An advanced subscriber line interface circuit architecture for low power and high speech quality

This paper describes and evaluates an architecture for an advanced subscriber line interface circuit (SLIC). This architecture reduces power consumption in the access system and improves the speech quality. It uses a semiconstant current (SCC) battery-feed method that effectively prevents power consumption increasing as metallic line length decreases due to the wider use of optical fiber in the local access network. The SCC method achieves this by forcibly limiting the maximum line current Moreover the SLIC adjusts the speech quality independently of the characteristics of a telephone set or metallic cable, so universally high speech quality is offered to all customers.