Power control under QoS and interference constraint in Femtocell cognitive networks

Power control is critical for femtocell networks that allow spectrum sharing among Macrocell and Femtocell. In this paper, we derive an optimal power control strategy toward reducing the CO₂ emissions and maximize total throughput under both the probability of dropping a packet due to buffer overflow constraints at the Femtocell user equipment (FUE) and the interference constraints to the Macrocell base station (MBS) for uplink transmission. We use linear programming to solve the CO₂ emissions minimization problem. For maximizing the total throughput of FUEs, we propose a distributed power control algorithms by employing geometry convex tool. Numerical results are used to validate the analysis and demonstrate a high degree of accuracy for the derived expressions. Results indicate that the performance of the FUEs depends on not only the interference constraint of the MBS but also the delay constraint of the FUEs.