Joint channel and Doppler shift estimation in TDS-OFDM using frequency sensitive set

Abstract

Time-varying channel always plays great obstacle to OFDM (orthogonal frequency domain modulation) as it introduces intercarrier interference (ICI). In terrestrial digital television broadcasting systems, residual Doppler shift may exist and deteriorate the orthogonality of subcarrier signal, especially during high-speed transportation such as high-speed railways. This paper proposed a jointly Doppler and channel estimation method originated from conventional sparse channel estimation in time-domain synchronized OFDM (TDS-OFDM) scheme, which shows a promising technique to further combat ICI without compromising on spectral efficiency.

A low complexity frequency offset estimation for dual PN TDS-OFDM

“…In the simulation, we adopt M = 2048 , while N has three different values of 128, 256 and 512. η = 112ppm, ε = 0.1 * N/2048 , which means that after one OFDM frame, the phase of carrier has changed nearly 0.1 * 2 * π [6] . η is searched in the range {(−N η /2)μ η , (−N η /2 + 1)μ η , · · · , (N η /2)μ η }, where μ η = 6 * 10 −6 , N η = 1000.…”

“…The work in [6] used a time domain model to jointly estimate channel response and CFO for dual PN TDS-OFDM systems. In [6] , channel model is path-based and CFO is assumed to be resulted by Doppler shift residue.…”

“…The work in [6] used a time domain model to jointly estimate channel response and CFO for dual PN TDS-OFDM systems. In [6] , channel model is path-based and CFO is assumed to be resulted by Doppler shift residue. Because CFO is too small to have obvious effect during one PN length, the second PN of every two consecutive OFDM frames is piled up to obtain a longer PN sequence.…”