基于FreeRTOS的LoRa网络节点操作系统的研究

无线传感器网络是物联网的一个重要组成部分，它是一种基于无线通信技术的分布式网络系统，由多个无线传感器节点组成，用于收集环境中的物理或化学信息，将物理世界的信息转化为数字信息，并通过无线网络传输给远程云端系统。从而实现自动化的数据采集，实时监测和管理等功能。然而，随着 5G 等高速通信技术的发展，物联网在多个应用领域中技术落地加速，同时也给无线传感器网络带来了新的挑战。例如，5G 技术虽然可以涵盖多种场景，但不适用于低密度、低速率、低功耗、远距离物联需求。LoRa 和 NB­-IoT 等无线通信技术以其低功耗、长距离、低成本的优势弥补了这些需求，但同时也存在无可靠操作系统等技术瓶颈。

过去传感器节点由于硬件平台性能有限，只能部署基于轮询或前后台的嵌入式系统，以实现对节点高效的控制。然而，面对如今日益复杂的应用需求，体系结构、性能各异的硬件平台和多样的无线通信技术，传统的嵌入式系统已经无法满足各种需求。而操作系统可以为传感器网络供资源管理、调度、安全等服务，同时为嵌入式设备供应用程序开发框架，以支持物联网应用的二次开发。因此，为传感器网络终端节点设计一个合适的操作系统至关重要。

本论文以 LoRa 通信技术和 FreeRTOS 实时操作系统内核为研究基础，拓展了系统对 LoRa 无线通信技术的支持，实现了 LoRa 网络终端节点的操作系统平台。 为了优化系统对 LoRa 中断处理的实时性和减少资源消耗，提出了多状态机系统框架和基于时间片调度的时钟管理子系统，替代了部分系统接口，为内核提供了裁剪空间。系统使用不同优先级的状态机分别管理系统线程和中断请求，将中断线程化处理，提高中断整体响应速度。最后，通过实验验证了该方案的有效性，降低了系统中断响应延迟，并减少了系统在资源上的消耗，占用更少的内存，且更加节能。

Wireless sensor networks (WSNs) have become a vital component of the Internet of Things (IoT) infrastructure, enabling the collection of physical and chemical information from the environment through distributed networks of wireless sensor nodes. The cap­tured data is then digitized and transmitted through a wireless network to a remote cloud system, enabling real­-time monitoring and management of the physical environment. However, the rapid proliferation of high­-speed communication technologies, such as 5G, has accelerated the implementation of IoT in diverse application fields, and presented new challenges to WSNs. Although 5G technology can support various scenarios, it is not well­-suited for low-­density, low­-speed, low-­power consumption, and long­-distance IoT requirements. Consequently, wireless communication technologies like LoRa and NB­-IoT have been developed to meet these specific needs. However, these technologies are not without their challenges, such as the lack of reliable operating systems.

In previous times, the performance limitations of hardware platforms hindered the deployment of embedded systems, necessitating alternative solutions to achieve efficient control of sensor nodes. However, with the emergence of increasingly complex applica­tion requirements and a variety of wireless communication technologies, traditional em­bedded systems are no longer sufficient to meet diverse needs. Operating systems offer resource management, scheduling, security, and other services for sensor networks, while also providing an application development framework for embedded devices to support the secondary development of IoT applications. Therefore, the development of a suitable operating system is critical for WSN end nodes.

This thesis presents the development of an operating system platform for LoRa net­ work end nodes that leverages LoRa communication technology and the FreeRTOS ker­nel. To optimize the real­-time performance of the system in LoRa interrupt processing and reduce resource consumption, we propose a multi­-FSM system framework and a clock management subsystem based on time slice scheduling. This framework replaces the original system interface and provides cutting space for the kernel. And the proposed system utilizes state machine with varying priorities to manage system threads and inter­rupt requests separately, resulting in threaded interrupt processing and improved the over­ all response speed of interrupts. Experimental verification of the system’s effectiveness demonstrates a reduction in the system interrupt response delay, resource consumption, and memory usage, leading to increased energy efficiency.

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