Comparison of Transmission Concepts for Indoor THz Communication Systems

Schram, Viktoria; Wu, Yifei; Kolleshi, Monika; Gerstacker, Wolfgang H.

doi:10.1109/iwmts49292.2020.9166303

Cited by 8 publications

(6 citation statements)

References 14 publications

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“…SC systems are found superior to CP-OFDM in mmWave systems [48]. For indoor THz scenarios, SC-FDMA with linear equalization is shown to be superior to CP-OFDM and SC with linear-/decision-feedback-equalization [49].…”

Section: Introductionmentioning

confidence: 94%

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

Tarboush¹,

Sarieddeen²,

Alouini³

et al. 2021

Preprint

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The prospects of utilizing single-carrier (SC) and multi-carrier (MC) waveforms in future terahertz (THz)-band communication systems remain unresolved. On the one hand, the limited multi-path (MP) components at high frequencies result in frequency-flat channels that favor low-complexity wideband SC systems. On the other hand, frequency-dependent molecular absorption and transceiver characteristics and the existence of MP components in indoor sub-THz systems can still result in frequency-selective channels, favoring off-the-shelf MC schemes such as orthogonal frequency-division multiplexing (OFDM). Variations of SC/MC designs result in different THz spectrum utilization, but spectral efficiency is not the primary concern with substantial available bandwidths; baseband complexity, power efficiency, and hardware impairment constraints are predominant. This paper presents a comprehensive study of SC/MC modulations for THz communications, utilizing an accurate wideband THz channel model and highlighting the various performance and complexity trade-offs of the candidate schemes. Simulations demonstrate the robustness of discrete-Fourier-transform spread OFDM (DFT-s-OFDM) to THz impairments and orthogonal time-frequency space (OTFS) to THz Doppler spreads.

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Section: Introductionmentioning

confidence: 94%

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

Tarboush¹,

Sarieddeen²,

Alouini³

et al. 2021

Preprint

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show abstract

“…For instance, there may exist possible reflectors close to the LoS path, yielding additional reflected paths; Besides, combined reflection and transmission of THz signals on a multi-layer objects like window glass also contribute to multiple available paths. Furthermore, when the communication bandwidth is sufficiently high, frequency-selective channel fading should be considered even for LoS scenario without multi-path propagation [36]. Hence, in this subsection, the proposed flexible IM-aided pilot design is extended to the frequency-selective fading channel, where some guidelines about the generalized design will be provided.…”

Section: Extension To Frequency-selective Fading Channelmentioning

confidence: 99%

“…At the receiver, for the k-th data block, the index pattern can be coarsely estimated using the channel estimate of the (k−1)-th data block as the prior knowledge of CSI. Note that a fixed pilot sequence is required to provide initial chan- caused by the frequency selectivity of THz channels [36]. Afterwards, a correlation-based method could be utilized to detect the index of pilot sequences.…”

Section: Extension To Frequency-selective Fading Channelmentioning

confidence: 99%

Terahertz Wireless Communications With Flexible Index Modulation Aided Pilot Design

Mao

Hanzo

2021

IEEE J. Select. Areas Commun.

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Terahertz (THz) wireless communication is envisioned as a promising technology, which is capable of providing ultra-high-rate transmission up to Terabit per second. However, some hardware imperfections, which are generally neglected in the existing literature concerning lower data rates and traditional operating frequencies, cannot be overlooked in the THz systems. Hardware imperfections usually consist of phase noise, in-phase/quadrature imbalance, and nonlinearity of power amplifier. Due to the timevariant characteristic of phase noise, frequent pilot insertion is required, leading to decreased spectral efficiency. In this paper, to address this issue, a novel pilot design strategy is proposed based on index modulation (IM), where the positions of pilots are flexibly changed in the data frame, and additional information bits can be conveyed by indices of pilots. Furthermore, a turbo receiving algorithm is developed, which jointly performs the detection of pilot indices and channel estimation in an iterative manner. It is shown that the proposed turbo receiver works well even under the situation where the prior knowledge of channel state information is outdated. Analytical and simulation results validate that the proposed schemes achieve significant enhancement of bit-error rate performance and channel estimation accuracy, whilst attaining higher spectral efficiency in comparison with its classical counterpart.

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“…Besides the ultra-high bandwidth, THz wireless technology has the advantage that it could be deployed much faster and more ef iciently than optical iber systems, especially in a high-density urban environment [4]. Moreover, THz communications are highly suited to the indoor environ-ment since THz communications systems can utilize the Non-Line-Of-Sight (NLOS) Multipath Components (MPCs) to enhance the link quality in indoor application [5], [6]. However, NLOS MPCs result in a highly frequencyselective channel, which requires the transmission system to deal with the Inter-Symbol Interference (ISI) effect.…”

Section: Introductionmentioning

confidence: 99%

Hierarchical beam alignment in SU-MIMO terahertz communications

Wu¹,

Koch²,

Vossiek³

et al. 2021

ITU-J FET

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Single-Carrier Frequency Division Multiple Access (SC-FDMA) is a promising technique for high data rate indoor Terahertz (THz) communications in future beyond 5G systems. In an indoor propagation scenario, the Line-Of-Sight (LOS) component may be blocked by the obstacles. Thus, efficient THz SC-FDMA communications require a fast and reliable Beam Alignment (BA) method for both LOS and Non-Line-Of-Sight (NLOS) scenarios. In this paper, we first adopt the hierarchical discrete Fourier transform codebook for LOS BA, and introduce the hierarchical k-means codebook for NLOS BA to improve the beamforming gain. Simulation results illustrate that the hierarchical DFT codebook and the hierarchical k-means codebook can achieve the beamforming gain close to that of the maximum ratio transmission in LOS and NLOS cases, respectively. Based on these two codebooks, we propose a Multi-Armed Bandit (MAB) algorithm named Hierarchical Beam Alignment (HBA) for single-user SC-FDMA THz systems to reduce the BA latency. HBA utilizes a hierarchical structure in the adopted codebook and prior knowledge regarding the noise power to speed up the BA process. Both theoretical analysis and simulation results indicate that the proposed BA method converges to the optimal beam with high probability for both the hierarchical DFT codebook and the hierarchical k-means codebook in the LOS and NLOS scenarios, respectively. The latency introduced by HBA is significantly lower when compared to an exhaustive search method and other MAB-based methods.

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Comparison of Transmission Concepts for Indoor THz Communication Systems

Cited by 8 publications

References 14 publications

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

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

Terahertz Wireless Communications With Flexible Index Modulation Aided Pilot Design

Hierarchical beam alignment in SU-MIMO terahertz communications

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