Optimizing Content Caching to Maximize the Density of Successful Receptions in Device-to-Device Networking

Abstract

Device-to-device (D2D) communication is a promising approach to optimize the utilization of air interface resources in 5G networks, since it allows decentralized opportunistic short-range communication. For D2D to be useful, mobile nodes must possess content that other mobiles want. Thus, intelligent caching techniques are essential for D2D. In this paper we use results from stochastic geometry to derive the probability of successful content delivery in the presence of interference and noise. We employ a general transmission strategy where multiple files are cached at the users and different files can be transmitted simultaneously throughout the network. We then formulate an optimization problem, and find the caching distribution that maximizes the density of successful receptions (DSR) under a simple transmission strategy where a single file is transmitted at a time throughout the network. We model file requests by a Zipf distribution with exponent γ r , which results in an optimal caching distribution that is also a Zipf distribution with exponent γ c , which is related to γ r through a simple expression involving the path loss exponent. We solve the optimal content placement problem for more general demand profiles under Rayleigh, Ricean and Nakagami small-scale fading distributions. Our results suggest that it is required to flatten the request distribution to optimize the caching performance. We also develop strategies to optimize content caching for the more general case with multiple files, and bound the DSR for that scenario.Parts of the manuscript were presented at the 2014 IEEE Globecom Workshops [1] and at the 2015 IEEE ICC Workshops [2].

Performance Analysis and Optimization of Cache-Enabled Small Cell Networks

“…Substituting (14) and (15) into (13) and after some manipulations, we can obtain the desired result (7). Note that P s j,SCD pb j q becomes the probability of successful transmission from the serving SBS to the typical user when b j =1 in traditional sub-6 GHz networks without caching.…”

“…where P s cov px, b j q is given by (7), which represents the conditional coverage probability that the received SINR is larger than ϕ s given a typical communication distance x. f |X s j | pxq is the probability density function (PDF) of the distance § § X s j § § between a typical sub-6 GHz UE and its nearest serving…”

“…This strategy is extended to the distributed relay networks with relay clustering in [6] to combat the half-duplex constraint, and it significantly improves the outage performance. Caching distribution in device-to-device (D2D) communication networks is studied in [7] under a simple transmission strategy where a single file is transmitted at a time. Several spatially correlated caching strategies are investigated for D2D networks in [8] in contrast to the baseline independent content placement.…”

The role of caching in next generation cellular networks: A survey and research outlook

“…Other authors [156][157][158][159][160] considered a different perspective of cache enabled networks, where the cache networks were modeled from stochastic geometry perspective with the main aim of characterizing the outage probability in closed form and evaluating the use of cache aided network from a purely physical layer standpoint. Based on benefits established by virtue of a vast and ever-increasing array of recent literature, caching has therefore been identified as one of the keys enables of 5G wireless networks.…”

Individual Preference Aware Caching Policy Design for Energy-Efficient Wireless D2D Communications

“…Not only different design goals, but also different techniques and scenarios were considered for cache-aided D2D. Stochastic geometry was exploited to analyze networks and propose caching policy designs in [20], [21]. Considering MIMO systems, scaling laws of throughput were discussed in [22] and [23].…”