scholarly journals Analisis Unjuk Kerja Improved Sinc Power Pulse pada Sistem OFDM Melalui Kanal Frequency Selective Fading

2019 ◽  
Vol 18 (3) ◽  
pp. 323
Author(s):  
Kadek Agus Mahabojana Dwi Prayoga ◽  
NMAE Dewi Wirastuti ◽  
Nyoman Pramaita
Keyword(s):  
Orthogonal Frequency Division Multiplexing ◽  
Pulse Shaping ◽  
Density Ratio ◽  
Pulse Frequency ◽  
Noise Power ◽  
Selective Fading ◽  
Frequency Selective Fading ◽  
Power Pulse ◽  
Noise Power Spectral Density ◽  
Frequency Selective

Kombinasi antara sistem OFDM (orthogonal frequency division multiplexing) dan Pulse Shaping mampu mengurangi Inter Carrier Interference (ICI) dan error yang terjadi. Penelitian ini bertujuan untuk mengetahui perbandingan performansi dari sistem OFDM tanpa pulse shaping dan OFDM dengan pulse shaping Improved Sinc Power (ISP) pulse yang melalui kanal Frequency Selective Fading, ditinjau dari BER (bit error rate) berbanding Eb/No (energy per bit to noise power spectral density ratio). Penelitian ini menggunakan metode simulasi dengan menggunakan program Matlab R2018a. Hasil dari simulasi didapat unjuk kerja sistem OFDM dengan pulse shaping ISP pulsememiliki hasil yang lebih baik dari OFDM tanpa pulse shaping. Pada kanal transmisi Frequency Selective Fading untuk mencapi nilai BER sebesar 10-1 sistem OFDM dengan pulse shaping ISP pulse dibutuhkan Eb/No sebesar 2 dB. Sedangkan pada sistem OFDM tanpa pulse shaping dibutuhkan Eb/No sebesar 10 dB. Kata Kunci — OFDM, Pulse Shaping, ICI, ISP pulse, Frequency Selective Fading.

Acoustic-based Upper Facial Action Recognition for Smart Eyewear

2021 ◽  
Vol 5 (2) ◽  
pp. 1-28
Author(s):  
Wentao Xie ◽  
Qian Zhang ◽  
Jin Zhang
Keyword(s):  
Frequency Domain ◽  
Orthogonal Frequency Division Multiplexing ◽  
Interaction Mechanism ◽  
Phase Changes ◽  
Experimental Result ◽  
Selective Fading ◽  
Time Frequency ◽  
Facial Action ◽  
Frequency Selective Fading ◽  
Frequency Selective

Smart eyewear (e.g., AR glasses) is considered to be the next big breakthrough for wearable devices. The interaction of state-of-the-art smart eyewear mostly relies on the touchpad which is obtrusive and not user-friendly. In this work, we propose a novel acoustic-based upper facial action (UFA) recognition system that serves as a hands-free interaction mechanism for smart eyewear. The proposed system is a glass-mounted acoustic sensing system with several pairs of commercial speakers and microphones to sense UFAs. There are two main challenges in designing the system. The first challenge is that the system is in a severe multipath environment and the received signal could have large attenuation due to the frequency-selective fading which will degrade the system's performance. To overcome this challenge, we design an Orthogonal Frequency Division Multiplexing (OFDM)-based channel state information (CSI) estimation scheme that is able to measure the phase changes caused by a facial action while mitigating the frequency-selective fading. The second challenge is that because the skin deformation caused by a facial action is tiny, the received signal has very small variations. Thus, it is hard to derive useful information directly from the received signal. To resolve this challenge, we apply a time-frequency analysis to derive the time-frequency domain signal from the CSI. We show that the derived time-frequency domain signal contains distinct patterns for different UFAs. Furthermore, we design a Convolutional Neural Network (CNN) to extract high-level features from the time-frequency patterns and classify the features into six UFAs, namely, cheek-raiser, brow-raiser, brow-lower, wink, blink and neutral. We evaluate the performance of our system through experiments on data collected from 26 subjects. The experimental result shows that our system can recognize the six UFAs with an average F1-score of 0.92.

scholarly journals Analisis Unjuk Kerja Convolutional Code pada Sistem MIMO MC-DSSS Melalui Kanal Rayleigh Fading

