The invention provides a downlink 
transmitter system and an operating method thereof. The downlink 
transmitter system is used for supporting transmission of two-
channel code words in a double-antenna channel and comprises a 
processing module, a layer mapping module, a 
precoding module and a resource mapping module, wherein the 
processing module is used for subjecting the inputted two-
channel code words to time-sharing serial 
processing in a one-
channel code word direction so as to obtain a 
code word serial data flow; the layer mapping module is used for subjecting the 
code word serial data flow to layering processing and outputting two 
layers of data flows; the 
precoding module is used for preprocessing the two 
layers of data flows and distributing the two 
layers of preprocessed data flows to different antenna ports; the resource mapping module is used for storing, reading and adding the two layers of data flows. The downlink 
transmitter system has the advantages of low hardware cost, simplicity in control, high universality and 
extensibility, capability of supporting downlink channel transmission and multiple double-antenna transmission 
modes stipulated by protocols and compatibility with single-antenna transmission 
modes.