A method and apparatus are provided for use in a wireless communications system to enable dynamic selection of k sub-MAPs, and rates for transmitting these k sub-MAPs within communication frames. The method comprises the steps: a) for at least one communication frame comprised within a first interval of time, retrieving information on statistical distribution of downlink (DL) channel rates for a group of subscriber devices; b) based on that information, selecting k and corresponding transmission rates for k sub-MAPs, to minimize total amount of resources to be allocated for MAP and sub-MAPs transmission within that communication frame comprised within the first time interval and/or within a second interval of time that proceeds the first interval of time; and c) transmitting the k sub-MAPs at the selected corresponding transmission rates in communication frames comprised within the first time interval and/or within the second interval of time that proceeds the first one.