Outside of North America asymmetric digital subscriber line (ADSL) has been the main engine of growth in mass market, high-speed access. Today, even in the USA, ADSL is growing faster than its rival cable.

It would be very wide of the mark, though, to suggest that any great numbers of us now live in 'hot-wired' societies. According to data produced for the DSL Forum by industry analyst Point Topic, at 30 June, 2004 DSL connections of all types had reached a global total of 78mn, while total worldwide broadband subscribers numbered a modest 123mn.

However, it is certainly the case that some service providers in some locations are having to take a crack at new marketing strategies to maintain broadband's momentum. Examples include: Belgacom's targeting of 'grey surfers'; Eircom's recent broadband promotion that included a new PC for €549, along with free broadband installation, modem and two months free rental; and a new Optus offer of up to four months free broadband every year when customers bundle with fixed line telephony and certain consumer post-paid mobile plans. Patently, some service providers are no longer in 'build it and they will come' terrain.

Copper options multiply
As well as new marketing ploys, operators are also starting to look at new technologies to add spice to the broadband pitch. Deployments of souped up ADSL, in the form of ADSL2 and ADSL2+, are underway, and very high speed digital subscriber line (VDSL) is shipping in quantity in a number of markets.

Depending on variables such as loop length, copper quality, the marketing strategy of the service provider, and how much users were prepared to pay for service, the original ADSL (standardised by the International Telecommunications Union as G.922.1 and .2) could in principle deliver downstream capacity up to the low, single Mbits/s level, and upstream capacity in the low hundreds of kbits/s range.

According to the DSL Forum, ADSL2 (standardised in July 2002 as G.992.3 and .4) offers new features and functionality targeted at improving performance and interoperability, and adds support for new applications, services, and deployment scenarios.

Of particular moment to both service providers and end users is the increase in data rate and the enlarged service palette, with ADSL2 capable of achieving downstream and upstream data rates of about 12Mbits/s and 1Mbits/s respectively, again depending on loop length and other factors. In some circumstances ADSL2 offers an increase in reach of about 600 ft/183 m, also significantly extending the potential customer catchment area.

The DSL Forum further notes that ADSL2+ (standardised by the ITU in early 2003 as G.992.5) then doubles the bandwidth used for downstream data transmission, achieving rates of 20Mbits/s on phone lines as long as 5,000 ft/1,525 m.

There are other variations on the new-age ADSL theme, such as bonding multiple phone lines to increase data rates, and quad-spectrum technology that takes data rates to 50Mbits/s.

Service providers get serious
This year saw the first sizeable commercial deployments of ADSL2 and ADSL2+, and the announcement of some large scale telco plans for future use of the new technologies.

In mid-2004, for example, Puerto Rico Telephone (PRT - the ninth largest US telco) selected Paradyne as its primary provider of DSL access equipment, including standards-based ADSL2+, for residential broadband deployments. Chief operations officer at PRT Gary Butler remarked "Delivery of over 24Mbits/s of bandwidth to residential customers opens new markets to us, and we are excited about the results we're seeing". Hand-over of the 30,000 line order was scheduled for completion in Q3 2004.

Paradyne subsequently reported that it would deliver its broadband access platform, also including ADSL2+, to players in the Egyptian competitive local exchange carrier (CLEC) market including Telecom Egypt Data, Nile OnLine, Raya Telecom and Noor Network. This was part of Egypt's Broadband Initiative announced by the country's Ministry of Communications and Information Technology in May 2004.

France Telecom is also aiming to provide more users with access to ADSL2+, this time at 16Mbits/s, as well as symmetric digital subscriber line (SDSL) at up to 8Mbits/s, as part of a €250mn extension to what is dubbed the 'Broadband For Everyone' initiative. The company says that, as of 2005, the ADSL2+ service will be deployed on the entire France Telecom network, ramping speeds up to 16Mbits/s, and even higher under optimal conditions.

Although doubts have been voiced about the business model for some species of telco TV (click here for details), the speeds of these newer forms of DSL put services such as streaming video, video on demand (VoD), videoconferencing, high definition TV (HDTV), and multi-channel digital TV (DTV) within the telco grasp. So much so in fact, that industry watchers have questioned the business case for VDSL.

