An apparatus comprising: means for receiving a stream of orthogonal frequency division multiplexing symbols and associated cyclic prefixes produced by at least one orthogonal frequency-division multiplexing modulator of a radio transmitter or transceiver, wherein the stream comprises a plurality of different numerologies; means for dividing said stream into a plurality of overlapping processing blocks of a first length, wherein at least one of the plurality of overlapping processing blocks comprises a non-overlapping section having values corresponding to a segment of said stream, the dividing comprising adjusting a length of the non-overlapping section at least based on whether a cyclic prefix is comprised in said segment of said stream and, if a cyclic prefix is comprised in said segment, on a length of said cyclic prefix so as to enable symbol-synchronous continuous fast convolution processing, wherein the adjusting of the length of the non-overlapping section of said at least one of the plurality of overlapping processing blocks comprises: if a non-overlapping section of an overlapping processing block comprises a cyclic prefix having an expanded length compared to a default length of a cyclic prefix defined for a numerology of an orthogonal frequency division multiplexing symbol of said non-overlapping section, calculating a length of a non-overlapping section of the overlapping processing block using a first equation dependent at least on the first length and an orthogonal frequency division multiplexing processing sampling rate of the overlapping processing block defined by the numerology and otherwise, calculating the length of the non-overlapping section of the overlapping processing block using a second equation dependent at least on the first length, wherein the second equation is different from the first equation; means for filtering the plurality of overlapping processing blocks using fast convolution processing; and means for concatenating a plurality of filtered processing blocks to form an output signal for transmission via at least one antenna of the radio transmitter or transceiver. means for receiving a stream of orthogonal frequency division multiplexing symbols and associated cyclic prefixes produced by at least one orthogonal frequency-division multiplexing modulator of a radio transmitter or transceiver, wherein the stream comprises a plurality of different numerologies; means for dividing said stream into a plurality of overlapping processing blocks of a first length, wherein at least one of the plurality of overlapping processing blocks comprises a non-overlapping section having values corresponding to a segment of said stream, the dividing comprising adjusting a length of the non-overlapping section at least based on whether a cyclic prefix is comprised in said segment of said stream and, if a cyclic prefix is comprised in said segment, on a length of said cyclic prefix so as to enable symbol-synchronous continuous fast convolution processing, wherein the adjusting of the length of the non-overlapping section of said at least one of the plurality of overlapping processing blocks comprises: if a non-overlapping section of an overlapping processing block comprises a cyclic prefix having an expanded length compared to a default length of a cyclic prefix defined for a numerology of an orthogonal frequency division multiplexing symbol of said non-overlapping section, calculating a length of a non-overlapping section of the overlapping processing block using a first equation dependent at least on the first length and an orthogonal frequency division multiplexing processing sampling rate of the overlapping processing block defined by the numerology and otherwise, calculating the length of the non-overlapping section of the overlapping processing block using a second equation dependent at least on the first length, wherein the second equation is different from the first equation; if a non-overlapping section of an overlapping processing block comprises a cyclic prefix having an expanded length compared to a default length of a cyclic prefix defined for a numerology of an orthogonal frequency division multiplexing symbol of said non-overlapping section, calculating a length of a non-overlapping section of the overlapping processing block using a first equation dependent at least on the first length and an orthogonal frequency division multiplexing processing sampling rate of the overlapping processing block defined by the numerology and otherwise, calculating the length of the non-overlapping section of the overlapping processing block using a second equation dependent at least on the first length, wherein the second equation is different from the first equation; means for filtering the plurality of overlapping processing blocks using fast convolution processing; and means for concatenating a plurality of filtered processing blocks to form an output signal for transmission via at least one antenna of the radio transmitter or transceiver.