Wideband MIMO THz System Design With MB-OFDM Waveform and Hybrid Beamforming

Terahertz (THz) band communication, operating in the range of
$(0.1-10)\times 10^{12}$
Hz, holds immense potential for fulfilling the ever-increasing demand for ultra-high data rate wireless communication. However, the unfavorable channel characteristics of THz communication pose a significant challenge in realizing this promising technology. In this paper, we present a novel solution to this challenge by proposing a wideband THz hybrid multiple-input multiple-output (MIMO) system design that leverages the ultra-wide bandwidth and the high spectral efficiency of MIMO schemes. We address the frequency-dependent nature of the THz channel by using a filter-bank-based channel model and a multi-bank orthogonal frequency division multiplexing (MB-OFDM) waveform design, which slices the wideband channel into smaller frequency-independent subbands. Specifically, we illustrate two different THz hybrid MIMO structures, one with a single precoder and combiner in the high sampling domain and another with a band-wise precoder design in the low sampling domain. We have adopted sub-optimal methods that alternatively optimize the beamformers. We evaluate the performance of our proposed MIMO schemes using numerical simulations that validate their feasibility and effectiveness in achieving communication in ultra-wideband frequency-dependent THz channels under various parameters and subband width assumptions. The results also indicate that the proposed MB-OFDM waveform design reduces the peak-to-average power ratio (PAPR) of the spatial streams compared to conventional OFDM.