Novel transmit diversity schemes and iterative channel estimation for TDS-OFDM system

When adopting transmit diversity in Time Domain Synchronous Orthogonal Frequency Division Multiplex (TDS-OFDM) system, the pseudo noise (PN) sequence from different transmit antennas will interfere with each other, so the receiver can't estimate the channel impulse response (CIR) correctly. In this paper, two frame structures with different PN sequence designs for transmit diversity are proposed. One scheme takes PN sequence and zero sequence as frame header alternatively, and the other scheme designs a pair of orthogonal PN sequence based on space-time technique. Based on the proposed schemes, the corresponding iterative channel estimation method is also addressed. Analysis and simulations show that the proposed scheme can achieve good channel estimation and greatly improve the system performance.