Michal Simko

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—In this paper, hardware implementation aspects of the channel estimator in 3GPP LTE terminals are investigated. A channel estimation ASIC, which handles the real-time channel estimation, is presented. Compared to traditional correlator-based channel estimators, the channel estimator presented boosts the throughput at feasible silicon cost by adopting a(More)
—Cellular networks are an essential part of todays communication infrastructure. The ever-increasing demand for higher data-rates calls for a close cooperation between researchers and industry/standardization experts which hardly exists in practice. In this article we give an overview about our efforts in trying to bridge this gap. Our research group(More)
Nowadays, most wireless communication systems employ coherent demodulation on the receiver side. Under this circumstance, part of the available transmission resource is reserved and utilized for channel estimation, referred to as pilot symbols. In recent standards, for example long-term evolution (LTE), a certain adjustment is allowed for the power radiated(More)
—The UMTS Long Term Evolution (LTE) allows the pilot symbol power to be adjusted with respect to that of the data symbols. Such power increase at the pilot symbols results in a more accurate channel estimate, but in turn reduces the amount of power available for the data transmission. In this paper, we derive optimal pilot symbol power allocation based on(More)
—In scenarios with time-varying channels such as intelligent traffic systems or high speed trains, the orthogonality between subcarriers in orthogonal frequency division multiplexing (OFDM) is destroyed leading to inter-carrier interference (ICI). In the literature, ICI equalization algorithms have been proposed; however, they assume perfect channel(More)
In this paper, we develop several increasingly tight and restrictive performance bounds for OFDM based MIMO wireless communication systems. Starting with channel capacity as the ultimate upper bound on the throughput, step by step we develop tighter bounds on the practically achievable throughput by incorporating typical design constraints. The presented(More)
—In this paper, we present an Approximate Linear Minimum Mean Square Error (ALMMSE) fast fading channel estimator for Orthogonal Frequency Division Multiplexing (OFDM). The ALMMSE channel estimator utilizes the knowledge of the structure of the autocorrelation matrix given by the Kronecker product between the time correlation matrix and the frequency(More)
—In this paper, we derive a closed-form expression for the Bit Error Probability (BEP) of an orthogonal frequency-division multiplexing system that utilizes pilot-symbol-aided channel estimation. We assume Rayleigh fading, additive white Gaussian noise, and that the interpolation is linear but otherwise completely arbitrary. It is shown that the minimum(More)
—In this paper, we compare the performance of the LTE rate matcher for different code rates when segmentation occurs. We present that, for certain cases of segmentation where the different segments are of dissimilar size, the rate applied to each segment may be different and thus degraded overall performance may occur. We show how a simple method which(More)