
The wireless channel is central within this context, thus estimating the channel is the key to make CR operational, taking in consideration that the transmission-reception technology is available. In this thesis, we design a MIMO system using OFDM modulation technology to transmit and receive two signals over the mobile wireless channel. First formulate the pilot design as a new optimization problem. We use MIMO concept to enhance system capacity and robustness of the wireless transmission. In Multi-Input Multi-Output (MIMO) based cognitive radio (CR) systems, with the increasing demand for data rate and reliability in Wireless communications and devices, several issues become very important like bandwidth efficiency, quality of service and radio coverage. In this paper, we evaluate the performance of selective adaptive arrays signal processing and selective space-time block coding signal processing and compare their performance under perfect CSI available at both the transmitter and receiver. By comparing their performance, we see that selective adaptive arrays signal processing outperforms selective space-time coding signal processing when perfect CSI is available at both the transmitter and receiver.