Electronic Design

Alternative Tech Ready To Challenge Cable/DSL Lead

Today, broadband services in the form of cable TV and DSL lines give us high-speed Internet services as well as Voice over Internet Protocol (VoIP) in some areas. But these high-speed services are used by just over 20% of U.S. households, according to the Department of Commerce. It's a geographical and socio-economic situation. About 80% of U.S. households have an online connection, yet only about a quarter of those have the high-speed link. Compare that to Japan with over 80% high-speed connections and over 90% in Korea.

We're well behind. But as usual, it's less of a technology limitation than a combination of business and regulatory issues. Now, we're on the threshold of a renewed broadband expansion thanks to passive optical networks (PONs), broadband wireless access (BWA), and broadband over power lines (BPL). The technology is there. All we need is a viable business model and the investment.

For years, regional telephone companies have been losing wireline business. Most have replaced that lost revenue with cellular services, but a similar trend is seen as entities like cable TV companies roll out VoIP. To stay viable, the telephone companies must shift to Internet calling.

SBC and Verizon are installing PONs in selected areas that will give them probably the best all-around broadband medium possible. Nothing is faster than fiber optics, which can handle virtually any service once it's installed.

PONs are fully passive, short-haul metropolitan networks. They have no intermediate amplifiers, repeaters, or other equipment between the carrier and the subscriber. Optical-fiber cable and related components like splitters and combiners have the quality and cost today to permit runs of up to 20 km.

Speeds up to 100 Mbits/s are possible with broadband PON (BPON). This ATM-based protocol can handle high-speed Internet service as well as VoIP phones and even high-definition TV. The overall package won't be cheap, but it's in the price range of other high-speed services. Some systems will be fiber to the home (FTTH). Others will use the PON up to a neighborhood terminal and then some form of fast DSL over the existing telephone twisted pair for the last hundred feet to the house. This will cut costs further but impair the bandwidth.

PONs will change the broadband market and bring some competition to the field. Just maybe, PONs will finally provide a path for high-definition TV, which has been waiting in the wings for years.

But there's still room for skepticism. Is cable TV so entrenched at this time that telephone companies won't be able to get a foothold? And if they do, will the cable companies retaliate by entering the cell-phone business, as some are now exploring?

The idea of using wireless for Internet connectivity and other broadband services to the home has been around for years. Now, the technology is ready to make that happen. A new standard, IEEE 802.16, has emerged with specifications and features that appear to make it a contender in the broadband race.

Also known as WiMAX, the name of the industry consortium supporting the standard, this system provides wireless links of up to several miles with a nearby basestation. The links use available bands in the 2- to 11-GHz range (3.5 and 5.8 GHz). And thanks to the adoption of orthogonal frequency-division multiplexing (OFDM), the line-of-sight (LOS) problem associated with previously unsuccessful systems seems to be solved. The system also provides variable data rates up to 100 Mbits/s, depending on the service you buy and your location with respect to the basestation.

That kind of service will offer the high-speed Internet connectivity that we want, not to mention the VoIP and even video that will eventually be offered. It will certainly be a godsend to people living in smaller towns and rural areas (ex-urban) not currently served by any broadband service other than satellite TV.

The 802.16 standard includes the 802.16e revision, which provides alternative technologies to permit access by computers moving at speeds up to 90 mph or so. A new standard, IEEE 802.20, also is being developed to further improve upon mobile access.

These two standards will compete. It's unclear which one will ultimately predominate. Lest we forget, the cell-phone 3G standards also call for high-speed Internet access from moving vehicles at rates up to 2 Mbits/s. That seems like too much competition for a relatively small mobile niche. Let the market decide.

Using the existing ac power lines to carry high-speed digital data seems like a less than stellar idea. Yet that's the definition of BPL, which makes it possible to transmit at data rates up to 2 or 3 Mbits/s in some cases. While a more typical rate is less than 500 kbits/s, that's still pretty impressive for a transmission line optimized for 60 Hz. It's done using techniques like discrete multitone (DMT), a form of orthogonal frequency-division management (OFDM) used in DSL.

The Federal Communications Commission gave final approval to BPL in October of 2004. Furthermore, several electrical utilities have been testing the concept over the past few years. Generally it works well, but its main downside is the massive electromagnetic interference (EMI) it causes some radio services. The utility companies and the equipment manufacturers both have taken steps to minimize the problem, but it still exists.

The ham's voice in Washington, the American Radio Relay League, has been relentless in beating on the FCC to stop BPL or at least solve the problem. While some progress has been made, problems still exist for the hams.

If you can ignore EMI, BPL does make some sense for electrical utilities because they'd get multiple duty from their massive wired network. It gives consumers one more broadband option, one that can be bundled with our electric bill. We could conceivably even get VoIP this way.

The electrical utilities could fully implement remote automatic meter reading. They can monitor energy usage, power outages, and impending faults. If fully implemented, BPL could also help meet the elusive goal of demand management, the ability to charge customers different rates for the electricity they use at different times (especially at peak times). A huge investment is necessary to make BPL happen, but it just may be successful in some areas, mostly rural.

Hide comments


  • Allowed HTML tags: <em> <strong> <blockquote> <br> <p>

Plain text

  • No HTML tags allowed.
  • Web page addresses and e-mail addresses turn into links automatically.
  • Lines and paragraphs break automatically.