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

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

3,3′-Bis(3-meth­oxy­benz­yl)-1,1′-(ethane-1,2-diyl)­diimidazolium dibromide dihydrate

In the title compound, C24H28N4O2 2+·2Br−·2H2O, the diimid­azo­lium cation is located on an inversion center. The imidazole and the benzene rings make a dihedral angle of 68.08 (04)°. In the crystal, O—H⋯Br, C—H⋯O and C—H⋯Br hydrogen bonds link the diimidazolium cations, the bromide anions and the water mol­ecules into a two-dimensional network

3,3′-Dibenzyl-1,1′-ethyl­enediimidazolium dibromide

In the title compound, C22H24N4 2+·2Br−, the imidazolium dication is located on a crystallographic inversion center. The imidazole and benzene rings make a dihedral angle of 73.1 (9)°. In the crystal, non-classical inter­molecular C—H⋯Br hydrogen bonds link the ion pairs into a two-dimensional network

Investigation of thermal resistance and power consumption in Ga-doped indium oxide (In2O3) nanowire phase change random access memory

The resistance stability and thermal resistance of phase change memory devices using similar to 40 nm diameter Ga-doped In2O3 nanowires (Ga:In2O3 NW) with different Ga-doping concentrations have been investigated. The estimated resistance stability (R(t)/R-0 ratio) improves with higher Ga concentration and is dependent on annealing temperature. The extracted thermal resistance (R-th) increases with higher Ga-concentration and thus the power consumption can be reduced by similar to 90% for the 11.5% Ga: In2O3 NW, compared to the 2.1% Ga: In2O3 NW. The excellent characteristics of Ga-doped In2O3 nanowire devices offer an avenue to develop low power and reliable phase change random access memory applications. (C) 2014 AIP Publishing LLC.X113sciescopu

THE BIOMECHANICALANALYSIS OF TAEKWONDO AXE-KICK IN SENIOR HIGH SCHOOL ATHLETIC

The purpose of this study was to investigate the biomechanical factors of the Taekwondo axe-kick and compare the differences between male and female athletes for timing kinematicsand kinetics. The data gained from 23 test subjects of the Taekwondo team from the junior high school (male:16, female:?). Base on the results and discussion of the study, we have reached the following conclusion: the average movement speed has significant difference between male and female groups. The average movement speed has significant positive correlation with the peak vertical ground reaction force (body weight), the peak front-rear ground reaction and impulse at the kicking leg. While the kicking leg attacked the target, the higher point of the kicking leg and the larger power at the peak tront-rear ground reaction force, the faster attacking velocity(the resultant of toe velocity) at the target