Bipolar chaotic pulse position modulation communication system based on cyclic LDPC
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Bipolar chaotic pulse position modulation communication system based on cyclic LDPC Hui Li1*, Hanyu Liu1* and Sina Vafi2
Abstract To overcome the error propagation and improve the communication efficiency of the chaotic pulse position modulation (CPPM) system, the bipolar chaotic pulse position modulation (BCPPM) communication system is proposed here. In BCPPM, every two-bit data are set as a group. The first bit and the discrete chaotic map determine the position of sent pulse, while the second bit determines the polarity of sent pulse. Each pulse in the channel contains two-bit information, so this scheme improves the communication efficiency. A (255,175) cyclic low-density parity-check code (LDPC) was designed, and its generator matrix and parity check matrix are cycled. Furthermore, the constructed BCPPM communication system is utilized in the cyclic LDPC aiming to mitigate the effect of noise. In the transmitter, it uses the encoder structure of cyclic codes while the min-sum algorithm is deployed to decode in the receiver. The analysis indicates that the proposed system is secure, insensitive to the channel distortion and convenient for multiple access communication. The simulation results show that in the additive white Gaussian noise (AWGN) channel, multipath channel, multiuser model, and hybrid communication environment, the BCPPM system has lower bit error rate (BER) compared with those of the CPPM and chaotic pulse on-off-keying (CPOOK). In addition, using cyclic LDPC codes, the system is more suitable for hardware implementation. Keywords: Chaotic pulse position modulation; Multipath channel; Multiuser; Cyclic-LDPC
1 Introduction The ultra wideband (UWB) communication system is widely used in communication systems especially in military applications. This technique not only meets the requirements of traditional communication system, but also provides a secure transmission. Due to the flexible working environment, such as indoor or outdoor, it can overcome the multipath propagation and interference from other devices effectively [1,2]. Chaotic communication offers high security and a low probability of intercept [3]. However, since the chaotic synchronization is very sensitive to the signal distortion, filtering and channel noise, utilizing the chaotic communication systems encounters many difficulties in practical applications [4]. In view of the good robust performance of UWB communication on filtering and channel noise, some scholars combined the UWB with chaotic communication and proposed a model of communication system, * Correspondence: [email protected]; [email protected] 1 School of Electrical Engineering and Automation, Henan Polytechnic University, Jiaozuo 454000, China Full list of author information is available at the end of the article
named as chaotic pulse position modulation (CPPM) [5]. In the CPPM system, the intervals between pulses are chaotically changed based on the chaotic map. This communication scheme protects information from interception. Besides, the
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