Wireless talkback and smart home integrated system for smart community and control method thereof

Abstract

The invention discloses a wireless talkback and smart home integrated system for a smart cell and a control method thereof, an ad hoc network wireless local area network is constructed through an ESP-WIFI-MESH protocol, and the wireless talkback and smart home integrated system comprises an outdoor host, a wireless repeater and an indoor extension. The system adopts mesh topology to realize multi-hop redundant transmission, automatically selects an optimal path and ensures communication reliability; dynamic priority scheduling of alarm, voice, video and smart home control data is supported, wherein the alarm signal is the highest priority. The indoor extension set is integrated with a multi-protocol gateway and is compatible with Wi-Fi / Bluetooth / ZigBee equipment, so that wireless access of smart home such as water, electricity and meters is realized. The community integrated management platform monitors the state of equipment in a centralized manner, and supports remote management, anomaly detection and emergency linkage. The system has the advantages of being low in cost, easy to expand, short in construction period and the like, the problems of complex wiring, signal shielding and the like in old community reconstruction are effectively solved, and community security and protection intelligence is improved.

Description

Technical Field

[0001] The present invention relates to the field of intercom technology, and particularly to a wireless intercom and smart home integration system for intelligent communities and its control method. Background Art

[0002] As the core infrastructure of intelligent communities, building intercom systems have long relied on traditional wired or basic wireless technologies (such as WiFi, Bluetooth), but face significant challenges in practical applications.

[0003] Traditional wired intercom systems need to deploy audio-video lines, power lines, and control lines separately for each household, and the material cost accounts for more than 40% of the total investment. For example, Chinese Patent Publication No. CN110247804B discloses a system for a household to obtain community shared device information. By establishing a physical link of a standard Ethernet between systems in a smart community, a community information integration system, and an Internet of Things gateway, it solves the problem that residents cannot effectively obtain relevant information about shared devices in the smart community; without increasing community hardware resources and network fees, it can provide smart community shared device services to residents, bringing an integrated smart experience of the smart community and home after the residents move in. However, the above system proposes to integrate community shared device information through an Ethernet architecture (core, aggregation, access switches), which relies on multiple network devices, has high hardware costs, and a long construction period (2-3 weeks per building). If smart home devices use wired protocols such as RS-485 and KNX, dedicated communication lines need to be additionally laid, resulting in a 30%-50% increase in construction costs.

[0004] Chinese Patent Publication No. CN205921681U discloses an upgraded architecture for a building intercom system in old residential areas based on wireless technology. Its unit entrance machine is connected to a signal conversion device by wire; the wireless signal repeater is wirelessly connected to the signal conversion device; a small wireless local area network is formed among the signal conversion device, the wireless signal repeater, and the indoor wireless intercom terminal, and it cooperates with the unit entrance machine and the indoor machine to form a new networking method. This networking method can enable the indoor machines that are not faulty to communicate in the traditional wired intercom manner; while the faulty indoor machines communicate in a wireless manner, so as to improve on the basis of the original system and utilize the original system resources to restore the intercom function. However, in the renovation of old residential areas, it is necessary to replace faulty devices with wireless modules. If the number of faulty devices is large, the hardware cost will increase sharply, and dense WiFi signals are likely to cause channel competition, further deteriorating communication stability; moreover, it adopts a hybrid wired / wireless architecture, allowing some indoor machines to be wirelessly replaced, but its star topology relies on a single access point (AP). Once the repeater fails, it needs to be manually replaced and re-networked, with low maintenance efficiency. Separate wiring for independent subsystems (such as access control, security, smart home) leads to redundant lines and high management complexity, making it difficult to achieve unified control.

[0005] Chinese Patent CN108924492A discloses a smart visual access control system based on Wi-Fi networking, but it relies on a third-party cloud server, posing data security risks; wireless signals are vulnerable to building structures and electromagnetic interference, resulting in unstable communication. In addition, the method of using a cloud management server usually requires paying fees to the corresponding third-party operator, and due to third-party management, it is prone to information leakage.

[0006] Therefore, there is an urgent need for a wireless intercom system that supports self-organizing network, high scalability, short construction period, and low cost to adapt to the renovation needs of old and smart communities. Summary of the Invention

[0007] The present invention overcomes the above-mentioned deficiencies in the technology and provides a configuration method and a control method for intelligent devices.

[0008] To achieve the above object, the present invention adopts the following technical solutions:

[0009] The first aspect of the embodiment of the present invention discloses a wireless intercom and smart home integration system for smart communities, including:

[0010] Multiple outdoor wireless digital hosts 100, each including a first ESP wireless module 101, a first Wi-Fi module 102, and a main control CPU module 103; the first ESP wireless module 101 and the first Wi-Fi module 102 are respectively connected to the main control CPU module 103 in an interactive manner;

[0011] Multiple wireless repeaters 200, each including a second ESP wireless module 201 and a second Wi-Fi module 202;

[0012] Multiple wireless indoor extension phones 300, each including a third ESP wireless module 301 and a smart home access module 310; the first ESP wireless module 101, the second ESP wireless module 201, and the third ESP wireless module 301 are all wireless communication modules that support the Mesh protocol; the outdoor wireless digital hosts 100, the multiple wireless repeaters 200, and the multiple wireless indoor extension phones 300 are wirelessly connected through their respective ESP wireless modules and self-organize into a wireless local area network; the outdoor wireless digital hosts 100 of different buildings communicate with each other through the existing local area network in the community; among them, the smart home access module 310 of each wireless indoor extension phone 300 is connected to the smart home devices in the household through wired or wireless means.

[0013] Preferably, the third ESP wireless module 301 is a wireless communication module that supports Wi-Fi / Bluetooth dual-mode communication;

[0014] The smart home access module 310 includes:

[0015] A multi-protocol gateway 3101 that supports Wi-Fi / Bluetooth / ZigBee protocols;

[0016] A smart home interface 3102 that incorporates the multi-protocol gateway 3101 and is used for wirelessly connecting to smart water meters, electricity meters, gas sensors, and third-party smart home devices, and automatically adapting to the device communication protocols;

[0017] An expansion slot 3103 that provides a USB-C interface for plugging in and connecting smart home devices.

[0018] Preferably, each outdoor wireless digital host 100 further includes: a memory 104, a first audio input module 105, a first audio output module 106, a Flash memory 107, a first digital-to-analog and analog-to-digital conversion module 108, a lock control module 109, a liquid crystal display screen 110, a numeric keypad 111, and a first power supply module 112 that powers each module of the outdoor wireless digital host 100. The main control CPU module 103 is also respectively interconnected with the memory 104, the Flash memory 107, the first digital-to-analog and analog-to-digital conversion module 108, the lock control module 109, the liquid crystal display screen 110, and the numeric keypad 111. The first ESP wireless module 101 sends voice signal data packets to the wireless indoor extension 300 or receives intercom signals from the wireless indoor extension 300 through multiple wireless repeaters 200. The first digital-to-analog and analog-to-digital conversion module 108 is electrically connected to the first audio input module 105 and the first audio output module 106 respectively. The lock control module 109 is used to receive the unlocking instruction sent by the main control CPU module 103 for unlocking and locking. Each wireless indoor extension 300 further includes: a second audio input module 302, a second audio output module 303, a second digital-to-analog and analog-to-digital conversion module 304, a key module 305, and a third power supply module 306 that powers each module of the wireless indoor extension 300. The second ESP wireless module 301 sends intercom signals to the outdoor wireless digital host 100 or receives voice signal data packets from the wireless indoor extension 300 through multiple wireless repeaters 200. The second digital-to-analog and analog-to-digital conversion module 304 is electrically connected to the second audio input module 302 and the second audio output module 303 respectively.

[0019] Preferably, it further includes: a community integrated management platform 400, which is set up in the property center and is used for monitoring the community status;

[0020] Each outdoor wireless digital host 100 communicates with the community integrated management platform 400 through the community local area network.

[0021] Each outdoor wireless digital host 100 further includes a first emergency alarm module 113, an Ethernet communication module 114, a camera module 115, a face recognition module 116, an NFC module 117, and a fingerprint recognition module 118, which are respectively interconnected with the main control CPU module 103;

[0022] The first emergency alarm module 113 includes a first alarm button 1131. When it is detected that the first alarm button 1131 is continuously pressed for more than a preset second threshold, an alarm instruction is triggered; the alarm instruction is sent to the local area network of the community through the Ethernet communication module 114 or the first Wi-Fi module 102, and then forwarded to the community integrated management platform 400;

[0023] Each wireless indoor extension 300 further includes a second emergency alarm module 307. The second emergency alarm module 307 includes a second alarm button 3071. When it is detected that the second alarm button 3071 is continuously pressed for more than a preset second threshold, an alarm instruction is triggered; the alarm instruction is sent to the outdoor wireless digital host 100 through the self-organized wireless local area network of the third ESP wireless module 301, and then forwarded to the community integrated management platform 400 by the outdoor wireless digital host 100 through the local area network of the community.

