# Experimental Evaluation of the Packet Reception Performance of LoRa
## 4 Study on the Relationship between Physical Layer Parameters and the Performance of LoRa
### Brief Description of the Transceivers Used in the Experiments  
In order to evaluate the impact of parameter settings on the performance of LoRa, we used three LoRa devices in the experiments: An LoRa transceiver developed based on software radios, and two commercial transceivers, as shown in Figure 4. We designed the LoRa transceiver according to the characteristics and transmission process of the LoRa signal. This transceiver was developed based on USRP B200 software radios and can  
Figure 3: A time versus frequency diagram of the LoRa signal. (**a**) No noise in the channel. (**b**) The SNR in the channel is \(-3\) dB.  
Figure 2: System model of the LoRa physical layer.  
realize LoRa signals with various transmission characteristics. Our own developed LoRa transceiver uses a single antenna with 2 dBi gain. Moreover, our LoRa transceiver supports six different spreading factors, \(\text{SF}\in[7,12]\). The available BW are 125, 250, 500 kHz, etc., and CR are 4/5, 4/6, 4/7, and 4/8. By setting these parameters, we can obtain the LoRa signal we want. Our LoRa transceiver has no special requirements for terminal nodes and can work with any existing LoRa nodes.  
The other two commercial transceivers are the Semtech SX1276 LoRa (tm) mbed (tm) Enabled Shields and the RN2483 Mote from Microchip. Semtech SX1276 LoRa (tm) mbed (tm) Enabled Shields combine the Semtech SX1276 Low Power Long Range Transceiver with the ARM mbed (tm) Internet of Things (IoT) Device Platform. The mbed shields plug into mbed microcontroller development platforms from STMicroelectronics, NXP, and others. The SX1276 MB1 MAS is designed around ISM frequency bands 433 and 868 MHz for use in China and Europe. SX1276 MB1 MAS can operate in several frequency bands using two different RF ports: PA_LF and PA_HF. PA_LF covers the lower frequency band (band below 525 MHz), while PA_HF covers the higher frequency band (band above 860 MHz). The operating frequency band is controlled by register settings to produce the following values: 434, 470, 490, 868, and 915 MHz. However, changing the frequency band also requires the corresponding impedance matching in the RF front end to be changed to prevent reflections from degrading the performance. The transmit power of SX1276 MB1 MAS can reach 14 dBm, and the maximum power can reach 20 dBm by modifying the register and current limiter. Microchip Technology RN2483 LoRa(tm) Mote is an LoRaWAN Class A terminal device based on the RN2483 LoRa module. RN2483 Mote includes a light and temperature sensor that can generate data, which can start transmission according to a fixed schedule or by pressing. The RN2483 Mote operates from 863,000 to 870,000 MHz and 433,050 MHz to 434,790 MHz. The transmit power is 10 dBm on the 433 MHz band (limited to meet regulations) and the maximum transmit power is 14 dBm on the 868 MHz band. RN2483 Mote supports six different spreading factors, \(\text{SF}\in[7,12]\). The operating radio bandwidths are 125, 250, and 500 kHz.  
Figure 4: Our own developed LoRa transceiver and two commercial LoRa transceivers. From left to right: Latto, a transceiver developed based on USRP B200 software radios; the Semtech SX1276 LoRa (tm) mbed (tm) Enabled Shields; and the Microchip Technology RN2483 LoRa® Mote.