# LoRa 2.4 GHz Communication Link and Range
## 6 Discussion  
We investigated the maximum communication range of LoRa in the 2.4 GHz band, which is defined as the maximum distance between a transmitter and receiver at which a LoRa-modulated message can be received properly. Our investigations included three environments: LoS free space, NLoS indoor and urban outdoor. In all three scenarios, we maximized the range by reducing the bandwidth and increasing the spreading factor. Based on the total link budget of the wireless communication system, including receiver sensitivity, antenna gains and cable losses, we were able to estimate the range of LoRa at 2.4 GHz. It is important to note that we did not include a fade margin in the link budget calculations. The fade margin can be defined as the level of received power in excess of that required for a specified minimum level of system performance. The reason for excluding this loss parameter in (9) is the high variability of fade margin in different scenarios. For instance, a 5 dB fade margin decreases the maximum urban range from 867 m to 576 m, while a 10 dB fade margin further decreases the range to 164 m. Thus, this should be taken into account when analyzing the results. Nonetheless, the largest factor by far in a link budget is the path loss. The free space line-of-sight scenario resulted in a theoretical maximum range of 133 km when transmitting at the highest SF and using the lowest bandwidth. In reality, the signal will always have to cope with obstacles, multipath propagation effects and interference with other signals. Therefore, these ranges will never be achieved in a real-world environment. Nevertheless, the results of the Free Space Path Loss model are useful as a benchmark as they enable us to compare them with different frequencies and technologies. For instance, the maximum range of LoRa at 868 MHz calculated with the FSPL model equals 921 km, which is almost seven times the range of LoRa at 2.4 GHz. For the indoor range estimation of 2.4 GHz LoRa, an indoor path loss model was evaluated. In order to provide the highest possible accuracy, a model based on real-world measurements was adopted and slightly modified, taking into account both wall and interaction loss [28]. The estimated range varies from 18 m to 74 m, depending on the SF and BW. It should be noted that a path loss exponent of 5 was chosen, simulating an obstructed indoor environment. However, in an indoor LoS scenario, the range might therefore be increased. Finally, the maximum communication range in an urban environment was found to be 867 m. As indicated in Figure 4, the range at an SF of 10 and a BW equal to 406 kHz is 443 m. This is similar to the results of the experiments with the SX1280 chipset carried out by [PERSON] et al. [17]. They found that ToF ranging with the aforementioned SF and BW failed for ranges over about 500 m. Although they only investigated the ranging feature at an SF of 10 and a BW equal to 406 kbit/s and 1625 kbit/s, this partially validates our range estimations of the ECC-33 path loss model. Figure 4: Communication range and data rate for every combination of spreading factor (SF) and bandwidth (BW) in an urban environment. Besides the communication range, we investigated the data rates for all combinations of SFs and BWs and consequently associated this information with the highest achievable range. The highest possible data rate of LoRa at 2.4 GHz equals 253.91 kbit/s, which is almost seven times higher than the maximum data rate of LoRa at 868 MHz. This data rate can be achieved if the distance between the transmitter and receiver is not greater than 3739 m, 18 m and 3 m in a free space, indoor and urban environment, respectively. Some significant differences in terms of range arise when comparing LoRa to other technologies operating in the 2.4 GHz band. As mentioned earlier, the range of the latest Bluetooth standard equals 50 m and 165 m in an indoor and outdoor environment, respectively.