设计了一种简易数字控制红外通信装置,系统硬件部分由红外发射电路、红外接收电路和中转电路3部分组成。系统以STM32F051C4为控制核心,以红外线为载体,采用PWM调制技术、曼彻斯特编码方式,实现了语音和温度信号的实时传输。系统设计完...设计了一种简易数字控制红外通信装置,系统硬件部分由红外发射电路、红外接收电路和中转电路3部分组成。系统以STM32F051C4为控制核心,以红外线为载体,采用PWM调制技术、曼彻斯特编码方式,实现了语音和温度信号的实时传输。系统设计完成后经过实验测试,在输入800 Hz的正弦信号,输出电压有效值不低于0.4 V时,红外光发射电路与红外光接收电路之间的传输距离最大为4 m,输出的噪声电压小于40 m V;电路最大供电电流不超过20 m A。展开更多
Due to the ubiquitous open air links and complex electromagnetic environment in the satellite communications,how to ensure the security and reliability of the information through the satellite communications is an urg...Due to the ubiquitous open air links and complex electromagnetic environment in the satellite communications,how to ensure the security and reliability of the information through the satellite communications is an urgent problem.This paper combines the AES(Advanced Encryption Standard) with LDPC(Low Density Parity Check Code) to design a secure and reliable error correction method — SEEC(Satellite Encryption and Error Correction).This method selects the LDPC codes,which is suitable for satellite communications,and uses the AES round key to control the encoding process,at the same time,proposes a new algorithm of round key generation.Based on a fairly good property in error correction in satellite communications,the method improves the security of the system,achieves a shorter key size,and then makes the key management easier.Eventually,the method shows a great error correction capability and encryption effect by the MATLAB simulation.展开更多
In this paper, based on the characteristics of polar codes, a new decode-and-forward strategy called generalized partial information relaying protocol is proposed for degraded multiple-relay networks with orthogonal r...In this paper, based on the characteristics of polar codes, a new decode-and-forward strategy called generalized partial information relaying protocol is proposed for degraded multiple-relay networks with orthogonal receiver components(MRNORCs). In such a protocol, with the help of partial information from previous nodes, each relay node tries to recover the received source message and re-encodes part of the decoded message for transmission to satisfy the decoding requirements for the following relay node or the destination node. In order to construct practical polar codes, the nested structures are developed based on this protocol and the information sets corresponding to the partial messages forwarded are also calculated. The proposed scheme is proved to be capable of achieving the theoretical capacity of the degraded MRN-ORCs while still retains the low-complexity feature of polar codes. We perform simulations to testify the practicability of the proposed scheme and compare polar codes by using successive-cancellation list decoder(SCLD) with traditional low-density parity-check(LDPC) codes. The results show that the obtained polar codes provide significant gain.展开更多
A new log-likelihood ratio(LLR) message estimation method is proposed for polarization-division multiplexing eight quadrature amplitude modulation(PDM-8QAM) bit-interleaved coded modulation(BICM) optical communication...A new log-likelihood ratio(LLR) message estimation method is proposed for polarization-division multiplexing eight quadrature amplitude modulation(PDM-8QAM) bit-interleaved coded modulation(BICM) optical communication system.The formulation of the posterior probability is theoretically analyzed,and the way to reduce the pre-decoding bit error rate(BER) of the low density parity check(LDPC) decoder for PDM-8QAM constellations is presented.Simulation results show that it outperforms the traditional scheme,i.e.,the new post-decoding BER is decreased down to 50%of that of the traditional post-decoding algorithm.展开更多
文摘设计了一种简易数字控制红外通信装置,系统硬件部分由红外发射电路、红外接收电路和中转电路3部分组成。系统以STM32F051C4为控制核心,以红外线为载体,采用PWM调制技术、曼彻斯特编码方式,实现了语音和温度信号的实时传输。系统设计完成后经过实验测试,在输入800 Hz的正弦信号,输出电压有效值不低于0.4 V时,红外光发射电路与红外光接收电路之间的传输距离最大为4 m,输出的噪声电压小于40 m V;电路最大供电电流不超过20 m A。
基金supported by the National 863 Project of China under Grant No.2012AA01A509,No.2012AA120800
文摘Due to the ubiquitous open air links and complex electromagnetic environment in the satellite communications,how to ensure the security and reliability of the information through the satellite communications is an urgent problem.This paper combines the AES(Advanced Encryption Standard) with LDPC(Low Density Parity Check Code) to design a secure and reliable error correction method — SEEC(Satellite Encryption and Error Correction).This method selects the LDPC codes,which is suitable for satellite communications,and uses the AES round key to control the encoding process,at the same time,proposes a new algorithm of round key generation.Based on a fairly good property in error correction in satellite communications,the method improves the security of the system,achieves a shorter key size,and then makes the key management easier.Eventually,the method shows a great error correction capability and encryption effect by the MATLAB simulation.
基金supported by the National Natural Science Foundation of China (No.41574137, 41304117)
文摘In this paper, based on the characteristics of polar codes, a new decode-and-forward strategy called generalized partial information relaying protocol is proposed for degraded multiple-relay networks with orthogonal receiver components(MRNORCs). In such a protocol, with the help of partial information from previous nodes, each relay node tries to recover the received source message and re-encodes part of the decoded message for transmission to satisfy the decoding requirements for the following relay node or the destination node. In order to construct practical polar codes, the nested structures are developed based on this protocol and the information sets corresponding to the partial messages forwarded are also calculated. The proposed scheme is proved to be capable of achieving the theoretical capacity of the degraded MRN-ORCs while still retains the low-complexity feature of polar codes. We perform simulations to testify the practicability of the proposed scheme and compare polar codes by using successive-cancellation list decoder(SCLD) with traditional low-density parity-check(LDPC) codes. The results show that the obtained polar codes provide significant gain.
基金supported by the National Natural Science Foundation of China(No.61205065)the Fund of State Key Laboratory of Information Photonics and Optical Communicationsthe Fundamental Research Funds for the Central Universities in China(No.2014RC1201)
文摘A new log-likelihood ratio(LLR) message estimation method is proposed for polarization-division multiplexing eight quadrature amplitude modulation(PDM-8QAM) bit-interleaved coded modulation(BICM) optical communication system.The formulation of the posterior probability is theoretically analyzed,and the way to reduce the pre-decoding bit error rate(BER) of the low density parity check(LDPC) decoder for PDM-8QAM constellations is presented.Simulation results show that it outperforms the traditional scheme,i.e.,the new post-decoding BER is decreased down to 50%of that of the traditional post-decoding algorithm.
