Maximal ratio combining of two amplify-forward relay branches with individual links experiencing Nakagami fading

Abstract;Relay based communication has gained considerable importance in the recent years. In this paper we find the end-toend statistics of a two hop non-regenerative relay branch, with each hop being Nakagami-m distributed. Analytical expression for the density function of the signal envelope at the output of a maximal ratio combiner in the destination node is also derived and compared with the simulation results, assuming that the destination node receives the signal through two independent relay paths. These statistics are useful in evaluating the system performance

Time and angle of arrival statistics of mobile-tomobile communication channel employing dual annular strip model

Abstract: In this paper, a generalized channel model for mobile-to-mobile communication based on the single bounce geometrybased channel modeling techniques has been proposed and analyzed. The model assumes the scatterers to be present in annular strips around the transmitting and the receiving mobile stations. Time of arrival and angle of arrival statistics, being two important channel parameters, have been derived and verified through computer simulations

Effect of array geometry on the capacity of outdoor MIMO communication

Abstract: MIMO systems have gained immense attention in the recent times for supporting high data rates and reliability. Different MIMO channel models have been proposed in the literature. Geometrically based single bounce one ring channel model is a widely used technique for modeling the channel. Evaluation of the performance of the channel has been widely studied under a uniform linear and circular array assumption. Other easily implementable array geometries require to be explored. In this paper four different array geometries each having four elements have been studied

An S-Parameter based modeling of a MIMO channel using half-wave dipole antennas

Abstract: In this paper we have introduced an S-parameter based approach for computation of MIMO channel matrix where the entire channel model is developed using half-wave dipoles. For the model under consideration, suitably terminated dipole antennas represent scatterers with different scattering coefficients. We first validate our approach by comparing results obtained by our method with the results already reported in literature for similar model evaluated using different method. Using our proposed method, we determine the variation of capacity of a MIMO link as function of separation of antennas in the mobile station for a macrocellular scenario where the scattering environment is represented by a ring of scatterers surrounding the mobile station. We further extend our approach for modeling a dual polarized MIMO system. Simulation results on capacity match with the expected results that further corroborate the effectiveness of our approach

MIMO Channel Modeling: A Review

Abstract: Channel modeling plays an important role in understanding the behavior and designing of communication systems for different environments. In this paper, we make a brief review of the different channel modeling techniques used to model a multiple-input-multiple-output (MIMO) wireless channel

Analysis of different combining schemes of two amplify-forward relay branches with individual links experiencing Nakagami fading

Abstract: Relay based communication has gained considerable importance in the recent years. In this paper we find the end-toend statistics of a two hop non-regenerative relay branch, each hop being Nakagami-m faded. Closed form expressions for the probability density functions of the signal envelope at the output of a selection combiner and a maximal ratio combiner at the destination node are also derived and analytical formulations are verified through computer simulation. These density functions are useful in evaluating the system performance in terms of bit error rate and outage probability

Alternative Technique for "Complex" Spectra Analysis

. The choice of a suitable random matrix model of a complex system is very sensitive to the nature of its complexity. The statistical spectral analysis of various complex systems requires, therefore, a thorough probing of a wide range of random matrix ensembles which is not an easy task. It is highly desirable, if possible, to identify a common mathematcal structure among all the ensembles and analyze it to gain information about the ensemble- properties. Our successful search in this direction leads to Calogero Hamiltonian, a one-dimensional quantum hamiltonian with inverse-square interaction, as the common base. This is because both, the eigenvalues of the ensembles, and, a general state of Calogero Hamiltonian, evolve in an analogous way for arbitrary initial conditions. The varying nature of the complexity is reflected in the different form of the evolution parameter in each case. A complete investigation of Calogero Hamiltonian can then help us in the spectral analysis of complex systems.Comment: 20 pages, No figures, Revised Version (Minor Changes

Scintillation Counters for the D0 Muon Upgrade

We present the results of an upgrade to the D0 muon system. Scintillating counters have been added to the existing central D0 muon system to provide rejection for cosmic ray muons and out-of-time background, and to provide additional fast timing information for muons in an upgraded Tevatron. Performance and results from the 1994-1996 Tevatron run are presented.Comment: 30 pages, 25 postscript figure

Evidence of Color Coherence Effects in W+jets Events from ppbar Collisions at sqrt(s) = 1.8 TeV

We report the results of a study of color coherence effects in ppbar collisions based on data collected by the D0 detector during the 1994-1995 run of the Fermilab Tevatron Collider, at a center of mass energy sqrt(s) = 1.8 TeV. Initial-to-final state color interference effects are studied by examining particle distribution patterns in events with a W boson and at least one jet. The data are compared to Monte Carlo simulations with different color coherence implementations and to an analytic modified-leading-logarithm perturbative calculation based on the local parton-hadron duality hypothesis.Comment: 13 pages, 6 figures. Submitted to Physics Letters

Magnetic order in spin-1 and spin-3/2 interpolating square-triangle Heisenberg antiferromagnets

Using the coupled cluster method we investigate spin-$s$ $J_{1}$-$J_{2}'$ Heisenberg antiferromagnets (HAFs) on an infinite, anisotropic, triangular lattice when the spin quantum number $s=1$ or $s=3/2$. With respect to a square-lattice geometry the model has antiferromagnetic ($J_{1} > 0$) bonds between nearest neighbours and competing ($J_{2}' > 0$) bonds between next-nearest neighbours across only one of the diagonals of each square plaquette, the same one in each square. In a topologically equivalent triangular-lattice geometry, we have two types of nearest-neighbour bonds: namely the $J_{2}' \equiv \kappa J_{1}$ bonds along parallel chains and the $J_{1}$ bonds producing an interchain coupling. The model thus interpolates between an isotropic HAF on the square lattice at $\kappa = 0$ and a set of decoupled chains at $\kappa \rightarrow \infty$, with the isotropic HAF on the triangular lattice in between at $\kappa = 1$. For both the $s=1$ and the $s=3/2$ models we find a second-order quantum phase transition at $\kappa_{c}=0.615 \pm 0.010$ and $\kappa_{c}=0.575 \pm 0.005$ respectively, between a N\'{e}el antiferromagnetic state and a helical state. In both cases the ground-state energy $E$ and its first derivative $dE/d\kappa$ are continuous at $\kappa=\kappa_{c}$, while the order parameter for the transition (viz., the average on-site magnetization) does not go to zero on either side of the transition. The transition at $\kappa = \kappa_{c}$ for both the $s=1$ and $s=3/2$ cases is analogous to that observed in our previous work for the $s=1/2$ case at a value $\kappa_{c}=0.80 \pm 0.01$. However, for the higher spin values the transition is of continuous (second-order) type, as in the classical case, whereas for the $s=1/2$ case it appears to be weakly first-order in nature (although a second-order transition could not be excluded).Comment: 17 pages, 8 figues (Figs. 2-7 have subfigs. (a)-(d)