TeraMIMO: A Channel Simulator for Wideband Ultra-Massive MIMO Terahertz Communications

Abstract

Following recent advances in terahertz (THz) technology, there is a consensus on the crucial role of THz communications in the next generation of wireless systems. Aiming at catalyzing THz communications research, we propose TeraMIMO, an accurate stochastic MATLAB simulator of statistical THz channels. We simulate ultra-massive multiple-input multipleoutput antenna configurations as critical infrastructure enablers that overcome the limitation in THz communications distances. We consider both line-of-sight and multipath components and propose frequency-and delay-domain implementations for singleand multi-carrier paradigms in both time-invariant and timevariant scenarios. We implement exhaustive molecular absorption computations based on radiative transfer theory alongside alternative sub-THz approximations. We further model THz-specific constraints, including wideband beam split effects, spherical wave propagation, and misalignment fading. We verify TeraMIMO by analogy with measurement-based channel models in the literature and ergodic capacity analysis. We introduce a graphical user interface and a guide for using TeraMIMO in THz channel generation and analyses.

Phase Shift Optimization Algorithm for Achievable Rate Maximization in Reconfigurable Intelligent Surface-Assisted THz Communications

“…Algorithm 1 summarizes all the steps of the proposed method. It is important to note that while we assumed a clustered channel model with LOS and NLOS components and with path loss modelled according to [35,42], recent works [40] are trying to define more accurate THz channel models, which may provide more insight on the achievable gains of THz systems. However, the proposed RIS optimization algorithm is not dependent on a specific channel model and can be directly applied to improved models that may arise in the future.…”

“…s N s ] T , with s i ∈ C corresponding to an amplitude and phase modulated symbol and E s 2 = N s . We consider a typical discrete-time complex baseband representation for the received signal, which is a vector-based representation that is often adopted in signal processing works for MIMO communications in the THz band [6,27,40]. It allows modeling the effect on the amplitude and phase of the information symbols after passing through all possible transmit-RIS-receiver array links and after being processed by the precoder and combiner.…”

Single- versus Multi-Carrier Terahertz-Band Communications: A Comparative Study

“…We aim to evaluate the performance of candidate SC/MC schemes in realistic THz settings, including massive antenna dimensions and ultra-wide BWs. We adopt the array-ofsubarrays (AoSA) architecture of TeraMIMO [44], in which each subarray (SA) is composed of many antenna elements (AEs), as depicted in Fig. 1.…”

“…Hardware imperfections include PA non-linearity, wideband in/quadrature-phase imbalance (IQI) [40], phase uncertainty in the phase-shifters (PSs) [41], and PHN (studied for SC schemes [42] and CP-OFDM [43] in sub-THz and THz [40] systems). THz channelinduced phenomena such as beam split and misalignment [44] are also critical, especially with UM-MIMO systems. Moreover, the synchronization becomes more challenging with carrier frequency offset (CFO) and symbol-timing offset (STO) at THz frequencies.…”

“…• We study the THz compatibility of multiple modulation schemes, namely, SC-FDE, CP-OFDM, DFT-s-OFDM, OTFS, and OQAM/FBMC, adopting our newly developed accurate THz channel model/simulator (TeraMIMO [44]). ), and 𝑗 = √ −1 denote the Kronecker product, remainder modulo 𝑁, inner product, real part, and imaginary unit, respectively.…”