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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...
In this paper, a low-complexity algorithm for cell ID group and subframe number estimation, which requires the highest computational complexity in the SSS detection procedure, is proposed for low-power MTC devices. Through simulation under LTE-based MTC environment, we show that the proposed method for SSS detection requires five times less computation complexity than the conventional method, while...
Traditional OFDM based transmission system uses Cyclic Prefix (CP) in an OFDM symbol in order to maintain orthogonality of transmission. Present days' Ultra-Wideband (UWB) systems use Multi-Band OFDM (MB-OFDM) techniques for transmission in application like Wireless Personal Area Network (WPAN). UWB based systems are power limited by the regulation of FCC. CP introduces correlation in the transmitted...
This paper presents baseband receiver design for the third Generation Partnership Project (3GPP) Long Term Evolution (LTE) downlink systems under fast-fading channels. We aim to support 2×2 open-loop spatial multiplexing at high mobility up to 240 Km/hr with well-synchronized capability. The proposed receiver contains the functional blocks of mode detection, synchronization, channel tracking, inter-carrier...
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...
This paper addresses the effect of timing synchronization errors for two different multicarrier techniques CPOFDM and FBMC. Such errors degrade the performance of the reference receiver by causing multi user interference. This interference occurs when the signals from different transmitters arrive at a given receiver with arbitrary timing misalignments, leading to the destruction of orthogonality...
The OFDM technology can conquer the frequency selected fading and the inter-channel interference (ICI) effectively, so it is the core technology in the future mobile communications. The basic principle and some key technologies of OFDM are studied in this paper. Then we gave the OFDM block diagram and simulink model. Under the non-ideal synchronization circumstance, we studied the signal changes before...
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...
Time offset estimation is one of the main tasks of the initial ranging process in orthogonal frequency-division multiple access (OFDMA)-based network. Recently, the multiuser time offset estimation based on phase shift over adjacent subcarriers has been presented. This method can reduce the huge computation complexity of the timing recovery based on peak correlation searching of long PN codes. The...
Timing and frequency synchronization is the important task in receiver. In this paper, an efficient timing and carrier frequency offset (CFO) estimation algorithm for orthogonal frequency division multiple access/ time division duplexing (OFDMA/TDD) mode in IEEE 802.16-2004 standard (WiMAX) is represented. This method has high performance and jointly estimates timing error and CFO. The performance...
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 this paper a novel timing Synchronization method for Orthogonal Frequency Division Multiplexing (OFDM) systems is proposed. This method is based on the transmission of a training symbol at the transmitter and using symmetrical correlation between some parts of this training symbol in receiver. The proposed method has an impulse-like timing metric and makes it possible to estimate the correct timing...
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...
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...
In this paper we present a time delay estimation algorithm for known symbol padding (KSP) orthogonal frequency division multiplexing (OFDM) systems. The estimator exploits both the pilot symbols in the guard interval and on the pilot carriers, and takes the frequency selectivity of the fading channel into account. Our simulations indicate that the time delay estimator gives rise to only a small degradation...
This paper proposes a pilot-aided joint channel estimation and synchronization scheme for burst-mode orthogonal frequency division multiplexing (OFDM) systems over time- and frequency-selective (doubly selective) channels. Based on the basis expansion model (BEM) for representing doubly-selective channels, a least-square (LS) cost function of carrier frequency offset (CFO) and BEM coefficients is...
A fine time tracking system is presented for orthogonal frequency division multiplexing (OFDM) systems working in multipath fading channels. Due to the channel variability, coarse timing is the most common sampling synchronization level performed in these environments. However, in case of slow time variant channels, fine time tracking can help in some way to the channel equalization, improving the...
A joint estimation and compensation algorithm of the carrier frequency offset (CFO) and sampling clock offset (SCO) is proposed for orthogonal frequency division multiplexing (OFDM) systems under multipath fading channels. First, we propose the joint weighted least-squares (JWLS) algorithm with intercarrier interference (ICI) cancellation to enhance the accuracy of the CFO and SCO estimation. Next,...
Owing to SC-FDE (single carrier with frequency domain equalization) systems perform equalization in frequency domain, carrier frequency synchronization and timing synchronization are the most important preconditions. A novel synchronization method is proposed in this paper, which adopts new structure of training symbols and new calculation method. Simulation results demonstrate that the proposed method...
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