ANALISIS DAN SIMULASI KAPASITAS DEDICATED CHANNEL SISTEM WCDMA DENGAN HSDPA

ABSTRAKSI: Untuk mengikuti perkembangan atas permintaan aplikasi mobile masa depan, 3GPP mempunyai target untuk meningkatkan rata-rata paket data downlink dalam berbagai tingkatan. Sebagai hasilnya, spesifikasi WCDMA telah disusun dengan fitur HSDPA release 5. Sasaran dari HSDPA adalah meningkatkan kapasitas sistem dengan meningkatkan data rate dan mengurangi delay. Peningkatan kapasitas sistem bisa didapat dengan sharing untuk resource code secara dinamis dan power yang ditentukan. Dalam skenario implementasi teknologi HSDPA, ada kemungkinan beberapa sel telah mengimplementasi HSDPA dan sebagiannya belum diterapkan. Apa yang akan terjadi pada sel-sel yang belum menerapkan HSDPA? Ketika HSDPA diimplementasikan pada suatu sel, base station akan menyerap power lebih, sehingga memberikan efek interferensi pada sel-sel yang bersebelahan, yang akhirnya mempengaruhi kapasitas dedicated channel. Untuk power yang lebih tinngi, jika ketersediaan data dalam kanal HSDPA bervariasi, maka efek interferensi pada sel yang bersebelahan akan membesar dan berfluktuasi, sehingga mempengaruhi kapasitas dedicated channel sel-sel tersebut. Penurunan kapasitas dedicated channel akan menonjol jika trafik data HSDPA lebih besar. Data dalam kanal HSDPA yang berfluktuasi tidak menurunkan kapasitas lebih jauh. Hanyalah penerapan power yang lebih yang akan kapasitas dedicated channel. Dalam beberapa kasus, variasinya bisa diabaikan. Dengan perhitungan memakai formula-formula fading rate, power control, interferensi, besarnya SIR, kita bisa mendapatkan besarnya fluktuasi kapasitas sistem dan kualitasnya, serta membandingkannya dengan besaran-besaran referensi. Dari hasil perhitungan didapatkan besar power HSDPA sebesar 12,56 Watt dan dari hasil perhitungan memakai formula interferensi didapatkan nilai SIR sebesar -9,158 dB.Kata Kunci : WCDMA, HSDPA release 5, dedicated channel, base station, resource code, downlink.ABSTRACT: Keeping an eye on the future upcoming demands for mobile applications, 3GPP has the target to enhance the downlink packet data rate in many folds. As a result, WCDMA specifcations have been evolved with the addition of a new feature called HSDPA (High Speed Downlink Packet Access) in Release 5. The goal of HSDPA has been to increase the system capacity by increasing the data rate and reduce the round trip delay. The increase of system capacity has been achieved by dynamic sharing of code resource and certain amount of power. However, in a real deployment scenario, it may happen that some of the cells are implemented with HSDPA and some are not yet; what will happen to the capacity of those cells without HSDPA? When HSDPA is implemented in a cell, the base station uses more power, imparting more interference to the neighbouring cells, thus affecting their dedicated channel capacity. In addition to the higher power, if the availability of data in the HSDPA channel varies, then the interference to the neighbouring cell might be larger and fluctuating, in turn, the dedicated channel capacity of the neighbouring cells might be affected. It has been found that the decrease in the dedicated channel capacity is more if the HSDPA data traffc is larger. The fluctuating data in HSDPA channel has not degraded the capacity further; it is only the higher power, which has affected the dedicated channel capacity. However, in all these cases, variation can be considered as negligible. We can use various formulas such as fading rate, power control, interference system and SIR, we can calculate some fluctuations in system capacity and quality, then we can compare it with reference system. From calculation method, it is gained that HSDPA power for system model is 12,56 Watt and with using interference formula, the SIR calculation result is -9,158 dB.Keyword: High Speed Downlink Packet Access (HSDPA), 3rd Generation Partnership Project (3GPP)