Why can LoRa technology achieve communication advantages such as low power consumption, long distance, and anti-interference?
LoRa is a linear frequency modulation spread spectrum IoT modulation technology, also known as broadband phenomenon FM (Chirp Modulation) technology. Compared with the traditional FSK technology, LoRa has a longer transmission distance under the same power consumption, and has strong anti-interference ability.
Wireless module with low power consumption
The application of the LoRa module is generally the Internet of Things devices, usually powered by batteries, and the use time is more than a few years, which requires the LoRa module to have extremely low power consumption. The realization of the low power consumption of the LoRa module is mainly determined by two aspects: on the one hand, the wireless module chip needs to have low power consumption; on the other hand, the software communication protocol also needs to have low power consumption.
First of all, the power consumption of LoRa in hardware is very low. For example, the current of SX126X series hot start sleep mode is only 1.2uA, the receiving current at 125kHz is 4.6mA, and the sending current at 17dBm power is only 58mA.
Secondly, in terms of software communication protocols, LoRa does not have complex communication protocols like other wireless technologies. The data packets are very simple, and there is no need to send a large amount of handshake data. In order to achieve the purpose of saving power, the industry widely uses the Wake on Radio (WOR) method, as shown in the figure:
The LoRa chip enters the receiving (RX) mode periodically to listen to whether there is a wake-up preamble, and is in the sleep (Sleep) mode at other times. The receiving current of WOR is shown in the figure below. Most of the time it is in sleep mode, and only a small part of the time is woken up in receiving mode, so its overall power consumption is very low. For example, Ebyte's E22 and E32 modules all have WOR function, which can meet the low power consumption requirements very well.
long-distance data transmission
In wireless communication, (Refer article: Explanation of WiFi Wireless Communication Technology )the standard to measure the communication distance is the link budget, which is equal to the transmit power minus the sensitivity. Sensitivity is a negative number, and the higher the sensitivity, the more negative, so the way to improve the link budget is to increase the transmit power and improve the sensitivity. However, the transmission power has strict requirements in various countries and regions, so the only way to increase the communication distance is to increase the sensitivity. The LoRa sensitivity has reached -123dBm when BW=125kHz, SF=7; when BW=7.81kHz, SF=12, the sensitivity has reached -149.1dBm. The sensitivity of Bluetooth is around -90dbm, and ZigBee is around -85dBm, so the transmission distance of LoRa is much longer than that of other wireless communication technologies. However, LoRa uses bandwidth in exchange for sensitivity, which will result in a very slow transmission rate, so LoRa is suitable for long-distance, low-speed, and small-volume applications.
The LoRa module can realize long-distance data transmission. In addition to the sensitivity advantage, another very important factor is the super anti-interference ability. LoRa can still communicate when the noise is lower than 20dB, which is not available in existing traditional communication technologies.
LoRa can normally demodulate the signal 20dB below the noise, while FSK theoretically needs to be 8dB above the noise to ensure demodulation. When the communication process encounters external electromagnetic signal interference, LoRa can continue to communicate stably, while traditional wireless technology cannot communicate. Therefore, in some areas with serious channel interference, customers will choose LoRa technology as the core technology for stable communication.