The Research Of HARQ Technique In The LTE Uplink And Its Implementation In The MAC

To compete with WiMAX and other emerging broadband wireless communications technology, 3GPP has put forward the Long Term Evolution (LTE) plan, which increases the peak data rates of packets, improves the service quality and makes fully use of frequency spectrum.And Hybrid Automatic Repeat Request is one of the wireless technology, crucial to the wireless communications system characterized with high-speed of datas and high quality of service.In the paper, it first analyzes LTE radio protocol stack and a variety of key wireless technologies of LTE, and studies the existing kinds of HARQ mechanism in 3GPP protocols and the latest development in depth.Then, an LTE uplink simplified baseband simulation platform is builded based on MATLAB, on this basis, three HARQ mechanism is constructed, realizing modules of CRC calculation, Turbo coding and decoding, rate matching and chase combination and so on. Simulations performance of the system with Type-I, CC, IR HARQ are preformed respectively. The results show that: IR HARQ is the most efficient scheme. And more simulations on IR HARQ mechanism with improved chase combination indicate this system gain increased furthest, but its implementation complexity is also the highest among them. Last but not least, with DSP/BIOS as the operating system, the MAC scheduling code in LTE uplink HARQ system is achieved on DSP hardware platform using C language. After the debugging of the system, the technology of HARQ in LTE is successfully completely.