An overlay architecture for cognitive radio systems

In this paper, we examine joint optimization of the transmitter/receiver pulse shaping filter of an overlay cognitive wireless system that allows both the overlay (new) and the legacy (existing) users to share the spectrum at the same time without the need of sensing the spectrum. The composite sum of the mean-squared error (MSE) of the overlay system and the excess MSE in the legacy system due to the presence of the overlay system is used as figure of merit. The effect of varying the overlay transmitter power along with the amount of overlap between the overlay and the legacy users are investigated.