scholarly journals Turbo Decoder for Low-Power Ultrawideband Communication Systems

2008 ◽  
Vol 2008 ◽  
pp. 1-7 ◽  
Author(s):  
Esam A. Obiedat ◽  
Lei Cao
Keyword(s):  
Computational Complexity ◽  
Communication Systems ◽  
Orthogonal Frequency Division Multiplexing ◽  
Signal To Noise Ratio ◽  
Turbo Decoding ◽  
Ofdm Symbol ◽  
Turbo Decoder ◽  
Multicarrier Systems ◽  
Ultrawideband Communication ◽  
Ber Performance

A new method to reduce the computational complexity of the turbo decoding in ultrawideband (UWB) orthogonal frequency division multiplexing (OFDM) system is proposed. Existing stopping techniques for turbo decoding process using constrained decoding assume fixed signal-to-noise ratio (SNR) for all the OFDM symbol bits so they fail to yield an acceptable bit-error rate (BER) performance in multicarrier systems. In this paper, we propose a bit-level stopping technique for turbo decoding process based on the constrained decoding method. In this technique, we combine the cyclic redundancy check (CRC) with an adaptive threshold on the log likelihood ratio (LLR) on each subcarrier to detect for convergence. The threshold is adaptive in the sense that the threshold on the LLR of a bit is determined by the average SNR of the OFDM symbol and the channel gain of the transmission subcarrier. Results show that when the channel state information (CSI) is used to determine the threshold on LLR, the stopping technique can reduce the computational complexity by about 0.5–2.5 equivalent iterations compared to GENIE turbo without degradation in the BER performance.

scholarly journals BER performance study for optical OFDM of optical camera communication

2021 ◽  
Vol 11 (5) ◽  
pp. 4263
Author(s):  
Noor J. Jihad ◽  
Sinan M. Abdul Satar
Keyword(s):  
Orthogonal Frequency Division Multiplexing ◽  
Signal To Noise Ratio ◽  
Frequency Division ◽  
Performance Study ◽  
Mapping Rule ◽  
Bit Loading ◽  
Dc Bias ◽  
Optical Ofdm ◽  
Ber Performance ◽  
Optical Camera Communication

In this article, different forms of optical orthogonal frequency division multiplexing (OFDM) were observed which were suitable for optical camera communication (OCC) systems. This research aims to establish the bit error rate (BER) versus signal-to-noise ratio (SNR) of the OCC system. This research will focus on OCC systems and the design that produces the noise of the clipping but will gain SNR as a whole if an optimum clipping factor is chosen. The BER versus SNR analysis was investigated for the different clipping factors 0.7, 1.4, and 2.6. The BER performance of the asymmetrically clipped optical OFDM (ACO-OFDM) was also compared with the direct current optical OFDM (DCO-OFDM) to show the suitable effectiveness of the proposed approach. ACO-OFDM was considered to be better due to lower bit loading, but DCO-OFDM was efficient for higher SNR values. This was because the DC bias used was inefficient in terms of optical capacity, while ACO-OFDM used only half of the subcarriers to transmit the information. Moreover, ACO-OFDM two-dimensional half-subcarriers of mapping rule would introduce the clipping noise to its unused 2D subcarriers, although further data can be provided by the 2D DCO-OFDM mapping rule.

scholarly journals Study of the Performance of Deep Learning-Based Channel Equalization for Indoor Visible Light Communication Systems

Photonics ◽  
2021 ◽  
Vol 8 (10) ◽  
pp. 453
Author(s):  
Pu Miao ◽  
Weibang Yin ◽  
Hui Peng ◽  
Yu Yao
Keyword(s):  
Deep Learning ◽  
Visible Light ◽  
Communication Systems ◽  
Orthogonal Frequency Division Multiplexing ◽  
Light Emitting Diode ◽  
Visible Light Communication ◽  
Channel Equalization ◽  
Training Data ◽  
Traditional System ◽  
Ber Performance

The inherent impairments of visible light communication (VLC) in terms of nonlinearity of light-emitting diode (LED) and the optical multipath restrict bit error rate (BER) performance. In this paper, a model-driven deep learning (DL) equalization scheme is proposed to deal with the severe channel impairments. By imitating the block-by-block signal processing block in orthogonal frequency division multiplexing (OFDM) communication, the proposed scheme employs two subnets to replace the signal demodulation module in traditional system for learning the channel nonlinearity and the symbol de-mapping relationship from the training data. In addition, the conventional solution and algorithm are also incorporated into the system architecture to accelerate the convergence speed. After an efficient training, the distorted symbols can be implicitly equalized into the binary bits directly. The results demonstrate that the proposed scheme can address the overall channel impairments efficiently and can recover the original symbols with better BER performance. Moreover, it can still work robustly when the system is complicated by serious distortions and interference, which demonstrates the superiority and validity of the proposed scheme in channel equalization.

