With the vigorous development of the Internet of Things, the popularity of smart homes is also rising. Due to the safety, energy saving, comfort, convenience, and high efficiency of smart homes, more and more customers have begun to accept and develop smart home items and systems. In the past few years of promoting Zigbee technology in China, I have been fortunate to see Chinese manufacturers achieve "overtaking on a curve" in the field of Internet of Things and smart home. Wireless modem China's smart home technology and market are developing extremely rapidly. Our products and systems can Said to be the world leader. Chengdu Yibyte Electronic Technology Co., Ltd. is a high-tech enterprise focusing on Internet of Things application experts. It has hundreds of independent research and development products and has been unanimously recognized by customers. The company has strong R&D technical strength and a complete after-sales system to provide customers with comprehensive solutions and technical support, shorten the R&D cycle, reduce R&D costs, and provide a powerful platform for new product R&D ideas. The technical interface of the smart home system To analyze the wireless technology of the smart home, it must first be clear: what is the scope of the smart home?
What is the system architecture? This is the basis of our discussion. Let's take a subsystem in the smart home - the smart lighting system as an example to illustrate the problem. As shown in the figure, the home intelligent lighting system can be roughly divided into three technical interfaces: ① cloud-based applications and services; ② home-wide wireless control network; ③ internal control software and driving circuits of intelligent lighting products. Of the three technical interfaces, the most concerned, discussed, and confusing is the second interface: the home wireless control network. Various product forms coexist in the market, and various opinions are contending on the Internet. It should be understood that technology itself does not matter whether it is good or bad (clumsy technology is naturally eliminated in its development), only suitable or not. What we think about is: what kind of wireless technology is more suitable for smart home network? In other words, what unique requirements does a smart home system have for wireless interconnection technology? How does the smart home system work? The acceptance of new things by individual consumers often exceeds the expectations of the industry, and smart home is also an example. The scope of smart home is extremely wide, and there is no unified definition. Its typical subsystem—smart lighting—can be as simple as an independent controller (a mobile phone is also a controller) and a lamp, or as complex as a complete lighting system integrating lighting devices, sensors, smart switches, and control algorithms.
As the first step for consumers to get in touch with smart lighting, a light bulb that can be controlled with a mobile phone and is easy to install is a good product form. This light bulb may not be so perfect and not rich in functions, but it must be screwed on like a normal light bulb. It can be operated in a few minutes. Therefore, for consumers, the first requirement of smart products is: low complexity and easy installation. When consumers gradually get used to using mobile phones to control light bulbs at home, new demands have emerged. At this time, switching devices seamlessly interconnected with light bulbs can provide more natural and intuitive services. If it is equipped with suitable sensors, such as motion, temperature and humidity, and light sensors, by setting specific rules, a small, automatically operating lighting system will appear. This lighting subsystem can interact with other subsystems such as security, audio-visual, kitchen and bathroom, and sunshade systems. This makes up a typical smart home wireless network.
Therefore, the wireless network of the smart home should be a large-scale, multi-device local area network. In technical language - it should be a mesh network. Let's put aside the dazzling technical indicators and market promotion, and think about what elements should be in a stable and reliable smart home wireless network along the lines of thought just now.
1. Mesh networking. The number of nodes in a smart home system can range from a few to dozens or even hundreds, which is completely different from point-to-point controlled smart products, requiring the network to provide greater redundancy for load balancing and path selection. To achieve load balancing, it is necessary to work hard on the routing protocol, create and select routes reasonably, and perform continuous and dynamic optimization.
2. Robustness. In a network with a large number of nodes, robustness is critical. Smart home systems are mostly deployed indoors, and the occlusion, reflection and interference of the radio environment on the spatial structure all put forward higher requirements on the robustness of the system. Rational creation of routes and maintenance of devices, as well as different types of communication packets, all have a decisive impact on the robustness of the network.
3. Reusability of space. In a limited frequency spectrum, how to reasonably avoid and allocate different technologies also poses a challenge to the stability of the wireless network. The spatial access mechanism, as well as the coordination of software and protocols, play a big role in it. Why does Zigbee go to great lengths to do mesh networking? Wireless Transmission Test kits Another IoT wireless technology that is also used to connect low-power resource-constrained devices—low power wide area network (LPWAN)—is a typical centralized network structure (ie, a star network). It will be very interesting to compare the characteristics of these two technologies, and it will also help us to deepen our understanding of IoT wireless connection technology. LPWAN (such as NB-IoT and Lora) is an excellent wireless network, which directly connects IoT devices to base stations over long distances, and then accesses the cloud. This network topology determines that while LPWAN obtains low power consumption and long-distance connections, it gives up an extremely important feature for smart homes-local interaction of devices. Please see the example below. This is an extremely simple device interaction - light a light bulb (or sensor, of course) when the door is opened.
In a local mesh networking network, door locks can be directly connected to light bulbs, and this function can be realized in one step through logical binding at the application layer. Under the LPWAN architecture, the door lock must report the message to the base station. Usually, the base station does not implement application logic and needs to be further reported to the cloud. The cloud sends instructions to the light bulb through processing-turning the light on or off. This data path is clearly overcomplicated for this application. Of course, in practical applications, each message transmission of LPWAN also means a fee, but this is another level. Furthermore, if hundreds of devices are operated in this way, the performance difference of the system will be very obvious. Some people may think, why can't local communication be realized on LPWAN, such as NB-IoT devices? It is not surprising that this question is asked, and it is even somewhat taken for granted. I once met an Internet of Things practitioner at a seminar, and he described his new application on NB-IoT at a large length, which was based on this idea.
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