Читать книгу Dynamic Spectrum Access Decisions - George F. Elmasry - Страница 11

The coupling of spectrum sensing and dynamic spectrum access (DSA) solely with cognitive radios can do a disservice to the wireless communications community. Long before the concept of cognitive radios was coined, the defense community had elaborate spectrum sensing techniques. Since World War II, the defense community have had signal intelligence (SigInt) capabilities that are decades ahead of the commercial world's sensing capabilities. In today's commercial wireless system, we have the concept of finding the geolocation of a spectrum emitter through using multiple receivers (sensors) that can estimate the geolocation of the emitter and the direction of the emitter's beam. The defense community had this concept implemented in SigInt decades before the commercial world understood it and without having preknowledge of the emitted signal characteristics. SigInt capabilities used spectrum sensors extensively as part of the cat‐and‐mouse game of detecting the enemy's spectrum emission and overcoming the enemy's jammers.

As dynamic spectrum access capabilities are quickly evolving in the commercial wireless arena, one can see now how spectrum sensing leading to dynamic spectrum access ought to be decoupled from building the cognitive capabilities. As this book shows, we can have wireless communications systems that are not necessarily defined as cognitive systems, yet these systems can perform spectrum sensing, can analyze the sensed information and can use a form of dynamic spectrum access. Even with cognitive radios, breaking the problem domain to separate the spectrum sensing aspects from the cognitive capabilities can be helpful. When building communications systems, considering what type of spectrum sensing capabilities to use, how to process spectrum sensing information and how to make dynamic spectrum access decisions separate from designing and building a cognitive engine can be critical to optimizing these systems.

There are multiple goals behind this book from my own experience with commercial and military wireless communications systems. The first goal is to have the reader first focus on spectrum sensing and DSA approaches apart from building a cognitive engine. The second goal is to cover aspects of spectrum sensing without being tied to a specific system. The third goal is to create a reference and senior level or graduate school level textbook for a course in dynamic spectrum access. A course in cognitive radios and cognitive networks for electrical and computer engineering students should focus on the aspects covered in this book. The book considers cognitive engine design secondary to the digital communications aspects of DSA.

The book is divided into four parts. The first two parts can be used as a textbook, with chapters including exercises. The first part represents digital communications theoretical bases and concept descriptions of DSA that can apply to any system. The second part includes some case studies for designing DSA capabilities as a set of cloud services. The second part does not cover every possible application that can use DSA, but these examples should be eye‐opening for any engineer who is looking to design DSA capable systems. The third part of the book includes the public domain publication of the US Army Techniques for Spectrum Management Operation, which provides excellent information on the US Army doctrine for spectrum management. The reader can see the involvement of the military domain use of DSA and see the challenges facing military applications of DSA. The fourth part is the established DySPAN standardization, also known as the IEEE P1900.

George F. Elmasry