185 research outputs found
How Much Can D2D Communication Reduce Content Delivery Latency in Fog Networks with Edge Caching?
A Fog-Radio Access Network (F-RAN) is studied in which cache-enabled Edge
Nodes (ENs) with dedicated fronthaul connections to the cloud aim at delivering
contents to mobile users. Using an information-theoretic approach, this work
tackles the problem of quantifying the potential latency reduction that can be
obtained by enabling Device-to-Device (D2D) communication over out-of-band
broadcast links. Following prior work, the Normalized Delivery Time (NDT) --- a
metric that captures the high signal-to-noise ratio worst-case latency --- is
adopted as the performance criterion of interest. Joint edge caching, downlink
transmission, and D2D communication policies based on compress-and-forward are
proposed that are shown to be information-theoretically optimal to within a
constant multiplicative factor of two for all values of the problem parameters,
and to achieve the minimum NDT for a number of special cases. The analysis
provides insights on the role of D2D cooperation in improving the delivery
latency.Comment: Submitted to the IEEE Transactions on Communication
Centralized Coded Caching with User Cooperation
In this paper, we consider the coded-caching broadcast network with user
cooperation, where a server connects with multiple users and the users can
cooperate with each other through a cooperation network. We propose a
centralized coded caching scheme based on a new deterministic placement
strategy and a parallel delivery strategy. It is shown that the new scheme
optimally allocate the communication loads on the server and users, obtaining
cooperation gain and parallel gain that greatly reduces the transmission delay.
Furthermore, we show that the number of users who parallelly send information
should decrease when the users' caching size increases. In other words, letting
more users parallelly send information could be harmful. Finally, we derive a
constant multiplicative gap between the lower bound and upper bound on the
transmission delay, which proves that our scheme is order optimal.Comment: 9 pages, submitted to ITW201
Information-Theoretic Analysis of D2D-Aided Pipelined Content Delivery in Fog-RAN
In a Fog-Radio Access Network (F-RAN), edge caching and fronthaul
connectivity to a cloud processor are utilized for the purpose of content
delivery. Additional Device-to-Device (D2D) communication capabilities can
support the operation of an F-RAN by alleviating fronthaul and cloud processing
load, and reducing the delivery time. In this work, basic limits on the
normalized delivery time (NDT) metric, which captures the high signal-to-noise
ratio worst-case latency for delivering any requested content to the users, are
derived. Assuming proactive offline caching, out-of-band D2D communication, and
an F-RAN with two edge nodes and two users, an information-theoretically
optimal caching and delivery strategy is presented. Unlike prior work, the NDT
performance is studied under pipelined transmission, whereby the edge nodes
transmit on the wireless channel while simultaneously receiving messages over
the fronthaul links, and the users transmit messages over the D2D links while
at the same time receiving on the wireless channel. Insights are provided on
the regimes in which D2D communication is beneficial, and the maximum
improvement to the latency is characterized.Comment: This work was presented at 2018 15th International Symposium on
Wireless Communication Systems (ISWCS). arXiv admin note: text overlap with
arXiv:1904.01256, arXiv:1801.0075
A review on green caching strategies for next generation communication networks
© 2020 IEEE. In recent years, the ever-increasing demand for networking resources and energy, fueled by the unprecedented upsurge in Internet traffic, has been a cause for concern for many service providers. Content caching, which serves user requests locally, is deemed to be an enabling technology in addressing the challenges offered by the phenomenal growth in Internet traffic. Conventionally, content caching is considered as a viable solution to alleviate the backhaul pressure. However, recently, many studies have reported energy cost reductions contributed by content caching in cache-equipped networks. The hypothesis is that caching shortens content delivery distance and eventually achieves significant reduction in transmission energy consumption. This has motivated us to conduct this study and in this article, a comprehensive survey of the state-of-the-art green caching techniques is provided. This review paper extensively discusses contributions of the existing studies on green caching. In addition, the study explores different cache-equipped network types, solution methods, and application scenarios. We categorically present that the optimal selection of the caching nodes, smart resource management, popular content selection, and renewable energy integration can substantially improve energy efficiency of the cache-equipped systems. In addition, based on the comprehensive analysis, we also highlight some potential research ideas relevant to green content caching
Edge-Caching Wireless Networks: Performance Analysis and Optimization
Edge-caching has received much attention as an efficient technique to reduce
delivery latency and network congestion during peak-traffic times by bringing
data closer to end users. Existing works usually design caching algorithms
separately from physical layer design. In this paper, we analyse edge-caching
wireless networks by taking into account the caching capability when designing
the signal transmission. Particularly, we investigate multi-layer caching where
both base station (BS) and users are capable of storing content data in their
local cache and analyse the performance of edge-caching wireless networks under
two notable uncoded and coded caching strategies. Firstly, we propose a coded
caching strategy that is applied to arbitrary values of cache size. The
required backhaul and access rates are derived as a function of the BS and user
cache size. Secondly, closed-form expressions for the system energy efficiency
(EE) corresponding to the two caching methods are derived. Based on the derived
formulas, the system EE is maximized via precoding vectors design and
optimization while satisfying a predefined user request rate. Thirdly, two
optimization problems are proposed to minimize the content delivery time for
the two caching strategies. Finally, numerical results are presented to verify
the effectiveness of the two caching methods.Comment: to appear in IEEE Trans. Wireless Commu
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