[0024] Preferably, the second emergency alarm module 307 further includes:

[0025] Wearable device linkage end 3072: It is a port of the smart home interface 3102, wirelessly connected to the user's wearable device through the Bluetooth function of the multi-protocol gateway 3101, receives a fall signal and triggers an alarm instruction;

[0026] Environmental perception unit 3073: It is used to detect abnormal sounds through the second audio input module 302 of the wireless indoor extension 300;

[0027] Preset contact call unit 3074: It is used to first transmit to the outdoor wireless digital host 100 through the self-organized wireless local area network after the alarm instruction is triggered, and then transmit to the local area network of the community to initiate a voice call to the preset contact;

[0028] Camera linkage unit 3075: It is used to wirelessly control the indoor camera to start recording after the alarm instruction is triggered through the smart home access module 310, and transmit the real-time picture to the community integrated management platform 400;

[0029] Abnormal water and electricity usage analysis unit 3076: It is used to judge abnormal water and electricity usage and trigger a hierarchical alarm according to the daily water and electricity usage patterns of the household.

[0030] Preferably, the abnormal water and electricity usage analysis unit 3076 includes:

[0031] The water and electricity behavior model library 30761 is used to store the baseline water / electricity usage patterns of different households;

[0032] The anomaly determination module 30762 is used to trigger a hierarchical alarm action by comparing real-time data with the baseline;

[0033] The anomaly determination module 30762 includes:

[0034] The water usage anomaly determination and warning unit 307621: If the continuous non-water usage duration ≥ 12 hours, it is determined that there is a water usage anomaly, and a pop-up warning is sent to the property platform;

[0035] The electricity usage anomaly determination and warning unit 307622: If the sudden increase in night electricity consumption ≥ 200% and lasts ≥ 30 minutes, it is determined that there is an electricity usage anomaly, and a text message alarm is sent to the emergency contact;

[0036] The linked alarm unit 307623: After determining an anomaly, the community comprehensive management platform 400 makes a call to the indoor wireless extension 300 in the area. If there is no response within the preset threshold time, an alarm instruction is triggered, and the preset contact call unit 3074 is linked to automatically call the preset emergency contact and the linked camera unit 3075 monitors the indoor picture of the household.

[0037] Preferably, the community comprehensive management platform 400 includes:

[0038] The access control management unit 401 is used to store the face feature templates, mobile phone numbers, unlocking passwords, and original access card information of the households;

[0039] The remote unlocking unit 402 is used to send an unlocking instruction to the outdoor wireless digital host 100 remotely;

[0040] The emergency alarm processing unit 403 is used to receive the alarm instruction sent by the outdoor wireless digital host 100 in real time and issue an alarm, and to obtain the target location where the alarm instruction locates the alarm and control the camera picture in the area where the target location is located on the monitoring display screen to be enlarged and displayed;

[0041] The abnormal capture unit 404 is used to receive the visitor capture pictures taken by the camera module 115, and is configured to: identify whether the face is that of a registered person through the lightweight YOLO algorithm. If it is determined that it is a non-registered person, an alarm is issued to remind the property personnel;

[0042] The household picture monitoring unit 405 is communicatively connected to the cameras in each household's interior, receives the real-time pictures transmitted by the camera linkage unit 3075 and displays them.

[0043] Preferably, each wireless repeater 200 further includes: a dynamic IP connection module 203 responsible for dynamically allocating IP addresses, and a second power supply module 204 for powering each module of the wireless repeater 200; wherein, the dynamic IP connection module 203 includes:

[0044] A processor chip 2031 that supports the DHCP protocol, which is connected to the second ESP module 201 and is used to start the DHCP protocol when detecting that a new wireless indoor extension 300 is accessed;

[0045] An IP address memory 2032, which is connected to the processor chip 2031 and is used to store an IP address pool that can be allocated;

[0046] A network interface controller 2033, which is used to communicate with the upper-level node through Ethernet.

[0047] A second aspect of the embodiments of the present invention discloses a control method for a wireless intercom and smart home integration system for an intelligent community, which is applied to the wireless intercom and smart home integration system described in the first aspect, and includes the following steps:

[0048] When a user presses the alarm button of the outdoor wireless digital host or the alarm button of the wireless indoor extension, an alarm instruction is generated and encrypted into an alarm packet, a priority marking instruction is triggered, and the alarm packet is marked as the first priority, and the first priority is the highest priority;

[0049] When a visitor initiates a call through the outdoor wireless digital host, voice data of an intercom call signal is generated and encapsulated into a voice data packet, a priority marking instruction is triggered, and the voice data packet is marked as the second priority; if the outdoor wireless digital host is configured with a camera, video stream data is synchronously generated and encapsulated into a video data packet, and a priority marking instruction is triggered, and the video data packet is marked as the third priority;

[0050] When a user presses the intercom button of the wireless indoor extension, voice data and video stream data of an intercom call signal are generated, respectively encapsulated into a voice data packet and a video data packet, a priority marking instruction is triggered, and the voice data packet is marked as the second priority, and the video data packet is marked as the third priority;

[0051] When a user controls a smart home device through the wireless indoor extension / remote client, control data of a control signal is generated, packaged into a control data packet, a priority marking instruction is triggered, and the control data packet is marked as the fourth priority;

[0052] The alarm packet, voice data packet, video data packet, and control data packet are multi-hop transmitted through multiple wireless repeaters, and dynamic scheduling is performed according to the priority level during the transmission process to ensure that the first-priority data is preferentially transmitted;

[0053] After receiving the voice data packet and the video data packet, the target wireless indoor extension decodes them. If the decoding is successful, it triggers a ring and displays a picture, and the household can perform voice visual intercom or remote unlocking operations through the extension;

[0054] The wireless intercom and smart home integration system processes data transmission in the order of the first priority, the second priority, the third priority, and the fourth priority, where the alarm packet preempts the voice, video, and control data channels.

[0055] Preferably, in the alarm packet data transmission path, the alarm packet is encapsulated using the AES encryption algorithm, marked in the packet header as having the highest transmission priority higher than the voice data packet, and executes the highest-level transmission mechanism through the self-formed wireless local area network to ensure that it preferentially obtains channel resources, and the encryption process does not increase additional transmission latency;

[0056] In the voice packet data transmission path, the UDP protocol is used to transmit the voice data packet, and the dynamic routing optimization algorithm is combined to monitor the network topology in real time to avoid the optimal path of high-load nodes or interference areas;

[0057] In the video packet data transmission path, the video data is compressed by H.265 encoding, and a low-latency mode is configured;

[0058] The highest-level transmission mechanism includes:

[0059] When an alarm packet is detected, the current non-emergency data transmission is immediately interrupted, and dedicated channel resources are reserved to ensure real-time performance;

[0060] Select the path with the highest score as the transmission path according to the first transmission path scoring formula;

[0061] The CSMA / CA algorithm is used, and the backoff window of the alarm packet is fixed at 2 time slots;

[0062] Among them, the first transmission path scoring formula is:

[0063] The first path score = RSS I × M + (1 / number of hops) × N; where, RSS I represents the signal strength, M represents the weight ratio of the influence of RSS I, and N represents the weight ratio of the influence of the number of hops;

[0064] Among them, 0.4 ≤ M ≤ 0.8, 0.2 ≤ N ≤ 0.6, and M + N = 1 is satisfied.

[0065] The implementation steps of the dynamic routing optimization algorithm include:

[0066] Collect the RSS I, packet loss rate, and delay time of each path in real time;

[0067] Select the path with the highest score as the transmission path according to the second transmission path scoring formula;

[0068] Among them, the second transmission path scoring formula is:

[0069] The second path score = A1 × RSSI + A2 × (1 / delay time) + A3 × (1 - packet loss rate), where RSSI represents the signal strength, A1 represents the weight ratio of the RSSI influence, A2 represents the weight ratio of the delay data influence, A3 represents the weight ratio of the packet loss rate influence, A1 + A2 + A3 = 1, and A1 > A2 > A3;

[0070] Set up a path switching mechanism. If the current path score drops by more than the preset threshold B, and the standby path score is higher than the preset percentage value C, then switch the path within the preset T time, where B takes 15 - 30%, C takes 20 - 30%, and T takes 5 - 15 ms.

[0071] Compared with the prior art, the embodiments of the present invention have the following beneficial effects:

[0072] 1. In this case, a wireless local area network based on the ESP-WIFI-MESH protocol is constructed through the ESP wireless module, and a multi-hop transmission path is realized by adopting a mesh topology structure to form a redundant network. Even if a single node's signal attenuates or fails, the system can automatically select other nodes with strong signals for relaying communication to ensure that global communication is not interrupted, significantly improving the network reliability, especially adapting to the signal shielding problem caused by the complex building structure in old communities. Moreover, the wireless indoor extension only integrates the ESP module and omits the Wi-Fi module, so as to reduce the hardware cost, and at the same time avoid the high standby power consumption generated by the Wi-Fi module of the extension, significantly reducing the long-term operation energy consumption; and there will be no situation of channel competition with other indoor Wi-Fi devices, ensuring communication stability. The core intercom function is guaranteed by a dedicated MESH network, and the extended functions are concentrated on the host and the wireless repeater. On the one hand, it avoids the direct exposure of the extension to the public network, and on the other hand, it avoids the high cost and high power consumption defects of the full Wi-Fi solution. Moreover, the Wi-Fi modules of the host and the wireless repeater can access the external network, support firewalls and data encryption, and realize remote management and docking with the cloud platform, taking into account both security and flexibility. The MESH network supports multi-level relay expansion, and new extensions can automatically access the nearest relay node and complete networking without complex configuration. Combining the design of deploying wireless repeaters every 3 floors in the corridor not only adapts to the scattered building structure in old communities but also supports the future expansion of the number of extensions, solving the pain point of the poor scalability of the traditional wiring system.

