A Convex Optimization Algorithm for Total Rate Maximization in Block Diagonalization Based Ultra Dense Network

Ultra dense network (UDN) has drawn widely attention due to its virtual cell structure in which users are served by multiple base stations (BS) could significantly boost the total capacity, and have vast potential for further development in next 5G wireless systems. Nevertheless, the interference between different users in UDN is still a critical issue and hence the quality of communications can be seriously affected. In this paper, we consider a UDN consisting of multiple virtual cells, and focus on maximizing the total user rate of this network. To eliminate the interference between each user, block diagonalization is used so that the original rate maximization problem can be transformed to a convex optimization problem. To solve this problem, an algorithm is proposed which is based on barrier method and in combination with Newton method and backtracking line search. Simulation results have validated that the proposed algorithm can have same performance but with significantly faster computing speed than the existing CVX solver.