面向物联网设备的高效可靠OTA更新协议设计

Design of an Efficient and Reliable OTA Update Protocol for IoT Devices

摘要: 针对物联网设备软件在线升级过程中采用“停止–等待”协议传输文件效率低下问题，本文提出一种双层升级方案：传输层采用基于批量下发与接收方主动错误申请的选择性重传机制；存储层设计适配裸闪存的A/B分区原子更新架构。仿真采用马尔可夫突发丢包模型，对比传统停止–等待协议、CoAP分块传输与本文协议。结果表明：在1%~5%丢包率下，本文协议相比传统方案耗时降低84.4%~84.6%；相比CoAP同样降低约84.4%~84.6%。在5%丢包率下，传统协议成功率88.8%，CoAP为88.5%，本文协议达99.1%。在5%突发丢包环境下，传统协议成功率72.3%，CoAP为71.9%，本文协议达97.8%。本文还从理论上阐述了固件签名验签及控制消息重传机制，增强了安全性及鲁棒性。该方案为资源受限物联网设备提供了高效可靠的升级解决方案。

Abstract: To address the low efficiency of the “stop-and-wait” protocol in over-the-air (OTA) upgrades for IoT devices, this paper proposes a two-layer upgrade scheme. The transport layer adopts a selective retransmission mechanism based on batch distribution and receiver-initiated error requests; the storage layer designs an A/B partition atomic update architecture adapted to raw flash memory. The simulation uses a Markov burst loss model and compares the traditional stop-and-wait protocol, CoAP block-wise transfer, and the proposed protocol. Results show that under 1%~5% packet loss rates, the proposed protocol reduces upgrade time by 84.4%~84.6% compared with the traditional scheme, and by approximately 84.4%~84.6% compared with CoAP. At a 5% packet loss rate, the success rates are 88.8% (traditional), 88.5% (CoAP), and 99.1% (proposed). Under 5% burst loss, the success rates are 72.3% (traditional), 71.9% (CoAP), and 97.8% (proposed). This paper also theoretically elaborates on firmware signature verification and control message retransmission mechanisms, enhancing security and robustness. The proposed scheme provides an efficient and reliable upgrade solution for resource-constrained IoT devices.