[0073] 2. The community integrated management platform in this case centrally monitors all host devices through the local area network, supports remote fault troubleshooting, configuration updates, and status analysis; moreover, it can be deployed in combination with the existing property monitoring network to avoid duplicate wiring, reduce operation and maintenance costs, and improve management efficiency; the system can seamlessly access the existing local area network in the community (such as the monitoring network), utilize the existing network line resources, reduce the network reconstruction investment in the renovation of old communities, and accelerate the project implementation.

[0074] 3. The indoor wireless extension in this case integrates a smart home access module and directly wirelessly connects to water and electricity meters through the multi-protocol gateway built in it, without the need to damage the wall for wiring, shortening the deployment time. Moreover, a single gateway supports Wi-Fi / Bluetooth / ZigBee, solving the problem of fragmented protocols for smart home devices and reducing the user access threshold. In contrast, old buildings need to deploy an RS-485 bus to connect water and electricity meters, simplifying the construction complexity and reducing costs.

[0075] 4. In this case, the alarm instruction is marked as the first priority, which can preempt the voice / video channel to ensure the emergency signal is transmitted without delay, so that in the event of a sudden security incident, the alarm data can reach the property or household terminal preferentially through multi-hop relay, shortening the response time. Moreover, the alarm packet is encrypted to prevent information leakage and enhance the privacy protection ability of the weak security links in old communities. At the same time, in this case, voice (the second priority) is prior to video (the third priority), and video (the third priority) is prior to smart home device control (the fourth priority), balancing the real-time interaction requirements and bandwidth resources, so that when a visitor calls, the voice can be connected immediately, the video stream is transmitted later, and the visual intercom is prioritized before transmitting the control instruction data to avoid network congestion. In this way, the system dynamically schedules the transmission order according to the priority, ensuring the stable transmission of key data (such as alarms and voices) and improving the communication efficiency in the old community environment with limited bandwidth. BRIEF DESCRIPTION OF THE DRAWINGS

[0076] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings required in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0077] Figure 1 It is a schematic diagram of the architecture of the wireless building intercom system in this case.

[0078] Figure 2 It is a block diagram of the structure of a single outdoor wireless digital host in this case.

[0079] Figure 3 It is a block diagram of the structure of a single wireless repeater in this case.

[0080] Figure 4 It is the structural block diagram of a single wireless indoor extension in this case.

[0081] Figure 5 It is the structural block diagram of the second emergency alarm module.

[0082] Figure 6 It is the structural block diagram of the community integrated management platform. Specific implementation manners

[0083] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0084] It should be noted that the terms "first", "second", "third", "fourth", etc. in the specification and claims of the present invention are used to distinguish different objects, rather than to describe a specific order. The terms "including" and "having" in the embodiments of the present invention and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device that includes a series of steps or units does not necessarily have to be limited to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0085] Embodiment 1

[0086] As Figures 1-6 shown, a wireless intercom and smart home integration system for an intelligent community and its control method include: an outdoor wireless digital host 100, a plurality of wireless repeaters 200 and a plurality of wireless indoor extensions 300. The three are wirelessly connected through their respective ESP wireless modules and self-constitute a wireless local area network. The first ESP wireless module 101, the second ESP wireless module 201, and the third ESP wireless module 301 are all wireless communication modules that support the Mesh protocol; the outdoor wireless digital host 100, the plurality of wireless repeaters 200 and the plurality of wireless indoor extensions 300 are wirelessly connected through their respective ESP wireless modules and self-constitute a wireless local area network based on the ESP-WIFI-MESH protocol;

[0087] The outdoor wireless digital hosts 100 of different buildings communicate with each other through the community local area network. The community local area network can be the local area network of the existing monitoring system in the community or the existing community local area network.

[0088] As Figure 2As shown in the figure, the outdoor wireless host 100 is fixedly installed on the outer side of the door frame at the entrance of the building unit. It integrates a first ESP wireless module 101, a first WiFi module 102, a main control CPU module 103, a memory 104, a first audio input module 105, a first audio output module 106, a Flash memory 107, a first digital-to-analog and analog-to-digital conversion module 108, a lock control module 109, a liquid crystal display screen 110, a numeric keypad 111, and a first power supply module 112 for powering each module of the outdoor wireless digital host 100. The memory 104 is connected to the main control CPU module 101 through a DDR4 interface and is used to cache audio and video data; the Flash memory 107 is connected to the main control CPU module 103 through an eMMC bus and is used to store firmware programs; the first audio input module 105 is used to input voice signals, which may specifically include an audio input interface and a microphone; the first audio output module 106 is used to output voice signals, which may specifically include an audio output interface and a speaker; the first digital-to-analog and analog-to-digital conversion module 108 is respectively connected to the first audio input module 105 and the first audio output module 106 and is used to realize the conversion between analog voice signals and digital signals; the lock control module 109 is connected to the main control CPU module 103 through a relay inside it and is used to receive unlocking instructions and control the on / off of the electromagnetic lock. The liquid crystal display screen 110 and the numeric keypad 111 are respectively connected to the main control CPU module 103, facilitating users to view and operate the buttons for intercom. Specifically, during implementation, the first ESP wireless module 101 sends voice signal data packets to the wireless indoor extension 300 through multiple wireless repeaters 200 or receives intercom signals from the wireless indoor extension 300.

[0089] Multiple wireless repeaters 200 are fixedly installed on the wall of the corridor shaft, with one wireless repeater 200 set every three floors. Each wireless repeater 200 includes:

[0090] A second ESP wireless module 201: Supports the ESP-WIFI-MESH protocol and is responsible for Mesh network communication.

[0091] A second WiFi module 202: Used to connect to the Internet, can be directly connected to existing WiFi devices such as mobile phones and tablets as an extended function to provide flexible access for the user side, and can also be connected to an external cloud platform or monitoring device. At the same time, the second WiFi module 202 can be uniformly connected to the external network with the first WiFi module 103, facilitating the implementation of security measures such as firewalls and data encryption to avoid the risk of the extension being directly exposed to the public network.

[0092] Each wireless indoor extension 300 includes:

[0093] The third ESP wireless module 301, the second audio input module 302, the second audio output module 303, the second digital-to-analog and analog-to-digital conversion module 304, the button module 305, the smart home access module 310, and the third power supply module 306 that powers each module of the wireless indoor extension 300; the third ESP wireless module 301 receives voice signal data packets from the outdoor wireless digital host 100 through the wireless repeater 200 or sends an intercom signal to the outdoor wireless digital host 100 through the wireless repeater 200;

[0094] The second digital-to-analog and analog-to-digital conversion module 304 is electrically connected to the second audio output module 303, and the voice signal after digital-to-analog conversion is played through the speaker (such as a horn) of the second audio output module 303; the second digital-to-analog and analog-to-digital conversion module 304 is also electrically connected to the second audio input module 302, and is used to perform analog-to-digital conversion on the intercom audio signal received from the microphone of the second audio input module 302 and send it to the outdoor wireless digital host 100;

[0095] The smart home access module 310 includes:

[0096] A multi-protocol gateway 3101 that supports Wi-Fi / Bluetooth / ZigBee protocols; specifically, a gateway of model DSGW-210 can be used.

[0097] A smart home interface 3102 that incorporates the multi-protocol gateway 3101 and can be directly connected to a smart water meter, an electric meter, a gas sensor, or other smart electrical devices without additional wiring;

[0098] An expansion slot 3103 that provides a USB-C interface and supports plug-and-play IoT devices such as temperature and humidity sensors and smart sockets. Specifically, in implementation, the smart water meter accesses the gateway through the ZigBee protocol, and the smart socket is bound through the BLE protocol. The user can insert a USB-C temperature and humidity sensor into the expansion slot 3103, and the wireless indoor extension automatically identifies the device ID and uploads the data to the cloud. In this way, the water and electricity meters can be directly connected to the system through the gateway built into the wireless extension, eliminating the need for in-house communication line deployment. The household can bind third-party devices such as Xiaomi smart sockets and Huawei sensors through the wireless indoor extension or mobile phone, and automatically adapt the protocol.

[0099] Specifically, in implementation, the ESP wireless module can also be referred to as an ESP module; the first and second ESP wireless modules can use chips of the ESP32 series launched by Espressif Systems that support MESH networking, such as ESP32-S2 or ESP32-C6. The third ESP wireless module 301 can use a wireless communication module that supports Wi-Fi / Bluetooth dual-mode communication, specifically, an ESP32-WROOM module can be used.

[0100] The first Wi F i module 102 uses an IoT chip that supports dual-band communications of 2.4GHz and 5GHz; specifically, the QCA4024 chip of Qualcomm's QCA402x series is preferred. In this way, by supporting dual-band communications of 2.4GHz and 5GHz, 2.4GHz has strong penetration and is suitable for environments with many obstacles, while 5GHz has less interference and high bandwidth, which is suitable for high-quality data transmission. This case is aimed at old communities, where there may be many physical obstacles. Dual-band can provide a more flexible connection method. The device can automatically select the optimal frequency band according to signal strength and interference conditions, enhance signal penetration, and balance speed and stability.

[0101] like Figure 1 As shown, the intercom system of this case also includes: a community integrated management platform 400, which is used to monitor the community status; each outdoor wireless digital host 100 and the community integrated management platform 400 communicate with each other through the community local area network. The community integrated management platform 400 is deployed in the computer room of the property management center and connected to the outdoor wireless digital host 100 of each building through a Gigabit Ethernet switch.

