Transmission And Sensing Technology In Cognitive Radio Based On MIMO

With the extensive application of wireless communication technology, spectrum resources are increasingly strained, scarce radio spectrum resource has become the main reason for the restriction of development of wireless communication technology. Cognitive radio technology emerges, without prejudice to the authorized user to use the case and improve the spectrum utilization. What’s more, it has some ability to learn, through the spectrum sensing, it can adjust its transmission frequency and power to the certain scene. This technique become a hot topic in the future of wireless communications.Currently Cognitive radio can significantly improve the use efficiency of frequency resources on the time dimension by using spectrum sensing and sharing technology. This article makes the MIMO technologies into existing cognitive radio implementation platform, and uses USRP software-defined radio platform to design and implement the MIMO system. The first scheme is based on the space-time coding MIMO system, which is Alamouti coded, the main work is design and implementation of coding, channel estimation, synchronization and decoding digital signal processing module; the second scheme is based on the receive diversity MIMO system, which uses MRC technology, the main work is to approximate SNR, which is based on the obtained RSSI, so as to ensure the merger value of each shunt. Based on these two theoretical scheme, carried out Matlab theory simulation. What’ more, the algorithm is implemented by C ++, and uses GNURadio and USRPN210 to validate the theory, and the results are analyzed. These systems really improve the effectiveness of the information transmission of the cognitive radio system due to the result above.Finally, this article analyzes the existing wireless communication method of acquiring the position information, taking the features of muti-antenna of the cognitive radio MIMO system into account, this article raises the algorithm to acquire the location and power information of the authorization user,which is based on the RSSI/TDOA algorithm. At the low expense of the accuracy,this article find the algorithm which has the simpler location model and calculation process. What’s more, given the existence of communication noise,a weighting algorithm is proposed based on RSSI and TDOA data,which is in the statistical point of view, to the optimize the result of authorized user location information based on RSSI / TDOA,so as to reduce its root mean square error(RMSE). This article uses Matlab to simulate these two theoretical algorithm above and analyzes the results.