Pub Date : 2023-07-01DOI: 10.1109/JSTSP.2023.3305128
Nan Yang;Chong Han;Josep Miquel Jornet;Peiying Zhu;Markku Juntti
Terahertz (THz) communications has been envisioned as an enabling and highly promising technology for the sixth generation (6G) and beyond wireless networks which aim to provide full and unlimited wireless connectivity for the ubiquitous intelligent information society of 2030 and beyond. In particular, the ultra-wide THz band from 0.1 to 10 THz offers enormous potential to alleviate the spectrum scarcity and break the capacity limitation of emerging wireless systems, such as the fifth generation (5G) wireless networks. This will undoubtedly support epoch-making wireless applications that demand ultra-high quality of service requirements and multi-terabits/s data transmission in the 6G and beyond era, such as holographic communications, immersive extended reality, ultra-fast backhaul and wireless local area networks, and wireless high-bandwidth secure transmission. Moreover, THz transceivers and antennas boast an incredibly compact size, reaching sub-millimetric dimensions. This miniaturization enables the seamless integration of extremely small radios into various environments, giving rise to ground-breaking applications, e.g., the Internet of Nano-Things and wireless networks-on-chip. Furthermore, the utilization of the THz band extends beyond traditional radar and localization, opening doors to novel wireless sensing capabilities and underpinning cutting-edge applications such as healthcare nano-bio-sensing. Due to the aforementioned advantages, an unprecedented amount of spectrum within the 0.275–0.45 THz band was opened for land mobile and fixed service in 6G after World Radio Conference 2019. Additionally, the IEEE 802.15.3 d standard has been established as the first wireless standard in the sub-THz band (specifically, 253–322 GHz) to support data rates of 100 gigabit/s and above.
{"title":"Guest Editorial Advanced Signal Processing for Terahertz Communications in 6G and Beyond Networks","authors":"Nan Yang;Chong Han;Josep Miquel Jornet;Peiying Zhu;Markku Juntti","doi":"10.1109/JSTSP.2023.3305128","DOIUrl":"https://doi.org/10.1109/JSTSP.2023.3305128","url":null,"abstract":"Terahertz (THz) communications has been envisioned as an enabling and highly promising technology for the sixth generation (6G) and beyond wireless networks which aim to provide full and unlimited wireless connectivity for the ubiquitous intelligent information society of 2030 and beyond. In particular, the ultra-wide THz band from 0.1 to 10 THz offers enormous potential to alleviate the spectrum scarcity and break the capacity limitation of emerging wireless systems, such as the fifth generation (5G) wireless networks. This will undoubtedly support epoch-making wireless applications that demand ultra-high quality of service requirements and multi-terabits/s data transmission in the 6G and beyond era, such as holographic communications, immersive extended reality, ultra-fast backhaul and wireless local area networks, and wireless high-bandwidth secure transmission. Moreover, THz transceivers and antennas boast an incredibly compact size, reaching sub-millimetric dimensions. This miniaturization enables the seamless integration of extremely small radios into various environments, giving rise to ground-breaking applications, e.g., the Internet of Nano-Things and wireless networks-on-chip. Furthermore, the utilization of the THz band extends beyond traditional radar and localization, opening doors to novel wireless sensing capabilities and underpinning cutting-edge applications such as healthcare nano-bio-sensing. Due to the aforementioned advantages, an unprecedented amount of spectrum within the 0.275–0.45 THz band was opened for land mobile and fixed service in 6G after World Radio Conference 2019. Additionally, the IEEE 802.15.3 d standard has been established as the first wireless standard in the sub-THz band (specifically, 253–322 GHz) to support data rates of 100 gigabit/s and above.","PeriodicalId":13038,"journal":{"name":"IEEE Journal of Selected Topics in Signal Processing","volume":"17 4","pages":"709-712"},"PeriodicalIF":7.5,"publicationDate":"2023-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/iel7/4200690/10284021/10284025.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"50274227","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-07-01DOI: 10.1109/JSTSP.2023.3306631
{"title":"IEEE Signal Processing Society Information","authors":"","doi":"10.1109/JSTSP.2023.3306631","DOIUrl":"https://doi.org/10.1109/JSTSP.2023.3306631","url":null,"abstract":"","PeriodicalId":13038,"journal":{"name":"IEEE Journal of Selected Topics in Signal Processing","volume":"17 4","pages":"C2-C2"},"PeriodicalIF":7.5,"publicationDate":"2023-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/iel7/4200690/10284021/10284022.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"50274203","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-07-01DOI: 10.1109/JSTSP.2023.3307906
