Comparative study of four modified timing metrics for the frame synchronization in OFDMA mode of WMAN (original) (raw)
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The aim of this paper is to survey and compare previous methods for Data-aided timing and frequency synchronization of OFDM System.Synchronization has been one of the crucial research topics in orthogonal frequency division multiplexing (OFDM) system because of its sensitivity to the timing and frequency errors [1]. To guarantee the fast and accurate data transmission, the Inter Symbol Interference (ISI) and Inter Carrier Interference (ICI) caused in the transmission have to be eliminated as much as possible.ORTHOGONAL frequency-division multiplexing(OFDM) has been of major interest for both wireline-based and wireless applications [1]-[3] due to its highdata rate transmission capability and its robustness to multipathdelay spread. However, OFDM systems are much more sensitive to synchronization errors than single carrier systems [4],[5]. This paper summarizes various methods to cater this synchronization problem.
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TIMING SYNCHRONIZATION IN MIMO-OFDM SYSTEMS Farhan Farhan, M.S.T. Western Carolina University (March 2013) Director: James Z. Zhang OFDM (Orthogonal Frequency Division Multiplexing) provides a promising physical layer for 4G and 3GPP LTE Systems in terms of efficient use of bandwidth and high data rates. It is used in several applications like WiFi (IEEE 802.11n), WiMax (IEEE 802.16), Digital Audio Broadcasting (DAB), Digital Video Broadcasting (DVB) and so on. OFDM suffers from inter-symbol interference and inter-carrier interference in wireless and fading environments and it is important to estimate and correct the start of OFDM symbol efficiently to reduce timing and frequency offset errors. Synchronization issues in OFDM are crucial and can lead to certain amount of information loss if they are not properly addressed. There are two modes of implementation forDigital Video Broadcasting-Terrestrial (DVB-T) and this thesis implements the 2K mode. It highlights the implementation of...
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EURASIP Journal on Wireless Communications and Networking, 2006
Orthogonal frequency division multiplexing (OFDM) is a parallel transmission scheme for transmitting data at very high rates over time dispersive radio channels. In an OFDM system, frame synchronization and frequency offset estimation are extremely important for maintaining orthogonality among the subcarriers. In this paper, for a preamble having two identical halves in time, a timing metric is proposed for OFDM frame synchronization. The timing metric is analyzed and its mean values at the preamble boundary and in its neighborhood are evaluated, for AWGN and for frequency selective channels with specified mean power profile of the channel taps, and the variance expression is derived for AWGN case. Since the derivation of the variance expression for frequency selective channel case is tedious, we used simulations to estimate the same. Based on the theoretical value of the mean and estimate of the variance, we suggest a threshold for detection of the preamble boundary and evaluating the probability of false and correct detections. We also suggest a method for a threshold selection and the preamble boundary detection in practical applications. A simple and computationally efficient method for estimating fractional and integer frequency offset, using the same preamble, is also described. Simulations are used to corroborate the results of the analysis. The proposed method of frame synchronization and frequency offset estimation is applied to the downlink synchronization in OFDM mode of wireless metropolitan area network (WMAN) standard IEEE 802.16-2004, and its performance is studied through simulations.