A method for encoding a status PDU including receiving AMD PDUs, determining whether or not there are missing AMD PDUs, calculating an error-checking range and at least one error-occurrence range if it is determined that there are missing PDUs, calculating a distance ratio using the error checking range and error occurrence range, determining whether or not the distance ratio is greater than or equal to a threshold value, selecting a type of super-field for constituting a status PDU based on a determination result, encoding the status PDU with the type of selected super-field, and sending the encoded status PDU to a sending party.