Research On Trellis-Coded Modulation And HARQ Techniques In Wireless Communication

The development of China's wireless mobile communication technology is unprecedentedly rapid since the 21st century. The most significant character of next generation transmission system is high speed and wide band, therefore the designing of system should satisfy larger capacity, higher spectrum efficiency and more reliable transmission quality. Error correction coding is required to be highly efficient without expending spectrum, thus the association of coding and modulation takes on special significance and gradually becomes a researching hotspot in wireless communication field.This thesis mainly researches on trellis-coded modulation (TCM) technology. Firstly the fundamental principle of TCM is introduced, and different kinds of TCM systems aiming at different coder types and modulation schemes are constructed. The designing and working theory of the system is presented in detail both generally and specifically. Existing algorithms are reasonably optimized during simulation process so as to obtain bigger coding gain.Along with the proposal of Turbo codes, the combination of Turbo codes and TCM earns increasing concern. This thesis introduces two types of Turbo TCM schemes, and simulates the systems adopting different schemes. Simulation results shows the combination scheme of TCM and Turbo codes exerts favorable capability under low SNR condition. Performances of different schemes are compared, which can be theoretical guidance to system implementation for the future.Besides channel coding in physical layer, retransmission technique in data link layer is also considered and associated with TCM in this thesis. Hybrid Automatic Repeat Request (HARQ) system model based on TCM is built, forward error correction coding and modulation modules in conventional HARQ system are substituted with TCM, and system retransmission mechanism is explained in detail. The signal processing manner of TCM based HARQ system receiver is improved, and simulation results of the improved system capabilities are also presented. It shows that complexity of code combining processing method in receiver can be reduced through retransmission and symbol-bit rearrangement, and considerable performance improvement is obtained.