THz drone system with non-ideal hardware, beam misalignment error and mutual coupling.
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| Title: | THz drone system with non-ideal hardware, beam misalignment error and mutual coupling. |
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| Authors: | Azam, MD Afaque1 (AUTHOR) |
| Source: | Physical Communication. Oct2025, Vol. 72, pN.PAG-N.PAG. 1p. |
| Subject Terms: | Channel estimation, Bit error rate, Mean square algorithms, Signal-to-noise ratio, Electromagnetic coupling |
| Abstract: | In this work, a time division duplex (TDD) based THz drone system acting as a base station (BS) equipped with a uniform linear array (ULA) is considered. The transceiver used at the BS and the UE is assumed to have hardware impairments. The effect of these impairments is summarized as an additive signal distortion term in the signal model. Due to the continuous rotational motion of drone rotors and the narrow THz beam, the presence of beam misalignment (BM) error is assumed. Two distinct BM error models are used to analyze the system behavior. Close packing of antenna elements at the BS array for the THz carrier leads to the mutual coupling (MC) effect. In this work, the effect of MC on system performance is also considered. Linear minimum mean square error (LMMSE) based uplink channel estimation is performed. A closed-form expression for the mean square error (MSE) of the channel estimate is presented and verified. A novel and approximate closed-form expression for uplink (UL) and downlink (DL) signal-to-distortion and noise ratio (SDNR) is presented and verified numerically. It is observed that the system performance saturates at high transmission power. The received SDNR decreases on using higher operating frequencies and hardware distortion. From the numerical simulations, it is observed that in the presence of hardware impairments, increasing the transmission power beyond a certain threshold does not improve the signal quality. A similar observation is obtained for the DL SDNR in the presence of the MC effect. Some results on bit error rate (BER) are also presented. It is observed that the impact of hardware distortion is to set a lower floor on the achievable BER. An increase in BM error further increases the BER and reduces the system performance. • A THz drone wireless system is studied, considering hardware distortions modeled as an additional additive term in the uplink (UL) and downlink (DL) signal models. • BM errors caused by continuous drone vibrations are analyzed. Several stochastic models are introduced, and their impact on the signal-to-distortion-plus-noise ratio (SDNR) is studied. • An UL channel estimation scheme using LMMSE is proposed. Closed-form expressions for the mean-squared error (MSE) under BM error conditions are derived. • The effects of radio-frequency MC (RF MC) on the antenna elements in the THz array are considered. The combined impact of all the factors on the system performance is analyzed. • Approximate closed-form expressions for UL and DL SDNR are developed under the influence of these factors and their accuracy is verified through numerical simulations. [ABSTRACT FROM AUTHOR] |
| Database: | Supplemental Index |
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