Alejandro Cohen;Rafael G. L. D'Oliveira;Chia-Yi Yeh;Hichem Guerboukha;Rabi Shrestha;Zhaoji Fang;Edward W. Knightly;Muriel Médard;Daniel M. Mittleman
Security against eavesdropping is one of the key concerns in the design of any communication system. Many common considerations of the security of a wireless communication channel rely on comparing the signal level measured by Bob (the intended receiver) to that accessible to Eve (a single eavesdropper). Frameworks such as Wyner's wiretap model ensure the security of a link, in an average sense, when Bob's signal-to-noise ratio (SNR) exceeds Eve's. Unfortunately, because these guarantees rely on the noise realizations at Eve, statistically, Eve can still occasionally succeed in decoding information. The goal of achieving exactly zero probability of intercept over an engineered region of the broadcast sector, which we term absolute security, remains elusive. Here, we describe the first architecture for a wireless link with a single eavesdropper, that provides absolute security. I.e., a cryptographic deterministic and non-probabilistic security approach that does not rely on statistical assumptions about noise, shared secure key, or Eve's computational power. Our approach relies on the inherent properties of broadband and high-gain antennas, and is therefore ideally suited for implementation in millimeter-wave and terahertz wireless systems, where such antennas will generally be employed. We exploit spatial minima of the antenna pattern at different frequencies, the union of which defines a wide region where Eve is guaranteed to fail regardless of her computational capabilities, and regardless of the noise in the channels. Unlike conventional zero-forcing beam forming methods, we show that, for realistic assumptions about the antenna configuration and power budget, this absolute security guarantee can be achieved over most possible eavesdropper locations. Since we use relatively simple frequency-multiplexed coding, together with the underlying physics of a diffracting aperture, this idea is broadly applicable in many contexts.
{"title":"Absolute Security in Terahertz Wireless Links","authors":"Alejandro Cohen;Rafael G. L. D'Oliveira;Chia-Yi Yeh;Hichem Guerboukha;Rabi Shrestha;Zhaoji Fang;Edward W. Knightly;Muriel Médard;Daniel M. Mittleman","doi":"10.1109/JSTSP.2023.3307906","DOIUrl":"https://doi.org/10.1109/JSTSP.2023.3307906","url":null,"abstract":"Security against eavesdropping is one of the key concerns in the design of any communication system. Many common considerations of the security of a wireless communication channel rely on comparing the signal level measured by Bob (the intended receiver) to that accessible to Eve (a single eavesdropper). Frameworks such as Wyner's wiretap model ensure the security of a link, in an average sense, when Bob's signal-to-noise ratio (SNR) exceeds Eve's. Unfortunately, because these guarantees rely on the noise realizations at Eve, statistically, Eve can still occasionally succeed in decoding information. The goal of achieving \u0000<italic>exactly zero</i>\u0000 probability of intercept over an engineered region of the broadcast sector, which we term absolute security, remains elusive. Here, we describe the first architecture for a wireless link with a single eavesdropper, that provides absolute security. I.e., a cryptographic deterministic and non-probabilistic security approach that does not rely on statistical assumptions about noise, shared secure key, or Eve's computational power. Our approach relies on the inherent properties of broadband and high-gain antennas, and is therefore ideally suited for implementation in millimeter-wave and terahertz wireless systems, where such antennas will generally be employed. We exploit spatial minima of the antenna pattern at different frequencies, the union of which defines a wide region where Eve is guaranteed to fail regardless of her computational capabilities, and regardless of the noise in the channels. Unlike conventional zero-forcing beam forming methods, we show that, for realistic assumptions about the antenna configuration and power budget, this absolute security guarantee can be achieved over most possible eavesdropper locations. Since we use relatively simple frequency-multiplexed coding, together with the underlying physics of a diffracting aperture, this idea is broadly applicable in many contexts.","PeriodicalId":13038,"journal":{"name":"IEEE Journal of Selected Topics in Signal Processing","volume":"17 4","pages":"819-833"},"PeriodicalIF":7.5,"publicationDate":"2023-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"50397111","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This article studies the channel estimation for wideband multiple-input multiple-output (MIMO) systems equipped with hybrid analog/digital transceivers operating in the millimeter-wave (mmWave) or terahertz (THz) bands. By exploiting the low-rank property of the concatenated channel matrix of the delay taps, we formulate the channel estimation problem as a low-rank matrix sensing (LRMS) problem and solve