Download - Kapasitas Kanal pada Sistem CDMA
-
7/27/2019 Kapasitas Kanal pada Sistem CDMA
1/16
Perhitungan Kapasitas Kanal
Pada Sistem CDMA
Arif Hidayat ST
-
7/27/2019 Kapasitas Kanal pada Sistem CDMA
2/16
Overview System CDMA
Kapasitas System CDMA tergantung dari
bayaknya interferensi dari system tersebut
Untuk memaksimalkan kapasitas dari
system CDMA perlu dilakukan pengaturanpower dan mengurangi interferensi
system.
Bloking pada sistem CDMA terjadi ketikatotal interferensy melebihi Noise
-
7/27/2019 Kapasitas Kanal pada Sistem CDMA
3/16
Persamaan Energy Per Bit
Assuming:
P denotes the received power from each subscriber at the basestation antenna
R denotes the data rate (9600 bps for Rate Set 1, 14400 bps for RateSet 2)
Power control is perfect
Subscribers are transmitting just enough power to be received
Uniform subscriber distribution
-
7/27/2019 Kapasitas Kanal pada Sistem CDMA
4/16
Interferensi Total
W=Bandwidth of the channel N = Jumlah User (Kanal N)
-
7/27/2019 Kapasitas Kanal pada Sistem CDMA
5/16
Energi Bit dibanding Noise
Jika dilakukan perbandingan Energi Bit
dibandingkan dengan Noise di dapat :
Pendekatan
-
7/27/2019 Kapasitas Kanal pada Sistem CDMA
6/16
Perhitungan Level Interferensi
Persamaan di atas adalah pada kondisi
ideal
Pada aplikasinya terdapat interferensi
yang didapat dari cell lain sehingga didapat persamaan
-
7/27/2019 Kapasitas Kanal pada Sistem CDMA
7/16
Perhitungan level Interferensi
Io = Interference power density impacted by
other cells, and the number of users withan average voice or data activity rate
f = Ratio of out of cell (inter-cell) interference
power to in cell (intra-cell) interferencepower. This factor is used to adjust the
capacity of a single cell to account for the
Interference generated by other users in a multiple
cell system.
=Average voice or data activity factor
=Thermal noise
-
7/27/2019 Kapasitas Kanal pada Sistem CDMA
8/16
Perhitungan Level Interferensi
Sehingga Persamaan Total Energi Bit
dibanding dengan nilai Interferensimenjadi
Dengan melakukan pendekatan di dapat
-
7/27/2019 Kapasitas Kanal pada Sistem CDMA
9/16
Perhitungan Jumlah Kanal
Pendekatan Nilai N
-
7/27/2019 Kapasitas Kanal pada Sistem CDMA
10/16
Kapasitas Kanal Reverse Persamaan Kapasitas Kanal Reverse
Io= Total received signal
No=Thermal noise power
Eb=Energy per bit
Ratio of Signal energy bit to the sum of interference and noiseadjusted fo imperfect power control
W = Bandwidth of the channel
-
7/27/2019 Kapasitas Kanal pada Sistem CDMA
11/16
Kapasitas Kanal Reverse Lanjutan
R =Data rate
W /R =Processing gainf= Ratio of out of cell (inter-cell) interference
power to in cell (intra-cell) interference power.
This factor is used to adjust the capacity of asingle cell to account for the interferencegenerated by other users in a multiple cellsystem.
=Average voice or data
Gs = Sectorization gain
-
7/27/2019 Kapasitas Kanal pada Sistem CDMA
12/16
Adjusted Eb/Io The adjusted Eb/(No+Io) requirement to account
for imperfect power control (power controldeviation) can be determined by:
Signal / (Interference plus noise) ratiorequirement under perfect power control
Standard deviation in imperfect powercontrol
Constant value equal to ln(10)/10
-
7/27/2019 Kapasitas Kanal pada Sistem CDMA
13/16
Rasio Power Intra dan Inter Cell
Some reverse link pole equations may use
the term F, where F is defined as the ratioof in cell (intra-cell) interference power to
the sum of out of cell (inter-cell)
interference power and in cell (intra-cell)
interference power. F is related to f by the
following equation.
-
7/27/2019 Kapasitas Kanal pada Sistem CDMA
14/16
Referse N Capacity Final Persamaan Referse N Capacity Final
Assuming the following values for the various parameters, the reverse link polecapacity for an IS-95 Rate Set 2 site would be 19 users or roughly 12.3
Erlangs per sector (assuming an Erlang B model with 2% grade of service)for a three sector site (57 users per site). This value represents the polecapacity or the point at which no more users can be added without seriouslydegrading the quality of the system.
= Bandwidth of the channel (only one CDMA Channel) 1228800 Hz
= Data rate 14400 bps
= Ratio of out of cell (inter-cell) interference power to in cell 0.7= Average voice or data activity factor 0.4
-
7/27/2019 Kapasitas Kanal pada Sistem CDMA
15/16
Referse Pole Capacity Calculation
=Sectorization gain per sector for a three
sector site 2.4/3
= Signal / (Interference plus noise) ratio
requirement under perfect power
control 6.5 dB
= Standard deviation in imperfect power
control 2.5= Constant value ln(10)/10
-
7/27/2019 Kapasitas Kanal pada Sistem CDMA
16/16
Reverse Pole Capacity Lanjutan