Modelling Load Balancing and Carrier Aggregation in Mobile Networks

In this paper, we study the performance of multicarrier mobile networks. Specifically, we analyze the flow-level performance of two inter-carrier load balancing schemes and the gain engendered by Carrier Aggregation (CA). CA is one of the most important features of HSPA+ and LTE-A networks; it allows devices to be served simultaneously by several carriers. We propose two load balancing schemes, namely Join the Fastest Queue (JFQ) and Volume Balancing (VB), that allow the traffic of CA and non-CA users to be distributed over the aggregated carriers. We then evaluate the performance of these schemes by means of analytical modeling. We show that the proposed schemes achieve quasi-ideal load balancing. We also investigate the impact of mixing traffic of CA and non-CA users in the same cell and show that performance is practically insensitive to the traffic mix.Comment: 8 pages, 6 figures, submitted to WiOpt201

Spin Degree of Freedom in a Two-Dimensional Electron Liquid

We have investigated correlation between spin polarization and magnetotransport in a high mobility silicon inversion layer which shows the metal-insulator transition. Increase in the resistivity in a parallel magnetic field reaches saturation at the critical field for the full polarization evaluated from an analysis of low-field Shubnikov-de Haas oscillations. By rotating the sample at various total strength of the magnetic field, we found that the normal component of the magnetic field at minima in the diagonal resistivity increases linearly with the concentration of ``spin-up'' electrons.Comment: 4 pages, RevTeX, 6 eps-figures, to appear in PR

Parallel magnetic field induced giant magnetoresistance in low density {\it quasi}-two dimensional layers

We provide a possible theoretical explanation for the recently observed giant positive magnetoresistance in high mobility low density {\it quasi}-two dimensional electron and hole systems. Our explanation is based on the strong coupling of the parallel field to the {\it orbital} motion arising from the {\it finite} layer thickness and the large Fermi wavelength of the {\it quasi}-two dimensional system at low carrier densities.Comment: 4 pages with 4 figures. Accepted for Publication in Physical Review Letter

Classical versus Quantum Effects in the B=0 Conducting Phase in Two Dimensions

In the dilute two-dimensional electron system in silicon, we show that the temperature below which Shubnikov-de Haas oscillations become apparent is approximately the same as the temperature below which an exponential decrease in resistance is seen in B=0, suggesting that the anomalous behavior in zero field is observed only when the system is in a degenerate (quantum) state. The temperature dependence of the resistance is found to be qualitatively similar in B=0 and at integer Landau level filling factors.Comment: 3 pages, 3 figure

A New Liquid Phase and Metal-Insulator Transition in Si MOSFETs

We argue that there is a new liquid phase in the two-dimensional electron system in Si MOSFETs at low enough electron densities. The recently observed metal-insulator transition results as a crossover from the percolation transition of the liquid phase through the disorder landscape in the system below the liquid-gas critical temperature. The consequences of our theory are discussed for variety of physical properties relevant to the recent experiments.Comment: 12 pages of RevTeX with 3 postscript figure

Comment on "Theory of metal-insulator transitions in gated semiconductors" (B. L. Altshuler and D. L. Maslov, Phys. Rev. Lett. 82, 145 (1999))

In a recent Letter, Altshuler and Maslov propose a model which attributes the anomalous temperature and field dependence of the resistivity of two-dimensional electron (or hole) systems to the charging and discharging of traps in the oxide (spacer), rather than to intrinsic behavior of interacting particles associated with a conductor-insulator transition in two dimensions. We argue against this model based on existing experimental evidence.Comment: 1 page; submitted to PR

Possible triplet superconductivity in MOSFETs

A theory that predicts a spin-triplet, even-parity superconducting ground state in two-dimensional electron systems is re-analyzed in the light of recent experiments showing a possible insulator-to-conductor transition in such systems. It is shown that the observations are consistent with such an exotic superconductivity mechanism, and predictions are made for experiments that would further corroborate or refute this proposal.Comment: 4 pp., REVTeX, psfig, 1 eps fig, final version as publishe