391 research outputs found
Radio access protocols with multi-user detection for URLLC in 5G
No full textIn this paper we present collision-free and contention-based radio access protocols for sporadic small data packet transmissions in the 5G uplink. We compare them by computer simulations with respect to throughput, latency, and final negative acknowledgement (NACK) probability. Based on the performance evaluation results, we analyze the tradeoff between the number of transmission attempts of a packet and advanced collision resolution methods. Moreover, we investigate the impact of multi-user detection on the protocol performance. The key outcome of our study is that contention-based radio access protocols combined with multi-user detection are well suited for ultra-reliable low-latency communications (URLLC), providing error rates down to 10-5 in a low traffic load scenario
Analysis of 5G Radio Access Protocols for Uplink URLLC in Connection-Less Mode
No full textUplink ultra-reliable low-latency communication (URLLC) entails dependable and almost instantaneous packet transmissions from industrial Internet of Things terminals to the serving base station. While most of the literature addresses terminals which are always connected to the network, here we focus on terminals which would benefit from a connection-less radio access, because they are employed for low-duty-cycle applications related to industrial safety, while still requiring a URLLC quality of service. Our aim is to investigate the performance of two standard-compliant radio access protocols, i.e., the one-stage approach and the two-stage approach, in supporting uplink URLLC in connection-less mode. We derive a mathematical model of these protocols under the assumption that the base station has multi-user detection capabilities. The model is used to cross-validate our simulator and calibrate the protocols together with the validated simulator, providing well-grounded guidelines for the selection of the parameter values. The simulator is finally exploited to assess the URLLC performance of the proposed protocols. The key outcome of this study is that, when combined with multi-user detection at the base station and after an appropriate system parameters selection, the one-stage approach satisfies the desired URLLC service requirements, thus representing a viable solution to support safety-related industrial applications
Comparison of collision-free and contention-based radio access protocols for the Internet of things
No full textThe fifth-generation (5G) cellular networks will face
the challenge of integrating the traditional broadband services
with the Internet of Things (IoT), which is characterized by
sporadic uplink transmissions of small data packets. Indeed,
the access procedure of the previous generation cellular network
(4G) is not able to support IoT traffic efficiently, because
it requires a large amount of signaling for the connection
setup before the actual data transmission. In this context,
we introduce two innovative radio access protocols for sporadic
transmissions of small data packets, which are suitable for
5G networks, because they provide a resource-efficient packet
delivery exploiting a connectionless approach. The core of this
paper resides in the derivation of an analytical framework to
evaluate the performance of all the aforementioned protocols.
The final goal is the comparison between 4G and 5G radio access
solutions employing both our analytical framework and computer
simulations. The performance evaluation results show the benefits
of the protocols envisioned for 5G in terms of signaling overhead
and access latency
Open Access and Academic Library Public Services: Roles for Reference and Instruction
No full textPaper presented at the IFLA Satellite Preconference: Open Access to Science Information; Trends, Models and Strategies for Libraries, Chania, Crete, Greece. Aug. 6-8, 2010. This paper is published as a chapter in the DeGruyter monograph entitled: Open Access to STM Information: Trends, Models and Strategies for Libraries. Edited by Anthi Katsirikou, Berlin/Munich: De Gruyter Saur, 2011, pp. 29-38.(IFLA Publications; Nr. 153)The published version of the chapter is available in the DeGruyter published monograph available from: http://www.ifla.org/publications/ifla-publications-series-153. http://dx.doi.org/10.1515/9783110263749.2
Taking stock of open access : progress and issues
No full textPurpose - Aims at providing a broad overview of some of the issues emerging from the growth in open access publishing, with specific reference to the use of repositories and open access journals. Design/methodology/approach - A paper largely based on specific experience with institutional repositories and the internationally run E-library and information science (LIS) archive. Findings - The open access initiative is dramatically transforming the process of scholarly communication bringing great benefits to the academic world with an, as yet, uncertain outcome for commercial publishers. Practical implications - Outlines the benefits of the open access movement with reference to repositories and open access journals to authors and readers alike and gives some food for thought on potential barriers to the complete permeation of the open access model, such as copyright restrictions and version control issues. Some illustrative examples of country-specific initiatives and the international E-LIS venture are given. Originality/value - An attempt to introduce general theories and practical implications of the open access movement to those largely unfamiliar with the movement
Robust and Flexible Tracking of Vehicles Exploiting Soft Map-Matching and Data Fusion
