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In this paper, the authors address the problem of true Cramer-Rao lower bound (CRLB) derivation for a non-data-aided (NDA) vector parameter estimation over non-constant gain flat Rayleigh fading channel (FRFC). General CRLB expressions for carrier frequency offset, carrier phase, symbol timing and signal to noise ratio (SNR) estimation are analytically developed going through the computation of the...
Time domain synchronous orthogonal frequency division multiplex (TDS-OFDM) is an effective multi-carrier modulation scheme to improve spectrum efficiency. Conventional synchronization algorithm based on the time-domain differential correlation of the pseudo noise (PN) sequence may not work well in severe multipath fading channels. In this paper, a robust synchronization algorithm is proposed where...
A novel cell search scheme based on coherent sequence detection and sign decision is proposed in this paper. The given structure of the SCH (synchronization channel) allows the UE (user equipment) to detect cell ID with low complexity, and the adverse effects of the channel fading and frequency offset are eliminated in the three search steps. The performance of the scheme is investigated in various...
This paper introduces novel frame synchronization methods which require lower computational complexity than conventional methods. There are two contributions in this paper. First, a low-complexity method to compute signal estimation error is introduced. Second, an algorithm is proposed to search frame timing candidates efficiently for an estimation error minimizing timing candidate. The simulation...
In this paper a frequency offset estimation technique for Wireless Local Area Networks is presented. For frequency offset estimation, we have applied a low-complexity frequency offset estimator for simple AWGN channels to fading channels in the MIMO-OFDM systems. Simulation results have shown that the performance of the proposed estimator is better than the low complexity frequency offset estimator...
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...
Orthogonal frequency division multiplexing (OFDM) systems are more sensitive to timing and frequency offsets than single carrier systems. This paper presents a method of joint time and frequency synchronization for OFDM systems. The synchronization technique is examined in both AWGN and multipath fading environments. Compared with conventional schemes, the proposed schemes can achieve smaller mean...
In orthogonal frequency division multiplexing (OFDM) system, synchronization and channel estimation are two important issues under the wireless fading channel in broadband wireless communication. The timing and frequency offset will affect the accuracy of channel estimation. These issues are studied in this paper, and a frequency selective fading channel under the OFDM system model is set up. This...
A time and frequency synchronization scheme for OFDM wireless communication system based on a novel training sequence is proposed. The training sequence includes only one OFDM symbol. It is centro-symmetric and only modulated on even sub-carriers, the second half of which is duplicate of the first half. So, timing metric can avoid peak plateau, and frequency offset estimator can effectively resist...
In this paper, we propose a coarse and fine frequency synchronization method which is suitable for the 3rd Generation Partnership Project (3GPP) long term evolution (LTE) orthogonal frequency division multiple access (OFDMA) system in time division duplexing (TDD) mode. In general, primary synchronization signal (PSS) correlation based estimation method and cyclic prefix (CP) correlation based tracking...
In this paper, we propose a cooperative communation scheme using multi-symbol encapsulated orthogonal frequency division multiplexing (MSE-OFDM), in which one cyclic prefix (CP) is used for multiple OFDM symbols. We use the FFT size-reduced MSE-OFDM system which can be used to reduce the peak-to-average power ratio (PAPR) and improve the robustness to carrier frequency offset. The cooperative communication...
In this paper the Coefficient Tracking Synchronization Algorithm is proposed for the compensation and the suitability of the fast channel fluctuation OFDM in the WAVE (Wireless Access in Vehicular Environments) system. The in progress of standardization WAVE process, IEEE802.11's physical layer is considered on the coexistence of fading and Frequency offset of OFDM channel to find the system performance...
A frequency offset estimation algorithm for DTMB system based on signalpsilas second-order cyclostationary is developed. A unified structure of the method is given for diverse modes in DTMB system. Simulations show that this approach has good performance for both single-carrier and multi-carrier modes in AWGN and dynamic Rayleigh fading channel.
In this paper, we propose a new frequency synchronization algorithm for orthogonal frequency division multiplexing (OFDM) system by combining PN sequences with cyclic prefix. It is the improvement of Tufvesson's algorithm. In the new algorithm, the frequency offset is estimation with two steps. First a small step (span of the correlation) is used to estimate frequency offset which will result in a...
Cyclic delay diversity (CDD) is a simple transmit diversity technique for coded OFDM systems with multiple transmit antennas. It is applicable to existed wireless communication systems since it does not need modifications of the standard OFDM receiver. However, CDD causes serious degradation in the performance of post-FFT estimation, i.e., integer frequency offset (IFO). This paper suggests pilot...
In this paper we propose a modified MSE based automatic blind modulation recognition (ABMR) algorithm for recognizing different rectangular QAM signals. The proposed method is robust to preprocessing errors like error in estimation of carrier frequency, synchronization and extraction of constellation from real band-pass signals. The performance of the proposed algorithm has been evaluated in the both...
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