DMT versus QAM
It's fair to say that VDSL has had a somewhat chequered history. It was once seen as the next big thing, then relegated to a niche curiosity, then revved up again. At the same time, in a repeat of the technology wars that characterised the development of the original ADSL, the birth of VDSL has been attended by a sometimes acrimonious contest between rival modulation schemes. Instead of carrierless amplitude phase (CAP) and discrete multi-tone (DMT) modulation as in the case of early ADSL, the VDSL battle has been between DMT and quadrature amplitude modulation (QAM).

Although DMT scored an early success winning the backing of the USA's IEEE and ANSI's T1E1.4 Working Group in mid-2003, the VDSL 1 standard (ITU G.993.1) that was 'consented' by ITU-T Study Group 15 on 28 April 2004 specified both QAM and DMT. However, the future looks to be weighted in favour of DMT inasmuch as an enhanced VDSL standard (VDSL 2), which is planned for 'consent' and subsequent approval in 2005, is to be based on DMT. In a May 2004 ITU announcement that the QAM/DMT VDSL1 deal had brought the 'triple play' of video, voice and Internet services one step closer, Peter Wery, the then chairman of Study Group 15, noted: "Future evolution of the VDSL standard, promising even higher bit rates and longer distances, will be based on the DMT technology used for ADSL, thus establishing a single world-wide standard. This will allow the broadband telecom consumer to benefit from the economies of scale offered by global volumes as well as the technological innovation driven by competition".

Korea flies VDSL flag
Regardless of this decision, QAM-based VDSL roll-outs continue. Likewise, regardless of any doubts about the need for VDSL given the data rates and reach able to be achieved with ADSL2 and ADSL2+, VDSL market forecasts are quite positive. According to the Dittberner Associates Inc research company, for example, worldwide capital expenditures related to full-service VDSL will grow to US$7.2bn by 2013, up from an estimated US$877mn dollars in 2004. Dr. Alain Thiney, vice president at Dittberner, acknowledges that VDSL penetration is currently very low or non-existent in most countries, and will remain limited in the next few years. But, he adds: "It is anticipated that in highly developed countries VDSL penetration will increase substantially in the last five years of the forecast to the 30% to 40% range (unless a breakthrough wireless technology emerges). There is already an established market for video services in these countries, and the demand for higher bandwidth corresponds to consumers’ ability and willingness to pay for new services".

Meanwhile, most countries is not all countries in terms of current low level VDSL penetration. Japan and South Korea are famously committed to the VDSL proposition. As an indication of the latter's continuing enthusiasm, in October leading VDSL vendor Metalink reported that shipments of its VDSL products to South Korea for the third quarter of 2004 had increased by approximately 17%, compared to shipments in the second quarter of 2004. The company attributed the growth to two major factors: acceleration of 'Long Reach VDSL' deployment by Korea Telecom, and the first volume shipments to Neowave Inc, a developer, manufacturer and supplier of fibre optics transmission and Internet access systems. "'Total-VDSL', the company's solution for 'Long Reach VDSL' applications, has become the preferred choice of Korean operators in their new broadband deployments", claims Metalink chairman and ceo Tzvi Shukhman.

'Total-VDSL' provides scalability ranging from over 50Mbits/s and up to 5 km DSL service capability. According to Metalink, this scalability is performed automatically using dynamic rate adaptive algorithms that provide the highest possible bitrate compared to any other legacy xDSL technology, including ADSL/ADSL2+.

A recent European recruit to the VDSL camp is Belgacom (click here for details). At the beginning of November Belgacom launched two commercial VDSL services - one for residential and small-to-medium enterprises (SMEs) running at 9 Mbits/s downstream and 400 kbits/s upstream, and the other for larger enterprises providing a download speed of 9 Mbits/s and an upload speed of 640 kbits/s.

The Belgian incumbent has been in the ADSL business for five years. Now's clearly the time to step the broadband game up to the next level...
John Williamson