scholarly journals Analysis of Intercarrier Interference Cancellation Scheme in OFDM Systems

2012 ◽  
Vol 1 (1) ◽  
pp. 13-23
Author(s):  
Nasir Salh Almisbah ◽  
Elessaid S Saad
Keyword(s):  
Interference Cancellation ◽  
Orthogonal Frequency Division Multiplexing ◽  
Modulation Scheme ◽  
Intercarrier Interference ◽  
Frequency Division ◽  
Ofdm Systems ◽  
Ieee 802.11A ◽  
Wireless Standards ◽  
Carrier To Interference Ratio ◽  
Subcarrier Frequency

Abstract: Orthogonal Frequency Division Multiplexing (OFDM) is an emerging multi-carrier modulation scheme, which has been adopted for several wireless standards such as IEEE 802.11a and HiperLAN2. In OFDM systems, the performance is very sensitive to subcarrier frequency errors (offset). This paper shows the analysis and derivations of intercarrier interference (ICI) complex gain that used in self-cancellation scheme and its dependence on subcarrier frequency offset. Simulation shows that better improvement in performance is achieved for systems that use this cancellation scheme. Moreover, analysis and simulation show that theoretical carrier-to-interference ratio (CIR) for OFDM with cancellation scheme is greater than conventional one by more than 14dB.DOI: 10.18495/comengapp.11.013023

scholarly journals Performance on ICI Self-Cancellation in FFT-OFDM and DCT-OFDM System

2015 ◽  
Vol 2015 ◽  
pp. 1-7
Author(s):  
Shilpi Gupta ◽  
Upena Dalal ◽  
Vishnu Narayan Mishra
Keyword(s):  
Bit Error Rate ◽  
Orthogonal Frequency Division Multiplexing ◽  
The Other ◽  
Frequency Division Multiplexing ◽  
Intercarrier Interference ◽  
Frequency Division ◽  
Ofdm System ◽  
Awgn Channel ◽  
Energy Compaction ◽  
Carrier To Interference Ratio

In orthogonal frequency division multiplexing (OFDM) system, the existence of frequency offset in AWGN channel affects the orthogonality among the subcarriers and consequently introduces the intercarrier interference (ICI). The paper investigates new ICI self-cancellation technique to mitigate the effect of ICI in FFT-OFDM and compares it to DCT based OFDM system in terms of bit error rate (BER) and carrier to interference ratio (CIR). The proposed method for group size three results in a significant 20 dB improved CIR in FFT-OFDM. In terms of BER, proposed ICI self-cancellation technique outperforms the other self-cancellation techniques in FFT-OFDM. Also, this paper investigates outperforming BER and CIR improvement by using DCT-OFDM without applying self-cancellation techniques, due to its energy compaction property.

scholarly journals Comparison of SPS and FA methods for Blind Carrier Frequency Offset Estimation in OFDM systems

2022 ◽  
Vol 16 ◽  
pp. 7-11
Author(s):  
K. Seshadri Sastry ◽  
K. Baburao ◽  
A.V. Prabu ◽  
G.Naveen Kumar
Keyword(s):  
Carrier Frequency ◽  
Orthogonal Frequency Division Multiplexing ◽  
Carrier Frequency Offset ◽  
Frequency Offset ◽  
Intercarrier Interference ◽  
Frequency Division ◽  
Ofdm Systems ◽  
Frequency Offset Estimation ◽  
Synchronization Errors ◽  
Carrier Frequency Offset Estimation

In orthogonal frequency-division multiplexing (OFDM) systems, synchronization issues are of great importance since synchronization errors might destroy the orthogonality among all subcarriers and, therefore, introduce intercarrier interference (ICI) and intersymbol interference (ISI). Several schemes of frequency offset estimation in OFDM systems have been investigated. This paper compares performance and computational complexity of Smoothing Power Spectrum (SPS) and Frequency Analysis (FA) methods for blind carrier frequency offset (CFO) estimation in OFDM systems.

scholarly journals Spatial Diversity Scheme to Efficiently Cancel ISI and ICI in OFDM-OQAM Systems

2010 ◽  
Vol 2010 ◽  
pp. 1-10 ◽  
Author(s):  
Nizar Zorba ◽  
Faouzi Bader
Keyword(s):  
Orthogonal Frequency Division Multiplexing ◽  
Spatial Diversity ◽  
Cyclic Prefix ◽  
Closed Form Expression ◽  
Intercarrier Interference ◽  
Frequency Division ◽  
Ofdm Systems ◽  
Transmission Scheme ◽  
Form Expression ◽  
Channel Characteristics

This paper is based on an Offset Quadrature Amplitude Modulation (OQAM) Orthogonal Frequency Division Multiplexing (OFDM) transmission scheme that is operated without a Cyclic Prefix (CP), where the multiple transmitting antennas are employed to substantially reduce the inherent intersymbol and intercarrier interference. The proposed scheme avoids the use of the CDMA technology to get rid of the interference. The nonemployment of the CP increases the spectral efficiency in comparison with classical CP-OFDM systems, as it does not employ the CP for its correct performance. On the other hand, the non-employment of the CP comes at cost of Intersymbol Interference (ISI). This paper presents a method which cancels the interference terms by employing a multiantenna precoding strategy based on spatial diversity OQAM-OFDM scheme, so that the overall system can get the advantage of the CP removal while no ISI is generated. Moreover, the proposed system benefits from the multiuser gain through an opportunistic scheduler at the transmitter side to select the user with the best channel characteristics at each instant. The resultant scheme OQAM-OFDM-MIMO data rate is obtained in a closed form expression and proved to be higher than the classical CP-OFDM systems.

