Analysis of Intercarrier Interference Cancellation Scheme in OFDM Systems (original) (raw)
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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. A well-known problem of OFDM is its sensitivity to frequency offset between the transmitted and received carrier frequencies. This frequency offset introduces inter-carrier interference (ICI) in the OFDM symbol. This project investigates three methods for combating the effects of ICI: ICI self-cancellation (SC), maximum likelihood (ML) estimation, and extended Kalman filter (EKF) method. These three methods are compared in terms of bit error rate performance, bandwidth efficiency, and computational complexity. Through simulations, it is shown that the three techniques are effective in mitigating the effects of ICI. For high values of the frequency offset and for higher order modulation schemes, the ML and EKF methods perform better than the SC method.
Intercarrier Interference Self-Cancellation Scheme for OFDM Mobile Communication Systems
IEEE Transactions on Communications, 2001
For orthogonal frequency-division multiplexing (OFDM) communication systems, the frequency offsets in mobile radio channels distort the orthogonality between subcarriers resulting in intercarrier interference (ICI). This paper studies an efficient ICI cancellation method termed ICI self-cancellation scheme. The scheme works in two very simple steps. At the transmitter side, one data symbol is modulated onto a group of adjacent subcarriers with a group of weighting coefficients. The weighting coefficients are designed so that the ICI caused by the channel frequency errors can be minimized. At the receiver side, by linearly combining the received signals on these subcarriers with proposed coefficients, the residual ICI contained in the received signals can then be further reduced. The carrier-to-interference power ratio (CIR) can be increased by 15 and 30 dB when the group size is two or three, respectively, for a channel with a constant frequency offset. Although the redundant modulation causes a reduction in bandwidth efficiency, it can be compensated, for example, by using larger signal alphabet sizes. Simulations show that OFDM systems using the proposed ICI self-cancellation scheme perform much better than standard systems while having the same bandwidth efficiency in multipath mobile radio channels with large Doppler frequencies.
Inter Carrier Interference (ICI) Cancellation in OFDM Systems: A Review
In the area of wireless communications, the demand for high data rate transmission is rapidly increasing. Orthogonal frequency division multiplexing (OFDM) is known to be a promising technique for high-rate transmission that can overcome the inter symbol interference (ISI) which results from the time dispersive nature of wireless channels. For OFDM communication systems the orthogonality is lost among the sub-carriers due to frequency offset which results in Inter carrier Interference (ICI). This ICI rapidly degrades the performance of OFDM system. We have so many ICI cancellation methods like time windowing and frequency equalization to improve the BER performance of OFDM systems. In this an efficient ICI cancellation methods termed ICI self-cancellation (SC) scheme, extended Kalman filter (EKF) method and another ICI cancellation scheme, named Total ICI Cancellation scheme are proposed. However the total ICI cancellation scheme has does not lower the transmission rate or reduce the bandwidth efficiency. It is shown that for high values of the frequency offset and for higher order modulation schemes, the EKF method perform better than the SC method. Keywords—Orthogonal frequency divison multiplexing (OFDM) Inter carrier interference(ICI), self cancellation (SC),Extended Kalman filtering (EKF) .
Design And Implementation Of Ofdm System And Reduction Of Inter Carrier Interference
Orthogonal frequency-division multiplexing (OFDM) [1] is a method of encoding digital data on multiple carrier frequencies. OFDM[1] has developed into a popular scheme for wideband digital communication, whether wireless or over copper wires, used in applications such as digital television and audio broadcasting, DSL Internet access, wireless networks, powerline networks, and 4G mobile communications. In the Several wireless standards such as IEEE 802.11a[2] and HiperLAN2[3].The orthogonality of the subcarriers is no longer maintained which results in ICI (Inter carrier Interference)[4]
INTER-CARRIER INTERFERENCE REDUCTION TECHNIQUE IN OFDM SYSTEM BASED ON SELF CANCELLATION TECHNIQUE
Orthogonal frequency division multiplexing (OFDM) is considered as a one of the best modulation schemes in wireless communications. However, OFDM suffers from the sensitivity to frequency offset. This frequency offset introduces the problem of inter-carrier interference (ICI) in OFDM system. This paper presents a new self cancellation technique (modified self cancellation technique) using the self cancellation technique with zero -gab. In proposed technique a zero sub-carriers carries are used in order to mitigate the interference occurred by the main -lobe of the two adjacent sub-carriers, in addition to zeros sub-carrier, the proposed technique used self-cancellation in order to mitigate the effect of the side-lobes of other sub-carriers. In terms of carrier-to-interference ratio (CIR) and bit-error rate (BER) the modified self cancellation technique gives good results compared to that using only the conventional self cancellation technique. U IntroductionU :
BER Analysis of ICI Self-Cancellation Schemes for OFDM based Wireless Systems
IJPTT
— the consistently rising demand for very high rate data transmission over wireless mediums requires ingenious usage of electromagnetic resources considering constraints like power consumption, spectrum efficiency, robustness against multipath propagation and implementation complexity. Orthogonal frequency division multiplexing (OFDM) is a propitious technique for next generation wireless communication systems. Nevertheless it suffers from Inter-Carrier Interference (ICI) due to its susceptibility to the frequency offset caused by frequency difference between local oscillator of transmitter and receiver or due to Doppler shift. This paper epitomize self-cancellation techniques to mitigate ICI effect for OFDM based wireless systems. The performances of ICI self-cancellation schemes have been in terms of the bit error rate (BER). Simulation results exhibit ICI self-cancellation Scheme that outperforms other existing self-cancellation methods and robustness to large frequency offset.
