Abstract
The fifth generation cellular networks are required to provide very fast and reliable communications while dealing with the increase of users traffic. In heterogeneous networks (HetNets) assisted with device-to-device (D2D) communications, traffic can be offloaded to small base stations or to users to make content delivery faster and alleviate the traffic burden from the core network. In this paper, we aim to maximize the probability of successfully delivering files to users, referred to as the successful delivery probability, by jointly optimizing the caching placement and channel allocation in cache-enabled D2D-assisted HetNets. First, an analytical expression of the average content delivery delay is derived. The latter is subsequently used to formulate the joint optimization problem of cache placement and channel allocation. Due to the problem’s non-convexity, a linearization transformation is proposed, which allows to find the optimal solution. However, given the high complexity of the problem, we propose a low-complex heuristic approach for channel allocation and caching. Numerical results illustrate the efficacy of the proposed solutions and compare them to the conventional HetNet. Finally, the impact of several key parameters, e.g., transmit power, caching capacity, and QoS requirements, is investigated, which provides design guidelines for D2D-assisted HetNets.
Highlights
W ITH the fast growth of new heavy mobile applications such as live streaming, language processing, and augmented reality, future wireless networks are required to focus on communication and connectivity, and on high caching in order to satisfy stringent application demands [1].The proposal of heterogeneous networks (HetNets) using small cells and different radio technologies improves the energy efficiency (EE) and spectral efficiency (SE) performances [2]
We investigated in [37] the caching placement problem in a D2D-assisted HetNet, where we successfully derived the optimal solution that minimizes the average content delivery delay
In an attempt to overcome these shortcomings, we propose in this paper to investigate a multi-tier D2D-assisted HetNet, taking into account caching at all tiers, interference among simultaneous transmissions, and accounting for the effect of fast varying channels on content delivery delay
Summary
W ITH the fast growth of new heavy mobile applications such as live streaming, language processing, and augmented reality, future wireless networks are required to focus on communication and connectivity, and on high caching in order to satisfy stringent application demands [1]. Authors of [25] proposed a caching policy for millimeter-wave (mmWave) D2D-based cellular networks, where content is strategically disseminated and exchanged among D2D users for maximized offloading gain, while Amer et al designed in [26] a D2D caching framework with inter-cluster cooperation, where nodes of the same cluster cooperate through D2D communications, while nodes of different clusters exchange data through cellular transmissions. In [28], Zhang et al studied user preference and transmission coverage region aware D2D caching deployment methods, which aimed to maximize a cache utility function, while in [29], the authors investigated multi-winner auction based cache placement in order to minimize the traffic load and average content access delay of D2D-assisted cellular networks.
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