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RISS 인기검색어
- 검색키워드
- 저자 : Pabst, R. (검색결과 5 건)
- 무료
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Fixed Relays for Next Generation Wireless Systems - System Concept and Performance Evaluation
Pabst Ralf,Esseling Norbert,Walke Bernhard H. The Korea Institute of Information and Commucation 2005 Journal of communications and networks Vol.7 No.2
This work presents a concept and the related analysis of the traffic performance for a wireless broadband system based on fixed relay stations acting as wireless bridges. The analysis focuses on the important performance indicators end-to-end throughput and delay, taking into account the effects of an automated repeat request protocol. An extension to a MAC frame based access protocol like IEEE 802.11e, 802.15.3, 802.16a, and HIPERLAN2 is outlined and taken as basis for the calculations. The system is intended for both dense populated areas as an overlay to cellular radio systems and to provide wide-area broad-band coverage. The two possible deployment scenarios for both dense urban and wide-area environments are introduced. Analytical and validating simulation results are shown, proving the suitability of the proposed concept for both of the mentioned scenarios. It is established that the fixed relaying concept is well suited to substantially contribute to provide high capacity cellular broad-band radio coverage in next generation (NG) cellular wireless broadband systems.
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Classification of structured validation data using stateless and stateful features
Schwenk, G.,Pabst, R.,Mü,ller, K.R. Elsevier Science B.V., Amsterdam. 2019 COMPUTER COMMUNICATIONS -GUILDFORD THEN AMSTERDAM- Vol.138 No.-
<P><B>Abstract</B></P> <P>To reliably identify problems impacting the service quality and system dependability of mobile communication networks, the monitored data needs to be validated. This paper proposes and evaluates analysis methods, features and learning methods for the automatic validation of such data, with a special focus on failure data of mobile communication data. This data can be analyzed for discriminating failures caused by problems in the infrastructure (valid failures) from those caused by other circumstances like device imperfections (invalid failures), with the purpose of filtering the invalid failures, which effectively increases both dependability and value of the underlying data. To represent the complex structural and temporal properties of the mobile communication data, two complementary feature representations are proposed and compared, followed by a discussion of classification methods which are suitable for these feature spaces and for an interpretation of their results to support manual auditing. Their classification performances on these feature spaces are evaluated and compared to competitive approaches. In the evaluation a classification performances of up to 97% AUC–ROC is achieved. This renders our approach a good alternative to using manual matching rules, which require costly expert-knowledge and are much more time-consuming to define and maintain — while also highlighting the relevance of combining feature spaces of different problem perspectives. Additionally it is shown that using non-proprietary data analysis can enable feature representations nearly as expressive as those created by using proprietary analysis methods, which allows a broader application of the proposed methods, due to the lower processing requirements.</P>
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Attosecond counter-rotating-wave effect in xenon driven by strong fields
Anand, M.,Pabst, Stefan,Kwon, Ojoon,Kim, Dong Eon American Physical Society 2017 Physical Review A Vol.95 No.5
<P>We investigate the subfemtosecond dynamics of a highly excited xenon atom coherently driven by a strong control field at which the Rabi frequency of the system is comparable to the frequency of a driving laser. The widely used rotating-wave approximation breaks down at such fields, resulting in features such as the counter-rotating-wave (CRW) effect. We present a time-resolved observation of the CRW effect in the highly excited 4d(-1)np xenon using attosecond transient absorption spectroscopy. Time-dependent many-body theory confirms the observation and explains the various features of the absorption spectrum seen in experiment.</P>
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Rajinder Bhasin,Thomas Pabst 대한토목학회 2015 KSCE JOURNAL OF CIVIL ENGINEERING Vol.19 No.3
Numerical simulations have been performed to assess the stability of a large underground powerhouse in the Himalayas, using bothfinite element and distinct element approaches. Large convergences (around 250-300 mm) along the 45 m high wall of the MachineHall have been measured by total station measurements during construction and up to 60 mm in the post construction and operationalphase. Displacements are continuing at a reduced rate of about 3 to 6 mm per year. A large number of rock bolts have failed in thepowerhouse and the shotcrete liner presents cracks and failure marks, thus questioning the long-term integrity and stability of theexisting rock support system. The purpose of the numerical analysis was to back-calculate the prevailing rock mass conditionssurrounding the machine hall, thereby gaining a better understanding of the mechanisms responsible for the instability in the cavern. The results from the analysis indicate that there was possibly an underestimation of the rock support requirements needed for thecavern, coupled with a not so good installation (incomplete grouting of the bolts). Both the length and the capacity of the rock boltswere underestimated presumably due to the existence of a high stress regime in the area, which may not have been taken intoconsideration in the design of rock support. The effect of a possible earthquake, frequent in this area, has also been studied and provesto induce a significant increase of the displacements and the support failure.
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