Browsing by Author "Hasan, M."

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Open Access
Efficient channel estimation for reconfigurable MIMO antennas: training techniques and performance analysis
(Institute of Electrical and Electronics Engineers Inc., 2017) Bahceci, I.; Hasan, M.; Duman, T. M.; Cetiner, B. A.
Multifunctional and reconfigurable multiple-input multiple-output (MR-MIMO) antennas are capable of dynamically changing the operation frequencies, polarizations, and radiation patterns, and can remarkably enhance system capabilities. However, in coherent communication systems, using MR-MIMO antennas with a large number of operational modes may incur prohibitive complexity due to the need for channel state estimation for each mode. To address this issue, we derive an explicit relation among the radiation patterns for the antenna modes and the resulting channel gains. We propose a joint channel estimation/prediction scheme where only a subset of all the antenna modes is trained for estimation, and then, the channels associated with the modes that are not trained are predicted using the correlations among the different antenna modes. We propose various training mechanisms with reduced overhead and improved estimation performance, and study the impact of channel estimation error and training overhead on the MR-MIMO system performance. We demonstrate that one can achieve significantly improved data rates and lower error probabilities utilizing the proposed approaches. For instance, under practical settings, we observe about 25% throughput increase or about 3-dB signal-to-noise ratio improvement under the same training overhead with respect to non-reconfigurable antenna systems.
Open Access
Inborn errors of OAS–RNase L in SARS-CoV-2–related multisystem inflammatory syndrome in children
(American Association for the Advancement of Science (AAAS), 2022-12-20) Lee, D.; Pen, J. L.; Yatim, A.; Dong, B.; Aquino, Y.; Ogishi, M.; Pescarmona, R.; Talouarn, E.; Rinchai, D.; Zhang, P.; Perret, M.; Liu, Z.; Jordan, L.; Bozdemir, S. E.; Bayhan, G. I.; Beaufils, C.; Bizien, L.; Bisiaux, A.; Lei, W.; Hasan, M.; Chen, J.; Gaughan, C.; Asthana, A.; Libri, V.; Luna, Joseph M.; Jaffré, Fabrice; Hoffmann, H.; Michailidis, E.; Moreews, M.; Seeleuthner, Y.; Bilguvar, K.; Mane, S.; Flores, C.; Zhang, Y.; Arias, A. A.; Bailey, R.; Schlüter, A.; Milisavljevic, B.; Bigio, B.; Voyer, T. L.; Materna, M.; Gervais, A.; Moncada-Velez, M.; Pala, F.; Lazarov, T.; Levy, R.; Neehus, A.; Rosain, J.; Peel, J.; Chan, Y.; Morin, M.; Pino-Ramirez, R. M.; Belkaya, Serkan; Lorenzo, L.; Anton, J.; Delafontaine, S.; Toubiana, J.; Bajolle, F.; Fumadó, V.; DeDiego, M. L.; Fidouh, N.; Rozenberg, F.; Pérez-Tur, J.; Chen, S.; Evans, T.; Geissmann, F.; Lebon, P.; Weiss, S. R.; Bonnet, D.; Duval, X.; Cohort§, C.; Effort, C.; Pan-Hammarström, Q.; Planas, A. M.; Meyts, I.; Haerynck, F.; Pujol, A.; Sancho-Shimizu, V.; Dalgard, C.; Bustamante, J.; Puel, A.; Boisson-Dupuis, S.; Boisson, B.; Maniatis, T.; Zhang, Q.; Bastard, P.; Notarangelo, L.; Béziat, V.; Diego, R.; Rodriguez-Gallego, C.; Su, H. C.; Lifton, R. P.; Jouanguy, E.; Cobat, A.; Alsina, L.; Keles, S.; Haddad, E.; Abel, L.; Belot, A.; Quintana-Murci, L.; Rice, C. M.; Silverman, R. H.; Zhang, S.; Casanova, J.
Multisystem inflammatory syndrome in children (MIS-C) is a rare and severe condition that follows benign COVID-19. We report autosomal recessive deficiencies of OAS1, OAS2, or RNASEL in five unrelated children with MIS-C. The cytosolic double-stranded RNA (dsRNA)-sensing OAS1 and OAS2 generate 2'-5'-linked oligoadenylates (2-5A) that activate the single-stranded RNA-degrading ribonuclease L (RNase L). Monocytic cell lines and primary myeloid cells with OAS1, OAS2, or RNase L deficiencies produce excessive amounts of inflammatory cytokines upon dsRNA or severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) stimulation. Exogenous 2-5A suppresses cytokine production in OAS1-deficient but not RNase L-deficient cells. Cytokine production in RNase L-deficient cells is impaired by MDA5 or RIG-I deficiency and abolished by mitochondrial antiviral-signaling protein (MAVS) deficiency. Recessive OAS-RNase L deficiencies in these patients unleash the production of SARS-CoV-2-triggered, MAVS-mediated inflammatory cytokines by mononuclear phagocytes, thereby underlying MIS-C.
Open Access
Mode shift keying for reconfigurable MIMO antennas: performance analysis and antenna design
(IEEE, 2019-01) Hasan, M.; Bahçeci, İsrafil; Towfiq, Md. A.; Duman, Tolga M.; Çetiner, B. A.
Space-shift-keying (SSK) and spatial modulation (SM) enable multiple antenna transmission systems to convey information on antenna indices. While SSK/SM helps reduce the number of radio frequency (RF) chains, large numbers of antennas and low spatial correlations are required to achieve high data rates. This work investigates the use and design of multifunctional reconfigurable antennas (MRAs) for SSK/SM based transmission where a single-element MRA generates large numbers of modes. To enhance legacy SSK/SM performance while reducing RF hardware complexity, we propose single- and multi-carrier antenna mode-shift keying (MoSK) and mode modulation (MoM) schemes facilitated by MRAs. Based on an error probability analysis, we determine criteria for MRA design and mode set selection suitable for MoSK/MoM. We also develop two MRA designs and investigate their performances over Rayleigh fading channels. We argue that by creating MRA modes with low pattern correlations, channel correlations can be reduced to improve the detection performance. Extensive simulations demonstrate that MoSK/MoM performance exceeds that of SSK/SM along with significant complexity reduction. For instance, a single-carrier MoSK/MoM using a single MRA with 8 modes achieves about 2 dB gain compared to legacy SSK/SM requiring 8 antennas, and by multi-carrier MoSK/MoM using 4 subcarriers, an MRA with 32 modes can attain an error rate performance comparable to this single-carrier system.