The article uses the term "CCAs" without ever defining it. I followed the links, and googled it, with no useful result.
What is a CCA in this context?
After some searching apparently it means “congestion control algorithm”. Definitely should have been defined in the article, especially since they have a whole section dedicated to explaining what it is.
Congestion Control Algorithms
a Congestion Control Algorithm -- which uses various signals (mostly dropped packets) to try to estimate the available bandwidth and avoid network connection.