How can I extend a Wireless Network WIRELESSLY?

Hi,

I have a wireless network feeding all my desktops and notebooks upstairs and downstairs.

However, I have installed a DVR Camera system upstairs which can only connect to the Internet via a Network cable, but my wireless router is downstairs.

Please advise whether or not it is possible to install a wireless access point which would connect to my router downstairs and then connect to my DVR with a wired connection….