Research On The Application Of Ofdm Based On Ldpc Code Cooperation Communication

The needs of wireless communication service grow rapidly at modern society, the most obvious trend is to high data rate、 high mobility and no gap roaming, therefore, it puts forward a lot of requirements to the development of the communication. LDPC codes、 multiple relays HARQ collaborative communication and OFDM technology are the future important technology to improve the quality of communication and data transmission rate. The paper will do some research focus on the structure of the LDPC code method、 multiple relays HARQ collaborative communication and OFDM technology, and do the research on the OFDM system based on LDPC code under the conditions of multiple relays coordination communication.LDPC codes are a class of linear block codes which can be represented by spare parity-check matrix or binary maps. It has very low density, low decoding complexity and approximation Shannon limit performance. The paper expounds the LDPC codes of the basic definition and knitting decoding principle systematically, put foucs research on the LDPC code of the check matrix structure method and no-4cycles is brought out. The simulation result shows that the method has better performance than Gallager random structure method.Multiple antennas multiple relays coordination can make up the problem brought by MIMO and improve system performance through the diversity gain. HARQ technology can maximize reduce error rate、 improve the system throughput. In the paper, we combining the multiple antenna multiple relays with HARQ technology, and do the research on the multiple antennas multiple relays coordination HARQ communication system, and put forward a kind of relay option. The simulation result shows that using this method can obtain larger system performance with less relays, it also indicates that multiple antennas relay’s performance is better than the single antenna relay’s.Finally, under the condition of multiple antennas multiple relays channel, applying LDPC code to OFDM system, the simulation results show that using LDPC coded OFDM system can get better performance.