it using a low-complexity generalized conditional gradient-alternating minimization (GCG-ALTMIN) algorithm. This LRMS-based solution can accommodate different precoder/combiner and training structures. In addition, it does not require knowledge about the array responses at the transceivers, in contrast to most existing solutions allowing low training overhead. Furthermore, a preconditioned conjugate gradient (PCG) algorithm-based implementation and a low-rank matrix completion (LRMC) formulation are proposed to further reduce the computational complexity. In order to enhance the channel estimation performance for fat and tall channel matrices, we introduce a matrix reshaping approach that can preserve the channel rank by exploiting the shift-invariance property of uniform arrays. We also introduce a spectrum denoising (SD) approach for further improving the performance when the array responses are known and the number of paths is small. These approaches can effectively enhance the performance at a given training overhead. Simulation results suggest that the proposed solutions can achieve higher channel estimation accuracy and reduce the computational complexity as compared to several representative channel estimation schemes.
{"title":"Low-Rank Matrix Sensing-Based Channel Estimation for mmWave and THz Hybrid MIMO Systems","authors":"Khawaja Fahad Masood;Jun Tong;Jiangtao Xi;Jinhong Yuan;Qinghua Guo;Yanguang Yu","doi":"10.1109/JSTSP.2023.3288703","DOIUrl":"https://doi.org/10.1109/JSTSP.2023.3288703","url":null,"abstract":"This article studies the channel estimation for wideband multiple-input multiple-output (MIMO) systems equipped with hybrid analog/digital transceivers operating in the millimeter-wave (mmWave) or terahertz (THz) bands. By exploiting the low-rank property of the concatenated channel matrix of the delay taps, we formulate the channel estimation problem as a low-rank matrix sensing (LRMS) problem and solve it using a low-complexity generalized conditional gradient-alternating minimization (GCG-ALTMIN) algorithm. This LRMS-based solution can accommodate different precoder/combiner and training structures. In addition, it does not require knowledge about the array responses at the transceivers, in contrast to most existing solutions allowing low training overhead. Furthermore, a preconditioned conjugate gradient (PCG) algorithm-based implementation and a low-rank matrix completion (LRMC) formulation are proposed to further reduce the computational complexity. In order to enhance the channel estimation performance for fat and tall channel matrices, we introduce a matrix reshaping approach that can preserve the channel rank by exploiting the shift-invariance property of uniform arrays. We also introduce a spectrum denoising (SD) approach for further improving the performance when the array responses are known and the number of paths is small. These approaches can effectively enhance the performance at a given training overhead. Simulation results suggest that the proposed solutions can achieve higher channel estimation accuracy and reduce the computational complexity as compared to several representative channel estimation schemes.","PeriodicalId":13038,"journal":{"name":"IEEE Journal of Selected Topics in Signal Processing","volume":"17 4","pages":"777-793"},"PeriodicalIF":7.5,"publicationDate":"2023-06-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"50274209","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-06-15DOI: 10.1109/JSTSP.2023.3286700
Evangelos N. Papasotiriou;Sotiris Droulias;Angeliki Alexiou
The terahertz (THz) frequency band has recently attracted considerable attention in wireless communications as potential candidate for providing the necessary high bandwidth for demanding applications. With increasing frequency, however, the communication link becomes more vulnerable to blockage, and pathloss increases. While both effects can be mitigated with the judicious utilization of directional beams and Reconfigurable Intelligent Surfaces (RISs), high directivity could potentially increase the probability of undesired misalignment between the beam that is steered by the RIS, and the user. It is therefore crucial to characterize and understand the stochastic behavior of misalignment in RIS-aided THz links. In this work, beam misalignment in RIS-aided links is studied theoretically and analytical models are derived, the validity of which is verified through numerical calculations. It is demonstrated that there is a distinction in the stochastic behavior of misalignment between pointing errors that occur on the steering plane or normally to the steering plane, with direct consequences on the link robustness on misalignment. The analytical models capture the impact of misalignment under these qualitatively different conditions and provide the necessary tools for assessing the stochastic RIS performance with respect to crucial link parameters, such as the transmitter's beam width, the transmitter-RIS distance, the RIS-receiver distance, and the steering angle of the RIS.
