For a complete stability analysis of multi-dimensional controlled systems modeled in the framework of second-order linear differential equations with two time-delays, the determination of stability crossing curves (or...
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For a complete stability analysis of multi-dimensional controlled systems modeled in the framework of second-order linear differential equations with two time-delays, the determination of stability crossing curves (or stability switching curves) within the domain of the delays is significantly important. This paper presents a simple receptance-based approach to solve this problem for a single-input-multiple-output controlled system using its second-order model. The proposed approach is based on a reduced characteristic function of the controlled system. This characteristic function is directly related to the receptance of the uncontrolled system and has a peculiar form that is well-suited for an effective method of calculation of these curves. Moreover, this method can find the direction in which the characteristic roots cross the imaginary axis as the delays deviate from a stability crossing curve. An example case study with two independent and constant delays is given to demonstrate the effectiveness of the proposed approach.
Molecular Communication via Diffusion (MCvD) is a prominent small-scale technology, which roots from the nature. With solid analytical foundations on channel response and advanced modulation techniques, molecular sing...
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Molecular Communication via Diffusion (MCvD) is a prominent small-scale technology, which roots from the nature. With solid analytical foundations on channel response and advanced modulation techniques, molecular single-input-single-output (SISO) systems are one of the most studied molecular networks in the literature. However, the literature is yet to provide sufficient analytical channel modeling on molecular multiple-output systems with fully absorbing receivers, one of the common applications in the area. In this paper, a channel model for molecular single-input-multiple-output (SIMO) systems is proposed for estimating the channel response of such systems. With the model's recursive nature, the closed-form solution of the channel response of molecular 2-Rx SIMO systems is analytically derived. A simplified model with lower complexity is also presented at a cost of slightly less accurate channel estimation. The models are extended to the molecular SIMO systems with more than two receivers. The performance of the methods are evaluated for several topologies with different parameters, and the accuracy of the model is verified by comparing to computer-simulated channel estimations in terms of quantitative error metrics such as root-mean-squared error. The performance of the simplified model is verified by the amount of deviation, indicating sufficient channel modeling performance with reduced computational power.
Deep learning based channel estimation techniques have recently found an overwhelming interest owing to data-driven learning-based adaptability compared to conventional estimation techniques which rely on model-based ...
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Deep learning based channel estimation techniques have recently found an overwhelming interest owing to data-driven learning-based adaptability compared to conventional estimation techniques which rely on model-based approach. This paper exploits the availability of low cost software defined radio (SDR) devices to implement and test over-the-air (OTA) deep learning driven channel estimation solutions in realistic settings for 5G and beyond wireless communications. We have designed and implemented a ZYNQ SDR-based deep learning driven channel estimation platform which utilises real-world 5G new radio (NR) signals to develop and test the performance of a deep learning solution for wireless channel estimators. To this end, we have considered the time-frequency response of an OTA communication channel for single-input-single-output (SISO) and single-input-multiple-output (SIMO) networks under various line-of-sight and non-line-of-sight scenarios as a two-dimensional image. We have utilised convolutional deep learning technique for channel estimation. The main purpose is to use OTA samples obtained via the SDR platform to determine the unknown values of the channel response using known values at the pilot locations and evaluate performance compared to conventional technique. Our results show that the performance of the deep learning channel estimator using OTA data is as good as that of conventional methods with the flexibility to adapt based on data analytics of the time-varying nature of the channel.
This paper investigates the physical-layer security (PLS) of a single-input-multiple-output (SIMO) underlay cognitive radio network (CRN) over cascaded kappa-mu fading channels. A secondary user (SU) transmitter commu...
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This paper investigates the physical-layer security (PLS) of a single-input-multiple-output (SIMO) underlay cognitive radio network (CRN) over cascaded kappa-mu fading channels. A secondary user (SU) transmitter communicates with a secondary user receiver over cascaded kappa-mu channels. Moreover, an eavesdropper residing in the SUs transmission's range would be capable of intercepting the SUs' transmission. The SU destination and the eavesdropper are both assumed to be equipped with multiple antennas. Both of the receivers adopt maximalratio combining (MRC) over the multiple copies of the signal. In an underlay CRN, the SU transmitter should keep adjusting the transmission power to ensure not to disturb the primary users' (PUs) transmission. PLS is analyzed in terms of the secrecy outage probability (SOP) and the probability of non-zero secrecy capacity (P-nz). Results indicate the evident effect of the cascade level and the number of antennas at the eavesdropper over the secrecy of the SUs pair. In addition, results reveal that PLS can be strengthened by increasing the number of antennas at the legitimate receiver. The impact of the interference level tolerable by the PU receiver over SUs' secrecy is also analyzed. Monte-Carlo simulations and analytical results are presented to assess the system performance.
Rich scattering of the signals in the ultraviolet (UV) band of electromagnetic spectrum enables non-line-of-sight (NLOS) outdoor wireless connectivity. It eliminates the line-of-sight requirement of the links which ar...
