Electronic Design

A Dizzying Mix Of Standards

When it comes to home networking, wireless still dominates. Thanks to the Wi-Fi Alliance, all IEEE 802.11 wireless local-area products (WLAN) products work with one another. Using one standard with its interoperability and backward compatibility makes it easy for consumers to set up, use, move, and change all of their devices with minimal problems.

But that’s not the case with wired communications. The only wired communications standard you can depend on is Ethernet, and very few homes are fully wired with CAT5 or CAT6. Instead, we have a real mix of wired standards that use the existing telephone wiring, coax from the cable connections, or the ac powerline. There are multiple variations for each of those media, too. Furthermore, none are compatible.

This has led to a huge fragmentation in the home networking marketplace and mass confusion among consumers as to which one is best for them. While some standards do exist, they are all essentially isolated islands of technology where even backward compatibility often doesn’t exist from one version of the standard to the next.

Because of the widespread differences, few standards have achieved the critical mass to claim victory. Most of the chip vendors and customer premise equipment (CPE) manufacturers have not seen the volumes they need to be fully profitable. Yet up to this point, most of them have stuck to their guns defending their technology and standard. None of them has come close to meeting or beating wireless. Of course, the potential is there.

The latest version of the Home Plug Powerline Alliance (HPPA) standard, HomePlug AV, uses advanced physical-layer (PHY) and media access controller (MAC) technologies that provide a 200-Mbit/s powerline network for video, audio, and data. HomePlug has the greatest number of powerline products in the marketplace.

The High-Definition Power Line Communications Alliance (HD-PLCA) standard is popular here and in Japan. It promises data rates to 210 Mbits/s on the ac powerline. The Universal Powerline Association (UPA), which offers a different standard for powerline communications, has sought to establish a worldwide standard for this technology.

IEEE P1901 was the IEEE’s attempt at creating a standard that everyone could agree upon—or at least at providing some compatibility. It features a dual-PHY approach to both major types of orthogonal frequency-division multiplexing (OFDM) and multiple coding options.

The HomePNA Alliance (HPNA) standard uses either the coax cable wiring or the standard twisted-pair telephone wiring in the home. In its latest variation, it can achieve 320 Mbits/s. AT&T’s U-verse Internet Protocol television (IPTV) distribution system uses it.

The Multimedia over Coax Alliance (MoCA) standard uses the installed base of coax for cable TV in most homes. It sends data backward through the splitters to cover all outlets and can achieve a data rate of 175 Mbits/s. The Verizon FiOS fiber-optical network uses MoCA for broadband connectivity in the home with the Verizon service.

All of these standards, except HPNA and MoCA, use the ac power wiring in the home as the transmission medium. They also all have products in the field. The PHY technology in all cases is some variation of OFDM, including both fast Fourier transform (FFT) and wavelet processes, the only modulation technology with the robustness to stand up to the noisy ac line. HPNA and MoCA use the cable TV coax that exists in most homes today. It too uses OFDM.

None of these standards has won a majority of home or small-office networking customers to dominate or even give wireless a good competitive run. The solution seems to lie in creating a common wired standard that all can agree to and have some form of compatibility.

Some extremely clever engineering has led to high-capability technologies. Each achieves the goal of successful home networking up to a point. The older technologies are already in their second or third generations. Nevertheless, no one has broken through to lead the pack. Many companies decided it was time for action to remedy the situation. The result has been a common standard, G.hn. For more, see “G.hn Standard Promises Compatibility At Home”.

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