{"title":"Analytical Characterization of RIS-Aided Terahertz Links in the Presence of Beam Misalignment","authors":"Evangelos N. Papasotiriou;Sotiris Droulias;Angeliki Alexiou","doi":"10.1109/JSTSP.2023.3286700","DOIUrl":"https://doi.org/10.1109/JSTSP.2023.3286700","url":null,"abstract":"The terahertz (THz) frequency band has recently attracted considerable attention in wireless communications as potential candidate for providing the necessary high bandwidth for demanding applications. With increasing frequency, however, the communication link becomes more vulnerable to blockage, and pathloss increases. While both effects can be mitigated with the judicious utilization of directional beams and Reconfigurable Intelligent Surfaces (RISs), high directivity could potentially increase the probability of undesired misalignment between the beam that is steered by the RIS, and the user. It is therefore crucial to characterize and understand the stochastic behavior of misalignment in RIS-aided THz links. In this work, beam misalignment in RIS-aided links is studied theoretically and analytical models are derived, the validity of which is verified through numerical calculations. It is demonstrated that there is a distinction in the stochastic behavior of misalignment between pointing errors that occur on the steering plane or normally to the steering plane, with direct consequences on the link robustness on misalignment. The analytical models capture the impact of misalignment under these qualitatively different conditions and provide the necessary tools for assessing the stochastic RIS performance with respect to crucial link parameters, such as the transmitter's beam width, the transmitter-RIS distance, the RIS-receiver distance, and the steering angle of the RIS.","PeriodicalId":13038,"journal":{"name":"IEEE Journal of Selected Topics in Signal Processing","volume":"17 4","pages":"850-860"},"PeriodicalIF":7.5,"publicationDate":"2023-06-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"50274204","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-06-13DOI: 10.1109/JSTSP.2023.3285431
Yijin Pan;Cunhua Pan;Shi Jin;Jiangzhou Wang
The affordable hardware cost of ultra-large (XL) reconfigurable intelligent surfaces (RIS) renders them attractive solutions for the performance enhancement of localization and communication systems. However, XL-RIS results in near-field propagation channels, especially for the high-frequency terahertz (THz) communication system, which poses significant challenges for localization and channel estimation. In this article, we focus on the spherical wavefront propagation in the near field of the THz system with the assistance of a RIS. A near-field channel estimation and localization (NF-JCEL) algorithm is proposed based on the derived second-order Fresnel approximation of the near-field channel model. To be specific, we carefully devise a down-sampled Toeplitz covariance matrix, which enables the decoupling and separate estimation of user equipment (UE) distances and angles of arrival (AoAs). Using the sub-space based method and one-dimensional search, we estimate the angles of arrival (AoAs) and user equipment (UE) distances. The channel attenuation coefficients are obtained through the least square (LS) method. To alleviate the impact of THz channel fading peaks caused by molecular absorption, estimates on multiple sub-bands are utilized for location estimation. Simulation results validate the superiority of the proposed NF-JCEL algorithm to the conventional far-field algorithm and show that higher resolution accuracy can be obtained by the proposed algorithm.