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Rich scattering of the signals in the ultraviolet (UV) band of electromagnetic spectrum enables non-line-of-sight (NLOS) outdoor wireless connectivity. It eliminates the line-of-sight requirement of the links which are using the signals in the infra-red band. Besides scattering losses, UV signals also suffer from atmospheric turbulence-induced fading. The turbulent atmospheric channel causes fluctuations in the received signal intensity of a NLOS ultraviolet (NLOS-UV) link, resulting in power loss and the performance degradation at the receiver. In this study, spatial diversity techniques are investigated as an appealing fading mitigation technique for NLOS-UV systems over atmospheric turbulence channels. In particular, the outage probabilities of multiple-input-single-output (MISO), single-input-multiple-output (SIMO), and multiple-input-multiple-output (MIMO) links are studied, and the outage performances are investigated for different system configurations. Closed-form expressions are derived for the outage probability of MISO, SIMO, and MIMO systems, and the accuracy of the derivations is confirmed through Monte Carlo simulations. The outage probability of single-input-single-output link is also derived as a benchmark. The results demonstrate significant performance improvements through deployment and proper configuration of MIMO systems in NLOS-UV communication links.
This paper presents a novel integrated dc/dc topology with a step-up output and a step-down output. A new control scheme is developed to regulate both outputs simultaneously. Compared with discrete configurations, the...
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ISBN:
(纸本)9781509007370
This paper presents a novel integrated dc/dc topology with a step-up output and a step-down output. A new control scheme is developed to regulate both outputs simultaneously. Compared with discrete configurations, the proposed integrated converter utilizes a lower number of switches due to the reuse of components. The converter characteristics are studied comprehensively. It is demonstrated that all MOSFETs are turned on at zero voltage with reduced switching losses. For the step-up stage, the converter provides a high boost ratio and is able to clamp the switch voltage spikes. For the step-down stage, the steady-state characteristics and the dynamic performances are similar to that of the conventional buck converter. Moreover, the step-down output port can be extended to multiple ports, where the single-input-multiple-output (SIMO) version of converter can be derived. A 250 W, 42 V to 390 V and 15 V converter prototype is designed, analyzed and tested. The experimental results are presented to verify the feasibility of the topology.
This paper presents a novel integrated dc/dc topology with a step-up output and a step-down output. A new control scheme is developed to regulate both outputs simultaneously. Compared with discrete configurations, the...
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ISBN:
(纸本)9781509007387
This paper presents a novel integrated dc/dc topology with a step-up output and a step-down output. A new control scheme is developed to regulate both outputs simultaneously. Compared with discrete configurations, the proposed integrated converter utilizes a lower number of switches due to the reuse of components. The converter characteristics are studied comprehensively. It is demonstrated that all MOSFETs are turned on at zero voltage with reduced switching losses. For the step-up stage, the converter provides a high boost ratio and is able to clamp the switch voltage spikes. For the step-down stage, the steady-state characteristics and the dynamic performances are similar to that of the conventional buck converter. Moreover, the step-down output port can be extended to multiple ports, where the single-input-multiple-output (SIMO) version of converter can be derived. A 250 W, 42 V to 390 V and 15 V converter prototype is designed, analyzed and tested. The experimental results are presented to verify the feasibility of the topology.
We firstly applied diversity reception technology to a real-time none-light-of-sight (NLOS) ultraviolet (UV) communication system based on a 9.3mW LED array. Field experiment with 4 receivers (Rxs) achieves bit error ...
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ISBN:
(纸本)9781479987986
We firstly applied diversity reception technology to a real-time none-light-of-sight (NLOS) ultraviolet (UV) communication system based on a 9.3mW LED array. Field experiment with 4 receivers (Rxs) achieves bit error rate (BER) improvement, and related conclusions on single-input-multiple-output (SIMO) UV system design are given. Innovatively, the correlation characteristics in UV channel are studied according to measurements of two branches. Experiment result shows that once the transmission distance goes beyond 20m, the value of correlation coefficient remains to be less than 0.4, in which case the Rx branches can be considered to be fading independently, thus achieving diversity gain for the system.
A transponder system is developed to fulfill the in-orbit calibration of the HY-2 satellite altimeter (ALT) and scatterometer (SCAT). The interaction of a calibration transponder and radar (altimeter/scatterometer) is...
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ISBN:
(纸本)9781457710056
A transponder system is developed to fulfill the in-orbit calibration of the HY-2 satellite altimeter (ALT) and scatterometer (SCAT). The interaction of a calibration transponder and radar (altimeter/scatterometer) is rather complicated. After a brief description of the two active payloads on HY-2 satellite, several key issues are investigated in detail, including time arrangement and power budget. There are some innovations in calibration strategy, including the pre-distortion technology in ALT calibration and the single-input-multiple-output (SIMO) technology in the SCAT calibration.
Device-to-device (D2D) communications underlaying a cellular infrastructure has recently been proposed as a means of increasing the resource utilization, improving the user throughput and extending the battery lifetim...
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ISBN:
(纸本)9781424492688
Device-to-device (D2D) communications underlaying a cellular infrastructure has recently been proposed as a means of increasing the resource utilization, improving the user throughput and extending the battery lifetime of user equipments. In this paper we propose a new distributed power control algorithm that iteratively determines the signal-to-noise-and-interference-ratio (SINR) targets in a mixed cellular and D2D environment and allocates transmit powers such that the overall power consumption is minimized subject to a sum-rate constraint. The performance of the distributed power control algorithm is benchmarked with respect to the optimal SINR target setting that we obtain using the Augmented Lagrangian Penalty Function (ALPF) method. The proposed scheme shows consistently near optimum performance both in a single-input-multiple-output (SIMO) and a multiple-input-multiple-output (MIMO) setting.
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