scholarly journals Quasi-Orthogonal Time Division Multiplexing and Its Performances in Rayleigh Fading Channels

2012 ◽  
Vol 2012 ◽  
pp. 1-5
Author(s):  
Enchang Sun ◽  
Kechu Yi ◽  
Bin Tian ◽  
Dongying Zhang
Keyword(s):  
Fading Channels ◽  
Orthogonal Frequency Division Multiplexing ◽  
Rayleigh Fading ◽  
Carrier Frequency Offset ◽  
Satellite Communications ◽  
Rayleigh Fading Channels ◽  
Transmission Scheme ◽  
Time Division Multiplexing ◽  
Single Carrier ◽  
Time Division

This paper proposes an efficient transmission scheme, Quasi-Orthogonal Time Division Multiplexing (QOTDM), which employs the shift orthogonal property of the pulse function with raised-cosine spectral shape, and the signal waveforms are quasi-orthogonal in time domain. Comparing to orthogonal frequency division multiplexing (OFDM), QOTDM is less sensitive to carrier frequency offset and power amplifier nonlinearities while keeping a similar spectral efficiency with OFDM due to single-carrier characteristics. QOTDM is a suitable consideration for the downlink transmission such as in satellite communications. An upper bound of sample error probability (SER) is derived to evaluate the performance of QOTDM. Comparisons of QOTDM and OFDM in Rayleigh fading channels show that the proposed QOTDM system is better than that of OFDM system in terms of bit error rate (BER) in high Eb/No regions.

scholarly journals Performance Enhanced Coded OFDM with Almost Linear Inter leaver over Rayleigh Fading Channels

2021 ◽  
Author(s):  
chenggao han
Keyword(s):  
Fading Channels ◽  
Orthogonal Frequency Division Multiplexing ◽  
Rayleigh Fading ◽  
Rayleigh Fading Channels ◽  
Frequency Division ◽  
Industry Standards ◽  
Comprehensive Performance ◽  
Union Bound ◽  
Simulation Results ◽  
Coded Ofdm

This paper presents a comprehensive performance analysis of coded orthogonal frequency division multiplexing (COFDM) over the quasi-static multipath Rayleigh fading channels. We first analyze the pairwise error probability (PEP) of COFDM and then consider the union bound on bit error rate (BER) by introducing the notion of diversity guard (DG) and a novel interleaver class, named almost linear interleaver (ALI). A construction of ALI is also introduced with its parameter selection. Simulation results show that the COFDM with ALI outperforms that with random interleaver (RI) and the block interleaver (BI) adopted in the IEEE industry standards.<br><br>

scholarly journals Software-Based Analysis of Multi User Orthogonal Frequency Division Multiplexing (OFDM)

2016 ◽  
Vol 3 (2) ◽  
pp. 1-6
Author(s):  
Widya Catur Kristanti Putri
Keyword(s):  
Fading Channels ◽  
Orthogonal Frequency Division Multiplexing ◽  
Rayleigh Fading ◽  
Code Rate ◽  
Rayleigh Fading Channels ◽  
Bandwidth Efficiency ◽  
Frequency Division ◽  
Frequency Allocation ◽  
Study Program ◽  
Bpsk Modulation

The application of OFDM technology is still not fully implemented in the Telecommunication Study Program at State Polytechnic of Malang. This is because the application of this technology is applied to hardware. However, this can be overcome by simulating the OFDM technology through software. From the application of the system into the program by entering the predetermined parameters, the BER value can be compared to the predetermined parameters. Bit error that appears in the application of the OFDM Multi user system for bit error in BPSK Modulation with AWGN and Rayleigh Fading channels appears bit error respectively with an average of 9 bits and 14 bits at 11 dB SNR. Whereas in the QPSK modulation with AWGN and Rayleigh Fading channels, each bit error appears with an average of 13 bits and 18 bits on the SNR of 14 dB. Furthermore, in the calculation of bandwidth efficiency in the frequency allocation of 20 MHz for BPSK modulation, three values ??of bandwidth efficiency are obtained, among others, 1 bps / Hz in theory for practical, namely the code rate ½ is 0.3 bps / Hz and the code rate ¾ is 0.45 bps / Hz. While the QPSK modulation also obtained three values ??of bandwidth efficiency, namely, 2 bps / Hz in theory for practical, namely the code rate ½ is 0.6 bps / Hz and the code rate ¾ is 0.9 bps / Hz.

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.

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