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In this paper, based on mutually orthogonal (MO) ZCZ polyphase sequence (PS) sets proposed by Ref. [11], a method for improving the family size of ZCZ sequences in each set mentioned above is presented. As compared with Ref. [11], the resulting ZCZ sequences in each set can arrive to their theoretical bound due to expansion of their family size, whereas the length and width of ZCZ of ZCZ sequences...
We propose a simple and robust carrier frequency recovery (CFR) scheme for DVB-S2 receivers. The proposed coarse CFR scheme employs a modified Mengali and Morelli (M&M) algorithm and recovers a coarse carrier frequency offset (CFO) accurately. After coarse CFR, a fine CFR scheme that employs a simple pilot block correlation algorithm recovers a residual CFO. The proposed scheme shows a bit error...
This paper presents an architecture of an autocorrelator for Orthogonal Frequency Division Multiplexing systems. The received signal is quantized to only the sign-bit, which dramatically simplifies the frequency offset estimation. Hardware cost is reduced under the assumption that synchronization during acquisition does not have to be very accurate, but sufficient for coarse estimation. The architecture...
Utilizing the characteristic of IEEE 802.16d downlink frame's format, this paper proposed a modified frame synchronization method, which can achieve a better frame synchronization. The first OFDM training symbol in long preamble is used for rough synchronization, and the second OFDM training symbol in long preamble is used for fine synchronization. Due to symbol repetition in long preamble, autocorrelation...
The correlation-based method is the popular solution for timing synchronization. The performance of this method is decreased in low signal-to-noise ratio (SNR) because of the limited correlation peaks. In this paper, a new method based on more peaks by using a new structure of the short preamble is proposed. Simulation results show that the proposed approach greatly improves the estimation accuracy...
By analytical means, this paper investigates the application of a multi-periodic preamble for the synchronization in OFDM systems, which is based on an auto-correlation of the received signal. In contrast to common system configurations, the multi-periodic preamble enables to select the two parameters correlation shift and correlation window length independently of each other. This allows adapting...
In the cooperative relay system, different frames from different relays are not aligned in the time domain, and have different carrier frequency offsets (CFOs). Estimation of these time offsets and multiple CFOs is a crucial and challenging task. In this contribution, a new preamble structure is proposed, and the corresponding timing and frequency synchronization algorithms are also presented for...
OFDM system performance is sensitive to frequency offset and timing error than single-carried system. In this paper, a novel joint time and frequency synchronization method is proposed based on PN sequences for OFDM. A special training symbol of OFDM is constructed with the PN sequence and the differentially coded PN sequence in the transmitter, in the receiver, the training symbol is differentially...
A blind synchronization algorithm for the direct sequence code division multiple access (DS-CDMA) signals is presented in this paper without knowledge of spreading sequence, carrier frequency, or the number of users. The only a priori information used is the symbol period. The algorithm exploits the structure of the signal correlation matrix and estimate the timing offset based on l1-norm of the correlation...
It is well known that the cyclic property of transmitted signal can be used to achieve joint frame and carrier frequency synchronization, while the uncompensated sampling frequency offset (SFO) would still be a problem. Based on the observation that the impact of SFO on the received cyclic block and its replica is equivalent to a relative time shift, a joint synchronization scheme solely based on...
In this paper, a complete solution to the initial synchronization for multi-cell OFDMA (orthogonal frequency division multiple access) systems is proposed. The proposed method consists of the following operations: timing synchronization, fractional carrier frequency offset (CFO) estimation, fractional CFO compensation, and joint integer CFO and preamble index estimation. To estimate multiple fractional...
In this paper, we propose a low-complexity carrier frequency offset (CFO) estimation algorithm for OFDM based wireless LAN, IEEE 802.11a. The complexity of the arctangent operation to calculate the argument of auto-correlation for CFO estimation is reduced by a novel range pointer method. The proposed algorithm estimates fine CFO value first and then based on the fine CFO value, simple criteria is...
Considering the features of Underwater Acoustic channel and the sensitivity versus synchronization for CI/OFDM system, A time and frequency synchronization method based on Constant Amplitude Zero Auto-Correlation(CAZAC) sequence is presented. The time offset estimation and carrier frequency offset estimation can be achieved simultaneously. The fractional part and integral part of carrier offset estimation...
According to the packet structure of IEEE Standard 802.11a and the characters of short training symbols, a new frequency offset estimation algorithm is presented. A two stages strategy based on auto-correlation algorithm is used to solve the contradiction between estimation accuracy and estimation range. At the first stage, the coarse frequency offset estimating bases on the identity of half cyclical...
The synchronization problem is analyzed for low voltage power-line communication of orthogonal frequency division multiplexing (OFDM). It is analysed theoretically what affect synchronization problem such as frequency synchronization error and timing synchronization error. A new symbol timing and carrier frequency synchronization algorithm is presented and the algorithm divides the OFDM symbol into...
Audio-to-video synchronization (AV-sync) may drift and is difficult to recover without dedicated human effort. In this work, we develop an interactive method to recover the drifted AV-sync by audiovisual correlation analysis. Given a video segment, a user specifies a rough time span during which a person is speaking. Our system first detects a speaker region using face detection. It then does a two-stage...
We propose a three-stage cross correlation-based timing synchronization algorithm for multiband-OFDM UWB systems. By utilizing the time-domain base sequence of the packet/frame synchronization preamble, the proposed algorithm first performs a coarse estimation on the reference symbol boundary, followed by a fine estimation on locating the exact boundary of the FFT window for the symbol, and a final...
Aiming at the problems of the detection of the pseudo-random code sequence and the information symbol period of long pseudo-random code DSSS (direct sequence spread spectral) signals, the paper proposes a method based on the processing of delay-multiply. The method does processing of chip-delay-multiply on the received signals at first, then does correlation matrix analysis and gets an estimation...
Secure transmission of information over hostile wireless environments is desired by both military and civilian parties. Direct-sequence spread spectrum (DS-SS) is such a covert technique resistant to interference, interception and multipath fading. Identifying spread-spectrum signals by an unintended receiver (or eavesdropper) without a priori knowledge is a challenging problem. To address this problem,...
This paper presents an efficient frequency estimator for digital video broadcasting - second generation (DVB-S2). Analyzing the robust algorithm among data-aided approaches, we find that the Luise & Reggiannini (L&R) algorithm is the most suitable one for coarse frequency estimation with respect to estimation performance and complexity. However, it requires many multipliers and adders to compute...
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