An embodiment of the invention provides a method to be performed by a first wireless communication apparatus in communicating with a second wireless communication apparatus. First, the first wireless communication apparatus determines whether a plurality of sub-channels are simultaneously available for the second wireless communication apparatus. Then, the first wireless communication apparatus simultaneously uses the sub-channels to transmit a plurality of divergent copies of a data segment to the second wireless communication apparatus, respectively, if the sub-channels are simultaneously available for the second wireless communication apparatus.