Crosstalk cancellation for digital subscriber lines (DSL)

Digital subscriber lines (DSL) denote a family of technologies providing digital data transmission over conventional telephone lines. The high availability of telephone lines - almost every horne (in industrialized countries) is connected with a telephone line - makes DSL very attractive in comparison to other competing broadband access technologies. From the beginning of the 21st century, this has led to a boom of DSL. Telephone lines are intended to carry narrowband voice band signals in a frequency range from 300 Hz to 3.4 kHz. But used for DSL, telephone lines carry broadband signals with frequencies up to several hundreds of kHz, and even up to several MHz. For such frequencies, signal attenuation, in conjunction with another physical effect called crosstalk, plays a crucial role. Crosstalk denotes an electromagnetic coupling between DSL signals of neighbouring lines. Crosstalk signals act as noise and thus limit the performance of DSL systems (i. e., data rates and reach). This thesis investigates crosstalk cancellation. Within the presented framework, crosstalk is not cancelled within the transmission systems, e. g., like proposed by dynamic spectrum management level 3, but it is cancelled outside the transmission systems. This type of crosstalk cancellation is independent of the underlying DSL systems, guaranteeing compatibility with already installed DSL-based network infrastructure devices.