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Increased Complexity And Reduced Network Capacity
- Feb 02, 2018 -

LoRa is one of the LPWAN communication technologies and is an ultra-long-range wireless transmission scheme based on spread spectrum technology adopted and promoted by Semtech Corporation of the United States.

Is the physical layer or wireless modulation used to establish long-range communication links. Many conventional wireless systems use frequency shift keying (FSK) modulation as the physical layer because it is a very efficient modulation that achieves low power consumption.

LoRa is based on chirp spread spectrum modulation, which maintains the same low power consumption characteristics as FSK modulation but significantly increases the communication distance.

LoRa technology itself has superior receiver sensitivity (RSSI) and superior signal-to-noise ratio (SNR). In addition, the use of frequency hopping technology, through the pseudo-random code sequence frequency shift keying, the carrier frequency continues to change and spread the spectrum to prevent frequency interference.

At present, LoRa mainly operates in the global free frequency band, including 433,868,915 MHz and so on.

In a mesh network, individual terminal nodes forward information of other nodes to increase the communication distance of the network and the size of the network area. Although this increases the range, it also adds complexity, reduces network capacity, and reduces battery life as nodes accept and forward potentially unrelated information from other nodes. When implementing long-haul connections, the most significant benefit of the long-distance star architecture is the protection of battery life.

If the gateway is installed at the location of an existing mobile communication base station with a transmitting power of 20dBm (100mW), then it can cover about 2km in a high-construction-intensive urban environment and 10km in a less densely populated suburban area. The gateway / concentrator also contains the MAC layer protocol, which is transparent to the upper layers.

LoRa network mainly by the terminal (built-in LoRa module), gateway (or base station), web server and application server. Application data can be bi-directional transmission.

The LoRaWAN network architecture is a typical star topology in which the LoRa gateway is a transparent transport relay connecting the end devices to the back-end central server. Terminal devices communicate with one or more gateways in a single hop. All nodes and gateways are two-way communication.