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 Optimization of Massive MIMO-OFDM Systems for PAPR Reduction

2020 ◽  
Vol 2 (2) ◽  
pp. 29-35
Author(s):  
Sivasankari J ◽  
Sridevi B ◽  
Mahima L
Keyword(s):  
Massive Mimo ◽  
Firefly Algorithm ◽  
Ofdm Systems ◽  
Ofdm System ◽  
High Data ◽  
Recent Approach ◽  
Current Scenario ◽  
Mimo Ofdm ◽  
Mimo Technology

Of late there has been an increase in use of wireless communication system. The recent approach used is Massive-MIMO technology. But in the current scenario where spectrum is limited, the demand for high data degrades the quality of services. Therefore, OFDM system was proposed. Though coupling OFDM system with MIMO can further improve the performance of next generation wireless systems, there are certain issues like antenna design, channel estimation, PAPR etc. which requires due consideration. Amongst them, PAPR is the major problem that contributes high in performance degradation. To overcome this issue, Modified Firefly algorithm is used which was inspired the behaviour of fireflies. With the firefly algorithm, PAPR is highly reduced leading to better performance.

scholarly journals SBL Kalman Filter Based Hybrid Precoder/ Combiner for mmWave MIMO Systems: A Frequency Domain Approach

2021 ◽  
Author(s):  
Shoukath Ali k ◽  
Sampath Palaniswami
Keyword(s):  
Kalman Filter ◽  
Frequency Domain ◽  
Orthogonal Frequency Division Multiplexing ◽  
Mimo Systems ◽  
Least Square ◽  
Ofdm Systems ◽  
Millimetre Wave ◽  
Minimum Number ◽  
Mimo Ofdm ◽  
Frequency Domain Approach

Abstract The optimal design of hybrid precoder/ combiner for Millimetre Wave (mmWave) Multiple Input and Multiple Output Orthogonal Frequency Division Multiplexing (MIMO-OFDM ) system is developed presented. In the frequency domain approach, Sparse Bayesian Learning - Kalman Filter (SBL-KF) algorithm is used to design the optimal hybrid precoder/ combiner in mmWave MIMO OFDM systems. Sparse signal recovery problem for Single Measurement Vector (SMV) is discussed, that is close to the design of ideal digital baseband precoder by maximizing the mutual information from the hybrid precoder. SBL-KF scheme select the minimum number of active Radio Frequency (RF) chains based on the hyper parameter estimator. The minimum number of RF chain is approximate the ideal digital precoder / combiner design. Proposed SBL-KF scheme achieve low power consumption and enhanced spectral efficiency, when compared to the SBL, Orthogonal Matching Pursuit (OMP), Simultaneous OMP (SOMP) and Least Square schemes, which activate a fixed data streams and fixed number of RF chains.

scholarly journals Uplink Multiuser MIMO-OFDM System in the Presence of Phase Noises, Power Imbalance, and Correlation

2018 ◽  
Vol 2018 ◽  
pp. 1-8
Author(s):  
Xiaoming Chen ◽  
Andreas Wolfgang ◽  
Tommy Svensson
Keyword(s):  
Orthogonal Frequency Division Multiplexing ◽  
Mimo Systems ◽  
Multiple Input Multiple Output ◽  
Base Station ◽  
Closed Form Expression ◽  
Ofdm System ◽  
Multiuser Mimo ◽  
Single Antenna ◽  
Input Multiple Output ◽  
Mimo Ofdm

The effects of phase noises (PNs), power imbalances, and correlations on multiuser orthogonal frequency division multiplexing (OFDM) multiple-input multiple-output (MIMO) systems are studied. It is assumed that each user is equipped with a single antenna, whereas the base station (BS) has multiple antennas and use zero-forcing (ZF) decoder for multiuser detection. Since each user has an independent oscillator, the received uplink (UL) signal at each BS antenna is corrupted by all of these independent PNs. Furthermore, there may be power imbalances and correlations (due to common scatterers) between different users. These impairments are jointly analyzed in this work. A closed-form expression of the mean square error (MSE) performance of the multiuser MIMO-OFDM system is derived. The analytical results are verified by simulations.

