## Conceptual Scheme
### Personal LoRa Node  
The personal LoRa node is composed of an ESP32-based MCU with the various sensors coupled and placed in areas that do not interfere with the user's daily life, therefore being as unintrusive as possible. The ESP32 MCU allows a battery saving mode (Deep Sleep Mode) that is only activated during the scheduled period, collecting and sending the data at that moment. Considering that one of the built-in sensors is the gyroscope, whenever there is a sudden change, due to a fall, for example, it can automatically activate the MCU by programming a General Purpose Input/Output (GPIO) interruption of the Real Time Clock (RTC). The ESP32 MCU consists of several modules (Figure 4b) and can operate in the following modes, as it seen in Table 2[58]:  
* Active Mode: the chip radio is powered on. The chip can receive, transmit, or listen. * Sleep Mode Modem: the CPU is operational and the clock is configurable. The Wi-Fi/Bluetooth baseband and radio are disabled
* Light Sleep Mode: the CPU is paused. The RTC memory and RTC peripherals, as well as the Ultra-Low Power (ULP) co-processor, are running. Any wake-up events (MAC, host, RTC timer, or external interrupts) will wake up the chip. * Deep Sleep Mode: only the RTC memory and RTC peripherals are powered on. Wi-Fi and Bluetooth connection data are stored in the RTC memory. The ULP co-processor is functional. * Hibernation Mode: the internal 8-MHz oscillator and ULP co-processor are disabled. The RTC recovery memory is powered down. Only one RTC timer on the slow clock and certain RTC GPIOs are active. The RTC timer or the RTC GPIOs can wake up the chip from Hibernation Mode. ESP32 has 34 GPIO pins that can be assigned several functions by programming the appropriate registers. There are several kinds of GPIOs: digital-only, analog-enabled, capacitive-touch-enabled, among others. Analog-enabled GPIOs and capacitive-touch-enabled GPIOs can be configured as digital GPIOs. The ESP32 Pin Layout is shown in Figure 4a. MCU ESP32 contains one or two low-power Xtensa 32-bit LX6 microprocessor(s) with several features, namely a seven-stage pipeline to support a clock frequency of up to 240 MHz (160 MHz for ESP32-S0 WD, ESP32-D2 WD, and ESP32-U4 WDH) and a 16/24-bit instruction set that provides high code density, among others[58]. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Power Mode** & **Description** & \multicolumn{2}{c}{**Power**} \\  & & **Consumption** \\ \hline Active (RF & \multicolumn{2}{c}{Wi-Fi Tx packet} & \\ working) & \multicolumn{2}{c}{Wi-Fi/BT Tx packet} & 160 mA\(\sim\)260 mA \\  & \multicolumn{2}{c}{Wi-Fi/BT Rx and listening} & \\  & & 240 MHz & Dual-core chip(s) & 30 mA\(\sim\)68 mA \\  & & Single-core chip(s) & N/A \\  & The CPU is & \multicolumn{2}{c}{Dual-core chip(s)} & 27 mA\(\sim\)44 mA \\ Modem-sleep & powered on & 160 MHz & Single-core chip(s) & 27 mA\(\sim\)34 mA \\  & & Normal speed: 80 & Dual-core chip(s) & 20 mA\(\sim\)31 mA \\  & & MHz & Single-core chip(s) & 20 mA\(\sim\)25 mA \\ Light-sleep & & - & 0.8 mA \\  & & The ULP co-processor is powered on & 150 uA \\ Deep-sleep & \multicolumn{2}{c}{ULP sensor-monitored pattern} & 100 uA @1\% duty \\  & & RTC timer + RTC memory & 10 uA \\ Hibernation & \multicolumn{2}{c}{RTC timer only} & 5 uA \\ Power-off & \multicolumn{2}{c}{CHIP\_PU is set to low level; the chip is powered off} & 1 uA \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Power consumption by power modes (source: [58]). Therefore, via the ESP32 MCU, the Deep Sleep battery-saving mode can be activated, which will have an extremely low power consumption. In this mode, the CPUs, most RAM and all clocked digital peripherals are turned off. The only parts of the chip that can still be connected are the RTC controller, RTC peripherals (including the ULP coprocessor) and RTC memories. This device has several ways of activating ESP32 when in Deep Sleep mode, and wake-up sources can be set up at any time before entering Deep Sleep mode.