How Does LoRa Network

LoRa is one of the popular technologies specially designed for wireless transmission in the Internet of Things. LoRa network specification includes LoRa physical layer technology (non open technology provided by semtech) and LoRAWAN (MAC multimedia access layer) open layer protocol. It depends on LORA IC: SX1262, SX1276, SX1272 etc.

Protocol layer The whole network protocol layer of LoRa is as follows:

The application layer is the application layer, and the common LoRaWAN protocol is the LoRaMAC protocol. The terminal types defined in the protocol are ClassA, ClassB and Class C. The main difference is that ClassA triggers the downlink receiving window, which can only be opened when the uplink sends data. ClassB defines the ping cycle and monitors the downlink data regularly; ClassC monitors downlink reception as much as possible, and basically only stops downlink reception during uplink transmission; According to the protocol, each terminal must support ClassA, while B and C are optional functions. At the same time, terminals that support the ClassC function do not need to support the classB type. The physical layer of LoRa is not open, so we can roughly understand its physical layer technology with some data. LoRa is designed to use ISM(industrial scientific medicine), that is, unlicensed free frequency band.

Structure The overall network structure of LoRa is divided into terminal, gateway, network service and application service. In general, data transmission can be carried out between LoRa terminals and gateways with the help of LoRa wireless technology. The interaction between the gateway and the core network or WAN can be through TCP/IP protocol, of course, it can also be wired Ethernet or 3G/4G wireless connection. In order to ensure the security and reliability of data, LoRaWAN uses a symmetric encryption algorithm AES with a length of 128 bits for integrity protection and data encryption.

Star Network Connect

The End device usually using thelora module.

The server modules in LoRaWAN can be subdivided into Join Server, Application Server and Network Server. They are only divided by function, but can actually be a physical whole. When the terminal device requests network service capability, the joining server is used for the activation process. Netwrok server is responsible for MAC data interaction with gateway and terminal. Application Server is an application layer server. The reference network model provided by the specification is as follows.

Family Connection

Mobile Connection

Compared with NB IoT effect, it mainly compares the implementation of type functions under analogy, which is easy to understand and does not compare performance. ClassA can send data only after the uplink sends data. Similarly, when the NB IoT module is in PSM (power saving mode) mode, the network can send data to the terminal only when the terminal sends data to the upstream. In this case, the network needs to be able to cache data. ClassB mode is somewhat similar to the DRX and eDRX modes of NB IoT. The maximum eDRX of NB module can be configured as 2.9 hours, while the maximum receiving cycle of LoRa is 128 seconds; The ClassC terminal can receive all the time except the uplink transmission time, which is closer to the connection status of NB IoT.