails, the power is switched to the maximum.

[0016] According to specific embodiments provided by the present invention, the present invention discloses the following technical effects: (1) Zero-configuration deployment: The slave device automatically selects the host with the strongest signal, and the host automatically makes decisions and corrects errors. No manual intervention is required in the pairing process, which greatly reduces the deployment cost and threshold.

[0017] (2) High reliability connection: Through the "dual slave observation mode" and "long-term monitoring and error correction mechanism", it can effectively identify and correct initial misconfiguration and connection anomalies that occur during operation, ensuring that the slave always maintains a connection with the correct master.

[0018] (3) Strong anti-interference capability: It combines anti-interference methods such as "intelligent frequency selection", "active frequency hopping", "power adaptive control" and "TDD synchronization", which can effectively cope with complex and ever-changing wireless environments and ensure the stability of communication links.

[0019] (4) Energy saving and self-adaptation: The slave device's dynamic power control mechanism reduces equipment power consumption. The observation window can be adaptively adjusted according to ΔRSSI. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 A flowchart of the method provided in an embodiment of the present invention; Figure 2 Examples of prior art elevator coverage systems and multi-elevator scenarios provided in embodiments of the present invention; Figure 3 The overall system flowchart provided for embodiments of the present invention; Figure 4 A host workflow diagram provided for embodiments of the present invention; Figure 5 A slave device workflow diagram provided for embodiments of the present invention; Figure 6 This is a flowchart of the adjacent frequency avoidance strategy provided in an embodiment of the present invention; Figure 7 A flowchart illustrating the new slave device contention access process provided in this embodiment of the invention; Figure 8 This is a flowchart of the dual-slave observation mode provided in an embodiment of the present invention; Figure 9 This is a flowchart of the access prohibition and contention mode provided in an embodiment of the present invention; Figure 10 A flowchart of slave power control provided for embodiments of the present invention; Figure 11 This is a schematic diagram of the TDD synchronization mechanism provided in an embodiment of the present invention; Figure 12 This is a schematic diagram of multi-shaft main unit synchronization provided in an embodiment of the present invention; Figure 13 A flowchart illustrating the connection maintenance and data collection process provided in this embodiment of the invention. Detailed Implementation

[0022] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0023] The purpose of this invention is to provide an automatic pairing method for elevator coverage systems based on RSSI spatial characteristics. Based on the spatial fingerprint of RSSI during elevator movement, it realizes automatic pairing and self-correction of master and slave with zero configuration. Through collaborative mechanisms such as distributed non-cooperative frequency self-allocation, master-led anti-interference frequency hopping, slave uplink power adaptive control, and synchronization based on 4G / 5G TDD frames, it significantly reduces deployment and maintenance costs, improves connection reliability, and enhances anti-interference and energy-saving effects in complex multi-shaft scenarios.

[0024] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0025] Figure 1 The method flowchart provided in the embodiments of the present invention is as follows: Figure 1 As shown, this invention provides an automatic pairing method for elevator coverage systems based on RSSI spatial features, applied to elevator coverage systems including a master unit and a slave unit, wherein the master unit is located at the top of the elevator shaft and the slave unit is located at the top of the car. The method includes: Step 100: During the vertical movement of the elevator car, the slave unit continuously detects and reports the Received Signal Strength Indicator (RSSI) received from the master unit, and obtains the RSSI record; Step 200: The host records and updates the historical maximum RSSI value max_RSSI, the historical minimum RSSI value min_RSSI, and the dynamic range of the difference between the two based on the RSSI to form a spatial fingerprint of the well. Step 300: Under the premise that the host only allows one slave to connect at a time, the host performs slave identification and pairing decision based on the spatial fingerprint; the decision is based on at least one of the following discriminations: absolute strength discrimination, extreme value discrimination, dynamic range discrimination, to distinguish slaves in this hoistway from slaves in adjacent hoistways; Step 400: The host establishes or maintains a connection with the slave device in this shaft, and triggers the termination and re-competition for access to complete self-correction when the connection is determined to be abnormal based on the spatial fingerprint.

[0026] The present invention aims to provide an automatic pairing and anti-interference method and system for elevator coverage systems. Its core lies in utilizing the unique spatial structure and motion characteristics of elevator shafts, and through a series of collaborative intelligent algorithms, to achieve automatic identification, pairing and interference suppression of master and slave devices.

