Space Division Multiplexing Aided Opportunistic Spectrum Access for Cognitive Radio Networks
In this paper, a space division multiplexing (SDM) based joint adaptive beamforming downlink transmission scheme for infrastructured cognitive radio multi-input multioutput system is proposed. When spectrum holes exist traditional opportunistic spectrum access is employed. While there is no idle spectrum available, cognitive base station and cognitive user firstly evaluate spatial correlation between cognitive transmission and intersystem interference based on the preprocessed channel information. Incorporated with transmission gain, authorized frequency channel and eigenmode are jointly selected. Then on the premise that no interference is imposed on the primary, cognitive transmission is carried out adopting SDM. The proposed scheme exploits selection diversity of both authorized channel and cognitive eigenmode, thus achieves better spatio-frequency resource management and near-optimal cognitive throughput performance.