Modified design of STBC Encoder for reducing Non-Linear distortions in OFDM Channel Estimation

Abstract

The non-orthogonal encoding in MIMO communication cause fading in OFDM Channel which further increase the BER. For Orthogonal Frequency Division Multiplexing (OFDM) systems, this work develops a new Quasi Space-time block codes (STBC) Encoder of while maintain full rate in Multiple Input Multiple Output (MIMO) communication. This work shows that not only the Alamouti-scheme which was useful only for STBC for two transmit antennas but with four transmit antenna we can also archive optionality with full rate of communication. This work is carried out on 4x4 Orthogonal Frequency Division Multiplexing (OFDM) framework and use encoder having 12 full orthogonal sets outs of total 16 possible combination of fading matrix. Non-Linear distortions due to High power amplifiers (HPA) at transmitters of MIMO communication system are one of the major causes of Low SNR (Signal to Noise Ratio), Proposed STBC encoder fading matrix also kept the input signals symbols linear with output signal symbols. This work is carried out on MATLAB-2018b EDA device and tried on something very similar with different commotion channels conditions.