{"title":"RIS-Aided Near-Field Localization and Channel Estimation for the Terahertz System","authors":"Yijin Pan;Cunhua Pan;Shi Jin;Jiangzhou Wang","doi":"10.1109/JSTSP.2023.3285431","DOIUrl":"https://doi.org/10.1109/JSTSP.2023.3285431","url":null,"abstract":"The affordable hardware cost of ultra-large (XL) reconfigurable intelligent surfaces (RIS) renders them attractive solutions for the performance enhancement of localization and communication systems. However, XL-RIS results in near-field propagation channels, especially for the high-frequency terahertz (THz) communication system, which poses significant challenges for localization and channel estimation. In this article, we focus on the spherical wavefront propagation in the near field of the THz system with the assistance of a RIS. A near-field channel estimation and localization (NF-JCEL) algorithm is proposed based on the derived second-order Fresnel approximation of the near-field channel model. To be specific, we carefully devise a down-sampled Toeplitz covariance matrix, which enables the decoupling and separate estimation of user equipment (UE) distances and angles of arrival (AoAs). Using the sub-space based method and one-dimensional search, we estimate the angles of arrival (AoAs) and user equipment (UE) distances. The channel attenuation coefficients are obtained through the least square (LS) method. To alleviate the impact of THz channel fading peaks caused by molecular absorption, estimates on multiple sub-bands are utilized for location estimation. Simulation results validate the superiority of the proposed NF-JCEL algorithm to the conventional far-field algorithm and show that higher resolution accuracy can be obtained by the proposed algorithm.","PeriodicalId":13038,"journal":{"name":"IEEE Journal of Selected Topics in Signal Processing","volume":"17 4","pages":"878-892"},"PeriodicalIF":7.5,"publicationDate":"2023-06-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"50397109","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
We propose a communication framework suitable for data rate maximization in the Terahertz (THz) bands using adaptive Orthogonal Frequency Division Multiplexing (OFDM) numerology and carrier aggregation. OFDM is a widely adopted waveform due to the simplicity of its implementation and its effectiveness in combating frequency selectivity when the numerology is carefully chosen. However, it suffers from a multitude of limitations, including phase noise due to local oscillator inaccuracies, high peak-to-average power ratio, and is particularly sensitive to time-frequency synchronization errors, which can considerably impact its performance. This is especially relevant at THz frequencies where larger-than-usual bandwidth is available, and the choice of the numerology should be carefully made given the intrinsic transceiver constraints. Moreover, the abundance of frequency resources in the THz band imposes new design challenges that should be addressed, especially since the bandwidth usability at these frequencies depends on the communication distance. Hence, we propose a dynamic OFDM numerology adaptation mechanism, where the bandwidth of a Component Carrier (CC) covered by a single OFDM waveform is changed. For each CC, the Component Carrier Data Rate (CCDR) is evaluated while considering the effect of both hardware impairments and the wireless channel statistics. We further propose the adoption of a dynamic distance-aware CC allocation such that the available frequency resources are fully utilized, and maximize an Aggregated Data Rate (ADR) through the aggregation of several CCs. Simulation results show that the proposed approach yields the highest ADR out of all possible setups.
