BEIJING — A Chinese court has sentenced a democracy advocate who started several online groups and participated in political discussions to eight years in prison on the charge of inciting subversion.

Cao Haibo’s sentencing comes as China prepares for a once-in-a-decade leadership transition that kicks off Nov. 8. In the lead-up to the opening of the Communist Party congress in Beijing, authorities have intensified pressure on activists, dissidents, and lawyers around the country.