## 2 Indoor Scenario Simulation and Characterization
Based on the simulation results obtained by means of the 3D ray launching method, it is possible to estimate the increase of current consumption of the transmitter as a function of the receiver location. In order to obtain the current estimation, a specific calculation module within the 3D Ray Launching algorithm has been implemented, considering conventional transceiver current consumption values as a function of their modes of operation, enabling the possibility of depicting current consumption graphs within the simulation scenario. Figure 12 shows the current consumption increase map for the case of antenna 3 transmitting. The map represents the increase of current consumption of the transmitting device placed at antenna 3 point, for each possible receiver location within the scenario. As can be seen in Figure 12, the estimated energy consumption increase varies from 0.018 mA to 1.78 mA, depending on the placement of the receiver mote. As expected, if a receiver is placed at the left zone of the scenario, the consumption for the transmitter at antenna 3 point will has a great increase comparing to the rest of the scenario, due to the low power levels received in that area because the existence of a plumb wall. Figure 4:1 Delay spread when antenna 3 is transmitting for the plane at 1 m height. Finally, current consumption maps in all over the scenario for previously presented three different configurations are shown in Figure 4:2 As expected the energy consumption when eight antennas are emitting is considerably lower than in other cases and the difference in consumption level is also noticeable when three or four antennas are utilized. Figure 4:3 Estimation of Energy consumption for the antenna 3 in terms of current values in mA for different receiver locations within the scenario at height 1 m.  
Figure 4:4 Current consumption in all over the scenario for the cases of three (**a**); four (**b**) and eight (**c**) emitters. Therefore, the optimum situation of the antennas is based on three premises, a constant distribution of power distribution all over the scenario, an appropriate SNR level and a low consumption. The reception of a high level of power in all points of the scenario provides not only a good user experience, but also decreases the current consumption of the devices and therefore the introduction of as many devices as possible may seem like a good idea. However, a higher number of antennas implies more inter-system interferences with the consequent degradation of SNR. Thus, a good balance between coverage and capacity, by means of deterministic system modelling (which considers network topology impact), is found with the aim of implementing an optimum communication system. The use of the 3D Ray Launching algorithm combined with the current estimation function aids in the optimal node location, which is achieved as a combination of the number of active transmitters, total number of users and external interference sources considered in the scenario. Due to the large variability in the possible combinations of the previous factors, the design procedure is site-specific, although as a general comment, the initial estimation of current consumption plots provides the initial location of the transceivers to be deployed, taking also into account capacity requirements, which will provide the total amount of required nodes.