{"title":"Adapt and Aggregate: Adaptive OFDM Numerology and Carrier Aggregation for High Data Rate Terahertz Communications","authors":"Lutfi Samara;Tommaso Zugno;Mate Boban;Malte Schellmann;Thomas Kürner","doi":"10.1109/JSTSP.2023.3285448","DOIUrl":"https://doi.org/10.1109/JSTSP.2023.3285448","url":null,"abstract":"We propose a communication framework suitable for data rate maximization in the Terahertz (THz) bands using adaptive Orthogonal Frequency Division Multiplexing (OFDM) numerology and carrier aggregation. OFDM is a widely adopted waveform due to the simplicity of its implementation and its effectiveness in combating frequency selectivity when the numerology is carefully chosen. However, it suffers from a multitude of limitations, including phase noise due to local oscillator inaccuracies, high peak-to-average power ratio, and is particularly sensitive to time-frequency synchronization errors, which can considerably impact its performance. This is especially relevant at THz frequencies where larger-than-usual bandwidth is available, and the choice of the numerology should be carefully made given the intrinsic transceiver constraints. Moreover, the abundance of frequency resources in the THz band imposes new design challenges that should be addressed, especially since the bandwidth usability at these frequencies depends on the communication distance. Hence, we propose a dynamic OFDM numerology adaptation mechanism, where the bandwidth of a Component Carrier (CC) covered by a single OFDM waveform is changed. For each CC, the Component Carrier Data Rate (CCDR) is evaluated while considering the effect of both hardware impairments and the wireless channel statistics. We further propose the adoption of a dynamic distance-aware CC allocation such that the available frequency resources are fully utilized, and maximize an Aggregated Data Rate (ADR) through the aggregation of several CCs. Simulation results show that the proposed approach yields the highest ADR out of all possible setups.","PeriodicalId":13038,"journal":{"name":"IEEE Journal of Selected Topics in Signal Processing","volume":"17 4","pages":"794-805"},"PeriodicalIF":7.5,"publicationDate":"2023-06-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"50274208","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-06-13DOI: 10.1109/JSTSP.2023.3285450
Lasantha Thakshila Wedage;Bernard Butler;Sasitharan Balasubramaniam;Yevgeni Koucheryavy;Mehmet C. Vuran
Reliable Terahertz (THz) links are necessary for outdoor point-to-point communication with the exponential growth of wireless data traffic. This study presents a modified Monte Carlo simulation procedure for estimating THz link attenuation due to multiple scattering by charged dust particles on the THz beam propagation path. Scattering models are developed for beams through dust, based on Mie and Rayleigh approximations for corresponding frequencies on Earth (0.24 THz) and Mars (0.24 & 1.64 THz). The simulation results are compared, considering parameters such as the number of Monte-Carlo photon (MCP) packets, visibility, dust particle placement density along the beam, frequency, and distance between the transmitter and the receiver. Moreover, a channel capacity model was proposed, considering THz link attenuation due to dust storms, spreading loss, and molecular absorption loss for Earth and Mars outdoor environments. Simulation results for Earth show that the link attenuation increases with dust particle placement density, distance, and frequency, and attenuation decreases with visibility and MCP packets. On Mars, similar results are obtained for both frequencies, except that the attenuation varies around a constant value with the frequency increase. Moreover, attenuation is slightly higher at 0.24 THz frequency compared to 1.64 THz when more dust particles are present on the beam propagation path. Channel capacity is estimated for Earth and Mars environments considering time and distance-dependent scenarios. Time windows that show a sudden drop of dust particles along the beam provide opportunities to communicate with high reliability. Moreover, increasing the distance between the transmitter and receiver severely reduces the channel capacity measurement in strong dust storm conditions in both environments. Our study has found that weak dust storms have relatively little effect on Mars but much more significant effects on Earth.
