The Application Of Space-Time Coding Technology Based On OFDM

With the rapid development of wireless communications in recent years, the studies of next-generation mobile communication (4G) have been carried out in full swing. The next generation of mobile communication can increase the data transfer rate in the limited bandwidth of high-capacity transmission. The space-time coding technique is the important technology to solve the bandwidth problem based on OFDM (orthogonal frequency division multiplexing), it can take full advantage of multi-scattering wireless channel which caused by multipath environment, thereby enhancing the ability of anti-fading.In this paper the OFDM system and the space-time coding techniques have been studied, analyze the three kinds of space-time coding principle of encoding and decoding, and And simulate analysis of each encoding method. By comparing the complexity of the decoding and the improving of space-time block coding, it proposes a new coding method - a new space-time block coding, and this encoding method is applied to OFDM systems, builting NSTBC (new Space-Time Block Coding)- OFDM system.Through the analysis between OFDM system and NSTBC-OFDM simulation, it obtained the performance curves of these two systems which mainly for its BER analysis. By changing the number and modulation methods about the transmitting antenna and receiving antenna, it receives different antennas and different modulation schemes under the BER curves. Analysis of these curves, you can see space-time coding technology significantly reduce the systemBER in the post-OFDM system and improve diversity gain.Finally, it is the research in NSTBC-OFDM system channel estimation method, including training sequence based channel estimation methods, and based on pilot symbol channel estimation method. After space-time coding techniques applied to this system, the channel estimation algorithm has been simplified, as well as the traditional channel estimation algorithm proposed to improve the algorithm, so that algorithm has been optimized. Through the algorithm, it takes an improved channel estimation method - iterative channel estimation method, and iterative algorithm is applied to a new space-time coded OFDM system. The algorithm reduces the complexity of channel estimation, and the simulation which shows that the system performance using the algorithm to be significantly improved.