scholarly journals Indoor optical wireless MIMO-OFDM system

2014 ◽  
Vol 17 (1) ◽  
pp. 5-16
Author(s):  
Khoa Le Dang ◽  
Tung Thanh Vu ◽  
Tu Thanh Nguyen ◽  
Phuong Huu Nguyen
Keyword(s):  
Fading Channels ◽  
Electromagnetic Interference ◽  
Orthogonal Frequency Division Multiplexing ◽  
High Speed ◽  
Optical Wireless ◽  
Error Vector Magnitude ◽  
Ofdm System ◽  
High Data ◽  
Mimo Ofdm ◽  
Vector Magnitude

Indoor optical wireless systems have attracted attention, because they allow high-speed transmission without electromagnetic interference. Multi Input Multi Output (MIMO) techniques are very promising in providing high data rate or providing performance over fading channels. Orthogonal frequency division multiplexing (OFDM) can send multiple high speed signals by using orthogonal carrier frequencies. In this paper, we propose an optical wireless MIMO-OFDM system to achieve better performance. The signal of each optical transmit antenna is detected by using zero forcing (ZF) algorithm. We use the error vector magnitude (EVM) to predict BER performance. The analysis of bit error rate (BER) shows that the proposed system achieve better performance transmission than OMIMO system when transmitting the signal over reflection channels.

scholarly journals Channel capacity and performance evaluation of precoded MIMO-OFDM system with large-size constellation

2019 ◽  
Vol 9 (6) ◽  
pp. 5024
Author(s):  
Hussein A. Leftah ◽  
Huda N. Alminshid
Keyword(s):  
Fading Channels ◽  
Channel Capacity ◽  
Orthogonal Frequency Division Multiplexing ◽  
Multiple Input Multiple Output ◽  
Ofdm System ◽  
Large Size ◽  
Multiple Input ◽  
Input Multiple Output ◽  
Mimo Ofdm ◽  
And Performance

<p>Multiple input-multiple output (MIMO) is a multipath diversity exploring approach which is emerged with orthogonal frequency division multiplexing (OFDM) to produce MIMO-OFDM that is widely used in wireless communications. This paper presents a discrete Hart-ley transform (DHT) precoded MIMO-OFDM system over multipath frequency-selective fading channel with large-size quadrature amplitude modulation (16-QAM, 64-QAM and 256-QAM). A mathematical models for the BER and channel capacity over mutlipath fading channels are also derived in this paper. Average Bit-error-rate (BER) and channel capacity of the presented system is considered and compared with that of the traditional MIMO-OFDM. Simulation results shows that the transmission performance and channel capacity of the proposed schemes is better than that of the traditional MIMO-OFDM without a pre-coder.</p>

scholarly journals An auto synchronization technique of unipolar MPAM signals in OFDM and its application for optical wireless communication systems

2015 ◽  
Vol 18 (3) ◽  
pp. 218-224
Author(s):  
Khoa Le Dang ◽  
Phuong Huu Nguyen ◽  
Hiroshi Ochi
Keyword(s):  
Electromagnetic Interference ◽  
Communication Systems ◽  
Orthogonal Frequency Division Multiplexing ◽  
High Speed ◽  
Wireless Systems ◽  
Cyclic Prefix ◽  
Wireless Communication Systems ◽  
Optical Wireless Communication ◽  
Frequency Division ◽  
Optical Wireless

Optical wireless systems have attracted attention, because they allow high-speed transmission without electromagnetic interference. Orthogonal frequency division multiplexing (OFDM) can send multiple high speed signals by using orthogonal carrier frequencies. Recently, studies have been focused on the optimal OFDM technique for optical wireless systems. When using OFDM, one important issue is determining the cyclic prefix and removing it from the frame before the receiver detects signals. In this paper, we propose a new auto synchronization technique of unipolar MPAM signals. It can remove the cyclic prefix in any sample of the OFDM frame using unipolar MPAM. It is a candidate for wideband systems and using 2-PAM or 4-PAM. The results of mathematical analysis and simulations show that it can be used for optical wireless systems.

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 BER PERFORMANCE ANALYSIS OF 4QAM/OFDM OVER DIFFERENT SCENARIOS OF LAPLACE FADING CHANNEL.

