The Infona portal uses cookies, i.e. strings of text saved by a browser on the user's device. The portal can access those files and use them to remember the user's data, such as their chosen settings (screen view, interface language, etc.), or their login data. By using the Infona portal the user accepts automatic saving and using this information for portal operation purposes. More information on the subject can be found in the Privacy Policy and Terms of Service. By closing this window the user confirms that they have read the information on cookie usage, and they accept the privacy policy and the way cookies are used by the portal. You can change the cookie settings in your browser.
Orthogonal frequency division multiplexing (OFDM) systems are highly sensitive to ICI caused by carrier frequency errors, so reliable time and frequency synchronization is crucial for the system. In this paper, a new method combined DA (PN estimation) and NDA (ML estimation) method to do frequency synchronization in frequency domain is proposed with large estimation range. Simulation and performance...
In this paper, an optimal signal-to-noise ratio (SNR) which is independent from correlation-interval and mobile speed is analyzed, which is on the basis of the channel auto-correlation Doppler shift estimation algorithm. And then an optimized SNR tracking (OSNRT) algorithm on the basis of Rake receiver under multi-path fading channel is proposed. The improved algorithm calculated Doppler shift by...
A new method is presented for blind parameter estimation of frequency hopping signals. According to the inner structure of frequency hopping signals, the three-parameter frequency-time atom is obtained from the unit windowed sine function by successive applications of scaling, time-shift and frequency-shift operators. On the base of these, a new matching pursuit based parameter estimation method of...
In this paper, we proposed a carrier frequency synchronization algorithm joint channel estimation for OFDM using block-type pilot. Each pilot symbol was composed of repeated short PN-sequences. By using this kind of pilot, the estimation of the carrier frequency offset (CFO) was performed into two steps, an acquisition step and a tracking step. During the acquisition step, the estimation range and...
In this paper, we propose a multiple CFOs(Carrier Frequency Offset) estimation and mitigation algorithm for the destination node in a cooperative OFDM(Orthogonal Frequency Division Multiplex) system. In a cooperative OFDM system, every relay node has a separate local oscillator, so that each relay-to-destination link has individual CFO parameter, so that the traditional estimation and mitigation algorithms...
In this paper, an improved expectation-maximum (IEM) frequency estimation algorithm is discussed, in which the unknown data symbols and the known pilot symbols are exploited jointly in a recursive way. Compared with the data-aided ML estimation, the IEM algorithm can improve the performance without increasing the number of pilot symbols, and is superior in performance to the non-data aided blind estimator...
A new algorithm based on pilots for the joint carrier frequency offset (CFO) and channel estimation of the uplink of MC-DS-CDMA systems is presented. As with the specially designed pilots, the inter-user interference (IUI) among user specific sub-matrix of received signal matrix in time domain does not exist any more, CFO and channel estimations are easily obtained for all users with single user CFO...
In this paper, a novel superimposed pilot based carrier frequency offset (CFO) estimator for Orthogonal frequency division multiplexing (OFDM) systems over frequency selective fading channel is proposed. Through utilizing the properly designed superimposed pilots, the CFO estimation can be resolved by implementing the fast Fourier transform (FFT) operation on the average values of the received signals...
This work explores theoretically the unique aspects of different signal processing stages in a Multi-Band (MB) Orthogonal Frequency Division Multiplexing (OFDM) based system in realistic Ultra-Wideband (UWB) channel. In the process of analysis, it emphasizes the significant aspects of signal processing steps in UWB receiver design comparing a narrow-band system. The analysis preliminary considers...
In this paper, we propose a joint carrier frequency offset (CFO) and channel estimation scheme based on the well known variable projection (VP) method for the uplink channel of orthogonal frequency division multiplexing (OFDM) systems. The CFOs and channel coefficients are estimated by minimizing the least-squares (LS) cost function through a numerical optimization technique. In each iteration, the...
The exact statistical models for the measurement phase noise in estimating the frequency and phase of a single sinusoid over the additive white Gaussian noise channel are derived. The a posteriori probability density function (PDF) and the a priori PDF of the phase noise derived are given by explicit, closed-form expressions that are valid for arbitrary signal-to-noise ratios. It is shown that as...
This paper presents the proposition of the tracking algorithm of the carrier frequency and sampling frequency offsets. The algorithm uses a phase difference between channel transfer function estimates computed for the same subcarrier of two successive OFDM symbols. Proposed solution was compared, by means of computer simulation, with similar non-data aided algorithm introduced in [1]. Both schemes...
A novel channel estimation scheme is proposed for coherent impulse radio ultra wideband (IR-UWB) system based on IEEE 802.15.4a specification. By extracting and utilizing the information on the frequency synchronization, the proposed channel estimation algorithm improves the receiver performance even under the restricted number of preamble symbols in IEEE 802.15.4a signal format. Simulation results...
This paper investigates the performance of a coherent receiver for ultra-wide-band Impulse Radio. Specifically, we suppose that the useful signal is affected by a dispersive channel and that the receiver collects also multiple access interference (MAI), while experiencing frequency drifts due to clock mis-alignments. Building upon a Gaussian mixture (GM) model for MAI, the receiver uses a space alternating...
In this paper, we propose a new algorithm for the carrier frequency offset (CFO) estimation of the uplink of multicarrier DS-CDMA (MC-DS-CDMA) systems. Firstly, our method exploits a new pilot scheme to obtain the approximation of the interested userpsilas signal from the composite signals on the user specific subcarrier in the receiver. Then the fast Fourier transform (FFT) operation is applied to...
In this work we present efficient channel estimation algorithms for wideband amplify-and-forward (AF) based relay networks which utilize a recently proposed transmission model. It is shown that all channels in the network from the source through the relays to the destination/receiver node can be blindly estimated up to a phase ambiguities vector which contains the phases of the direct source to destination...
We consider carrier frequency offset (CFO) estimation for single-carrier and single-user transmission over a frequency-selective channel. When training is solely devoted to frequency synchronization, it is important to design the training to optimize CFO estimation performance. In this paper we exhibit the training sequence that minimizes the Cramer-Rao bound associated with the carrier frequency...
We propose a new simple and accurate approach to estimate the Doppler spread which is a key parameter in the context of wireless communication systems. This new approach stems from the well known fact that the crosscorrelation of the channel is a weighted summation of monochromatic plane waves (or inverse Fourier transform of its power spectral density). In the case of Doppler spread, these plane...
The parallel time-interleaved structure is an effective way to achieve high sampling rate in most practical data acquisition systems. However, timing mismatch of this structure degrades the performance of the whole ADC system. For this reason, an estimation algorithm by the means of statistics is proposed in this paper, which could evaluate timing mismatch without any special calibration signal. Furthermore,...
Set the date range to filter the displayed results. You can set a starting date, ending date or both. You can enter the dates manually or choose them from the calendar.