High SNR sum capacity analysis of BD MIMO BC systems with imperfect CSI

We investigate the sum capacity of Block Diagonalization precoding Multiple Input Multiple Output Broadcast Channels (BD MIMO BC) with imperfect Channel State Information (CSI) at the base station. Since it is difficult to obtain the exact expression, a lower and an upper bounds of the sum capacity under Gaussian channel estimation errors are drived instead. Analyses show that the gap between two bounds is considerably tight at all Signal to Noise Ratio (SNR) region. From the lower bound of the sum capacity, we can see that the multiplexing gain tends to be zero at high SNR region, which indicates that the BD MIMO BC system with channel estimation errors is interference-limited at high SNR.     

Inverse QR iterative method for subspace tracking

The Bi-LS method based on QR decomposition provides a convenient framework for developing efficient subspace tracking algorithms. To overcome the shortcoming of the backsubstitution step and improve the parallel architecture of the Bi-LS algorithms, a Bi-LS subspace tracking algorithm based on Inverse QR (IQR) decomposition is developed. The proposed IQR iterative algorithm for subspace tracking is well suited for the parallel implementation in the systolic array. Simulation results are presented to illustrate the effectiveness of the proposed IQR subspace tracking algorithm.     

An adaptive digital image watermark algorithm based on gray-scale morphology

An adaptive digital image watermark algorithm with strong robustness based on gray-scale morphology is proposed in this paper. The embedded strategies include: The algorithm seeks and ex-tracts adaptively the image strong texture regions. The algorithm maps the image strong texture region to the wavelet tree structures, and embeds adaptively watermark into the wavelet coefficients corre-sponding to the image’s strong texture regions. According to the visual masking features, the algorithm adjusts adaptively the watermark-embedding intensity. Experimental results show the algorithm is robust to compression, filtering, noise as well as strong shear attacks. The algorithm is blind watermark scheme. The image strong texture region extraction method based on morphology in this algorithm is simple and effective and adaptive to various images.     

Solution-Processed High-<Emphasis Type="Italic">k</Emphasis> Dielectric,ZrO<Subscript>2</Subscript>, and Integration in Thin-Film Transistors

We report a sol–gel method to deposit a high-k dielectric, zirconium oxide (ZrO₂). This solution-based approach has advantages of easy processing and low fabrication cost. Effects of annealing temperatures on dielectric properties, such as tunneling current density and capacitance density, are reported. Morphological and chemical characterizations suggest that the process temperature can be kept at or below 300°C. We have employed the solution-processed ZrO₂ dielectric in a zinc tin oxide thin-film transistor. Saturation mobility of 4.0 cm²/V s at operating voltage of 2 V has been observed. The measured subthreshold swing is 74 mV/decade, which is the result of the combination of an electronically clean dielectric/semiconductor interface and high insulator capacitance.     

Euclidean Geometry LDPC-VBLAST System Design and Performance Evaluation

Among popular multi-transmit and multi-receive antennas techniques, the VBLAST (Vertical Bell Laboratories Layered Space-Time) architecture has been shown to be a good solution for wireless communications applications that require the transmission of data at high rates. Recently, the application of efficient error correction coding schemes such as low density parity-check (LDPC) codes to systems with multi-transmit and multi-receive antennas has shown to significantly improve bit error rate performance. Although irregular LDPC codes with non-structure are quite popular due to the ease of constructing the parity check matrices and their very good error rate performance, the complexity of the encoder is high. Simple implementation of both encoder and decoder can be an asset in wireless communications applications. In this paper, we study the application of Euclidean geometry LDPC codes to the VBLAST system. We assess system performance using different code parameters and different numbers of antennas via Monte-Carlo simulation and show that the combination of Euclidean geometry LDPC codes and VBLAST can significantly improve bit error rate performance. We also show that interleaving data is necessary to improve performance of LDPC codes when a higher number of antennas is, used in order to mitigate the effect of error propagation. The simplicity of the implementation of both encoder and decoder makes Euclidean geometry LDPC codes with VBLAST system attractive and suitable for practical applications.     

Scattering of Electromagnetic Waves by a Coated Nihility Cylinder

An analytical solution for the scattering of electromagnetic plane waves from an infinitely long nihility cylinder, coated with a double positive (DPS), double negative (DNG), epsilon negative (ENG), or mu negative (MNG) layer of uniform thickness is presented. The solution is determined by solving the scalar wave equation in the cylindrical coordinates, for different regions and applying the appropriate boundary conditions at the interfaces. Both TM and TE polarizations as incident plane have been considered in the analysis. Comparison of behaviors of a coated nihility cylinder with a coated PEC cylinder has been made. It is noted that two situations are more closer for DNG coating as compared to DPS coating.     

Geometrical Characteristics and Surface Polarity of Inclined Crystallographic Planes of the Wurtzite and Zincblende Structures

Inclined crystallographic planes of the wurtzite structure were investigated in comparison with the zincblende structure in terms of surface geometry characteristics. The ball–stick model indicates that the semipolar surface possesses a surface polarity resembling the anion polarity, which agrees with the common experimental observations of epitaxial growth preference for the cation-polarity surface over the surface. The wurtzite surface was found to share geometrical similarities with the zincblende {100} surface uniquely among the possible semipolar planes. This finding encourages epitaxial growth on the plane of wurtzite semiconductors, e.g., GaN, with the potential of avoiding atomic step formations typically associated with off-axis crystallographic planes.     

A pilot-assisted non-Cyclic Prefixed MIMO-SCFDE system

A non-Cyclic Prefixed Multiple-Input Multiple-Output Single-Carrier Frequency-Domain Equalization (non-CP MIMO-SCFDE) system based on a recursive algorithm of Joint Channel Es- timation and Data Detection (recursive-JCEDD) is proposed in this paper. Unlike the traditional CP MIMO-SCFDE system, the transmitted block of the proposed system is designed in the way that block-type pilot sequences and Single-Carrier (SC) information sequences have been arranged alter- nately without any cyclic prefix before each ...     

Cellular Controlled Short-Range Communication for Cooperative P2P Networking

This article advocates a novel communication architecture and associated collaborative framework for future wireless communication systems. In contrast to the dominating cellular architecture and the upcoming peer-to-peer architecture, the new approach envisions a cellular controlled short-range communication network among cooperating mobile and wireless devices. The role of the mobile device will change, from being an agnostic entity in respect to the surrounding world to a cognitive device. This cognitive device is capable of being aware of the neighboring devices as well as on the possibility to establish cooperation with them. The novel architecture together with several possible cooperative strategies will bring clear benefits for the network and service providers, mobile device manufacturers and also end users.

Downlink Capacity Analysis of Collaborative Crossed Timeslots in CDMA TDD Systems

Traffic asymmetry between uplink and downlink is expected to be a remarkable 3G characteristic in cellular mobile multimedia communications. CDMA system with TDD is a good solution to this traffic asymmetry. However, the level of traffic asymmetry may be significantly different from a cell to another cell. To tackle this problem and to support the traffic hot spot, crossed slots are examined. The use of crossed slots is restricted within a certain range of a cell by investigating the inter-cell interference and the maximum planned load factor. We examine the radius of inner zone and discuss the capacity of downlink crossed slots for various neighbor cell environments. Computational results show that the capacity increase in the target cell is outstanding by reducing the service range of neighbor cells. When all six neighbors reduce their service range by 20%, the capacity at target cell crossed slot is increased by 35%. Monte Carlo simulation is performed with large scale fading to verify the numerical analysis.