Fog-Aided Wireless Networks for Content Delivery: Fundamental Latency Trade-Offs

Abstract

A fog-aided wireless network architecture is studied in which edge-nodes (ENs), such as base stations, are connected to a cloud processor via dedicated fronthaul links, while also being endowed with caches. Cloud processing enables the centralized implementation of cooperative transmission strategies at the ENs, albeit at the cost of an increased latency due to fronthaul transfer. In contrast, the proactive caching of popular content at the ENs allows for the low-latency delivery of the cached files, but with generally limited opportunities for cooperative transmission among the ENs. The interplay between cloud processing and edge caching is addressed from an information-theoretic viewpoint by investigating the fundamental limits of a high Signal-to-Noise-Ratio (SNR) metric, termed normalized delivery time (NDT), which captures the worst-case coding latency for delivering any requested content to the users. The NDT is defined under the assumptions of either serial or pipelined fronthaul-edge transmission, and is studied as a function of fronthaul and cache capacity constraints. Placement and delivery strategies across both fronthaul and wireless, or edge, segments are proposed with the aim of minimizing the NDT. Information-theoretic lower bounds on the NDT are also derived. Achievability arguments and lower bounds are leveraged to characterize the minimal NDT in a number of important special cases, including systems with no caching capabilities, as well as to prove that the proposed schemes achieve optimality within a constant multiplicative factor of 2 for all values of the problem parameters.

References in corpus (4)

• Content-Centric Sparse Multicast Beamforming for Cache-Enabled Cloud RAN
• Placing Dynamic Content in Caches with Small Population
• Fundamental Tradeoff between Storage and Latency in Cache-Aided Wireless Interference Networks
• Critical Database Size for Effective Caching

Cited by in corpus (10)

• Ultra-Low Latency (ULL) Networks: The IEEE TSN and IETF DetNet Standards and Related 5G ULL Research
• Fundamental Structure of Optimal Cache Placement for Coded Caching with Nonuniform Demands
• Memory-Rate Tradeoff for Caching with Uncoded Placement under Nonuniform Random Demands
• Online Reinforcement Learning of X-Haul Content Delivery Mode in Fog Radio Access Networks
• Decentralized Caching under Nonuniform File Popularity and Size: Memory-Rate Tradeoff Characterization
• Topological Content Delivery with Feedback and Random Receiver Cache
• Signal-Aligned Network Coding in K-User MIMO Interference Channels with Limited Receiver Cooperation
• Information-Theoretic Analysis of D2D-Aided Pipelined Content Delivery in Fog-RAN
• A New Class of Structured Beamforming for Content-Centric Fog Radio Access Networks
• Blind Interference Alignment for MapReduce: Exploiting Side-information with Reconfigurable Antennas