Dynamic Resource Allocation in OFDM Based Cognitive Radio System Considering Primary and Secondary Users QoS

摘要

In many of the present day wireless systems the total spectrum is not utilized efficiently. This can be overcome by using cognitive radio (CR). Cognitive radio is an artificial intelligent wireless technology, which can allocate the licensed user channels to the unlicensed users without disturbing the licensed users, thereby improving the spectrum efficiency. In this paper we concentrate on multiuser orthogonal frequency division multiplexing (MU-OFDM) CR. In a conventional OFDM system the capacity is maximized using water filling algorithm. In this paper we jointly optimize the power and subcarrier allocation for OFDM based CR system in a multiuser environment. This is performed by modifying the water filling algorithm by using the convex optimization theory. Having implement it, we achieve the maximum error-free capacity under total power constraint and a peak power constraint.