Novel Transmit Diversity Scheme for TDS-OFDM System With Frequency-Shift m-Sequence Padding

This contribution proposes a design method for training sequence (TS) defined as frequency-shift m-sequence (FSMS) and a novel transmit diversity scheme with FSMS padding as guard interval (GI) for the further evolution of time domain synchronous orthogonal frequency domain multiplexing (TDS-OFDM) systems. The good auto-correlation characteristic of FSMS can facilitate synchronization and channel estimation at the receiver. Due to the cross-correlation characteristics of FSMSs, the accuracy of channel estimation is affected by the mutual interference among the transmit antennas. To further improve the accuracy of channel estimation, the channel impulse response (CIR) should be estimated in an iterative manner to suppress the effects of the mutual interference and additive white Gaussian noise. Compared with the transmit diversity schemes based on the space-frequency coded TS and space-time coded TS for TDS-OFDM system, the proposed transmit diversity scheme with FSMS padding can provide diversity gain and superior system performance over time-varying and/or frequency-selective propagation conditions.