Joint Power and Subchannel Allocation in Heterogeneous OFDMA Small-Cell Networks

Abstract

This chapter proposes a joint subchannel and power allocation algorithm for the downlink of an orthogonal frequency-division multiple access (OFDMA) small-cell network. The total throughput of all femtocell user equipments is maximized while the network capacity of an existing macrocell is protected. We employ an iterative approach in which subchannels and transmit powers of base stations are alternatively assigned and optimized at every step. For a fixed power allocation, we prove that the optimal policy in each cell is to give each subchannel to the user with the highest signal-to-interference-plus-noise ratio on that subchannel. For a given subchannel assignment, we adopt the successive convex approximation approach and transform the highly nonconvex power allocation problem into a sequence of convex subproblems. We show that the overall joint subchannel and power allocation algorithm converges to some local maximum of the original design problem.