Tan N. Nguyen

Performance of time switching based energy harvesting for amplify-and-forward half-duplex relaying with hardware impairment

In this paper, we derive the formulas for outage probability and system throughput of an amplify-and-forward half-duplex relay network, in which the relay node is equipped with time switching based energy harvesting capability. It can be learnt from the analysis that the throughput performance of the system of interest is maximized only at an appropriate choice of the time-switching factor. This optimal value can be found by numerical algorithm. The analysis also clarifies the effect of other parameters such as transmitted-power-to-noise ratio and the data rate, to the system performance. All these above results are confirmed by Monte-Carlo simulation.

On the Performance of Decode-and-Forward Half-Duplex Relaying with Time Switching Based Energy Harvesting in the Condition of Hardware Impairment

In this paper, the outage performance and system throughput of a decode-and-forward half-duplex relay network, in which the relay node is equipped with time switching based energy harvesting capability, are derived rigorously. The analytical results provide theoretical insights into the effect of various system parameters, such as time switching factor, source transmission rate, transmitting-power-to-noise ratio to system performance. Our analysis is confirmed by Monte-Carlo simulation, and can serve as a guideline to design practical energy-harvested relaying systems.

Performance Enhancement for Energy Harvesting Based Two-Way Relay Protocols in Wireless Ad-hoc Networks with Partial and Full Relay Selection Methods

Abstract In this paper, we propose two relay selection methods to enhance system outage performance for energy harvesting (EH) based two-way relaying protocols in wireless adhoc networks. In the proposed protocol, two source nodes communicate with each other via the assistance of multiple decode-and-forward (DF) relays using three-phase digital network coding. At the first and second phases, two sources broadcast their data to the relays. Employing a power-splitting model, the relays would harvest energy from radio frequency (RF) signals of the sources to transmit the data at the third phase. We propose a simple partial relay selection (PRS) method and an opportunistic relay selection (ORS) method to enhance the reliability of data transmission at the cooperative phase. For performance evaluation, we derive exact and asymptotic expressions of the system outage probability (SOP) for the proposed protocols over block Rayleigh fading channels. Finally, Monte Carlo simulations are presented to verify the theoretical derivations as well as to compare the performance of the proposed protocols with that of the random relay selection protocol.

Adaptive Energy Harvesting Relaying Protocol for Two-Way Half-Duplex System Network over Rician Fading Channels

We investigate the system performance of a two-way amplify-and-forward (AF) energy harvesting relay network over the Rician fading environment. For details, the delay-limited (DL) and delay-tolerant (DT) transmission modes are proposed and investigated when both energy and information are transferred between the source node and the destination node via a relay node. In the first stage, the analytical expressions of the achievable throughput, ergodic capacity, the outage probability, and symbol error ratio (SER) were proposed, analyzed, and demonstrated. After that, the closed-form expressions for the system performance are studied in connection with all system parameters. Moreover, the analytical results are also demonstrated by Monte Carlo simulation in comparison with the closed-form expressions. Finally, the research results show that the analytical and the simulation results agree well with each other in all system parameters.

Energy harvesting over Rician fading channel: A performance analysis for half-duplex bidirectional sensor networks under hardware impairments

In this paper, a rigorous analysis of the performance of time-switching energy harvesting strategy that is applied for a half-duplex bidirectional wireless sensor network with intermediate relay over a Rician fading channel is presented to provide the exact-form expressions of the outage probability, achievable throughput and the symbol-error-rate (SER) of the system under the hardware impairment condition. Using the proposed probabilistic models for wireless channels between mobile nodes as well as for the hardware noises, we derive the outage probability of the system, and then the throughput and SER can be obtained as a result. Both exact analysis and asymptotic analysis at high signal-power-to-noise-ratio regime are provided. Monte Carlo simulation is also conducted to verify the analysis. This work confirms the effectiveness of energy harvesting applied in wireless sensor networks over a Rician fading channel, and can provide an insightful understanding about the effect of various parameters on the system performance.

Performance Analysis of General Hybrid TSR-PSR Energy Harvesting Protocol for Amplify-and-Forward Half-Duplex Relaying Networks

In this paper, we propose a hybrid protocol for energy harvesting in wireless relay networks, which combines the benefits of both time-switching relaying (TSR) and power-splitting relaying (PSR), which are two main protocols for energy harvesting. In TSR, a dedicated harvesting time in each time slot is allocated for energy harvesting, while the remaining time is used for information transmission. In PSR, a portion of received power is split for energy harvesting. TSR can simplify the hardware compared to PSR, but reduce the throughput or achievable rate of the system. Specifically, we conduct a rigorous analysis to derive the closed-form formulas for performance factors of the system. We deliver the analysis results for various transmission modes: instantaneous transmission, delay-limited transmission, and delay-tolerant transmission, which are different from each other on the availability of statistical information about the channels between source and relay nodes. The results are also confirmed by Monte Carlo simulation. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Bi-layers Red-emitting Sr 2 Si 5 N 8 :Eu 2+ Phosphor and Yellow-emitting YAG:Ce Phosphor: A New Approach for Improving the Color Rendering Index of the Remote Phosphor Packaging WLEDs

Due to optimal advances such as chromatic performance, durability, low power consumption, high efficiency, long-lifetime, and excellent environmental friendliness, white LEDs (WLEDs) are widely used in vehicle front lighting, backlighting, decorative lighting, street lighting, and even general lighting. In this paper, the remote packaging WLEDs (RP-WLEDs) with bi-layer red-emitting Sr2Si5N8: Eu2+ and yellow-emitting YAG:Ce phosphor was proposed and investigated. The simulation results based on the MATLAB software and the commercial software Light Tools indicated that the color rendering index (CRI) of bi-layer phosphor RP-WLEDs had a significant increase. The CRI had a considerable increase from 72 to 94. In conclusion, the results showed that bi-layer red-emitting Sr2Si5N8:Eu2+ and yellow-emitting YAG:Ce phosphor could be a prospective approach for manufacturing RP-WLEDs with enhanced optical properties.

A Novel Compressed Sensing Approach to Speech Signal Compression

Compressed sensing (CS) is a technique to sample compressible signals below the Nyquist rate, whilst still allowing near optimal reconstruction of the signal. In this paper, we apply the iterative hard thresholding (IHT) algorithm for compressed sensing on the speech signal. The interested speech signal is transformed to the frequency domain using Discrete Fourier Transform (DCT) and then compressed sensing is applied to that signal. The compressed signal can be reconstructed using the recently introduced Iterative Hard Thresholding (IHT) algorithm and also by the tradditional \( \ell_{1} \) minimization (basic pursuit) for comparison. It is shown that the compressed sensing can provide better root mean square error (RMSE) than the tradition DCT compression method, given the same compression ratio.

On the Performance of Energy Harvesting for Decode-and-Forward Full-Duplex Relay Networks in Imperfect CSI Condition

In this paper, we analyze the outage and throughput performance of a decode-and-forward (DF) full-duplex relay network (FDRN), in which the single relay node harvests energy from the source node by using time-switching relaying (TSR) protocol and uses this energy to forward the decoded message to the destination. The imperfect channel state information (CSI) is assumed throughout the analysis. We derive the outage probability expressions, and from which the optimal time switching factor are obtained via the numerical search method. This study provides an insightful look at the effect of various system parameters, including the time switching factor and the channel estimation error, on the performance of this network. The analysis is verified by simulation results, which confirm that the proposed scheme still can provide acceptable outage performance in imperfect CSI condition.