ABSTRAKSI: Teknik Spread Spectrum banyak digunakan pita frekuensi Industrial, Scientific, and Medical (ISM band) yang terletak pada rentang frekuensi 2.402 – 2.480 GHz. Metode spread spectrum yang digunakan antara lain Direct Sequence dan Frequency Hopping dimana keduanya bertugas untuk menangani kondisi kanal buruk baik akibat fluktuasi kanal maupun interferensi. Sistem non collaborative coexistence mechanism tidak memungkinkan adanya komunikasi untuk berkoordinasi antara sistem yang saling berinterferensi. Salah satu metodenya adalah Adaptive Frequency Hopping (AFH) yang merupakan modifikasi dari Frequency Hopping Spread Spectrum (FH-SS). Keadaptifan AFH tersebut membuat sistem tidak menggunakan frekuensi pembawa yang terkena kanal buruk tetapi berpindah ke frekuensi pembawa lain sehingga diharapkan dapat meningkatkan performansi dan throughput dalam menghadapi kanal buruk.
Pada tugas akhir ini telah dilakukan simulasi untuk meneliti penerapan sistem Non Collaborative Coexistence Mechanism Adaptive Frequency Hopping (AFH) pada pita frekuensi ISM yang dilengkapi dengan Hybrid ARQ – FEC selective repeat sebagai teknik retransmisi paket untuk data rate 64 Kbps, 384 Kbps dan 2 Mbps. Penginterferensi yang digunakan adalah WLAN, Bluetooth, dan Cordless Device. Penelitian ini membandingkan performansi sistem berbasis AFH dan Fixed Frequency Hopping (FFH) seperti probabilitas blocking dan ukuran antrian untuk tiap trafik rata-rata. Simulasi dilakukan pada kanal AWGN dan Rayleigh multipath fading menggunakan software Matlab 7.
Hasil simulasi menunjukkan bahwa penerapan sistem non collaborative coexistence mechanism adaptive frequency hopping lebih efektif daripada sistem fixed frequency hopping dalam menurunkan jumlah ukuran antrian dan probabilitas blocking. Ukuran antrian dapat direduksi oleh sistem AFH hingga hanya menggunakan ≈ 1/6 – 1/3 kapasitas maksimum buffer pada trafik pengamatan 1 Erlang. Kemampuan sistem AFH juga dapat menurunkan probabilitas blocking hingga ≈ 0.1 – 0.2 atau ≈ 10% - 20% pada trafik pengamatan 2 Erlang.Kata Kunci : ABSTRACT: Industrial, Scientific, and Medical band (ISM Band) located in 2.402 – 2.480 GHz is mostly utilized spread spectrum technique. Spread spectrum types that is commonly used are Direct Sequence Spread Spectrum (DSSS) and Frequency Hopping Spread Spectrum (FHSS). Those methods are used to deal with bad channel occurance that is caused by not only channel fluctuation but also other systems interferences. Communication among interrupted systems on ISM band are not allowed when using non collaborative coexistence mechanism. One of the method is Adaptive Frequency Hopping (AFH) as FHSS modification. AFH adaptability makes system abandon interrupted carrier frequency and move to another frequency that is expected could improve the performance and throughput on dealing with bad channel.
This final assignment has been simulated non collaborative coexistence mechanism adafptive frequency hopping implementation on ISM frequency system that is eqquiped by Hybrid ARQ – FEC selective repeat as a packet retransmission technique on data rate 64 Kbps, 384 Kbps, and 2 Mbps. Intruder systems are WiFi, Bluetooth, and Cordless Device. This research compares the Adaptive Frequency Hopping (AFH) and Fixed Frequency Hopping (FFH) system performance in terms of blocking probability and queuing size for each traffic observation. The system has been simulated on AWGN and Rayleigh multipath fading channel using Matlab 7 software.
Simulation result shows that non collaborative coexistence mechanism adaptive frequency hopping implementation is more effective compared to fixed frequency hopping in terms of reducing queuing size and blocking probability. AFH system reduces queuing size so the system only uses ≈ 1/6 – 1/3 buffer capacity on 1 Erlang traffic. AFH ability could decreases blocking probability up to ≈ 0.1 – 0.2 atau ≈ 10% - 20% on 2 Erlang traffic.Keyword: