For applications of elastic optical network (EON),this paper proposes a sub-wav elength granularity optical signal transmission technique based on sub-carrier multiplexing in electrical domain with high flexibility,fine granu larity and high efficiency.The digital signal processing in electrical domain can help to support flexible configurabil ity on different sub-wavelength signals with different modulation formats and transmission rates.To meet the fl exibility requirements from sub-wavelength signal transmission in EON,this paper also proposes a based on c hannel estimation and frequency-domain equalization (FDE) method based on.Detai led studies focus on performance comparisons between pilot signal based FDE a nd training sequence based time-domain equalization (TDE) and FDE methods with different equalization algo rithms.Simulation results show that the pilot signal based zero-forcing FDE algorithm can obtain effective dispersion compen sation and improve the transmission performance with low computation complexity.Meanwhile,taking into account the flexibility requirements from frequency slot and routing configuration in sub-wavelength gr anularity EON,this paper uses numerical simulations to study in detail the transmission performance with diffe rent sub-wavelength signal numbers,transmission distances and modulation formats.It is verified that the channel estimation and FDE method base don linearly frequency chirped pilot signal can achieve good adaptability under different EON configurations,and is one of the key technologies to be used in flexible o ptical transceivers and sub-wavelength signal dynamic redconfiguration.