The Performance Analysis Of OSTBC-OFDM System Over Nakagami-m Fading Channels

With the integration of Internet and multimedia services in next generation wireless communications, the demand for wide-band high data rate communication services is growing. Wireless system designers are faced with a number of challenges. These include the limited availability of the radio frequency spectrum and a complex time-varying wireless environment (fading and multipath). Therefore, high speed, reliable and high frequency efficient wireless transmission technology is being the investigations of hot spots in the area of mobile communication.The multiple-input multiple-output (MIMO) technology is an important breakthrough in the area of wireless communication. Being the key technology of new generation mobile communication systems, it can be used to improve the capacity, error probability and frequency efficiency significantly without extra frequency bandwidths and transmitted power. Space-time coding technology introduces spatial and temporal correlation at transmission. It indicates a new idea of providing high transmission rate in wireless communication systems and has recently received considerable attention. Orthogonal frequency division multiplexing (OFDM) is a multi-carrier transmission scheme that can potentially attain high-rate transmission due to enhanced temporal spectral efficiency, which lead to that OFDM technology has obtained more attention.This paper is mainly focused on the space-time coding technique and OFDM technique. Firstly, we introduce the principle of space-time code and OFDM. Secondly, we analyze the encoding and decoding theories, features, and compare performances of various space-time block code schemes. Simultaneously, we present the examples and simulation results. Later, based on the basic model of STBC-OFDM system, we propose the STBC-OFDM system modeling with precoder (PST-OFDM), which can recover the signal accurately and give the performance results of STBC-OFDM over different fading channels. Finally, a scheme for mitigation of multipath fading effects and suppression of multiuser interference (MUI) is presented. Using The Monte Carlo simulation, performances of multiuser STBC-OFDM systems are analyzed with simulation results given. Using the traditional probability density function (PDF) approach, the closed-form expressions for average symbol error rate (SER) of OSTBC-OFDM systems employing M-PSK and M-QAM modulation schemes over uncorrelated Nakagami-m fading channels with different noise environment (including Gaussian noise and non-Gaussian noise) are derived, which are expressed in terms of several hypergeometric functions. The SER performance with respect to flat fading channels and frequency-selective fading channels are evaluated with these expressions, respectively. In addition, according to the moment generating function approach, we derive the closed-form expressions for average symbol error rate (SER) of OSTBC-OFDM systems employing M-PSK modulation schemes over correlated Nakagami-m fading channels. Finally, Monte Carlo simulation is performed, and simulation results show fine agreement with the analyses.