The Internet of Things can be understood literally by breaking down the words. Things are lighting nodes, connections are the Internet, and networks are networks or cloud services directly formed by things. From this point of view, the Internet is the bridge in the middle. If everything wants to realize the Internet of Things technology, it cannot be achieved without a certain communication method, that is, the carrier. The most popular communication carriers of the Internet of Things today include NB-IoT, LoRa , WIFI, and ZigBee. These are the most common communication carriers of the Internet of Things. These carriers have an important commonality, that is, wireless. From the chaotic lines Detachment in the cable is a trend demand, and it is also taken into consideration for user convenience and comfort. Of course, there are more than just these communication carriers used in the lighting field of the Internet of Things today. Let’s briefly talk about the characteristics of these communication carriers and their applications in the current lighting field.
Let’s first take a look at the common wired communication carriers.
For RS485 bus communication, the maximum communication distance is about 1219m, and the maximum transmission rate is 10Mbps. It can generally reach 128 or 256 nodes, and the largest one can support 400 nodes. Common applications are tunnel lighting and landscape lighting. Communication in tunnel lighting is often based on the MODBUS protocol. Each tunnel light is a node of the Internet of Things. Through the multi-slave function supported by 485, all tunnel lights are connected in parallel on the 485 bus, which is two twisted pairs. On the cable; for landscape lighting, it is commonly implemented based on the DMX512 protocol. It has more powerful functions than MODBUS and more complex data, so it can achieve more complex lighting functions, so it is most suitable for application in large-scale landscape lighting. The characteristic of RS485 is its long distance, which avoids external signal interference and is reliable. However, the need to pull additional wires brings more inconvenience to the on-site lighting renovation project, and if there is line damage or terminal equipment failure in the middle, the back-end equipment will fail. Therefore, this kind of communication carrier is often used more in commercial lighting. In home lighting, it is often out of place and will not be favored by users in the long run.
DALI is a wired communication technology that mainly occupies a large share in the field of indoor lighting. The system based on the DALI protocol has distributed intelligent modules. Each module has digital control and digital communication capabilities. Address and lighting scene information are stored in the memory of each DALI module. The DALI module communicates with digital elements through the DALI bus, transmits instructions and status information, and implements functions such as light switching, dimming control, and system settings. From a functional point of view, due to the richness of data management, although the cost of wiring is increased, the management is superior to RS485, and the security is better than wireless methods.
Ethernet, a wired broadband communications carrier. Without exception, this kind of wired communication carrier is not common in home lighting. It is common in the field of outdoor smart lighting, with the help of light poles, video sensors and street light control transmitted through wired broadband carriers to achieve high speed and safety purposes. Streetlights and surveillance are major components of the city, and their security cannot be underestimated. Once information about streetlights is intercepted, they will be arbitrarily controlled by hackers, causing everything that relies on lighting, such as urban transportation, to fall into chaos. Therefore, this kind of communication exists in municipal lighting situations. Although there are not many, it is a way of promotion. Ethernet is also one of the longest-standing ones in the communication industry.
PLC, power carrier, transmits signals through existing power lines, eliminating the need for additional lines and avoiding the probability of line damage. Usually power carriers also have self-organizing network capabilities, so data can be transmitted over long distances through relays. This is a relatively excellent communication carrier. Currently, this type of communication is widely used in outdoor lighting and indoors. Because of the standardization of power lines and the maturity of power carrier communication technology, this method is widely used in the market. Promote it widely. What I have to say is that when this communication method is used in outdoor lighting renovation, most lighting companies encounter short communication distances. Long distances will slow down the communication speed or reduce the success rate, which makes lighting project renovation owners feel confused. have no choice.
The next most popular wireless carrier. ZigBee and Bluetooth, these two communication carriers can be discussed together. Both types of communication are mostly implemented based on 2.4G. They are characterized by supporting networking. The disadvantage is that the communication distance between two people is short. This is because the 2.4G frequency band is limited and it is easy to produce large noise under the obstruction of obstacles. attenuation. However, these two kinds of communication have a wide range of applications in indoor lighting, because they have low power consumption, energy saving, fast data transmission speed, and can effectively avoid the probability of control collision. In addition to the networking method, if there are several individual nodes Failure, other nodes will not fail due to the failure.
