31 research outputs found
Errors and power when communicating with spins
We consider a network composed of a finite set of communicating nodes that send individual particles to each other, and each particle can carry binary information. Though our main motivation is related to communications in nanonetworks with electrons that carry magnetic spin as the bipolar information, one can also imagine that the particles may be molecules that use chirality to convey information. Since it is difficult for a particle to carry an identifier that conveys the identity of the “source” or “destination”, each node receives particles whose source cannot be ascertained since physical imperfections may result in particles being directed to the wrong destination in a manner that interferes with the correctly directed particles, and particles that should arrive at a node may be received by some other node. In addition, noise may randomly switch the polarity of particles, and in the case of magnetic spin we can also have the effect of entanglement.We estimate the error probability in such a multipoint network as a function of the rate of flow of particles, and the power consumption per communicating pair of nodes. We then design a bipolar detector and show that it can significantly eliminate the effect of errors
Routing Diverse Evacuees with Cognitive Packets
This paper explores the idea of smart building evacuation when evacuees can
belong to different categories with respect to their ability to move and their
health conditions. This leads to new algorithms that use the Cognitive Packet
Network concept to tailor different quality of service needs to different
evacuees. These ideas are implemented in a simulated environment and evaluated
with regard to their effectiveness.Comment: 7 pages, 7 figure
Capacity Based Evacuation with Dynamic Exit Signs
Exit paths in buildings are designed to minimise evacuation time when the
building is at full capacity. We present an evacuation support system which
does this regardless of the number of evacuees. The core concept is to even-out
congestion in the building by diverting evacuees to less-congested paths in
order to make maximal usage of all accessible routes throughout the entire
evacuation process. The system issues a set of flow-optimal routes using a
capacity-constrained routing algorithm which anticipates evolutions in path
metrics using the concept of "future capacity reservation". In order to direct
evacuees in an intuitive manner whilst implementing the routing algorithm's
scheme, we use dynamic exit signs, i.e. whose pointing direction can be
controlled. To make this system practical and minimise reliance on sensors
during the evacuation, we use an evacuee mobility model and make several
assumptions on the characteristics of the evacuee flow. We validate this
concept using simulations, and show how the underpinning assumptions may limit
the system's performance, especially in low-headcount evacuations
NEMESYS: Enhanced Network Security for Seamless Service Provisioning in the Smart Mobile Ecosystem
As a consequence of the growing popularity of smart mobile devices, mobile
malware is clearly on the rise, with attackers targeting valuable user
information and exploiting vulnerabilities of the mobile ecosystems. With the
emergence of large-scale mobile botnets, smartphones can also be used to launch
attacks on mobile networks. The NEMESYS project will develop novel security
technologies for seamless service provisioning in the smart mobile ecosystem,
and improve mobile network security through better understanding of the threat
landscape. NEMESYS will gather and analyze information about the nature of
cyber-attacks targeting mobile users and the mobile network so that appropriate
counter-measures can be taken. We will develop a data collection infrastructure
that incorporates virtualized mobile honeypots and a honeyclient, to gather,
detect and provide early warning of mobile attacks and better understand the
modus operandi of cyber-criminals that target mobile devices. By correlating
the extracted information with the known patterns of attacks from wireline
networks, we will reveal and identify trends in the way that cyber-criminals
launch attacks against mobile devices.Comment: Accepted for publication in Proceedings of the 28th International
Symposium on Computer and Information Sciences (ISCIS'13); 9 pages; 1 figur
Search in the Universe of Big Networks and Data
Searching in the Internet for some object characterised by its attributes in
the form of data, such as a hotel in a certain city whose price is less than
something, is one of our most common activities when we access the Web. We
discuss this problem in a general setting, and compute the average amount of
time and the energy it takes to find an object in an infinitely large search
space. We consider the use of N search agents which act concurrently. Both the
case where the search agent knows which way it needs to go to find the object,
and the case where the search agent is perfectly ignorant and may even head
