Optimal resource allocation in HetNets

The deployment of pico cells to cover traffic hot spots within the footprint of a macro cell provides a powerful approach to meet the massive growth in traffic demands fueled by smartphones and bandwidth-hungry applications. Joint optimization of resource allocation and user association is of critical importance to achieve the maximum capacity benefits in such heterogeneous network deployments (HetNets). We first examine the problem of minimizing the amount of resources required to satisfy given traffic demands. We characterize the structure of the optimal solution, and identify a simple optimality condition in terms of the physical transmission rates of the edge users between the macro cell and the various pico cells. We further demonstrate how these structural properties can be leveraged in designing a distributed online algorithm for achieving a max-min fair throughput allocation across all users. Numerical experiments are presented to illustrate the results.