A method comprising: determining a plurality of power spectrum density, PSD, profiles for a plurality of cabinet-deployed digital subscriber lines, DSLs, comprising jointly and iteratively determining a plurality of cutoff frequencies based on crosstalk coupling parameters among the DSLs; characterized in that the determining of cutoff frequencies comprises for each line n, where n equals 1 to N, where N is a total number of the plurality of DSLs: for each subcarrier k, where k equals 1 to K, where K is a number of subcarriers: determining a gain h k n, n and a background noise parameter σ k n, and for each line m, where m equals 1 to N, where m ≠ n: determining a crosstalk coupling parameter h k n, m from line m into line n, and setting initial values of variables DPBOFMAX max n DPBOFMAX min n, and DPBOFMAX tol n, wherein the initial values satisfy a constraint DPBOFMAX max n - DPBOFMAX min n > DPBOFMAX tol n; wherein DPBOFMAX min n refers to the minimum allowed value of cutoff frequency DPBOFMAX for line n, DPBOFMAX max n refers to the maximum allowed value of DPBOFMAX for line n, DPBOFMAX tol n refers to the tolerance of iteration of DPBOFMAX for line n; for each line i, where i equals 1 to N, iteratively repeating the following steps until DPBOFMAX max i - DPBOFMAX min i ≤ DPBOFMAX tol i: for each line n, where n equals 1 to N, performing the following steps if DPBOFMAX max n - DPBOFMAX min n > DPBOFMAX tol n: determining an intermediate cutoff frequency DPBOFMAX int n as DPBOFMAX int n = DPBOFMAX max n + DPBOFMAX min n / 2, for each subcarrier f k, where k equals 1 to K, where K is a number of subcarriers, determining a transmit PSD parameter s k n based on the intermediate cutoff frequency, determining a data rate R n based on the transmit PSD parameters and a plurality of the crosstalk coupling functions corresponding to all DSLs, and if R n > R target n, set DPBOFMAX min n equal to DPBOFMAX int n, and otherwise set DPBOFMAX max n equal to DPBOFMAX int n, where R target n is a required data rate; and determining the cutoff frequency of the PSD profile as a final intermediate cutoff frequency produced by the iterative steps; wherein the cutoff frequencies and PSD profiles are in one to one correspondence, and wherein each profile comprises a reduced PSD portion below the cutoff frequency of the profile and a maximum PSD portion above the cutoff frequency. determining a plurality of power spectrum density, PSD, profiles for a plurality of cabinet-deployed digital subscriber lines, DSLs, comprising jointly and iteratively determining a plurality of cutoff frequencies based on crosstalk coupling parameters among the DSLs; characterized in that the determining of cutoff frequencies comprises for each line n, where n equals 1 to N, where N is a total number of the plurality of DSLs: for each subcarrier k, where k equals 1 to K, where K is a number of subcarriers: determining a gain h k n, n and a background noise parameter σ k n, and for each line m, where m equals 1 to N, where m ≠ n: determining a crosstalk coupling parameter h k n, m from line m into line n, and for each subcarrier k, where k equals 1 to K, where K is a number of subcarriers: determining a gain h k n, n and a background noise parameter σ k n, and for each line m, where m equals 1 to N, where m ≠ n: determining a crosstalk coupling parameter h k n, m from line m into line n, and determining a gain h k n, n and a background noise parameter σ k n, and for each line m, where m equals 1 to N, where m ≠ n: determining a crosstalk coupling parameter h k n, m from line m into line n, and determining a crosstalk coupling parameter h k n, m from line m into line n, and setting initial values of variables DPBOFMAX max n DPBOFMAX min n, and DPBOFMAX tol n, wherein the initial values satisfy a constraint DPBOFMAX max n - DPBOFMAX min n > DPBOFMAX tol n; wherein DPBOFMAX min n refers to the minimum allowed value of cutoff frequency DPBOFMAX for line n, DPBOFMAX max n refers to the maximum allowed value of DPBOFMAX for line n, DPBOFMAX tol n refers to the tolerance of iteration of DPBOFMAX for line n; for each line i, where i equals 1 to N, iteratively repeating the following steps until DPBOFMAX max i - DPBOFMAX min i ≤ DPBOFMAX tol i: for each line n, where n equals 1 to N, performing the following steps if DPBOFMAX max n - DPBOFMAX min n > DPBOFMAX tol n: determining an intermediate cutoff frequency DPBOFMAX int n as DPBOFMAX int n = DPBOFMAX max n + DPBOFMAX min n / 2, for each subcarrier f k, where k equals 1 to K, where K is a number of subcarriers, determining a transmit PSD parameter s k n based on the intermediate cutoff frequency, determining a data rate R n based on the transmit PSD parameters and a plurality of the crosstalk coupling functions corresponding to all DSLs, and if R n > R target n, set DPBOFMAX min n equal to DPBOFMAX int n, and otherwise set DPBOFMAX max n equal to DPBOFMAX int n, where R target n is a required data rate; and determining the cutoff frequency of the PSD profile as a final intermediate cutoff frequency produced by the iterative steps; wherein the cutoff frequencies and PSD profiles are in one to one correspondence, and wherein each profile comprises a reduced PSD portion below the cutoff frequency of the profile and a maximum PSD portion above the cutoff frequency.