## 4 Integration of Biosensors
### Node Configuration
#### 4.2.2 Communications Protocol
This self-sustainable capability reduces the risk of data loss, and the scalability of mesh networks accommodates a growing number of devices, increasing overall robustness. The dynamic topology of mesh networks seamlessly adapts to changes, allowing nodes to join or leave without affecting connectivity. In multi-hop IoT scenarios, mesh networks extend coverage beyond the range of individual nodes, contributing to reliability although introducing some latency due to the multi-hop nature [67]. In contrast, dynamic routing in mesh networks optimizes the data paths to minimize communication delays. * Wi-Fi: A common wireless communication protocol in multi-hop IoT systems, it operates in the 2.4 GHz and 5 GHz frequency bands and uses the IEEE 802.11 family of standards for broad compatibility and high data rates [68]. It uses CSMA/CA for channel access and supports both infrastructure and ad hoc networking modes [69]. Wi-Fi's flexibility extends to multi-hop scenarios through mesh networking, improving coverage and reliability, which is critical in environments where direct communication between devices is difficult [70]. Its high data rates, suitable for bandwidth-intensive applications, work with TCP/IP for seamless Internet integration and broad device compatibility. Security is addressed through WPA3, which provides robust encryption and authentication, while WPA2 or WPA3 Enterprise enhances security in corporate environments. Despite the benefits of Wi-Fi, power consumption is a challenge, particularly for battery-powered IoT devices, so a balance between data speed and energy efficiency is required when designing effective multi-hop Wi-Fi IoT networks. * Zigbee: Based on IEEE 802.15.4 [71] and operating in the 2.4 GHz ISM band, Zigbee uses DSSS modulation for robust communication in multi-hop IoT systems. It uses CSMA-CA to minimize collisions, supports multiple topologies, and addresses with 16-bit and 64-bit identifiers [72]. Zigbee defines application profiles and clusters and adopts the Zigbee 3.0 standard for interoperability across vendors [73]. Efficiency is ensured, with security provided by AES encryption and authentication, and networks consist of coordinator, router, and end device types. The Zigbee stack, under Zigbee 3.0, improves the level of compatibility and is being used in smart homes and industrial IoT [74]. Despite advantages such as low power consumption and mesh networking, Zigbee faces challenges such as limited data rates and potential interference in the 2.4 GHz band. These issues need to be recognized in different applications to effectively implement Zigbee in multi-hop IoT systems. * Thread: A communication protocol tailored for the IoT is essential for building reliable multi-hop networks that operate over low-power wireless networks using an IPv6-based protocol. Its mesh topology allows devices to communicate directly, extending coverage through multi-hop communication and ensuring secure data transmission with banking-class encryption and authentication mechanisms [75]. Thread optimizes power consumption for low-power devices and supports sleep modes to extend battery life [76]. With its mesh topology, Thread scales effectively, accommodating a wide range of devices and increasing scalability. However, Thread provides a robust solution for multi-hop IoT networks with features such as mesh topology, IPv6 addressing, security, low-power operation, interoperability, dynamic routing, and scalability [77]. * Bluetooth low-energy mesh: Designed for low-power, short-range communications, BLE becomes a powerful solution for scalable, multi-hop IoT networks when integrated into a mesh topology [78]. In a BLE Mesh network, devices work together to relay data, extending coverage beyond point-to-point connections with flexibility and resilience [79]. BLE is particularly energy efficient, making it suitable for battery-powered IoT devices, which is critical in remote or impractical battery replacement scenarios [80].