[0027] The system described in this invention includes a master unit and a slave unit. The master unit is located at the top of the elevator shaft, and the slave unit is located at the top of the elevator car. The system achieves automatic pairing and anti-interference through the following mechanism: The method comprises the following eight collaborative technical modules: 1. A shaft spatial fingerprint recognition mechanism based on motion feature perception This mechanism utilizes the characteristic that the Received Signal Strength Indication (RSSI) changes significantly and regularly with position during the vertical movement of the elevator car to generate a unique spatial fingerprint for each shaft.

[0028] Feature extraction: During operation, the slave device continuously detects and reports the RSSI values ​​it receives from the master device. The master device records and updates the historical maximum RSSI value (max_RSSI), historical minimum RSSI value (min_RSSI), and the dynamic range of the difference between the two values ​​(ΔRSSI) reported by the slave device.

[0029] Shaft identification criteria: (1) Absolute strength discrimination: Due to wall isolation and space loss, at any position in this shaft, the RSSI received by the slave device from the host device in this shaft is always higher than the RSSI received from the host device in the adjacent shaft.

[0030] (2) Extreme value discrimination: when the slave device of this hoistway moves to the top, the max_RSSI recorded is higher than the signal strength of the host device of this hoistway that the slave device of the neighboring hoistway can receive at the top; conversely, when it moves to the bottom, the min_RSSI recorded is lower than the signal strength of the host device of this hoistway that the neighboring hoistway receives at the bottom.

[0031] (3) Dynamic range determination: The ΔRSSI reported by the slave device in this hoistway is very likely to be greater than the RSSI change range experienced by the slave device in the neighboring hoistway when receiving the host signal in this hoistway.

[0032] 2. Distributed non-cooperative frequency self-allocation mechanism To address the constraint of inability to communicate between hosts, this mechanism enables each host to independently and intelligently select its operating frequency, reducing interference at the source.

[0033] Random Delay Scan: After the host is powered on, a random delay time of 0-10 seconds is generated using its unique hardware ID (such as SN number) as a random seed to stagger the host's frequency scanning timing and avoid simultaneous scanning decisions.

[0034] Intelligent frequency selection strategy: The host scans the background RSSI of all available frequencies (such as F1-F5) and executes the following decision process: (1) Adjacent frequency avoidance: If there is strong interference at a certain frequency (such as RSSI≥-60dBm), then the frequency and its adjacent frequencies are marked as "avoid use".

[0035] (2) Optimal selection: Among the non-"avoided" frequency points, select the frequency point with the lowest background RSSI.

[0036] (3) Random collision reduction: If there are multiple clean frequency points with the lowest RSSI (RSSI≤-95dBm), then randomly select one of these frequency points to further reduce the probability of multiple hosts having the same frequency point.

[0037] 3. Slave dynamic access mechanism based on signal strength contention The host follows the principle of "strongest signal priority" and dynamically manages the access of slave devices to ensure that the connected slave device has the best signal.

[0038] Access Decision: When a new slave device requests access, the master device executes the following decision process: (1) If the historical max_RSSI of the currently connected slave is higher than the set threshold (e.g., -20dBm), it indicates that it is highly likely to be a slave in this shaft, and the new access request is rejected.

[0039] (2) Otherwise, compare the current RSSI of the new slave with the RSSI most recently reported by the current slave. If the signal strength of the new slave exceeds a certain threshold (e.g., 5dB), the master disconnects the current connection and binds to the new slave.

[0040] (3) Otherwise, reject the new slave device connection.

[0041] 4. Dual-slave observation and multi-dimensional feature decision-making mechanism When the same slave fails to access the network multiple times, the "dual slave observation mode" is triggered, which allows the master to temporarily connect to two slaves and make a final decision by collecting their characteristic data.

[0042] Triggering condition: The number of consecutive access rejections (e.g., 3 times) of the same slave device reaches the threshold.

[0043] Observation window adaptive: The host dynamically sets the observation duration (e.g., from 60 seconds to 300 seconds) based on the ΔRSSI stability and value reported by the connected slave devices. The higher the floor, the longer the observation time, to ensure that complete motion cycle data is collected.

