Three hop AF relay transmissions for OFDM applying real and imaginary TFI pilot signals
Yuta Ida, Takahiro Matsumoto, Shinya Matsufuji · 2017
Multi-hop relay transmissions achieve high quality and vast area communications by using several relay nodes. For the relay method based on an amplify-and-forward (AF), channel estimation (CE) is only demanded in the destination node. In the single-hop AF relay transmission for orthogonal frequency division multiplexing (OFDM) systems, we have proposed the CE by using the pilot signal based on the time frequency interferometry (TFI). However, in the multi-hop AF relay transmission, the conventional TFI method degrades the system performance due to a null signal and the overlapped channel. To solve this problem, in this paper, we propose the CE based on the real and imaginary TFI pilot signals in the three hop AF relay transmission for OFDM systems.