The present invention provides an advantageous transmitter apparatus and associated method, for generating a Single-Carrier Discrete Cosine Transform (SC-DCT) OFDM signal for transmission. These transmit-side innovations include circuit configuration and signal processing methods for mapping Ku “input subcarriers” to N “output subcarriers,” where the “output subcarriers” are some or all of the subcarriers defined for the SC-DCT OFDM signal. In one or more embodiments, Ku is less than N, and the mapping is based on advantageous DCT/IDCT precoding. The present invention additionally or alternatively includes advantageous frequency-selective mapping, and further provides a corresponding receiver apparatus and associated method, for receiving and de-mapping the SC-DCT OFDM signals contemplated herein.