[0044] Multi-dimensional decision-making: Within the observation window, the master unit collects RSSI data reported by the two slave units and calculates their respective max_RSSI, min_RSSI, and ΔRSSI. After observation, decisions are made in order of priority. (1) Prioritize the option with the larger max_RSSI; (2) If max_RSSI is equal, then choose the one with larger min_RSSI.

[0045] (3) If all of the above are equivalent, then choose the one with larger ΔRSSI.

[0046] (4) If all features cannot be distinguished, the original slave connection is maintained.

[0047] Execution: Disconnect the slave connection of the machine identified as being in an adjacent shaft, and retain the slave connection of the machine in this shaft.

[0048] 5. Abnormal connection detection and self-repair mechanism (access prohibited and contention mode) This mechanism is used to handle abnormal connection states where the production time signal quality is substandard, and to perform self-repair.

[0049] Triggering condition: If the max_RSSI reported by the current slave device is consistently lower than the set threshold (e.g., -20dBm) for a period of time (e.g., 1 hour), the master device suspects that it is not a device in this hoistway.

[0050] Execution process: (1) The host disconnects the current slave connection and initiates a short "block access window" (e.g., 30 seconds).

[0051] (2) In this window, reject all access requests from the original slave machine, and listen for access requests from other new slave machines.

[0052] (3) If a new slave device is connected, it will be bound to it and the system will return to normal.

[0053] (4) If no new slave device is added within the window period, the original slave device is allowed to reconnect, but the number of disconnections is recorded. If the number of disconnections is too high (e.g., 3 times), an indicator light alarm will be triggered to prompt manual intervention.

[0054] 6. Host-led anti-interference frequency hopping mechanism When the communication environment deteriorates, the host actively switches its operating frequency to avoid interference.

[0055] Triggering condition: The host detects that the number of consecutive communication failures with the slave (e.g., 3 times) exceeds the threshold.

[0056] Execution process: The host actively scans and selects a new clean frequency, then transmits at a fixed power after switching. The slave device, unable to receive a signal, triggers a rescan, automatically finding the host's new frequency and reconnecting, thus restoring communication.

[0057] 7. Slave-mounted uplink power adaptive control mechanism The slave device adaptively adjusts its own transmission power based on the strength of the received downlink signal to achieve energy saving and noise reduction.

[0058] Power mapping table: The slave device pre-stores a power level mapping table, which divides the downlink RSSI into multiple intervals (such as ≥-30dBm, -31~-50dBm, -51~-70dBm, ≤-71dBm), and each interval corresponds to a specific transmit power level.

[0059] Dynamic adjustment: The slave device measures the downlink RSSI in real time, obtains the corresponding transmit power from a table, and adjusts it automatically. Power is reduced when the signal is strong and increased when the signal is weak. In the event of continuous communication failures, it automatically switches to maximum power to ensure link quality.

[0060] 8. System synchronization mechanism based on common TDD frames By using ubiquitous 4G / 5G base station signals as a synchronization source, the communication timing of all master and slave devices in the area is kept consistent, fundamentally avoiding send and receive conflicts.

[0061] Clock extraction: The host receives and demodulates the PSS / SSS synchronization signal of the base station and generates a 10ms local clock reference that is strictly synchronized with the base station's TDD frame.

[0062] Time Division Duplex (TDD) Synchronization: Host: Transmits signals in the first 5ms of a 10ms cycle and receives signals in the last 5ms.

[0063] Slave: Receives the synchronization signal from the master, locks its timing, and receives (listens to the master) in the first 5ms of the 10ms cycle, and transmits in the last 5ms.

[0064] All master and slave devices in the shaft transmit and receive at the same time, eliminating co-frequency interference within the system.

[0065] Preferably, to improve the reliability of RSSI data, the system preprocesses the acquired raw RSSI values. For example, a sliding window averaging filter algorithm is used to preprocess the acquired raw RSSI data to eliminate transient interference and noise interference, thereby improving the accuracy and reliability of the feature values. A queue of fixed length (e.g., N=5) is maintained. Each time a new RSSI sample value is obtained, it is placed at the end of the queue, and the oldest data is discarded. Then, the arithmetic mean of all data in the queue is calculated as the current valid RSSI value and output. The filtered RSSI value is used in all decision-making processes that require signal strength, effectively improving the system's anti-interference capability and discrimination accuracy.