[0102] As described above, in this case, a wireless local area network based on the ESP-WIFI-MESH protocol is constructed through the ESP wireless module, adopting a mesh topology to achieve multi-hop transmission paths and form a redundant network. Even if the signal of a single node attenuates or fails, the system can automatically select other nodes with strong signals for relaying communication, ensuring that global communication is not interrupted, significantly improving the network reliability, especially adapting to the signal occlusion problem caused by the complex building structure in old communities. Moreover, the wireless indoor extension only integrates the ESP module and omits the Wi-Fi module, so as to reduce the hardware cost (the cost of the Wi-Fi chip is 2-3 times that of the ESP module), and at the same time avoid the high standby power consumption generated by the Wi-Fi module in the extension (the standby power consumption of the Wi-Fi module is 50-100 mW, and the ESP module is only 10 μW in sleep mode), significantly reducing the long-term operation energy consumption; and there will be no situation of competing with the channels of other Wi-Fi devices in the room, ensuring communication stability. The core intercom function is guaranteed through a dedicated MESH network, and the extended functions (such as Internet access) are concentrated on the host and the wireless repeater. On the one hand, it avoids the extension being directly exposed to the public network, and on the other hand, it avoids the high cost and high power consumption defects of the all-Wi-Fi solution. Moreover, the Wi-Fi modules of the host and the wireless repeater can access the external network, support firewalls and data encryption, and realize remote management (such as firmware upgrade, status monitoring) and docking with the cloud platform, taking into account both security and flexibility. The MESH network supports multi-level relay expansion. Newly added extensions can automatically access the nearest relay node and complete networking without complex configuration. Combined with the design of deploying wireless repeaters every 3 floors in the corridor, it not only adapts to the scattered building structure in old communities, but also supports the future expansion of the number of extensions, solving the pain point of poor scalability of traditional wiring systems. In addition, the integrated management platform of the same community centrally monitors all host devices through the local area network, supports remote fault troubleshooting, configuration update and status analysis; and can be deployed in combination with the existing monitoring network of the property, avoiding repeated wiring, reducing the operation and maintenance cost, and improving the management efficiency; the system can seamlessly access the existing local area network of the community (such as the monitoring network), utilize the existing network line resources, reduce the network reconstruction investment in the renovation of old communities, and accelerate the project implementation. In addition, the indoor wireless extension of this case integrates a smart home access module, directly wirelessly connects to the water and electricity meters through its built-in multi-protocol gateway, without damaging the wall wiring, and shortening the deployment time. Moreover, a single gateway supports Wi-Fi / Bluetooth / ZigBee, solving the problem of fragmented protocols of smart home devices and reducing the user access threshold. In contrast, old buildings need to deploy an RS-485 bus to connect the water and electricity meters, simplifying the construction complexity and reducing the cost.

[0103] As Figure 2As shown in the figure, each outdoor wireless digital host 100 further includes a first emergency alarm module 113, an Ethernet communication module 114, a camera module 115, a face recognition module 116, an NFC module 117, and a fingerprint recognition module 118, which are respectively interconnected with the main control CPU module 103. The RJ45 interface of the Ethernet communication module 114 of each outdoor wireless digital host 100 is connected to the existing local area network of the community through a network cable. The camera module can be used to capture images and videos for real-time monitoring and recording. The face recognition module can be used to identify the identities of residents or visitors to improve security. The NFC module can be used for access control to achieve fast access control, and thus cooperate with the face recognition module to realize face recognition and enhanced authentication of the NFC module.

[0104] The first emergency alarm module 113 of the outdoor wireless digital host 100 includes:

[0105] A first alarm button 1131. When an emergency occurs, the user long-presses the first alarm button 1131 for 1.5 seconds to trigger an alarm instruction, which is sent to the main control CPU module and then sent to the local area network of the community through the Ethernet communication module 114 or the first Wi-Fi module 102, and then forwarded to the community integrated management platform 400. Generally, the Ethernet communication module 114 is used for wired connection to the local area network, but when the wired connection fails, the first Wi-Fi module 102 can also be used for wireless transmission.

[0106] Each wireless indoor extension 300 further includes a second emergency alarm module 307. The second emergency alarm module 307 includes a second alarm button 3071. When it is detected that the second alarm button 3071 is continuously pressed and triggered for 2 seconds, an alarm instruction is triggered.

[0107] Some existing smart wearable devices have a fall detection function. For example, the acceleration sensor and gyroscope are used to detect the user's fall action (specifically, when the change in gravitational acceleration exceeds the threshold within 5 consecutive seconds detected by the acceleration sensor of the wearable device, it is determined as a fall). When it is determined as a fall, a fall detection signal is sent. The second emergency alarm module 307 of the wireless indoor extension 300 further includes:

[0108] A wearable device linkage end 3072: It is a port of the smart home interface 3102 and is wirelessly connected to the user's wearable device (such as a smart bracelet, a health monitoring device) through the Bluetooth function of the multi-protocol gateway 3101 to receive the fall signal and trigger an alarm instruction;

[0109] An environment perception unit 3073: It detects abnormal sounds (such as the sound of a fall impact) through the microphone built in the indoor extension;

[0110] Preset contact calling unit 3074: after the alarm instruction is triggered, it is first transmitted to the outdoor wireless digital host 100 through the self-organizing wireless LAN, and then transmitted to the local LAN of the community to initiate a voice call to the preset contact such as property management and family members;

[0111] Camera linkage unit 3075: After the alarm command is triggered, the smart camera in the room is wirelessly controlled by the smart home access module 310 to start recording, and the real-time image is transmitted to the community integrated management platform 400.

[0112] Water and electricity usage abnormality analysis unit 3076: used to determine water and electricity usage abnormalities and trigger graded alarms based on the residents' daily water and electricity usage patterns.

[0113] The alarm instruction is sent to the outdoor wireless digital host 100 through the self-organizing wireless local area network of the third ESP wireless module 301, and then forwarded by the outdoor wireless digital host 100 to the community integrated management platform 400 through the community local area network.

[0114] As mentioned above, the outdoor wireless digital host in this case adopts the first emergency alarm module and the second emergency alarm module of the wireless indoor extension to form "indoor + outdoor" dual emergency trigger coverage. The indoor extension alarm command is transmitted to the outdoor host via the Mesh network, and then uploaded to the management platform via Ethernet / WiFi; the outdoor host alarm is sent directly via Ethernet / WiFi, so that the redundant path of the Mesh network can ensure that even if a single node fails, the alarm signal can still be relayed to the management platform in multiple hops, thereby improving the reliability of alarm signal transmission. The outdoor host integrates camera, face / fingerprint / NFC recognition modules, not only integrates multi-functional access control, but also can start camera monitoring and identity authentication when the alarm is triggered, providing visual on-site information for the management platform. In addition, through the triple trigger mode of physical button + wearable device + environmental perception, it adapts to different emergency scenarios and significantly improves the reliability of alarm. The wearable device linkage terminal supports multi-protocol gateways (such as Bluetooth 5.2+Zigbee), is compatible with mainstream health monitoring devices (such as Apple Watch, Huawei bracelet), and reduces the threshold for user device adaptation. Preset contact call units to facilitate timely notification of relevant personnel to help customers and shorten emergency response time. The camera linkage unit uploads real-time images to the management platform, providing multi-dimensional information for remote analysis.

[0115] like Figure 5 As shown, as a preferred embodiment, the water and electricity usage abnormality analysis unit (3076) includes:

[0116] Water and electricity behavior model library 30761, used to store the baseline of water / electricity consumption patterns of different households;

[0117] The abnormality determination module 30762 is used to trigger a graded alarm action by comparing the real-time data with the baseline;

[0118] The abnormality determination module 30762 includes:

[0119] Abnormal water use determination and warning unit 307621: If the continuous non-use time is ≥ 12 hours, the water use is determined to be abnormal, and a pop-up warning is sent to the property platform; this threshold is set based on the statistical analysis of the historical water use data of 100 households. It is found that under normal circumstances, except for the family traveling, no family has a record of non-use of water for more than 12 hours. Therefore, when it is detected that the continuous non-use time exceeds 12 hours, we believe that there may be an abnormal situation and send a pop-up warning to the property platform.

[0120] Abnormal power consumption determination and warning unit (307622):

[0121] If the power consumption at night increases by ≥200% and lasts for ≥30 minutes, it is considered abnormal. This threshold setting is also based on our statistical analysis of the nighttime power consumption data of 100 households. Under normal circumstances, the power consumption at night fluctuates slightly, and it is extremely rare for the sudden increase to exceed 200% and last for more than 30 minutes. Therefore, when this situation is detected, we believe that there may be abnormal power consumption, such as electrical failure, short circuit or illegal intrusion, and send a text message alarm to the emergency contact.

[0122] Abnormal power consumption determination and warning unit 307622: if the power consumption increases by ≥200% between 22:00 and 6:00 at night, it is determined that the power consumption is abnormal and a text message alarm is sent to the emergency contact;

[0123] Linkage alarm unit 307623: After determining an abnormality, the community integrated management platform 400 calls the wireless indoor extension 300. If there is no response within the preset threshold time, the alarm command is triggered, and the preset contact calling unit 3074 is linked to automatically call the preset emergency contact and the linkage camera linkage unit 3075 to monitor the indoor residents' screen.

