Resource allocation for the downlink of OFDMA cellular networks and optimization of the reuse factor

In this paper, we investigate the issue of power control and sub-carrier assignment in a downlink OFDMA system. We assume that a certain part of the available bandwidth is likely to be reused by the different base stations (and is thus subject to multicell interference) and that the other part of the bandwidth is shared in an orthogonal way between them (and is thus protected from multicell interference). Although this problem of multicell resource allocation is non-convex, we provide, in the limit of large number of users, the general form of its global solution. As a byproduct, we characterize the optimal value of the frequency reuse factor.