# Efficient Runtime Firmware Update Mechanism for LoRaWAN Class A Devices
## 3 Developed System
### Background--LoRaWAN Network Specifications
Based on this, the network server can initiate a downlink transmission at any time, assuming the end device's receiver is open, thus eliminating latency. The trade-off is the energy consumption of the receiver, making Class C suitable for applications with continuous energy availability [14]. For battery-powered devices, temporary switching between Class A and C modes is possible, which can be useful for intermittent tasks such as FUOTA updates [14]. LoRaWAN end device classes offer significant flexibility, allowing network optimization according to specific application requirements, balancing energy consumption, latency, and bidirectional communication capability. By carefully configure chirps, LoRa technology optimally combines range and energy efficiency for various IoT applications. The Spread Factor (SF) is a crucial parameter that determines the data transfer rate, receiver sensitivity affecting the link budget and the communication range (Table 1). A higher SF value increases receiver sensitivity, enabling longer communication ranges, lower data transfer rates, and higher energy consumption. Figure 1: Typical architecture of the LoRaWAN network. Conversely, a lower SF value results in faster chirps, leading to higher data transmission rates at the expenses of a reduced communication range [15] as shown in (Table 1). This means that by altering the SF, the coverage area of the network can increase or decrease, although this is achieved at the expense of transmission rate. Additionally, the LoRa network uses Spreading Factors to manage network access. Signals modulated with different spreading factors can be transmitted simultaneously on the same frequency channel because they are orthogonal and do not interfere with each other. This characteristic allows multiple devices to communicate at the same time on the same frequency without interference, optimizing network capacity [15]. Thus, LoRa modulation offers a robust and flexible solution for long-distance, low-power communication, meeting the requirements of IoT applications. Access to the LoRaWAN network requires compliance with rules regarding the duty cycle and the maximum number of communications with remote devices to avoid network congestion and ensure fair access. The purpose of the duty cycle limitation is to ensure that devices operating in the ISM band do not cause harmful interference to other devices operating in the same band. Thus, the number of uplink transmissions is limited to 30 s per day, and downlink transmissions to 10 messages per day [15]. In Europe, duty cycle limits range between 0.1% and 1%, depending on the channel used. This restriction aims to ensure fair and efficient use of the total available transmission time [16]. The maximum packet payload size also depends on the selected SF value (Table 1). The Things Network (TTN) is an open LoRaWAN platform that supports all existing operation modes A, B and C, regional parameters and stack versions, offering a community infrastructure for connecting IoT devices to the digital world as depicted in Figure 1. It provides services such as device registration, security key management, data routing, and more, facilitating the development and deployment of IoT solutions based on LoRaWAN [15].