Equalizers, communication systems and operating methods thereof

A method of operating a receiver, the receiver comprising a decision feedback equalizer, the method comprising:

• converting a received data signal into a digital symbol stream;
• synchronizing the digital symbol stream into a data frame corresponding to a transmitted frame unit;
• and
• performing a decision feedback equalization operation on the data frame using a predetermined fixed pattern as a feedback decision value,
• wherein the data frame includes a data field at a front end and a comma field at a rear end, and wherein the comma field has a same bit value as the predetermined fixed pattern.

A communication system comprising:

• a transmitter configured to modulate a transmission data frame including a data field at a front end and a comma field at a rear end into an analog data signal and to transmit the modulated analog data signal;
• and
• a receiver configured to receive the analog data signal and to restore the data frame,
• wherein the receiver comprises:
• an analog-to-digital converter configured to convert the analog data signal into a digital symbol;
• and
• a digital signal processor configured to synchronize the digital symbol with the transmitted data frame using a comma index and to filter the synchronized data frame by applying a decision feedback equalization operation, and
• wherein feedback data used in the decision feedback equalization operation comprises a fixed pattern having a same bit value as the comma field.