Most of the existing DSA schemes are the unlicensed user, traffic in a licensed spectrum without compromising the transmissions of the licensed users, in which all the unlicensed users are typically treated equally. Dynamic Spectrum Access (DSA) is an important design aspect for the cognitive radio networks. Specifically, the unlicensed user traffic is divided into two priority classes (i.e., high and low priority). The DSA scheme should perform spectrum handoff to protect the licensed user's transmission. Different DSA schemes (i.e., centralized and distributed) are considered to manage the prioritized unlicensed user traffic.