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In this paper, we propose a novel sampling frequency offset estimation algorithm to improve the performance of the practical intensity-modulation and direction-detection (IMDD)-based OFDM system. For this scheme, only OFDM symbol is used, which reduce the complexity of implement in practical system. And, by taking the relationship of phase rotating of subcarriers into account, we successfully estimate...
This paper proposes a novel algorithm for Time of Arrival (ToA) estimation in Orthogonal Frequency Division Multiplexing (OFDM) systems. The algorithm performs the estimation starting from the channel frequency samples, in a fully opportunistic way when some known reference signals are already available for operations different from ToA estimation itself. The developed solution, named Difference-Based...
A joint timing offset (TO) and frequency offset (FO) estimation method based on Radon-Wigner transform (RWT) is first proposed for coherent optical orthogonal frequency-division multiplexing (CO-OFDM) systems. The result shows that the timing and frequency synchronization performance of the proposed method are both better than the Schmidl & Cox method and fractional Fourier transform (FrFT) algorithm...
The cognitive radio (CR) have been proposed to improve spectral efficiency and to meet growing demands for higher data rates in mobile communications and satellite communications. In this paper, we propose a blind estimation algorithm for a secondary user to estimate transmission parameters of the primary signal in an OFDM overlay system, using only the available fast Fourier transform (FFT) component...
A constant modulus algorithm-(CMA) based carrier frequency offset estimation method for coherent optical orthogonal frequency division multiplexing (CO-OFDM) system is proposed. Theoretical analysis and simulation results indicate that the frequency offset estimation range of the proposed algorithm can achieve [−5.9, +5.9] GHz, and the mean normalized estimation error can be kept under 0.001 even...
The downlink positioning method specified by 3GPP is a part of LTE location service. The method utilizes the time difference of Positioning Reference Signal (PRS) for ranging, therefore time delay estimation of PRS is a fundamental question in the method. A conventional algorithm relies on time correlation however faces challenges in multipath channel. For OFDM signal, Multiple Signal Classification...
In this paper, we design a novel training symbol structure to estimate in-phase/quadrature (IQ) mismatch. Based on this structure the estimation method is deduced in frequency domain which can achieve the estimation of IQ mismatch and channel distortion independently and improve the system performance obviously. Numerical simulation shows that the proposed method has better system BER performance...
Phase noise compensation plays an indispensable role in realizing the potential of orthogonal frequency division multiplexing (OFDM) for high-data-rate communications. Due to various heuristics employed to deal with the particular properties of phase noise, the existing approaches are still performance-limited in terms of accuracy and computational cost. In this paper, we focus on channel estimation...
In this paper, the algorithms of combining channel estimation with CFO estimation are studied for mobile OFDM system. The comb-type pilot is used for channel estimation. There are some known algorithms for channel estimation such as LS (Least Square), Minimum Mean Square Error (MMSE), some adaptive estimators such as Kalman Filter, Extended Kalman Filter… To enhance performance, we modified the algorithm...
Vital sign (e.g., breathing rate) monitoring has become increasingly more important because it can offer useful clues to medical conditions such as sleep disorders or anomalies. There is a compelling need for technologies that enable contact-free, easy deployment, and long-term vital sign monitoring for healthcare. In this paper, we present a SonarBeat system to leverage a phase based active sonar...
The L-Band Digital Aeronautical Communication System (LDACS) is a typical pilot-aided orthogonal frequency division multiplexing (OFDM) communication system. With the performance of LDACS in the Unmanned Aerial Vehicle (UAV) over-water channel, the pilot is redesign based on Zadoff-Chu (ZC) sequence. The new periodic ZC-pilot could reduce the effects of noise by correlated calculation. Based on new...
Using OMP algorithm for time-delay detecting and apply BEM based on comb-type pilot for channel estimation is the most commonly used method for sparse time-frequency doubly-selective channels, but the channel estimation performance will decrease sharply when the number of channel paths is large, and this method need to obtain the channel sparsity as prior information in advance. In this paper, a novel...
The estimation of symbol timing offset (STO) is an important issue for orthogonal frequency division multiplexing (OFDM) systems. In the literature, a variety of STO estimation methods have been proposed. In this paper, we propose a new blind STO estimation for OFDM systems with constant modulus (CM) constellation. The proposed estimator can estimate STO with only one OFDM symbol. Besides, a low complexity...
We propose a non-pilot aided sampling frequency offset (SFO) estimation algorithm in Multi-IFoF fronthaul with estimation error below 12ppb under SFO range from −100ppm to 100ppm and high robustness at received optical power as low as − 27dBm.
Satellite precision formation flying (PFF) is a concept in which multiple spacecraft communicate via an inter-satellite link (ISL) and cooperate to achieve the goal of a single, more complex satellite. This enables the creation of virtual scientific structures such as interferometers or imagers that would not be deployable in space because of their physical dimensions. PFF requires precise knowledge...
Quadrature downconversion impairments should be taken into account and compensated to the increasing of the Direct Conversion Receiver (DCR) reception quality. DC-offset and I/Q-imbalance are fitted into this group. Experimental estimation of two relatively simple compensation methods for the indicated drawbacks is reviewed in the paper. Energy efficiency and computational complexity estimation are...
This work proposes a novel authentication method for identifying Unmanned Aerial Vehicles (UAVs) based on a channel-tap power. A ground control station utilized the channel-tap power as a radio-frequency fingerprint (RFF) to directly detect UAVs via physical (PHY) layer. The proposed authentication method uses the Neyman-Pearson test to discriminate between two UAVs, UAVI and UAVA, which are controlled...
In this paper, we propose a new technique for synchronization and channel estimation in M-QAM OFDM radio over fiber (RoF) system by using constant amplitude zero auto-correlation (CAZAC) sequence based training preamble. Delay and correlate method is used to identify the training sequence in the received signal vector and to correct the symbol timing offset. For an optimum demodulation of OFDM signal,...
Channel estimation is one of the most important parts in current mobile communication systems. Among the huge contributions in channel estimation studies, the discrete Fourier transform (DFT)-based channel estimation has attracted lots of interests since it can not only be easily implemented but also have acceptable performance in practical systems. In this paper, we propose an improved DFT-based...
This paper proposes a channel estimation and equalization methods for a transmit diversity system of using time domain training sequence inserted orthogonal frequency division multiplexing (TS-OFDM) signal in higher time-varying fading channels. The salient feature of the proposed channel impulse response (CIR) estimation method for the transmit diversity system with a space frequency block coding...
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