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.

scholarly journals A Novel Hybrid Block INF Diagonalization (HBID) Precoding Technique for Capacity Improvement in MU-MIMO-OFDM System

2019 ◽  
Vol 9 (1) ◽  
pp. 5369-5375
Keyword(s):  
Orthogonal Frequency Division Multiplexing ◽  
Mimo System ◽  
Multiple Input Multiple Output ◽  
Average Power ◽  
Threshold Value ◽  
Ofdm Systems ◽  
Ofdm System ◽  
Transmission Scheme ◽  
Mimo Ofdm ◽  
Sum Rate

In wireless communication system, the emerging technology is MU-Multiple Input Multiple Output-Orthogonal Frequency Division Multiplexing (MU-MIMO-OFDM). For minimizing Peak-to-Average Power Ratio (PAPR) in the uplink transmission scheme, OFDM is exploited in MIMO system and compared with Single Carrier-Frequency Domain Processing (SC-FDP). Further reducing the PAPR value, a new method is proposed Hybrid Block Inf Diagonalization (HBID) technique for an uplink OFDM system and calculated the less Bit Error Rate (BER). In this paper, the HBID precoding technique reduces PAPR with such amount and unwanted amplitude of the signal is to be cut down for a specific threshold value as 1.4 for best performance so that the PAPR value is reduced in considerable rate of OFDM then compared to SC-FDP system. Also, we compared the various precoding techniques with HBID method in MIMO-OFDM systems with various parameters such as BER, PAPR, Number of users, Sum rate. Finally, the proposed method reduces PAPR with 47% and BER with 50%, number of users with 49% and sum rate as 57%. HBID based precoding method shows its excellence with the lowest PAPR value and thereby enhance the presentation of the OFDM system

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 The effect of wavelet transform on OFDM system in modern cellular networks

2019 ◽  
Vol 15 (1) ◽  
pp. 324
Author(s):  
Mayada Faris Ghanim
Keyword(s):  
Fourier Transform ◽  
Wavelet Transform ◽  
Wireless Communications ◽  
Cellular Networks ◽  
Orthogonal Frequency Division Multiplexing ◽  
Cyclic Prefix ◽  
Frequency Division Multiplexing ◽  
Frequency Division ◽  
Ofdm Systems ◽  
Ofdm System

Wavelet transform has many advantages that make it suitable and efficient approach to replace Fast Fourier Transform (FFT) in conventional Orthogonal Frequency Division Multiplexing (OFDM) systems. Wavelet transform is employed in modern cellular networks to remove the use of cyclic prefix, which leads to decreasing the bandwidth losses and the power of transmission. Wavelet based OFDM system is designed in order to overcome the drawbacks of OFDM system so that the proposed system is good candidate for next generation wireless communications.

scholarly journals Distributed Structured Compressive Sensing-Based Time-Frequency Joint Channel Estimation for Massive MIMO-OFDM Systems

2019 ◽  
Vol 2019 ◽  
pp. 1-16 ◽  
Author(s):  
Wenjie Zhang ◽  
Hui Li ◽  
Rong Jin ◽  
Shanlin Wei ◽  
Wei Cheng ◽  
...  
Keyword(s):  
Energy Efficiency ◽  
Channel Estimation ◽  
Massive Mimo ◽  
Orthogonal Frequency Division Multiplexing ◽  
Spectrum Efficiency ◽  
Ofdm Systems ◽  
Time Frequency ◽  
Common Support ◽  
Mimo Ofdm ◽  
Joint Channel

