Journal articles: 'Inter-symbol Interference (ISI)'

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Kim, Kyung Ki. "Modeling and analysis of inter-symbol interference (ISI) jitter." IEICE Electronics Express 4, no. 19 (2007): 582–87. http://dx.doi.org/10.1587/elex.4.582.

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Bakkar, Mohammad. "Inner-symbol Interference (INSI) reduction in OFDM system using distinctive characteristics of the pilot symbols." Association of Arab Universities Journal of Engineering Sciences 27, no. 1 (March 31, 2020): 122–29. http://dx.doi.org/10.33261/jaaru.2019.27.1.013.

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This research presents a wireless communication system using Quadrature Amplitude Modulation (16QAM) depending on using of the Orthogonal Frequency Division Multiplexing (OFDM). OFDM transmission system can effectively reduce inter symbol interference (ISI) caused by multipath fading, especially in the case of broadband data transmission. There are two kind of interference; inter symbol interference (ITSI) and inner symbol interference (INSI). ITSI is the interference caused by the delayed waves with larger than OFDM symbol duration, in order to avoid ITSI effectively, we insert guard interval every each OFDM symbol. On other hands, INSI is the interference caused by the delayed waves with less than OFDM symbol duration. To avoid INSI, this work proposes a new scheme in order to estimate the times of delayed waves by using distinctive characteristics of OFDM signal, which is inserted pilot signal periodically in frequency axis before IFFT at the transmitter. In this paper, we evaluate the estimation accuracy of the proposed estimation method and the BER performance of the proposed system under multipath fading environment by computer simulation with MATLAB.

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Yang, Jieying. "Orthogonal frequency division multiplexing technology based on MATLAB." Applied and Computational Engineering 6, no. 1 (June 14, 2023): 351–58. http://dx.doi.org/10.54254/2755-2721/6/20230807.

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The subcarriers of an orthogonal frequency division multiplexing (OFDM) system are not identical in the time domain, and their spectra also overlap. As a result, the spectrum is being used effectively. Its effective use of frequency resources and capacity to combat channel fading have made it the de facto technical standard. In wireless communication, numerous pathways in the channel can lead to interference between symbols, known as inter-symbol interference (ISI). This research supplements OFDM systems with some safeguards to eliminate inter-symbol interference. Most traditionally, OFDM symbols have had their post-event sample points duplicated to their beginnings, a process known as Cyclic prefix (CP) padding in the protection interval. In order to further counteract ISI, a protection interval might be added to the beginning of each symbol. An OFDM system's bit error rate (BER) can be decreased by using cyclic prefixes to attenuate inter-code interference. This study explains how OFDM and CP-OFDM work and compares their performance. The primary topic of this study is a contrast between OFDM and CP-OFDM concerning the performance metrics of average symbol error rate (BER) and signal spectrum diagram (PSD).

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Nguyen, Viet-Hung, Minh-Tuan Nguyen, and Yong-Hwa Kim. "Deep neural network for orthogonal frequency division multiplexing systems without cyclic prefix transmission." MATEC Web of Conferences 189 (2018): 04016. http://dx.doi.org/10.1051/matecconf/201818904016.

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Orthogonal frequency division multiplexing (OFDM) is widely used in wired or wireless transmission systems. In the structure of OFDM, a cycle prefix (CP) has been exploited to avoid the effects of inter-symbol interference (ISI) and inter-carrier interference (ICI). This paper proposes a new approach to transmit the signals without CP transmission. Using the deep neural network, the proposed OFDM system transmits data without the CP. Simulation results show that the proposed scheme can estimate the CP at the receiver and overcome the effect of ISI.

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Wu, Zhuang, Xiao Xin Ma, and Lan Zhang. "Anti-Jamming Ability Research on COFDM Modulation of UAV Image Transmission." Advanced Materials Research 1079-1080 (December 2014): 614–17. http://dx.doi.org/10.4028/www.scientific.net/amr.1079-1080.614.

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Thefrequency offset and phase noise will make the orthogonal property between eachsub carrier deterioration. Only1% frequency offset will cause 30dB signal-to-noise ratio decrease. In order to researchanti-jamming ability on COFDM modulation, we use the PXW-100S type codedmodulation module and the PXW-500S type DVB-T receiving board for unmannedaerial vehicle(UAV) platform, through the elimination of inter symbol interference(ISI) and inter carrier interference(ICI).

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Wang, Feng, and Xuan De Ji. "A Joint Chip Equalization Adaptive Rake Receiver for DS-CDMA UWB Systems over ISI Channels." Advanced Materials Research 505 (April 2012): 274–81. http://dx.doi.org/10.4028/www.scientific.net/amr.505.274.

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There is serious inter-symbol interference (ISI) when ultra-wideband (UWB) wireless communication systems work at high data speed since there is much larger channel delay spread. The serious ISI becomes a major factor that affects the performance of UWB systems. In this paper, suppression ISI is developed for direct sequence spread-code division multiple access (DS-CDMA) UWB systems with a high data speed, and a joint chip equalization adaptive Rake (JCE-Rake) receiver is proposed. The proposed JCE-Rake receiver spreads the number of traditional Rake receiver taps to collect multi-path component and equalize the inter-chip interference simultaneously. Then the soft output of JCE-Rake receiver is despreaded with the user's spreading code. Finally the decision is made to recover the transmitted symbol. The simulation results verify that ISI is suppressed effectively and the system performance is improved evidently.

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Sun, Zeng You, and Fan Ming Zeng. "Optimization and Simulation of OFDM System Based on Orthogonal Wavelet." Applied Mechanics and Materials 548-549 (April 2014): 1221–26. http://dx.doi.org/10.4028/www.scientific.net/amm.548-549.1221.

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In order to reduce the Orthogonal Frequency division Multiplexing (OFDM) Inter-Carrier Interference (ICI), Put forward a kind of modulation method that based on the orthogonal frequency division multiplexing of orthogonal wavelet, Using orthogonal wavelet instead of discrete Fourier transform, optimize the design for OFDM systems, on the premise of without protection interval to reduce the system interference, using MATLAB to simulate the OFDM system, results show that the optimization of the OFDM can reduce the power of the ICI and Inter-symbol Interference (ISI) and improve the comprehensive anti-jamming of the OFDM system.

