Scalability study of ultra-dense networks with access point placement restrictions

Network densification appears to be a scalable means of addressing increasing traffic demands. Indeed, network densification can, at least theoretically, logarithmically increase the delivered traffic in a given area when assuming that access points can be placed arbitrarily close to the users. In practice, however, access points cannot be placed arbitrarily close to the users because of geographical constraints. In this paper, we quantitatively evaluate this scalability issue in a very densely populated pedestrian street where access points cannot be placed anywhere on the street itself, but only on walls abutting the street. By means of simulations, we obtain the optimal number of access points for a maximum average user throughput and show how this number is affected by user distribution, street width, and beamwidth of the antenna.