Hybrid Opportunistic Spectrum Access and Power Allocation for Secondary Link Communication
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.