Performance evaluation of MIMO-OFDM implementation on Wireless open-Access Research Platform (WARP)

Spatial diversity technique known as multiple-input-multiple-output (MIMO) and multi-carrier modulation technique, one of which is an orthogonal frequency division multiplexing (OFDM) technique, is two candidate techniques that are suitable for use on high-speed data transmission in the future. OFDM technique uses a large number of sub-carriers to overcome the effects of frequency selective fading and using cyclic-prefix to suppress inter-symbol-interference (ISI) caused by multipath propagation. The duration of the cyclic-prefix should be longer than the delay-spread of the multipath channel, so that ISI can be removed completely. The application of MIMO diversity techniques on the OFDM system will improve system performance significantly. By using MIMO techniques, many propagation path will be available. These propagation path are departing from a number of antennas on the transmitter side toward a number of antennas on the receiver side directly. Therefore, if there is a severe distortion signals coming out from one of propagation-path then the system may rely on other signals from other propagation-path. Thus the possibility of errors that may occur can be prevented. Furthermore, to increase the diversity of the fading effect, in this study, we use space-time coding-block-code (STBC) Alamouti. This paper aims to study the combined performance of MIMO-OFDM technique when applied to the Wireless open-Access Research Platform (WARP) module, which is one of the software defined radio (SDR) device. The MIMO-OFDM system performance isanalyzed and compared to the MISO-OFDM system, both system use quadrature phase shift keying (QPSK) modulation scheme.