Читать книгу Dynamic Spectrum Access Decisions - George F. Elmasry - Страница 18

As the old saying goes “there is no free lunch”. With DSA, the amount of control traffic could increase. In order to create distributed and centralized aspects of DSA, spectrum sensing information has to flow from sensor nodes to other sensor nodes or to the centralized arbitrator. Negotiation between distributed agents could use control plane bandwidth as well. Configuring sensing nodes on what frequency bands to sense will also require messaging over the air. The tradeoff between the increase in control traffic and the gain obtained from DSA optimizing the available spectrum resources must be quantified. In a network that operates on a narrowband of frequency, which results in a low bit per second transmission rate, the amount of control traffic increase may render the gain from DSA techniques worthless to this network. In a heterogeneous set of networks, such a low bandwidth network may be allocated a fixed frequency and the global DSA design may have to work around this fixed frequency assignment when optimizing spectrum resources for the rest of the heterogeneous networks.

Even when we are certain that DSA gain exceeds the impact of DSA control traffic, DSA design has to find ways to reduce the impact of DSA control traffic through techniques that do some local processing (fusion) of spectrum sensing information and abstract them before sending them OTA such that we do not compromise spectrum sensing information relevance while we minimize the use of OTA resources for DSA control traffic.