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Sakaue, Taichi, Chang-Jun Ahn, Tatsuya Omori, and Ken-Ya Hashimoto. "Time Domain Replica Signal Based Interference Compensation for SP-MIMO/OFDM with Large Delay Spread Channel." International Journal of Distributed Systems and Technologies 5, no. 4 (October 2014): 1–17. http://dx.doi.org/10.4018/ijdst.2014100101.

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In mobile communications, MIMO-OFDM transmission performance suffers severe degradation caused by the large delay spread channel greater than guard interval (GI). This is because the excess delay results in considerable inter-symbol interference (ISI) between adjacent symbols and inter-carrier-interference (ICI) among subcarrier in the same symbol. In case of scattered pilot (SP), the interference of pilot signals causes the deterioration of channel estimation. To mitigate this problem, in this paper, we propose the interference compensation scheme using the time domain replica signals. We make the time domain replica signals from detected signals and the excess channel impulse responses over GI. After compensation of the time domain replica signals and the received signals, we recalculate the channel state information (CSI) and the CSI is updated. Finally, we carry out the channel compensation with updated CSI for obtaining accurate compensated signals.

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Peng, Yaqiu, and Mingqi Li. "Discrete Fourier Transform-Based Block Faster-Than- Nyquist Transmission for 5G Wireless Communications." Applied Sciences 10, no. 4 (February 14, 2020): 1313. http://dx.doi.org/10.3390/app10041313.

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Faster-than-Nyquist (FTN) signaling is regarded as a potential candidate for improving data rate and spectral efficiency of 5G new radio (NR). However, complex detectors have to be utilized to eliminate the inter symbol interference (ISI) introduced by time-domain packing and the inter carrier interference (ICI) introduced by frequency-domain packing. Thus, the exploration of low complexity transceiver schemes and detectors is of great importance. In this paper, we consider a discrete Fourier transform (DFT) block transmission for multi-carrier FTN signaling, i.e., DBT-MC-FTN. With the aid of DFTs/IDFTs and frequency domain windowing, time- and frequency domain packing can be implemented flexibly and efficiently. At the receiver, the inherent ISI and ICI can be canceled via a soft successive interference cancellation (SIC) detector. The effectiveness of the detector is verified by the simulation over the additive white Gaussian noise channel and the fading channel. Furthermore, based on the characteristics of the efficient architecture of DFT-MC-FTN, two pilot-aided channel estimation schemes, i.e., time-division-multiplexing DBT-MC-FTN symbol-level pilot, and frequency-division-multiplexing subcarrier-level pilot within the DBT-MC-FTN symbol, respectively, are also derived. Numerical results show that the proposed channel estimation schemes can achieve high channel estimation accuracy.

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Isnawati, Anggun Fitrian, Riyanto Riyanto, and Ajeng Enggar Wijayanti. "Pengaruh Dispersi Terhadap Kecepatan Data Komunikasi Optik Menggunakan Pengkodean Return To Zero (RZ) Dan Non Return To Zero (NRZ)." JURNAL INFOTEL - Informatika Telekomunikasi Elektronika 1, no. 2 (November 10, 2009): 1. http://dx.doi.org/10.20895/infotel.v1i2.65.

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Fiber optic has characteristics for optical transmission system. One of optical characteristics is pulse broadening, known as dispersion. The dispersion is a condition where pulse in output side is larger than pulse in input side. It means that pulse broadening had happened. In the communication system, it’s known as inter symbol interference (ISI). Effect of Inter symbol interference increasing the error bit or BER value. In optical communication system, dispersion is most influence to the data rate that fiber can support. Besides, bandwidth, information capacity, transmission distance, wavelength and fiber type can also influenced by the dispersion.

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Myint, Lin Min Min, and Chanon Warisarn. "Equalizer Design for Bit-Patterned Media Recording System Based on ISI and ITI Estimations by Cross Correlation Functions." Applied Mechanics and Materials 781 (August 2015): 223–26. http://dx.doi.org/10.4028/www.scientific.net/amm.781.223.

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Due to ultra-high density, a bit-patterned media recording (BPMR) system experiences two-dimensional (2D) interference--inter-symbol interference (ISI) and inter-track interference (ITI)--which degrades the overall performance of a recording systems. Therefore, we propose a novel single-track equalization and a single track detection that can perform these duties almost equally well. Our novel equalizer design uses ISI and ITI estimation schemes with the help of cross-correlation functions. The simulation result shows that our proposed method is able to achieve a significant performance gain over the one-dimensional (1D) equalization method and the conventional joint-track equalization, especially at higher recording density.

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Sun, Yan Dong, Tong Liang Fan, and Sheng Bo Huang. "Comparative Study on Zero Forcing Block Linear Equalization for TD-SCDMA." Applied Mechanics and Materials 590 (June 2014): 710–15. http://dx.doi.org/10.4028/www.scientific.net/amm.590.710.

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3G standards such as TD-SCDMA use multi-user detection (MUD) at the base station to combat multi address interference (MAI) and inter-symbol interference (ISI). We review Cholesky factorization and Schur algorithm for Zero Forcing Block Linear Equalization. We compare the solutions of different algorithm for ZF-BLE by computation, and analyze the complexity of those methods.

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Nguyen, Thien An, and Jaejin Lee. "Two-Dimensional Interference Estimator with Parallel Structure for Holographic Data Storage Channel." Applied Sciences 12, no. 4 (February 17, 2022): 2112. http://dx.doi.org/10.3390/app12042112.

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Recently, holographic data storage (HDS) has attracted significant attention as the next-generation storage technology because of its large capacity and high-speed transfer capabilities. However, two-dimensional (2D) inter-symbol interference (ISI) is a critical problem encountered in HDS. Therefore, in this study, we propose a 2D interference estimator to prevent the 2D ISI. In addition, we propose a parallel structure to exploit horizontal interference (HI) and vertical interference (VI) effectively. After detecting the HI and VI, the signal is combined using an average function. The simulation results indicate that the proposed model can significantly improve the performance of HDS.

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Djuric, Nikola. "In-track iterative decoding for two-track partial response magnetic recording channels." Facta universitatis - series: Electronics and Energetics 17, no. 3 (2004): 343–52. http://dx.doi.org/10.2298/fuee0403343d.