[0124] During specific implementation, if it is detected that there is no water usage for more than 12 hours, it is determined that the user may be unable to move due to a fall or sudden illness, and a pop-up warning is sent to the property platform; the community integrated management platform 400 makes a call to the wireless indoor extension 300 where the household is located. If there is no response within 10 minutes, an alarm instruction is triggered, and the alarm instruction is forwarded to the community integrated management platform 400, and the community integrated management platform 400 performs corresponding processing (such as alarm, sending someone to check, etc.). If it is detected that the nighttime electricity consumption suddenly increases by more than 200% and lasts for ≥ 30 minutes, it is determined that there is a fire risk, and a text message alarm is sent to the emergency contact; or an alarm is pushed to the user's mobile phone APP. Similarly, the community integrated management platform 400 makes a call to the wireless indoor extension 300 where the household is located. If there is no response within 5 minutes, an alarm instruction is triggered, and the alarm instruction is forwarded to the community integrated management platform 400, and the community integrated management platform 400 performs corresponding processing (such as notifying the property to conduct a search, power off, etc.).

[0125] As Figure 6 shown, the community integrated management platform 400 includes:

[0126] An access control management unit 401, which is used to store the household's face feature template, mobile phone number, unlocking password, and original access card information;

[0127] A remote unlocking unit 402, which is used to remotely send an unlocking instruction to the outdoor wireless digital host 100;

[0128] An emergency alarm processing unit 403, which is used to receive the alarm instruction sent by the outdoor wireless digital host 100 in real time and issue an alarm, and is used to obtain the target position where the alarm instruction locates the alarm and control the camera image in the area where the target position is located on the monitoring display screen to be enlarged and displayed;

[0129] An abnormal capture unit 404, which is used to receive the visitor capture pictures taken by the camera module 115 (such as a stranger lingering at the unit building entrance for more than 3 minutes), and is configured to: identify whether the face is that of a registered person through a lightweight YOLO algorithm. If it is determined that it is a non-registered person, an alarm is issued to remind the property staff;

[0130] A household picture monitoring unit 405 is communicatively connected to the cameras in each household, receives the real-time pictures transmitted by the camera linkage unit 3075, and highlights them in a pop-up window on the monitoring screen. During specific implementation, the cameras in the household can communicate with the community local area network through the home Wi-Fi and then transmit them to the monitoring unit 405.

[0131] Specifically, the lightweight YOLO algorithm is implemented in the following way:

[0132] Channel pruning is performed on the original YOLOv5 model, and the number of parameters is reduced by 60% to reduce the hardware deployment cost;

[0133] With INT8 quantization, the inference speed is increased by 3 times, supporting real-time 30fps video stream analysis;

[0134] Automatically adjust the face recognition confidence threshold according to the light intensity (for example, lower the threshold in strong light to avoid missed reports and increase the threshold in weak light to reduce false reports) to ensure that the false alarm rate < 1%.

[0135] The working process of abnormal capture is as follows:

[0136] The camera module detects that the target stays at the entrance of the unit building for more than 3 minutes;

[0137] The abnormal capture unit starts lightweight YOLO analysis: set the input as a 1280x720@30fps video stream, and the output is a face feature vector + behavior label;

[0138] The access control management unit performs feature comparison. When it is determined to be a stranger, the emergency alarm unit triggers an audible and visual alarm.

[0139] As described above, the access control management unit 401 integrates face, mobile phone, password, and traditional access card information to form a multi-factor identity authentication system, taking into account both convenience and security. The remote unlocking unit 402 supports remote authorization unlocking by property management or residents, especially suitable for visitor management scenarios, improving the user experience. The abnormal capture unit 404 realizes triple optimization through a lightweight YOLO algorithm, improving the effect of captured photos. At the same time, it cooperates with behavior analysis linkage. For example, when a stranger is detected wandering for more than 3 minutes, an alarm is automatically triggered and pushed to the property management, providing a basis for abnormal determination; after the captured image by the camera module 115 is analyzed by YOLO, the feature vector is compared with the access control database 401, and when a stranger is determined, the emergency unit 403 is triggered, forming an efficient collaboration. Through the setting of the emergency alarm unit 403, it is convenient to quickly lock the incident area after receiving the alarm instruction, and automatically zoom in on the camera image of the target area on the monitoring display screen to assist the security personnel in making decisions. The resident video monitoring unit 405 is connected to the camera linkage unit 3075. When an alarm is triggered (such as fall detection, abnormal water and electricity), the real-time image of the abnormal resident is automatically displayed, so as to provide a security management solution for old residential areas using the intercom system in this case and ensure the safety of users.

[0140] As Figure 3 shown, in specific implementation, each wireless repeater 200 further includes: a dynamic IP connection module 203 responsible for dynamic allocation of IP addresses, and a second power supply module 204 for powering each module of the wireless repeater;

[0141] Among them, the dynamic IP connection module 203 includes:

[0142] A processor chip 2031 that supports the DHCP protocol (such as model W7500P), which is connected to the second ESP wireless module 201 and is used to start the DHCP protocol when a new wireless indoor extension 300 is detected to be connected.

[0143] An IP address memory 2032, which is connected to the processor chip 2031 through the I2C bus and is used to store an assignable IP address pool (such as 192.168.1.100 - 200); specifically, an EEPROM chip can be used, such as a chip with the model AT24C256.

[0144] A network interface controller 2033, which is used to communicate with the upper - level node through Ethernet; the network interface controller 2033 can specifically adopt a PHY chip with the model LAN8720A; it is dedicated to processing Ethernet communication with the host 100, including extension information synchronization, status reporting, etc. In this way, through the setting of the dynamic IP connection module 203, it is convenient for the new wireless indoor extension to be plug - and - play, automatically assign an IP address to the wireless indoor extension, without the need for manual IP setting, reducing the operation and maintenance cost.

[0145] During specific implementation, since the third ESP wireless module 301 has a built - in Mesh protocol stack, it automatically starts the scanning mode after being powered on. The third ESP wireless module 301 initializes, scans the broadcast signals of the surrounding wireless repeaters 200, selects the node with the strongest RSSI and the optimal network level as the parent node; completes the identity authentication through WPA3 encryption and sends a registration request to the parent node (wireless repeater). The network interface controller of the dynamic IP connection module 203 of the parent node synchronizes the extension information to the memory 14 of the outdoor wireless digital host 100 to complete the binding. In this way, the dynamic IP connection module 203 assigns a unique IP address to the wireless repeater 200 and the connected sub - devices through the second ESP wireless module 201. The wireless indoor extension 300 is used to be bound to the household room and automatically join the Mesh network after being powered on.

[0146] The specific working process of the new wireless indoor extension access is as follows:

[0147] The third ESP wireless module 301 of the wireless indoor extension scans the Mesh network, selects the parent node (wireless repeater) and completes the WPA3 authentication. The second ESP module 201 of the parent node records the extension MAC address and triggers the DHCP process of the dynamic IP connection module by sending a "new device access" instruction. The processor chip 2031 queries the available IP pool 192.168.1.100 - 200 from the IP address memory and generates a DHCPOFFER. The second ESP module 201 encapsulates the DHCPOFFER into a Mesh protocol frame and sends it to the extension through the wireless link.

[0148] After the extension accepts the configuration, it sends a "configuration completed" confirmation frame through the Mesh network. The second ESP module 201 of the parent node sends the extension IP / MAC information to the dynamic IP connection module 203. The network interface controller 2033 encapsulates the synchronization data according to the TCP / IP protocol and sends it through Ethernet to the memory 14 of the outdoor wireless digital host 100, achieving consistent network-wide status.

[0149] As Figure 2 shown, in specific implementation, the outdoor wireless digital host 100 further includes:

[0150] An environment adaptation module 119 connected to the main control CPU module 103, and the environment adaptation module 119 includes:

[0151] A temperature and humidity sensor 1191 for real-time monitoring of environmental temperature and humidity;

[0152] An air pressure sensor 1192 for detecting rainfall or air pressure changes;

[0153] An ambient light sensor 1193 for sensing the ambient light intensity;

[0154] The first ESP wireless module 101 dynamically adjusts its own transmission power through a power dynamic adjustment mechanism;

[0155] Among them, the dynamic adjustment mechanism includes:

[0156] When the temperature detected by the temperature and humidity sensor 1191 is higher than the preset temperature, it is determined to be in a high-temperature environment, and it automatically switches to the 5GHz band and increases the transmission power to compensate for the high-temperature signal attenuation;

[0157] When rainfall is detected by the air pressure sensor 1192, it automatically switches to the 2.4GHz band and increases the transmission power to compensate for the rain fade effect; the rain fade effect has a significant impact on high-frequency signals, and the 2.4GHz band has stronger penetration ability for rain and fog, thus compensating for the rain fade.

[0158] When no human activity is detected by the ambient light sensor 1193, it switches to the sleep mode and only retains the heartbeat packet listening.

[0159] As described above, in this case, through the environmental adaptation module 119, three types of sensors for temperature and humidity, air pressure, and ambient light are integrated to achieve real-time monitoring of key environmental factors such as high temperature, rainfall, and light intensity. Through the dynamic adjustment mechanism, it automatically switches between the 2.4GHz and 5GHz frequency bands according to environmental parameters to balance signal penetration and bandwidth requirements; when the temperature exceeds the preset threshold, the system automatically switches to the 5GHz frequency band and increases the transmission power to effectively offset the signal attenuation caused by high temperature (such as the increased path loss caused by changes in air density); and when it rains, it is linked and adjusted through the air pressure sensor, switches to the 2.4GHz frequency band and increases the power to compensate for the scattering and absorption effects of rainwater to ensure the stability of the communication link. When the ambient light sensor detects no human activity, the device enters the sleep mode, only retaining the heartbeat packet listening function to reduce power consumption.

