LTE modeling for low complexity Time Varying channels in MIMO-OFDM

Abstract

This MIMO-OFDM study is under the development of LTE (long term evolution).This technique also used in 4G (4^th generation).If we considered this OFDM system using time-varying channel, the orthogonality among subcarrier is the considerable issue for ICI(inter-carrier interference).In existing methods number of channel models and different frame structures are developed to mitigate ICI but problem we faced is its computational complexity is very high. In this implementation we considered low complexity and ICI reduction method for MIMO-OFDM system using linear time varying channels. Complexity of the proposed work is reduced from to ), K=number of subcarriers, M and N are number of transmitters and receivers respectively. Time domain synchronous OFDM is suitable for proposed work because its advantage of easily estimation of linear time varying channels. We analyzed performance of proposed work using two different modulations, QPSK and 16 QAM.By proposed work execution results in MATLAB,we can show that  2dB SNR gain is achieved when the uncoded BER is  and the normalized Doppler frequency is 0.1.In this work we shown the comparative analysis of linear time varying (LTV) channel and linear time invariant (LTI) channel in MIMO-OFDM for given two modulations,QPSK and 16QAM and by changing the number of receiving antennas and Doppler frequency. For comparative analysis we used two objective parameters MSE and BER.The proposed work is extended to SUI modeling for LTI and LTV channels. We used SUI modeling parameters such as antenna diversity, antenna correlation, antenna power gain, etc.Finally, we showed that using SUI

modeling to normal channels (Rayleigh) we can get better performance compared to proposed work.