Abstract
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.
Highlights
Proactive caching of popular content at the Edge Nodes (ENs) is an effective way of reducing delivery time [1], [2]
Vectors um, xm, yk, zk, and vk, which represents fronthaul message sent to EN m ∈ [M], output codeword transmitted by EN m, signal received by user k ∈ [K] on the shared wireless channel, white Gaussian noise at user k, and D2D message transmitted by user k, respectively, have T entries, where T is the delivery latency
We have studied the benefits of out-of-band broadcast Device-to-Device (D2D) communication for content delivery in a general Fog-Radio Access Network (F-RAN) with arbitrary number of Edge Nodes (ENs) and users
Summary
Proactive caching of popular content at the Edge Nodes (ENs) is an effective way of reducing delivery time [1], [2]. In this paper, motivated by the emergence of Device-toDevice (D2D) communication solutions [8]–[10], we study the impact of D2D communication on the delivery latency of F-RAN architectures To this end, we consider a D2D-aided F-RAN, illustrated, in which edge caching, fronthaul connectivity to a CP, and users’ cooperation are leveraged to reduce content delivery time. For the general case of arbitrary number of M and K, we prove that a more practical D2D strategy based on compress-and-forward achieves the minimum NDT to within a multiplicative factor of 2 This implies that the optimality gap of this strategy does not scale with the size of the system. Notation: For any positive integer A, we define the set [A] {1, 2, . . . , A}
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
