On the performance of joint low‐complexity equalization and CFO compensation for SISO‐OFDM communication systems with chaotic interleaving and DCT

Abstract

The implementation of the Orthogonal Frequency Division Multiplexing (OFDM) can be achieved using Inverse Discrete Cosine Transform (IDCT), and DCT instead of Inverse Discrete Fourier Transform (IDFT), and DFT. The Carrier Frequency Offset (CFO) is the main issue of the OFDM system. One of the tools to mitigate the CFO effect and improve the Bit-Error-Rate (BER) performance is the equalization procedure. Also, the 1-Dimension (1-D), and 2-Dimension (2-D) burst errors can be mitigated using a chaotic interleaver in the OFDM system. This consequently improves the BER performance. In this paper, we propose a Joint Low-Complexity Regularized Linear Zero Forcing (JLCRLZF) equalizer for the OFDM system based on DCT in addition to a chaotic interleaving scheme. The proposed equalizer depends on the concept of the banded-matrix approximation, and jointly performs the equalization and CFO compensation processes. Simulation results ensure the importance of the proposed JLCRLZF equalizer compared to other algorithms.

Low‐complexity joint equalization and CFO compensation in uplink SC‐FDMA NOMA system under different power allocation strategies

“…Moreover, in SC-FDMA NOMA the normalized interference between the subcarriers has less significant effect on the neighboring subcarriers when the subcarrier distance increases. 30 This indicates that adjacent subcarriers only contribute to the interference on desired subcarrier, while the interference becomes negligible with increase in subcarrier distance (k − p). Hence, a design parameter 𝜏 can be introduced to play a significant role in reducing the complexity of equalization techniques.…”

“…In the simulations, we consider 𝜏 = 20 as a best choice to preserve the BER performance at lower complexity. 30 In Figure 7, it can be perceived that the performance of proposed JLRZF DCT SC-FDMA NOMA loses about 2 dB gain compared to MMSE DCT SC-FDMA NOMA system at BER of 10 −4 . However, the loss in SNR is very high for ZF and JLZF based equalization schemes compared to JRZF.…”

“…In SC‐FDMA NOMA, LRZF offers better performance with lower complexity compared to LMMSE. Moreover, in SC‐FDMA NOMA the normalized interference between the subcarriers has less significant effect on the neighboring subcarriers when the subcarrier distance increases 30 . This indicates that adjacent subcarriers only contribute to the interference on desired subcarrier, while the interference becomes negligible with increase in subcarrier distance $$$ \left(k-p\right) $$$.…”

“…The banded matrix bandwidth $$$ \tau $$$ represents the value of banded bandwidth required to achieve better BER performance with reduced complexity. In the simulations, we consider $$$ \tau =20 $$$ as a best choice to preserve the BER performance at lower complexity 30 . In Figure 7, it can be perceived that the performance of proposed JLRZF DCT SC‐FDMA NOMA loses about 2 dB gain compared to MMSE DCT SC‐FDMA NOMA system at BER of 10 −4 .…”