[0066] See Figure 2 The elevator coverage system uses a master-slave cascaded networking method to achieve 4G / 5G signal coverage in the elevator car. The system typically consists of one master unit and one slave unit, and all devices have 4G / 5G signal amplification capabilities.

[0067] Main unit: As the central hub of the system, it is installed in the elevator machine room. The coverage antenna is installed on the top of the elevator shaft. It is responsible for receiving 4G / 5G signals from the operator's base station, performing initial amplification and processing, and transmitting the enhanced signal to the slave unit in the shaft through a wireless link.

[0068] Slave Unit: As an extension node for signal coverage, it is directly installed on the top of the elevator car. It receives and amplifies the signal sent by the host unit, and finally transmits the enhanced 4G / 5G signal into the car through the coverage antenna installed inside the car.

[0069] The master and slave devices cannot communicate with each other.

[0070] See Figure 3 The overall system flow is as follows: (1) All master and slave devices are powered on. The master device first listens to the interference of all frequencies in the environment (scanning RSSI), and then selects the optimal working frequency according to the frequency selection strategy and starts broadcasting. The slave device scans all frequencies at the same time to find the master device with the strongest signal.

[0071] (2) The slave device attempts to connect to the host with the strongest signal detected by the scan. The host only allows one slave device to connect and always tends to allow the slave device with the stronger signal to connect. If a stronger slave device requests to connect, the host will remove the currently weaker slave device and allow the stronger slave device to connect.

[0072] (3) After the connection is established, the slave device continuously reports the signal strength (RSSI) during elevator operation. The master device continuously records and updates the maximum and minimum values ​​of the signal strength.

[0073] (4) If a competition that is difficult to judge occurs (the same slave is denied access multiple times), the master will start the "dual slave observation mode" and listen to the two slaves for a period of time. By comparing the signal characteristics (maximum / minimum / range of change) reported by them, it will distinguish whether it is the slave in this hoistway or the slave in the neighboring hoistway. Finally, the connection of the slave in this hoistway will be maintained and the connection of the slave in the neighboring hoistway will be disconnected.

[0074] (5) During operation, the host continuously monitors (e.g., every hour) the max_RSSI reported by the slave and determines whether it is greater than the expected threshold (e.g., -20dBm). If it is not satisfied, the slave is disconnected and enters the "Access Denied and Contention Mode".

[0075] (6) During system operation, in order to reduce system interference, the following strategies are implemented simultaneously: 1) When the host is subjected to severe interference, it will implement a frequency hopping strategy to reduce the interference; 2) Depending on the strength of the received RSSI, the transmitter can only increase its own transmission power to save energy and reduce interference; 3) All devices are synchronized with the base station clock to avoid transmission and reception conflicts.

[0076] See Figure 4 The host workflow is as follows: (1) Power-on initialization: (a) Random delay of 0-10s (to avoid interference from simultaneous scanning by multiple hosts).

[0077] (b) Scan all frequency points and detect background RSSI.

[0078] (c) Execute the adjacent frequency avoidance algorithm (avoid strong interference frequency points).

[0079] (d) Lock the operating frequency.

[0080] (e) The host synchronizes 4G / 5G base station signals and generates a local clock reference with a 10ms period.

[0081] (f) The host controls FSK to transmit signals at a fixed power in the first 5ms based on a 10ms cycle.

[0082] (2) Slave access control: The master can only connect to one slave at a time. When a second slave requests to connect: (a) Determine if the current slave's max_RSSI is greater than the threshold (e.g., -20dBm): If the conditions are met, reject the new slave device connection.

[0083] (b) If the RSSI of the new slave is more than 3dB higher than that of the current slave, unbind the current slave and bind the new slave.

[0084] (c) Otherwise, reject new slave device access.

[0085] (3) Exception handling process: (a) When the same slave connection is rejected 3 times, the "dual slave observation mode" is triggered.

[0086] (b) When the max_RSSI reported by the slave device for 1 hour is less than the threshold, the “Access Denied and Contention Mode” is triggered.

[0087] (4) RSSI management reported by slave devices: Continuously record and update the maximum and minimum values ​​of RSSI reported by all connected slave devices.

[0088] See Figure 5 , the slave device's working process is as follows: The slave device adopts the "strongest signal first" strategy: (1)Power-on initialization: (a)Perform a full-frequency scan (F1 - F5) to detect all master device signals.

[0089] (b)Select the master device with the strongest RSSI (and RSSI ≥ -105dBm) and attempt to connect.

