User association in small cell heterogeneous network with downlink sum rate

This paper is concerned with the optimal association of user equipments (UEs) to the base stations, which are either a macro base station or pico base stations, for the sum rate utility in a cooperative heterogeneous network (HetNet). This is a nonconvex combinatorial problem. By recasting the problem as a d.c (difference of convex (d.c.)) program, the optimal association solution is sought by d.c iterations (DCI), each of which solves a simple convex quadratic problem over a convex set. Numerical simulation shows the efficiency of the proposed procedure in term of performance and computational time.