Single-Carrier and Multicarrier Transceivers Based on Discrete Cosine Transform Type-IV

Multicarrier and single-carrier communications can be performed by using different orthogonal transforms. In this work, we derive the conditions to use discrete cosine transform type-IV even (DCT4e) in these contexts. Basically, these conditions are the two following: 1) The channel impulse response has to be symmetric. 2) Redundancy (a prefix and also a suffix guard sequence) must be appended into each data symbol to be transmitted. To satisfy the former, a front-end prefilter must be incorporated at the receiver. With regard to the second condition, we use a matrix formulation to demonstrate how the global transmission channel matrix can be diagonalized when symmetric extension or zero padding are used as redundancy. The use of zero padding requires an additional block at the receiver, whose structure is also shown. Moreover, a new expression based on the DCT4e to obtain the value of the per-subcarrier coefficients of the frequency-domain equalizer is derived. Finally, the proposed transceivers are compared to the DFT-based standardized systems in different communication scenarios under the presence of carrier frequency offset.