Power Allocation for Broadcasting in Multiuser OFDM Systems with Sublinear Complexity

It has been shown that adaptive power and rate allocation for multiuser orthogonal frequency multiplexing (OFDM) improves the system performance significantly. In this paper, the resource allocation that aims at minimizing the total transmission power under certain data transmission constraints is considered. First, the power variation for single-user water-filling while changing the subcarrier assignment is derived. Based on this, a class of methods for multiuser resource allocation is proposed. The presented methods, consisting of tactical processes, can achieve a good balance of computational complexity and performance. Compared to previous works, simulations show that our methods have comparable or better performance and that the computing time for the proposed methods is approximately sublinearly increasing in the number of users K and the number of subcarriers N.