"Network transmission technology" in "smart home"

    1. About the meaning of smart home network transmission technology

    Transmission technology refers to the technology that makes full use of the transmission capabilities of different channels to form a complete transmission system so that information can be transmitted reliably. The transmission system is an important part of the communication system, and the transmission technology mainly depends on the transmission characteristics of the specific channel. Its channels are divided into wired and wireless.

    There are two types of information that need to be transmitted in the smart home network system. One type is control information. The common characteristics of this information are small data volume and low transmission rate, but high real-time and reliability requirements. The other type is data information, including various high-definition video and audio information, which requires a high transmission rate but low real-time requirements.

    "Smart home network" is a network system that can fully cover family life and provide various intelligent services. The smart home network system includes several major functional modules such as control center, home gateway, and home facilities. The control center is mainly used to interpret user instructions and enable and coordinate different home devices to work together. The home gateway is responsible for connecting the network that manages various smart home appliances and access control security with the Internet, thereby providing users with a remote viewing and control platform, and providing an information sharing platform for various home devices. Home devices perform their respective duties to complete the instructions issued by the control center.

    2. Wired transmission method in smart home

    The advantages of wired transmission are good reliability, convenient protocol design, low power consumption, and because the bandwidth is relatively large, the compression ratio can be reduced. It is also the preferred transmission method for smart home networks. At present, there are many wired transmission methods for smart homes, such as X-10 and CEBUS of power line carriers, EIB, C-Bus, LonWorks, SCS, RS-485, CAN and other buses, which perform protocol control on other peripheral devices. Many users believe that wired transmission is not only stable but also safer than wireless. However, wired transmission requires wiring and the installation process is complicated. Therefore, it is also the shortcoming of wired transmission. Of course, these implementation schemes each have their own characteristics, and different transmission methods need to be selected according to different required data transmission rates and data transmission ranges.

    LonWorks Bus Technology

    LonWorks is a local operation network. It is a fieldbus network developed by Echelon Corporation of the United States and officially announced in 1990. It is an open standard and one of the most widely used and most promising fieldbus technologies in the world. It adopts the complete seven-layer communication protocol in the ISO/OSI model and the object-oriented design method. It simplifies the network communication design into parameter settings through network variables. Its maximum communication rate is 1.25Mbps (communication distance does not exceed 130m), the farthest communication distance is 27000m (communication rate is 78Kbps), and the total number of nodes can reach 32000. The transmission medium of the network can be twisted pair, coaxial cable, optical fiber, radio frequency, infrared, power line, etc. The core of LonWorks technology is LonTalk protocol, which is based on the complete seven-layer communication protocol in the ISO/OSI model, has good scalability and portability, and is convenient for communicating with nodes on TCP/IP network.

    3. Wireless transmission technology in smart home

    Wireless transmission mechanism is easier to deploy and expand than wired transmission mechanism. It has become an important choice for smart home networks and will become the preferred communication mechanism in the future. At present, the wireless technologies used in homes are mainly radio frequency technology, infrared technology, WIFI technology, Bluetooth technology and ZIGBEE technology, which is being vigorously promoted. Among them, the more mature radio frequency technology has the characteristics of low cost and good penetration, but the anti-interference and security are poor. It is currently only used for one-way communication. Infrared technology is relatively mature, but it must be connected in a straight line of sight, which is very restrictive and not suitable for home networks. Here we focus on ZIGBEE technology as an example.

    ZIGBEE TECHNOLOGY

    ZIGBEE technology belongs to the IEEE802.15.4 protocol and is a short-distance, low-power, low-rate, low-cost two-way wireless communication technology. It is mainly used for wireless data transmission between various electronic devices with short distances, low power consumption and low transmission rates. Since ZIGBEE has a low transmission rate, the transmission power is only 1mW, and it uses a sleep mode with low power consumption, so ZIGBEE devices are very power-saving. In terms of low power consumption cost, according to Baidu Encyclopedia, the initial cost of the ZigBee module is about US$6, and it is estimated that it will soon drop to US$1.5-2.5, and the ZigBee protocol is free of patent fees. In addition, it can withstand a large network capacity and flexible network composition. Therefore, ZIGBEE, as a low-power data rate and low-cost technology, is obviously more suitable for applications in home automation, security systems, etc.