Mathematical analysis of the impact of timing synchronization errors on the performance of an OFDM system

Mostofi, Yasamin; Cox, D.C.

doi:10.1109/tcomm.2005.861675

Cited by 163 publications

(92 citation statements)

References 5 publications

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“…Kesalahan dalam estimasi waktu tidak hanya menyebabkan ICI dan ISI tetapi juga menurunkan kinerja estimasi kanal [7]. Persyaratan untuk sinkronisasi akan tinggi dengan meningkatnya kompleksitas sistem.…”

Section: Ofdmunclassified

Studi Perbandingan Teknik Sinkronisasi Waktu untuk Sistem Mobile OFDM

Suyoto

2014

INKOM

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OFDM (Orthogonal Frequency Division Multiplexing) is a modulation technique suitable for high delay spread applications. However, the performance of OFDM is very sensitive to time synchronization errors. In this study, we review some of the algorithms for time synchronization in communication systems OFDM in the ITU Vehicular multipath channel model. From the results of the reviews we chose four time synchronization algorithm that has impulsive timing metric to be evaluated in calculating the arrival time of OFDM symbol. Simulation is done by considering the influence of SNR (Signal to Noise Ratio) and CIR (Channel Impulse Response). Performance of the algorithm is measured by the MSE (Mean Squared Error) of offset timing point. The simulation results show that conventional techniques (autocorrelation and crosscorrelation technique) is not enough for the system to channel conditions with high delay spread. Conventional techniques that combined with statistical changes of correlator has better performance to channel conditions with high delay spread. keywords: Mobile, Time synchronization, Multipath channels, OFDM Abstrak OFDM (Orthogonal Frequency Division Multiplexing) adalah teknik modulasi cocok untuk aplikasi delay spread yang tinggi. Namun kinerja OFDM sangat sensitif terhadap kesalahan sinkronisasi waktu. Pada tulisan ini, pengkajian terhadap beberapa algoritma untuk sinkronisasi waktu di sistem komunikasi OFDM pada model kanal multipath ITU Vehicular dilakukan. Dari hasil analisis, terpilih empat algoritma sinkronisasi waktu yang mempunyai ukuran pewaktu yang bersifat impulsif untuk dievaluasi kinerjanya dalam menghitung waktu kedatangan simbol OFDM. Simulasi dilakukan dengan mempertimbangkan pengaruh SNR (Sinyal to Noise Ration) dan CIR (Channel Impulse Response). Kinerja dari algoritma diukur dengan MSE (Mean Squared Error) dari offset timing point. Hasil simulasi menunjukkan bahwa teknik konvensional (teknik autocorrelation dan crosscorrelation) tidak cukup untuk sistem dengan kondisi kanal dengan delay spread yang cukup tinggi. Teknik konvensional yang digabungkan dengan teknik perubahan statistik pada korelator mempunyai kinerja yang lebih baik pada kondisi kanal dengan delay spread yang cukup tinggi. kata kunci: Mobile, Sinkronisasi waktu, Kanal multipath, OFDM

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Section: Ofdmunclassified

Studi Perbandingan Teknik Sinkronisasi Waktu untuk Sistem Mobile OFDM

Suyoto

2014

INKOM

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“…Recently OFDM technique is also used for cognitive radio systems, which the use of frequency spectrum in the OFDM systems can be done as efficiently as possible [4]- [5]. However, OFDM systems need strict timing synchronization between transmitter and receiver, as an error in timing estimation give rise to InterSymbol Interference (ISI) and can decrease the overall performance of OFDM systems [6]- [7].…”

Section: Introductionmentioning

confidence: 99%

Improved Timing Estimation Using Iterative Normalization Technique for OFDM Systems

Suyoto

Iskandar

Sugihartono

et al. 2017

IJECE

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Conventional timing estimation schemes based on autocorrelation experience performance degradation in the multipath channel environment with high delay spread. To overcome this problem, we proposed an improvement of the timing estimation for the OFDM system based on statistical change of symmetrical correlator. The new method uses iterative normalization technique to the correlator output before the detection based on statistical change of symmetric correlator is applied. Thus, it increases the detection probability and achieves better performance than previously published methods in the multipath environment. Computer simulation shows that our method is very robust in the fading multipath channel. are supporting applications that run in a high speed mobility environment. Recently OFDM technique is also used for cognitive radio systems, which the use of frequency spectrum in the OFDM systems can be done as efficiently as possible [4]- [5]. However, OFDM systems need strict timing synchronization between transmitter and receiver, as an error in timing estimation give rise to InterSymbol Interference (ISI) and can decrease the overall performance of OFDM systems [6]- [7].For symbol timing estimation, Schmidl [8] used a preamble consists of two identical parts for symbol timing estimation. But, the timing metric of Schmidl's method has a plateau, which causes a large variance in the timing offset estimation. To decrease the plateau, Minn [9] proposed a new training symbol with four identical parts. It results a sharper timing metric than Schmidl's method, however, it still has ambiguity due to some side-lobes at a side of the peak correlation region, thus estimation variance is still large. In order to reduce the variance, Park [10] proposed a sharper timing metric using symmetric correlation property of the preamble. Yet, the timing metric of Park's method has two large side-lobes. To eliminate the side-lobes of Park's timing metric, Yi [11] proposed a new preamble structure that has symmetric correlation property. The performance of all the above-mentioned approaches decrease in multipath channel environments.To overcome this problem, Cho [12] proposed a method that exploits statistical change of symmetric correlator. It reduces the multipath channel effect, hence the variance of the timing offset estimation is small. However, Cho's method generates error detection if the correlation magnitude on the first arriving path is much smaller than the strongest path. To overcome this problem, we proposed an iterative normalization technique to the correlator output before the detection based on statistical change of symmetric correlator is applied. Considering the very small correlation magnitude on the first arriving path, we attempt to increase the correlation magnitude on the first arriving path to

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“…To address this need, several technologies have been combined for high rate transmission with forward error correction techniques.Frequency division multiplexing (FDM) is a technology that transmits multiple signals simultaneously over a wired or a wireless system in which each signal is limited by a specific frequency band, and is modulated by data stream. Orthogonal Frequency Division Multiplexing [1] and is a special case of frequency division multiplexing, where the data is distributed over a large number of carriers, which are orthogonal to each other. OFDM [2] is spectrally efficient compared to the conventional FDM systems, since it doesn't need guard bands between adjacent channels.…”

Section: Introductionmentioning

confidence: 99%

Comparative Study of OFDM and CDMA Technique

Gari¹

2013

IOSR-JECE

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Mathematical analysis of the impact of timing synchronization errors on the performance of an OFDM system

Cited by 163 publications

References 5 publications

Studi Perbandingan Teknik Sinkronisasi Waktu untuk Sistem Mobile OFDM

Studi Perbandingan Teknik Sinkronisasi Waktu untuk Sistem Mobile OFDM

Improved Timing Estimation Using Iterative Normalization Technique for OFDM Systems

Comparative Study of OFDM and CDMA Technique

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