Key Technology Research And Simulation Analysis Based On WIMAX Physical Layer

WIMAX is an emerging broadband wireless access technology which can providehigh-speed Internet connection. With rapid development of the high-tech such as4G network,mobile internet and the Internet of Things, WIMAX as one of the important supporttechnology also plays a huge role in promoting. LDPC codes and OFDM as the coretechnology in WIMAX in order to deeply study and fully exert its advantage, which need tofocus on discussion in Wireless Communication.This paper focuses on some technologies related with the WiMAX Physical Layer,including the principle of OFDM technology, the principle of the LDPC codes and MIMOtechnology and configuration parameters based on WiMAX standard. We discussed thePerformance of the OFDM System Based on WiMAX Physical Layer. The analysis accord tothe system diagram of the scrambling, concatenated coding, interleaving, symbol mappingand OFDM modulation. through each section for carry out the modularization programming.Next, through experimental observation the performance of the OFDM system, comparing thesystem performance under different conditions primarily including the presence or absence ofconcatenated coding, different coding rate, different symbol mapping method, differentchannel types and the presence or absence of a cyclic prefix on the Performance of the System,comprehensive description of the the Performance of the OFDM System Based on WiMAX.Then this paper analyse and compare the difference in performance between MIMO-OFDMsystem and OFDM system. The simulation results proved the MIMO-OFDM system has thebetter performance.Then this paper discuss how LDPC code in a parity check matrix is generated, andthereby completing the different ways of coding, description of the the special check matrixand rapid coding scheme of the LDPC code based on WiMAX standard in detail. Major workfocuses on LDPC decoding algorithm, dissertate the LLR-SP decoding algorithm, Min-sumdecoding algorithm, the check node matching decoding algorithm, Normalied Min-sum andOffset Min-sum decoding algorithm. Then two improvements were proposed. Firstly, basedon Normalied Min-sum decoding algorithm, we obtain linear calculating formula by differentSNR selected. This paper proposed improved Normalied Min-sum decoding algorithm, compared to Normalied Min-sum decoding algorithm, performance has improved. Secondly,by analyzing the foreign scholars proposed the checksum node matching algorithm and weverify its excellent performance. On the basis with the proposed improved NormalizedMin-Sum decoding algorithm is combined to build a new algorithm called MNMS-DM,through the experimental data can indicate the decoding performance of the new algorithmhas improved greatly, almost close to the performance of the LLR-SP decoding algorithm.Finally, the MNMS-DM decoding algorithm will be applied in the LDPC code based onWiMAX standard which compare the different code lengths, the different ways of coding,different bit rates, the number of different iterations on the LDPC codes. The proposedMNMS-DM Decoding algorithm has a good performance on LDPC decoding.