Since the Ministry of Industry and Information Technology issued the “Notice on Comprehensively Promoting the Construction and Development of the Mobile Internet of Things (NB-IoT)” in 2017, the three major communication operators, China Mobile, China Telecom, and China Unicom, have fully launched the construction of NB-IoT networks. As of now, The NB network has achieved signal coverage in most cities.
At the same time, a large number of applications based on NB-IoT networks have been gradually promoted, and projects such as remote meter reading, asset tracking, smart parking, smart manhole covers, and smart agriculture have been launched in various places. Among them, smart parking is recognized by the industry as the most suitable One of the application scenarios of NB network commercialization.
NB smart parking, urban roadside parking is the primary implementation scenario
In fact, in most domestic NB smart parking cases, the role of NB is mainly reflected in the parking space detector. A parking space detector is installed on each parking space to detect the occupancy status of the parking space. Whenever the parking space status is updated, It can be uploaded to the background in real time through the NB-IoT network. It has two functions: first, it can generate a billing order based on the vehicle’s entry and exit time as a basis for payment; second, it can publish parking space occupancy information through the platform to facilitate car owners to find free parking spaces.
The first and most typical application is urban roadside temporary parking spaces. These parking spaces are widely distributed on the edge of urban roads. They cannot be centrally managed using gate equipment like parking lots. Charging can only be achieved through parking space detectors. , and managed through the platform. The second point can be applied to both roadside parking spaces and closed parking lots. However, for small parking lots, it is not necessary to install a parking space guidance system. Therefore, the most suitable application scenario for NB-IoT smart parking is mainly urban roadside parking.
Because NB parking space detectors can be powered by batteries, the service life of a device can be more than 5 years. In addition, NB-IoT is a network built by operators. Unlike Zigbee, which requires self-built networks, users only need to pay a certain amount. With “phone charges”, you can directly use the operator’s NB network like a mobile phone, plug and play, which greatly reduces the difficulty of project implementation and reduces the project’s construction costs and later maintenance costs. Yiche has adopted NB geomagnetic solutions in many large-scale urban roadside parking projects recently launched in Xi’an, Chuzhou, Mengzi, Renqiu, etc.
Based on our experience in the implementation of previous projects, we calculated based on an urban roadside parking project with 10,000 berths. Taking traditional geomagnetism as an example, in addition to needing to configure one geomagnet for each berth, on average every 15 geomagnets need to be equipped with a 4G communication device. Gateways require 666 gateways, and each gateway needs to be installed with a column with a height of about 3 meters.
Compared with ordinary wireless communication technology, NB reduces the equipment cost of wireless gateways and the corresponding installation and construction costs. Although the equipment price of NB geomagnetic vehicle detectors is about 20% higher than that of traditional geomagnetics at this stage, overall, using NB Compared with the traditional geomagnetic solution, the construction cost of the geomagnetic solution still needs to be reduced by more than 20%. In addition, since the NB geomagnetic data is directly uploaded to the background, the gateway link is missing, which also brings us great convenience in equipment maintenance.
NB new geomagnetic technology, high cost and low power consumption
The cost of NB geomagnetic is higher than that of traditional geomagnetic. In addition to the current higher cost of NB communication modules, another reason is that the power consumption of NB geomagnetic is also higher than that of traditional geomagnetic. For a long time, one of the main features of NB geomagnetic propaganda in the industry is low power consumption, but in fact, low power consumption is for 2G/3G/4G communication technology. Compared with traditional geomagnetic communication technologies such as Zigbee, Its power consumption is actually higher, mainly for the following two reasons.
First, the transmit power of NB is greater than that of traditional geomagnetic communication technology. First of all, the maximum transmit power of the NB network is 23dBm, and according to the national radio management regulations, the maximum transmit power of the 470M frequency band commonly used by traditional geomagnetic communication technology is generally limited to below 17dBm;
Secondly, in actual applications, the coverage distance of NB network is farther than that of traditional geomagnetic communication technology, which will also lead to greater transmit power of NB terminals. Generally speaking, the emission current of traditional geomagnetism is between 60 and 120mA, and the emission current of NB geomagnetism is between 60 and 200mA. The maximum instantaneous current can reach more than 300mA.
Second, NB takes longer to complete a data report than traditional geomagnetic communication technology. First of all, the time it takes for traditional geomagnetic communication technology to report data is milliseconds, while NB takes several seconds to complete a data report;
Secondly, after traditional geomagnetic communication technology sends data, it can immediately enter the sleep state. However, after NB geomagnetic sends data once, it must first go through an IDLE idle state of about 20 seconds before entering deep sleep, and the IDLE state retention time is determined by the base station. Configured, the terminal cannot be changed. However, the latest version of the NB network has been improved and the RA function has been opened, allowing the terminal to send instructions to the network side to directly enter the sleep state.
Screenshot of NB geomagnetic transmission current test. It usually takes 1 to 5 seconds for NB geomagnetic to complete a data transmission.
Screenshot of traditional geomagnetic emission current test. It usually only takes 300~800ms to complete a data transmission in traditional geomagnetic field.
In actual use, the power consumption of traditional geomagnetism and NB geomagnetism is related to the network environment. If the network signal is good, the terminal transmission power will be low. If the network signal is poor, the terminal transmission power will increase accordingly. This is the adaptive mechanism of the network. . In addition, the battery life of the geomagnetic field is also closely related to the turnover frequency of parking spaces. According to the comprehensive evaluation of our laboratory, the overall power consumption level of NB geomagnetism is about 2 to 2.5 times that of traditional geomagnetism. We believe that as NB technology continues to mature, there will be some room for improvement in power consumption.
In addition to the above NB geomagnetic parking space detectors used in roadside parking, there is another application scenario that is very suitable for NB, which is parking space reservation/shared parking. A key device needed for parking space reservation or shared parking is the parking space lock. The car owner user can Make a reservation and place an order through the mobile app. After driving to the designated parking space, you can control the parking lock to fall through your mobile phone. This type of parking spaces are often scattered in various parking lots. Parking space locks based on NB communication can be powered by batteries and are easy to install. Normally, the batteries only need to be replaced every six months.
All in all, NB-IoT is just a communication method for the Internet of Things. It mainly solves the problems of low power consumption, large connections, wide coverage, and large capacity.
NB can only solve the problems it can solve in the parking scenario, but cannot solve all problems. In certain scenarios in the parking industry, such as roadside parking, vehicle detectors using NB communication have obvious advantages. However, not every scenario or device is suitable for NB communication. For example, for some devices that must be connected to mains power, the power supply itself is no longer a problem. It would be meaningless to use NB battery power supply. In actual projects, we cannot blindly use NB to promote the application of NB. We still need to recommend the most appropriate solution to the customer based on the actual needs of the customer.