2021 ◽  
Vol 25 (Special) ◽  
pp. 1-26-1-33
Author(s):  
Hassan F. Mohammed ◽  
◽  
Ghanim A. Al-Rubaye ◽  
Keyword(s):  
Fading Channels ◽  
Fading Channel ◽  
Orthogonal Frequency Division Multiplexing ◽  
High Speed ◽  
Additive White Gaussian Noise ◽  
Multipath Fading ◽  
Local Area ◽  
Ofdm System ◽  
Multicarrier Transmission ◽  
Simulation Results

Multicarrier transmission, also known as (OFDM) Orthogonal Frequency Division multiplexing, in wireless communications, it has been proven to be an essential technique for countering multipath fading. It has been used successfully for HF radio applications and has been selected as the interface for digital audio transmission, digital terrestrial TV broadcasting, and high-speed wireless local area networks in Europe. In this paper, we suggested a new design for modeling multipath fading channels, such as the Laplace fading channel, in order to discover new simulation results and effects. Furthermore, the variance of the Laplace fading channel has been computed and the new Bit Error Rate (BER) derivation is established, and the performance of (M-QAM), M-ary Quadrature Amplitude Modulation (with M=4 over OFDM system under Laplace fading channels in Additive White Gaussian Noise (AWGN) is discussed and compared to the conventional M-QAM/OFDM system Rayleigh fading channel in AWGN. All the simulation results are examined using the optimum signal detection based on the Euclidean distance and evaluated using Monte-Carlo simulation.

scholarly journals On the Comparison of Various Overhead Arrangements for Massive MIMO-OFDM Channel Estimation

2014 ◽  
Vol 60 (2) ◽  
pp. 173-179 ◽  
Author(s):  
Pallaviram Sure ◽  
Chandra Mohan Bhuma
Keyword(s):  
System Reliability ◽  
Massive Mimo ◽  
Orthogonal Frequency Division Multiplexing ◽  
Mimo Systems ◽  
Cyclic Prefix ◽  
Doppler Spectrum ◽  
Ofdm Systems ◽  
Ofdm System ◽  
High Data ◽  
Mimo Ofdm

Abstract Massive multi input multi output (MIMO) systems incorporate orthogonal frequency division multiplexing (OFDM) technology to render high data rate services for future wireless communication applications. The channel estimator (CE) employed by a reliable massive MIMO-OFDM system requires huge amount of overhead in the form of known and null data transmissions, hence limiting the system spectral efficiency (SE). Often, CE design is a tradeoff between SE and system reliability. In this paper, CE with three different overhead arrangements, namely time domain synchronous (TDS), comb type with cyclic prefix (CTCP), 2D grid type with cyclic prefix (GTCP) are investigated and a GTCP based CE is proposed which offers both high SE and improved system reliability. The proposed CE uses autocorrelation based denoising threshold for channel impulse response (CIR) estimation and does not require any knowledge of channel statistics (KCS). A 4 x 16 MIMO-OFDM system is simulated in a rayleigh fading channel environment with U-shaped doppler spectrum. From the bit error rate (BER) performance results inWiMax SUI-4, Advanced Television Technology Center (ATTC) and Brazil A channel environments, it is verified that the proposed CE with GTCP overhead and proposed denoising scheme, indeed improves both SE and system reliability. Hence it is suitable for application in all massive MIMO-OFDM systems.

scholarly journals Phase Noise Effect on MIMO-OFDM Systems with Common and Independent Oscillators

2017 ◽  
Vol 2017 ◽  
pp. 1-12 ◽  
Author(s):  
Xiaoming Chen ◽  
Hua Wang ◽  
Wei Fan ◽  
Yaning Zou ◽  
Andreas Wolfgang ◽  
...  
Keyword(s):  
Orthogonal Frequency Division Multiplexing ◽  
Multiple Input Multiple Output ◽  
Spatial Multiplexing ◽  
Ofdm Systems ◽  
Error Vector Magnitude ◽  
Multiple Input ◽  
Input Multiple Output ◽  
Mimo Ofdm ◽  
Value Decomposition ◽  
Vector Magnitude

The effects of oscillator phase noises (PNs) on multiple-input multiple-output (MIMO) orthogonal frequency division multiplexing (OFDM) systems are studied. It is shown that PNs of common oscillators at the transmitter and at the receiver have the same influence on the performance of (single-stream) beamforming MIMO-OFDM systems, yet different influences on spatial multiplexing MIMO-OFDM systems with singular value decomposition (SVD) based precoding/decoding. When each antenna is equipped with an independent oscillator, the PNs at the transmitter and at the receiver have different influences on beamforming MIMO-OFDM systems as well as spatial multiplexing MIMO-OFDM systems. Specifically, the PN effect on the transmitter (receiver) can be alleviated by having more transmit (receive) antennas for the case of independent oscillators. It is found that the independent oscillator case outperforms the common oscillator case in terms of error vector magnitude (EVM).