[0090] (c)If the received RSSI < -105dBm, wait for 30s and then perform a full-frequency scan again.

[0091] (2)Connection maintenance: (a)Report the RSSI detected by itself to the master device regularly (per second).

[0092] (b)If the connection is terminated, immediately rescan and attempt to connect to the master device with the strongest signal (RSSI ≥ -105dBm).

[0093] To reduce the probability of selecting the same frequency point due to multiple master devices powering on simultaneously, the master device uses its SN number (or the ID of the MCU) as a random seed to generate a random integer between 0 and 10, and the master device delays the frequency scan time by 0 - 10s accordingly. The process steps for the master device to randomly delay the frequency scan time are as follows: (1)Obtain the ID of the MCU.

[0094] (2)Generate a hash seed.

[0095] (3)Initialize the random number generator.

[0096] (4)Generate a random delay between 0 and 10.

[0097] (5)Convert it to the time base Ticks of Free RTOS.

[0098] (6)Execute the scan delay.

[0099] (7)Perform a frequency scan after the delay ends.

[0100] After the master device scans the frequency points, different strategies are executed according to different interference intensities. The frequency point selection strategy is as follows: (1)Strong interference frequency point (RSSI ≥ -60dBm): Execute the adjacent frequency avoidance strategy.

[0101] (2)General interference frequency point (-95dBm < RSSI < -60dBm): Select the frequency point with the least interference.

[0102] (3) Clean frequency (RSSI ≤ -95dBm): Randomly select a clean frequency.

[0103] See Figure 6 The adjacent frequency avoidance strategy is as follows: When strong RSSI interference is detected at a certain frequency, avoid selecting adjacent frequencies. The adjacent frequency avoidance strategy is as follows: (1) Scan and record the RSSI of each frequency point.

[0104] (2) Mark strong interference frequency points (≥-60dBm) and adjacent frequency points as "avoid selection".

[0105] (3) Select the frequency with the lowest RSSI from the non-"avoid selection" frequency points.

[0106] (4) If all frequencies are marked as “avoid selection”, then select the frequency with the lowest RSSI.

[0107] To further reduce the probability of hosts selecting the same frequency, each host uses its serial number (or MCU ID) as a random seed to generate a random integer from 1 to 5 (corresponding to 5 frequency points), and then selects the corresponding frequency point. The steps of the random frequency point selection mechanism are as follows: (1) After the host starts up, it scans all frequency points and records the background RSSI of each frequency point.

[0108] (2) Based on the background RSSI, the frequency points are divided into two groups: 1) Clean frequency points: Frequency points where the background RSSI is below a certain threshold (e.g., -95dBm).

[0109] 2) Interference frequency points: Frequency points where the background RSSI is higher than this threshold.

[0110] (3) If a clean frequency point exists, then randomly select one of the clean frequency points as the working frequency point.

[0111] (4) If there is no clean frequency, select the frequency with the lowest background RSSI among all frequencies, and randomly select one of these frequencies with the lowest RSSI.

[0112] See Figure 7 The new slave device contention access strategy is as follows: (1) When a new slave requests access, the master obtains the current slave's historical max_RSSI.

[0113] (2) If max_RSSI > threshold (e.g. -20dBm), then the access request of the new slave is rejected.

[0114] (3) Otherwise, compare the RSSI of the new slave with the RSSI of the current slave. If the RSSI of the new slave device is more than 3dB higher than that of the current slave device, unbind the current slave device and bind the new slave device.

[0115] Otherwise, refuse new slave device access.

[0116] See Figure 8 The dual-slave observation mode is as follows: If the same slave device is rejected multiple times (e.g., 3 times) in a row, the master device triggers the dual-slave observation mode, allowing two slave devices to connect simultaneously. Within the preset observation window, the master device collects the RSSI data reported by the two slave devices, records and updates their maximum RSSI, minimum RSSI, and dynamic range (ΔRSSI). After the observation is completed, the master device retains the slave device in this hoistway and removes the slave device from the hoistway, based on the decision rule of maximum RSSI first, minimum RSSI second, and dynamic range third.

[0117] (1) If the same slave device is rejected multiple times (e.g., 3 times) in a row, the master device will trigger the dual slave device observation mode.

[0118] (2) The master maintains both slaves connected at the same time.

