1,720,958 research outputs found
Modeling RACH Arrivals and Collisions for Human-Type Communication
Full text linkThis letter proposes an analytical model to evaluate the collision probability on the Random-Access CHannel (RACH) in Long-Term Evolution systems as a function of the number of user equipment, the number of available preambles, and the Inter-arrival times of the RACH Requests (IRRs) of the average user. The model for the IRR of the average user is obtained from real traffic data captured at the eNodeB of a mobile operator, and is derived by emulating the radio resource control (RRC) state machine for different RRCs Inactivity timer (RRCIT) settings. The results of this letter suggest that when RRCIT is set to a few seconds, a mixture model is more accurate than the Poisson hypothesis both in modeling the IRR and in estimating the RACH performance
LTE traffic analysis and application behavior characterization
No full textThe deployment of LTE and the explosion of smart-phones and tablet market increase the requirements of mobile connectivity, together with a change in the users expectations in terms of bandwidth, access speed, reliability and QoS man-agement. In this new network scenario, traffic characterization and monitoring is of paramount relevance in order to prevent possible pitfalls during the deployment of new services. Hence, the paper presents the traffic analysis of a deployed eNodeB in a commercial network. The analysis is aimed at detecting traffic features at call and frame level, also accounting for the handset types
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
On RACH preambles separation between human and machine type communication
No full textIn LTE and LTE-Advanced systems the rate of requests on the Random Access CHannel (RACH) can be high. Indeed, the Machine Type Communication (MTC) implies to have a high number of devices that need to request radio resources for transmitting small amount of data. Furthermore, reducing the time in which radio resources are allocated to Human Type Communications (HTC) for energy savings purposes, may lead to radio access network overload as well. In this framework, this paper aims at providing a set of guidelines for the resource allocation task in the RACH. In particular, the study investigates the impact of both the backoff indicator scheme and the maximum number of retransmissions on the RACH performance parameters. The rate of RACH requests associated with the HTC traffic is modelled by inferring their statistical properties starting from a dataset acquired in an operational eNodeB. The estimation of the average delay and the average number of maximum retransmissions gives insights on how many preambles should be reserved for HTC in order to meet the target performance, and provides suggestions on the configuration of the backoff indicator
LTE traffic analysis for signalling load and energy consumption trade-off in mobile networks
No full textIn the LTE systems, battery lifetime and network traffic overhead on control plane may be largely affected by the Discontinuous reception (DRX) configuration and the Radio Resource Control (RRC) Inactivity Timer. In this scenario, the paper proposes an analysis aimed at defining how to properly set the RRC Inactivity Timer to achieve a trade-off between energy savings and traffic overhead on the control plane. The analysis is based on an energy consumption model, whose key parameters are inferred directly from passive measurements carried out by monitoring a commercial eNodeB of one of the Italian Mobile Operators. The results suggest that taking into account the network traffic characteristics is possible to find the RRC inactivity timer value that permits to save energy of user's device while the increase of the signalling load is limited
Test and monitoring of LTE network: A step towards low cost solutions based on NetFPGA
No full textThe paper presents the lessons learned during the test activity of LTE network in Telecom Italia Lab. The issues mainly regard the lack of low cost and flexible monitoring and test platforms easy to reconfigure and adapt to the diverse network interfaces. The paper presents the design guideline for the development of FPGA-based devices able to overcome the presented issues. Exploiríng the NetFPGA platform and re-using the available open-source software, a preliminary prototype implementing some ideas is presented Furthermore, the paper shows the preliminary results obtained during the utilization of the NetFPGA prototype in the test activities
Design and development of management functions for distributed monitoring based on SDN-based network
No full textIn the latest years, we have seen a fast evolution of Internet systems and a remarkable increase of the number and variety of services required. The need of new architectural solutions has led to the creation of new tools that allow to develop more flexible and dynamic networks. Software Defined Networking (SDN) goes in this direction, offering a new way to manage networks, based on programmability, virtualization of the network and centralization of decision processes. In this article we will analyse how it is possible to deploy these new tools to realize some fundamental network functions also for monitoring systems. We will also show a real testbed where we implemented the functions we describe, and we will show the experimental results obtained with it
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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