# LoRa Resource Allocation Algorithm for Higher Data Rates
## 3 LRA Algorithm Framework
### Resource Allocation Algorithm
\begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline
**BW (kHz)** & **SF** & **Delay (ms)** & **RSSI (dBm)** & \(T_{tx}\) **(s)** & \(E_{tx}\) **(l)** & \(E_{rx}\) **(l)** & \(E_{total}\) **(l)** \\ \hline \multirow{2}{*}{125} & 7 & \multirow{2}{*}{700} & \(-41\) & \multirow{2}{*}{32.971} & \multirow{2}{*}{9.46} & \multirow{2}{*}{1.25} & \multirow{2}{*}{10.71} \\ \cline{2-2} \cline{5-8}  & 8 & & & & & & \\ \hline \multirow{2}{*}{250} & 7 & \multirow{2}{*}{400} & \(-41\) & \multirow{2}{*}{19.153} & \multirow{2}{*}{5.49} & \multirow{2}{*}{0.727} & \multirow{2}{*}{6.217} \\ \cline{2-2} \cline{5-8}  & 8 & & & & & & \\ \hline \multirow{2}{*}{500} & 7 & \multirow{2}{*}{250} & \(-47\) & \multirow{2}{*}{12.255} & \multirow{2}{*}{3.52} & \multirow{2}{*}{0.465} & \multirow{2}{*}{3.985} \\ \cline{2-2} \cline{5-8}  & 8 & & & & & & \\ \hline \hline \end{tabular}
\end{table} 
Table 3: \(T_{tx}\) results for parallel transmission of a 24 kB image over the LC on other SF combinations. In the next trial, the total transmission times using our proposed algorithm is compared with a single transceiver setup. In this regard, the same experiment is repeated using a single LoRa module at the transmitter and receiver operating on SF = 7. This time, the whole string of bytes is formed into equal sized packets and fed into the buffer of the transmitter. Table 4 shows the \(T_{tx}\) for different BWs. In this case, the packet processing times are lower than the parallel transmission as no further delay is required for synchronizing a concurrently received packet. However, the overall transmission times are significantly longer compared to specific parallel SF combinations. The underlying reason is the synchronization and distribution of data packets during parallel transmission. The proposed LRA algorithm assigns dedicated data segments to each LoRa radio in a synchronized manner, enabling simultaneous packet transmissions. This approach not only facilitates multiple transmissions at once but also reduces the total number of packets sent over each LoRa channel, ultimately leading to lower overall transmission times. Figure 9 demonstrates the effect of different SF combinations on the \(T_{tx}\) compared to a single setup operating solely on SF = 7. In a single transceiver setup, the fastest transmission occurs with SF = 7, excluding SF = 6 due to its unavailability in some modules. As shown in Figure 9, the \(T_{tx}\) can be significantly improved using SF combinations of 7 and 8 or 7 and 9. Other SF combinations fail to enhance \(T_{tx}\), as higher SFs lead to increased transmission times. The percentage of improvement for each parallel setup is detailed in Figure 10. The combination of SFs 7 and 8 improved the \(T_{tx}\) by 42.36%, 34.27%, and 38.16% for BWs of 125 kHz, 250 kHz, and 500 kHz, respectively. Meanwhile, the parallel setup with SFs 7 and 9 achieved improvements of 19.98%, 13.84%, and 15.43% for the same BWs. The performance of SF combinations that enhance \(T_{tx}\) compared to a single transceiver setup is evaluated in terms of BR. Figure 11 presents the BR of a single LoRa channel \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline
**BW (kHz)** & **SF** & **Delay (ms)** & **RSSI (dBm)** & \(T_{tx}\) **(s)** & \(E_{tx}\) **(J)** & \(E_{rx}\) **(J)** & \(E_{total}\) **(J)** \\ \hline
125 & 7 & 550 & \(-45\) & 57.205 & 16.42 & 2.17 & 18.59 \\ \hline
250 & 7 & 300 & \(-40\) & 29.138 & 8.37 & 1.10 & 9.47 \\ \hline
500 & 7 & 200 & \(-41\) & 19.816 & 5.69 & 0.75 & 6.44 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: \(T_{tx}\) results of the same image transmission over a single transceiver setup with different BWs. Figure 9: Transmission time for sending the same image over different parallel setups compared with a single transceiver setup. operating on SF = 7, as well as LCs utilizing SF combinations of 7 and 8 and 7 and 9, while accounting for packet processing times. When SF = 7 and 8 are employed, the BR increases by 73.5%, 52.13%, and 61.7% for BWs of 125 kHz, 250 kHz, and 500 kHz, respectively.