Abstract

This paper discuss the Low Complexity Post-Coded MIMO OFDM (PC-MIMO OFDM) Systems: Design and performance analysis. The signal is propagating from the transmitter to receiver along number of different paths, referred as multipath in wireless environment. Path loss, macroscopic fading and microscopic fading are propagating signal power drops. Orthogonal Frequency Division Multiplexing (OFDM) provides a viable solution to communicate over selective fading channels. OFDM offers several advantages like resilience to multipath fading in intersymbol interference, low complexity and others. Multiple input multiple output (MIMO) utilizes spatial diversity by having several transmit and receive antennas. The combination of MIMO and OFDM has been designed to improve the data rate and Quality of service (QoS) .The wireless system utilizes the multiplexing gain and/or diversity gain which is a major problem in communication. The combination MIMO-OFDM is very natural and beneficial, since OFDM enables support of more antennas and large bandwidths. Coded or precoded OFDM systems are generally employed to overcome the symbol recovery problem in uncoded OFDM systems. The post coded OFDM systems introduce frequency diversity by manipulating the OFDM systems in time domain so that the computational complexity of the system can be significantly reduced. We discuss the design principle of PC-MIMO OFDM system transmitter that uses up sampling operation and spreading codes to introduce frequency diversity .We also describe the design of low complexity receiver for PC-MIMO OFDM systems to minimize error performance. The main advantages of this scheme are reduce system complexity by having a simple encoder/decoder ,smaller size inverse fast Fourier transform/fast Fourier transform (IFFT/FFT)modules, and lower clock rates in the receiver and transmitter leading to be lower energy consumption. The proposed system is found to be equally good over Gaussian and Fading channels where it achieves