ABSTRAKSI: Salah satu pengembangan dari sistem W-CDMA adalah pada bagian receiver. Receiver untuk sistem multiuser terdiri dari receiver optimal dan sub optimal. Receiver optimal sangat kompleks, sehingga dikembangkan receiver sub optimal yang memiliki kinerja mendekati receiver optimal tetapi dengan kompleksitas yang tidak terlalu tinggi.
Successive Interference Cancellation (SIC) merupakan algoritma yang diterapkan pada receiver sub optimal. Receiver dengan algoritma SIC akan mendeteksi semua user satu persatu. Pada bagian ini dilakukan proses cancellation, yaitu menghilangkan efek sinyal user yang terdeteksi sebelumnya dari semua sinyal terima untuk mengurangi kompleksitas sinyal- sinyal lain yang masih tersisa. Dalam tugas akhir ini, performansi diamati dalam sistem single user, dua user dan tiga user. Analisa juga membandingkan performansi system konvensional dan system yang menggunakan algoritma SIC.
Hasil simulasi pada sistem single user menunjukkan bahwa performansinya sangat bergantung pada kondisi kanal yang dimodelkan. Pemodelan kanal bergantung pada besarnya relative mean power dan relative delay setiap tap. Performansi terbaik terjadi pada speed 50 Km/h, target BER tercapai di SNR -8.91 dB. Sistem tiga user speed 50 Km/h dengan SIC mampu memberikan perbaikan sebesar 66.67 % pada SNR 7 dB. Pada sistem dengan SIC, pencapaian BER 10-3 pada sistem dua user adalah di SNR + (-3.48) dB. Pencapaian BER 10-3 pada system tiga user adalah di SNR + 1.18 dB. Pertambahan jumlah user aktif akan mempengaruhi performansi sistem baik sistem konvensional maupun sistem dengan algoritma SIC
Kata Kunci : WCDMA, Successive Interference Cancellation. CancellationABSTRACT: One of W-CDMA system development is in receiver. Multiuser system receivers consist of optimal receiver and sub optimal receiver. Optimal receiver is very complex. Thus the development is conducted to find sub optimal receiver which its performance approaches optimal receiver but the complexity is lower than it.
Successive Interference Cancellation (SIC) is an algorithm that used in sub optimal receiver. Receiver with SIC algorithm will detect all users one by one. There is cancellation process, that cancel signal effect of the first detected signal from all received signals and substract the complexity of the user that will be detected next. In this final research. The performance of W-CDMA is analyzed single-user, twouser, three-user systems. This also analyzes the performance comparation between conventional and system with SIC algorithm.
Simulation results show that the condition of modeled channel influence the performance of single-user system. Meanwhile, the condition of modeled channel depends on relative mean power and relative delay of each tap in channel. The best performance of single user system is occurred in speed 50 Km/h, BER target is achieved at -8.91 dB. Three-user system with SIC gives 66.67% BER improvement at 7 dB SNR. In two-user system with SIC, the 10-3 BER is achieved at SNR + (-3.48) dB while in three-user system with SIC, it is achieved at SNR + 1.18 dB. The increasing of active users will effect the performance of conventional system and system with SIC algorithm.
Keyword: W-CDMA, Successive Interference Cancellation, Cancellation