combine multiple internet connections

I am using an internet connection through a router via lan access, but as my bandwith is low, I am also using in addition phone internet connection shared via USB.
When I am downloading big file, only one internet connection is used at a time but never both connections together.

If possible, it could be great to aggregate multiple internet connections together to speed up the download of big file.
Or spread download chunks to each internet connections depending on speed of these internet connections.