scholarly journals Efficient Offline Waveform Design Using Quincunx/Hexagonal Time-Frequency Lattices

2017 ◽  
Vol 2017 ◽  
pp. 1-16 ◽  
Author(s):  
Raouia Ayadi ◽  
Inès Kammoun ◽  
Mohamed Siala
Keyword(s):  
Orthogonal Frequency Division Multiplexing ◽  
Pulse Shaping ◽  
Cellular Systems ◽  
Strong Increase ◽  
Intercarrier Interference ◽  
Time Frequency ◽  
Synchronization Errors ◽  
Filter Bank Multicarrier ◽  
Wireless Cellular Systems ◽  
Rectangular Lattices

Conventional orthogonal frequency division multiplexing (OFDM) may turn to be inappropriate for future wireless cellular systems services, because of extreme natural and artificial impairments they are expected to generate. Natural impairments result from higher Doppler and delay spreads, while artificial impairments result from multisource transmissions and synchronization relaxation for closed-loop signaling overhead reduction. These severe impairments induce a dramatic loss in orthogonality between subcarriers and OFDM symbols and lead to a strong increase in intercarrier interference (ICI) and intersymbol interference (ISI). To fight against these impairments, we propose here an optimization of the transmit/receive waveforms for filter-bank multicarrier (FBMC) systems, with hexagonal time-frequency (TF) lattices, operating over severe doubly dispersive channels. For this, we exploit the Ping-pong Optimized Pulse Shaping (POPS) paradigm, recently applied to rectangular TF lattices, to design waveforms maximizing the signal-to-interference-plus-noise ratio (SINR) for hexagonal TF lattices. We show that FBMC, with hexagonal lattices, offers a strong improvement in SINR with respect to conventional OFDM and an improvement of around 1 dB with respect to POPS-FBMC, with rectangular lattices. Furthermore, we show that hexagonal POPS-FBMC brings more robustness to frequency synchronization errors and offers a 10 dB reduction in out-of-band (OOB) emissions, with respect to rectangular POPS-FBMC.

scholarly journals FILTER BANK MULTICARRIER (FBMC) UNTUK 5G

2021 ◽  
Vol 13 (2) ◽  
pp. 135-142
Author(s):  
Gradiyanto Jason ◽  
Theresia Ghozali ◽  
Kumala Indriati
Keyword(s):  
Amplitude Modulation ◽  
Orthogonal Frequency Division Multiplexing ◽  
Dynamic Spectrum Access ◽  
Filter Bank ◽  
Quadrature Amplitude Modulation ◽  
Cyclic Prefix ◽  
Intercarrier Interference ◽  
Frequency Division ◽  
Spectrum Access ◽  
Filter Bank Multicarrier

Saat ini, teknologi pada bidang telekomunikasi berkembang dengan pesat. Pengguna telekomunikasi membutuhkan teknologi komunikasi yang cepat dengan bandwidth yang lebih lebar. Oleh karena itu dikembangkanlah Filter Bank Multi Carrier/Offset Quadrature Amplitude Modulation yang merupakan teknologi kandidat modulasi yang akan digunakan pada 5G. Filter Bank Multi Carrier/Offset Quadrature Amplitude Modulation (FMBC/OQAM) merupakan perkembangan dari Orthogonal Frequency Division Multiplexing (OFDM) yang dimodifikasi dengan menggunakan filter untuk mengurangi noise. OFDM menggunakan teknik multiplexing yang membagi bandwith menjadi beberapa frekuensi sub-carrier. Tetapi OFDM memiliki kelemahan yaitu memerlukan Cyclic Prefix (CP) untuk mengatasi Intersymbol Interference (ISI) serta Intercarrier Interference (ICI). Dengan menggunakan Filter berdasarkan Lembaga Physical layer for dynamic spectrum access and cognitive radio (PHYDYAS)  ,lebar bandwith yang bertambah akibat Cyclic prefix  akan dapat dikurangi Hasil yang dicapai dalam penelitian ini adalah  FBMC berhasil diterapkan  dan data yang dikirim sama dengan data yang diterima.

scholarly journals INTER CARRIER INTERFERENCE AND SIGNAL TO INTERFERENCE RATIO OF VARIOUS PULSE SHAPING FUNCTIONS USED IN OFDM SYSTEM WITH CARRIER FREQUENCY OFFSET

2012 ◽  
pp. 68-71
Author(s):  
SHANKAR AENAGANDULA ◽  
ASHOK KUMAR ◽  
SRINIVAS K ◽  
MONIKA NANDA
Keyword(s):  
Carrier Frequency ◽  
Orthogonal Frequency Division Multiplexing ◽  
Pulse Shaping ◽  
Carrier Frequency Offset ◽  
Signal To Noise Ratio ◽  
Frequency Offset ◽  
Performance Comparison ◽  
Intercarrier Interference ◽  
Ofdm Systems ◽  
Ofdm System

