Capacity enhancement and design analysis of UWB MIMO OFDM over SISO system using microstrip antennas

Multiple-Input Multiple-Output (MIMO) systems offer high capacity to wireless systems over a SISO system and the capacity increases linearly with the number of transmitting antennas as long as the number of receiving antennas is greater than or equal to the number of transmitting antennas. OFDM based Ultra Wideband (UWB) system combines OFDM modulation technique with a multi banding approach, which divides the spectrum into several sub-bands, whose bandwidth is approximately 528 MHz. It is a popular method for high data rate wireless communications. MIMO techniques promise a significant boost in the performance of OFDM systems as compared to SISO systems. In this paper, a novel design UWB MIMO OFDM system using a compact double-sided printed antenna having ultra-wideband and band-notched characteristic is proposed and its capacity enhancement over the conventional SISO system is shown. The UWB antennas are designed on CST Microwave studio simulation software with return loss less than -10dB, and further using the results from CST, the data throughput for both single and multiple antenna system is compared for performance analysis. The MIMO UWB antennas are designed using polarization diversity of the individual antennas. The performance curves of both the systems are analyzed for capacity enhancement. The transmitting bandwidth is UWB (i.e. 3.1-10.6 GHz) and the receiving bandwidth is notch UWB (notch bandwidth 5-5.9 GHz) are chosen to reduce the interference at the receiver side for both the systems. Furthermore, the systems are designed at a frequency of 9.4 GHz that is used for micro power radar application in the ultra wideband removing the interference from WLAN band.