Turbo Receiver For Mimo-ofdm System Technology Research

With the quick growth of the capacity and quality requirements, the technologies in wireless communication domain grow rapidly. MIMO can use the space-multiplexing diversity efficiently to boost the system throughput. OFDM can resist frequency selective channel by converting it to flat fading channel in frequency domain. MIMO-OFDM system, which combines the two technologies, can improve channel capacity and robustness of wireless communication system.The architecture of receiver as well as detection and decoding algorithms are critical to the performance of MIMO-OFDM system. In order to keep the whole information when passing it from the detector to decoder, the Turbo receiver use'soft information'instead of'hard'bits. The Turbo receiver can improve performance of MIMO-OFDM system by using the'soft information'. However, the Turbo receiver is more difficult to implement because of the complex iteration architecture. As a result, it is important to find suitable MIMO detection and decoding algorithm, which can satisfy the system requirements and without much complexity.This paper is divided into two main parts, algorithm part and implementation part. In algorithm part, we compared the performance and complexity of several soft-in-soft-out MIMO detection algorithms and several soft-in-soft-out decoding algorithms.Finally we decided to use PIC and Turbo code in MIMO-OFDM system. We also decided for how many times the receiver, the detector and the decoder should iterative. In implementation part, we designed the DSP data processing flow and data transmit flow. The main task of this part is the DSP implementation of SISO Turbo decoder using C language. The C code has to be optimized because of the real time processing requirement. Finally, the result of testing the optimized C code on a single DSP board shows that the decoder meets the requirement of the MIMO-OFDM system.