Power-efficient copper access

While the data rate has traditionally been a key performance measure for copper access technology, power efficiency is becoming increasingly important. Line drivers are receiving significant focus since they account for roughly 50 percent of the total power consumption of a digital subscriber line access multiplexer. One approach to reduce this power consumption is to insightfully exploit currently available features. The low power mode (L2), as standardized for Asymmetric Digital Subscriber Line 2 (ADSL2/2plus), can contribute to huge power savings by reducing transmit power during periods of low user traffic. However, effective single or multi-line management is required to ensure that time-varying crosstalk generated by the lines exiting L2 does not jeopardize the stability of neighboring lines. Another approach is to develop an advanced, scalable, joint optimization of power allocation to tones on multiple lines (potentially time varying), with an explicit objective to lower power consumption as well as to optimize the data rate.