Abstract
This work explores beam forming and two-way relaying to alleviate the dual issues of the spectrum congestion and spectrum under-utilization. These problems can be alleviated by the implementation of underlay cognitive radio networks. However, their reliability, capacity or power, and coverage depend on bi-directional or abbreviated as primary-to-secondary (P2S) and secondary-to-primary (S2P) interference constraints. This work makes of two-way relaying to improve these essential and paramount efficiencies, performance and effectiveness measures.