Harald Welte is a recovering Linux Kernel hacker with a history of hacking and developing (mostly open source) hardware, firmware and system-level software. Working in network protocols ever since the 1990s, he has dedicated the last 15 years of his life to spearheading Free and Open Source software in the domain of cellular networks.

He has worked extensively on implementations of cellular protocol stacks on virtually any interface at any protocol level from 2G to 4G - most of that in the context of the Osmocom project, which he co-started.

You can find more information on the (sadly rather infrequently updated) blog, and the usually more up-to-date fediverse presence at https://chaos.social/@LaF0rge