Femtocell

Summary

In telecommunications, a femtocell is a small, low-power cellular base station, typically designed for use in a home or small business. A broader term which is more widespread in the industry is small cell, with femtocell as a subset. It connects to the service provider's network via broadband (such as DSL or cable); current designs typically support four to eight simultaneously active mobile phones in a residential setting depending on version number and femtocell hardware, and eight to sixteen mobile phones in enterprise settings. A femtocell allows service providers to extend service coverage indoors or at the cell edge, especially where access would otherwise be limited or unavailable. Although much attention is focused on WCDMA, the concept is applicable to all standards, including GSM, CDMA2000, TD-SCDMA, WiMAX and LTE solutions. The use of femtocells allows network coverage in places where the signal to the main network cells might be too weak. Furthermore, femtocells lower

Official source

https://en.wikipedia.org/wiki/Femtocell

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Miniaturized Microwave Cavities for Industrial Applications

Maddalena Violetti

Microwave cavities, or microwave resonators, are used in a variety of applications, including filters, oscillators, frequency meters, and tuned amplifiers. The ever-increasing demand for compact and/or portable telecommunication systems drives the need for further miniaturization of such structures for improved integration. In this thesis, new miniature microwave cavity solutions are proposed, which are useful in at least two scopes of application. In the first scope, the new devices are used as microwave front-ends of a short-range radar system for on-line blade tip monitoring in gas turbines (i.e. land-based large-frame turbines, aero-derivatives and aero-engines). In general, microwave sensors are advantageous for blade tip sensing: contrary to other existing techniques, they can survive to high temperatures for extended period of operation, unaffected by contaminants, like gases and dirt. Nonetheless, the microwave front-end of such systems is of difficult implementation, due to the strict thermal-mechanical constraints of the specific field of application (i.e. a large temperature change, the presence of vibrations, dirt and combustion by-products) and the tight requirements on the size of candidate probe designs. Antenna-based solutions are currently used as tip monitoring probes, with the disadvantage of being complex structures with radiation characteristics that are not entirely well suited for short range sensing. As a valid alternative, we propose two cavity-based probe solutions, namely a miniature waveguide resonator probe and a coaxial resonator probe, which represent an elegant compromise between robustness, miniaturization and simplicity of operation. Tests in laboratory and on real turbine engines demonstrated the suitability of such devices for the aimed application and several improved characteristics with respect to other comparable techniques, like antenna-based and eddy-current sensors. In the second scope, the new proposed solutions are used as microwave resonators in miniature rubidium atomic clocks. Attempts to miniaturize such kind of systems are usually limited by the dimensional constraints of standard microwave cavity resonators (MWR) , which account for a large part of the volume of the physics package. We propose a new miniature MWR based on a loop-gap resonator structure, also referred to as the μ-LGR. This cavity design meets the desired field configuration for the atomic clock operation and achieves an interesting size-reduction. A laboratory experiment of an atomic clock integrating the μ-LGR achieved unmatched results of stability compared to other microcell clocks. Finally, we propose a miniature planar MWR for the integration of 2D microfabricated cells.

EPFL2012

, ,

We study the energy consumptions of two strategies that increase the capacity of an LTE network: (1) the deployment of redundant macro and micro base stations by the operator at locations where the traffic is high, and (2) the deployment of publicly accessible femto base stations by home users. Previous studies show the deployment of publicly accessible residential femto base stations is considerably more energy efficient; however, the results are proposed using an abstracted model of LTE networks, where the coverage constraint was neglected in the study, as well as some other important physical and traffic layer specifications of LTE networks. We study a realistic scenario where coverage is provided by a set of non-redundant macro-micro base stations and additional capacity is provided by redundant macro-micro base stations or by femto base stations. We quantify the energy consumption of macro-micro and femto deployment strategies by using a simulation of a plausible LTE deployment in a mid-size metropolitan area, based on data obtained from an operator and using detailed models of heterogeneous devices, traffic, and physical layers. The metrics of interest are operator-energy-consumption/total-energy-consumption per unit of network capacity. For the scenarios we studied, we observe the following: (1) There is no significant difference between operator energy consumption of femto and macro-micro deployment strategies. From the point of view of society, i.e. total energy consumption, macro-micro deployment is even more energy efficient in some cases. This differs from the previous findings, which compared the energy consumption of femto and macro-micro deployment strategies, and found that femto deployment is considerably more energy efficient. (2) The deployment of femto base stations has a positive effect on mobile-terminal energy consumption; however, it is not significant compared to the macro-micro deployment strategy. (3) The energy saving that could be obtained by making macro and micro base stations more energy proportional is much higher than that of femto deployment.

2011

A pricing mechanism for Femto Base Stations

Ramin Khalili, Jean-Yves Le Boudec

Telecom service providers have not control over functionality of Femto-BSs. However, they can motivate home service providers to cooperate with them (e.g. activate their Femto-BSs) by porpoising a reasonable price for service they provide. A home service provider can then evaluate its utility according to the price proposed by the telecoms service provider and decide to cooperate if it gets a positive utility. In this report, we propose a pricing mechanism and evaluate the behavior of home service providers (i.e., the number of active Femto-BSs) for a given price. We mainly focus our attention on Nash equilibrium analysis.

2012

Miniaturized Microwave Cavities for Industrial Applications

Maddalena Violetti

EPFL2012

, ,

2011