1. Introduction
With the growing popularity of the bandwidth-hungry services as high definition
video streaming or gaming, the user requirements to the telecommunication networks
are becoming more demanding. These requirements result in the need of network
upgrades, for example migrations from copper to fiber for the fixed networks or 2G-
3G-4G-5G upgrades for mobile networks, and thus imply higher costs for an NP. In
order for the NP to stay profitable, there are two potential ways: increase the Average
Revenue Per User (ARPU) and/or decrease the Total Cost of Ownership (TCO) of the
network.
Traditionally, the fixed access network market was characterized by no or limited
competition, e.g., there was a single national telephone company providing the con-
nectivity and the service. The increase in the ARPU was easily achieved through the
increase of the respective user tariffs. With the market development and appearance
of competitors (supported by the regulators to avoid monopoly), the increasing of
the ARPU by a single NP is not possible anymore as the customers can switch to a
cheaper NP alternative. Hence, the revenues of the traditional NPs are not increasing
at best [14]. On the other hand, the costs of the network maintenance and upgrade are
growing due to the increasing network complexity. To be able to decrease the overall
network costs or the TCO, an NP has to understand and analyze its components. The
network TCO or costs of the network implementation, upgrade and operation are di-
vided into Capital Expenditures (CapEx) and Operational Expenditures (OpEx) [15].
