Abstract
Multimedia content delivery via the cellular infrastructure increases fast due to the very high volumes of mobile video traffic generated by the billions of end devices populating the mobile data network. A critical mass of mobile video content requests refers to the consumption of the same popular video content, which is consumed by different end terminals spanning small geographical regions. Such content requests place a great burden on the backhaul of content-agnostic cellular networks, which fail to exploit the correlation of video requests to decongest their backhaul links. This creates redundant retransmissions while fetching the same video content from a central server to the network edge, using the bandwidth-limited backhaul at peak-time periods. With the integration of multi-access edge computing (MEC) capabilities in 5G mobile cellular networks, mobile network operators can place popular video content closer to the network edge at off-peak time periods, predicting user requests exhibiting a high correlation for a given time interval over smaller geographical regions. In this paper, we investigate popular content placement in multi-tier heterogeneous cellular networks where the edge network infrastructure can cooperate to create content delivery (and placement) clusters to effectively serve correlated video requests. To this end, we model the cooperative content placement problem using the multiple knapsack problem (MKP) formulation and present an exact (optimal) bound-and-bound strategy to solve it. The performance of the proposed strategy is evaluated in-depth using extensive system-level simulations and is compared against that of other state-of-the-art algorithms. Valuable design guidelines and key performance trade-offs are discussed, paving the way towards cluster-based cooperative caching in MEC-enabled cellular network setups.
Highlights
The emergence of new technologies, such as the Internet of things (IoT), machine to machine communications (M2M), e-health, and vehicular communications has pushed the cellular traffic much higher than anticipated [1]
Different from the vast majority of existing approaches, which typically formulate the problem of network-wide content placement given a content popularity distribution, in this work we focus on the emerging scenario where the mobile network operator (MNO) can assign the heterogeneous edge network nodes of the heterogeneous cellular networks (HCN) to multi-access edge computing (MEC) clusters of different sizes and capabilities, e.g. different number of infrastructure nodes per MEC cluster, different mixture of MEC node types and cache sizes
The greedy strategy orders video files of M in descending order based on their popularity and places them in the cache of mobile helpers (MHs) sequentially without repetition, i.e. the cache of the first MH is filled by skipping files that cannot fit, the cache of the second MH is filled with the remaining files, etc., until no other file can fit into the cache of any MH
Summary
The emergence of new technologies, such as the Internet of things (IoT), machine to machine communications (M2M), e-health, and vehicular communications has pushed the cellular traffic much higher than anticipated [1]. Popular video segments are redundantly re-transmitted from the central content server (residing in the far Internet) to the end user equipment (UE) (residing at the network edge) creating unnecessary utilization of intermediate network resources, especially in heterogeneous cellular networks (HCN) with multiple network tiers and high deployment density [3]. This problem will be further exacerbated in the fifth generation (5G) of mobile cellular networks, where low latency requirements of less than 1ms are targeted for specific service types co-utilizing the wireless medium [4].
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