15,037 research outputs found
On the Reliability of LTE Random Access: Performance Bounds for Machine-to-Machine Burst Resolution Time
Random Access Channel (RACH) has been identified as one of the major
bottlenecks for accommodating massive number of machine-to-machine (M2M) users
in LTE networks, especially for the case of burst arrival of connection
requests. As a consequence, the burst resolution problem has sparked a large
number of works in the area, analyzing and optimizing the average performance
of RACH. However, the understanding of what are the probabilistic performance
limits of RACH is still missing. To address this limitation, in the paper, we
investigate the reliability of RACH with access class barring (ACB). We model
RACH as a queuing system, and apply stochastic network calculus to derive
probabilistic performance bounds for burst resolution time, i.e., the worst
case time it takes to connect a burst of M2M devices to the base station. We
illustrate the accuracy of the proposed methodology and its potential
applications in performance assessment and system dimensioning.Comment: Presented at IEEE International Conference on Communications (ICC),
201
Real-time and Probabilistic Temporal Logics: An Overview
Over the last two decades, there has been an extensive study on logical
formalisms for specifying and verifying real-time systems. Temporal logics have
been an important research subject within this direction. Although numerous
logics have been introduced for the formal specification of real-time and
complex systems, an up to date comprehensive analysis of these logics does not
exist in the literature. In this paper we analyse real-time and probabilistic
temporal logics which have been widely used in this field. We extrapolate the
notions of decidability, axiomatizability, expressiveness, model checking, etc.
for each logic analysed. We also provide a comparison of features of the
temporal logics discussed
Modification of quantum measure in area tensor Regge calculus and positivity
A comparative analysis of the versions of quantum measure in the area tensor
Regge calculus is performed on the simplest configurations of the system. The
quantum measure is constructed in such the way that it reduces to the Feynman
path integral describing canonical quantisation if the continuous limit along
any of the coordinates is taken. As we have found earlier, it is possible to
implement also the correspondence principle (proportionality of the Lorentzian
(Euclidean) measure to (), being the action). For that a
certain kind of the connection representation of the Regge action should be
used, namely, as a sum of independent contributions of selfdual and
antiselfdual sectors (that is, effectively 3-dimensional ones). There are two
such representations, the (anti)selfdual connections being SU(2) or SO(3)
rotation matrices according to the two ways of decomposing full SO(4) group, as
SU(2) SU(2) or SO(3) SO(3). The measure from SU(2) rotations
although positive on physical surface violates positivity outside this surface
in the general configuration space of arbitrary independent area tensors. The
measure based on SO(3) rotations is expected to be positive in this general
configuration space on condition that the scale of area tensors considered as
parameters is bounded from above by the value of the order of Plank unit.Comment: 10 pages, plain LaTe
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