An apparatus for band-limited frequency division multiplexing for uplink transmission to a base station or access point, particularly from an IoT device, comprises a signal modulator to transmit a signal over a set of contiguous equally spaced frequency sub-carriers ranging from a lowest frequency sub-carrier via intermediate sub-carriers to a highest frequency sub-carrier. The signal modulator contains a filter to apply asymmetric filtering over the range of the frequency sub-carriers, thereby to reduce a peak-to-average power ratio of the transmitted signal.