away from the object being sought. We show that under mild conditions regarding
the randomness of the search and the use of a time-out, the search agent will
always find the object despite the fact that the search space is infinite. We
obtain a formula for the average search time and the average energy expended by
N search agents acting concurrently and independently of each other. We see
that the time-out itself can be used to minimise the search time and the amount
of energy that is consumed to find an object. An approximate formula is derived
for the number of search agents that can help us guarantee that an object is
found in a given time, and we discuss how the competition between search agents
and other agents that try to hide the data object, can be used by opposing
parties to guarantee their own success.Comment: IEEE Network Magazine - Special Issue on Networking for Big Data,
July-August 201
About the cumulative idle time in multiphase queues
The paper is designated to the analysis of queueing systems, arising in the network theory and communications theory (called multiphase queueing systems, tandem queues or series of queueing systems). Also we note that multiphase queueing systems can be useful for modelling practical multi-stage service systems in a variety of disciplines, especially on manufacturing (assembly lines), computer networking (packet switch structures), and in telecommunications (e.g. cellular mobile networks), etc. This research presents heavy traffic limit theorems for the cumulative idle time in multiphase queues. In this work, functional limit theorems are proved for the values of important probability characteristics of the queueing system (a cumulative idle time of a customer)
Mobile network anomaly detection and mitigation: The NEMESYS approach
Mobile malware and mobile network attacks are becoming a significant threat that accompanies the increasing popularity of smart phones and tablets. Thus in this paper we present our research vision that aims to develop a network-based security solution combining analytical modelling, simulation and learning, together with billing and control-plane data, to detect anomalies and attacks, and eliminate or mitigate their effects, as part of the EU FP7 NEMESYS project. These ideas are supplemented with a careful review of the state-of-the-art regarding anomaly detection techniques that mobile network operators may use to protect their infrastructure and secure users against malware
Adaptive Dispatching of Tasks in the Cloud
The increasingly wide application of Cloud Computing enables the
consolidation of tens of thousands of applications in shared infrastructures.
Thus, meeting the quality of service requirements of so many diverse
applications in such shared resource environments has become a real challenge,
especially since the characteristics and workload of applications differ widely
and may change over time. This paper presents an experimental system that can
exploit a variety of online quality of service aware adaptive task allocation
schemes, and three such schemes are designed and compared. These are a
measurement driven algorithm that uses reinforcement learning, secondly a
"sensible" allocation algorithm that assigns jobs to sub-systems that are
observed to provide a lower response time, and then an algorithm that splits
the job arrival stream into sub-streams at rates computed from the hosts'
processing capabilities. All of these schemes are compared via measurements
among themselves and with a simple round-robin scheduler, on two experimental
test-beds with homogeneous and heterogeneous hosts having different processing
capacities.Comment: 10 pages, 9 figure
Storms in mobile networks
Mobile networks are vulnerable to signalling attacks and storms caused by traffic that overloads the control plane through excessive signalling, which can be introduced via malware and mobile botnets. With the advent of machine-to-machine (M2M) communications over mobile networks, the potential for signalling storms increases due to the normally periodic nature of M2M traffic and the sheer number of communicating nodes. Several mobile network operators have also experienced signalling storms due to poorly designed applications that result in service outage. The radio resource control (RRC) protocol is particularly susceptible to such attacks, motivating this work within the EU FP7 NEMESYS project which presents simulations that clarify the temporal dynamics of user behavior and signalling, allowing us to suggest how such attacks can be detected and mitigated
Finding the principal points of a random variable
The p-principal points of a random variable X with finite second moment are those p points in R minimizing the expected squared distance from X to the closest point. Although the determination of principal points involves in general the resolution of a multiextremal optimization problem, existing procedures in the literature provide just a local optimum. In this paper we show that standard Global Optimization techniques can be applied.Ministerio de Ciencia y Tecnologí