Читать книгу Dynamic Spectrum Access Decisions - George F. Elmasry - Страница 65

The previous chapter covered the ROC model and emphasized two distinct DSA ROC models. The simplest ROC model covered the cases similar to that of a secondary user hypothesizing the presence or absence of a primary user's signal in order to use a spectrum band opportunistically.¹ The second ROC model covered the same‐channel in‐band spectrum sensing which hypothesizes if the signal used for communications is suffering from interference by another signal or not. The previous chapter also showed how local decision fusion can add other dimensions to the spectrum sensing hypotheses such as the spatial dimension. The previous chapter also introduced some of the decisions that can be made locally and some of the decisions that can be made in a distributed cooperative or centralized manner.

As alluded to in the previous chapter, the DSA design may not stop at the local decision fusion and the solution may rely on cooperative distributed decision fusion or the use of a centralized spectrum arbitrator. Decision fusion can be made locally, in a distributed way and/or in a centralized arbitrator. This chapter covers the DSA design approaches that need to be thought of in cognitive networks, taking into consideration a variety of reasons to include the optimization of control traffic volume, the speed of making DSA decisions, the interdependency between DSA decisions and other cognitive networking processes, and the need for the different hierarchies of DSA decisions to work in harmony.

To make the best case for using a hybrid DSA design, this chapter uses examples from military communications systems where spectrum access needs to be more dynamic and the networks are heterogeneous and hierarchical. This book makes the case for considering hybrid DSA design in most applications. The second part of the book emphasizes approaches that can be common between different applications and areas where the DSA design approach may differ. In the second part of the book, Chapter 5 emphasizes the concept of developing DSA capabilities as a set of cloud services available at the different network hierarchical entities, which further emphasizes the hybrid DSA design consideration. Chapter 6 focuses on dynamic spectrum management for commercial cellular 5G systems. The cellular 5G dynamic spectrum management design is also a hybrid approach. Chapter 8 covers the inclusion of co‐site interference mitigation as a subset of DSA cloud services, which also emphasizes the need for hybrid DSA design approaches.