Date Added: Jan 2013
Cognitive Radio Network (CRN) is a promising wireless network since CRN can improve the wireless resource (e.g. spectrum, power etc.) usage efficiency significantly by implementing more flexible wireless resource allocation policy. A novel secondary spectrum usage scheme (i.e. opportunistic spectrum access) is introduced. The SUs in SRN can access the spectrum allocated to PUs originally while the spectrum is not used by any PU. Moreover, the transmission power allocation plays a key role in cognitive radio network protocol designs. The efficient power allocation cannot only improves the network performance (e.g. spectrum efficient, network throughput etc.), but also guarantees the Quality-of-Service (QoS) of PUs.