{"title":"Comparative Analysis of Terahertz Propagation Under Dust Storm Conditions on Mars and Earth","authors":"Lasantha Thakshila Wedage;Bernard Butler;Sasitharan Balasubramaniam;Yevgeni Koucheryavy;Mehmet C. Vuran","doi":"10.1109/JSTSP.2023.3285450","DOIUrl":"https://doi.org/10.1109/JSTSP.2023.3285450","url":null,"abstract":"Reliable Terahertz (THz) links are necessary for outdoor point-to-point communication with the exponential growth of wireless data traffic. This study presents a modified Monte Carlo simulation procedure for estimating THz link attenuation due to multiple scattering by charged dust particles on the THz beam propagation path. Scattering models are developed for beams through dust, based on Mie and Rayleigh approximations for corresponding frequencies on Earth (0.24 THz) and Mars (0.24 & 1.64 THz). The simulation results are compared, considering parameters such as the number of Monte-Carlo photon (MCP) packets, visibility, dust particle placement density along the beam, frequency, and distance between the transmitter and the receiver. Moreover, a channel capacity model was proposed, considering THz link attenuation due to dust storms, spreading loss, and molecular absorption loss for Earth and Mars outdoor environments. Simulation results for Earth show that the link attenuation increases with dust particle placement density, distance, and frequency, and attenuation decreases with visibility and MCP packets. On Mars, similar results are obtained for both frequencies, except that the attenuation varies around a constant value with the frequency increase. Moreover, attenuation is slightly higher at 0.24 THz frequency compared to 1.64 THz when more dust particles are present on the beam propagation path. Channel capacity is estimated for Earth and Mars environments considering time and distance-dependent scenarios. Time windows that show a sudden drop of dust particles along the beam provide opportunities to communicate with high reliability. Moreover, increasing the distance between the transmitter and receiver severely reduces the channel capacity measurement in strong dust storm conditions in both environments. Our study has found that weak dust storms have relatively little effect on Mars but much more significant effects on Earth.","PeriodicalId":13038,"journal":{"name":"IEEE Journal of Selected Topics in Signal Processing","volume":"17 4","pages":"745-760"},"PeriodicalIF":7.5,"publicationDate":"2023-06-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"50397108","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This article presents a comprehensive study for analyzing and modeling the scattering phenomenon of terahertz (THz) waves bouncing on rough surfaces. More specifically, a generic parametric methodology to accurately model the rough characteristics focusing on the root-mean-square (RMS) height and correlation length of a surface is proposed. Firstly, a Monte Carlo-based approach is developed for the efficient and accurate software realization of such rough surfaces. Then, the full-wave simulator FEKO is used to simulate at 300 GHz the far-field behavior of scattering waves on 30 distinct surfaces having 6 RMS heights and 5 correlation lengths. By employing the directive scattering (DS) model, the variation of the scattering coefficient, $S$ , and its equivalent roughness, $alpha _{R}$ , are studied for the scattering amplitude aspect. Furthermore, the statistical characteristics of the phase and polarization of the scattered signals are obtained and compared with those available in existing 3GPP channel model standards which are valid for lower frequency bands. These comparisons show that although the phases follow the normal distribution, as is the case with equivalent 3GPP channel models, the cross-polarization ratios (XPRs) follow the logistic distribution. This is an important difference which could have a great impact on the standardization activities of the current 3GPP-related working groups. Finally, the proposed scattering model at the THz band is realized through an algorithmic implementation. Compared with the classical two-dimensional DS model which characterizes only the amplitude of the scattered signal, the proposed three-dimensional scattering model can be efficiently used to accurately characterize all the important parameters of the scattered signals, namely, amplitude, phase, and polarization at the THz band. Additionally, the proposed scattering model can effectively work in conjunction with ray-tracing (RT) schemes leading to precise scattering and channel modeling for new applications, such as holographic radios and multi-user multiple-input multiple-output (MU-MIMO) systems.
