Nowadays, there is significant demand for the higher data rate with spectral efficient communications using the Multiple Input Multiple Output (MIMO) systems. The Orthogonal Frequency Division Multiplexing (OFDM) is recognized as key technology as it delivers the high data rate transmission the future MIMO systems. The conventional OFDM standards such as cyclic prefix OFDM (CP-OFDM) and time domain synchronous OFDM (TDS-OFDM) are mainly based on frequency domainpilots and time based pseudo noise (PN) sequence for the channel estimation respectively. However, the fast data rate, spectral efficiency, efficient performance over the fast fading channels becomes more essential for the OFDM based communication systems like Massive MIMO or IEEE 802.16m,Mobile WiMAX.The recent OFDM standard called Time Frequency Training OFDM (TFT-OFDM) delivered the higher data rate and spectral efficiency compared to CP-OFDM. Additionally, TFT-OFDM delivers better BER performance compared to TDS-OFDM. Moreover TFT-OFDM offers reliable performance in high speed environment, thus TFT-OFDM gains the significant attentions from researchers for the efficient channel estimation. In TFT-OFDM, both the time-domain training sequenceand frequency-domain grouped pilots are exploited for the joint timefrequency channel estimation. Further, there are number of optimizations introduced in TFT-OFDM systems to enhance the spectral and data rate efficiency. In this paper, we present the systematic review of TFT-OFDM methods with respect to the two key challenges of MIMO systems such as Spectral efficiency and higher data rate. The outcome of this paper shows the current challenges based on recent works comparative study.
Volume 11 | 01-Special Issue
Pages: 730-735