An Adaptive Conditional Zero-Forcing Decoder with Full-diversity, Least Complexity and Essentially-ML Performance for STBCs

A low complexity, essentially-ML decoding technique for the Golden code and the 3 antenna Perfect code was introduced by Sirianunpiboon, Howard and Calderbank. Though no theoretical analysis of the decoder was given, the simulations showed that this decoding technique has almost maximum-likelihood (ML) performance. Inspired by this technique, in this paper we introduce two new low complexity decoders for Space-Time Block Codes (STBCs) - the Adaptive Conditional Zero-Forcing (ACZF) decoder and the ACZF decoder with successive interference cancellation (ACZF-SIC), which include as a special case the decoding technique of Sirianunpiboon et al. We show that both ACZF and ACZF-SIC decoders are capable of achieving full-diversity, and we give sufficient conditions for an STBC to give full-diversity with these decoders. We then show that the Golden code, the 3 and 4 antenna Perfect codes, the 3 antenna Threaded Algebraic Space-Time code and the 4 antenna rate 2 code of Srinath and Rajan are all full-diversity ACZF/ACZF-SIC decodable with complexity strictly less than that of their ML decoders. Simulations show that the proposed decoding method performs identical to ML decoding for all these five codes. These STBCs along with the proposed decoding algorithm outperform all known codes in terms of decoding complexity and error performance for 2,3 and 4 transmit antennas. We further provide a lower bound on the complexity of full-diversity ACZF/ACZF-SIC decoding. All the five codes listed above achieve this lower bound and hence are optimal in terms of minimizing the ACZF/ACZF-SIC decoding complexity. Both ACZF and ACZF-SIC decoders are amenable to sphere decoding implementation.Comment: 11 pages, 4 figures. Corrected a minor typographical erro

Full-Rate, Full-Diversity, Finite Feedback Space-Time Schemes with Minimum Feedback and Transmission Duration

In this paper a MIMO quasi static block fading channel with finite N-ary delay-free, noise-free feedback is considered. The transmitter uses a set of N Space-Time Block Codes (STBCs), one corresponding to each of the N possible feedback values, to encode and transmit information. The feedback function used at the receiver and the N component STBCs used at the transmitter together constitute a Finite Feedback Scheme (FFS). Although a number of FFSs are available in the literature that provably achieve full-diversity, there is no known universal criterion to determine whether a given arbitrary FFS achieves full-diversity or not. Further, all known full-diversity FFSs for T<N_t where N_t is the number of transmit antennas, have rate at the most 1. In this paper a universal necessary condition for any FFS to achieve full-diversity is given, using which the notion of Feedback-Transmission duration optimal (FT-Optimal) FFSs - schemes that use minimum amount of feedback N given the transmission duration T, and minimum transmission duration given the amount of feedback to achieve full-diversity - is introduced. When there is no feedback (N=1) an FT-optimal scheme consists of a single STBC with T=N_t, and the universal necessary condition reduces to the well known necessary and sufficient condition for an STBC to achieve full-diversity: every non-zero codeword difference matrix of the STBC must be of rank N_t. Also, a sufficient condition for full-diversity is given for the FFSs in which the component STBC with the largest minimum Euclidean distance is chosen. Using this sufficient condition full-rate (rate N_t) full-diversity FT-Optimal schemes are constructed for all (N_t,T,N) with NT=N_t. These are the first full-rate full-diversity FFSs reported in the literature for T<N_t. Simulation results show that the new schemes have the best error performance among all known FFSs.Comment: 12 pages, 5 figures, 1 tabl

Asymptotically-Optimal, Fast-Decodable, Full-Diversity STBCs

For a family/sequence of STBCs $\mathcal{C}_1,\mathcal{C}_2,\dots$, with increasing number of transmit antennas $N_i$, with rates $R_i$ complex symbols per channel use (cspcu), the asymptotic normalized rate is defined as $\lim_{i \to \infty}{\frac{R_i}{N_i}}$. A family of STBCs is said to be asymptotically-good if the asymptotic normalized rate is non-zero, i.e., when the rate scales as a non-zero fraction of the number of transmit antennas, and the family of STBCs is said to be asymptotically-optimal if the asymptotic normalized rate is 1, which is the maximum possible value. In this paper, we construct a new class of full-diversity STBCs that have the least ML decoding complexity among all known codes for any number of transmit antennas $N>1$ and rates $R>1$ cspcu. For a large set of $\left(R,N\right)$ pairs, the new codes have lower ML decoding complexity than the codes already available in the literature. Among the new codes, the class of full-rate codes ($R=N$) are asymptotically-optimal and fast-decodable, and for $N>5$ have lower ML decoding complexity than all other families of asymptotically-optimal, fast-decodable, full-diversity STBCs available in the literature. The construction of the new STBCs is facilitated by the following further contributions of this paper:(i) For $g > 1$, we construct $g$-group ML-decodable codes with rates greater than one cspcu. These codes are asymptotically-good too. For $g>2$, these are the first instances of $g$-group ML-decodable codes with rates greater than $1$ cspcu presented in the literature. (ii) We construct a new class of fast-group-decodable codes for all even number of transmit antennas and rates $1 < R \leq 5/4$.(iii) Given a design with full-rank linear dispersion matrices, we show that a full-diversity STBC can be constructed from this design by encoding the real symbols independently using only regular PAM constellations.Comment: 16 pages, 3 tables. The title has been changed.The class of asymptotically-good multigroup ML decodable codes has been extended to a broader class of number of antennas. New fast-group-decodable codes and asymptotically-optimal, fast-decodable codes have been include

