50,135 research outputs found
Ultra-Reliable Communication in 5G Wireless Systems
Wireless 5G systems will not only be "4G, but faster". One of the novel
features discussed in relation to 5G is Ultra-Reliable Communication (URC), an
operation mode not present in today's wireless systems. URC refers to provision
of certain level of communication service almost 100 % of the time. Example URC
applications include reliable cloud connectivity, critical connections for
industrial automation and reliable wireless coordination among vehicles. This
paper puts forward a systematic view on URC in 5G wireless systems. It starts
by analyzing the fundamental mechanisms that constitute a wireless connection
and concludes that one of the key steps towards enabling URC is revision of the
methods for encoding control information (metadata) and data. It introduces the
key concept of Reliable Service Composition, where a service is designed to
adapt its requirements to the level of reliability that can be attained. The
problem of URC is analyzed across two different dimensions. The first dimension
is the type of URC problem that is defined based on the time frame used to
measure the reliability of the packet transmission. Two types of URC problems
are identified: long-term URC (URC-L) and short-term URC (URC-S). The second
dimension is represented by the type of reliability impairment that can affect
the communication reliability in a given scenario. The main objective of this
paper is to create the context for defining and solving the new engineering
problems posed by URC in 5G.Comment: To be presented at the 1st International Conference on 5G for
Ubiquitous Connectivit
IETF standardization in the field of the Internet of Things (IoT): a survey
Smart embedded objects will become an important part of what is called the Internet of Things. However, the integration of embedded devices into the Internet introduces several challenges, since many of the existing Internet technologies and protocols were not designed for this class of devices. In the past few years, there have been many efforts to enable the extension of Internet technologies to constrained devices. Initially, this resulted in proprietary protocols and architectures. Later, the integration of constrained devices into the Internet was embraced by IETF, moving towards standardized IP-based protocols. In this paper, we will briefly review the history of integrating constrained devices into the Internet, followed by an extensive overview of IETF standardization work in the 6LoWPAN, ROLL and CoRE working groups. This is complemented with a broad overview of related research results that illustrate how this work can be extended or used to tackle other problems and with a discussion on open issues and challenges. As such the aim of this paper is twofold: apart from giving readers solid insights in IETF standardization work on the Internet of Things, it also aims to encourage readers to further explore the world of Internet-connected objects, pointing to future research opportunities
Moving Object Trajectories Meta-Model And Spatio-Temporal Queries
In this paper, a general moving object trajectories framework is put forward
to allow independent applications processing trajectories data benefit from a
high level of interoperability, information sharing as well as an efficient
answer for a wide range of complex trajectory queries. Our proposed meta-model
is based on ontology and event approach, incorporates existing presentations of
trajectory and integrates new patterns like space-time path to describe
activities in geographical space-time. We introduce recursive Region of
Interest concepts and deal mobile objects trajectories with diverse
spatio-temporal sampling protocols and different sensors available that
traditional data model alone are incapable for this purpose.Comment: International Journal of Database Management Systems (IJDMS) Vol.4,
No.2, April 201
Taming Uncertainty in the Assurance Process of Self-Adaptive Systems: a Goal-Oriented Approach
Goals are first-class entities in a self-adaptive system (SAS) as they guide
the self-adaptation. A SAS often operates in dynamic and partially unknown
environments, which cause uncertainty that the SAS has to address to achieve
its goals. Moreover, besides the environment, other classes of uncertainty have
been identified. However, these various classes and their sources are not
systematically addressed by current approaches throughout the life cycle of the
SAS. In general, uncertainty typically makes the assurance provision of SAS
goals exclusively at design time not viable. This calls for an assurance
process that spans the whole life cycle of the SAS. In this work, we propose a
goal-oriented assurance process that supports taming different sources (within
different classes) of uncertainty from defining the goals at design time to
performing self-adaptation at runtime. Based on a goal model augmented with
uncertainty annotations, we automatically generate parametric symbolic formulae
with parameterized uncertainties at design time using symbolic model checking.
These formulae and the goal model guide the synthesis of adaptation policies by
engineers. At runtime, the generated formulae are evaluated to resolve the
uncertainty and to steer the self-adaptation using the policies. In this paper,
we focus on reliability and cost properties, for which we evaluate our approach
on the Body Sensor Network (BSN) implemented in OpenDaVINCI. The results of the
validation are promising and show that our approach is able to systematically
tame multiple classes of uncertainty, and that it is effective and efficient in
providing assurances for the goals of self-adaptive systems
Throughput Analysis of Buffer-Constrained Wireless Systems in the Finite Blocklength Regime
In this paper, wireless systems operating under queueing constraints in the
form of limitations on the buffer violation probabilities are considered. The
throughput under such constraints is captured by the effective capacity
formulation. It is assumed that finite blocklength codes are employed for
transmission. Under this assumption, a recent result on the channel coding rate
in the finite blocklength regime is incorporated into the analysis and the
throughput achieved with such codes in the presence of queueing constraints and
decoding errors is identified. Performance of different transmission strategies
(e.g., variable-rate, variable-power, and fixed-rate transmissions) is studied.
Interactions between the throughput, queueing constraints, coding blocklength,
decoding error probabilities, and signal-to-noise ratio are investigated and
several conclusions with important practical implications are drawn
Federal Workforce: Sustained Attention to Human Capital Leading Practices Can Help Improve Agency Performance
[Excerpt] A careful consideration of federal pay is an essential part of fiscal stewardship and is necessary to support the recruitment and retention of a talented, agile, and high-performing federal workforce. High-performing organizations have found that the life-cycle of human capital management activities—including workforce planning, recruitment, on-boarding, compensation, engagement, succession planning, and retirement programs—need to be aligned for the cost-effective achievement of an organization’s mission. However, despite some improvements, strategic human capital management—and more specifically, skills gaps in mission critical occupations—continues to be a GAO high-risk area.
This testimony is based on a body of GAO work primarily issued between June 2012 and March 2017. It focuses on (1) lessons learned in creating a more market driven, results-oriented approach to federal pay, and (2) opportunities, in addition to pay and benefits, that OPM and agencies could use to be more competitive in the labor market and address skills gaps
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