Abstract: An over-the-air computation (AirComp) scheme is proposed for federated edge learning (FEEL) without channel state information (CSI) at the edge devices (EDs) or edge server (ES). The proposed scheme adopts the majority vote (MV) principle and uses pulse-position modulation (PPM) symbols constructed with discrete Fourier transform (DFT)-spread orthogonal frequency division multiplexing (OFDM) (DFT-s-OFDM) as votes from EDs. By taking the delay spread and synchronization errors into account, we show how to eliminate the need for truncated-channel inversion (TCI) at the EDs and detect MV at the ED with a non-coherent detector. The proposed method naturally reduces the peak-to-mean envelope power ratio (PMEPR) of the signal as it inherits the properties of the single-carrier (SC) waveform.

Abstract: A method, performed at a transmitter, for increasing communication link distance and reliability in a communication channel or dual function radar communication system, is provided. The method includes calculating an information sequence, indices of non-zero elements and corresponding values in the sequence indicating information bits to be transmitted; shaping a Discrete Fourier Transform (DFT) of the information sequence by special frequency-domain spectral shaping (FDSS) in the frequency domain to form a frequency-domain representation of chirp signals; mapping the shaped sequence to orthogonal frequency division multiplexing (OFDM) subcarriers; performing an inverse DFT of the mapped shaped sequence to form chirp signals to be transmitted; and transmitting the chirp signals with a cycle prefix (CP).