Spectrally Encapsulated Orthogonal Frequency Division Multiplexing for Short Packet Transmission

A spectrally encapsulated orthogonal frequency division multiplexing (SE-OFDM) precoding scheme for short packet transmission that is able to suppress the out-of-band emission (OoBE) while maintaining the advantage of thecyclic prefix (CP)-OFDM is proposed. The SE-OFDM symbol consists of a prefix, an information (I)-symboland a suffix that are generated by head, center and tail matrices, respectively. The prefix and suffix play the roles of guard interval (GI) and suppress the OoBE, and the I-symbol has the same size as the DFT symbolin the CP-OFDM symbol and serves as an information field. Specifically, since the center matrix generating theI-symbol is orthogonal, data and pilot symbols can be allocated to any subcarriers without distinction. Even if the proposed precoder is required to generate OFDM symbols with spectral efficiency in the transmitter, any decoder corresponding to that is not required in the receiver. The precoder, which is in matrix form, is created through six processes: inverse discrete Fourier transform (IDFT), permutation, weighting, filtering, orthogonalizing, and approximating. Through the orthogonalizing process, the center matrix of the precoder matrix becomes orthogonal, and the head and tail matrices retain the ability to block the OoBE to adjacent channels. The proposed scheme is compared with CP-OFDM in terms of the OoBE, autocorrelation, and bit error rate (BER).