Читать книгу Dynamic Spectrum Access Decisions - George F. Elmasry - Страница 80

This section shows how the generic cognitive engine construct used in the central arbitrator can execute the thread illustrated in Figure 5.3. The importance of this thread is that it is the initialization thread and subsequent threads can be considered a subset of this thread, as indicated by the curved arrow at the right‐hand side of the figure. The curved arrow means that the update to the information repository, the fusion of information, and the monitor of resources will continue to occur as a loop. At any moment, this loop can trigger a decision to propagate a new policy, rule set or configuration parameters or propagate a new frequency assignments. Note that there is no need for a human in the loop. The central arbitrator decisions are autonomous. Configuration parameters can be updated and propagated autonomously.

Figure 5.3 The main thread in the central arbitrator.

Notice with Figure 5.3 that information repository updates can be:

 from external sources to include sensors, external database, and external tools.

 geolocation information updates propagated from lower hierarchy.

 a result of fusion that evolves the states of the DSA cognitive engine.

The decision maker can create a new frequency plan that includes:

 new frequency assignments to some or all networks (change of operational frequencies).

 new backup frequencies for each network (Note that backup frequencies, much like operational frequencies have to be a result of decision fusion so that they are spatially separated and when nodes use them for connectivity, nodes will not suffer from interference due to lack of spatial separation or from external systems in the same geographical location.).

 sensing frequency. (Note that in order to reduce the control traffic volume, the central arbitrator may select a subset of sensing capable nodes per each network. Not all sensors must be activated at all the times. This subset of sensors can be geographically dispersed to create a comprehensive spectrum map for the least amount of spectrum sensing control traffic volume.)