Filter and nested-lattice code design for fading MIMO channels with side-information

Linear-assignment Gel'fand-Pinsker coding (LA-GPC) is a coding technique for channels with interference known only at the transmitter, where the known interference is treated as side-information (SI). As a special case of LA-GPC, dirty paper coding has been shown to be able to achieve the optimal interference-free rate for interference channels with perfect channel state information at the transmitter (CSIT). In the cases where only the channel distribution information at the transmitter (CDIT) is available, LA-GPC also has good (sometimes optimal) performance in a variety of fast and slow fading SI channels. In this paper, we design the filters in nested-lattice based coding to make it achieve the same rate performance as LA-GPC in multiple-input multiple-output (MIMO) channels. Compared with the random Gaussian codebooks used in previous works, our resultant coding schemes have an algebraic structure and can be implemented in practical systems. A simulation in a slow-fading channel is also provided, and near interference-free error performance is obtained. The proposed coding schemes can serve as the fundamental building blocks to achieve the promised rate performance of MIMO Gaussian broadcast channels with CDIT or perfect CSITComment: submitted to IEEE Transactions on Communications, Feb, 200

Metalloporphyrins Based Semiconducting Thin Films Deposition And Characterization For Organic Field Effect Transistor

Porphyrins are suitable for their use as the active layer of the organic field-effect transistor (OFET), as they can be easily tailored and they possess a large conjugated π system and good film-forming properties. Various types of porphyrins were selected for this study, i.e., Octaethyl–21H, 23H–Porphine (OEP), Octaethyl–21H, 23H–Porphine Copper (II) (OEP-Cu), Octaethyl–21H, 23H–Porphine Nickel (II) (OEP-Ni), Octaethyl–21H, 23H–Porphine Zinc (II) (OEP-Zn), protoporphyrin IX Zinc (II) (Proto-Zn) and protoporphyrin IX Cobalt Chloride (Proto-Co). All the porphyrins were characterised using the field emission scanning electron microscope (FESEM), Fourier transform infrared (FTIR) and ultraviolet – visible (UV–Vis) analysis. In this research, the organic field-effect transistor devices were prepared by the solution deposition methods (i.e., drop casting and spin coating techniques). The concentrations of the porphyrins used are ranged from 0.05 to 10.0 mg/ml (depending on the solution deposition method). The device with a top contact source and drain structure was selected for spin coating method and bottom contact structure was selected for drop casting method. The Aluminium source and the drain were produced after the thermal evaporation process. The effects of the metalloporphyrins on the electrical properties of the spin-coated organic field-effect transistors, the effects of annealing, the effectiveness of benzocyclobutene as a potential dielectric layer for organic field-effect transistors and the silane adhesion promoter surface treatment on the performance of the diode and the OFET device were also investigated. It was found that the spin coating technique is more suitable as compared to the drop casting technique in the preparation of the porphyrins thin film, due to its better thickness uniformity. In addition, thin film spun coated at concentration blow 3.00 mg/ml and with the gap size of 50μm exhibited the lowest current density of 1.12 A/m2 as compared to the drop casted thin film with the highest current density of 2.77 x 10-5 A/m2 at 5.0V. From the I-V results, the current density of metalloporphyrin is higher than Octaethyl–21H, 23H–Porphine, especially in the presence of silane adhesion promoter. Metalloporphyrins thin film did not shows current leakage in the current density measurement. This makes Octaethyl–21H, 23H– Porphine-Zinc, Octaethyl–21H, 23H–Porphine-Copper and Octaethyl–21H, 23H– Porphine-Nickel are capable to form good quality thin film at low solution concentration. Nevertheless, compared to protoporphyrins (i.e. Proto-Zn and Proto-Cu), both Octaethyl–21H, 23H–Porphine and metalloporphyrins (i.e., OEP-Zn, OEP-Cu and OEP-Ni) do not show good interactions with indium tin oxide (ITO) substrate. Proto-Zn thin film achieved good electrical properties even with low concentration. The protoporphyrins thin film exhibited smoother surface morphology and lower surface roughness compared to the other porphyrins thin films. From the I-V test conducted from voltage ranged -40.0V to 40.0V, benzocyclobutene thin film showed very low current density, no voltage breakdown and high resistivity. This indicates that BCB is suitable to be used as dielectric layer. Based on the Fourier transform infrared analysis, it was found that silane could form interfacial interaction between protoporphyrins and indium tin oxide substrate