[0160] The system deployment method of the intercom system in this case includes:

[0161] Reusing the local lines of the existing monitoring network in the community to avoid adding new communication pipelines;

[0162] The wireless repeater (200) obtains power through the corridor lighting circuit, eliminating the need for independent power wiring;

[0163] The household binds the smart home device to the wireless indoor extension (300) by themselves, and there is no need for construction personnel to enter the house throughout the process.

[0164] The working principle of the intercom system in this case is as follows:

[0165] The outdoor wireless digital host (100), multiple wireless repeaters (200), and multiple wireless indoor extensions (300) in this system are each equipped with an ESP wireless module and build a self-organizing multi-hop wireless network (MESH network) based on the ESP-WIFI-MESH protocol. The wireless repeater (200) selects the path with strong signal (high RSSI) and few hops as the node to transmit data preferentially. After the wireless indoor extension (300) completes the WPA3 encryption authentication by scanning the optimal parent node (wireless repeater), it automatically accesses the network, and its authentication information is synchronized to the host (100) to achieve full-network binding.

[0166] In the audio and video transmission process, when a visitor presses the digital button on the outdoor wireless digital host, the first audio input module (such as a microphone) collects the voice signal. The first digital-to-analog and analog-to-digital conversion module (108) converts the analog voice signal into a digital signal. The voice digital signal is processed and compressed by the main control CPU module into a voice signal data packet, and is transmitted through the MESH network composed of the first ESP wireless module (101) to the target wireless indoor extension. After the resident in the room where the corresponding wireless indoor extension is located answers, it is output through the second audio output module. When the resident presses the button on the button module to trigger the reverse call signal, the second audio input module receives the call signal and converts the received digital call signal into an analog call signal through the second digital-to-analog and analog-to-digital conversion module, and forwards it to the wireless repeater through the Mesh network (i.e., the self-organizing multi-hop wireless network) and then to the outdoor wireless digital host. The whole process is supported by the memory buffer for real-time data to support multi-channel concurrency. Moreover, when the resident presses the unlock button on the wireless indoor extension, the unlock instruction is also sent to the main control CPU module of the outdoor wireless digital host through the Mesh network, so that the lock control module controls the electromagnetic lock to unlock.

[0167] In addition, the system scalability is realized through the Ethernet communication module to cross buildings or connect to the cloud. The first WiFi module of the outdoor wireless digital host and the second WiFi module of the wireless repeater support access to the Internet, providing the wireless indoor extension with the capabilities of firmware remote upgrade and smart home linkage, forming an efficient, secure, and scalable wireless building intercom solution. The Ethernet module can communicate with the outdoor hosts of other buildings or communicate with the community integrated management platform (400) through the TCP / IP protocol, and can also communicate and connect with the network interface controller of the wireless repeater.

[0168] To sum up, this case is an ESP-WIFI-MESH wireless intercom and smart home integration system for intelligent communities. The outdoor wireless digital host, wireless repeater, and wireless indoor extension terminal form a small wireless local area network through the ESP-WIFI-MESH networking technology, and then form a connected system with the monitoring system local area network and the management center host already built in the community. It realizes functions such as calling, intercom, unlocking, smart home access, and emergency alarm for the elderly between the digital host, wireless indoor extension, and management center host. It solves the problems of complex wiring, high cost, insufficient signal coverage, low bandwidth, and poor anti-interference of the traditional system, and realizes a system with low-cost rapid deployment, wide coverage, and multi-functional integrated smart home functions.

[0169] Embodiment 2

[0170] A control method for a wireless intercom and smart home integration system for intelligent communities, which is applied to the wireless intercom and smart home integration system described in Embodiment 1, and includes the following steps:

[0171] Alarm Trigger and Priority Marking: When the user presses the alarm button on the outdoor wireless digital host or the alarm button on the wireless indoor extension, an alarm instruction is generated and encrypted into an alarm packet, and the priority marking instruction is triggered to mark the alarm packet as the first priority, and the first priority is the highest priority;

[0172] Outdoor Host Call Process: When a visitor initiates a call through the outdoor wireless digital host, the voice data of the intercom call signal is generated and encapsulated into a voice data packet; if the outdoor host is equipped with a camera, the video stream data is synchronously generated and encapsulated into a video data packet; the priority marking instruction is triggered to mark the voice data packet as the second priority and the video data packet as the third priority;

[0173] Indoor Extension Intercom Trigger: When the user presses the intercom button on the wireless indoor extension, the voice data and video stream data of the intercom call signal are generated, respectively encapsulated into a voice data packet and a video data packet, and the priority marking instruction is triggered to mark the voice data packet as the second priority and the video data packet as the third priority;

[0174] Smart Home Device Control Trigger: When the user controls the smart home device through the wireless indoor extension / remote client, the control data of the control signal is generated, packed into a control data packet, and the priority marking instruction is triggered to mark the control data packet as the fourth priority;

[0175] Multi-hop Transmission Mechanism: The alarm packet, voice data packet, video data packet, and control data packet are multi-hop transmitted through multiple wireless repeaters, and dynamic scheduling is performed according to the priority level during the transmission process to ensure that the first priority data is transmitted first;

[0176] Extension Response and Interaction: After the target wireless indoor extension receives the voice data packet and the video data packet, it decodes them. If the decoding is successful, it triggers the ringing and displays the picture, and the resident conducts voice-visual intercom or remote unlocking operation through the extension;

[0177] System-level Priority Rule: The ad-hoc wireless intercom system processes data transmission in the order of the first priority, the second priority, the third priority, and the fourth priority, where the alarm packet preempts the voice, video, and control data channels.

[0178] As described above, in the method of this case, the alarm instruction is marked as the first priority, which can preempt the voice / video channel to ensure the delay-free transmission of emergency signals. So that in the event of an emergency security incident, the alarm data can reach the property or household terminal preferentially through multi-hop relay, shortening the response time. Moreover, the alarm packet is encrypted to prevent information leakage and enhance the privacy protection ability of the weak security links in old residential areas. At the same time, in this case, voice (second priority) is prior to video (third priority), and video (third priority) is prior to smart home device control (fourth priority), balancing the real-time interaction requirements and bandwidth resources. So that when a visitor calls, the voice can be connected immediately and the video stream can be transmitted later, and the visual intercom is given priority before transmitting the control instruction data to avoid network congestion. In this way, the system dynamically schedules the transmission order according to the priority, ensuring the stable transmission of key data (such as alarm and voice) in the old residential area environment with limited bandwidth and improving the communication efficiency.

[0179] Moreover, by using the intercom system of this case, through the MESH self-organizing network of the outdoor wireless digital host, wireless repeater, and wireless indoor extension phone, and cooperating with the local area network of the community to expand the coverage, the problem of signal dead corners caused by dense buildings and many obstructions in old residential areas is solved, enabling the alarm signal to cross obstacles and ensuring reliable reception by the property center. And the household can trigger the intercom or remote unlock with one key on the extension phone, and the ringing response mechanism improves the operation convenience, especially suitable for the quick operation of the elderly or in emergency scenarios. In addition, this case also supports camera expansion (such as synchronizing the video stream when a visitor calls), taking into account the basic voice function and upgrade requirements, and adapting to the renovation budgets and technical conditions of different old residential areas.

[0180] As a preferred implementation manner, the alarm packet transmission method includes the following steps:

[0181] In the alarm packet data transmission path, the AES_GCM_256 encryption algorithm is used to encapsulate the alarm packet to ensure data confidentiality and integrity;

[0182] It is explicitly marked as the highest transmission priority through the QoS field in the packet header, triggering the self-organized wireless local area network to execute the highest-level transmission mechanism;

[0183] Among them, the highest-level transmission mechanism includes:

[0184] When an alarm packet is detected, immediately interrupt the current non-emergency data transmission and reserve dedicated channel resources to ensure real-time performance;

[0185] Select the path with the highest score as the transmission path according to the first transmission path scoring formula;

[0186] Using the collision avoidance algorithm (CSMA / CA), the backoff window for the alarm packet is fixed at 2 time slots (the conventional data is 16 - 64 time slots); the backoff window in the CSMA / CA algorithm is used to determine how long a node needs to wait after detecting that the channel is busy before attempting to send data again. The larger the backoff window, the longer the node may wait, thus reducing the probability of collision because the node has a longer random backoff time to choose from.

[0187] Among them, the first transmission path scoring formula is preferably:

[0188] Path score = RSSI × 0.8 + (1 / number of hops) × 0.2. Among them, RSSI represents the signal strength: the range is usually negative (such as -30dBm to -90dBm), and the larger the value (closer to 0), the stronger the signal. The weight M is taken as 0.8 (greater than 0.5), emphasizing that the signal quality is more important for the path than the number of hops. The fewer the number of hops, the shorter the path, and the lower the probability of delay and packet loss. 1 / number of hops means that when the number of hops increases, the score of this item drops sharply (for example, when the number of hops = 1, the score is 1; when the number of hops = 2, the score is 0.5), punishing long paths. The weight N is taken as 0.2 (less than 0.4) as an auxiliary index to balance the signal strength and the path length. For example: Path A: RSSI = -50dBm, number of hops = 3 → score = (-50 × 0.8) + (1 / 3 × 0.2) = -40 + 0.067 ≈ -39.93

[0189] Path B: RSSI = -60dBm, number of hops = 2 → score = (-60 × 0.8) + (0.5 × 0.2) = -48 + 0.1 = -47.9; thus, path A is selected (although the number of hops is more, but the signal is stronger).

