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The following topics are dealt with: VLSI; OFDM; embedded systems; filters; MIMO; cellular and integrated systems; media processing; Internet; image processing; network routing; QoS and resource allocation; network management; channel modelling and equalization; ad hoc networks; communication signal processing; WSN; channel estimation; WLAN and WWAN; coding and detection; security; UWB; cognitive...
In this paper, we derive the optimal carrier frequency offset (CFO) and channel estimator for OFDMA uplink based on joint maximum likelihood (ML) criterion. Direct implementation of the resultant estimation scheme is quite challenging due to the need of multi-dimensional exhaustive search in multi-CFO estimation. To solve this problem, a computationally efficient method using importance sampling technique...
Affine preceding superimposes training signals on linearly precoded data. It enhances symbol recovery and effectively identifies the frequency-selective fading channel. Previous works have shown its advantage over the standard time-multiplexed training. This paper considers orthogonal affine precoding for joint channel estimation and symbol detection in wireless MIMO-OFDM systems. Analytical and numerical...
In order to attain near-single user performance in uplink multicarrier code division multiple access (MC-CDMA) systems, multiuser detection (MUD) methods may be employed which rely on simultaneous estimation of the channel frequency response of multiple users. In this paper, performance of a MC-CDMA system employing minimum mean-square error (MMSE) MUD at receiver, is evaluated using two pilot symbol...
We address pilot-aided channel estimation for a flat-fading spatially-correlated MIMO system, which employing Uniform Linear Arrays(ULA) on dual side and working in sparse scattering (multipath) environment. In case of sparse scattering, channel matrix and spatial correlation of flat-fading MIMO systems are parameterized by structure of multipaths, which is represented as Direction of Arrivals(DOAs),...
In this paper we consider the use of M-QAM hierarchical constellations (quadrature amplitude modulation) combined with implicit pilots for the transmission of multicast and broadcast services in OFDM (orthogonal frequency division multiplexing) systems. This method of pilot transmission allows coherent detection at the receiver while avoiding the spectral degradation associated with the usual pilot...
We have investigated channel estimation with robust pilot symbol and spatial correlation information. Uncorrelative MIMO channel estimation based on ML criterion and pilot design scheme is given in this paper. Since spatial correlation cannot be avoided in real MIMO systems, we present new channel estimation which can make the best of spatial correlation information. The theoretic analysis and simulation...
Local positioning, particularly in indoor environments, poses challenges that are not faced by global and terrestrial positioning systems. Many a times, it is cost effective to build these localization schemes on the existing wireless local area networks (WLANs). In that direction, a time-of-arrival (TOA) estimation based on the "distorted template", which is obtained by convolving the clean...
In a recent study on blind multichannel identification, we presented a fast Fourier transform based algorithm, called the BI-FFT algorithm. The BI-FFT algorithm is capable of dealing with channel outputs of a very short length, which is of practical importance in communication applications where wireless channels involve high mobility. However, when the output sample size is relatively large, the...
To accommodate information streams with different data rates over a direct-sequence code-division multiple-access (DS-CDMA) network is required due to a large variety of information sources, such as voice, data, and images. This paper provides a novel adaptive blind estimating method for dual-rate DS-CDMA signals. The underlying idea is to estimate the channel and spatial signature by transforming...
Block transmission in wireless communications systems is very sensitive to Carrier Frequency Offset (CFO). In order to reduce the number of pilot symbols used in the estimation of rapidly-varying CFO it was proposed to use a truncated Taylor's series to predict the CFO, where the derivatives up to order d -1 of the series terms are recursively estimated with a d-order Kalman filter (KF). We propose...
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