## 2 LPWAN IoT Technologies
### Ingenu RPMA  
In 2010, Ingenu patented RPMA technology [29]. Ingenu has created LPWAN technology under the RPMA standard, providing a significantly larger connection capacity than SigFox or LoRa. It is mainly developed for machine communications and offers many advantages over conventional IoT and M2M connectivity solutions. Each access point can cover up to 300+ square miles, which is a superior range compared with cellular technologies. Ingenu RPMA is a technology that has been developed from the ground up using novel modulation techniques to decrease overall ownership costs while extending the range and increasing the link capacity compared with SigFox and LoRa networks. RPMA technology penetrates deeper and wider with high scalability compared with other wireless technologies, as shown in Figure 6. It aims to provide robust data transmission capabilities at a low cost and meet or exceed the data features that are expected by the industry based on cellular technologies. Efficient signal transmission handling plays an important role in achieving the required transmission gains. Among the significant features of transmission, one of its gains is the unit differences in signal power causing exponential coverage differences. RPMA attains its widest coverage by optimizing its receiver sensitivity, which results in a good signal power while maintaining a massive capacity. End devices may also alter their transmitting power to reach the nearest access point (AP) while minimizing  
Figure 5: Telensa UNB network architecture.  
interference with other nearby end devices. RPMA also maximizes the transmission power to the greatest extent permitted by government legislation by operating in the universal band and 2.4 GHz unlicensed, which allows for greater transmission power and offers a bandwidth of 80 MHz (up to 40 channels with a 1-MHz bandwidth and 1-MHz buffer). The RPMA is efficient, and its signal needs only a 1-MHz channel width for supporting an entire network. These important elements work together to provide a strong signal and industry-leading coverage per access point, as well as allow RPMA a great deal of freedom in terms of placing frequencies where there is less traffic [13]. However, because the 2.4-GHz frequency band is widely used by many other technologies, such as Bluetooth and Wi-Fi, there may be interference because the spectrum is more likely to be crowded.  
RPMA has a longer range in open space and a higher link budget [21]. RPMA is capable of demodulating up to 1200 signals at the same time when they are sent on the same frequency. A strict synchronization between the AP and end devices is maintained to ensure that the end devices transmit a signal that fits inside specified frames of a specific size. The number of possible signals that might have been transmitted in each frame is in the thousands. End devices transmit their signals with a random delay that is short enough to not exceed the size of the frame in which they are transmitted. Moreover, to select the signal delay, the end devices individually calculate the optimal spreading factor for transmission, depending on the measurement of the strength of the downlink signal. The RPMA AP does not need previous knowledge about the spreading factor that the end device will pick because the AP brute-forces its way through all potential spreading factors and delay durations.  
RPMA allows for bidirectional communication, although with minor link asymmetry. When utilizing DL communication, access points (APs) distribute signals for individual end devices before broadcasting them via CDMA. Ingenu stated that RPMA could achieve a receiver sensitivity of \(-142\) dBm and a link budget of 168 dB with a maximum link budget of \(-142\) dBm.