1,251 research outputs found
NOMA Assisted Wireless Caching: Strategies and Performance Analysis
Conventional wireless caching assumes that content can be pushed to local
caching infrastructure during off-peak hours in an error-free manner; however,
this assumption is not applicable if local caches need to be frequently updated
via wireless transmission. This paper investigates a new approach to wireless
caching for the case when cache content has to be updated during on-peak hours.
Two non-orthogonal multiple access (NOMA) assisted caching strategies are
developed, namely the push-then-deliver strategy and the push-and-deliver
strategy. In the push-then-deliver strategy, the NOMA principle is applied to
push more content files to the content servers during a short time interval
reserved for content pushing in on-peak hours and to provide more connectivity
for content delivery, compared to the conventional orthogonal multiple access
(OMA) strategy. The push-and-deliver strategy is motivated by the fact that
some users' requests cannot be accommodated locally and the base station has to
serve them directly. These events during the content delivery phase are
exploited as opportunities for content pushing, which further facilitates the
frequent update of the files cached at the content servers. It is also shown
that this strategy can be straightforwardly extended to device-to-device
caching, and various analytical results are developed to illustrate the
superiority of the proposed caching strategies compared to OMA based schemes
Cache-enabled Heterogeneous Cellular Networks: Comparison and Tradeoffs
Caching popular contents at base stations (BSs) is a promising way to unleash
the potential of cellular heterogeneous networks (HetNets), where backhaul has
become a bottleneck. In this paper, we compare a cache-enabled HetNet where a
tier of multi-antenna macro BSs is overlaid by a tier of helper nodes having
caches but no backhaul with a conventional HetNet where the macro BSs tier is
overlaid by a tier of pico BSs with limited-capacity backhaul. We resort
stochastic geometry theory to derive the area spectral efficiencies (ASEs) of
these two kinds of HetNets and obtain the closed-form expressions under a
special case. We use numerical results to show that the helper density is only
1/4 of the pico BS density to achieve the same target ASE, and the helper
density can be further reduced by increasing cache capacity. With given total
cache capacity within an area, there exists an optimal helper node density that
maximizes the ASE.Comment: Accepted by IEEE International Conference on Communications (ICC)
2016. This version includes detailed proofs of the proposition
Proactive Caching for Energy-Efficiency in Wireless Networks: A Markov Decision Process Approach
Content caching in wireless networks provides a substantial opportunity to
trade off low cost memory storage with energy consumption, yet finding the
optimal causal policy with low computational complexity remains a challenge.
This paper models the Joint Pushing and Caching (JPC) problem as a Markov
Decision Process (MDP) and provides a solution to determine the optimal
randomized policy. A novel approach to decouple the influence from buffer
occupancy and user requests is proposed to turn the high-dimensional
optimization problem into three low-dimensional ones. Furthermore, a
non-iterative algorithm to solve one of the sub-problems is presented,
exploiting a structural property we found as \textit{generalized monotonicity},
and hence significantly reduces the computational complexity. The result
attains close performance in comparison with theoretical bounds from
non-practical policies, while benefiting from higher time efficiency than the
unadapted MDP solution.Comment: 6 pages, 6 figures, submitted to IEEE International Conference on
Communications 201
Cyber Insurance for Heterogeneous Wireless Networks
Heterogeneous wireless networks (HWNs) composed of densely deployed base
stations of different types with various radio access technologies have become
a prevailing trend to accommodate ever-increasing traffic demand in enormous
volume. Nowadays, users rely heavily on HWNs for ubiquitous network access that
contains valuable and critical information such as financial transactions,
e-health, and public safety. Cyber risks, representing one of the most
significant threats to network security and reliability, are increasing in
severity. To address this problem, this article introduces the concept of cyber
insurance to transfer the cyber risk (i.e., service outage, as a consequence of
cyber risks in HWNs) to a third party insurer. Firstly, a review of the
enabling technologies for HWNs and their vulnerabilities to cyber risks is
presented. Then, the fundamentals of cyber insurance are introduced, and
subsequently, a cyber insurance framework for HWNs is presented. Finally, open
issues are discussed and the challenges are highlighted for integrating cyber
insurance as a service of next generation HWNs.Comment: IEEE Communications Magazine (Heterogeneous Ultra Dense Networks
GreenDelivery: Proactive Content Caching and Push with Energy-Harvesting-based Small Cells
The explosive growth of mobile multimedia traffic calls for scalable wireless
access with high quality of service and low energy cost. Motivated by the
emerging energy harvesting communications, and the trend of caching multimedia
contents at the access edge and user terminals, we propose a paradigm-shift
framework, namely GreenDelivery, enabling efficient content delivery with
energy harvesting based small cells. To resolve the two-dimensional randomness
of energy harvesting and content request arrivals, proactive caching and push
are jointly optimized, with respect to the content popularity distribution and
battery states. We thus develop a novel way of understanding the interplay
between content and energy over time and space. Case studies are provided to
show the substantial reduction of macro BS activities, and thus the related
energy consumption from the power grid is reduced. Research issues of the
proposed GreenDelivery framework are also discussed.Comment: 15 pages, 5 figures, accepted by IEEE Communications Magazin
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