Chapter 6Introduction to Software Radio1
Although a certain number of authors affirm that cognitive radio (CR) is totally independent of the software radio (SR), the same affirmation is also found in the Federal Communications Commission (FCC) rulemaking [FCC 05]; it seems to us that the SR, in whatever form (ideal or software defined), is the technology that will provide greatest flexibility, necessary in CR. That is why we describe, in this section, the SR as support technology. It is clear that the more the technology will be ideal, the more the CR will be supported effectively. However, even with software-defined radio (SDR), it will be possible to offer a CR with limited features.
The outburst in sales of mobile phones and increase in the volume of data transmission (particularly on the Internet) show that not only the users but also the operators have growing needs for anywhere, anytime communications. A significant geographic mobility leads to strict constraints on the terminals (see Figure 6.1). The terminals, based on their localization, must be able to connect to networks having different standards. It seems easier for a fixed terminal (because we can take its time to reconfigure it); however, mobility engendering a network change must be realized by avoiding any communication breaks for the user (handover). The SR is directly related to the evolution of wireless mobile telecommunications. Indeed, the idea of a terminal that can transmit any type ...