18,521 research outputs found
Fuzzy-logic framework for future dynamic cellular systems
There is a growing need to develop more robust and energy-efficient network architectures to cope with ever increasing traffic and energy demands. The aim is also to achieve energy-efficient adaptive cellular system architecture capable of delivering a high quality of service (QoS) whilst optimising energy consumption. To gain significant energy savings, new dynamic architectures will allow future systems to achieve energy saving whilst maintaining QoS at different levels of traffic demand. We consider a heterogeneous cellular system where the elements of it can adapt and change their architecture depending on the network demand. We demonstrate substantial savings of energy, especially in low-traffic periods where most mobile systems are over engineered. Energy savings are also achieved in high-traffic periods by capitalising on traffic variations in the spatial domain. We adopt a fuzzy-logic algorithm for the multi-objective decisions we face in the system, where it provides stability and the ability to handle imprecise data
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Technology in the United Kingdom’s Higher Education Context
Frequently, university-wide strategic decisions about technology are made without fully understanding the implications for resources, administration, teaching programmes, teaching practices and learning approaches, often resulting in technology-led course designs. Yet evidence shows that it is not the technology per se that changes learning and teaching but the pedagogical advantage we make of its use. In parallel, professional development programmes have largely focused on how to use the technology, resulting in replication or supplement of existing teaching practices, as opposed to transforming learning. In particular, the lack of specific context and reflection in professional development programmes can lead to a poor understanding of how and why students use technology effectively in learning. This requires a rethink of how we support initiatives that use technology in learning and teaching. Professional development programmes need to focus not only on the individual teacher, but also on support staff, departmental, and senior managers, so that appropriate policies, supporting structures and resources are in place for effective technology use. This chapter critiques these issues in the context of higher education in the United Kingdom and examines the political drivers that have pushed for the use of information communication technology (ICT) in learning and teaching. It considers this in the context of the United Kingdom Open University and how this institution has addressed some of the issues highlighted. Finally, a framework for professional development to support ICT in learning and teaching is presented aimed at holistically improving the student learning experience. This framework incorporates not only individual staff but also faculty and institutional management
Predicting a User's Next Cell With Supervised Learning Based on Channel States
Knowing a user's next cell allows more efficient resource allocation and
enables new location-aware services. To anticipate the cell a user will
hand-over to, we introduce a new machine learning based prediction system.
Therein, we formulate the prediction as a classification problem based on
information that is readily available in cellular networks. Using only Channel
State Information (CSI) and handover history, we perform classification by
embedding Support Vector Machines (SVMs) into an efficient pre-processing
structure. Simulation results from a Manhattan Grid scenario and from a
realistic radio map of downtown Frankfurt show that our system provides timely
prediction at high accuracy.Comment: The 14th IEEE International Workshop on Signal Processing Advances
for Wireless Communications (SPAWC), Darmstadt : Germany (2013
An Efficient Uplink Multi-Connectivity Scheme for 5G mmWave Control Plane Applications
The millimeter wave (mmWave) frequencies offer the potential of orders of
magnitude increases in capacity for next-generation cellular systems. However,
links in mmWave networks are susceptible to blockage and may suffer from rapid
variations in quality. Connectivity to multiple cells - at mmWave and/or
traditional frequencies - is considered essential for robust communication. One
of the challenges in supporting multi-connectivity in mmWaves is the
requirement for the network to track the direction of each link in addition to
its power and timing. To address this challenge, we implement a novel uplink
measurement system that, with the joint help of a local coordinator operating
in the legacy band, guarantees continuous monitoring of the channel propagation
conditions and allows for the design of efficient control plane applications,
including handover, beam tracking and initial access. We show that an
uplink-based multi-connectivity approach enables less consuming, better
performing, faster and more stable cell selection and scheduling decisions with
respect to a traditional downlink-based standalone scheme. Moreover, we argue
that the presented framework guarantees (i) efficient tracking of the user in
the presence of the channel dynamics expected at mmWaves, and (ii) fast
reaction to situations in which the primary propagation path is blocked or not
available.Comment: Submitted for publication in IEEE Transactions on Wireless
Communications (TWC
EVEREST IST - 2002 - 00185 : D23 : final report
Deliverable pĂşblic del projecte europeu EVERESTThis deliverable constitutes the final report of the project IST-2002-001858 EVEREST. After its successful completion, the project presents this document that firstly summarizes the context, goal and the approach objective of the project. Then it presents a concise summary of the major goals and results, as well as highlights the most valuable lessons derived form the project work. A list of deliverables and publications is included in the annex.Postprint (published version
Cell Selection in Wireless Two-Tier Networks: A Context-Aware Matching Game
The deployment of small cell networks is seen as a major feature of the next
generation of wireless networks. In this paper, a novel approach for cell
association in small cell networks is proposed. The proposed approach exploits
new types of information extracted from the users' devices and environment to
improve the way in which users are assigned to their serving base stations.
