 crosstalk interference cancellation can result in higher SINR and therefore higher transmission capacity. Fixed Broadband Communications Systems Removal of interference at a CO is relatively easy. A CO receives and detects the upstream signals of all users within a link bundle. It may then recalculate the crosstalk value associated with one user and subtract it from the received signal of another and thereby produce a less noisy signal. Alternatively it may jointly detect the signals of multiple users given the amount of crosstalk as calculated from all received signals. Through this process, the received signal is made free of crosstalk and therefore signal detection is done without any FEXT. While the CO receiver detects all upstream signals, in downstream an end user only detects desired signal with FEXT present from all other active users. However it cannot calculate the crosstalk values since it does not know about the channel parameters of other users. However the transmitter of the CO can pre-decorrelate the transmitted signal using the upstream channel vec- tors. The transmitter multiplies the individual signals by the inverse of the vector matrix. This cancels the transmission channel vector matrix and as a result the received signal at any user is FEXT-free. This method is known as Vectored VDSL because it is generally used in VDSL. In cases when two or more operators use the same copper bundle then Vectored VDSL may not be possible as one operator's transmitter may not know about another operator's down- stream data. To implement Vectored operation, multiple operators need to collaborate. ADSL/VDSL Standards Enhancements ADSL/VDSL standards have evolved to deliver higher transmission rates in both upstream and downstream. DMT technology used in ADSL/VDSL standards facilitates a simple frequency spectrum allocation. Generally the first 4 kHz (or in the case of ISDN legacy systems the first 80-120 kHz) are reserved for plain old telephone service (POTS) voice communication. A guard band is then specifie