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The article analyses performance of in-track iterative decoding over a Two track recording system with a one-head and a two-head detector. A two-track system is modeled as a partial response of in-track inter symbol interference (ISI) channel with linear symmetrical inter track interference (ITI). It is presented the bit error rate performance of in-track low-density parity-check codes, used with various ideal partial response equalization targets (Dicode, PR4, EPR4, E2PR4 and ME2PR4), over two-track magnetic recording system.

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Harbi, Yahya, ALI AL-JANABI, Hayder Almusa, Marwa Chafii, and Alister Burr. "Iterative Interference Cancellation for Multi-Carrier Modulation in MIMO-DWT Downlink Transmission." Journal of Telecommunications and the Digital Economy 9, no. 4 (December 5, 2021): 75–87. http://dx.doi.org/10.18080/jtde.v9n4.426.

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The Multiple-Input Multiple-Output Orthogonal Frequency Division Multiplexing (MIMO-OFDM) scheme represents the dominant radio interface for broadband multicarrier communication systems. However, with insufficient Cyclic Prefixes (CP), Inter-Symbol Interference (ISI) and Inter-Carrier Interference (ICI) occur due to the time-varying multipath channel. This means that the performance of the system will be degraded. In this paper, we investigate the interference problem for a MIMO Discrete Wavelet Transform (MIMO-DWT) system under the effect of the downlink LTE channel. A Low-Density Parity-Check (LDPC) decoder is used to estimate the decoded signal. The proposed iterative algorithm uses the estimated decoded signal to compute the components required for ICI/ISI interference reduction. In this paper, Iterative Interference Cancellation (IIC) is employed to mitigate the effects of interference that contaminates the received signal due to multiple antenna transmission and a multipath channel. An equalizer with minimum mean square error is considered. We compare the performance of our proposed algorithm with the traditional MIMO-OFDM scheme in terms of bit error probability under insufficient CP. Simulation results verify that significant improvements are achieved by using IIC and MIMO-IIC for both systems.

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Dang, Khoa Le, An Truong Nguyen, Phu Huu Bui, and Phuong Huu Nguyen. "IMPLEMENTING AN OFDM SYSTEM ON HARDWARE." Science and Technology Development Journal 12, no. 12 (June 28, 2009): 73–85. http://dx.doi.org/10.32508/stdj.v12i12.2322.

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Recently, OFDM technique has been applied to many digital communications systems such as DVB-T, WiFi, WiMAX and MIMO systems. OFDM can send multiple high speed signals by using orthogonal carrier frequencies. In addition, OFDM technique can combat inter-symbol interference (ISI) and inter-channel interference (ICI). Therefore, OFL has been an essential technology in high-speed communications. The aim of this project is to implement the base-band OFDM system on hardware exploiting FPGA-based DSP Development Kit and DSPBuilder® software from Altera®. The results can be used for training purpose and for a further development of OFDM-based communication systems.

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Wang, Jia Jia, Cheng Mei Li, Bin Li, Hao Chang, and Jian Jun Wu. "Joint Selection of OFDM Parameters in Mobile Satellite Communications." Applied Mechanics and Materials 385-386 (August 2013): 1586–90. http://dx.doi.org/10.4028/www.scientific.net/amm.385-386.1586.

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In mobile satellite communication based on OFDM technology, the system performance can’t be optimal if the cyclic prefix (CP) length and subcarrier interval of LTE specification are transplanted into mobile satellite communication directly. In this paper, we analyze the impact of inter symbol interference (ISI) and inter carrier interference (ICI) which are caused by multipath delay spread and Doppler frequency shift separately on system capacity, and derive the optimal CP length and subcarrier interval for GEO, MEO and LEO mobile satellite communication by numeric calculation. Finally, the simulation results show that the OFDM parameters of LTE specification can be used in GEO mobile satellite communications, but cannot in MEO and LEO.

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Abdul Majed, Mahmood Mohmmmed saeed, and Buthaina Mosa Omran. "Pilot Based Channel Estimation and Synchronization in OFDM System." Journal of Engineering 26, no. 6 (June 1, 2020): 50–59. http://dx.doi.org/10.31026/j.eng.2020.06.04.

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Channel estimation and synchronization are considered the most challenging issues in Orthogonal Frequency Division Multiplexing (OFDM) system. OFDM is highly affected by synchronization errors that cause reduction in subcarriers orthogonality, leading to significant performance degradation. The synchronization errors cause two issues: Symbol Time Offset (STO), which produces inter symbol interference (ISI) and Carrier Frequency Offset (CFO), which results in inter carrier interference (ICI). The aim of the research is to simulate Comb type pilot based channel estimation for OFDM system showing the effect of pilot numbers on the channel estimation performance and propose a modified estimation method for STO with less number of pilot to mitigate ISI effect. Channel estimation is simulated for different pilot number with 16QAM modulation in Ped-A Rayleigh channel. The STO effect assumed less than the cyclic prefix length to minimize ISI and maintain the orthogonality between subcarriers. The simulation results show that the high number of pilots are needed to achieve good channel estimation in case no synchronization used while similar results are achieved with smaller number of pilots if the propose modification on the synchronization method are used aligned with the channel estimation. The proposed system is evaluated in terms of BER and SNR.

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Min Hwang, Yu, Young Ghyu Sun, Issac Sim, and Jin Young Kim. "Iterative Approach for Performance Improvement of PLC Systems." International Journal of Engineering & Technology 7, no. 4.4 (September 15, 2018): 7. http://dx.doi.org/10.14419/ijet.v7i4.4.19592.

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In this paper, we propose Turbo equalizer scheme using zero-forcing (ZF) and simulate in power line communication (PLC) systems with high speed. Due to impulsive noise and multipath fading in PLC systems, inter-symbol interference (ISI) happens. We employ Turbo equalizer scheme to get over ISI and improve performance. From simulation results, it is confirmed that the proposed Turbo equalizer can remarkably improve PLC system performance.

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Suyoto, Suyoto, Agus Subekti, Arief Suryadi Satyawan, Vita Awalia Mardiana, Nasrullah Armi, and Dayat Kurniawan. "Performance analysis of OFDM-IM scheme under STO and CFO." International Journal of Electrical and Computer Engineering (IJECE) 11, no. 4 (August 1, 2021): 3293. http://dx.doi.org/10.11591/ijece.v11i4.pp3293-3299.

