scholarly journals Channel Estimation Based on IOTA Filter in OFDM/OQPSK and OFDM/OQAM Systems

2019 ◽  
Vol 9 (7) ◽  
pp. 1454 ◽  
Author(s):  
Xiao Zhou ◽  
Chengyou Wang ◽  
Ruiguang Tang
Keyword(s):  
Channel Estimation ◽  
Fading Channels ◽  
Orthogonal Frequency Division Multiplexing ◽  
Rayleigh Fading ◽  
Noise Suppression ◽  
Additive White Gaussian Noise ◽  
Density Ratio ◽  
Estimation Method ◽  
Rayleigh Fading Channels ◽  
Noise Power

In this paper, we present a study of bit error rate (BER) for orthogonal frequency division multiplexing/offset quadrature phase shift keying (OFDM/OQPSK) and OFDM/offset quadrature amplitude modulation (OQAM) systems with an isotropic orthogonal transfer algorithm (IOTA) filter. The novel noise suppression method based on an IOTA filter is proposed to reduce the error of channel estimation caused by additive white Gaussian noise (AWGN). The OFDM/OQPSK and OFDM/OQAM systems do not insert the guard interval (GI) and pilots in the signal frames, thus they possess transmission efficiency. An analysis was carried out for convolutional coded OFDM/OQPSK and OFDM/OQAM systems in Rayleigh fading channels with generator polynomials and constraint lengths. Compared with conventional OFDM/QPSK and OFDM/QAM systems with the insertion of comb-type pilots, the proposed IOTA filter-based channel estimation method can provide significant energy per bit to time-varying noise power spectral density ratio gains over time and frequency-selective propagation Rayleigh fading channels in OFDM/OQPSK and OFDM/OQAM systems.

New OFDM Channel Estimation Method Based on ISI Cancellation

2014 ◽  
Vol 651-653 ◽  
pp. 2343-2346
Author(s):  
Jin Cui ◽  
Ding Rong Shao ◽  
Bo Zhang
Keyword(s):  
Channel Estimation ◽  
Orthogonal Frequency Division Multiplexing ◽  
Rayleigh Fading ◽  
Additive White Gaussian Noise ◽  
Estimation Method ◽  
Low Complexity ◽  
Cyclic Prefix ◽  
Time Varying ◽  
Frequency Division ◽  
Varying Environments

According to the application needs of OFDM techniques, a new method of orthogonal frequency division multiplexing (OFDM) channel estimation based on inter symbol interference (ISI) cancellation was proposed. The channel estimation was based on circular convolution, after which a low-complexity frequency-domain ZF equalization was used. The performance of bit-error-rate (BER) was also simulated and analyzed under the additive-white-Gaussian-noise (AWGN) channel, Rayleigh fading channel with mobility. The simulation results showed that this method could be applied to the channels of time-varying environments, and could get better performance than the traditional cyclic prefix (CP)-OFDM.

PERFORMANCE OF QAM-OFDM SYSTEM OVER RAYLEIGH FADING CHANNEL IN WEI BULL NOISE DISTRIBUTION

2021 ◽  
Vol 25 (Special) ◽  
pp. 1-157-1-166
Author(s):  
Nabaa I. Abed ◽  
◽  
Ghanim A.AL Rubaye ◽  
Keyword(s):  
Fading Channels ◽  
Communication Networks ◽  
Orthogonal Frequency Division Multiplexing ◽  
Rayleigh Fading ◽  
Additive White Gaussian Noise ◽  
Wireless Networking ◽  
Ofdm System ◽  
Exact Match ◽  
Communication Industry ◽  
Non Gaussian

The phenomenal increase in the usage of mobile devices and wireless networking tools in recent years has resulted in the communication industry needing higher data speeds for connections and bandwidth. As a result, multi-carrier modulation has been suggested as a reliable and effective method of transmitting data over difficult communication networks such as selective fading channels. Orthogonal Frequency Division Multiplexing (OFDM) is a highly effective multi-carrier technique that can meet users' high demands. Many studies have looked into this technique, mostly as a way to counteract fading and Additive White Gaussian Noise (AWGN). As a result, the performance evaluation of the QAM-OFDM system in the presence of multi-path Rayleigh fading in Weibull noise is examined in this article. Furthermore, bit error rate performance (BER) is computed using the optimal derivation of the real system contaminated by compound Gaussian and non-Gaussian (Weibull) noise distributions at the OFDM demodulator output. The derived result is an exact match to the simulated result over various scenarios introduced by the MATLAB software package.

scholarly journals A Novel Noise Suppression Channel Estimation Method Based on Adaptive Weighted Averaging for OFDM Systems

Symmetry ◽  
2019 ◽  
Vol 11 (8) ◽  
pp. 997 ◽  
Author(s):  
Zhang ◽  
Zhou ◽  
Wang
Keyword(s):  
Fourier Transform ◽  
Channel Estimation ◽  
Fast Fourier Transform ◽  
Orthogonal Frequency Division Multiplexing ◽  
Noise Suppression ◽  
Estimation Method ◽  
Weighted Averaging ◽  
Doppler Spread ◽  
Estimation Methods ◽  
Ofdm Systems

Orthogonal frequency division multiplexing (OFDM) systems have inherent symmetric properties, such as coding and decoding, constellation mapping and demapping, inverse fast Fourier transform (IFFT) and fast Fourier transform (FFT) operations corresponding to multi-carrier modulation and demodulation, and channel estimation is a necessary module to resist channel fading in the OFDM system. However, the noise in the channel will significantly affect the accuracy of channel estimation, which further affects the recovery quality of the final received signals. Therefore, this paper proposes an efficient noise suppression channel estimation method for OFDM systems based on adaptive weighted averaging. The basic idea of the proposed method is averaging the last few channel coefficients obtained from coarse estimation to suppress the noise effect, while the average frame number is adaptively adjusted by combining Doppler spread and signal-to-noise ratio (SNR) information. Meanwhile, to better combat the negative effect brought by Doppler spread and inter-carrier interference (ICI), the proposed method introduces a weighting factor to correct the weighted value of each frame in the averaging process. Simulation results show that the proposed channel estimation method is effective and provides better performance compared with other conventional channel estimation methods.

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