Mihai Enescu

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In this paper we address the problem of joint channel and frequency offset estimation and tracking in multiple-input multiple-output (MIMO) OFDM systems for mobile users. The proposed method stems from extended Kalman filtering and is suitable for time-frequency-space selective channels. Separate offset for each MIMO channel branch is considered because of(More)
In this paper we address the problem of channel estimation for Multiple-Input Multiple-Output OFDM systems for mobile users. Channel tracking and equalization method stemming from Kalman filtering is proposed for time-frequency selective channels. Tracking of MIMO channel matrix is performed in time-domain and equalization in frequency domain. Computational(More)
In this paper we address the problem of channel parameter estimation and tracking for multiple-input-multiple-output (MIMO) OFDM systems where the channels are spatially correlated. Starting from the OFDM transmission model with independent MIMO channels, we derive a state-space model that accounts for a spatial correlation structure. An advanced spatial(More)
This paper is analyzing the impact of some practical issues on SVD-based downlink precoding in TDD systems. Future MIMO OFDM based systems promise high throughput and robust transmission. Downlink precoding has been considered as one strong candidate to realize such benefits. However most previous research on this technique is based on ideal assumptions and(More)
This article addresses the problem of blind source separation from time-varying noisy mixtures using a state variable model and recursive estimation. An estimate of each source signal is produced real time at the arrival of new observed mixture vector. The goal is to perform the separation and attenuate noise simultaneously, as well as to adapt to changes(More)
In this article, we present a practical coordinated multipoint (CoMP) system for LTE-Advanced. In this CoMP system, cooperation is enabled for cell-edge users via dynamic switching between the normal single-cell operation and CoMP. We first formulate a general CoMP system model of several CoMP schemes. We then investigate a practical finite-rate feedback(More)
This paper proposes a combined frequency and time domain channel estimation method for MIMO OFDM systems. Initial channel estimation is performed by first estimating the channel response in frequency domain, exploiting a set of dedicated pilot carriers, followed by an interpolation step. In order to reduce the interpolation error and improve the bit error(More)
In this paper we study the performance of linear interference suppression receivers which estimate the interference covariance either from the data symbols or from the reference symbols. For numerical radio system-level simulation purposes, receiver algorithm models are proposed which take into account practical estimation losses caused by the channel and(More)