Improvement of Bit Rate Using M-ary Chaotic Pulse Position Modulation

Abstract

Recent studies have pointed out that Chaotic Pulse Position Modulation (CPPM) is a very promising method forimproving privacy and security in chaos-based digital communication. Especially, CPPM provides better performance thanother chaotic modulation methods in noise- and distortion-affected environments. In this paper we present our developmentof a robust method named M-ary CPPM which is based on the combination of the conventional CPPM and multi-symbolmodulation in order to improve the transmission bit rate. The M-ary CPPM signal has a pulse train format in which eachpulse is a symbol and the chaotically-varied inter-pulse time interval conveys the binary information of k bits (M = 2k).The analysis and development of modulation and demodulation schemes are presented in detail. Theoretical evaluation ofBit-Error-Rate (BER) performance in the presence of additive white Gaussian noise (AWGN) and the use of AWGN filteringis also provided. The chaotic behavior of the M-ary CPPM is investigated with the variation of modulation parameters.In order to verify the performance of the proposed schemes, numerical simulations were carried out in Simulink andcomparison between simulation and theoretical results is reported.