Time and Frequency Synchronization of GFDM Waveforms for IoT Applications

Generalized frequency division multiplexing (GFDM) is a major candidate for the fifth-generation (5G) waveform and beyond, and can be used as a modulation technique for Internet of things (IoT) applications. GFDM, however, requires dedicated step to synchronize time and frequency. Current methods of synchronization for GFDM do not perform well, leading to an increase in the bit error rate. In this paper, we propose a method to synchronize time and frequency of GFDM waveforms in a fading channel, under a situation that the channel gains have already been estimated perfectly. The proposed method inserts a known marker and estimates the time and frequency jointly. We compare the proposed method and existing methods in terms of the root mean square error between an actual time or frequency offset and the estimated one. The results show that the proposed method outperform existing methods over a wide range of the signal to noise ratios (SNRs). Furthermore, the proposed method has a desirable property, that the root mean square error approaches zero with an increase in the SNR. The proposed method can synchronize time and frequency accurately and enhance the use of GFDM as a modulation technique in IoT applications.