In this paper, we propose a new channel estimation algorithm for low earth orbit satellite digital communications. Low earth orbit satellite channels impart severe spreading in delay and Doppler on the transmitted signal. We model the channel as a tapped-delay-line lter with time-varying complex coeecients. The time evolution of the taps is described by an auto-regressive model. A coupled lter ...

This paper considers maximum likelihood (ML) estimation of time-varying finite impulse response (FIR) channels. The channel is modelled as a tapped-delay line filter with complex coefficients. The complexity of the likelihood function and the large number of parameters to be estimated, make analytical maximization of the likelihood function infeasible. Taking the structure of the channel tap co...

This paper evaluates the performance of a multi-user MIMO detector for various channel models. An implementation of the COST 259 channel model is used in comparison to a simple stochastic tapped delay line model. The performance of the receiver using the various channel models is shown for varying number of users and varying antenna spacings. The receiver has no knowledge about the detailed aut...

Techniques for modeling and simulating the underlying channel-PHY play an essential role in understanding network protocol and application behavior of tactical data link (TDL). Inappropriate modeling and simulation of channel-PHY make the results incredibility. In this paper a model architecture of channel and physical layer is described in NS-2 (Network Simulator version 2). The five key techn...

This paper presents active control of acoustic noise using radial basis function (RBF) networks and its digital signal processor (DSP) real-time implementation. The neural control system consists of two stages: first, identification (modeling) of secondary path of the active noise control using RBF networks and its learning algorithm, and secondly neural control of primary path based on neural ...

We experimentally demonstrate a reconfigurable optical converter/encoder for quadrature amplitude modulated (QAM) signals. The system utilizes nonlinear wavelength multicasting, conversion-dispersion delays, and simultaneous nonlinear multiplexing and sampling. We show baud rate tunability (31 and 20 Gbaud) and reconfigurable conversions from lower-order QAM signals to higher-order QAM signals ...

Multipath fading is one of the major practical concerns in wireless communications. Multipath problem always exists in mobile environment, especially for mobile unit which is often embedded in its surroundings. A time-variant tapped line delay model has been used for multipath fading in a wide-band spread spectrum mobile system. In this paper, we proposed to use the detection and estimation tec...

This paper presents exact analytical results of the LMS performances on correlated data vectors. The case addressed here is of data vectors constructed from a tapped delay line. While the results are for the two-dimensional case, they do provide indications of the effect this structure of data vectors, so common to LMS applications, has on LMS performance. They show conclusively the possibility...

We experimentally demonstrate a reconfigurable optical tapped delay line in conjunction with coherent detection to search multiple patterns among quadrature phase shift keying (QPSK) symbols in 20 Gbaud data channel and also to equalize 20 and 31 Gbaud QPSK, 20 Gbaud 8 phase shift keying (PSK), and 16 QAM signals. Multiple patterns are searched successfully on QPSK signals, and correlation peak...