Design And Application With Full Diversity LDPC Codes

Channel fading are the main factors affecting the transmission reliability.If several different parts of a transport packet has different fading factor,the channel can be modeled as a block fading(BF)channel.Conventional channel coding such as low density parity check(LDPC)codes in additive white gaussian noise(AWGN)channels can get superior performance,but will exist diversity gain loss in BF.In this paper,we focus on full diversity LDPC codes,but current study on full diversity LDPC codes are more concentrated in the construction and the theoretical analysis.Based on these,we research on full diversity LDPC codes combined with the application of distributed antennas,and build a low-complexity hardware testbed,to verify the application in a distributed antenna scenarios can achieve excellent performance full diversity LDPC codes.Generally speaking:First,we build a combination of low complexity distributed antenna with full diversity LDPC codes hardware test platform.It adopts low complexity commercial RF chips(CC1101)and ARM platform,set up four transmitting antennas distributed antenna system.Each antenna time-sharing transmits parts of the full diversity LDPC codes,since each transmission experienced flat fading,so that the entire block codeword experienced block fading.So we can verify the advantages of full diversity LDPC codes and traditional LDPC codes designed for AWGN channel.Furthermore,we combine uplink receive diversity technology and feedback retransmission technology to design a reliable data distribution system.The data distribution system downlink adopts distributed antenna with full diversity LDPC codes and time-sharing transmission;uplink transmission takes the restriction of node complexity into account,using a low coding complexity of Turbo codes and multi-antenna diversity reception,to ensure the reliability of the uplink effectively.In addition,using feedback retransmission technology can still achieve reliable transmission even if uplink or downlink fails.Through the above technical solutions to achieve a reliable data distribution,which proves efficient transmission technology based on distributed antenna with full diversity LDPC codes,the technology can be further used in wireless sensor networks.