Bluetooth Low Energy (BLE) is widely used in modern IoT systems because it consumes very little power, saves energy, and allows for simple device connectivity; however, maintaining security and communication reliability remains a challenge. In this paper, an authentication system is designed using industry-grade BLE-enabled nodes (nRF5340 development kit) that include a peripheral node with a keypad for entering a PIN and a central node with an LCD display. The entered PIN is sent wirelessly from the peripheral node to the central node via BLE technology, where it is verified in real time and displayed as correct or incorrect. Next, only after successful authentication can the peripheral node send data to the central node. In addition to authentication, the peripheral node can measure temperature in real time using the temperature sensor interfaced to it and send it wirelessly to the central node, where it can be displayed on the LCD interface. Received Signal Strength Indicator (RSSI) values are collected during experiments under various scenarios to evaluate the system's performance. We see that the signal strength (measured in terms of RSSI values) is strong at close range but weak as distance increases, indicating a decaying logarithmic pattern. The system also has low latency, which allows for quick input and output, and it uses PIN-based authentication to ensure security and prevent misuse. The entire system seamlessly integrates communication, sensing, and security, making it suitable for smart access control and wireless monitoring systems, including home automation.

翻译：蓝牙低功耗（BLE）因其功耗极低、节省能源且支持简单设备连接而广泛应用于现代物联网系统，但维护安全性和通信可靠性仍是一项挑战。本文利用工业级支持BLE的节点（nRF5340开发套件）设计了一套认证系统，该系统包含一个配备键盘可输入PIN码的外围节点和一个带有LCD显示屏的中心节点。输入的PIN码通过BLE技术从外围节点无线传输至中心节点，实时验证并显示正确或错误结果。仅当认证成功后，外围节点方可向中心节点发送数据。除认证功能外，外围节点还可通过连接的温度传感器实时测量温度，并将数据无线发送至中心节点，最终在LCD界面上显示。实验过程中，我们在不同场景下采集接收信号强度指示（RSSI）值以评估系统性能。结果表明，信号强度（以RSSI值衡量）在近距离时较强，但随着距离增加而减弱，呈现对数衰减模式。该系统还具备低延迟特性，可实现快速输入输出，并通过基于PIN码的认证确保安全性、防止滥用。整个系统无缝集成了通信、感知与安全功能，适用于智能门禁控制和无线监控系统，包括家庭自动化场景。