| 1. |
- Dimou, Konstantinos, et al.
(författare)
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Generic link layer : A solution for multi-radio transmission diversity in communication networks beyond 3G
- 2005
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Ingår i: VTC2005-FALL. - 0780391527 ; , s. 1672-1676
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Konferensbidrag (refereegranskat)abstract
- Communication systems beyond 3G (B3G) will consist of a mixture of radio access technologies. For such systems the challenge is to provide a multi-radio access architecture that facilitates the interconnection of heterogeneous radio access networks and supports efficiently the various services. Achieving this interconnection in a transparent way for users and services requires extensions at link layer level. The Generic Link Layer (GLL), as proposed in the context of the Ambient Networks (AN) project addresses this challenge. The principal role of GLL within the AN multi-radio access architecture is to integrate different Radio Access Technologies (RATs) at the link layer and to facilitate their efficient interworking. A feature that is enabled by the use of GLL is termed multi-radio transmission diversity (MRTD). It implies a well-defined split of a data-flow over the available RATs; the main benefits thereby are gain in user QoS, in spectral efficiency and in robustness. In this paper we give the system architecture and the GLL functions required for the realization of MRTD. Then, the specific scenario of cooperation between UMTS and IEEE 802.11 is discussed.
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| 2. |
- Lederer, M.T., et al.
(författare)
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Towards abundance determination from dynamic atmospheres
- 2006
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Ingår i: Memorie della Societa Astronomica Italiana, v.77. ; , s. 1008-1013
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- We summarize our efforts to determine element abundances (e.g. for the elements C and O) and isotopic ratios (e. g. isotope[12]{C}/isotope[13]{C}) along the Asymptotic Giant Branch (AGB). For the modelling of AGB star spectra for stars on the lower part of the AGB, hydrostatic model atmospheres have been shown to reproduce observations quite well. Stars climbing up the AGB get more and more dynamic. For these strongly pulsating stars dynamic model atmospheres have to be used in order to reproduce the observed spectra which are dominated by dynamical effects. Both the developments of hydrostatic and dynamic model atmospheres are considered, referring to the problems encountered in the synthesis of cool star spectra. We emphasize the importance of AGB stars in globular clusters, which provide a method to get a homogenous sample of stars well-defined in mass, metallicity, and luminosity. Finally, we point out the relevance of our investigations for stellar evolutionary models.
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