Research On Coding And Decoding Algorithms Of Low-Density Parity-Check Code Based On Ultra-Wideband System

The wireless communication has replaced the cable communication mode in manyapplication areas because of its flexible mobile features. And for a large number of users ofwireless has the demand to access the wireless data, the spectrum resources are increasinglyscarce, the improvement of wireless communication security level requirement, dependenceon the space capability，anti-interference, as well as the data rate, the ultra-widebandcommunication system can be a good solution for above problems. But there is a problem: theUWB system must be operated under the Effective Isotropic Radiated Power(EIRP),and thisstrict rules makes the signal-to-noise operate level is very low. For such a low power signal,the performance of UWB system could be limited, and would damage the effectiveness ofinformation during transmission.A potential solution is proposed, namely introduce apowerful channel coding, a coding with the ability of error correction and detection isattractive for low cycle pulse system. So we under the premise of reduce the symbol repetitionand guarantee the transfer data rate, then add the channel coding module, this could has apositive role in improving the system performance. So it is necessary and meaningful toresearch the channel coding scheme in UWB system.In this paper, the UWB system basic principle of communication is first introduced, andanalysis the launch and receiving process, the modulation、demodulation and multiple accesscontrol mechanisms. In this paper, we mainly introduce the LDPC (Low-Density-parity-check)codes, through the research of H matrix’s structure, encoding algorithm and decodingalgorithm, we find LDPC codes has its advantages. In this paper, we propose a methodcombining the QC-LDPC and the RA code, and applied to IR-UWB systems, by this way toimprove the overall performance of the system. We use the simulation analysis, through thedifferent modulation mode, multiple access system. When we use a structured constructedLDPC code scheme to replace the repetition coding used in traditional UWB system canobtain greater performance gain. At the same time, we analyzes the single pulse andmulti-pulse system, no multi-path channel，the typical indoor multi-path propagation channel,as well as the selection of decision rules, different receiver structure, how these parametersaffect the performance of the whole system. This paper analyzes the bit error rate of theIR-UWB systems with the presence of LDPC rectifying and detection error code, and theimpact of different length of LDPC data packet on the IR-UWB system. The simulationresults confirm the feasibility of theory study, the combination of the two kinds of schemeshas played a positive role to improve the system performance in error correction ability.