Abstract-In cloud environments, resources can be requested on-demand when they are needed. A cloud management system is responsible for determining which physical machines are responsible for processing the requests. The problem of determining which servers are used for which services is referred to as the Cloud Application Placement Problem (CAPP), and multiple criteria such as cost and number of migrations must be taken into account. When applications are constructed as a collection of communicating services, such as in Service-Oriented Architectures, it becomes important to take the underlying network properties into account when these placement decisions are made. In this paper, we propose an Integer Linear Programming (ILP) formulation for the CAPP, which optimizes multiple criteria such as cost, latency and number of migrations between subsequent invocations by using multiple optimization criteria. We also present hierarchical algorithms based on particle swarm optimization and genetic algorithms to solve the CAPP. These algorithms are be executed within a management hierarchy, which reduces the amount of information needed for the algorithms to function, increasing scalability of the management system. Finally, we evaluate the hierarchical algorithms by comparing them to an optimal algorithm based on the ILP formulation.

This paper presents an analysis of the polarization characteristics of specular and dense multipath components (SMC & DMC) in a large industrial hall based on frequency-domain channel sounding experiments at 1.3 GHz with 22 MHz bandwidth. The RiMAX maximum-likelihood estimator is used to extract the full polarimetric SMC and DMC from the measurement data by taking into account the polarimetric radiating patterns of the dual-polarized antennas. Cross-polar discrimination (XPD) values are presented for the measured channels and for the SMC and DMC separately.

Abstract-The electromagnetic reverberation time characteristics of indoor environments are experimentally investigated from 2 to 10 GHz with bandwidths up to 900 MHz. At a given frequency, the reverberation time is observed to be approximately constant up to 900 MHz. Moreover, the reverberation time decreases for increasing frequencies. Based on the theory of electromagnetic fields in cavities, a model to predict the room quality factor, reverberation time value, and average absorption coefficient is developed for the first time in indoor environments for the investigated frequency range. The validity and robustness of the model is investigated with data obtained for various environments, central frequencies, and bandwidths. The model is applied to another room over the whole 2-10 GHz frequency band and a maximum and average relative error of 22.30% and 8.80% were obtained, respectively, with an rms error of 1.90 ns. Furthermore, good agreement is obtained with measurements reported in the literature with settings falling into the model range; scenarios for which relative errors smaller than 10% were computed. The results demonstrate that this approach is not only an accurate alternative to the reverberation time measurements and computations of indoor environments in the 2-10 GHz frequency range but also a viable route to link propagation mechanisms in indoor scenarios with reverberation chambers.