To overcome the error propagation and improve the communication efficiency of the chaotic pulse position modulation\n(CPPM) system, the bipolar chaotic pulse position modulation (BCPPM) communication system is proposed here.\nIn BCPPM, every two-bit data are set as a group. The first bit and the discrete chaotic map determine the position\nof sent pulse, while the second bit determines the polarity of sent pulse. Each pulse in the channel contains\ntwo-bit information, so this scheme improves the communication efficiency. A (255,175) cyclic low-density\nparity-check code (LDPC) was designed, and its generator matrix and parity check matrix are cycled. Furthermore,\nthe constructed BCPPM communication system is utilized in the cyclic LDPC aiming to mitigate the effect of\nnoise. In the transmitter, it uses the encoder structure of cyclic codes while the min-sum algorithm is deployed\nto decode in the receiver. The analysis indicates that the proposed system is secure, insensitive to the channel\ndistortion and convenient for multiple access communication. The simulation results show that in the additive white\nGaussian noise (AWGN) channel, multipath channel, multiuser model, and hybrid communication environment, the\nBCPPM system has lower bit error rate (BER) compared with those of the CPPM and chaotic pulse on-off-keying\n(CPOOK). In addition, using cyclic LDPC codes, the system is more suitable for hardware implementation.
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