Journal ArticleDOI
EM-Based Adaptive Frequency Domain Estimation of Doppler Shifts with CRLB Analysis for CDMA Systems
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TLDR
A frequency domain equalizer (FDE) based receiver architecture is developed to exploit Doppler diversity in the frequency domain and demonstrate that this receiver architecture features a low complexity while still achieving a good performance compared with traditional CDMA receivers.Abstract:
Combating time and frequency selectivity in wireless channels is one of the most challenging tasks in next generation wireless networks. In this paper, we propose an adaptive estimation algorithm to estimate Doppler shifts in a direct sequence code division multiple access (DS-CDMA) radio system with multiple Doppler subpaths. By modeling doubly selective channels using a basis expansion model (BEM), an expectation-maximization (EM) algorithm based adaptive estimation method is developed to extract accurate Doppler shift information. The Cramer-Rao lower bound (CRLB) analysis is conducted to study the performance bound of the proposed estimation algorithm. Based on the estimated Doppler shift results, a frequency domain equalizer (FDE) based receiver architecture is developed to exploit Doppler diversity in the frequency domain. Our analysis and simulation results demonstrate that this receiver architecture features a low complexity while still achieving a good performance compared with traditional CDMA receivers.read more
Citations
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Journal ArticleDOI
Joint-Detection for Doppler-Shift Acquisition in Space Communications
TL;DR: A joint-detection scheme, which uses multiple combination periods to narrow the search range for Doppler-shift acquisition, is firstly proposed to increase the acquisition probability and the theoretical analysis and simulations results are presented to evaluate this scheme.
Journal ArticleDOI
Search-Range-Correction-Based Doppler Shift Acquisition for Space Communications
TL;DR: Simulations results show that the proposed scheme can obtain much higher acquisition probability of Doppler shift, compared with existing acquisition schemes, including the fast Fourier transform (FFT), time-frequency, and single SRC using two combination periods.
Journal ArticleDOI
Nondata-Aided Doppler Frequency Estimation for OFDM Systems Over Doubly Selective Fading Channels
TL;DR: A time-domain nondata-aided maximum-likelihood (ML) estimation of Doppler frequency for orthogonal frequency-division multiplexing (OFDM) over doubly selective fading channels with the Clarke–Jakes–Doppler spectrum is introduced.
Journal ArticleDOI
UKF-Based Iterative Channel Estimation Using Two-Dimensional Block Spread Coding for Uplink Transmission in Multicarrier CDMA Networks
TL;DR: The challenges to CE in 2-D block spread coding networks are demonstrated through analytical derivation and an unscented Kalman-filter (UKF)-based iterative CE is proposed for uplink transmission in multicarrier CDMA networks.
Proceedings ArticleDOI
Doppler-aided channel estimation in satellite communication base on frequency-domain equalization
TL;DR: A algorithm is proposed which padding zeros in received signal in time-domain, then use energy sorting to eliminate severals of largest component in frequency domain channel estimation, and adopt doppler shift to further revised the channel parameter estimation.
References
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TL;DR: An overview of the fundamental principles behind modeling and simulation of communication systems is presented, which include Monte Carlo simulation, discrete time representation, signals, and random-number generation.
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Basis expansion models and diversity techniques for blind identification and equalization of time-varying channels
TL;DR: Novel algorithms are developed for blind identification, direct, zero-forcing equalization and minimum mean square error (MMSE) equalization by combining channel diversity with temporal (fractional sampling) and/or spatial diversity which becomes available with multiple receivers.
Journal ArticleDOI
Jakes fading model revisited
TL;DR: Modifications are proposed to the Jakes fading model for simulating time-correlated Rayleigh fading waveforms which solve the problem of difficult to create multiple uncorrelated fadingWaveforms.