scholarly journals Wiener-based ICI cancellation schemes for OFDM systems over fading channels

2013 ◽  
Vol 10 (2) ◽  
pp. 877-896 ◽  
Author(s):  
Jyh-Horng Wen ◽  
Yung-Cheng Yao ◽  
Ying-Chih Kuo
Keyword(s):  
Fading Channels ◽  
Interference Cancellation ◽  
Orthogonal Frequency Division Multiplexing ◽  
Intercarrier Interference ◽  
Ofdm Systems ◽  
Computation Complexity ◽  
Zero Forcing ◽  
Ofdm Signals ◽  
Ici Cancellation ◽  
Better Than

The subcarriers of orthogonal frequency division multiplexing (OFDM) systems may fail to keep orthogonal to each other under timevarying channels. The loss of orthogonality among the subcarriers will degrade the system performace, and this effect is named intercarrier interference (ICI). In this paper, a Wiener-based successive interference cancellation (SIC) scheme is proposed to detect the OFDM signals. It provides good ICI cancellation performance; however, it suffers large computation complexity. Therefore, a modified Wienerbased SIC scheme is further proposed to reduce the computation complexity. Simulation results show the performance of the Wienerbased SIC scheme is better than those of zero forcing, zero forcing plus SIC and original Wiener-based schemes. Furthermore, with the modified Wiener-based SIC scheme, the performance is still better than the others. Although the performace of the modified Wiener-based SIC scheme suffers little degradation compared to Wiener-based SIC scheme, the computation complexity can be dramatically reduced.

scholarly journals Channel Estimation Techniques for OFDM and UFMC Systems for 5G Communications

2019 ◽  
Vol 8 (2S8) ◽  
pp. 1776-1778
Keyword(s):  
Channel Estimation ◽  
Communication Systems ◽  
Orthogonal Frequency Division Multiplexing ◽  
Wireless Communication Systems ◽  
Modulation Scheme ◽  
Frequency Division ◽  
Ofdm Systems ◽  
Machine Type ◽  
Machine Type Communications ◽  
Simulation Results

In this paper, pilot-assisted techniques for channel estimation (CE) are simulated for Universal Filtered Multi-Carrier (UFMC) modulation scheme. UFMC aims at replacing orthogonal frequency division multiplexing (OFDM) and improves performance and robustness in the case of timefrequency misalignment. These techniques efficiently support Internet of Things (IoT) and massive machine type communications (mMTC), which are identified as challenges for 5G wireless communication systems (WCS). Pilot-aided techniques are adopted and applied to OFDM and UFMC. Simulation results are supplemented to compare the performance of UFMC systems with conventional CP-OFDM systems.

scholarly journals Partial ML Detection for Frequency-Asynchronous Distributed Alamouti-Coded (FADAC) OFDM

2019 ◽  
Vol 2019 ◽  
pp. 1-10
Author(s):  
Bong-seok Kim ◽  
Dongjun Na ◽  
Kwonhue Choi
Keyword(s):  
Interference Cancellation ◽  
Orthogonal Frequency Division Multiplexing ◽  
Intercarrier Interference ◽  
Frequency Division ◽  
Maximum Likelihood Detection ◽  
Set Size ◽  
Decision Variables ◽  
Free Level ◽  
Frequency Offsets ◽  
Ml Detection

To further enhance frequency-asynchronous distributed Alamouti-coded (FADAC) orthogonal frequency division multiplexing (OFDM), we propose a new scheme which combines the partial maximum likelihood detection (PMLD) to the residual intercarrier interference cancellation (RIC). In order to decrease the performance gap from intercarrier interference- (ICI-) free level after single time iteration of the RIC, the final stage of the proposed scheme performs the PMLD limited to the symbols of less-reliable decision variables. We show that with the practically acceptable candidate symbol set size, a single iteration for RIC is enough to achieve the ICI-free performance. Moreover, the proposed scheme substantially expands the allowable ranges of the three undesirable terms, i.e., the timing and frequency offsets between the transmit antennas and the multipath delay spreads.

scholarly journals PAPR Reduction of OFDM System with Biorthoganoal Wavelet Transforms

2021 ◽  
pp. 17-22
Author(s):  
Palle Jagadeeswara Rao and Dr. A S Srinivasa Rao
Keyword(s):  
Wavelet Transform ◽  
Wavelet Transforms ◽  
Orthogonal Frequency Division Multiplexing ◽  
Spectrum Efficiency ◽  
Frequency Division Multiplexing ◽  
Intercarrier Interference ◽  
Frequency Division ◽  
Ofdm Systems ◽  
Ofdm System ◽  
Available Bandwidth

Orthogonal Frequency Division Multiplexing (OFDM) and Multiple Input and Multiple Output (MIMO) are two main techniques employed in 4th Generation Long Term Evolution (LTE). In OFDM multiple carriers are used and it provides higher level of spectral efficiency as compared to Frequency Division Multiplexing (FDM). In OFDM because of loss of orthogonality between the subcarriers there is intercarrier interference (ICI) and intersymbol interference (ISI) and to overcome this problem use of cyclic prefixing (CP) is required, which uses 20% of available bandwidth. Wavelet based OFDM provides good orthogonality and with its use Bit Error Rate (BER) is improved. Wavelet based system does not require cyclic prefix, so spectrum efficiency is increased. It is proposed to use wavelet transform including biorthoganoal wavelet transform with OFDM systems. This approach will reduce PAPR in the OFDM system effectively. We will design this model with different modulation Techniques like QPSK and QAM and compare the BER results.

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