Sync-TCP is based on Reno's congestion control, but in addition adapts its cwnd according to changes in one-way delay.
The name "Sync-TCP" is actually a misnomer - the developers initially assumed synchronized clocks between the two TCP endpoints, but it turns out that this isn't actually required by the protocol.
References
Delay-based early congestion detection and adaptation in TCP: impact on web performance, M.C. Weigle, K. Jeffay, F. Donelson Smith, to appear in: Computer Communications. Preprint: http://www.cs.odu.edu/~mweigle/papers/comcom05-preprint.pdf
Sync-TCP in high-speed environments, A. Khan, D.M. Shah, Z. Xu, Proc. 43rd annual ACM Southeast Regional Conference, Vol. 2, 2005 - ACM portal