Performance of selection schemes in a symbiotic dynamic spectrum access system

In this paper, we analyze the outage performance of secondary selection schemes in a symbiotic dynamic spectrum access (DSA) system. In this system, one opportunistically selected secondary node relays the primary signal for boosting the signal-to-noise-ratio (SNR) at the primary receiver, so as to raise the peak interference tolerance limit (ITL) of the primary receiver. This enables the secondary base station to simultaneously communicate to another opportunistically selected secondary node. Assuming peak secondary transmit power and peak interference constraints, we derive the exact and asymptotic outage probability of secondary system in such a framework for simple selection schemes. While availability of a large number of nodes for selection improves performance, the exact proportion of nodes that should serve as primary relay candidates to minimize outage performance is a strong function of the SNR.