No full textAccurate positioning of vehicles and pedestrians is crucial for enhancing road safety. In this paper, we propose and compare two implementations based on Unscented Kalman Filter (UKF) and Particle Filter (PF) to perform trajectory estimation with sensor fusion. For the latter, a novel soft map-matching technique is applied on top of a PF. The main benefit of our method is the possibility of detecting reliably critical situations, like vehicles skidding off the road. Moreover, we can reduce the positioning error by 45% w.r.t. prior art approaches. Our solution can be implemented as a cloud service in the 5G mobile radio network
Presentation of Gondang Sabangunan and Uning-Uningan by Sanggar Gemilang Sentosa at the Saur Matua Ceremony in Medan City: Analysis of Musical Function and Structure
No full textThis thesis is entitled "Presentation of Gondang Sabangunan and Uning-Uningan by Sanggar Gemilang Sentosa at the Saur Matua Ceremony in Medan City: Analysis of Musical Function and Structure". The purpose of this study is to analyze the function and musical structure of the presentation of Gondang Sabangunan and Uning-Uningan by Sanggar Gemilang Sentosa in Glugur Darat Village, East Medan District, Medan. To answer the above problems, the author uses Bruno Nettl's structural analysis theory, namely about the treasury of tones, scales, tonality, intervals, melodic cantour, rhythm, tempo, and form. Allan P. Merriam's theory about the meaning of use and function in the context of music. The research method used is a descriptive qualitative research method by conducting observations, interviews, and recordings in the field. The results of this study are the death ceremony of Saur Matua which in its traditional event uses gondang sabangunan and uning-uningan.76 PagesSkripsi Sarjan
Hybrid retransmission scheme for QoS-defined 5G ultra-reliable low-latency communications
No full textOne of the key challenges in next generation 5G networks is to deliver Ultra-Reliable Low-Latency Communications (URLLC). Recent advances in information theory about principles
that govern short packet transmissions pointed out that, for the URLLC typical short packet dimension, achieving higher reliabilities comes at the price of a lower maximum achievable
rate, thus reducing spectral efficiency. Hence, retransmissions are used in LTE and planned for 5G, in order to achieve reliability with a better resource consumption, at the price of increased
packet latency. Keeping in mind the stringent requirements for URLLC, in this paper we analyze the tradeoffs and limitations of retransmission strategies considered in the literature, either too
demanding in terms of wireless resources and aggressive URLLC performance or the contrary. Then we propose a novel scheme, whose purpose is to match the URLLC requirements, minimizing the resource consumption. We evaluate the schemes through simulations and highlight the advantages of the proposed scheme, providing also insights on the performance HARQ techniques in URLLC scenarios
A transitory regime : water supply in Conakry, Guinea
No full textBoth consumers and the government benefited from reform of the water system in Conakry, Guinea, whose deterioration since independence had become critical by the mid-1980s. Less than 40 percent of Conakry's population had access to piped water - low even by regional standards - and service was intermittent, at best, for the few who had connections. The public agency in charge of the sector was inefficient, overstaffed, and virtually insolvent. In several ways, the reform introduced to the sector in 1989 under a World Bank-led project was remarkable. It showed that even in a weak institutional environment, where contracts are hard to enforce and political interference is common, private sector participation can improve sector performance. The authors discuss the mechanismsthat made progress possible and identify factors that inhibit the positive effects of reform. Water has become very expensive, the number of connections has increased very slowly, and conflicts have developed between SEEG (the private operator) and SONEG (the state agency). Among the underlying problems: a) The lack of strong, stable institutions. b) The lack of an independent agency capable of restraining arbitrary government action, regulating the private operator, and enforcing contractual arrangements. c) The lack of adequate conflict resolution mechanisms for contract disputes. d) Weak administrative capacity.Environmental Economics&Policies,Water and Industry,Water Conservation,Decentralization,Water Supply and Systems,Town Water Supply and Sanitation,Water and Industry,Water Supply and Sanitation Governance and Institutions,Environmental Economics&Policies,Water Conservation
Genome-wide analysis and expression characteristics of small auxin-up RNA (SAUR) genes in moso bamboo (Phyllostachys edulis)
No full textMoso bamboo (Phyllostachys edulis) is well-known for its rapid shoot growth. Auxin exerts pleiotropic effects on plant growth. The small auxin-up RNA (SAUR) genes are early auxin-responsive genes involved in plant growth. In total, 38 SAUR genes were identified in P. edulis (PheSAUR). A comprehensive overview of the PheSAUR gene family is presented, including the gene structures, phylogeny and subcellular location predictions. A transcriptome analysis indicated that 37 (except PheSAUR18) of the PheSAUR genes were expressed during shoot growth process and the PheSAUR genes were differentially expressed. Furthermore, quantitative real-time PCR analysis indicated that all of the PheSAUR genes could be induced in different tissues of seedlings and that 37 (except PheSAUR41) of the PheSAUR genes were up-regulated after indole-3-acetic acid (IAA) treatment. These results reveal a comprehensive overview of the PheSAUR gene family and may pave the way for deciphering their functions during bamboo development.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author
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