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Cross-Field Channel Estimation for Ultra Massive-MIMO THz Systems

IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS 2024年第8期23卷 8619-8635页

作者： Tarboush, Simon Ali, Anum Al-Naffouri, Tareq Y. Samsung Res Amer Stand & Mobil Innovat Lab Plano TX 75023 USA King Abdullah Univ Sci & Technol KAUST Elect & Comp Engn Program Comp Elect & Math Sci & Engn CEMSE Div Thuwal 23955 Saudi Arabia

The large bandwidth combined with ultra-massive multiple-input multiple-output (UM-MIMO) arrays enables terahertz (THz) systems to achieve terabits-per-second throughput. The THz systems are expected to operate in the near, intermediate, as well as the far-field. As such, channel estimation strategies suitable for the near, intermediate, or far-field have been introduced in the literature. In this work, we propose a cross-field, i.e., able to operate in near, intermediate, and far-field, compressive channel estimation strategy. For an array-of-subarrays (AoSA) architecture, the proposed method compares the received signals across the arrays to determine whether a near, intermediate, or far-field channel estimation approach will be appropriate. Subsequently, compressed estimation is performed in which the proximity of multiple subarrays (SAs) at the transmitter and receiver is exploited to reduce computational complexity and increase estimation accuracy. Numerical results show that the proposed method can enhance channel estimation accuracy and complexity at all distances of interest.

关键词： Near-field far-field intermediate-field spherical wave model planar wave model hybrid spherical-planar wave model array-of-subarrays Near-field far-field intermediate-field spherical wave model planar wave model hybrid spherical-planar wave model array-of-subarrays

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Analysis of Indoor THz Communication Systems With Finite-Bit DACs and ADCs

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IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY 2022年第1期71卷 375-390页

作者： Zhang, Yujiao Li, Dan Qiao, Deli Zhang, Lei East China Normal Univ Sch Commun & Elect Engn Shanghai 200241 Peoples R China Huawei Technol Inc Chengdu Peoples R China Univ Glasgow Sch Engn Glasgow G12 8QQ Lanark Scotland

Terahertz (THz) communication is foreseen to be a key technology for the 6G wireless communications. In this paper, the performance of downlink Terahertz (THz) communication systems with low-resolution digital-to-analog converters (DACs) at the Access Point (AP) and/or finite-bit analog-to-digital converters (ADCs) at the user sides are investigated. array-of-subarrays architecture is assumed at the AP, where each RF chain uniquely activates a disjoint subset of antennas, each of which is connected to an exclusive phase shifter. Hybrid precodings including maximum ratio transmission (MRT) and zero-forcing (ZF) precoding are considered. The best beamsteering direction for the phase shifters in the large subarray antenna regime is first proved to be the direction of the line-of-sight (LOS) path. Subsequently, the closed-form expression of the lower-bound of the achievable rate in the large subarray antenna regime is derived, which is the same for both MRT and ZF and is independent of the transmit power. Moreover, numerical results show that the rate loss caused by the phase uncertainties can be negligible in large subarray antenna regime and moderate resolution DACs and ADCs can achieve performance close to the infinite-resolution one. Numerical results validating the analysis are provided as well. Overall, the impact of finite-bit precoding and finite-bit ADCs on the achievable rate of indoor THz communication systems is characterized.

关键词： Precoding Communication systems Antennas Antenna arrays Massive MIMO Transmitting antennas Quantization (signal) Terahertz communication systems array-of-subarrays finite-bit DAC finite-bit ADC hybrid precoding

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Energy Efficiency of Indoor THz Communication Systems with Finite-bit DACs/ADCs under Minimum Rate Constraints

Energy Efficiency of Indoor THz Communication Systems with F...

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IEEE/CIC International Conference on Communications in China (ICCC)

作者： Zhang, Yujiao Qiao, Deli East China Normal Univ Sch Commun & Elect Engn Shanghai Peoples R China Southeast Univ Natl Mobile Commun Res Lab Nanjing Peoples R China

ISBN: (数字)9781665484800

ISBN: (纸本)9781665484800

Terahertz (THz) communication is expected to be a key technology of next-generation wireless communication. In this paper, we study the energy efficiency of an indoor THz communication system employing array-of-subarray structure. In the system, each radio frequency (RF) chain is connected with one antenna subarray and finite-bit digital-to-analog converters (DACs) at the access point (AP) side or analog-to-digital converters (ADCs) at user side. We assume minimum achievable rate constraint to satisfy the communication requirements and propose a joint power and subarray optimization policy to maximize the energy efficiency, which is the division of the sum achievable rate and total power consumption including the transmission power and circuit power given by the up-to-date studies. Specifically, the energy efficiency maximization problem is decomposed into subproblems of finding the optimal power allocation and optimal subarray number. An algorithm is proposed to find the optimal settings. Through numerical results, the proposed scheme outperforms other benchmark schemes in terms of energy efficiency. Also, it is shown that the optimal configuration of the number of subarrays is essential for energy efficiency maximization in the considered system.

关键词： Terahertz communication systems array-of-subarrays finite-bit DAC finite-bit ADC energy efficiency

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Near or far: On determining the appropriate channel estimation strategy in cross-field communication 13

Near or far: On determining the appropriate channel estimati...

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13rd IEEE Sensor array and Multichannel Signal Processing Workshop (SAM)

作者： Tarboush, Simon Ali, Anum Al-Naffouri, Tareq Y. Samsung Res Amer Stand & Mobil Innovat Lab Plano TX USA King Abdullah Univ Sci & Technol Dept CEMSE Informat Sci Lab Thuwal Saudi Arabia

ISBN: (纸本)9798350344820;9798350344813

The use of ultra-massive multiple-input multiple-output and high-frequency large bandwidth systems is likely in the next-generation wireless communication systems. In such systems, the user moves between near- and far-field regions, and consequently, the channel estimation will need to be carried out in the cross-field scenario. Channel estimation strategies have been proposed for both near- and far-fields, but in the cross-field problem, the first step is to determine whether the near- or far-field is applicable so that an appropriate channel estimation strategy can be employed. In this work, we propose using a hidden Markov model over an ensemble of region estimates to enhance the accuracy of selecting the actual region. The region indicators are calculated using the pair-wise power differences between received signals across the subarrays within an array-of-subarrays architecture. Numerical results show that the proposed method achieves a high success rate in determining the appropriate channel estimation strategy.

关键词： array-of-subarrays spherical wave model hybrid spherical-planar wave model planar wave model

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