LTE-A system downlink HARQ system-level design and simulation

Hybrid automatic retransmission technology for reducing the error rate and the rate of data transmission system play an important role in the LTE-A system, so designing A good kind of HARQ transmission mechanisms and processes is necessary for system operation, which has guidance for network and terminal. In this paper the main research is the downlink HARQ. Based on the interface between the layers, the paper designs a flow chart for the HARQ, finally, makes a brief introduction of the SDL and TTCN tools and its work principles, based on the previous design and development of code, takes the process of data transmission for instance, by the C code embedded in the SDL, gets the software implementation, and by use of the TTCN tools, makes a conduction of test case, and then by the co-simulation of SDL and TTCN, gets the MSC diagram of the related process, and verify the correction of the previous designed by the analysis of the MSC.