Novel decision-directed channel estimation method for TDS-OFDM system

2008 ◽  
Author(s):  
Fang Yang ◽  
Kewu Peng ◽  
Jian Song ◽  
Changyong Pan ◽  
Zhixing Yang
Keyword(s):  
Channel Estimation ◽  
Estimation Method ◽  
Ofdm System

scholarly journals Pilot Based Channel Estimation and Synchronization in OFDM System

2020 ◽  
Vol 26 (6) ◽  
pp. 50-59
Author(s):  
Mahmood Mohmmmed saeed Abdul Majed ◽  
Buthaina Mosa Omran
Keyword(s):  
Channel Estimation ◽  
Orthogonal Frequency Division Multiplexing ◽  
Carrier Frequency Offset ◽  
Estimation Method ◽  
Frequency Division ◽  
Ofdm System ◽  
Synchronization Errors ◽  
Rayleigh Channel ◽  
Significant Performance ◽  
Time Offset

Channel estimation and synchronization are considered the most challenging issues in Orthogonal Frequency Division Multiplexing (OFDM) system. OFDM is highly affected by synchronization errors that cause reduction in subcarriers orthogonality, leading to significant performance degradation. The synchronization errors cause two issues: Symbol Time Offset (STO), which produces inter symbol interference (ISI) and Carrier Frequency Offset (CFO), which results in inter carrier interference (ICI). The aim of the research is to simulate Comb type pilot based channel estimation for OFDM system showing the effect of pilot numbers on the channel estimation performance and propose a modified estimation method for STO with less number of pilot to mitigate ISI effect. Channel estimation is simulated for different pilot number with 16QAM modulation in Ped-A Rayleigh channel. The STO effect assumed less than the cyclic prefix length to minimize ISI and maintain the orthogonality between subcarriers. The simulation results show that the high number of pilots are needed to achieve good channel estimation in case no synchronization used while similar results are achieved with smaller number of pilots if the propose modification on the synchronization method are used aligned with the channel estimation. The proposed system is evaluated in terms of BER and SNR.

scholarly journals Singular Value Decomposition Channel Estimation in STBC MIMO-OFDM System

2019 ◽  
Vol 9 (15) ◽  
pp. 3067 ◽  
Author(s):  
Tang ◽  
Zhou ◽  
Wang
Keyword(s):  
Singular Value Decomposition ◽  
Channel Estimation ◽  
Estimation Method ◽  
Singular Value ◽  
Ofdm System ◽  
Time Block ◽  
Autocorrelation Matrix ◽  
Mimo Ofdm ◽  
Value Decomposition ◽  
Inverse Operation

The multiple-input multiple-output orthogonal frequency division multiplexing (MIMO-OFDM) technology is the combination of the OFDM and MIMO technologies, which could improve the system capacity and make efficient utilization of the frequency spectrum. This paper utilizes space-time block coding (STBC) to achieve diversity gains and combat the channel fading. However, channel estimation is an essential block for space-time block decoding (STBD). Many channel estimation methods are utilized for the single antenna OFDM system, but they cannot be directly applied to the multiple antennas system due to the interference from other antennas. In this paper, orthogonal pilot sequences are designed to suppress the interference of pilot symbols from other transmit antennas. This paper also derives a minimum mean square error (MMSE) channel estimation method in MIMO-OFDM systems. The MMSE method involves the inverse operation of the channel autocorrelation matrix, which has a large calculation complexity. To further reduce the complexity of the MMSE method, the singular value decomposition (SVD) is used to decompose the channel autocorrelation matrix, which avoids the inverse operation. Simulation results verify that the SVD channel estimation method with comb-type pilots and STBC can be effectively adapted to multipath propagation conditions.

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