oroujeny, B. (2018). Filter bank multicar- rier in massive MIMO: analysis and channel equalization. IEEE Transactions on Signal Processing 66 (15): 3987-4000. Orthogonal Time-Frequency Space Modulation: Principles and Implementation Arman Farhang1 and Behrouz Farhang-Boroujeny2 1 Department of Electronic Engineering, Maynooth University, Maynooth, Co., Ireland 2Electrical and Computer Engineering Department, University of Utah, USA 6.1 Introduction While orthogonal frequency division multiplexing modulation (OFDM) scheme achieves a performance near the capacity limits in linear time-invariant channels, it leads to a poor performance in doubly dispersive channels. This is due to the large amount of interference that is imposed by the channel Doppler spread. The common approach to cope with this issue in the existing wireless standards such as IEEE 802.11a and digital video broadcasting systems is to shorten OFDM symbol duration in time SO that the channel variations over each OFDM symbol are negligible. However, this reduces the spectral efficiency of trans- mission since the cyclic prefix (CP) length should remain constant. A thorough analysis of OFDM in such channels is conducted in [1]. Another classical approach for handling time-varying channels is to utilize filtered multicarrier systems that are optimized for a balanced performance in doubly dispersive channels [2]. Recently, new signaling techniques have emerged in the literature to tackle the TV chan- nels [3, 4]. In [3], the authors introduce a new waveform called frequency division multi- plexing with a frequency-domain cyclic prefix (FDM-FDCP). This waveform outperforms OFDM in channels with high Doppler and low delay spread. However, its performance in channels with high Doppler and medium to high delay spread is yet to be understood [3]. Orthogonal time-frequency space (OTFS) modulation has recently been proposed as another emerging signaling technique [4]. OTFS is an effective waveform for signaling over TV channels that takes advantage of the time 