a Power allocation for multi-antenna multiple access channels in cognitive radio networks

A cognitive radio network is often described as a secondary communication network operating in a frequency band originally allocated to a primary network consisting of one or multiple primary users. A fundamental challenge for realizing such a system is to ensure the quality of service of the primary users as well as to maximize the throughput of the secondary users. In this paper, we consider a sum-rate maximization problem for single-input multiple output multiple access channels (SIMO-MAC) under interference constraints for the primary users as well as a peak transmission power constraint for each secondary user. We apply zero-forcing based decision feedback equalizers to decouple the SIMO-MAC, and develop a capped water-filling algorithm to maximize the sum-rate of the secondary users. We also investigate another scenario where only multiple primary users' interference constraints are considered. Furthermore, we provide numerical simulations to illustrate the effectiveness of the algorithm.