HPNA standards for Home Phoneline Networking Association is an organization that certifies products which implement ITU Recommendation G.989.1, a document that describes how to transmit data over existing telephone wires within the walls of your home. Devices based on HPNA 3.0 can reach speeds up to 128 Mbps, but can only reach other devices that are physically connected to the same "copper wire."
HPNA is not a wireless technology per se -- it just reuses wires that are already there. Wi-Fi is a true wireless technology because it connects mobile devices over the air. Also, HPNA is only intended for residential use inside homes. Wi-Fi is widely deployed in residential, commercial, and private business facilities. It can make sense to combine these technologies -- for example, using HPNA to connect your broadband router to your Wi-Fi AP, then using Wi-Fi to connect laptops to that AP.
This was first published in August 2006