Orthogonal space-time block codes in MIMO-OFDM cognitive radio communication system

This paper describes the MIMO technology, cognitive radio technology as well as orthogonal space-time block codes. To take full advantages of these three techniques, we eventually combine them to form a new program. The cognitive link and the main link of MIMO system can be set multiple antennas. In the cognitive system, cognitive users can use the authorized free frequency band, thereby enhancing the utilization of spectrum resources, and the estimated channel information will be used for channel decoding. The orthogonal space-time block codes in MIMO system can provide multiple transmit/receive antennas´ full diversity gain, minimizing the impact of multi- path fading and gaining better BER performance, increasing the digital transmission rate at the same time. Simulation results show that the cognitive radio communication system based on MIMO OSTBC has significantly improved the signal to noise ratio in comparison to normal un-coded system.