HomePlug AV is specified as a "200 Mbps" technology, but testing suggests that it delivers only a limited percentage of that speed in real-life usage environments. Why was the "200-Mbps" peak PHY rate chosen as the technology designator? What range of TCP (transmission control protocol) and UDP (user datagram protocol) speeds do you believe most consumers will experience in real-life settings, and what kinds of applications are supportable (and conversely unsupportable) by those speeds, both in single- and multiple-coincident-data-stream situations? And do you address potential consumer confusion and frustration, when they don't get the performance results that the "200-Mbps" stamp on the outside of the product box might otherwise suggest they'll achieve?

There is some confusion about this in all data-communications communities, including wireless ones. Take, for example, IEEE 802.11g Wi-Fi, which is known as a 54-Mbps technology. 54 Mbps is the PHY rate minus forward error correction bits. The standards bodies, during technology and specification development, decide which type of PHY rate they will associate with their standard. In the case of 802.11g, 54 Mbps is the coded PHY rate, as opposed to the higher raw PHY rate (a little over 70 Mbps). Few consumers are aware of this distinction. Even so, it allows the Wi-Fi standards people to churn out different standards classes with the same apples-for-apples PHY rating.

Regarding HomePlug AV, 200 Mbps is the raw PHY rate, which includes forward error correction bits. This approach follows that of the wireless technologies—associating a PHY rate with each wireless standard. Some of our customers who market in retail state on their boxes what UDP and TCP rates consumers should expect.

The user-datagram protocol is the fastest medium access control (MAC), protocol because it does not require acknowledgements to each packet sent. It finds use for streaming music and video, and for VOIP telephony. Our tests have shown that HomePlug AV typically delivers a UDP rate across the home in the 50- to 90-Mbps range, depending on noise and attenuation.

The transmission control protocol is slower than UDP, but is more careful, checking to make sure that each packet was successfully received and, if necessary, repeating the transmission. HomePlug AV typically delivers a TCP rate across the home in the 30- to >60-Mbps range, depending on noise and attenuation.

A protocol that many use to judge the performance of a digital technology is Windows File Transfer. This protocol runs under TCP and is therefore even slower than TCP. The peak Windows File Transfer throughput for HomePlug AV is around 36 Mbps.

It is important to understand that whether the technology is wired or wireless, this hierarchy of protocol performance is always true. We need more editors to understand this to help us educate the public.