Intercarrier Interference Immune OFDM System
In Today's world OFDM plays very important role for wireless communication systems.OFDM has overlapping subcarrier spectrum due to this overlapping spectrum OFDM has very high spectral efficiency. OFDM is also known as Multicarrier modulation technique and this OFDM system is very sensitive to carrier frequency offset, which cause loss of Orthogonality and amplitude reduction of OFDM signal and lead to Inter Carrier Interference(ICI) ,which is one of the major weakness of OFDM system. Existing techniques for OFDM can be directly adopted in SC-OFDM to improve performance however, this improved performance comes at costs such as decreased throughput. We have analyzed the effect of ICI on an SC-OFDM system. This system is immune to ICI and it outperforms OFDM, SC-OFDM systems with Phase Shift Keying modulation and quadrature Amplitude Modulation.
Intersymbol and Intercarrier Interference in OFDM Systems: Unified Formulation and Analysis
arXiv (Cornell University), 2020
A unified matrix formulation is presented for the analysis of intersymbol and intercarrier interference in orthogonal frequency-division multiplexing (OFDM) systems. The proposed formulation relies on six parameters and allows studying various schemes, including those with windowing in the transmitter and/or in the receiver (called windowed OFDM systems), which may add cyclic suffix and/or cyclic prefix (CP), besides the conventional CP-OFDM. The proposed framework encompasses seven different OFDM systems. It considers the overlap-and-add procedure performed in the transmitter of windowed OFDM systems, being jointly formulated with the channel convolution. The intersymbol and intercarrier interference, caused when the order of the channel impulse response is higher than the number of CP samples, is characterized. A new equivalent channel matrix that is useful for calculating both the received signal and the interference power is defined and characterized. Unlike previous works, this new channel matrix has no restrictions on the length of the channel impulse response, which means that the study is not constrained to the particular case of two or three data blocks interfering in the received signal. Theoretical expressions for the powers of three different kinds of interference are derived. These expressions allow calculating the signal-to-interference-plus-noise ratio, useful for computing the data rate of each OFDM system. The proposed formulation is applied to realistic examples, showing its effectiveness through comparisons based on numerical performance assessments of the considered OFDM systems.
New ICI Self Cancellation Scheme for OFDM Systems
International Journal of Computer and Communication Engineering, 2014
Orthogonal Frequency Division Multiplexing (OFDM) is sensitive to Carrier Frequency Offset (CFO), which in turn causes Intercarrier Interference (ICI) and degrades system performance. During the last decade, several ICI self cancellation schemes were proposed in the literature. This paper introduces a new ICI self-cancellation scheme with an improved immunity against CFO errors as evidenced by Carrier to Interference Ratio (CIR) and Bit Error Rate (BER) analyses. Index Terms-Carrier frequency offset (CFO), self cancellation (SC), intercarrier interference (ICI), CIR (carrier to interference ratio), OFDM (orthogonal frequency-division multiplexing).
ICI Cancellation in OFDM Systems by Frequency Offset Reduction
Applied Mechanics and Materials, 2014
The rapid growth within the field of digital communication during the recent years expanded the need for high-speed data transmission to support a wide range of services such as: video, data and voice in wireless communication systems, etc. Orthogonal frequency division multiplexing (OFDM) and a multicarrier modulation scheme are employed to achieve the high data rates. Since OFDM is very much sensitive to carrier frequency offsets, which cause the Inter-carrier Interference (ICI) leads to mitigation of this ICI is necessary. The objectives of this paper are to, proposed an efficient ICI self-cancellation scheme to mitigate the effect of ICI on OFDM systems. For this purpose, a redundant data is transmitted onto adjacent sub-carriers such that the ICI between adjacent sub-carriers cancels out at the receiver side. One data symbol is modulated into a group of adjacent sub carriers with a group of weighting coefficients. At the receiver side, the received signals are linearly combined...