For indoor Wireless Local Area Networks (WLANs) planning, an accurate propagation modelling is required. Semi-empirical models represent an efficient approach to the indoor channel coverage prediction. Their parameters are estimated from measurement results. In the case called ill-conditioned, the Least Square (LS) regression leads to a bad estimation of the model parameters and thus to numeric...

Multi-user multi-input multi-output (MU-MIMO) transmission is being provided by in the uplink of the 3GPP LTE and LTE-A standards. To minimize the interference among different antenna channels care must be exercised in channel estimation according to the property of reference signals (RSs). When user equipments (UEs) are allocated narrow transmission bands channel estimation methods may yield r...

Underwater acoustic channel (UAC) is one of the most challenging communication channels in the world, owing to its complex multi-path and absorption as well as variable ambient noise. Although adaptive equalization could effectively eliminate the inter-symbol interference (ISI) with the help of training sequences, the convergence rate of equalization in sparse UAC decreased remarkably. Besides,...

Ultra wideband (UWB) communication is mainly used for short range of communication in wireless personal area networks. Orthogonal Frequency Division Multiplexing (OFDM) is being used as a key physical layer technology for Fourth Generation (4G) wireless communication. OFDM based communication gives high spectral efficiency and mitigates Inter-symbol Interference (ISI) in a wireless medium. In t...

In this paper, we have evaluated various methods of time-frequency-selective fading channels estimation in OFDM system and some of them improved under time varying conditions. So, these different techniques will be studied through different algorithms and for different schemes of modulations (16 QAM, BPSK, QPSK,...). Channel estimation gathers different schemes and algorithms, some of them are ...

---Orthogonal Frequency Division Multiplexing (OFDM) has been recently applied widely in wireless communication systems, due to its high data rate, transmission capability with high bandwidth, efficiency and its robustness to multipath delay .Channel estimation is an essential problem in OFDM system. Pilot-aided channel estimation has been used; a good choice of the pilot pattern should match t...

Coastal global navigation satellite system (GNSS) stations equipped with a standard geodetic receiver and antenna enable water level measurement using the GNSS interferometry reflectometry (GNSS-IR) technique. By GNSS-IR, vertical distance between reflector surface (e.g., surface) can be obtained in (height) reference frame. In this study, signal-to-noise ratio (SNR) data from four selected ove...

We analyzed the effect of time and frequency domain windowing, or weighting, of the transmitted signal for least squares (LS) and minimum mean-square error (MMSE) estimators when the channel is time-variant. We considered the estimation error for different windows and we found that the windows can be selected independently. We explained the performance of the estimators with the help of the rad...

In this paper, we propose a differential evolution (DE) algorithm for optimizing the placement and power of the pilot tones that are utilized by a least square (LS) algorithm for channel estimation in multipleinput and multiple-output orthogonal frequency-division multiplexing (MIMO-OFDM) systems. Computer simulations demonstrated that the performance of the LS algorithm was increased by optimi...