Alokasi Daya Kirim pada Visible Light Communication menggunakan Algoritma Waterfilling

ABSTRAKPeningkatan terhadap kebutuhan akses data membuat Visible Light Communication (VLC) menjadi alternatif media transmisi nirkabel yang efisien. Namun berdasarkan performansinya, VLC memiliki permasalahan data rate yang tidak merata diterima oleh User Equipment (UE). Dalam mengatasi permasalahan tersebut, penelitian ini menerapkan alokasi daya kirim dengan algoritma waterfilling yang mampu memberikan keadilan data rate setiap UE berdasarkan nilai kanal. Penelitian ini menggunakan kanal Line Of Sight (LOS) dengan 3 skenario berbeda. Kami menggunakan parameter validasi untuk mengukur setiap kinerja dengan nilai Signal Noise Ratio (SNR), data rate, fairness index dan efisiensi energi. Dari hasil simulasi menggunakan algoritma waterfilling, kami memperoleh nilai fairness index untuk data rate sebesar 100% namun tidak memiliki efisiensi daya. Dengan memodifikasi algorima waterfilling, terjadi penurunan fairness index, SNR serta data rate, tapi memberikan efisiensi energi LED hingga 9%. Dengan demikan, daya yang dipancarkan oleh LED memiliki lifetime yang lebih panjang dengan modified waterfilling.Kata kunci: VLC, Power Allocation, Waterfilling, Fairness. ABSTRACTThe increase in the need for data access makes Visible Light Communication (VLC) an alternative wireless transmission medium that is efficient. However, based on its performance, VLC has a data rate problem that is not evenly accepted by User Equipment (UE). In overcoming this problem, this study applies power allocation with waterfilling algorithm that is able to provide fair data rate for each UE based on channel value. This study uses the Line Of Sight (LOS) channel with 3 different scenarios. We use validation parameters to measure each performance using the Signal Noise Ratio (SNR) value, data rate, fairness index and energy efficiency. From the results of simulation using the waterfilling algorithm, we obtain a fairness index value for the data rate of 100% but does not have a power efficiency. By modifying the waterfilling algorithm, there is a decrease in the fairness index, SNR and data rate, but provide LED energy efficiency of up to 9%. Thus, the power emitted by the LED has a longer lifetime with modified waterfilling algorithm.Keywords: VLC, Power Allocation, Waterfilling, Fairness.

Asymptotic Reverse Waterfilling Algorithm of NRDF for Certain Classes of Vector Gauss-Markov Processes

<div>In this paper, we revisit the asymptotic reverse-waterfilling characterization of the nonanticipative rate distortion</div><div>function (NRDF) derived for a time-invariant multidimensional Gauss-Markov processes with mean-squared error (MSE) distortion in [1]. We show that for certain classes of time-invariant multidimensional Gauss-Markov processes, the specific characterization behaves as a reverse-waterfilling algorithm obtained in matrix form ensuring that the numerical approach of [1, Algorithm 1] is optimal. In addition, we give an equivalent characterization that utilizes the eigenvalues of the involved matrices reminiscent of the well-known reverse-waterfilling algorithm in information theory. For the latter, we also propose a novel numerical approach to solve the algorithm optimally. The efficacy of our proposed iterative scheme compared to similar existing schemes is demonstrated via experiments. Finally, we use our new results to derive an analytical solution of the asymptotic NRDF for a correlated time-invariant two-dimensional Gauss-Markov process.</div>

Asymptotic Reverse Waterfilling Algorithm of NRDF for Certain Classes of Vector Gauss-Markov Processes

<div>In this paper, we revisit the asymptotic reverse-waterfilling characterization of the nonanticipative rate distortion</div><div>function (NRDF) derived for a time-invariant multidimensional Gauss-Markov processes with mean-squared error (MSE) distortion in [1]. We show that for certain classes of time-invariant multidimensional Gauss-Markov processes, the specific characterization behaves as a reverse-waterfilling algorithm obtained in matrix form ensuring that the numerical approach of [1, Algorithm 1] is optimal. In addition, we give an equivalent characterization that utilizes the eigenvalues of the involved matrices reminiscent of the well-known reverse-waterfilling algorithm in information theory. For the latter, we also propose a novel numerical approach to solve the algorithm optimally. The efficacy of our proposed iterative scheme compared to similar existing schemes is demonstrated via experiments. Finally, we use our new results to derive an analytical solution of the asymptotic NRDF for a correlated time-invariant two-dimensional Gauss-Markov process.</div>

Performance evaluation of 2-port MIMO LTE-U terminal antenna with user’s hand effect

This paper presents the performance evaluation of 2-port MIMO antenna for LTE-U sub 6 GHz band. The evaluation focuses on the effect of user’s hand in a uniform environment and the analysis were carried out on simulation and measurement data of antenna ports. Results show that the highest performance of the design is on the frequency range from 4.5 GHz to 5.5 GHz, and the ports have low envelope correlation coefficient (ECC) less than 0.16 in both cases of without and with user’s hand. However, the presence of the user’s hand reduces mean effective gain (MEG) of ports and diversity combining gain by more than 1.6 dB compared with no-hand case. The multiplexing efficiency is around 81% and reduced by the presence of the user’s hand to 55%. Despite this reduction; the design shows high spatial multiplexing capability in both cases. The capacity carried by the second transmission eigenmode is about 39% from the total capacity under waterfilling algorithm transmit power allocation.