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In this letter, performance analysis of orthogonal frequency division multiplexing with index modulation (OFDM-IM) is presented in term of bit error rate (BERs). The analysis considers its performance under two impairments, symbol time offset (STO) and carrier frequency offset (CFO) in frequency-selective fading channel. As orthogonal multicarrier system, OFDM-IM is subject to both inter-symbol interference (ISI) and inter-carrier interference (ICI) in a frequency-selective fading channel. OFDM-IM is a new multicarrier communication system, where the active subcarriers indices are used to carry additional bits of information. In general, in the previous existing works, OFDM-IM are evaluated only for near-ideal communication scenarios by only incorporating the CFO factor. In this work, the OFDM-IM performance is investigated and compared with conventional OFDM in the presence of two impairments, STO and CFO. Simulation results show that OFDM-IM outperforms the conventional OFDM with the presence of STO and CFO, especially at high SNR areas.

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Aldhaibani, A. O., S. A. Aljunid, Mohd Shamsul Anuar, A. R. Arief, and H. Y. Ahmed. "Simulative Effect of Cyclic Prefix in Optical OFDM." Applied Mechanics and Materials 661 (October 2014): 190–94. http://dx.doi.org/10.4028/www.scientific.net/amm.661.190.

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Orthogonal frequency division multiplexing (OFDM) is one of the Multi-Carrier Modulation (MCM) techniques that transmit signals through multiple carriers. These carriers (subcarriers) have different frequencies and they are orthogonal to each other. There are different parameters which alter the performance of OFDM system. In this paper, the effect of cyclic prefix length (CP) on optical (OFDM) system is investigated. Although employing a CP as the guard interval is a simple way to combat inter-symbol interference (ISI) and inter-carrier interference (ICI), it reduces the transmission efficiency of the system. The simulation results show the effect of CP length in power receiver, penalty of power and improved the performance based on signal to noise ratio (SNR). In addition, a tradeoff is needed between reduced interference effects and transmission efficiency.

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Zacko Gbadoubissa, Jocelyn Edinio, Ado Adamou Abba Ari, Emanuel Radoi, and Abdelhak Mourad Gueroui. "M-Ary Direct Modulation Chirp Spread Spectrum for Spectrally Efficient Communications." Information 14, no. 6 (June 6, 2023): 323. http://dx.doi.org/10.3390/info14060323.

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Spread spectrum techniques, such as the Chirp Spread Spectrum (CSS) used by LoRa technology, are important for machine-to-machine communication in the context of the Internet of Things. They offer high processing gain, reliable communication over long ranges, robustness to interference and noise in harsh environments, etc. However, these features are compromised by their poor spectral efficiency, resulting in a very low data transmission rate. This paper deals with a spectrally efficient variant of CSS. The system uses M-ary phase keying to modulate the data and exploits CSS’s properties to transmit the modulated symbols as overlapping chirps. The overlapping of chirp signals may affect the system performance due to inter-symbol interference. Therefore, we analyse the relationship between the number of overlaps and the effect of inter-symbol interference (ISI), and we also determine the BER expression as a function of the number of overlaps. Finally, we derive the optimal number of overlapping symbols that corresponds to the minimum error probability.

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.S, Ramakrishna, and Priyatam Kumar. "Bit Error Rate Performance Analysis for Various Modulation Techniques using SUI Channel in Multi-Carrier System." International Journal of Advanced Research in Computer Science and Software Engineering 7, no. 7 (July 30, 2017): 419. http://dx.doi.org/10.23956/ijarcsse.v7i7.170.

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Orthogonal Frequency Division Multiplexing (OFDM) is of the strong prospects as a future wireless communication system. Improved spectral efficiency has been found in OFDM based on DFT, has a good orthogonality but inter symbol interference (ISI) and inter carrier interference (ICI) degrade the performance. ISI and ICI can be improved by using cyclic prefix (CP). About 20% of bandwidth is consumed by CP. For preferable performance DWT based OFDM gives better outlook than DFT based OFDM.. Three advantages of using DWT are desirable signal to noise ratio, desirable data rate and below per power requirement are given by wavelet based OFDM. Comparison of performances of BER using practical channel model known as Stanford University Interim (SUI) is given in this paper. Consideration to QPSK, 4QAM, 8QAM, 16 -QAM, 32QAM, 64-QAM, 128QAM and 256 QAM has been given in modeling. Channel condition and modulation are the pre - cursors given for the selection of particular performance.

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Sharma, Mahendra, and Santhosh Kumar Singh. "Orthogonality Measurent of OFDM Signal." Indonesian Journal of Electrical Engineering and Computer Science 9, no. 3 (March 1, 2018): 595. http://dx.doi.org/10.11591/ijeecs.v9.i3.pp595-598.

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<p>In recent days, Orthogonal Frequency Division Multiplexing is the technique to transmit and receive the signal without any overlapping of the signal. OFDM is also a multiplexing technique as well as modulation technique. It is a multi-carrier transmission technique in which single high data stream is divided into a number of lower rate streams that are transmitted simultaneous over some narrow sub channel. In general, OFDM avoids Inter-Symbol Interference (ISI), Inter-Carrier Interference (ICI) and fault transmissions between source and destination node. To measure the performance of the system by using the parameters like Bit Error rate (BER), Spectrum analysis and signal strength detection. Based on the parameters the best system can be identified.</p>

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Li, Lin, Zhaorui Zhu, and Jian Zhang. "Neural Network-Based Transceiver Design for VLC System over ISI Channel." Photonics 9, no. 3 (March 16, 2022): 190. http://dx.doi.org/10.3390/photonics9030190.

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In this letter, we construct the neural network (NN)-based transceiver to compensate for the varying inter-symbol-interference (ISI) effect in visible light communication (VLC) systems. For processing variable-length sequences, the convolution neural network (CNN) is utilized, and then the residual network structure is further leveraged at the receiver part to enhance the performance. To cope with varying ISI, the pilot sequence, instead of channel side information (CSI) obtained by an additional module, is integrated into the framework to recover the data sequence directly. Simulation results show that the symbol error rate (SER) performance of the proposed NN-based transceiver can outperform separately designed transceiver schemes and approach the ideal perfect CSI (PCSI) case with a few pilot symbols or even no pilot.

