Capacity analysis of reservation-based random access for broadband wireless access networks

Abstract—In this paper we propose a novel model for the capacity analysis on the reservation-based random multiple access system, which can be applied to the medium access control protocol of the emerging WiMAX technology. In such a wireless broadband access system, in order to support QoS, the channel time is divided into consecutive frames, where each frame consists of some consequent mini-slots for the transmission of requests, used for the bandwidth reservation, and consequent slots for the actual data packet transmission. Three main outcomes are obtained: first, the upper and lower bounds of the capacity are derived for the considered system. Second, we found through the mathematical analysis that the transmission rate of reservationbased multiple access protocol is maximized, when the ratio between the number of mini-slots and that of the slots per frame is equal to the reciprocal of the random multiple access algorithm’s transmission rate. Third, in the case of WiMAX networks with a large number of subscribers, our analysis takes into account both the capacity and the mean packet delay criteria and suggests to keep such a ratio constant and independent of application-level data traffic arrival rate

Postcard: Cottage Hotel, Ellis, Kansas. 11914

This black and white photographic postcard features a three story building with a hotel sign on the front. A covered porch is on the right side of the building and automobiles are parked along the curb. Written text is in the bottom left corner and printed text is in the top right corner. Handwriting is on the back of the card.https://scholars.fhsu.edu/tj_postcards/1920/thumbnail.jp

A professional development curriculum for educators of deaf students: comparative linguistics

The teachers at Rochester School for the Deaf (RSD) find a challenge: their ability to translate fluently between two languages grammatically, American Sign Language (ASL) and English providing the instructions related to the literacy. Almost all of the teachers have been rated at the Advanced level of Sign Communication Proficiency Interview (SCPI), an assessment measurement. The indication is that they do not demonstrate complete bilingual competence. For the literacy skills, it is important for the teachers to be able to switch fluidly between the two langues of instruction - ASL and English - while teaching deaf and hard of hearing students in the classroom. This is where the attention shifts to the needs of teachers. To satisfy the teacher\u27s particular needs, they need to attend professional development training to improve their language skills, enhance their metacognitive skills and be able to apply the bilingual strategy to their instruction. The one-year professional development training was designed to provide the resources for the teachers and teacher assistants to work in this area. After one year of training, they would have more knowledge in grammar translation between ASL and English and be able to apply bilingual strategies in the classroom. Consequently, teachers hope that children will acquire more literacy skills in both ASL amd English. This proposal outlines a professional development training program, which focuses on teachers\u27 amd teacher assistants\u27 development of metacognitive awareness of targeted language concepts. After a one-year training period, the participants\u27 skills will increase in grammar translation between ASL and English in order to apply bilingual strategies in the classroom. This will positively impact the literacy development of their deaf and hard of hearing students

Statistical Delay Bound for WirelessHART Networks

In this paper we provide a performance analysis framework for wireless industrial networks by deriving a service curve and a bound on the delay violation probability. For this purpose we use the (min,x) stochastic network calculus as well as a recently presented recursive formula for an end-to-end delay bound of wireless heterogeneous networks. The derived results are mapped to WirelessHART networks used in process automation and were validated via simulations. In addition to WirelessHART, our results can be applied to any wireless network whose physical layer conforms the IEEE 802.15.4 standard, while its MAC protocol incorporates TDMA and channel hopping, like e.g. ISA100.11a or TSCH-based networks. The provided delay analysis is especially useful during the network design phase, offering further research potential towards optimal routing and power management in QoS-constrained wireless industrial networks.Comment: Accepted at PE-WASUN 201

On the Performance of Packet Aggregation in IEEE 802.11ac MU-MIMO WLANs

Multi-user spatial multiplexing combined with packet aggregation can significantly increase the performance of Wireless Local Area Networks (WLANs). In this letter, we present and evaluate a simple technique to perform packet aggregation in IEEE 802.11ac MU-MIMO (Multi-user Multiple Input Multiple Output) WLANs. Results show that in non-saturation conditions both the number of active stations (STAs) and the queue size have a significant impact on the system performance. If the number of stations is excessively high, the heterogeneity of destinations in the packets contained in the queue makes it difficult to take full advantage of packet aggregation. This effect can be alleviated by increasing the queue size, which increases the chances to schedule a large number of packets at each transmission, hence improving the system throughput at the cost of a higher delay

