31,689 research outputs found
Correlated shadowing and fading characterization of MIMO off-body channels by means of multiple autonomous on-body nodes
In off-body communication systems low-cost and compact transceivers are important for realistic applications. An autonomous off-body wireless node was designed and integrated onto a textile antenna. Channel measurements were performed for an indoor non line-off-sight 4x2 MIMO (Multiple-Input Multiple-Output) link using four off-body transmitting nodes and two similar fixed receiving nodes. The channel behavior is characterized as Rayleigh fading with lognormal shadowing and is fitted to a model determining fading and shadowing correlation matrices. The physics of the propagation is captured accurately by the model which is further used to simulate a link using diversity by means of Selection Combining, as implemented on the wireless nodes. The performance of measured and simulated links is compared in terms of outage probability level. The measurements and analysis confirm that the correlated shadowing and fading model is relevant for realistic off-body networks employing diversity by means of Selection Combining
Peak-Age Violation Guarantees for the Transmission of Short Packets over Fading Channels
We investigate the probability that the peak age of information in a
point-to-point communication system operating over a multiantenna wireless
fading channel exceeds a predetermined value. The packets are scheduled
according to a last-come first-serve policy with preemption in service, and are
transmitted over the channel using a simple automatic repetition request
protocol. We consider quadrature phase shift keying modulation, pilot-assisted
transmission, maximum-likelihood channel estimation, and mismatched scaled
nearest-neighbor decoding. Our analysis, which exploits nonasymptotic tools in
information theory, allows one to determine, for a given information packet
size, the physical layer parameters such as the SNR, the number of transmit and
receive antennas, the amount of frequency diversity to exploit, and the number
of pilot symbols, to ensure that the system operates below a target peak-age
violation probability.Comment: 6 pages, 6 figures. To be presented at Infocom 201
Turbo Packet Combining for Broadband Space-Time BICM Hybrid-ARQ Systems with Co-Channel Interference
In this paper, efficient turbo packet combining for single carrier (SC)
broadband multiple-input--multiple-output (MIMO) hybrid--automatic repeat
request (ARQ) transmission with unknown co-channel interference (CCI) is
studied. We propose a new frequency domain soft minimum mean square error
(MMSE)-based signal level combining technique where received signals and
channel frequency responses (CFR)s corresponding to all retransmissions are
used to decode the data packet. We provide a recursive implementation algorithm
for the introduced scheme, and show that both its computational complexity and
memory requirements are quite insensitive to the ARQ delay, i.e., maximum
number of ARQ rounds. Furthermore, we analyze the asymptotic performance, and
show that under a sum-rank condition on the CCI MIMO ARQ channel, the proposed
packet combining scheme is not interference-limited. Simulation results are
provided to demonstrate the gains offered by the proposed technique.Comment: 12 pages, 7 figures, and 2 table
Wireless Network Code Design and Performance Analysis using Diversity-Multiplexing Tradeoff
Network coding and cooperative communication have received considerable
attention from the research community recently in order to mitigate the adverse
effects of fading in wireless transmissions and at the same time to achieve
high throughput and better spectral efficiency. In this work, we design and
analyze deterministic and random network coding schemes for a cooperative
communication setup with multiple sources and destinations. We show that our
schemes outperform conventional cooperation in terms of the
diversity-multiplexing tradeoff (DMT). Specifically, it achieves the
full-diversity order at the expense of a slightly reduced multiplexing rate. We
establish the link between the parity-check matrix for a
systematic MDS code and the network coding coefficients in a cooperative
communication system of source-destination pairs and relays. We present
two ways to generate the network coding matrix: using the Cauchy matrices and
the Vandermonde matrices, and establish that they both offer the maximum
diversity order
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
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