distributed multiple-input multiple-output (D-MIMO) systems have drawn considerable attention as they can combine the advantages of point-to-point MIMO with distributed antenna system (DAS). However, the performance a...
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distributed multiple-input multiple-output (D-MIMO) systems have drawn considerable attention as they can combine the advantages of point-to-point MIMO with distributed antenna system (DAS). However, the performance analysis of D-MIMO system with zero-forcing (ZF) receivers over semi-correlated K fading channels involves special functions, such as Bessel and Meijer-G functions, which do not enable us to further analysis. In this paper, by using moment matching method, we present a new method that use a Gamma distribution to approximate the K distribution (Rayleigh/Gamma distribution). Using the approximate distribution as a starting point, we derive the approximate analytical expressions on the achievable sum rate (ASR), symbol error ratio (SER), and outage probability (OP) of D-MIMO systems operating in semi-correlated K fading channels employing ZF receivers. To get useful insight into implications of system and fading parameters on the performance, the analytical asymptotic approximations on the ASR in high signal-to-noise ratio (SNR) and low-SNR regime are provided, respectively. Finally, we perform the approximate large-system analysis in the high-SNR and provide asymptotic sum rate expressions when the number of antennas at the base station (BS) grows large, and when the number of antennas at both ends grows large with a fixed and finite ratio. It is demonstrated that the proposed approximate expressions accurately match with the analytical expressions, especially for large-system limit.
We propose a wideband model-embedding delta-sigma radio-over-fiber (DS-RoF) design for keeping the adjacent channel leakage low. This RoF design is derived on the basis of the DS-RoF embedding a pulse-distortion model...
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We propose a wideband model-embedding delta-sigma radio-over-fiber (DS-RoF) design for keeping the adjacent channel leakage low. This RoF design is derived on the basis of the DS-RoF embedding a pulse-distortion model (PDM). To enable wideband modulation with low adjacent channel leakage, we also propose an optimization method using an objective function simulating the adjacent channel leakage. By refining the digital down-converter from previous work, we additionally propose an extended PDM that generalizes its parameters from real numbers to complex numbers, which allow for fine-tuned delay adjustments in the PDM. A RoF demonstration using commercially available small form-factor pluggable (SFP) modules and a 10-km single mode fiber (SMF) with a 400-MHz-bandwidth orthogonal frequency division multiplexing (OFDM) signal, including a calibration path for modeling pulse distortion, revealed that the proposed design with our extended complex-valued PDM improved the signal-to-noise ratio (SNR) by 0.8 dB, normalized mean-squared error (NMSE) by 0.3 dB and adjacent channel leakage ratio (ACLR) by 0.4 dB compared with a RoF design with the original real-valued PDM. These results indicate that the complex-valued PDM, which enables fine-tuned delay adjustments, increases modeling accuracy, leading to enhanced compensation performance. Moreover, the proposed DS-RoF design with our complex-valued PDM also achieved an ACLR below -31 dBc. This result indicates that, to the best of our knowledge, we are the first to realize a 400-MHz-bandwidth modulation required for 5G millimeter wave as a DS-RoF system.
In this paper, a novel bistatic range grouping algorithm is proposed in order to localize multiple targets in distributedmultiple -inputmultiple -output (MIMO) radar systems. In a distributed MIMO radar, target loca...
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In this paper, a novel bistatic range grouping algorithm is proposed in order to localize multiple targets in distributedmultiple -inputmultiple -output (MIMO) radar systems. In a distributed MIMO radar, target localization is performed based on bistatic ranges, the distances between antennas through a target, without directional information, and grouping bistatic ranges with respect to the target is a crucial step to estimate multiple targets efficiently. In contrast to the existing grouping schemes that use tentative target estimation or complicated joint bistatic range grouping and target estimation, the proposed algorithm uses only the geometric property of bistatic ranges, resulting in computationally efficient and robust grouping algorithm without noise enhancement, especially for realistic noisy environments where other existing grouping algorithms often fail. The performance of the proposed scheme is confirmed by evaluating the probability of miss detection and the probability of false alarm through numerical simulations for various environments including indirect paths and blocked paths. The root mean square error performance of the multi -target localization using the proposed bistatic grouping algorithm is also presented for realistic noisy environments.
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