Joint optimization of detection thresholds and power allocation in OFDM based cognitive femtocell networks

Spectrum sensing in cognitive femtocells play an important role in detecting spectrum holes and to opportunistically use under-utilized frequency bands without causing harmful interference to macrocell users. In case of mass deployment of femtocells, interference management is essential to maximize the capacity and achievable data rates. In this paper, a novel algorithm is proposed, based on Lagrangian dual decomposition technique, for jointly optimizing the detection threshold and power allocation to maximize the total aggregated opportunistic throughput per unit bandwidth of a co-channel OFDM based femtocell network, densely deployed over a macrocell architecture, under a constraint of the total interference generated towards macrocell users. Simulation results show that the proposed algorithm is stable, attains convergence and achieves considerable rate gain.