[0190] As described above, in this case, when the alarm packet is sent through the advanced transmission mechanism, the node sends a control frame to reserve the channel, forcing other nodes to delay transmission. At the same time, through the collision avoidance algorithm, the backoff window of the alarm packet is fixed at 2 time slots, which is much smaller than the 16 - 64 time slots of the conventional data. Although a small backoff window usually increases the collision risk, due to the channel reservation in this case, conflicts are avoided; moreover, the alarm packet is usually sporadic, and even if the backoff window is small, the actual collision probability is still lower than that of the frequently sent conventional data; thus, both the collision risk is reduced and the waiting time of the node is reduced. The path with the highest score is selected as the transmission path through the transmission path scoring formula, so as to select a path with strong signal and few hops, improving the overall network efficiency.

[0191] As a preferred implementation manner, the method in this case includes:

[0192] In the voice packet data transmission path, the UDP protocol is used to transmit voice data packets, and the dynamic routing optimization algorithm is combined to monitor the network topology in real time, and the optimal path that avoids high - load nodes or interference areas is selected;

[0193] The implementation steps of the dynamic routing optimization algorithm include:

[0194] Link quality assessment: Real-time collection of RSSI, packet loss rate, and delay time of each path;

[0195] Select the path with the highest score as the transmission path according to the second transmission path scoring formula;

[0196] Among them, the second transmission path scoring formula is:

[0197] Second path score = A1 × RSSI + A2 × (1 / delay) + A3 × (1 - packet loss rate).

[0198] Set the path switching mechanism: Set the path switching mechanism. If the score of the current path drops by more than the preset threshold B, and the score of the backup path is higher than the preset proportional value C, then switch the path within the preset time T, where B takes 15 - 30%, C takes 20 - 30%, and T takes 5 - 15ms.

[0199] In specific implementation, A1 takes 0.5, A2 takes 0.3, A3 takes 0.2, B takes 15%, C takes 20%, and T takes 10ms.; Second path score = 0.5 × RSSI + 0.3 × (1 / delay time) + 0.2 × (1 - packet loss rate); If the score of the current path drops by more than 15%, and the score of the backup path is higher than 20%, then switch the path within 10ms;

[0200] Take the following example:

[0201] Path 1: RSSI = -55dBm, delay time = 80ms, packet loss rate = 2%

[0202] Path 2: RSSI = -60dBm, delay time = 60ms, packet loss rate = 1%

[0203] Calculate the scores:

[0204] Path 1 score = 0.5(-55) + 0.3(1 / 80) + 0.2*(1 - 0.02) = -27.5 + 0.00375 + 0.196 = -27.301

[0205] Path 2 score = 0.5(-60) + 0.3(1 / 60) + 0.2*(1 - 0.01) = -30 +

[0206] 0.005 + 0.198 = -29.807

[0207] The score of Path 1 is higher, so preferentially select the stable link Path 1 for transmission.

[0208] When there is interference in Path 1 during the transmission process, the RSSI drops sharply to -70 dBm, the delay rises to 120 ms, and the packet loss rate rises to 8%.

[0209] New score: 0.5(-70)+0.3(1 / 120)+0.2*(1 - 0.08)= -35 +

[0210] 0.0025 + 0.184 = -34.8135; while the score of Path 2 is still -29.807. At this time, the score of Path 2 is 16.8% higher than that of Path 1 (exceeding the preset B = 15%). Trigger the handover: Switch to Path 2 within T = 10 ms to quickly restore the voice quality.

[0211] As described above, the method in this case transmits voice data packets by adopting the UDP protocol to balance the transmission reliability and protocol overhead; by using the second transmission path scoring formula to select the path with the highest score as the transmission path, it can reduce the end-to-end delay of voice packets; by cooperating with the path switching mechanism, it can flexibly switch when interference occurs in the transmission path, ensuring that voice data is always transmitted in a better transmission path and improving the transmission efficiency. The weight relationship A1 > A2 > A3 is set in the dynamic routing optimization algorithm because RSSI directly reflects the signal quality of the wireless link. Insufficient signal strength will lead to an increase in the bit error rate, an increase in the packet loss rate, and even communication interruption. Even if the delay or packet loss rate meets the standards temporarily, if the signal strength remains low, the link stability will be difficult to guarantee. Among the paths with similar RSSIs, the delay becomes the key differentiating factor. The delay directly affects the usability of voice communication (whether the conversation can be smooth), while the packet loss rate more affects the voice quality (the clarity of the conversation). In scenarios where the real-time requirement is higher than the voice quality (such as tactical communication and emergency dispatch), giving priority to ensuring the delay can avoid conversation interruption caused by network jitter, and at the same time, make up for the impact of packet loss through coding and decoding technologies to achieve a balance between experience and efficiency. Prioritizing the selection of low-delay paths can improve the real-time interactivity. The packet loss rate is usually the result of insufficient signal strength or increased delay jitter. After prioritizing the optimization of RSSI and delay, the packet loss rate often improves naturally without the need to assign too high a weight separately. Therefore, the setting of A1 > A2 > A3 can further improve the transmission efficiency on the premise of signal stability, balancing the reliability and real-time requirements of voice transmission

[0212] In the video packet data transmission path, the video data is compressed by H.265 encoding, and the low-delay mode (GOP = 1 and B frames are disabled) is configured. During specific implementation, the low-delay mode of H.265 encoding is enabled, GOP = 1 is set, B frames are disabled, and the IDR frame interval is forced to be 1 second; in this way, the end-to-end delay can be compressed to the single-frame processing time (≤1 ms) through an extremely simple coding structure, reducing the bandwidth occupancy. Control instruction type data packets adopt the MQTT over TCP protocol to ensure the reliable arrival of instructions.

[0213] The above has introduced in detail a wireless intercom and smart home integration system and its control method for smart communities disclosed in the embodiments of the present invention. Specific examples are used in this article to elaborate on the principle and implementation manner of the present invention. The description of the above embodiments is only used to help understand the method and its core idea of the present invention; at the same time, for those of ordinary skill in the art, according to the idea of the present invention, there will be changes in the specific implementation manner and application scope. In summary, the content of this specification should not be construed as a limitation to the present invention.

Claims

1. A wireless intercom and smart home integrated system for smart communities, characterized in that: include: A plurality of outdoor wireless digital hosts (100), each comprising a first ESP wireless module (101), a first Wi-Fi module (102) and a main control CPU module (103); the first ESP wireless module (101) and the first Wi-Fi module (102) are interactively connected to the main control CPU module (103) respectively; A plurality of wireless repeaters (200), each comprising a second ESP wireless module (201) and a second Wi-Fi module (202); A plurality of wireless indoor extensions (300), each comprising a third ESP wireless module (301) and a smart home access module (310); The first ESP wireless module (101), the second ESP wireless module (201), and the third ESP wireless module (301) are all wireless communication modules supporting the Mesh protocol; the outdoor wireless digital host (100), the plurality of wireless repeaters (200), and the plurality of wireless indoor extensions (300) are wirelessly connected through their respective ESP wireless modules and self-compose a wireless local area network; The outdoor wireless digital hosts (100) in different buildings communicate with each other through the existing local area network in the community; The smart home access module (310) of each wireless indoor extension (300) is connected to the smart home equipment in the resident's room via wired or wireless means.

2. The wireless intercom and smart home integrated system according to claim 1, characterized in that: The third ESP wireless module (301) is a wireless communication module supporting Wi-Fi / Bluetooth dual-mode communication; The smart home access module (310) comprises: A multi-protocol gateway (3101) that supports Wi-Fi / Bluetooth / ZigBee protocols; A smart home interface (3102) having the multi-protocol gateway (3101) built therein, for wirelessly connecting to smart water meters, electric meters, gas sensors and third-party smart home devices, and automatically adapting to the device communication protocol; The expansion slot (3103) provides a USB-C interface for plugging and connecting smart home devices.

3. The wireless intercom and smart home integrated system according to claim 2 is characterized in that: Each outdoor wireless digital host (100) further comprises: a memory (104), a first audio input module (105), a first audio output module (106), a Flash memory (107), a first digital-to-analog and analog-to-digital conversion module (108), a lock control module (109), a liquid crystal display (110), a numeric keyboard (111), and a first power supply module (112) for supplying power to each module of the outdoor wireless digital host (100); the main control CPU module (103) is also interactively connected to the memory (104), the Flash memory (107), the first digital-to-analog and analog-to-digital conversion module (108), the lock control module (109), the liquid crystal display (110), and the numeric keyboard (111); the first ESP wireless module (101) sends a voice signal data packet to the wireless indoor extension (300) or receives an intercom signal from the wireless indoor extension (300) through a plurality of wireless repeaters (200); The first digital-to-analog and analog-to-digital conversion module (108) is electrically connected to the first audio input module (105) and the first audio output module (106) respectively; the lock control module (109) is used to receive the unlocking instruction sent by the main control CPU module (103) to unlock and lock; Each wireless indoor extension (300) further comprises: a second audio input module (302), a second audio output module (303), a second digital-to-analog and analog-to-digital conversion module (304), a key module (305), and a third power supply module (306) for supplying power to each module of the wireless indoor extension (300); the second ESP wireless module (301) sends intercom signals to the outdoor wireless digital host (100) or receives voice signal data packets from the wireless indoor extension (300) through a plurality of wireless repeaters (200); The second digital-to-analog and analog-to-digital conversion module (304) is electrically connected to the second audio input module (302) and the second audio output module (303) respectively.