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Wang, Zixin, Fan Meng, and Lenan Wu. "Neural Network-Based Receiver in Band-Limited Communication System with MPPSK Modulation." ITM Web of Conferences 17 (2018): 01005. http://dx.doi.org/10.1051/itmconf/20181701005.

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As a type of the spectrally efficient modulation, the m-ary phase position shift keying (MPPSK) has been considered to meet the increasing spectrum requirement in the future wireless system. To limit the signal bandwidth and cancel the out-band interference the band-pass filters are used, which introduce the waveform distortion and inter-symbol interference (ISI). Therefore, a single hidden-layer neural network (NN)-based receiver is proposed to jointly equalize and demodulate the received signal. The impulse response of the system is static and the network parameters can be obtained after off-line training. The number of the hidden nodes is also determined through simulations. Simulation results show that the NN-based receiver works well in the communication system with different allocated bandwidths. By observing the modified confusion matrix, the false symbol decision is relevant to modulation index, waveform distortions and the ISI.

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Timakul, Sekson, Santi Koonkarnkhai, Piya Kovintavewat, and Somsak Choomchuay. "A Concatenate Code for Error Correcting Code in Bit Pattern Media Recoding System." Advanced Materials Research 834-836 (October 2013): 962–67. http://dx.doi.org/10.4028/www.scientific.net/amr.834-836.962.

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Bit Pattern Media Recording (BPMR) is the modern HDD recording technique which can overcome the constraint of conventional technique by offering tremendous areal density. However, narrow track of BPMR can cause noise generating from inter-track interference (ITI) and In. inter-symbol interference (ISI). One traditional technique used to improve BER of the system is the introducing of error control coding. In this paper, we investigate concatenate code applied to BPMR. We proposed inner code with low-density parity-check (LDPC) and Reed-Solomon (RS) codes as outer code. The obtained simulation results confirmed to us that the concatenated coding scheme yielded better performance compared with the single LDPC code deployment.

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Wu, Junyi, Zhiwen Liu, Ziyi Yang, and Changhao Du. "Fractionally spaced frequency domain equalization system based on FQPSK modulation." Applied and Computational Engineering 6, no. 1 (June 14, 2023): 947–52. http://dx.doi.org/10.54254/2755-2721/6/20230965.

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Severe multi-path effects in the process of high-speed data transmission cause inter-symbol interference (ISI). The single carrier frequency domain equalization (SC-FDE) method combining the benefits of Feher-patented quadrature phase shift keying (FQPSK) modulation is raised to solve this problem, including the constant envelope, high spectrum efficiency, and insensitivity to nonlinear distortion. Furthermore, a fractionally spaced frequency domain equalization (FS-FDE) system based on FQPSK modulation is modeled based on the proposed algorithm. Simulation results confirm the superior performance of the proposed model on erasing ISI, comparing to the symbol-spaced FDE (SS-FDE) system based on FQPSK modulation and the FS-FDE system based on QPSK modulation.

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Joo, Jung Suk. "Two-Stage Detection using ISI Cancelling for Multipath Fading Channels." ECTI Transactions on Electrical Engineering, Electronics, and Communications 7, no. 1 (February 20, 2008): 21–23. http://dx.doi.org/10.37936/ecti-eec.200971.171803.

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A simple detection scheme which can be easily implemented without maximum likelihood sequence estimation (MLSE) is proposed. It has a two-stage structure and makes ¯nal decisions after eliminating inter-symbol interference (ISI) due to both past and future symbols by using tentative decisions. Computer simulation results demonstrate that the proposed scheme can have a comparable performance to that of a tentative decision (TD)-MLSE when the number of resolvable channel paths is two, although its performance degrades as the number of resolvable channel paths increases.

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Fakher, Abolqassem, Falih Alnahwi, and Majid Alwan. "Performance Evaluation of OFDM System with Insufficient CP Using LMS Equalizer under Harsh Multipath Conditions." Iraqi Journal for Electrical and Electronic Engineering 15, no. 2 (December 1, 2019): 122–29. http://dx.doi.org/10.37917/ijeee.15.2.13.

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This paper presents an insufficient cyclic prefix (CP) Orthogonal Frequency Division Multiplexing (OFDM) system with equalizer whose coefficients are calculated using Least Mean Square (LMS) algorithm. The OFDM signal is passed through a channel with four multipath signals which cause the OFDM signal to be under high inter-symbol interference (ISI) and inter-carrier interference (ICI).8-QAM and 16-QAM digital modulation techniques are used to evaluate the performance of the proposed system. The simulation results have accentuated the high performance of the LMS equalizer via comparing its Bit Error Rate (BER) and constellation diagram with those of the Minimum Mean Square Error and Zero Forcing equalizers. Moreover, the results also reveal that the LMS equalizer provides BER performance close to that of the OFDM system with a hypothetical sufficient CP.

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Song, Eakhwan, Juyeop Kim, and Jiseong Kim. "A Passive Equalizer Optimization Method Based on Time-Domain Inter-Symbol Interference (ISI) Cancellation Technique." IEEE Transactions on Electromagnetic Compatibility 60, no. 3 (June 2018): 807–10. http://dx.doi.org/10.1109/temc.2017.2749519.

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Cui, Jin, Ding Rong Shao, and Bo Zhang. "New OFDM Channel Estimation Method Based on ISI Cancellation." Applied Mechanics and Materials 651-653 (September 2014): 2343–46. http://dx.doi.org/10.4028/www.scientific.net/amm.651-653.2343.

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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.

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Jeganlal, R., G. Jiji, C. Mariyal, H. Sehina, and T. Ajith Bosco Raj. "Performance Analysis of GFDM System in 5G Cellular Networks." International Journal of Circuits, Systems and Signal Processing 17 (March 6, 2023): 39–43. http://dx.doi.org/10.46300/9106.2023.17.4.

