Chaos codes: perbandingan kinerja dan aplikasinya dalam sistem CDMA

Wijanto, Eddy (2009) Chaos codes: perbandingan kinerja dan aplikasinya dalam sistem CDMA. Masters thesis, Universitas Pelita Harapan.

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Abstract

The aperiodic property and the sensitivity to changes in initial conditions of chaos phenomena can be used in Code Division Multiple Access (CDMA) systems that differentiate users based on certain codes. In this thesis, the performance of chaos codes as spreading codes, scrambling codes, and overloading codes is analyzed. The analysis is carried out on the correlation property and the performance comparison in bit error rate (BER) curves. In the process of spreading, when there is only additive white Gaussian noise (AWGN), chaos codes BER is worse than orthogonal variable spreading factor (OVSF) and gold codes, but better than the m-sequences. Scrambling process aims to improve the performance of the spreading codes and adding the variations of CDMA codes. Simulated with AWGN and multipath, chaos codes as scrambler codes have a better performance compared to the gold codes, especially when the number of users are not too large. The new application that was analyzed in this thesis is the process of overloading. The process of overloading is the process of transmitting codes on the normal CDMA codes. The application of overloading can be in the field of military that aims to damage the opponent communication system. In general, the disturbance caused by chaos codes as overloading codes to OVSF greater when compared with gold codes. The performance of chaos codes that is inserted into OVSF system still have a strong performance in general, and is still better when compared with gold codes. For eight users when Eb/No is 10 dB, the BER value for gold codes and OVSF is almost the same values, i.e. 5 x 10-6, where for codes chaos is 2 x 10-4, while the m-sequence is 9 x 10-4. As scrambling codes for eight users with the code length of 16, to reach BER value of 3 x 10-2, gold codes require the Eb/No of 5 dB, and chaos codes as scrambling codes require the Eb/No of 4 dB. In the overloading process, for codes with the length of 128 and with four users, when the Eb/No is 10 dB before inserted with overloading codes, OVSF have BER value of 3 x 10-6. After chaos codes is inserted, its BER value becomes 3 x 10-4, and after inserted with gold codes, the BER becomes 2 x 10-4. BER value of chaos codes after insertion is 1 x 10-5, while BER value of gold codes is 4 x 10-5. / Sifat aperiodic dan sensitif terhadap perubahan kondisi awal dari fenomena chaos dapat dimanfaatkan dalam sistem Code Division Multiple Access (CDMA) yang membedakan penggunanya berdasarkan kode tertentu. Dalam Tesis ini dianalisis kinerja chaos codes sebagai spreading codes, scrambling codes, dan overloading codes. Analisis dilakukan terhadap sifat korelasi dan perbandingan kinerja dalam bentuk kurva bit error rate (BER). Chaos codes menunjukkan nilai autocorrelation dan crosscorrelation yang lebih baik bila dibandingkan dengan orthogonal variable spreading factor (OVSF). Dalam proses spreading, untuk kondisi hanya terdapat additive white Gaussian noise (AWGN), chaos codes lebih buruk bila dibandingkan OVSF dan gold codes tetapi lebih baik bila dibandingkan dengan m-sequence. Proses scrambling bertujuan untuk memperbaiki kinerja kode spreading serta menambah variasi kode CDMA. Dalam kondisi terdapat noise AWGN dan multipath, chaos codes sebagai scrambler memiliki kinerja yang lebih baik dibandingkan dengan gold codes terutama untuk jumlah user yang tidak terlalu besar. Aplikasi baru yang dianalisis dalam Tesis ini adalah proses overloading. Proses overloading merupakan proses penyisipan kode overloading ke dalam kode CDMA. Penerapannya dapat dalam bidang militer yang bertujuan untuk mengganggu sistem komunikasi pihak lawan. Secara umum efek yang ditimbulkan oleh chaos codes sebagai overloading codes terhadap OVSF lebih besar bila dibandingkan dengan gold codes. Kinerja chaos codes yang ditransmisikan ke dalam sistem OVSF masih tetap memiliki kinerja yang baik dan secara umum masih lebih baik bila dibandingkan dengan gold codes. Untuk delapan user pada aplikasi spreading saat Eb/No 10 dB, nilai BER untuk OVSF dan gold codes 5 x 10-6, chaos codes 2 x 10-4, sedangkan m-sequence 9 x 10-4. Sebagai scrambler untuk delapan user dengan panjang kode 16, untuk mencapai nilai BER 3 x 10-2 gold codes memerlukan Eb/No 5 dB, dan chaos codes memerlukan Eb/No 4 dB. Dalam proses overloading, untuk panjang kode 128 dengan empat user, saat Eb/No 10 dB sebelum disisipi dengan overloading codes OVSF memiliki nilai BER 3 x 10-6. Setelah disisipi dengan chaos codes BER-nya menjadi 3 x 10-4, dan setelah disisipi dengan gold codes BER-nya 2 x 10-4. Nilai BER chaos codes yang ditransmisikan 1 x 10-5 sedangkan gold codes 4 x 10-5.

Item Type: Thesis (Masters)
Creators:
CreatorsNIMEmail
Wijanto, EddyNIM04920070003UNSPECIFIED
Contributors:
ContributionContributorsNIDN/NIDKEmail
Thesis advisorMartoyo, IhanNIDN0318057301UNSPECIFIED
Thesis advisorKanalebe, Herman YacobNIDN8887640017UNSPECIFIED
Additional Information: T 49-07 WIJ c
Uncontrolled Keywords: Chaos codes ; logistic map ; m-sequence ; gold codes ; OVSF ; CDMA ; AWGN ; multipath ; scrambling ; overloading
Subjects: T Technology > TK Electrical engineering. Electronics Nuclear engineering
Divisions: University Subject > Historic > Faculty/School > Department of Master of Electrical Engineering Program
Historic > Faculty/School > Department of Master of Electrical Engineering Program
Depositing User: Phillips Iman Heri Wahyudi
Date Deposited: 14 Dec 2021 02:12
Last Modified: 16 Dec 2021 06:59
URI: http://repository.uph.edu/id/eprint/43776

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