Spectrum Sharing Between Cellular and Mobile Ad Hoc Networks: Transmission-Capacity Trade-Off

TL;DR

This paper analyzes the capacity trade-offs in spectrum sharing between cellular uplink and mobile ad hoc networks using stochastic geometry, showing that spectrum overlay is more efficient and SIC enhances capacities.

Contribution

It introduces a stochastic geometry-based analysis of spectrum sharing methods, quantifies the capacity trade-offs, and demonstrates the benefits of spectrum overlay and successive interference cancellation.

Findings

Spectrum overlay outperforms spectrum underlay in efficiency.

SIC increases transmission capacities linearly based on interference thresholds.

The capacity trade-off can be represented by a linear equation depending on network parameters.

Abstract

Spectrum sharing between wireless networks improves the efficiency of spectrum usage, and thereby alleviates spectrum scarcity due to growing demands for wireless broadband access. To improve the usual underutilization of the cellular uplink spectrum, this paper studies spectrum sharing between a cellular uplink and a mobile ad hoc networks. These networks access either all frequency sub-channels or their disjoint sub-sets, called spectrum underlay and spectrum overlay, respectively. Given these spectrum sharing methods, the capacity trade-off between the coexisting networks is analyzed based on the transmission capacity of a network with Poisson distributed transmitters. This metric is defined as the maximum density of transmitters subject to an outage constraint for a given signal-to-interference ratio (SIR). Using tools from stochastic geometry, the transmission-capacity trade-off between the coexisting networks is analyzed, where both spectrum overlay and underlay as well as successive interference cancelation (SIC) are considered. In particular, for small target outage probability, the transmission capacities of the coexisting networks are proved to satisfy a linear equation, whose coefficients depend on the spectrum sharing method and whether SIC is applied. This linear equation shows that spectrum overlay is more efficient than spectrum underlay. Furthermore, this result also provides insight into the effects of different network parameters on transmission capacities, including link diversity gains, transmission distances, and the base station density. In particular, SIC is shown to increase transmission capacities of both coexisting networks by a linear factor, which depends on the interference-power threshold for qualifying canceled interferers.