  We investigate the performance of a two-hop cognitive relay network with a
buffered decode and forward (DF) relay. We derive expressions for the rate
performance of an adaptive link selection-based buffered relay (ALSBR) scheme
with peak power and peak interference constraints on the secondary nodes, and
compare its performance with that of conventional unbuffered relay (CUBR) and
conventional buffered relay (CBR) schemes. Use of buffered relays with adaptive
link selection is shown to be particularly advantageous in underlay cognitive
radio networks. The insights developed are of significance to system designers
since cognitive radio frameworks are being explored for use in 5G systems.
Computer simulation results are presented to demonstrate accuracy of the
derived expressions.
