LoRa It's a kind of LPWAN Communications technology , Based on spread spectrum technology, it is widely used in ultra long distance wireless transmission scenarios . Now? ,LoRa Mainly around the world 433、868、915MHz And so on . Its biggest feature is high sensitivity , Long transmission distance , Low power consumption , There are many network nodes .
NB-IoT Is developing actively , but LoRa Technology has logged into business projects around the world , Its technology maturity has been in a leading position . In recent years ,LoRa Technology is still very useful . This article briefly introduces LoRa The basic content of technology .
One 、LoRa The secret of low power consumption
We know that distance and power consumption are natural contradictions in communication systems . When the transmission power decreases , The propagation distance must be very close . that ,LoRa How to solve this contradiction ？ The root cause is LoRa There are hyperlinked budgets , because LoRa It can improve the sensitivity of the receiver , No need for high transmit power .LoRa The sensitivity of the receiver is based on direct sequence spread spectrum technology .LoRa High signal gain is achieved by using a high spreading coefficient . Usually ,FSK The signal-to-noise ratio of 8dB, and LoRa It only needs -20dB.
in addition ,LoRa The application of forward error correction coding technology increases the redundancy of transmission information , Effectively resist multipath fading . Transmission efficiency is slightly sacrificed , But it can effectively improve the reliability of transmission . After all ,LoRa No need for high transmission rate .
Two 、LoRa The Internet
LoRa The network is mainly composed of terminals ( With built-in LoRa modular )、 gateway ( Or base station )、 Network services and application services . Application data can be transferred in both directions .
LoRaWAN Network architecture is a typical starting topology . In this network architecture ,LoRa Gateway is a transparent transmission relay connecting terminal equipment and back-end central services .
3、 ... and 、LoRa Terminal equipment
LoRa The terminal node of can be a water meter 、 Gas meter 、 Smoke Alarm 、 Pet tracking devices and other equipment . These nodes first pass through LoRa Wireless communication is connected to LoRa gateway , And then through 3G Network connection to network services . Or Ethernet . The gateway and the network server pass through TCP/IP Protocol to communicate .
LoRa The network divides the terminal equipment into A/B/C Three types of ：
a class : Two way communication terminal equipment
This type of terminal device allows two-way communication , And the uplink transmission of each terminal device has two downlink receiving windows . The transmission time slot of the terminal device depends on its own communication requirements , Its fine tuning is based on aroha agreement .
b class : A bidirectional communication terminal device having a preset reception time slot
This type of terminal device opens the redundant receiving window within a preset time . To achieve this , Terminal device receives beacon synchronously from gateway , Synchronize the time between the base station and the module through the beacon .
c class : Bidirectional communication terminal equipment with maximum receiving window
This type of terminal device will continue to open the receiving window , Only shut down during transmission .
Ebat focuses on the wireless communication industry of the Internet of things , Always pay attention to the Internet of things communication technology and industry development , Walking in the forefront of wireless communication technology of the Internet of things . Keep close cooperation with the above chip manufacturers , Develop simple and easy to use , High quality and low price wireless communication module . Include WiFi module 、 Bluetooth module 、Zigbee module 、NB module 、4G module 、 Private wireless module 、LoRa Module and LoRaWAN Gateway module .
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