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In this paper, a new and efficient approach for Orthogonal Frequency-Division Multiplexing (OFDM) timing offset error estimation has been presented without using pilot signal. The effect of timing offset on bit error rate (BER) has been analyzed using BPSK, QPSK, 8-PSK modulation scheme and an analytical expression has been derived using probabilistic equation to estimate timing offset. This will...
In this paper, two fast and accurate FFT-based frequency offset estimation methods for OFDM systems are proposed. We analyze and simulate proposed methods in both Gaussian and multipath fading channels, and compare the results with those obtained using well known Schmidl's method. The simulation results are presented in terms of Error Variance (EV). Both proposed FFT-based methods have significantly...
This paper studies the frame synchronization of Orthogonal Frequency Division Multiple Access-Time Division Duplexing (OFDMA-TDD) systems and proposes a new method for downlink of IEEE 802.16 to improve frame synchronization performance. In this paper, we adapt three existing timing metrics for frame synchronization in OFDM mode of WiMAX. Among the methods considered, it is shown that direct application...
In this paper, we propose a new method for frame synchronization in OFDMA mode of WMAN. The scheme is based on the preamble suggested for OFDMA mode of WMAN where the preamble consists of real subsymbols and OFDMA data symbols contain complex subsymbols for each frame. The proposed method is independent of frequency offset and results in sharp peak at the frame boundary. A simple approach for selecting...
In this paper, we adapt four existing timing metrics for frame synchronization in OFDMA mode of WMAN. Among the methods considered, first method uses cyclic prefix information present in the symbol, second method uses the symmetry in the time domain preamble data, third method exploits a priori knowledge of the preamble PN sequence, and the fourth method exploits the conjugate symmetry in the time...
This paper introduces an on-line unsupervised LEArning neural network (NN) for adaptive feature extraction via Principal component analysis (LEAP) of lower signal to noise ratios (SNR) direct sequence code-division multiple-access (DS-CDMA) signals. The proposed method is based on eigen-analysis of DS-CDMA signals, and exploits the cyclo-stationarity of communication signals adequately. The received...
This paper presents a burst modulation/demodulation method for narrowband wireless communication systems, whose traffic is especially dominated by short packet bursts. In order to improve transmission efficiency and burst synchronization performance, the proposed method provides a preamble-less frame structure with minimum number of training symbols. This paper also presents the experimentally measured...
Li and Xia have recently investigated the design of space-time codes that achieve full spatial diversity for asynchronous cooperative communications. They show that certain of the binary space-time trellis codes derived from the Hammons-El Gamal stacking construction are delay tolerant and can be used in the multilevel code constructions by Lu and Kumar to produce delay tolerant space-time codes for...
This work studies the performance of a data-driven reduced rank scheme for rapid timing acquisition in multiple access communications. Our results show that when only a limited amount of preamble bits are available, instead of the true second-order statistics (SOS), the reduced rank scheme provides reliable timing information. Exploiting the structure of the multiple access interference, the data...
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