# Capacity Scaling of Cellular Networks: Impact of Bandwidth, Infrastructure Density and Number of Antennas

## TL;DR

This paper analyzes how cellular network capacity scales with bandwidth, infrastructure density, and antennas, revealing a fundamental bandwidth limit and highlighting the importance of multi-hop protocols for future ultra dense networks.

## Contribution

It establishes the capacity scaling laws of large cellular networks and demonstrates the effectiveness of multi-hop protocols over single-hop in wideband regimes.

## Key findings

- Network capacity has a fundamental bandwidth limit.
- Multi-hop protocols achieve optimal capacity scaling.
- Single-hop protocols are insufficient in wideband regimes.

## Abstract

The availability of very wide spectrum in millimeter wave bands combined with large antenna arrays and ultra dense networks raises two basic questions: What is the true value of overly abundant degrees of freedom and how can networks be designed to fully exploit them? This paper determines the capacity scaling of large cellular networks as a function of bandwidth, area, number of antennas and base station density. It is found that the network capacity has a fundamental bandwidth scaling limit, beyond which the network becomes power-limited. An infrastructure multi-hop protocol achieves the optimal network capacity scaling for all network parameters. In contrast, current protocols that use only single-hop direct transmissions can not achieve the capacity scaling in wideband regimes except in the special case when the density of base stations is taken to impractical extremes. This finding suggests that multi-hop communication will be important to fully realize the potential of next-generation cellular networks. Dedicated relays, if sufficiently dense, can also perform this task, relieving user nodes from the battery drain of cooperation. On the other hand, more sophisticated strategies such as hierarchical cooperation, that are essential for achieving capacity scaling in ad hoc networks, are unnecessary in the cellular context.