A network element in a long term evolution time division duplex, LTE-TDD, cellular communication system comprising: a signal processing logic module arranged to: generate a single system information, SI, message; and generate a variable SI window length, si-Windowlength, parameter for transmission to at least one wireless communication unit; wherein the signal processing logic module is arranged to determine availability of downlink transmissions to the at least one wireless communication unit, wherein the availability of downlink subframes is obtained from radio frame configuration information; a transceiver arranged to transmit the si-Windowlength parameter and the single system information, SI, message to the at least one wireless communication unit in a variable length transmission time window, SI window, a number of times, wherein the number of transmissions is based on the si-Windowlength parameter; wherein a start time of a transmission of the single SI message, the start time comprising a subframe, a, in which the SI window starts in a corresponding radio frame, SFN, is calculated as: a = xmody, wherein x = ( n - 1) * w, wherein n corresponds to an order of entry of the SI message in a list of SI messages wherein w is the si-Windowlength and y equals a number of downlink subframes in a radio frame, wherein SFN is determined as: SFN mod T = FLOOR / y x, wherein T is the SI periodicity, si-Periodicity, of the SI message; and wherein a duration of the variable length transmission time window, SI window, is equal to a time window that contains a number of downlink subframes equal in time to the si-Windowlength. a signal processing logic module arranged to: generate a single system information, SI, message; and generate a variable SI window length, si-Windowlength, parameter for transmission to at least one wireless communication unit; wherein the signal processing logic module is arranged to determine availability of downlink transmissions to the at least one wireless communication unit, wherein the availability of downlink subframes is obtained from radio frame configuration information; a transceiver arranged to transmit the si-Windowlength parameter and the single system information, SI, message to the at least one wireless communication unit in a variable length transmission time window, SI window, a number of times, wherein the number of transmissions is based on the si-Windowlength parameter; wherein a start time of a transmission of the single SI message, the start time comprising a subframe, a, in which the SI window starts in a corresponding radio frame, SFN, is calculated as: a = xmody, wherein x = ( n - 1) * w, wherein n corresponds to an order of entry of the SI message in a list of SI messages wherein w is the si-Windowlength and y equals a number of downlink subframes in a radio frame, wherein SFN is determined as: SFN mod T = FLOOR / y x, wherein T is the SI periodicity, si-Periodicity, of the SI message; and wherein a duration of the variable length transmission time window, SI window, is equal to a time window that contains a number of downlink subframes equal in time to the si-Windowlength. generate a single system information, SI, message; and generate a variable SI window length, si-Windowlength, parameter for transmission to at least one wireless communication unit; wherein the signal processing logic module is arranged to determine availability of downlink transmissions to the at least one wireless communication unit, wherein the availability of downlink subframes is obtained from radio frame configuration information; a transceiver arranged to transmit the si-Windowlength parameter and the single system information, SI, message to the at least one wireless communication unit in a variable length transmission time window, SI window, a number of times, wherein the number of transmissions is based on the si-Windowlength parameter; wherein a start time of a transmission of the single SI message, the start time comprising a subframe, a, in which the SI window starts in a corresponding radio frame, SFN, is calculated as: a = xmody, wherein x = ( n - 1) * w, wherein n corresponds to an order of entry of the SI message in a list of SI messages wherein w is the si-Windowlength and y equals a number of downlink subframes in a radio frame, wherein SFN is determined as: SFN mod T = FLOOR / y x, wherein T is the SI periodicity, si-Periodicity, of the SI message; and wherein a duration of the variable length transmission time window, SI window, is equal to a time window that contains a number of downlink subframes equal in time to the si-Windowlength.