اسم المؤلف:
ابراهيم فهمي علي
اسم المشرف:
حكمت نجم عبد الله
المستخلص:
في هذه الدراسة, تم تصميم منظومتين من CPM وتم تقييم ادائهما في مختلف قنوات الاتصال. اولا, تم اقتراح تقنية فعالة لتخمين القيمة الابتدائية للاشارة الفوضوية في منظومة تضمين القيمة الابتدائية المسماة M - ary ICM. هذه التقنية سميت ب MACE. هذه التقنية قللت من تع | In this study, two Chaotic Parameter Modulation(CPM) schemes are designed and their performance in different communication channels has been evaluated. Firstly, an efficient technique for initial condition estimation of chaotic signal in M - ary Initial Condition Modulation (ICM) scheme is proposed. This technique has been called Maximum Auto Correlation Estimation (MACE). It reduces the complexity of the demodulator; thereby, it minimizes the hardware implementation cost. Simulation results confirm that, the proposed technique outperforms the conventional technique used in direct sequence spread spectrum quadrature amplitude modulation (DSSS - QAM) system in AWGN channel when high modulation level (M) is used. At BER=10 - 3, 16, 256 ary DSSS - QAM achieve gains in Eb/N0 of about 7dB and 0.8dB in comparison with 16, 256 - ary ICM respectively because the modulation level is low. While 1024, 4096 and 16384 - ary ICM achieve gains in Eb/N0 of about 6dB, 10dB and16.5dB in comparison with 1024, 4096 and 16384 ary DSSS - QAM respectively because the modulation level is high. Furthermore, a modified version of ICM that uses BPSK modulation and one chaotic signals source together with MACE technique is proposed to reduce the implementation cost named as BPSK - ICM scheme. Simulation results confirm that, BPSK - ICM has a comparable BER performance to the DS - SS system in AWGN channel.Secondly, the bifurcation parameter of a chaotic signal has been estimated accurately by utilizing the ergodic properties of a chaotic dynamical signal. In BPSK ergodic chaotic parameter modulation (BPSK - ECPM) scheme, the information signal modulates the bifurcating parameter of the chaotic signal. A mean value estimation technique is used at the receiver to retrieve the original information accurately. This method minimizes the computational complexity of the receiver; thereby, reduces the total implementation cost.Simulation results show that, at BER=10 - 3, BPSK - ECPM scheme achieves gains in Eb/N0 of about 1dB, 1.5dB, 5.2dB, 6.5dB, 9dB, 10 dB and 11 dB, as compared with CSS, CC,FM - DCSK, DCSK,CSK,COOK and QCSK schemes respectively in AWGN channel. While in Rayleigh fading channel, at BER=10 - 3, BPSK - ECPM achieve gains in Eb/N0 of about 4.8dB, 5.8dB, 6.5dB and 11.8dB, as compared with FM - DCSK,CSS,CC and DCSK schemes respectively. Furthermore, BPSK - ECPM scheme outperforms conventional chaotic modulation systems in the presence of synchronization error and high data rate problems. Finally, BPSK - ECPM scheme shows a good recovery performance of image signal in multipath fading channel for intelligent transportation system (ITS).
