62,864 research outputs found
Wireless industrial monitoring and control networks: the journey so far and the road ahead
While traditional wired communication technologies have played a crucial role in industrial monitoring and control networks over the past few decades, they are increasingly proving to be inadequate to meet the highly dynamic and stringent demands of today’s industrial applications, primarily due to the very rigid nature of wired infrastructures. Wireless technology, however, through its increased pervasiveness, has the potential to revolutionize the industry, not only by mitigating the problems faced by wired solutions, but also by introducing a completely new class of applications. While present day wireless technologies made some preliminary inroads in the monitoring domain, they still have severe limitations especially when real-time, reliable distributed control operations are concerned. This article provides the reader with an overview of existing wireless technologies commonly used in the monitoring and control industry. It highlights the pros and cons of each technology and assesses the degree to which each technology is able to meet the stringent demands of industrial monitoring and control networks. Additionally, it summarizes mechanisms proposed by academia, especially serving critical applications by addressing the real-time and reliability requirements of industrial process automation. The article also describes certain key research problems from the physical layer communication for sensor networks and the wireless networking perspective that have yet to be addressed to allow the successful use of wireless technologies in industrial monitoring and control networks
V2X Content Distribution Based on Batched Network Coding with Distributed Scheduling
Content distribution is an application in intelligent transportation system
to assist vehicles in acquiring information such as digital maps and
entertainment materials. In this paper, we consider content distribution from a
single roadside infrastructure unit to a group of vehicles passing by it. To
combat the short connection time and the lossy channel quality, the downloaded
contents need to be further shared among vehicles after the initial
broadcasting phase. To this end, we propose a joint infrastructure-to-vehicle
(I2V) and vehicle-to-vehicle (V2V) communication scheme based on batched sparse
(BATS) coding to minimize the traffic overhead and reduce the total
transmission delay. In the I2V phase, the roadside unit (RSU) encodes the
original large-size file into a number of batches in a rateless manner, each
containing a fixed number of coded packets, and sequentially broadcasts them
during the I2V connection time. In the V2V phase, vehicles perform the network
coded cooperative sharing by re-encoding the received packets. We propose a
utility-based distributed algorithm to efficiently schedule the V2V cooperative
transmissions, hence reducing the transmission delay. A closed-form expression
for the expected rank distribution of the proposed content distribution scheme
is derived, which is used to design the optimal BATS code. The performance of
the proposed content distribution scheme is evaluated by extensive simulations
that consider multi-lane road and realistic vehicular traffic settings, and
shown to significantly outperform the existing content distribution protocols.Comment: 12 pages and 9 figure
CASPR: Judiciously Using the Cloud for Wide-Area Packet Recovery
We revisit a classic networking problem -- how to recover from lost packets
in the best-effort Internet. We propose CASPR, a system that judiciously
leverages the cloud to recover from lost or delayed packets. CASPR supplements
and protects best-effort connections by sending a small number of coded packets
along the highly reliable but expensive cloud paths. When receivers detect
packet loss, they recover packets with the help of the nearby data center, not
the sender, thus providing quick and reliable packet recovery for
latency-sensitive applications. Using a prototype implementation and its
deployment on the public cloud and the PlanetLab testbed, we quantify the
benefits of CASPR in providing fast, cost effective packet recovery. Using
controlled experiments, we also explore how these benefits translate into
improvements up and down the network stack
Relay Selection for Wireless Communications Against Eavesdropping: A Security-Reliability Tradeoff Perspective
This article examines the secrecy coding aided wireless communications from a
source to a destination in the presence of an eavesdropper from a
security-reliability tradeoff (SRT) perspective. Explicitly, the security is
quantified in terms of the intercept probability experienced at the
eavesdropper, while the outage probability encountered at the destination is
used to measure the transmission reliability. We characterize the SRT of
conventional direct transmission from the source to the destination and show
that if the outage probability is increased, the intercept probability
decreases, and vice versa. We first demonstrate that the employment of relay
nodes for assisting the source-destination transmissions is capable of
defending against eavesdropping, followed by quantifying the benefits of
single-relay selection (SRS) as well as of multi-relay selection (MRS) schemes.
More specifically, in the SRS scheme, only the single "best" relay is selected
for forwarding the source signal to the destination, whereas the MRS scheme
allows multiple relays to participate in this process. It is illustrated that
both the SRS and MRS schemes achieve a better SRT than the conventional direct
transmission, especially upon increasing the number of relays. Numerical
results also show that as expected, the MRS outperforms the SRS in terms of its
SRT. Additionally, we present some open challenges and future directions for
the wireless relay aided physical-layer security.Comment: 16 pages, IEEE Network, 201
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