Cognitive Networks: Towards Self-Aware Networks

13.2. Spectrum Pooling Concept

The notion of spectrum pooling was first introduced in ^[]. In this resource-sharing strategy called spectrum pooling the primary user would get the highest priority. Once a primary user appears in a frequency band all secondary users transmitting in this band would have to leave immediately, giving priority to the primary user.

A cognitive radio-based spectrum pooling concept has been developed in ^[]. A COg-nitive Radio approach for Usage of Virtual Unlicensed Spectrum (CORVUS), a vision of a cognitive radio-based approach that uses allocated spectrum in a opportunistic manner to create virtual unlicensed bands, i.e. bands that are shared with primary users on a non-interfering basis, has been proposed in ^[]. The principles of the CORVUS system are explained below.

13.2.1. CORVUS System

The basic assumptions of the CORVUS system are as follows

• There is plenty of spectrum available for sharing by secondary users.

• Secondary users are capable of using cognitive radio techniques to avoid interfering with primary users if present.

In this system, the SUs have to keep monitoring the presence of PUs at regular intervals and as soon as a PU is found using its spectrum band, the SU must vacate that particular band and try to relocate to some other band.

The principal idea of the spectrum pooling concept in CORVUS is depicted in Figure 13.2. This system covers a certain bandwidth W. Within this spectral range, several PUs legally own different parts of the ...