scholarly journals Improved Efficiency of Data Transmission in Wireless Communication Systems with Orthogonal Frequency Multiplexing

2021 ◽  
pp. 15-18
Author(s):  
Olga Safonova ◽  
◽  
Elena Arepyeva ◽  
Nadezhda Ermakova ◽  
◽  
...  
Keyword(s):  
Communication Systems ◽  
Orthogonal Frequency Division Multiplexing ◽  
Transmission Rate ◽  
Signal To Noise Ratio ◽  
Radio Channel ◽  
Radio Communication ◽  
Software Model ◽  
Radio Broadcasting ◽  
Mimo Ofdm ◽  
Frequency Multiplexing

The active introduction of Orthogonal Frequency Division Multiplexing (OFDM) technology is now beginning to be widely used in wireless transmission systems, television, radio communication, and radio broadcasting. The efficiency of using a dedicated frequency band at a constant high transmission rate allows you to combat interference arising from the transmission of a useful information on the radio channel. A method of improving quality of information transmission in communication systems with orthogonal frequency multiplexing is described. It is shown that with an increase in the number of receiving and transmitting antennas, the noise immunity increases significantly. An experiment was carried out to change the number of receiving-transmitting antennas and the signal-to-noise ratio, and the dependence of the appearance of an error on the number of transmitting antennas was obtained. The work investigated the software model of MIMO OFDM (modulators and demodulators). As a result of the analysis, the dependence of the appearance of the error frequency on the probability of the error was obtained. This showed that the use of OFDM and MIMO places increased demands on channel estimation.

scholarly journals Optimization of system’s parameters for wavelength conversion of E-band signals

2022 ◽  
Vol 12 (2) ◽  
pp. 1659
Author(s):  
Yazan Alkhlefat ◽  
Sevia Mahdaliza Idrus Sutan Nameh ◽  
Farabi M. Iqbal
Keyword(s):  
Communication Systems ◽  
Orthogonal Frequency Division Multiplexing ◽  
High Speed ◽  
Wavelength Conversion ◽  
Signal To Noise Ratio ◽  
Optical Amplifier ◽  
Optical Signal ◽  
Error Vector Magnitude ◽  
Wavelength Converter ◽  
High Data

Current and future wireless communication systems are designed to achieve the user’s demands such as high data rate and high speed with low latency and simultaneously to save bandwidth and spectrum. In 5G and 6G networks, a high speed of transmitting and switching is required for internet of things (IoT) applications with higher capacity. To achieve these requirements a semiconductor optical amplifier (SOA) is considered as a wavelength converter to transmit a signal with an orthogonal frequency division multiplexing with subcarrier power modulation (OFDM-SPM). It exploits the subcarrier’s power in conventional OFDM block in order to send additional bits beside the normally transmitted bits. In this paper, we optimized the SOA’s parameters to have efficient wavelength conversion process. These parameters are included the injection current (IC) of SOA, power of pump and probe signals. A 7 Gbps OFDM-SPM signal with a millimeter waves (MMW) carrier of 80 GHz is considered for signal switching. The simulation results investigated and analyzed the performance of the designed system in terms of error vector magnitude (EVM), bit error rate (BER) and optical signal-to-noise ratio (OSNR). The optimum value of IC is 0.6 A while probe power is 9.45 and 8.9 dBm for pump power. The simulation is executed by virtual photonic integrated (VPI) software.

scholarly journals Transceiver Design for GFDM with Hexagonal Time–Frequency Allocation Using the Polyphase Decomposition

Electronics ◽  
2020 ◽  
Vol 9 (11) ◽  
pp. 1862
Author(s):  
Evren Catak ◽  
Arild Moldsvor ◽  
Mohammad Derawi
Keyword(s):  
Energy Consumption ◽  
Computational Complexity ◽  
Communication Systems ◽  
Orthogonal Frequency Division Multiplexing ◽  
Channel Model ◽  
Low Latency ◽  
Frequency Division Multiplexing ◽  
Frequency Division ◽  
Next Generation ◽  
Time Frequency

