Generalized DFT-s-OFDM Waveforms Without Cyclic Prefix

This paper deals with generalized discrete Fourier transform-spread-orthogonal frequency division multiplexing (G-DFT-s-OFDM) waveforms, which replace the cyclic prefix of traditional OFDM/DFT-s-OFDM with an internal guard period. Such waveforms feature significant benefits in terms of flexibility, spectral containment, and low peak-to-average power ratio. Aspects related to reference sequence design and mapping for channel estimation are thoroughly addressed, and a new estimator for the specific zero-tail DFT-s-OFDM case is proposed. Furthermore, we address the opportunity of exploiting the internal guard period at each symbol for frequent channel state information updates, thus enabling the possibility of tracking rapidly varying propagation conditions.