Person: ACAR, YUSUF
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Dr. Öğr. Üyesi
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ACAR
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YUSUF
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Publication Metadata only Iterative Channel Estimation For Spatial Modulation Systems Over Fast Fading Channels(IEEE, 345 E 47Th St, New York, Ny 10017 Usa, 2014) Doğan, Hakan; Panayırcı, Erdal; ACAR, YUSUF; 237377; 41066; 10331Spatial Modulation (SM) based on the use of antenna indices to transmit information in addition to the conventional signal constellations has been recently proposed to solve practical problems encountered in MIMO systems. In the literature, estimation of CSI for SM systems is simply investigated by RLS for slow fading channels. However, iterative receivers that offer significant performance gains over a non- iterative when the total number of pilot is not sufficient and the channel is fast fading have not been investigated for SM based systems. In this paper, it shown that the RLS based receiver has a performance degradation for fast fading channels and a new iterative channel estimation techniques is proposed with the necessary signal model to enhance receiver performance for fast fading channels. Computer simulation results indicate that proposed iterative receiver has a significant performance advantage over the RLS based receiver for time-varying Rayleigh channels.Publication Metadata only Pilot symbol aided channel estimation for spatial modulation-OFDM systems and its performance analysis with different types of interpolations(Springer, 233 Spring St, New York, Ny 10013 USA, 2017-06) Doğan, Hakan; Panayırcı, Erdal; ACAR, YUSUF; 237377; 10331Spatial modulation orthogonal frequency division multiplexing (SM-OFDM) system has been recently proposed as an alternative for multiple-input multiple-output (MIMO)-OFDM systems to increase spectral efficiency by keeping a low-complexity implementation. In the literature, SM-OFDM systems assume a perfect channel state information (P-CSI) available at the receiver for coherent detection and the channel estimation problem is not considered. It is clear that the channel estimation is a critical issue on the performance of SM-OFDM systems. In this paper, a frame structure where pilot symbols are typically interspersed with data symbols among the sub-carriers to aid the channel estimation is considered. Then the pilot symbol aided channel estimation (PSA-CE) technique with different interpolations is proposed for the SM-OFDM systems. It is shown that in the proposed PSA-CE, equidistantly spaced pilot symbols allow to reconstruct the channel response by means of interpolation if the spacing of the pilots is sufficiently close to satisfy the sampling theorem. Linear, nearest neighbor, piecewise cubic Hermite and the low-pass interpolations are investigated to explore trade-off between complexity and performances. We show that the low pass interpolator yields better performance than the other interpolation techniques for selected cases such as higher order modulations. The results validate the potential of the proposed PSA-CE estimation applying to SM-OFDM systems.Publication Metadata only On channel estimation for spatial modulated systems over time-varying channels(Academic Press inc Elsevier Science, 525 B St, Ste 1900, San Diego, Ca 92101-4495 USA, 2015-02) Doğan, Hakan; Panayırcı, Erdal; ACAR, YUSUF; 237377; 10331Spatial Modulation (SM) has been proposed recently for multiple-input multiple-output (MIMO) systems to cope with the interchannel interference and to reduce the detection complexity as compared to the conventional MIMO systems. In SM system, the data symbols are transmitted by a randomly selected active antenna of a MIMO transmitter to the receiver through a wireless channel. The information is carried both by the data symbol from any signal constellation such as M-ary phase shift keying (M-PSK) or M-ary quadrature amplitude modulation (M-QAM), by the index of the selected antenna. The channel estimation is a critical process at the receiver during the coherent detection of the transmitted symbol and the antenna index, randomly selected. Recently, the channel estimation of channel for SM systems has been investigated by the recursive least square (RLS) algorithm for only quasi-static fading channels. In this paper, a novel channel estimation is proposed for SM systems in the presence of rapidly time-varying channels. The Bayesian mean square error (MSE) bound has been derived as a benchmark and the performance of the proposed approaches is studied in terms of MSE and bit-error rate (BER). Computer simulation results have confirmed that the proposed iterative channel estimation technique has significant BER/MSE performance advantages compared with existing channel estimation algorithm proposed earlier in the literature. (C) 2014 Elsevier Inc. All rights reserved.