Scalability aspects of ultra-dense networks with limited possibilities to place access points

Network densification appears to be a scalable means to address increasing traffic demands. Indeed, network densification can, at least theoretically, infinitely 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 their placement possibilities are limited. In this paper, we quantitatively evaluate this scalability issue for a very densely populated pedestrian street use case where access points cannot be placed anywhere on the street itself, but only on walls delimiting the street. By means of simulation, 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.