Energy-Delay Tradeoffs of Virtual Base Stations With a Computational-Resource-Aware Energy Consumption Model

The next generation (5G) cellular network faces the challenges of efficiency, flexibility, and sustainability to support data traffic in the mobile Internet era. To tackle these challenges, cloud-based cellular architectures have been proposed where virtual base stations (VBSs) play a key role. VBSs bring further energy savings but also demands a new energy consumption model as well as the optimization of computational resources. This paper studies the energy-delay tradeoffs of VBSs with delay tolerant traffic. We propose a computational-resource-aware energy consumption model to capture the total energy consumption of a VBS and reflect the dynamic allocation of computational resources including the number of CPU cores and the CPU speed. Based on the model, we analyze the energy-delay tradeoffs of a VBS considering BS sleeping and state switching cost to minimize the weighted sum of power consumption and average delay. We derive the explicit form of the optimal data transmission rate and find the condition under which the energy optimal rate exists and is unique. Opportunities to reduce the average delay and achieve energy savings simultaneously are observed. We further propose an efficient algorithm to jointly optimize the data rate and the number of CPU cores. Numerical results validate our theoretical analyses and under a typical simulation setting we find more than 60% energy savings can be achieved by VBSs compared with conventional base stations under the EARTH model, which demonstrates the great potential of VBSs in 5G cellular systems.Comment: 5 pages, 3 figures, accepted by ICCS'1

Fixed trace β\beta-Hermite ensembles: Asymptotic eigenvalue density and the edge of the density

In the present paper, fixed trace $\beta$-Hermite ensembles generalizing the fixed trace Gaussian Hermite ensemble are considered. For all $\beta$, we prove the Wigner semicircle law for these ensembles by using two different methods: one is the moment equivalence method with the help of the matrix model for general $\beta$, the other is to use asymptotic analysis tools. At the edge of the density, we prove that the edge scaling limit for $\beta$-HE implies the same limit for fixed trace $\beta$-Hermite ensembles. Consequently, explicit limit can be given for fixed trace GOE, GUE and GSE. Furthermore, for even $\beta$, analogous to $\beta$-Hermite ensembles, a multiple integral of the Konstevich type can be obtained.Comment: 16 page

Pharmacokinetics, Metabolism and Toxicity of Carbon Nanotubes for Biomedical Purposes

Carbon nanotubes (CNTs) have attracted great interest of the nano community and beyond. However, the biomedical applications of CNTs arouse serious concerns for their unknown in vivo consequence, in which the information of pharmacokinetics, metabolism and toxicity of CNTs is essential. In this review, we summarize the updated data of CNTs from the biomedical view. The information shows that surface chemistry is crucial in regulating the in vivo behaviors of CNTs. Among the functionalization methods, PEGylation is the most efficient one to improve the pharmacokinetics and biocompatibility of CNTs. The guiding effects of the pharmacokinetics, metabolism and toxicity information on the biomedical applications of CNTs are discussed