Rethinking Dense Cells for Integrated Sensing and Communications: A Stochastic Geometric View

The inclusion of the sensing functionality in the coming generations of cellular networks, necessitates a rethink of dense cell deployments. In this paper, we analyze and optimize dense cell topologies for dual-functional radar-communication (DFRC) cellular networks. With the aid of tools from stochastic geometry, we derive new analytical expressions of the potential spectral efficiencies in (bit/sec/m^{2}) of radar and communication systems. Based on the new formulations of the potential spectral efficiencies, the energy efficiency (bit/Joule) of DFRC systems is provided in a tractable closed-form formula. Then, an optimization problem to obtain the optimal base station (BS) density that maximizes the network-level energy efficiency is formulated and investigated. In this regard, the mathematical expression of the energy efficiency is shown to be a uni-modal and concave function in the density of the BSs. Therefore, optimal density of the BSs that maximizes the energy efficiency can be obtained. Our analytical and numerical results demonstrate that the inclusion of the sensing functionality clearly differentiates the optimal BS topologies for the DFRC systems against classical communication-only systems.