Polynomial-time assignment-based cell association with generic utility functions

Cell association is a significant research issue in future mobile communication systems due to the unacceptably large computational time of traditional schemes. This article proposes a polynomial-time cell association scheme which not only completes the association in polynomial time but also fits for a generic optimization objective function. On the one hand, traditional cell association as a non-deterministic polynomial (NP) hard problem with a generic utility function is heuristically transformed into a 2-dimensional assignment optimization and solved by a certain polynomial-time algorithm, which significantly saves computational time. On the other hand, the scheme jointly considers utility maximization and load balancing among multiple base stations (BSs) by maintaining an experience pool storing a set of weighting factor values and their corresponding performances. When an association optimization is required, a suitable weighting factor value is taken from the pool to calculate a long square utility matrix and a certain polynomial-time algorithm will be applied for the association. Comparing with several representative schemes, the proposed scheme achieves large system capacity and high fairness within a relatively short computational time.