Pilot Power Minimization in HSDPA Femtocells

In UMTS cellular networks, Common Pilot Channel (CPICH) signals are broadcast by base stations for channel estimation and cell selection. The strength of CPICH signal determines cell coverage and pilot pollution to neighboring cells; pilot power allocation thus involves a tradeoff between coverage and interference. In this paper, we study the issue of pilot power management in closed-access High-Speed Downlink Packet Access (HSDPA) femtocell network. We minimize the total pilot power in a HSDPA femtocell network subject to instantaneous coverage requirements. We formulate a generalized optimization problem in a femtocell network and propose a suboptimal analytic solution to pilot power allocation implemented in each femtocell. Simulation results show that the proposed algorithm outperforms fixed pilot power schemes in terms of much lower allocated pilot power and interference to macro user equipments.