Ethyl 4-(dimethyl­amino)benzoate

Mol­ecules of the title compound, C11H15NO2, are essentially planar (r.m.s. deviation = 0.035 Å) and are linked into a chain along the a axis by weak C—H⋯O hydrogen bonds

SYNTHESIS, CHARACTERIZATION, ANTI-MICROBIAL, ANTI-CANCER, AND ANTI-OXIDANT ACTIVITY OF NOVEL 1-(NAPHTHALEIN 2-YL OXY)(PHENYL)(METHYL) THIOUREA MANNICH BASE AND ITS METAL COMPLEXES

ABSTRACT Objective: Mannich bases of 2-naphthol are predominantly popular in metal-mediated and ligand-accelerated catalysis of enantioselective carbon-carbon bond formation. Since these compounds have multiple centre for chelation with metal ions, they are likely to be potent inhibitors of metallo-enzymes. A number of pharmaceutical and agricultural agents have a naphthalein frame work. Our present study focuses on the synthesis of Mannich base derived from the condensation of 2-naphthol, benzaldehyde and thiourea and its metal complexes and their biological activities. Methods: The ligand 1-(naphthalein -2-yloxy )(phenyl)(methyl) thiourea (BNBTU) was synthesized by Mannich condensation reactionÂ&nbsp; between 2- naphthol, benzaldehyde and thiourea in 1:1:1 molar ratio. Mn(II), Co(II), Ni(II), Cu(II)Â&nbsp; and Zn(II) complexes of the new Mannich base BNBTU have been synthesized. Results: The anti-bacterial activity of the ligand and all the metal complexes leads to the conclusion that most of the complexes were found to have activities against E.coliÂ&nbsp;Â&nbsp;Â&nbsp; and B. subtilis. The cytotoxic effects of the newly synthesized ligand have been found good inhibition activity against the cancer cell line. Further the ligand and the metal complexes have been screened for their fungicidal and anti-oxidant properties and they are found to be significantly active. Conclusion: The ligand 1-(naphthalein -2-yloxy )(phenyl)(methyl) thiourea (BNBTU) has shown as one of the novel ligand and its coordination with transition metals exhibited enhanced biological activity

A handy tool for forecasting population to aid estimation of water demand

1587-1592Estimation of demographic variations for societal or infrastructural development policies requires accurate prediction of futuristic population for a given locality. Economic viability as well as sustainability at large, of the engineering designs in urban development activities depend on the variations in projected populations for a given design period. Considering the uncertainties in existing calculation practices to derive an average value, present study offers a computationally efficient program capable of forecasting the future population based on the existing past population data using three well-known population forecasting methods, namely, arithmetic increase method, geometric increase method and incremental increase method. The results proved that when compared to manual calculation, the predictions were accurate, precise and computationally efficient. This user-friendly tool will be highly beneficial for various service providers where population forecasting is inevitable. The robustness of the computer code has been demonstrated using six decades of real time census data of Coimbatore city

Gradient plasticity crack tip characterization by means of the extended finite element method

© 2017, Springer-Verlag Berlin Heidelberg. Strain gradient plasticity theories are being widely used for fracture assessment, as they provide a richer description of crack tip fields by incorporating the influence of geometrically necessary dislocations. Characterizing the behavior at the small scales involved in crack tip deformation requires, however, the use of a very refined mesh within microns to the crack. In this work a novel and efficient gradient-enhanced numerical framework is developed by means of the extended finite element method (X-FEM). A mechanism-based gradient plasticity model is employed and the approximation of the displacement field is enriched with the stress singularity of the gradient-dominated solution. Results reveal that the proposed numerical methodology largely outperforms the standard finite element approach. The present work could have important implications on the use of microstructurally-motivated models in large scale applications. The non-linear X-FEM code developed in MATLAB can be downloaded from www.empaneda.com/codes