| Abstract: | This paper considers a spectrum‐sharing cognitive radio (CR) multiple‐input–single‐output (MISO) system which consists of a secondary user transmitter (SU‐Tx) having multiple transmit antennas, K secondary user receivers (SU‐Rxs) each having a single antenna, and a primary user (PU) having a single antenna. The channel state information (CSI) for the links between SU‐Tx and SU‐Rxs are assumed to be perfectly known at the SU‐Tx. To ensure the quality of service (QoS) of PU and maximize channel capacity of SU, we formulate the channel capacity as a multiconstraint optimization problem and propose a power allocation algorithm based on QPSK constellation to solve the problem. Finally, numerical simulations are conducted to corroborate our theoretical results. It is shown that the proposed algorithm is capable of achieving a large channel capacity with fast convergence. © 2014 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. |