Orthogonal Frequency Division Multiplexing (OFDM) is the important modulation of choice for fourthgeneration broadband multimedia wireless systems. This paper is focused on the problem of reducing the intercarrierinterference (ICI) and signal to noise ratio in the transmission over OFDM using various pulse shaping methods. Here we have performed a detailed performance comparison of various pulse shaping functions used in OFDM System with Carrier Frequency Offset. They appear to be suitable for transmission in OFDM systems with carrier frequency offset. The results obtained by analysis show that the performance improvement over conventional pulse shapes, are significant for reducing average intercarrier-interference (ICI) power and increased ratio of average signal power to average ICI power (SIR).

scholarly journals Comparison of SPS and FA methods for Blind Carrier Frequency Offset Estimation in OFDM systems

2022 ◽  
Vol 16 ◽  
pp. 7-11
Author(s):  
K. Seshadri Sastry ◽  
K. Baburao ◽  
A.V. Prabu ◽  
G.Naveen Kumar
Keyword(s):  
Carrier Frequency ◽  
Orthogonal Frequency Division Multiplexing ◽  
Carrier Frequency Offset ◽  
Frequency Offset ◽  
Intercarrier Interference ◽  
Frequency Division ◽  
Ofdm Systems ◽  
Frequency Offset Estimation ◽  
Synchronization Errors ◽  
Carrier Frequency Offset Estimation

In orthogonal frequency-division multiplexing (OFDM) systems, synchronization issues are of great importance since synchronization errors might destroy the orthogonality among all subcarriers and, therefore, introduce intercarrier interference (ICI) and intersymbol interference (ISI). Several schemes of frequency offset estimation in OFDM systems have been investigated. This paper compares performance and computational complexity of Smoothing Power Spectrum (SPS) and Frequency Analysis (FA) methods for blind carrier frequency offset (CFO) estimation in OFDM systems.

scholarly journals Comparative Study of Pulse Shaping Filters in FBMC

2019 ◽  
pp. 30-40
Keyword(s):  
Comparative Study ◽  
Orthogonal Frequency Division Multiplexing ◽  
Pulse Shaping ◽  
Filter Bank ◽  
Hermite Function ◽  
Frequency Division ◽  
Ofdm Symbol ◽  
Dispersive Effect ◽  
Filter Bank Multicarrier ◽  
Transmitted Signal

Filter Bank Multicarrier (FBMC) is a multitone modulation technique that is expected to replace the Orthogonal Frequency Division Multiplexing (OFDM) due to its inherent characteristics that makes it immune to channel dispersive effect on the transmitted signal in both time and frequency. The most effective ingredient in the FBMC is the pulse shaping that the OFDM symbol lacks. In this paper, a comparative study is presented between different pulse shapes used in the FBMC like the RRC, PHYDIAS, IOTA and Hermite function alongside the conventional OFDM.

Improving Space-Time-Frequency MIMO-OFDM with ICI Self-Cancellation Scheme using Least Square Error Estimator

2015 ◽  
Vol 12 (1) ◽  
pp. 25
Author(s):  
Nur Farahiah Ibrahim ◽  
Zahari Abu Bakar ◽  
Azlina Idris
Keyword(s):  
Channel Estimation ◽  
Orthogonal Frequency Division Multiplexing ◽  
Symbol Error Rate ◽  
Space Time ◽  
Least Square ◽  
Error Estimator ◽  
Frequency Diversity ◽  
Time Frequency ◽  
Mimo Ofdm ◽  
Subcarrier Mapping

Channel estimation techniques for Multiple-input Multiple-output Orthogonal Frequency Division Multiplexing (MIMO-OFDM) based on comb type pilot arrangement with least-square error (LSE) estimator was investigated with space-time-frequency (STF) diversity implementation. The frequency offset in OFDM effected its performance. This was mitigated with the implementation of the presented inter-carrier interference self-cancellation (ICI-SC) techniques and different space-time subcarrier mapping. STF block coding in the system exploits the spatial, temporal and frequency diversity to improve performance. Estimated channel was fed into a decoder which combined the STF decoding together with the estimated channel coefficients using LSE estimator for equalization. The performance of the system was compared by measuring the symbol error rate with a PSK-16 and PSK-32. The results show that subcarrier mapping together with ICI-SC were able to increase the system performance. Introduction of channel estimation was also able to estimate the channel coefficient at only 5dB difference with a perfectly known channel.

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.

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