Could coax be the dark horse?

Several companies are gearing up to offer whole-home networking over coaxial cabling

Last time we considered Serconet’s unique NetHome technology. Here, we’ll examine a promising, yet often overlooked, technology for multimedia networking: old-fashioned coaxial cabling.

Over the next few years, home network owners will want to send high-quality traffic such as video around the home, and current technologies are either short on speed or long on difficulty and cost.

Today’s wireless LAN technologies (802.11b, a and g) aren’t fast enough for MPEG-2 — the current standard for most digital video, including DVDs and HDTV — as it requires 15M bit/sec of true bandwidth. Nor does wireless have enough reach for whole home multimedia networking.

Ethernet is great, but requires stringing or installing Cat 5 cabling. HomePNA 3.0 is moving to 100M bit/sec, but support for this technology is fading fast. And products using HomePlug AV, the 100M bit/sec next-generation standard for power line networking, won’t be available until 2005.

That brings us back to coax, the standard black cabling that snakes into your cable set-top box. The reasons are many why coax should be considered for multimedia networking:

• High availability: Some 70 million U.S. homes have coax cabling installed 
• High bandwidth: Coax has more bandwidth than wireless LANs and other no-new-wires technology such as HomePNA and HomePlug
• Available spectrum: Coax has a lot of available spectrum (the frequency real estate that can be allocated to network traffic) — up to 200 times that of phone lines
• Location: Coax is installed where it should be for multimedia networking: behind the entertainment center
• Despite all these benefits, there hasn’t been any real concerted effort across the industry to push coax networking. In 2000, a company called Broadband Home started an industry standards body called the Home Cable Networking Association, but last year it fizzled out. While there had been plenty of interest, no one could agree on which technology to adopt.

There are a variety of companies working on coax network solutions. Silicon maker Broadcom envisions the HomePNA protocol running over coax cabling, and the company is working with Ucentric and Comcast to trial this technology in Philadelphia. (Currently, HomePNA runs over copper phone wiring.) Broadband Home, which changed its name to CrossBar Media, has developed a network system called Avcast that uses analog UHF channels to rebroadcast content from one device to another via coax. And Entropic, a fabless semiconductor company, is working on chips that enable 1394 and Ethernet to work as the transport protocols. 

However, Coaxsys is developing perhaps the most promising approach. The company is developing Ethernet-to-coax bridges that let consumers network any Ethernet device over existing coax. A bridge, which contains one coax and one Ethernet port, is required for each connection, and allow for fast Ethernet speeds, up to 100M bit/sec.

The only drawback is that you also must install a coax hub at the point where the coax enters the home. The hub acts as the network switch, controlling all connections for the network. Even so, this technology is a great fit if you want to do whole-home video networking or online gaming in a part of the home remote from the broadband modem. Coaxsys is expected to ship its first products midyear.