Bit error rates of GFDM under time-varying channels and synchronization errors

Abstract

Synchronization errors affect the bit error rate of the generalized frequency division multiplexing (GFDM), which is a major waveform candidate for the fifth-generation (5G) communication system. At present, the bit error rate of GFDM is available under the synchronization errors in the additive white Gaussian noise (AWGN) channel, which is a simple channel model but is inadequate for the 5G system. This paper quantifies the bit error rate of GFDM under the synchronization errors and the time-varying channel, which extends the AWGN channel and includes fading as a major impairment. The bit error rates are simulated for various channel conditions, including the AWGN channel, the time-varying channel with no channel estimation, and the time-varying channel with a perfect channel estimation. In addition, the simulation covers a range of timing delays and frequency offsets, which come from synchronization errors. The simulation results indicate that GFDM is highly sensitive to timing delay. A timing delay as small as one sample can significantly degrade the bit error rate, making transmission unreliable. On the other hand, GFDM can tolerate a frequency offset up to a certain value before the bit error rate becomes unreliable. The results in this paper have practical applications to 5G systems and identify a level of synchronization errors that GFDM waveforms can tolerate.