A data unit processing method performed by a first communication device, comprising: configuring a data unit by the first communication device, the data unit comprising: a specific format preamble following a first packet format; and a symbol part, comprising at least one symbol and following a Wi-Fi long range packet format. The specific format preamble can be decoded according to a first communication standard and the symbol can be decoded according to a Wi-Fi long range mode. The symbol part can be identified according to the specific format preamble. A method can decode the above-mentioned data unit and a communication device can perform the methods are also disclosed.