Abstract: A vectoring controller is configured to determine first coefficient values for a vectoring matrix at a first tone based on a first number of iterations through an iterative update algorithm and a first channel matrix estimate at the first tone, and to determine second coefficient values for the vectoring matrix at a second neighboring tone based on a second number of iterations through the iterative update algorithm and a second channel matrix estimate at the second tone. The vectoring controller is configured to start with the first coefficient values as initial values for the respective second coefficient values in the iterative update algorithm. The second number of iterations is lower than or equal to the first number of iterations.

Abstract: A vectoring controller is configured to determine first coefficient values for a vectoring matrix at a first tone based on a first number of iterations through an iterative update algorithm and a first channel matrix estimate at the first tone, and to determine second coefficient values for the vectoring matrix at a second neighboring tone based on a second number of iterations through the iterative update algorithm and a second channel matrix estimate at the second tone. The vectoring controller is configured to start with the first coefficient values as initial values for the respective second coefficient values in the iterative update algorithm. The second number of iterations is lower than or equal to the first number of iterations.

Abstract: A method, central unit, and modem for reducing crosstalk in a Digital Subscriber Line (DSL) system. A virtual line referred to as a ghost line is introduced in the system as a substitution for all of the lines except a first line to induce crosstalk to the first line. The Power Spectral Density (PSD) on the first line is allocated to optimize against the ghost line. A modem on the first line reports to a central Spectrum Management Center (SMC), a measure indicating crosstalk impact from the ghost line. This process is repeated for each line. The SMC calculates updated ghost line parameters for each line, which reflect current crosstalk characteristics between each modem and the remaining modems, and sends the updated parameters to the modems. The modems then reallocate PSDs with respect to the updated ghost line parameters to either maximize the rate or minimize the power on their respective lines.

Abstract: A method and transmitter unit in a multi-tone, multi-line based transmission system, such as a digital subscriber line system, for determining a Power Spectral Density (PSD) of a plurality of users over a physical channel for at least one tone. Each of the users has a minimum required data rate and a maximum allowed power. A Power Minimization Problem (PMP) is formulated mathematically, introducing Lagrangian multipliers, and by utilizing a dual decomposition approach for the objective function of the PMP in order to solve the PMP on a per-tone basis.

Abstract: The present invention relates to method and arrangements for reducing crosstalk in a DSL system. This is achieved by providing the users in the network with a ghost line, i.e. a virtual line that should reflect the damage to be caused to the remaining users in the network, and that each user allocates the PSDs such that the allocated PSD is optimized against this ghost line. A central agent is adapted to continuously and individually update the ghost lines by collecting a measure indicating the impact of crosstalk from all modems.