Date Added: Oct 2010
In Cognitive Radio (CR) system, the spectrum band licensed to the Primary Link (PL) is usually divided into multiple sub-channels. Traditionally, the Secondary Link (SL) accesses the primary spectrum by either opportunistically selecting the idle sub-channels, called Opportunistic Spectrum Access (OSA), or coexisting with the PL in the same band, called Spectrum Sharing (SS). In this paper, the authors propose a Hybrid Opportunistic Spectrum Access (H-OSA) scheme, in which the SL has the opportunity to access all the sub-channels based on the activity and interference threshold of the PL. Based on the lagrange dual-decomposition theory, the optimal power solution on each sub-channel is derived to maximize the ergodic capacity of the SL.