By far, the most widely used broadband technology to access the Internet around the world today is DSL. Over 70% of broadband connections in Japan and Korea are DSL, while penetration in Europe is approximately 60%.
In the U.S., cable TV companies dominate broadband. But DSL isn't far behind, with about 46% of total connections. In fact, DSL growth is estimated at 15% to 20% annually, so it's expected to pass cable TV sometime this year as the dominant broadband technology in the U.S.
That says a lot, considering DSL uses the century-old #26 AWG twisted pair of the plain-old telephone system (POTS). Nevertheless, DSL is alive and well. In fact, it's expected not only to continue its growth in the U.S., but to become even better to meet the telcos' triple-play plans.
While growth figures for DSL are attractive, they don't tell the whole story. The Government Accountability Office report last year indicated that only 58% of U.S. households had any sort of Internet access, with 30% using dialup and 28% using broadband (cable, DSL, satellite). Another study from the Pew Internet & American Life Project showed that 42% of U.S. citizens have access to a broadband connection, the majority of whom reside in cities and the suburbs.
Rural areas are really underserved, with only an estimated 25% having any kind of high-speed Internet connection. (Yet AT&T and Verizon—the two largest DSL providers—claim to offer DSL service to 80% of their subscribers). This shortage won't be easily resolved, as the telcos and cable TV companies usually don't think it's profitable to provision so few customers in such remote areas.
Together, these factors leave a huge opening for some reasonably priced satellite technology or other wireless option. Satellite broadband connections are already available in some areas where satellite TV service is available. But the opportunity is a reality for DSL providers because the wiring is there. All they need to do is enable the service.
Flavors Of DSL
All DSL systems are based on orthogonal frequency-division multiplexing (OFDM), which divides the high-speed bit stream into many slower parallel streams and modulates each on adjacent carriers. The telcos refer to OFDM (also known as multicarrier modulation) as discrete multitone or DMT. Several versions are being implemented, and ADSL is the most widely used by far.
A Fresh Example
Texas Instruments' UR8 residential gateway architecture chip set exemplifies the latest trends and features based on DSL (see the figure). Designed for home gateway boxes, the chips cover all the latest DSL offerings, including the newest VDSL2 standard.
Also, these chips feature a multimedia gateway processor, a programmable DSL physical layer (PHY), a high-performance DSP-based voice subsystem, and a rich set of local-area network (LAN) interfaces. A well-defined application program interface (API) reduces time-to-market by allowing hardware and software reuse across all DSL platforms.
This chip set lets residential gateway designers handle Voice over Internet Protocol (VoIP), as well as multiple methods for distributing broadband services within the home. Some of the home networking technologies supported include Ethernet, Wi-Fi, and standards offered by the HomePlug Powerline Alliance, Multimedia over Coax Alliance (MoCA), and the Home Phoneline Networking Alliance (HomePNA).
No one knows which home networking technology will dominate in the future. Most homes with a network rely on Wi-Fi because of the conveniences of wireless. But will existing or even future wireless technologies have the bandwidth to support the triple play of high-speed data, VoIP, and Internet Protocol TV (IPTV) and video on demand (VOD)? That remains to be seen.
While IEEE 802.11g Wi-Fi systems seem to have the potential, current access points have limitations because walls, ceilings, and other obstructions shorten range and create dead zones. High attenuation and multipath cause speed to back off dramatically for a reliable connection, making video transport more iffy.
That's why so many vendors are joining with the MoCA and HomePNA crowd to support wired technologies that will virtually guarantee quality video transmission. Some new wireless systems such as the 802.11n upgrade and TZero's version of Ultra-Wideband (UWB) using multiple-input multiple-output (MIMO) may do the job. In any case, expect multiple home networking methods in the mix. Whatever works the best for the least money will win.
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