Pulse shaping design for OFDM systems

Spectrally contained OFDM-based waveforms are considered key enablers for a flexible air interface design to support a broad range of services and frequencies as envisaged for 5G mobile systems. By allowing for the flexible configuration of physical layer parameters in response to diverse requirements, these waveforms enable the in-band coexistence of different services. One candidate from this category of waveforms is pulse-shaped OFDM, which follows the idea of subcarrier filtering while fully maintaining the compatibility with CP-OFDM. In this paper, we provide an overview of pulse shaping methods in OFDM systems and propose a new pulse-shaped design method with arbitrary length constraint and good time-frequency localization property. Based on the pulse design, we discuss different receiver realizations and present a criterion for pulse shape evaluation. In addition, the parameterizations of OFDM system to address diverse requirements of the services envisaged for the 5G systems are described. Link and system performance results for selected scenarios show that a proper design of the OFDM numerologies and pulse shapes could substantially improve the performance under time and frequency distortions. Furthermore, pulse-shaped OFDM is able to support asynchronous transmissions and reduce the signal sensitivity to Doppler distortions, rendering it beneficial for various applications from the context of vehicular communications and the Internet-of-things.