STC-Mimo Block Spread OFDM in Frequency Selective AWGN Channels

Abstract

OFDM is a method of encoding data on multiple carrier frequencies in digital domain and it is developed into a popular scheme for wide band digital communication, which is essentially a Frequency-Division Multiplexing (FDM) scheme used as a digital multi-carrier modulation method. There is tremendous technological growth towards exploiting the bandwidth of a system. Especially, in wireless domain, 60 GHz RF band has a great scope which can offer a bandwidth of 5 GHz. OFDM systems transmit multiple parallel low bandwidth channels of data through a wideband channel. This technique achieves high data rate providing transmission using low bandwidth sub channels within the allocated channel. The more the number of sub-carriers the better will be the immunity to the frequency selective fading of signals and similarly higher will be the data-rates for that complex architecture with large number of oscillators and filters are required to implement an OFDM system in hardware. Initially after coding as per the Space Time code (STC), we multiply the symbols with the channel and then add white Gaussian noise to it, and then equalize the received symbols. Perform hard decision decoding and count the bit errors. Finally by repeating the same for multiple values of   we obtain the plot for simulation and theoretical results. The code for simulation is done in MATLAB.