Capacity and Stable Scheduling in Heterogeneous Wireless Networks

Heterogeneous wireless networks (HetNets) provide a means to increase network capacity by introducing small cells and adopting a layered architecture. HetNets allocate resources flexibly through time sharing and cell range expansion/contraction allowing a wide range of possible schedulers. In this paper we define the capacity of a HetNet down link in terms of the maximum number of downloads per second which can be achieved for a given offered traffic density. Given this definition we show that the capacity is determined via the solution to a continuous linear program (LP). If the solution is smaller than 1 then there is a scheduler such that the number of mobiles in the network has ergodic properties with finite mean waiting time. If the solution is greater than 1 then no such scheduler exists. The above results continue to hold if a more general class of schedulers is considered.Comment: 30 pages, 6 figure

Studies on solubility and solubility-related processes.

A general description is given of solubility and solubility related processes, including the solubility of gases and vapours in liquids, and the partition of solutes between two condensed phases. Particular attention is devoted to gas-liquid chromatography (GLC) and reverse-phase high performance liquid chromatography (RP-HPLC). Theories of solubility are surveyed, including Hildebrand's theory, the scaled particle theory, and theories based on linear regression analysis. The latter requires a knowledge of characteristic parameters of solutes (solvation parameters), and solvents (solvatochromic parameters), and the determination of these is discussed. It is shown that the method of multiple linear regression analysis is very useful in the study of solution and solubility related processes, and the aim of the work in the thesis is to set out characteristic solute parameters, and apply them to a wide range of processes. Methods are given for the determination of solute solvation parameters based on experimental procedure. A collection of parameters (R2 - an excess molar refraction, x*2 - dipolarity, αH2-hydrogen bond acidity, βH2-hydrogen bond basicity, log - Ostwald solubility coefficient on n-hexadecane, Vx - size parameter) is assembled for a wide range of solutes. The construction of a solute parameter database, and its associated programs is also discussed. A thermodynamically consistent set of explanatory variables, all related to Gibbs energy are determined. New scales of multifunctional solvation parameters reflecting real solubility situations are developed and EΣH2)- These, and the older parameters, above, are applied to various processes using equations 1 and 2 (where SP is the dependant solute variable); log SP(gas condensed phase) = c + r.R2 + S.ΣxH2 + a.ΣαH2 + b.ΣβH2 + l.logL16 [1] log SP (within condensed phase) = c + r.R2 + S.ΣxH2 + a.ΣαH2 + b.ΣβH2 [2] Equations 1 and 2 are shown to be extremely useful for the prediction of physicochemical and biochemical data, and for the interpolation of factors influencing solubility and solubility related processes

Millimeter Wave Beam Alignment: Large Deviations Analysis and Design Insights

In millimeter wave cellular communication, fast and reliable beam alignment via beam training is crucial to harvest sufficient beamforming gain for the subsequent data transmission. In this paper, we establish fundamental limits in beam-alignment performance under both the exhaustive search and the hierarchical search that adopts multi-resolution beamforming codebooks, accounting for time-domain training overhead. Specifically, we derive lower and upper bounds on the probability of misalignment for an arbitrary level in the hierarchical search, based on a single-path channel model. Using the method of large deviations, we characterize the decay rate functions of both bounds and show that the bounds coincide as the training sequence length goes large. We go on to characterize the asymptotic misalignment probability of both the hierarchical and exhaustive search, and show that the latter asymptotically outperforms the former, subject to the same training overhead and codebook resolution. We show via numerical results that this relative performance behavior holds in the non-asymptotic regime. Moreover, the exhaustive search is shown to achieve significantly higher worst-case spectrum efficiency than the hierarchical search, when the pre-beamforming signal-to-noise ratio (SNR) is relatively low. This study hence implies that the exhaustive search is more effective for users situated further from base stations, as they tend to have low SNR.Comment: Author final manuscript, to appear in IEEE Journal on Selected Areas in Communications (JSAC), Special Issue on Millimeter Wave Communications for Future Mobile Networks, 2017 (corresponding author: Min Li

Design and Analysis of Transmit Beamforming for Millimetre Wave Base Station Discovery

