Pulse shaped OFDM for asynchronous uplink access

This paper considers the scenario of massive machine type communication (MTC) in cellular uplink for short packet traffic. For this traffic type, the closed loop Timing Advance (TA) adjustment process applied in current LTE uplink introduces significant overhead in signaling and energy consumption. We propose to pulse shape the OFDM signals using time-frequency localized prototype filters. This improves the robustness of the waveform against timing offsets, so that the uplink transmission procedure can be simplified. Building on that property, an asynchronous uplink access scheme is developed. In the performance evaluation, we compare with both DFTs-OFDM and CP-OFDM schemes and demonstrate that higher spectral efficiency can be achieved by the pulse shaped OFDM scheme, highlighting the benefits in properly designing the pulse shapes of a multicarrier waveform.