Joint Channel Estimation and Signal Detection for the OFDM System Without Cyclic Prefix Over Doubly-Selective Channels

2015 ◽  
Vol 25 (14) ◽  
pp. 1540028
Author(s):  
Lijun Song ◽  
Xia Lei ◽  
Maozhu Jin ◽  
Zhihan Lv
Keyword(s):  
Channel Estimation ◽  
Signal Detection ◽  
Fading Channels ◽  
Orthogonal Frequency Division Multiplexing ◽  
High Speed ◽  
Detection Algorithm ◽  
Cyclic Prefix ◽  
Fast Time ◽  
Ofdm System ◽  
Joint Channel

In the high-speed railway wireless communication, a joint channel estimation and signal detection algorithm is proposed for the orthogonal frequency division multiplexing (OFDM) system without cyclic prefix in the doubly-selective fading channels. Our proposed method first combines the basis expansion model (BEM) and the inter symbol interference (ISI) cancellation to overcome the situation that exists with the fast time-varying channel and the normalized maximum multipath channel exceeding the length of the cyclic prefix (CP). At first, the channel estimation and signal detection can be approximated without considering the ISI. Then, the channel parameters and signal detection are updated through ISI cancellation and circular convolution reconstruction from the frequency domain. The simulations show the algorithm can improve the performance of channel estimation and signal detection.

Spectral Efficiency in Wireless Networks through MIMO-OFDM System

2017 ◽  
pp. 249-277
Author(s):  
Shuvabrata Bandopadhaya ◽  
Jibendu Sekhar Roy
Keyword(s):  
Orthogonal Frequency Division Multiplexing ◽  
Multiple Input Multiple Output ◽  
Wireless Channel ◽  
Estimation Methods ◽  
Ofdm System ◽  
Spectrum Utilization ◽  
High Data ◽  
Rate Transmission ◽  
Input Multiple Output ◽  
Mimo Ofdm

The traffic in Wireless Sensor Network (WSN) is brusty in nature; when any incident takes place, the data load on the channel increases suddenly demanding large channel spectrum. The scarcity of spectrum is the major technical obstacle for high data rate transmission along with better quality of service in any kind of wireless network. Hence it is very essential to enhance the spectrum efficiency of wireless channel. The major technical advancement in the physical layer which brings feasibility of broadband data transmission without increasing the transmission bandwidth or transmitting power are implementation of Multiple Input Multiple Output (MIMO) communication system with Orthogonal Frequency Division Multiplexing (OFDM) as modulation schemes. This chapter includes the fundamental concept of MIMO-OFDM system along with the channel estimation methods and the spectrum utilization issues therein.

Incorporating SDC Module for ISI Compensation for a Long-Haul Co-OFDM System

2018 ◽  
Vol 0 (0) ◽  
Author(s):  
Anu Chauhan ◽  
Arti Vaish
Keyword(s):  
Orthogonal Frequency Division Multiplexing ◽  
Dispersion Compensation ◽  
Data Rate ◽  
High Data Rate ◽  
Error Vector Magnitude ◽  
Ofdm System ◽  
Rate System ◽  
High Data ◽  
Ofdm Signal ◽  
Compensation Technique

AbstractWith the increase in demand of bandwidth hungry applications, it is recommended to develop a high data rate system for long-haul coherent optical orthogonal frequency division multiplexing (CO-OFDM). At a very high data rate, CO-OFDM signal experiences deterioration. At 50 Gbps, the signal experiences ISI effect and in order to overcome this ISI effect, a prolonged system has been developed to reach optimal ISI compensation technique. One of the prominent and competent techniques to enhance system performance is (SDCM) symmetrical dispersion compensation module. In order to make system more bandwidth efficient 4-QAM (Quadrature Amplitude Modulation) with gray coding is applied and manual adjustments are done at receiver phase to decrease error vector magnitude (EVM). OFDM data stream is successfully transmitted over a distance of 4,000 km to compete the demand of long-haul CO-OFDM system. With different launch powers and laser linewidths, the performance of the system is enhanced in terms of Q-factor, SNR and EVM.

scholarly journals EFFICIENT ANALYSIS OF MIMO-OFDM SYSTEM IN NAKAGAMI-m FADING CHANNEL

2016 ◽  
Vol 54 (6) ◽  
pp. 698
Author(s):  
Ho Van Cuu ◽  
Hoang Hiep Le ◽  
Nguyen Thi Thu-Hang
Keyword(s):  
Phase Shift ◽  
Fading Channels ◽  
Error Rate ◽  
Fading Channel ◽  
Orthogonal Frequency Division Multiplexing ◽  
Multipath Fading ◽  
Phase Shift Keying ◽  
Ofdm System ◽  
Shift Keying ◽  
Mimo Ofdm

Bit error rate (BER) and symbol error rate (SER) performance response fading parameter for multiple-input multiple-output (MIMO) orthogonal frequency division multiplexing (OFDM) system over Nakagami-m fading channel would be provided in this study. Some channel simulations and evaluations were for 2×2 MIMO-OFDM system in which data are sent from two transmit antennas to two receive antennas. In this study, authors have used binary phase-shift keying (BPSK) and quadrature phase-shift keying (QPSK) modulation techniques to modulate the data stream. In addition, numerical results have been presented and compared for several different environmental propagations such as Nakagami-m, Rician, Rayleigh multipath fading channels, and non-fading additive white Gaussian noise (AWGN) channel. Based on such obtained presentation and comparison, the paper would discuss further about relation between value of paramater m and quality of system.

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