Energy Efficiency and BER analysis of Concatenated FEC Coded MIMO-OFDM-FSO System

Various advanced digital signal processing techniques that includes modern algorithms and optimizations are applied to MIMO-OFDM system for cost and complexity reduction. A novel approach is utilized in the proposed model by taking the concatenated forward error correction codes with MIMO-OFDM system in free space. The performance of MIMO-OFDM-FSO system is investigated here which uses multiple antennas at both input and output sides along with orthogonal frequency division multiplexing technique that provides larger spectral efficiency. The purpose of this work is to reduce the bit error rate of MIMO-OFDM-FSO system to make it more energy efficient and economically suitable. Three concatenated Forward Error Correction (FEC) codes such as LDPC Code with Trellis coded modulation (TCM), Reed Solomon Code with Convolution codes, and LDPC Code with VBLAST are applied to MIMO-OF DM-FSO system to increase the energy efficiency with less power consumption which is a major economical concern. Gamma-Gamma channel is selected to investigate the BER performance of the system in strong and weak turbulence conditions and the result is simulated using MATLAB. The analysis shows that LDPC code concatenated with TCM code applied to MIMO-OFDM system exhibits better BER in the order of 10-9 in strong turbulence condition and 10-10 in weak turbulence condition. Further it is noticed that the concatenated FEC coded MIMO-OFDM is more energy efficient and shows better BER performance as compared to uncoded MIMO-OFDM in FSO.