Also on demand schemas can be supported, providing the system with rich flexible capabilities to serve dynamically traffic needs.
Each link gets the right to use a channel marked as high priority. In addition the Spectrum allocation system can allocate a second channel with a lower priority.
The spectrum allocation system is aware of the reception signal quality for all the links in a region, and it can detect interferences if they occur. When the spectrum allocation system detects signal interference in a link on its priority channel, the system automatically requests the other links that previously got permission to use this channel as lower priority link to cease using it. This way the link which has the priority over this channel can use it without any degradation.
Simulation analysis results of these techniques for urban scenarios [21] have shown that it is feasible to use half of the spectrum with respect to regular planning methods, reducing from 24 channels of 7 MHz to just 12 with spectrum sharing. SDN-based control can provide such a relevant efficiency in an automated and dynamic way.
The effectiveness of the solution proposed above can be validated by the following measurement. We still consider the scenario presented in Fig. 2. We consider in our experiment two possible antennas namely 1 and 2 ft antenna transmitting and receiving at 18 GHz. In Figs. 5 and 6 we display the radiation pattern of 1 and 2 ft antenna respectively. In these figures we show the measured radiation decrease relatively to the maximum signal received when the receiver is located at a given azimuth degrees (varying on the X axis) from the main lobe of the transmitter. Obviously the reception is maximal when the angle between the direction of the lobe of the transmitter and the receiver is 0