2017 ◽  
Vol 16 (2) ◽  
pp. 66 ◽  
Author(s):  
Kadek Agus Mahabojana Dwi Prayoga ◽  
Ni Made Ary Esta Dewi Wirastuti ◽  
I Gst A. Komang Diafari Djuni Hartawan
Keyword(s):  
Spread Spectrum ◽  
Orthogonal Frequency Division Multiplexing ◽  
Rayleigh Fading ◽  
Convolutional Code ◽  
Multiple Input Multiple Output ◽  
Density Ratio ◽  
Direct Sequence Spread Spectrum ◽  
Noise Power ◽  
Noise Power Spectral Density ◽  
Input Multiple Output

Kombinasi antara sistem MIMO (multiple input multiple output), OFDM (orthogonal frequency division multiplexing), dan spread spectrum serta adanya teknik pengkodean kanal mampu mengurangi efek fading dan error yang terjadi. Penelitian ini bertujuan untuk mengetahui perbandingan performansi dari sistem MIMO MC-DSSS (multi carrier-direct sequence spread spectrum) Uncoded atau tanpa pengkodean kanal dan MIMO MC-DSSS Convolutional Code atau dengan pengkodean kanal Convolutional yang melalui kanal Rayleigh Fading, ditinjau dari nilai dan grafik BER (bit error rate) berbanding Eb/No (energy per bit to noise power spectral density ratio). Penelitian ini menggunakan metode simulasi dengan menggunakan program Matlab R2015a. Hasil dari simulasi didapat unjuk kerja sistem MIMO MC-DSSS dengan Convolutional Code memiliki hasil yang lebih baik dari MIMO MC-DSSS. Pada kanal transmisi Rayleigh Fading untuk mencapi nilai BER sebesar 10-3 pada sistem MIMO MC-DSSS dengan Convolutional Code dibutuhkan Eb/No sebesar -7 dB. Sedangkan pada sistem MIMO MC-DSSS dibutuhkan Eb/No sebesar -3 dB.[turnitin 20%, 7-11-2016]

scholarly journals Single-RF Diversity Receiver for OFDM System Using ESPAR Antenna with Alternate Direction

1970 ◽  
Vol 6 (1) ◽  
pp. 89-93 ◽  
Author(s):  
Satoshi Tsukamoto ◽  
Minoru Okada
Keyword(s):  
Communication Systems ◽  
Orthogonal Frequency Division Multiplexing ◽  
Multipath Propagation ◽  
Maximal Ratio Combining ◽  
Diversity Gain ◽  
Efficient Technique ◽  
Selective Fading ◽  
Frequency Selective Fading ◽  
Frequency Selective ◽  
Diversity Scheme

This paper presents a single-RF diversity scheme for orthogonal frequency division multiplexing (OFDM) receiver using Electronically Steerable Passive Array Radiator (ESPAR) antenna whose direction changes alternately at the OFDM symbol rate. OFDM is widely used for mobile communication systems because of its broadband wireless transmission capability in a severe time dispersive multipath propagation channel. OFDM is, however, not efficient for mitigating the performance degradation due to fading. Diversity is an efficient technique for solving this problem. Although maximal ratio combining diversity is the most efficient technique, it requires the same number of RF front-end circuitry and analog-todigital converters (ADC) as antennas. Although ESPAR antenna-based diversity technique requires only a single-RF and ADC, the convergence is not fast enough to track fast variation of the channel state. Furthermore, it is not efficient in a frequency selective channel. In this paper, we propose a new OFDM diversity scheme using ESPAR antenna. The proposed scheme is capable of obtaining the diversity gain in a frequency selective fading environment and avoids the slow convergence rate problem in the conventional technique using ESPAR antenna. Computer simulation results show that the proposed scheme gives diversity gain in a frequency selective fading channel.

scholarly journals Performance analysis of OFDM-IM scheme under STO and CFO

2021 ◽  
Vol 11 (4) ◽  
pp. 3293
Author(s):  
Suyoto Suyoto ◽  
Agus Subekti ◽  
Arief Suryadi Satyawan ◽  
Vita Awalia Mardiana ◽  
Nasrullah Armi ◽  
...  
Keyword(s):  
Performance Analysis ◽  
Fading Channel ◽  
Orthogonal Frequency Division Multiplexing ◽  
Carrier Frequency Offset ◽  
Selective Fading ◽  
Multicarrier Communication ◽  
Frequency Selective Fading ◽  
Multicarrier System ◽  
Frequency Selective ◽  
Time Offset

