NoSQL databases are often preferred for IoT data storage because they excel at handling large volumes of unstructured or semi-structured data. IoT devices generate a wide variety of data types, and NoSQL databases provide the flexibility and scalability required to store and query this data efficiently.

Code signing is essential to guarantee that biometric devices are running only authentic firmware. It verifies the authenticity and integrity of the firmware, preventing unauthorized changes. Firmware updates are important but don't guarantee authenticity. Hardware redundancy and intrusion detection systems focus on system reliability and security but not specifically firmware authenticity.

When your smartwatch notifies you of a new message, it's a classic example of M2H (Machine-to-Human) communication. The smartwatch (machine) is relaying information to you (human), indicating a message has arrived.

In the context of real-time communication in IoT with minimal bandwidth usage, MQTT (Message Queuing Telemetry Transport) is a widely considered protocol. It is a lightweight publish-subscribe messaging protocol, designed for constrained devices and low bandwidth scenarios, making it a suitable choice for smart city projects.

5G's ultra-high data transfer speeds are a game-changer for IoT, allowing the rapid exchange of data between devices, enabling new IoT applications.

Post-deployment monitoring and maintenance activities are part of the Operations phase in the IoT project lifecycle. This phase involves ensuring the continued functionality, security, and optimization of the deployed IoT system.

During the Testing phase of the IoT project lifecycle, the system's performance is evaluated against the defined objectives to ensure that it meets the requirements and functions correctly.

Street lights not adapting to the environment could be due to sensor calibration errors. If the sensors are not correctly calibrated, they may not accurately perceive the changing environmental conditions and, consequently, may not trigger the desired adjustments in the street lights. Regular calibration and maintenance are essential.

Battery life is often the most critical factor when considering power management for IoT (Internet of Things) devices. IoT devices are frequently deployed in locations where it is impractical to replace or recharge batteries frequently. Therefore, maximizing battery life is crucial to ensuring the longevity and reliability of IoT deployments.

Bluetooth is not typically considered a standard protocol in IoT communications. While HTTP, MQTT, and XML-RPC are commonly used in IoT applications, Bluetooth is more commonly associated with short-range, point-to-point wireless connections between devices, making it less prevalent in broader IoT scenarios.