Design a system that delivers firmware updates to devices.

Focus on the architecture of the system, including how updates are packaged, transmitted, and applied to devices. Consider the different types of devices that will receive updates and their connectivity options (e.g., Wi-Fi, cellular). Discuss mechanisms for ensuring the integrity and security of the updates, such as encryption and authentication. Address how to handle version control and rollback procedures in case an update fails. Finally, think about user experience: how will users be notified of updates, and what options will they have to schedule or defer installations?