Читать книгу Dynamic Spectrum Access Decisions - George F. Elmasry - Страница 97

1 1 An entity is a network node, a gateway or the central arbitrator, as explained later in this chapter.

2 2 Most of the spectrum access systems (SASs) developed for the citizens broadband radio service (CBRS) in the USA, which operate around the 3.5 GHz band, offer DSA as a set of cloud services. CBRS allows enterprises to build their own LTE networks and share the band with the LTE cellular infrastructure.

3 3 Interference detection can be an outcome of decision fusion. As explained earlier, hypothesizing interference by a sensor at any time instant does not necessarily lead to interference detection. Fusion of many hypotheses that may come from different sensing sources is what produces a decision that interference is above a certain threshold, which requires new frequency assignment.

4 4 In military communications, all lower echelon networks are wireless MANETs. These wireless networks can be lower tier waveforms with small spectrum footprint and upper tier networks with large spectrum footprint.

5 5 The correct term to use here is frequency band not frequency. A frequency band is defined by a central frequency and bandwidth. The term frequency is used throughout this book loosely to mean a frequency band a network is operated with in order to differentiate an operational frequency band used by a network from the known defined frequency bands such as the HF band, the VHF band, and the UHF band.

6 6 Many decision fusion techniques use heuristic algorithms because reaching an optimum solution for a large number of networks and a large number of nodes within each network can be too computationally extensive to produce timely DSA services. Reducing the order of computational complexity is beyond the scope of this book.

7 7 Notice that considering control traffic volume impact is not simple or straightforward. A DSA design approach can add more control traffic but in the meantime makes the use of spectrum resources much more efficient. Such design is better than lowering the control traffic volume at the expense of reducing the efficiency of spectrum resources use. Although one can use a metric to measure control traffic, this metric's impact comes secondary to the metrics that measure throughput efficiency.

8 8 Chapter 8 explains how co‐site interference avoidance can be another DSA cloud service.