Energy-aware Incremental OTA Update for Flash-based Batteryless IoT Devices

TL;DR

The paper tackles the challenge of performing firmware OTA updates on batteryless IoT devices powered by energy harvesting, where memory is scarce and energy is intermittent. It introduces an energy-aware incremental OTA update framework that uses segment-based update packets, defers flash writes, and enables checkpoint-free resumption to reduce both energy consumption and total update time. Experimental results show EA achieves lower energy use in most benchmarks and comparable or faster update times than state-of-the-art approaches, highlighting its practicality for energy-constrained, flash-based devices. The approach offers a scalable path for secure, remote firmware maintenance in large batteryless IoT deployments.

Abstract

Over-the-air (OTA) firmware updates are essential for updating and maintaining IoT devices, especially those batteryless devices reliant on energy harvesting power sources. Flash memory, favored for its low cost and high density, is extensively used for data storage in many IoT devices. However, due to its high energy demands for update operations, there is often insufficient energy for code updates. This paper proposes an incremental flash-based OTA update approach tailored for energy harvesting IoT devices, tackling the challenges brought by limited memory resources and fluctuating energy availability. Our approach is composed of three techniques: segmentbased update packet design, deferred flash segment writes, and checkpoint-free update resumption. Segment-based update packet design segments firmware updates into smaller packets, each tailored for specific memory segments, thereby minimizing unnecessary flash operations and conserving energy. Deferred flash segment writes accumulate packets in Static Random-Access Memory (SRAM) for collective processing, reducing the frequency of energy-intensive operations. Crucially, our checkpointfree update resumption ensures efficient recovery from power interruptions without significant energy cost on data backup. Through thorough experimental evaluation, we have observed that our approach significantly reduces the total energy consumed during OTA updates, and decreases the average total update time in energy harvesting environments.

Figures (8)

• Figure 1: NOR Flash Memory Cell During Erase and Write Operations ti_flash
• Figure 2: The Overview of the Proposed Approach
• Figure 3: Segment-Based Update Packet Design Payload Structure
• Figure 4: The Steps of Deferred Flash Segment Writes
• Figure 5: Update Resumption with Power Constraints