We consider Carrier Frequency Offset (CFO) estimation in the context of Multiple-Input Multiple-Output (MIMO) Orthogonal Frequency Division Multiplexing (OFDM) systems over noisy frequency selective wireless channels with both single and multi-user scenarios. We conceived a new approach for parameter estimation by discretizing the continuous-valued CFO parameter into a discrete set of bins and then invoked detection theory, analogous to the Minimum Bit-Error-Ratio (MBER) optimization framework for detecting the finite-alphabet received signal. Using this radical approach, we propose a novel CFO estimation method and study its performance using both analytical results and Monte-Carlo simulations. We obtain expressions for the variance of the CFO estimation error and the resultant BER degradation with single user scenario. Our simulations demonstrate that the overall BER performance of an MIMO-OFDM system using the proposed method is substantially improved for all the modulation schemes considered, albeit this is achieved at an increased complexity. , IEEE Transactions on Vehicular Technology 3 Rewriting (1) as,
Chemical bond activations mediated by Hbond interactions involving highly electronegative elements such as nitrogen and oxygen are powerful tactics in modern catalysis research. On the contrary, kindred catalytic regimes in which heavier, less electronegative elements such as selenium engage in H-bond interactions to co-activate CÀ Se σ-bonds under oxidative conditions are elusive. Traditional strategies to enhance the nucleofugality of selenium residues predicate on the oxidative addition of electrophiles onto Se II -centers, which entails the elimination of the resulting Se IV moieties. Catalytic procedures in which Se IV nucleofuges are substituted rather than eliminated are very rare and, so far, not applicable to carbon-carbon bond formations. In this study, we introduce an unprecedented combination of OÀ H•••Se H-bond interactions and single electron oxidation to catalytically generate Se III nucleofuges that allow for the formation of new CÀ C σ-bonds by means of a type I semipinacol process in high yields and excellent selectivity.
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