2,828 research outputs found
Investigation of Wireless Channel Asymmetry in Indoor Environments
Asymmetry is unquestionably an important characteristic of the wireless
propagation channel, which needs to be accurately modeled for wireless and
mobile communications, 5G networks, and associated applications such as
indoor/outdoor localization. This paper reports on the potential causes of
propagation asymmetry. Practical channel measurements at Khalifa University
premises proved that wireless channels are asymmetric in realistic scenarios.
Some important conclusions and recommendation are also summarized.Comment: Accepted in IEEE International Symposium on Antennas and Propagation
(APS17), San Diego, California, 9-14 Jul. 2017. arXiv admin note: substantial
text overlap with arXiv:1704.0687
Identifying Design Requirements for Wireless Routing Link Metrics
In this paper, we identify and analyze the requirements to design a new
routing link metric for wireless multihop networks. Considering these
requirements, when a link metric is proposed, then both the design and
implementation of the link metric with a routing protocol become easy.
Secondly, the underlying network issues can easily be tackled. Thirdly, an
appreciable performance of the network is guaranteed. Along with the existing
implementation of three link metrics Expected Transmission Count (ETX), Minimum
Delay (MD), and Minimum Loss (ML), we implement inverse ETX; invETX with
Optimized Link State Routing (OLSR) using NS-2.34. The simulation results show
that how the computational burden of a metric degrades the performance of the
respective protocol and how a metric has to trade-off between different
performance parameters
On a reliable handoff procedure for supporting mobility in wireless sensor networks
Wireless sensor network (WSN) applications such as
patients’ health monitoring in hospitals, location-aware
ambient intelligence, industrial monitoring /maintenance
or homeland security require the support of mobile nodes
or node groups. In many of these applications, the lack of
network connectivity is not admissible or should at least be
time bounded, i.e. mobile nodes cannot be disconnected
from the rest of the WSN for an undefined period of time.
In this context, we aim at reliable and real-time mobility
support in WSNs, for which appropriate handoff and rerouting
decisions are mandatory. This paper1 drafts a
mechanism and correspondent heuristics for taking
reliable handoff decisions in WSNs. Fuzzy logic is used to
incorporate the inherent imprecision and uncertainty of
the physical quantities at stake
A Survey of Clock Synchronization Over Packet-Switched Networks
Clock synchronization is a prerequisite for the realization of emerging applications in various domains such as industrial automation and the intelligent power grid. This paper surveys the standardized protocols and technologies for providing synchronization of devices connected by packet-switched networks. A review of synchronization impairments and the state-of-the-art mechanisms to improve the synchronization accuracy is then presented. Providing microsecond to sub-microsecond synchronization accuracy under the presence of asymmetric delays in a cost-effective manner is a challenging problem, and still an open issue in many application scenarios. Further, security is of significant importance for systems where timing is critical. The security threats and solutions to protect exchanged synchronization messages are also discussed
A Performance Analysis Model of TCP over Multiple Heterogeneous Paths for 5G Mobile Services
Driven by the primary requirement of emerging 5G mobile services, the demand
for concurrent multipath transfer (CMT) is still prominent. Yet, multipath
transport protocols are not widely adopted and TCP-based CMT schemes will still
be in dominant position in 5G. However, the performance of TCP flow transferred
over multiple heterogeneous paths is prone to the link quality asymmetry, the
extent of which was revealed to be significant by our field investigation. In
this paper, we present a performance analysis model for TCP over multiple
heterogeneous paths in 5G scenarios, where both bandwidth and delay asymmetry
are taken into consideration. The evaluation adopting parameters from field
investigation shows that the proposed model can achieve high accuracy in
practical environments. Some interesting inferences can be drawn from the
proposed model, such as the dominant factor that affect the performance of TCP
over heterogeneous networks, and the criteria of determining the appropriate
number of links to be used under different circumstances of path heterogeneity.
Thus, the proposed model can provide a guidance to the design of TCP-based CMT
solutions for 5G mobile services
SymbioCity: Smart Cities for Smarter Networks
The "Smart City" (SC) concept revolves around the idea of embodying
cutting-edge ICT solutions in the very fabric of future cities, in order to
offer new and better services to citizens while lowering the city management
costs, both in monetary, social, and environmental terms. In this framework,
communication technologies are perceived as subservient to the SC services,
providing the means to collect and process the data needed to make the services
function. In this paper, we propose a new vision in which technology and SC
services are designed to take advantage of each other in a symbiotic manner.
According to this new paradigm, which we call "SymbioCity", SC services can
indeed be exploited to improve the performance of the same communication
systems that provide them with data. Suggestive examples of this symbiotic
ecosystem are discussed in the paper. The dissertation is then substantiated in
a proof-of-concept case study, where we show how the traffic monitoring service
provided by the London Smart City initiative can be used to predict the density
of users in a certain zone and optimize the cellular service in that area.Comment: 14 pages, submitted for publication to ETT Transactions on Emerging
Telecommunications Technologie
Droplet: A New Denial-of-Service Attack on Low Power Wireless Sensor Networks
In this paper we present a new kind of Denial-of-Service attack against the PHY layer of low power wireless sensor networks. Overcoming the very limited range of jamming-based attacks, this attack can penetrate deep into a target network with high power efficiency. We term this the Droplet attack, as it attains enormous disruption by dropping small, payload-less frame headers to its victim's radio receiver, depriving the latter of bandwidth and sleep time. We demonstrate the Droplet attack's high damage rate to full duty-cycle receivers, and further show that a high frequency version of Droplet can even force nodes running on very low duty-cycle MAC protocols to drop most of their packets
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