29,772 research outputs found
A resource management architecture for future mobile communications systems
This paper presents an overview of a hierarchical Resource Management architecture for future mobile communications systems. The architecture is designed to be generic and can therefore be adopted for a range of Radio Access Methodologies. In particular it provides a mechanism for radio resource management across airinterfaces such as those being defined for use with UMTS. Given the move towards packet-switched technologies both in the Core Network and the Radio Access Network [1], the architecture embraces the concept of statistical QoS applied to individual flows in the form of a commitment level. I
Separation Framework: An Enabler for Cooperative and D2D Communication for Future 5G Networks
Soaring capacity and coverage demands dictate that future cellular networks
need to soon migrate towards ultra-dense networks. However, network
densification comes with a host of challenges that include compromised energy
efficiency, complex interference management, cumbersome mobility management,
burdensome signaling overheads and higher backhaul costs. Interestingly, most
of the problems, that beleaguer network densification, stem from legacy
networks' one common feature i.e., tight coupling between the control and data
planes regardless of their degree of heterogeneity and cell density.
Consequently, in wake of 5G, control and data planes separation architecture
(SARC) has recently been conceived as a promising paradigm that has potential
to address most of aforementioned challenges. In this article, we review
various proposals that have been presented in literature so far to enable SARC.
More specifically, we analyze how and to what degree various SARC proposals
address the four main challenges in network densification namely: energy
efficiency, system level capacity maximization, interference management and
mobility management. We then focus on two salient features of future cellular
networks that have not yet been adapted in legacy networks at wide scale and
thus remain a hallmark of 5G, i.e., coordinated multipoint (CoMP), and
device-to-device (D2D) communications. After providing necessary background on
CoMP and D2D, we analyze how SARC can particularly act as a major enabler for
CoMP and D2D in context of 5G. This article thus serves as both a tutorial as
well as an up to date survey on SARC, CoMP and D2D. Most importantly, the
article provides an extensive outlook of challenges and opportunities that lie
at the crossroads of these three mutually entangled emerging technologies.Comment: 28 pages, 11 figures, IEEE Communications Surveys & Tutorials 201
Electric Power Allocation in a Network of Fast Charging Stations
In order to increase the penetration of electric vehicles, a network of fast
charging stations that can provide drivers with a certain level of quality of
service (QoS) is needed. However, given the strain that such a network can
exert on the power grid, and the mobility of loads represented by electric
vehicles, operating it efficiently is a challenging problem. In this paper, we
examine a network of charging stations equipped with an energy storage device
and propose a scheme that allocates power to them from the grid, as well as
routes customers. We examine three scenarios, gradually increasing their
complexity. In the first one, all stations have identical charging capabilities
and energy storage devices, draw constant power from the grid and no routing
decisions of customers are considered. It represents the current state of
affairs and serves as a baseline for evaluating the performance of the proposed
scheme. In the second scenario, power to the stations is allocated in an
optimal manner from the grid and in addition a certain percentage of customers
can be routed to nearby stations. In the final scenario, optimal allocation of
both power from the grid and customers to stations is considered. The three
scenarios are evaluated using real traffic traces corresponding to weekday rush
hour from a large metropolitan area in the US. The results indicate that the
proposed scheme offers substantial improvements of performance compared to the
current mode of operation; namely, more customers can be served with the same
amount of power, thus enabling the station operators to increase their
profitability. Further, the scheme provides guarantees to customers in terms of
the probability of being blocked by the closest charging station. Overall, the
paper addresses key issues related to the efficient operation of a network of
charging stations.Comment: Published in IEEE Journal on Selected Areas in Communications July
201
Integrating case-based reasoning and hypermedia documentation: an application for the diagnosis of a welding robot at Odense steel shipyard
Reliable and effective maintenance support is a vital consideration for the management within today's manufacturing environment. This paper discusses the development of a maintenance system for the world's largest robot welding facility. The development system combines a case-based reasoning approach for diagnosis with context information, as electronic on-line manuals, linked using open hypermedia technology. The work discussed in this paper delivers not only a maintenance system for the robot stations under consideration, but also a design framework for developing maintenance systems for other similar applications
Centaur operations at the space station
A study was conducted on the feasibility of using a Centaur vehicle as a testbed to demonstrate critical OTV technologies at the Space Station. Two Technology Demonstration Missions (TDMs) were identified: (1) Accommodations, and (2) Operations. The Accommodations TDM contained: (1) berthing, (2) checkout, maintenance and safing, and (3) payload integration missions. The Operations TDM contained: (1) a cryogenic propellant resupply mission, and (2) Centaur deployment activities. A modified Space Station Co-Orbiting Platform (COP) was selected as the optimum refueling and launch node due to safety and operational considerations. After completion of the TDMs, the fueled Centaur would carry out a mission to actually test deployment and help offset TDM costs. From the Station, the Centaur could carry a single payload in excess of 20,000 pounds to geosynchronous orbit or multiple payloads
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