Multi-user lattice coding for the multiple-access relay channel

This paper considers the multi-antenna multiple access relay channel (MARC), in which multiple users transmit messages to a common destination with the assistance of a relay. In a variety of MARC settings, the dynamic decode and forward (DDF) protocol is very useful due to its outstanding rate performance. However, the lack of good structured codebooks so far hinders practical applications of DDF for MARC. In this work, two classes of structured MARC codes are proposed: 1) one-to-one relay-mapper aided multiuser lattice coding (O-MLC), and 2) modulo-sum relay-mapper aided multiuser lattice coding (MS-MLC). The former enjoys better rate performance, while the latter provides more flexibility to tradeoff between the complexity of the relay mapper and the rate performance. It is shown that, in order to approach the rate performance achievable by an unstructured codebook with maximum-likelihood decoding, it is crucial to use a new K-stage coset decoder for structured O-MLC, instead of the one-stage decoder proposed in previous works. However, if O-MLC is decoded with the one-stage decoder only, it can still achieve the optimal DDF diversity-multiplexing gain tradeoff in the high signal-to-noise ratio regime. As for MS-MLC, its rate performance can approach that of the O-MLC by increasing the complexity of the modulo-sum relay-mapper. Finally, for practical implementations of both O-MLC and MS-MLC, practical short length lattice codes with linear mappers are designed, which facilitate efficient lattice decoding. Simulation results show that the proposed coding schemes outperform existing schemes in terms of outage probabilities in a variety of channel settings.Comment: 32 pages, 5 figure

Exploring Potential Modifiers of the Association between Neurodevelopmental Disorders and Risk of Bullying Exposure

This survey study examines data from the National Survey of Children’s Health to determine which sociodemographic factors might modify the association between neurodevelopmental disorders and being bullied

Elevated expression of L-selectin ligand in lymph node-derived human prostate cancer cells correlates with increased tumorigenicity.

Human prostate cancer LNCaP cells including C-33 and C-81 cells were originally derived from the lymph nodes of a patient with metastatic prostate cancer. These two cells were employed for characterization of L-selectin ligand and in vitro tumorigenicity, because they mimic the clinical conditions of early and late-stage human prostate cancer. C-81 cells exhibit higher in vitro migratory and invasive properties as compared with C-33 cells. We find that the L-selectin ligand and mucin glycan-associated MECA-79 epitope were elevated in C-81 cells. An increase of these glycotopes positively correlates with elevated tumorigenicity and expression of key glycosyl- and sulfotransferase genes. These results suggest that modulated expression of selective glycogenes correlates with altered tumorigenicity of cancer cells

Cognitive Radio with Partial Channel State Information at the Transmitter

In this paper, we present the cognitive radio system design with partial channel state information known at the transmitter (CSIT).We replace the dirty paper coding (DPC) used in the cognitive radio with full CSIT by the linear assignment Gel'fand-Pinsker coding (LA-GPC), which can utilize the limited knowledge of the channel more efficiently. Based on the achievable rate derived from the LA-GPC, two optimization problems under the fast and slow fading channels are formulated. We derive semianalytical solutions to find the relaying ratios and precoding coefficients. The critical observation is that the complex rate functions in these problems are closely related to ratios of quadratic form. Simulation results show that the proposed semi-analytical solutions perform close to the optimal solutions found by brute-force search, and outperform the systems based on naive DPC. Asymptotic analysis also shows that these solutions converge to the optimal ones solved with full CSIT when the K-factor of Rician channel approaches infinity. Moreover, a new coding scheme is proposed to implement the LA-GPC in practice. Simulation results show that the proposed practical coding scheme can efficiently reach the theoretical rate performance.Comment: resubmitted to IEEE Transaction on Wireless Communications, May 200