Ali Özgür Yilmaz

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—The iterative channel estimation and tracking problem is considered for time-varying frequency-flat fading multi-input multi-output (MIMO) systems. In order to jointly estimate and track the time-varying multi-antenna channel, the pilot symbol assisted modulation (PSAM) technique is generalized to the multi-antenna systems. By distributing the pilot(More)
—Parallel decodable turbo codes (PDTCs) are suitable for concurrent decoding and hence have low latency. Memory collision issue is an important problem met during parallel processing. In this article, we propose a collision free interleaver for parallel processing operations. The performance of PDTCs is analyzed with the proposed random interleaver(More)
It is known that rotated multidimensional constellations can be used effectively to achieve full-rate and full-diversity transmission in block fading channels. However, optimal decoding complexity is exponential with the number of fading blocks (or degrees of freedom). In this paper, we propose a reduced-complexity iterative receiver structure operating on(More)
—A low-complexity iterative channel estimation (ICE) algorithm is proposed with the promise of improved error performance. The new algorithm operates the LMS filter both in the forward and the backward directions along a block. The feedback from the decoder to the estimator is in the form of soft decisions. The pilot symbol assisted modulation (PSAM) is(More)
— We develop a technique to upper bound the point-to-point MIMO limited rate feedback (LRF) capacity under a wide class of vector quantization schemes. The upper bound turns out to be tight and can also be used to obtain an absolute upper bound by using a bounding distribution for Grassmannian beamforming. The bounding technique can be applied to other(More)
—GFDM and WCP-COQAM are amongst the candidate physical layer modulation formats to be used in 5G, whose claimed lower out-of-band (OOB) emissions are important with respect to cognitive radio based dynamic spectrum access solutions. In this study, we compare OFDM, GFDM and WCP-COQAM in terms of OOB emissions in a fair manner such that their spectral(More)
—Our main goal in this paper is to construct codes that can perform close to information-theoretic limits in time-varying channels. For this purpose, a new turbo-like code is first proposed for the block-fading channel which achieves the same error performance of a recently introduced blockwise concatenated code but with a lower complexity. The(More)