[0119] (3) The host selects the observation window type based on ΔRSSI stability: 1) It has stabilized. Start the adaptive observation window.

[0120] 2) If unstable, open a fixed observation window (e.g., 3 minutes).

[0121] (4) The RSSI values ​​reported by the two slave devices are continuously collected within the observation window.

[0122] (5) Record and update the maximum RSSI value, minimum RSSI value, and dynamic range (ΔRSSI).

[0123] (6) After the observation is completed, the decision is made to retain the slave unit in this wellbore: 1) If max_RSSI1 - max_RSSI2 > threshold (e.g., threshold = 5dB), select the slave with the larger maximum RSSI.

[0124] 2) Otherwise, if min_RSSI1-min_RSS2>th threshold (e.g., threshold=5dB), select the slave with the larger minimum RSSI.

[0125] 3) Otherwise, if ΔRSSI1-ΔRSSI2 > threshold (e.g., threshold = 10dB), select the slave with the larger ΔRSSI.

[0126] 4) Otherwise, keep the original slave connection and disconnect the new slave connection.

[0127] (7) Disarm the slave machine that is not in this shaft and retain the slave machine in this shaft.

[0128] The higher the hoistway, the longer the car travels, and the greater the range of RSSI variation (ΔRSSI). Therefore, the range of RSSI variation can be used to indirectly reflect the building's floor height. The process steps for the dynamic adjustment strategy of the observation window are as follows: (1) After the slave device is connected, it reports RSSI to the master device every 1 second.

[0129] (2) The host continuously updates the maximum and minimum values ​​of RSSI reported by the slave.

[0130] (3) Calculate the initial ΔRSSI = max_RSSI – min_RSSI.

[0131] (4) When the change in Δ value is less than 3dB after 10 consecutive updates, it is considered to be stable.

[0132] (5) During operation, the host continuously updates the ΔRSSI value.

[0133] Based on the obtained ΔRSSI, the total floor height of the building is estimated by referring to Table 1, and the observation window is dynamically adjusted. Table 1 is as follows: Table 1

[0134] See Figure 9 The following are prohibited access and competition modes: This mode is triggered when the master unit suspects that the slave unit is not in the same shaft (max_RSSI < threshold for 1 hour): (1) The host initializes and deactivates the counter Count=0; (2) Continuously monitor the RSSI reported by the slave device and record the maximum value max_RSSI.

[0135] (3) If max_RSSI > threshold (-20dBm), then exit max_RSSI monitoring.

[0136] (4) Check if max_RSSI remains below the threshold (e.g., -20dBm) for 1 hour: Condition met: Disconnect the current slave device and increment Count by 1.

[0137] (5) Immediately activate a 30-second "No Access and Contention Window": Reject all access requests from the original slave device.

[0138] Listen for other new slave device connection requests.

[0139] (6) Within 30 seconds: A new slave device has been connected: Bind the new slave device, Count=0. If the indicator light alarms, clear it.

[0140] No new slave device connected: Window ends.

[0141] (7) Check Count: Count<3: Allow the original slave device to reconnect.

[0142] Count≥3: Count=0, allowing the original slave device to connect, indicator light alarm.

[0143] If the host detects three consecutive communication failures, it will actively execute a frequency hopping algorithm, select a new communication frequency, and then transmit signals on the new frequency. Since the slave device cannot receive signals from the host, it will trigger a rescanning process to find the host's new frequency. The process of the anti-interference frequency hopping strategy is as follows: (1) The host detects three consecutive communication failures with the slave.

[0144] (2) The host turns on the receiver and scans all frequency points.

[0145] (3) Select the new frequency F_new with the least interference according to the strategy of "avoiding adjacent frequencies" or "selecting the cleanest frequency".

[0146] (4) The host switches the operating frequency to F_new and immediately transmits the signal at maximum power.

[0147] (5) The slave device cannot receive the signal from the master device, triggering a communication timeout.

[0148] (6) The slave device enters the rescanning process and rediscovers the host signal on the F_new frequency point.

[0149] (7) The slave device initiates an access request, the master device accepts it, and the two parties resume normal communication on the new frequency.

[0150] See Figure 10 Slave dynamic power control adjusts its uplink transmit power based on the downlink signal strength received by the slave (i.e., the RSSI of the signal transmitted by the master at the slave end). It reduces transmit power when the signal is strong and increases transmit power when the signal is weak.