Human Resource Management und Unternehmungsstrategie

"Das aus den USA stammende Konzept Human Resource Management (HRM) findet in den letzten fünf Jahren verstärkt auch in der Bundesrepublik Deutschland Aufmerksamkeit. Eine vergleichende Analyse der einschlägigen US-amerikanischen und deutschsprachigen Literatur ergibt jedoch, daß weitgehend Deckungsgleichheit des HRM mit den bei uns schon lange geläufigen Konzepten Personalpolitik oder Personalmanagement besteht. Das spezifisch Neue an der heutigen Debatte über Human Resource Management sehe ich in der systematischen Integration bislang getrennt gehandhabter Personalbeschaffungs- und Entwicklungsmaßnahmen sowie deren Einbindung in Strategie- und Strukturentscheidungen aus einer General Management-Perspektive. Vor allem die systematische Stellung des HRM zur Unternehmensstrategie ist Gegenstand kontroverser Diskussionen in Theorie und Praxis des Personalmanagements. Nach einer kurzen Vorstellung des Konzepts des Human Resource Managements wird der Stellenwert des HRM in der strategischen Planung und anschließend im strategischen Management untersucht. Während das Konzept der strategischen Planung dazu verführt, viel zu anspruchsvolle, das Leistungsvermögen der gegebenen Human Resources überfordernde Strategien zu formulieren, neigt eine von den internen Ressourcen der Unternehmung ausgehende Konzeption des strategischen Managements zu einem bisweilen gefährlichen Festhalten am Bekannten und Bewährten. Die Lösung des Dilemmas wird in einem Konzept der integrativen Unternehmensentwicklung gesehen." (Autorenreferat)Personalpolitik - Konzeption, human resource management, Personalentwicklung, Unternehmensführung, Management

Technologies for space station autonomy

This report presents an informal survey of experts in the field of spacecraft automation, with recommendations for which technologies should be given the greatest development attention for implementation on the initial 1990's NASA Space Station. The recommendations implemented an autonomy philosophy that was developed by the Concept Development Group's Autonomy Working Group during 1983. They were based on assessments of the technologies' likely maturity by 1987, and of their impact on recurring costs, non-recurring costs, and productivity. The three technology areas recommended for programmatic emphasis were: (1) artificial intelligence expert (knowledge based) systems and processors; (2) fault tolerant computing; and (3) high order (procedure oriented) computer languages. This report also describes other elements required for Station autonomy, including technologies for later implementation, system evolvability, and management attitudes and goals. The cost impact of various technologies is treated qualitatively, and some cases in which both the recurring and nonrecurring costs might be reduced while the crew productivity is increased, are also considered. Strong programmatic emphasis on life cycle cost and productivity is recommended

On the analysis of youTube QoE in cellular networks through in-smartphone measurements

International audienceCellular-network operators are becoming increasingly interested in knowing the Quality of Experience (QoE) of their customers. QoE measurements represent today a main source of information to monitor, analyze, and subsequently manage operational networks. In this paper, we focus on the analysis of YouTube QoE in cellular networks, using QoE and distributed network measurements collected in real users' smart-phones. Relying on YoMoApp, a well-known tool for collecting YouTube smartphone measurements and QoE feedback in a crowdsourcing fashion, we have built a dataset covering about 360 different cellular users around the globe, throughout the past five years. Using this dataset, we study the characteristics of different QoE-relevant features for YouTube in smartphones. Measurements reveal a constant improvement of YouTube QoE in cellular networks over time, as well as an enhancement of the YouTube video streaming functioning in smartphones. Using the gathered measurements, we additionally investigate two case studies for YouTube QoE monitoring and analysis in cellular networks: the machine-learning-based prediction of QoE-relevant metrics from network-level measurements, and the modeling and assessment of YouTube QoE and user engagement in cellular networks and smartphone devices. Last but not least, we introduce the YoMoApp cloud dashboard to openly share smartphone YouTube QoE measurements, which allows anyone using the YoMoApp smartphone app to get immediate access to all the raw measurements collected at her devices