# A Survey of LoRaWAN for IoT: From Technology to Application
## 5 Physical Layer Performance Evaluation
### Coverage  
LoRa coverage depends on transmission parameters (mainly SFs, transmit power and channel bandwidth used) and environment conditions where the gateways and the end nodes are deployed. Several empirical studies were performed to assess coverage for outdoor and indoor environments as well as indoor-to-outdoor coverage.  
In [32], a measurement campaign performed in the city of Oulu in Finland (mostly a flat city) is presented. The gateway was placed in an antenna tower at 24 m above the sea level. Results showed that in the range of 2 km the packet loss ratio (PLR) was 12% while the Received Signal Strength Indicator (RSSI) was above \(-\)100 dBm. For ranges from 2 to 5 km, the PLR was 15%; for ranges from 5 to 10 km, 33% of packets were lost; and above this range, 74% of packets were lost. For measurements in open sea area losses were lower, being 31% for ranges 5-15 km and 38% for ranges 15-30 km, respectively. Thus, it is shown that LoRa can achieve good coverage range (up to \(\sim\)5 km) while packet loss performance can degrade faster in the areas above 5 km. No ADR, repetition or acknowledgement mechanism was considered in this study. Long coverage in such a case comes as a result of terrain configuration. It is expected that in more hilly terrain the coverage would be lower. However, still the coverage distance will be acceptable in terms of some km.  
Another coverage test was performed in an urban environment with 5-6 floor buildings [33]. LoRa gateway was deployed on top of two store building. The achieved coverage was around 2 km. However, beyond 1.5 km range only SF12 could be used for coverage. Based on such coverage range authors of [33] calculate a rough coverage planning for the city that has 100 km\({}^{2}\). With such a conservative coverage range, the whole city can be covered with only 30 gateways. In [34] Lora gateway was deployed on the second floor of a house in a suburban environment. Coverage using SF12 could go up to 2800 m with 20% PLR. The other tested SFs had lower coverage, SF7 having coverage of 650 m with 18% PLR while SF9 having coverage up to 2300 m with 12% PLR. Similarly, in [60] it was shown that in highly built areas LoRa coverage will decrease to less than 1 km for SF10. In Figure 6, the PLR from different studies for the same transmission configuration is shown. In general, it can be concluded that in city environments coverages up to a km can be easily achievable using SF7. For longer coverage that can go even beyond 2 km, higher SFs (SF12) should be used.  
In addition to outdoor environments, other authors studied the indoor coverage [35; 36; 37]. LoRa indoor coverage is sufficiently good, offering RSSI values that are even higher than \(-\)70 dBm [37]. Under such conditions, all SFs can be used for communication. In addition to indoor communication, LoRa can be used to offer communication in an industrial area of 34,000 m\({}^{2}\) only with SF7 [39]. By using higher SFs the coverage area can be extended even further. For other industrial applications the LoRaradio might be connected to a mobile object or a rotated object. Thus, in [61] an empirical evaluation to account for the impact of Doppler shift and angular velocity in LoRa performance has been presented. It is shown that when the end node moves with a speed of 100 km/h only one third of packets are received correctly. In addition, it is shown that under angular velocities higher than 78 rad/s LoRa communication using SF12 and 125 MHz channel bandwidth becomes unreliable with up to 50% packet losses.