3,438 research outputs found
Optimal Control of Wireless Computing Networks
Augmented information (AgI) services allow users to consume information that
results from the execution of a chain of service functions that process source
information to create real-time augmented value. Applications include real-time
analysis of remote sensing data, real-time computer vision, personalized video
streaming, and augmented reality, among others. We consider the problem of
optimal distribution of AgI services over a wireless computing network, in
which nodes are equipped with both communication and computing resources. We
characterize the wireless computing network capacity region and design a joint
flow scheduling and resource allocation algorithm that stabilizes the
underlying queuing system while achieving a network cost arbitrarily close to
the minimum, with a tradeoff in network delay. Our solution captures the unique
chaining and flow scaling aspects of AgI services, while exploiting the use of
the broadcast approach coding scheme over the wireless channel.Comment: 30 pages, journa
Distortion Minimization in Gaussian Layered Broadcast Coding with Successive Refinement
A transmitter without channel state information (CSI) wishes to send a
delay-limited Gaussian source over a slowly fading channel. The source is coded
in superimposed layers, with each layer successively refining the description
in the previous one. The receiver decodes the layers that are supported by the
channel realization and reconstructs the source up to a distortion. The
expected distortion is minimized by optimally allocating the transmit power
among the source layers. For two source layers, the allocation is optimal when
power is first assigned to the higher layer up to a power ceiling that depends
only on the channel fading distribution; all remaining power, if any, is
allocated to the lower layer. For convex distortion cost functions with convex
constraints, the minimization is formulated as a convex optimization problem.
In the limit of a continuum of infinite layers, the minimum expected distortion
is given by the solution to a set of linear differential equations in terms of
the density of the fading distribution. As the bandwidth ratio b (channel uses
per source symbol) tends to zero, the power distribution that minimizes
expected distortion converges to the one that maximizes expected capacity.
While expected distortion can be improved by acquiring CSI at the transmitter
(CSIT) or by increasing diversity from the realization of independent fading
paths, at high SNR the performance benefit from diversity exceeds that from
CSIT, especially when b is large.Comment: Accepted for publication in IEEE Transactions on Information Theor
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