[0151] (1) The power mapping table established by the slave device is shown in Table 2: Table 2

[0152] (2) The slave device measures the downlink RSSI.

[0153] (3) Obtain the required uplink power by looking up the table based on the downlink RSSI.

[0154] (4) Adjust the uplink transmission power of the slave device.

[0155] (5) If communication fails three times in a row, the transmission power will be adjusted to the maximum.

[0156] See Figure 11 In multiple adjacent elevator shafts, if the host devices use the same frequency for FSK communication, severe co-channel interference will occur, leading to a degraded communication quality. The TDD frame structure of 4G / 5G base stations is used to synchronize the communication timing of the host and slave devices within the elevator coverage system, thereby avoiding transmit / receive conflicts. Specifically, the transmit and receive periods of FSK communication are aligned with the TDD frames of the base station, ensuring that all hosts transmit and receive at the same time. The synchronization strategy based on 4G / 5G TDD frames is as follows: (1) The host receives the downlink signal from the base station through the 4G / 5G synchronization detection module.

[0157] (2) Detect the frame start position (demodulate the PSS / SSS synchronization signal) and generate a local clock reference with a 10ms period.

[0158] (3) The host controls the FSK to transmit in the first 5ms and receive in the last 5ms based on a 10ms period.

[0159] (4) The master sends a synchronization signal to the slave at a period of 10ms.

[0160] (5) The slave device receives the synchronization signal sent by the master device through the built-in synchronization detection module.

[0161] (6) Detect the frame start position (demodulate the synchronization signal) and generate a local clock reference with a 10ms period.

[0162] (7) The slave device controls FSK to receive in the first 5ms and transmit in the last 5ms based on a 10ms period.

[0163] See Figure 12 The FSK communication transmission and reception time of all hosts in the shaft is aligned with the TDD frame of the base station, ensuring that all hosts transmit and receive at the same time, thus solving the interference problem of hosts in multiple elevator shafts.

[0164] To overcome the effects of instantaneous fading of wireless signals and environmental noise, and to improve the stability and reliability of RSSI measurements, thereby ensuring the accuracy of subsequent wellbore identification decisions, this system preprocesses the raw RSSI data collected.

[0165] In a preferred embodiment of the present invention, the RSSI signal preprocessing is performed using a moving average filter algorithm. The specific implementation steps are as follows: (1) Data buffer initialization: Open a circular queue buffer of length N (e.g., N=5) in the slave's memory to store the RSSI values ​​sampled most recently N times, and set the initial value to 0.

[0166] (2) Real-time data update and filtering: (a) A new data sample value RSSI_new is obtained each time.

[0167] (b) Place it at the end of the data, while discarding the oldest data in the data.

[0168] (c) Calculate the arithmetic mean of the current data N data points.

[0169] (d) Use this average value as the current filtered output value RSSI_out. The mathematical formula is:

[0170] in: The oldest data. The latest data.

[0171] (3) Application of filtered data: The RSSI_out value obtained after the above filtering process will be used in all subsequent key decision-making processes, including but not limited to: updating historical extreme values ​​(max_RSSI / min_RSSI), calculating dynamic range (ΔRSSI), triggering contention access decision, and performing feature comparison in dual slave observation mode.

[0172] See Figure 13 During system operation, the host transmits a signal at a fixed power, the slave detects RSSI and reports the RSSI value at 1-second intervals, and the host records and updates the maximum / minimum / ΔRSSI value of the slave's RSSI.

[0173] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0174] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. Furthermore, those skilled in the art will recognize that, based on the ideas of the present invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A RSSI spatial feature-based elevator coverage system automatic pairing method applied to an elevator coverage system comprising a master and a slave, the master being located at the top of the elevator shaft and the slave being located at the top of the car, characterized in that, The method comprises: The slave machine continuously detects and reports the received signal strength indication (RSSI) received from the master machine during vertical movement of the elevator car, to obtain an RSSI record; The master machine forms a spatial fingerprint of the hoistway based on the RSSI record and updates a historical maximum RSSI value max_RSSI, a historical minimum RSSI value min_RSSI, and a dynamic range ΔRSSI of the two values; Under the premise that the master machine only allows one slave machine to be connected at the same time, the master machine performs slave machine identification and pairing decision based on the spatial fingerprint; the decision is based on at least one of the following discriminators: absolute strength discrimination, extreme value discrimination, and dynamic range discrimination, to distinguish between the slave machine of the current hoistway and the slave machine of the adjacent hoistway; The master machine establishes or maintains a connection with the slave machine of the current hoistway accordingly, and triggers disconnection and re-competition for access to complete self-correction when it is determined that the connection is abnormal based on the spatial fingerprint.

