Scattered-pilot channel estimation for GFDM

This work presents the channel estimation for Generalized Frequency Division Multiplexing (GFDM). GFDM can be considered as a filtered bank multicarrier scheme, where a spectrally-contained pulse shaping is applied over each subcarrier to reduce out of band radiation (OOB). However, due to pulse shaping, subcarriers in GFDM are no longer orthogonal and there is inherent interference. Due to such interference, the channel estimation for GFDM is not trivial. In this work, two channel estimation methods for GFDM are proposed, 1) Pilot Interference Cancellation (Pilot-IC) where interference is pre-canceled only at pilot symbols, 2) Transmitter IC (Tx-IC) where interference is pre-cancelled at both data and pilot symbols. With scattered pilots over frequency and time grid, this allows frequency selective and time varying fading channels to be estimated, with reduced overhead. The simulation results show that these two methods can provide the same MSE performance. Moreover, the Pilot-IC pairing with a Zero Forcing (ZF) receiver, and the Tx-IC pairing with a simple Matched Filter (MF) receiver, also provide the same BER performance. Hence, it is possible to cancel the interference either at the transmitter or the receiver.