Israeli telecommunications equipment maker ECI Telecom said this week it was behind a new consortium aimed at getting to the next technical level in DSL technologies. It wants to develop and promote an upgrade to DSL technology called Dynamic Spectrum Management (DSM).
DSM is an attempt at taking copper networks to fiber-optic-like data transfer rates and is, ECI says, the next step after ADSL2+ and VDSL2, which are the core installation focus of current DSL suppliers. ADSL2+ can send data over a 2.2 MHz channel which offers data rates up to 24 Mbps, but which is resilient over a much further distance from a telephone exchange than other high speed technologies and is better than ADSL up to around 10,000 feet from the exchange. VDSL2 uses a 30 MHz carrier and the signal deteriorates rapidly
ECI and partners set out store to double the speed of DSL from its peak at 100 Mbps at under 1000 feet from the exchange, to its useful rate of around 25 to 35 Mbps between 3,000 and 4,000 feet from a telephone exchange.
Most recently new chips have emerged which can support either scheme, depending on what conditions the chips find on the network.
ECI Telecom says it has secured $10m of Israeli government money and will lead the consortium alongside operators including Telefonica and Bezeq, vendors such as Actelis, RIT Technologies and Amethist, as well as leading academic institutions, including the Technion, Bar Ilan University and Tel Aviv University.
"The main obstacle for the advancement of DSL technology is the interference ("crosstalk") generated from different DSL lines that share the same telephone cable binder," said Professor John Cioffi, Professor of Engineering at Stanford University, a pioneer of DSM research, who is also recognized as the inventor of the DMT line code. "DSM is a promising technology for the future evolution of broadband access networks using existing copper infrastructure."
ECI Telecom will be presenting a discussion on DSM and the Consortium at the Broadband World Forum in Paris on October 12, 2006.
DSM uses four key concepts that Cioffi describes as channel identification, spectrum balancing, vectored transmission methods and multi-user detection.
The idea works best when fiber is feeding a DSL line, and spectrum balancing co-ordinates the allocation of different frequencies to each user in a cable binder to achieve best results based on the characteristics of the line. Using these ideas ECI has already achieved rates of 45 Mbps at distances of over 1,500 feet from an exchange and it claims these techniques can double the speed of broadband over ADSL distances like 12,000 feet.
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