Multiobjective Subchannel and Power Allocation in Interference-Limited Two-Tier OFDMA Femtocell Networks

The cochannel deployment of femtocells in a macrocell network is a cost-effective and efficient way to increase network coverage and capacity. However, such deployment is exigent due to the presence of inter- and intratier interference and the ad hoc operation of femtocells. Motivated by the flexible subchannel allocation capability of orthogonal frequency-division multiple access, in this paper, we consider the problem of joint subchannel and power allocation in both the uplink and downlink of a two-tier orthogonal-frequency-division-multiplexing-based femtocell network. It is a multiobjective optimization problem that aims to maximize the throughput of all users, simultaneously increasing the power efficiency of femtocell base stations. Interference to macrocell users is kept below a certain tolerable threshold. The minimum-rate requirements of delay-sensitive users are also taken into consideration. The problem is solved using nondominated sorting genetic algorithm version II, and the results are compared with the existing solution.