ABSTRAKSI: Indonesia merupakan daerah rawan bencana yang bisa mengakibatkan jaringan Global System for Mobile Communication (GSM) di daerah tersebut mengalami kerusakan. Oleh karena itu, dibutuhkan sebuah layanan GSM dengan investasi yang kecil dan instalasi yang mudah untuk menanggulangi dua masalah tersebut. Open Base Transceiver Station (OpenBTS) adalah salah satu opsi yang dapat digunakan. Tidak hanya dapat terkoneksi dengan jaringan seluler eksisting, OpenBTS juga mampu berdiri sendiri sebagai private network.
Pada penelitian Tugas Akhir ini dibuat rancang bangun coverage area OpenBTS di lingkungan kampus Institut Teknologi Telkom. Terdapat dua tahap, yaitu rancang bangun kapasitas dan rancang bangun coverage. Pada penelitian ini terdapat dua skenario perancangan, yaitu distribusi pengguna seimbang dan distribusi tidak seimbang. Keduanya menggunakan tiga kondisi, yaitu low-rate (rasio pengguna aktif dan idle 0,1), normal (0,1183), dan high-rate (0,2). Rancang bangun kapasitas menghasilkan nilai radius sel dan jumlah sel. Pada tahap kedua dilakukan perhitungan radio link budget sesuai standar availability layanan di tepi sel (disebut juga probabilitas cakupan di tepi sel) dan simulasi untuk mendapatkan nilai rata-rata Receive Signal Level (RSL). Model propagasi yang digunakan adalah COST-Hata dan band frekuensi DCS 1800 MHz. Software Atoll 2.8.1 digunakan untuk simulasi perancangan agar mendapatkan nilai rata-rata RSL.
Jumlah sel yang dibutuhkan untuk mencakup lingkungan kampus Institut Teknologi Telkom sesuai hasil rancang bangun pada tahun 2012 didapatkan berkisar antara 10-20 sel. Radius sel antara 58,23-107,73 meter. Maximum path loss didapatkan antara 93,27 dB s.d. 100,75 dB. Adapun besar Maximum Allowable Path Loss (MAPL) sesuai standar availability layanan di tepi sel didapatkan sebesar 99,9223 dB. Daya pancar maksimal base station di semua kondisi adalah 9,54 dBm atau berada di bawah kemampuan maksimum daya pancar OpenBTS, yaitu 20 dBm. Nilai rata-rata RSL berdasarkan hasil simulasi didapatkan antara -89,35 dBm s.d. -83,05 dBm. Seluruh kondisi kecuali kondisi low-rate distribusi tidak seimbang memenuhi standar nilai availability 75%. Sedangkan, kondisi low-rate distribusi tidak seimbang sendiri hanya mencapai 72%, sehingga tidak memenuhi standar availability layanan di tepi sel.Kata Kunci : coverage area, GSM, atoll, OpenBTS, availability layanan di tepi selABSTRACT: Indonesia is a disaster sensitive area that can cause the Global System for Mobile Communication (GSM) service damaged. Therefore, a low cost and easy install GSM service is needed to overcome these issues. Open Base Transceiver Station (OpenBTS) is one of the option that can be used. Not only can connected to existing cellular network, OpenBTS can also stand alone as a private network.
In this final project study, OpenBTS coverage area design on Institut Teknologi Telkom campus area made consists of two phases; capacity design and coverage design. There are two design scenarios in this final project, namely balanced user distribution and unbalanced user distribution. Both of them use three conditions, low-rate (the ratio of active and idle users is 0,1), normal (0,1183), and high-rate (0,2). Capacity design produces the cell radius value and the number of cells. The second phase consists of radio link budget calculation based on service availability at the cell-edge standard (also called coverage probability at the cell-edge) and simulation to obtain the average value of Receive Signal Level (RSL). The propagation model used is COST-Hata and the frequency band is DCS 1800 MHz. Atoll 2.8.1 software is used to simulate the design in order to obtain the average value of RSL.
The number of cells needed to cover Institut Teknologi Telkom campus area according to the result of the design is obtained between 10-20 cells. Cell radius between 58.23 to 107.73 meters. Maximum path loss is obtained between 93.27 dB to 100.75 dB. As for the Maximum Allowable Path Loss (MAPL) based on service availability at the cell-edge standard is obtained 99.9223 dB. Maximum base station transmit power of all conditions is 9.54 dBm or below the maximum transmit power capability of OpenBTS, which is 20 dBm. The average value of RSL based on simulation results is obtained between -89.35 dBm to -85.03 dBm. All conditions except low-rate of unbalanced user distribution condition meet the 75% availability standard. While, low-rate of unbalanced user distribution condition itself only achieves 72%, so it does not meet the service availability at the cell-edge standard.Keyword: coverage area, GSM, atoll, OpenBTS, service availability at the cell-edge