In this paper, we develop an analytical framework for the initial access (a.k.a. Base Station (BS) discovery) in a millimeter-wave (mm-wave) communication system and propose an effective strategy for transmitting the Reference Signals (RSs) used for BS discovery. Specifically, by formulating the problem of BS discovery at User Equipments (UEs) as hypothesis tests, we derive a detector based on the Generalised Likelihood Ratio Test (GLRT) and characterise the statistical behaviour of the detector. The theoretical results obtained allow analysis of the impact of key system parameters on the performance of BS discovery, and show that RS transmission with narrow beams may not be helpful in improving the overall BS discovery performance due to the cost of spatial scanning. Using the method of large deviations, we identify the desirable beam pattern that minimises the average miss-discovery probability of UEs within a targeted detectable region. We then propose to transmit the RS with sequential scanning, using a pre-designed codebook with narrow and/or wide beams to approximate the desirable patterns. The proposed design allows flexible choices of the codebook sizes and the associated beam widths to better approximate the desirable patterns. Numerical results demonstrate the effectiveness of the proposed method.Comment: 30 pages, 13 figures, submitte

Capsaicinoids – a potential role for weight management

The prevalence of overweight and obese individuals has risen dramatically in populations around the world over the last 30 years (Popkin et al., 2012) representing a rapidly growing burden to public health services (Wang et al., 2011). Reliance on lifestyle modification, although initially promising, has proven to be unsuccessful over the longer term (Barte et al., 2010) and there are currently a lack of successful treatment options. Capsaicinoids are a bio-active group of compounds, naturally occurring in the fruit of the plant from the genus capsicum. Initial research suggests these compounds may have beneficial effects on weight loss outcomes when ingested (Lejeune et al., 2003). A systematic review of the available literature on capsaicinoids found evidence that ingestion may increase energy expenditure by around 210kJ/day and lipid oxidation by around 20%. Ingestion may also reduce energy intake although evidence has been conflicting and the size of the effect unclear. To further aid understanding, a meta-analysis was undertaken involving intervention trials assessing the effects of capsaicinoids on energy intake. Analysis suggested capsaicinoid ingestion prior to a meal reduced ad libitum energy intake energy intake by 251kJ (60kcal) per meal (95% confidence interval of 337 – 166kJ) p < 0.001. Caution should be applied to this result however, due to the small size of the reduction and the short term nature of the trials involved. Longer term trials are needed to assess potential changes in body composition as a result of capsaicinoid interventions. To this end, a six-week placebo control intervention study was conducted to assess changes in body fat in 60 Caucasian women. Results of a sensitivity analysis found a small, statistically significant decrease in body fat percentage (0.64%, p = 0.022) and total body fat (0.67kg, p = 0.007) in the intervention group. However, the robustness of these findings are called into question by the results of an interaction analysis which of observed no significant difference between placebo control and intervention groups over time for these outcomes. The effect was also small and therefore longer term supplementation would be required to produce a medically beneficial changes in body composition

Precious

Sheet music contains sexist and/or misogynistic language, concepts, and/or imagry promoting rape culture. With Ukulele arrangement. Contains advertisements and/or short musical examples of pieces being sold by publisher.https://digitalcommons.library.umaine.edu/mmb-vp/7112/thumbnail.jp

Greenhouse gas balance over thaw-freeze cycles in discontinuous zone permafrost

Peat in the discontinuous permafrost zone contains a globally significant reservoir of carbon that has undergone multiple permafrost-thaw cycles since the end of the mid-Holocene (~3700 years before present). Periods of thaw increase C decomposition rates which leads to the release of CO2 and CH4 to the atmosphere creating potential climate feedback. To determine the magnitude and direction of such feedback, we measured CO2 and CH4 emissions and modeled C accumulation rates and radiative fluxes from measurements of two radioactive tracers with differing lifetimes to describe the C balance of the peatland over multiple permafrost-thaw cycles since the initiation of permafrost at the site. At thaw features, the balance between increased primary production and higher CH4 emission stimulated by warmer temperatures and wetter conditions favors C sequestration and enhanced peat accumulation. Flux measurements suggest that frozen plateaus may intermittently (order of years to decades) act as CO2 sources depending on temperature and net ecosystem respiration rates, but modeling results suggest that—despite brief periods of net C loss to the atmosphere at the initiation of thaw—integrated over millennia, these sites have acted as net C sinks via peat accumulation. In greenhouse gas terms, the transition from frozen permafrost to thawed wetland is accompanied by increasing CO2 uptake that is partially offset by increasing CH4 emissions. In the short-term (decadal time scale) the net effect of this transition is likely enhanced warming via increased radiative C emissions, while in the long-term (centuries) net C deposition provides a negative feedback to climate warming