  One of the promising technologies for the next generation wireless networks
is the reconfigurable intelligent surfaces (RISs). This technology provides
planar surfaces the capability to manipulate the reflected waves of impinging
signals, which leads to a more controllable wireless environment. One potential
use case of such technology is providing indirect line-of-sight (LoS) links
between mobile users and base stations (BSs) which do not have direct LoS
channels. Objects that act as blockages for the communication links, such as
buildings or trees, can be equipped with RISs to enhance the coverage
probability of the cellular network through providing extra indirect LoS-links.
In this paper, we use tools from stochastic geometry to study the effect of
large-scale deployment of RISs on the performance of cellular networks. In
particular, we model the blockages using the line Boolean model. For this
setup, we study how equipping a subset of the blockages with RISs will enhance
the performance of the cellular network. We first derive the ratio of the
blind-spots to the total area. Next, we derive the probability that a typical
mobile user associates with a BS using an RIS. Finally, we derive the
probability distribution of the path-loss between the typical user and its
associated BS. We draw multiple useful system-level insights from the proposed
analysis. For instance, we show that deployment of RISs highly improves the
coverage regions of the BSs. Furthermore, we show that to ensure that the ratio
of blind-spots to the total area is below 10^5, the required density of RISs
increases from just 6 RISs/km2 when the density of the blockages is 300
blockage/km^2 to 490 RISs/km^2 when the density of the blockages is 700
blockage/km^2.
