Throughput and Delay Scaling of Content-Centric Ad Hoc and Heterogeneous Wireless Networks

TL;DR

This paper analyzes the throughput and delay scaling laws in content-centric wireless networks, proposing caching schemes and extending results to heterogeneous networks with base stations, highlighting conditions for optimal performance.

Contribution

It introduces an order-optimal caching and transmission scheme for content-centric wireless networks and extends analysis to heterogeneous networks with base stations.

Findings

Throughput and delay are order-optimal within a class of schemes.

Optimal performance depends on content popularity distribution and network heterogeneity.

Heterogeneous networks outperform homogeneous ones only under certain conditions.

Abstract

We study the throughput and delay characteristics of wireless caching networks, where users are mainly interested in retrieving content stored in the network, rather than in maintaining source-destination communication. Nodes are assumed to be uniformly distributed in the network area. Each node has a limited-capacity content store, which it uses to cache contents. We propose an achievable caching and transmission scheme whereby requesters retrieve content from the caching point which is closest in Euclidean distance. We establish the throughput and delay scaling of the achievable scheme, and show that the throughput and delay performance are order-optimal within a class of schemes. We then solve the caching optimization problem, and evaluate the network performance for a Zipf content popularity distribution, letting the number of content types and the network size both go to infinity. Finally, we extend our analysis to heterogeneous wireless networks where, in addition to wireless nodes, there are a number of base stations uniformly distributed at random in the network area. We show that in order to achieve a better performance in a heterogeneous network in the order sense, the number of base stations needs to be greater than the ratio of the number of nodes to the number of content types. Furthermore, we show that the heterogeneous network does not yield performance advantages in the order sense if the Zipf content popularity distribution exponent exceeds 3/2.