NB-IoT, LoRa, and Sigfox are the most prominent members of LPWAN in recent years. In the third quarter of 2017, it was reported that the number of public LPWA networks in experimental status and commercial use increased to 198, with NB-IoT taking the lead with 69 networks (occupying 35%), followed by LoRa and Sigfox. Among several low-power wide-area networks, LoRa is commercially available earlier and is more open. An industry alliance was established in 2015, and it is currently the most widely used in LPWAN. NB-IoT, which achieved standard freezing in 2016, uses licensed spectrum to avoid wireless interference and has carrier-level security and quality assurance. Therefore, it has a more competitive advantage in smart lighting scenarios that require high reliability. , the fastest growing market share. Also affected are Z-Wave and Sixfox. Both of these are wireless communication technologies based on Sub-1GHZ like LoRa. They are both unlicensed spectrum LPWAN technologies, while NB-IoT is an authorized communication method, so this communication carrier is mainly used in China. Three major operators to support operations. Obviously, this unlicensed communication technology is relatively open and has a flexible deployment method in the lighting industry. It is independent of other operators. Lighting companies can act as their own operating departments, and even the municipal lighting management department itself is an operator.
Also based on wireless radio frequency communication technology, these outstanding communication carriers have their own relative characteristics. LoRa is a communication network based on LoRa spread spectrum modulation technology. The wireless frequency band it covers has good diffraction and reflection capabilities. Coupled with spread spectrum technology, the signal is not easily interfered and packet loss occurs in the air, so it is suitable for outdoor use. Lighting is very helpful in complex cities. It solves the problems of power carriers in the past. In addition, with the perfect encryption method, its security is also reliable. Therefore, transmission is relatively unaffected by trees and buildings. It is an emerging short-distance wireless communication technology based on radio frequency, low cost, low power consumption, high reliability, and suitable for networks. Z-wave operating frequency band is 908.42MHz (United States) ~ 868.42MHz (Europe), using FSK (BFSK/GFSK) modulation method, the data transmission rate is 9.6kbps, the effective coverage range of the signal is 30m indoors, and can be used outdoors More than 100m, mainly used in indoor lighting situations abroad, but still a rare communication carrier in China.
NB-IoT can still be said to be a new thing at present. Although it is emerging in the field of lighting, there are still many shortcomings. The stability of the entire network is still limited by the perfection of the technology, which leads to whether it can still be used in the field of outdoor lighting. It is widely used; in the field of indoor lighting, it is even more difficult to break out, and the higher cost is beyond the reach of ordinary users.
Similar to NB-IoT, there are 2G, 3G, 4G, and then there is 5G communication technology. The common feature of these is that the IoT structure directly skips the intermediate gateway and directly accesses the network. That is, each communication method Each node is an individual. These communication technologies have been around for a long time in history and are used for stable communication performance. Although they have poor advantages in speed and cost, it is difficult to conceal their stability.
Dual-mode communication, the concept of dual-mode is broad, and it is nothing more than a redundant means composed of two communication modes. This kind of communication carrier currently mainly exists in outdoor commercial lighting, and the cost is unacceptable for indoor lighting. At the same time, because the range of indoor lighting is small, there is no need to use this technology. The combination of dual-mode is usually a mixture of wired and wireless technologies. It is common to combine power line communication technology and SUB-1GHZ wireless communication technology into one. Taking advantage of the natural differences between the two channels, the physical layer can be realized according to the quality of each channel. Automatic switching and hybrid routing can be implemented at the network layer. The two complement each other to maximize the timeliness and reliability of communication, which can survive well in complex urban environments.
Finally, there is the WiFi communication carrier. The most common application of this communication carrier is in indoor lighting. As everyone knows, WiFi should be used by mobile devices to surf the Internet, so it can be easily used by ordinary users, and for individual families , WiFi can basically cover the entire home interior, so sensors and lighting plus WiFi communication are convenient. A router interface completes the summary management of home lighting, combined with cloud data management, such communication is suitable for indoor low-cost lighting upgrades. Of course, outdoor lighting is also being gradually improved. Because urban WiFi coverage is gradually expanding, it is entirely possible for each street lighting node to access through WiFi.
Based on the various communication carriers mentioned above, they can be seen in both indoor and outdoor lighting. Each has its own advantages. Select the appropriate communication carrier according to the complexity of the environment and the degree of data security to ensure reliable networking of lighting nodes.