Generalized frequency division multiplexing (GFDM) is a waveform for the next-generation communication systems to succeed in the drawbacks of orthogonal frequency division multiplexing (OFDM). The symbols of users are transmitted with the time- and frequency-shifted versions of a prototype filter. According to filtering operation, the computational complexity and processing load are high for the devices that suffer from energy consumption. The communication systems are required to support the new generation devices that need low energy consumption and low latency issues. Motivated by such demands of the next-generation communication system, we propose a novel GFDM waveform that we call hexagonal GFDM. The contributions of the hexagonal GFDM are that it: (i) supports short transmission time based on its hexagonal time–frequency allocations; and (ii) provides low latency communication with low computational complexity manner. Furthermore, we design a transmitter and receiver structure in a less complicated way with mathematical derivation by using polyphase decomposition and Fourier transform (FT) transformation. The proposed systems are realized analytically and investigated over Rayleigh fading channel model through computer simulations.

scholarly journals Architecture and Implementation of Fading Compensation for Dynamic Spectrum Access Wireless Communication Systems

VLSI Design ◽  
2013 ◽  
Vol 2013 ◽  
pp. 1-9
Author(s):  
Masahide Hatanaka ◽  
Toru Homemoto ◽  
Takao Onoye
Keyword(s):  
Wireless Communication ◽  
Communication Systems ◽  
Orthogonal Frequency Division Multiplexing ◽  
Dynamic Spectrum Access ◽  
Dynamic Spectrum ◽  
Wireless Communication Systems ◽  
Clock Frequency ◽  
Spectrum Access ◽  
Ofdm Symbol ◽  
Piecewise Linear Interpolation

This paper proposes an efficient architecture and implementation of fading compensation dedicated to dynamic spectrum access (DSA) wireless communication. Since pilot subcarrier arrangements are adaptively determined in wireless communication systems with DSA, the proposed architecture employs piecewise linear interpolation to the channel response estimation for data subcarriers in order to increase the channel estimation accuracy. The fading compensation for an orthogonal frequency-division multiplexing (OFDM) symbol is performed within the time for one OFDM symbol to make increase of latency smaller. The proposed architecture guarantees real-time processing with 76 MHz or higher clock frequency. The FPGA implementation of the proposed architecture occupies 1,577 slices and works up to 121 MHz.

scholarly journals Performance on FBMC-OQAM and OFDM Multicarrier Systems

2019 ◽  
Vol 8 (10) ◽  
pp. 1564-1568
Keyword(s):  
Orthogonal Frequency Division Multiplexing ◽  
Filter Bank ◽  
Signal To Noise Ratio ◽  
Cyclic Prefix ◽  
Frequency Division Multiplexing ◽  
Frequency Division ◽  
Signal To Noise ◽  
Multicarrier Systems ◽  
Noise Ratio ◽  
Power Equality

Filter Bank Multi Carrier (FBMC) offers best detestable properties took a gander at over orthogonal frequency division multiplexing (OFDM) to the attack of nonexistent hindrance. FBMC system is a multicarrier structure, particularly sensible for 5G remote correspondences. FBMC beats OFDM as a result of proficient use of the open information move limit and without usage of cyclic prefix (CP). In this paper, we address the issue of remarkable enrollment at the pilot territory and used to audit the channels with pilot picture, in like way consider the fundamental conditions for utilization of the assistant pilot pictures. First and two partner pictures for each pilot plans with power equality uses instead of one picture; it can attainable inspirations driving necessity of OFDM and FBMC depending upon signal to noise ratio (SNR) what's relentlessly possible to improve the introduction of one frivolity pictures by using multiple associate pictures. Finally autonomous the BER execution reenactment results and adornment pilot pictures

scholarly journals LDM-Ex-FDM: A Novel Multi-Service Transmission Scheme for the ATSC 3.0 System

2021 ◽  
Vol 11 (7) ◽  
pp. 3178
Author(s):  
Xianzheng Deng ◽  
Xin Bian ◽  
Mingqi Li
Keyword(s):  
Computational Complexity ◽  
Interference Cancellation ◽  
Signal To Noise Ratio ◽  
Core Layer ◽  
Mobile Service ◽  
Transmission Scheme ◽  
Equal Interval ◽  
High Modulation ◽  
Simulation Results ◽  
Ber Performance