2. The RSSI spatial feature based elevator coverage system automatic pairing method according to claim 1, characterized in that, The absolute strength discrimination is that, at any position in the current hoistway, the RSSI received by the slave machine from the master machine of the current hoistway is higher than the RSSI received from the master machine of the adjacent hoistway.

3. The RSSI spatial feature based elevator coverage system automatic pairing method according to claim 1, characterized in that, The extreme value discrimination includes that the max_RSSI recorded when the slave machine of the current hoistway moves to the top is higher than the signal strength of the master machine of the current hoistway received by the slave machine of the adjacent hoistway at the top thereof, and the min_RSSI recorded when the slave machine of the current hoistway moves to the bottom is lower than the signal strength of the master machine of the current hoistway received by the slave machine of the adjacent hoistway at the bottom thereof.

4. The RSSI spatial feature based elevator coverage system automatic pairing method of claim 1, wherein, The ΔRSSI reported by the slave machine of the current hoistway is greater than the RSSI range experienced by the slave machine of the adjacent hoistway when receiving the signal of the master machine of the current hoistway.

5. The RSSI spatial feature based elevator coverage system automatic pairing method according to claim 1, characterized in that, The master machine makes a decision on access of a new slave machine in accordance with the principle of priority of the strongest signal: when a new slave machine requests access, if the max_RSSI of the currently connected slave machine is higher than a preset threshold, the master machine rejects the access of the new slave machine; Otherwise, if the current RSSI of the new slave machine exceeds a preset threshold relative to the recently reported RSSI of the current slave machine, the master machine disconnects the current connection and binds the new slave machine, otherwise, the master machine rejects the access of the new slave machine.

6. The RSSI spatial feature based elevator coverage system automatic pairing method according to claim 1, characterized in that, When the same slave machine is continuously rejected for access for a preset number of times, the master machine triggers a double slave machine observation mode, allowing two slave machines to be connected at the same time and collecting their respective RSSIs within an observation window, calculating their respective max_RSSI, min_RSSI, and ΔRSSI, and making a decision in the following priority: preferentially selecting the one with a larger max_RSSI; if they are equivalent, selecting the one with a larger min_RSSI; if they are still equivalent, selecting the one with a larger ΔRSSI; otherwise, maintaining the connection of the original slave machine.

7. The RSSI spatial feature based elevator coverage system automatic pairing method according to claim 6, characterized in that, The observation window is adaptively set: the master machine dynamically sets the observation time length according to the stability and value of ΔRSSI, to match the complete motion cycle data collection of different hoistway heights.

8. The RSSI spatial feature based elevator coverage system automatic pairing method according to claim 1, characterized in that, The master machine performs a distributed non-cooperative frequency point self-distribution mechanism to select a working frequency point, specifically including: generating a random delay with a unique hardware ID as a random seed after power-on to stagger the frequency point scanning time; scanning the background RSSI of available frequency points and performing adjacent frequency avoidance, marking strong interference frequency points and their adjacent frequency points as avoided; selecting the frequency point with the lowest background RSSI from the non-avoided frequency points; when there are multiple clean frequency points, randomly selecting one from them.

9. The RSSI spatial feature based elevator coverage system automatic pairing method according to claim 1, characterized in that, When the master detects that the continuous communication with the slave fails for a preset number of times, the master executes a master-led anti-interference frequency hopping mechanism: re-scans the available frequency points and selects a new working frequency point with less interference to switch transmission, so that the slave automatically addresses through the re-scanning process and resumes communication at the new frequency point.

10. The RSSI spatial feature based elevator coverage system automatic pairing method according to claim 1, characterized in that, The slave controls the uplink transmission power adaptively based on the received downlink RSSI, divides the downlink RSSI into multiple intervals and maps it to corresponding transmission power levels, reduces the power when the signal is strong, increases the power when the signal is weak, and switches to the maximum power when the continuous communication fails.

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