235 research outputs found
Cross-Layer Optimization of Fast Video Delivery in Cache-Enabled Relaying Networks
This paper investigates the cross-layer optimization of fast video delivery
and caching for minimization of the overall video delivery time in a two-hop
relaying network. The half-duplex relay nodes are equipped with both a cache
and a buffer which facilitate joint scheduling of fetching and delivery to
exploit the channel diversity for improving the overall delivery performance.
The fast delivery control is formulated as a two-stage functional non-convex
optimization problem. By exploiting the underlying convex and quasi-convex
structures, the problem can be solved exactly and efficiently by the developed
algorithm. Simulation results show that significant caching and buffering gains
can be achieved with the proposed framework, which translates into a reduction
of the overall video delivery time. Besides, a trade-off between caching and
buffering gains is unveiled.Comment: 7 pages, 4 figures; accepted for presentation at IEEE Globecom, San
Diego, CA, Dec. 201
Caching in Heterogeneous Networks
A promising solution in order to cope with the massive request of wireless data traffic
consists of having replicas of the potential requested content memorized across the
network. In cache-enabled heterogeneous networks, content is pre-fetched close to the
users during network off-peak periods in order to directly serve the users when the
network is congested. In fact, the main idea behind caching is the replacement of
backhaul capacity with storage capabilities, for example, at the edge of the network.
Caching content at the edge of heterogeneous networks not only leads to significantly
reduce the traffic congestion in the backhaul link but also leads to achieve higher
levels of energy efficiency. However, the good performance of a system foresees a deep
analysis of the possible caching techniques. Due to the physical limitation of the caches’
size and the excessive amount of content, the design of caching policies which define
how the content has to be cached and select the likely data to store is crucial.
Within this thesis, caching techniques for storing and delivering the content in
heterogeneous networks are investigated from two different aspects. The first part
of the thesis is focused on the reduction of the power consumption when the cached
content is delivered over an Gaussian interference channel and per-file rate constraints
are imposed. Cooperative approaches between the transmitters in order to mitigate
the interference experienced by the users are analyzed. Based on such approaches, the
caching optimization problem for obtaining the best cache allocation solution (in the
sense of minimizing the average power consumption) is proposed. The second part of
the thesis is focused on caching techniques at packet level with the aim of reducing
the transmissions from the core of an heterogeneous network. The design of caching
schemes based on rate-less codes for storing and delivering the cached content are
proposed. For each design, the placement optimization problem which minimizes the
transmission over the backhaul link is formulated
Cloud-Edge Non-Orthogonal Transmission for Fog Networks with Delayed CSI at the Cloud
In a Fog Radio Access Network (F-RAN), the cloud processor (CP) collects
channel state information (CSI) from the edge nodes (ENs) over fronthaul links.
As a result, the CSI at the cloud is generally affected by an error due to
outdating. In this work, the problem of content delivery based on fronthaul
transmission and edge caching is studied from an information-theoretic
perspective in the high signal-to-noise ratio (SNR) regime. For the set-up
under study, under the assumption of perfect CSI, prior work has shown the
(approximate or exact) optimality of a scheme in which the ENs transmit
information received from the cloud and cached contents over orthogonal
resources. In this work, it is demonstrated that a non-orthogonal transmission
scheme is able to substantially improve the latency performance in the presence
of imperfect CSI at the cloud.Comment: 5 pages, 4 figures, submitte
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