Joint User Association and eICIC for Max–Min Fairness in HetNets

In heterogeneous networks, an enhanced intercell interference coordination (eICIC) via almost blank subframes (ABS) is introduced to reduce the interference from macrocells to the users locating at the edge of small cells. In this letter, we formulate the user association and ABS ratio issues jointly as a network-wide max–min fairness optimization problem which turns out to be NP-hard. To overcome this difficulty, the problem is decomposed into two subproblems. First, we solve the optimal ABS ratio problem for given user association and second, maximize network utility through user association. Further, a low-complexity greedy algorithm is proposed based on the marginal utility. The effectiveness of our algorithm is corroborated by the results from numerical evaluation.