Efficient POPS-OFDM waveform design for future wireless communication systems

WOS: 000459697700017Future wireless networks are required to offer new applications and services, which will experience high dispersions in time and frequency, incurred mainly by coarse synchronization. Coarse synchronization is induced by signaling overhead reduction and dictated by the tremendous optimization of the radio interface efficiency. It is expected to dramatically damage waveform orthogonality in conventional orthogonal frequency-division multiplexing (OFDM) systems and to result in oppressive intercarrier interference (ICI). To alleviate the degradation in performance caused by ICI, the concept of nonorthogonal multiplexing has been promoted, as a serious alternative to strict orthogonal multiplexing, for guaranteeing the OFDM benefits without requiring high-level synchronization. Within this nonorthogonal multiplexing framework, ping-pong optimized pulse shaping-OFDM (POPS-OFDM) has been introduced as a powerful tool to efficiently design waveforms, which withstand future multicarrier systems' dispersion impairments. In this paper, we investigate the discrete time version of the POPS-OFDM approach and study its sensitivity and robustness against estimation and synchronization errors. Based on numerical results, we show that POPS-OFDM provides an important gain in the signal-to-interference ratio, typically higher than 5 dB, with respect to conventional OFDM. We also demonstrate that POPS-OFDM brings an increased robustness against synchronization errors and ensures a dramatic reduction in out-of-band emissions, enabling flexible and improved spectrum utilization.Scientific and Technological Research Council of Turkey through Bideb 2232 Program [115C136]The work of T. Baykas was supported by the Scientific and Technological Research Council of Turkey through Bideb 2232 Program under Grant 115C136

Characterization of Ping-Pong Optimized Pulse Shaping-OFDM (POPS-OFDM) for 5G systems

International audienceDue to high mobility situations that are commonly envisaged for the next Fifth Generation (5G) of mobile communication systems, the wireless propagation channel becomes a time-frequency variant, where the time dispersion emerges from the multipath characteristic and the time-selectivity arises from the Doppler spread. This aspect can dramatically damage the waveforms orthogonality that is induced in the Orthogonal frequency division multiplexing (OFDM) signal. Consequently, this results in oppressive Inter-Carrier Interference (ICI) and Inter-Symbol Interference (ISI), which leads to performance degradation in OFDM systems. To efficiently overcome these drawbacks, we propose Ping-pong Optimized Pulse Shaping-OFDM (POPS-OFDM ) algorithm that maximizes the received Signal to Interference plus Noise Ratio (SINR) by optimizing systematically the OFDM waveforms at the Transmitter (TX) and Receiver (RX) sides. We derived the exact closed-form expression of the SINR of the considered multicarrier system and the optimized waveform is searched as a linear combination of several of the most localized Hermite functions. Then, we go further by testing its robustness against time synchronization errors. The results confirm the advantage behind POPS-OFDM algorithm in enhancing spectacular performance and its robustness compared to multicarrier systems using conventional waveforms. Simulations are given to support our claim

On the Joint Use of Time Reversal and POPS-OFDM for 5G Systems

International audience—This paper investigates the efficiency of the combination of the Ping-pong Optimized Pulse Shaping-Orthogonal Frequency Division Multiplexing (POPS-OFDM) algorithm with the Time Reversal (TR) technique. This algorithm optimizes the transmit and receive OFDM waveforms with a significant reduction in the system Inter-Carrier Interference (ICI)/Inter-Symbol Interference (ISI) and guarantees maximal Signal to Interference plus Noise Ratio (SINR) for realistic mobile radio channels in 5G Systems. To this end, we characterize the scattering function of the TR channel and we derive the closed-form expression of the SINR as a Generalized Rayleigh Quotient. Numerical analysis reveals a significant gain in SINR and Out-Of-Band (OOB) emissions, brought by the proposed TR-POPS-OFDM approach