274 research outputs found
Soft Cache Hits and the Impact of Alternative Content Recommendations on Mobile Edge Caching
Caching popular content at the edge of future mobile networks has been widely
considered in order to alleviate the impact of the data tsunami on both the
access and backhaul networks. A number of interesting techniques have been
proposed, including femto-caching and "delayed" or opportunistic cache access.
Nevertheless, the majority of these approaches suffer from the rather limited
storage capacity of the edge caches, compared to the tremendous and rapidly
increasing size of the Internet content catalog. We propose to depart from the
assumption of hard cache misses, common in most existing works, and consider
"soft" cache misses, where if the original content is not available, an
alternative content that is locally cached can be recommended. Given that
Internet content consumption is increasingly entertainment-oriented, we believe
that a related content could often lead to complete or at least partial user
satisfaction, without the need to retrieve the original content over expensive
links. In this paper, we formulate the problem of optimal edge caching with
soft cache hits, in the context of delayed access, and analyze the expected
gains. We then show using synthetic and real datasets of related video contents
that promising caching gains could be achieved in practice
Backhaul-Aware Caching Placement for Wireless Networks
As the capacity demand of mobile applications keeps increasing, the backhaul
network is becoming a bottleneck to support high quality of experience (QoE) in
next-generation wireless networks. Content caching at base stations (BSs) is a
promising approach to alleviate the backhaul burden and reduce user-perceived
latency. In this paper, we consider a wireless caching network where all the
BSs are connected to a central controller via backhaul links. In such a
network, users can obtain the required data from candidate BSs if the data are
pre-cached. Otherwise, the user data need to be first retrieved from the
central controller to local BSs, which introduces extra delay over the
backhaul. In order to reduce the download delay, the caching placement strategy
needs to be optimized. We formulate such a design problem as the minimization
of the average download delay over user requests, subject to the caching
capacity constraint of each BS. Different from existing works, our model takes
BS cooperation in the radio access into consideration and is fully aware of the
propagation delay on the backhaul links. The design problem is a mixed integer
programming problem and is highly complicated, and thus we relax the problem
and propose a low-complexity algorithm. Simulation results will show that the
proposed algorithm can effectively determine the near-optimal caching placement
and provide significant performance gains over conventional caching placement
strategies.Comment: 6 pages, 3 figures, accepted to IEEE Globecom, San Diego, CA, Dec.
201
On the Interplay Between Edge Caching and HARQ in Fog-RAN
In a Fog Radio Access Network (Fog-RAN), edge caching is combined with
cloud-aided transmission in order to compensate for the limited hit probability
of the caches at the base stations (BSs). Unlike the typical wired scenarios
studied in the networking literature in which entire files are typically
cached, recent research has suggested that fractional caching at the BSs of a
wireless system can be beneficial. This paper investigates the benefits of
fractional caching in a scenario with a cloud processor connected via a
wireless fronthaul link to a BS, which serves a number of mobile users on a
wireless downlink channel using orthogonal spectral resources. The fronthaul
and downlink channels occupy orthogonal frequency bands. The end-to-end
delivery latency for given requests of the users depends on the HARQ processes
run on the two links to counteract fading-induced outages. An analytical
framework based on theory of Markov chains with rewards is provided that
enables the optimization of fractional edge caching at the BSs. Numerical
results demonstrate meaningful advantages for fractional caching due to the
interplay between caching and HARQ transmission. The gains are observed in the
typical case in which the performance is limited by the wireless downlink
channel and the file popularity distribution is not too skewed
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