4. The wireless intercom and smart home integrated system according to claim 3 is characterized in that: Also includes: The community comprehensive management platform (400) is set up in the property center and is used to monitor the community status; Each outdoor wireless digital host (100) and the community integrated management platform (400) communicate with each other through the community local area network; Each outdoor wireless digital host (100) further comprises a first emergency alarm module (113), an Ethernet communication module (114), a camera module (115), a face recognition module (116), an NFC module (117) and a fingerprint recognition module (118) which are interactively connected to the main control CPU module (103) respectively; The first emergency alarm module (113) includes a first alarm button (1131), and when it is detected that the first alarm button (1131) is continuously pressed for more than a preset second threshold, an alarm instruction is triggered; the alarm instruction is sent to the community local area network through the Ethernet communication module (114) or the first Wi-Fi module (102), and then forwarded to the community integrated management platform (400); Each wireless indoor extension (300) further comprises a second emergency alarm module (307), wherein the second emergency alarm module (307) comprises a second alarm button (3071), and when it is detected that the second alarm button (3071) is continuously pressed for more than a preset number of seconds, an alarm instruction is triggered; the alarm instruction is sent to the outdoor wireless digital host (100) via the self-organizing wireless local area network of the third ESP wireless module (301), and then forwarded by the outdoor wireless digital host (100) to the community integrated management platform (400) via the community local area network.

5. The wireless intercom and smart home integrated system according to claim 4 is characterized in that: The second emergency alarm module (307) further comprises: Wearable device linkage terminal (3072): It is a port of the smart home interface (3102), which is wirelessly connected to the user's wearable device through the Bluetooth function of the multi-protocol gateway (3101), receives the fall signal and triggers the alarm instruction; An environment sensing unit (3073): used to detect abnormal sounds through the second audio input module (302) of the wireless indoor extension (300); A preset contact calling unit (3074): used to transmit the alarm command to the outdoor wireless digital host (100) through the self-organizing wireless local area network after the alarm command is triggered, and then transmit it to the local local area network of the cell to initiate a voice call to the preset contact; A camera linkage unit (3075): used to wirelessly control the camera in the room to start recording through the smart home access module (310) after the alarm command is triggered, and transmit the real-time image to the community integrated management platform (400); Water and electricity usage abnormality analysis unit (3076): used to determine water and electricity usage abnormalities and trigger graded alarms based on the daily water and electricity usage patterns of residents.

6. The wireless intercom and smart home integrated system according to claim 5, characterized in that: The water and electricity usage abnormality analysis unit (3076) comprises: Water and electricity behavior model library (30761), used to store the baseline of water / electricity usage patterns of different households; Anomaly determination module (30762), used to trigger graded alarm actions by comparing real-time data with the baseline; The abnormality determination module (30762) includes: Abnormal water use determination and warning unit (307621): If there is no water use for ≥12 hours, the water use is determined to be abnormal and a pop-up warning is sent to the property platform; Abnormal power consumption determination and warning unit (307622): If the power consumption at night increases by ≥200% and lasts for ≥30 minutes, the power consumption is determined to be abnormal and a text message alarm is sent to the emergency contact; Linkage alarm unit (307623): After determining an abnormality, the community integrated management platform (400) calls the wireless indoor extension (300) where it is located. If there is no response within the preset threshold time, the alarm command is triggered, and the preset contact calling unit (3074) is linked to automatically call the preset emergency contact and the linkage camera linkage unit (3075) monitors the indoor resident screen.

7. The wireless intercom and smart home integrated system according to claim 6, characterized in that: The community integrated management platform (400) comprises: The access control management unit (401) is used to store the resident's facial feature template, mobile phone number, unlocking password and original access control card information; A remote unlocking unit (402), used for remotely sending an unlocking instruction to an outdoor wireless digital host (100); An emergency alarm processing unit (403) is used to receive an alarm instruction sent by an outdoor wireless digital host (100) in real time and send out an alarm, and to obtain the alarm instruction to locate the target position where the alarm is sent out and control the camera image in the area where the target position is located on the monitoring display screen to be enlarged and displayed; The abnormal capture unit (404) is used to receive the visitor snapshot image taken by the camera module (115), and is configured to: identify whether the face is that of a registered person through a lightweight YOLO algorithm, and if it is determined to be a non-registered person, issue an alarm to alert the property staff; The resident image monitoring unit (405) is connected to the cameras in each resident's room, receives the real-time images transmitted by the camera linkage unit (3075) and displays them.

8. The wireless intercom and smart home integrated system according to claim 1, characterized in that: Each wireless repeater (200) further comprises: a dynamic IP connection module (203) responsible for the dynamic allocation of IP addresses, and a second power supply module (204) for supplying power to each module of the wireless repeater (200); Wherein, the dynamic IP connection module (203) comprises: A processor chip (2031) supporting the DHCP protocol, which is connected to the second ESP module (201) and is used to start the DHCP protocol when detecting that a new wireless indoor extension (300) is connected; An IP address memory (2032), connected to the processor chip (2031), for storing an allocatable IP address pool; The network interface controller (2033) is used to communicate with the upper node via Ethernet.

9. A self-organizing network wireless intercom method for the renovation of old residential areas, characterized in that: The wireless intercom and smart home integration system applied to any one of claims 1 to 8 comprises the following steps: When the user presses the alarm button of the outdoor wireless digital host or the alarm button of the wireless indoor extension, an alarm instruction is generated and encrypted into an alarm packet, triggering a priority marking instruction to mark the alarm packet as the first priority, which is the highest priority; When a visitor initiates a call through the outdoor wireless digital host, voice data of the intercom call signal is generated and encapsulated into a voice data packet, triggering a priority marking instruction to mark the voice data packet as the second priority; if the outdoor wireless digital host is equipped with a camera, video stream data is synchronously generated and encapsulated into a video data packet, triggering a priority marking instruction to mark the video data packet as the third priority; When the user presses the intercom button of the wireless indoor extension, the voice data and video stream data of the intercom call signal are generated, which are respectively encapsulated into a voice data packet and a video data packet, triggering a priority marking instruction to mark the voice data packet as the second priority and the video data packet as the third priority; When the user controls the smart home device through the wireless indoor extension / remote user terminal, control data of the control signal is generated, packaged into a control data packet, and a priority marking instruction is triggered to mark the control data packet as the fourth priority; The alarm packet, voice data packet, video data packet and control data packet are transmitted in multiple hops through multiple wireless repeaters, and dynamically scheduled according to the priority level during the transmission process to ensure that the first priority data is transmitted first; The target wireless indoor extension receives the voice data packet and the video data packet and decodes them. If the decoding is successful, the ringing and the display screen are triggered. The resident can use the extension to perform voice visual intercom or remote unlocking operations; The wireless intercom and smart home integration system processes data transmission in the order of first priority, second priority, third priority and fourth priority, wherein the alarm packet preempts the voice, video and control data channels.

10. The wireless intercom method according to claim 9, characterized in that: In the alarm packet data transmission path, the alarm packet is encapsulated using the AES encryption algorithm, marked as the highest transmission priority higher than the voice data packet through the packet header, and the highest level of transmission mechanism is implemented through the self-organizing wireless LAN to ensure that it has priority in obtaining channel resources, and the encryption process does not increase additional transmission delay; In the voice packet data transmission path, the UDP protocol is used to transmit voice data packets, and the dynamic routing optimization algorithm is combined to monitor the network topology in real time to avoid the optimal path of high-load nodes or interference areas; In the video packet data transmission path, the video data is compressed by H.265 encoding and configured in low latency mode; The highest level transport mechanisms include: When an alarm packet is detected, the current non-urgent data transmission is immediately interrupted and dedicated channel resources are reserved to ensure real-time performance; Selecting the path with the highest score as the transmission path according to the first transmission path scoring formula; Using CSMA / CA algorithm, the alarm packet backoff window is fixed at 2 time slots; Among them, the first transmission path scoring formula is: First path score = RSSI × M + (1 / number of hops) × N; RSSI represents signal strength, M represents RSSI influence weight ratio, and N represents number of hops influence weight ratio; Among them, 0.4≤M≤0.8, 0.2≤N≤0.6, and M+N=1. The implementation steps of the dynamic routing optimization algorithm include: Collect RSSI, packet loss rate and delay time of each path in real time; Selecting the path with the highest score as the transmission path according to the second transmission path scoring formula; Among them, the second transmission path scoring formula is: Second path score = A1 × RSSI + A2 × (1 / delay time) + A3 × (1-packet loss rate), where RSSI represents signal strength, A1 represents RSSI impact weight ratio, A2 represents delay data impact weight ratio, A3 represents packet loss rate impact weight ratio, A1 + A2 + A3 = 1, A1 > A2 > A3; The path switching mechanism is set. If the current path score drops below the preset threshold value B, and the backup path score is higher than the preset ratio value C, the path is switched within the preset time T, where B is 15-30%, C is 20-30%, and T is 5-15ms.

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