In massive multi-input multi-output orthogonal frequency division multiplexing (MIMO-OFDM) systems, accurate channel state information (CSI) is essential to realize system performance gains such as high spectrum and energy efficiency. However, high-dimensional CSI acquisition requires prohibitively high pilot overhead, which leads to a significant reduction in spectrum efficiency and energy efficiency. In this paper, we propose a more efficient time-frequency joint channel estimation scheme for massive MIMO-OFDM systems to resolve those problems. First, partial channel common support (PCCS) is obtained by using time-domain training. Second, utilizing the spatiotemporal common sparse property of the MIMO channels and the obtained PCCS information, we propose the priori-information aided distributed structured sparsity adaptive matching pursuit (PA-DS-SAMP) algorithm to achieve accurate channel estimation in frequency domain. Third, through performance analysis of the proposed algorithm, two signal power reference thresholds are given, which can ensure that the signal can be recovered accurately under power-limited noise and accurately recovered according to probability under Gaussian noise. Finally, pilot design, computational complexity, spectrum efficiency, and energy efficiency are discussed as well. Simulation results show that the proposed method achieves higher channel estimation accuracy while requiring lower pilot sequence overhead compared with other methods.

MINIMIZING HIGH PAPR IN OFDM SYSTEM USING CIRCULANT SHIFT CODEWORD

2016 ◽  
Vol 78 (2) ◽  
Author(s):  
Ezmin Abdullah ◽  
Azlina Idris ◽  
Azilah Saparon
Keyword(s):  
Orthogonal Frequency Division Multiplexing ◽  
Average Power ◽  
Signal Distortion ◽  
Ofdm Systems ◽  
Ofdm System ◽  
High Data ◽  
Distortion Energy ◽  
Db Difference ◽  
Selective Mapping ◽  
Ofdm Signals

Orthogonal Frequency Division Multiplexing (OFDM) has been widely used in various high data rate wireless communications standards. The high peak-to-average power ratio (PAPR) has however been known to be a constant problem in OFDM systems. The high PAPR in the OFDM system has led to many problems such as signal distortion, energy spilling to the adjacent channel and reducing system performance gradually. In this paper, a technique involving the manipulation of codeword using circulant shift will be introduced. The key idea of the proposed technique is to generate scramble data sequences like the conventional selective mapping (SLM) technique. The simulation results showed that the proposed technique overcame original OFDM signals and conventional SLM with a 19.5% improvement and 1.1 dB difference from conventional SLM. Besides that, the proposed technique offered a lower computationally complexity where the number of IFFT blocks can be reduced by about 57% as compared to conventional SLM.  

scholarly journals ICI and PAPR enhancement in MIMO-OFDM system using RNS coding

2019 ◽  
Vol 9 (2) ◽  
pp. 1209
Author(s):  
M. I. Youssef ◽  
A. E. Emam ◽  
M. Abd Khalifa
Keyword(s):  
Orthogonal Frequency Division Multiplexing ◽  
Multiple Input Multiple Output ◽  
Number System ◽  
Residue Number System ◽  
Cumulative Distribution ◽  
Transmission Model ◽  
Ofdm Systems ◽  
Ofdm System ◽  
Mimo Ofdm ◽  
Residue Numbers

<p><span>The Inter-Carrier-Interference (ICI) is considered a bottleneck in the utilization of Multiple-Input-Multiple-Output Orthogonal Frequency Division Multiplexing (MIMO-OFDM) systems, due to the sensitivity of the OFDM towards frequency offsets which lead to loss of orthogonality, interference and performance degradation. In this paper Residue Numbers as a coding scheme is impeded in MIMO-OFDM systems, where the ICI levels is measured and evaluated with respect to conventional ICI mitigation techniques implemented in MIMO-OFDM. The Carrier-to-Interference Ratio (CIR), the system Bit-Error-Rate (BER) and the Complementary Cumulative Distribution Function (CCDF) for MIMO-OFDM system with Residue Number System (RNS) coding are analyzed and evaluated. The results had demonstrated a performance of transmission model with and without RNS.</span></p>

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