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Orthogonal Frequency Division Multiplexing (OFDM) is employed in the current 4G cellular technologies. Because of its resistance to multipath propagation channels, OFDM is a popular multicarrier modulation technique. Although OFDM is one of the effective approaches for a 4G network, out-of-band radiation, inter-symbol interference (ISI), and inter-carrier interference make this method unsuitable for 5G. (ICI). A new approach or next-generation cellular network, i.e., very high data rate, low latency, greater throughput, more device connectivity, and improved device-to-device communication, should be used to deliver effective and dependable communication. The system introduces generalized frequency division multiplexing (GFDM). In GFDM, a single cyclic prefix is utilized throughout the frame and an adjustable pulse-shaping filter can be used to monitor the transmitted signal’s out-of-band emission. Using this ISI, the multipath channel can be controlled. In the proposed system, with large signal constellations, higher-order modulation schemes, and advanced receiver structure, a very high data rate can be achieved. By using various iterative receiver structures the performance of the GFDM system in 5G cellular networks can be analyzed.

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Yuminaka, Yasushi. "High-Speed Data Transmission Techniques Using Raised Cosine Signaling." Key Engineering Materials 459 (December 2010): 252–59. http://dx.doi.org/10.4028/www.scientific.net/kem.459.252.

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In this paper, we propose new pulse-shaping techniques using raised cosine signaling instead of using conventional digital signals (rectangular waves), to reduce Inter-symbol interference (ISI) and crosstalk noise. Unlike a rectangular pulse, the raised cosine pulse takes on the shape of a sinc pulse that minimizes ISI. Also, limited bandwidth of the signal can reduce crosstalk noise. We show the simulation and experimental results of the raised cosine signaling scheme to show the new signaling method plays a critical part in maintaining signal integrity in high-speed VLSI systems.

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Peng, Gang, Rui Li, Yushu He, and Zhiren Han. "Timing and Frequency Synchronization Using CAZAC Sequences for OFDM Systems." Sensors 23, no. 6 (March 16, 2023): 3168. http://dx.doi.org/10.3390/s23063168.

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Since orthogonal frequency division multiplexing (OFDM) systems are very susceptible to symbol timing offset (STO) and carrier frequency offset (CFO), which cause inter-symbol interference (ISI) and inter-carrier interference (ICI), accurate STO and CFO estimations are very important. In this study, first, a new preamble structure based on the Zadoff–Chu (ZC) sequences was designed. On this basis, we proposed a new timing synchronization algorithm, called the continuous correlation peak detection (CCPD) algorithm, and its improved algorithm: the accumulated correlation peak detection (ACPD) algorithm. Next, the correlation peaks that were obtained during the timing synchronization were used for the frequency offset estimation. For this, the quadratic interpolation algorithm was adopted as the frequency offset estimation algorithm, which was better than the fast Fourier transform (FFT) algorithm. The simulation results showed that when the correct timing probability reached 100%, under the parameters of m = 8 and N = 512, the performance of the CCPD algorithm was 4 dB higher than that of Du’s algorithm, and that of the ACPD algorithm was 7 dB. Under the same parameters, the quadratic interpolation algorithm also had a great performance improvement in both small and large frequency offsets, when compared with the FFT algorithm.

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Simerjeet Kaur, Dr Kamal Kumar Sharma, and Mr. Navnidhi Sharma. "Analysis of BER Improvement of Adaptive Equalizer using CE and STB code." International Journal of Research in Informative Science Application & Techniques (IJRISAT) 3, no. 6 (June 25, 2019): 44–50. http://dx.doi.org/10.46828/ijrisat.v3i6.132.

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In a wireless communication channel, when the modulation bandwidth is exceeding the coherence bandwidth ISI takes place as the transmitted pulses are spread into the adjacent symbols. To combat the effects of ISI and noise and to reconstruct the signal and minimize Bit Error Rate (BER), the adaptive channel equalizer is used at the receiver end. Various kinds of interferences in a communication channel exists like Inter symbol Interference, Multipath Interference and Additive Interference which deals with the design of an Adaptive Equalizer. The idea of the equalizer is to build filter in the receiver that counter acts the effect of the channel. In essence, the equalizer must “unscatter” the impulse response and can be stated as the goal of designing the equalizer E so that the impulse response of the combined channel and equalizer CE has a single spike. We investigate channel equalization and introduce hierarchical and adaptive nonlinear channel equalization algorithms that are highly efficient and provide significantly enhanced bit error rate (BER) performance. Due to the high complexity of nonlinear equalizers and poor performance of linear ones, to equalize highly difficult channels, we employ piecewise linear equalizers.

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Monga, Himanshu, Shilpa Rani, and Pooja Mehta. "Performance Evaluation of Wavelet-Based Optical Wireless System using On-Off Keying Modulation." Journal of Optical Communications 40, no. 3 (July 26, 2019): 261–64. http://dx.doi.org/10.1515/joc-2017-0051.

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Abstract The paper investigates the performance of DWT (Discrete Wavelet Transform) and CWT (Continuous Wavelet Transform) techniques based on On – Off keying modulation (OOK) for reduced BER with increase in SNR in optical wireless system. In this work, the effects of Inter-symbol Interference (ISI) and light interference on Artificial Neural Network (ANN) receiver are analyzed and reported. In proposed optical wireless system the On- Off Keying (OOK) modulation is used at receiver to analyze BER and SNR. It is further concluded that error prospect in the received signal relates to the noise level, which is given in terms of obtained SNR value.

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Golani, Ori, Meir Feder, and Mark Shtaif. "Equalization Methods for Out-of-Band Nonlinearity Mitigation in Fiber-Optic Communications." Applied Sciences 9, no. 3 (February 2, 2019): 511. http://dx.doi.org/10.3390/app9030511.

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In recent years, it has been established that the adverse effects of nonlinear interference noise (NLIN) can be mitigated using adaptive equalization methods. As such, a wide variety of adaptive equalization methods have been used to treat nonlinearity, in different transmission scenarios. This paper reviews the principles of out-of-band nonlinearity mitigation using adaptive equalization. Statistical properties of NLIN that can be exploited for mitigation are discussed, as well as the cost and benefit of various types of equalizers. In particular we describe the equivalence between the NLIN and time-dependent inter-symbol-interference (ISI) and discuss ways in which the ISI coefficients can be characterized theoretically and experimentally. We further discuss the effectiveness of existing ISI mitigation algorithms, and explain the need for designing customized algorithms that take advantage of the various correlation properties characterizing the ISI coefficients. This paper is intended to be a practical reference for researchers who want to apply equalization algorithms or design new methods for nonlinearity mitigation.