{"title":"Full-Wave Simulation and Scattering Modeling for Terahertz Communications","authors":"Haofan Yi;Ke Guan;P. Takis Mathiopoulos;Pengxiang Xie;Danping He;Jianwu Dou;Zhangdui Zhong","doi":"10.1109/JSTSP.2023.3285099","DOIUrl":"https://doi.org/10.1109/JSTSP.2023.3285099","url":null,"abstract":"This article presents a comprehensive study for analyzing and modeling the scattering phenomenon of terahertz (THz) waves bouncing on rough surfaces. More specifically, a generic parametric methodology to accurately model the rough characteristics focusing on the root-mean-square (RMS) height and correlation length of a surface is proposed. Firstly, a Monte Carlo-based approach is developed for the efficient and accurate software realization of such rough surfaces. Then, the full-wave simulator FEKO is used to simulate at 300 GHz the far-field behavior of scattering waves on 30 distinct surfaces having 6 RMS heights and 5 correlation lengths. By employing the directive scattering (DS) model, the variation of the scattering coefficient, \u0000<inline-formula><tex-math>$S$</tex-math></inline-formula>\u0000, and its equivalent roughness, \u0000<inline-formula><tex-math>$alpha _{R}$</tex-math></inline-formula>\u0000, are studied for the scattering amplitude aspect. Furthermore, the statistical characteristics of the phase and polarization of the scattered signals are obtained and compared with those available in existing 3GPP channel model standards which are valid for lower frequency bands. These comparisons show that although the phases follow the normal distribution, as is the case with equivalent 3GPP channel models, the cross-polarization ratios (XPRs) follow the logistic distribution. This is an important difference which could have a great impact on the standardization activities of the current 3GPP-related working groups. Finally, the proposed scattering model at the THz band is realized through an algorithmic implementation. Compared with the classical two-dimensional DS model which characterizes only the amplitude of the scattered signal, the proposed three-dimensional scattering model can be efficiently used to accurately characterize all the important parameters of the scattered signals, namely, amplitude, phase, and polarization at the THz band. Additionally, the proposed scattering model can effectively work in conjunction with ray-tracing (RT) schemes leading to precise scattering and channel modeling for new applications, such as holographic radios and multi-user multiple-input multiple-output (MU-MIMO) systems.","PeriodicalId":13038,"journal":{"name":"IEEE Journal of Selected Topics in Signal Processing","volume":"17 4","pages":"713-728"},"PeriodicalIF":7.5,"publicationDate":"2023-06-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"50274920","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Next-generation wireless networks will see the convergence of communication and sensing, also exploiting the availability of large bandwidths in the THz spectrum and electrically large antenna arrays on handheld devices. In particular, it is envisaged that user devices will be able to automatically scan their surroundings by steering a very narrow antenna beam and collecting echoes reflected by objects and walls. These data will be utilized to derive a map of the surrounding indoor environment and infer users' trajectories using simultaneous localization and mapping (SLAM) techniques. In this article, we address this scenario by proposing original radio-SLAM (R-SLAM) algorithms, derived from image processing techniques, to map the environment and pinpoint the device position in the map starting from measurements sensed by a mobile THz radar. Initially, to fully understand the THz backscattering phenomenon, we provide an experimental characterization of the THz backscattering channel in indoor environments. Then, the performance of the proposed algorithms is assessed using real-world THz radar measurements and is compared with state-of-the-art SLAM techniques, demonstrating the superiority of the proposed approaches.
{"title":"Radio SLAM for 6G Systems at THz Frequencies: Design and Experimental Validation","authors":"Marina Lotti;Gianni Pasolini;Anna Guerra;Francesco Guidi;Raffaele D'Errico;Davide Dardari","doi":"10.1109/JSTSP.2023.3285101","DOIUrl":"https://doi.org/10.1109/JSTSP.2023.3285101","url":null,"abstract":"Next-generation wireless networks will see the convergence of communication and sensing, also exploiting the availability of large bandwidths in the THz spectrum and electrically large antenna arrays on handheld devices. In particular, it is envisaged that user devices will be able to automatically scan their surroundings by steering a very narrow antenna beam and collecting echoes reflected by objects and walls. These data will be utilized to derive a map of the surrounding indoor environment and infer users' trajectories using simultaneous localization and mapping (SLAM) techniques. In this article, we address this scenario by proposing original radio-SLAM (R-SLAM) algorithms, derived from image processing techniques, to map the environment and pinpoint the device position in the map starting from measurements sensed by a mobile THz radar. Initially, to fully understand the THz backscattering phenomenon, we provide an experimental characterization of the THz backscattering channel in indoor environments. Then, the performance of the proposed algorithms is assessed using real-world THz radar measurements and is compared with state-of-the-art SLAM techniques, demonstrating the superiority of the proposed approaches.","PeriodicalId":13038,"journal":{"name":"IEEE Journal of Selected Topics in Signal Processing","volume":"17 4","pages":"834-849"},"PeriodicalIF":7.5,"publicationDate":"2023-06-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/iel7/4200690/10284021/10148622.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"50274205","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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