Examples of such context information include the devices' screen size and the
users' trajectory. The problem is formulated as a matching game with
externalities and a new, distributed algorithm is proposed to solve this game.
The proposed algorithm is shown to reach a stable matching whose properties are
studied. Simulation results show that the proposed context-aware matching
approach yields significant performance gains, in terms of the average utility
per user, when compared with a classical max-SINR approach.Comment: 11 pages, 11 figures, Journal article in ICST Wireless Spectrum, 201
Optimal mobility-aware admission control in content delivery networks
This paper addresses the problem of mobility management in Content Delivery Networks (CDN). We introduce a CDN architecture where admission control is performed at mobility aware access routers. We formulate a Markov Modulated Poisson Decision Process for access control that captures the bursty nature of data and packetized traffic together with the heterogeneity of multimedia services. The optimization of performance parameters, like the blocking probabilities and the overall utilization, is conducted and the structural properties of the optimal solutions are also studied. Heuristics are proposed to encompass the computational difficulties of the optimal solution when several classes of multimedia traffic are considered
On the Minimization of Handover Decision Instability in Wireless Local Area Networks
This paper addresses handover decision instability which impacts negatively
on both user perception and network performances. To this aim, a new technique
called The HandOver Decision STAbility Technique (HODSTAT) is proposed for
horizontal handover in Wireless Local Area Networks (WLAN) based on IEEE
802.11standard. HODSTAT is based on a hysteresis margin analysis that, combined
with a utilitybased function, evaluates the need for the handover and
determines if the handover is needed or avoided. Indeed, if a Mobile Terminal
(MT) only transiently hands over to a better network, the gain from using this
new network may be diminished by the handover overhead and short usage
duration. The approach that we adopt throughout this article aims at reducing
the minimum handover occurrence that leads to the interruption of network
connectivity (this is due to the nature of handover in WLAN which is a break
before make which causes additional delay and packet loss). To this end, MT
rather performs a handover only if the connectivity of the current network is
threatened or if the performance of a neighboring network is really better
comparing the current one with a hysteresis margin. This hysteresis should make
a tradeoff between handover occurrence and the necessity to change the current
network of attachment. Our extensive simulation results show that our proposed
algorithm outperforms other decision stability approaches for handover decision
algorithm.Comment: 13 Pages, IJWM
Network layer access control for context-aware IPv6 applications
As part of the Lancaster GUIDE II project, we have developed a novel wireless access point protocol designed to support the development of next generation mobile context-aware applications in our local environs. Once deployed, this architecture will allow ordinary citizens secure, accountable and convenient access to a set of tailored applications including location, multimedia and context based services, and the public Internet. Our architecture utilises packet marking and network level packet filtering techniques within a modified Mobile IPv6 protocol stack to perform access control over a range of wireless network technologies. In this paper, we describe the rationale for, and components of, our architecture and contrast our approach with other state-of-the- art systems. The paper also contains details of our current implementation work, including preliminary performance measurements
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