## 5 Results and Analysis
### Interference Measurement Results and Analysis
The transmissions observed in this sub-band may originate from IEEE 802.15.4 technologies, wireless-M readings, and Sigfox, which share the same sub-band [49]. The last sub-band with signal activity in this area is the downlink 869.4-869.65 MHz, but rare transmissions mainly centred at 869.5 MHz with power levels at \(-107.03\) dBm were observed. The sub-band requires a 10% DC restriction or the implementation of LBT + AFA, and the intensity of signal activity shows fewer chances of signal interference, if any. The next measurement results, in Figure 10, were recorded from George Square. The sub-band 865-867 MHz signal activity was characterised by nearly continuous but weaker signals. Notable transmissions were centred at 865.7 MHz, 866.5 MHz, and 866.8 MHz with power levels at \(-107\) dBm, \(-109.8\) dBm, and \(-110\) dBm, respectively. The next sub-band, \(868.0\)-\(868.6\) MHz for mandatory LoRa channels, showed the variation of periodic strong and frequent weaker signals. These transmissions centred at \(868.1\) MHz, \(868.3\) MHz, and \(868.5\) MHz with power levels at \(-94.8\) dBm, \(-106.89\) dBm, and \(-79.20\) dBm, respectively. Moreover, strong transmissions centred at \(868.0\) MHz and \(868.3\) MHz at \(-78.44\) dBm and \(-79.3\) dBm, respectively, were observed in this area. Furthermore, the measurement observed weaker signal activity of \(3\) s periodic behaviour with the transmission centred at \(868.1\) MHz. Unlike the previous measurement results (Figure 9), weaker signals were observed at George Square in mandatory LoRa channels but at a  
The measurement results presented in Figure 11 were recorded from Kelvingrove Park. In the upper section of 865.0-868.0 MHz sub-band, infrequent multiple signal activity was observed with transmission centred at 867.3 MHz and 867.8 MHz with power levels at \(-\)79 dBm and \(-\)75 dBm respectively. The 868.0 MHz-868.6 MHz sub-band was highly occupied with signals of varying nature. The measurement results showed two periodic transmissions centred at 868.0 MHz with weaker signal power levels at \(-\)91 dBm and stronger signal levels at \(-\)78 dBm. There was activity of signals at roughly 2 s periodic behaviour centred at 868.1 and 868.3 MHz and power levels between \(-\)101.22 dBm and \(-\)93.9 dBm and another relatively strong signal activity with transmission centred at 868.5 MHz with power level at \(-\)77 dBm. The 869.4-869.65 MHz sub-band for LoRa downlink channels was occupied with three transmissions centred at 869.5 MHz. A transmitter emitted infrequent power levels at \(-\)107 dBm, whereas the other signals with power levels at \(-\)92.61 dBm and \(-\)91 dBm appeared frequently. As shown in Table 7, the probability of signals experiencing interference in mandatory LoRa uplink, 868.0-868.6 MHz and downlink, 869.4-869.65 MHz is 64.9% and 49.7%, respectively. The subsequent measurement was performed at Buchanan bus station, and the measurement results are presented in Figure 12. The signal activity was only observed in the audio sub-band, 863-865.0 MHz and the 865.0-868.0 MHz for RFID. The latter was occupied with frequent but discontinuous transmissions centred at 865. 7 MHz, 866.3 MHz, 866.8 MHz, and 867.5 MHz with power levels at \(-\)83.52 dBm, \(-\)78 dBm, \(-\)79.93 dBm, and \(-\)80.58 dBm, respectively. The signal activity in this sub-band was quite similar to signal activity observed in the same sub-band at GCU, with the difference being the power levels and the carrier frequencies. It was observed that an RFID-based [50] system could have been operating to track bus location and display the bus arrivals. Although no signal activity was observed in the mandatory LoRa channel for uplink, traffic was observed in 869.4-869.65 MHz sub-band for mandatory LoRa downlink channels. These signals were weak, with power levels varying between \(-\)103.5 dBm and \(-\)108.56 dBm. The probability