In this letter, performance analysis of orthogonal frequency division multiplexing with index modulation (OFDM-IM) is presented in term of bit error rate (BERs). The analysis considers its performance under two impairments, symbol time offset (STO) and carrier frequency offset (CFO) in frequency-selective fading channel. As orthogonal multicarrier system, OFDM-IM is subject to both inter-symbol interference (ISI) and inter-carrier interference (ICI) in a frequency-selective fading channel. OFDM-IM is a new multicarrier communication system, where the active subcarriers indices are used to carry additional bits of information. In general, in the previous existing works, OFDM-IM are evaluated only for near-ideal communication scenarios by only incorporating the CFO factor. In this work, the OFDM-IM performance is investigated and compared with conventional OFDM in the presence of two impairments, STO and CFO. Simulation results show that OFDM-IM outperforms the conventional OFDM with the presence of STO and CFO, especially at high SNR areas.

scholarly journals Evaluaciónde OPS para la Reducción de la PAPR en un SistemaOFDM conCanal Multitrayecto

2020 ◽  
Vol 44 (2) ◽  
pp. 35-42
Author(s):  
María Peñaherrera ◽  
Diego Reinoso
Keyword(s):  
Bit Error Rate ◽  
Orthogonal Frequency Division Multiplexing ◽  
Density Ratio ◽  
Average Power ◽  
Noise Power ◽  
Power Ratio ◽  
Frequency Division ◽  
Complementary Distribution ◽  
Noise Power Spectral Density ◽  
Power Spectral

OFDM (Orthogonal Frequency Division Multiplexing) es una tecnología de comunicacióninalámbrica que tiene ventajas como alta eficiencia espectral, alta tasa de transmisión y es robusta a la propagación por mulitrayecto. Sin embargo, su principal desventaja es que tienealta PAPR (Peak-to-Average Power Ratio).Este artículo presenta la evaluaciónde la técnica OPS (Orthogonal Pilot Sequence) para la reducción de la PAPR en un sistema OFDM con canal multitrayecto. Para la evaluación se consideran dos tipos de canalesmultitrayecto selectivos en frecuencia, con y sin línea de vista. Se evalúa la técnica OPS obteniendola gráfica del BER (Bit Error Rate)vs Eb/No (energy per bit to noise power spectral density ratio) y la gráfica de la CCDF (Cumulative Complementary Distribution Function) para distintos parámetros. Losresultados muestran una reducción de la PAPR cuando se utiliza la técnica OPS y una mejora en el BER.

scholarly journals New OSTBC for Blind Channel Estimation and Tracking in MIMO-OFDM Systems

2019 ◽  
Vol 3 ◽  
pp. 49-57
Author(s):  
Abdelkader Tami ◽  
Mokhtar Keche ◽  
Boubaker S. Bouazza
Keyword(s):  
Channel Estimation ◽  
Orthogonal Frequency Division Multiplexing ◽  
Mimo Systems ◽  
Blind Channel Estimation ◽  
Mimo Channel ◽  
Selective Fading ◽  
Frequency Selective Fading ◽  
Blind Channel ◽  
Flat Fading ◽  
Frequency Selective

Applying orthogonal space time block coding (OSTBC) to multiple-input multiple-output (MIMO) systems helps reduce receiver complexity. However, this approach has been applied only to flat fading channels, as when the channel is a frequency selective fading MIMO channel, OSTBC cannot be used directly since its orthogonal propriety may be lost. Furthermore, the MIMO channel is not always known. To deal with this problem, many techniques were proposed to estimate the channel using a training sequence. Unfortunately, these techniques reduce the useful spectral bandwidth. This paper proposes OSTBC for blind channel estimation and data detection in the case of a MIMO frequency selective channel. The aim of this new OSTBC is twofold: to solve the ambiguity of channel estimation and to reduce the complexity of the detector. By exploiting the well-known technique of orthogonal frequency division multiplexing (OFDM), the frequency selective fading MIMO channel is split into a set of flat fading subchannels. Moreover, to accommodate the fact that a MIMO channel can be time varying, the steady state Kalman channel estimator (SS-KCE) is extended to track the channel’s fast variations. The performance of the proposed blind algorithm is related by the adequate choice of the number of subcarriers and it is compared with other existing approaches by means of Monte Carlo simulations.

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