 | May 1, 2000 |
Intense density
ADVANCE: Carrier-side chips drive ADSL deployment
In DSL, as in most communication topics, the client side of the communication link gets the most attention. We've been deluged with stories about the latest ICs for consumer ADSL modems, and granted they're important. But cost-effective, low-power, high-density supporting technologies for the service-provider side of the connection are even more important. Without them there is no ADSL service to the consumer.
The two sides of the equation impose quite different requirements. The consumer side consists of a single port, so an ideal design might combine an analog front end, an ADSL modem, a controller, and perhaps even a PCI-bus interface. The carrier side, however, needs a product that handles multiple lines, and that means quite a different integration strategy.
Alcatel has just announced a set of three chips that fully implement four ADSL lines in carrier gear. Only two years ago, four ADSL lines required 12 ICs. The DynaMiTe family relies on industry-standard DMT (discrete multitone) modulation and can support both full-rate G.DMT and low-rate G.Lite ADSL services. To boost the integration factor, Alcatel integrated horizontally rather than vertically, if you will. The MTC 20454 IC includes four analog-front-end circuits and the MTC 20455 IC includes four ADSL modems. By separating the analog and DSP (digital signal processing) functions, the design matches each function to the most appropriate IC fabrication technology, which minimizes power consumption and cost.
The third IC, a microcontroller, comes with Alcatel software to support the multimode operation and in fact can even support ADSL-over-ISDN operation. Alcatel claims the DynaMiTe family achieves the highest port density and lowest power consumption in the industry. The design uses only a half watt of power per ADSL line, which makes carriers smile because it reduces the use of power and space in the cental office. In turn, this will ultimately yield more cost-effective ADSL lines to consumers.
|