In order to improve system coverage performance, in this paper, a multi-service transmission scheme on the basis of the puncturing technique, namely layered division multiplexing extension frequency-division multiplexing (LDM-Ex-FDM), is proposed. The key idea of the proposed scheme is that the symbols punctured from the enhanced layer (EL) of fixed services will be independently transmitted on a certain number of subcarriers orthogonal to the LDM signal of the core layer (CL) and most of the EL. By doing so, the punctured symbols will be demodulated with a higher signal-to-noise ratio (SNR) on the receiver side and can be recovered well, thus improving the reception performance of the EL fixed services. Moreover, two puncturing strategies based on bit-interleaved coded modulation (BICM) symbols of the LDM-Ex-FDM scheme, namely equal interval symbol puncturing (EISP) and non-equal interval symbol puncturing (NEISP), are developed to improve the performance of the EL services. Simulation results are given to show that, when the puncturing rate in the LDM-Ex-FDM scheme is configured as 1/12, the performance of the fixed service can be improved by 1.8 dB, meanwhile the bit error rate (BER) performance of the mobile service is not affected. Thus, the overall system coverage performance can be improved. Furthermore, to reduce the computational complexity and the demodulation delay of fixed service carried in the EL, at the receiver, a direct interference cancellation (DIC) detector is proposed as well. Simulation results are given to show that, under high injection level and high modulation order, the proposed DIC scheme is able to achieve almost the same BER performance as that of the traditional successive interference cancellation (SIC) scheme while with lower computational complexity.

scholarly journals PAPR Reduction Using Fireworks Search Optimization Algorithm in MIMO-OFDM Systems

2018 ◽  
Vol 2018 ◽  
pp. 1-11 ◽  
Author(s):  
Lahcen Amhaimar ◽  
Saida Ahyoud ◽  
Ali Elyaakoubi ◽  
Abdelmoumen Kaabal ◽  
Kamal Attari ◽  
...  
Keyword(s):  
Computational Complexity ◽  
Communication Systems ◽  
Orthogonal Frequency Division Multiplexing ◽  
Multiple Input Multiple Output ◽  
Average Power ◽  
Papr Reduction ◽  
Main Concern ◽  
Ofdm Systems ◽  
Fireworks Algorithm ◽  
Mimo Ofdm

The transceiver combination technology, of orthogonal frequency division multiplexing (OFDM) with multiple-input multiple-output (MIMO), provides a viable alternative to enhance the quality of service and simultaneously to achieve high spectral efficiency and data rate for wireless mobile communication systems. However, the high peak-to-average power ratio (PAPR) is the main concern that should be taken into consideration in the MIMO-OFDM system. Partial transmit sequences (PTSs) is a promising scheme and straightforward method, able to achieve an effective PAPR reduction performance, but it requires an exhaustive search to find the optimum phase factors, which causes high computational complexity increased with the number of subblocks. In this paper, a reduced computational complexity PTS scheme is proposed, based on a novel swarm intelligence algorithm, called fireworks algorithm (FWA). Simulation results confirmed the adequacy and the effectiveness of the proposed method which can effectively reduce the computation complexity while keeping good PAPR reduction. Moreover, it turns out from the results that the proposed PTS scheme-based FWA clearly outperforms the hottest and most important evolutionary algorithm in the literature like simulated annealing (SA), particle swarm optimization (PSO), and genetic algorithm (GA).

scholarly journals Peak-to-Average Power Ratio Reduction Method Based on Partial Transmit Sequence and Discrete Fourier Transform Spreading

Electronics ◽  
2021 ◽  
Vol 10 (6) ◽  
pp. 642
Author(s):  
Nahla Al Harthi ◽  
Zhongfeng Zhang ◽  
Daejin Kim ◽  
Seungwon Choi
Keyword(s):  
Fourier Transform ◽  
Computational Complexity ◽  
Discrete Fourier Transform ◽  
Computer Simulations ◽  
Orthogonal Frequency Division Multiplexing ◽  
Complexity Analysis ◽  
Average Power ◽  
Power Ratio ◽  
Partial Transmit Sequence ◽  
Ber Performance

Recently, filter bank multicarrier with offset quadrature amplitude modulation (FBMC/OQAM) has received increasing attention from researchers, owing to its merits and superior spectral efficiency. High peak-to-average power ratio (PAPR) occurs in approximately all multicarrier systems, including FBMC/OQAM, and may cause bit-error-rate (BER) degradation if not appropriately handled. Conventional PAPR reduction methods for orthogonal frequency division multiplexing (OFDM), such as partial transmit sequence (PTS), selective mapping (SLM), and discrete Fourier transform (DFT) spreading, are ineffective in FBMC/OQAM because of the different structure of the symbols. This study proposes a novel method combining DFT spreading and PTS methods to reduce the PAPR of FBMC/OQAM systems with reasonable computational complexity. Numerical results obtained from various computer simulations show that the proposed method achieves a noticeable enhancement in the PAPR performance of the FBMC/OQAM signal compared to other existing methods without affecting the BER performance. Further, the computational complexity analysis and BER performance of the proposed method are presented in comparison to typical existing methods. From our computer simulations, the proposed method reduces the PAPR by approximately 32.8% compared to that of the conventional methods, and the BER performance is improved by 25% with a high-power amplifier effect.

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