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Siddiq, Abdulrahman Ikram. "Variable Length Cyclic Prefix OFDM using Multipath Delay Tracking." Tikrit Journal of Engineering Sciences 18, no. 2 (June 30, 2011): 12–21. http://dx.doi.org/10.25130/tjes.18.2.02.

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The Cyclic Prefix (CP) technique is widely used in Orthogonal Frequency Division Multiplexing (OFDM) systems. A CP of length greater than the channel order guarantees the orthogonality of the consecutive OFDM symbols. Therefore, the effects of Inter Symbol Interference (ISI) and Inter Carrier Interference (ICI) are cancelled. On the other hand, CP reduces the transmission efficiency.Conventional OFDM systems use constant length CP. For time varying channels, CP length may become shorter than channel order resulting in considerable loss in orthogonality and performance degradation. Otherwise, when CP length becomes much greater than channel order it results with time and power wasting, and hence decreasing transmission efficiency.This paper proposes the usage of a multipath delay-tracking module to provide the OFDM system with the actual channel order and accordingly the suitable CP length will be determined. Computer simulations show that the proposed system saves about 47.6% of the time and power spent by the same constant length CP OFDM system tested under the same conditions.

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HANUMOLU, PAVAN KUMAR, GU-YEON WEI, and UN-KU MOON. "EQUALIZERS FOR HIGH-SPEED SERIAL LINKS." International Journal of High Speed Electronics and Systems 15, no. 02 (June 2005): 429–58. http://dx.doi.org/10.1142/s0129156405003259.

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In this tutorial paper we present equalization techniques to mitigate inter-symbol interference (ISI) in high-speed communication links. Both transmit and receive equalizers are analyzed and high-speed circuits implementing them are presented. It is shown that a digital transmit equalizer is the simplest to design, while a continuous-time receive equalizer generally provides better performance. Decision feedback equalizer (DFE) is described and the loop latency problem is addressed. Finally, techniques to set the equalizer parameters adaptively are presented.

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Yang, Jie, Hua Min Zhang, and Wu Xie. "MMSE-BLE Algorithm of Single-Carrier Multi-User Channel Capacity." Key Engineering Materials 480-481 (June 2011): 855–61. http://dx.doi.org/10.4028/www.scientific.net/kem.480-481.855.

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A kind of minimum mean square error linear equalizer (MMSE-BLE) algorithm is presented for the solution on channel capacity of single-carrier code division multiple accesses (SC-CDMA) system, this algorithm received data symbol vector multiplied by covariance matrix by using Wiener estimator, and gets the decorrelation of multiple access interference (MAI), inter-symbol interference (ISI) and noise. MMSE-BLE algorithm calculates the channel capacity with MMSE criterion algorithm, so that it can analyze the multi-user uplink channel capacity of space-time coding SC-CDMA system under the multipath conditions effectively. The simulation results show that the number of user, path, transmitting and receiving antennas, multipath diversity gain, etc. All of them have an impact on the capacity of multi-user system, it seems that multiple antennas should be used for reception to get single-path diversity gain in frequency selective channels.

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Aljanaby, Ashwaq A. Abed, and Malathe Salah AL Deen Salah AL -Deen. "ADAPTIVE CYCLIC PREFIX LENGTH FOR CONVOLUITIONAL CODE OFDM SYSTEM IN FREQUENCY SELECTIVE CHANNEL." Journal of Engineering 18, no. 1 (May 10, 2023): 51–63. http://dx.doi.org/10.31026/j.eng.2012.01.04.

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Orthogonal Frequency Division Multiplexing (OFDM) is one of recent years multicarrier modulation used in order to combat the Inter Symbol Interference (ISI) introduced by frequency selective mobile radio channel. The circular extension of the data symbol, commonly referred to as cyclic prefix is one of the key elements in an OFDM transmission scheme. This paper study The influence of the cyclic prefix duration on the BER performance of an OFDM-VCPL (Orthogonal frequency division multiplexing - Variable Cyclic Prefix Length) system and the conventional OFDM system with frame 64-QAM modulation is evaluated by means of computer simulation in a multipath fading channel. The adaptation of CP is done with respect to the delay spread estimation of the channel.

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Wang, Wen Bin, Dao Yuan Liu, and Yu Qin Yao. "Research of Equalization Technology Based on Matlab." Applied Mechanics and Materials 513-517 (February 2014): 3786–89. http://dx.doi.org/10.4028/www.scientific.net/amm.513-517.3786.

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In the modern digital communication system, inter-symbol interference (ISI) caused by the imperfectness of the channel is a major factor that degrades the performance of communication. In order to decrease the influence of ISI and improve communication quality, people usually use equalization technology. Generally, channel response is changing over time, so the adaptive equalizer is necessary. This paper firstly introduced the theoretical foundation and realization method of the adaptive equalization system. Then discuss the LMS algorithm. Finally, the SIMULINK tool is used to build a communication system. The set of simulation results by observing the eye diagrams of the signals before and after equalization have validated the equalization effect.

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Xia, Yu, Fang Ye, Yi Bing Li, and Ling Wang. "A Modified DFE-MMSE Equalization Algorithm." Advanced Materials Research 981 (July 2014): 444–49. http://dx.doi.org/10.4028/www.scientific.net/amr.981.444.

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In wireless communication, inter symbol interference (ISI) and signal distortion are often caused by the frequency deviation and time offset of wireless channel. To eliminate or reduce ISI, people proposed the channel equalization technology. However, traditional decision feedback equalization algorithm based on MMSE criterion equalizer (DFE-MMSE) often introduces the error diffusion which degrades the performance of the equalizer in iterative system. In this paper, we propose an improved DFE-MMSE algorithm to reduce the error diffusion and improve the performance of iterative equalization, with a correction factor. Simulation results show that our algorithm achieves better bit error rate, which makes it competent in more practical cases.

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Fatima, Bouasria. "The Channel Shortening comparison between OFDM & MC-CDMA System over an ADSL Channel using a Water-filling." International Journal of Electrical and Computer Engineering (IJECE) 9, no. 5 (October 1, 2019): 3695. http://dx.doi.org/10.11591/ijece.v9i5.pp3695-3700.

