SFO compensation by pilot-aided channel estimation for real-time DDO-OFDM system

• A pilot-aided and linear interpolated channel estimation is experimentally demonstrated in real-time OFDM system.
• The pilot-aided and linear interpolated channel estimation can help to compensate the sampling frequency offset effect.

In this paper, we experimentally demonstrated a pilot-aided and linear interpolated channel estimation technique in the real-time direct-detection optical orthogonal frequency division multiplexing (DDO-OFDM) system using a cost-effective directly modulated laser (DML). It has been verified that the pilot-aided and linear interpolated channel estimation technique can help to compensate the sampling frequency offset (SFO) effect. The experimental results show that, based on the pilot-aided and linear interpolated channel estimation technique, even at a SFO of 170 ppm, a 16-QAM-OFDM signal can be successfully transmitted over 100-km SSMF under the hard-decision forward-error-correction (HD-FEC) threshold with a bit error rate of 3.8×10−3. And the effect of up to ~25 ppm SFO can be negligible.