A method implemented by a Cable Modem Termination System, CMTS, comprising: allocating, by the CMTS, a specific probing symbol within a probing frame for wideband probing; defining a probing pattern in the allocated probing symbol, wherein the probing pattern comprises a set of pilots from scattered subcarriers of the allocated probing symbol; and instructing a Cable Modem, CM, to transmit a probing sequence in the allocated probing symbol; characterized in that instructing the CM to transmit the probing sequence comprises sending an upstream bandwidth allocation map, MAP, message comprising a plurality of successive probing information elements, P-IE,, wherein each P-IE comprises a service flow identifier field, a reserved field, a power field, an equalizer field, a stagger field, a probing frame field, a Symbol In Frame field, a start subcarrier field, and a subcarrier skip field, wherein a parameter in the service flow identifier field indicates a ranging service flow identifier, SID, for a downstream network unit assigned to use the P-IE; the reserved field is reserved for future extension; a parameter in the power field indicates whether power control may be employed for probing; a parameter in the equalizer field indicates whether a transmit equalizer is to be employed for probing; a parameter in the stagger field indicates whether a staggered pattern is to be employed for pilot subcarriers; wherein the parameter in the stagger field set to a value of one instructs a downstream network unit identified by the SID specified in the service flow identifier field to repeat a pattern in P-IE in the next number of symbols equal in quantity to the parameter in the subcarrier skip field, and by moving the pattern up by one subcarrier in each symbol and wrapping the pattern back to the beginning; a parameter in the probing frame field indicate a number of frames offset from a frame beginning at an allocation start time specified in the MAP message; a parameter in the Symbol In Frame field specifies the probing symbol within the probing frame, wherein the parameter in the Symbol In Frame field is a number of symbols offset from the beginning of the probing frame; a parameter in the start subcarrier field indicates a starting subcarrier to be used by the probe pattern; and a parameter in the subcarrier skip field is a number of subcarriers to be skipped between successive pilots in the probe pattern, wherein the parameter in the subcarrier skip field when being set to a value of zero indicates no skipping of subcarriers and that all non-excluded subcarriers are to be employed for probing. allocating, by the CMTS, a specific probing symbol within a probing frame for wideband probing; defining a probing pattern in the allocated probing symbol, wherein the probing pattern comprises a set of pilots from scattered subcarriers of the allocated probing symbol; and instructing a Cable Modem, CM, to transmit a probing sequence in the allocated probing symbol; a parameter in the service flow identifier field indicates a ranging service flow identifier, SID, for a downstream network unit assigned to use the P-IE; the reserved field is reserved for future extension; a parameter in the power field indicates whether power control may be employed for probing; a parameter in the equalizer field indicates whether a transmit equalizer is to be employed for probing; a parameter in the stagger field indicates whether a staggered pattern is to be employed for pilot subcarriers; wherein the parameter in the stagger field set to a value of one instructs a downstream network unit identified by the SID specified in the service flow identifier field to repeat a pattern in P-IE in the next number of symbols equal in quantity to the parameter in the subcarrier skip field, and by moving the pattern up by one subcarrier in each symbol and wrapping the pattern back to the beginning; a parameter in the probing frame field indicate a number of frames offset from a frame beginning at an allocation start time specified in the MAP message; a parameter in the Symbol In Frame field specifies the probing symbol within the probing frame, wherein the parameter in the Symbol In Frame field is a number of symbols offset from the beginning of the probing frame; a parameter in the start subcarrier field indicates a starting subcarrier to be used by the probe pattern; and a parameter in the subcarrier skip field is a number of subcarriers to be skipped between successive pilots in the probe pattern, wherein the parameter in the subcarrier skip field when being set to a value of zero indicates no skipping of subcarriers and that all non-excluded subcarriers are to be employed for probing.