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<p>In this paper our objective focuses on the development of digital transmission techniques in order to solve the problem of Inter-Symbol Interference (ISI) due to multiple paths and the improvement of Multi-Carrier Code Division Multiple Access (MC-CDMA) system performance. The both algorithm: MERRY algorithm (Multicarrier Equalization by Restoration of Redundancy) called TEQ (Time domain EQualizer) and the power allocation method to allocate appropriate power to each user (Water-filling technique (WF)) [1] is used. Finally, the numerical results show that combining Water Filling with TEQ technique allows to reduce the ISI for MC-CDMA systems.</p>

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Et.al, Judy Simon. "A Performance Analysis of Wavelet based LTE-OFDM with Multi-equalizers." Turkish Journal of Computer and Mathematics Education (TURCOMAT) 12, no. 6 (April 11, 2021): 108–16. http://dx.doi.org/10.17762/turcomat.v12i6.1274.

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A rapid change in usage of mobile data and mobile based applications such as online gaming, mobile TV etc. motivates the mobile wireless communication system to work on new emerging trends Long Term Evolution (LTE). LTE-4G architecture provides an optimized packet based radio access technology. The basic signal format of LTE is Orthogonal Frequency Division Multiplexing (OFDM) Modulation. This modulation scheme satisfies the spectrum flexibility requirement in LTE. LTE-MIMO-OFDM with IFFT and FFT transform introduced to provide the cost-effective solution for very wide carriers with high PAPR. Inter-symbol Interference (ISI) and inter carrier interference (ICI) are predominant factors which exist in the wireless communication channel. Existing methods of ISI and ICI reduction to improve signal quality have been achieved using conventional OFDM techniques. However, a better modulation scheme is required to achieve high data rate, low latency and flexible bandwidth deployment. This paper has proposed a Wavelet based LTE-MIMO-OFDM modulation scheme with multi equalizer that improves the performance of system by reducing PAPR and BER in MCM. Experimental results show the performance of this scheme and the results is compared with existing MMSE and Multi equalizer MMSE and achieves a flexible spectral efficiency with reduction of PAPR and BER.

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Cuc, Adriana-Maria, Florin Lucian Morgoș, and Cristian Grava. "Performance Analysis of Turbo Codes, LDPC Codes, and Polar Codes over an AWGN Channel in the Presence of Inter Symbol Interference." Sensors 23, no. 4 (February 9, 2023): 1942. http://dx.doi.org/10.3390/s23041942.

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This paper discusses the results of simulations relating to the performances of turbo codes, low density parity check (LDPC) codes, and polar codes over an additive white Gaussian noise (AWGN) channel in the presence of inter symbol interference, denoting the disturbances that altered the original signal. To eliminate the negative effects of inter symbol interference (ISI), an equalizer was used at the level of the receiver. Practically, two types of equalizers were used: zero forcing (ZF) and minimum mean square error (MMSE), considering the case of perfect channel estimation and the case of estimation using the least square algorithm. The performance measure used was the modification of the bit error rate compared to a given signal to noise ratio; in this sense, the MMSE equalizer offered a higher performance than the ZF equalizer. The aspect of channel equalization considered here is not novel, but there have been very few works that dealt with equalization in the context of the use of turbo codes, especially LDPC codes and polar codes for channel coding. In this respect, this research can be considered a contribution to the field of digital communications.

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Song, Lijun, Xia Lei, Maozhu Jin, and Zhihan Lv. "Joint Channel Estimation and Signal Detection for the OFDM System Without Cyclic Prefix Over Doubly-Selective Channels." International Journal of Bifurcation and Chaos 25, no. 14 (December 30, 2015): 1540028. http://dx.doi.org/10.1142/s0218127415400283.

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In the high-speed railway wireless communication, a joint channel estimation and signal detection algorithm is proposed for the orthogonal frequency division multiplexing (OFDM) system without cyclic prefix in the doubly-selective fading channels. Our proposed method first combines the basis expansion model (BEM) and the inter symbol interference (ISI) cancellation to overcome the situation that exists with the fast time-varying channel and the normalized maximum multipath channel exceeding the length of the cyclic prefix (CP). At first, the channel estimation and signal detection can be approximated without considering the ISI. Then, the channel parameters and signal detection are updated through ISI cancellation and circular convolution reconstruction from the frequency domain. The simulations show the algorithm can improve the performance of channel estimation and signal detection.

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Liu, Shun Lan, and Lin Wang. "New Hybrid Blind Equalization Algorithms." Applied Mechanics and Materials 182-183 (June 2012): 1810–15. http://dx.doi.org/10.4028/www.scientific.net/amm.182-183.1810.

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A novel decision-directed Modified Constant Modulus Algorithm (DD-MCMA) was proposed firstly. Then a constellation matched error (CME) function was added to the cost function of DD-MCMA and CME-DD-MCMA algorithm was presented. Furthermore, we improve the CME-DD-MCMA by replacing the fixed step with variable step size, that is VSS-CME-DD-MCMA algorithm. The simulation results show that the proposed new blind equalization algorithms can tremendously accelerate the convergence speed and achieve lower residual inter-symbol interference (ISI) than MCMA, and among the three proposed algorithms, VSS-CME-DD-MCMA has the fastest convergence speed and the lowest residual ISI, but it has the largest computation complexity.

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Radhi Shabib Kaned. "Investigation of Phase Noise on the Performance of LMS-RLS Adaptive Equalizer." Diyala Journal of Engineering Sciences 6, no. 1 (March 1, 2013): 27–35. http://dx.doi.org/10.24237/djes.2013.06103.

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This paper investigates the effect of phase noise on equalization of communication channels using least mean square (LMS) and recursive least square (RLS) adaptive algorithms. The aim of the investigation is to mitigate inter-symbol interference (ISI) caused by the channel and to impose the bit error rate (BER) in the received signals. The equalizerusestwobasicadaptivealgorithms: LMS algorithmand RLS algorithm. Without LMS-RLS equalizer,theBER ismorethan when the system modelincludesLMS-RLS equalizer as indicated in table (1) and table (2). Equalizer algorithm is analyzed using MATLAB v.9 Communication Block Set.

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Journal articles on the topic 'Inter-symbol Interference (ISI)'

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