Distributed Base Station Association and Power Control for Heterogeneous Cellular Networks

In this paper, we propose a universal joint base station (BS) association (BSA) and power control (PC) algorithm for heterogeneous cellular networks. Specifically, the proposed algorithm iteratively updates the BSA solution and the transmit power of each user. Here, the new transmit power level is expressed as a function of the power in the previous iteration, and this function is called the power update function (puf). We prove the convergence of this algorithm when the puf of the PC strategy satisfies the so-called "two-sided scalable (2.s.s.) function" property. Then, we develop a novel hybrid PC (HPC) scheme by using noncooperative game theory and prove that its corresponding puf is 2.s.s. Therefore, this HPC scheme can be employed in the proposed joint BSA and PC algorithm. We then devise an adaptation mechanism for the HPC algorithm so that it can support the signal-to-interference-plus-noise ratio (SINR) requirements of all users whenever possible while exploiting multiuser diversity to improve the system throughput. We show that the proposed HPC adaptation algorithm outperforms the well-known Foschini-Miljianic PC algorithm in both feasible and infeasible systems. In addition, we present the application of the developed framework to design a hybrid access scheme for two-tier macrocell-femtocell networks. Numerical results are then presented to illustrate the convergence of the proposed algorithms and their superior performance, compared with existing algorithms in the literature.