Every year, students grow, learn and contribute to new findings, as they carry out their master thesis projects at QRTECH. Following up on a very promising bachelor thesis [1] from the spring of 2021, QRTECH invites two computer science students to examine the field of delta-updates over low bandwidth radio. This is a great opportunity for you to conduct secondary research and contribute to new findings!

Background

Many resource-constrained Internet of Things units are used in a manner which makes them inaccessible via cable and at the same time unable to receive large amounts of data using radio transmissions. Upgrading firmware is hence difficult or in some cases impossible. Integrating support for delta updates in the unit is a potential solution to this problem, as it significantly reduces the payload during an upgrade scenario. Delta-updates is a method where the difference between the new and old firmware is transferred instead of a complete firmware image.

LoRa is a long range, low power wireless platform that is becoming widely used by Internet of Things devices, many of them being power constrained by battery life requirements. There have not been any really good options to perform firmware upgrades over the air (FOTA) on LoRa, as it has very limited bandwidth, especially downstream to the devices, combined with a risk of frequent packet losses. Methods to improve this exist, but they require the devices to operate in a different power mode, rapidly decreasing battery life.

The aforementioned thesis work [1] investigates and demonstrates an implementation of delta-updates as an addition to Zephyr RTOS [2].

Thesis proposal

It will be up to the students in cooperation with their supervisors and examiner to define the exact scope of work, but these are some topics of interest:

State of the art for FOTA over LoRa

Investigate the different methods of achieving FOTA over LoRa that are in use or being proposed today. Are there techniques that can be applied to this thesis work and can the weaknesses listed in the background description be confirmed?

Constraining the delta-updates

When source code is compiled into a binary firmware, the compiler can be expected to generate compact and efficient code, preserving memory footprint and execution time. This may not be beneficial from a delta-update perspective, where we want to minimize the binary differences following a source code modification, so compromises or some innovative methods may be needed.

Investigate techniques that can be applied to the firmware development process to constrain the size of the delta-updates. How can tools be modified and what is the firmware developer required to do or know? This part can be purely theoretical or it can also be proven by implementation.

Demonstration of delta-updates over LoRa

This part of the thesis will be to propose a method for low-power, low-bandwidth updates of Zephyr based firmware over LoRa. The method shall be demonstrated as a proof-of-concept implementation. The method and its results shall be documented and evaluated.

Proposal for future work

This part of the thesis will be to propose what future work can be done to transform the thesis results into an industrial solution that can eventually be upstreamed as a contribution to the open-source Zephyr project.

References

[1] Linnéa Lindh, Delta Updates for Embedded Systems - An Implementation of 

Firmware Patching for Zephyr RTOS, Chalmers University of Technology, 2021. [Online]. Available: https://gitlab.endian.se/thesis-projects/delta-updates-for-embedded-systems

[2] Zephyr Project, ”About the Zephyr Project”, 2020. [Online]. 

Available: https://www.zephyrproject.org/learn-about/