The major part of the data traffic takes place indoors and this trend is expected to accelerate in the near future, . Therefore, one of the main goals of new-coming wireless networks such as the LTE and LTE-A is to extend the indoor coverage of wireless broadband services. The design strategy of a wireless system is dictated by, among other factors, the limitations posed by the physical propagation environment. For example, the interference levels entering the link budgets that define the maximum data rates and coverage areas must be based on accurate propagation computations. The latter can also be used for planning location-based services requiring an accurate prediction of the user's position based on received signal strengths. Furthermore, in spite of advances in computing technology, the propagation predictions are usually rather time-consuming. Hence, producing accurate yet reasonably fast propagation models still remains at the core of wireless network planning and optimization. This is further accentuated by the introduction of Multiple Input Multiple Output (MIMO) technologies that employ multiple antennas at both the transmit and the receive sides of the wireless communication link.
It is well-known that building structures have an attenuating impact ...