The present disclosure describes methods, system, and devices for mapping multiple transport blocks (TBs) in a frequency domain. The method includes transmitting a set of transport blocks (TBs) between a first wireless device and a second wireless device by: mapping the set of TBs in a resource space comprising a time unit in a time domain and a frequency unit in a frequency domain, wherein: each TB mapped to a same codeword in the set of TBs is separated in frequency domain; the set of TBs comprises n TBs mapped to the same codeword, and n is an integer larger than 1; and each TB in the set of TBs is capable of being packaged separately at a transmitting end, and capable of being delivered separately to an upper layer at a receiving end.