Have a look at the German system. They are also bicameral. Their primary house, the Bundestag, is like the US Congress. The secondary house, the Bundesrat, is representing the 16 German states. The votes the representatives there cast are bound to decisions of their State governments. So the state government decides yes or no on a question, and all representatives of that state are bound to that decision of their state.
This way, the first chamber represents the overall interests if the people on a federal level, while the secondary chamber represets state interests.